WO1993005348A1

WO1993005348A1 - Vacuum panel heat exchangers (vphe)

Info

Publication number: WO1993005348A1
Application number: PCT/AU1992/000464
Authority: WO
Inventors: Robert Kenneth Prudhoe
Original assignee: Robert Kenneth Prudhoe
Priority date: 1991-08-30
Filing date: 1992-08-31
Publication date: 1993-03-18

Abstract

A typical heat transfer building panel suitable for use in building and room construction comprising walls defining an enclosure containing a two-phase heat transfer material at such pressure that it may occupy both phases under conditions of temperature differential between opposing evaporator and condenser sections at bottom and top of VPHE panel respectively whereby thermal energy is transferred in one direction only through the panel. Distribution of a suitable liquid phase change material is achieved using a relatively thin liquid reservoir means so that the evaporator section is full of liquid and 100 % wet all the times, or alternatively, the evaporator is wetted using a single or multiple wick system. An inner VPHE supporting structure is constructed to provide surface areas for efficient heat transfer and sufficient strength to maintain its shape under pressure and/or vacuum. The panel whether working under vacuum or positive pressure with respect to atmospheric pressure is generally known as a 'Bi-phase Operated Internal Gas Accumulator Panel'. When the panel operates at a lower than atmospheric pressure it functions as a Vacuum Panel Heat Exchanger (VPHE). One or more evaporator sections may be provided on a common surface in a common VPHE sealed enclosure. The open space of the VPHE has a common condenser surface with one or more means to direct condensate back to one or more of the evaporator fluid reservoirs. The panel functions as a thermo-syphon and all working fluids and fluid/panel construction material compatibilities commonly known and proven for thermo-syphons and/or heat pipes are suitable for application in this invention.

Description

VACUUM PANEL HEAT EXCHANGERS (VPHE)

This invention relates to vacuum panel heat exchanger (VPHE) technology that dramatically improves heat transfer thermal performance. As an example only, panels according to this invention use a thermosyphon technique to either transfer heat from inside a building enclosure to the outside atmosphere or alternatively to transfer heat from the outside atmosphere to the inside of the building enclosure the process of heat transfer depending on the respective location of the VPHE evaporator and condenser surfaces. The VPHE building panel may be used as

an effective method to collect solar energy of the sun for the purpose of hot water and/or space heating. These panels may also be used most effectively for passive cooling of heat emitting enclosures or for general heat exchangers to transfer heat from a heated fluid to a cooler fluid.

The uniquenes of this particular VPHE is the modified internal construction that provides enhanced wetting of the evaporator surface. Its operation and application is generally described as follows:

It has been observed that the thermal performance of a given single wick type VPHE panel in an inclined or vertical configuration is determined by the ability of a suitable wick (for example, sintered copper) to effectively draw up and evenly distribute a suitable two- phase heat transfer material such as a working fluid over the evaporator to a given height by capiiliary action and thereby provide a sufficient flow of liquid and effective wetting of the evaporator plate. In this regard the

practical size and height of a given VPHE panel is

determined by the ability of the wick to raise the level of the working fluid , for example sintered copper may raise the liquid with a sufficient flow to say 20 inches height, however above this height the evaporator will not be effective. Under such circumstances it would be of no practical use to make the VPHE panel higher than 20 inches. An appropriate internal VPHE structure that could enable a single stage wick evaporator to be replaced with a more effective wetting system would have considerable merit. For example, a 100% wet evaporator on a vertical or inclined wall or surface without the need for a wick would be a major improvement because the VPHE will be much more effective m its thermal operation and more simple in its construction, with savings in construction cost and improvement in thermal efficiency.

The use of a suitable multi-stage wick would also be a dramatic improvement when compared to a single stage wick. It is the principle objective of this invention to provide a system of VPHE internal structure that will provide enhanced wetting of the evaporator when compared to a single stage wick system. Methods to achieve this principle objective in accordance with this invention are to use a single stage or multi-stage wickless evaporator or alternatively, to utilise a multi-stage evaporator that comprises a plurality of wicks depending into respective liquid resevoirs with apporopriate liquid return means from a common condenser wall that returns the condensate to the respective wicks and fluid resevoirs. A multistage wickless evaporator or multi-stage wick evaporator will enable a single VPHE building panel to be made much higher with better thermal performance and enhanced wetting of the evaporator when compared to a VPHE with a single stage wick evaporator.

A single stage or multi-stage wickless VPHE would have a number of advantages when compared to a VPHE that utilises a single wick to wet the evaporator, for example: larger and taller VPHE panels can be constructed with evenly distributed heat transfer performance and consequent savings in construction cost when compared to the cost of a number of smaller wick type VPHE panels to do the same job.

The operation of the improved evaporator will now be described with reference to the accompanying drawings and embodiements:

Fig. 1. shows the known type of vertical VPHE building heat transfer panel that may be mounted in the wall or inclined ceiling of a building. This VPHE uses a vertical wick to wet the evaporator ; Fig. 2 shows a wickless VPHE building panel in accordance with this invention where a specific internal structure provides a single stage wickless VPHE that will give an enhanced thermal performance when compared to the VPHE unit in Fig. 1.;

Fig. 2A shows an example of a suitable inner support structure that can fit inside the VPHE panel shown in Fig.2;

Fig. 3. shows a modification to the VPHE of Fig.2 which provides for a multi-stage evaporator on a common evaporator surface and common condenser that may be installed in a vertical or inclined wall or ceiling of a building enclosure to provide a passive cooling or solar heating panel depending on specific location of the

evaporator and condenser sections;

Fig.4. shows a view of a building enclosure which is subject to passivce solar heating using ceiling mounted and/or vertical wall mounted VPHE panels in conjunction with suitable translucence screens to reduce heat loss from cool winds in combination with asuitable adjustable louvre system and/or roller blind system or other suitable means to reduce heat gain from the VPHE in summer time when heating of the building enclosure is not needed;

Fig.5. shows VPHE panel units in combination with a hot water heat exchanger manufactured and installed in accordance with this invention for the purpose of solar hot water heating;

Fig. 6 shows VPHE panels in accordance with this invention installed in the vertical wall and inclined roof of a

building for the purpose of solar space heating of the enclosure. In this instance the VPHE panels are installed so that the evaporator and condenser units are off-set from the roof and wall surfaces, thus doubling evaporator and condenser effective surface area, to dramatically increase heat transfer thermal performance compared to single sided evaporator and condenser units ;

Fig. 7 shows yet another illustration of VPHE panels

manufactured and installed in accordance with this

invention where the VPHE is configured as a special type of thermal diode building roof and wall tile for the purpose of providing a novel type of VPHE passive cooling system for electronic equipment enclosures. VPHE tiles are shown in combination with Phase Change Material (PCM) building bricks to help provide thermal stability in the equipment room;

Fig. 8. is yet another illustration using VPHE panels in accordance with this invention for passive cooling of heat emitting enclosures. One VPHE panel is shown with an offset from the inclined ceiling with fins as a method to double the VPHE evaporator surface area and some

automatically operated air circulating fans are shown to increase the rate of heat transfer from the heated room air into the VPHE evaporator unit;

Fig. 9. shows a number of flat VPHE units installed in the form of modular panel units for the purpose of passive solar heating of a building enclosure. The VPHE panels go direct through the wall and inclined ceiling where the entire surface area of evaporator and condenser is exposed to provide enhanced thermal performance, in combination with automatically controlled circulating fans and the

PCM thermal energy storage structure; Fig. 10. is similar to Fig. 9 except that the VPHE panels are installed in reverse so that the VPHE panels act in the passive cooling mode to transfer heat from inside the building enclosure to the outside atmosphere which acts as the heat sink;

Fig. 11. shows four flat VPHE tyhermo-syphon panel units installed in a common building construction panel in accordance with this invention that may be used for a multitude of practical purposes;

Fig. 12. shows the building VPHE panel of Fig. 11 installed in an inclined roof structure of a building for the purpose of providing a passive solar heating system to heat the inside of the building enclosure. A translucent screen such as glass or perspex or other suitable solar ray

transmitting material is shown to reduce the heat loss from cool wind. A thermostatically controlled air circulating fan is shown inside the building enclosure to increase heat transfer from the VPHE unit into the room air to provide heating means for the room enclosure;

Fig. 13 shows the same VPHE panel of Fig. 11 and 12 installed in combination with an air to water insulated heat exchanger for the purpose of providing a VPHE solar hot water heating system: Fig. 13 A shows another application of the VPHE modular panel detailed in in Fig. 1 1 , Fig. 12 and Fig. 13 where it may be used as a heat exchanger to transfer heat from a hotter fluid to a cooler fluid;

Fig. 14 shows a single flat type VPHE panel that includes heat transfer fins, a working fluid, an inner support structure and an appropriate valve device to fill the VPHE with an appropriate working fluid and to adjust the internal working pressure as required to satisfy operating conditions of the VPHE;

Fig. 15 is yet another illustration that shows a flat type VPHE panel similar to that in Fig. 14, except that this panel has no heat transfer fins provided;

Fig. 16. shows a typical compatible VPHE inner support structure suitable for the VPHE panels, as described in Fig. 14 and Fig. 15 above.

Fig. 16. A shows another type of inner support structure that may be used for this invention which may be fabricated from a suitable material in a concentena expandable "Vee" shape.

Fig. 16. B shows another type of suitable inner support structure that may be fabricated using a suitable type of mould and suitable material of construction.

Fig. 16. C shows yet another type of inner support structure fabricated in continuous corrugation shape;

Fig.17 shows yet another type of VPHE building construction panels in accordance with this invention in which the evaporator and the condenser units are separate physically, but jointed thermodynamically by inter- connecting hoses and/or welded pipes and vacuum fittings to provide for special types of VPHE heating and/or cooling systems that may be retro-fitted to all types of buildings and/or building enclosures.

As to whether the VPHE system is used for heating or cooling depends on the inter-relationship between the physical positioning of the evaporator and condenser sections. Where solar heating of a building enclosure or hot water is required the evaporator section is located outside exposed to sunlight and the condenser section is located in the cooler building enclosure or cooler water which is to be heated;

Fig. 18 is an illustration of the split system type VPHE units being used for space heating of building enclosures; Fig. 19 is yet another illustration of the

split/system , VPHE units being used for passive solar heating of a multi storey building, each floor having its own dedicated passive heating system;

Fig. 20 is a perspective sectional view of the split/system VPHE units being used for passive solar heating of water.

