JPH09243195A - Absorption type heat pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance a heat collection rate in a GAX unit (absorption type regenerative heat exchanger) of an absorption type heat pump and inhibit an increase in the cost accompanying the improvement in the heat collection rate. SOLUTION: A vaporizer is classified into two types: or more particularly, a low temperature vaporizer 35a and a high temperature vaporizer 35b where the low temperature vaporizer 35a vaporizes refrigerants at a temperature required to provide a specified cool water and the high temperature vaporizer vaporizes refrigerants at a higher temperature. An absorber is classified into two types: One is a high pressure absorber 50b, which is internally furnished with a GAX unit (absorption regenerative heat exchanger) is connected to the high temperature vaporizer while the other is a tow temperature absorber 50a which is connected to the low temperature absorber 35a. The bottom of the high pressure absorber 50b is connected to a spray device 51a, which is internally furnished with the top of the low pressure absorber 50a by way of a pressure reducing valve 59 and refrigerant vapor generated at the high temperature vaporizer 35b is introduced to the high pressure absorber 50b while refrigerant vapor generated at the low temperature vaporizer 35a is introduced to the low pressure absorber 50a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an absorption heat pump, and more particularly to GAX (Generator-Absorber Heat).
Exchanger: Absorption-type heat pump that applies a cycle of absorption and regeneration.

[0002]

2. Description of the Related Art The GAX cycle is well known as a method for improving the efficiency of an absorption refrigeration cycle using ammonia as a refrigerant and water as an absorbent.
There is an example disclosed in Japanese Patent No. 3526. The absorption heat pump disclosed in the publication has a temperature at which the temperature of the heating-side fluid and the temperature of the heated-side fluid overlap due to heat exchange in the GAX unit (heat exchange unit that gives heat of the absorber to the generator). As a method of increasing the area, a method is used in which the refrigerant vapor generated in the evaporator is mechanically compressed using a compressor before being supplied to the absorber. The effect is shown in FIG. The pressure before the refrigerant vapor is compressed is P ₁ , and the pressure after the compression is P ₂ . The overlapping temperature range when the refrigerant vapor is not compressed is smudging, and the overlapping temperature range when the refrigerant vapor is compressed is hatched.
Shown respectively.

The temperature range shown by in the figure is the temperature range in which heat can be exchanged on the generator side when the compressor is not used, and the temperature range shown by is the temperature where heat can be exchanged on the absorber side when the compressor is not used. Range, the temperature range indicated by is the temperature range where heat can be exchanged on the generator side when using a compressor, the temperature range shown by is the temperature range where heat can be exchanged on the absorber side when using a compressor, Respectively. As can be understood from this figure, by mechanically increasing the pressure of the absorber, the temperature range where the temperature of the heating side fluid and the temperature of the heated side fluid overlap during heat exchange between the absorber and the generator. Can be increased, which in turn increases the amount of heat exchange between the absorber and the generator. Japanese Patent Application Laid-Open No. 6-174323 discloses a similar device.

[0004]

However, in this method, since the pressure of the absorber is increased by using the compressor, the compressor and its operating power are required.

The problem to be solved by the present invention is to increase the heat recovery rate in the GAX (absorption / regeneration heat exchanger) of an absorption heat pump and to suppress the increase in cost associated therewith.

[0006]

