US20140250927A1

US20140250927A1 - Adsorption heat pump system and method of driving adsorption heat pump

Info

Publication number: US20140250927A1
Application number: US14/282,694
Authority: US
Inventors: Hiroaki Yoshida; Noriyasu Aso
Original assignee: Fujitsu Ltd
Current assignee: Fujitsu Ltd
Priority date: 2011-11-22
Filing date: 2014-05-20
Publication date: 2014-09-11
Also published as: CN103946648A; JP5725201B2; WO2013076805A1; CN103946648B; JPWO2013076805A1

Abstract

An adsorption heat pump system includes: an adsorption heat pump including a condenser configured to condense a vapor of a refrigerant; an air-cooling device configured to air-cool a coolant discharged from the condenser in the adsorption heat pump and to resupply the air-cooled coolant to the condenser; and a controller. The controller controls a flow rate of the coolant to be supplied to the condenser according to a difference in temperature between the coolant supplied to the condenser and the coolant discharged from the condenser.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of International Patent Application No. PCT/JP2011/076864 filed Nov. 22, 2011 and designated the U.S., the entire contents of which are incorporated herein by reference.

FIELD

The embodiments discussed herein are related to an adsorption heat pump system and a method of driving an adsorption heat pump.

BACKGROUND

Along with the recent advent of advanced information society, a large amount of data has been handled by a computer, and many computers have been often placed and collectively managed in a single room in a facility such as a data center. In such a data center, for example, a large number of racks (server racks) are placed in a computer room and many computers (servers) are stored in each of the racks. Then, a large amount of jobs are efficiently processed by organically distributing the jobs to the computers according to their respective operating statuses.
Along with the operation of the computers, a large amount of heat is generated from the computers. Since a high temperature inside the computer causes malfunction and failure, cooling of the computer is important. For this reason, in the data center, the room temperature is usually adjusted by using fans to discharge the heat generated from the computers to the outside of the racks and also using an air conditioner.
Meanwhile, in the data center, a large amount of power is consumed by an air-conditioning system. In this regard, there has been proposed a technology to collect heat (waste heat) discharged from an electronic device such as a computer and to efficiently use the collected heat as energy. In general, the temperature of the heat collected from the electronic device such as the computer is 90° C. or less, and use of an adsorption heat pump (AHP) may make it possible to utilize the waste heat of 90° C. or less to obtain cooling water which may be used for air conditioning, cooling of the electronic device, and the like.

Patent Document 1: Japanese Laid-open Patent Publication No. 08-42935

SUMMARY

According to one aspect of the disclosed technology, provided is an adsorption heat pump system including: an adsorption heat pump including a condenser configured to condense a vapor of a refrigerant; an air-cooling device configured to air-cool a coolant discharged from the condenser in the adsorption heat pump and to resupply the air-cooled coolant to the condenser; and a controller configured to control a flow rate of the coolant to be supplied to the condenser according to a difference in temperature between the coolant supplied to the condenser and the coolant discharged from the condenser.
According to another aspect of the disclosed technology, provided is a method of driving an adsorption heat pump configured to cool a coolant discharged from a condenser in the adsorption heat pump by using an air-cooling device. The method includes: controlling a flow rate of the coolant to be supplied to the condenser such that a difference in temperature between the coolant supplied to the condenser and the coolant discharged from the condenser is equal to or more than a set value.
The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view illustrating an example of an adsorption heat pump;

FIG. 2 is a schematic view illustrating an adsorption heat pump system according to a first embodiment;

FIGS. 3A and 3B are schematic views illustrating air-cooling devices of Modified Example 1;

FIG. 4 is a view (Part 1) illustrating an adsorption heat pump system of Modified Example 2;

FIG. 5 is a view (Part 2) illustrating the adsorption heat pump system of Modified Example 2;

FIG. 6 is a view illustrating an adsorption heat pump system of Modified Example 3;

FIG. 7 is a view illustrating an adsorption heat pump system of an experimental example; and

FIG. 8 is a schematic view illustrating an adsorption heat pump system according to a second embodiment.

