A novel electronic expansion valve control method for falling film water source heat pump unit

Abstract

The present invention relates to the technical field of water source heat pump units, and specifically discloses a novel electronic expansion valve control method for a falling film water source heat pump unit, including: obtaining the current current of the compressor, the current exhaust temperature of the compressor, the current condensing pressure of the condenser, the current evaporating pressure of the evaporator, the current outlet water temperature and the current inlet water temperature; calculating the first target opening of the electronic expansion valve and the second target opening of the electronic expansion valve; controlling the unit to stop running or output the first target opening of the electronic expansion valve according to the comparison result between the first target opening and the second target opening; after outputting the first target opening, calculating the third target opening of the electronic expansion valve; adjusting the current opening of the electronic expansion valve to the first target opening or to the third target opening according to the comparison result between the first target opening and the third target opening. The present invention can ensure the safety, stability and reliability of the operation of the entire water source heat pump unit.

Description

Technical Field

[0001] The invention relates to the technical field of water source heat pump units, and in particular to an electronic expansion valve control method for a novel falling film water source heat pump unit. Background Art

[0002] In order to reduce the loss of the compressor and protect the compressor, the current design of the heat pump unit often ensures that the compressor suction superheat is at least 2 to 5°C. Therefore, whether it is equipped with a thermal expansion valve or an electronic expansion valve, the unit can control the liquid level through the suction superheat.

[0003] The compressor suction superheat of a fully liquid or falling film chiller / heat pump unit is generally very small or even zero. If traditional suction superheat control or exhaust superheat is used as a feedback signal for liquid supply control, although the cost is low, the temperature transfer has a certain lag, so the control accuracy and stability are difficult to guarantee; and the condenser side and evaporator side liquid level method, although it can guarantee control accuracy and stability to a certain extent, is limited by cost and will hardly have much room for development in the future; and the method that relies on monitoring the exhaust superheat control is also subject to the lag of temperature transfer, and is greatly affected by the fluctuations of the compressor compression ratio and the unit load, and therefore cannot effectively control the electronic expansion valve.

[0004] If a new type of electronic expansion valve control method for falling film water source heat pump units is developed, it will not only be able to control and adjust the operating status of the unit more reasonably and effectively, but also save the investment and manufacturing costs of the unit, which will produce huge social and economic benefits. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a novel electronic expansion valve control method for a falling film water source heat pump unit to solve the problem that the electronic expansion valve control of the existing falling film water source heat pump unit is unreasonable and has low precision.

[0006] As a first aspect of the present invention, a method for controlling an electronic expansion valve of a novel falling film water source heat pump unit is provided, wherein the novel falling film water source heat pump unit comprises a compressor, a current transformer, an exhaust temperature sensor, a condenser, a high pressure pressure sensor, an electronic expansion valve, a low pressure pressure sensor, a falling film evaporator, a water outlet temperature sensor and a water inlet temperature sensor, wherein the compressor provides power for refrigerant circulation, and water and refrigerant perform heat exchange in the condenser or the falling film evaporator; the current transformer is used to detect the current current of the compressor; the exhaust temperature sensor is used to detect the current exhaust temperature of the compressor; the high pressure sensor is used to detect the current condensing pressure of the condenser; the low pressure sensor is used to detect the current evaporation pressure of the falling film evaporator; the water outlet temperature sensor is used to detect the current water outlet temperature; the water inlet temperature sensor is used to detect the current water inlet temperature; wherein the method for controlling an electronic expansion valve of the novel falling film water source heat pump unit comprises:

[0007] Step S1: obtaining the current current of the compressor, the current exhaust temperature of the compressor, the current condensing pressure of the condenser, the current evaporating pressure of the falling film evaporator, the current outlet water temperature and the current inlet water temperature;

[0008] Step S2: calculating the current cooling capacity of the novel falling film water source heat pump unit according to the current current of the compressor and the preset full load current;

[0009] Step S3: calculating the first target opening of the electronic expansion valve according to the current cooling capacity of the novel falling film water source heat pump unit, the current water outlet temperature and the current water inlet temperature, and calculating the second target opening of the electronic expansion valve according to the current cooling capacity of the novel falling film water source heat pump unit, the current condensing pressure of the condenser and the current evaporating pressure of the falling film evaporator;

[0010] Step S4: comparing the first target opening of the electronic expansion valve with the second target opening of the electronic expansion valve, and controlling the novel falling film water source heat pump unit to stop running or executing step S5 according to the comparison result between the first target opening and the second target opening;

[0011] Step S5: outputting the first target opening of the electronic expansion valve, and then calculating the third target opening of the electronic expansion valve according to the current exhaust temperature of the compressor and the current condensing pressure of the condenser;

[0012] Step S6: Compare the first target opening of the electronic expansion valve with the third target opening of the electronic expansion valve, and adjust the current opening of the electronic expansion valve to the first target opening or adjust the current opening of the electronic expansion valve to the third target opening based on the comparison result between the first target opening and the third target opening.

