A control method for initial opening degree of a fixed-frequency unit and a fixed-frequency heat pump unit

Abstract

The present application relates to a kind of control methods of initial opening degree of fixed frequency unit starting, the control method is by monitoring the backwater temperature of fixed frequency unit, environment temperature, and according to different working mode to calculate initial opening degree, and according to the relationship of backwater temperature and preset backwater temperature threshold, the relationship of environment temperature and preset ring temperature threshold Determine different correction coefficient to correct starting initial opening degree, and then make the initial opening degree of fixed frequency unit starting and the working condition of operating environment match, avoid the phenomenon of high exhaust temperature and high pressure when fixed frequency unit starts using fixed initial opening degree, affect the normal operation of unit Problem, can prolong the service life of unit, improve user experience.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat pump control, in particular to a control method for initial opening degree of fixed-frequency unit start-up and fixed-frequency heat pump unit. BACKGROUND

[0002] The heat pump unit is a kind of high-efficiency and environmentally friendly energy utilization technology, and its core working principle is the reverse Carnot cycle. By consuming a small amount of electric energy or other energy, the heat energy in the low-temperature heat source is transferred to a high-temperature environment to achieve the purpose of heating or refrigeration. As a kind of heat pump unit, the air source heat pump unit absorbs the low-temperature heat energy in the air with very little electric energy, and the heat energy is compressed by the compressor to become high-temperature heat energy, which is then transmitted to the place where heating or refrigeration is needed. It is favored by consumers and users, and has been widely used in hotels, schools, hospitals, saunas, beauty salons, swimming pools, laundry rooms and other places for refrigeration and hot water supply.

[0003] Due to the wide application scenarios of the heat pump unit and the complex and diverse working conditions, there are high requirements for the technical indicators and design schemes of the heat pump unit. For the operating environment of the heat pump unit, it needs to meet the interactive limit working conditions of ambient temperature-35℃ to 45℃ and water temperature 15℃ to 55℃. Especially in the initial stage of start-up operation, the design of the initial opening degree of the electronic expansion valve requires higher requirements. If the initial opening degree is too small, it is easy to trigger high discharge temperature or high pressure problems, and if the initial opening degree is too large, it will cause system oil shortage or liquid return phenomenon.

[0004] At present, the conventional control method of the fixed-frequency unit start-up stage runs at a fixed opening degree set in the start-up stage of the unit, and after stable operation for several minutes, the electronic expansion valve opening degree is adjusted according to the superheat degree of the return gas after the electronic expansion valve is closed at a fixed closing rate to a certain fixed opening degree. This control scheme still has the problems of high discharge temperature and high pressure during start-up in the wide operating range of ambient temperature-35℃ to 45℃, which affects the normal operation of the unit. SUMMARY

[0005] Based on this, the purpose of the present application is to provide a control method for initial opening degree of fixed-frequency unit start-up.

[0006] A control method for initial opening degree of fixed-frequency unit start-up, comprising the following steps:

[0007] Obtaining the working mode, return water temperature T w-in and ambient temperature T E of the unit;

[0008] In the refrigeration mode, the initial opening degree K0 of start-up is calculated by formula (1):

[0009] K0=k C1 *k C2 *(C0-α C *TE +β C *T w-in ) (1);

[0010] In the heating mode, the initial opening K0 of the start-up is calculated via formula (2):

[0011] K0=k H1 *k H2 *(C0-β H *T w-in +α H *T E ) (2);

[0012] The opening of the electronic expansion valve is controlled to be the initial opening K0 of the start-up;

[0013] In formula (1), k C1 represents the first opening correction factor in the refrigeration mode, k C2 represents the second opening correction factor in the refrigeration mode, C0 is a regulation parameter, α C represents the influence factor of the ambient temperature T E in the refrigeration mode, and β C represents the influence factor of the return water temperature T w-in in the refrigeration mode;

[0014] In formula (2), α H represents the influence factor of the ambient temperature T E in the heating mode, β H represents the influence factor of the return water temperature T w-in in the heating mode, k H1 represents the first opening correction factor in the heating mode, and the value is determined according to the relationship between the return water temperature T w-in of the unit and a preset return water temperature threshold, k H2 represents the second opening correction factor in the heating mode, and the value is determined according to the relationship between the ambient temperature T E and a preset ambient temperature threshold.

