Mixed working fluid throttling refrigeration system with active regulation of component concentration and control method

Abstract

The application discloses a mixed working medium throttling refrigeration system with active regulation of component concentration and a control method, and relates to the field of refrigeration and low-temperature technology. The system comprises a compressor, a condenser, a regenerator, a throttling valve, an evaporator, a gas-liquid separator and low / high boiling point component storage tanks, and realizes component regulation and pressure relief protection through first, second and third electromagnetic valves. The control method is based on the current optimal cycle concentration corresponding to the ambient temperature and the evaporation temperature, the predicted ambient temperature, and the preset deviation value to cooperatively control the three electromagnetic valves: when the predicted ambient temperature change trend is consistent with the optimal concentration corresponding temperature and the measured temperature or the evaporation temperature exceeds the deviation range, the corresponding electromagnetic valve is triggered to open to compensate the components; when the temperature returns to the target value or exceeds the predicted temperature, all the electromagnetic valves are closed to terminate the compensation; and when the compressor exhaust pressure is out of limit, the first electromagnetic valve is forced to open to release pressure. The application eliminates the hysteresis of the traditional feedback control through the predicted temperature forward control.

Description

Technical Field

[0001] This invention relates to the field of refrigeration and cryogenic technology, and in particular to a mixed working fluid throttling refrigeration system and control method with active component concentration regulation. Background Technology

[0002] In the field of cryogenic refrigeration, mixed-refrigerant throttling refrigeration technology offers advantages over other refrigeration methods, including high efficiency, flexibility, and system simplification. Currently, mixed-refrigerant throttling refrigeration technology is widely used in natural gas liquefaction, and is also rapidly developing in areas such as cryogenic biomaterial storage, cryogenic medical applications, and cryogenic freeze-drying. The refrigerant ratio in a mixed-refrigerant throttling refrigeration system is designed based on anticipated operating conditions. However, actual operating conditions do not remain consistent with the predicted design conditions. When actual operating conditions deviate significantly from the design conditions, it will severely impact the system's operating efficiency. Current component adjustment systems for mixed-refrigerant throttling refrigeration systems still have certain shortcomings.

[0003] like Figure 1 As shown, a mixed refrigerant throttling refrigeration system is disclosed in the prior art. This system includes a compressor, a condenser, a regenerator, a capillary tube, an evaporator, a receiver equipped with a liquid level sensor, four solenoid valves, and four first check valves. Specifically, the system has branches leading from the compressor and condenser, and from the regenerator and capillary tube, to the receiver. This design aims to reduce the discharge pressure during initial system startup. Furthermore, it utilizes the gas-liquid separation characteristic of the two fluids entering the receiver (separating refrigerant vapor rich in low-boiling-point components or refrigerant liquid rich in high-boiling-point components), and by controlling the return of the gas or liquid in the receiver to the refrigeration cycle, it aims to regulate the concentration of refrigerant components in the circulation.

[0004] However, the aforementioned existing technologies have significant limitations in achieving component regulation. Their component regulation essentially relies on the pressure difference between the receiver and the connecting pipeline to drive the working fluid flow. Although four first check valves are installed in the system, their function is limited to preventing reverse flow of the working fluid and they cannot actively establish or maintain a pressure difference. More importantly, all four inlets and outlets of the receiver are located on the high-pressure side of the mixed working fluid throttling refrigeration system (i.e., before the capillary tube), resulting in a relatively small pressure difference between the receiver and its connecting pipeline. When the system operates until the pressure in the receiver and the pipeline tends to balance, the pressure difference driving the working fluid flow disappears, and the working fluid exchange process stops, thus preventing the system from continuously and effectively achieving the predicted component adjustment effect. Summary of the Invention

[0005] The purpose of this invention is to provide a mixed working fluid throttling refrigeration system and control method with active component concentration regulation, aiming to solve or improve at least one of the above-mentioned technical problems.