DESCRIPTION OF EMBODIMENTS

Prior to description of embodiments, a preliminary matter will be given below in order to facilitate understanding of the embodiments.
FIG. 1 is a schematic view illustrating an example of an adsorption heat pump.
An adsorption heat pump 10 illustrated in FIG. 1 includes an evaporator 11, a condenser 12 disposed above the evaporator 11, and adsorbers 13 a and 13 b disposed in parallel between the evaporator 11 and the condenser 12. A space inside the adsorption heat pump 10 is depressurized to about 1/100 atm to 1/10 atm, for example.
A cooling water pipe 11 a through which cooling water passes and a tray 11 b to store a refrigerant are provided in the evaporator 11. While water, alcohol or the like is used as the refrigerant, water is used here as the refrigerant.
In each of the adsorbers 13 a and 13 b, a heat-transfer pipe 14 and an adsorbent (desiccant) 15 are provided. The adsorber 13 a and the evaporator 11 are connected through a valve 16 a, and the adsorber 13 b and the evaporator 11 are connected through a valve 16 b. As the adsorbent 15, activated carbon, silica gel, zeolite or the like is used, for example.
In the condenser 12, a cooling water pipe 12 a with a number of plate fins attached thereto is disposed. A valve 17 a is disposed between the condenser 12 and the adsorber 13 a, and a valve 17 b is disposed between the condenser 12 and the adsorber 13 b.
The valves 16 a, 16 b, 17 a and 17 b are opened and closed by electrical signals to be outputted from a controller (not illustrated), for example. The condenser 12 and the evaporator 11 are connected by a pipe 18.
Operations of the above adsorption heat pump 10 will be described below.
Here, it is assumed that the valve 16 a between the evaporator 11 and the adsorber 13 a and the valve 17 b between the adsorber 13 b and the condenser 12 are both open in an initial state. Meanwhile, it is assumed that the valve 16 b between the evaporator 11 and the adsorber 13 b and the valve 17 a between the adsorber 13 a and the condenser 12 are both closed. It is also assumed that cooling water is supplied to the cooling water pipe 12 a in the condenser 12 and that hot water heated by heat discharged from an electronic device is supplied to the heat-transfer pipe 14 in the adsorber 13 b.
The pressure inside the adsorber 13 a is lowered as the adsorbent 15 adsorbs moisture in the atmosphere. Since the valve 16 a between the adsorber 13 a and the evaporator 11 is open, the pressure inside the evaporator 11 is also reduced. Accordingly, the water stored in the tray 11 b evaporates, depriving the cooling water pipe 11 a of latent heat. As a result, the temperature of the water passing through the cooling water pipe 11 a is lowered, and thus low-temperature cooling water is discharged from the cooling water pipe 11 a. This cooling water is used for room air conditioning, cooling of electronic devices, and the like, for example.
A water vapor generated by the evaporator 11 enters into the adsorber 13 a through the valve 16 a, and is adsorbed by the adsorbent 15.
While the adsorption process is carried out in one adsorber 13 a to adsorb moisture onto the adsorbent 15, a restoration process is carried out in the other adsorber 13 b to restore (dry) the adsorbent 15. More specifically, in the adsorber 13 b, the moisture adsorbed onto the adsorbent 15 is heated and turned into a water vapor by the hot water passing through the heat-transfer pipe 14, and then separates from the adsorbent 15. The water vapor generated in the adsorber 13 b passes through the open valve 17 b and then enters into the condenser 12.
The water vapor that has entered into the condenser 12 from the adsorber 13 b is cooled by the cooling water passing through the cooling water pipe 12 a, and is condensed into a liquid around the cooling water pipe 12 a. This liquid moves to the evaporator 11 through the pipe 18 and is stored in the tray 11 b.
After the adsorbent 15 in the adsorber 13 a adsorbs a certain amount of moisture, adsorption efficiency of the adsorbent 15 is lowered. Therefore, after the elapse of a certain period of time, the controller switches the hot water supply destination from the adsorber 13 b to the adsorber 13 a, and also closes the valves 16 a and 17 b and opens the valves 16 b and 17 a. Thus, moisture adsorption by the adsorbent 15 is started in the adsorber 13 b, and the adsorbent 15 in the adsorber 13 a is restored by moisture evaporation from the adsorbent 15.
The adsorption heat pump 10 operates continuously by switching the hot water supply destination between the adsorbers 13 a and 13 b at intervals of a certain period of time as described above.
Meanwhile, as described above, the cooling water is supplied to the cooling water pipe 12 a in the condenser 12. Normally, circulating water is used as the cooling water to be supplied to the condenser 12, and a cooling device cools the circulating water so as not to increase the temperature thereof. When the cooling device consumes a large amount of power, an energy-saving effect achieved by the use of the adsorption heat pump is reduced. For this reason, a sprinkler cooling tower with relatively low power consumption is often used as the cooling device.
However, the sprinkler cooling tower occupies a relatively large space for installation, making it difficult to use the adsorption heat pump described above in a relatively small-scale facility.
In the following embodiments, description will be given of an adsorption heat pump system and a method of driving an adsorption heat pump, which may be used even in a relatively small-scale facility.
(1. First Embodiment) FIG. 2 is a schematic view illustrating an adsorption heat pump system according to a first embodiment.
An adsorption heat pump 20 includes an evaporator 21, a condenser 22 disposed above the evaporator 21, adsorbers 23 a and 23 b disposed in parallel between the evaporator 21 and the condenser 22, and a controller 30. A space inside the adsorption heat pump 20 is depressurized to about 1/100 atm to 1/10 atm, for example.
Note that while two adsorbers 23 a and 23 b are disposed in parallel between the evaporator 21 and the condenser 22 in this embodiment, three or more adsorbers may be disposed between the evaporator 21 and the condenser 22.
