Jet enthalpy-increasing heat pump system control method and device, and jet enthalpy-increasing heat pump system

Abstract

The present disclosure relates to a control method and device for a jet enthalpy heat pump system, and a jet enthalpy heat pump system, wherein the control method comprises: during the stable operation of the compressor, judging whether a trough appears in the exhaust temperature variation curve of the compressor; when a trough appears in the exhaust temperature variation curve, calculating the difference ΔT between the current actual exhaust superheat T and the initial target exhaust superheat T0; when the difference ΔT is not higher than a first preset difference ΔT1, entering exhaust peak-valley control, and during the exhaust peak-valley control process, adjusting the liquid injection electronic expansion valve (5) in stages according to the difference ΔT so that the current actual exhaust superheat T gradually reaches the initial target exhaust superheat T0, and the liquid injection electronic expansion valve (5) is located between the condenser (3) and the flash tank (7).

Description

Technical Field

[0001] The present disclosure relates to the technical field of heat pump control, and in particular to a control method and device for a jet enthalpy-increasing heat pump system, and a jet enthalpy-increasing heat pump system. Background Art

[0002] Compared with conventional heat pump systems, the jet enthalpy heat pump system adds a flash tank, an electronic expansion valve and a solenoid valve. Since the flash tank has the function of storing refrigerant, the refrigerant circulation volume in the system varies greatly. In addition, the jet enthalpy heat pump system has two electronic expansion valves, which are respectively set before and after the flash tank to adjust the refrigerant circulation volume. The coordinated control of these three variables has a greater impact on exhaust fluctuations, especially when the actual exhaust superheat is relatively low, the liquid injection electronic expansion valve continues to close excessively, causing the exhaust temperature to soar to the protection temperature. Summary of the invention

[0003] The embodiments of the present disclosure provide a control method and device for a jet enthalpy heat pump system, and a jet enthalpy heat pump system, which can ensure stable operation of the jet enthalpy heat pump system.

[0004] According to a first aspect of the present disclosure, there is provided a method for controlling an injection enthalpy heat pump system, comprising:

[0005] During the stable operation of the compressor, determine whether a trough appears in the exhaust temperature variation curve of the compressor;

[0006] When the exhaust temperature variation curve has a trough, the difference ΔT between the current actual exhaust superheat T and the initial target exhaust superheat T0 is calculated;

[0007] When the difference ΔT is not higher than the first preset difference ΔT1, the exhaust peak-valley control is entered. During the exhaust peak-valley control process, the liquid injection electronic expansion valve is adjusted in stages according to the difference ΔT so that the current actual exhaust superheat T gradually reaches the initial target exhaust superheat T0. The liquid injection electronic expansion valve is located between the condenser and the flash tank.

[0008] In some embodiments, the control method of the jet enthalpy heat pump system further includes:

[0009] When the current actual exhaust superheat T reaches the initial target exhaust superheat T0, the exhaust peak-valley control is exited.

[0010] In some embodiments, when the difference ΔT is not lower than the second preset difference ΔT2 and is not higher than the first preset difference ΔT1, the first exhaust peak-valley control step is entered; when the difference ΔT is lower than the second preset difference ΔT2, the second exhaust peak-valley control step is entered;

[0011] The number of stages in the first exhaust peak-valley control step is smaller than the number of stages in the second exhaust peak-valley control step, and the second preset difference ΔT2 is lower than the first preset difference ΔT1.

[0012] In some embodiments, when the difference ΔT is not lower than the second preset difference ΔT2 and is not higher than the first preset difference ΔT1, the second preset difference ΔT2 is lower than the first preset difference ΔT1, and the first exhaust peak-valley control step is entered. The first exhaust peak-valley control step includes:

[0013] The liquid injection electronic expansion valve is adjusted according to the first target exhaust gas superheat T01, T01=T0+ΔT1; wherein the first target exhaust gas superheat T01 is lower than the target exhaust gas superheat T0;

[0014] After reaching the first target exhaust superheat degree T01, the exhaust superheat degree is restored to the initial target exhaust superheat degree T0.

[0015] In some embodiments, when the difference ΔT is lower than the second preset difference ΔT2, the second preset difference ΔT2 is lower than the first preset difference ΔT1, and the second exhaust peak-valley control step is entered, and the second exhaust peak-valley control step includes:

[0016] The liquid injection electronic expansion valve is adjusted according to the second target exhaust gas superheat T02, T02 = T0 + ΔT2;

[0017] After reaching the second target exhaust superheat T02, the liquid injection electronic expansion valve is adjusted according to the first target exhaust superheat T01, T01 = T0 + ΔT1;

[0018] After reaching the first target exhaust superheat T01, the exhaust superheat is restored to the initial target exhaust superheat T0;

[0019] The first target exhaust superheat T01 is lower than the target exhaust superheat T0, and the second target exhaust superheat T02 is lower than the first target exhaust superheat T01.