VPHE evaporator and condenser sections are connected together thermodynamically using a system of vacuum hoses and appropriated vacuum fittings such as, by

way of example, those manufactured by "Swagelok";

Fig. 21 is a perspective view of a three storey building that houses heat emitting electronic equipment and the split- system VPHE units are being used as a means of passive cooling system to transfer heat generated by the electronic equipment within the building enclosure to the outside ambient air. Evaporator units of various configurations are mounted inside the equipment rooms and the heat is

transferred to the external condenser units mounted at a higher level on the outside wall of the building, the

evaporator and condenser units being suitably connected by means of vacuum hoses and fittings of appropriate quality to perform the desired duty;

Fig. 22 shows surface shapes of an e v a p o r a t o r o r a condenser side of a VPHE passive heating and/or cooling

system;

Fig. 23 shows alternative shapes to Fig. 22;

Fig. 24 shows an alternative shape to Fig. 22;

Fig.25 shows yet other alternative shapes to Fig. 22 Fig. 26 illustrates a novel type of VPHE roof tile passive solar heating installation in accordance with this invention. The VPHE tiles in this instance are

manufactured in flat plate configuration and may have heat conducting fins if so desired to increase the surface area and the amount of solar heat absorbed by the tile;

Fig. 27 shows a method of manufacture of a VPHE in accordance with this invention that provides for a

number of evaporator/condenser tubes to interconnect into a common manifold at each end that provides that all tubes can operator under a common vacuum and/or pressure;

Fig.28 shows a method of constructing a VPHE in accordance with this invention where a triangular "Vee" shape formed sheet is used in combination with a flat

sheet; Fig.29 is similar to Fig. 27 except that two opposing corrugated shets are effectively jointed together to form the vacuum seal of the VPHE;

Fig. 30 shows yet another method of VPHE

construction using one flat sheet located mid way between two opposing corrugated sheets;

Fig. 31 shows a method of manufacture of a VPHE using one flat sheet which is vacuum sealed to a corrugated sheet;

Fig. 32 (a) and (b) show : (a) method of VPHE manufacture using a flat sheet located between two opposing square section or rectangle sheets; and (b) one flat sheet located between two opposing :Vee" shape sheets;

Fig. 33 shows a method of solar heating of water for a swimming pool in accordance with this invention;

Fig. 34 shows a method of solar heating of a building enclosure use a VPHE constructed from a pipe system into common end manifolds in accordance with this invention;

Fig. 35 shows a a double chamber VPHE in accordance with this invention; and

Fig. 36 shows a multiple chamber VPHE in accordance with this invention that uses a plurality of liquid resevoir means operating in conjunction with a plurality of liquid condensate means to return the

condensate to its respective liquid resevoir means.

To those conversant in the art it will be well appreciated that this invention also applies to improvements of a single VPHE wick system up a vertical or inclined wall

into a multiple wick system against a common evaporator wall. It has been observed that the thermal performance of a given VPHE panel in an inclined or vertical

configuration is determined by the ability of a suitable wick (for example, sintered copper) to effectively draw up and evenly distribute a suitable two-phase heat transfer material such as a working fluid over the evaporator to a given height by capilliary action and thereby provide a sufficient flow of liquid and effective wetting of the

evaporator plate. In this regard the practical size and height of a given VPHE panel is determined by the ability of the wick to raise the level of the working fluid , for example sintered copper may raise the liquid with a sufficient flow to say 20" height, however above this height the evaporator will not be effective. Under such circumstances it would be of no practical use to make the VPHE panel higher than 20 inches.

An internal heat pipe structure that could enable the inner wick system of an evaporator panel to work for much greater heights would have considerable merit when compared to the existing known single stage wick system. Additionally, a wet evaporator on a vertical or inclined wall or surface without the need for a wick would be a major improvement.

It is the principle objective of this invention to provide an internal VPHE structure that will enable the evaporator to have a multi-stage wick and/or wickless system that will enable the evaporator and VPHE panel to be made much higher with better thermal performance and more even wetting than using a single stage wick.

A multi-stage wick would have a number of advantages when compared to a single stage wick: larger and taller VPHE panels can be constructed with evenly

distributed heat transfer performance and consequent savings in construction cost when compared to the cost of a number of smaller panels that use a single wick to do the same job.

The operation of the improved evaporator wick system will now be described with reference to the accompanying drawings and embodiements:

Fig. 1. shows a vertical VPHE panel;

Fig. 37 shows the VPHE panel shown in Fig. 1 with the addition of an internal structure that provides a multi/stage wick that will provide an enhanced thermal performance;

Fig. 38. shows VPHE panels with multi-stage wicks installed as a passive cooling system where the VPHE panels are installed as part of the wall and inclined roof structure of a building which houses heat generating electronic equipment;

Fig. 39 shows the VPHE panel with a multi-stage wick in combination with a heat exchanger that may be used for the purpose of solar hot air or hot water heating;

Fig. 40. shows yet another application of the multi-stage wick VPHE installed in the wall or inclined roof of a building for the purpose of direct solar heating of the building in the winter time; Fig. 41 shows a number of VPHE panels in

combination with a phase change material thermal store for passive cooling of an electronic equipment room;

Fig. 42 shows a number of VPHE panels in combination with a phase change material (PCM) thermal store and the sun's radiant energy for passive solar

heating of a building enclosure;

Fig. 43 shows a VPHE panel in combination with a heat exchanger, a parobolic reflector and the sun for solar

heating of a fluid such as water or air passing through the heat exchanger;

Fig. 44 shows a further embodiement of a VPHE panel including a resevoir arrangement which distributes the working fluid over the internal evaporator surface of the panel;

Fig. 45 shows a cross section of a support that could be positioned inside an evaporator fluid resevoir of one of the lower evaporator sections shown in Fig. 44 ;

Fig. 46 is a perspective view that shows how the inner support structure fits into the evaporator fluid resevoir;

Fig. 47 shows a perspective view of a building enclosure incorporating wall panels for the purpose of solar space heating according to the invention;

Fig. 48 shows a section view of a wall panel according to the invention;

Fig.49 shows a panel being used as a solar energy collection device for the specific purpose of heating water;

Fig. 50 shows two panels one fixed and the other that can rotate for temperature control of an

enclosure;

Fig. 51 shows a panel being used as an air

heating and a thermal energy storage system.

Fig. 52 shows a lower first side of a panel

Fig. 53 shows an alternative shape to Fig. 52

Fig. 54 shows an alternative shape to Fig. 52

Fig.55 shows yet another alternative shape to Fig. 52

Fig. 1. shows the known type of VPHE 1 , that can be used for vertical or inclined mounting in a wall or

roof of a building to either transfer heat out of a building enclosure to the cooler exterior or alternatively such panel could be used to collect solar energy on the evaporator face 2, and transfer heat into a building enclosure. The inner space 3, of the VPHE is subject to a given internal vacuum pressure that controls the temperature at which the fluid 5, boils. The wick 4, acts as a capilliary to draw the working fluid up from the fluid resevoir 5, whereupon boiling the vapour formed will fill up the entire inner space 3, and condense evenly on the condenser surface 6, providing the temperature of the condenser is below the condensation temperature of the vapour within the VPHE.

The performance of this type of VPHE panel will depend on the ability of the wick 4, to draw up by capilliary action the working fruid from the fluid resevoir 5. The vertical height of the panel in such a configuration will be restricted using a single wick by the ability of the wick to effectively raise the working fluid.

Fig. 2 shows a perspective sectional view of a VPHE panel 10, manufactured and installed in accordance with this invention. The VPHE 10, rather than being straight and vertical as shown by the wick type VPHE panel in Fig.1 , has a step section or a dog leg 11 , whereby

the 100% liquid filled evaporator 12, filled with

appropriate working fluid 13, is

installed on the hotter side of the insulated building wall section 15.

The VPHE has an adjusting valve 16, by which the internal pressure of the VPHE may be adjusted by a suitable means such as bleeding off to increase pressure or by using a vacuum pump to reduce pressure in accordance with the specific operating conditions of the VPHE. Another vacuum tight valve 17, has been shown as means to fill the VPHE with an appropriate amount of working fluid 13, as required.

The VPHE houses inside an inner support structure to prevent the panel from collapsing when the

vacuum is pulled on the panel Such structure is designed to adequately support the VPHE 10, and the material of

construction must be compatible with the choosen VPHE working fluid.

The design of inner support structure must be such as to maximise heat transfer and provide an even distribution of liquid in the evaporator and/or even

distribution of vapour in the condenser section.

Fig. 2A shows by way of example a suitable inner support structure that could fit inside the VPHE panel described in Fig.2. A number of support legs 21 , are shown to fit close inside the VPHE panel and prevent the VPHE from collapsing when a sufficient vacuum is pulled. The number of support legs 21 , is determined by the length of the panel and the space between legs is determined by the amount of support required which in turn depends on the degree of vacuum pulled.

A number of holes 22, of suitable size are shown drilled into each support leg to enable an even distribution of liquid in the evaporator section combined with an even distribution of vapour in the condenser section.. The space between each inner support leg is adjusted simply using a common screwed rod 23, with sleeves 24, of a slightly larger diameter cut to an appropriate length to suit the VPHE design and working pressure as required.

The materials of construction of the inner support structure must be compatible with the working fluid and the materials of construction of the VPHE and valve fittings .

Fig. 3 shows a VPHE panel 30, in accordance with this invention. This panel is similar to that in Fig.2, except that it has a primary liquid resevoir31 , and two secondary liquid resevoirs 32 and 33 on a common

evaporator surface 34, with a plurality of liquid return means 35. 36 and 37 to return the liquid condensate from the surface of the common condenser wall 38, to the respective liquid resevoirs adjacent to the common evaporator wall 34.

This variation means that a much higher VPHE panel with a common open inner chamber 39, and common evaporator and condenser walls can be fabricated as part of a building wall or ceiling section.

A valve 40, is shown as means to adjust the pressure in the panel and another valve 41 , is provided as means to fill the VPHE with working fluid whilst valve or drain cock 42, is provided to drain the panel of working fluid for the purposes of maintenance or to change the working fluid.