[0013] Furthermore, the first target opening of the electronic expansion valve is calculated according to the current cooling capacity of the novel falling film water source heat pump unit, the current water outlet temperature and the current water inlet temperature, and further includes:

[0014] Calculate the current evaporation temperature Te1 of the falling film evaporator according to the current cooling capacity Q1 of the novel falling film water source heat pump unit, the current water outlet temperature Tout and the current water inlet temperature Tin;

[0015] Comparing the current evaporation temperature Te1 of the falling film evaporator with the preset theoretical evaporation temperature Te;

[0016] If Te1<Te, then increase the current opening of the electronic expansion valve until Te1=Te;

[0017] If Te1>Te, the current opening of the electronic expansion valve is reduced until Te1=Te;

[0018] If Te1=Te, the current opening of the electronic expansion valve is maintained unchanged;

[0019] The current opening degree of the electronic expansion valve in the state of Te1=Te is used as the first target opening degree X1 of the electronic expansion valve.

[0020] Further, the comparing the first target opening of the electronic expansion valve with the second target opening of the electronic expansion valve, and controlling the novel falling film water source heat pump unit to stop running or execute step S5 according to the comparison result of the first target opening and the second target opening, further includes:

[0021] comparing a first target opening degree X1 of the electronic expansion valve with a second target opening degree X2 of the electronic expansion valve;

[0022] If X1>1.05*X2, the novel falling film water source heat pump unit is controlled to stop running;

[0023] If X1≤1.05*X2, execute step S5.

[0024] Further, the calculating of the third target opening of the electronic expansion valve according to the current exhaust temperature of the compressor and the current condensing pressure of the condenser further includes:

[0025] Obtaining a current condensation temperature Tc1 of the condenser according to a current condensation pressure Ph of the condenser;

[0026] Calculate the current exhaust gas superheat Tsh1 of the compressor according to the current exhaust gas temperature Tp of the compressor and the current condensing temperature Tc1 of the condenser;

[0027] Comparing the current exhaust gas superheat Tsh1 of the compressor with a preset reasonable exhaust gas superheat Tsh;

[0028] If Tsh1>Tsh, then increase the current opening of the electronic expansion valve until Tsh1=Tsh;

[0029] If Tsh1<Tsh, then reduce the current opening of the electronic expansion valve until Tsh1=Tsh;

[0030] If Tsh1=Tsh, the current opening of the electronic expansion valve is maintained unchanged;

[0031] The current opening degree of the electronic expansion valve in the state of Tsh1 = Tsh is used as the third target opening degree X3 of the electronic expansion valve.

[0032] Further, the comparing the first target opening of the electronic expansion valve with the third target opening of the electronic expansion valve, and adjusting the current opening of the electronic expansion valve to the first target opening or adjusting the current opening of the electronic expansion valve to the third target opening according to the comparison result of the first target opening and the third target opening, further includes:

[0033] comparing a first target opening degree X1 of the electronic expansion valve with a third target opening degree X3 of the electronic expansion valve;

[0034] If X1≥X3, the current opening of the electronic expansion valve is adjusted to the first target opening X1;

[0035] If X1<X3, the current opening of the electronic expansion valve is adjusted to the third target opening X3.

[0036] The novel electronic expansion valve control method of the falling film water source heat pump unit provided by the present invention has the following beneficial effects: while achieving more effective and precise control of the electronic expansion valve, it can also reduce capital investment costs and ensure the safety, stability and reliability of the operation of the entire water source heat pump unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation of the present invention.

[0038] Figure 1 This is a structural block diagram of the novel falling film water source heat pump unit provided by the present invention.

[0039] Figure 2 A flow chart of the electronic expansion valve control method of the novel falling film water source heat pump unit provided by the present invention.

[0040] Figure 3 A flow chart of a specific implementation of the electronic expansion valve control method of the novel falling film water source heat pump unit provided by the present invention. DETAILED DESCRIPTION

[0041] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0042] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention.