[0020] In some embodiments, the step of determining whether a trough appears in the variation curve of the exhaust gas temperature of the compressor comprises:

[0021] Continuously calculate the difference ΔT between the current exhaust temperature and the exhaust temperature at the previous step time point 排气 ;

[0022] When the difference ΔT appears 排气 Not exceeding the first preset temperature difference ΔT1 排气 In the case of, the time t for finding the trough starts to count, the first preset temperature difference ΔT1 排气 is a negative value;

[0023] During the timing process, if a difference ΔT occurs 排气 Not less than the second preset temperature difference ΔT2 排气 , the second preset temperature difference ΔT2 排气 is a positive value, and the time t to find the trough does not exceed the preset holding time t 维持 In the case of , it is determined that a trough occurs.

[0024] In some embodiments, when it is determined that a trough occurs, the control method of the jet enthalpy heat pump system further includes:

[0025] Let the time for finding the valley be t=0, and let the exhaust valley mark f=1.

[0026] In some embodiments, the step of determining whether a trough appears in the variation curve of the exhaust gas temperature of the compressor further includes:

[0027] During the timing process, if a difference ΔT occurs 排气 =0, and the time t to find the trough does not exceed the preset holding time t 维持 In this case, maintain the timing.

[0028] In some embodiments, the step of determining whether a trough appears in the variation curve of the exhaust gas temperature of the compressor further includes:

[0029] When the time t to find the trough exceeds the preset holding time t 维持 In this case, stop timing and set the time for searching the trough t=0.

[0030] According to a second aspect of the present disclosure, there is provided a control device for an injection enthalpy heat pump system, comprising:

[0031] a memory configured to store instructions;

[0032] The processor is configured to execute the instructions so that the control device executes the injection enthalpy heat pump system control method described in the above embodiment.

[0033] According to a third aspect of the present disclosure, there is provided a jet enthalpy heat pump system, comprising the jet enthalpy heat pump system control device of the above embodiment.

[0034] According to a fourth aspect of the present disclosure, a non-transitory computer-readable storage medium is provided, wherein the computer-readable storage medium stores computer instructions, and when the instructions are executed by a processor, the control method of the jet enthalpy heat pump system of the above embodiment is implemented.

[0035] The control method of the jet reheat heat pump system of the embodiment of the present disclosure adopts an exhaust peak and valley control method, which first finds the exhaust trough, and then controls the rise of the exhaust temperature by controlling the staged adjustment of the liquid injection electronic expansion valve to prevent over-adjustment from causing a surge in the exhaust temperature, thereby reducing the exhaust peak and reducing the exhaust temperature fluctuation, thereby ensuring stable operation of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The drawings described herein are used to provide a further understanding of the present disclosure and constitute a part of the present application. The illustrative embodiments of the present disclosure and their descriptions are used to explain the present disclosure and do not constitute an improper limitation on the present disclosure. In the drawings:

[0037] Figure 1 The schematic diagram is a schematic diagram of some embodiments of the jet enthalpy heat pump system disclosed in the present invention.

[0038] Figure 2 The present invention provides a flow chart of some embodiments of the control method of the jet enthalpy heat pump system.

[0039] Figure 3 Flow charts of some embodiments of the peak-valley control method.

[0040] Figure 4 Flowchart of some embodiments for finding exhaust temperature valleys.

[0041] Figure 5 Flowcharts of some specific embodiments for finding exhaust temperature valleys.

[0042] Figure 6 This is a comparison chart of the exhaust temperature change curves before and after using the peak-valley control method.

[0043] Figure 7 The present invention is a schematic diagram of the module composition of some embodiments of the control device of the jet enthalpy increase heat pump system disclosed in the present invention. DETAILED DESCRIPTION

[0044] The present disclosure is described in detail below. In the following paragraphs, different aspects of the embodiments are defined in more detail. Each aspect so defined can be combined with any other aspect or aspects, unless explicitly stated not to be combined. In particular, any feature that is considered to be preferred or advantageous can be combined with one or more other features that are considered to be preferred or advantageous.

[0045] The terms "first", "second", etc. that appear in the present disclosure are only for the convenience of description to distinguish different components with the same name, and do not indicate a sequence or a primary and secondary relationship.

[0046] In addition, when an element is referred to as being "on" another element, the element may be directly on the other element, or may be indirectly on the other element with one or more intermediate elements interposed therebetween. In addition, when an element is referred to as being "connected to" another element, the element may be directly connected to the other element, or may be indirectly connected to the other element with one or more intermediate elements interposed therebetween. Hereinafter, the same reference numerals represent the same elements.

[0047] The descriptions of directions or positional relationships indicated by “upper”, “lower”, “top”, “bottom”, “front”, “back”, “inside” and “outside” are used in the present disclosure only to facilitate the description of the present disclosure, and do not indicate or imply that the device referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the scope of protection of the present disclosure.

[0048] At present, the control method used in conventional heat pump systems is:

[0049] When the unit detects that the actual exhaust superheat - target exhaust superheat ≤ △t1, the liquid injection electronic expansion valve will close. Because closing the liquid injection electronic expansion valve 5 will reduce the refrigerant circulation volume and reduce the low pressure, according to the principle of the pressure-enthalpy diagram, the exhaust temperature will increase along the isentropic line and the exhaust superheat will also increase.

