Compression condensing unit capable of meeting various requirements for refrigeration or low-temperature system and control method of compression condensing unit

Abstract

The invention relates to a compression condensing unit capable of meeting various requirements and a control method thereof. The compression condensing unit comprises a compressor, a condenser, a first expansion valve and a second expansion valve. The first expansion valve and the second expansion valve are connected in parallel to form a throttling assembly. An outlet of the throttling assembly is connected with an inlet of the evaporator arranged in the use space, and an inlet of the throttling assembly is connected with an outlet of the condenser; an exhaust port of the compressor is connected with an inlet of the condenser after passing through the oil separator, and an air suction port of the compressor is connected with an outlet of the evaporator after passing through the gas-liquid separator. Accurate control can be carried out through control methods such as the throttling control module and the compressor control module, the function of different high and low temperature outlet air temperatures or outlet water temperatures of the compression condensing unit is achieved, and the requirements for different target temperatures of use space are met structurally and systematically.

Description

TECHNICAL FIELD

[0001] The present application relates to a refrigeration device and a control method thereof, in particular to a compression condensing unit and a control method thereof for a refrigeration or low-temperature system, and more particularly to a compression condensing unit and a control method thereof for a refrigeration or low-temperature system capable of meeting multiple requirements. BACKGROUND

[0002] In the refrigeration and air conditioning industry, the power consumption of air conditioners in large public buildings accounts for about half of the total power consumption. In the refrigeration and cold storage industry, precision industry and laboratory testing, the demand for multiple target temperatures and different cold load requirements for storage and working environments is also increasing.

[0003] At present, compression condensing units are widely used in the above-mentioned industries. For temperature regulation and cold load regulation of the use space, one compression condensing unit is generally used to meet the target temperature requirement and cold load requirement of one use space. In order to meet the above-mentioned multiple temperature and different cold load requirements, the following methods are mainly used: 1) Multiple compressors with different cooling capacities are designed for the compression condensing unit, and PID control electric heating devices and humidifying devices are matched in the room to achieve temperature balance in the room. 2) A two-stage system is used, which can be switched to single-stage refrigeration mode or two-stage compression refrigeration mode according to the load requirement, so as to expand the environmental regulation range to meet the requirement.

[0004] However, the above-mentioned two methods have defects such as complex system design, high cost and poor energy saving effect, and cannot effectively meet the requirements. Therefore, it is of great significance to develop a compression condensing unit capable of meeting multiple target temperatures and different cold load requirements in the same use space. SUMMARY

[0005] The purpose of the present application is to overcome the problems of the prior art and fully meet the market demand.

[0006] The technical scheme of the present application is as follows: A compression condensing unit for a refrigeration or low-temperature system capable of meeting multiple requirements, comprising a compressor and a condenser, and a first expansion valve and a second expansion valve; the first expansion valve and the second expansion valve are connected in parallel to form a throttling assembly; the outlet of the throttling assembly is connected to the inlet of an evaporator arranged in a use space, and the inlet thereof is connected to the outlet of the condenser; the exhaust port of the compressor is connected to the inlet of the condenser after passing through an oil separator, and the suction port thereof is connected to the outlet of the evaporator after passing through a gas-liquid separator.

[0007] Furthermore, the compressor is a piston type and has a built-in energy regulating solenoid valve; the evaporator is a direct expansion coil type or other heat exchanger with similar functions; the inlet ends of the first expansion valve and the second expansion valve are respectively equipped with a first solenoid valve and a second solenoid valve.

[0008] Furthermore, a fourth shut-off valve, a fluorine filter, and a third shut-off valve are sequentially arranged on the pipeline between the inlet of the throttling component and the condenser.

[0009] Furthermore, the inlet of the throttling component is connected to the liquid injection port of the compressor after passing through a second shut-off valve, a third expansion valve, and a third expansion valve arranged in sequence.

[0010] Furthermore, the oil outlet of the oil separator is connected to the oil return port of the compressor after passing through a first shut-off valve and an oil filter arranged in sequence.

[0011] Furthermore, the compressor's exhaust port is equipped with a first temperature sensor and a first pressure sensor; the evaporator outlet is equipped with a second pressure sensor; and the operating space is equipped with a second temperature sensor.

