Heat pump air-conditioning system adapted to ultra-low temperature heating

Abstract

The present invention discloses a heat pump air-conditioning system adapted to ultra-low temperature heating, which includes a compressor (1), an air heat exchanger (3) equipped with an axial flow fan (17), a liquid receiver (5), a filter (6), an expansion valve A (7), an indoor heat exchanger (9) equipped with a centrifugal fan (16), a gas-liquid separator (10), and a four-way reversing valve (2), a check valve A (4), a check valve B (8), a check valve C (11), an expansion valve B (12), a check valve D (13), an internal circulation air heat exchanger (14), and a hot gas bypass valve (15). The present invention can effectively solve the problem of ultra-low temperature heat pump heating, has good market application value; realizes reliable operation of refrigeration and heating, can efficiently realize air conditioning; can effectively protect the refrigeration and heating system; is convenient for detection and maintenance.

Description

Technical Field

[0001] The present invention relates to the field of air conditioning systems, and specifically to a heat pump air conditioning system adapted to ultra-low temperature heating. Background Art

[0002] Special mobile vehicles are equipped with special air conditioners, which have functions such as refrigeration and heating, providing a good working environment for in-vehicle equipment and personnel. Due to the mobility and all-day operation characteristics of mobile vehicles, and the power generation output of the generators supporting special vehicles is not very large, the power consumption of special air conditioners is limited.

[0003] When special mobile vehicles are used in high-cold regions (the design requirement is up to -45°C), to ensure a relatively high temperature requirement in the cabin, the heating capacity required by special vehicles is very large. Ordinary heat pump heating has poor heating effect in an environment below -7°C and cannot meet the vehicle temperature adjustment requirements. To ensure the low-temperature heating requirements in high-cold regions, generally, special air conditioners use electric heating tubes (or PTC) for heating. This type of heating has low energy efficiency (the energy efficiency is about 0.8). When the heating demand is large, its power consumption is also very large. For example, for an 8-meter-long standard vehicle to meet the requirements of use in high-cold regions, a heating capacity of 10 kW is required, and the power consumption of electric heating is about 12.5 kW. Special mobile vehicles simply cannot provide such a large power source. Therefore, it is very difficult for general air conditioning systems to meet the requirements without special treatment. Summary of the Invention

[0004] The purpose of the present invention is to provide a heat pump air conditioning system adapted to ultra-low temperature heating, so as to solve the problem that the heating capacity of the air conditioning system of special mobile vehicles in the prior art cannot meet the requirements of special mobile vehicles in high-cold regions at ultra-low temperatures.

[0005] In order to achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A heat pump air conditioning system adapted to ultra-low temperature heating, including a compressor (1), an air heat exchanger (3) equipped with an axial flow fan (17), a liquid receiver (5), a filter (6), an expansion valve A (7), an indoor heat exchanger (9) equipped with a centrifugal fan (16), a gas-liquid separator (10), characterized in that it further includes a four-way reversing valve (2), a check valve A (4), a check valve B (8), a check valve C (11), an expansion valve B (12), a check valve D (13), an internal circulation air heat exchanger (14), and a hot gas bypass valve (15), wherein:

[0007] The outlet end of the compressor (1) is connected to a valve port (a) of a four-way reversing valve (2) through a pipeline. Another valve port (b) of the four-way reversing valve (2) is connected to a port of an air heat exchanger (3) through a pipeline. Another port of the air heat exchanger (3) is connected to the inlet of a check valve A (4) through a pipeline. The outlet of the check valve A (4) is connected to the interior of a liquid receiver (5) through a pipeline. The interior of the liquid receiver (5) is also connected to a port of a filter (6) through a pipeline. Another port of the filter (6) is connected to the inlet of an expansion valve A (7) through a pipeline. The outlet of the expansion valve A (7) is connected to the inlet of a check valve B (8) through a pipeline. The outlet of the check valve B (8) is connected to a port of an indoor heat exchanger (9) through a pipeline. Another port of the indoor heat exchanger (9) is connected to a third valve port (c) of the four-way reversing valve (2) through a pipeline. A fourth valve port (d) of the four-way reversing valve (2) is connected to the inlet of a gas-liquid separator (10) through a pipeline. The outlet of the gas-liquid separator (10) is connected to the inlet of the compressor (1) through a pipeline;