[0050] The greater the difference between |actual exhaust superheat - target exhaust superheat|, the greater the number of steps for closing the liquid injection electronic expansion valve; when △t1<actual exhaust superheat - target exhaust superheat ≤△t2, the liquid injection electronic expansion valve maintains the current number of steps unchanged; when actual exhaust superheat - target exhaust superheat >△t2, the liquid injection electronic expansion valve will open, and the greater the difference between actual exhaust superheat and target exhaust superheat, the greater the number of steps for opening the liquid injection electronic expansion valve 5.

[0051] The above conventional control method is fully applicable when the exhaust temperature of a conventional heat pump changes normally. However, when used in a jet enthalpy heat pump system, the presence of the flash tank will buffer the refrigerant, and the change of the system refrigerant is delayed. When the liquid injection electronic expansion valve is continuously closed, the exhaust temperature first rises to a controllable range, and then soars to the protection temperature. When the valve is opened again, it is already out of control.

[0052] Through research, the inventors found that the main reason why the compressor exhaust temperature soars during the closing process of the liquid spray electronic expansion valve is that: when the actual exhaust superheat is relatively low, the liquid spray electronic expansion valve will continue to close the valve to cause the exhaust temperature to rise, but excessive closing of the liquid spray electronic expansion valve will cause the high-pressure exhaust temperature to rise; at the same time, the jet enthalpy increase system cannot obtain liquid in the flash tank, and the exhaust temperature cannot be reduced; and because the liquid spray electronic expansion valve is excessively closed, the refrigerant circulation volume on the low-pressure side is reduced, and the compressor motor raises the refrigerant temperature again. Multiple factors cause the exhaust temperature to soar to the protection temperature.

[0053] Based on the above-mentioned jet enthalpy increase heat pump system, the present disclosure provides a jet enthalpy increase heat pump system control method, hereinafter referred to as "control method". In order to more clearly understand the control method, the working principle of the jet enthalpy increase system is first described.

[0054] Figure 1 The schematic diagram of some embodiments of the jet enthalpy heat pump system is shown in FIG. The main refrigerant circulation loop of the jet enthalpy heat pump system is provided with a compressor 1, an evaporator 12, a condenser 3, a four-way valve 2 and a flash tank 7. The four-way valve 2 is used to switch the heat exchange state of the evaporator 12 and the condenser 3.

[0055] The evaporator 12 may be a fin heat exchanger, and a fan 13 is provided near the evaporator 12 to accelerate the heat exchange process. A vapor-liquid separator 14 may be provided between the evaporator 12 and the compressor 1 to separate the gaseous refrigerant from the evaporated gas-liquid mixed refrigerant to supply it to the compressor.

[0056] The condenser 3 is a water-side heat exchanger, which can be connected to a water circulation loop. A terminal radiator is arranged on the water circulation loop to cool the water so as to dissipate heat from the condenser 3. A circulation pump 15 is also arranged on the water circulation loop to drive the water to flow.

[0057] The flash tank 7 is used to evaporate the liquid refrigerant generated after condensation in the condenser 3, and part of it is provided to the evaporator 12, and the other part is supplemented to the refrigerant port of the compressor 1 through the refrigerant branch to reduce the exhaust temperature of the compressor 1. A liquid injection solenoid valve 8 can be set on the refrigerant branch to control the on and off of the refrigerant branch, and the refrigerant flow rate can be further controlled in the on state.

[0058] An electronic expansion valve 10 may be provided between the flash tank 7 and the evaporator 12 to achieve throttling and cooling, and to adjust the flow of refrigerant provided from the flash tank 7 to the evaporator 12. A liquid-spraying electronic expansion valve 5 may be provided directly between the flash tank 7 and the condenser 3 to achieve throttling and cooling, and to adjust the flow of refrigerant provided from the condenser 3 to the flash tank 7, and to achieve throttling and cooling.

[0059] Optionally, a first filter 4 and a second filter 6 are respectively disposed on both sides of the liquid-spraying electronic expansion valve 5 , and a third filter 9 and a fourth filter 11 are respectively disposed on both sides of the electronic expansion valve 10 .

[0060] Optionally, an intake temperature sensing bag 18 is provided at the inlet of the compressor 1, an exhaust temperature sensing bag 19 is provided at the outlet, a low pressure switch 23 is provided at the inlet of the compressor 1, and a high pressure switch 24 is provided at the outlet for detecting gas pressure.

[0061] Optionally, an inlet temperature sensing package 20 is provided at the liquid inlet of the evaporator 12 , an air intake temperature sensing package 21 is provided at the air outlet, and an environment temperature sensing package 22 is provided outside the evaporator 12 .

[0062] Optionally, the water outlet of the condenser 3 is provided with a water outlet temperature sensing package 26, the water inlet is provided with a water inlet temperature sensing package 25, and the water circulation loop is provided with a water flow switch 16 for detecting water pressure.

