Single-stage cascade series single-effect lithium bromide absorption refrigeration heat pump unit

Abstract

The present invention relates to a single-stage cascade series single-effect lithium bromide absorption refrigeration / heat pump unit, belonging to the technical field of air-conditioning equipment. It includes: a circulating water pump (13), a first absorber (5) and a second evaporator (7) form a closed cycle; the lithium bromide solution flows through the generator (1), the single-effect absorber (14), the second absorber (8) and the first absorber (5); the high-temperature heat source flows through the generator (1); the low-temperature water flows in series through the single-effect evaporator (15) and the first evaporator (6); the medium-temperature water flows through the single-effect absorber (14), the second absorber (8) and the condenser (2). Before cooling the low-temperature water with the cascade refrigeration process, this unit connects in series a single-effect refrigeration that utilizes the high-temperature section of the low-temperature water and the low-temperature section of the medium-temperature water, thereby reducing the interval in which the low-temperature water needs to be cooled by the cascade refrigeration, and thus improving the COP of the entire unit.

Description

Technical Field

[0001] The present invention relates to a single-stage cascade series single-effect lithium bromide absorption refrigeration / heat pump unit, belonging to the technical field of air conditioning equipment. Background Art

[0002] Existing cascade single-effect lithium bromide absorption refrigeration / heat pump units (hereinafter referred to as cascade single-effect units, or units) are as follows Figure 1 As shown, it is composed of a generator 1, a condenser 2, a high-temperature heat exchanger 3, a low-temperature heat exchanger 4, a first absorber 5, a first evaporator 6, a second evaporator 7, a second absorber 8, a refrigerant pump 9, a refrigerant connecting pipe 10, a first solution pump 11, a second solution pump 12, a circulating water pump 13 and a control system (not shown in the figure) and pipes and valves connecting various components. Low-temperature water (cold water of a refrigeration unit or waste hot water of a heat pump unit, the same below) flows through the first evaporator 6 to cool down; medium-temperature water (cooling water of a refrigeration unit or hot water of a heat pump unit, the same below) flows through the second absorber 8 and the condenser 2 to heat up; a high-temperature driving heat source flows through the generator 1, releasing heat to drive the entire unit to operate; in addition, there is an internal circulating water driven by a circulating water pump 13, which circulates in a closed manner between the first absorber 5 and the second evaporator 7. When the unit is running, the refrigerant water pumped out by the refrigerant pump 9 and sprayed from the top of the first evaporator 6 absorbs the heat of the low-temperature water flowing through the heat transfer tube of the first evaporator 6, and enters the first absorber 5 after vaporization, and is absorbed by the lithium bromide concentrated solution therein, and releases heat to heat the circulating water flowing through the heat transfer tube of the first absorber 5; the circulating water with increased temperature is sent to the heat transfer tube of the second evaporator 7 by the circulating water pump 13, and is cooled by the refrigerant water sprayed from the top after being pumped out by the refrigerant pump 9, and returns to the first absorber 5 to absorb the heat released by the solution after the temperature is lowered, and the refrigerant water in the second evaporator 7 absorbs the heat and vaporizes and enters the second Absorber 8; the lithium bromide concentrated solution in the first absorber 5 absorbs the refrigerant vapor and becomes thinner in concentration. It is pumped out by the first solution pump 11 and enters the second absorber 8 after heat exchange and temperature increase through the low-temperature heat exchanger 4. After absorbing the refrigerant vapor generated by the second evaporator 7, the concentration decreases again (at the same time, heat is released to heat the medium-temperature water flowing through the heat transfer tube of the second absorber 8). Finally, it is pumped out by the second solution pump 12 and enters the generator 1 after heat exchange and temperature increase through the high-temperature heat exchanger 3 to be heated and concentrated by the high-temperature heat source. The concentrated concentrated solution is then heat exchanged and cooled through the high-temperature heat exchanger 3 and the low-temperature heat exchanger 4 and then returns to the first absorber 5 to absorb the refrigerant vapor. The concentrated refrigerant vapor enters the condenser 2, is cooled and condensed by the medium-temperature water, and the condensed refrigerant water returns to the second evaporator 7 and returns to the first evaporator 6 through the connecting pipe 11.