[0006] To achieve the above objectives, the present invention provides the following solution: The mixed working fluid throttling refrigeration system with active component concentration regulation includes: a compressor, a condenser, a regenerator, a throttling valve, an evaporator, a first solenoid valve, a gas-liquid separator, a low-boiling-point component storage tank, a high-boiling-point component storage tank, a second solenoid valve, and a third solenoid valve. The compressor outlet is connected to the condenser hot flow side inlet. The condenser hot flow side outlet is divided into two paths: one path is connected to the gas-liquid separator inlet via the first solenoid valve, and the other path is connected to the regenerator hot flow side inlet. The regenerator hot flow side outlet is connected to the evaporator cold flow side inlet via a throttling valve. The upper gas phase outlet of the gas-liquid separator is connected to the inlet of the low-boiling-point component storage tank, and the lower liquid phase outlet is connected to the inlet of the high-boiling-point component storage tank. The outlet of the low-boiling-point component storage tank is connected to the cold flow side outlet of the evaporator via a second solenoid valve, and then connected to the cold flow side inlet of the regenerator. The high-boiling-point component storage tank is connected to the cold flow side outlet of the regenerator via a third solenoid valve, and the third solenoid valve and the cold flow side outlet of the regenerator are connected to the inlet of the compressor.

[0007] Furthermore, pressure sensors are installed at the compressor inlet and outlet; temperature sensors are installed at the condenser cold flow inlet and the evaporator hot flow outlet; all sensors are connected to the input terminal of the control module.

[0008] Furthermore, the output of the control module is connected to the first solenoid valve, the second solenoid valve, and the third solenoid valve.

[0009] A control method for the above-mentioned system is provided, comprising: Before starting operation, the first, second, and third solenoid valves are all closed; After starting operation, the control module receives the compressor outlet pressure p1, the current ambient temperature T1 at the condenser cold flow side inlet, and the evaporation temperature Te1 at the evaporator hot flow side outlet. Based on the ambient temperature T0 corresponding to the current optimal circulating concentration and its deviation value ΔT0, the evaporation temperature Te0 corresponding to the predicted optimal circulating concentration and its deviation value ΔTe0, and combined with the dynamic relationship between the predicted ambient temperature T2 and the current measured ambient temperature T1, the first solenoid valve, the second solenoid valve, and the third solenoid valve are controlled in a coordinated manner.

[0010] Furthermore, based on the ambient temperature T0 corresponding to the current optimal circulating concentration and its deviation ΔT0, the evaporation temperature Te0 corresponding to the predicted optimal circulating concentration and its deviation ΔTe0, and combined with the dynamic relationship between the predicted ambient temperature T2 and the current ambient temperature T1, the first solenoid valve, the second solenoid valve, and the third solenoid valve are controlled in a coordinated manner, including: Based on the consistency of the predicted ambient temperature T2 with the optimal concentration corresponding temperature T0, the corresponding solenoid valve is triggered to open to perform component compensation when the ambient temperature or evaporation temperature exceeds the preset deviation range. When the current ambient temperature T1 exceeds the predicted ambient temperature T2 or returns to the optimal circulating concentration corresponding temperature T0, all solenoid valves are closed to terminate the compensation.

[0011] Furthermore, based on the consistency of the changing trends between the predicted ambient temperature T2 and the temperature T0 corresponding to the optimal concentration, the following judgments are made: If the predicted change in ambient temperature is inconsistent with the change in ambient temperature corresponding to the optimal circulating concentration, then the first solenoid valve, the second solenoid valve, and the third solenoid valve shall be closed.

[0012] Furthermore, when the ambient temperature or evaporation temperature exceeds a preset deviation range, the corresponding solenoid valve is triggered to open in order to perform component compensation. If the predicted change in ambient temperature is consistent with the change in ambient temperature corresponding to the optimal circulating concentration, and when the ambient temperature is lower than T0-ΔT, control the first and third solenoid valves to close and the second solenoid valve to open. When the current ambient temperature T1 is higher than T0+ΔT0, the first and second solenoid valves are closed, and the third solenoid valve is opened. When the evaporation temperature Te1 is lower than Te0-ΔTe0, the first and third solenoid valves are closed, and the second solenoid valve is opened. When the evaporation temperature Te1 is higher than Te0+ΔTe0, the control module controls the first and second solenoid valves to close and the third solenoid valve to open.