[0063] Based on the above-mentioned jet enthalpy heat pump system, the present disclosure provides a jet enthalpy heat pump system control method, hereinafter referred to as "control method". In some embodiments, Figure 2 As shown, the control method includes:

[0064] Step 110: during the stable operation of the compressor 1, determine whether a trough appears in the exhaust temperature variation curve of the compressor 1;

[0065] Step 120, when the exhaust temperature variation curve has a trough, calculating the difference ΔT between the current actual exhaust superheat T and the initial target exhaust superheat T0;

[0066] Step 130, when the difference ΔT is not higher than the first preset difference ΔT1, enter the exhaust peak-valley control. During the exhaust peak-valley control process, the liquid injection electronic expansion valve 5 is adjusted in stages according to the difference ΔT so that the current actual exhaust superheat T gradually reaches the initial target exhaust superheat T0. The liquid injection electronic expansion valve 5 is located between the condenser 3 and the flash tank 7.

[0067] Among them, steps 110 to 130 are executed sequentially.

[0068] In step 110, the determination of whether a trough appears in the exhaust temperature variation curve is always performed during the stable operation of the compressor. The exhaust temperature is detected by the exhaust temperature sensing package 19 provided at the outlet of the compressor 1. For example, the compressor 1 may be considered to have entered a stable operation process after a preset time has passed since it has been turned on. For example, the preset time may be 3 minutes, etc.; or the compressor 1 may be considered to have entered a stable operation process after a preset time has passed since the defrost is exited (i.e., the four-way valve is powered off). Because the exhaust is in an unstable stage when the defrost is exited, no trough determination is performed during this process. "Trough" means that the exhaust temperature at this moment is lower than the exhaust temperature at the previous and next moments.

[0069] In step 120, when the exhaust temperature variation curve has a trough, it indicates that the current exhaust temperature is low, and the opening of the liquid injection electronic expansion valve 5 needs to be reduced to achieve the target exhaust superheat T0. At this time, it is necessary to determine the difference between the current actual exhaust superheat T and the initial target exhaust superheat T0 by calculating the difference ΔT.

[0070] Among them, actual exhaust superheat = actual exhaust temperature - actual water outlet temperature, target exhaust superheat = target exhaust temperature - actual water outlet temperature. The exhaust temperature is detected by the exhaust temperature sensing package 19 installed at the outlet of the compressor 1, and the water outlet temperature is detected by the water outlet temperature sensing package 26 installed at the water outlet of the condenser 3.

[0071] In step 130, the difference ΔT and the first preset difference ΔT1 are both negative values, and the difference ΔT is not higher than the first preset difference ΔT1, indicating that the current actual exhaust superheat T has not reached the initial target exhaust superheat T0, and the gap is large. In this case, peak-valley control is entered to set multiple target exhaust superheats for staged adjustment to gradually reach the initial target exhaust superheat T0. In conventional control, the liquid injection electronic expansion valve 5 is prone to over-adjustment, resulting in a surge in exhaust temperature. Peak-valley control is to reduce the amplitude difference between the peaks and valleys and improve the stability of the exhaust temperature.

[0072] This embodiment adopts an exhaust peak-valley control method, which first finds the exhaust trough, and then controls the rise of the exhaust temperature by controlling the phased adjustment of the liquid injection electronic expansion valve to prevent over-adjustment from causing a surge in the exhaust temperature, thereby reducing the exhaust peak and exhaust temperature fluctuations to ensure stable operation of the unit.

[0073] In some embodiments, the control method of the jet enthalpy heat pump system further includes:

[0074] When the current actual exhaust superheat T reaches the initial target exhaust superheat T0, the exhaust peak-valley control is exited.

[0075] This embodiment can exit the exhaust peak and valley control in time when the current actual exhaust superheat T reaches the initial target exhaust superheat T0 and the exhaust temperature reaches the target value, and adopts a conventional control method without staged adjustment. It directly adjusts according to the initial target exhaust superheat T0 and looks for the next trough. This method can reduce the difficulty of control.

[0076] In some embodiments, when the difference ΔT is not lower than the second preset difference ΔT2 and not higher than the first preset difference ΔT1, the first exhaust peak-valley control step is entered; when the difference ΔT is lower than the second preset difference ΔT2, the second exhaust peak-valley control step is entered; wherein the number of stages in the first exhaust peak-valley control step is smaller than the number of stages in the second exhaust peak-valley control step, and the second preset difference ΔT2 is lower than the first preset difference ΔT1.

[0077] The difference ΔT, the second preset difference ΔT2 and the first preset difference ΔT1 are all negative values.

[0078] Among them, when ΔT2≤ΔT≤ΔT1, it means that in the peak-valley control condition, the difference between the current actual exhaust superheat T and the initial target exhaust superheat T0 is in a small range, and the first exhaust peak-valley control step is entered, and a smaller number of stages can be set, such as two-stage control. In the case of ΔT≤ΔT2, it means that in the peak-valley control condition, the difference between the current actual exhaust superheat T and the initial target exhaust superheat T0 is in a large range, and the second exhaust peak-valley control step is entered, and a larger number of stages can be set, such as three-stage control. The first exhaust peak-valley control step and the second exhaust peak-valley control step belong to two different branches of peak-valley control.

