A control method for a refrigerant circulation loop and the refrigerant circulation loop itself.

Abstract

This invention discloses a control method for a refrigerant circulation loop and a refrigerant circulation loop itself. The method includes: acquiring the real-time superheat value of the refrigerant circulation loop; determining the current numerical range of the real-time superheat value; when the real-time superheat value is within a first numerical range, controlling the opening and closing states of the valves in each automatic valve branch of the refrigerant circulation loop based on the relationship between the real-time superheat value and a preset target superheat value; and when the real-time superheat value is within a second numerical range, controlling the opening and closing of the manual valve branches in the refrigerant circulation loop. The technical solution provided by this invention adjusts the opening and closing states of each valve according to different superheat values, achieving multi-dimensional control of superheat. This solves the technical problems of narrow adjustment range and poor adjustment accuracy in the prior art, which relies on manually adjusting the fixed opening of a mechanical thermal expansion valve to control the superheat at the evaporator outlet.

Description

Technical Field

[0001] This invention relates to the field of test chamber control technology, and in particular to a control method and a refrigerant circulation loop. Background Technology

[0002] Currently, the industry typically uses evaporator outlet superheat as an auxiliary indicator of compressor operation safety and stability. Most methods control evaporator outlet superheat by manually adjusting the fixed opening of a mechanical thermostatic expansion valve. However, with continuous technological advancements, customers have increasingly higher requirements for their products, needing to verify the heat exchange uniformity and heat transfer capacity of their products under different evaporator outlet superheat conditions. The aforementioned methods cannot meet customers' wide-range adjustment needs, exhibiting problems such as narrow adjustment range and poor adjustment accuracy. Summary of the Invention

[0003] This invention provides a control method and a refrigerant circulation loop to solve the technical problems of narrow adjustment range and poor adjustment accuracy in the prior art, which controls the superheat of the evaporator outlet by manually adjusting the fixed opening of the mechanical thermostatic expansion valve.

[0004] According to one aspect of the present invention, a method for controlling a refrigerant circulation loop is provided, comprising:

[0005] Obtain the real-time superheat value of the refrigerant circulation loop;

[0006] Determine the current numerical range of the real-time superheat value, wherein the current numerical range includes a first numerical range and a second numerical range, and the minimum value of the second numerical range is greater than or equal to the maximum value of the first numerical range;

[0007] When the real-time superheat value is within the first numerical range, the valve opening and closing status of each automatic valve branch in the refrigerant circulation loop is controlled based on the relationship between the real-time superheat value and the preset target superheat value.

[0008] When the real-time superheat value is within the second numerical range, the manual valve branch in the refrigerant circulation loop is opened.

[0009] Optionally, when the real-time superheat value is within the first numerical range, controlling the valve opening and closing status of each automatic valve branch in the refrigerant circulation loop based on the relationship between the real-time superheat value and the preset target superheat value includes:

[0010] If the real-time superheat value is greater than the preset target superheat value, the valves of each automatic valve branch in the refrigerant circulation loop are adjusted from the normal operating state to the first correction state. The normal operating state is as follows: the pulse solenoid valve in the first automatic valve branch is operating at 100% opening, the first electronic expansion valve is operating at 50% opening, the first solenoid valve in the second automatic valve branch is open, the second electronic expansion valve is operating at 10% opening, and the second solenoid valve in the manual valve branch is closed.

[0011] The first corrected state is as follows: the pulse solenoid valve in the first automatic valve branch is operating at 100% opening, the first electronic expansion valve is operating by increasing its opening in real time based on the first feedback signal, the first solenoid valve in the second automatic valve branch is open, and the second solenoid valve in the manual valve branch is closed.

[0012] If the real-time superheat value is less than the preset target superheat value, the valves of each automatic valve branch in the refrigerant circulation loop are adjusted from the normal operating state to the second correction state. The second correction state is as follows: the pulse solenoid valve in the first automatic valve branch is operating at 100% opening, the first electronic expansion valve is operating by reducing its opening in real time based on the second feedback signal, the first solenoid valve in the second automatic valve branch is open, and the second solenoid valve in the manual valve branch is closed.

[0013] Optionally, during the operation of the refrigerant circulation loop in the first corrected state or the second corrected state, the control method further includes:

[0014] Determine whether the deviation between the real-time superheat value and the preset target superheat value meets the preset deviation value. If it does, adjust the refrigerant circulation loop to the normal operating state.

