Control method for starting initial opening degree of fixed-frequency unit and fixed-frequency heat pump unit

Abstract

The invention relates to a method for controlling the starting initial opening degree of a fixed-frequency unit, and the method comprises the steps: monitoring the return water temperature and the environment temperature of the fixed-frequency unit, and calculating the initial opening degree according to different working modes; according to the relation between the return water temperature and the preset return water temperature threshold value and the relation between the environment temperature and the preset environment temperature threshold value, different correction coefficients are determined to correct the starting initial opening degree, and then the starting initial opening degree of the fixed frequency unit is matched with the working condition of the operation environment; the problem that normal operation of the unit is affected due to high exhaust temperature and high pressure caused by fixed initial opening when the fixed-frequency unit is started is avoided, the service life of the unit can be prolonged, and the user experience is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of heat pump control, and in particular to a method for controlling the initial opening degree of a fixed-frequency unit and a fixed-frequency heat pump unit. Background Art

[0002] Heat pump unit is an efficient and environmentally friendly energy utilization technology. Its core working principle is the reverse Carnot cycle. It transfers the heat energy in the low-temperature heat source to the high-temperature environment by consuming a small amount of electricity or other energy to achieve the purpose of heating or cooling. As a type of heat pump unit, air source heat pump unit absorbs low-temperature heat energy in the air with very little electricity, converts it into high-temperature heat energy after compression by the compressor, and then transmits it to the place where heating or cooling is required. It is favored by consumers and users and has been widely used in hotels, schools, hospitals, saunas, beauty salons, swimming pools, laundries and other places for refrigeration and hot water supply.

[0003] Due to the wide application scenarios of heat pump units and the complex and diverse working conditions they face, high requirements are placed on the technical indicators and design solutions of heat pump units. For the operating environment of heat pump units, it is necessary to meet the interactive extreme conditions of ambient temperature -35℃~45℃ and water temperature 15℃~55℃, especially in the design of the adjustment of the initial opening of the electronic expansion valve in the initial stage of startup operation. The requirements are higher. If the initial opening is too small, it is easy to trigger high exhaust temperature or high pressure problems. If the initial opening is too large, it will cause oil shortage or liquid return in the system.

[0004] At present, the conventional control method of the fixed frequency unit startup stage is to operate at a set fixed opening during the unit startup stage. After a few minutes of stable operation, the electronic expansion valve opening is closed to a fixed opening at a fixed valve closing rate, and then the electronic expansion valve is adjusted according to the return air superheat. This control scheme still has high exhaust temperature and high pressure at startup under the wide operating range of ambient temperature -35℃~45℃, which affects the normal operation of the unit. Summary of the invention

[0005] Based on this, the object of the present invention is to provide a method for controlling the initial opening degree of a fixed-frequency unit when it is started up.

[0006] A method for controlling the initial opening degree of a fixed-frequency unit when starting up comprises the following steps:

[0007] Get the unit's operating mode and return water temperature T w-in and ambient temperature T E ;

[0008] In cooling mode, the initial opening degree K 0 Calculated by formula (1):

[0009] K 0 =k C1 *k C2 *(C0 -α C *T E +β C *T w-in ) (1);

[0010] In heating mode, the initial K 0 Calculated by formula (2):

[0011] K 0 =k H1 *k H2 *(C 0 -β H *T w-in +α H *T E ) (2);

[0012] Control the opening of the electronic expansion valve to the initial opening K 0 ;

[0013] (1) In the formula, k C1 Indicates the first opening correction factor in cooling mode, k C2 Indicates the second opening correction factor in cooling mode, C 0 is the adjustment parameter, α C Indicates the ambient temperature T E Influencing factor in cooling mode, β C Indicates the return water temperature T w-in Influencing factors in cooling mode;

[0014] (2) In the formula, α H Indicates the ambient temperature T E Influencing factor in heating mode, β H Indicates the return water temperature T w-in Influencing factor in heating mode, k H1 Indicates the first opening correction factor in heating mode, its value is based on the unit return water temperature T w-in Determined by the relationship with the preset return water temperature threshold, k H2 Indicates the second opening correction factor in heating mode, its value is based on the ambient temperature T E The relationship with the preset ambient temperature threshold is determined.