[0043] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so as to describe the embodiments of the present invention described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0044] In this embodiment, a novel electronic expansion valve control method for a falling film water source heat pump unit is provided. Figure 1As shown, the novel falling film water source heat pump unit includes a compressor 1, a current transformer 2, an exhaust temperature sensor 3, a condenser 4, a high pressure pressure sensor 5, an electronic expansion valve 6, a low pressure pressure sensor 7, a falling film evaporator 8, a water outlet temperature sensor 9 and a water inlet temperature sensor 10. The compressor 1 provides power for refrigerant circulation, and water and refrigerant exchange heat in the condenser 4 or the falling film evaporator 8; the current transformer 2 is used to detect the current current of the compressor 1; the exhaust temperature sensor 3 is used to detect the current exhaust temperature of the compressor 1; the high pressure pressure sensor 5 is used to detect the current condensing pressure of the condenser 4; the low pressure pressure sensor 7 is used to detect the current evaporation pressure of the falling film evaporator 8; the water outlet temperature sensor 9 is used to detect the current water outlet temperature; the water inlet temperature sensor 10 is used to detect the current water inlet temperature; as shown Figure 2 As shown, the electronic expansion valve control method of the novel falling film water source heat pump unit includes:

[0045] Step S1: obtaining the current current of the compressor 1, the current exhaust temperature of the compressor 1, the current condensing pressure of the condenser 4, the current evaporating pressure of the falling film evaporator 8, the current outlet water temperature and the current inlet water temperature;

[0046] Step S2: Calculating the current cooling capacity of the novel falling film water source heat pump unit according to the current current of the compressor 1 and the preset full load current;

[0047] It should be noted that the preset full-load current is obtained according to the compressor ten-coefficient model theory, and the capacity percentage of the new falling film water source heat pump unit is obtained according to the current current of the compressor 1 and the preset full-load current, so as to calculate the current cooling capacity Q1 of the new falling film water source heat pump unit.

[0048] Step S3: calculating the first target opening of the electronic expansion valve 6 according to the current cooling capacity of the novel falling film water source heat pump unit, the current water outlet temperature and the current water inlet temperature, and calculating the second target opening of the electronic expansion valve 6 according to the current cooling capacity of the novel falling film water source heat pump unit, the current condensing pressure of the condenser 4 and the current evaporating pressure of the falling film evaporator 8;

[0049] Preferably, if Figure 3 As shown, the first target opening of the electronic expansion valve 6 is calculated according to the current cooling capacity of the novel falling film water source heat pump unit, the current water outlet temperature and the current water inlet temperature, and further includes:

[0050] Calculate the current evaporation temperature Te1 of the falling film evaporator 8 according to the current cooling capacity Q1 of the novel falling film water source heat pump unit, the current water outlet temperature Tout and the current water inlet temperature Tin;

[0051] Comparing the current evaporation temperature Te1 of the falling film evaporator 8 with the preset theoretical evaporation temperature Te;

[0052] If Te1<Te, the current opening of the electronic expansion valve 6 is increased until Te1=Te;

[0053] If Te1>Te, the current opening of the electronic expansion valve 6 is reduced until Te1=Te;

[0054] If Te1=Te, the current opening of the electronic expansion valve 6 is maintained unchanged;

[0055] The current opening degree of the electronic expansion valve 6 in the state of Te1=Te is taken as the first target opening degree X1 of the electronic expansion valve 6 .

[0056] Step S4: comparing the first target opening of the electronic expansion valve 6 with the second target opening of the electronic expansion valve 6, and controlling the novel falling film water source heat pump unit to stop running or executing step S5 according to the comparison result between the first target opening and the second target opening;

[0057] Preferably, if Figure 3 As shown, the first target opening of the electronic expansion valve 6 is compared with the second target opening of the electronic expansion valve 6, and the novel falling film water source heat pump unit is controlled to stop running or execute step S5 according to the comparison result of the first target opening and the second target opening, and further includes:

[0058] Compare the first target opening degree X1 of the electronic expansion valve 6 with the second target opening degree X2 of the electronic expansion valve 6;

[0059] If X1>1.05*X2 (taking into account the 5% fluctuation of the operating conditions), the novel falling film water source heat pump unit is controlled to stop running and a fault error code is output;

[0060] If X1≤1.05*X2, execute step S5.

