A closed absorption heat pump system and an operation method thereof

Abstract

The present invention discloses a closed absorption heat pump system and an operation method, comprising: a first cavity for evaporating a refrigerant and diluting a concentrated solution in the first cavity into a dilute solution; a first solution heat exchanger connected to the first cavity for heating the dilute solution; the first solution heat exchanger is connected to a second cavity and a third cavity; the first cavity includes an evaporator and an absorber, the second cavity includes a generator and a condenser, and the third cavity includes an auxiliary generator and an auxiliary condenser; the second cavity and the third cavity are connected in parallel; the auxiliary condenser is used for preheating the dilute solution before the dilute solution enters the generator; after the dilute solution is preheated, it is concentrated into a concentrated solution by the generator, and after the concentrated solution enters the first solution heat exchanger for temperature reduction, it returns to the first cavity again; a concentration adjustment tank is arranged below the second cavity, and the volume of the refrigerant in the concentration adjustment tank is adjusted to adjust the solution concentration in the system.

Description

Technical Field

[0001] The present invention relates to the field of closed absorption heat pumps, and particularly to a closed absorption heat pump system and an operation method thereof. Background Art

[0002] In existing closed absorption heat pumps, water is generally used as the refrigerant and lithium bromide solution is used as the absorbent. When the unit operates, the concentration difference between the concentrated solution and the dilute solution is about 5%, and the concentration difference of the solution is relatively large, resulting in a relatively small overall circulation volume of the internal solution. Thus, the heat exchange effect of the solution heat exchanger can be better, and it is not necessary to consume too much driving heat source to heat the solution before entering the generator to saturation, thereby improving the energy efficiency ratio. However, such a design has the following defects:

[0003] 1. The boiling point rise is high, and the requirement for the driving heat source is higher. Otherwise, the generator needs to be enlarged, increasing the cost. After the circulation volume becomes small, it will become sensitive to changes in external parameters and can only adapt to operating conditions near the design conditions. When the actual operating conditions deviate greatly from the design conditions, the operating efficiency is low or even the unit cannot operate.

[0004] 2. At present, due to considerations of airtightness, the solution concentration of the closed absorption heat pump generally cannot be changed arbitrarily, which also exacerbates the poor adaptability to variable operating conditions. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a closed absorption heat pump system and an operation method thereof, including: a first cavity for evaporating the refrigerant and diluting the concentrated solution in the first cavity into a dilute solution; a first solution heat exchanger connected to the first cavity for heating the dilute solution; the first solution heat exchanger is connected to a second cavity and a third cavity; the second cavity includes a generator and a condenser, and the third cavity includes an auxiliary generator and an auxiliary condenser; the second cavity and the third cavity are in parallel; the auxiliary condenser is used to preheat the dilute solution before the dilute solution enters the generator; after the dilute solution is preheated, it is concentrated into the concentrated solution by the generator, and after the concentrated solution enters the first solution heat exchanger for temperature reduction, it returns to the first cavity again; a concentration adjustment tank is arranged below the second cavity, and the solution concentration in the system is adjusted by adjusting the volume of the refrigerant in the concentration adjustment tank; the first cavity is further connected with a refrigerant cooler for heating the dilute solution flowing out of the first cavity and at the same time reducing the temperature of the refrigerant entering the first cavity; a second solution heat exchanger is connected to the third cavity, the refrigerant cooler and the first cavity for heat exchange.

[0006] Preferably: the concentration adjustment tank is separated from the second cavity by a partition board and is communicated with the second cavity through an upper water pipe and a lower water pipe.

[0007] Preferably, one end of the water supply pipe disposed inside the concentration adjustment tank is connected to a condensate pump; one end of the drain pipe disposed inside the concentration adjustment tank is connected to a condensate valve.

[0008] Preferably, the first cavity includes an evaporator and an absorber. Waste heat water or refrigerant water enters the evaporator, and heat is transferred to the refrigerant.