Fig. 4 shows VPHE panels 50, 51 , 52, 53, 54, 55, and 56 constructed and installed in accordance with this invention for the purpose of solar space heating of the building enclosure. VPHE panels 50, 51 and 52 are located in the inclined roof to collect the solar radiation and direct the heat directly into the building enclosure 57. VPHE units 50 and 51 are of similar construction to those outlined in Fig. 2 whilst VPHE panel 52 has a multi stage evaporator unit and ϊs similar in construction to the panel outlined in Fig. 3.

A translucent shield 58, is provided to reduce heat loss from cool wind and a system of adjustable louvre 59 is shown to prevent the system from operating during warm to hot weather when solar space heating is not required.

Provision is also made in this invention to reduce the VPHE internal pressure in hot weather using the pressure

adjusting valve to render the system inoperative. This invention also has provision to connect together pressure- wise ail VPHE panels of the entire system so that the internal pressure of all panels may be adjusted

simultaneously to any desired pressure using a suitable vacuum pump and/or bleed of system and automatic pressure sensing and regulating system.

VPHE panels 53, 54, 55 and 56 are shown mounted in the vertical wall 60 of the room 57. VPHE panels 53, 54 and 56 have only one liquid resevoir evaporator being similar to panels illustrated in Fig. 2 whilst VPHE panel 55 has a primary evaporator and two secondary evaporators being similar to panel 52, in the ceiling or the panel construction shown in Fig.3.

VPHE units 53, 54, 55 and 56 operate in combination with translucent wind screen 61 and sun louvres 62 and transmit heat from the evaporator section to condenser sections where it is ejected and may be stored in a wall 63 made from special heat absorbing bricks that may contain some phase change material (PCM), the stored heat being released as required to the building enclosure 57, using room thermostat 64, which operates room air circulating fans 65, 66 and 67 and louvre operated fans 68 and 69 to circulate air from the room enclosure 57, into the cavity 70 where it collects stored heat and returns to the room to heat up the enclosure. Some bricks 72, which contain PCM are shown to form the basis of inner wall construction 73 that may store heat and stabilise temperatures in the room about the phase change temperature of the PCM selected for the specific application. Fig. 5 shows yet another application of the VPHE panels similar to those outlined in Fig. 2. In this application VPHE panels 80, 81 and 82 are located on a common panel unit 83, and mounted in an inclined roof 86, of a building and on the condenser side of the VPHE units is fitted an insulated heat exchanger 84 for the purpose of heating the fluid (may be water or air or any other fluid as so desired) that flows through heat exchanger 84.

In this particular application the three VPHE units 80, 81 and 82 are mounted on the common panel and enter the building through the roof space so that the evaporator sections and condenser sections are "off-set" from

respective panel and heat exchanger surfaces so as to provide maximum heat transfer surface area and maximise thermal performance of the unit.. A system of sun louvres or roller blind shutter or other suitable means may be provided to de-activate the system at times when heating of the fluid inside the heat exchanger is not needed.

Fig. 6 shows a number of building panels which contain VPHE units 91 , 92, 93, 94, 95, 96, 97, 98 and 99 in accordance with this invention mounted on panels and fitted into the inclined roof structure and vertical wall for the purpose of providing a solar space heating system to building enclosure 100. In this illustration all VPHE units have their evaporator and condenser sections "off-set" or mounted away from the roof and wall surfaces so as to provide maximum surface area of the evaporator and condenser sections, thus improving thermal heat transfer performance.. Similar to the operation of VPHE panels described in Fig 4., this system also provides for the possibility of translucent wind screens 101 and 102, automatically operated louvre sun shields 103 and 104, provision for internal air circulating fans 105 1 nd 106 and the provision of a high heat density storage wall that has bricks 107 that contain some phase change material. All panels may also be connected together with a common system of valves, connecting hoses and pressure adjustment means to adjust the pressure of the entire system

simultaneously as required by the operating conditions. Fig. 7 shows a building enciosure 120 with internal heat emitting electronic equipment load 121 , and a plurality of VPHE panels 122-130 inclusive installed in the inclined ceiling and in the vertical wall of the equipment room for the purpose of using the VPHE units as a passive cooling system to automatically transmit excess heat from the equipment room to the outside atmosphere at times when there is an excess of heat in the equipment room and when it is sufficently cool enough outside. Sun shields 131 and 132 are shown to reduce solar heat gain to the building enclosure. Circulating fans 131 , 132, and 133 are provided to inprove transfer of heat from within the room to the outside via the VPHE panels. A wall that contains bricks 134, that contain PCM are utilised to stabilise

temperatures within the equipment room enclosure. By careful adjustment of the pressure within the panel the VPHE can be calibrated and sealed to operate or "fire" at any given temperature to suit the desired room set p[oint temperature within the equipment room.

For example, if it is desired to maintain a steady temperature of 30 deg. C within the room, the pressure within VPHE panels is carefully calibrated so that the particular working fluid housed in the VPHE evaporator will boil when the room temperature reaches 30 deg. C and the unwanted room heat will be transferred to the outside providing the ambient temperature is less than 30 deg. C which is also the condensation temperature of the working fluid as well as the boiling temperature.

Fig. 8 is very similar to Fig. 7 except that in Fig. 8 there is one VPHE 150, shown that has its evaporator section off-set from the inclined ceiling surface so as to maximise the exposed surface area of the evaporator to enhance heat transfer.. This particular VPHE is also shown to have heat transfer fins on the evaporator 151 , to improve heat transfer in accordance with the scope of this invention.

Fig.9 shows a VPHE solar space heating system in accordance with this invention that utilises a number of VPHE modular panel units 160, 161 , 162 and 163

manufactured to house fiat type VPHE panels which may be plain or have heat transfer fins 164, 165 and be installed in accordance with this invention. The panel sections 160, 161 , 162 and 163 are added together as required to build up a section of a ceiling or a wall to any physical size

dependant on the amount of heat to be transferred. Translucent wind shields 166 1 nd 167 and air circulating fans 168, 169 and 170 are shown. In this

illustration adjustable sun louvres are also shown on the wall mounted VPHE panels. The VPHE panel system is designed so that modules of flat plate type VPHE's together on a common mounting panel may fit together on inclined roof areas or vertical walls in such a manner so as to provide an airtight and water tight seal between the inner building enclosure and the outer external atmospheric environment. The panels may be bolted, glued or slotted together in all different types of waterproof/airtight techniques which is included in the scope of this invention.

Fig. 10 shows an installation for natural passive cooling of a heat emitting electronic equipment enclosure 190, in accordance with this invention. Two VPHE modular panel units 180 and 181 installed in an inclined roof , contain flat plate type VPHE's in accordance with this invention.

Unit 180 contains three identical flat plate inclined VPHE units 182 while building panel 181 contains

one vertically installed VPHE unit with fins attached 183, one flat plate VPHE without fins 184 and one bent VPHE unit that contains fins 185.

The VPHE units may be manufactured, bent or formed to any desired shape to suit a particular application of heat transfer.

Mounted vertically in the wall is shown three VPHE modular panel units 186, 187, 188. Modular panel unit 186, contains two inclined flat plate VPHE panels, one without fins 189 and one with fins 191. Modular panel unit

187 contains two identical inclined VPHE flat panels.

Modular panel unit 188 contains one bent type VPHE 193 so that top part of the VPHE is inclined with the vertical and the bottom part of the VPHE is vertical.

When electronic equipment load 195, causes the temperature inside room 190 to exceed say 30 deg. C the working fluid in all VPHE panels will boil and the vapour will fill up the entire panels to condense on the VPHE surface area (condenser) which is located in the outside atmosphere, providing the outside temperature is less than the condensation temperature of the VPHE working fluid..

Thermostat 196 is provided to automatically turn on circulating fans 197 and 198 to improve heat

transfer when required. A solar screen 199 is provided over the roof mounted VPHE modular panel units to reduce solar heat gain to the building enclosure.

Fig 11 shows another type of VPHE modular panel unit 210 manufactured in accordance with this invention which may be used to form a solar space heating panel mounted on an inclined roof of a building or may be modified to embody a heat exchnager section that may be used for the purpose of heating hot water, air or any other

desired fluid.

VPHE modular panel 210 contains four identical flat type inclined VPHE panels 211 , rigidly fitted into a common flat sheet of a suitable metal (or other suitable material) with the outer edges turned down and soldered or welded that may form an airtight/waterproof cowl of a building, it is also in the scope of this invention that VPHE panels 211 may be bent to any desired shape and may contain any configuration of fins and be suitably sealed through the common panel 212 at any angle as dictated by the

particular application at hand.

Fig. 12 shows an application where VPHE modular panel unit 210, of Fig. 11 is mounted through the inclined roof 220 of building enclosure 221 , to form a passive solar space heating system in combination with room thermostat 222, that may turn on automatically the air circulating fans 223 and 224 as required.

A waterproof translucent cover 225, is fitted over VPHE modular panel unit 210 and a system of sun louvres, roller blind or means to reduce the pressure in VPHE panels

may be provided to prevent the VPHE panels from heating the enclosed space 221 in summer when heat is not needed.

Another method to deactivate the VPHE panels from heating would be to blow into the cowl that houses the VPHE panels an insulating medium such as light insulating objects like table tennis balls or small light balls of polystyrene foam, or small balls of ultra light "AEROGEL".

Further, another means to insulate the VPHE panels in accordance with this invention from heat at times when heat is not needed is to place over the VPHE panels using suitable means a layer or sheet of the newly

developed ultra light super thermal insulating material known as "AEROGEL" recently developed by a university in US. The "AEROGEL may be located as a blanket 226, roiled up on a spring loaded roller blind unit inside the roof top cowl unit 225, and when the VPHE's are to be put out of service the blind will automatically roll down over to cover the VPHE panels. A thermostat 227 could be used to sense when outdoor air temperature is too hot and activate the roller blind mechanism.

It is also within the scope of this invention to utilise the new ultra light high heat insulating material

"AEROGEL" in sheet form or insulating balls in combination with the VPHE modular panel units as means to provide super insulation and thermal stability to the overall building structure. The AEROGEL may be used in sheets of any desired width, height and thickness to form part of a high thermal insulating wall or ceili ng structure.

In a similar fashion in combination with VPHE panels in accordance with this invention, the AEROGEL may be blown into ceiling and wall cavities in small balls or granules or other shape or form that it may become commercially

available in due course. Aero-gel is excellent thermal insulation and the lightest material ever made by man, being approximately three (3) times the weight of air.

Fig. 13 shows the VPHE modular panel unit 210, in combination with and welded to an air/watertight,

insulated heat exchanger section 230, with fluid inlet 231 , and fluid outlet 232, the system to be utilised for the purpose of solar hot water heating or heating of any other fluid as required.

