Condensation device and carbon dioxide compression refrigeration system

Abstract

A condensation device for a carbon dioxide compression refrigeration system, and a carbon dioxide compression refrigeration system comprising same. The condensation device comprises: a generator, which receives gaseous carbon dioxide at a first temperature, and cools the gaseous carbon dioxide at the first temperature to gaseous carbon dioxide at a second temperature; an intermediate heat exchanger, which receives the gaseous carbon dioxide at the second temperature, and converts the gaseous carbon dioxide at the second temperature into gaseous carbon dioxide at a critical temperature; an evaporator, which enables the gaseous carbon dioxide at the critical temperature to be cooled by a refrigerant liquid to achieve condensation phase change, so that the gaseous carbon dioxide is converted into liquid carbon dioxide for discharge; a condenser; and an absorber.

Description

Condensing device and carbon dioxide compression refrigeration system

[0001] The present application claims priority to Chinese application CN2024212795583 filed on June 5, 2024 with the China National Intellectual Property Office. TECHNICAL FIELD

[0002] The present application relates to a condensing device for a carbon dioxide compression refrigeration system and a carbon dioxide compression refrigeration system comprising such a condensing device. BACKGROUND

[0003] The existing zero-carbon refrigeration system (CO2 system) on the market generally uses a transcritical CO2 compression refrigeration system in areas where the ambient temperature exceeds 31.1℃. The exhaust cooling device also generally uses a finned coil type air-cooled cooler. Such equipment operates in a supercritical condition when the air temperature is higher than 25℃. At this time, the COP value of the refrigeration system is smaller relative to the subcritical time, making it extremely difficult to promote the zero-carbon refrigeration system in subtropical and tropical regions.

[0004] With the increasingly serious "greenhouse effect", the high GWP value of the CFCS, HCFCS, and HFCS refrigerants widely used in the refrigeration field are first listed as elimination plans, and the excellent properties of CO2 are considered to be the most potential long-term alternative. SUMMARY

[0005] The purpose of the present application is to realize the subcritical operation of the CO2 compression refrigeration system without the aid of additional energy drive in the case of high temperature environment.

[0006] The application provides a condensing device for a carbon dioxide compression refrigeration system, comprising: a generator containing an absorbent solution, a first heat exchanger arranged in the generator, an inlet of the first heat exchanger being in fluid communication with a discharge outlet of a compressor of the carbon dioxide compression refrigeration system to receive gaseous carbon dioxide at a first temperature, so that the gaseous carbon dioxide at the first temperature heats the absorbent solution to increase the concentration of the absorbent solution, and the gaseous carbon dioxide at the first temperature is converted into gaseous carbon dioxide at a second temperature, the second temperature being lower than the first temperature; an intermediate heat exchanger fluidly connected to an outlet of the first heat exchanger to receive the gaseous carbon dioxide at the second temperature from the first heat exchanger, so that the gaseous carbon dioxide at the second temperature is converted into gaseous carbon dioxide at a critical temperature; an evaporator containing a refrigerant liquid, a second heat exchanger arranged in the evaporator, an inlet of the second heat exchanger being capable of receiving the gaseous carbon dioxide at the critical temperature from the intermediate heat exchanger, so that the gaseous carbon dioxide at the critical temperature is cooled by the refrigerant liquid to realize a condensation phase change, and is converted into liquid carbon dioxide to be discharged, while a part of the refrigerant liquid is converted into refrigerant vapor; a condenser, a third heat exchanger arranged in the condenser, the condenser being in fluid communication with the generator to receive the refrigerant vapor generated by the heated absorbent solution, an inlet of the third heat exchanger receiving cooling water from outside, so that the refrigerant vapor is condensed into the refrigerant liquid, the condenser also being in fluid communication with the evaporator to discharge the refrigerant liquid to the evaporator; an absorber, a fourth heat exchanger arranged in the absorber, the absorber being in fluid communication with the evaporator to receive the refrigerant vapor from the evaporator, the absorber also being in fluid communication with the generator to receive the absorbent solution with increased concentration, an inlet of the fourth heat exchanger receiving cooling water from outside to cool the refrigerant vapor to be converted into the refrigerant liquid, the refrigerant liquid being mixed with the absorbent solution with increased concentration to decrease the concentration of the absorbent solution, and the absorbent solution with decreased concentration being transported to the generator.

