A heat pump system

Abstract

The present application relates to a kind of heat pump systems, by obtaining the real-time return gas superheat when unit actual operation, and calculate the average of current time return gas superheat and last time return gas superheat, and whether the average falls into return gas superheat average allowable value range is judged to use different ways to assign target return gas superheat, and then control heat pump unit according to the target return gas superheat after assignment to control electronic expansion valve. Since the target return gas superheat is obtained from the actual operation process of heat pump system, the method can well adapt to heat pump system working condition change, frequency change, evaporator defrosting and different situations, can avoid the repeated oscillation of each operating parameter, improve user heating experience.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of heat pump, in particular to a heat pump system. BACKGROUND

[0002] At present, the heat pump system usually adopts the control mode of a given target return gas superheat degree to avoid liquid knock of the compressor and improve the energy efficiency of the heat pump system. However, in the actual operation process of the heat pump system, the requirements for the return gas superheat degree are quite different under different conditions such as the operation frequency and the defrosting of the evaporator. Therefore, the control mode of the given target return gas superheat degree cannot match the actual operation condition of the heat pump system. The mismatch of the target return gas superheat degree value will cause the fluctuation of the system operation parameters, affect the heating capacity of the heat pump system, and cause irregular oscillation of the exhaust gas, thereby affecting the heating experience of the user. SUMMARY

[0003] Therefore, the purpose of the present application is to provide a heat pump system, which adopts a target return gas superheat degree control mode that can well adapt to the change of the working condition of the heat pump system, the change of the frequency, the defrosting of the evaporator and other different conditions, and can avoid the repeated oscillation of the operation parameters to improve the heating experience of the user.

[0004] A heat pump system comprises a compressor, a four-way valve, a water-side heat exchanger, an electronic expansion valve, an air-side heat exchanger, a temperature monitoring module, and a controller electrically connected and / or communicatively connected with the compressor, the electronic expansion valve and the temperature monitoring module. The controller controls the electronic expansion valve by the following method:

[0005] S10 obtains the exhaust gas temperature and the condensing temperature at the current time, calculates the exhaust gas superheat degree at the current time according to the exhaust gas temperature and the condensing temperature, and judges whether the exhaust gas superheat degree at the current time is greater than a preset exhaust gas superheat degree threshold value:

[0006] If yes, S20 is executed;

[0007] If no, the target return gas superheat degree stored by the heat pump unit at the last shutdown is used to control the electronic expansion valve;

[0008] S20 obtains the return gas temperature and the evaporation temperature at the current time, calculates the return gas superheat degree at the current time according to the return gas temperature and the evaporation temperature, obtains the return gas superheat degree at the last time, calculates the average value of the return gas superheat degree at the current time according to the return gas superheat degree at the current time and the return gas superheat degree at the last time, and judges whether the average value of the return gas superheat degree at the current time falls within the average value range of the return gas superheat degree:

[0009] If yes, the target return gas superheat degree is equal to the average value of the return gas superheat degree at the current time, and the electronic expansion valve is controlled according to the average value of the return gas superheat degree at the current time;

[0010] If not, the target back gas superheat degree is equal to the preset given target back gas superheat degree, and the electronic expansion valve is controlled according to the given target back gas superheat degree.

[0011] Compared with the prior art, the target back gas superheat degree is valued in different ways by acquiring the real-time back gas superheat degree during actual operation of the unit, calculating the average value of the back gas superheat degree at the current time and the back gas superheat degree at the last time, and judging whether the average value falls within the average value range of the back gas superheat degree, and then controlling the electronic expansion valve according to the valued target back gas superheat degree. Since the target back gas superheat degree is obtained from the actual operation of the heat pump system, the method can well adapt to different situations such as changes in working conditions of the heat pump system, changes in frequency, defrosting of the evaporator, etc., and can avoid repeated oscillation of various operating parameters, thereby improving the user's heating experience.