[0009] Preferably, self-circulation pumps are installed on the evaporator, the absorber, the generator, and the auxiliary generator, and a pressure balance pipe is connected between the concentration adjustment tank and the second cavity.

[0010] Preferably, the generator is connected to a driving heat source inlet and a driving heat source outlet, and the driving heat source outlet is connected to the auxiliary generator.

[0011] Preferably, it further includes a plurality of valves and a plurality of pumps.

[0012] An operating method for a closed absorption heat pump system, the method comprising:

[0013] S1. Waste heat water or refrigerant water enters the evaporator, and heat is transferred to the refrigerant;

[0014] S2. The refrigerant evaporates into steam upon heating, and the waste heat water or refrigerant water flows out of the evaporator;

[0015] S3. The concentrated solution in the absorber absorbs the steam and is diluted into a dilute solution;

[0016] S4. The dilute solution is heated in the first solution heat exchanger, preheated through the auxiliary condenser, and finally enters the generator to be concentrated into the concentrated solution;

[0017] S5. The concentrated solution enters the first solution heat exchanger, exchanges heat with the dilute solution, and then returns to the absorber.

[0018] Preferably, the method further includes:

[0019] S6. The dilute solution in the absorber is heated through the refrigerant cooler, reheated through the second solution heat exchanger, and finally enters the auxiliary generator to be concentrated into the concentrated solution;

[0020] S7. The concentrated solution exchanges heat with the dilute solution through the second solution heat exchanger and then returns to the absorber;

[0021] S8. The generator and the auxiliary generator generate the refrigerant. After the refrigerant enters the condenser and the auxiliary condenser for condensation respectively, it enters the refrigerant cooler to be cooled down and then enters the evaporator, and then enters step S1.

[0022] Preferably, the method includes a solution concentration adjustment method:

[0023] Under stable operation conditions, close the condensate valve and the condensate pump;

[0024] When the solution concentration needs to be increased, open the condensate valve and keep the condensate pump closed. The refrigerant at the bottom of the condenser will enter the concentration adjustment tank along the down pipe, causing the liquid level in the concentration adjustment tank to rise. After the liquid level rises to the specified value, close the condensate valve;

[0025] When the solution concentration needs to be decreased, close the condensate valve and open the condensate pump. The refrigerant enters the condenser along the upper pipe. When the liquid level in the concentration adjustment tank drops to the specified value, close the condensate pump.

[0026] The technical effects and advantages of the present invention:

[0027] 1. Increase the solution circulation volume. Increasing the solution circulation volume can greatly enhance the system's performance maintaining ability under different working conditions. The concentration difference between the concentrated solution and the dilute solution of a conventional closed heat pump is about 4% - 5%, while that of the present invention is below 2%. While increasing the solution circulation volume, an auxiliary generator and a condenser are added in parallel with the original generator and condenser, and the heat of the auxiliary condenser is used to preheat the solution before entering the original generator, thus compensating for the problem of the decrease in the energy efficiency ratio caused by the increase in the circulation volume.

[0028] 2. Add a concentration adjustment tank below the generator and the condenser. By controlling the volume of the refrigerant in the concentration adjustment tank, the overall concentration can be adjusted, enabling adaptation to more working conditions. Description of the Drawings

[0029] Figure 1 is a schematic diagram of the system structure provided by an embodiment of the present application;

[0030] Figure 2 is a schematic diagram of the structure of the concentration adjustment tank provided by an embodiment of the present application.