[0012] A control method for a compressor-condensing unit that can meet various needs in a refrigeration or cryogenic system, using the aforementioned compressor-condensing unit, includes the following steps: 1) When the unit is powered on and receives the start-up command, it checks whether the software and hardware are normal; if not, it issues a fault alarm. 2) Execute the start-up command for pump-type electrical equipment; 3) After a delay of tt1 seconds, the operating space temperature T1 is detected by the second temperature sensor, and it is determined whether the compressor loading conditions are met; if they are met, proceed to the next step; if they are not met, confirm repeatedly. 4) After a delay of tt2 seconds, the high-temperature solenoid valve and the first expansion valve are energized sequentially. The initial opening degree of the first expansion valve is a%. 5) Start the compressor; the initial energy output of the compressor is b1%; 6) Execute the throttling system control module and compressor control module to bring the unit into normal operating condition; The throttling system control module includes two control modes: expansion valve opening control and expansion valve operating mode control. First, it performs high-temperature expansion valve opening control and continues for 10 seconds before entering expansion valve operating mode control. Then, it enters expansion valve opening control and performs real-time judgment and control of the expansion valve operating mode. The expansion valve operation mode control compares the evaporation pressure Pz, the target pressure Pj, and the pressure difference p1 of the evaporator to control the operation of the first and second expansion valves; the evaporation pressure Pz is acquired by the second pressure sensor; the target pressure Pj is the saturation pressure value corresponding to the target evaporation temperature Tee; and the pressure difference p1 is a constant. The compressor control module controls the compressor to load or unload by comparing the operating space temperature T1, the target operating space temperature Te, the operating space temperature setpoint Td, and the temperature differences d1 and d2; where d1 and d2 are constants. Simultaneously execute other control and alarm commands; 7) The unit enters normal operating condition, and the following judgments are made: i) If a shutdown command is received, proceed to step 8). ii) If the measured ambient temperature T1 is less than or equal to the ambient temperature setpoint Td, then after a delay of tt5 seconds, the compressor energy output is adjusted to b2%; after another delay of tt6 seconds, the compressor is turned off, and the process proceeds to step 3). iii) If a fault alarm signal is received, proceed to step 9). 8) After a 5-second delay (tt), the compressor energy output is adjusted to b2%; 9) After a 6-second delay, turn off the compressor; 10) Delay tt7 seconds to shut down all electronic expansion valves, solenoid valves and other powered devices; 11) The unit stops and control ends.

[0013] Furthermore, the throttling control module specifically comprises: 6.1.1) The opening degree of the high-temperature expansion valve is controlled and maintained for tt10 seconds; 6.1.2) Judgment and control of expansion valve operating mode: i) When Pz≥Pj+p1, the first expansion valve operates and the high-temperature solenoid valve opens. After t1 seconds, if the low-temperature solenoid valve is energized, the low-temperature solenoid valve is disconnected and the second expansion valve stops operating. ii) When Pz≤Pj-p1, the second expansion valve operates, the low-temperature solenoid valve opens, and after t1 seconds, if the high-temperature solenoid valve is energized, the high-temperature solenoid valve is disconnected, and the first expansion valve stops operating. iii) When Pj+p1≥Pz≥Pj-p1, maintain the current operating state of the expansion valve and solenoid valve; 6.1.3) Expansion valve opening control; 6.1.4) Return to step 6.1.2).

[0014] Furthermore, the compressor control module specifically comprises: 6.2.1) After the unit makes a real-time judgment, it shall perform the following actions: i) When T1≤Td, the compressor is in the emergency stop zone, all compressors immediately unload in sequence, and the unit shuts down in an emergency; ii) When Te-d2>T1≥Te-d1, the compressor is in the unloading zone and unloads according to a certain mode: if only one compressor is running at present, it will continuously or intermittently unload until the lowest load position is reached; if the measured room temperature T1 continues to drop and exceeds the set room temperature Td, it will shut down; if two or more compressors are running in parallel at present, all compressors will be unloaded in sequence until they are shut down. iii) When Te + d2 > T1 ≥ Te - d2, the compressor is in the holding zone, maintaining the current compressor energy load operation state; iv) When T1≥Te+d2, the compressor is in the loading zone and is loaded in a certain mode: if no compressor is running, the compressors are started one after another; each compressor is loaded continuously or intermittently until it is in the holding zone or at the maximum load position; 6.2.2) Return to step 6.2.1).

[0015] Furthermore, the target pressure Pj and the target evaporation temperature Tee have the following formula relationship: When T11≤Tee<T22: Pj=C1*Tee 4 / 10 8 +C2*Tee 3 / 10 6 +C3*Tee 2 +C4*Tee+C5; When T22≤Tee<T33: Pj=C6*Tee 4 / 10 8 +C7*Tee 3 / 10 7 +C8*Tee 2 +C9*Tee+C10; When T33≤Tee≤T44: Pj=(C11*Tee) 4 / 10 8 +C12*Tee 3 / 10 6 +C13*Tee 2 +C14*Tee+C15)*C16; where T11, T22, T33 and T44 are all constants.

[0016] The beneficial effects of this invention are: This invention utilizes a throttling component to achieve different outlet air or water temperatures for the compressor-condensing unit, structurally and systematically meeting the diverse target temperature requirements of the operating space. Simultaneously, by using a compressor equipped with an energy regulating valve as a different energy output device within the compressor-condensing unit, it achieves different cooling load outputs, satisfying the varying cooling load requirements of the operating space. Therefore, it can comprehensively and continuously cool and dehumidify high and low temperature air, or separately cool and dehumidify high-temperature, medium-temperature, and low-temperature air, meeting the different target temperatures and cooling load requirements within the operating space. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the present invention.