The adsorption heat pump system according to this embodiment includes the adsorption heat pump 20 described above, an air-cooling device 29 and a cooling water circulating pump 31. The adsorption heat pump 20 is disposed near an electronic device or the like which discharges waste heat, for example. The air-cooling device 29 and the cooling water circulating pump 31 are disposed outdoors.
A cooling water pipe 21 a through which cooling water passes and a tray 21 b to store a refrigerant are provided in the evaporator 21. While water, alcohol or the like is used as the refrigerant, water is used as the refrigerant in this embodiment.
In each of the adsorbers 23 a and 23 b, a heat-transfer pipe 24 and an adsorbent (desiccant) 25 are provided. A valve 26 a is disposed between the adsorber 23 a and the evaporator 21, and a valve 26 b is disposed between the adsorber 23 b and the evaporator 21. As the adsorbent 25, activated carbon, silica gel, zeolite or the like is used, for example.
A pressure sensor 41 a to detect a pressure inside the adsorber 23 a is disposed in the adsorber 23 a, and a pressure sensor 41 b to detect a pressure inside the adsorber 23 b is disposed in the adsorber 23 b. Signals to be outputted from these pressure sensors 41 a and 41 b are transmitted to the controller 30.
In the condenser 22, a cooling water pipe 22 a with a number of plate fins attached thereto is disposed. A valve 27 a is disposed between the condenser 22 and the adsorber 23 a, and a valve 27 b is disposed between the condenser 22 and the adsorber 23 b. The condenser 22 and the evaporator 21 are connected by a pipe 28.
A pressure sensor 22 b to detect a pressure inside the condenser 22 is disposed in the condenser 22. A signal to be outputted from this pressure sensor 22 b is also transmitted to the controller 30.
As the valves 26 a, 26 b, 27 a and 27 b, magnetic valves controlled to be opened and closed by the controller 30 may be used. However, differential pressure-driven valves are used in this embodiment, which are automatically opened and closed by a pressure difference, thereby achieving further power saving.
The air-cooling device 29 includes a pipe 29 b with a number of plate fins 29 a attached thereto and a blast fan 29 c. The air-cooling device 29 cools cooling water (refrigerant) passing through the pipe 29 b by blowing the outside air between the plate fins 29 a from the blast fan 29 c. An inlet of the air-cooling device 29 is connected to an outlet of the cooling water pipe 22 a in the condenser 22 through a pipe 35 a, and an outlet of the air-cooling device 29 is connected to the suction side of the cooling water circulating pump 31 through a pipe 35 b. Also, the ejection side of the cooling water circulating pump 31 is connected to an inlet of the cooling water pipe 22 a in the condenser 22 through a pipe 35 c.
A temperature sensor 42 a to detect a temperature of cooling water to be supplied to the cooling water pipe 22 a in the condenser 22 and a flow rate sensor 43 to detect a flow rate of the cooling water are disposed in the pipe 35 c. Also, a temperature sensor 42 b to detect a temperature of the cooling water to be discharged from the condenser 22 is disposed in the pipe 35 a. Signals to be outputted from these temperature sensors 42 a and 42 b and the flow rate sensor 43 are also transmitted to the controller 30.
The controller 30 adjusts the flow rate of the cooling water to be supplied to the condenser 22 by controlling the cooling water circulating pump 31 based on the signals outputted from the pressure sensors 22 b, 41 a and 41 b, the temperature sensors 42 a and 42 b and the flow rate sensor 43. Also, the controller 30 supplies hot water alternately to the heat-transfer pipe 24 in the adsorber 23 a and the heat-transfer pipe 24 in the adsorber 23 b repeatedly each for the certain period of time, the hot water being heated by heat discharged from the electronic device or the like.
A method of driving an adsorption heat pump in the above adsorption heat pump system will be described below.
Here, it is assumed that, in an initial state, the adsorbent 25 in the adsorber 23 a is in a dried state, while the adsorbent 25 in the adsorber 23 b is in a moisture-adsorbing state. It is also assumed that hot water heated to 60° C. to 90° C. by the heat discharged from the electronic device is supplied to the heat-transfer pipe 24 in the adsorber 23 b.
(Restoration Process) Since the hot water is supplied to the heat-transfer pipe 24 in the adsorber 23 b, moisture evaporates from the adsorbent 25 in the adsorber 23 b and the pressure inside the adsorber 23 b is increased. Accordingly, the valve 26 b is closed and the valve 27 b is opened, causing water vapor to enter into the condenser 22 from the adsorber 23 b. Meanwhile, the pressure inside the condenser 22 is increased to be higher than that inside the adsorber 23 a, and the valve 27 a is closed.
The water vapor that has entered into the condenser 22 from the adsorber 23 b is cooled by the cooling water passing through the cooling water pipe 22 a, and is condensed into a liquid. This liquid moves to the evaporator 21 through the pipe 28 and is stored in the tray 21 b.
By continuously supplying the hot water to the heat-transfer pipe 24 in the adsorber 23 b for the certain period of time, the adsorbent 25 in the adsorber 23 b is restored (dried).
(Adsorption Process) In the adsorber 23 a, moisture adsorption by the adsorbent 25 causes the pressure inside the adsorber 23 a to be lower than that inside the evaporator 21, and the valve 26 a is opened. Accordingly, the pressure inside the evaporator 21 is also reduced and the water as the refrigerant evaporates, depriving the cooling water pipe 21 a of latent heat. As a result, the temperature of the water passing through the cooling water pipe 21 a is lowered, and the low-temperature cooling water is discharged from the cooling water pipe 21 a. This cooling water is used for room air conditioning, cooling of electronic devices, and the like, for example.
A water vapor generated inside the evaporator 21 enters into the adsorber 23 a through the valve 26 a, and is adsorbed by the adsorbent 25.
Note that heat is generated when the adsorbent 25 adsorbs the moisture. Therefore, it is preferable to cool the adsorbent 25 by passing the cooling water through the heat-transfer pipe 24 in the adsorber (the adsorber 23 a or the adsorber 23 b) carrying out the adsorption process. In such a case, some of the cooling water to be discharged from the air-cooling device 29, for example, may be passed through the heat-transfer pipe 24 in the adsorber carrying out the adsorption process, or another air-cooling device may be separately provided for the adsorber.