Fig. 13 A shows yet another application of the VPHE modular panel 210 as outlined in Fig. 11 , Fig. 12 and Fig.13.

In this particular embodiement the panel 210 in combination with its insulated heat exchanger section 230 is welded to another insulated heat exchanger section 240, where the VPHE panels are used to transfer efficiently heat from the fluid in the hotter heat exchanger section 240, to the cooler fluid in heat exchanger section 230. The VPHE panels are shown mounted through the common panel in inclined configuration at a given angle, but in accordance with this invention any desired angle or desired shape of VPHE panel may be utilised.

Fig. 14 shows a typical flat type VPHE panel 200, with fins 210, that may be fitted into any VPHE modular building panel in accordance with this invention . Pressure adjustment means 220 is shown together with suitable means 230 to fill the panel with the working fluid and a suitable drain cock means 240 to drain the VPHE of its working fluid should it be desired to change the working fluid.

Fig.15 illustrates a typical flat type VPHE panel 250, without fins together with pressure adjustment means 220, liquid filling means 230 and drain cock means 240.

Fig. 16 shows a typical inner vacuum support matrix 260 that may be inserted inside panel 200 and panel 250 which is designed to provide adequate support and distribution of the working fluid and vapour inside the working VPHE. The inner support matrix is fabricated from a suitable material that must be compatible with the working fluid and the material of construction of the VPHE. A number of holes 270 have been drilled in sections of the inner support structure for even dispersion of the working fluid and to equalise the vapour dispersion throughout the panel.

This inner support matrix shown is typical but it may be of any desired length, size or shape to satisfy the size of the particular VPHE.

Fig. 16A shows another type of inner support structure 275, that may be made by folding or moulding in expandable "Vee" shape of any desired thickness, height or length from a suitable compatible material to suit a specific application. A number of hojesin the inner support structure are shown as to give an even distribution of fluid in the evaporator section and even distribution and pressure of vapour in the condenser section.

Fig. 16 B shows a cross section of another typical type of VPHE inner support structure 280, in

accordance with this invention that may be extrusion moulded from any suitable material to suit the application. Fig 16 C shows yet another type of inner support structure with corrugation shape in accordance with this invention.

It will be appreciated to those conversant in the art that this invention is not restricted only to the typical inner support structure types shown in Fig. 16, Fig. 16A, Fig. 16 B and Fig. 16C, and that the scope of this invention

provides that any shape of inner support structure, made of any given size, material and method of construction or manufacture may be used. In VPHE systems with the evaporator and

condenser sections located in a commen space or volume and used in the thermal diode mode it may be prudent to in some circumstances to manufacture the inner support structure from a low heat conducting material to minimise the conduction of heat at times when heat transfer is not desirable.

In other applications to maximise heat transfer from the heated evaporator section to the cooler condenser section an inner support structure made from a high heat conduction material such as copper or aluminium for example, may be benefical giving of course due consideration to compatibility between the inner support structure, the working fluid and the material of construction of the VPHE or BOINGA panel.

In design of the inner support structure for a specific application it is important for efficient operation of the VPHE to ensure that at all times during operation of the panel there is an even distribution of the working fluid in the evaporator and of the vapour in the condenser section.

Fig. 17 shows another type of VPHE modular panel system in accordance with this invention that provides for the evaporator section of the VPHE to be physically separate from the condenser section but to be jointed thermodynamically by means of suitable vacuum tight commercially available fittings and vacuum fluid and vapour lines that may be easily jointed together to make up an overall VPHE passive heating or cooling system as required. The particular advantage of this system is that it may be retro-fitted to existing buildings to provide a passive

heating or cooling means as dictated by the particular application. Modules of VPHE units may be jointed together to make up the overall system and it is in the scope of this invention that a number of modules of VPHE panels may be jointed together in common pressure control for ease of control to modify the thermal performance of the overall VPHE installed system as required.

The evaporator module 300, is thermodynamically joined with the condenser module 310, using commercially available vacuum hose couplings 320, that may plug into commercially available vacuum hose fluid and vapour lines

321 and 322 of suitable diameter and length to suit the specific application. The evaporator module 300, is 100 % full of the working fluid (for example, water or methanol) whereupon boiling at a specific preset temperature and pressure, the vapour rises up vacuum line 321, and via the exit spout 330, enters thecondenser module 310, whereupon said vapour condenses on the condenser walls, providing the temperature of said condenser walls is less than the condensation temperature of the vapour and the condensate by gravity means flows back to said evaporator module 300, via the liquid return hose 322.

Both the evaporator module 300, and condenser module 310 may be fitted with heat transfer fins 340, if so desired to increase the thermal performance of the system. The evaporator module 300, is shown fitted with a drain cock means 351 , to drain the evaporator of the working fluid as required. The condenser module is fitted with a suitable valve 360, that may be used to fill the system with an appropriate amount of the working fluid 370 as desired. Condenser section 310 is fitted with pressure adjustment valve 350, to adjust the operating pressure as required. The selection of and the quantity of working fluid is most important to the overall operation of the system. In the example of Fig. 17 the bottom of the condenser module contains a small amount of condensed vapour so that the fluid condensate return line 322, the vapour bubble fine 321 and the evaporator 300 are full of working fluid at all times, thus ensuring that the

evaporator module 300, is 100 % wetted continuously.

If this system is used for passive solar space heating and/or hot water heating the evaporator module is located outside the building enclosure and faces the sun to collect solar heat, while the condenser module (at an appropriately higher level) would be located within the building enclosure whereby heat is transferred from the hotter outside evaporator module to the cooler condenser module inside the building.

If this modular VPHE split system is to be used for passive cooling of a heat emitting building enclosure, the hotter evaporator section would be located inside the building enclosure and the condenser module would be located in the cooler outside atmosphere at an appropriately greater height than the evaporator module. The scope of this invention also provides that all fittings and lines between evaporator and condenser modules may be rigidly welded to provide a more

permanent type of installation.

Fig. 18 shows an example of the modular VPHE split system that may be used for passive solar space heating of two rooms 400 and 410, of a building.

The bottom room 400 is heated using the split VPHE system with evaporator module 420, located outside fitted thermodynamically to the condenser module 421 , using vapour flow line 422, and condensate liquid return line 425, with appropriate flexible hoses and vacuum fittings or welded pipes and fittings as covered in accordance with this invention.

The evaporator module 420, and the condenser module 421 , are shown to be mounted in vertical

configuration. Sun louvres 426, have been provided to prevent the system from heating during warmer weather. The top room 410, is shown with outer evaporator module 440 that contains heat transfer fins 441 connected with appropriate vacuum lines and fittings to a bent condenser module 450, that also contains heat transfer fins 451 .

Fig. 19 shows four enclosures 500, 510, 520 and 530 of a multi storey building being passively solar heated using modular VPHE split systems in accordance with this invention. In the bottom room 500, is shown the outside evaporator unit 501 , which is connected thermodynamically using appropriate vacuum lines and couplings to the condenser module 502. A thermostatically operated fan 503, is provided to operate automatically as required to increase the rate of heat transfer as required by the specific design and operating conditions. The evaporator is shown to be at a lower level than the condenser module so that the evaporator 501 , is 100% wetted at all times. Similarly room enclosures 510, 520 and 530 are heated using their own dedicated VPHE modular split-systems. In the upper room 530, the evaporator module and the condenser module are shown fitted with fins to increase the rate of heat transfer and thermal performance of the system. Fig. 20 illustrates three modular VPHE split system units utilised to provide solar hot water heating of water in a common insulated water tank 600, whereby the three condenser units 601 , 602 and 603 are located above the three evaporator modules 604, 605 and 606, the

evaporator and condenser modules being jointed together thermodynamically using appropriate vacuum fittings and vacuum lines 610, 611 , 612, 613, 614 and 615.

The insulated common water tank 600 is shown

fitted with three condensers, however provision for expansion of the system is provided for two more

condenser modules by plugging into the two spare inlet line plug connections 620, and the two outlet line plug connections 621. The insulated water tank 600, is shown fitted with an insulated tank top 630, that may be

removed for maintenance and inspection purposes. The water storage tank 600 may be fitted with appropriately encapsulated balls of a suitable phase change material (PCM) 640, to increase the heat thermal storage capacity of the system.

The insulated water storage tank 600 is shown fitted with an inlet water pipe connection 650, and a water outlet connection 651.

Fig. 21 illustrates a number of VPHE split system units used for passive cooling of ground floor building enclosure 700, first floor enclosure 710 and second floor enclosure 720 of a multi floor building that contains heat emitting equipment, for example electronic equipment.

The ground floor equipment enclosure 700, has electronic equipment heat load 7 01 , and is passively cooled

with inclined evaporator finned module 702, linked thermodynamically with appropriate vacuum fluid lines and couplings to its vertical finned condenser module 703, that is mounted adjacent to the outside wall of the building. It is to be noted that condenser module 703, is located higher than its evaporator module 702, so as to provide an adequate vapour flow and condensate liquid return flow. A wall mounted air circulating fan 704, operated

automatically by room thermostat 705 is provided to give added heat transfer at times when required. In a similar fashion to the ground floor, the first floor equipment room 710, with its electronic equipment load 71 1 is cooled using vertical wall mounted evaporator module 712, connected thermodynamically with

appropriate couplings and vacuum line connections to its finned condenser module 713 that is mounted vertically against the outside wall of the building. A circulating air fan and thermostat may be provided to give added heat transfer at times when needed.

The second floor equipment room enclosure 720, with its electronic equipment heat load 721 , is passively cooled using two VPHE modular split systems in accordance with this invention. One VPHE split system has its finned evaporator module 722, mounted in proximity to a vertical wall inside the enclosure and is connected

thermodynamically to its outside finned condenser module 723, mounted in a vertical position on the roof

immediately above.

The other VPHE modular split system has its evaporator module 723 mounted adjacent to a vertical wall inside the enclosure with its condenser section linked thermodynamically with appropriate couplings and fluid lines to the inclined finned condenser module 724, located outside and mounted on the inclined roof..

With all VPHE split modular systems, appropriate

shielding of the condenser sections from the sun may beprovided in the event of any condenser modules

beingdirectly exposed to the heat of direct solar

radiation, as direct solar heat gain will reduce the

effectiveness of the condenser modules.