[0007] Advantageously, the intermediate heat exchanger comprises: a fifth heat exchanger arranged between the first heat exchanger and the second heat exchanger, for receiving the gaseous carbon dioxide at the second temperature from the outlet of the first heat exchanger, the absorbent solution with decreased concentration being transported from the absorber to the generator to pass through the fifth heat exchanger and exchange heat with the gaseous carbon dioxide at the second temperature, so that the gaseous carbon dioxide at the second temperature is converted into gaseous carbon dioxide at a third temperature, the third temperature being lower than the second temperature, and the inlet of the second heat exchanger receiving the gaseous carbon dioxide at the third temperature from an outlet of the fifth heat exchanger.

[0008] Advantageously, the intermediate heat exchanger further comprises a sixth heat exchanger arranged between the fifth heat exchanger and the second heat exchanger, an inlet of the sixth heat exchanger receiving cooling water from outside, the gas carbon dioxide at the third temperature passing through the sixth heat exchanger and exchanging heat with the cooling water, so that the gas carbon dioxide at the third temperature is converted into gas carbon dioxide at a critical temperature, the gas carbon dioxide at the critical temperature being delivered to the inlet of the second heat exchanger.

[0009] Advantageously, the evaporator further comprises a refrigerant pump configured to pump the remaining portion of the refrigerant liquid from the bottom of the evaporator to the top of the evaporator again.

[0010] Advantageously, the condensing device further comprises a seventh heat exchanger arranged between the generator and the absorber, an inlet of the seventh heat exchanger receiving the absorbent solution with increased concentration from the generator, and an outlet of the seventh heat exchanger being located at the top of the absorber, the absorbent solution with decreased concentration passing through the seventh heat exchanger from the bottom of the absorber, the absorbent solution with decreased concentration and the absorbent solution with increased concentration exchanging heat, so that the absorbent solution with decreased concentration is heated and further passes through the fifth heat exchanger.

[0011] Advantageously, the condensing device further comprises a first fan arranged between the generator and the condenser for delivering the refrigerant vapor generated by the heated absorbent solution to the condenser; and a second fan arranged between the evaporator and the absorber for delivering the refrigerant vapor in the evaporator to the absorber.

[0012] Advantageously, the first heat exchanger, the second heat exchanger, the third heat exchanger, the fourth heat exchanger, the fifth heat exchanger, and the seventh heat exchanger are any one of plate type, shell and tube type, and double pipe type.

[0013] Advantageously, the sixth heat exchanger is a water-cooled condenser or an air cooler.

[0014] Advantageously, the refrigerant is water, and the absorbent is lithium bromide.

[0015] The present application also provides a carbon dioxide compression refrigeration system, comprising: a compressor; and a condensing device as described above, the condensing device being used to condense the gas carbon dioxide discharged from the compressor into liquid carbon dioxide. BRIEF DESCRIPTION OF DRAWINGS

[0016] The above and other features and advantages of the exemplary embodiments of the present application will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, which are given by way of illustration and are not meant to be limiting of the present application, and of which:

[0017] FIG. 1 shows a schematic diagram of a condensing device according to the present application.

[0018] FIG. 2 shows a schematic diagram of a carbon dioxide compression refrigeration system according to the present application. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the technical solutions of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be described clearly and completely below in combination with the accompanying drawings of the embodiments of the present disclosure. The same reference signs in the drawings represent the same components. It should be noted that the described embodiments are part of the embodiments of the present disclosure, rather than all the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by those of ordinary skill in the art without any inventive effort fall within the scope of protection of the present disclosure.

[0020] Compared with the embodiments shown in the drawings, the feasible implementation solutions within the protection scope of the present disclosure can have fewer components, have other components not shown in the drawings, have different components, have differently arranged components or differently connected components, etc. In addition, two or more components in the drawings can be implemented in a single component, or a single component shown in the drawings can be implemented as a plurality of separate components.

[0021] Unless otherwise defined, technical terms or scientific terms used herein should be understood as having the common meaning in the field of the present disclosure to those having ordinary skill in the art. The terms "first", "second" and similar terms used in the specification and claims of the present disclosure do not denote any order, quantity or importance, but are used to distinguish different components. When the number of components is not specified, the number of components can be one or more; similarly, the terms "one", "the", "said" and the like do not necessarily mean a quantity limitation. The terms "comprise", "include" and the like mean that the elements or objects before the terms encompass the elements or objects listed after the terms and their equivalents, without excluding other elements or objects. The terms "upper", "lower", "left", "right" and the like only represent the relative positional relationship of the device in use or the positional relationship shown in the drawings, and when the absolute position of the described object changes, the relative positional relationship can also change accordingly.