[0031] In the figure:

[0032] 101. Waste heat source or chilled water inlet; 102. Waste heat source or chilled water outlet; 103. First heat production water or cooling water inlet; 104. First heat production water or cooling water outlet; 105. Driving heat source inlet; 106. First driving heat source outlet; 107. Second heat production water or cooling water inlet; 108. Second heat production water or cooling water outlet; 109. Second driving heat source outlet; 110. Dilute solution inlet; 111. Concentrated solution outlet; 112. Condensate outlet; 2. Evaporator; 3. Absorber; 401. First solution heat exchanger; 402. Second solution heat exchanger; 501. Generator; 502. Auxiliary generator; 601. Condenser; 602. Auxiliary condenser; 7. Concentration adjustment tank; 8. Refrigerant cooler; 901. Valve; 902. Condensate valve; 1001. Water pump; 1002. Condensate pump; 1003. Generation self - circulation pump; 11. Baffle; 12. Liquid baffle; 1301. Upper water pipe; 1302. Lower water pipe; 14. Pressure balance pipe. Detailed implementation manners

[0033] The present invention will be further described in detail below in conjunction with the drawings and specific implementation manners. The embodiments of the present invention are given for the purpose of illustration and description, and are not exhaustive or limit the present invention to the disclosed form. Many modifications and variations are obvious to those of ordinary skill in the art. The embodiments are selected and described to better illustrate the principles and practical applications of the present invention, and enable those of ordinary skill in the art to understand the present invention and thus design various embodiments with various modifications suitable for specific purposes.

[0034] Please refer to Figure 1 , in this embodiment, a closed - type absorption heat pump system is provided, including: a first cavity for evaporating a refrigerant and diluting the concentrated solution in the first cavity into a dilute solution. In this embodiment, the first cavity includes an evaporator 2 and an absorber 3. The evaporator 2 is connected with a waste heat source or chilled water inlet 101 and a waste heat source or chilled water outlet 102, and the absorber 3 is connected with a first heat production water or cooling water inlet 103 and a first heat production water or cooling water outlet 107;

[0035] The first solution heat exchanger 401 is connected to the first cavity for heating the dilute solution. In this embodiment, the upper left and lower right of the first solution heat exchanger 401 are the same fluid, and the lower left and upper right are the same fluid;

[0036] The first solution heat exchanger 401 connects the second chamber and the third chamber. The second chamber and the third chamber are in parallel. In this embodiment, the second chamber includes a generator 501 and a condenser 601, and the third chamber includes an auxiliary generator 502 and an auxiliary condenser 602 to increase the system circulation volume. The generator 501 is connected to a driving heat source inlet 105 and a driving heat source outlet 106. The driving heat source outlet 106 is connected to the auxiliary generator 502. The condenser 601 is connected to a second hot water or cooling water inlet 107 and a second hot water or cooling water outlet 108;

[0037] The auxiliary condenser 602 is used to preheat the dilute solution before it enters the generator 501, compensating for the problem of reduced energy efficiency ratio caused by the increased circulation volume;

[0038] After the dilute solution is preheated, it is concentrated into a concentrated solution by the generator 501. After the concentrated solution enters the first solution heat exchanger 401 for temperature reduction, it returns to the first chamber again;

[0039] The first chamber is also connected to a refrigerant cooler 8 to heat the dilute solution flowing out of the first chamber, and at the same time reduce the temperature of the refrigerant entering the evaporator to increase the overall efficiency; a second solution heat exchanger 402, which is connected to the third chamber, the refrigerant cooler 8 and the first chamber for heat exchange. A bypass pipeline is provided between the second solution heat exchanger 402 and the refrigerant cooler 8 to increase the circulation volume. In this embodiment, the upper left and lower right of the second solution heat exchanger 402 are the same fluid, and the lower left and upper right are the same fluid; The evaporator 2, absorber 3, generator 501 and auxiliary generator 502 are all equipped with a self-circulation pump 1003, which pumps out the solution from the bottom of the equipment and sprays it down from the top. A pressure balance pipe 14 is connected between the concentration adjustment tank 7 and the second chamber.

