Refrigeration enthalpy increasing control method and system based on intermediate pressure and multi-parameter coupling

Abstract

The invention discloses a refrigeration enthalpy increasing control method and system based on intermediate pressure and multi-parameter coupling. The method comprises the steps that the intermediate pressure, the operation frequency of a compressor and the temperature of a coil pipe are collected in real time; the basic enthalpy increasing opening degree is determined on the basis of the intermediate pressure, a dynamic compensation value is calculated on the basis of the coil pipe temperature, the basic enthalpy increasing opening degree is combined with the dynamic compensation value, and the target opening degree of the electronic expansion valve for enthalpy increasing is determined; and the electronic expansion valve for enthalpy increasing is adjusted according to the target opening degree of the electronic expansion valve for enthalpy increasing, and therefore refrigeration enthalpy increasing control is achieved. According to the invention, rapid response, accurate adjustment and system protection of enthalpy increase control are realized.

Description

Technical Field

[0001] This invention relates to the field of refrigeration and heat pump technology, and more specifically, to a refrigeration enthalpy increase control method and system based on intermediate pressure and multi-parameter coupling. Background Technology

[0002] Vapor injection enthalpy enhancement technology is a key technology for improving the performance and operational reliability of refrigeration / heat pump systems over a wide range of operating conditions, especially under extreme conditions. Its principle is to increase the compressor's discharge volume and reduce the discharge temperature by injecting gas into the system, thereby improving the system's energy efficiency ratio and heating capacity. Existing vapor jet enthalpy control strategies are mostly based on fixed superheat or evaporation / condensation pressure; however, these methods have significant drawbacks: 1. Response lag: Superheat is a result of system operation rather than a cause. Its changes lag behind the actual changes in system load, resulting in slow control response, poor system stability, and difficulty in achieving optimal energy efficiency.

[0003] 2. Poor adaptability to operating conditions: The fixed threshold control logic cannot adapt to complex and changing ambient temperatures and load demands. When the ambient temperature is high, excessive enthalpy increase may lead to excessively high intermediate pressure, which in turn increases the compressor load and may even trigger system protection shutdown, thus compromising reliability.

[0004] 3. Lack of systematic protection: Existing technologies typically do not consider compressor operating frequency as a prerequisite for enthalpy enhancement. At low frequencies, the compressor's displacement is small, resulting in limited benefits from enthalpy enhancement and potentially disrupting the system's normal refrigerant circulation, leading to decreased efficiency and the risk of liquid slugging.

[0005] Chinese invention application No. 202110878070.7 discloses "Electronic Expansion Valve Control Method, Device, Air Conditioner and Storage Medium". In this invention, when the first current exhaust temperature of the outdoor unit is less than the preset target temperature, a first temperature difference is determined based on the first current exhaust temperature and the first historical exhaust temperature detected last time. When the first temperature difference is less than the first preset temperature, the opening degree to be adjusted is determined based on the first current exhaust temperature, and the opening degree of the electronic expansion valve is adjusted. Summary of the Invention

[0006] To address the technical problems existing in the background art, this invention provides a refrigeration enthalpy increase control method and system based on intermediate pressure and multi-parameter coupling. The technical solution adopted by this invention is as follows: The first aspect of this invention provides a method for controlling refrigeration enthalpy increase based on intermediate pressure and multi-parameter coupling, the method comprising: Real-time monitoring of intermediate pressure, compressor operating frequency, and coil temperature; The basic enthalpy-increasing opening is determined based on the intermediate pressure, and the dynamic compensation value is calculated based on the coil temperature. The basic enthalpy-increasing opening and the dynamic compensation value are combined to determine the target opening of the electronic expansion valve for enthalpy increase. The electronic expansion valve for enthalpy increase is adjusted according to the target opening degree of the electronic expansion valve for enthalpy increase, thereby realizing enthalpy increase control for refrigeration.

[0007] As a preferred embodiment, before determining the basic enthalpy-increasing opening based on the intermediate pressure, an enthalpy-increasing enable determination step is also included: Determine whether the preset compressor frequency condition and intermediate pressure protection condition are met simultaneously; If all conditions are met, the opening of the electronic expansion valve for increasing enthalpy can be adjusted; if any condition is not met, the electronic expansion valve for increasing enthalpy is controlled to close.

