Zero-load operation device for refrigeration unit

Abstract

A zero-load operation device for a refrigeration unit. The device comprises a compressor, a condenser, a main-circuit electronic expansion valve, an evaporator, a hot-gas bypass electronic expansion valve, and a liquid-line bypass electronic expansion valve, wherein the compressor, the condenser, the main-circuit electronic expansion valve and the evaporator are sequentially connected in a closed loop through pipelines; and two ends of the hot-gas bypass electronic expansion valve are respectively connected to an exhaust port and a suction port of the compressor, and two ends of the liquid-line bypass electronic expansion valve are respectively connected to the suction port of the compressor and a liquid outlet of the condenser. By means of the use of the hot-gas bypass electronic expansion valve in combination with the liquid-line bypass electronic expansion valve, the zero-load operation device for a refrigeration unit solves the problem of it not being possible to reduce the cooling capacity of the unit at a partial load to zero, and enables uninterrupted running of the unit at a zero load, thereby improving the accuracy of temperature control.

Description

A zero-load operation device for refrigeration units

[0001] This application claims priority to the following Chinese patent application: Chinese Patent Application No. 202411199996.3, filed on August 29, 2024, entitled "A Zero-Load Operation Device for a Refrigeration Unit". The entire contents of that patent application are incorporated herein by reference. Technical Field

[0002] This disclosure relates to the field of air conditioning technology, and in particular to a zero-load operation device for refrigeration units. Background Technology

[0003] Refrigeration refers to the process of removing heat from an object or system artificially over a certain period of time, thereby lowering its temperature below the ambient temperature and maintaining a low temperature.

[0004] In some fields where high temperature control accuracy is required, it is necessary to adjust the cooling capacity without stopping the compressor.

[0005] A more conventional approach is to use a hot gas bypass solenoid valve, which achieves high temperature control accuracy through frequent start-stop of the solenoid valve. However, this method is only suitable for small units and is affected by the lifespan of the solenoid valve.

[0006] Based on this, a method has emerged that uses a proportional regulating valve to replace the solenoid valve. In this case, the hot gas bypass flow rate can be adjusted proportionally, making the target temperature more accurate. However, this method only relatively broadens the adjustment range of the cooling capacity under partial load. It cannot achieve uninterrupted operation when the cooling capacity is zero, and the temperature control accuracy is still limited. Summary of the Invention

[0007] To address the aforementioned issues, this disclosure provides a zero-load operation device for refrigeration units. By using a hot gas bypass electronic expansion valve combined with a liquid circuit bypass electronic expansion valve, it solves the problem that the unit's partial load cooling capacity cannot be reduced to zero, enabling the unit to operate without stopping under zero load conditions and improving temperature control accuracy.

[0008] According to one aspect of this disclosure, a zero-load operation device for a refrigeration unit is provided, comprising a compressor, a condenser, a main circuit electronic expansion valve, an evaporator, a hot gas bypass electronic expansion valve, and a liquid bypass pipe electronic expansion valve, wherein the compressor, the condenser, the main circuit electronic expansion valve, and the evaporator are sequentially connected in a closed loop via pipelines; wherein the two ends of the hot gas bypass electronic expansion valve are respectively connected to the discharge port and the suction port of the compressor, and the two ends of the liquid bypass pipe electronic expansion valve are respectively connected to the suction port of the compressor and the liquid outlet of the condenser.

[0009] In some embodiments, the compressor's exhaust port and intake port are connected via a hot gas bypass line, and the hot gas bypass electronic expansion valve is installed on the hot gas bypass line. The advantage of this is that the hot gas bypass line allows for the specific installation of the hot gas bypass electronic expansion valve.

[0010] In some embodiments, the compressor's suction inlet and the condenser's liquid outlet are connected via a liquid bypass line, and an electronic expansion valve is installed on the liquid bypass line. The advantage of this is that the liquid bypass line allows for the specific installation of the liquid bypass electronic expansion valve.