[0040] The concentration adjustment tank 7 is arranged below the second chamber, separated from the second chamber by a partition, and communicates with the second chamber through a water supply pipe 1301 and a water discharge pipe 1302. One end of the water supply pipe 1301 arranged in the concentration adjustment tank 7 is connected to a condensate pump 1002; One end of the water discharge pipe 1302 arranged in the concentration adjustment tank 7 is connected to a condensate valve 902. By adjusting the refrigerant volume in the concentration adjustment tank 7, the solution concentration in the system is adjusted. Specifically:

[0041] Under stable operation conditions, both the condensate valve 902 and the condensate pump 1002 are in the closed state;

[0042] When the solution concentration needs to be increased, open the condensate valve 902 and keep the condensate pump 1002 closed. Since there is a pressure balance pipe 14 connecting the top of the concentration adjustment tank 7 and the top of the condenser 601, the upper and lower pressures are basically the same. Under the action of gravity, the refrigerant at the bottom of the condenser 601 will enter the concentration adjustment tank 7 along the drain pipe 1302, causing the liquid level of the concentration adjustment tank 7 to rise. After the liquid level rises to the specified value, close the condensate valve 902. At this time, since the volume of the refrigerant in the concentration adjustment tank 7 increases, the solvent of the externally circulated absorbent decreases, and the concentration will increase.

[0043] When the solution concentration needs to be decreased, keep the condensate valve 902 closed and open the condensate pump 1002. The refrigerant enters the condenser 601 through the water supply pipe 1301. When the liquid level of the concentration adjustment tank 7 drops to the specified value, close the condensate pump 1002. At this time, the volume of the refrigerant in the concentration adjustment tank 7 decreases, and the solvent of the externally circulated solution increases, resulting in a decrease in concentration.

[0044] The system includes multiple valves 901 and multiple pumps 1001 to control the flow direction of the fluid. When it is necessary to reduce the circulation volume of the system to adapt to more usage scenarios, by controlling the multiple valves 901 and multiple pumps 1001, the channels of the third cavity and the second solution heat exchanger 402 are closed, and the auxiliary generation loop returns to the absorber 3 only through the refrigerant cooler 8. The generator 501, the condenser 601, and the solution heat exchanger 2 are no longer used.

[0045] The system includes multiple fluid flow paths: a waste heat source or refrigerant water flow path, a solution flow path, a driving heat source flow path, and a refrigerant flow path. In the waste heat source or refrigerant water flow path, the waste heat source or refrigerant water flows through the waste heat source or refrigerant water inlet 101 to the evaporator 2 and then flows out through the waste heat source or refrigerant water outlet 102. The solution flow path includes a normal circuit and an auxiliary circuit. In the normal circuit, starting from the absorber 3, the solution in the absorber 3 absorbs the refrigerant vapor and becomes dilute. Then, one path is heated by the first solution heat exchanger 401 and further heated by the auxiliary condenser 602, and then enters the generator 501 to absorb the heat of the driving heat source for concentration, becoming a concentrated solution. After that, it is cooled by the first solution heat exchanger 401 and returns to the absorber 3. In the auxiliary circuit, starting from the absorber 3, the solution in the absorber 3 absorbs the refrigerant vapor and becomes dilute. Then, the other path is heated by the refrigerant cooler 8 and further heated by the second solution heat exchanger 402, and then enters the auxiliary generator 502 to be heated by the driving heat source for concentration. After that, it is cooled by the second solution heat exchanger 402 and returns to the absorber 3. The driving heat source flow path first passes through the generator 501 and then through the auxiliary generator 502, releasing heat twice and then exiting the system. In the refrigerant flow path, the refrigerant generated in the generator 501 and the auxiliary generator 502 enters the condenser 601 and the auxiliary condenser 602 respectively for condensation. After that, they are collected together and enter the refrigerant cooler 8. After the temperature drops, they enter the evaporator 2, absorb heat in the evaporator 2 and evaporate into refrigerant vapor, and then enter the absorber 3 to be absorbed by the solution.

[0046] The present invention also provides an operating method for a closed absorption heat pump system, and the method includes:

[0047] S1. The waste hot water or refrigerant water enters the evaporator 2 and transfers heat to the refrigerant.

[0048] S2. The refrigerant is heated and evaporated into vapor, and the waste hot water or refrigerant water flows out of the evaporator 2.