[0079] This embodiment can adopt different numbers of staged control strategies according to the different intervals of the difference ΔT when the difference ΔT meets the peak-valley control conditions, so that the current actual exhaust superheat T can reach the initial target exhaust superheat T0 more accurately and smoothly, preventing over-adjustment from causing exhaust temperature to soar, thereby reducing the exhaust peak, reducing exhaust temperature fluctuations, and ensuring stable operation of the unit.

[0080] In some embodiments, the control method further comprises:

[0081] Step 200 , determining the relationship between the difference ΔT and the first preset difference ΔT1 and the second preset difference ΔT2 .

[0082] like Figure 3 As shown, when the difference ΔT is not less than the second preset difference ΔT2 and not higher than the first preset difference ΔT1, the second preset difference ΔT2 is lower than the first preset difference ΔT1, that is, ΔT2≤ΔT≤ΔT1, and the first exhaust peak-valley control step is entered. The first exhaust peak-valley control step includes:

[0083] Step 210, adjusting the liquid injection electronic expansion valve 5 according to the first target exhaust gas superheat T01, T01 = T0 + ΔT1; wherein the first target exhaust gas superheat T01 is lower than the target exhaust gas superheat T0;

[0084] Step 220 : After reaching the first target exhaust superheat T01 , restore to the initial target exhaust superheat T0 and make a new judgment.

[0085] This embodiment can enter the first exhaust peak-valley control step under the peak-valley control condition when the difference between the current actual exhaust superheat T and the initial target exhaust superheat T0 is in a small range, and control the target exhaust superheat in two stages. It can make the current actual exhaust superheat T reach the initial target exhaust superheat T0 more accurately and smoothly without increasing the control difficulty too much, prevent over-adjustment from causing a surge in exhaust temperature, thereby reducing the exhaust peak, reducing exhaust temperature fluctuations, and ensuring stable operation of the unit.

[0086] like Figure 3 As shown, when the difference ΔT is lower than the second preset difference ΔT2, that is, ΔT≤ΔT2, and the second preset difference ΔT2 is lower than the first preset difference ΔT1, the second exhaust peak-valley control step is entered, and the second exhaust peak-valley control step includes:

[0087] Step 230, adjusting the liquid injection electronic expansion valve 5 according to the second target exhaust gas superheat T02, T02 = T0 + ΔT2;

[0088] Step 240, after reaching the second target exhaust gas superheat T02, adjusting the liquid injection electronic expansion valve 5 according to the first target exhaust gas superheat T01, T01 = T0 + ΔT1;

[0089] Step 250, after reaching the first target exhaust gas superheat T01, restore to the initial target exhaust gas superheat T0, and re-judge;

[0090] The first target exhaust superheat T01 is lower than the target exhaust superheat T0, and the second target exhaust superheat T02 is lower than the first target exhaust superheat T01.

[0091] This embodiment can enter the second exhaust peak-valley control step under the peak-valley control condition when the difference between the current actual exhaust superheat T and the initial target exhaust superheat T0 is in a large range, and control the target exhaust superheat in three stages to make more precise adjustments according to the situation, so that the current actual exhaust superheat T can reach the initial target exhaust superheat T0 more accurately and smoothly, preventing over-adjustment from causing a surge in exhaust temperature, thereby reducing the exhaust peak, reducing exhaust temperature fluctuations, and ensuring stable operation of the unit.

[0092] The peak-valley control process is described below through a specific embodiment.

[0093] In the conventional control process, in the situation where actual exhaust superheat - target exhaust superheat ≤ △t1, △t1 is a relatively large value such as -1°C or -2°C, indicating that as long as the actual exhaust superheat is 1°C or 2°C lower than the target exhaust superheat, the liquid injection electronic expansion valve 5 will be closed, and the degree of closing depends on the actual difference.

[0094] In the peak-valley control process, the first preset difference ΔT1 is a smaller value, for example, ΔT1 = -15°C, ΔT2 = -25°C, and the initial target exhaust superheat T0 = 50°C.

[0095] Through detection, the current exhaust temperature is 76℃, the outlet water temperature is 55℃, then the actual exhaust superheat is 76-55=21℃, the current actual exhaust superheat T-initial target exhaust superheat T0=21-50=-29<ΔT2, at this time enter the second exhaust peak and valley control step, adopt the new second target exhaust superheat T02, T02=50-25=25℃, that is, first close the liquid injection electronic expansion valve 5 to raise the exhaust temperature to 25+55=80℃ After reaching the second target exhaust superheat T02, it is further updated to the first target exhaust superheat T01, T01=50-15=35°C, that is, the valve is closed again to raise the exhaust temperature to 35+55=90°C. After reaching the first target exhaust superheat T01, the control according to the initial target exhaust superheat T0=50°C is restored, that is, the liquid injection electronic expansion valve 5 is closed again to raise the exhaust temperature to 50=55=105°C. After meeting the requirements, the exhaust peak and valley control is exited.