(Switch between Restoration Process and Adsorption Process) After the adsorbent 25 in the adsorber 23 a adsorbs a certain amount of moisture, adsorption efficiency of the adsorbent 25 is lowered. Therefore, after the elapse of a certain period of time, the controller 30 switches the hot water supply destination from the adsorber 23 b to the adsorber 23 a. Then, in the adsorber 23 a, the moisture adsorbed by the adsorbent 25 evaporates, and thus the pressure inside the adsorber 23 a is increased to close the valve 26 a and open the valve 27 a. Thus, a vapor generated in the adsorber 23 a enters into the condenser 22.
Meanwhile, in the adsorber 23 b, the stop of hot water supply reduces the pressure inside the adsorber 23 b. Thus, the valve 27 b is closed and the valve 26 b is opened, causing the vapor generated in the evaporator 21 to enter into the adsorber 23 b.
The adsorption heat pump 20 operates continuously by switching the hot water supply destination between the adsorbers 23 a and 23 b at the intervals of the certain period of time as described above.
(Control of Cooling Water Supplied to Condenser) In the condenser 22, moisture condensation generates condensation heat, which increases the temperature of the cooling water passing through the cooling water pipe 22 a. In this embodiment, the cooling water is cooled by the air-cooling device 29 and resupplied to the condenser 22. In this case, when there is a small difference between the outside air temperature and the temperature of the cooling water discharged from the condenser 22, heat-exchange efficiency of the air-cooling device 29 is reduced, leading to wasteful power consumption. For this reason, in this embodiment, the flow rate of the cooling water to be supplied to the condenser 22 is adjusted by controlling the cooling water circulating pump 31 such that the temperature of the cooling water discharged from the condenser 22 is higher than the outside air temperature by 2° C. or more, preferably 5° C. or more.
However, when the flow rate of the cooling water to be supplied to the condenser 22 is reduced so as to increase the heat-exchange efficiency of the air-cooling device 29, the amount of moisture to be condensed inside the condenser 22 is reduced and dew condensation occurs on an inner wall surface of the adsorber (the adsorber 23 a or the adsorber 23 b) carrying out the restoration process. The moisture condensed into dew drops on the inner wall surface of the adsorber evaporates from the inner wall surface and is adsorbed by the adsorbent 25 in the next adsorption process. Therefore, although the dew condensation on the inner wall surface of the adsorber does not cause the adsorption heat pump 20 to stop its operation, the moisture evaporation inside the adsorber does not contribute to cooling of the cooling water passing through the cooling water pipe 21 a in the evaporator 21, leading to performance degradation of the adsorption heat pump 20.
Therefore, in this embodiment, the pressure inside the condenser 22 and the pressure inside the adsorber (the adsorber 23 a or the adsorber 23 b) carrying out the restoration process are measured by the pressure sensors 22 b, 41 a and 41 b disposed in the condenser 22 and the adsorbers 23 a and 23 b. When a difference between the pressure inside the condenser 22 and the pressure inside the adsorber carrying out the restoration process is outside a predetermined range, the controller 30 controls an ejection amount of the cooling water circulating pump 31 such that the difference between the pressure inside the condenser 22 and the pressure inside the adsorber carrying out the restoration process is within the predetermined range.
A small difference between the pressure inside the condenser 22 and the pressure inside the adsorber carrying out the restoration process means a small amount of moisture to be condensed in the condenser 22 and a high likelihood of occurrence of dew condensation in the adsorber. It is preferable that there is a large difference between the pressure inside the condenser 22 and the pressure inside the adsorber carrying out the restoration process. However, the difference between the pressure inside the condenser 22 and the pressure inside the adsorber carrying out the restoration process is limited by the outside air temperature and is not increased more than a certain level.
In this embodiment, the amount of cooling water to be supplied to the condenser 22 is adjusted by controlling the cooling water circulating pump 31 such that the difference in pressure between the condenser 22 and the adsorber (the adsorber 23 a or the adsorber 23 b) carrying out the restoration process falls within the range of 1 kPa to 2 kPa.
However, an appropriate range of the difference in pressure between the condenser 22 and the adsorber (the adsorber 23 a or the adsorber 23 b) carrying out the restoration process varies depending on the temperature of the hot water to be supplied to the adsorption heat pump 20, the kind of the adsorbent 25, and the like. It is preferable that an appropriate pressure range which meets conditions is obtained beforehand by an experiment or the like and recorded in the controller 30.
(Effects) In the adsorption heat pump system according to this embodiment, as described above, the cooling water discharged from the condenser 22 is cooled by the air-cooling device 29 including the pipe 29 b with the fins 29 a attached thereto and the blast fan 29 c. Thus, no large-size equipment such as a sprinkler cooling tower is used, and the adsorption heat pump may be used even in a small-scale facility.
Moreover, in the adsorption heat pump system according to this embodiment, the flow rate of cooling water to be supplied to the condenser 22 is adjusted such that the difference between the pressure inside the condenser 22 and the pressure inside the adsorber 23 a or 23 b falls within the predetermined range. Thus, the heat-exchange efficiency of the air-cooling device may be increased to enable further power saving. Moreover, dew condensation of moisture (refrigerant) may be prevented in the adsorber 23 a or 23 b carrying out the restoration process. Thus, the performance degradation of the adsorption heat pump 20 is avoided.