[0015] Optionally, during the operation of the refrigerant circulation loop in the first corrected state, the control method further includes:

[0016] During the operation of the first electronic expansion valve in a state of increasing its opening degree in real time based on the first feedback signal, if the real-time superheat value is greater than the preset target superheat value when the opening degree of the first electronic expansion valve increases to 100%, then the first electronic expansion valve will be kept in the state of 100% opening degree, and the second electronic expansion valve will be controlled to operate in a state of increasing its opening degree in real time based on the first feedback signal.

[0017] Optionally, during the operation of the refrigerant circulation loop in the second corrected state, the control method further includes:

[0018] During the operation of the first electronic expansion valve in a state of real-time reduction of opening based on the second feedback signal, if the real-time superheat value is less than the preset target superheat value when the opening of the first electronic expansion valve is reduced to 10%, then the first electronic expansion valve is kept in the state of 10% opening, and the pulse solenoid valve is controlled to operate in a state of real-time reduction of opening based on the second feedback signal.

[0019] Optionally, when the real-time superheat value is within the second numerical range, controlling the opening of the manual valve branch in the refrigerant circulation loop includes:

[0020] When the real-time superheat value is within the second numerical range, each valve branch in the refrigerant circulation loop is controlled to operate in a third correction state. The third correction state is as follows: the pulse solenoid valve in the first automatic valve branch is operating at 100% opening, the first electronic expansion valve is operating at 100% opening, the first solenoid valve in the second automatic valve branch is open, the second electronic expansion valve is operating at 100% opening, and the second solenoid valve in the manual valve branch is open.

[0021] Optionally, before obtaining the real-time superheat value of the refrigerant circulation loop, the method further includes:

[0022] Obtain the real-time subcooling value of the refrigerant circulation loop;

[0023] Determine whether the real-time subcooling value meets the preset target subcooling value. If it does, then execute the step of obtaining the real-time superheat value of the refrigerant circulation loop.

[0024] If the condition is not met, the speed of the variable frequency condenser fan is adjusted based on the third feedback signal until the real-time subcooling value meets the preset target subcooling value.

[0025] Optionally, obtaining the real-time superheat value of the refrigerant circulation loop includes:

[0026] Obtain the real-time pressure and temperature values ​​at the evaporator outlet in the refrigerant circulation loop;

[0027] The real-time superheat value of the refrigerant circulation loop is determined based on the real-time pressure value and the real-time temperature value.

[0028] According to another aspect of the present invention, a refrigerant circulation loop is provided, the refrigerant circulation loop performing the control method of the refrigerant circulation loop according to any embodiment of the present invention, the refrigerant circulation loop comprising: at least two automatic valve branches, at least one manual valve branch, a variable frequency compressor, a condenser, a liquid receiver, an evaporator, and a gas-liquid separator;

[0029] At least two automatic valve branches and at least one manual valve branch are connected in parallel; the variable frequency compressor, the condenser, the liquid receiver, the parallel valve branches, the evaporator, and the gas-liquid separator are sequentially connected to form the refrigerant circulation loop;

[0030] The first automatic valve branch includes a pulse solenoid valve and a first electronic expansion valve connected in series; the second automatic valve branch includes a first solenoid valve and a second electronic expansion valve connected in series; and the manual valve branch includes a second solenoid valve and a manual expansion valve connected in series.

[0031] The operating status of each valve in the first automatic valve branch, the second automatic valve branch, and the manual valve branch is adjusted based on the current value range of the real-time superheat value at the evaporator outlet.

[0032] Optionally, the refrigerant circulation loop further includes: a first refrigerant charging valve, a temperature sensor after the receiver, a dryer filter, a sight glass, a pressure sensor after the receiver, a temperature sensor after the evaporator, a second refrigerant charging valve, and a pressure sensor after the evaporator.

[0033] The first refrigerant charging valve, the temperature sensor after the liquid receiver, the dryer filter, and the sight glass are sequentially connected between the liquid receiver and each valve branch connected in parallel.

[0034] The pressure sensor after the liquid reservoir is connected to the first refrigerant charging valve.

[0035] The temperature sensor after the evaporator and the second refrigerant charging valve are sequentially connected between the evaporator and the gas-liquid separator;

[0036] The pressure sensor after the evaporator is connected to the second refrigerant charging valve.