[0012] Further, the average value of the back gas superheat degree at the current time satisfies:

[0013]

[0014] In the formula, The average value of the back gas superheat degree at the current time is represented by T, and the unit is ℃. The back gas superheat degree at the last time is represented by T-1, and the unit is ℃. The back gas superheat degree at the current time is represented by T, and the unit is ℃. The unit is ℃.

[0015] Further, the average value range of the back gas superheat degree is 1-8 ℃.

[0016] Further, the given target back gas superheat degree Tg is in the range of 1-3 ℃.

[0017] Further, the method further comprises the following steps:

[0018] S30 real-time acquisition of the environment temperature, the compressor frequency change value and the target back gas superheat degree assignment time, and any one of the following conditions is satisfied, i.e., S10-S20 is executed to revalue the target back gas superheat degree:

[0019] If the environment temperature is in the temperature range of-5-5 ℃;

[0020] If the compressor frequency change value exceeds 15 Hz;

[0021] If the target back gas superheat degree assignment time exceeds 60 minutes.

[0022] In order to better understand and implement, the present application is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS ​

[0023] Figure 1 The structural schematic diagram of the present application is shown in the figure.

[0024] Figure 2 The controller control flow schematic diagram of the present application is shown in the figure. DETAILED DESCRIPTION

[0025] The technical solutions of the present application will be described in detail below with reference to the accompanying drawings of the embodiments of the present application.

[0026] The terms used in the embodiments of the present application are merely for the purpose of describing specific embodiments, and are not intended to limit the embodiments of the present application. The singular forms "a", "an" and "the" used in the embodiments of the present application and the appended claims are intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that "multiple" means two or more, unless otherwise stated; "and / or" means any or all possible combinations of one or more associated listed items; "first", "second", "third", etc. are only used to distinguish, and are not used to describe a specific order or sequence, and cannot be understood as indicating or implying relative importance.

[0027] To solve the problem that the control method of heat pump system using a given target return gas superheat degree does not match the actual operating conditions of the heat pump system, causing fluctuations in the operating parameters of the heat pump system, the present application provides a heat pump system that uses an improved target return gas superheat degree control method. This method obtains the real-time return gas superheat degree during the actual operation of the unit and processes it as the target return gas superheat degree to participate in the control of the heat pump system. Since the target return gas superheat degree is obtained from the actual operation of the heat pump system, this method can well adapt to different situations such as changes in heat pump system conditions, frequency changes, and evaporator defrosting, avoiding repeated oscillation of operating parameters and improving user heating experience.

[0028] In specific implementation, please refer to Figure 1 The heat pump system provided by the present application includes a compressor 10, a four-way valve 20, a water-side heat exchanger 30, an electronic expansion valve 40, an air-side heat exchanger 50, a temperature monitoring module 60, a controller (not shown in the figure), and other auxiliary pipes. The compressor 10, the four-way valve 20, the water-side heat exchanger 30, the electronic expansion valve 40, and the air-side heat exchanger 50 are connected through a refrigerant circulation pipeline; the controller is electrically connected and / or communicatively connected with the compressor 10, the electronic expansion valve 40, and the temperature monitoring module 60.

[0029] The temperature monitoring module 60 comprises a first temperature sensor 61, a second temperature sensor 62, a third temperature sensor 63, a fourth temperature sensor 64 and a fifth temperature sensor 65. The first temperature sensor 61 is arranged at the exhaust port of the compressor 10, for collecting the temperature signal of the high-temperature liquid refrigerant compressed by the compressor and transmitting the exhaust temperature signal of the refrigerant to the controller. The second temperature sensor 62 is arranged at the refrigerant inlet end of the water-side heat exchanger 30, for collecting the temperature signal of the high-temperature liquid refrigerant entering the inlet end of the water-side heat exchanger 30 and transmitting the condensation temperature signal to the controller. The third temperature sensor 63 is arranged at the gas return port of the compressor 10, for collecting the temperature signal of the low-temperature gaseous refrigerant entering the gas return port of the compressor 10 and transmitting the gas return temperature signal of the refrigerant to the controller. The fourth temperature sensor 64 is arranged at the refrigerant outlet end of the air-side heat exchanger 50, for collecting the temperature signal of the low-temperature gaseous refrigerant evaporated by the air-side heat exchanger 50 and transmitting the evaporation temperature signal of the refrigerant to the controller. The fifth temperature sensor 65 is used to collect the temperature signal of the environment and transmit the environmental temperature signal to the controller. The fifth temperature sensor 65 can be arranged outside the air-side heat exchanger 50 or on the housing of the heat pump system, which is not limited in the present application.