MODIFIED EXAMPLE 1

In the first embodiment described above, the cooling water is cooled by blowing the outside air onto the fins 29 a from the blast fan 29 c in the air-cooling device 29. However, a spray pipe 51 a may be provided as illustrated in FIG. 3A, for example, to spray water onto the fins 29 a. In this case, the water deprives the fins 29 a of latent heat during vaporization. Thus, cooling capacity of the air-cooling device 29 is increased compared with the case where the outside air is simply blown onto the fins 29 a.
Alternatively, as illustrated in FIG. 3B, water may be sprayed from a spray pipe 51 b disposed between the blast fan and the fins 29 a, and air of which temperature is lowered by vaporization heat may be sprayed onto the fins 29 a. Also in this case, the cooling capacity of the air-cooling device 29 is increased compared with the case where the outside air is simply blown onto the fins 29 a, as in the case of FIG. 3A.

MODIFIED EXAMPLE 2

In the first embodiment described above, whether or not there is dew condensation in the adsorber is determined based on the difference between the pressure inside the condenser 22 and the pressure inside the adsorber (the adsorber 23 a or the adsorber 23 b) carrying out the restoration process. However, as illustrated in FIG. 4, for example, humidity sensors 52 a and 52 b may be disposed inside the adsorbers 23 a and 23 b, and the controller 30 may determine whether or not there is dew condensation based on outputs from the humidity sensors 52 a and 52 b.
Alternatively, as illustrated in FIG. 5, for example, dew condensation sensors 53 a and 53 b whose electrical conductivity is changed by dew condensation may be disposed inside the adsorbers 23 a and 23 b, and the controller 30 may determine whether or not there is dew condensation based on outputs from the dew condensation sensors 53 a and 53 b.

MODIFIED EXAMPLE 3

When the amount of condensation heat generated during condensation of water vapor in the condenser 22 is smaller than the amount of heat absorbed from the hot water by the adsorber (the adsorber 23 a or the adsorber 23 b) carrying out the restoration process, dew condensation occurs in the adsorber due to insufficient condensation capacity.
In Modified Example 3, temperature sensors 54 a and 54 b to detect the temperature of hot water supplied to the adsorbers 23 a and 23 b and temperature sensors 55 a and 55 b to detect the temperature of hot water discharged from the adsorbers 23 a and 23 b are provided as illustrated in FIG. 6. Also, flow rate sensors 56 a and 56 b are provided to detect flow rates of hot water passing through the heat-transfer pipes 24 in the adsorbers 23 a and 23 b.
The controller 30 calculates an amount of heat absorbed by the adsorber (the adsorber 23 a or the adsorber 23 b) carrying out the restoration process from the outputs from the temperature sensors 54 a, 54 b, 55 a and 55 b and the flow rate sensors 56 a and 56 b. The controller 30 also calculates an amount of condensation heat in the condenser 22 from the outputs from the temperature sensors 42 a and 42 b and the flow rate sensor 43. Then, the controller 30 adjusts the cooling water circulating pump 31 such that the amount of heat absorbed by the adsorber and the amount of condensation heat in the condenser 22 become the same. Thus, the same effects as those achieved by the above embodiment may be achieved.