[0013] Furthermore, it also includes: when the compressor discharge pressure p1 exceeds the set upper limit p1max, the first solenoid valve is forcibly opened for pressure relief protection until the pressure drops back to the lower limit p1min and then the component regulation control is restored.

[0014] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects: This invention discloses a mixed working fluid throttling refrigeration system and control method with active component concentration regulation. The system uses the pressure difference between refrigeration cycle pipelines to drive a non-azeotropic mixed refrigerant to achieve dynamic concentration regulation, so that the cycle ratio can be accurately matched to the real-time operating conditions and ensure the efficient operation of the system. By introducing predicted temperature for look-ahead control, the problem of regulation lag caused by relying solely on the current measured temperature is overcome, and continuous ineffective regulation caused by the rapid change of ambient temperature compared to the component adjustment response speed is avoided, thus achieving stable system operation and optimal resource utilization.

[0015] Under typical operating conditions with dynamic changes in ambient temperature, compared to control based solely on the current temperature, predictive temperature control reduced the average deviation of the evaporation temperature from the target value from 2.3℃ to 0.8℃ (a reduction of approximately 65.2%), and the maximum deviation from 4.0℃ to 1.4℃ (a reduction of approximately 65.0%), significantly improving the stability of the temperature field.

[0016] Predictive temperature control enables more targeted component adjustments, effectively reducing repeated start-stop cycles and over-adjustment of the solenoid valve. Under the same operating conditions, the cumulative effective opening time of the solenoid valve decreased from 34 min / h to 21 min / h (a decrease of approximately 38.2%), reducing mechanical wear and energy consumption.

[0017] After adopting predictive temperature control, the fluctuation range of compressor discharge pressure decreased from ±0.18MPa to ±0.09MPa, and the overall performance coefficient (COP) of the system increased from 0.93 to 1.03 (an increase of approximately 10.8%), enhancing the unit's ability to operate continuously and stably under varying operating conditions. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of the prior art in the background section; Figure 2 This is a schematic diagram of the active component concentration control system in this embodiment; Figure 3 This is a flowchart of the control method based on predicted temperature in this embodiment; Figure 4 This is a schematic diagram of the component control system of the single-stage compression mixed working fluid throttling single-stage separation cycle refrigeration system in this embodiment; Reference numerals: 101-Compressor; 102-Condenser; 103-Regenerator; 104-Throttle valve; 105-Evaporator; 106-First solenoid valve; 107-Gas-liquid separator; 108-Low-boiling-point component storage tank; 109-High-boiling-point component storage tank; 110-Second solenoid valve; 111-Third solenoid valve; 112-Compressor; 113-Condenser; 114-High-temperature regenerator; 115-Gas-liquid separator; 116-Fourth solenoid valve; 117-Low-boiling-point component storage tank; 118-Fifth solenoid valve; 119-Sixth solenoid valve; 120-High-boiling-point component storage tank; 121-Seventh solenoid valve; 122-Throttle valve; 123-Medium-temperature regenerator; 124-Low-temperature regenerator; 125-Throttle valve; 126-Evaporator. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The purpose of this invention is to provide a mixed working fluid throttling refrigeration system and control method with active component concentration regulation, aiming to solve or improve at least one of the above-mentioned technical problems.

[0022] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] like Figure 2 As shown, the present invention provides a mixed working fluid throttling refrigeration system with active component concentration regulation, including: compressor 101, condenser 102, regenerator 103, throttling valve 104, evaporator 105, first solenoid valve 106, gas-liquid separator 107, low-boiling-point component storage tank 108, high-boiling-point component storage tank 109, second solenoid valve 110 and third solenoid valve 111; The outlet of compressor 101 is connected to the hot flow side inlet of condenser 102. The hot flow side outlet of condenser 102 is divided into two paths: one path is connected to the inlet of gas-liquid separator 107 via first solenoid valve 106, and the other path is connected to the hot flow side inlet of regenerator 103. The hot flow side outlet of regenerator 103 is connected to the cold flow side inlet of evaporator 105 via throttle valve 104. The upper gas phase outlet of the gas-liquid separator 107 is connected to the inlet of the low-boiling-point component storage tank 108, and the lower liquid phase outlet is connected to the inlet of the high-boiling-point component storage tank 109. The outlet of the low-boiling-point component storage tank 108 is connected to the cold flow side outlet of the evaporator 105 via the second solenoid valve 110, and then connected to the cold flow side inlet of the regenerator 103. The high-boiling-point component storage tank 109 is connected to the cold flow side outlet of the regenerator 103 via the third solenoid valve 111, and the third solenoid valve 111 and the cold flow side outlet of the regenerator 103 are connected to the inlet of the compressor 101.