[0015] Compared with the prior art, the control method for the initial opening of the start-up of the fixed-frequency unit provided in the application calculates the initial opening according to different working modes by monitoring the return water temperature and the ambient temperature of the fixed-frequency unit, and corrects the initial opening of the start-up according to the relationship between the return water temperature and the preset return water temperature threshold and the relationship between the ambient temperature and the preset ambient temperature threshold, so that the initial opening of the start-up of the fixed-frequency unit matches the working condition of the running environment, avoids the high discharge temperature and high pressure phenomenon caused by the fixed initial opening of the start-up of the fixed-frequency unit, and affects the normal operation of the unit, thereby prolonging the service life of the unit and improving the user experience.

[0016] Further, the first opening degree correction factor k H1 is determined by the following method:

[0017] If the unit return water temperature T w-in is less than or equal to a first preset return water temperature threshold k H1 is a set parameter k target ;

[0018] If the unit return water temperature T w-in is less than or equal to a second preset return water temperature threshold and greater than the first preset return water temperature threshold k H1 is a1*k target ;

[0019] If the unit return water temperature T w-in is greater than the second preset return water temperature threshold k H1 is a2*k target ;

[0020] wherein the set parameter k target is determined according to experiments, and has a value range of 0.1-3.0; k target <a1*k target <a2*k target , and a1 and a2 are rate coefficients of the set parameter k target .

[0021] Further, the second opening degree correction factor k H2 is determined by the following method:

[0022] If the ambient temperature T E is less than or equal to a first preset ambient temperature threshold k H2 has a value range of k1-Δk;

[0023] If the ambient temperature T E is less than or equal to a second preset ambient temperature threshold and greater than the first preset ambient temperature threshold k H2 has a value range of k1-k2;

[0024] If the ambient temperature T E is greater than the second preset ambient temperature threshold , then k H2 has a value range of k2+Δk;

[0025] Wherein, k1 represents the first initial opening coefficient, k2 represents the second initial opening coefficient, k1 and k2 are determined according to experiments, and the first initial opening coefficient k1 is less than the second initial opening coefficient k2, and Δk is a set allowable fluctuation value.

[0026] Further, the second opening degree correction factor k H2 When the value range is k1-k2, the specific value is determined by the following formula:

[0027]

[0028] In the formula, k1 represents the first initial opening coefficient, k2 represents the second initial opening coefficient, and C1 is a constant, and the value satisfies when k1=k2. H2

[0029] Meanwhile, the application provides a fixed frequency heat pump unit, 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 in sequence through a refrigerant circulation pipeline, and a controller in communication connection with the electronic expansion valve and the temperature monitoring module, wherein the controller executes the control method of the initial opening degree of the fixed frequency unit described in any one of the above.

[0030] Compared with the prior art, the fixed frequency heat pump unit provided by the application has the same beneficial effects as the control method of the initial opening degree of the fixed frequency unit described above, which will not be repeated here.

[0031] 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

[0032] Figure 1 The structure diagram of the fixed frequency unit of an embodiment of the application;

[0033] Figure 2 The flow chart of the electronic expansion valve control method of an embodiment of the application. DETAILED DESCRIPTION

[0034] The technical solutions of the application will be described in detail below with reference to the accompanying drawings of the embodiments of the application.