EXPERIMENTAL EXAMPLE

Hereinafter, description will be given of results obtained by actually manufacturing the adsorption heat pump system according to the first embodiment and checking the performance thereof.
As an experimental example, an adsorption heat pump system illustrated in FIG. 7 is manufactured. In FIG. 7, the same components as those in FIGS. 2 and 4 to 6 are denoted by the same reference numerals, and detailed description thereof is omitted.
In each of adsorbers 23 a and 23 b, five copper corrugated fin heat exchangers are disposed, each filled with 200 g of activated carbon subjected to hydrophilic treatment. Also, dew condensation sensors 53 a and 53 b are disposed inside the adsorbers 23 a and 23 b.
In an evaporator 21 and a condenser 22, copper plate fin heat exchangers having the same shape as those disposed in the adsorbers 23 a and 23 b are disposed. Note, however, that the heat exchangers in the evaporator 21 and the condenser 22 are filled with no activated carbon.
As valves 26 a and 26 b between the evaporator 21 and the adsorbers 23 a and 23 b and valves 27 a and 27 b between the condenser 22 and the adsorbers 23 a and 23 b, differential pressure-driven valves made of PET (polyethylene terephthalate) are used.
A temperature sensor 42 a to detect the temperature of cooling water to be supplied to the condenser 22 and a flow rate sensor 43 to detect the flow rate of the cooling water are disposed in a pipe 35 c on the inlet side of the condenser 22. Also, a temperature sensor 42 b to detect the temperature of the cooling water to be discharged from the condenser 22 is disposed in a pipe 35 a on the outlet side of the condenser 22. Signals to be outputted from these temperature sensors 42 a and 42 b and the flow rate sensor 43 are inputted to a controller 30.
Moreover, temperature sensors 54 a and 54 b and flow rate sensors 56 a and 56 b are disposed on the inlet side of heat-transfer pipes 24 in the adsorbers 23 a and 23 b, and temperature sensors 55 a and 55 b are disposed on the outlet side thereof. Signals to be outputted from these temperature sensors 54 a, 54 b, 55 a and 55 b and the flow rate sensors 56 a and 56 b are also inputted to the controller 30. Furthermore, a temperature sensor 57 is provided to detect the outside air temperature, and a signal to be outputted from the temperature sensor 57 is also inputted to the controller 30.
In the adsorption heat pump system thus configured, cooling water at 18° C. is supplied to a cooling water pipe 21 a in the evaporator 21. Also, hot water at 60° C. is supplied to the adsorber 23 b which carries out the restoration process, and cooling water cooled to 26° C. by the air-cooling device 29 is supplied to the condenser 22 and the adsorber 23 a which carries out the adsorption process. Then, the flow rate of the cooling water supplied to the condenser 22 is controlled such that a pressure difference between the condenser 22 and the adsorber 23 b is within the range of 1 kPa to 2 kPa. Note that the outside air temperature in this event is 25° C.
First, when the hot water at 60° C. is passed at a flow rate of 5 L (liter)/min through the adsorber 23 b, 400 W of heat on average is absorbed by the adsorber 23 b, and a maximum heat absorption rate is 600 W. In this event, the temperature of the cooling water discharged from the cooling water pipe 21 a in the evaporator 21 is 15° C.
Next, the flow rate of the cooling water supplied to the condenser 22 is set to 4 L/min. In this case, the temperature of the cooling water discharged from the condenser 22 is 27.4° C. When the flow rate of the cooling water supplied to the condenser 22 is set to 1 L/min to 2 L/min, the temperature of the cooling water discharged from the condenser 22 becomes 28.8° C. to 31.6° C.
Then, when the flow rate of the cooling water is set to 1 L/min or less, the temperature of the cooling water discharged from the condenser 22 becomes 34° C. In this event, occurrence of dew condensation inside the adsorber 23 b is confirmed by the dew condensation sensor 53 b. Therefore, the flow rate of the cooling water supplied to the condenser 22 is set back to 2 L/min.
As described above, the flow rate of the cooling water supplied to the condenser 22 is appropriately adjusted based on the presence or absence of dew condensation and a difference in cooling water temperature between the inlet side and outlet side of the condenser 22. As a result, it is confirmed that the cooling water discharged from the condenser 22 may be cooled using the outside air while avoiding the dew condensation in the adsorber 23 b. Note that when the cooling capacity of the air-cooling device 29 may be insufficient, the cooling capacity of the air-cooling device 29 may be improved by spraying a small amount of water onto the fins 29 a as described above.
(2. Second Embodiment) FIG. 8 is a schematic view illustrating an adsorption heat pump system according to a second embodiment.
The adsorption heat pump system illustrated in FIG. 8 includes two adsorption heat pumps 60 a and 60 b, a controller 70, air-cooling devices 81 and 84, a hot water supply source 82, a cooling water tank 83 and switching units 71 and 72. Note that although pumps are actually connected to the air-cooling devices 81 and 84, the hot water supply source 82 and the cooling water tank 83, respectively, FIG. 8 omits the illustration of those pumps.
Each of the adsorption heat pumps 60 a and 60 b includes an evaporator and condenser 61 and an adsorber 62. The insides of the adsorption heat pumps 60 a and 60 b are depressurized to about 1/100 atm to 1/10 atm, for example.