[0049] S3. The concentrated solution in the absorber 3 absorbs the vapor and is diluted into a dilute solution.

[0050] S4. The dilute solution is heated in the first solution heat exchanger 401, preheated by the auxiliary condenser 602, and finally enters the generator 501 to be concentrated into the concentrated solution.

[0051] S5. The concentrated solution enters the first solution heat exchanger 401, exchanges heat with the dilute solution, and then returns to the absorber 3.

[0052] S6. The dilute solution in the absorber 3 is heated by the refrigerant cooler 8, heated again by the second solution heat exchanger 402, and finally enters the auxiliary generator 502 to be concentrated into the concentrated solution.

[0053] S7. After the concentrated solution exchanges heat with the dilute solution through the second solution heat exchanger 402, it returns to the absorber 3;

[0054] S8. The generator 501 and the auxiliary generator 502 generate the refrigerant. After the refrigerant enters the condenser 601 and the auxiliary condenser 602 for condensation respectively, it enters the refrigerant cooler 8 to be cooled and then enters the evaporator 2, and enters step S1.

[0055] It further includes a solution concentration adjustment method:

[0056] Under stable operation conditions, close the condensate valve 902 and the condensate pump 1002;

[0057] When the solution concentration needs to be increased, open the condensate valve 902 and keep the condensate pump 1002 closed. The refrigerant at the bottom of the condenser 601 will enter the concentration adjustment tank 7 along the downpipe 1302, causing the liquid level of the concentration adjustment tank 7 to rise. After the liquid level rises to the specified value, close the condensate valve 902;

[0058] When the solution concentration needs to be decreased, close the condensate valve 902 and open the condensate pump 1002. The refrigerant enters the condenser 601 through the upper pipe 1301. When the liquid level of the concentration adjustment tank 7 drops to the specified value, close the condensate pump 1002.

[0059] Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art and related fields without creative efforts shall fall within the protection scope of the present invention. The structures, devices, and operation methods not specifically described and explained in the present invention shall be implemented by conventional means in the art without special instructions and limitations.

Claims

1. A closed absorption heat pump system, characterized in that, Comprising: A first cavity, the first cavity including an evaporator (2) and an absorber (3), for evaporating a refrigerant and diluting a concentrated solution in the first cavity into a dilute solution. The refrigerant is evaporated by entering the evaporator (2) with surplus hot water or chilled water, and the heat is transferred to the refrigerant. A first solution heat exchanger (401) connected to the first cavity, for heating the dilute solution. The first solution heat exchanger (401) is connected to a second cavity and a third cavity. The second cavity includes a generator (501) and a condenser (601), and the third cavity includes an auxiliary generator (502) and an auxiliary condenser (602). The second cavity and the third cavity are in parallel. The auxiliary condenser (602) is used for preheating the dilute solution before the dilute solution enters the generator (501). After the dilute solution is preheated, it is concentrated into the concentrated solution by the generator (501). After the concentrated solution enters the first solution heat exchanger (401) for cooling, it returns to the first cavity again. A concentration adjustment tank (7), arranged below the second cavity, for adjusting the concentration of the dilute solution or the concentrated solution in the system by adjusting the volume of the refrigerant in the concentration adjustment tank (7). The first cavity is further connected with a refrigerant cooler (8), for heating the dilute solution flowing out of the first cavity and simultaneously reducing the temperature of the refrigerant entering the first cavity. A second solution heat exchanger (402), connected to the third cavity, the refrigerant cooler (8) and the first cavity, for heat exchange. The mass concentration difference between the solutes of the dilute solution and the concentrated solution is below 2%. The solution in the absorber (3) absorbs the refrigerant vapor and becomes dilute. Then, another path passes through the refrigerant cooler (8) to be heated up, enters the second solution heat exchanger (402) to be further heated up, and then enters the auxiliary generator (502) to be concentrated by the heating of the driving heat source. After that, it passes through the second solution heat exchanger (402) to be cooled down and then returns to the absorber (3). The driving heat source flow path first passes through the generator (501) and then through the auxiliary generator (502), and releases heat twice before leaving the system. For the refrigerant flow path, the refrigerant generated in the generator (501) and the auxiliary generator (502) respectively enters the condenser (601) and the auxiliary condenser (602) for condensation. After that, they are collected together and enter the refrigerant cooler (8). After the temperature is reduced, they enter the evaporator (2), absorb heat in the evaporator (2) and evaporate into refrigerant vapor, and enter the absorber (3) to be absorbed by the solution.