This invention caters for each VPHE panel to have the option of a pressure alarm together with a valve that may be connected to vacuum lines running to a manifold with connection to a vacuum pump and a vacuum pressure relief valve so that settings on the system can be adjusted and/or detected in the event of leaks in the overall system.

The valve system, vacuum lines, manifold, vacuum pump and pressure relief system will also provide that settings of the overall system can be altered to change the thermal performance. The provision of these controls and

adjustments will enable a VPHE heating and/or cooling system to be de-activated at times when not needed. . It will be appreciated by those conversant in the art that this invention does not only apply to a heat transfer panei operating under a vacuum and it may also operate in other circumstances using a positive pressure within the heat transfer panels using working fluids and operating temperatures andpressures in accordance with a specific application.

Careful choice of panel and the working fluid to match the heat transfer characteristics is required to

ensure compatibility, this choice being well considered by those knowledgable in the art.

It will also be appreciated by those conversant in the art that all of the VPHE panels described in this invention may contain a valve for maintenance purposes through which the pressure within the panel can be controlled during its working life to adjust the

temperature at which the panel will operate, or

alternatively a change in pressure may be necessary to prevent the panel from operating at certain times of the year.

It will also be appreciated that this invention may operate in conjunction with an automatic control system that can sense the internal building temperature conditions and the external weather conditions and alter the pressure within the VPHE as required.

All condensate return drip trays, for example see Fig.3 items 35 and 36 may be manufactured to have a number of perforated punched holes so that vapour can pass up through the holes whilst the top of the hole being above the general surface of the drip tray will prevent the condensate from falling down through the holes and thus ensure that 100% of the condensate will return to its respective fluid resevoir.

It will also be appreciated, that dependent upon the method of manufacture, a number of holes or grooves may not be necessary for satisfactory vapour dispersion through the entire panel, and with enough space at the end of return drip trays satisfactory vapour dispersion may be possible without the need to have holes or grooves cut, thus simplifying the overall manufacture and reducing costs. Also within the scope of this invention is means to insulate VPHE panels from the suns energy when required at times when necessary to prevent unwanted heat from entering the building enclosure during warm or hot weather Such insulating devices include a system of louvres or roller blind or the provision of blowing in a number of small very light insulating balls (for example polystyrene or balls like table tennis balls etc..) to occupy the

enclosed space between the external evaporator surface of a VPHE installed for solar heating and a transparent panel that is used to reduce heat loss from cool wind.

These balls can be blown in using a suitable fan and when needed to reactivate the heating installation the balls can in a similar fashion be blown out to clear the space as required.

It is included in the scope of this invention that the newly developed "AERO-GEL" super light/super thermal insulating material may be used in the form of small balls and be blown into the compartment which houses the VPHE evaporator for the purpose to insulate the evaporator exposed surface area at times when not needed and

similarly the AERO-GEL small balls may be blown out automatically as needed to re-activate the

passive heating system.

Also within the scope of this invention is the use of AERO-GEL in the form of a roller blind material that can automatically or manually be rolled down over the

evaporator of the VPHE as required to de-activate the system.

VPHE evaporator modules mounted in the outside ambient may be covered with a sheet of light transparent material which may be glass or perspex that is positioned adjacent but away from the panels. This both minimises heat loss created by the wind blowing over the panels and also acts as a further element of thermal insulation and thus prevents heat flow from the building to the outside during the night or in periods of very cold weather when there is little or no sun.

Alternatively or together, adjustable louvres located over the evaporator may be used to be open during the day to assist solar collection to the panels and closed at night to minimise heat loss from the panels.

Also in accordance with this invention wickless VPHE units may be rotated on a pivot to enable the position of the evaporator to be rotated from a position inside the room to a position outside the room. The express purpose of the pivot action is so that the VPHE can easily be altered to enable it to function as a heating device (evaporator surface faces outside) during winter or during periods of cool weather whilst it can be rotated on the pivot to function as a cooling device (evaporator faces inside of room) as required for example, cooling can be obtained from radiating heat into the distant sky at night during warm weather.

A variety of evaporator and condenser surface configurations will be apparant to those conversant in the art and will include a panel having a planar configuration. For example the Vee shaped fins 700 or other shape fins 701 , 702 and 703 as shown in

Fig. 22 or Vee shaped fins710 of Fig 24 and other shaped fins 712 and 713 of Fig. 25 may be used that can contain the working fluid or vapour directly inside this type fin .

Fig. 23 shows other types of solid fins 720, 721 and 722 which are moulded on the outside surface of the evaporator and/or condenser modules. The various type of heat transfer fins are for the purpose to increase the effective heat transfer surface area whereby improving the thermal performance of the evaporator or condenser modules. It will be appreciated to those conversant in the art that this invention is not limited specifically to the evaporator and condenser fin types outlined in,

Fig. 22 to Fig. 25 inclusive, but may contain any fin shape or type that may be considered most suitable to satisfy the design criteria of VPHE evaporator and/or condenser surfaces.

Fig.26 shows a new type of roof construction in accordance with this invention using VPHE panels 810, 820, and 830 manufactured and installed in accordance with this invention to provide passive solar heating to the building enclosure 840.

The VPHE roof panels may be any desired thickness, width and length to suit a specific application and may contain any desired working fluid at any given internal adjusted working pressure to suit a specific

application. The roof panels if so desired, may all be joined together using a common pressure adjustment system so that all panels can be adjusted simultaneously as required. The VPHE panels are installed on the inclined roof surface so that the evaporator sections are exposed directly to the sun, whilst the inside condenser sections are

exposed immediately to the room air. Provision of suitably located circulating fans 841 and 842 may be used to increase the rate of heat transfer from the condenser surfaces 811 , 821 and 831 of VPHE panels 810, 820 and 830 respectively..

Located between the evaporator sections of VPHE's and overlapping condenser sections of other VPHE's is a layer of high thermal insulating material (such as the newly developed "AEROGEL") to maximise heat collection in the evaporator units and to minimise the unwanted heat transfer between evaporator sections of tiles and condenser sections of other overlapping tiles, for example, there is a layer of the high heat insulating material 870 between the flat underside of evaporator section 812 and the flat upper face of condenser section 821 of VPHE tile 820. A suitable VPHE waterproof mounting system is shown where wooden cross members 880, with metal brackets 881 , and nails

882 may be utilised to support the VPHE panels. The VPHE roof section will act as a very effective thermal diode where heat can easily be transmitted from the outside sun to the inside of the enclosure 840, but because of the vacuum in VPHE condenser sections in contact with the blanket of ultra high heat insulating material 870, there will be a very high resistance to heat flow from inside enclosure 840 to the outside atmosphere.

In combination with the VPHE panels is shown a roof top cowl 890 , upper insulated waterproof roof section

891 , and lower insulated waterproof roof section 892.

VPHE panels 810 and 820 are similar in that they have heat transfer fins on their upper face of the evaporator and on the lower surface of the condenser which faces the inside of building enclosure 840.

VPHE panel 830 is different in that it is a flat plate type and has no heat transfer fins.

Such a system would have good application in locations with readily available strong solar radiation combined with a low ambient air temperature. Similar to other VPHE illustrations in this document a system of transparent screen can be used to minimise heat loss from the evaporator surface of the VPHE and suitable means to prevent the system from operating in hot weather should be provided such as louvers, roller blind, provision of a heat insulating material or a simple means to reduce the pressure within the VPHE units to make said units inoperative.

FIG. 27 shows a method of manufacture of the VPHE 900, using a number of tubes 890, pipes or other shape to be connected at each end into common manifolds 901 and 902, whereby all tubes are subject to a common internal vacuum and/or pressure that may if so desired be adjusted via a valve 903, with a suitable pressure adjustment means.

Such a construction would have the advantage that it would be simple to manufacture, whilst being robust and not requiring the need for an inner support structure. Tube 904, is shown to have heat transfer fins 908, that may apply to all tubes or pipes or other appropriate shape if so desired. The VPHE 900, may contain a manifold 901 , and a working fluid draincock means 906, to drain the system of the

working fluid 907, if required. This VPHE method of manufacture may be utilised for example, as a roof tile, in accordance with the illustration in Fig. 26, or a wall panel as shown in fig. 4, an inclined roof panel or wall panel as shown in Fig. 6, Fig.7, and Fig.8., VPHE panels as shown in Fϊg.9, Fig. 10, Fig. 11 , Fig. 12 and Fig.13 and for VPHE Split- System applications as shown in Fig.17 to Fig. 26 inclusive. Vacuum fittings 909, and 910 may be provided if desired to enable this panel to be used for split-system application, in which working fluid 907, would fill the entire evaporator section, or if such panel was to pass through a wall or a ceiling of a building enclosure, working fluid 907, would only fill the VPHE to occupy the evaporator section of the overall panel..

A solar translucent screen 911 , may be used to reduce the heat loss from cold wind in the event of such a VPHE being used for wall or inclined roof heating mounting whereby the VPHE absorbs solar energy and transmits such heat to the inside of the building enclosure via the

condenser section. FIG. 28 shows a typical VPHE panel shape l 000, in accordance with this invention, that may be manufactured by folding and welding of suitable metal construction or by extrusion of a suitable heat conducting plastic or other suitable material.

The advantage of such a "Vee" construction is that the Vee shape 1001 , or other suitable shape enables the panel to be made and used without the need for an inner support structure.

A vacuum adjustment means 1002, is provided, and vacuum hose connection means 1003, may be utilised should this particular panel be required for operation in split- system mode.

FIG. 29, shows the VPHE made with shape comprising two opposed corrugated sheets 1010, of any suitable material and it is noted that here also an inner support structure would not be required as the opposing corrugations of each surface would provide adequate support and structural strength to withstand the applied vacuum.

It is to be noted that a VPHE panel made from such a shape would be suitable for application as building solar heating roof tiles, similar to tiles 810,, 820 and 830 as shown in Fig. 26 afore described. To those conversant in the art, it will be appreciated that such a system of utilisation of corrugated VPHE tiles or panels may also apply for vertical or inclined mounting in building walls for heating and/or passive cooling of an enclosure dependant on whether the evaporator section is either inside the building enclosure or outside the enclosure. An example of a suitable material would be normal corrugated iron roof or wall construction panels that may be clamped and welded together to provide a relatively low cost heating or cooling system.

