Integrated phase change cold storage system and method for vacuum cooling system

Abstract

The invention discloses an integrated phase change cold storage system and method for a vacuum cooling system. The system comprises a vacuum pump, a vacuum chamber, a water catcher, a circulating pump, a refrigeration main machine and a cold storage box body with a built-in sealed ice pipe unit which are connected through pipelines and two three-way valves. The method comprises three modes: a cold storage mode; a cooling mode; and in the cooling and cold supplementing mode, the occurrence time of surplus cold energy is judged based on the water catcher outlet temperature (T2), automatic triggering is conducted, then the opening degree of a three-way valve is dynamically adjusted according to different intervals where the T2 value is located, and flow is distributed to achieve cooperation of cooling and cold supplementing. Through phase change latent heat cold storage and intelligent control, the problems that a traditional scheme is large in size, high in cost and incapable of achieving continuous production are solved, and miniaturization, low cost and efficient automatic operation of the system are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of industrial refrigeration and energy saving, and in particular to a system and method for efficiently dealing with peak load and continuous production by integrating a phase change cold storage unit in a single refrigerant circuit through two three-way valves and realizing three operating modes through intelligent control based on temperature feedback. BACKGROUND

[0002] Vacuum cooling is a key rapid cooling technology in the food, chemical and other industries, which has the advantages of fast cooling speed, uniform cooling temperature, hygiene and energy saving, etc. However, it has inherent characteristics that the evaporation load is huge at the initial stage of cooling, forming a very high instantaneous peak load, and the evaporation load drops sharply at the end of cooling, which leads to the system having to configure the refrigeration host and water catcher according to the peak load, resulting in huge equipment investment, high energy consumption and low operating efficiency most of the time.

[0003] In the prior art, it is a common scheme to use ethylene glycol solution for sensible heat storage, but this scheme has inherent defects: the ethylene glycol storage density is extremely low, requiring a large storage tank, and the equipment and medium costs are high; during the cooling process, the temperature of ethylene glycol in the storage tank continues to rise, resulting in unstable outlet temperature and affecting cooling efficiency; in addition, due to the contradiction between the storage process and the cooling process, continuous production cannot be efficiently stored, thereby affecting the rhythm of continuous production. Therefore, there is an urgent need for an intelligent solution that has high storage density, stable operation, can cope with peak load, and can realize the connection of continuous production, storage and cooling in a single circuit architecture. SUMMARY

[0004] The purpose of the present application is to overcome the shortcomings of the prior art and provide an integrated phase change cold storage system and method. The system integrates a phase change cold storage unit in a single circuit through two three-way valves, intelligently identifies the load state, and automatically and smoothly switches between three operating modes seamlessly, not only greatly improving the storage density, reducing the system size and cost, but also fully utilizing the system characteristics, efficiently dealing with peak load, and providing a continuous and stable low-temperature cold source for vacuum cooling, realizing continuous, efficient and energy-saving operation.

[0005] To achieve the above purpose, the technical scheme adopted by the present application is as follows: An integrated phase change cold storage system for a vacuum cooling system, comprising: a vacuum cooling unit comprising a vacuum chamber and a water catcher; a vacuum pumping unit comprising a vacuum pump connected to the vacuum chamber; a refrigeration unit comprising a refrigeration host; a fluid delivery unit comprising a circulating pump; The integrated phase change cold storage device comprises a sealed and heat-insulated cold storage box, one or more groups of sealed phase change units internally encapsulating water and provided with fins, and a glycol water solution filled in the box and immersed in the phase change units. The pipeline switching unit comprises a first three-way valve and a second three-way valve and a mixing point; the first three-way valve is an electrically adjusted three-way valve. The signal detection unit comprises a temperature sensor for detecting temperature, wherein a first temperature sensor (T2) is arranged on the outlet pipeline of the water catcher. The control unit is electrically connected with the refrigeration host, the circulating pump, the vacuum pump, the first and second three-way valves, and the temperature sensor. The vacuum chamber, the water catcher, the circulating pump, the cold storage box, and the refrigeration host are connected through pipelines and the first and second three-way valves to form a complete carrier refrigerant circulation loop.