[0030] The controller further comprises a storage unit and a processing unit.

[0031] The storage unit is used to store various preset values of the heat pump system, including the exhaust superheat threshold value the average value range of the gas return superheat and the given target gas return superheat the exhaust temperature collected by the temperature monitoring module 60 at each time collection point the condensation temperature the gas return temperature and the evaporation temperature and the target gas return superheat obtained at each time collection point

[0032] The processing unit is used to calculate the exhaust superheat ΔT D of the heat pump system according to the exhaust temperature T C and the condensation temperature T D , and compare the exhaust superheat ΔT D with the preset exhaust superheat threshold value for judgment; calculate the gas return superheat ΔT S of the heat pump system according to the gas return temperature T E and the evaporation temperature T S , calculate the average value of the gas return superheat ΔT S from the gas return superheats at different time points and compare the average value of the gas return superheat with the given target gas return superheat compared with a preset average value range of the return gas superheat degree, and an opening degree adjustment signal is output to the electronic expansion valve 40 according to a judgment result, so as to control the operation of the compressor of the heat pump system.

[0033] Please refer to Figure 1 The controller controls the opening degree adjustment of the electronic expansion valve 40 of the heat pump system through the following steps.

[0034] S10 obtains the exhaust temperature at the current time and the condensing temperature According to the exhaust temperature and the condensing temperature The exhaust superheat degree at the current time is calculated Judge whether the exhaust superheat degree at the current time Is greater than the preset exhaust superheat degree threshold

[0035] If the exhaust superheat degree at the current time Is greater than the exhaust superheat degree threshold Then execute S20;

[0036] If the exhaust superheat degree at the current time Is less than or equal to the exhaust superheat degree threshold According to the target return gas superheat degree stored by the heat pump unit at the last shutdown Control the electronic expansion valve.

[0037] Specifically, the time interval between the current time and the previous time is 3-15 seconds, that is, the sampling time interval is 3-15 seconds.

[0038] The exhaust superheat degree at the current time Satisfies:

[0039]

[0040] In the formula, Indicates the exhaust temperature at the current time, unit: ℃; T C t Indicates the condensing temperature at the current time, unit: ℃.

[0041] The exhaust superheat degree threshold Is 14-16 ℃.

[0042] S20 obtains the return gas temperature at the current time and the evaporation temperature According to the return gas temperature and the evaporation temperature The return gas superheat degree at the current time is calculated Get the return gas superheat degree at the last time the current time the last time the average value of the current time judging whether the average value of the current time falls within the allowable range of the average value of the return gas superheat

[0043] if the average value of the current time falls within the allowable range of the average value of the return gas superheat, the target return gas superheat is equal to the average value of the current time the heat pump unit is controlled according to the average value of the current time of the return gas superheat;

[0044] if the average value of the current time does not fall within the allowable range of the average value of the return gas superheat, the target return gas superheat is equal to the preset given target return gas superheat the heat pump unit is controlled according to the given target return gas superheat .

[0045] Specifically, the current time satisfies:

[0046]

[0047] wherein T S t represents the return gas temperature at the current time, in ℃; represents the evaporation temperature at the current time, in ℃.

[0048] the average value of the current time satisfies:

[0049]

[0050] wherein represents the return gas superheat at the last time, in ℃; represents the return gas superheat at the current time , in ℃.

