WO2003006896A1

WO2003006896A1 - Solar thermal collector with tanks

Info

Publication number: WO2003006896A1
Application number: PCT/HR2002/000033
Authority: WO
Inventors: Marijan ČERKEZ; Vladimir ŠKARUPKA
Original assignee: Cerkez Marijan; Skarupka Vladimir
Priority date: 2001-07-11
Filing date: 2002-07-02
Publication date: 2003-01-23
Also published as: HRP20010519A2; HRPK20010519B1

Abstract

Solar thermal collector with tanks is a stationary thermodynamic device of greenhouse type for conversion of radiated sunlight into the heat of working substance in tanks, which external shells serve as sunlight energy absorbers and the working substance in tanks as accumulation mass of received thermal energy. The collector consist of at least one large horizontal cylindrical tank (1) and at least one smaller vertical cylindrical, thermally insulated tank (2) through which the working substance is flowing (3). The greenhouse space with tanks is closed with the casing covered with a joint multilayered light permeable jacket on the supporting construction arranged on multilayered horizontal base. The base consist of thermoaccumulation plate (14), thermal-hydroinsulating interlayer (15), supporting plate (16) and drain layer (18), dug in the ground (19). Absorption surfaces (20) inside the greenhouse space are coated with absorption coating and reflecting surfaces (21) surrounding this space with reflecting coating.

Description

SOLAR THERMAL COLLECTOR WITH TANKS Technical Field

The scope of the invention is the solar thermal collector with tanks by means of which a part of radiated sunlight energy is transformed into the thermal energy of working substance in tanks, which external shells serve as solar light energy absorbers and the working substance in tanks itself as accumulation mass of received thermal energy.

According to the sixth edition of the International Classification of Patents, the invention belongs to the field of technique marked with the mark: F24J-2/24 - Solar collectors with conduction of working substance through the collector with thermal accumulation mass.

The sunlight has a broad spectrum of visible and non-visible radiation. A part of sun light spectrum causes heating of the body on which the sun light falls. In solar thermal collectors a part of sunlight spectrum is transformed into thermal energy of various media.

With solar thermal collector with tanks according to the invention, the technical problem of transforming the sunlight energy into thermal energy of working substance flowing through the collector, is solved. Background Art Today there exist various types resp. constructions of solar thermal collector, of which the most represented are plane plate collectors made of plates and/or tubes exposed to the sunlight through which the working substance is conducted and in which the sunlight energy is converted into the heat of working substance. The received heat of the working substance is utilized directly without tank for accumulation of heated working substance or indirectly from the tank for accumulation of heated working substance. In construction of plate collectors with tank, the tank itself is not used as a sunlight energy absorber. Solar thermal collector with tanks according to the invention belongs to types of solar collectors with conducting the opearating medium through the collector with thermal accumulation mass in which tanks are used as sunlight energy absorbers and working substances in tanks as accumulation mass of received thermal energy. Similar solar collectors are described in patent documents EP0334997A1 , FR2540610A and US4520795. In these patent documents there are described solar thermal collectors consisting of one large cylindrical tank through which working substance is flowing and which is placed in casing which upper side exposed to the sunlight is made of light permeable material and the lower side, in the shadow of the tank itself, is made of the layer of thermally insulating material. Conversion of sunlight energy into a thermal energy of working substance takes place by absorption of directly radiated sunlight on the radiated upper surface of the cylindric tank and by direct transfer of the heat from the tank's shell to the working substance. Accumulation mass of received heat energy is primary itself the mass of working substance. Thermal losses of accumulated thermal energy in periods without sunlight because of air convexion between the tank and casing, are prevented by the casing made of light permeable material on the uppeer side and the layer of thermally insulating material on the lower side of the tank. In the patent document FR2536157A3 it is described the solar thermal collector with improved thermodynamic characteristics in relation to above described collectors. Improvement is carried out in conversion of sunlight energy into thermal energy of working substance by increasing the quantity of light energy brought to the radiated upper surface of the cylindrical tank. The light is brought to the upper surface of cylindrical tank by direct radiation and a part of the light reflected from the plane reflecting surface, that in periods withoug sunlight serves as the cover of the plane light permeable part of the casing. In this way the degree of conversion of sunlight energy into thermal energy of working substance is improved and thermal losses of accumulated thermal energy, reduced. Disclosure of the Invention The solar thermal collector with tanks according to the invention is a stationary thermodynamic device of a polythene or glass greenhouse type, for conversion of radiated sunlight into the heat of working substance in the collector. It sonsist of at least one large horizontal metal cylindrical tank without thermal insulation, which longitudinal axis is preferably arranged in direction north-south and at least one smaller vertical metal cylindrical tank with thermal insulation, preferably arranged on the north side of the horizontal tank. Both tanks are placed on supports by which they are separated from the basis on which they are arranged. The tanks are fromthe upper side and on their sided covered with the joint multilayered light permeable shell on the supporting construction constituting polythene or glass greenhouse in which inner side there are tanks i closed air space. Tanks and shell are arranged on the multilayered basis on the drain layer put on the ground. The upper layer of the base having the form of a plate with the surface equal to the surface of a layout of light permeable shell is the thermoaccumulation layer. The upper thermoaccumulation layer of the base lies on the lower supporting layer of the base. The lower supporting layer has also a form of the plate, which surface exceeds the surface of layout of the ligt permeable shell. Larger and smaller axes of these plates overlap, so that outside the layout of light permeable shell there is a belt of lower supporting plate, surroundidng the light permeable shell of the collector on all four sides. Between the upper, thermoaccumulation and lower, supporting plate there is a thermal-hydroinsulating interlayer that prevents transfer of heat from the polyethene-glass greenhouse space to the ground and passage of water and humidity from the ground into the polyethene-gass greenhouse space. The cold working substance, mostly water from water supply system, is brought under pressure to the lower part of horizontal metal cylindrical tank through horizontal perforated supply pipe. Warmed up working substance is withdrawn from the upper part of horizontal metal cylindrical tank through horizontal perforated drain pipe through distributing valve with manual or automatic control, to the lower part of metal cylindrical tank and/or outlet tube from upper part of the vertical metal cylindrical tank towards energy users. All absorption surfaces inside the greenhouse space are coated with absorption coating absorbing radiated sunlight and converting it into heat which is transferred over the air space and tanks' shells on the working substance. Absorption surfaces consist of the external shell of horizontal tank, external shell of thermal insulation of vertical tank, upper surface of upper thermoaccumulation layer of the base and surfaces of supports, pipes and valves, that are during the day exposed to the sunlight.