[0006] The connecting pipeline comprises three connecting paths, wherein: a. The cold storage mode loop structure: the outlet of the circulating pump is connected with the inlet of the first three-way valve, the A1 outlet of the first three-way valve is connected with the inlet of the evaporator of the refrigeration host through a pipeline, the outlet of the evaporator of the refrigeration host is connected with the inlet of the cold storage box, the outlet of the cold storage box is connected with the inlet of the second three-way valve, and one outlet of the second three-way valve is connected with the mixing point through a pipeline. b. The cooling mode loop structure: the outlet of the water catcher is connected with the inlet of the circulating pump, the outlet of the circulating pump is connected with the inlet of the first three-way valve, the outlet of the first three-way valve is connected with the inlet of the evaporator of the refrigeration host through a pipeline, the outlet of the evaporator of the refrigeration host is connected with the inlet of the cold storage box, the outlet of the cold storage box is connected with the inlet of the second three-way valve, and the outlet of the second three-way valve is connected with the inlet of the water catcher through a pipeline. c. The cooling + cold supplement mode loop structure: c1. The first branch: the outlet of the circulating pump is connected with the inlet of the first three-way valve, the A1 outlet of the first three-way valve is connected with the inlet of the evaporator of the refrigeration host through a pipeline, the outlet of the evaporator of the refrigeration host is connected with the inlet of the cold storage box, the outlet of the cold storage box is connected with the inlet of the second three-way valve, and one outlet of the second three-way valve is connected with the mixing point through a pipeline. c2. The second branch: the outlet of the circulating pump is connected with the inlet of the first three-way valve, the A2 outlet of the first three-way valve is directly connected with the mixing point through a pipeline; the total loop: the outlet of the mixing point is connected with the inlet of the water catcher through a pipeline, the outlet of the water catcher is connected with the inlet of the circulating pump, and finally a closed loop is formed.

[0007] Further, the sealed phase change unit is composed of a sealed pipe internally encapsulating phase change material water, and the outer surface of the sealed pipe is provided with fins.

[0008] A control method for the aforementioned integrated phase change cold storage system, the method comprising three operating modes: Cold storage mode: During system idle periods, the first and second three-way valves are controlled to switch flow channels, allowing the refrigerant to bypass the water trap and form a circulation loop of "circulation pump → first three-way valve → refrigeration unit → cold storage box → second three-way valve → circulation pump"; the refrigeration unit is controlled to freeze the water in the sealed phase change unit; and the cold storage box outlet temperature and refrigeration unit load indication parameters are monitored to intelligently determine the cold storage completion status and automatically shut down.

[0009] Cooling mode: In the initial stage of the vacuum cooling process, the first and second three-way valves are controlled to switch the flow channels, so that all the refrigerant flows through the loop of "water trap → circulating pump → first three-way valve → refrigeration unit → cold storage box → second three-way valve → water trap"; the refrigeration unit operates according to the load demand to cool the refrigerant to the target temperature.

[0010] Cooling + supplemental cooling mode: During the vacuum cooling process, the control unit uses the temperature value of the first temperature sensor (T2) installed on the outlet pipe of the water catcher as the basis for judgment; when T2 is lower than the first preset threshold, it indicates that the heat load of the water catcher is lower than the cooling capacity of the refrigeration unit, and excess cooling capacity appears, and the system automatically enters this mode. Upon entering this mode, the control unit executes a preset segmented control strategy based on the different temperature ranges of the temperature value of the first temperature sensor (T2), dynamically adjusting the opening of the first three-way valve to divide the refrigerant flowing from the circulating pump into a first branch and a second branch. The first branch flows through the refrigeration unit and the cold storage tank to replenish the cold storage tank. The second branch bypasses the refrigeration unit and the cold storage tank. After the fluid from the first branch flows out of the cold storage tank, it mixes with the fluid from the second branch at the mixing point and is then supplied to the water trap. Beneficial effects

[0011] 1. Intelligent response to peak load: The phase change cold storage unit can instantly release a large amount of cold energy, which perfectly makes up for the insufficient power of the refrigeration unit in the initial stage of cooling, allowing the system to configure the refrigeration unit according to the average load rather than the peak load.