[0096] If the exhaust temperature is 85°C and the outlet water temperature is 55°C when entering the exhaust peak-valley control, then the first exhaust peak-valley control step will be entered, and the exhaust peak-valley control will be exited after the requirements are met.

[0097] If the exhaust temperature is 95℃ and the outlet water temperature is 55℃ when entering the exhaust peak-valley control, then 95-55=40℃, actual exhaust superheat degree-target exhaust superheat degree=40-50=-10>ΔT1, and the exhaust peak-valley control is not entered, and the control is directly exited according to the conventional control. In this case, staged control is not required, the actual exhaust temperature is very close to the target exhaust temperature, and the liquid injection electronic expansion valve 5 will not be over-adjusted.

[0098] The purpose of the above control strategy is to control the exhaust temperature in stages when the difference between the actual exhaust temperature and the target exhaust temperature is too large, so as to prevent over-adjustment caused by closing the liquid injection electronic expansion valve 5.

[0099] In some embodiments, Figure 4 As shown, the step of determining whether a trough appears in the variation curve of the exhaust gas temperature of the compressor in step 110 includes:

[0100] Step 111: Continuously calculate the difference ΔT between the current exhaust temperature and the exhaust temperature at the previous time point 排气 ;

[0101] Step 112: When the difference ΔT appears 排气 Not exceeding the first preset temperature difference ΔT1 排气 In the case of, the time t for finding the trough starts to count, the first preset temperature difference ΔT1 排气 is a negative value;

[0102] Step 113: During the timing process, if a difference ΔT 排气 Not less than the second preset temperature difference ΔT2 排气 , the second preset temperature difference ΔT2 排气 is a positive value, and the time t to find the trough does not exceed the preset holding time t 维持 In the case of , it is determined that a trough occurs.

[0103] Among them, steps 111 to 113 are executed sequentially.

[0104] In step 111, the step length may be 1 second, that is, the difference ΔT between the current exhaust temperature and the exhaust temperature of the previous second is calculated. 排气 , by the difference ΔT 排气 Determine the changing trend of the exhaust temperature, such as increase, decrease or unchanged.

[0105] In step 112, the first preset temperature difference ΔT1 排气 is a negative value, for example, ΔT1 排气 = -1, at ΔT 排气 ≤ΔT1 排气 In the case of , the time t for finding the trough is started, for example, starting from 1s. ΔT 排气 ≤ΔT1 排气 Indicates that the exhaust temperature has a downward trend and starts to look for the trough, ΔT1 排气 = -1°C, other values ​​are also acceptable, but if |ΔT1 排气 If it is too large, the search accuracy may be low and the trough may be missed. For example, if ΔT1 排气 = -3℃ as the condition for finding the trough, if ΔT1 排气 =-1℃, the exhaust temperature will rise and this trough will be missed.

[0106] In step 113, during the timing process, the second preset temperature difference ΔT2 排气 is a positive value, if the difference ΔT 排气 ≥ΔT2 排气 , for example, ΔT2 排气 =1℃, and the time t to find the trough does not exceed the preset holding time t维持 In the case of, for example, t 维持 =60s, that is, 1s≤t≤60s, and it is determined that a trough appears.

[0107] This embodiment can be used to adjust the exhaust gas temperature difference ΔT 排气 Reaching the negative first preset temperature difference ΔT1 排气 , it means that the current exhaust temperature is decreasing, and the timing starts at this time. When looking for the trough period t 维持 If ΔT 排气 Reaching the positive second preset temperature difference ΔT2 排气 , it means that the current exhaust temperature is on the rise, and the trough can be determined accordingly. This method can accurately and continuously find the trough, and when the trough appears and the peak-valley control condition is met, the peak-valley control is performed.

[0108] In some embodiments, when it is determined that a trough occurs, the control method further includes:

[0109] Let the time for finding the valley be t=0, and let the exhaust valley mark f=1.

[0110] The default value of the exhaust trough mark is 0. After exiting the exhaust peak-valley control, f is restored to the default value, f = 0. Only when a trough is found, f = 1, otherwise, f = 0.

[0111] This embodiment can reset the trough search time t to zero after finding the trough so as to restart the search for the next trough. Moreover, after finding the trough, the exhaust trough mark f is set to 1 to determine the state of the trough according to the value of f during the control process.

[0112] In some embodiments, the step of determining whether a trough appears in the variation curve of the exhaust gas temperature of the compressor in step 110 further includes:

[0113] During the timing process, if a difference ΔT occurs 排气 =0, and the time t to find the trough does not exceed the preset holding time t 维持 In this case, maintain the timing.

[0114] This embodiment has a ΔT 排气 ≤ΔT1 排气 In the process of finding the trough time t, if the difference ΔT 排气 =0, it means that after the exhaust temperature shows a downward trend, there is no upward inflection point, and the trough has not appeared. At this time, if it has not exceeded the trough search period, the timing will continue to be maintained to wait for the trough to appear.