The quantity of radiated sunlight is increased by the light reflected from reflecting coating to the upper surface of a belt of the lower supporting plate surrounding a light permeable shell of collector to the absorption surfaces inside the greenhouse space. Thermal accumulation mass of the collector consists primarily of the mass of working substance, flowing through the horizontal and vertical tank and of the mass of upper thermoaccumulation layer of the base. To this mass there are added also masses of tanks themselves, thermal insulation vertical tank, tank's support, pipes and valves inside a greenhouse space. Thermal insulation consists of at least two layers of light permeable jacket, air jacket inside the greenhouse space, thermal insulating jacket round the vertical tank, uper thermoaccumulation layer of the base and of thermal. hydroinsulation interlayer in the base of the collector. Thermodynamic process of converting sunlight energy into exploitable thermal energy of working substance in the collector according to the invention is much more advantageous than processes described in mentioned patent documents. Total quantity of radiated sunlight has been increased by the light reflected from reflecting coating on the upper surface of a belt of lower supporting plate surrounding a light permeable jacket of the collector to the absorption surfaces inside the greehouse space. Reflecting surfaces round the light permeable jacket of the collector are arranged on all sides and not only on one side of light permeable jacket as it is described in the patent document FR2536157A3 which provides for higher daily exploitation of reflected light. Absorption surface of the collector according to the invention is larger than absorption surfaces of described collectors for surface of upper plate of the upper thermoaccumulation layer of the base and the surface of external shell of vertical tank. Accumulation mass of the collector according to the invention is increased in relation to accummulation masses of described collectors for the mass of working substance in vertical tank, its mass with its thermal insulation and for the mass of the upper thermoaccumulation layer of a base of the collector.

Thermal insulation of the collector according to the invention is improved in relation to thermal insulations of described collectors, for thermal insulation of vertikal tank, upper thermoaccumulation layer in the base of the collector and thermal- hydroinsulating interlayer in the base of the collector.

All mentioned construction characteristics of the collector according to the invention show undoubtedly that this collector is a thermal device for conversion of sunlight energy into exploitable thermal energy of working substance with substantially more advantageous conversion process than processes described in mentioned patent documents.

Because of increased quantity of light brought to absorption surfaces inside a greenhouse space, increased absorption surfaces, increased total accumulation mass and improved thermal insulation, this collector has mora advantageous degree of conversion of radiated absorbed and reflected light into exploitable thermal energy of working substance, which results in lower price of exploitable thermal energy of working substance.

Fig. 1 shows longitudinal section A-A from the fig. 2 of solar thermal collector with tanks.

