Expansion valve control method and heat pump ejection augmented enthalpy system

Abstract

The present application relates to air heat pump technical field, especially to a kind of expansion valve control method and heat pump air injection enthalpy increasing system, expansion valve control method includes the following steps: unit normal start heating, detect ambient temperature Ta, exhaust temperature Td, back gas temperature Ts, outlet water temperature To, inlet water temperature Ti, liquid pipe temperature TliP and coil temperature Tdef;Expansion valve enters start initial opening and keeps set length;Expansion valve enters opening adjustment state;Detect the suction superheat TSH of unit, exhaust superheat TdSH and subcooling TlSH, wherein TSH=Ts-Tdef, TdSH=Td-To, TlSH=To-TliP;Difference between current suction superheat TSH and target suction superheat ΔTSH, difference between exhaust superheat TdSH and target exhaust superheat ΔTdSH, difference between subcooling TlSH and target subcooling ΔTlSH;According to the opening of expansion valve is controlled according to the calculation result.The present application can effectively regulate expansion valve.

Description

Technical Field

[0001] This invention relates to the field of air heat pump technology, and in particular to an expansion valve control method and a heat pump vapor injection enthalpy enhancement system. Background Technology

[0002] like Figure 2 As shown, existing ordinary air source heat pumps on the market rely on electricity to drive compressor 1. Compressor 1 creates a high-pressure and low-pressure system environment. Liquid refrigerant absorbs heat from the air in the low-pressure evaporator 5 and evaporates into a gaseous form. The gaseous refrigerant is then compressed by compressor 1 to become a high-pressure, high-temperature state. In condenser 3, the high-pressure, high-temperature gaseous refrigerant condenses into a liquid, simultaneously transferring heat to the water, thus heating the water. The liquid refrigerant enters the economizer through the main circuit, and then enters the evaporator 5 through the economizer and expansion valve 4 to absorb heat from the air. Finally, it enters compressor 1 through four-way valve 2. Air source heat pump water heaters are electrically driven, but they do not directly heat water with electricity. Instead, they heat water by the temperature difference between the inside and outside of the pipes, ensuring water and electricity isolation and making them very safe. During operation, no waste gas, waste residue, or other pollutants are emitted, making them green and environmentally friendly.

[0003] To ensure stable operation of the heat pump system, current systems typically employ an expansion valve 4. The opening of the expansion valve 4 is adjusted by a stepper motor, with the smallest angle range of the stepper motor's rotation defined as a "step." Therefore, the opening adjustment of the expansion valve 4 is generally measured in "steps." During heat pump operation, the opening of the expansion valve 4 is adjusted according to actual needs. In existing technology, the return gas superheat or exhaust gas superheat of the expansion valve 4 is controlled by a set step size. This adjustment is too simplistic and lagging, failing to effectively assess and adjust for complex operating conditions, easily leading to uncontrolled adjustment and high / low pressure faults.

[0004] Therefore, an expansion valve control method and a heat pump vapor injection enthalpy enhancement system are needed to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide an expansion valve control method and a heat pump jet enthalpy enhancement system, which can effectively regulate the expansion valve, thereby avoiding uncontrolled regulation and eliminating malfunctions.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] The expansion valve control method includes the following steps:

[0008] S1. When the unit is running normally and heating, the ambient temperature Ta, exhaust temperature Td, return gas temperature Ts, outlet water temperature To, inlet water temperature Ti, liquid pipe temperature TliP, and coil temperature Tdef are monitored.

[0009] S2, the expansion valve enters the initial opening degree of start and keeps for a set time length;

[0010] S3, the expansion valve turns into the opening degree adjustment state;

[0011] S4, the suction superheat TSH, the exhaust superheat TdSH and the subcooling TlSH of the unit are detected, wherein TSH=Ts-Tdef, TdSH=Td-To, TlSH=To-TliP;

[0012] S5, the difference between the current suction superheat TSH and the target suction superheat ΔTSH, the difference between the exhaust superheat TdSH and the target exhaust superheat ΔTdSH, and the difference between the subcooling TlSH and the target subcooling ΔTlSH are compared;

[0013] S6, the opening degree of the expansion valve is controlled according to the calculation result.

[0014] Further, in the step S5, when TSH-ΔTSH>0 and TdSH-ΔTdSH>0 and TlSH-ΔTlSH>0, or TSH-ΔTSH<0 and TdSH-ΔTdSH<0 and TlSH-ΔTlSH<0, the opening degree of the expansion valve is adjusted according to the increment ΔP.

[0015] Further, ΔP=ΔPdsh, wherein ΔPdsh is the operation opening degree value of the expansion valve adjusted according to the exhaust superheat deviation and the exhaust superheat deviation change rate in the set time length.