[0115] In some embodiments, the step of determining whether a trough appears in the variation curve of the exhaust gas temperature of the compressor in step 110 further includes:

[0116] When the time t to find the trough exceeds the preset holding time t 维持 In this case, stop timing and set the time for searching the trough t=0.

[0117] In this embodiment, the time t of searching for the trough exceeds the preset maintenance time t 维持 In the case of , it means that a trough search cycle ends, then the timing is stopped, and the trough search time t = 0, so that 排气 ≤ΔT1 排气 In this case, the next trough search cycle is started.

[0118] like Figure 5 As shown, a specific embodiment is given to illustrate how to find the exhaust temperature trough.

[0119] Continuously calculate the difference ΔT between the current exhaust temperature and the exhaust temperature at the previous step time point 排气 , at ΔT 排气 ≤ΔT1 排气 (For example, ΔT1 排气 =-1℃), it means that the exhaust temperature is decreasing and there may be a trough, so the time t for finding the trough starts from 1s; if ΔT 排气 >ΔT1 排气 , then the time to find the trough is t=0.

[0120] After the time t for finding the trough starts from 1s, there are three situations:

[0121] (1) If ΔT 排气 ≥ΔT2 排气 (For example, ΔT2 排气 =1°C), and then determine whether t≤t 维持 , specifically, 1≤t≤t 维持 If the exhaust gas trough is found, the exhaust gas trough mark f=1, t=0. Then, according to steps 120 and 130, it is determined whether the conditions for entering the exhaust gas temperature peak-valley control are met. If the conditions are met, the exhaust gas temperature peak-valley logic control is performed. After the exhaust gas temperature peak-valley control is completed and the initial target exhaust gas superheat T0 is reached, the exhaust gas trough mark f=0. If 1≤t≤t is not satisfied, the exhaust gas trough mark f=0 is set. 维持 , then the time is not counted, and the judgment continues to determine whether ΔT is satisfied 排气 ≤ΔT1 排气 .

[0122] (2) If ΔT 排气 =0, then determine whether t≤t维持 , specifically, 1≤t≤t 维持 If the condition is satisfied, the timing is continued, otherwise, no timing is performed. t=0, f=0, the unit controls the exhaust temperature according to the conventional logic and continuously determines ΔT 排气 .

[0123] (3) If ΔT 排气 ≤ΔT1 排气 (For example, ΔT1 排气 =-1°C), then the time t for finding the trough is started from 1s.

[0124] like Figure 6 As shown in the figure, curve 1 and curve 2 are the exhaust temperature change curves before and after the peak-valley control is adopted. It can be clearly seen that the oscillation amplitude of curve 1 is large and unstable. In the process of closing the liquid injection electronic expansion valve, the exhaust temperature is prone to over-adjustment. The oscillation amplitude of curve 2 is significantly reduced, and the exhaust temperature changes more steadily, which can prevent the exhaust temperature from over-adjusting and causing the exhaust temperature to soar.

[0125] Figure 7 Schematic diagram of some embodiments of the control device of the jet enthalpy heat pump system disclosed in the present invention. Figure 5 As shown, the control device of the present disclosure may include a memory 71 and a processor 72, wherein: the memory 71 is used to store instructions, the processor 72 is coupled to the memory 71, and the processor 72 is configured to execute the control method described in any of the above embodiments based on the instructions stored in the memory.

[0126] like Figure 7 As shown, the control device further includes a communication interface 73 for information exchange with other devices. At the same time, the control device further includes a bus 74, through which the processor 72, the communication interface 73, and the memory 71 communicate with each other.

[0127] The memory 71 may include a high-speed RAM memory, and may also include a non-volatile memory, such as at least one disk memory. The memory 71 may also be a memory array. The memory 71 may also be divided into blocks, and the blocks may be combined according to certain rules.

[0128] In addition, the processor 72 may be a central processing unit CPU, or may be an application specific integrated circuit ASIC, or may be configured to implement one or more integrated circuits of the embodiments of the present disclosure.

[0129] According to another aspect of the present disclosure, a non-transitory computer-readable storage medium is provided, wherein the computer-readable storage medium stores computer instructions, and when the instructions are executed by a processor, the control method as described in any of the above embodiments is implemented.

[0130] Each of the above steps in the inspection method disclosed herein can be performed by a processor. These controllers can be general-purpose processors, programmable logic controllers (PLC), digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or any appropriate combination thereof, for performing the functions described in the present disclosure.

[0131] The above is a detailed introduction to a control method and device for a jet enthalpy heat pump system and a jet enthalpy heat pump system provided by the present disclosure. Specific embodiments are used herein to illustrate the principles and implementation methods of the present disclosure. The description of the above embodiments is only used to help understand the method and core idea of ​​the present disclosure. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present disclosure, several improvements and modifications can be made to the present disclosure, and these improvements and modifications also fall within the scope of protection of the claims of the present disclosure.