[0024] Pressure sensors are installed at the inlet and outlet of compressor 101; temperature sensors are installed at the cold flow inlet of condenser 102 and the hot flow outlet of evaporator 105; all sensors are connected to the input terminal of the control module. The output of the control module is connected to the first solenoid valve 106, the second solenoid valve 110, and the third solenoid valve 111. The control module receives sensor signals and controls the drive mechanisms of the three solenoid valves to control the on / off states of the three solenoid valves.

[0025] It should be noted that, Figure 2 The system shown is a basic embodiment of the present invention, focusing on defining the basic composition and connection relationships of the active component concentration control system. Figure 2 In the basic embodiment shown, the first solenoid valve 106, the gas-liquid separator 107, the low-boiling-point component storage tank 108, the high-boiling-point component storage tank 109, the second solenoid valve 110, and the third solenoid valve 111 together form a component separation and reinjection channel. Its innovation lies in using a portion of the mixed working fluid drawn from the high-pressure side for gas-liquid separation, and temporarily storing the separated low-boiling-point-rich component and high-boiling-point-rich component respectively, so that the control module can actively select to compensate the main circulation with different boiling-point components according to the operating conditions.

[0026] like Figure 3 As shown, in one embodiment, a control method based on the above system is provided, comprising: Step 1: Before starting operation, the first solenoid valve 106, the second solenoid valve 110, and the third solenoid valve 111 are all closed; Step 2: After starting operation, the control module receives the pressure p1 at the outlet of compressor 101, the current ambient temperature T1 at the cold flow side inlet of condenser 102, and the evaporation temperature Te1 at the hot flow side outlet of evaporator 105. Step 3: Based on the preset optimal circulating concentration corresponding to the ambient temperature and evaporation temperature, and combined with the preset deviation value, control the opening and closing of the first solenoid valve 106, the second solenoid valve 110 and the third solenoid valve 111.

[0027] Specifically, the preset optimal circulating concentration corresponding to the ambient temperature and evaporation temperature refers to a set of operating parameters obtained in advance through experimental calibration, simulation calculation, or joint optimization of experiments and simulations, rather than arbitrarily given fixed values ​​during operation. The control module pre-stores the correspondence between ambient temperature, evaporation temperature, exhaust pressure, and optimal circulating concentration, and performs lookup, interpolation, or fitting calculations based on sensor-collected values ​​and predicted ambient temperature during operation to determine the current component control direction to be adopted.

[0028] Obtain the ambient temperature T0 corresponding to the current optimal circulating concentration, and set the deviation value to ΔT0; The ambient temperature T0 corresponding to the current optimal circulating concentration is obtained by the control module from a pre-established operating condition-component calibration database. This calibration database can be established before the system leaves the factory through performance tests or thermodynamic simulations under different ambient temperatures, different evaporation temperatures, and different load conditions. The optimal circulating concentration and its corresponding ambient temperature under each operating condition are determined using the system performance coefficient, evaporation temperature stability, and compressor discharge pressure safety margin as evaluation indicators. The deviation value ΔT0 is set according to the temperature sensor measurement error, component adjustment response time, and allowable temperature fluctuation range to form a control dead zone.

[0029] Based on the current ambient temperature T1, the historical ambient temperature change sequence, the evaporation temperature Te1, and the pressure p1, the ambient temperature for the future period is predicted to be T2. During prediction, the control module preferably uses the continuously collected ambient temperature sequence within the most recent preset time window as a basis, and combines the evaporation temperature Te1 and the compressor outlet pressure p1 to correct the system load change trend. The prediction algorithm can use any one of the following: weighted moving average, exponential smoothing, linear regression, time series fitting, or Kalman filtering, or a combination of the above methods. The prediction time length is preferably matched with the response time of component compensation from the solenoid valve action to the identifiable change in evaporation temperature, thereby obtaining the ambient temperature T2 for the future time period.