A first means of the present invention is as follows.
In order to solve the above problems, a strong solution having a high refrigerant concentration, which is obtained by absorbing a refrigerant into an absorbent, is introduced, and a regeneration unit that separately generates the strong solution into a refrigerant vapor and a weak solution having a low refrigerant concentration, A condenser that cools the refrigerant vapor generated in the regeneration unit into a liquid refrigerant and a liquid refrigerant generated in this condenser are introduced through an expansion valve, and the liquid refrigerant is evaporated by heat exchange with a heat medium. The evaporator to be introduced, the refrigerant vapor evaporated in this evaporator and the weak solution generated in the regeneration unit are introduced, and an absorption unit that absorbs the refrigerant vapor in the weak solution to generate a strong solution, and this absorption unit In an absorption heat pump including a solution pump that supplies the generated strong solution to the regeneration unit, the evaporator includes at least two evaporators that evaporate a refrigerant at different temperatures, and the absorption unit And a high-pressure side absorber in which the weak solution spraying device and a heat exchange flow path defined by a heat transfer wall below the spraying device are installed, and the high-pressure side absorber. A solution spraying device that is arranged below the solution sprayer and is connected to the bottom of the high-pressure side absorber via a pressure reducing valve, and a heat exchange flow path that is defined below the solution spraying device and that is defined by heat transfer walls. A low pressure side absorber that is internally installed, and is configured to include a strong solution in the heat exchange flow path of the high pressure side absorber, and cooling water to the heat exchange flow path of the low pressure side absorber, respectively, The solution pump is arranged by connecting the suction side to the low pressure side absorber bottom,
The refrigerant vapor evaporated in the high temperature side evaporator of the two evaporators is guided to the high pressure side absorber bottom, and the refrigerant vapor evaporated in the low temperature side evaporator is guided to the low pressure side absorber bottom. It is characterized by doing.

FIG. 2 shows an example of an NH ₃ --H ₂ O Duhring diagram in the case of the above configuration. An evaporator with a high evaporation temperature is a high temperature evaporator, and an evaporator with a low evaporation temperature is a low temperature evaporator. The pressure of the low temperature evaporator is Pa and the pressure of the high temperature evaporator is Pb. The area of smudging shows the heat exchange temperature area when there is one evaporator, and the area of hatching shows the heat exchange temperature area when the evaporator is divided into two evaporators with different evaporation temperatures (different pressures). ing. The temperature of the refrigerant evaporated in the low temperature evaporator (that is, the pressure of the low temperature evaporator) is set by the evaporator outlet temperature of the required cooling medium (for example, cold water). In this case, the temperature range of the weak solution flowing on the heating fluid side of the GAX part (outside the heat exchange flow path of the high-pressure side absorber) is from A to
The range of B, the temperature range of the strong solution flowing on the GAX part heated fluid side (in the heat exchange flow path of the high-pressure side absorber) is the range of C to D in FIG. 2.

On the other hand, if only the evaporator with pressure Pa is used, GA
The temperature range of the weak solution flowing on the part X heating fluid side (outside the heat exchange flow path of the high-pressure side absorber) is the range A ′ to B ′ in FIG.
The temperature range of the strong solution flowing on the part X heated fluid side (in the heat exchange flow path of the high-pressure side absorber) is the range C to D ′ in FIG.
It can be understood that the temperature range in which heat can be exchanged is expanded when two evaporators having different evaporation pressures (evaporation temperatures) are provided. By expanding the temperature range in which heat can be exchanged, the amount of heat exchanged in the GAX section is increased and the coefficient of performance is improved.

The second means of the present invention is the same as the above-mentioned first means, as a method of making the evaporation temperatures of the two evaporators different from each other, a branch pipe is provided on the downstream side of the expansion valve, and one of them is evaporated on the high temperature side. To the evaporator on the low temperature side through the pressure reducing valve,
They are connected to each other. The liquid refrigerant that evaporates after leaving the expansion valve and further decompressed by the decompression valve evaporates at a lower temperature than the liquid refrigerant that evaporates after exiting the expansion valve.

A third means of the present invention is the same as the first or second means, wherein a regenerator top is equipped with a partial condenser through which a strong solution pressurized by a solution pump flows, and a high pressure side absorber is installed. The strong solution that has passed through the dephlegmator is introduced into the heat exchange passage, and the cooling fluid flows through the heat exchange passage installed in the low pressure side absorber.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. FIG. 1 shows a system configuration diagram of an embodiment of an absorption heat pump according to the present invention. This embodiment is an example of an absorption heat pump using ammonia as a refrigerant and an absorbent as water. The illustrated absorption heat pump includes a regeneration unit 31, a condenser 32, a refrigerant heat exchanger 33, and an expansion valve 3.
4, a high temperature evaporator 35b, a low temperature evaporator 35a, an absorption unit 36, a solution pump 37, and pressure reducing valves 57, 59, 61.