[0016] Further, if not satisfied, the opening degree of the expansion valve is adjusted using the valve increment ΔP1 of the return gas superheat control.

[0017] Further, ΔP1=ΔPsh, ΔPsh is the operation opening degree value of the expansion valve adjusted according to the return gas superheat deviation and the return gas superheat deviation change rate in the set time length.

[0018] Further, it is also necessary to further judge TlSH, if TlSH-ΔTlSH≥0, ΔP1 adjusts the opening degree of the expansion valve according to the return gas superheat setting increment.

[0019] Further, if TlSH-ΔTlSH<0, ΔP1 cannot be negative.

[0020] Further, the initial opening degree in the step S2 can be calibrated according to the actual situation.

[0021] Further, the target suction superheat degree ΔTSH, the target discharge superheat degree ΔTdSH and the target subcooling degree ΔTlSH can be calibrated according to actual conditions.

[0022] The heat pump jet augmenting enthalpy system comprises an expansion valve, and the expansion valve is controlled by using the expansion valve control method.

[0023] The present application has the following beneficial effects:

[0024] The expansion valve control method provided by the present application comprises the following steps: when a unit is normally started and heated, detecting various temperatures, and then the expansion valve enters a starting initial opening degree and is kept for a set time length, and then the expansion valve enters an opening degree adjusting state, detecting a suction superheat degree TSH, a discharge superheat degree TdSH and a subcooling degree TlSH of the unit, comparing a difference between the current suction superheat degree TSH and a target suction superheat degree ΔTSH, a difference between the discharge superheat degree TdSH and a target discharge superheat degree ΔTdSH, and a difference between the subcooling degree TlSH and a target subcooling degree ΔTlSH, and controlling the opening degree of the expansion valve according to the calculation result.

[0025] The heat pump jet augmenting enthalpy system provided by the present application comprises an expansion valve, and the expansion valve is controlled by using the expansion valve control method, so that the expansion valve can be effectively adjusted, and thus the adjustment is prevented from being out of control and the fault is eliminated. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments of the present application will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art according to the contents of the embodiments of the present application and the drawings without any creative effort.

[0027] Figure 1 is a flow chart of the expansion valve control method of the present application;

[0028] Figure 2 is a principle diagram of the heat pump jet augmenting enthalpy system.

[0029] In the drawings:

[0030] 1, compressor; 2, four-way valve; 3, condenser; 4, expansion valve; 5, evaporator. DETAILED DESCRIPTION

[0031] Before any embodiments of the application are explained in detail, it is to be understood that the application is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the above-described drawings. It is being understood that the same are merely exemplary.

[0032] In this application, the terms "comprise", "contain", "include", or any other variant thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without more limitations, an element defined by the phrase "comprising a" does not exclude the existence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0033] In this application, the term "and / or", is a description of the associated relationship between objects, which means that there can be three kinds of relationships. For example, an expansion valve control method and / or an expansion valve control method can mean that there is only one expansion valve control method, there is an expansion valve control method and an expansion valve control method at the same time, and there is only an expansion valve control method. In addition, the character " / " in this application generally represents a "and / or" relationship between the front and rear associated objects.

[0034] In this application, the terms "connection", "combination", "coupling", "mounting" can be direct connection, combination, coupling or mounting, or indirect connection, combination, coupling or mounting. Among them, for example, direct connection means that two parts or components are connected together without setting intermediate parts, indirect connection means that two parts or components are connected with at least one intermediate part, and the two parts or components are connected through the intermediate part. In addition, "connection" and "coupling" are not limited to physical or mechanical connection or coupling, and can include electrical connection or coupling.

[0035] In this application, those of ordinary skill in the art will understand that the relative terms used in connection with a quantity or a condition (for example, "about", "approximately", "substantially" and the like) include the value indicated and have the meaning indicated by the context. For example, the relative terms at least include the degree of error related to the measurement of a specific value, the tolerance caused by manufacturing, assembly, use, etc. related to a specific value. Such terms should also be considered to disclose the range defined by the absolute values of the two endpoints. The relative term can refer to a certain percentage (for example, 1%, 5%, 10% or more) of the indicated value. The numerical value without the relative term should also be disclosed as a specific value with a tolerance. In addition, "substantially" when expressing the relative angular positional relationship (for example, substantially parallel, substantially perpendicular), can refer to a certain degree (for example, 1 degree, 5 degrees, 10 degrees or more) added or subtracted from the indicated angle.

[0036] In this application, it will be understood by those of ordinary skill in the art that the functions performed by components can be performed by one component, multiple components, one part, or multiple parts.