[0003] In the cascade single-effect unit, the heat extracted from the low-temperature water flowing through the first evaporator 6 first enters the closed-circulation water flowing through the first absorber 5, and then enters the medium-temperature water flowing through the second absorber 8 after the heat in the closed-circulation water is extracted in the second evaporator 7. That is to say, in order to extract the heat from the low-temperature water and enter the medium-temperature water, the cascade single-effect unit needs to consume the high-temperature driving heat source and use the lithium bromide absorption single-effect refrigeration principle to refrigerate the low-temperature water flowing through the first evaporator 6 (i.e., extract the heat therein, the same below), and also needs to consume the high-temperature driving heat source and use the lithium bromide absorption single-effect refrigeration principle to refrigerate the closed-circulation water flowing through the second evaporator 7. The heat released by the closed-circulation water in the second evaporator 7 (also called the cooling capacity) is the heat absorbed by it in the first absorber 5. For the lithium bromide absorption unit, the heat exchange in the absorber is about 1.2 times the cooling capacity of the corresponding evaporator. Therefore, in order to extract the heat from the low-temperature water and put it into the medium-temperature water, the cascade single-effect unit needs to consume a high-temperature driving heat source and use the lithium bromide absorption single-effect refrigeration principle to refrigerate the low-temperature water and the circulating water at the same time. The cooling capacity is about 2.2 times the heat of the low-temperature water. Assuming that the COP of the lithium bromide absorption single-effect refrigeration cycle is 0.8, the COP of the cascade single-effect unit is about 0.8÷2.2=0.364. If the COP of the cascade single-effect unit is to be improved, one way is to improve the efficiency (i.e., COP) of the single-effect refrigeration cycle as much as possible, such as increasing the heat exchange area to reduce the heat exchange end difference of the heat exchanger, etc. Another way is to reduce the refrigeration demand of the second evaporator 7. Summary of the invention

[0004] The object of the present invention is to provide a single-stage cascade series single-effect lithium bromide absorption refrigeration / heat pump unit, which can reduce the refrigeration demand of the second evaporator and improve the COP of the cascade single-effect unit.

[0005] The object of the present invention is achieved as follows: A single-stage cascade series single-effect lithium bromide absorption refrigeration / heat pump unit, comprising: a generator, a condenser, a high-temperature heat exchanger, a first absorber, a first evaporator, a second evaporator, a second absorber, a circulating water pump, a single-effect absorber, and a single-effect evaporator; the first evaporator and the first absorber are in one cavity and are equipped with a first solution pump, the second evaporator and the second absorber are in another cavity, and the refrigerant water of the first evaporator and the second evaporator is connected by a refrigerant water connecting pipe; the circulating water pump, the first absorber, and the second evaporator form a closed loop; the single-effect evaporator and the single-effect absorber are in one cavity; the single-effect evaporator and the first evaporator are arranged in series; the lithium bromide solution flows through the generator, the single-effect absorber, the second absorber, and the first absorber in series-parallel or in series; the refrigerant vapor generated by the concentration of the solution in the generator enters the condenser, and after condensation, it returns to the second evaporator and the first evaporator. The high-temperature heat source flows through the generator; the low-temperature water (the chilled water of the refrigeration unit or the surplus hot water of the heat pump unit, the same below) flows through the single-effect evaporator and the first evaporator in series; the medium-temperature water (the cooling water of the refrigeration unit or the hot water of the heat pump unit, the same below) flows through the single-effect absorber, the second absorber, and the condenser.

[0006] Further, after the medium-temperature water flows through the single-effect absorber, it flows through the second absorber in series first and then through the condenser. Or, after the medium-temperature water flows through the single-effect absorber, it first flows through the condenser and then flows through the second absorber in series; or, after the medium-temperature water flows through the single-effect absorber, it is divided into two paths and flows through the second absorber and the condenser in parallel.