The regeneration unit 31 includes a vertical regeneration container 38.
Inside, the regenerator 39, a weak solution heat exchanger 40, a rectifier 41 consisting of a recovery stage 41a and a concentration stage 41b, and a partial condenser 42 forming a heat exchange flow path are provided in this order from the bottom. Formed. The bottom of the regeneration vessel 38 is connected to the inlet side of the heat exchanger 40 by a pipe. With this playback unit 31,
Strong solution 55 (43b) supplied from solution pump 37
Is the refrigerant vapor 44 taken out from the top of the regeneration container 38.
And the weak solution 56 that collects at the bottom of the regeneration container 38 is separated.

The absorption unit 36 has a high pressure inside which is provided a heat exchange passage forming a spraying device 51b arranged at the top and an absorption heat recovery heat exchange part (that is, absorption regeneration heat exchanger) 52 arranged below the spraying device 51b. The side absorber 50b, the spraying device 51a arranged at the top, and the absorbing / dissipating part 5 arranged therebelow.
Low-pressure-side absorber 50a having a heat exchange flow path forming the inside 3
And a solution pipe 60 that connects the bottom of the high-pressure side absorber 50b to the spraying device 51a via the pressure reducing valve 59. The spraying device 51b is connected to the outlet side of the heat exchanger 40 via a pressure reducing valve 57, and the absorption heat recovery heat exchange section 5
The input side of 2 is connected to the output side of the divider 42. The suction side of the solution pump 37 is connected to the bottom of the low-pressure side absorber 50a, and the discharge side of the solution pump 37 is connected to the decompressor 42.
Is connected to the input side of. The outlet side of the absorption heat recovery heat exchange section 52 is connected between the recovery stage 41a and the concentration stage 41b of the rectifier 41.

The condenser 32 incorporates a heat exchange coil 45 through which a cooling fluid flows, the top portion is connected to the top portion of the regeneration unit 31, and the bottom portion is connected to the heating side fluid passage inlet of the refrigerant heat exchanger 33. .

The refrigerant heat exchanger 33 includes a heating side fluid flow path,
The low pressure side heated side fluid flow path and the high pressure side heated side fluid flow path are provided, and the outlet side of the low pressure side heated side fluid flow path is at the bottom of the low pressure side absorber 50a and the high pressure side heated side fluid flow. The outlet side of the passage is connected to the bottom of the high pressure side absorber 50b.

The high temperature evaporator 35b is constructed by incorporating a refrigerant distribution device 47b arranged at the top and a heat exchange coil 48b arranged below the refrigerant distribution device 47b and through which a cooling fluid flows, the refrigerant distribution device 47b. Refrigerant heat exchanger 3
3 is connected to the outlet side of the heating-side fluid flow path via an expansion valve 34. The high temperature evaporator 35b is also communicated with the high pressure side heated side fluid flow channel entering side of the refrigerant heat exchanger 33.

The low temperature evaporator 35a is constructed by internally mounting a refrigerant distribution device 47a arranged at the top and a heat exchange coil 48a arranged below the refrigerant distribution device 47a and through which a cooling fluid flows, the refrigerant distribution device 47a. It is connected to the outlet side of the expansion valve 34 via a pressure reducing valve 61. Low temperature evaporator 3
5a is also communicated with the low pressure side heated side fluid passage entry side of the refrigerant heat exchanger 33. The operation of the embodiment thus configured will be described below. Condenser 32
Introduces the refrigerant vapor 44 generated in the regeneration unit 31, cools it with the cooling fluid flowing through the heat exchange coil 45, and condenses it. Liquid refrigerant 46 condensed by the condenser 32
Is split into two through the refrigerant heat exchanger 33 and the expansion valve 34, and one of the two is sprayed onto the heat exchange coil 48b from the refrigerant spraying device 47b provided at the top of the high temperature evaporator 35b. The dispersed refrigerant deprives the heat of the cooling fluid flowing through the heat exchange coil 48b and evaporates, and this refrigerant vapor 49b passes through the refrigerant heat exchanger 33 and is introduced to the bottom of the high pressure side absorber 50b. The other of the two divided liquid refrigerants 46 is decompressed via the pressure reducing valve 61, and is transferred from the refrigerant distribution device 47a provided at the top of the low temperature evaporator 35a to the heat exchange coil 48a.
Sprinkled on top. The dispersed refrigerant is the heat exchange coil 48a.
The heat of the cooling fluid flowing in the refrigerant is evaporated and evaporated, and the refrigerant vapor 49a is introduced into the bottom portion of the low pressure side absorber 50a via the refrigerant heat exchanger 33. In the high temperature evaporator 35b, the refrigerant evaporates at a higher temperature pressure in the low temperature evaporator 35a.