[0037] In this application, the terms "upper", "lower", "left", "right", "front", "back", and the like are described in the orientation and positional relationship shown in the drawings, and should not be understood as limiting the embodiments of the present application. In addition, it is also understood in the context that when referring to one element connected to another element "on" or "under", it can be directly connected to another element "on" or "under" or indirectly connected to another element "on" or "under" through an intermediate element. It should also be understood that the terms "upper", "lower", "left", "right", "front", "back", and the like not only represent the positive direction, but also can be understood as the side direction. For example, the lower side can include the directly below, left below, right below, front below, and back below, etc.

[0038] When the heat pump jet augmenting enthalpy system is working, in order to be able to effectively adjust the expansion valve, thereby avoiding out-of-control adjustment, eliminating faults, such as Figure 1 As shown in the figure, the present application provides an expansion valve control method. The expansion valve control method comprises the following steps:

[0039] S1, the unit is normally started to heat, and the ambient temperature Ta, the exhaust temperature Td, the return air temperature Ts, the outlet water temperature To, the inlet water temperature Ti, the liquid pipe temperature TliP and the coil temperature Tdef are detected, wherein the exhaust temperature is the discharge temperature of the gaseous refrigerant of the compressor, the return air temperature is the temperature of the gaseous refrigerant entering the compressor, the outlet water temperature is the outlet water temperature of the condenser, the inlet water temperature is the inlet water temperature of the condenser, the liquid pipe temperature is the temperature of the refrigerant in the condenser, and the coil temperature is the temperature of the refrigerant in the evaporator;

[0040] S2, the expansion valve enters the starting initial opening and keeps for a set time length;

[0041] S3, the expansion valve enters the opening adjustment state;

[0042] S4, the suction superheat TSH, the exhaust superheat TdSH and the subcooling TlSH of the unit are detected, wherein TSH = Ts-Tdef, TdSH = Td-To, and TlSH = To-TliP;

[0043] S5, the difference between the current suction superheat TSH and the target suction superheat ΔTSH, the difference between the exhaust superheat TdSH and the target exhaust superheat ΔTdSH, and the difference between the subcooling TlSH and the target subcooling ΔTlSH are compared;

[0044] S6、According to the calculation result, the opening of the expansion valve is controlled.

[0045] By adjusting the opening of the expansion valve according to the suction superheat degree, the exhaust superheat degree and the supercooling degree, the adjustment can be avoided to be too single, the judgment and adjustment of the complex operation condition can be met, so that the expansion valve can be effectively adjusted, and the adjustment out of control can be avoided.

[0046] Further, in step S5, when TSH-ΔTSH>0 and TdSH-ΔTdSH>0 and TlSH-ΔTlSH>0, or TSH-ΔTSH<0 and TdSH-ΔTdSH<0 and TlSH-ΔTlSH<0, the opening of the expansion valve is adjusted according to the increment ΔP. Through the above analysis, if the above conditions are met, it is determined that there is a need for adjustment between the exhaust temperature and the outlet water temperature, and by adjusting the opening of the expansion valve, the gasification efficiency of the liquid refrigerant can be adjusted, so as to achieve the effect of adjusting the exhaust superheat degree. Moreover, the intervention time of the exhaust superheat degree adjustment can be judged, so that when the expansion valve needs to be adjusted more quickly, a larger valve adjustment amount of the exhaust superheat degree is selected to quickly respond to the adjustment rate, so as to prevent the system from being liquid-impinged and the exhaust protection or high-pressure situation from being caused due to the lagging adjustment of the expansion valve.

[0047] Further, ΔP=ΔPdsh, wherein ΔPdsh is the operation opening value of the expansion valve obtained according to the exhaust superheat degree deviation and the exhaust superheat degree deviation change rate within the set time length. By using the above method, the adjustment is made according to the exhaust superheat degree deviation and the exhaust superheat degree deviation change rate, which plays a role of pre-judgment, so as to reduce the lag of the adjustment and control, and the function of quickly adjusting the opening of the expansion valve can be well met.

[0048] Further, if the conditions are not met, the opening of the expansion valve is adjusted by using the return gas superheat degree control valve increment ΔP1. By analyzing, when the conditions of adjusting the opening of the expansion valve by using the exhaust superheat degree control are not met, the return gas superheat degree control is used to adjust the expansion valve, so as to ensure that the operation opening of the expansion valve meets the actual working condition, thereby ensuring that the heat pump system has high energy efficiency. Moreover, the exhaust superheat degree control or the return gas superheat degree control is used according to the actual needs, the control mode of the expansion valve is enriched, and the needs of the adjustment and control under different working conditions can be met.

[0049] Further, ΔP1=ΔPsh, and ΔPsh is the operation opening value of the expansion valve obtained according to the return gas superheat degree deviation and the return gas superheat degree deviation change rate within the set time length. By using the above method, the adjustment is made according to the return gas superheat degree deviation and the return gas superheat degree deviation change rate, which plays a role of pre-judgment, so as to reduce the lag of the adjustment and control, and the function of quickly adjusting the opening of the expansion valve can be well met.