[0007] The first solution pump extracts the dilute solution in the first absorber and the second absorber (the solutions of the first absorber and the second absorber are connected), sends it to the generator through the high-temperature heat exchanger, and the concentrated solution then enters the single-effect absorber and the first absorber in parallel through the high-temperature heat exchanger, and the solution in the single-effect absorber then enters the second absorber.

[0008] Or, the first solution pump extracts the dilute solution in the first absorber and the second absorber (the solutions of the first absorber and the second absorber are connected), sends it to the generator through the high-temperature heat exchanger, and the concentrated solution then enters the single-effect absorber and the second absorber in parallel through the high-temperature heat exchanger, and the solution in the single-effect absorber then enters the first absorber.

[0009] Or, the second absorber of the unit is equipped with a second solution pump (the solutions of the first absorber and the second absorber are not connected), the first solution pump extracts the dilute solution in the first absorber, sends it to the generator through the high-temperature heat exchanger, the concentrated solution then enters the single-effect absorber first through the high-temperature heat exchanger and then enters the second absorber, and the second solution pump then extracts the dilute solution in the second absorber and returns it to the first absorber.

[0010] Alternatively, except that the second absorber of the unit is equipped with a second solution pump (the solutions in the first absorber and the second absorber are not connected), the unit further includes a low-temperature heat exchanger. The second solution pump extracts the dilute solution from the second absorber and sends it to the generator via the high-temperature heat exchanger. The concentrated solution then enters the single-effect absorber through the high-temperature heat exchanger and the low-temperature heat exchanger first, and then enters the first absorber. The first solution pump then extracts the dilute solution from the first absorber and returns it to the second absorber via the low-temperature heat exchanger.

[0011] The beneficial effects of the present invention are as follows:

[0012] Compared with the existing cascade single-effect unit, the present invention adds a single-effect evaporator and a single-effect absorber. The low-temperature water is cooled in the single-effect evaporator before entering the first evaporator, and the medium-temperature water flows through the single-effect absorber before entering the second absorber. That is, before cooling the low-temperature water using the cascade refrigeration process, the present invention connects in series a single-effect refrigeration that utilizes the high-temperature section of the low-temperature water and the low-temperature section of the medium-temperature water, thereby reducing the interval in which the low-temperature water needs to be cooled using the cascade method. The refrigeration load of the low-temperature water in the first evaporator is reduced, which will lower the load of the second evaporator, and thus the COP of the entire unit can be improved.

[0013] Taking the inlet and outlet temperatures of the low-temperature water as 12 / 7 °C and the inlet and outlet temperatures of the medium-temperature water as 45 / 51 °C as an example, when using the existing cascade single-effect unit, its COP is only about 0.364. When using the unit of the present invention, the low-temperature water can be first cooled to 10 °C (the medium-temperature water flowing in and out of the single-effect absorber is about 45 / 46 °C) through the single-effect evaporator and the single-effect absorber, and then cooled to 7 °C in the first evaporator through the cascade method. That is, the 12 / 10 °C cooling of the low-temperature water is single-effect refrigeration, with a COP of about 0.8, and the 10 / 7 °C cooling of the low-temperature water is cascade refrigeration, with a COP of about 0.364. Therefore, its comprehensive COP is about 0.465, that is, the COP is increased by about 27.7%. Description of the Drawings

[0014] Figure 1 It is the working principle diagram of the conventional cascade single-effect lithium bromide absorption refrigeration / heat pump unit.

[0015] Figure 2 It is the working principle diagram of Example 1 of the single-stage cascade series single-effect lithium bromide absorption refrigeration / heat pump unit of the present invention.

[0016] Figure 3 It is the working principle diagram of Example 2 of the present invention.

[0017] Figure 4 It is the working principle diagram of Example 3 of the present invention.

[0018] Figure 5 It is the working principle diagram of Example 4 of the present invention.