[0012] 2. Achieve efficient and continuous production: The innovative "cooling + supplemental cooling mode" and segmented control strategy utilize the surplus cooling capacity of the system in the middle and late stages of cooling to simultaneously supplement the cooling of the cold storage unit, completely solving the problem of cold load connection in multi-batch continuous production.

[0013] 3. High energy storage density and low overall cost: Utilizing the latent heat of water / ice phase change for cold storage, the energy storage density is more than 10 times that of sensible heat storage of ethylene glycol, significantly reducing equipment volume, media consumption, and equipment cost.

[0014] 4. The system has strong self-adaptive capabilities and is simple and reliable: Based on the closed-loop control strategy of temperature feedback, it can intelligently identify the system load status and automatically and smoothly switch between three working modes, accurately capture the timing of the occurrence of excess cooling capacity and maximize its utilization. Attached Figure Description

[0015] Figure 1 This is a schematic diagram illustrating the structural principle of the integrated phase change cold storage system described in this invention. Figure 2 This is a flowchart of the control method described in this invention; Figure 3 This is a schematic diagram of a cyclic process.

[0016] In the diagram: 1. Vacuum pump; 2. Vacuum chamber; 3. Water trap; 4. Circulation pump; 5. Cold storage tank; 6. Refrigeration unit; 7a. First three-way valve; 7b. Second three-way valve; 8. Mixing point (M) temperature sensor (T1, T2, T3) control unit.

[0017] The solid line represents the main flow path in cooling mode, the black dashed line represents the flow path in cold storage mode, and the dotted line represents the flow path for both cooling and supplemental cooling. Detailed Implementation

[0018] To enhance understanding of the present invention, the present invention will be further described in detail below with reference to embodiments and accompanying drawings. These embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention. Example

[0019] I. System Composition See Figure 1 The system includes: vacuum pump 1, vacuum chamber 2, water trap 3, circulation pump 4, cold storage box 5, refrigeration unit 6, first three-way valve 7a, second three-way valve 7b, mixing point M, temperature sensors (T1, T2, T3) and control unit 8.

[0020] The pipeline switching unit includes two three-way valves and one mixing point. Their connection relationship is as follows: The outlet of the circulating pump 4 is connected to the inlet of the first three-way valve 7a; One outlet A1 of the first three-way valve 7a is connected to the evaporator inlet of the refrigeration unit 6, and the other outlet A2 is connected to the mixing point M via a pipe. The evaporator outlet of the refrigeration unit 6 is connected to the inlet of the cold storage box 5; The outlet of the cold storage box 5 is connected to the inlet of the second three-way valve 7b; One outlet of the second three-way valve 7b is connected to the inlet of the circulating pump 4, and the other outlet is connected to the mixing point M; The outlet of the mixing point M is connected to the inlet pipe of the water trap 3; The outlet pipe of the water trap 3 is connected to the inlet of the circulating pump 4.

[0021] The first temperature sensor T2 is installed on the outlet pipe of the water catcher 3.

[0022] II. Implementation Process of Control Methods The control unit automatically controls the switching of the three-way valve and the operating status of the refrigeration unit based on temperature sensor signals. 1. Cold Storage Mode: Connect the first three-way valve 7a to port A1, and the second three-way valve 7b to the inlet of the circulating pump. Start the circulating pump 4 and the refrigeration unit 6. The refrigerant circulates and stores cold in the loop "circulating pump → 7aA1 → refrigeration unit → cold storage tank → 7b → circulating pump". The cold storage mode actively bypasses the water trap to reduce energy consumption and potential risks.