[0018] Figure 2 This is a schematic diagram of the control flow of the present invention.

[0019] Figure 3 This is a schematic diagram of the throttling control module.

[0020] Figure 4 This is a schematic diagram of the compressor control module.

[0021] Wherein, 1-compressor; 2-first temperature sensor; 3-first pressure sensor; 4-oil separator; 5-first shut-off valve; 6-oil filter; 8-third expansion valve; 9-gas-liquid separator; 10-second pressure sensor; 11-condenser; 12-third shut-off valve; 13-fluorine filter; 14-fourth shut-off valve; 16-first solenoid valve; 17-first expansion valve; 19-evaporator; 20-second temperature sensor; 21-second expansion valve; 22-second solenoid valve; 23-second shut-off valve; 24-third solenoid valve. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] like Figure 1 As shown.

[0024] The present invention provides a compressor-condenser unit for refrigeration or cryogenic systems that can meet various needs, including a compressor 1 and a condenser 11, as well as a first expansion valve 17 and a second expansion valve 21, and an evaporator 19 is provided in the usage space.

[0025] The compressor 1 is a piston type and has a built-in energy regulating solenoid valve. It can also be a scroll type or similar device that can compress gas, increase gas pressure, or transport gas.

[0026] The first expansion valve 17 and the second expansion valve 21 are responsible for throttling under high-temperature and low-temperature conditions, respectively, and are connected in parallel to form a throttling assembly. The outlet of this throttling assembly is connected to the inlet of the evaporator 19, and its inlet is connected to the outlet of the condenser 11. The exhaust port of the compressor 1 is connected to the inlet of the condenser 11 after passing through the oil separator 4, and its suction port is connected to the outlet of the evaporator 19 after passing through the gas-liquid separator 9.

[0027] The inlet ends of the first expansion valve 17 and the second expansion valve 21 are respectively provided with a first solenoid valve 16 and a second solenoid valve 22, so that the opening and closing of the corresponding expansion valves can be controlled respectively.

[0028] The pipeline between the inlet of the throttling component and the condenser is provided with a fourth shut-off valve 14, a fluorine filter 13 and a third shut-off valve 12 arranged in sequence.

[0029] The inlet of the throttling component is connected to the liquid injection port of the compressor 1 after passing through the second shut-off valve 23, the third solenoid valve 24 and the third expansion valve 8 arranged in sequence, forming a liquid injection system to achieve the liquid injection cooling effect.

[0030] The oil outlet of the oil separator 4 is connected to the oil return port of the compressor after passing through the first shut-off valve 5 and the oil filter 6 arranged in sequence, forming an oil return passage.

[0031] The compressor 1 is equipped with a first temperature sensor 2 and a first pressure sensor 3 at its exhaust port to detect the exhaust temperature and pressure of the compressor.

[0032] A second pressure sensor 10 is provided at the outlet of the evaporator 19 to detect the evaporation pressure.

[0033] A second temperature sensor 20 is provided in the usage space to detect the temperature of the usage space.

[0034] The evaporator is a direct expansion coil type, but it is not limited to this scheme. It can also be a finned or shell-and-tube type or similar heat exchange equipment suitable for the unit's operating conditions and needs.

[0035] The compressor-condenser unit does not include an evaporator, which is installed separately on site. However, this is not the only option; similar solutions that meet the requirements can also be adopted, such as assembling the evaporator onto the unit before delivery from the factory.

[0036] The compressor in the aforementioned compression condensing unit is a piston type and has a built-in energy regulating solenoid valve, but it is not limited to piston type. It can also be a scroll type or similar equipment that can compress gas, increase gas pressure, or transport gas.

[0037] Both the solenoid valve and the shut-off valve have the function of cutting off the flow of fluid medium, but are not limited to this type of valve and may be other valves with similar functions.

[0038] In the aforementioned compressor-condenser unit, two expansion valves are connected in parallel. The first expansion valve and the second expansion valve are respectively a high-temperature stage expansion valve and a low-temperature stage expansion valve. The first solenoid valve and the second solenoid valve are respectively a high-temperature stage solenoid valve and a low-temperature stage solenoid valve. The first expansion valve and the first solenoid valve are responsible for throttling under high-temperature conditions, while the second expansion valve and the second solenoid valve are responsible for throttling under low-temperature conditions. However, this scheme is not limited to, and similar schemes that can meet the refrigerant throttling requirements of the unit under high, medium, and low temperature conditions can also be adopted.

[0039] The compressor-condenser unit can consist of a single unit or several units connected in parallel.