[0008] The inlet of a check valve C (11) is connected in parallel through a pipeline to the pipeline between the outlet of the check valve B (8) and the corresponding port of the indoor heat exchanger (9). The outlet of the check valve C (11) is connected in parallel through a pipeline to the pipeline between the port of the filter (6) and the inlet of the expansion valve A (7); The inlet of an expansion valve B (12) is connected in parallel to the pipeline between the outlet of the check valve A (4) and the liquid receiver (5). The outlet of the expansion valve B (12) is connected to the inlet of a check valve D (13) through a pipeline. The outlet of the check valve D (13) is connected in parallel through a pipeline to the pipeline between the inlet of the check valve A (4) and the corresponding port of the air heat exchanger (3);

[0009] The internal circulation air heat exchanger (14) is coupled with the air heat exchanger (3) integrally and shares an axial flow fan (17). The third valve port (c) of the four-way reversing valve (2) is also connected in parallel through a pipeline to the inlet of a hot gas bypass valve (15). The outlet of the hot gas bypass valve (15) is connected to a port of the internal circulation air heat exchanger (14) through a pipeline. Another port of the internal circulation air heat exchanger (14) is connected to the interior of the liquid receiver (5) through a pipeline.

[0010] Furthermore, it also includes a temperature sensor A (21), a temperature sensor B (22), a temperature sensor C (23), and a temperature sensor D (24). Among them, the temperature sensor A (21) is arranged on the indoor return air side of the indoor heat exchanger (9), the temperature sensor B (22) is arranged at the coil of the air heat exchanger (3), the temperature sensor C (23) is arranged on the condensation inlet air side of the air heat exchanger (3), and the temperature sensor D (24) is arranged at the shell of the liquid receiver (5).

[0011] Further, it also includes a low-voltage protector (20), and the low-voltage protector (20) is bypass-connected to the pipeline between the fourth valve port (d) of the four-way reversing valve (2) and the inlet of the gas-liquid separator (10).

[0012] Further, it also includes a refrigerant charging nozzle (25), and the refrigerant charging nozzle (25) is bypass-connected to the pipeline between the fourth valve port (d) of the four-way reversing valve (2) and the inlet of the gas-liquid separator (10).

[0013] Further, it also includes an electric heater A (18) and an electric heater B (19), wherein the electric heater A (18) is arranged on the shell of the compressor (1), and the electric heater B (19) is arranged on the shell of the liquid receiver (5).

[0014] The heat pump air-conditioning system of the present invention adapted to ultra-low temperature heating can detect the current indoor return air, the coil of the air heat exchanger, the environment, and the temperature of the liquid receiver in real time, and feedback them to the control unit of the special mobile vehicle. The control unit automatically compares the return air temperature with the set temperature (T0). When the return air temperature reaches the set temperature, the compressor stops working, the refrigeration or heating system stops working, and the centrifugal fan continues to work for ventilation. Thus, refrigeration and heating operations are achieved.

[0015] For the heat pump air-conditioning system of the present invention adapted to ultra-low temperature heating, when the ambient temperature is low (e.g., lower than -7°C), the hot gas bypass valve is activated to adjust the refrigerant amount entering the internal circulation heat exchanger, control the output heating capacity, and further adjust the indoor temperature, so as to ensure the heating capacity finally output by the air conditioner in an ultra-low temperature environment. This enables the air conditioner to operate in a good and efficient heating environment state.

[0016] For the heat pump air-conditioning system of the present invention adapted to ultra-low temperature heating, when the temperature of the liquid receiver shell is low (e.g., less than -20°C), the electric heaters A and B are turned on. When the temperature sensor D detects that the temperature of the liquid receiver shell is greater than -20°C (this value is adjusted according to different compressors), the electric heaters A and B stop working. This realizes reliable operation for ultra-low temperature heating.

[0017] For the heat pump air-conditioning system of the present invention adapted to ultra-low temperature heating, the pressure protector detects the low pressure value of the system and feedbacks it to the control unit. The control unit automatically compares the pressure value with the low pressure value set by the pressure protector. When the system pressure is lower than the set pressure, the compressor stops working, thereby protecting the compressor and avoiding the compressor from idling without refrigerant.