The evaporator and condenser 61 includes a heat-transfer pipe 63 through which cooling water passes and a tray 64 to store a refrigerant. The heat-transfer pipe 63 has plate fins 63 a provided thereto. A temperature sensor 75 a and a flow rate sensor 76 are disposed on the inlet side of the heat-transfer pipe 63, and a temperature sensor 75 b is disposed on the outlet side thereof.
The adsorber 62 includes a heat-transfer pipe 65 and an adsorbent 66. A temperature sensor 73 a and a flow rate sensor 74 are disposed on the inlet side of the heat-transfer pipe 65, and a temperature sensor 73 b is disposed on the outlet side thereof.
Note that although the adsorber 62 is disposed above the evaporator and condenser 61 in FIG. 8, the adsorber 62 may be disposed lateral to the evaporator and condenser 61. Also in this embodiment, water is used as the refrigerant enclosed in the adsorption heat pumps 60 a and 60 b.
Each of the air-cooling devices 81 and 84 includes a pipe with plate fins attached thereto and a blast fan for blowing the outside air toward the plate fins. The hot water supply source 82 supplies hot water heated by heat discharged from an electronic device or the like.
The cooling water tank 83 stores cooling water cooled by the adsorption heat pumps 60 a and 60 b. The cooling water stored in the cooling water tank 83 is used for room air conditioning, cooling of electronic devices, and the like.
The controller 70 controls the switching unit 72 to allow the adsorption heat pumps 60 a and 60 b to alternately carry out the adsorption process and the restoration process.
Hereinafter, description will be given of a method of driving the adsorption heat pumps in the adsorption heat pump system according to this embodiment. Here, it is assumed that, in an initial state, the adsorbent 66 in the adsorber 62 in the adsorption heat pump 60 a is in a moisture-adsorbing state, while the adsorbent 66 in the adsorber 62 in the adsorption heat pump 60 b is in a dried state.
In this case, the controller 70 controls the switching unit 71 to connect the adsorber 62 in the adsorption heat pump 60 a with the hot water supply source 82 and to connect the adsorber 62 in the adsorption heat pump 60 b with the air-cooling device 81. At the same time, the controller 70 controls the switching unit 72 to connect the evaporator and condenser 61 in the adsorption heat pump 60 a with the air-cooling device 84 and to connect the evaporator and condenser 61 in the adsorption heat pump 60 b with the cooling water tank 83.
Then, the hot water is supplied to the adsorber 62 in the adsorption heat pump 60 a and a water vapor is generated by evaporation of moisture adsorbed on the adsorbent 66. This water vapor is cooled into a liquid by the evaporator and condenser 61 and then stored in the tray 64.
Meanwhile, in the adsorption heat pump 60 b, moisture is adsorbed onto the adsorbent 66 in the adsorber 62 and thus the pressure inside the adsorption heat pump 60 b is reduced. Accordingly, the water stored in the tray 64 evaporates to deprive the heat-transfer pipe 63 of latent heat. As a result, the temperature of the cooling water passing through the heat-transfer pipe 63 is lowered.
After the elapse of a certain period of time, the controller 70 controls the switching unit 71 to connect the adsorber 62 in the adsorption heat pump 60 a with the air-cooling device 81 and to connect the adsorber 62 in the adsorption heat pump 60 b with the hot water supply source 82. At the same time, the controller 70 controls the switching unit 72 to connect the evaporator and condenser 61 in the adsorption heat pump 60 a with the cooling water tank 83 and to connect the evaporator and condenser 61 in the adsorption heat pump 60 b with the air-cooling device 84.
Then, in the adsorption heat pump 60 a, moisture is adsorbed onto the adsorbent 66 in the adsorber 62 and thus the pressure inside the adsorption heat pump 60 a is reduced. Accordingly, the water stored in the tray 64 evaporates to deprive the heat-transfer pipe 63 of latent heat. As a result, the temperature of the cooling water passing through the heat-transfer pipe 63 is lowered.
Meanwhile, the hot water is supplied to the adsorber 62 in the adsorption heat pump 60 b and a water vapor is generated by evaporation of moisture adsorbed on the adsorbent 66. This water vapor is cooled and condensed into a liquid by the evaporator and condenser 61 and then stored in the tray 64.
The low-temperature cooling water is continuously supplied to the cooling water tank 83 by the controller 70 controlling the switching units 71 and 72 at intervals of a certain period of time as described above.
The controller 70 acquires the temperatures of the cooling water or hot water on the inlet and outlet sides of the heat- transfer pipes 65 and 63 in the adsorption heat pumps 60 a and 60 b from the temperature sensors 73 a, 73 b, 75 a and 75 b, and the flow rates of the cooling water or hot water from the flow rate sensors 74 and 76. Then, the controller 70 adjusts the amount of cooling water to be supplied to the evaporator and condenser 61 from the air-cooling device such that the amount of heat adsorbed by the adsorber 62 carrying out the adsorption process becomes equal to the amount of condensation heat in the evaporator and condenser 61 carrying out the restoration process.
As in the case of the first embodiment, the adsorption heat pump system according to this embodiment also uses no large-size equipment such as a sprinkler cooling tower and thus may be used even in a small-scale facility.
All examples and conditional language recited herein are intended for the pedagogical purposes of aiding the reader in understanding the invention and the concepts contributed by the inventor to further the art, and are not to be construed as limitations to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although one or more embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.