[0037] This invention provides a control method and a refrigerant circulation loop for a refrigerant circulation loop. The method includes: acquiring the real-time superheat value of the refrigerant circulation loop; determining the current numerical range of the real-time superheat value; when the real-time superheat value is within a first numerical range, controlling the opening and closing states of each automatic valve branch in the refrigerant circulation loop based on the relationship between the real-time superheat value and a preset target superheat value; and when the real-time superheat value is within a second numerical range, controlling the opening and closing of the manual valve branch in the refrigerant circulation loop. The technical solution provided by this invention adjusts the opening and closing states of each valve according to different superheat values, achieving multi-dimensional control of superheat. This solves the technical problems of narrow adjustment range and poor adjustment accuracy in the prior art, which relies on manually adjusting the fixed opening of a mechanical thermal expansion valve to control the superheat at the evaporator outlet. It achieves the technical effect of improving the superheat adjustment range and enhancing the superheat adjustment accuracy.

[0038] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 A flowchart of a control method for a refrigerant circulation loop provided in an embodiment of the present invention;

[0041] Figure 2 This is a schematic diagram of a refrigerant circulation loop provided in an embodiment of the present invention. Detailed Implementation

[0042] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0043] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0044] Figure 1 A flowchart of a control method for a refrigerant circulation loop provided in an embodiment of the present invention is shown below. Figure 1 The control method includes:

[0045] S110. Obtain the real-time superheat value of the refrigerant circulation loop.

[0046] Specifically, by acquiring the real-time pressure and temperature values ​​at the evaporator outlet in the refrigerant circulation loop, the real-time superheat value of the refrigerant circulation loop is determined based on the real-time pressure and temperature values.

[0047] S120. Determine the current value range of the real-time superheat value, wherein the current value range includes a first value range and a second value range, and the minimum value of the second value range is greater than or equal to the maximum value of the first value range.

[0048] The first numerical range is the range of superheat values ​​when the refrigerant circulation loop is operating normally, and the second numerical range is the range of superheat values ​​when the refrigerant circulation loop is operating abnormally. For example, the industry generally sets the first numerical range to 0K-7K or 0K-10K and the second numerical range to 7K-20K or 10K-20K.

[0049] S130. When the real-time superheat value is within the first value range, the valve opening and closing status of each automatic valve branch in the refrigerant circulation loop is controlled based on the relationship between the real-time superheat value and the preset target superheat value.

[0050] The preset target overheat value is any value within the first numerical range.

[0051] Specifically, when the real-time superheat value is within the first value range, it indicates that the refrigerant circulation loop is in normal operation. At this time, the real-time superheat value is in the normal superheat value stage. Therefore, it is necessary to compare the real-time superheat value with the preset target superheat value and control the valve opening and closing status of each automatic valve branch in the refrigerant circulation loop according to the comparison result.

[0052] S140. When the real-time superheat value is within the second numerical range, the manual valve branch in the refrigerant circulation loop is opened.

[0053] Specifically, when the real-time superheat value is in the second range, it indicates that the refrigerant circulation loop is in an abnormal operating state. At this time, the real-time superheat value is in the abnormal superheat value stage. Therefore, the manual valve branch in the refrigerant circulation loop is opened to enable the real-time superheat value to be adjusted to the normal superheat value stage as soon as possible.

[0054] The technical solution provided by this invention adjusts the opening and closing states of each valve according to the superheat value in different ranges, thereby achieving multi-dimensional control of superheat. This solves the technical problems of narrow adjustment range and poor adjustment accuracy in the prior art, which controls the superheat at the evaporator outlet by manually adjusting the fixed opening of the mechanical thermal expansion valve. It achieves the technical effect of improving the superheat adjustment range and enhancing the superheat adjustment accuracy.

[0055] Figure 2 This is a schematic diagram of the refrigerant circulation loop provided in an embodiment of the present invention. Based on the above technical solutions, S130 specifically includes:

[0056] If the real-time superheat value is greater than the preset target superheat value, the valves of each automatic valve branch in the refrigerant circulation loop will be adjusted from the normal operating state to the first correction state.

[0057] Among them, see Figure 2The normal operating state is as follows: the pulse solenoid valve HSV1 in the first automatic valve branch 11 is at 100% opening, the first electronic expansion valve EEV1 is at 50% opening, the first solenoid valve SV2 in the second automatic valve branch 12 is open, the second electronic expansion valve EEV2 is at 10% opening, and the second solenoid valve SV1 in the manual valve branch 13 is closed. The first correction state is as follows: the pulse solenoid valve HSV1 in the first automatic valve branch 11 is at 100% opening, the first electronic expansion valve EEV1 operates by increasing its opening in real time based on the first feedback signal, the first solenoid valve SV2 in the second automatic valve branch 12 is open, and the second solenoid valve SV1 in the manual valve branch 13 is closed. Both the first solenoid valve SV2 and the second solenoid valve SV1 are low-leakage solenoid valves, and both the first electronic expansion valve and the second electronic expansion valve are high-precision electronic expansion valves. The first feedback signal is the deviation feedback signal obtained by calculating the deviation between the real-time superheat value and the preset target superheat value when the valves in each automatic valve branch in the refrigerant circulation loop are operating in the first correction state.