[0035] ​In order to solve the problem that the fixed initial opening degree of the existing fixed frequency unit causes the fixed opening degree to be mismatched with the environmental working condition, and further causes the unit to have high discharge temperature and high pressure when starting, thereby affecting the normal operation of the unit, the present application provides a control method for the initial opening degree of the fixed frequency unit when starting. The control method monitors the return water temperature and the environmental temperature of the fixed frequency unit, calculates the initial opening degree according to different working modes, and determines different correction coefficients according to the relationship between the return water temperature and the preset return water temperature threshold value and the relationship between the environmental temperature and the preset environmental temperature threshold value to correct the initial opening degree when starting, so that the initial opening degree of the fixed frequency unit when starting is matched with the working condition of the running environment, the problem of high discharge temperature and high pressure when the fixed frequency unit starts is avoided, and the normal operation of the unit is affected, the service life of the unit is prolonged, and the user experience is improved.

[0036] In specific implementation, please refer to Figure 1 The fixed frequency unit 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 temperature detection module 60, a controller (not shown in the figure), and other auxiliary pipes. The controller is in communication connection with the electronic expansion valve 40 and the temperature detection module 60.

[0037] The temperature detection module 60 comprises a first temperature sensor 61, a second temperature sensor 62 and a third temperature sensor 63. The first temperature sensor 61 is arranged at the return water end of the water-side heat exchanger 30, and is used to collect the return water temperature T w-in and transmit the return water temperature T w-in to the controller. The second temperature sensor 62 is arranged at the outlet end of the water-side heat exchanger 30, and is used to collect the outlet water temperature T w-out and transmit the outlet water temperature T out-w to the controller. The third temperature sensor 63 is used to collect the environmental temperature T E and transmit the environmental temperature T E to the controller. The third temperature sensor 63 can be arranged outside the air-side heat exchanger 30, or can be arranged on the shell of the fixed frequency unit, which is not limited in the present application.

[0038] The controller receives the pressure and temperature signals collected by the pressure detection module 60 and the temperature detection module 60 and the working mode of the unit, calculates the initial opening degree of the electronic expansion valve based on the collected signals, and adjusts the initial opening degree of the electronic expansion valve according to the calculated initial opening degree of the electronic expansion valve.

[0039] Specifically, please refer to Figure 2 The controller controls the initial opening degree of the electronic expansion valve in the following manner.

[0040] S10 obtains the working mode of the unit:

[0041] If the refrigeration mode, step S20 is performed;

[0042] If the heating mode, step S30 is performed.

[0043] S20 obtains return water temperature T w-in and ambient temperature T E , calculates the initial opening degree K0 of the electronic expansion valve:

[0044] K0=k C1 *k C2 *(C0-α C *T E +β C *T w-in )

[0045] Wherein, k C1 represents the first opening correction factor in the refrigeration mode, k C2 represents the second opening correction factor in the refrigeration mode, k C1 , k C2 are all preset parameters, k C1 takes the value range 0.1-3.0, k C2 takes the value range 0.1-3.0; C0 is an adjustment parameter determined according to experiment, which takes the value range 80-400; α C represents the influence factor of ambient temperature T E in the refrigeration mode, which takes the value range 0.1-3.0; β C represents the influence factor of return water temperature T w-in in the refrigeration mode, which takes the value range 0.1-3.0.

[0046] S30 obtains return water temperature T w-in and ambient temperature T E , calculates the initial opening degree K0 of the electronic expansion valve:

[0047] K0=k H1 *k H2 *(C0-β H *T w-in +α H *T E )

[0048] Wherein, C0 is an adjustment parameter determined according to experiment, which takes the value range 80-400; α H represents the influence factor of ambient temperature T E in the heating mode, which takes the value range 0.1-3.0; β represents the influence factor of return water temperature T w-in in the heating mode, which takes the value range 0.1-3.0;

[0049] k H1 represents the first opening degree correction factor in the heating mode, the value of which is determined according to the unit return water temperature T w-in in relation to the preset return water temperature threshold, and the specific determination method is as follows.