[0011] In some embodiments, the opening degree of the main circuit electronic expansion valve is controlled by the superheat of the evaporator. The advantage is that the opening degree control of the main circuit electronic expansion valve is described.

[0012] In some embodiments, the opening degree of the hot gas bypass electronic expansion valve is controlled by the superheat of the compressor suction gas. The advantage is that the opening degree control of the hot gas bypass electronic expansion valve is described.

[0013] In some embodiments, the opening degree of the liquid bypass electronic expansion valve is controlled in steps by the opening degree of the hot gas bypass electronic expansion valve. The advantage is that it describes the opening degree control of the liquid bypass electronic expansion valve, where one opening degree range of the hot gas bypass electronic expansion valve corresponds to a fixed opening degree value, while another range corresponds to another fixed value.

[0014] In some embodiments, the compressor is a fixed-frequency compressor or a variable-frequency compressor. The advantage is that, with a fixed-frequency compressor, the refrigerant flow rate at the compressor inlet is also fixed because the compressor's cooling capacity is a fixed value under certain operating conditions. With a variable-frequency compressor, the load rate can be varied from 100% to the minimum partial load rate through compressor frequency conversion.

[0015] In some embodiments, the evaporator is a shell-and-tube heat exchanger or a finned heat exchanger. The advantage is that it describes the available types of evaporators, and other types of heat exchangers can be selected according to actual needs. Attached Figure Description

[0016] Figure 1 is a schematic diagram of a zero-load operation device for a refrigeration unit according to one embodiment of the present disclosure.

[0017] In the diagram: 1. Compressor; 2. Condenser; 3. Main circuit electronic expansion valve; 4. Evaporator; 5. Hot gas bypass electronic expansion valve; 6. Liquid bypass electronic expansion valve; 7. Hot gas bypass pipeline; 8. Liquid bypass pipeline. Detailed Implementation

[0018] The present disclosure will now be described in further detail with reference to the accompanying drawings.

[0019] As shown in Figure 1, the device includes a main circuit consisting of a compressor 1, a condenser 2, a main circuit electronic expansion valve 3, and an evaporator 4 connected in a closed loop through pipelines, which is a conventional closed-loop refrigeration circuit.

[0020] Preferably, the evaporator 4 can be a heat exchanger of different types, such as a shell-and-tube heat exchanger or a finned heat exchanger.

[0021] A hot gas bypass pipe 7 is connected between the exhaust port and the suction port of the compressor 1, and a hot gas bypass electronic expansion valve 5 is installed on the hot gas bypass pipe 7.

[0022] A liquid bypass line 8 is connected between the compressor 1 and the condenser 2, and an electronic expansion valve for the liquid bypass line 8 is installed on the liquid bypass line 8. One end of the liquid bypass line 8 is connected to the suction port of the compressor 1, and the other end is connected to the liquid outlet of the condenser 2.

[0023] When both the hot gas bypass electronic expansion valve 5 and the liquid bypass electronic expansion valve are closed, the compressor 1, condenser 2, main circuit electronic expansion valve 3, and evaporator 4 are connected in sequence to form a conventional closed-loop refrigeration circuit, and the opening degree of the main circuit electronic expansion valve 3 can be controlled by the superheat at the outlet of the evaporator 4.

[0024] When the hot gas bypass electronic expansion valve 5 and the liquid bypass electronic expansion valve are open, the opening degree of the hot gas bypass electronic expansion valve 5 is controlled by the superheat of the compressor 1's suction gas, and the opening degree of the liquid bypass electronic expansion valve 6 is controlled in steps by the opening degree of the hot gas bypass electronic expansion valve 5. That is, within a certain range, one opening degree range of the hot gas bypass electronic expansion valve 5 corresponds to a fixed opening degree value of the liquid bypass electronic expansion valve 6, and another range corresponds to another fixed value.

[0025] Compressor 1 can be a fixed-frequency compressor or a variable-frequency compressor, and the operation mode of this embodiment is different depending on the type of compressor 1.