[0058] Specifically, when the real-time superheat value is greater than the preset target superheat value, it indicates that although the refrigerant circulation loop is in normal operation, it is not in the optimal operating state and there is a risk of abnormal operation. Therefore, it is necessary to set the pulse solenoid valve HSV1 in the first automatic valve branch 11 to 100% opening, and the first electronic expansion valve EEV1 to operate with a real-time increased opening based on the first feedback signal. In other words, when the real-time superheat value is greater than the preset target superheat value, when the valves in each automatic valve branch in the refrigerant circulation loop are in the second correction state, the deviation feedback signal obtained by calculating the deviation between the real-time superheat value and the preset target superheat value is used to set the first electronic expansion valve EEV1 to operate with a real-time increased opening.

[0059] If the real-time superheat value is less than the preset target superheat value, the valves of each automatic valve branch in the refrigerant circulation loop will be adjusted from the normal operating state to the second correction state.

[0060] See also Figure 2 The second correction state is as follows: the pulse solenoid valve in the first automatic valve branch is at 100% opening; the first electronic expansion valve operates by reducing its opening in real time based on the second feedback signal; the first solenoid valve in the second automatic valve branch is open; and the second solenoid valve in the manual valve branch is closed. The second feedback signal is a deviation feedback signal obtained by calculating the deviation between the real-time superheat value and the preset target superheat value when the valves in each automatic valve branch of the refrigerant circulation loop are operating in the second correction state.

[0061] Specifically, when the real-time superheat value is less than the preset target superheat value, it indicates that although the refrigerant circulation loop is in normal operation, it is not in the optimal operating state. Therefore, the pulse solenoid valve HSV1 in the first automatic valve branch 11 needs to be in the 100% opening state, and the first electronic expansion valve EEV1 needs to operate in the state of real-time reduced opening based on the second feedback signal. That is to say, when the real-time superheat value is less than the preset target superheat value, when the valves in each automatic valve branch in the refrigerant circulation loop are in the second correction state, the deviation feedback signal obtained by calculating the deviation between the real-time superheat value and the preset target superheat value is used to operate the first electronic expansion valve EEV1 in the state of real-time reduced opening.

[0062] The technical solution provided by this invention adjusts the opening and closing state of each valve according to the relationship between the real-time superheat value when the real-time superheat value is within a first numerical range and the preset target superheat value, thereby achieving multi-dimensional control of superheat and further improving the accuracy of superheat adjustment.

[0063] Based on the above technical solutions, S140 specifically includes:

[0064] When the real-time superheat value is within the second range, the valve branches in the refrigerant circulation loop are controlled to operate in the third correction state.

[0065] See also Figure 2 The third corrected state is as follows: the pulse solenoid valve HSV1 in the first automatic valve branch 11 is in a 100% open state, the first electronic expansion valve EEV1 is in a 100% open state, the first solenoid valve SV2 in the second automatic valve branch 12 is open, the second electronic expansion valve EEV2 is in a 100% open state, and the second solenoid valve SV1 in the manual valve branch 13 is open.

[0066] Specifically, when the real-time superheat value is within the second value range, it indicates that the refrigerant circulation loop is in an abnormal operating phase. Therefore, it is necessary to control each valve branch in the refrigerant circulation loop to operate in the third correction state. That is, in the third correction state, the pulse solenoid valve HSV1 in the first automatic valve branch 11 is in a 100% opening state, the first electronic expansion valve EEV1 is in a 100% opening state, the first solenoid valve SV2 in the second automatic valve branch 12 is open, the second electronic expansion valve EEV2 is in a 100% opening state, and the second solenoid valve SV1 in the manual valve branch 13 is open.

[0067] Optionally, during the operation of the refrigerant circulation loop in the first correction state or the second correction state, the control method further includes: determining whether the deviation between the real-time superheat value and the preset target superheat value meets the preset deviation value; if it does, adjusting the refrigerant circulation loop to the normal operating state.