[0050] If the unit return water temperature T w-in is less than or equal to the first preset return water temperature threshold that is, k H1 is a set parameter k target , wherein the first preset return water temperature threshold has a value range of 25℃±2℃.

[0051] If the unit return water temperature T w-in is less than or equal to the second preset return water temperature threshold and greater than the first preset return water temperature threshold that is, k H1 is a1*k target , wherein the second preset return water temperature threshold has a value range of 40℃±2℃.

[0052] If the unit return water temperature T w-in is greater than the second preset return water temperature threshold that is, k H1 has a value range of a2*k target .

[0053] The set parameter k target is determined according to experiments, and has a value range of 0.1-3.0; k target <a1*k target <a2*k target , and a1 and a2 are the rate coefficients of the set parameter k target .

[0054] k H2 represents the second opening degree correction factor in the heating mode, the value of which is determined according to the environmental temperature T E in relation to the preset environmental temperature threshold, and the specific determination method is as follows:

[0055] If the environmental temperature T E is less than or equal to the first preset environmental temperature threshold that is, k H2 has a value range of k1-Δk; wherein the first preset environmental temperature threshold The value range is -20℃±2℃; k1 represents a first initial opening coefficient, the value of which is determined according to experiments, and Δk is a set allowable fluctuation value, for example, k1=1 and Δk=0.05.

[0056] If the ambient temperature T E is less than or equal to a second preset ring temperature threshold and greater than a first preset ring temperature threshold That is k H2 The value range is k1-k2.

[0057] Further, k H2 satisfies:

[0058]

[0059] wherein k2 represents a second initial opening coefficient, the value of which is determined according to experiments, for example, k2=2; C1 is a constant, the value of which satisfies that when k H2 =k2.

[0060] The second preset ring temperature threshold has a value range of 20℃±2℃.

[0061] If the ambient temperature T E is greater than the second preset ring temperature threshold That is k H2 The value range is k2+Δk.

[0062] S40 controls the opening degree of the electronic expansion valve to be the initial opening degree K0 when the machine is started.

[0063] 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. In the embodiments of the present application and the claims, the singular forms "a", "an" and "the" are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that "a plurality of" and "several" mean two or more, unless otherwise indicated; "and / or" means any or all possible combinations of one or more associated listed items; "first", "second", "third", etc. are merely used for differentiation, and are not intended to describe a specific order or sequence, nor can they be understood as indicating or implying relative importance. The above description relates to the drawings, and unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. 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 the specific circumstances.

[0064] The above embodiments only express several implementation manners of the present application, and the description is relatively 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, several modifications and improvements can be made without departing from the concept of the present application, and the present application also intends to include these modifications and improvements.

Claims

1. A method for controlling the initial opening degree of a fixed-frequency generator unit during startup, characterized in that, Includes the following steps: Obtain the unit's operating mode and return water temperature T w-in and ambient temperature T E ; In cooling mode, the initial start-up opening degree K0 is calculated using equation (1): K0=k C1 *k C2 *(C0-a C *T E +b C *T w-in ) (1); In heating mode, the initial start-up K0 is calculated using equation (2): K0=k H1 *k H2 *(C0-β H *T w-in +a H *T E ) (2); The opening degree of the electronic expansion valve is controlled to be the initial opening degree K0 at startup; (1) In the formula, k C1 k represents the first opening correction factor in cooling mode. C2 This represents the second opening correction factor in cooling mode, where C0 is the adjustment parameter and α is the value. C Indicates ambient temperature T E Influencing factors in cooling mode, β C Indicates the return water temperature T w-in Influencing factors under cooling mode; (2) In the formula, α H Indicates ambient temperature T E Influencing factors under heating mode, β H Indicates the return water temperature T w-in Influencing factors under heating mode, k H1 This represents the first opening correction factor in heating mode, and its value is based on the unit return water temperature T. w-in The relationship with the preset return water temperature threshold is determined, k H2 This represents the second opening correction factor in heating mode, and its value depends on the ambient temperature T. E The relationship with the preset ambient temperature threshold is determined.