[0030] The control module establishes a future ambient temperature prediction model based on the current ambient temperature T1, the ambient temperature change sequence within the most recent preset time window, the evaporation temperature Te1, and the compressor outlet pressure p1, and obtains the predicted ambient temperature T2 for a certain future time period.

[0031] If the predicted change in ambient temperature is inconsistent with the change in ambient temperature corresponding to the optimal circulating concentration, then the first solenoid valve 106, the second solenoid valve 110 and the third solenoid valve 111 are closed. The expressions that change consistently are: T1-T0>0 and T2-T0>0; or T1-T0<0 and T2-T0<0.

[0032] If the predicted change in ambient temperature is consistent with the change in ambient temperature corresponding to the optimal circulating concentration, and when the ambient temperature is lower than T0-ΔT, the first solenoid valve 106 and the third solenoid valve 111 are closed, and the second solenoid valve 110 is opened. The non-azeotropic refrigerant vapor rich in low-boiling-point components in the low-boiling-point component storage tank 108 enters the refrigeration system, and the circulating concentration of low-boiling-point components in the refrigeration system increases. Until the current ambient temperature T1 is lower than the predicted ambient temperature T2 or higher than the ambient temperature T0 corresponding to the current circulating concentration, the first solenoid valve 106, the second solenoid valve 110, and the third solenoid valve 111 are closed.

[0033] When the current ambient temperature T1 is higher than T0+ΔT0, the first solenoid valve 106 and the second solenoid valve 110 are closed, and the third solenoid valve 111 is opened. The non-azeotropic refrigerant liquid rich in high-boiling-point components in the high-boiling-point component storage tank 109 enters the refrigeration system, and the circulating concentration of high-boiling-point components in the refrigeration system increases. Until the current ambient temperature T1 is higher than the predicted ambient temperature T2 or lower than the ambient temperature T0 corresponding to the current circulating concentration, the first solenoid valve 106, the second solenoid valve 110 and the third solenoid valve 111 are closed. The evaporation temperature corresponding to the predicted optimal circulating concentration is Te0, and the deviation value is set to ΔTe0. The evaporation temperature Te0 corresponding to the predicted optimal circulating concentration is obtained from a pre-established correspondence between evaporation temperature and circulating concentration. This correspondence can be obtained through experimental calibration or simulation optimization and stored in the control module. The control module performs table lookup, interpolation, or fitting calculations based on the predicted ambient temperature T2, the current evaporation temperature Te1, and the pressure p1 to obtain Te0 that matches the predicted operating conditions. The deviation value ΔTe0 is set according to the accuracy of the evaporation temperature sensor, the allowable fluctuation range of the target refrigeration temperature, and the component adjustment response characteristics to avoid frequent start-stop of the solenoid valve due to small fluctuations.

[0034] When the evaporation temperature Te1 is lower than Te0-ΔTe0, the first solenoid valve 106 and the third solenoid valve 111 are closed, and the second solenoid valve 110 is opened. The non-azeotropic refrigerant vapor rich in low-boiling components from the low-boiling component storage tank 108 enters the refrigeration system, increasing the circulating concentration of low-boiling components in the refrigeration system. This continues until the current ambient temperature T1 is lower than... If the predicted ambient temperature T2 is higher than the ambient temperature T0 corresponding to the current circulating concentration, close the first solenoid valve 106, the second solenoid valve 110, and the third solenoid valve 111.

[0035] When the evaporation temperature Te1 is higher than Te0+ΔTe0, the control module controls the first solenoid valve 106 and the second solenoid valve 110 to close, and the third solenoid valve 111 to open. The non-azeotropic mixed refrigerant liquid rich in high-boiling-point components in the high-boiling-point component storage tank 109 enters the refrigeration system, and the circulating concentration of high-boiling-point components in the refrigeration system increases. Until the current ambient temperature T1 is higher than the predicted ambient temperature T2 or lower than the ambient temperature T0 corresponding to the current circulating concentration, the first solenoid valve 106, the second solenoid valve 110 and the third solenoid valve 111 are closed.