Fig. 30, shows another method of construction of a VPHE 1020, that has opposing corrugated sheets 1021 , and 1022 of any suitable construction material with a flat sheet 1023 located mid way between the corrugated sheets and the three sheets fused together at the sides 1024 and at the ends such that the upper section contains the VPHE with its working fluid under vacuum, whilst the lower heat exchanger section 1026, (vacuum not necessary) contains a given fluid such as water or air to be heated. It is to be noted that suitable compatible end caps 1027, for each end of the VPHE, welded or fused together to

withstand the applied vacuum will be necessary during manufacture.

FIG. 31, shows another construction technique similar to that already described wherein the VPHE 1030, may contain a corrugated sheet 1031 , appropriately fused together during construction to a flat sheet 1032.

Fig. 32 (a) and (b) show yet other types of VPHE sheet construction. Fig. 32. (a) shows a VPHE 1035, constructed from two square or rectangular type shape sheets 1036, with a flat sheet 1037 located between the square or rectangular shape section sheets. Fig. 32 (b) shows a VPHE made using one flat sheet 1039, located between two opposing triangular section sheets 1038.

To those conversant in the art it will be appreciated that the particular shape of the VPHE sheet construction will depend on application for a specific task in hand.

It will also be appreciated that an opposing "Vee" shape sheets such as in FIG. 32 (b) or opposing "Corrugated" shapes such as in Fig. 30 would be superior in heat transfer to the opposing square sections as shown in Fig. 32 (a), because the triangle and corrugated shapes make contact at a point surface with the flat sheet, therefore providing a greater surface area for heat transfer than that of the square section. This invention provides that any given desired shape of any given suitable material, with or without heat transfer fins or projections may be utilised depending on the specific application at hand.

FIG. 33 shows a VPHE application in accordance with this invention where the VPHE 1040, is manufactured with vacuum sealing of the upper VPHE section of opposing corrugated sheets 1041 and 1042, similar to normal corrugated roof sheeting. The bottom corrugated section is full of water from the swimming pool and operates as a heat exchanger to heat -such water. The VPHE filled with its working fluid 1043, at an appropriate vacuum setting operates in heat exchange with water jacket 1044, through which may flow water from a swimming pool 1045, via water pipes 1046, 1047, 1048 and water circulating pump 1049. A vacuum pressure adjustment means 1050, is provided in the VPHE, together with valves or hose fittings 1051 , and 1052, that may provide inter connection with other VPHE panels operating under a common vacuum setting or alternatively, may provide for vacuum line connections, if so desired with another VPHE condenser section wherein the VPHE could operate in split-system mode. A solar translucent screen 1053, may be used to reduce the chill from cold winds.

FIG. 34, shows a VPHE 1060, that is similar to the VPHE in Fig. 27 except that respective tubes 1061 , filled with a suitable amount of working fluid are bent to any desired shape. The tubes 1060, may be made from any suitable material (such as copper or aluminiun) or a suitable heat conducting plastic or other suitable material and be bent to the most suitable shape accordingly to suit a specific application.

In this particular example, the VPHE is shown in application as a solar building heating system, together with a solar wind shield 1062, that may be used. Inside the heated enclosure 1063, may be included a fan 1064, to force room air across theVPHE condenser section and a shield 1065, is provided for aesthetic reasons to hide the heat transfer condenser coils of the VPHE.

The VPHE may have an upper manifold, 1067, and a lower manifold 1066, pressure adjustment means 1068, fluid lineconnection means 1069, and working fluid

draincock means 1070.

FIG.35, shows three identical double chamber VPHE units 1100, jointed together using a common evaporator

/condenser wall 1101 , in accordance with this invention. Heat received at the evaporator surface 1102, of the first VPHE chamber 1103, is transfered to heat the working fluid 1105, of the evaporator section of the second chamber 1104, by transfer of the heat of condensation from first said chamber via the common condenser/evaporator wall 1101 , into the working fluid 1 105.

Each respective chamber may have its own working fluid, inner support structure, and vacuum

adjustment valve 1106 so that respective VPHE chambers may be calibrated as desired. It is to be noted that each chamber may contain different working fluids, and may have a different operating vacuum adjustment or calibration dependant on a specific application. An advantage of the double chamber VPHE system would be that a much higherthermal resistance could be achieved when operating in the reverse thermal diode mode combined with the possibility to design time lags into the system prior to the VPHE firing.

FIG. 36, shows yet another application for a multi- chamber VPHE 1200, and in this particular illustration three independant vacuum chambers 1201 , 1202 and 1203, are shown jointed together physically and

thermally via their respective common condenser/

evaporator walls 1204 and 1205 respectively.

Multiple liquid resevoir means 1206, located on a common evaporator surface 1207, in each chamber form the evaporator, whereby following boiling of the working fluid 1208, the vapour thus formed will condense on the common condenser/evaporator wall 1204, giving up its latent heat of condensation to heat the working fluid in the adjacent opposing multiple liquid resevoir means of the evaporator located on the other side of the common

condenser/evaporator wall 1204.

Each chamber may have its own pressure adjustment valve 1209, working fluid, and inner support structure. In this particular example of a multiple vacuum- chamber VPHE, respective evaporators have been shown to contain a pluralityof thin liquid resevoirs and following boiling of the working fluid, the condensate occuring on a common condenser wall will return to its respective liquid resevoir means via a plurality of liquid return means from said condenser wall to the respective liquid resevoirs.

It will be appreciated that with this multi- vacuum chamber system, very high thermal

resistances may be achieved when operating in reverse thermal diode mode as the overall VPHE may contain 2, 3, or 4 or more adjoining chambers to form the overall thermal resistance.

Basic testing of VPHE panels operating vertically to transfer heat from hot water (heat source held constant at 60 C) at the evaporator section to cold water at the condenser section using water as the working fluid inside the VPHE, with a vacuum of 28 inches of mercury pulled inside the panel. Heat transfer was tested and computed to be very effective and the average heat transfer

coefficient "Uc" of the condenser section over the test run was 3250 watt/m2. K , whilst the average heat transfer coefficient "Ue" of the evaporator was computed to be 1900 watt/m2.K. The construction material of the VPHE was 1 mm thick copper sheet and the inner support structure was fabricated also from copper sheet with a number of holes drilled similar to construction outlined in Fig. 2A, to enable an even dispersion of the working fluid over the entire

evaporator inner surface area, and vapour to be in even contact with the entire inner condenser surface area.

Fig. 1. shows a VPHE 1 , that can be used for vertical or inclined mounting in a wall or roof of a building

to either transfer heat out of a building enclosure to the cooler exterior or alternatively such panel could be used to collect solar energy on the evaporator face 2, and transfer heat into a building enclosure.

The inner space , of the VPHE is subject to a given internal vacuum pressure that controls the temperature at which the fluid is raised by the wick 4, from the fluid resevoir 5, will boil, whereupon the vapour formed will fill up the entire inner space 3, and condense evenly on the condenser panel 6, providing the temperature of the condenser is below the condensation temperature of the vapour within the VPHE.

The performance of the VPHE panel will depend on the ability of the wick 4, to draw up by capilliary action the working fluid from the fluid resevoir 5. The vertical height of the panel in such a configuration will be

restricted using a single wick by the ability of the wick to effectively raise the working fluid.

Fig. 37 shows a similar VPHE to that shown in Fig.1 with a modified internal structure to

accomodate two additional fluid resevoirs 2007, together with two condensate return drip trays 2008, which have been provided to split the wick 2004 of Fig.1 up into three separate wicks 2009, to form three evaporator sections in a common VPHE inner chamber.

The condensate return drip trays are fabricated with a number of punched holes 2010, so that vapor can pass up through the holes to fill up the entire inner chamber and condense into a liquid at the condensor 2006, with all of the condensate running down the condensate

return drip trays to fall into their respective fluid

resevoirs to be drawn up the respective evaporator wick sections. The holes 2010, in the drip return trays are punched so that vapour can pass up through the holes but the condensate cannot fall down through the holes with 100% of the condensate from each drip tray returning into its

respective fluid resevoir 2007, the liquid working fluid being in contact with its respective wick section.

Referring now to Fig.38 the VPHE 2011 , is shown with a multiple-stage wick system installed in the inclined roof of an equipment enclosure 2013, which houses the heat

emitting electronic equipment 2014.

The three multi-stage evaporators 2015 are shown on the underside of the VPHE which faces the inside of the

building, each wick for example sintered copper, being immersed in its own fluid resevoir.

Another VPHE 2016, is shown mounted vertically in the wall similarly which contains three stages of the multiple wick system in accordance with this invention..

For both VPHEs either in the roof or in the wall when the equipment room heats up to the boiling

temperature of the working fluid, the fluid will boil and vapourise, condensing on the condenser panel, with condensate returning back to each evaporator section via each condensate drip return tray to each respective fluid resevoir.

Fig. 39. shows yet another application of an inclined multi-stage wick VPHE in accordance with this invention being used to receive solar energy and heat a fluid 2021, via a heat exchanger compartment 2022, such as water or air that can be circulated either to a hot water receiving vessel or the hot air can be circulated using a fan either direct heating of a room or to a thermal storage vessel such as a phase change material. In this example four wicks 2023, 2024, 2025 and 2026 are shown with each wick immersed in their own fluid resevoir 2027, 2028, 2029, and 2030 respectively.

The internal working pressure of the VPHE is adjusted to make the liquid boil on the evaporator surface at the desired temperature. A transparent screen 2031 , is shown to let the suns energy through to impinge on the evaporator panel whilst acting as an insulator from possible

cold wind.

Fig.40 shows yet another example of VPHE installed either in an inclined roof 2100, or in a vertical wall for the direct solar heating of a building enclosure 2102, during cooler weather. in a similar fashion to Fig. 38 transparent screens 2103 and 2104 are shown to let the radiation of the sun through whilst minimising heat loss from cool air or wind. Fig.41 shows a number of VPHEs 2200, 2201 , 2202, 2203 and 2204 an electronic equipment room 2205 with heat emitting equipment 2206, in combination with a PCM thermal cool store room 2207 that houses rods or balls 2208, that contain a PCM and a sun shield 2209 for the purpose of passive cooling of the electronic equipment room 2205. VPHE panels 2200 and 2201 are mounted horizontally in the ceiling of the equipment room and the cool PCM store room 2207.

VPHE panels 2202, 2203 and 2204 are shown mounted vertically in the walls of the equipment room and the cool store room. In the equipment room VPHE panels 2201 and 2204 have their internal pressure adjusted so as to pass heat into the outside atmosphere when the evaporator temperature reaches a preset temperature, say 27 C.