[0061] Step S5: outputting the first target opening of the electronic expansion valve 6, and then calculating the third target opening of the electronic expansion valve 6 according to the current exhaust temperature of the compressor 1 and the current condensing pressure of the condenser 4;

[0062] Preferably, the step of calculating the third target opening of the electronic expansion valve 6 according to the current exhaust temperature of the compressor 1 and the current condensing pressure of the condenser 4 further includes:

[0063] Obtaining a current condensation temperature Tc1 of the condenser 4 according to a current condensation pressure Ph of the condenser 4;

[0064] Calculating the current exhaust gas superheat Tsh1 of the compressor 1 according to the current exhaust gas temperature Tp of the compressor 1 and the current condensing temperature Tc1 of the condenser 4;

[0065] Comparing the current exhaust gas superheat Tsh1 of the compressor 1 with a preset reasonable exhaust gas superheat Tsh;

[0066] If Tsh1>Tsh, the current opening of the electronic expansion valve 6 is increased until Tsh1=Tsh;

[0067] If Tsh1<Tsh, then reduce the current opening of the electronic expansion valve 6 until Tsh1=Tsh;

[0068] If Tsh1 = Tsh, the current opening of the electronic expansion valve 6 is maintained unchanged;

[0069] The current opening degree of the electronic expansion valve 6 in the state of Tsh1 = Tsh is used as the third target opening degree X3 of the electronic expansion valve 6 .

[0070] Step S6: Compare the first target opening of the electronic expansion valve 6 with the third target opening of the electronic expansion valve 6, and adjust the current opening of the electronic expansion valve 6 to the first target opening or adjust the current opening of the electronic expansion valve 6 to the third target opening based on the comparison result between the first target opening and the third target opening.

[0071] Preferably, if Figure 3 As shown, the first target opening of the electronic expansion valve 6 is compared with the third target opening of the electronic expansion valve 6, and the current opening of the electronic expansion valve 6 is adjusted to the first target opening or the current opening of the electronic expansion valve 6 is adjusted to the third target opening according to the comparison result of the first target opening and the third target opening, and further includes:

[0072] comparing the first target opening X1 of the electronic expansion valve 6 with the third target opening X3 of the electronic expansion valve 6;

[0073] If X1 ≥ X3 (taking into account a 5% fluctuation in the operating conditions), the current opening of the electronic expansion valve 6 is adjusted to the first target opening X1;

[0074] If X1<X3, the current opening of the electronic expansion valve 6 is adjusted to the third target opening X3.

[0075] The novel electronic expansion valve control method for the falling film water source heat pump unit provided in the embodiment of the present invention ensures that the control of the electronic expansion valve will not have a large deviation through multiple control coupling, and is safer and more reliable; compared with the traditional electronic expansion valve control logic, it is more accurate and rapid, and will not have a lag phenomenon; it has higher stability and lower implementation cost, and is a liquid supply control technology with relatively promising development prospects.

[0076] The novel electronic expansion valve control method of the falling film water source heat pump unit provided in the embodiment of the present invention can achieve more effective and accurate control of the electronic expansion valve while reducing capital investment costs and ensuring the safety, stability and reliability of the operation of the entire water source heat pump unit.

[0077] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A novel electronic expansion valve control method for a falling film water source heat pump unit, characterized in that: The novel falling film water source heat pump unit comprises a compressor (1), a current transformer (2), an exhaust temperature sensor (3), a condenser (4), a high pressure sensor (5), an electronic expansion valve (6), a low pressure sensor (7), a falling film evaporator (8), a water outlet temperature sensor (9) and a water inlet temperature sensor (10). The compressor (1) provides power for refrigerant circulation, and water and refrigerant exchange heat in the condenser (4) or the falling film evaporator (8); the current transformer (2) is used to detect the current current of the compressor (1); the exhaust temperature sensor (3) is used to detect the current exhaust temperature of the compressor (1); the high pressure sensor (5) is used to detect the current condensing pressure of the condenser (4); the low pressure sensor (7) is used to detect the current evaporation pressure of the falling film evaporator (8); the water outlet temperature sensor (9) is used to detect the current water outlet temperature; The water inlet temperature sensor (10) is used to detect the current water inlet temperature; wherein the electronic expansion valve control method of the novel falling film water source heat pump unit comprises: Step S1: obtaining the current current of the compressor (1), the current exhaust temperature of the compressor (1), the current condensing pressure of the condenser (4), the current evaporating pressure of the falling film evaporator (8), the current water outlet temperature and the current water inlet temperature; Step S2: calculating the current cooling capacity of the novel falling film water source heat pump unit according to the current current of the compressor (1) and the preset full load current; Step S3: calculating a first target opening of the electronic expansion valve (6) according to the current cooling capacity of the novel falling film water source heat pump unit, the current water outlet temperature and the current water inlet temperature, and calculating a second target opening of the electronic expansion valve (6) according to the current cooling capacity of the novel falling film water source heat pump unit, the current condensing pressure of the condenser (4) and the current evaporating pressure of the falling film evaporator (8); Step S4: comparing the first target opening of the electronic expansion valve (6) with the second target opening of the electronic expansion valve (6), and controlling the novel falling film water source heat pump unit to stop operating or executing step S5 according to the comparison result between the first target opening and the second target opening; Step S5: outputting a first target opening of the electronic expansion valve (6), and then calculating a third target opening of the electronic expansion valve (6) according to a current exhaust temperature of the compressor (1) and a current condensing pressure of the condenser (4); Step S6: comparing the first target opening of the electronic expansion valve (6) with the third target opening of the electronic expansion valve (6), and adjusting the current opening of the electronic expansion valve (6) to the first target opening or adjusting the current opening of the electronic expansion valve (6) to the third target opening based on the comparison result between the first target opening and the third target opening.

