Fan control method based on compression ratio and air energy heat pump

Abstract

The application relates to a fan control method based on a compression ratio and an air energy heat pump. The fan control method comprises the following steps: controlling a fan to operate at a basic rotating speed, and calculating a current time compression ratio; acquiring a reference compression ratio of a compressor, calculating a fan target rotating speed according to the current time compression ratio and the reference compression ratio, and controlling the fan to operate according to the target rotating speed. The control method can control the fan rotating speed through a PID adjustment mode based on the change rate of the compression ratio and the reference compression ratio when the heat pump is in a partial load or low load working condition, can more accurately match the refrigeration or heating demand of the heat pump, can match the rotating speed of the fan with the actual required evaporation capacity, can control the energy consumption of the fan on the basis of improving the evaporation capacity of the evaporator, and can make the energy efficiency ratio of the system reach better optimization.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of control of heat pumps, and in particular to a fan control method based on compression ratio and an air-source heat pump. BACKGROUND

[0002] As a new type of energy-saving and environment-friendly equipment, the air-source heat pump has a high energy efficiency ratio. During operation, it only consumes electric energy and does not produce common air pollutants such as ozone, carbon monoxide, and sulfur dioxide. It is widely used in refrigeration and heating scenarios and has a good market prospect. The main components of the air-source heat pump include a compressor, a finned heat exchanger, a double-pipe heat exchanger, a fan, a water pump, etc. The heat exchange capacity of the finned heat exchanger is related to the fan speed during heat exchange. When the air-source heat pump is in a partial load or low load working condition, as the fan speed increases, the heat exchange capacity of the finned heat exchanger also increases to a certain extent. However, increasing the fan speed to improve the heat exchange capacity of the finned heat exchanger has the risk of reducing the overall energy efficiency, because when the fan speed is increased, the energy consumption of the fan also increases. Therefore, a method for controlling the fan speed is needed to improve the heat exchange capacity of the finned heat exchanger while considering the energy consumption of the fan, so as to achieve the best energy efficiency of the air-source heat pump.

[0003] The existing air-source heat pump mainly uses temperature control method and pressure control method to control the fan speed under low load or partial load working condition.

[0004] The temperature control method directly controls the fan speed by detecting the temperature. It is simple and easy to implement, but it has the following disadvantages: on the one hand, it cannot directly reflect the state of the refrigerant, and in the case of no gas or insufficient gas capacity, it may cause liquid damage to the compressor; on the other hand, in the case of poor sensor insulation or large refrigerant flow variation, the temperature measurement value has large deviation and cannot directly reflect the operating state of the heat pump; on the other hand, the temperature sensor has a long response time, which may cause control lag and affect the stability of the heat pump; on the other hand, when the temperature frequently changes, the fan needs to be frequently adjusted, which may cause the overall energy efficiency to decrease.

[0005] The pressure control method controls the fan speed by detecting the pressure change, which can reflect the state of the refrigerant. However, it has the following disadvantages: it is greatly affected by environmental temperature fluctuations and refrigerant flow variations, which may cause the pressure to change too quickly, resulting in frequent adjustment of the fan, decreased energy efficiency of the heat pump, increased equipment noise and vibration, and affected equipment life. SUMMARY

[0006] Therefore, the purpose of the present application is to provide a fan control method based on compression ratio and an air-source heat pump.

[0007] A fan control method based on compression ratio, comprising:

[0008] S10 the compressor is started to run for a period of time t, and the fan is controlled to run at a basic speed N BASE running; and obtaining the current high pressure of the compressor the current low pressure calculating the current compression ratio R t ;

[0009] S20 obtaining the reference compression ratio R BASE of the compressor, and calculating the target speed N of the fan according to the current compression ratio R t and the reference compression ratio R BASE , the target speed N of the fan satisfies:

[0010]

[0011] In the formula, N represents the target speed of the fan, unit: r / min, N BASE represents the basic speed of the fan, unit: r / min, R t represents the current compression ratio, R BASE represents the reference compression ratio, K P represents the proportional adjustment coefficient, K I represents the integral adjustment coefficient, and t represents time, unit: min.