The refrigerant vapor introduced into the bottom of the high-pressure side absorber 50b becomes a weak solution sprayed from the weak solution spraying device 51b on the heat transfer surface of the heat exchange passage forming the absorption heat recovery heat exchange section 52. The weak solution that has been absorbed and sprinkled increases the refrigerant concentration and accumulates at the bottom of the high-pressure side absorber 50b. The absorption heat generated by the absorption of the refrigerant vapor heats the strong solution 43b flowing inside the heat exchange channel and is recovered as a part of the heat necessary for regeneration. The weak solution accumulated at the bottom of the high-pressure side absorber 50b is guided to the spraying device 51a of the low-pressure side absorber 50a via the pressure reducing valve 59, and is sprayed onto the heat transfer surface of the heat exchange passage forming the absorption / radiation part 53. . The sprayed weak solution absorbs the refrigerant vapor from the low temperature evaporator 35a guided to the bottom of the low pressure side absorber 50a on the heat transfer surface of the heat exchange passage forming the absorption and heat dissipation part 53,
It becomes a strong solution and accumulates at the bottom of the low pressure side absorber 50a. The absorbed heat at this time is taken by the cooling fluid flowing through the heat exchange flow path of the absorption / radiation unit 53, and absorption is continuously performed.

The strong solution 43a accumulated at the bottom of the low pressure side absorber 50a is pressurized by the solution pump 37 and heated through the partial condenser 42 of the regeneration unit 31, and the heated strong solution 43b is absorbed by the absorption unit 36. Is introduced into the heat exchange passage from the lower inlet of the absorbed heat recovery heat exchange section 52. The strong solution 55 passing through the absorption heat recovery heat exchange section 52 is introduced into the middle stage of the rectifier 41 of the regeneration unit 31. The recycling container 3 is separated by the recycling process of the recycling unit 31.
The weak solution 56 collected at the bottom of 8 passes through the heat exchanger 40 and the pressure reducing valve 57 and is supplied to the weak solution spraying device 51b provided in the high pressure side absorber 50b.

In the absorption heat recovery heat exchange section 52, the strong solution 55 which has become a gas-liquid two-phase flow due to boiling flows from the upper outlet of the absorption heat recovery heat exchange section 52 to the rectifier 4 of the regeneration unit 31.
Sent to 1. The two-phase strong solution 55 introduced into the rectifier 41 is separated into a refrigerant vapor and a weak solution. The refrigerant vapor increases in concentration in the process of rising in the rectifier 41, and the vapor is further concentrated in the dephlegmator 42 by heat exchange with the low-temperature strong solution 43a to increase the concentration of the refrigerant vapor and supplied to the condenser 32. To be done. On the other hand, the strong solution has a reduced refrigerant concentration in the process of descending the rectifier 41, and when it passes through the weak solution heat exchanger 40 and the regenerative heat input device 39, it becomes a weak solution and accumulates at the bottom of the regenerating container 38.
As described above, it is supplied to the high pressure side absorber 50b. In this way, the absorption step and the regeneration step are repeatedly performed, and in the process, cold heat or hot heat is taken out of the system from the high temperature evaporator 35b, the low temperature evaporator 35a or the absorption / radiation unit 53.

Here, the change in temperature and pressure of the solution in the system will be described with reference to FIG.