[0019] Reference numerals in the drawings:

[0020] Generator 1, condenser 2, high-temperature heat exchanger 3, low-temperature heat exchanger 4, first absorber 5, first evaporator 6, second evaporator 7, second absorber 8, refrigerant pump 9, refrigerant connecting pipe 10, first solution pump 11, second solution pump 12, circulating water pump 13, single-effect absorber 14, single-effect evaporator 15.

[0021] Low-temperature water enters at A1 and exits at A2, medium-temperature water enters at B1 and exits at B2, heat source enters at C1 and exits at C2. Detailed implementation mode

[0022] To further understand the content of the present invention, the present invention will be described in detail with reference to the accompanying drawings.

[0023] Embodiment 1

[0024] The single-stage cascade series single-effect lithium bromide absorption refrigeration / heat pump unit involved in the present invention is shown in Figure 2, the unit is composed of a generator 1, a condenser 2, a high-temperature heat exchanger 3, a first absorber 5, a first evaporator 6, a second evaporator 7, a second absorber 8, a refrigerant pump 9, a refrigerant connecting pipe 10, a first solution pump 11, a circulating water pump 13, a single-effect absorber 14, a single-effect evaporator 15, as well as a control system and pipelines, valves, etc. connecting each component. The single-effect evaporator 15 and the single-effect absorber 14 are in one cavity, the first evaporator 6 and the first absorber 5 are in one cavity, the second evaporator 7 and the second absorber 8 are in another cavity, and the refrigerant water of the first evaporator 6 and the second evaporator 7 is connected by the refrigerant water connecting pipe 10. The low-temperature water flows through the single-effect evaporator 15 and the first evaporator 6 in series for cooling; the circulating water driven by the circulating water pump 13 circulates in a closed loop in the first absorber 5 (heating up) and the second evaporator 7 (cooling down); the medium-temperature water flows through the single-effect absorber 14, the second absorber 8 and the condenser 2 in series for heating up; the high-temperature driving heat source flows through the generator 1, releasing heat to drive the operation of the whole unit. When the unit is operating, the lithium bromide solution in the generator 1 is heated and concentrated by the high-temperature driving heat source. After the concentrated lithium bromide solution is cooled by heat exchange in the high-temperature heat exchanger 3, it enters the single-effect absorber 14 and the first absorber 5 in parallel from the top and drips down. The concentrated refrigerant vapor is cooled and condensed in the condenser 2 by the medium-temperature water and then enters the second evaporator 7, and enters the first evaporator 6 through the refrigerant connecting pipe 10. The refrigerant water in the first evaporator 6 is pumped out by the refrigerant pump 9 and drips down from the top of the single-effect evaporator 15, the first evaporator 6 and the second evaporator 7, respectively exchanging heat with the low-temperature water or the closed-loop circulating water flowing through its heat transfer tubes, reducing its temperature, and then vaporizing into refrigerant vapor and entering the single-effect absorber 14, the first absorber 5 or the second absorber 8 in the same cavity respectively. The lithium bromide concentrated solution dripping down from the top of the single-effect absorber 14 absorbs the refrigerant vapor therein, becomes thinner in concentration, and releases heat to heat the medium-temperature water flowing through its heat transfer tubes at the same time. After the solution concentration decreases, it enters the second absorber 8 to continue absorbing the refrigerant vapor therein, becomes thinner in concentration, and releases heat to heat the medium-temperature water flowing through it at the same time; the lithium bromide concentrated solution dripping down from the top of the first absorber 5 absorbs the refrigerant vapor therein, becomes thinner in concentration, and releases heat to heat the closed-loop circulating water flowing through it at the same time; the dilute solutions in the first absorber 5 and the second absorber 8 are pumped out by the first solution pump 11 again, heated and raised in temperature by heat exchange in the high-temperature heat exchanger 3, and then enter the generator 1 to be heated and concentrated by the high-temperature heat source again.

[0025] Figure 2 In the single-stage cascade series single-effect lithium bromide absorption refrigeration / heat pump unit shown, the medium-temperature water first flows through the single-effect absorber 14, then flows through the second absorber 8 in series first, and finally flows through the condenser 2; it can also be that it first flows through the single-effect absorber 14, then flows through the condenser 2 in series first, and finally flows through the second absorber 8; or it first flows through the single-effect absorber 14 in series, and then flows through the single-effect absorber 8 and the condenser 2 in two parallel branches.