[0008] As a preferred embodiment, the compressor frequency condition is: the compressor operating frequency is not lower than a preset frequency threshold; the intermediate pressure protection condition is: the intermediate pressure is not higher than a preset pressure protection threshold.

[0009] As a preferred embodiment, the calculation method of the dynamic compensation value satisfies the following relationship: ΔOpen = C - K * (Tcoil - T0) Where ΔOpen is the dynamic compensation value, C is the compensation constant, K is the compensation coefficient greater than zero, Tcoil is the real-time acquired coil temperature, and T0 is the reference coil temperature.

[0010] As a preferred embodiment, the method for determining the basic enthalpy increase opening based on the intermediate pressure includes: The value is obtained by looking up a pre-defined intermediate pressure-basic enthalpy increase opening mapping table.

[0011] As a preferred embodiment, the formula for calculating the target opening of the electronic expansion valve for enthalpy increase is as follows: Target_Opening = Base_Opening + Δopen, Wherein, Target_Opening is the target opening degree, Base_Opening is the base enthalpy opening degree, and ΔOpen is the dynamic compensation value.

[0012] The second aspect of the present invention provides a refrigeration enthalpy increase control system based on intermediate pressure and multi-parameter coupling, the system including a parameter acquisition module, a target opening degree calculation module and an opening degree adjustment module; The parameter acquisition module is used to collect intermediate pressure, compressor operating frequency and coil temperature in real time. The target opening calculation module is used to determine the basic enthalpy increase opening based on the intermediate pressure, and to calculate the dynamic compensation value based on the coil temperature. The basic enthalpy increase opening is combined with the dynamic compensation value to determine the target opening of the electronic expansion valve for enthalpy increase. The opening adjustment module is used to adjust the electronic expansion valve for enthalpy increase according to the target opening of the electronic expansion valve for enthalpy increase, thereby realizing enthalpy increase control for refrigeration.

[0013] As a preferred embodiment, the parameter acquisition module includes an intermediate pressure acquisition module, a frequency acquisition module, and a temperature acquisition module; The intermediate pressure acquisition module is used to acquire intermediate pressure in real time. The frequency acquisition module is used to acquire the compressor's operating frequency in real time; The temperature acquisition module is used to acquire the coil temperature in real time.

[0014] As a preferred embodiment, the system further includes an enthalpy increase enable judgment module, which is used for: Determine whether the preset compressor frequency condition and intermediate pressure protection condition are met simultaneously; If all conditions are met, the opening of the electronic expansion valve for increasing enthalpy can be adjusted; if any condition is not met, the electronic expansion valve for increasing enthalpy is controlled to close.

[0015] Compared with the prior art, the beneficial effects of this invention are: This invention employs an intermediate pressure acquisition module to detect intermediate pressure in real time. This allows the control system to directly and instantly perceive system load changes, providing fast and accurate input to the control logic. This significantly improves the system's response speed and control precision, enhancing system stability and dynamic performance. By introducing an "enthalpy enhancement enable judgment" logic that includes compressor operating frequency conditions and absolute intermediate pressure protection conditions, the frequency condition prevents enthalpy enhancement from activating under low load and low compressor displacement, avoiding energy efficiency degradation and potential liquid slugging risks. The pressure protection condition provides a high-pressure safety valve for the system, directly preventing system overpressure and compressor damage caused by excessive gas injection. By introducing a dynamic compensation value (ΔOpen) based on coil temperature (Tcoil), which is related to both coil and ambient temperatures, the invention corrects the basic enthalpy enhancement opening, achieving adaptive optimization of enthalpy enhancement control. When the ambient and coil temperatures are high, the gas injection amount is automatically reduced to prevent excessively high condensing pressure and a surge in compressor power consumption. When the ambient temperature is suitable or low, the gas injection amount is automatically increased to maximize the advantages of jet enthalpy enhancement in reducing exhaust temperature and improving energy efficiency. This enables the system to intelligently adapt to a wide range of environmental conditions and load requirements, always maintaining an efficient and safe operating range. Attached Figure Description

[0016] Figure 1 This is a flowchart of the refrigeration enthalpy increase control method based on intermediate pressure and multi-parameter coupling provided in this embodiment; Figure 2 This is a block diagram of the refrigeration enthalpy increase control system based on intermediate pressure and multi-parameter coupling provided in this embodiment; Figure 3 This is a schematic diagram of a refrigeration enthalpy enhancement system. Detailed Implementation The accompanying drawings are for illustrative purposes only and should not be construed as limiting the invention. It should be understood that the described embodiments are merely some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of the embodiments of this application.