Claims

What is claimed is:

1. An adsorption heat pump system comprising:

an adsorption heat pump including a condenser configured to condense a vapor of a refrigerant;

an air-cooling device configured to air-cool a coolant discharged from the condenser in the adsorption heat pump and to resupply the air-cooled coolant to the condenser; and

a controller configured to control a flow rate of the coolant to be supplied to the condenser according to a difference in temperature between the coolant supplied to the condenser and the coolant discharged from the condenser.

2. The adsorption heat pump system according to claim 1, wherein

the adsorption heat pump further includes an evaporator configured to generate a vapor of the refrigerant and a plurality of adsorbers disposed in parallel between the evaporator and the condenser, and

each of the plurality of adsorbers includes an adsorbent configured to adsorb the vapor of the refrigerant and a heat-transfer pipe through which hot water passes at intervals of a certain period of time.

3. The adsorption heat pump system according to claim 2, wherein

the controller controls the flow rate of the coolant to be supplied to the condenser such that the difference in temperature between the coolant supplied to the condenser and the coolant discharged from the condenser is equal to or higher than a preset temperature and no dew condensation occurs within the adsorber through which the hot water is passing.

4. The adsorption heat pump system according to claim 3, further comprising:

a sensor configured to detect whether or not there is dew condensation within each of the plurality of adsorbers,

wherein a signal outputted from the sensor is inputted to the controller.

5. The adsorption heat pump system according to claim 3, wherein

the controller controls the flow rate of the coolant to be supplied to the condenser such that an amount of heat adsorbed by the adsorber through which the hot water is passing becomes equal to an amount of condensation heat in the condenser.

6. The adsorption heat pump system according to claim 2, wherein

differential pressure-driven valves configured to be automatically opened and closed by a pressure difference are disposed between the evaporator and the plurality of adsorbers and between the condenser and the plurality of adsorbers.

7. The adsorption heat pump system according to claim 1, wherein

the air-cooling device includes a pipe through which the coolant passes, cooling fins attached to the pipe, a blast fan configured to blow outside air onto the cooling fins, and a spray pipe configured to spray water onto the cooling fins.

8. The adsorption heat pump system according to claim 1, wherein

the air-cooling device includes a pipe through which the coolant passes, cooling fins attached to the pipe, a blast fan configured to blow outside air onto the cooling fins, and a spray pipe configured to spray water between the cooling fins and the blast fan.

9. The adsorption heat pump system according to claim 2, wherein

the controller passes the hot water through the plurality of adsorbers in turn at the intervals of the certain period of time.

10. The adsorption heat pump system according to claim 1, wherein

the adsorbent contains at least one of activated carbon, silica gel and zeolite.

11. A method of driving an adsorption heat pump configured to cool a coolant discharged from a condenser in the adsorption heat pump by using an air-cooling device, comprising:

controlling a flow rate of the coolant to be supplied to the condenser such that a difference in temperature between the coolant supplied to the condenser and the coolant discharged from the condenser is equal to or more than a set value.

12. The method of driving an adsorption heat pump, according to claim 11, wherein

the air-cooling device is disposed outdoors.

13. The method of driving an adsorption heat pump, according to claim 11, wherein

the hot water is water heated by heat discharged from an electronic device.

14. The method of driving an adsorption heat pump, according to claim 11, wherein

the adsorption heat pump further includes an evaporator configured to generate a vapor of a refrigerant and a plurality of adsorbers disposed in parallel between the evaporator and the condenser, and

15. The method of driving an adsorption heat pump, according to claim 14, comprising:

controlling the flow rate of the coolant to be supplied to the adsorption heat pump such that the difference in temperature between the coolant supplied to the condenser and the coolant discharged from the condenser is equal to or higher than a preset temperature and no dew condensation occurs within the adsorber through which the hot water is passing.

16. The method of driving an adsorption heat pump, according to claim 15, further comprising:

controlling the flow rate of the coolant to be supplied to the condenser such that an amount of heat adsorbed by the adsorber having the hot water supplied thereto becomes equal to an amount of condensation heat in the condenser.

17. The method of driving an adsorption heat pump, according to claim 14, wherein