2. The method for controlling the initial opening degree of a fixed-frequency generator unit according to claim 1, characterized in that, The first opening correction factor k in the heating mode H1 Determined by the following method: If the unit return water temperature T w-in Less than or equal to the first preset return water temperature threshold k H1 To set parameter k target ; If the unit return water temperature T w-in Less than or equal to the second preset return water temperature threshold And greater than the first preset return water temperature threshold k H1 For a1*k target ; If the unit return water temperature T w-in Greater than the second preset return water temperature threshold k H1 For a2*k target ; Among them, the parameter k is set. target Based on experiments, its value range is determined to be 0.1–3.0; k target <a1*k target <a2*k target a1 and a2 are the set parameters k target The multiplier.

3. The method for controlling the initial opening degree of a fixed-frequency generator unit according to claim 2, characterized in that, The first preset return water temperature threshold The value range is 25℃±2℃; the second preset return water temperature threshold. The value range is 40℃±2℃.

4. The method for controlling the initial start-up opening degree of a fixed-frequency generator unit according to any one of claims 1 to 3, characterized in that, The second opening correction factor k in the heating mode H2 Determined by the following method: If the ambient temperature T E Less than or equal to the first preset ambient temperature threshold k H2 The value range is k1-Δk; If the ambient temperature T E Less than or equal to the second preset ambient temperature threshold And greater than the first preset ambient temperature threshold k H2 The value range is k1 to k2; If the ambient temperature T E Greater than the second preset ambient temperature threshold Then k H2 The range of values ​​is k² + Δk; Where k1 represents the first initial opening coefficient, k2 represents the second initial opening coefficient, both k1 and k2 are determined by experiments, and the first initial opening coefficient k1 is less than the second initial opening coefficient k2, Δk is the set allowable fluctuation value.

5. The method for controlling the initial opening degree of a fixed-frequency generator unit according to claim 4, characterized in that, The second opening correction factor k in the heating mode H2 When the value range is k1 to k2, the specific value is determined by the following formula: In the formula, k1 represents the first initial opening coefficient, k2 represents the second initial opening coefficient, and C1 is a constant whose value satisfies the following condition: When, make k H2 =k2.

6. The method for controlling the initial opening degree of a fixed-frequency generator unit according to claim 5, characterized in that, The first preset return water temperature threshold The value range is 25℃±2℃; the second preset return water temperature threshold. The value range is 40℃±2℃.

7. The method for controlling the initial opening degree of a fixed-frequency generator unit according to claim 5, characterized in that, The ambient temperature T E Influence factor α under heating mode H The value range is 0.1 to 3.0; the return water temperature T w-in Influence factor β under heating mode H The value range is 0.1 to 3.

0.

8. The method for controlling the initial opening degree of a fixed-frequency generator unit according to any one of claims 1, 2, 3, 5, 6, or 7, characterized in that, The first opening correction factor k in the cooling mode C1 The second opening correction factor k in the cooling mode C2 All are preset parameters, k C1 The value range is 0.1 to 3.0, k C2 The value range is 0.1 to 3.

0.

9. The method for controlling the initial opening degree of a fixed-frequency generator unit according to claim 8, characterized in that, The ambient temperature T E Influence factor α under cooling mode C The value range is 0.1 to 3.0; the return water temperature T w-in Influence factor β under cooling mode C The value range is 0.1 to 3.

0.

10. A fixed-frequency heat pump unit, comprising a compressor, a four-way valve, a water-side heat exchanger, an electronic expansion valve, and an air-side heat exchanger connected sequentially via a refrigerant circulation pipeline, and a temperature monitoring module, and a controller communicatively connected to the electronic expansion valve and the temperature monitoring module, characterized in that, The controller executes the control method for the initial start-up degree of the fixed-frequency generator unit as described in any one of claims 1 to 9.

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