[0040] The compressor-condenser unit includes a circuit connecting the refrigerant outlet and refrigerant inlet of the evaporator. A gas-liquid separator, compressor, oil separator, condenser, and refrigerant filter are connected in sequence on the circuit. The refrigerant outlet circuit located between the refrigerant filter and the evaporator is provided with two parallel pipelines. A first expansion valve and a first solenoid valve are connected in sequence on one pipeline and a second expansion valve and a second solenoid valve are connected in sequence on the other pipeline. However, this is not limited to this scheme, and similar schemes that can meet the structural and operating requirements of the unit can also be adopted.

[0041] In the aforementioned compressor-condenser unit, a liquid injection system is provided on the circuit between the fluorine filter and the throttling system, and the liquid injection system is directly connected to the liquid injection port of the compressor; an oil return system is provided between the compressor and the oil separator, and the oil return system is directly connected to the oil outlet of the oil separator and the oil return port of the compressor. However, this solution is not limited to this one, and similar solutions that can meet the structural and operating requirements of the unit can also be adopted. In the aforementioned compressor-condenser unit, R404A refrigerant is selected, but it is not limited to this scheme. Similar schemes that can meet the requirements of the unit system and operating conditions can also be adopted. The control of the compressor-condensing unit, from the power-on command to the shutdown, consists of 11 steps, as detailed below. However, this is not the only option; other similar solutions that can meet the unit control requirements may also be used.

[0042] The condenser 11 is a shell-and-tube type, or a similar device that can meet the heat exchange requirements of refrigerant and cooling water.

[0043] The first expansion valve 17 and the second expansion valve 21 are both electronic expansion valves, or they can be thermal expansion valves or similar devices that can play a throttling role.

[0044] The second pressure sensor is installed between the gas-liquid separator and the evaporator and on the pipeline near the latter, but it is not limited to this solution. A similar solution that meets the requirements can also be adopted, such as installing it on the evaporator of the unit.

[0045] The second temperature sensor 20 is installed in the operating space 18 near the evaporator 19, but it is not limited to this solution. It can also be installed in the evaporator outlet pipe of the unit or similar solutions that meet the requirements.

[0046] The first temperature sensor 2 and the first pressure sensor 3 are installed on the compressor 1 and the oil separator 4 near the compressor 1, but they are not limited to this solution and can also be installed in other similar locations that meet the requirements.

[0047] The specific connection method of the present invention is as follows: like Figure 1 As shown, the unit is directly connected to the evaporator 19 in the space via refrigerant inlet and outlet pipelines to form the entire refrigeration unit system. The outlet pipeline of the evaporator 19 is connected to the gas-liquid separator 9, the outlet of the gas-liquid separator 9 is connected to the compressor 1, the outlet of the compressor 1 is connected to the oil separator 4, the outlet of the oil separator 4 is connected to the condenser 11, the condenser 11 is connected to the refrigerant filter 13 via the third shut-off valve 12, and the refrigerant filter 13 is connected to the throttling system via the fourth shut-off valve 14. The throttling system located between the refrigerant filter 13 and the evaporator 19 has two parallel pipelines, and a first expansion valve 17 is installed on each of the two parallel pipelines in sequence. The first solenoid valve 16 and the second expansion valve 21 and the second solenoid valve 22 are connected in sequence on another branch pipe; a liquid injection system is connected to the main liquid pipe circuit between the fluorine filter 13 and the throttling system. The liquid injection system is directly connected to the compressor injection port. From the main liquid pipe circuit, the second shut-off valve 23, the third solenoid valve 24 and the third expansion valve 8 are connected in sequence; an oil return system is connected between the compressor 1 and the oil separator 4. The oil return system is directly connected to the oil outlet of the oil separator 4 and the oil return port of the compressor 1. From the oil separator 4, the first shut-off valve 5 and the oil filter 6 are connected in sequence; the condenser 11 is connected to the cooling water inlet and outlet pipes.

[0048] The refrigeration principle of the compressor-condenser unit is as follows: After the refrigerant is compressed and pressurized by the compressor 1, it enters the oil separator 4 for oil separation, then enters the condenser 11 to exchange heat with the coolant on the cooling side, and after passing through the dryer filter 13, it enters the throttling component to reduce pressure and temperature, and then enters the evaporator 19 to exchange heat with the external environment before entering the compressor 1, forming a cycle.

[0049] Specifically, in the condenser 11, the refrigerant absorbs heat from the high-pressure side refrigerant, its temperature rises, and then it enters the external cold source. After exchanging heat with the external cold source and releasing heat to cool down, it flows back to the condenser 11 to exchange heat with the high-pressure side refrigerant. In the evaporator 19, the low-pressure side refrigerant exchanges heat with the air in the operating space, becomes superheated, and provides the cooling load before entering the compressor 1. This cycle repeats to meet the cooling load requirements of the operating space.