[0017] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0018] In the following description, when referring to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims. In the description of this application, it should be understood that the terms "first," "second," "third," etc., are used only to distinguish similar objects and are not necessarily used to describe a specific order or sequence, nor should they be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0019] Furthermore, in the description of this application, unless otherwise stated, "multiple" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. The invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] Example 1 Please refer to Figure 1 This embodiment provides a refrigeration enthalpy increase control method based on intermediate pressure and multi-parameter coupling, the method including: S1: Real-time acquisition of intermediate pressure, compressor operating frequency, and coil temperature; S2: Determine the basic enthalpy increase opening based on the intermediate pressure, calculate the dynamic compensation value based on the coil temperature, and combine the basic enthalpy increase opening with the dynamic compensation value to determine the target opening of the electronic expansion valve for enthalpy increase; In one specific embodiment, before determining the basic enthalpy increase opening based on the intermediate pressure, an enthalpy increase enable determination step is also included: Determine whether the preset compressor frequency condition and intermediate pressure protection condition are met simultaneously; If all conditions are met, the opening of the electronic expansion valve for increasing enthalpy can be adjusted; if any condition is not met, the electronic expansion valve for increasing enthalpy is controlled to close.

[0022] In one specific embodiment, the compressor frequency condition is: the compressor operating frequency is not lower than a preset frequency threshold; the intermediate pressure protection condition is: the intermediate pressure is not higher than a preset pressure protection threshold.

[0023] In a preferred embodiment, the preset frequency threshold is 41 Hz and the preset pressure protection threshold is 2.7 MPa.

[0024] In a specific embodiment, the calculation method of the dynamic compensation value satisfies the following relationship: ΔOpen = C - K * (Tcoil - T0) Where ΔOpen is the dynamic compensation value, C is the compensation constant, K is the compensation coefficient greater than zero, Tcoil is the real-time acquired coil temperature, and T0 is the reference coil temperature.

[0025] In a preferred embodiment, the compensation constant is 8, in units of pulse count or opening percentage, the compensation coefficient K is 0.2, and the reference coil temperature T0 is 25°C.

[0026] In one specific embodiment, the method for determining the basic enthalpy increase opening based on the intermediate pressure includes: The value is obtained by looking up a pre-defined intermediate pressure-basic enthalpy increase opening mapping table.

[0027] In one specific embodiment, the formula for calculating the target opening of the electronic expansion valve for enthalpy increase is as follows: Target_Opening = Base_Opening + Δopen, Wherein, Target_Opening is the target opening degree, Base_Opening is the base enthalpy opening degree, and ΔOpen is the dynamic compensation value.

[0028] In one specific embodiment, the operation of the "exhaust" control logic includes: 1. High-temperature operating conditions (high ambient temperature leads to an increase in coil temperature T_coil): Situation: For example, in summer when the temperature is high, the coil temperature T_coil rises from 25°C to 40°C.

[0029] Calculate: ΔOpen = 8 - 0.2 * (40 - 25) = 8 - 3 = 5 Logic: An increase in the value of (T_coil – T0) leads to a decrease in the ΔOpen compensation value, which in turn leads to a decrease in the final Target_Opening.

[0030] Impact on "exhaust": The opening of the electronic expansion valve for enthalpy increase decreases, reducing the amount of intermediate-pressure gaseous refrigerant supplied. This is because, under high-temperature conditions, the system's condensing pressure is already very high. If a large amount of gas is supplied, it will lead to excessively high intermediate pressure Pm, increased compressor work, decreased efficiency, and even triggering high-pressure protection. By reducing gas supply, these problems are avoided, while ensuring that the exhaust temperature does not rise abnormally due to excessive compressor load. This is a preventative and optimized exhaust control logic.