[0012] S30 controlling the fan to run according to the target speed N.

[0013] Compared with the prior art, the fan control method based on the compression ratio of the application can more sensitively reflect the dynamic change of the heat pump through the change rate of the compression ratio and the reference compression ratio, quickly respond to the change of the heat pump load, help to timely adjust the fan speed, quickly restore the balance of the heat pump, and reduce fluctuations and unstable factors; under the condition that the heat pump is in partial load or low load, the PID adjustment mode based on the change rate of the compression ratio and the reference compression ratio is used to control the fan speed, which can more accurately match the refrigeration or heating demand of the heat pump, match the speed of the fan with the actual required evaporation capacity, control the energy consumption of the fan on the basis of improving the evaporation capacity of the evaporator, and make the energy efficiency ratio of the system better optimized.

[0014] Further, the current compression ratio R t satisfies:

[0015]

[0016] In the formula, represents the current high pressure of the compressor, represents the current low pressure of the compressor.

[0017] Further, the current compression ratio Rt satisfies:

[0018]

[0019] wherein: represents the current high pressure of the compressor, represents the current low pressure of the compressor, and γ represents the specific heat ratio of the refrigerant.

[0020] Further, the reference compression ratio R BASE satisfies:

[0021]

[0022] wherein P c,design represents the design condensing pressure of the water-side heat exchanger; P e,design represents the design evaporating pressure of the air-side heat exchanger.

[0023] Further, the design evaporating pressure P e,design of the air-side heat exchanger and the design condensing pressure P c,design of the water-side heat exchanger are determined by the following method:

[0024] SA1 obtains the outdoor ambient temperature and the indoor target temperature of the air energy heat pump under a rated cooling mode condition. and the indoor target temperature of the air energy heat pump under a rated heating mode condition. e , and the temperature difference ΔT c of the water-side heat exchanger;

[0025] SA2A calculates the design cooling evaporating temperature according to the outdoor ambient temperature of the air energy heat pump under the rated cooling mode condition. and the temperature difference ΔT e of the air-side heat exchanger, to obtain the design heating evaporating temperature

[0026] SA2B calculates the design cooling condensing temperature according to the indoor target temperature of the air energy heat pump under the rated cooling mode condition. and the temperature difference ΔT c of the water-side heat exchanger, to obtain the design heating condensing temperature

[0027] SA3 calculates the design cooling evaporating temperature and the design heating evaporating temperature finds out the corresponding design evaporation pressure P e,design ; according to the design refrigeration condensing temperature and the design heating condensing temperature finds out the corresponding design condensing pressure P e,design .

[0028] Further, the design heating evaporation temperature satisfies:

[0029]

[0030] In the formula, indicates the indoor target temperature, ΔT e indicates the temperature difference of the air heat exchanger 25s~35s.

[0031] Further, the design heating condensing temperature satisfies:

[0032]

[0033] In the formula, indicates the outdoor environment temperature, ΔT c indicates the temperature difference of the water side heat exchanger.

[0034] Meanwhile, the application provides an air energy heat pump, comprising a compressor, a four-way valve, a water side heat exchanger, an electronic expansion valve, an air side heat exchanger, a fan arranged at one side of the air side heat exchanger, a pressure detection module, and a controller in communication connection with the compressor, the fan, and the pressure detection module, wherein the controller controls the rotating speed of the fan through any one of the above fan control methods based on the compression ratio.

[0035] Compared with the prior art, the air energy heat pump of the application has the same beneficial effects as the above-mentioned fan control method based on the compression ratio, which will not be repeated here.

[0036] In order to better understand and implement, the application will be described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is a structural schematic diagram of an embodiment of the application;

[0038] Figure 2 is a schematic diagram of the air flow direction of the air side heat exchanger of an embodiment of the application;

[0039] Figure 3 is a flow chart of the fan control method of an embodiment of the application. DETAILED DESCRIPTION

[0040] The technical solutions of the present application will be described clearly and completely below with reference to the accompanying drawings of the embodiments of the present application.