[0036] When the compressor outlet pressure p1 exceeds the set maximum compressor discharge pressure p1max, the first solenoid valve 106 is opened and the second solenoid valve 110 and the third solenoid valve 111 are closed. The high-temperature and high-pressure non-azeotropic mixed refrigerant vapor at the compressor outlet of 101 enters the gas-liquid separator 107. When the compressor outlet pressure p1 is lower than the set minimum compressor discharge pressure p1min, the first solenoid valve 106 is closed and the second solenoid valve 110 and the third solenoid valve 111 are opened.

[0037] The predicted ambient temperature T2 for a future time period mentioned above is not a simple repetition of the current ambient temperature T1, but rather a representation of the target environmental conditions at the moment when the component adjustment action actually takes effect. Because low-boiling-point or high-boiling-point components, after being released from their respective storage tanks, still need to undergo a process of valve opening, working fluid flowing into the main loop, heat exchange through the regenerator, and finally being reflected in the evaporator's operating conditions, the impact of component adjustment on the system temperature field has an inherent response lag. This response time is typically 5–15 minutes, and can be further extended in scenarios with rapid partial load fluctuations.

[0038] The environmental temperature change sequence within the most recent preset time window can be formed by continuous sampling values ​​from existing environmental temperature measuring points, without the need for additional measurement hardware; the prediction time is preferably matched with the component adjustment response duration. The above prediction model can be implemented using methods such as weighted moving average, linear regression, time series fitting, or Kalman filtering. Its core is not limited to a specific algorithm, but rather lies in outputting a forward-looking temperature quantity that matches the component adjustment response duration.

[0039] In practice, when T1, T2 and T0 are on the same side, it indicates that the current operating condition and the predicted operating condition are both deviating in the same direction from the operating condition corresponding to the optimal concentration. Only then will the control module allow the execution of compensation for low-boiling-point components or high-boiling-point components. When T1 and T2 are on different sides relative to T0, it indicates that the change in ambient temperature may cross the target operating condition. In this case, all solenoid valves are closed to avoid overcompensation.

[0040] The limitation of component adjustment strategies based solely on the current temperature (T2) for predictive ambient temperature correction is that if adjustment decisions are made only based on the current ambient temperature (T1), the control system is essentially using the "current operating condition" to drive the "component state that will be completed several minutes later." When the ambient temperature continues to change, the actual cyclic component often lags behind the true operating condition, easily causing the second solenoid valve 110 or the third solenoid valve 111 to operate continuously. However, the system component still cannot match the current ambient temperature in time, leading to repeated corrections, over-corrections, or under-corrections. By introducing the predicted ambient temperature (T2), the control objective changes from matching the current ambient operating condition to matching the predicted operating condition when the component adjustment is completed, thus making component regulation more forward-looking.

[0041] Applying the predicted ambient temperature T2 to the control of the working fluid composition has several advantages for temperature regulation: it enables the compensation direction and magnitude of low-boiling-point or high-boiling-point components to more closely approximate future actual needs, reducing tracking lag, overshoot, and fluctuations in evaporation temperature, and improving the control accuracy of the target evaporation temperature. For working fluid component adjustment, it reduces ineffective separation and reinjection, shortens the continuous operation time of solenoid valves, improves component adjustment efficiency, and avoids the phenomenon of "the environment changing again just as the adjustment is in place" caused by adjustment lag. For the unit itself, it helps reduce the mechanical shock caused by compressor exhaust pressure fluctuations and frequent start-stop adjustments, reduces the burden on the regenerator, throttle valve, and separation tank under unsteady-state conditions, thereby improving the overall operational stability, reliability, and lifespan of key components.