[0068] The preset deviation value is pre-set based on the safety and stability of the refrigerant circulation loop operation. When the deviation between the real-time superheat value and the preset target superheat value is less than or equal to the preset deviation value, it indicates that the real-time superheat value is within a relatively stable range, and the refrigerant circulation loop is adjusted to normal operation. When the deviation between the real-time superheat value and the preset target superheat value is greater than the preset deviation value, the opening and closing status of each valve in the refrigerant circulation loop operation in the first correction state or the second correction state continues to be adjusted.

[0069] Optionally, during the operation of the refrigerant circulation loop in the first corrected state, the control method further includes: during the operation of the first electronic expansion valve in a state of increasing its opening in real time based on the first feedback signal, if the real-time superheat value is greater than the preset target superheat value when the opening of the first electronic expansion valve increases to 100%, then the first electronic expansion valve is kept operating at 100% opening, and the second electronic expansion valve is controlled to operate in a state of increasing its opening in real time based on the first feedback signal.

[0070] Specifically, during the operation of the refrigerant circulation loop in the first correction state, after the first electronic expansion valve is operated in a state of increasing its opening in real time based on the first feedback signal, and the opening of the first electronic expansion valve has reached its maximum opening, if the real-time superheat value is still greater than the preset target superheat value, then the first electronic expansion valve is kept operating at its maximum opening, and the second electronic expansion valve is controlled to operate in a state of increasing its opening in real time based on the first feedback signal, until the deviation between the real-time superheat value and the preset target superheat value meets the preset deviation value, thereby further improving the superheat adjustment accuracy and increasing the superheat adjustment range.

[0071] Optionally, during the operation of the refrigerant circulation loop in the second corrected state, the control method further includes: during the operation of the first electronic expansion valve in a state of real-time reduction of opening based on the second feedback signal, if the real-time superheat value is less than the preset target superheat value when the opening of the first electronic expansion valve is reduced to 10%, then the first electronic expansion valve is kept operating at 10% opening, and the pulse solenoid valve is controlled to operate in a state of real-time reduction of opening based on the second feedback signal.

[0072] Specifically, during the operation of the refrigerant circulation loop in the second correction state, after the first electronic expansion valve is operated in a state of real-time reduction of opening based on the second feedback signal, the opening of the first electronic expansion valve has reached the minimum opening. If the real-time superheat value is still less than the preset target superheat value, the first electronic expansion valve is kept operating at the minimum opening, and the pulse solenoid valve is controlled to operate in a state of real-time reduction of opening based on the second feedback signal until the deviation between the real-time superheat value and the preset target superheat value meets the preset deviation value, thereby further improving the superheat adjustment accuracy and increasing the superheat adjustment range.

[0073] Optionally, before obtaining the real-time superheat value of the refrigerant circulation loop, the following steps are also included:

[0074] Obtain the real-time subcooling value of the refrigerant circulation loop; determine whether the real-time subcooling value meets the preset target subcooling value. If it does, proceed to obtain the real-time superheat value of the refrigerant circulation loop; if it does not, adjust the speed of the variable frequency condenser fan based on the third feedback signal until the real-time subcooling value meets the preset target subcooling value.

[0075] The third feedback signal is a deviation feedback signal calculated based on the difference between the real-time subcooling value and the preset target subcooling value. Specifically, the high-temperature, high-pressure steam discharged from the variable frequency compressor undergoes a phase change from gaseous to liquid after passing through the condenser group (composed of a condenser and a variable frequency condenser fan). After passing through the liquid receiver, only liquid flows out, while the gas is stored in the liquid receiver. A pressure sensor monitors the real-time pressure value after the liquid receiver, and a temperature sensor monitors the real-time temperature value. Based on the pressure and temperature values, the real-time subcooling value can be calculated and output in real time. It is then determined whether the real-time subcooling value meets the preset target subcooling value. If it does, the step of obtaining the real-time superheat value of the refrigerant circulation loop is executed. If it does not meet the target, the deviation between the real-time subcooling value and the preset target subcooling value is calculated using PID control. The variable frequency condenser fan adjusts its speed based on the deviation signal fed back from the real-time subcooling value to ensure that the real-time subcooling after the condenser remains constant within the set deviation range.

[0076] Optionally, obtaining the real-time superheat value of the refrigerant circulation loop includes: obtaining the real-time pressure value and real-time temperature value of the evaporator outlet in the refrigerant circulation loop, and determining the real-time superheat value of the refrigerant circulation loop based on the real-time pressure value and real-time temperature value.