[0015] Compared with the prior art, the control method for the initial opening of the fixed-frequency unit proposed in the present application monitors the return water temperature and ambient temperature of the fixed-frequency unit, calculates the initial opening 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, and the relationship between the ambient temperature and the preset ambient temperature threshold to correct the initial opening of the unit, so as to match the initial opening of the fixed-frequency unit with the working conditions of the operating environment, avoid the problem of high exhaust temperature and high pressure caused by using a fixed initial opening when the fixed-frequency unit is started, and affect the normal operation of the unit, thereby extending the life of the unit and improving the user experience.

[0016] Furthermore, the first opening correction factor k in the heating mode is H1 Determined by the following method:

[0017] 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 the parameter k target ;

[0018] 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 a 1 *k target ;

[0019] If the unit return water temperature T w-in Greater than the second preset return water temperature threshold k H1 for a 2 *k target ;

[0020] Among them, setting parameter k target According to the experimental determination, its value range is 0.1~3.0; k target <a 1 *k target <a 2 *k target , a 1 、a 2 To set the parameter k target The multiplication factor.

[0021] Furthermore, the second opening correction factor k in the heating mode is H2 Determined by the following method:

[0022] 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;

[0023] 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 k 1 ~k 2 ;

[0024] If the ambient temperature T E Greater than the second preset ambient temperature threshold Then k H2 The value range is k 2 +Δk;

[0025] Among them, k 1 Indicates the first initial opening coefficient, k 2 Indicates the second initial opening coefficient, k 1 and k 2 All are determined based on experiments, and the first initial opening coefficient k 1 Less than the second initial opening coefficient k 2 , Δk is the set allowable fluctuation value.

[0026] Furthermore, the second opening correction factor k in the heating mode is H2 The value range is k 1 ~k 2 The specific value is determined by the following formula:

[0027]

[0028] In the formula, k 1 Indicates the first initial opening coefficient, k 2 Indicates the second initial opening coefficient, C 1 is a constant whose value satisfies When k H2 =k 2 .

[0029] At the same time, the present invention provides a fixed-frequency heat pump unit, including 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 communicatively connected to the electronic expansion valve and the temperature monitoring module, and the controller executes the control method for the initial opening of the fixed-frequency unit when it is started up as described in any of the above items.

[0030] Compared with the prior art, the fixed-frequency heat pump unit provided by the present invention has the same beneficial effects as the above-mentioned method for controlling the initial opening degree of the fixed-frequency unit, which will not be described in detail here.

[0031] For better understanding and implementation, the present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a structural schematic diagram of a fixed-frequency unit according to an embodiment of the present invention;

[0033] Figure 2 The figure is a flow chart of an electronic expansion valve control method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0034] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention.

[0035] In order to solve the problem that the fixed opening caused by the adjustment method of the fixed initial opening in the operation of the existing fixed-frequency unit under wide temperature conditions does not match the environmental working conditions, thereby causing the unit to have high exhaust temperature and high pressure when starting up, affecting the normal operation of the unit, the present invention proposes a control method for the initial opening of the fixed-frequency unit when starting up. The control method monitors the return water temperature and ambient temperature of the fixed-frequency unit, calculates the initial opening 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, and the relationship between the ambient temperature and the preset ambient temperature threshold to correct the initial opening of the start-up, thereby matching the initial opening of the fixed-frequency unit with the working conditions of the operating environment, avoiding the problem of high exhaust temperature and high pressure when the fixed-frequency unit is started up using a fixed initial opening, which affects the normal operation of the unit, and can extend the life of the unit and improve the user experience.