[0031] Low temperature / standard operating conditions (moderate or low ambient temperature resulting in lower T_coil): Situation: For example, in spring and autumn or at the beginning of the cooling process, T_coil is 20°C.

[0032] Calculate: ΔOpen = 8 - 0.2 * (20 - 25) = 8 - (-1) = 9 Logic: A negative (T_coil – T0) value leads to an increase in the ΔOpen compensation value, which in turn leads to an increase in the final Target_Opening.

[0033] Impact on "exhaust": The opening of the electronic expansion valve for enthalpy enhancement increases, leading to a greater supply gas volume. Under standard or low load conditions, the system allows and requires more supply gas to significantly reduce the compressor's exhaust temperature, improving system energy efficiency and operational reliability. At this point, the intermediate pressure Pm is within a safe range, and increasing the supply gas volume maximizes the advantages of jet enthalpy enhancement technology. S3: Adjust the electronic expansion valve for enthalpy increase according to the target opening degree of the electronic expansion valve for enthalpy increase, thereby realizing enthalpy increase control for refrigeration.

[0034] Example 2 Please refer to Figure 2 This embodiment provides a refrigeration enthalpy increase control system based on intermediate pressure and multi-parameter coupling. The system includes a parameter acquisition module, a target opening degree calculation module, and an opening degree adjustment module. The parameter acquisition module is used to collect intermediate pressure, compressor operating frequency and coil temperature in real time. The target opening calculation module is used to determine the basic enthalpy increase opening based on the intermediate pressure, and to calculate the dynamic compensation value based on the coil temperature. The basic enthalpy increase opening is combined with the dynamic compensation value to determine the target opening of the electronic expansion valve for enthalpy increase. The opening adjustment module is used to adjust the electronic expansion valve for enthalpy increase according to the target opening of the electronic expansion valve for enthalpy increase, thereby realizing enthalpy increase control for refrigeration.

[0035] In one specific embodiment, the parameter acquisition module includes an intermediate pressure acquisition module, a frequency acquisition module, and a temperature acquisition module; The intermediate pressure acquisition module is used to acquire intermediate pressure in real time. The frequency acquisition module is used to acquire the compressor's operating frequency in real time; The temperature acquisition module is used to acquire the coil temperature in real time.

[0036] In one specific embodiment, the system further includes an enthalpy increase enable determination module, which is used to: Determine whether the preset compressor frequency condition and intermediate pressure protection condition are met simultaneously; If all conditions are met, the opening of the electronic expansion valve for increasing enthalpy can be adjusted; if any condition is not met, the electronic expansion valve for increasing enthalpy is controlled to close.

[0037] Please refer to Figure 3 , Figure 3 This is a schematic diagram of a refrigeration enthalpy enhancement system, which includes a shell-and-tube heat exchanger, a four-way valve and its components, a high-pressure switch, a needle valve, a low-pressure switch, a drive board, an ambient temperature sensor, a gas-liquid separator, a compressor, a finned heat exchanger, a filter, an electronic expansion valve, a pressure sensor, a plate heat exchanger, a coil sensor, and an electronic expansion valve for enthalpy enhancement. Figure 3 The section marked in red represents the enthalpy-increasing circuit, which includes a plate heat exchanger, an electronic expansion valve for enthalpy increase, and a compressor. The intermediate pressure acquisition module includes the pressure sensor, which is installed on the connecting pipeline between the plate heat exchanger and the compressor to collect intermediate pressure in real time. The frequency acquisition module includes the drive board, which is used to collect the compressor's operating frequency in real time. The temperature acquisition module includes a coil sensor to collect the coil temperature in real time.

[0038] Example 3 This embodiment provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the cooling enthalpy increase control method based on intermediate pressure and multi-parameter coupling described in Embodiment 1.