[0050] Specifically, the oil separated in the oil separator 4 flows into the oil return port of the compressor 1 after passing through the first shut-off valve 5 and the oil filter 6 under oil pressure, thus achieving a good oil return effect for the unit.

[0051] Specifically, subcooled high-pressure refrigerant is drawn from the main liquid line before the throttling component, and after being throttled and cooled by the third expansion valve 8, it enters the liquid injection port of the compressor 1, thus achieving the liquid injection cooling effect of the unit.

[0052] Specifically, for high-temperature operating conditions, the first solenoid valve 16 and the corresponding expansion valve are opened; for low-temperature operating conditions, the second solenoid valve 22 (low-temperature solenoid valve) and the corresponding expansion valve are opened.

[0053] like Figure 2 As shown, the present invention discloses a control method for a compressor condensing unit for refrigeration or cryogenic systems that can meet various needs. The method utilizes the aforementioned compressor condensing unit and includes the following steps: 1) When the unit is powered on and receives the start-up command, it checks whether the software and hardware are normal; if not, it issues a fault alarm. 2) Execute the start-up command for pump-type electrical equipment; 3) After a delay of tt1 seconds, the operating space temperature T1 is detected by the second temperature sensor, and it is determined whether the compressor loading conditions are met. If they are met, proceed to the next step; if not, repeatedly confirm. The default value of tt1 is 5, which can be changed according to actual needs. 4) After a delay of tt2 seconds, the high-temperature solenoid valve and the first expansion valve are energized sequentially. The initial opening degree of the first expansion valve is a%; where tt2 has a default value of 5 and a has a default value of 25, both of which can be modified according to actual needs. 5) Start the compressor; the initial energy output of the compressor is b1%; where b1 has a default value of 50, which can be modified according to actual needs; 6) Execute the throttling system control module and compressor control module to bring the unit into normal operating condition; The throttling system control module includes two control modes: expansion valve opening control and expansion valve operating mode control. After the entire unit starts up, it enters the throttling system control module, first controlling the opening of the high-temperature expansion valve for 10 seconds, then entering the expansion valve operating mode control. After determining and selecting the expansion valve operating mode, it then enters the expansion valve opening control, and continuously judges and controls the expansion valve operating mode in real time.

[0054] The expansion valve operation mode control compares the evaporation pressure Pz, the target pressure Pj, and the pressure difference p1 of the evaporator to control the operation of the first and second expansion valves; the evaporation pressure Pz is acquired by the second pressure sensor; the target pressure Pj is the saturation pressure value corresponding to the target evaporation temperature Tee; and the pressure difference p1 is a constant. The compressor control module controls the compressor to load or unload by comparing the operating space temperature T1, the target operating space temperature Te, the operating space temperature setpoint Td, and the temperature differences d1 and d2; where d1 and d2 are constants. Simultaneously execute other control and alarm commands; 7) The unit enters normal operating condition, and the following judgments are made: i) If a shutdown command is received, proceed to step 8). ii) If the measured ambient temperature T1 is less than or equal to the ambient temperature setpoint Td, then after a delay of tt5 seconds, the compressor energy output is adjusted to b2%; after another delay of tt6 seconds, the compressor is turned off, and the process proceeds to step 3). iii) If a fault alarm signal is received, proceed to step 9). 8) After a 5-second delay (tt), the compressor energy output is adjusted to b2%; 9) After a 6-second delay, turn off the compressor; 10) Delay tt7 seconds to shut down all electronic expansion valves, solenoid valves and other powered devices; 11) The unit stops and control ends.

[0055] The default values ​​for tt5 are 5, b2 is 50, tt6 is 30, and tt7 is 30. These values ​​can be changed according to actual needs.

[0056] Furthermore, such as Figure 3 As shown, the specific steps of the throttling control module are as follows: 6.1.1) The opening degree of the high-temperature expansion valve is controlled and maintained for tt10 seconds; The default value for tt10 is 1800, which can be changed according to actual needs.

[0057] 6.1.2) Judgment and control of expansion valve operating mode: i) When Pz≥Pj+p1, the first expansion valve operates and the high-temperature solenoid valve opens. After t1 seconds, if the low-temperature solenoid valve is energized, the low-temperature solenoid valve is disconnected and the second expansion valve stops operating. ii) When Pz≤Pj-p1, the second expansion valve operates, the low-temperature solenoid valve opens, and after t1 seconds, if the high-temperature solenoid valve is energized, the high-temperature solenoid valve is disconnected, and the first expansion valve stops operating. iii) When Pj + p1 ≥ Pz ≥ Pj - p1, maintain the current operating state of the expansion valve and solenoid valve; 6.1.3) Expansion valve opening control; 6.1.4) Return to step 6.1.2).