A weak solution in the regeneration unit 38 (E in FIG. 2)
The point) is decompressed by the pressure reducing valve 57 and guided to the spraying device 51b of the high pressure side absorber 50b (point a in FIG. 2). Spraying device 5
The weak solution sprayed from 1b onto the heat transfer surface of the absorbed heat recovery heat exchange section 52 exchanges heat with the strong solution flowing in the heat exchange flow path of the absorbed heat recovery heat exchange section 52 while absorbing the refrigerant vapor. It is cooled and reaches the bottom of the high pressure side absorber 50b (b in FIG. 2).
point). The high pressure side absorber 50b is in communication with the high temperature evaporator 35b, and its pressure is the same as the pressure of the high temperature evaporator 35b.
b. The weak solution accumulated at the bottom of the high pressure side absorber 50b is decompressed by the pressure reducing valve 59 to the same Pa as the low temperature evaporator 35a, and flows into the spraying device 51a of the low pressure side absorber 50a (point f in FIG. 2). The weak solution sprayed from the spraying device 51a onto the heat transfer surface of the absorption / radiation unit 53 absorbs the refrigerant vapor introduced from the low-temperature evaporator 35a via the refrigerant heat exchanger 33, and the heat exchange flow of the absorption / radiation unit 53. It is cooled by exchanging heat with the cooling fluid flowing in the passage to become a strong solution, and the low pressure side absorber 50a.
Bottom (point g in FIG. 2).

The strong solution accumulated at the bottom of the low pressure side absorber 50a is pressurized by the solution pump 37, and the regeneration unit 3
1 through the partial condenser 42, and the absorption heat recovery heat exchange section 5
2 reaches the heat exchange channel inlet (point c in FIG. 2). The strong solution flowing into the heat exchange flow path of the absorbed heat recovery heat exchange section 52 is
Flowing while being heated by a weak solution flowing outside the heat exchange channel,
It becomes a gas-liquid two-phase and reaches the heat exchange passage outlet (d in FIG. 2).
point). The strong solution reaching the heat exchange channel outlet is regenerated by the regeneration unit 3
After being guided to 1 and separated into a solution and a vapor, the solution accumulates at the bottom of the regeneration unit 31 (point e in FIG. 2).

The solution circulates as described above to form a refrigeration cycle. In this refrigeration cycle, before the strong solution flows into the rectifier 41 of the regeneration unit 31, the absorption heat recovery heat exchange section 52 recovers the heat of the weak solution flowing outside thereof. In the present embodiment, the evaporator and the absorber are divided into two, and the high pressure side absorber 5 in which the absorbed heat recovery heat exchange section 52 is installed is installed.
By increasing the pressure of 0b, the weak solution temperature at the refrigerant vapor absorption start position outside the absorption heat recovery heat exchange unit 52 was increased, and the heat exchange temperature region in the absorption heat recovery heat exchange unit 52 could be widened.

The evaporator is composed of a high temperature evaporator and a low temperature evaporator, and the absorber is divided into a high pressure side absorber connected to the high temperature evaporator and a low pressure side absorber connected to the low temperature evaporator. The degree of improvement in the coefficient of performance (COP) was examined by simulation. The simulation was performed under the following temperature and pressure conditions.

[0026] For comparison, the temperature and pressure conditions of the cycle in which the evaporator was not divided into two evaporators that evaporate at different temperatures were the same as the above conditions. However, the conditions of the evaporator are the same as those of the low temperature evaporator and the absorber described above. FIG. 3 shows a Duhring diagram at this time.

As a result of the simulation, COP, 0.88 of the cycle in which the evaporator and the absorber were divided, and COP, 0.81 of the cycle in which the evaporator and the absorber were not divided were obtained. From this result, by dividing the evaporator and absorber under the above temperature and pressure conditions,
It was confirmed that the COP was improved by about 9%.

[0028]

According to the present invention, a low-temperature evaporator in which a refrigerant evaporates at a temperature required to obtain cold water at a desired temperature and a high-temperature evaporator in which a refrigerant evaporates at a higher temperature than that It is composed of two, and by dividing the absorber into a high pressure side absorber connected to the high temperature evaporator and a low pressure side absorber connected to the low temperature evaporator, without using power from a compressor or the like, In other words, GA without increasing the input
It is possible to raise the temperature of the weak solution for heat exchange in the X part (absorption heat recovery heat exchange part). Although the heat transfer area is increased by dividing the evaporator and the absorber, the amount of heat exchange in the GAX portion is increased, and COP is improved.