[0036] For specific implementation, see Figure 1 The fixed frequency unit proposed by the present invention 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, and a temperature detection module 60, and a controller (not shown), and other auxiliary pipes connected through a refrigerant pipeline. The controller is in communication connection with the electronic expansion valve 40 and the temperature detection module 60.

[0037] The temperature detection module 60 includes a first temperature sensor 61, a second temperature sensor 62 and a third temperature sensor 63. The first temperature sensor 61 is disposed 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 the return water temperature T w-in The second temperature sensor 62 is arranged at the outlet of the water side heat exchanger 30, and is used to collect the outlet water temperature T w-out , and the outlet water temperature T out-w The third temperature sensor 63 is used to collect the ambient temperature T E , and the ambient temperature T EThe third temperature sensor 63 can be arranged on the outside of the air-side heat exchanger 30 or on the casing 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 of the electronic expansion valve based on the collected signals, and adjusts the initial opening of the electronic expansion valve according to the calculated initial opening of the electronic expansion valve.

[0039] For details, please refer to Figure 2 The controller controls the initial opening of the electronic expansion valve in the following way.

[0040] S10 obtains the unit's operating mode:

[0041] If it is cooling mode, execute step S20;

[0042] If it is heating mode, execute step S30.

[0043] S20 obtains the return water temperature T of the unit w-in and ambient temperature T E , calculate the initial opening degree K of the electronic expansion valve 0 :

[0044] K 0 =k C1 *k C2 *(C 0 -α C *T E +β C *T w-in )

[0045] Among them, k C1 Indicates the first opening correction factor in cooling mode, k C2 Indicates the second opening correction factor in cooling mode, k C1 , k C2 All are preset parameters, k C1 The value range is 0.1~3.0, k C2 The value range is 0.1~3.0; C 0 is the adjustment parameter determined by experiment, and its value range is 80~400; α C Indicates the ambient temperature T E The influence factor in cooling mode ranges from 0.1 to 3.0; β C Indicates the return water temperature T w-in The influence factor in cooling mode ranges from 0.1 to 3.0.

[0046] S30 obtains the return water temperature T of the unit w-inand ambient temperature T E , calculate the initial opening degree K of the electronic expansion valve 0 :

[0047] K 0 =k H1 *k H2 *(C 0 -β H *T w-in +α H *T E )

[0048] Among them, C 0 is the adjustment parameter determined by experiment, and its value range is 80~400; α H Indicates the ambient temperature T E Influencing factor in heating mode, the value range is 0.1~3.0; β represents the return water temperature T w-in The influence factor in heating mode ranges from 0.1 to 3.0;

[0049] k H1 Indicates the first opening correction factor in heating mode, its value is based on the unit return water temperature T w-in The relationship between the return water temperature and the preset return water temperature threshold is determined by the following method.

[0050] If the unit return water temperature T w-in Less than or equal to the first preset return water temperature threshold Right now k H1 To set the parameter k target , wherein the first preset return water temperature threshold The value range is 25℃±2℃.

[0051] 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 Right now k H1 for a 1 *k target , where the second preset return water temperature threshold The value range is 40℃±2℃.

[0052] If the unit return water temperature T w-in Greater than the second preset return water temperature threshold Right now k H1 Value range a 2 *k target .

[0053] The setting parameter ktarget According to the experimental determination, its value range is 0.1~3.0; k target <a 1 *k target <a 2 *k target , a 1 、a 2 To set the parameter k target The multiplication factor.

[0054] k H2 Indicates the second opening correction factor in heating mode, its value is based on the ambient temperature T E The relationship with the preset ambient temperature threshold is determined, and the specific determination method is as follows:

[0055] If the ambient temperature T E Less than or equal to the first preset ambient temperature threshold Right now k H2 The value range is k 1 -Δk; wherein the first preset ambient temperature threshold Value range: -20℃±2℃; k 1 represents the first initial opening coefficient, whose value is determined according to experiments, and Δk is the set allowable fluctuation value, for example, k 1 =1, Δk=0.05.