[0058] Where Pj is the saturation pressure value corresponding to the target evaporation temperature, with a default value of 2.7 bar, which can also be changed according to actual needs; p1 is a positive value, with a default value of 0.3 bar, which can also be changed according to actual needs; t1 is a positive value, with a default value of 6 seconds, which can also be changed according to actual needs.

[0059] Furthermore, the target pressure Pj and the target evaporation temperature Tee have the following relationship: When T11≤Tee<T22: Pj=C1*Tee 4 / 10 8 +C2*Tee 3 / 10 6 +C3*Tee 2 +C4*Tee+C5; When T22≤Tee<T33: Pj=C6*Tee 4 / 10 8 +C7*Tee 3 / 10 7 +C8*Tee 2 +C9*Tee+C10; When T33≤Tee≤T44: Pj=(C11*Tee) 4 / 10 8 +C12*Tee 3 / 10 6 +C13*Tee 2 +C14*Tee+C15)*C16; where T11 has a default value of -60, T22 has a default value of -24, T33 has a default value of 11, T44 has a default value of 70, C1 has a default value of 0, C2 has a default value of 8, C3 has a default value of 0.002, C4 has a default value of 0.183, C5 has a default value of 5.971, C6 has a default value of 2, C7 has a default value of 1, C8 has a default value of 0.002, C9 has a default value of 0.191, C10 has a default value of 6.048, C11 has a default value of 4, C12 has a default value of 8, C13 has a default value of 0.002, C14 has a default value of 0.158, C15 has a default value of 5, and C16 has a default value of 1.2; all of the above default values ​​can be modified according to actual needs.

[0060] Furthermore, such as Figure 4 As shown, the specific steps of the compressor control module are as follows: 6.2.1) After the unit makes a real-time judgment, it shall perform the following actions: i) When T1≤Td, the compressor is in the emergency stop zone, all compressors immediately unload in sequence, and the unit shuts down in an emergency; ii) When Te-d2>T1≥Te-d1, the compressor is in the unloading zone and unloads according to a certain mode: if only one compressor is running at present, it will continuously or intermittently unload until the lowest load position is reached; if the measured room temperature T1 continues to drop and exceeds the set room temperature Td, it will shut down; if two or more compressors are running in parallel at present, all compressors will be unloaded in sequence until they are shut down. iii) When Te + d2 > T1 ≥ Te - d2, the compressor is in the holding zone, maintaining the current compressor energy load operation state; iv) When T1≥Te+d2, the compressor is in the loading zone and is installed in a certain mode: if no compressor is running, the compressors are turned on one after another; each compressor is continuously or intermittently loaded until it is in the holding zone or at the maximum load position; 6.2.2) Return to step 6.2.1).

[0061] Among them, Td has a default value of -35, Te has a default value of -30, d2 is a positive value with a default value of 1, and d1 is a positive value with a default value of 5; these default values ​​can be changed according to actual needs.

[0062] The compressor's load increase / decrease fine-tuning mode involves energizing the adjustable solenoid valve (energizing for t2 seconds, de-energizing for t3 seconds, and repeating this cycle); or energizing the loading solenoid valve for t2 seconds, de-energizing for t3 seconds, then energizing the unloading solenoid valve for t4 seconds, de-energizing for t5 seconds, and repeating this cycle. Here, t2 is a positive value with a default value of 25; t3 is a positive value with a default value of 5; t4 is a positive value with a default value of 5; and t5 is a positive value with a default value of 5. All values ​​can be modified according to actual needs.

[0063] Further, implementation examples of operating opening control for high-temperature or low-temperature expansion valves: When the measured suction superheat TX1 of the unit is greater than or equal to the target suction superheat TX2 + d4, the valve opening is increased in a certain number of steps; when the target suction superheat TX2 - d4 is less than or equal to the measured suction superheat TX1, which is less than or equal to the target suction superheat TX2 + d4, the valve opening is maintained; when the measured suction superheat TX1 is less than or equal to the target suction superheat TX2 - d4, the valve opening is decreased in a certain number of steps. TX1 is the measured calculated value, TX2 is the set value (default value is 5), and d4 is a constant value (default value is 3). All of these values ​​can be modified according to actual needs.

[0064] The present invention also includes a temperature control module, the control steps of which are as follows: The measured exhaust temperature T2 is obtained through the first temperature sensor and compared with the exhaust target temperature Tp and the temperature difference d3. When T2≤Tp-d3, the third solenoid valve 24 is disconnected, and the liquid spraying system stops working; When T2≥Tp+d3, the third solenoid valve 24 closes and the liquid spraying system starts to work; The default value for Tp is 90, and for d3 it is a positive value with a default value of 5. These can be modified according to actual needs. This ensures that the compressor-condenser unit operates stably and reliably at reasonable oil and exhaust temperatures, providing a long-term stable cooling load for the space in use.