[0050] Further, it is also needed to further judge TlSH, if TlSH-ΔTlSH≥0, then ΔP1 adjusts the opening of the expansion valve according to the set increment of the superheat degree of the return gas. The set increment is used for control, which can meet the need of adjusting the opening of the expansion valve, and the control is simple.

[0051] Further, if TlSH-ΔTlSH<0, then ΔP1 cannot be negative. Through the above limitation, the opening of the expansion valve can be avoided to be small.

[0052] Further, the initial opening in step S2 can be calibrated according to the actual situation. Through the test or long-term data arrangement, different initial openings can be set for different environments, so that the corresponding initial opening is set according to the use environment of the heat pump jet and enthalpy increasing system, so that the heat pump jet and enthalpy increasing system can be normally started, and the liquid hammer caused by unstable control of the expansion valve during starting is avoided.

[0053] Further, the target suction superheat degree ΔTSH, the target discharge superheat degree ΔTdSH and the target subcooling degree ΔTlSH can be calibrated according to the actual situation. Different target suction superheat degrees ΔTSH, target discharge superheat degrees ΔTdSH and target subcooling degrees ΔTlSH can be set for different environments, so that the heat pump jet and enthalpy increasing system is set according to the use environment, so that the heat pump jet and enthalpy increasing system can be stably operated.

[0054] The embodiment also provides a heat pump jet and enthalpy increasing system, which comprises an expansion valve, and the expansion valve is controlled by using the above expansion valve control method, so that the expansion valve can be effectively adjusted, and the out-of-control adjustment and the failure can be avoided.

[0055] Obviously, the above embodiment of the present application is only an example for clearly explaining the present application, and is not a limitation on the embodiments of the present application. For those skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, all the embodiments are not enumerated, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application should be included in the protection scope of the claims of the present application.

Claims

1. An expansion valve control method, characterized in that, Includes the following steps: S1. When the unit is running normally and heating, the ambient temperature Ta, exhaust temperature Td, return gas temperature Ts, outlet water temperature To, inlet water temperature Ti, liquid pipe temperature TliP, and coil temperature Tdef are monitored. S2. The expansion valve enters the initial opening degree and remains at the set duration. S3. The expansion valve enters the opening adjustment state; S4. Detect the intake superheat TSH, exhaust superheat TdSH and subcooling TlSH of the unit, where TSH=Ts-Tdef, TdSH=Td-To, and TlSH=To-TliP; S5. Compare the difference between the current intake superheat TSH and the target intake superheat ΔTSH, the difference between the exhaust superheat TdSH and the target exhaust superheat ΔTdSH, and the difference between the subcooling TlSH and the target subcooling ΔTlSH. S6. Control the opening degree of the expansion valve according to the calculation results; In step S5, when TSH-ΔTSH>0 and TdSH-ΔTdSH>0 and TlSH-ΔTlSH>0, or TSH-ΔTSH<0 and TdSH-ΔTdSH<0 and TlSH-ΔTlSH<0, the opening of the expansion valve is adjusted according to the increment ΔP to control the exhaust superheat.

2. The expansion valve control method according to claim 1, characterized in that, ΔP = ΔPdsh, where ΔPdsh is the operating opening value of the expansion valve calculated based on the exhaust superheat deviation and the rate of change of exhaust superheat deviation within a set time period.

3. The expansion valve control method according to claim 1, characterized in that, If the conditions are not met, the opening of the expansion valve is adjusted by using the return gas superheat control valve increment ΔP1.

4. The expansion valve control method according to claim 3, characterized in that, ΔP1 = ΔPsh, where ΔPsh is the operating opening value of the expansion valve calculated based on the return gas superheat deviation and the rate of change of the return gas superheat deviation within a set time period.

5. The expansion valve control method according to claim 3, characterized in that, Further determination of TlSH is required. If TlSH-ΔTlSH≥0, then ΔP1 adjusts the opening of the expansion valve according to the return gas superheat setting increment.

6. The expansion valve control method according to claim 5, characterized in that, If TlSH-ΔTlSH<0, then ΔP1 cannot be negative.

7. The expansion valve control method according to claim 1, characterized in that, The initial opening in step S2 can be calibrated according to the actual situation.

8. The expansion valve control method according to claim 1, characterized in that, The target intake superheat ΔTSH, the target exhaust superheat ΔTdSH, and the target subcooling ΔTlSH can be calibrated according to actual conditions.

9. A heat pump vapor injection enthalpy enhancement system, characterized in that, It includes an expansion valve, which is controlled by the expansion valve control method as described in any one of claims 1-8.

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