2. The closed absorption heat pump system according to claim 1, characterized in that, The concentration adjustment tank (7) is separated from the second cavity by a partition, and is communicated with the second cavity through an upper water pipe (1301) and a lower water pipe (1302).

3. The closed absorption heat pump system according to claim 2, characterized in that, One end of the upper water pipe (1301) arranged in the concentration adjustment tank (7) is connected with a condensate pump (1002); one end of the lower water pipe (1302) arranged in the concentration adjustment tank (7) is connected with a condensate valve (902).

4. The closed absorption heat pump system according to claim 1, characterized in that, The evaporator (2), the absorber (3), the generator (501) and the auxiliary generator (502) are all equipped with a self-circulating pump (1003), and a pressure balance pipe (14) is connected between the concentration adjustment tank (7) and the second cavity.

5. A closed absorption heat pump system according to claim 1, characterized in that, The generator (501) is connected with a driving heat source inlet (105) and a driving heat source outlet (106), and the driving heat source outlet (106) is connected to the auxiliary generator (502).

6. The closed absorption heat pump system according to claim 1, wherein It further includes a plurality of valves (901) and a plurality of water pumps (1001).

7. An operating method for a closed absorption heat pump system, characterized in that, The method is applicable to the heat pump system described in claim 3 above, and includes: S1. The surplus hot water or refrigerant water enters the evaporator (2) and transfers heat to the refrigerant. S2. The refrigerant evaporates into steam by heating, and the surplus hot water or refrigerant water flows out of the evaporator (2). S3. The concentrated solution in the absorber (3) absorbs the steam and is diluted into a dilute solution. S4. The dilute solution is heated in the first solution heat exchanger (401), preheated by the auxiliary condenser (602), and finally enters the generator (501) to be concentrated into the concentrated solution. S5. The concentrated solution enters the first solution heat exchanger (401), exchanges heat with the dilute solution, and then returns to the absorber (3).

8. The operating method of a closed absorption heat pump system according to claim 7, characterized in that, The method further includes: S6. The dilute solution in the absorber (3) is heated by the refrigerant cooler (8), reheated by the second solution heat exchanger (402), and finally enters the auxiliary generator (502) to be concentrated into the concentrated solution. S7. The concentrated solution exchanges heat with the dilute solution through the second solution heat exchanger (402) and then returns to the absorber (3). S8. The generator (501) and the auxiliary generator (502) generate the refrigerant. The refrigerant enters the condenser (601) and the auxiliary condenser (602) respectively for condensation, then enters the refrigerant cooler (8) to be cooled down and then enters the evaporator (2) to enter step S1.

9. The operating method of a closed absorption heat pump system according to claim 8, characterized in that The method includes a solution concentration adjustment method: Under stable operation conditions, close the condensate valve (902) and the condensate pump (1002). When the solution concentration needs to be increased, open the condensate valve (902) and keep the condensate pump (1002) closed. The refrigerant at the bottom of the condenser (601) will enter the concentration adjustment tank (7) along the down pipe (1302), causing the liquid level of the concentration adjustment tank (7) to rise. After the liquid level rises to the specified value, close the condensate valve (902). When the solution concentration needs to be decreased, close the condensate valve (902), open the condensate pump (1002), the refrigerant enters the condenser (601) along the upper pipe (1301), and when the liquid level of the concentration adjustment tank (7) drops to the specified value, close the condensate pump (1002).

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