[0022] Referring to FIG. 1, a schematic diagram of a condensing device for a carbon dioxide compression refrigeration system according to the present application is described.

[0023] The condensing apparatus comprises a generator 1, which is capable of containing an absorbent solution, a first heat exchanger provided in the generator, for example in the form of a heating coil of the first heat exchanger. The gaseous carbon dioxide at a first temperature (greater than 100°C) discharged from the discharge port of the compressor of the carbon dioxide compression refrigeration system enters the first heat exchanger, thereby exchanging heat with the absorbent solution, so that the gaseous carbon dioxide at the first temperature is cooled (first cooling) to gaseous carbon dioxide at a second temperature, while the absorbent solution is evaporated to produce refrigerant vapor, and the concentration of the absorbent solution is increased (i.e. a concentrated solution).

[0024] The gaseous carbon dioxide at the second temperature is converted to gaseous carbon dioxide at a critical temperature by an intermediate heat exchanger, and the gaseous carbon dioxide at the critical temperature is delivered to an evaporator 4. The evaporator 4 is capable of containing refrigerant liquid, and a second heat exchanger is provided in the evaporator 4. The gaseous carbon dioxide at the critical temperature enters the second heat exchanger, thereby exchanging heat with the refrigerant liquid in the evaporator, so that the gaseous carbon dioxide at the critical temperature is converted to liquid carbon dioxide, while a portion of the refrigerant liquid is evaporated to become refrigerant vapor. The remaining portion of the refrigerant liquid is located at the bottom of the evaporator, and can be pumped to the top of the evaporator by a refrigerant pump 4-1, thereby achieving circulation of the refrigerant liquid.

[0025] The refrigerant vapor can be delivered to the top of an absorber 5 by a second fan 4-2. In addition, the absorbent solution with increased concentration discharged from the generator 1 enters the absorber 5. A fourth heat exchanger is provided in the absorber 5, which receives cooling water from the outside, thereby converting the refrigerant vapor to refrigerant liquid, and the refrigerant liquid is mixed with the absorbent solution with increased concentration, so that the concentration of the absorbent solution is reduced (i.e. a dilute solution). The absorbent solution with reduced concentration can be delivered back to the generator, as described below.

[0026] The intermediate heat exchanger comprises a fifth heat exchanger 2 and a sixth heat exchanger 3. The fifth heat exchanger 2 is capable of receiving gaseous carbon dioxide at the second temperature from the first heat exchanger, and the absorbent solution with reduced concentration passes through the fifth heat exchanger, thereby exchanging heat with the gaseous carbon dioxide at the second temperature, so that the gaseous carbon dioxide at the second temperature is cooled (second cooling) to gaseous carbon dioxide at a third temperature, while the temperature of the absorbent solution with reduced concentration is increased.

[0027] The sixth heat exchanger 3 is provided downstream of the fifth heat exchanger 2, and the inlet of the sixth heat exchanger 3 receives cooling water from the outside. The gaseous carbon dioxide at the third temperature passes through the sixth heat exchanger, so that the cooling water and the gaseous carbon dioxide at the third temperature exchange heat exchangers, the gaseous carbon dioxide at the third temperature is converted (third cooling) to gaseous carbon dioxide at a critical temperature, and is delivered to the inlet of the second heat exchanger.

[0028] A seventh heat exchanger 6 is also provided between the generator 1 and the absorber 5, the concentration-increased absorbent solution from the generator 1 enters the inlet of the seventh heat exchanger 6, and the concentration-decreased absorbent solution from the absorber 5 is pumped through the seventh heat exchanger 6 via a solution pump 5-1, both of which exchange heat, so that the concentration-decreased absorbent solution is increased in temperature, and the concentration-increased absorbent solution is decreased in temperature, and is optionally delivered to the top of the absorber via a shutoff valve 7. The concentration-decreased absorbent solution then passes through the fifth heat exchanger, as described above.

[0029] The refrigerant vapor from the generator 1 can be delivered to the condenser 9 via a first fan 9-1, and a third heat exchanger is provided in the condenser 9, which receives cooling water from the outside, so as to condense the refrigerant vapor into refrigerant liquid, and the refrigerant liquid is optionally delivered to the evaporator 4 via a shutoff valve 8.

[0030] The cooling water of the third heat exchanger and the sixth heat exchanger 3 can be returned to the cooling tower after heat exchange.