[0018] For the heat pump air-conditioning system of the present invention adapted to ultra-low temperature heating, the refrigerant charging nozzle is fixed on the pipeline between the outlet of the four-way reversing valve and the inlet of the gas-liquid separator, which is convenient for refrigerant charging.

[0019] The heat pump air-conditioning system adapted to ultra-low temperature heating of the present invention is provided with check valve A, check valve B, check valve C, and check valve D, which can only allow the refrigerant to flow in one direction, that is, the refrigerant flows from the air heat exchanger towards check valve A, the refrigerant flows from expansion valve A towards check valve B, the refrigerant flows from the indoor heat exchanger towards check valve C, and the refrigerant flows from expansion valve B towards check valve D. This prevents the refrigerant from flowing reversely in the system and enables reliable operation of refrigeration and heating.

[0020] Compared with the prior art, the advantages of the present invention are as follows:

[0021] 1) It effectively solves the problem of ultra-low temperature heat pump heating and has good market application value;

[0022] 2) It realizes reliable operation of refrigeration and heating and can efficiently achieve air conditioning;

[0023] 3) It can effectively protect the refrigeration and heating system;

[0024] 4) It is convenient for detection and maintenance. Description of the Drawings

[0025] Figure 1 It is the structural schematic diagram of the system of the present invention. Detailed Embodiment

[0026] The present invention will be further described below in conjunction with the drawings and embodiments.

[0027] As Figure 1 shown, the present invention will be further described below in conjunction with the drawings and embodiments.

[0028] As Figure 1 shown, the heat pump air-conditioning system adapted to ultra-low temperature heating includes a compressor 1, a four-way reversing valve 2, an air heat exchanger 3, a check valve A 4, a liquid receiver 5, a filter 6, an expansion valve A 7, a check valve B 8, an indoor heat exchanger 9, a gas-liquid separator 10, a check valve C 11, an expansion valve B 12, a check valve D 13, an internal circulation air heat exchanger 14, a hot gas bypass valve 15, a centrifugal fan 16, an axial flow fan 17, an electric heating tape A 18, an electric heating B 19, a low-pressure protector 20, a temperature sensor A 21, a temperature sensor B 22, a temperature sensor C 23, a temperature sensor D 24, and a refrigerant charging nozzle 25.

[0029] The outlet of the compressor 1 is connected to a valve port a of the four-way reversing valve 2 through a pipeline. Another valve port b of the four-way reversing valve 2 is connected to a port of the air heat exchanger 3 through a pipeline. Another port of the air heat exchanger 3 is connected to the inlet end of the check valve A4 through a pipeline. The outlet end of the check valve A4 is connected to the inside of the liquid receiver 5 through a pipeline. The inside of the liquid receiver 5 is also connected to a port of the filter 6 through a pipeline. Another port of the filter 6 is connected to the inlet end of the expansion valve A7 through a pipeline. The outlet end of the expansion valve A7 is connected to the inlet end of the check valve B8 through a pipeline. The outlet end of the check valve B8 is connected to a port of the indoor heat exchanger 9 through a pipeline. Another port of the indoor heat exchanger 9 is connected to the third valve port c of the four-way reversing valve 2 through a pipeline. The fourth valve port d of the four-way reversing valve 2 is connected to the inlet of the gas-liquid separator 10 through a pipeline. The outlet of the gas-liquid separator 10 is connected to the refrigerant inlet of the compressor 1 through a pipeline, thus forming a compression refrigeration system.

[0030] The inlet end of the check valve C11 is connected in parallel to the pipeline between the outlet end of the check valve B8 and the corresponding port of the indoor heat exchanger 9 through a pipeline bypass. The outlet end of the check valve C11 is connected in parallel to the pipeline between the liquid receiver 5 and the inlet end of the filter 6 through a pipeline bypass. The inlet end of the expansion valve B12 is connected in parallel to the pipeline between the outlet end of the check valve A4 and the liquid receiver 5. The outlet end of the expansion valve B12 is connected to the inlet end of the check valve D13 through a pipeline. The outlet end of the check valve D13 is connected in parallel to the pipeline between the inlet end of the check valve A4 and the corresponding port of the air heat exchanger 3 through a pipeline bypass, thus forming a compression heating system.