[0041] The compression ratio is the ratio of the outlet pressure and the inlet pressure of the compressor, and its size determines the degree of change in the volume of gas passing through the compressor per unit time. A high compression ratio means higher heat pump efficiency and working pressure, but also accompanied by higher energy consumption. How to seek a suitable compression ratio and use the compression ratio to adjust the fan speed so that the air energy heat pump is in high energy efficiency is an effective method to solve the problem of energy efficiency decline caused by increasing the fan speed to improve the heat exchange capacity of the finned heat exchanger. Therefore, the present application is designed after research, and an air energy heat pump is provided. The air energy heat pump comprises a fan control method based on the compression ratio, which controls the fan speed based on the PID adjustment mode of the change rate of the compression ratio and the reference compression ratio, can more accurately match the refrigeration or heating demand of the heat pump, match the speed of the fan with the actual required evaporation capacity, control the energy consumption of the fan on the basis of improving the evaporation capacity of the evaporator, and make the energy efficiency ratio of the system better optimized.

[0042] In specific implementation, please refer to Figure 1 The air energy heat pump provided by the present application comprises 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 fan 60 arranged on one side of the air-side heat exchanger 50, a pressure detection module 70 for monitoring the high pressure of the exhaust gas of the compressor 10 and the low pressure of the suction gas, and a controller in communication connection with the compressor 10, the fan 60 and the pressure detection module 70.

[0043] The compressor 10 comprises an exhaust port A and a gas return port B. The pressure detection module 70 comprises a first pressure gauge 71 and a second pressure gauge 72. The first pressure gauge 71 is arranged at the exhaust port A of the compressor 10 and is used for detecting the high pressure of the exhaust gas of the compressor The second pressure gauge 72 is arranged at the gas return port B of the compressor 10 and is used for detecting the low pressure of the suction gas of the compressor

[0044] The controller comprises a storage unit and a processing unit. The storage unit is used for receiving the pressure signals collected by the pressure detection module 70 and the preset reference compression ratio. The processing unit is used for calculating the compression ratio and the fan speed according to the collected signals, and controlling the rotation of the fan according to the calculated fan speed.

[0045] Please refer to Figure 2 Meanwhile, the controller controls the speed of the fan in the following manner. Specifically, the following steps are included.

[0046] S10 After the compressor is started and operated for a time period t, the fan is controlled to rotate at a basic speed NBASE running; and obtaining current high pressure of the compressor current low pressure calculating current compression ratio R t .

[0047] The time period t is set to 3-5 minutes.

[0048] The current compression ratio R t satisfies:

[0049]

[0050] In the formula, represents the current high pressure of the compressor, represents the current low pressure of the compressor.

[0051] In another embodiment, the current compression ratio R t satisfies:

[0052]

[0053] In the formula: represents the current high pressure of the compressor, represents the current low pressure of the compressor, and γ represents the specific heat ratio of the refrigerant.

[0054] S20 obtains a reference compression ratio R BASE of the compressor, calculates a fan target speed N according to the current compression ratio R t and the reference compression ratio R BASE .

[0055] The fan target speed N satisfies:

[0056]

[0057] In the formula, N represents the fan target speed, unit r / min, N BASE represents the fan base speed, unit r / min, R t represents the current compression ratio, R BASE represents the reference compression ratio, K P represents the proportional adjustment coefficient, K I represents the integral adjustment coefficient, and t represents time, unit min. Among them, K P and K I are obtained by experiment and calculation according to different units.

[0058] In the calculation of the above fan target speed, the proportional adjustment coefficient K P is a main adjustment part of the target fan speed as a coarse adjustment part; the integral adjustment coefficient KI As a fine-tuning part, it aims to eliminate steady-state error.

[0059] The reference compression ratio R of the compressor BASE It is calculated by the following method:

[0060]

[0061] In the formula, P c,design Indicates the design condensing pressure of the water side heat exchanger; P e,design Indicates the design evaporation pressure of the air side heat exchanger.