[0031] The first heat exchanger, the second heat exchanger, the third heat exchanger, the fourth heat exchanger, the fifth heat exchanger, and the seventh heat exchanger are any one of plate type, shell-and-tube type, and double-pipe type. The sixth heat exchanger is a water-cooled condenser or an air cooler.

[0032] Advantageously, the refrigerant is water, and the absorbent is lithium bromide.

[0033] An eighth heat exchanger 3-1 is also shown in FIG. 1, for example, in the form of an air-cooled air cooler. When the temperature is low (below 0°C) for a long time in winter, the carbon dioxide gas discharged by the compressor can be directly delivered to the eighth heat exchanger 3-1, and then condensed into liquid carbon dioxide. In other words, the eighth heat exchanger can replace the above-mentioned condensing device, so as to realize switching use in winter and summer.

[0034] FIG. 2 shows a schematic diagram of a carbon dioxide compression refrigeration system according to the present application. The carbon dioxide compression refrigeration system comprises a low-temperature compressor 10, a medium-temperature compressor 20, and a condensing device 30 as described above. Referring to FIG. 2, the carbon dioxide compression refrigeration system further comprises a regenerator 40, a medium-temperature expansion valve 70, a medium-temperature evaporator 50, a low-temperature expansion valve 80, a low-temperature evaporator 60, a liquid storage tank 90, an ejector 100, a bypass valve 110, and a medium-pressure valve 120.

[0035] The working process of the carbon dioxide compression refrigeration system is described below. The medium-temperature compressor 20 pressurizes the high-temperature and low-pressure carbon dioxide gas into high-temperature and high-pressure carbon dioxide gas, which is then delivered to the condensing device 30 as described above. After passing through the condensing device 30 as described above, the high-temperature and high-pressure carbon dioxide gas is converted into liquid carbon dioxide.

[0036] If the temperature of the liquid carbon dioxide is lower than the predetermined threshold, the bypass valve 110 is opened so that the liquid carbon dioxide passes through the bypass valve 110 to the ejector 100. If the temperature of the liquid carbon dioxide is not lower than the predetermined threshold, the bypass valve 110 is closed so that the liquid carbon dioxide passes through the bypass valve 110 to the regenerator 40 and then to the ejector 100.

[0037] After passing through the ejector 100, the temperature and pressure of the liquid carbon dioxide are reduced, and the liquid carbon dioxide enters the liquid storage tank 90 and is then delivered to the medium-temperature expansion valve 70 and the low-temperature expansion valve 80, respectively. After throttling expansion, the temperature and pressure are reduced again, and the liquid carbon dioxide exchanges heat with the medium-temperature evaporator 50 and the low-temperature evaporator 60. The low-temperature compressor 10 pressurizes the low-pressure carbon dioxide of the low-temperature evaporator and delivers the pressurized carbon dioxide to the medium-temperature compressor 20.

[0038] By means of the condensing device of the present application, the carbon dioxide compression refrigeration system utilizes the principle of lithium bromide absorption refrigeration to achieve a carbon dioxide refrigeration cycle in a subcritical state in a high-temperature environment (for example, in tropical and subtropical regions), thereby achieving the purpose of energy saving.

[0039] It will be obvious to a person skilled in the art that the present application is not limited to the details of the above-described exemplary embodiments, but that the present application can be implemented in other concrete forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, the scope of the present application being defined by the appended claims rather than the above description, and it is intended to embrace all changes and modifications that fall within the meaning and scope of the equivalent elements of the claims. Any reference signs in the claims should not be considered as limiting the claims involved.