Claims

1. A control method for a jet enthalpy heat pump system, characterized in that: include: During the stable operation of the compressor (1), determining whether a trough appears in the exhaust temperature variation curve of the compressor (1); When the exhaust temperature variation curve has a trough, the difference ΔT between the current actual exhaust superheat T and the initial target exhaust superheat T0 is calculated; When the difference ΔT is not higher than the first preset difference ΔT1, the exhaust peak-valley control is entered. During the exhaust peak-valley control process, the liquid injection electronic expansion valve (5) is adjusted in stages according to the difference ΔT so that the current actual exhaust superheat T gradually reaches the initial target exhaust superheat T0. The liquid injection electronic expansion valve (5) is located between the condenser (3) and the flash tank (7).

2. The control method of the jet enthalpy heat pump system according to claim 1, characterized in that: Also includes: When the current actual exhaust superheat T reaches the initial target exhaust superheat T0, the exhaust peak-valley control is exited.

3. The control method of the jet enthalpy heat pump system according to claim 1, characterized in that: When the difference ΔT is not lower than the second preset difference ΔT2 and is not higher than the first preset difference ΔT1, the first exhaust peak-valley control step is entered; when the difference ΔT is lower than the second preset difference ΔT2, the second exhaust peak-valley control step is entered; The number of stages in the first exhaust peak-valley control step is smaller than the number of stages in the second exhaust peak-valley control step, and the second preset difference ΔT2 is lower than the first preset difference ΔT1.

4. The control method of the jet enthalpy heat pump system according to claim 1, characterized in that: When the difference ΔT is not lower than the second preset difference ΔT2 and not higher than the first preset difference ΔT1, the second preset difference ΔT2 is lower than the first preset difference ΔT1, and the first exhaust peak-valley control step is entered. The first exhaust peak-valley control step includes: The liquid injection electronic expansion valve (5) is adjusted according to a first target exhaust gas superheat T01, T01=T0+ΔT1; wherein the first target exhaust gas superheat T01 is lower than the target exhaust gas superheat T0; After reaching the first target exhaust superheat degree T01, the exhaust superheat degree is restored to the initial target exhaust superheat degree T0.

5. The control method of the jet enthalpy heat pump system according to claim 1, characterized in that: When the difference ΔT is lower than the second preset difference ΔT2, and the second preset difference ΔT2 is lower than the first preset difference ΔT1, the second exhaust peak-valley control step is entered, and the second exhaust peak-valley control step includes: The liquid injection electronic expansion valve (5) is adjusted according to a second target exhaust gas superheat T02, T02=T0+ΔT2; After the second target exhaust gas superheat T02 is reached, the liquid injection electronic expansion valve (5) is adjusted according to the first target exhaust gas superheat T01, T01=T0+ΔT1; After reaching the first target exhaust superheat T01, returning to the initial target exhaust superheat T0; The first target exhaust superheat T01 is lower than the target exhaust superheat T0, and the second target exhaust superheat T02 is lower than the first target exhaust superheat T01.

6. The control method of the jet enthalpy heat pump system according to any one of claims 1 to 5, characterized in that: The step of judging whether a trough appears in the variation curve of the exhaust gas temperature of the compressor (1) comprises: Continuously calculate the difference ΔT between the current exhaust temperature and the exhaust temperature at the previous step time point 排气 ; When the difference ΔT appears 排气 Does not exceed the first preset temperature difference ΔT1 排气 In the case of, the time t for finding the trough starts to count, and the first preset temperature difference ΔT1 排气 is a negative value; During the timing process, if the difference ΔT occurs 排气 Not less than the second preset temperature difference ΔT2 排气 , the second preset temperature difference ΔT2 排气 is a positive value, and the time t for searching for the trough does not exceed the preset maintenance time t 维持 In the case of , it is determined that a trough occurs.

7. The control method of the jet enthalpy heat pump system according to claim 6, characterized in that: When a trough is determined, it also includes: The time for searching for the valley is set to t=0, and the exhaust valley flag f=1.

8. The control method of the jet enthalpy heat pump system according to claim 6, characterized in that: The step of judging whether a trough appears in the variation curve of the exhaust gas temperature of the compressor (1) further comprises: During the timing process, if the difference ΔT occurs 排气 =0, and the time t for searching for the trough does not exceed the preset maintenance time t 维持 In this case, maintain the timing.

9. The control method of the jet enthalpy heat pump system according to claim 6, characterized in that: The step of judging whether a trough appears in the variation curve of the exhaust gas temperature of the compressor (1) further comprises: When the time t for searching for the trough exceeds the preset maintenance time t 维持 In this case, stop timing and make the time t=0 for searching the trough.

10. A control device for a jet enthalpy heat pump system, characterized in that: include: A memory (71) configured to store instructions; The processor (72) is configured to execute the instructions so that the control device executes the control method of the jet enthalpy heat pump system according to any one of claims 1 to 9.

11. A jet enthalpy heat pump system, characterized in that: It comprises the jet enthalpy increase heat pump system control device as described in any one of claims 1 to 9.

12. A non-transitory computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and when the instructions are executed by a processor, the control method of the jet enthalpy heat pump system according to any one of claims 1 to 9 is implemented.

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