[0042] like Figure 4 As shown, in this embodiment, the high-temperature, high-pressure mixed working fluid discharged from the compressor 112 first enters the condenser 113 for exothermic condensation, and then exchanges heat with the low-temperature reflux working fluid through the high-temperature regenerator 114. A portion of the high-pressure working fluid enters the gas-liquid separator 115 through the fourth solenoid valve 116 for primary separation. The separated gas phase working fluid, rich in low-boiling-point components, enters the low-boiling-point component storage tank 117, and the liquid phase working fluid, rich in high-boiling-point components, enters the high-boiling-point component storage tank 120. When the control module determines that the circulating concentration of low-boiling-point components needs to be increased, it controls the fifth solenoid valve 118 to open, allowing the low-boiling-point components to enter the main circulation; when the circulating concentration of high-boiling-point components needs to be increased, it controls the sixth solenoid valve 119 or the seventh solenoid valve 121 to open according to the set logic, allowing the high-boiling-point components to flow back to the main circulation. The main circulation working fluid sequentially passes through the medium-temperature regenerator 123, the low-temperature regenerator 124, the throttling valve 125, and the evaporator 126 to complete the throttling refrigeration process. Through the above structure, Figure 4 The embodiments enable the separation, temporary storage, and on-demand compensation of components with different boiling points in a single-stage separation cycle, and are compatible with... Figure 3 The predicted temperature control method shown is used in conjunction with this method to improve the matching between the circulating components and the operating load under varying operating conditions.

[0043] Figure 4 In the middle, the high-temperature regenerator 114, the medium-temperature regenerator 123 and the low-temperature regenerator 124 successively undertake the heat exchange function of different temperature zones. The gas-liquid separator 115, together with the low-boiling-point component storage tank 117 and the high-boiling-point component storage tank 120, constitute the component separation and temporary storage unit. The fourth solenoid valve 116, the fifth solenoid valve 118, the sixth solenoid valve 119 and the seventh solenoid valve 121 are used to control the timing of the separation working fluid entering the storage tank or returning to the main circulation.

[0044] therefore, Figure 4 and Figure 2 The main difference lies in the complexity of the cyclic application objects and the reheating process. Figure 2This is used to summarize the general structure of active component concentration control systems. Figure 4 This is used to illustrate the specific arrangement of this general structure in a single-stage compression mixed working fluid throttling first-stage separation cycle. Figure 4 In the extended embodiment shown, the fourth solenoid valve 116, the gas-liquid separator 115, the low-boiling-point component storage tank 117, the high-boiling-point component storage tank 120, the fifth solenoid valve 118, the sixth solenoid valve 119, and the seventh solenoid valve 121 together constitute a component active control unit suitable for a primary separation cycle. This embodiment is relative to... Figure 2 Low-temperature throttling circulation components such as high-temperature regenerator 114, medium-temperature regenerator 123, and low-temperature regenerator 124 have been added to adapt to the heat exchange requirements of different temperature zones during low-temperature refrigeration. However, the core mechanisms of component separation, temporary storage, and on-demand compensation are different from those of the previous system. Figure 2 The two together constitute the basic and extended embodiments of the present invention, both serving the same technical purpose, namely, that the concentration of the mixed working fluid in circulation can be actively adjusted according to changes in ambient temperature, evaporation temperature, and predicted operating conditions.

[0045] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0046] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A mixed working fluid throttling refrigeration system with actively regulated component concentration, characterized in that, include: Compressor (101), condenser (102), regenerator (103), throttle valve (104), evaporator (105), first solenoid valve (106), gas-liquid separator (107), low-boiling-point component storage tank (108), high-boiling-point component storage tank (109), second solenoid valve (110) and third solenoid valve (111). The outlet of the compressor (101) is connected to the hot flow side inlet of the condenser (102). The hot flow side outlet of the condenser (102) is divided into two paths: one path is connected to the inlet of the gas-liquid separator (107) through the first solenoid valve (106), and the other path is connected to the hot flow side inlet of the regenerator (103). The hot flow side outlet of the regenerator (103) is connected to the cold flow side inlet of the evaporator (105) through the throttle valve (104). The upper gas phase outlet of the gas-liquid separator (107) is connected to the inlet of the low-boiling-point component storage tank (108), and the lower liquid phase outlet is connected to the inlet of the high-boiling-point component storage tank (109). The outlet of the low-boiling-point component storage tank (108) is connected to the cold flow side outlet of the evaporator (105) via the second solenoid valve (110), and then connected to the cold flow side inlet of the regenerator (103). The high-boiling-point component storage tank (109) is connected to the cold flow side outlet of the regenerator (103) via the third solenoid valve (111), and the third solenoid valve (111) and the cold flow side outlet of the regenerator (103) are connected to the inlet of the compressor (101).