Fig. 2 shows cross-section B-B from the Fig. 1 of solar thermal collector with tanks. The solar thermal collector with tanks shown in figures 1 and 2 is a stationary thermodynamic device of a greenhouse type for conversion of radiated sunlight into a heat of working substance in the collector. It consists of at least one large horizontal cylindrical tank 1 which longitudinal axis is preferably arranged in direction north N - south S and at least one smaller vertical cylindrical tank 2, arranged preferably on the north side of horizontal tank 1. Tanks 1 and 2 are made of sheet metal with good thermal conductivity, with anticorrosive protection on internal shells. Efficient vollume of a large horizontal cylindrical tank 1 is larger than daily consumption of a liquid orking substance 3 and efficient volume of a smaller vertical cylindrical tank 2 is many times smaller than the volume of horizontal tank 1. Vertical cylindrical tank 2 is coated with a layer of thermal insulation 4 in metal shell 5. The cold working substance 3 is brought under pressure to the lower part of horizontal cylindrical tank 1 by horizontal supply pipe 6 that is perforated in the tank 1 itself. Warmed up working substance 3 is withdrawn from the upper part of horizontal cylindrical tank 1 through horizontal perforated drain pipe 7 to the distribution valve 8. Depending on necessary quantity of working substance 3 and its outlet temperature, a working substance 3, heated in horizontal cylindrical tank 1 is directed to the vertical cylindrical tank 2 and/or to energy users by means of distribution valve 8 that may be controlled manually or automatically. If smaller quantities of working substance 3 with higher outlet temperature are needed, the complete working substance 3 or its major part is directed by distribution valve 8 and pipes 9 in the lower part of vertical cylindrical tank 2. If larger quantities of working substance 3 with lower outlet temperature are needed, the complete working substance 3 or its major part is directed by the distribution valve 8 and pipes 10 in outlet pipe 1 by which heated working substance is brought from the collector towards energy users. Due to better thermal insulation of vertical cylindrical tank 2, the working substance in it is cooled slower, resp. it retains longer the necessary heat. Therefore reserves of a warm working substance 3 from vertical cylindrical tank 2 are used in periods without sunlight or in morning hours.

Tanks and armature for distribution of working substance ara arranged in the casing of the collector, filled in with the air from environment. The casing is a stationalry building object covered on the upper side and flank sides with multilayered light permeable jacket on supporting construction, constituting greenhouse put on the horizontal base on the ground.

Horizontal cylindrical tank 1 is arranged on supports 12 and vertical cylindrical tank 2 on supports 13 arranged on horizontal base of the collector. Supports 12 and 13 are arranged on the upper, thermoaccumulation plate 14 which surface is equal to the layout surface of light permeable jacket and which is with its complete thickness in the greenhouse space. Thermoaccumulation plate 14 is made of concrete with or without armature or other thermoaccumulation materials. In thermodynamic sense, the plate 14 primarily represents the accumulator of a part of received thermal energy of the collector during periods with light and during periods without lights it has a minor function of thermal insulator. In statical sense it represents the support taking over a part of the weight of collector's erection.

Thermoaccumulation plate 14 lies on the lower, supporting plate 16 which surface exceeds the surface of layout of light permeable jacket. Larger axes and smaller axes of these plates overlap, so that outside of layout of the light permeable jacket there is the belt 17 of the lower supporting plate 16, surrounding on all four sides the light permeable jacket of the collector. Supporting plate 16 is above the ground level and its belt 17 is made with moderate inclination for draining precipitation waters. It is made of reinforced concrete with primary function of statical support of collector's erection and anchorage of greenhouse construction. In thermodynamic sense, the supporting place 16 has a secondary function of thermal accumulator and thermal insulator.

Between the upper, thermoaccumulation plate 14 and lower supporting plate 16 there is a thermal-hydroinsulation interlayer 15 by which there is prevented the transfer of heat from greenhouse space to the ground and passage of water and humidity from inthe ground to the greenhouse space. It is made of building materials with good thermal-insulating and hydroinsulating characteristics.

The lower supporting plate 16 lies on drain layer 18 made of water permeable gravel burrowed in ground 19. The layout of drain layer 18 is equal to or larger than layout of supporting plate 16. Drain layer 18 has primary function of suporter of collector erection and drainage of precipitation waters.

All surfaces inside the greenhouse space exposed to daily direct and/or reflected sunlight, represent absorption surfaces of 20 collectors. These surfaces are coated with absorption coating that absorbs radiated sunlight and converts it into the heat that is transferred over the air space and tanks' shells to the working substance 3.