[0026] Example 2

[0027] Refer to Figure 3 , the difference between this embodiment and Embodiment 1 is that the concentrated lithium bromide solution is divided into two paths. One path first absorbs refrigerant vapor in the single-effect absorber 14 and becomes diluted in concentration, then enters the first absorber 5, and absorbs refrigerant vapor again in the first absorber 5 and becomes further diluted in concentration. The other path enters the second absorber 8 to absorb refrigerant vapor and becomes diluted in concentration. After the two paths of solutions are combined, they are pumped out by the first solution pump 11.

[0028] Example 3

[0029] The single-stage cascade series single-effect lithium bromide absorption refrigeration / heat pump unit involved in the present invention, refer to Figure 4, the unit consists of a generator 1, a condenser 2, a high-temperature heat exchanger 3, a first absorber 5, a first evaporator 6, a second evaporator 7, a second absorber 8, a refrigerant pump 9, a refrigerant connecting pipe 10, a first solution pump 11, a second solution pump 12, a circulating water pump 13, a single-effect absorber 14, a single-effect evaporator 15, as well as a control system and pipelines, valves, etc. connecting each component. The single-effect evaporator 15 and the single-effect absorber 14 are in one cavity, the first evaporator 6 and the first absorber 5 are in one cavity, the second evaporator 7 and the second absorber 8 are in another cavity, and the refrigerant water of the first evaporator 6 and the second evaporator 7 is connected by the refrigerant water connecting pipe 10. Low-temperature water flows through the single-effect evaporator 15 and the first evaporator 6 in series for cooling; the circulating water driven by the circulating water pump 13 undergoes a closed-loop cycle in the first absorber 5 (heating up) and the second evaporator 7 (cooling down); medium-temperature water flows through the single-effect absorber 14, the second absorber 8 and the condenser 2 in series for heating up; the high-temperature driving heat source flows through the generator 1, releasing heat to drive the operation of the entire unit. When the unit is operating, the lithium bromide solution in the generator 1 is heated and concentrated by the high-temperature driving heat source. After being cooled by heat exchange in the high-temperature heat exchanger 3, the concentrated lithium bromide solution enters the single-effect absorber 14 from the top and drips down. The refrigerant vapor concentrated out is cooled and condensed in the condenser 2 by the medium-temperature water and then enters the second evaporator 7, and then enters the first evaporator 6 through the refrigerant connecting pipe 10. The refrigerant water in the first evaporator 6 is pumped out by the refrigerant pump 9 and drips down from the tops of the single-effect evaporator 15, the first evaporator 6 and the second evaporator 7, respectively exchanging heat with the low-temperature water or the closed-loop circulating water flowing through their heat transfer tubes to reduce its temperature, and then vaporizes into refrigerant vapor and enters the single-effect absorber 14, the first absorber 5 or the second absorber 8 in the same cavity respectively. The lithium bromide concentrated solution dripping down from the top of the single-effect absorber 14 releases heat to heat the medium-temperature water flowing through its heat transfer tubes while absorbing the refrigerant vapor in it and becoming thinner in concentration; after the solution concentration decreases, it enters the second absorber 8 to continue absorbing the refrigerant vapor in it, while releasing heat to heat the medium-temperature water flowing through it; after the solution absorbs the refrigerant vapor in the second absorber 8 and becomes thinner in concentration again, it is pumped out by the second solution pump 12 and sent into the first absorber 5 to absorb the refrigerant vapor again and release heat to heat the closed-loop circulating water flowing through it. After the solution becomes further thinner in concentration, it is pumped out by the first solution pump 11, heated up by heat exchange in the high-temperature heat exchanger 3 and then enters the generator 1 to be heated and concentrated by the high-temperature heat source again.