VPHEs 2200 and 2202 have their internal pressure set to pass heat from the PCM cool store 2208, to the outside when the evaporator temperature reaches say 23 C and the outside or condenser temperature is less that 23 C. VPHE panels 2201 and 2204 will provide the normal passive cooling for the equipment room when the outside

temperature is less than 27 C. During the cooler part of the day the PCM store will cool down to 23 C. VPHE 2203 is used for emergency cooling at times when the outside air temperature is greater than 27 C and the temperature on the evaporator of VPHE 2203 exceeds a preset temperature, say 30 C when excess heat will pass through VPHE 2203 and be absorbed into the pre-cooled PCM store 2208. The PCM store will regenerate with cooling as soon as the outside temperature is less than 23 C and heat will automatically pass through VPHEs 2202 and 2200 to the outside

atmosphere.

Fig. 42. shows VPHEs 2300, 2301 , 2302 and 2303, a PCM heat store 2304, a transparent screen 2305 and circulating fans 2306 and 2307 to act in combination with the solar radiation and provide an effective heating installation for room 2309 during times of cool weather but clear skies.

VPHEs 2300 and 2301 are shown mounted in an inclined roof structure to receive solar energy. Room 2309 contains bricks 2310 that contain some phase change material located as part of a high density energy storage wall 2311. Fig.43 shows yet another application of a multistage wick VPHE 2400 in accordance with this invention being used in combination with a heat exchanger 2401 to heat fluid 2402 (water or air) passing within, and a parabolic reflector 2403 to direct the suns radiant energy to the underside of the VPHE multi-stage evaporator unit 2404.

It will be appreciated by those conversant in the art that this invention does not only apply to a heat transfer panel operating under a vacuum and it may also operate in other circumstances using a positive pressure within the heat transfer panel dependant on the working fluid and operating temperatures and pressures in accordance with a specific application.

The example of wick shown here has been

sintered copper or a plurality of twills or a mesh

structure to suit the application may be used.

The type of wick to be choosen for a specific application will be choosen to maximise the capilliary head and ensure that the wick permability will allow maximum liquid and vapour capacity in conjunction with optimum thickness to minimise heat transfer resistance.. Careful choice of panel and wick and working liquid to match the heat transfer characteristics is required to ensure compatibility, this choice being well considered by those knowledgable in the art. It will also be appreciated that a given wick

configuration can comprise a combination of a number of different types of wicks that may be joined together to form an overall wick. For example, in some instances it may be beneficial to join a flexible twill wick onto a fixed sintered copper wick to suit a specific application.

It will also be appreciated by those conversant in the art that all of the VPHE panels described in this

invention may contain a valve for maintenance purposes through which the pressure within the panel can be

controlled during its working life to adjust the

temperature at which the panel will operate, or

alternatively a change in pressure may be necessary to prevent the panel from operating at certain times of the year. For example, in Fig 40. which is a solar heating

installation for a building it would be prudent to

alter the pressure within the summertime to prevent the panel from heating the building enclosure. It will also be appreciated that this invention may operate in conjunction with an automatic control system that can sense the internal building temperature conditions and the external weather conditions and alter the pressure within the VPHE as required to optimise VPHE system performance.

All condensate return drip trays shown Fig. 37- Fig.51 may be manufactured to have a number of perforated punched holes or slots so that vapour can pass up

through the holes whilst the top of the hole being above the general surface of the drip tray will prevent the condensate from falling down through the holes and thus ensure that 100% of the condensate will return to its respective fluid resevoir. It will also be appreciated, that dependent upon the method of manufacture, a number of holes or grooves may not be necessary for satisfactory vapour dispersion through the entire panel, and with enough space at the end of return drip trays satisfactory vapour dispersion may be possible without the need to have

holes or grooves cut, thus simplifying the overall

manufacture and reducing costs.

Also .within the scope of this invention is means to insulate VPHE panels from the suns energy when required at times when necessary to prevent unwanted heat from entering the building enclosure during warm or hot

weather. Such insulating devices include a system of louvres or roller blind or the provision of blowing in a number of small very light insulating balls (for example polystyrene or balls like table tennis balls etc..) to occupy the enclosed space between the external evaporator surface of a VPHE installed for solar heating and a transparent panel that is used to reduce heat loss from cool wind.

These balls can be blown in using a suitable fan and when needed to reactivate the heating installation the balls can in a similar fashion be blown out to clear the space as required. Another method to insulate or deactivate the panel during warm weather when heating is not required, is to utilise a roller blanket of the new heat insulating material AER-O-GEL where suitable provision can provision the

Aerogel over the VPHE as required.

Fig. 44. shows another variation of the VPHE panel shown in Fig.37 . The evaporator 2400, is divided up into four sections 2401 , 2402, 2403 and 2404. Sections 2402, 2403, 2404 are different to section 2401 , because the wick 2405 shown in section 2401 is not necessary being replaced with thin (say 5mm to 12mm wide) evaporator sections 2406, 2407, 2408 that hold the working fluid. Evaporator section 2401 is similar to the wicked evaporator section to that shown in Fig.37. and has been used in this illustration to provide a means to

adequately wet the top part of the evaporator. Return fluid drip trays 2410. 2411 , 2412, and 2413 have been shown to provide adequate means for condensate liquid to return from the condenser to the working fluid resevoirs of each evaporator section.

The use of respective thin fluid resevoirs is designed to distribute the working fluid evenly over the internal evaporator surfac of the panel and to avoid the need for a wick.

Each evaporator section is initially filled with working fluid 2409 simply by rotating the vertical VPHE panel clockwise sufficiently until working fluid at the bottom of the VPHE flows to fill each evaporator section and when all

evaporator sections are full of working fluid the VPHE is rotated anti-clockwise back to the vertical position prior to installation in a vertical wall. The inner VPHE is supported by adequate means or bracing 2420 to prevent the VPHE from collapsing when the vacuum is pulled.

Fig.45 shows a cross . section of a support 2500, that could be sliped if necessary into each evaporator fluid resevoir so as to provide adequate support .

Fig. 46 is a perspective view that shows how

the inner support 2500 shown in Fig. 45 would fit into the evaporator fluid resevoir.

Fig. 47 shows a perspective view of a building enclosure 2500 in which the panel is used as a means to transmit the suns solar heat into the building through the wall panels 2502. It is to be noted that the wicks or capilliary 2504 in the wall panels are in this embodiement liquid transport mediums within the panel and are

positioned on the hot side of the panel which faces the sun. The sintered wick acts via capilliary action to cover the entire surface area of the panel with the two-phase liquid and it is essential that the bottom of the capilliary is immersed in the liquid return resevoirs 2506 shown in the wall panels. An alternative method of phase change material distribution is the bubble pump method which requires no external power source to ensure adequate coverage of the internal wall surface of the panel. A bubble pump may comprise a plurality of hollow tubes of such a dimension that the boiling phase change material migrates up the tube from the vicinity of the resevoir and emits from the top of the vertically orientated tubes to top portions of the panel.

The wall panels 2502 are shown with a sheet of

light transparent material 2508 which may be glass or perspex which is positioned adjacent but away from the panels.

This both minimises heat loss created by the wind blowing over the panels and also acts as a further element of thermal insulation and thus prevents heat flow from inside the building to the outside during the night or in periods of very cold weather when there is little or no sun.

Alternatively or together, adjustable louvres 2520 are shown which can be open during the day to assist solar collection to the panels and closed at night to minimise heat loss from the panels. Louvres 2520 are useful in the summertime or in hot weather to prevent unnecessary heat gain to the building at times when cooling may be required.

Fig, 48 shows a view of a wall type panel . The wicks 2504 are preferably sintered copper or some other type of suitable metallic mesh.

The material 2504 must be placed contiguous with the hot evaporator side or sun side of the wall and must depend into the liquid resevoir 2506 to enable it to draw up the liquid. Ideally the entire evaporator surface will become wetted with liquid. Also shown is a glass or perspex wind shield 2508.

Fig. 49 shows the panel 2602, being used as a solar collection device for the specific purpose of hot water heating that is to be used for either building space heating or for domestic hot water purposes. The panel is linked with a water pipe system 2621 , a pump 2622, and an

insulated water storage vessel 2623 that may contain a phase change material 2624 encapsulated in a suitable configuration of containers, for example in spheres or tubes. Also shown is a hot water distribution pipe 2625, that links the water storage vessel 2623, a water pump 2626 and a heating coil 2627, for the purpose of heating the inside of a building enclosure 2628, which may have insulated walls 2629 and a ceiling 2630.

It is to be noted that the condenser side of the panel 2631 in this application would be waterproof and in physical association with the water heat exchanger panel 2632. Thus it is envisaged that the panel and water heat exchanger would be manufactured for modular fitment or in a unitary body.

In this particular application the VPHE panel has been shown with a wick 2640, in the top evaporator section in combination with thin liquid resevoirs 2641 , in the lower two evaporator sections.

Fig. 50 shows the panel 2733 , in a configuration where it may be mounted either in a wall 2734, or ceiling 2735, of a building enclosure 2737. The illustration shows the room which may contain wall panels or bricks 2738, that may contain some phase change material (PCM) so that the heat energy transmitted into the building may be effectively stored within the latent heat of fusion of the PCM.

It is to be noted some suitable insulating louvres 2739, would fit over the outside of the panel so that the solar heat can be transmitted to the inside of the building when desired (during cool weather) when the louvres would be open. VPHE 2740 as shown in the wall 2738 may be rotated on a pivot 2741 , to enable the position of the

evaporator to be rotated from a position inside the room to a position outside the room.

The express purpose of the pivot action is so that the VPHE can easily be altered to enable it to function as a heating device (evaporator surface faces outside) during winter or during periods of cool weather whilst it can be rotated on the pivot to function as a cooling device

(evaporator faces inside of room) as required for example, cooling can be obtained from radiating heat into the distant sky at night during warm weather.