[0031] The third valve port c of the four-way reversing valve 2 is also connected to the inlet of the hot gas bypass valve 15 through a pipeline. The outlet of the hot gas bypass valve 15 is connected to the inlet end of the internal circulation air heat exchanger 14 through a pipeline. The internal circulation air heat exchanger 14 is coupled with the air heat exchanger 3. The outlet end of the internal circulation air heat exchanger 14 is connected to the inside of the liquid receiver 5 through a pipeline, thus forming a low-temperature heating bypass system.

[0032] In the present invention, the heat exchange amount of the indoor heat exchanger 8 is discharged into the indoor environment through the circulation of the centrifugal fan 16. The air heat exchanger 3 and the internal circulation air heat exchanger 14 are coupled together and share the axial flow fan 17. The heat exchange amount of the air heat exchanger 3 and the internal circulation air heat exchanger 14 is discharged into the atmosphere through the circulation of the axial flow fan 17.

[0033] In the present invention, the electric heater A18 is wound around the shell of the compressor 1, and the electric heater B19 is wound around the shell of the liquid receiver.

[0034] In the present invention, the temperature sensor A21 is placed at the indoor return side of the indoor heat exchanger 9, the temperature sensor B22 is placed at the coil of the air heat exchanger 3, the temperature sensor C23 is placed at the condensate inlet of the coupling structure between the internal circulation air heat exchanger 14 and the air heat exchanger 3, the temperature sensor D24 is placed at the liquid storage tank housing, and the pressure protector 16 is placed between the fourth valve port d of the four-way reversing valve 2 and the pipeline of the gas-liquid separator 10.

[0035] In the present invention, the check valve A4, check valve B8, check valve C11, and check valve D13 can only allow the refrigerant to flow in one direction, preventing the refrigerant from flowing reversely in the system. That is, the refrigerant flows from the air heat exchanger 3 towards the check valve A4, the refrigerant flows from the expansion valve A7 towards the check valve B8, the refrigerant flows from the indoor heat exchanger 9 towards the check valve C11, and the refrigerant flows from the expansion valve B12 towards the check valve D13.

[0036] In the present invention, the refrigerant filling nozzle 25 is fixed on the pipeline between the fourth valve port d of the four-way reversing valve 2 and the inlet of the gas-liquid separator 10.

[0037] The following further describes the present invention with reference to the accompanying drawings:

[0038] When the refrigeration system operates, the compressor 1 compresses the refrigerant into a high-temperature and high-pressure gas, which enters the air heat exchanger 3 through the four-way reversing valve 2. After heat exchange with the forced convection air in the air heat exchanger 3, it is cooled into a liquid and enters the liquid storage tank 5 through the check valve A4, passes through the filter 6, enters the expansion valve A7, and after throttling, becomes a low-temperature and low-pressure refrigerant liquid. It passes through the check valve B8 and enters the indoor heat exchanger 9 for heat exchange and then becomes a gas. After passing through the four-way reversing valve 2, it enters the gas-liquid separator 10 for separation and then enters the compressor 1 again. This cycle repeats, and at the same time, the centrifugal fan 16 and the axial flow fan 17 continuously operate for forced convection heat exchange to achieve refrigeration.

[0039] When the environmental temperature is relatively low and the heating system operates, the compressor 1 compresses the refrigerant into a high-temperature and high-pressure gas, which enters the indoor heat exchanger 9 through the four-way reversing valve 2. After heat exchange with the forced convection air in the indoor heat exchanger 9, it is cooled into a liquid and passes through the check valve C11 and the filter 6, enters the liquid storage tank 5, enters the expansion valve B12, and after throttling, becomes a low-temperature and low-pressure refrigerant liquid. It passes through the check valve D13 and enters the air heat exchanger 3 for heat exchange and then becomes a gas. After passing through the four-way reversing valve 2, it enters the gas-liquid separator 10 for separation and then enters the compressor 1 again. This cycle repeats, and at the same time, the centrifugal fan 16 and the axial flow fan 17 continuously operate for forced convection heat exchange to achieve heating.