[0040] In addition, it should be understood that, although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. A condensing apparatus for a carbon dioxide compression refrigeration system, characterized by, The condensing apparatus comprises: a generator containing an absorbent solution, a first heat exchanger disposed in the generator, an inlet of the first heat exchanger being fluidly connected to a discharge outlet of a compressor of a carbon dioxide compression refrigeration system to receive gaseous carbon dioxide at a first temperature, such that the gaseous carbon dioxide at the first temperature heats the absorbent solution to increase a concentration of the absorbent solution while the gaseous carbon dioxide at the first temperature is converted into gaseous carbon dioxide at a second temperature, the second temperature being lower than the first temperature; an intermediate heat exchanger fluidly connected to an outlet of the first heat exchanger to receive the gaseous carbon dioxide at the second temperature from the first heat exchanger, such that the gaseous carbon dioxide at the second temperature is converted into gaseous carbon dioxide at a critical temperature; an evaporator containing a refrigerant liquid, a second heat exchanger disposed in the evaporator, an inlet of the second heat exchanger being able to receive the gaseous carbon dioxide at the critical temperature from the intermediate heat exchanger, such that the gaseous carbon dioxide at the critical temperature is cooled by the refrigerant liquid to achieve a condensation phase change to become liquid carbon dioxide to be discharged, while a portion of the refrigerant liquid is converted into refrigerant vapor; a condenser, a third heat exchanger disposed in the condenser, the condenser being fluidly connected to the generator to receive the refrigerant vapor generated by the heated absorbent solution, an inlet of the third heat exchanger receiving cooling water from outside to condense the refrigerant vapor into the refrigerant liquid, the condenser also being fluidly connected to the evaporator to discharge the refrigerant liquid to the evaporator; an absorber, a fourth heat exchanger disposed in the absorber, the absorber being fluidly connected to the evaporator to receive the refrigerant vapor from the evaporator, the absorber also being fluidly connected to the generator to receive the absorbent solution with the increased concentration, an inlet of the fourth heat exchanger receiving cooling water from outside to cool the refrigerant vapor to be converted into the refrigerant liquid, the refrigerant liquid being mixed with the absorbent solution with the increased concentration to decrease a concentration of the absorbent solution, the absorbent solution with the decreased concentration being delivered to the generator.

2. The condensing apparatus of claim 1 wherein, The intermediate heat exchanger comprises: a fifth heat exchanger disposed between the first heat exchanger and the second heat exchanger to receive the gaseous carbon dioxide at the second temperature from the outlet of the first heat exchanger, the absorbent solution with the decreased concentration being delivered from the absorber to the generator to pass through the fifth heat exchanger and exchange heat with the gaseous carbon dioxide at the second temperature, such that the gaseous carbon dioxide at the second temperature is converted into gaseous carbon dioxide at a third temperature, the third temperature being lower than the second temperature, an inlet of the second heat exchanger receiving the gaseous carbon dioxide at the third temperature from an outlet of the fifth heat exchanger.

3. The condensing apparatus of claim 2 wherein, The intermediate heat exchanger further comprises: a sixth heat exchanger disposed between the fifth heat exchanger and the second heat exchanger, an inlet of the sixth heat exchanger receiving cooling water from outside, the gaseous carbon dioxide at the third temperature passing through the sixth heat exchanger and exchanging heat with the cooling water, such that the gaseous carbon dioxide at the third temperature is converted into gaseous carbon dioxide at the critical temperature, the gaseous carbon dioxide at the critical temperature being delivered to the inlet of the second heat exchanger.

4. The condensing apparatus according to any one of claims 1 to 3, wherein The evaporator further comprises a refrigerant pump configured to pump the remaining portion of the refrigerant liquid from a bottom of the evaporator to a top of the evaporator again.

5. The condensing apparatus of claim 2 wherein, The condensing apparatus further comprises: a seventh heat exchanger disposed between the generator and the absorber, an inlet of the seventh heat exchanger receiving the concentrated absorbent solution from the generator, and an outlet of the seventh heat exchanger being located at the top of the absorber, the concentrated absorbent solution from the bottom of the absorber passing through the seventh heat exchanger, the concentrated absorbent solution and the concentrated absorbent solution being heat exchanged so that the concentrated absorbent solution is heated, and further passing through the fifth heat exchanger.

6. The condensing apparatus of any one of claims 1 to 3, wherein, The condensing device further comprises: a first fan disposed between the generator and the condenser for transporting the refrigerant vapor generated by the heated absorbent solution to the condenser; a second fan disposed between the evaporator and the absorber for transporting the refrigerant vapor in the evaporator to the absorber.

7. The condensing apparatus of any one of claims 1 to 3, wherein, The first heat exchanger, the second heat exchanger, the third heat exchanger, the fourth heat exchanger, the fifth heat exchanger, and the seventh heat exchanger are any one of plate type, shell and tube type, and double pipe type.

8. The condensing apparatus of any one of claims 1 to 3, wherein, The sixth heat exchanger is a water-cooled condenser or an air cooler.

9. The condensing apparatus of any one of claims 1 to 3, wherein, The refrigerant is water, and the absorbent is lithium bromide.

10. A carbon dioxide compression refrigeration system characterized by, The carbon dioxide compression refrigeration system comprises: a compressor; the condensing device as claimed in any one of claims 1 to 9 for condensing the gaseous carbon dioxide discharged from the compressor into liquid carbon dioxide.

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