[0077] The real-time pressure value is obtained by a pressure sensor, and the real-time temperature value is obtained by a temperature sensor.

[0078] This invention also provides a refrigerant circulation loop that executes the control method for the refrigerant circulation loop of any embodiment of this invention. (Continuing on...) Figure 2 The refrigerant circulation loop specifically includes: at least two automatic valve branches (i.e., the first automatic valve branch 11 and the second automatic valve branch 12), at least one manual valve branch 13, a variable frequency compressor CM, a condenser COND, a liquid receiver LR, an evaporator EVAP, and a gas-liquid separator RA; the at least two automatic valve branches and the at least one manual valve branch are connected in parallel; the variable frequency compressor CM, the condenser COND, the liquid receiver LR, the parallel valve branches, the evaporator EVAP, and the gas-liquid separator RA are sequentially connected to form the refrigerant circulation loop.

[0079] The first automatic valve branch 11 includes a pulse solenoid valve HSV1 and a first electronic expansion valve EEV1 connected in series; the second automatic valve branch 12 includes a first solenoid valve SV2 and a second electronic expansion valve EEV2 connected in series; and the manual valve branch 13 includes a second solenoid valve SV1 and a manual expansion valve MEV1 connected in series. The operating status of each valve in the first automatic valve branch 11, the second automatic valve branch 12, and the manual valve branch 13 is adjusted based on the current value range of the real-time superheat value at the evaporator outlet.

[0080] Optionally, the refrigerant circulation loop further includes: a first refrigerant charging valve TV1, a receiver-after-temperature sensor TT1, a dryer filter D1, a sight glass SGN, a receiver-after-pressure sensor TP1, an evaporator-after-temperature sensor TT2, a second refrigerant charging valve TV2, and an evaporator-after-pressure sensor TP2; the first refrigerant charging valve TV1, the receiver-after-temperature sensor TT1, the dryer filter D1, and the sight glass SGN are sequentially connected between the receiver LR and each valve branch connected in parallel; the receiver-after-pressure sensor TP1 is connected to the first refrigerant charging valve TV1; the evaporator-after-temperature sensor TT2 and the second refrigerant charging valve TV2 are sequentially connected between the evaporator EVAP and the gas-liquid separator RA; and the evaporator-after-pressure sensor TP2 is connected to the second refrigerant charging valve TV2.

[0081] The refrigerant circulation loop works as follows: After the refrigerant is discharged from the discharge port of the variable frequency compressor CM, it sequentially enters the condenser COND (including the variable frequency condenser fan FD1), the liquid receiver LR, the dryer filter D1, the sight glass SGN, and at least two automatic valve branches and at least one manual valve branch are connected in parallel: the first automatic valve branch includes the pulse solenoid valve HSV1 and the first electronic expansion valve EEV1 connected in series, the second automatic valve branch includes the first solenoid valve SV2 and the second electronic expansion valve EEV2 connected in series, and the manual valve branch includes the second solenoid valve SV1 and the manual expansion valve MEV1 connected in series. After the parallel loop, the refrigerant flows through the evaporator EVAP (including the evaporator fan FD2), and then through the gas-liquid separator RA. The refrigerant after exiting the gas-liquid separator RA enters the variable frequency compressor CM, forming a closed loop.

[0082] The variable frequency compressor (CM) is the core power source of this refrigerant circulation loop. It compresses the low-temperature, low-pressure refrigerant vapor into high-pressure, high-temperature superheated vapor, creating conditions for condensation at a higher temperature. It then transports and drives the refrigerant to flow within the loop, completing the refrigeration cycle and achieving the purpose of refrigeration through heat-work conversion. The purpose of using a variable frequency compressor is to quickly respond to different heating power requirements and customer response time requirements, ensuring that the system can reach the required operating state and boundary conditions in a short time, while also providing energy-saving advantages.

[0083] The condenser COND and condenser fan FD1 are used to condense the high-pressure, high-temperature refrigerant vapor delivered by the variable frequency compressor into a high-pressure, high-temperature liquid. The condensation process is a heat dissipation process, so the evaporator is a device that condenses refrigerant vapor into a refrigerant liquid. The function of the condenser fan is to transfer the heat dissipated by the refrigerant in the evaporator to the air, maintaining the condensing temperature and pressure within a reasonable range.

[0084] The receiver LR is used to store the liquid component of the refrigerant, reduce the load on the evaporator, and adapt to the supply demand caused by load changes. When the evaporation load increases, the supply also increases, and it is replenished by the liquid stored in the receiver; when the load decreases, the required liquid volume also decreases, and the excess liquid is stored in the receiver tank.