[0062] Wherein, the design evaporation pressure P e,design of the air side heat exchanger and the design condensing pressure P c,design of the water side heat exchanger are determined by the following method.

[0063] SA1 obtains the outdoor environment temperature under the rated cooling working condition of the air energy heat pump And the indoor target temperature The outdoor environment temperature under the rated heating mode working condition And the indoor target temperature And the temperature difference ΔT e of the air side heat exchanger and the temperature difference ΔT c of the water side heat exchanger.

[0064] SA2A calculates the design refrigeration evaporation temperature According to the outdoor environment temperature under the rated cooling working condition According to the indoor target temperature under the rated heating working condition And the temperature difference ΔT e of the air side heat exchanger, the design heating evaporation temperature

[0065] Specifically, the outdoor environment temperature under the rated cooling working condition As the design refrigeration evaporation temperature For example, the outdoor environment temperature under the rated cooling working condition Is 35℃, and the design refrigeration evaporation temperature Is 35℃.

[0066] The design heating evaporation temperature Satisfies:

[0067]

[0068] In the formula, Indicates the indoor target temperature, ΔT e Indicates the temperature difference of the air heat exchanger.

[0069] The temperature difference ΔT of the air-side heat exchanger e The value range is 5℃~10℃.

[0070] SA2B is based on the indoor target temperature under the rated cooling conditions. The design refrigeration condensing temperature was calculated. Based on the outdoor ambient temperature under the rated thermal conditions Temperature difference ΔT between water and heat exchanger c The design heating condensing temperature was calculated.

[0071] In practice, the target indoor temperature under rated cooling conditions will be... As the design refrigeration evaporation temperature

[0072] The designed heating and condensation temperature satisfy:

[0073]

[0074] In the formula, ΔT represents the outdoor ambient temperature. c This indicates the temperature difference in the water-side heat exchanger.

[0075] The temperature difference ΔT of the water-side heat exchanger e The value range is 5℃~10℃.

[0076] SA3 is designed for refrigeration and evaporation temperatures. and the designed heating and evaporation temperature Find the corresponding design evaporation pressure P e,design According to the design refrigeration condensing temperature and design heating and condensing temperature Find the corresponding design condensation pressure P e,design .

[0077] In practice, refrigerant characteristic tables or refrigerant calculation software, such as Ref Tools, can be used to design the evaporation pressure P. e,design and design condensation pressure P e,design The search.

[0078] S30 controls the fan to run at the target speed N.

[0079] The compression ratio-based fan control method of the present invention has the following beneficial technical effects.

[0080] 1) The compression ratio can more directly and comprehensively reflect the working status of the compressor and the overall load of the heat pump;

[0081] 2) Through the change rate of the compression ratio and the reference compression ratio, the dynamic change of the heat pump can be more sensitively reflected, the change of the heat pump load can be quickly responded, the fan speed can be adjusted in time, the balance of the heat pump can be quickly restored, and the fluctuation and instability factors can be reduced;

[0082] 3) In the heat pump under the part load or low load working condition, through the PID adjustment mode based on the change rate of the compression ratio and the reference compression ratio, the fan speed can be controlled, the refrigeration or heating demand of the heat pump can be more accurately matched, the speed of the fan can be matched with the actual required evaporation capacity, the energy consumption of the fan can be controlled on the basis of improving the evaporation capacity of the evaporator, and the energy efficiency ratio of the system can be better optimized.

[0083] 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 claims are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that "multiple" and "several" refer to 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 for distinction, and are not used to describe a specific order or sequence, and cannot be understood as indicating or implying relative importance. When the above description refers to the drawings, the same numbers in different drawings represent the same or similar elements, unless otherwise indicated. In the description of the present application, the specific meanings of the above terms in the present application can be understood by those skilled in the art according to specific circumstances.

[0084] The above embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as limiting the scope of the patent. It should be pointed out that for those skilled in the art, without departing from the concept of the present application, some modifications and improvements can be made, and the present application also intends to include these modifications and improvements.