[0065] The advantages of this invention are: 1) This invention utilizes the mutual coupling of high and low temperature expansion valves and variable compressors in the operation strategy and electrical system to realize different energy outputs of the compressor condensing unit, as well as different outlet air temperature or outlet water temperature at high and low temperatures, thus meeting the needs of different target temperatures and different cooling loads in the space.

[0066] 2) This invention has excellent adaptability to high and low temperature conditions: the two expansion valves can control the refrigerant flow of different circuits respectively. Under high temperature conditions, it can accurately match the demand of large loads, and under low temperature conditions, it can avoid excessive refrigerant throttling. When paired with an energy-adjustable piston compressor (the compression capacity can be adjusted as needed), it can further adapt to load fluctuations in a wide temperature range and avoid the unit from "overload" or "inefficient operation" under extreme conditions.

[0067] 3) This invention significantly saves energy and reduces operating costs: Traditional compressor condensing units often waste energy due to the mismatch between "fixed capacity" and "dynamic load". However, this invention can achieve "on-demand energy supply" - when the load is low (such as in spring and autumn or at night), the compressor reduces energy output and the two expansion valves reduce refrigerant flow simultaneously to avoid "overloading". When the load is high, the two work together to increase output and reduce ineffective energy consumption. Long-term operation can significantly reduce electricity costs.

[0068] 4) This invention offers more stable operation and extends unit lifespan: Under high and low temperature conditions, units are prone to malfunctions due to refrigerant flow imbalances and sudden changes in compressor load (such as compressor liquid slugging at low temperatures and overload at high temperatures). The precise flow control of the dual expansion valves can prevent refrigerant oversupply or undersupply, while the energy-adjustable compressor can smoothly adjust the load, reducing the frequency of unit start-ups and shutdowns and component impacts, lowering the probability of failure, and extending the overall service life of the unit.

[0069] 5) The load matching of the present invention is more precise and can more accurately meet the temperature requirements of the space: If used in cold chain and other scenarios, this combination can avoid the temperature of the space fluctuating (such as the temperature fluctuation of cold chain storage) through stable refrigerant output and compression efficiency, ensuring higher temperature control accuracy and improving the comfort / safety of use or storage.

[0070] All parts not covered in this invention are the same as or can be implemented using existing technologies.

Claims

1. A multi-capacity compression-condensing unit for a refrigeration or cryogenic system comprising a compressor and a condenser, characterized in that, Further comprising a first expansion valve and a second expansion valve; the first expansion valve and the second expansion valve are connected in parallel to form a throttling assembly; the outlet of the throttling assembly is connected with the inlet of an evaporator arranged in a use space, and the inlet thereof is connected with the outlet of the condenser; the exhaust port of the compressor is connected with the inlet of the condenser after passing through an oil separator, and the suction port thereof is connected with the outlet of the evaporator after passing through a gas-liquid separator.

2. The multi-capability compression-condensing unit for refrigeration or cryogenics system according to claim 1, wherein, The compressor is a piston type and is provided with an energy regulating electromagnetic valve; the inlet ends of the first expansion valve and the second expansion valve are respectively provided with a first electromagnetic valve and a second electromagnetic valve.

3. The multi-capability compression-condensing unit for refrigeration or cryogenics system, as recited in claim 1, wherein, A fourth stop valve, a fluorine filter and a third stop valve are sequentially arranged on the pipeline between the inlet of the throttling assembly and the condenser.

4. The multi-capability compression-condensing unit for refrigeration or cryogenics system, as recited in claim 1, wherein, The inlet of the throttling assembly is connected with the liquid injection port of the compressor after passing through a second stop valve, a third electromagnetic valve and a third expansion valve arranged in sequence.

5. The multi-capability compression-condensing unit for refrigeration or cryogenics system, as recited in claim 1, wherein, The oil outlet of the oil separator is connected with the oil return port of the compressor after passing through a first stop valve and an oil filter arranged in sequence.

6. The multi-capability compression-condensing unit for refrigeration or cryogenics system, as recited in claim 1, wherein, The exhaust port of the compressor is provided with a first temperature sensor and a first pressure sensor; the outlet of the evaporator is provided with a second pressure sensor; and the use space is provided with a second temperature sensor.