[0051] The return gas superheat at the last time used for calculating the average value of the return gas superheat at the current time for the first time after starting is the target return gas superheat before the last shutdown.

[0052] The allowable range of the average value of the return gas superheat is 1-8 ℃, which can avoid the influence of unreasonable return gas superheat on the reliability of the system.

[0053] The given target return gas superheat The value range is 1℃~3℃. This setting can prevent compressor liquid slugging or low energy efficiency.

[0054] S30 acquires ambient temperature T in real time t Determine the ambient temperature T t Does it fall into the trap of reheating the target? The ambient temperature range to be assigned:

[0055] If the ambient temperature T t If the temperature falls within the ambient temperature range, execute S10-S20 every 30 minutes to re-check the target return gas superheat. Assign a value;

[0056] If the ambient temperature T t If the temperature does not fall within the ambient temperature range, the target return gas superheat will not be recalculated. Perform the assignment.

[0057] The ambient temperature range is -5℃ to 5℃. Frost is easily formed at this temperature, which has a significant impact on the operation of the heat pump system.

[0058] Furthermore, by monitoring the compressor frequency change ΔP or the target return gas superheat assignment time t, it can be determined whether the target return gas superheat needs to be re-adjusted. Perform the assignment.

[0059] S`30 Real-time acquisition of compressor frequency P t Calculate the compressor frequency P at the current moment. t Compared with the compressor frequency P at the previous moment t-1 The change value ΔP t-1～t Determine the frequency change value ΔP of the compressor. t-1～t Is it greater than the preset frequency change threshold ΔP? DV :

[0060] If the compressor frequency change value ΔP t-1～t Greater than the frequency change threshold ΔP DV Then execute S10-S20 to re-apply the target return gas superheat. Assign a value;

[0061] If the compressor frequency change value ΔP t-1～t Less than or equal to the frequency change threshold ΔP DV Then the target superheat will not be re-exposed. Perform the assignment.

[0062] The frequency change threshold ΔP DV The value range is 10Hz to 15Hz.

[0063] S``30 real-time acquisition of target back gas superheat assignment time t, determine whether the target back gas superheat assignment time t exceeds the preset start re-assignment time t MAX :

[0064] If the target back gas superheat assignment time t is greater than the start re-assignment time t MAX , then execute S10-S20, re-assign the target back gas superheat ;

[0065] If the target back gas superheat assignment time t is less than or equal to the start re-assignment time t MAX , then do not re-assign the target back gas superheat .

[0066] The target back gas superheat assignment time t refers to the time from the most recent determination of the target back gas superheat.

[0067] The start re-assignment time t MAX is in the range of 40 minutes to 60 minutes.

[0068] The ambient temperature T t , the compressor frequency change value ΔP t-1～t and the target back gas superheat assignment time t can also be acquired simultaneously, as long as any one of the ambient temperature T t , the compressor frequency P and the target back gas superheat assignment time t meets the requirements of S30, S`30, S``30, the target back gas superheat is re-assigned by executing steps S10-S20, for example:

[0069] S```30 real-time acquisition of the ambient temperature T t , the compressor frequency change value ΔP t-1～t and the target back gas superheat assignment time t, any one of the following is executed S10-S20, re-assigning the target back gas superheat:

[0070] If the ambient temperature is in the temperature range of -5℃ to 5℃;

[0071] If the compressor frequency change value exceeds 15 Hz;

[0072] If the target back gas superheat assignment time exceeds 60 minutes.

[0073] The heat pump system described in the application obtains the real-time return gas superheat when the unit is actually running, calculates the average of the return gas superheat at the current time and the return gas superheat at the last time, judges whether the average falls into the average value range of the return gas superheat, and assigns the target return gas superheat in different ways, and then controls the heat pump unit to control the electronic expansion valve according to the assigned target return gas superheat. Since the target return gas superheat is obtained from the actual operation of the heat pump system, the method can well adapt to different situations such as changes in working conditions, frequency changes, and evaporator defrosting of the heat pump system, and can avoid repeated oscillation of various operating parameters and improve the user's heating experience.