[0085] The dryer filter D1 is used to absorb moisture in the refrigerant circulation loop, block impurities in the loop from passing through, and prevent blockage of the system piping.

[0086] The sight glass (SGN) is used to observe the refrigerant level, determine whether the system is operating properly, and detect whether there is water vapor downstream of the dryer filter in the system.

[0087] The first / second solenoid valve SV1 / 2 is used to control the flow of refrigerant according to the power supply status. It is closed when not energized, which can restrict the flow of refrigerant. When the valve coil is energized, the flow of refrigerant is allowed.

[0088] The first electronic expansion valve EEV1, the second electronic expansion valve EEV2, and the manual expansion valve MEV1 are used to control the injection of liquid refrigerant into the evaporator. When the refrigerant passes through the electronic expansion valve, it can achieve isenthalpic pressure reduction and control the refrigerant flow through the system signal, so that the superheat at the evaporator outlet is kept at a certain level, preventing the liquid refrigerant from leaving the evaporator and entering the variable frequency compressor.

[0089] The evaporator EVAP and evaporator fan FD2 are used to evaporate the low-pressure, low-temperature gas-liquid mixture of refrigerant, throttled by the electronic expansion valve, into a low-pressure, medium-temperature gas. Evaporation is an endothermic process, so the evaporator is a device that evaporates liquid refrigerant into gas. The function of the evaporator fan is to transfer the cooled refrigerant released from the evaporator into the air.

[0090] The HSV1 pulse solenoid valve is a solenoid valve used to perform rapid cyclic cycles in a short period of time to maintain a very close temperature, thereby regulating the refrigerant flow while keeping the pressure essentially constant.

[0091] The gas-liquid separator RA is used to contain the refrigerant returning to the system, preventing liquid slugging in the compressor and dilution of the compressor oil by excessive refrigerant.

[0092] Pressure sensors are used to measure the system's operating pressure in real time. By monitoring the pressure, it can be ensured that the system operates within the specified requirements. Temperature sensors are used to measure the system's operating temperature in real time. By monitoring the temperature, it can be ensured that the system operates within the specified requirements.

[0093] The refrigerant circulation loop provided in the embodiments of the present invention can execute the control method of the refrigerant circulation loop provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method.

[0094] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0095] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A control method for a refrigerant circulation loop, characterized in that, include: Obtain the real-time superheat value of the refrigerant circulation loop; Determine the current value range of the real-time superheat value, wherein the current value range includes a first value range and a second value range, the minimum value of the second value range is greater than or equal to the maximum value of the first value range; the first value range is the value range of the superheat value when the refrigerant circulation loop is operating normally, and the second value range is the value range of the superheat value when the refrigerant circulation loop is operating abnormally. When the real-time superheat value is within the first numerical range, the valve opening and closing status of each automatic valve branch in the refrigerant circulation loop is controlled based on the relationship between the real-time superheat value and the preset target superheat value. When the real-time superheat value is within the second numerical range, the manual valve branch in the refrigerant circulation loop is opened. When the real-time superheat value is within the first numerical range, controlling the valve opening and closing status of each automatic valve branch in the refrigerant circulation loop based on the relationship between the real-time superheat value and the preset target superheat value includes: If the real-time superheat value is greater than the preset target superheat value, the valves of each automatic valve branch in the refrigerant circulation loop are adjusted from the normal operating state to the first correction state. The normal operating state is as follows: the pulse solenoid valve in the first automatic valve branch is operating at 100% opening, the first electronic expansion valve is operating at 50% opening, the first solenoid valve in the second automatic valve branch is open, the second electronic expansion valve is operating at 10% opening, and the second solenoid valve in the manual valve branch is closed. The first corrected state is as follows: the pulse solenoid valve in the first automatic valve branch is operating at 100% opening, the first electronic expansion valve is operating by increasing its opening in real time based on the first feedback signal, the first solenoid valve in the second automatic valve branch is open, and the second solenoid valve in the manual valve branch is closed. If the real-time superheat value is less than the preset target superheat value, the valves of each automatic valve branch in the refrigerant circulation loop are adjusted from the normal operating state to the second correction state. The second correction state is as follows: the pulse solenoid valve in the first automatic valve branch is operating at 100% opening, the first electronic expansion valve is operating by reducing its opening in real time based on the second feedback signal, the first solenoid valve in the second automatic valve branch is open, and the second solenoid valve in the manual valve branch is closed. When the real-time superheat value is within the second numerical range, controlling the opening of the manual valve branch in the refrigerant circulation loop includes: When the real-time superheat value is within the second numerical range, each valve branch in the refrigerant circulation loop is controlled to operate in a third correction state. The third correction state is as follows: the pulse solenoid valve in the first automatic valve branch is operating at 100% opening, the first electronic expansion valve is operating at 100% opening, the first solenoid valve in the second automatic valve branch is open, the second electronic expansion valve is operating at 100% opening, and the second solenoid valve in the manual valve branch is open.