[0040] When the unit operates in heating mode at low temperatures (e.g., when the ambient temperature is below -7°C), due to the low inlet air temperature of the air heat exchanger 3 (the temperature collected by the temperature sensor C23) and the low temperature of the air exchanger coil (the temperature collected by the temperature sensor B22), the evaporation pressure is low. Given that the condensation temperature and pressure of the indoor heat exchanger are constant, the heating effect is poor. Therefore, when heating at low ambient temperatures, the coil temperature collected by the air exchanger coil temperature is used to adjust the opening degree of the hot gas bypass valve 15 to control the bypass flow of the refrigerant, thereby controlling the evaporation pressure and ensuring the normal heating capacity of the system in ultra-low temperature conditions, achieving ultra-low temperature heating operation. Specifically: The compressor 1 compresses the refrigerant into a high-temperature and high-pressure gas. After passing through the four-way reversing valve 2, a part of the gas enters the indoor heat exchanger 9. After the indoor heat exchanger 9 exchanges heat with forced convection air and cools into a liquid, it passes through the check valve C11 and the filter 6 and enters the liquid receiver 5. Another part passes through the hot gas bypass valve 15, connects to the inlet end of the internal circulation air heat exchanger 14, and after converging with the refrigerant from the filter 6 entering the liquid receiver 5 in the liquid receiver 5, the liquid refrigerant is separated in the liquid receiver 5 and then enters the expansion valve B12 through the outlet end of the liquid receiver 5. After throttling, it becomes a low-temperature and low-pressure refrigerant liquid, passes through the check valve D13, enters the air heat exchanger 3 for heat exchange and then becomes a gas, passes through the four-way reversing valve 2, enters the gas-liquid separator 10 for separation, and then enters the compressor 1 again. This cycle repeats, and at the same time, the centrifugal fan 16 and the axial flow fan 17 continuously operate for forced convection heat exchange to achieve ultra-low temperature heating. To prevent the temperature of the air heat exchanger 3 from further decreasing, hot gas bypass is used to adjust part of the refrigerant to enter the internal circulation air heat exchanger 14 through the hot gas bypass valve 15, increasing the temperature of the air heat exchanger 3 without changing the operating state of the indoor heat exchanger 9, thus ensuring that the indoor heat exchanger 9 always delivers the maximum heating capacity and guaranteeing the final heating capacity output by the air conditioner in ultra-low temperature environments.

[0041] When the unit needs to operate in heating mode at ultra-low temperatures (e.g., when the ambient temperature is below -20°C, determined according to the operating temperature of the compressor), due to the low ambient temperature, the lubricating oil of the compressor 1 solidifies. At this time, it is necessary to preheat the refrigerant in the compressor 1 and the liquid receiver 5. The electric heater A18 is wound around the shell of the compressor 1, and the electric heater B19 is wound around the liquid receiver 5. A temperature sensor D24 is installed on the shell of the liquid receiver 5.

[0042] The temperature and humidity sensors A21, B22, C23, and D24 detect the current indoor return air, air heat exchanger coil, ambient, and liquid receiver temperatures in real time and feedback them to the control unit. The control unit automatically compares the return air temperature with the set temperature (T0). When the return air temperature reaches the set temperature, the compressor 1 stops working, and the refrigeration or heating system stops working, while the centrifugal fan 16 continues to work for ventilation. When the ambient temperature is low (e.g., below -7°C), the hot gas bypass valve 15 is activated to adjust the refrigerant amount entering the internal circulation heat exchanger 14, control the output heating capacity, and thus adjust the indoor temperature. When the temperature of the liquid receiver 3 housing is low (e.g., less than -20°C), the electric heaters A and B are turned on. When the temperature sensor D24 detects that the temperature of the liquid receiver housing is greater than -20°C (this value is adjusted according to the compressor), the electric heaters A and B stop working.

[0043] The pressure protector 20 detects the low-pressure value of the system and feedbacks it to the control unit. The control unit automatically compares the pressure value with the low-pressure value set by the pressure protector 20. When the system pressure is lower than the set pressure, the compressor 1 stops working to protect the compressor 1.

[0044] The system of the present invention is provided with a refrigerant filling nozzle 25 to facilitate the filling of refrigerant.

[0045] The embodiments described in the present invention are only descriptions of the preferred embodiments of the present invention, and do not limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various variations and improvements made by those skilled in the art to the technical solutions of the present invention shall fall within the protection scope of the present invention. The technical content claimed by the present invention has been fully recorded in the claims.