[0030] Figure 4 In the single-stage cascade series single-effect lithium bromide absorption refrigeration / heat pump unit shown, the medium-temperature water first flows through the single-effect absorber 14, then flows through the second absorber 8 in series first, and finally flows through the condenser 2; it can also be that it first flows through the single-effect absorber 14, then flows through the condenser 2 in series first, and finally flows through the second absorber 8; or it first flows through the single-effect absorber 14 in series and then flows through the single-effect absorber 8 and the condenser 2 in two parallel branches.

[0031] Embodiment 4

[0032] Refer to Figure 5 , the single-stage series cascade single-effect lithium bromide absorption refrigeration / heat pump unit involved in the present invention is composed of a generator 1, a condenser 2, a high-temperature heat exchanger 3, a low-temperature heat exchanger 4, a first absorber 5, a first evaporator 6, a second evaporator 7, a second absorber 8, a refrigerant pump 9, a refrigerant connecting pipe 10, a first solution pump 11, a second solution pump 12, a circulating water pump 13, a single-effect absorber 14, a single-effect evaporator 15, as well as a control system and pipelines, valves, etc. connecting various components. The single-effect evaporator 15 and the single-effect absorber 14 are in one cavity, the first evaporator 6 and the first absorber 5 are in one cavity, the second evaporator 7 and the second absorber 8 are in another cavity, and the refrigerant water of the first evaporator 6 and the second evaporator 7 is connected by a refrigerant water connecting pipe 10. Low-temperature water flows through the single-effect evaporator 15 and the first evaporator 6 in series for cooling; the circulating water driven by the circulating water pump 13 circulates in a closed loop in the first absorber 5 (heating up) and the second evaporator 7 (cooling down); medium-temperature water flows through the single-effect absorber 14, the second absorber 8 and the condenser 2 in series for heating up; the high-temperature driving heat source flows through the generator 1, releases heat to drive the operation of the whole unit. When the unit is operating, the lithium bromide solution in the generator 1 is heated and concentrated by the high-temperature driving heat source. After the concentrated lithium bromide solution is cooled by heat exchange through the high-temperature heat exchanger 3 and the low-temperature heat exchanger 4, it enters the single-effect absorber 14 and drips from the top. The concentrated refrigerant vapor is cooled and condensed in the condenser 2 by medium-temperature water and then enters the second evaporator 7, and enters the first evaporator 6 through the refrigerant connecting pipe 10. The refrigerant water in the first evaporator 6 is pumped out by the refrigerant pump 9 and drips from the tops of the single-effect evaporator 15, the first evaporator 6 and the second evaporator 7, respectively exchanges heat with the low-temperature water or the closed-loop circulating water flowing through its heat transfer tubes, reduces its temperature, and then vaporizes into refrigerant vapor and enters the single-effect absorber 14, the first absorber 5 or the second absorber 8 in the same cavity respectively. The lithium bromide concentrated solution dripping from the top of the single-effect absorber 14 absorbs the refrigerant vapor therein, releases heat to heat the medium-temperature water flowing through its heat transfer tubes while the concentration becomes thinner; after the solution concentration decreases, it enters the first absorber 5 to continue absorbing the refrigerant vapor therein, and at the same time releases heat to heat the closed-loop circulating water flowing through it; after the solution absorbs the refrigerant vapor in the first absorber 5 and the concentration becomes thinner again, it is pumped out by the first solution pump 11, heated by heat exchange through the low-temperature heat exchanger 4 and then enters the second absorber 8, absorbs the refrigerant vapor again and releases heat to heat the medium-temperature water flowing through it. After the solution concentration becomes further thinner, it is pumped out by the second solution pump 12, heated by heat exchange through the high-temperature heat exchanger 3 and then enters the generator 1 to be heated and concentrated again by the high-temperature heat source.

[0033] Figure 5In the shown single-stage series cascade single-effect lithium bromide absorption refrigeration / heat pump unit, the medium-temperature water first flows through the single-effect absorber 14, then in series first through the second absorber 8, and finally through the condenser 2; it can also be that it first flows through the single-effect absorber 14, then in series first through the condenser 2, and finally through the second absorber 8; or it first flows through the single-effect absorber 14 in series, and then branches into two paths to flow through the single-effect absorber 8 and the condenser 2 in parallel.