7. A control method for a multi-demand-capable compression-condensing unit for a refrigeration or cryogenics system, characterized by, The compressor condenser unit of claims 1 to 6 comprises the following steps: 1) After the unit is powered on and receives a start command, it is detected whether the software and hardware are normal; if not, a fault alarm is issued; 2) Execute the start command of the pump type electrical equipment; 3) After a delay of tt1 seconds, the use space temperature T1 is detected by the second temperature sensor, and it is determined whether it meets the compressor loading conditions; if yes, the next step is entered; if not, it is repeatedly confirmed; 4) After a delay of tt2 seconds, the high temperature electromagnetic valve and the first expansion valve are powered on in sequence, and the initial opening of the first expansion valve is a%; 5) Start the compressor; the initial energy output of the compressor is b1%; 6) Execute the throttling system control module and the compressor control module, and execute other control and alarm commands; The throttling system control module includes two control modes of expansion valve running opening control and expansion valve running mode control; first, the high temperature expansion valve running opening control is performed, and after tt10 seconds, the expansion valve running mode control is entered; then, the expansion valve running opening control is entered, and the expansion valve running mode is judged and controlled in real time; The expansion valve running mode control controls the operation of the first expansion valve, the first electromagnetic valve, the second electromagnetic valve and the second expansion valve by comparing the evaporating pressure Pz of the evaporator, the target pressure Pj and the pressure difference p1; the evaporating pressure Pz is collected by the second pressure sensor; the target pressure Pj is the saturation pressure value corresponding to the target evaporating temperature Tee; and the pressure difference p1 is a constant; The compressor control module controls the compressor to load or unload by comparing the use space temperature T1, the use space target temperature Te, the use space temperature setting value Td and the temperature difference d1, d2; d1, d2 are constants; Other control and alarm commands are executed at the same time; 7) The unit enters a normal operating state and makes the following judgments: i) if a shutdown command is received, go to step 8); ii) if the measured temperature of the space T1 is less than the set temperature of the space Td, delay for tt5 seconds, then set the energy output of the compressor to b2%, delay for tt6 seconds, then shut down the compressor, and go to step 3); iii) if a fault alarm signal is received, go to step 9); 8) delay for tt5 seconds, then set the energy output of the compressor to b2%; 9) delay for tt6 seconds, then shut down the compressor; 10) delay for tt7 seconds, then shut down all electronic expansion valves, electromagnetic valves and other powered devices; 11) shut down the unit, and the control ends.

8. The control method of the multi-demand-satisfying compression-condensing unit for a refrigeration or cryogenics system according to claim 7, characterized by, The throttle control module specifically comprises: 6.1.1) high-temperature expansion valve operation opening control, and continue for tt10 seconds; 6.1.2) expansion valve operation mode judgment and control: i) when Pz≥Pj+p1, the first expansion valve operates, the high-temperature electromagnetic valve is opened, and after t1 seconds, if the low-temperature electromagnetic valve is in the powered state, the low-temperature electromagnetic valve is disconnected, and the second expansion valve stops operating; ii) when Pz≤Pj-p1, the second expansion valve operates, the low-temperature electromagnetic valve is opened, and after t1 seconds, if the high-temperature electromagnetic valve is in the powered state, the high-temperature electromagnetic valve is disconnected, and the first expansion valve stops operating; iii) when Pj+p1≥Pz≥Pj-p1, the current operation state of the expansion valve and the electromagnetic valve is maintained; 6.1.3) expansion valve operation opening control; 6.1.4) return to step 6.1.2).

9. The control method of the multi-demand-satisfying compression-condensing unit for a refrigeration or cryogenics system according to claim 7, characterized by, The compressor control module specifically comprises: 6.2.1) after the unit performs real-time judgment, the following actions are performed: i) when T1≤Td, the compressor is in the emergency stop zone, all compressors are immediately unloaded in turn, and the unit is shut down in emergency; ii) when Te-d2>T1≥Te-d1, the compressor is in the unloading zone, and unloading is performed in a certain mode: if only one compressor is currently operating, unloading is performed continuously or intermittently until the lowest load position; if the measured temperature of the space T1 continues to drop and exceeds the set temperature of the space Td, the unit is shut down; if two or more compressors are currently operating in parallel, all the compressors are unloaded in turn until the unit is shut down; iii) when Te+d2>T1≥Te-d2, the compressor is in the maintaining zone, and the current energy load operation state of the compressor is maintained; iv) when T1≥Te+d2, the compressor is in the loading zone, and loading is performed in a certain mode: if no compressor is operating, the compressors are turned on successively; each compressor is continuously or intermittently loaded until the compressor is in the maintaining zone or the maximum load position; 6.2.2) return to step 6.2.1).

10. The control method of the multi-demand-satisfying compression-condensing unit for a refrigeration or cryogenics system according to claim 7, characterized by, The target pressure Pj and the target evaporation temperature Tee have the following formula relationship: When T11 < Tee < T22: Pj = C1*Tee 4 / 10 8 +C2*Tee 3 / 10 6 +C3*Tee 2 +C4*Tee+C5; When T22 < Tee < T33: Pj = C6*Tee 4 / 10 8 +C7*Tee 3 / 10 7 +C8*Tee 2 +C9*Tee+C10; When T33≤ Tee≤ T44: Pj = (C11*Tee 4 / 10 8 +C12*Tee 3 / 10 6 +C13*Tee 2 +C14*Tee+C15)*C16; wherein T11, T22, T33 and T44 are all constants.

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