[0026] In the case where compressor 1 is a fixed-frequency compressor, its cooling capacity is constant under certain operating conditions, resulting in a fixed refrigerant flow rate at the compressor 1 suction inlet. However, if compressor 1 is a variable-frequency compressor, the load rate can be varied from 100% to the minimum part load rate. The minimum part load rate refers to the ratio of the minimum load to the maximum load of compressor 1 under certain operating conditions. In this case, since the cooling capacity of compressor 1 has a minimum value under certain operating conditions, the refrigerant flow rate at the compressor 1 suction inlet also has a minimum value.

[0027] When the required cooling capacity decreases, the main circuit electronic expansion valve 3 will close slightly due to the insufficient superheat at the outlet of evaporator 4. At this time, the hot gas bypass electronic expansion valve 5 and the liquid bypass electronic expansion valve can be opened, allowing some refrigerant to pass through the hot gas bypass pipe 7 and the liquid bypass pipe 8.

[0028] When the required cooling capacity is zero, the superheat at the outlet of evaporator 4 will be too low, causing the electronic expansion valve to close slightly until it is completely shut off. At this time, this portion of refrigerant will pass entirely through the hot gas bypass line 7 and the liquid bypass line 8.

[0029] In summary, the hot gas bypass electronic expansion valve 5 combined with the liquid circuit bypass electronic expansion valve 6 can achieve zero-load operation of the compressor 1 without stopping, thereby achieving higher precision in cooling capacity and temperature regulation. This method is applicable to fixed-frequency and variable-frequency machines, as well as different types of evaporators 4, and has a wide range of applications. It can be used in various high-precision temperature regulation devices.

[0030] The above descriptions are merely some embodiments of this disclosure. Those skilled in the art can make various modifications and improvements without departing from the inventive concept of this disclosure, and all such modifications and improvements fall within the scope of protection of this disclosure.

Claims

1. A zero-load operation device for a refrigeration unit, characterized in that: The system includes a compressor (1), a condenser (2), a main circuit electronic expansion valve (3), an evaporator (4), a hot gas bypass electronic expansion valve (5), and a liquid bypass pipe electronic expansion valve (6). The compressor (1), the condenser (2), the main circuit electronic expansion valve (3), and the evaporator (4) are connected in a closed loop via pipelines. The two ends of the hot gas bypass electronic expansion valve (5) are connected to the exhaust port and the suction port of the compressor (1), respectively. The two ends of the liquid bypass pipe electronic expansion valve (6) are connected to the suction port of the compressor (1) and the liquid outlet of the condenser (2), respectively.

2. The zero-load operation device for a refrigeration unit according to claim 1, characterized in that: The exhaust port and intake port of the compressor (1) are connected by a hot gas bypass pipe (7), and the hot gas bypass electronic expansion valve (5) is installed on the hot gas bypass pipe (7).

3. The zero-load operation device for a refrigeration unit according to claim 1, characterized in that: The suction port of the compressor (1) and the liquid outlet of the condenser (2) are connected by a liquid bypass pipe (8), and the liquid bypass pipe electronic expansion valve (6) is installed on the liquid bypass pipe (8).

4. A zero-load operation device for a refrigeration unit according to claim 1, characterized in that: The opening degree of the main circuit electronic expansion valve (3) is controlled by the superheat of the evaporator (4).

5. A zero-load operation device for a refrigeration unit according to claim 1, characterized in that: The opening degree of the hot gas bypass electronic expansion valve (5) is controlled by the superheat of the gas drawn in by the compressor (1).

6. A zero-load operation device for a refrigeration unit according to claim 1, characterized in that: The opening degree of the liquid bypass electronic expansion valve (6) is controlled in stages by the opening degree of the hot gas bypass electronic expansion valve (5).

7. A zero-load operation device for a refrigeration unit according to claim 1, characterized in that: The compressor (1) is a fixed-frequency compressor or a variable-frequency compressor.

8. A zero-load operation device for a refrigeration unit according to claim 1, characterized in that: The evaporator (4) is a shell-and-tube heat exchanger or a finned heat exchanger.

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