Claims

1. A single-stage cascaded series single-effect lithium bromide absorption refrigeration / heat pump unit, comprising: Generator (1), condenser (2), high-temperature heat exchanger (3), first absorber (5), first evaporator (6), second evaporator (7), second absorber (8) and circulating water pump (13); characterized in that: the circulating water pump (13), the first absorber (5) and the second evaporator (7) form a closed cycle; the unit further includes a single-effect absorber (14) and a single-effect evaporator (15), the single-effect evaporator (15) and the single-effect absorber (14) are in one cavity, the first evaporator (6) and the first absorber (5) are in one cavity, the second evaporator (7) and the second absorber (8) are in another cavity, the refrigerant water of the first evaporator (6) and the second evaporator (7) is connected by a refrigerant water connecting pipe (10); the single-effect evaporator (15) and the first evaporator (6) are connected in series; the lithium bromide solution flows through the generator (1), the single-effect absorber (14), the second absorber (8) and the first absorber (5); the high-temperature heat source flows through the generator (1); the low-temperature water flows through the single-effect evaporator (15) and the first evaporator (6) in series; the medium-temperature water flows through the single-effect absorber (14), the second absorber (8) and the condenser (2); After the medium-temperature water flows through the single-effect absorber (14), it first flows through the second absorber (8) in series and then through the condenser (2); or after the medium-temperature water flows through the single-effect absorber (14), it first flows through the condenser (2) and then through the second absorber (8) in series; or after the medium-temperature water flows through the single-effect absorber (14), it flows through the second absorber (8) and the condenser (2) in two parallel paths; The solutions of the first absorber (5) and the second absorber (8) are connected. The first solution pump (11) pumps out the dilute solution in the first absorber (5) and the second absorber (8), sends it to the generator (1) through the high-temperature heat exchanger (3), and the concentrated solution then enters the single-effect absorber (14) and the first absorber (5) in parallel through the high-temperature heat exchanger (3), and the solution of the single-effect absorber (14) then enters the second absorber (8); or the concentrated solution then enters the single-effect absorber (14) and the second absorber (8) in parallel through the high-temperature heat exchanger (3), and the solution of the single-effect absorber (14) then enters the first absorber (5).

2. A single-stage cascade series single-effect lithium bromide absorption refrigeration / heat pump unit according to claim 1, characterized in that: The unit further includes a second solution pump (12). The first solution pump (11) pumps out the dilute solution in the first absorber (5), sends it to the generator (1) through the high-temperature heat exchanger (3), and the concentrated solution then enters the single-effect absorber (14) first and then the second absorber (8) through the high-temperature heat exchanger (3). The second solution pump (12) then pumps out the dilute solution in the second absorber (8) and returns it to the first absorber (5).

3. A single-stage cascade series single-effect lithium bromide absorption refrigeration / heat pump unit according to claim 1, characterized in that: The unit further includes a second solution pump (12) and a low-temperature heat exchanger (4). The second solution pump (12) extracts the dilute solution from the second absorber (8), sends it to the generator (1) via the high-temperature heat exchanger (3). The concentrated solution then enters the single-effect absorber (14) via the high-temperature heat exchanger (3) and the low-temperature heat exchanger (4), and then enters the first absorber (5). The first solution pump (11) then extracts the dilute solution from the first absorber (5) and returns it to the second absorber (8) via the low-temperature heat exchanger (4).

4. A single-stage cascade series single-effect lithium bromide absorption refrigeration / heat pump unit according to claim 1, characterized in that: The low-temperature water is the chilled water of the refrigeration unit or the surplus hot water of the heat pump unit.

5. A single-stage cascade series single-effect lithium bromide absorption refrigeration / heat pump unit according to claim 1, characterized in that: The medium-temperature water is the cooling water of the refrigeration unit or the hot water of the heat pump unit.

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