2. The control method according to claim 1, characterized in that, During the operation of the refrigerant circulation loop in the first corrected state or the second corrected state, the control method further includes: Determine whether the deviation between the real-time superheat value and the preset target superheat value meets the preset deviation value. If it does, adjust the refrigerant circulation loop to the normal operating state.

3. The control method according to claim 1, characterized in that, During the operation of the refrigerant circulation loop in the first corrected state, the control method further includes: During the operation of the first electronic expansion valve in a state of increasing its opening degree in real time based on the first feedback signal, if the real-time superheat value is greater than the preset target superheat value when the opening degree of the first electronic expansion valve increases to 100%, then the first electronic expansion valve will be kept in the state of 100% opening degree, and the second electronic expansion valve will be controlled to operate in a state of increasing its opening degree in real time based on the first feedback signal.

4. The control method according to claim 1, characterized in that, During the operation of the refrigerant circulation loop in the second corrected state, the control method further includes: During the operation of the first electronic expansion valve in a state of real-time reduction of opening based on the second feedback signal, if the real-time superheat value is less than the preset target superheat value when the opening of the first electronic expansion valve is reduced to 10%, then the first electronic expansion valve will be kept in the state of 10% opening, and the pulse solenoid valve will be controlled to operate in a state of real-time reduction of opening based on the second feedback signal.

5. The control method according to claim 1, characterized in that, Before obtaining the real-time superheat value of the refrigerant circulation loop, the method further includes: Obtain the real-time subcooling value of the refrigerant circulation loop; Determine whether the real-time subcooling value meets the preset target subcooling value. If it does, then execute the step of obtaining the real-time superheat value of the refrigerant circulation loop. If the condition is not met, the speed of the variable frequency condenser fan is adjusted based on the third feedback signal until the real-time subcooling value meets the preset target subcooling value.

6. The control method according to claim 1, characterized in that, The process of obtaining the real-time superheat value of the refrigerant circulation loop includes: Obtain the real-time pressure and temperature values ​​at the evaporator outlet in the refrigerant circulation loop; The real-time superheat value of the refrigerant circulation loop is determined based on the real-time pressure value and the real-time temperature value.

7. A refrigerant circulation loop, characterized in that, The refrigerant circulation loop performs the control method of the refrigerant circulation loop according to any one of claims 1-6, and the refrigerant circulation loop includes: at least two automatic valve branches, at least one manual valve branch, a variable frequency compressor, a condenser, a liquid receiver, an evaporator, and a gas-liquid separator. At least two automatic valve branches and at least one manual valve branch are connected in parallel; the variable frequency compressor, the condenser, the liquid receiver, the parallel valve branches, the evaporator, and the gas-liquid separator are sequentially connected to form the refrigerant circulation loop; The first automatic valve branch includes a pulse solenoid valve and a first electronic expansion valve connected in series; the second automatic valve branch includes a first solenoid valve and a second electronic expansion valve connected in series; and the manual valve branch includes a second solenoid valve and a manual expansion valve connected in series. The operating status of each valve in the first automatic valve branch, the second automatic valve branch, and the manual valve branch is adjusted based on the current value range of the real-time superheat value at the evaporator outlet.

8. The refrigerant circulation loop according to claim 7, characterized in that, The refrigerant circulation loop also includes: a first refrigerant charging valve, a temperature sensor after the receiver, a dryer filter, a sight glass, a pressure sensor after the receiver, a temperature sensor after the evaporator, a second refrigerant charging valve, and a pressure sensor after the evaporator. The first refrigerant charging valve, the temperature sensor after the liquid receiver, the dryer filter, and the sight glass are sequentially connected between the liquid receiver and each valve branch connected in parallel. The pressure sensor after the liquid reservoir is connected to the first refrigerant charging valve. The temperature sensor after the evaporator and the second refrigerant charging valve are sequentially connected between the evaporator and the gas-liquid separator; The pressure sensor after the evaporator is connected to the second refrigerant charging valve.

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