[0074] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, and the present application also intends to include these modifications and improvements.

Claims

1. A heat pump system, comprising a compressor, a four-way valve, a water-side heat exchanger, an electronic expansion valve, an air-side heat exchanger, and a temperature monitoring module connected via a refrigerant circulation pipeline, and a controller electrically and / or communicatively connected to the compressor, the electronic expansion valve, and the temperature monitoring module, characterized in that, The controller controls the electronic expansion valve using the following method: S10 acquires the current exhaust temperature and condensation temperature, calculates the current exhaust superheat based on the exhaust temperature and condensation temperature, and determines whether the current exhaust superheat is greater than a preset exhaust superheat threshold. If yes, then execute S20; If not, the electronic expansion valve will be controlled according to the target return gas superheat stored in the heat pump unit at the time of the last shutdown. S20 acquires the current return gas temperature and evaporation temperature, and calculates the current return gas superheat based on the return gas temperature and evaporation temperature; acquires the previous return gas superheat, and calculates the average return gas superheat based on the current return gas superheat and the previous return gas superheat; determines whether the current average return gas superheat falls within the allowable range of the average return gas superheat. If so, then set the target return gas superheat to be equal to the average return gas superheat at the current moment, and control the electronic expansion valve according to the average return gas superheat at the current moment; If not, then set the target return gas superheat to equal the preset given target return gas superheat, and control the electronic expansion valve according to the given target return gas superheat.

2. The heat pump system according to claim 1, characterized in that, The exhaust superheat threshold is 14℃~16℃.

3. The heat pump system according to claim 1, characterized in that, The current average superheat of the return gas satisfies: In the formula, This represents the average superheat of the return gas at the current moment, in °C. This indicates the superheat of the return gas at the previous moment, in °C. Indicates the current temperature of the return gas superheat. The unit is ℃.

4. The heat pump system according to claim 1, characterized in that, The allowable range for the average value of the return gas superheat is 1℃ to 8℃.

5. The heat pump system according to claim 1, characterized in that, The given target return gas superheat The value range is 1℃~3℃.

6. The heat pump system according to any one of claims 1-5, characterized in that, It also includes the following steps: S30 acquires the ambient temperature in real time and determines whether the ambient temperature falls within the ambient temperature range for which the target return gas superheat has been reassigned: If the ambient temperature falls within the ambient temperature range, execute S10-S20 every 30 minutes to reassign the target return gas superheat value; If the ambient temperature does not fall within the ambient temperature range, the target return gas superheat will not be reassigned. The ambient temperature range is -5℃ to 5℃.

7. The heat pump system according to any one of claims 1-5, characterized in that, It also includes the following steps: S`30 acquires the compressor frequency in real time, calculates the change in compressor frequency between the current moment and the previous moment, and determines whether the change in compressor frequency is greater than a preset frequency change threshold. If so, execute S10-S20 to reassign the target return gas superheat value; If not, the target return gas superheat will not be reassigned; The frequency change threshold ranges from 10Hz to 15Hz.

8. The heat pump system according to any one of claims 1-5, characterized in that, It also includes the following steps: S``30 acquires the target return gas superheat assignment time in real time and determines whether the target return gas superheat assignment time exceeds the preset start-up reassignment time: If so, execute S10-S20 to reassign the target return gas superheat value; If not, the target return gas superheat will not be reassigned; The reassignment time is between 40 and 60 minutes.

9. The heat pump system according to any one of claims 1-5, characterized in that, It also includes the following steps: S```30 acquires the ambient temperature, compressor frequency change value, and target return gas superheat assignment time in real time. If any of the following conditions are met, S10-S20 are executed to reassign the target return gas superheat: If the ambient temperature is within the temperature range of -5℃ to 5℃; If the compressor frequency change exceeds 15Hz; If the target return gas superheat assignment time exceeds 60 minutes.

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