Claims

1. A method of controlling a fan based on a compression ratio, the method comprising: Comprising: S10 the compressor is started and runs for a period of time t, and the fan is controlled to run at a basic speed N BASE Running; and acquire the current time high pressure of the compressor current time low pressure calculate the current time compression ratio R t ; S20 obtaining a reference compression ratio R of the compressor BASE , calculating a fan target rotation speed N according to the current time compression ratio R t and the reference compression ratio R BASE , the fan target rotation speed N satisfying: In the formula, N represents the target rotating speed of the fan, unit: r / min, N BASE R represents the basic rotating speed of the fan, unit: r / min, R t R represents the current compression ratio, unit: r / min, R BASE K represents the reference compression ratio, unit: r / min, K P K represents the proportional regulation coefficient, unit: r / min, K I K represents the integral regulation coefficient, t represents time, unit: min; S30 controls the fan to run according to the target rotating speed N.

2. The compression ratio-based blower control method of claim 1, wherein, The current time compression ratio R t satisfies: In the formula, represents the current time high pressure of the compressor, represents the current time low pressure of the compressor.

3. The compression ratio based blower control method of claim 1, wherein, The current time compression ratio R t satisfies: In the formulae: represents the current time high pressure of the compressor, represents the current time low pressure of the compressor, and γ represents the specific heat ratio of the refrigerant.

4. The compression ratio based blower control method according to any one of claims 1 to 3, characterized by, the reference compression ratio R of the compressor BASE satisfies: where P c,design represents the design condensing pressure of the water side heat exchanger; P e,design represents the design evaporating pressure of the air side heat exchanger.

5. The compression ratio based blower control method of claim 4, wherein, The design evaporation pressure P of the air side heat exchanger e,design and the design condensation pressure P of the water side heat exchanger c,design is determined by the method: SA1 the outdoor ambient temperature at the rated cooling operating condition of the air-to-air heat pump and the indoor target temperature the outdoor ambient temperature at the rated heating operating condition and the indoor target temperature and the temperature difference ΔT of the air-side heat exchanger e and the temperature difference ΔT of the water-side heat exchanger c ; SA2A calculates the design cooling evaporating temperature according to the outdoor ambient temperature under the rated cooling operating condition calculates the design cooling evaporating temperature calculates the design heating evaporating temperature according to the indoor target temperature under the rated heating operating condition and the temperature difference ΔT of the air side heat exchanger e calculates the design heating evaporating temperature SA2B calculates the indoor target temperature according to the rated cooling operating condition The design refrigeration condensing temperature is calculated According to the outdoor ambient temperature under the rated heating operating condition And the temperature difference ΔT of the water side heat exchanger c The design heating condensing temperature is calculated SA3 according to the design cooling evaporation temperature and the design heating evaporation temperature finds the corresponding design evaporation pressure P e,design ; according to the design cooling condensation temperature and the design heating condensation temperature finds the corresponding design condensation pressure P e,design .

6. The compression ratio-based blower control method of claim 5, wherein, Design heating evaporation temperature satisfies: wherein represents the indoor target temperature, ΔT e represents the temperature difference of the air heat exchanger.

7. The compression ratio-based blower control method according to claim 5 or 6, characterized by, Design heating condensing temperature satisfies: In the formula, represents the outdoor ambient temperature, ΔT c represents the temperature difference of the water side heat exchanger.

8. The compression ratio-based blower control method of claim 7, wherein, The temperature difference ΔT of the air side heat exchanger e The temperature difference ΔT of the water side heat exchanger e The temperature difference ΔT of the water side heat exchanger 9. The compression ratio based blower control method of claim 1, wherein, The time period t ranges from 3 min to 5 min.

10. An air-to-air heat pump, characterized in that Comprise a compressor, a four-way valve, a water-side heat exchanger, an electronic expansion valve, an air-side heat exchanger, a fan arranged on one side of the air-side heat exchanger, a pressure detection module, and a controller in communication connection with the compressor, the fan, and the pressure detection module, wherein the controller controls the rotating speed of the fan by the fan control method based on the compression ratio according to any one of claims 1-9.

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