Claims

1. A heat pump air-conditioning system adapted to ultra-low temperature heating, comprising a compressor (1), an air heat exchanger (3) equipped with an axial flow fan (17), a liquid receiver (5), a filter (6), an expansion valve A (7), an indoor heat exchanger (9) equipped with a centrifugal fan (16), and a gas-liquid separator (10), characterized in that, It also includes a four-way reversing valve (2), a check valve A (4), a check valve B (8), a check valve C (11), an expansion valve B (12), a check valve D (13), an internal circulation air heat exchanger (14), and a hot gas bypass valve (15), where: The outlet end of the compressor (1) is connected to a valve port (a) of the four-way reversing valve (2) through a pipeline. Another valve port (b) of the four-way reversing valve (2) is connected to a port of the air heat exchanger (3) through a pipeline. Another port of the air heat exchanger (3) is connected to the inlet of the check valve A (4) through a pipeline. The outlet of the check valve A (4) is connected to the inside of the liquid receiver (5) through a pipeline. The inside of the liquid receiver (5) is also connected to a port of the filter (6) through a pipeline. Another port of the filter (6) is connected to the inlet of the expansion valve A (7) through a pipeline. The outlet of the expansion valve A (7) is connected to the inlet of the check valve B (8) through a pipeline. The outlet of the check valve B (8) is connected to a port of the indoor heat exchanger (9) through a pipeline. Another port of the indoor heat exchanger (9) is connected to the third valve port (c) of the four-way reversing valve (2) through a pipeline. The fourth valve port (d) of the four-way reversing valve (2) is connected to the inlet of the gas-liquid separator (10) through a pipeline. The outlet of the gas-liquid separator (10) is connected to the inlet of the compressor (1) through a pipeline; The inlet of the check valve C (11) is connected in parallel through a pipeline to the pipeline between the outlet of the check valve B (8) and the corresponding port of the indoor heat exchanger (9). The outlet of the check valve C (11) is connected in parallel through a pipeline to the pipeline between the port of the filter (6) and the inlet of the expansion valve A (7); The inlet of the expansion valve B (12) is connected in parallel bypass to the pipeline between the outlet of the check valve A (4) and the liquid receiver (5). The outlet of the expansion valve B (12) is connected to the inlet of the check valve D (13) through a pipeline. The outlet of the check valve D (13) is connected in parallel bypass through a pipeline to the pipeline between the inlet of the check valve A (4) and the corresponding port of the air heat exchanger (3); The internal circulation air heat exchanger (14) is coupled with the air heat exchanger (3) integrally and shares an axial flow fan (17). The third valve port (c) of the four-way reversing valve (2) is also connected in parallel by a pipeline to the inlet of the hot gas bypass valve (15). The outlet of the hot gas bypass valve (15) is connected to a port of the internal circulation air heat exchanger (14) through a pipeline. Another port of the internal circulation air heat exchanger (14) is connected to the inside of the liquid receiver (5) through a pipeline; The heat pump air conditioner system adapted to ultra-low temperature heating, characterized in that it further includes a temperature sensor A (21), a temperature sensor B (22), a temperature sensor C (23), and a temperature sensor D (24), where the temperature sensor A (21) is arranged on the indoor return air side of the indoor heat exchanger (9), the temperature sensor B (22) is arranged at the coil of the air heat exchanger (3), the temperature sensor C (23) is arranged on the condensing air inlet side of the air heat exchanger (3), and the temperature sensor D (24) is arranged on the shell of the liquid receiver (5); The described heat pump air conditioning system adapted to ultra-low temperature heating is characterized in that it further includes a low pressure protector (20), and the low pressure protector (20) is bypass-connected to the pipeline between the fourth valve port (d) of the four-way reversing valve (2) and the inlet of the gas-liquid separator (10).

2. The heat pump air conditioning system adapted to ultra-low temperature heating according to claim 1, characterized in that, It further includes a refrigerant charging nozzle (25), and the refrigerant charging nozzle (25) is bypass-connected to the pipeline between the fourth valve port (d) of the four-way reversing valve (2) and the inlet of the gas-liquid separator (10).

3. The heat pump air-conditioning system adapted to ultra-low temperature heating according to claim 1, characterized in that, It further includes an electric heater A (18) and an electric heater B (19), wherein the electric heater A (18) is arranged on the shell of the compressor (1), and the electric heater B (19) is arranged on the shell of the liquid receiver (5).

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