Fig. 51 shows a panel 2800, as part of an air heating and thermal storage system for the purpose of space heating a building enclosure. In this application the panel 2800, is linked with a

panel/air heat exchanger 2801 , an air flow duct 2802, a fan 2803, and an insulated heat storage vessel 804, that may contain some phase change material (PCM)

encapsulated in suitable containers such as spheres or tubes or any other suitable shape. The heat storage vessel 2804, is also linked with another air flow circuit comprising an air flow duct 2806, an air fan 2807, a room thermostat 2850, and a room 2808, which is to be heated. The room walls may contain bricks 2809. The fan 2803 is turned " on - off" by some suitable control system linked to a thermostat located inside the heat storage vessel or panels. These panels contain phase change material for the purpose of providing additional energy storage capacity and to stabilise temperatures within the room by

directing the flow of air to or from the heat exchanger as the temperature requirements vary. In this embodiement use of the panel 2800 acts as a thermal energy conductor and provides heat from the atmosphere to the air propelled by fan 2803 from the panel/air heat exchanger 2801.

Thermal energy in the hot air is added to the heat storage bank 2804, that contains phase change material 2805..

The fan 2803 is tumed'on' by some suitable control system linked to a controlling thermostat 2840, located inside the heat storage vessel to regulate the use of the fans. When the heat storage vessel is sufficiently charged with heat, fan 2803 will be controlled "off".

When the building space 2808, requires some heat as detected by a room thermostat 2850, the control system turns on fan 2807 to circulate hot air between the heat storage vessel and room 2808 and its walls 2809 and thereby heat from the heat storage vessel is transferred to heat the room as required.

Fig. 52 shows an embodiement of an evaporator plate 2900, wherein construction is such as to assist liquid accumulation and increase the exposed surface area of such a plate. Thus warm air inside the enclosure or room that is above the boiling temperature of the liquid inside the panel is adjacent continuous hollow fin arrangements 2907, to increase the effective surface area of the liquid exposed to the room's thermal energy, whilst providing a suitable resevoir for the liquid 2903, to accumulate within the panel. It will be appreciated that such a shape for the lower plate may be also used on the upper condensing side of the panel.

A variety of configurations will be apparant to those conversant in the art and will include:

Fig. 53 which is a panel having a planar configuration for example, the "Vee" shaped fins 2908, and various types of corrugations of the surface to improve the effectiveness of heat transfer;

Fig. 54 that shows another 'Vee" shape to increase heat transfer and satisfying the needs of a specific application; and;

Fig. 55 that shows a number of other s hapes 2910, 2911 , 2912 and 2913 that may be manufactured to enhance thermal energy transfer performance and

mechanical strength and aesthetic acceptance.

Claims

CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A panel structure for transferring heat

preferrentiaily in one direction, said panel structure comprising,

side walls and edge walls forming a sealed hollow panel having an evaporator wall and a condenser wall,

a two phase heat transfer fluid partially filling said panel,

at least one two phase heat-transfer fluid resevoir means located on the internal surface of said evaporator wall ,

at least one two phase heat-transfer return drip tray arranged to abut said condenser wall and collect fluid which has condensed on said condenser wall and also arranged to direct said collected fluid into a respective two phase heat-transfer fluid resevoir means,

wherein under conditions of temperature

differential between the external surface of said

evaporator and condenser walls, and a p re-determined internal vapour pressure and upon sufficient heat energy being imparted through said evaporator wall to convert the two phase heat-transfer fluid into a vapour state, vapour migrates to said condenser wall and condenses thereon into a liquid state thereby transferring heat energy in one direction from said evaporator wall to said condenser wall and through said panel structure and said panel structure being without pipes adapted to communicate a heat- transfer fluid in either of its states between evaporator or condenser walls.

2. A panel structure according to Claim 1 wherein at least one of said two phase heat-transfer fluid resevoir means is arranged to have its contents distributed over a substantial portion of an internal surface of said

evaporator wall.

3. A panel structure according to Claim 1 wherein at least one capilliary means is located internal of said panel adjacent to said evaporator wall and arranged to depend into said resevoir means.

4. A panel structure according to Claim 3 wherein said capilliary means comprises a sintered copper wick material,

5. A panel structure according to Claim 3 wherein said capilliary means comprises a metallic mesh material.

6 . A panel structure according to Claim 1 wherein said trays have perforations which allow vapour to pass upwards through said perforations but do not allow liquid to pass downards through said perforations.

7. A panel structure according to Claim 1 wherein said two phase heat-transfer fluid comprises any one of the class 1 refrigerants , florocarbons, water, ammonia, freon 11, pentane, freon 113, acetone, methanol, ethanol, and liquid metal working fluids or a combination thereof.

8. A panel structure according to Claim 1 when used in a building structure wherein said panel structure further comprises pivot means between said panel structure and said building structure to allow the position of respective evaporator and condenser walls to either face internal or external of the building structure depending on whether said panel is to be used to pass heat out of or into said building structure.

9. A panel structure according to Claim 1 wherein said panel is arranged for fitment with like panel

structures or building elements to form portions of a building structure.

10. A panel structure according to Claim 9 wherein said panel structure is vertically orientated.

11. A panel structure according to Claim 9 wherein said panel structure is horizontally orientated.

12 A panel structure according to Claim 1 further comprising a translucent wind break means spaced way from said panel so as to allow thermal energy to be

transmitted therethrough and on to said evaporator wall or said condenser wall to reduce the incidence of air currents onto said evaporator wall or said condenser wall.

13. A combination consisting of a panel structure according to Claim 1 and a heat exchanger portion

wherein said heat exchanger portion is located adjacent either said condenser or evaporator wall to respectively obtain heat from or provide heat to said walls.

14. A panel structure according to Claim 3 wherein said resevoir means is located within said panel, below and adjacent said capilliary means into which depends said capilliary means and adapted to receive said two phase heat-transfer fluid in its liquid state from said condenser wall .

15. A panel structure according to Claim 1 wherein the external surface of either or both of said evaporator or condenser walls is non-planar.

16. A panel structure according to Claim 15 wherein the profile of either or both of said evaporator or condenser walls comprises a corrugated shape.

17. A combination consisting of a panel structure according to Claim 1 and a phase change material thermal storage means, wherein said phase change material thermal storage means is located adjacent either said condenser or evaporator wall to respectively obtain heat from or provide heat to said walls.

18. A panel structure according to claim 1 wherein in use in a building structure said evaporator wall and at least one of said two phase change heat-transfer resevoir means is located outside said building structure, while said condenser wall is located inside said building structure.

19. A panel structure according to Claim 18 wherein said panel structure is used in the wall of said building

structure.

20. A panel structure according to Claim 18 wherein said panel structure is used in the sloping roof of said building structure.

21. A panel structure according to Claim 18 wherein said panel structure is used in the flat roof of said building structure.

22 A combination consisting of a panel structure according to Claim 18 and a heat exchanger portion, wherein said heat exchanger poirtion is located adjacent either said condenser wall or said evaporator wall to respectively obtain heat from or provide heat to said walls.

23. A panel structure according to Claim 1 where in use in a building structure said evaporator wall and at least one of said two phase heat-transfer fluid resevoir means is located inside said building structure, while said

condenser wall is located outside said building structure.

24. A panel structure according to Claim 23 wherein said panel structure is used in the wall of a building structure.

25. A panel structure according to Claim 23 wherein said panel structure is used in the sloping roof of said building structure.

26. A panel structure according to Claim 23 wherein said panel structure is used in the flat roof of said building structure.

27. A combination consisting a panel structure

according to Claim 23 and a heat exchanger portion, wherein said heat exchanger portion is located adjacent either said condenser wall or said evaporator wall to respectively obtain heat from or provide heat to said walls.

28. A combination consisting of a panel structure according to Claim 1 and a first heat exchanger portion located adjacent one of said condenser or said evaporator walls and a second heat exchanger portion located adjacent the other of said condenser or said evaporator walls to respectively obtain heat from or provide heat to said walls.

29. A combination consisting of at least two panel structures according to Claim 1 arranged so that a portion of one of said condenser walls is in heat exchange proximity to an evaporator wall of another panel structure.

30. A combination consisting of at least two of said panel structures according to claim 29 which contain different two phase heat-transfer fluids.

31. A combination according to Claim 29 wherein at least two of said panel structures have different internal pressures.

32. A combination according to Claim 29 when used in a building structure as a portion of a wall of said building structure.

33. A panel structure according to any preceeding claim wherein said panel further comprises valve means to control the internal vapour pressure of said panel.

34. A panel structure according to Claim 33 further comprising a pressure alarm means arranged to detect the pressure internally of said panel structure and having alarm means to provide a signal if said pressure reaches a predetermined level.

35. A panel structure according to claim 34 further comprising control means adapted to receive said alarm signal and to restore with pressurising means said

internal pressure to a level which existed prior to the provision of said alarm means signal.

36. A plurality of panel structures according to claim 1 where said panel structures are connected such that all of said panel structures operate at a common pressure.

37. A heat exchange panel substantially as

hereinbefore claimed and described with reference to the accompanying figures 2 to 55..

38. A heat exchanger apparatus comprising a plurality o f

upper panel structures and a corresponding plurality of lower panel structures for transferring heat preferentially in one direction between said panel upper and lower panel structures,

adapted to be connected together , wherein at least one

said lower panel structure comprising, side walls and edge walls forming a sealed hollow panel containing a two phase heat-transfer material, at .least one said upper panel structure

comprising, side walls and edge walls forming a sealed

hollow panel having a valve means for controlling the pressure internal of said upper panel, and said heat exchanger further comprising, at least one two phase heat- transfer material return means to. communicate said material between said at least one of upper panel structure and said corresponding lower panel structure,

wherein under conditions of temperature

differential

between the external surface of at least one said lower panel structure and said at least one upper panel and a predetermined internal vapour pressure, upon sufficient heat energy being imparted through said lower panel to convert the two phase heat-transfer fluid into a vapour state, vapour migrates to said upper panel and condenses therein into a liquid state thereby transferring heat energy in one direction from said lower to said upper panel through said return means.

39. A heat exchanger apparatus according to Claim 38 wherein at least one two phase heat-transfer material return means is adapted to communicate said material in its vapour state from said lower panel structure to said upper panel structure.

40. A heat exchanger apparatus comprising

a manifold having an upper condenser chamber and a plurality of dependant evaporator chambers,

a twophase heat-transfer fluid partially filling a

lower portion of said evaporator chambers,

a valve means in said manifold for controlling the

pressure internal of said manifold,

such that in conditions of heat differential between said lower portion of said chambers and said upper chambers said two phase heat-transfer fluid transfers heat energy from evaporator chambers to said condenser chamber.

41. A heat exchanger apparatus according to Claim 39 wherein said lower portions of said evaporator chambers are in liquid communication with at least an adjacent one of said evaporator chambers.