[Brief description of drawings]

FIG. 1 is a system diagram showing a main configuration of an embodiment of the present invention.

FIG. 2 is a Duhring diagram showing the principle of the present invention.

FIG. 3 is a Duhring diagram showing an example of the present invention.

FIG. 4 is a Dühring diagram showing an example of a conventional technique.

[Explanation of symbols]

31 Regeneration Unit 32 Condenser 33 Refrigerant Heat Exchanger 34 Expansion Valve 35a Low Temperature Evaporator 35b High Temperature Evaporator 36 Absorption Unit 37 Solution Pump 38 Regeneration Container 39 Regeneration Heater 40 Weak Solution Heat Exchanger 41 Fractioner 41a Recovery Stage 41b Condensing stage 42 Decompressor 43a, b Strong solution 44 Refrigerant vapor 45 Heat exchange coil 46 Liquid refrigerant 47a, b Refrigerant spraying device 48a, b Heat exchange coil 49a, b Refrigerant vapor 50a High pressure side absorber 50b Low pressure side absorber 51a , B Dispersing device 52 Absorption heat recovery heat exchange part 53 Absorption heat dissipation part 55 Strong solution 56 Weak solution 57 Pressure reducing valve 58 Weak solution 59 Pressure reducing valve 60 Solution piping 61 Pressure reducing valve

Claims (4)

[Claims] 1. A regeneration unit 31 for introducing a strong solution having a high refrigerant concentration, which is obtained by absorbing a refrigerant into an absorbent, and separating and producing the strong solution into a refrigerant vapor and a weak solution having a low refrigerant concentration, and the regeneration unit. A condenser that cools the refrigerant vapor generated in 1. to a liquid refrigerant, and introduces the liquid refrigerant generated in this condenser through an expansion valve, and evaporates the liquid refrigerant by heat exchange with a heat medium. And an absorption unit that introduces the refrigerant vapor evaporated in this evaporator and the weak solution generated in the regeneration unit, absorbs the refrigerant vapor in the weak solution to generate a strong solution, and is generated in this absorption unit. In an absorption heat pump including a solution pump that supplies a strong solution to the regeneration unit, the evaporator includes at least two evaporators that evaporate a refrigerant at different temperatures, and the absorption unit is A high-pressure side absorber in which the weak solution spraying device and a heat exchange passage defined and arranged by a heat transfer wall below the solution spraying device are installed, and below the high-pressure side absorber A solution spraying device that is arranged and connected to the bottom of the high-pressure side absorber via a pressure reducing valve, and a heat exchange flow path that is defined and arranged by a heat transfer wall below the solution spraying device are installed. A high pressure side absorber, a strong solution is introduced into the heat exchange flow path of the high pressure side absorber, and cooling water is introduced into the heat exchange flow path of the low pressure side absorber. Is arranged with the suction side connected to the low pressure side absorber bottom, and the refrigerant vapor evaporated in the high temperature side evaporator of the two evaporators is guided to the high pressure side absorber bottom part, and the low temperature side evaporator It is characterized in that the refrigerant vapor that has been vaporized in is introduced to the bottom of the low-pressure side absorber. Absorption heat pump to be. 2. A branch pipe is provided on the downstream side of the expansion valve, one of which is connected to the evaporator on the high temperature side, and the other is connected to the evaporator on the low temperature side via a pressure reducing valve. The absorption heat pump according to claim 1. 3. A dephlegmator in which a strong solution pressurized by a solution pump flows is installed at the top of the regeneration unit, and a heat exchange passage provided in a high pressure side absorber passes through the dephlegmator. The absorption type heat pump according to claim 1 or 2, wherein a strong solution is introduced and a cooling fluid flows through a heat exchange passage installed in the low pressure side absorber. 4. The absorption heat pump according to claim 1, wherein the refrigerant is ammonia and the absorbent is water.