[0056] 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 Right now k H2 The value range is k 1 ~k 2 .

[0057] Furthermore, k H2 satisfy:

[0058]

[0059] Among them, k 2 represents the second initial opening coefficient, whose value is determined according to experiments, for example, k 2 =2; C 1 is a constant whose value satisfies When k H2 =k 2 .

[0060] Among them, the second preset ambient temperature threshold The value range is 20℃±2℃.

[0061] If the ambient temperature TE Greater than the second preset ambient temperature threshold Right now Then k H2 The value range is k 2 +Δk.

[0062] S40 controls the opening of the electronic expansion valve to the initial opening K 0 .

[0063] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the embodiments of the present application. The singular forms of "a", "said" and "the" used in the embodiments of the present application and the claims are also intended to include plural forms, unless the context clearly indicates other meanings. It should also be understood that, unless otherwise specified, "multiple" and "several" refer to two or more; "and / or" refers to and includes any or all possible combinations of one or more associated listed items; "first", "second", "third", etc. are only used to distinguish, rather than to describe a specific order or sequence, and cannot be understood as indicating or implying relative importance. When the above description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. In the description of the present application, for those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0064] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, and the present invention is also intended to include these modifications and modifications.

Claims

1. A method for controlling the initial opening degree of a fixed-frequency unit, characterized in that: The following steps are involved: Get the unit's operating mode and return water temperature T w-in and ambient temperature T E ; In cooling mode, the initial opening degree K0 is calculated by formula (1): K0=k C1 *k C2 *(C0-a C *T E +b C *T w-in ) (1); In heating mode, the initial K0 is calculated by formula (2): K0=k H1 *k H2 *(C0-β H *T w-in +a H *T E ) (2); Control the opening of the electronic expansion valve to the initial opening K0 at startup; (1) In the formula, k C1 Indicates the first opening correction factor in cooling mode, k C2 Indicates the second opening correction factor in cooling mode, C0 is the adjustment parameter, α C Indicates the ambient temperature T E Influencing factor in cooling mode, β C Indicates the return water temperature T w-in Influencing factors in cooling mode; (2) In the formula, α H Indicates the ambient temperature T E Influencing factor in heating mode, β H Indicates the return water temperature T w-in Influencing factor in heating mode, k H1 Indicates the first opening correction factor in heating mode, its value is based on the unit return water temperature T w-in Determined by the relationship with the preset return water temperature threshold, k H2 Indicates the second opening correction factor in heating mode, its value is based 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 unit when starting up according to claim 1 is 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 the 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 a1*k target ; If the unit return water temperature T w-in Greater than the second preset return water temperature threshold k H1 is a2*k target ; Among them, setting parameter k target According to the experimental determination, its value range is 0.1~3.0; k target <a1*k target <a2*k target , a1, a2 are setting parameters k target The multiplication factor.

3. The method for controlling the initial opening degree of a fixed-frequency unit when starting up according to claim 2 is 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 opening degree of a fixed-frequency unit when it is started 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~k2; If the ambient temperature T E Greater than the second preset ambient temperature threshold Then k H2 The value range is k2+Δk; Wherein, k1 represents the first initial opening coefficient, k2 represents the second initial opening coefficient, k1 and k2 are both determined according to experiments, and the first initial opening coefficient k1 is smaller than the second initial opening coefficient k2, and Δk is the set allowable fluctuation value.

5. The method for controlling the initial opening degree of a fixed-frequency unit when starting up according to claim 4 is 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 When k H2 =k2.

6. The method for controlling the initial opening degree of a fixed-frequency unit when starting up according to claim 5 is 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 unit when starting up according to claim 5, characterized in that: The ambient temperature T E Influence factor α in heating mode H The value range of the return water temperature T w-in Influencing factor β in heating mode H The value range is 0.1~3.

0.

8. The method for controlling the initial opening degree of a fixed-frequency unit when it is started according to claim 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 0.1~3.0, k C2 The value range is 0.1 to 3.

0.

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

0.

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

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