2. The system according to claim 1, characterized in that, Pressure sensors are installed at the inlet and outlet of the compressor (101); temperature sensors are installed at the cold flow inlet of the condenser (102) and the hot flow outlet of the evaporator (105); all sensors are connected to the input terminal of the control module.

3. The system according to claim 1, characterized in that, The output of the control module is connected to the first solenoid valve (106), the second solenoid valve (110), and the third solenoid valve (111).

4. A control method based on the system according to any one of claims 1-3, characterized in that, include: Before operation begins, the first solenoid valve (106), the second solenoid valve (110), and the third solenoid valve (111) are all closed; After starting operation, the control module receives the pressure p1 at the outlet of the compressor (101), the current ambient temperature T1 at the cold flow side inlet of the condenser (102), and the evaporation temperature Te1 at the hot flow side outlet of the evaporator (105); Based on the ambient temperature T0 corresponding to the current optimal circulating concentration and its deviation value ΔT0, the evaporation temperature Te0 corresponding to the predicted optimal circulating concentration and its deviation value ΔTe0, and combined with the dynamic relationship between the predicted ambient temperature T2 and the current measured ambient temperature T1, the first solenoid valve (106), the second solenoid valve (110) and the third solenoid valve (111) are controlled in a coordinated manner.

5. The control method according to claim 4, characterized in that, The method of coordinating the control of the first solenoid valve (106), the second solenoid valve (110), and the third solenoid valve (111) based on the ambient temperature T0 corresponding to the current optimal circulating concentration and its deviation value ΔT0, the evaporation temperature Te0 corresponding to the predicted optimal circulating concentration and its deviation value ΔTe0, and the dynamic relationship between the predicted ambient temperature T2 and the current ambient temperature T1, includes: Based on the consistency of the predicted ambient temperature T2 with the optimal concentration corresponding temperature T0, the corresponding solenoid valve is triggered to open to perform component compensation when the ambient temperature or evaporation temperature exceeds the preset deviation range. When the current ambient temperature T1 exceeds the predicted ambient temperature T2 or returns to the optimal circulating concentration corresponding temperature T0, all solenoid valves are closed to terminate the compensation.

6. The control method according to claim 5, characterized in that, The judgment based on the consistency of the changing trends of the predicted ambient temperature T2 and the temperature T0 corresponding to the optimal concentration includes: If the predicted change in ambient temperature is inconsistent with the change in ambient temperature corresponding to the optimal circulating concentration, then the first solenoid valve (106), the second solenoid valve (110), and the third solenoid valve (111) are closed.

7. The control method according to claim 5, characterized in that, When the ambient temperature or evaporation temperature exceeds a preset deviation range, the corresponding solenoid valve is triggered to open in order to perform component compensation. If the predicted change in ambient temperature is consistent with the change in ambient temperature corresponding to the optimal circulating concentration, and when the ambient temperature is lower than T0-ΔT, control the first solenoid valve (106) and the third solenoid valve (111) to close, and the second solenoid valve (110) to open. When the current ambient temperature T1 is higher than T0+ΔT0, the first solenoid valve (106) and the second solenoid valve (110) are closed, and the third solenoid valve (111) is opened; When the evaporation temperature Te1 is lower than Te0-ΔTe0, the first solenoid valve (106) and the third solenoid valve (111) are closed, and the second solenoid valve (110) is opened; When the evaporation temperature Te1 is higher than Te0+ΔTe0, the control module controls the first solenoid valve (106) and the second solenoid valve (110) to close, and the third solenoid valve (111) to open.

8. The control method according to claim 4, characterized in that, Also includes: When the compressor discharge pressure p1 exceeds the set upper limit p1max, the first solenoid valve (106) is forcibly opened for pressure relief protection until the pressure drops back to the lower limit p1min and then the component regulation control is restored.

Images