Absorption surfaces 20 consist of the surface of external shell of horizontal tank 1 , surface of external metal shell 5 of vertical tank 2, upper surface of the upper thermoaccumulation plate 14, external surfaces of supporters 12 and 13 and external surfaces of pipes 6, 9 and 10 which are during the day exposed to the sunlight.

Quantity of radiated sunlight increases by the light reflected from reflecting surfaces 21 on the upper surface of the belt 17 of the lower supporting plate 16 surrounding the light permeable jacket of the collector. Reflecting surfaces 21 are coated with reflecting coating that reflects a high percentage of sunlight to absorption surfaces 20 inside the greenhouse space. High characteristics of light reflexion, resistance to atmospheric influences and good adhesion to concrete base show thermoceramic coatings.

The greenhouse space in which there are tanks is closed on the upper side and flank sides with one of known constructions of multilayered light permeable jackets in construction of greenhouse. The most suitable construction of Night permeable jacket for this purpose is greenhouse construction consisting of supporters anchoraged in the lower supporting plate which carry two or more layers of plastic foils having a high degree of sunlight permeability, high thermic, thermoinsulation and mechanical characteristics. The solar thermal collectors with tanks are constructed as stationary thermodynamic devices of greenhouse type for conversion of radiated sunlight into the heat of working substance in the collector for large area of application. They are foreseen for preparation of large quantities of warm working substance in geographical areas with higher daily insolation. Working substance may be any liquid substance as e..g. water and other liquids. They are applied particularly for water treatment for sanitary needs as e.g.:

• for residential buildings, family houses and weekend houses,

• for farms and industrial plants,

• for hotels, restaurants and catering objects, • bathing places, swimming pools, showers on beaches and camps,

• schools, kindergardens and medical institutions.

Claims

1. Solar thermal collector with tanks in which the radiated sunlight is converted into thermal energy of working substance in the collector with stationary greenhouse space closed with the casing covered on the upper side and flank sides with joint multilayered light permeable jacket on supporting construction constituting greenhouse put on the horizontal base on the ground, characterized by, that in one greenhouse space there is at least one large horizontal cylindrical metal tank (1), which longitudinal axis is arranged preferably in direction north (N) - south (S), which efficient volume is larger than daily consumption of liquid working substance (3) and at least one smaller vertical cylindrical metal tank (2) arranged preferable on the north side of the horizontal tand (1), which efficient volume is many times smaller than efficient volume of horizontal tank (1) and which is coated with a layer of thermal insulation (4) in metal shell (5), that cold working substance (3) is brought under pressure to the lower part of the tank (1) by horizontal supply pipe (6) which part in the tank (1) is perforated and warmed up working substance (3) is withdrawn from the lower oart of the tank (1) by horizontal discharge pipe (7), which part in the tank (1) is perforated, to the distribution valve (8) controlled either manually or automatically, by which the working substance (3), warmed up in the tank (1), is directed through the pipe (9) to the lower part of the tang (2) and/or through the pipe (10) to the outlet pipe (11) by which the warmed up working substance is withdrawn from the upper part of the tank (2) towards energy users, that the tank (1) is put on supporters (12) and the tank (2) on supports (13) arranged on the horizontal base of the collector consisting of upper, thermoaccumulation plate (14) made of concrete or other thermoaccumulation material, which surface is equal to the surface of layout of light permeable jacket and which is with its complete thickness in the greenhouse space, thermal-hydroinsulating interlayer (15), lower, supporting plate (16) of reinforced concrete, which surface exceeds the surface of layout of light permeable jacket for the belt (7) surface with moderate inclination for draining precipitation waters, surrounding on all four sides the light permeable jacket and drain layer (18) dug in the ground (19), made of water permeable gravel and which layout is equal to or larger than the layout of supporting plate (16).

2. Solar thermal collector with tanks according to the claim 1 , characterized by, that absorption surfaces (20) inside the greenhouse space are exposed to daily direct and/or reflected sunlight, consisting of external surface of the shell of horizontal tank (1), external surface of the shell (5) of vertical tank (2), upper surface of thermoaccumulation plate (14), external surfaces of supporters (12) and (13) and external surfaces of pipes (6), (9) and (10) coated with absorption coating and that reflecting surfaces (21) on the upper surface of belt (7) of the lower supporting plate (16) surrounding the light permeable jacket of the collector, is coated with reflecting coating.

3. Solar thermal collector with tanks according to the patent claims 1 and 2, characterized by, that it is applied for warm water processing for sanitary and industrial needs and warming up other fluid substances.