[0039] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A refrigeration enthalpy increase control method based on intermediate pressure and multi-parameter coupling, characterized in that, The method includes: Real-time monitoring of intermediate pressure, compressor operating frequency, and coil temperature; The basic enthalpy increase opening is determined based on the intermediate pressure, and the dynamic compensation value is calculated based on the coil temperature. The basic enthalpy increase opening and the dynamic compensation value are combined to determine the target opening of the electronic expansion valve for enthalpy increase. The electronic expansion valve for enthalpy increase is adjusted according to the target opening degree of the electronic expansion valve for enthalpy increase, thereby realizing enthalpy increase control for refrigeration.

2. The refrigeration enthalpy increase control method based on intermediate pressure and multi-parameter coupling according to claim 1, characterized in that, Before determining the basic enthalpy-increasing opening based on the intermediate pressure, the process also includes an enthalpy-increasing enable determination step: Determine whether the preset compressor frequency condition and intermediate pressure protection condition are met simultaneously; If all conditions are met, the opening of the electronic expansion valve for increasing enthalpy can be adjusted; if any condition is not met, the electronic expansion valve for increasing enthalpy is controlled to close.

3. The refrigeration enthalpy increase control method based on intermediate pressure and multi-parameter coupling according to claim 2, characterized in that, The compressor frequency condition is: the compressor operating frequency is not lower than a preset frequency threshold; the intermediate pressure protection condition is: the intermediate pressure is not higher than a preset pressure protection threshold.

4. The refrigeration enthalpy increase control method based on intermediate pressure and multi-parameter coupling according to claim 1, characterized in that, The calculation method for the dynamic compensation value satisfies the following relationship: ΔOpen = C - K * (Tcoil - T0) Where ΔOpen is the dynamic compensation value, C is the compensation constant, K is the compensation coefficient greater than zero, Tcoil is the real-time acquired coil temperature, and T0 is the reference coil temperature.

5. The refrigeration enthalpy increase control method based on intermediate pressure and multi-parameter coupling according to claim 1, characterized in that, The method for determining the basic enthalpy-increasing opening based on the intermediate pressure includes: The value is obtained by looking up a pre-defined intermediate pressure-basic enthalpy increase opening mapping table.

6. The refrigeration enthalpy increase control method based on intermediate pressure and multi-parameter coupling according to claim 1, characterized in that, The formula for calculating the target opening of the electronic expansion valve for enthalpy increase is as follows: Target_Opening = Base_Opening + Δopen, Wherein, Target_Opening is the target opening degree, Base_Opening is the base enthalpy opening degree, and ΔOpen is the dynamic compensation value.

7. A refrigeration enthalpy increase control system based on intermediate pressure and multi-parameter coupling, characterized in that, The system includes a parameter acquisition module, a target opening calculation module, and an opening adjustment module; The parameter acquisition module is used to collect intermediate pressure, compressor operating frequency and coil temperature in real time. The target opening calculation module is used to determine the basic enthalpy increase opening based on the intermediate pressure, and to calculate the dynamic compensation value based on the coil temperature. The basic enthalpy increase opening is combined with the dynamic compensation value to determine the target opening of the electronic expansion valve for enthalpy increase. The opening adjustment module is used to adjust the electronic expansion valve for enthalpy increase according to the target opening of the electronic expansion valve for enthalpy increase, thereby realizing enthalpy increase control for refrigeration.

8. The refrigeration enthalpy increase control system based on intermediate pressure and multi-parameter coupling according to claim 7, characterized in that, The parameter acquisition module includes an intermediate pressure acquisition module, a frequency acquisition module, and a temperature acquisition module; The intermediate pressure acquisition module is used to acquire intermediate pressure in real time. The frequency acquisition module is used to acquire the compressor's operating frequency in real time; The temperature acquisition module is used to acquire the coil temperature in real time.

9. The refrigeration enthalpy increase control system based on intermediate pressure and multi-parameter coupling according to claim 7, characterized in that, The system further includes an enthalpy increase enable judgment module, which is used for: Determine whether the preset compressor frequency condition and intermediate pressure protection condition are met simultaneously; If all conditions are met, the opening of the electronic expansion valve for increasing enthalpy can be adjusted; if any condition is not met, the electronic expansion valve for increasing enthalpy is controlled to close.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by the processor, it implements the steps of the cooling enthalpy control method based on intermediate pressure and multi-parameter coupling as described in any one of claims 1 to 6.

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