2. The electronic expansion valve control method of the novel falling film water source heat pump unit according to claim 1 is characterized in that: The first target opening degree of the electronic expansion valve (6) is calculated according to the current cooling capacity of the novel falling film water source heat pump unit, the current water outlet temperature and the current water inlet temperature, further comprising: Calculating the current evaporation temperature Te1 of the falling film evaporator (8) according to the current cooling capacity Q1 of the novel falling film water source heat pump unit, the current water outlet temperature Tout and the current water inlet temperature Tin; comparing the current evaporation temperature Te1 of the falling film evaporator (8) with the preset theoretical evaporation temperature Te; If Te1<Te, then increase the current opening of the electronic expansion valve (6) until Te1=Te; If Te1>Te, the current opening of the electronic expansion valve (6) is reduced until Te1=Te; If Te1=Te, the current opening of the electronic expansion valve (6) is maintained unchanged; The current opening degree of the electronic expansion valve (6) in the state of Te1=Te is used as the first target opening degree X1 of the electronic expansion valve (6).

3. The electronic expansion valve control method of the novel falling film water source heat pump unit according to claim 1 is characterized in that: The step of comparing the first target opening of the electronic expansion valve (6) with the second target opening of the electronic expansion valve (6), and controlling the novel falling film water source heat pump unit to stop operating or execute step S5 according to the comparison result between the first target opening and the second target opening, further comprises: comparing a first target opening degree X1 of the electronic expansion valve (6) with a second target opening degree X2 of the electronic expansion valve (6); If X1>1.05*X2, the novel falling film water source heat pump unit is controlled to stop running; If X1≤1.05*X2, execute step S5.

4. The electronic expansion valve control method of the novel falling film water source heat pump unit according to claim 1 is characterized in that: The step of calculating the third target opening degree of the electronic expansion valve (6) according to the current exhaust temperature of the compressor (1) and the current condensing pressure of the condenser (4) further includes: Obtaining a current condensation temperature Tc1 of the condenser (4) according to a current condensation pressure Ph of the condenser (4); Calculating a current exhaust gas superheat Tsh1 of the compressor (1) according to a current exhaust gas temperature Tp of the compressor (1) and a current condensing temperature Tc1 of the condenser (4); comparing a current exhaust gas superheat Tsh1 of the compressor (1) with a preset reasonable exhaust gas superheat Tsh; If Tsh1>Tsh, then increase the current opening of the electronic expansion valve (6) until Tsh1=Tsh; If Tsh1<Tsh, then reduce the current opening of the electronic expansion valve (6) until Tsh1=Tsh; If Tsh1=Tsh, the current opening of the electronic expansion valve (6) is maintained unchanged; The current opening degree of the electronic expansion valve (6) in the state of Tsh1=Tsh is used as the third target opening degree X3 of the electronic expansion valve (6).

5. The electronic expansion valve control method of the novel falling film water source heat pump unit according to claim 1 is characterized in that: The step of comparing the first target opening of the electronic expansion valve (6) with the third target opening of the electronic expansion valve (6), and adjusting the current opening of the electronic expansion valve (6) to the first target opening or adjusting the current opening of the electronic expansion valve (6) to the third target opening according to the comparison result of the first target opening and the third target opening, further comprises: comparing a first target opening degree X1 of the electronic expansion valve (6) with a third target opening degree X3 of the electronic expansion valve (6); If X1≥X3, the current opening of the electronic expansion valve (6) is adjusted to the first target opening X1; If X1<X3, the current opening of the electronic expansion valve (6) is adjusted to the third target opening X3.

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