[0023] 2. Cooling Mode: Control the first three-way valve 7a to connect to port A1, and the second three-way valve 7b to connect to mixing point M. The refrigerant circulates and cools along the loop: "water trap → circulating pump → 7aA1 → refrigerator → cold storage tank → 7b → mixing point M → water trap". In the initial stage of vacuum cooling, the refrigerator operates at full load, and the cold storage tank releases the stored cold energy to meet the peak evaporation load in the initial stage of vacuum cooling.

[0024] 3. Cooling + Cooling Supplement Mode: Mode Trigger: During cooling mode operation, the controller continuously monitors the water trap outlet temperature T2. When T2 drops and stabilizes below the first preset threshold (e.g., 5°C), it is determined that excess cooling capacity has appeared, and the system automatically switches to this mode.

[0025] Segmented control: In the cooling + supplemental cooling mode, the chiller's cooling capacity is only partially surplus, and can only cool a portion of the refrigerant returning from the water trap to a suitable cooling temperature. Therefore, upon entering this mode, the controller adjusts the opening of the first three-way valve 7a to divert the flow according to the different temperature ranges of T2. First branch: 7aA1->Refrigeration unit->Cold storage box->7b->Mixing point M.

[0026] Second branch: 7aA2->Mixed point M.

[0027] See the cyclic flow path Figure 3 .

[0028] The specific control mode is: When T2 is in the first temperature range (e.g., between the second preset threshold and the first preset threshold): control the opening of the first three-way valve 7a so that a small portion of the flow (e.g., 5%-10%) goes to the cooling circuit (first branch) through A1, and most of the flow bypasses through A2 (second branch).

[0029] When T2 is in the second temperature range (e.g., between the third preset threshold and the second preset threshold): control the opening of the first three-way valve 7a so that a medium proportion of flow (e.g., 20%-30%) passes through A1 for cooling.

[0030] When T2 is below the third preset threshold (e.g., close to 0°C): control the opening of the first three-way valve 7a so that most of the flow (e.g., 40%-50%) goes through A1 for cooling, maximizing the use of surplus cooling capacity for supplemental cooling.

[0031] The second three-way valve 7b remains open to the mixing point M. The two fluids mix at the mixing point M and then enter the water trap.

[0032] III. Effects After applying this invention, a system that needs to handle a peak cooling capacity of 200kW only needs to be configured with a 100kW refrigeration unit, the volume of the cold storage unit is significantly reduced, continuous production of batches every 30 minutes can be achieved, and the overall energy consumption is significantly reduced.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An integrated phase change cold storage system for a vacuum cooling system, characterized in that, include: Vacuum chamber; Water trap; A vacuum pump is connected to the vacuum chamber; Refrigeration unit; Circulating pump; An integrated phase change cold storage device includes a sealed and insulated cold storage box, a sealed phase change unit disposed inside the box, and a refrigerant filled inside the box and immersed in the phase change unit. The pipeline switching device includes a first three-way valve and a second three-way valve; the first three-way valve is an electrically adjustable three-way valve. A temperature detection device, including a first temperature sensor disposed on the outlet pipe of the water catcher; The control unit is communicatively connected to the refrigeration unit, circulating pump, vacuum pump, pipeline switching device, and temperature detection device. Connect the vacuum chamber, water catcher, circulating pump, refrigeration unit, cold storage box and pipeline switching device in series to form a refrigerant circulation loop; The outlet of the circulating pump is connected to the inlet of the first three-way valve; one outlet of the first three-way valve is connected to the inlet of the evaporator of the refrigeration unit, and the other outlet is connected to a mixing point; The outlet of the evaporator of the refrigeration unit is connected to the inlet of the cold storage box. The outlet of the cold storage box is connected to the inlet of the second three-way valve; One outlet of the second three-way valve is connected to the inlet of the circulation pump, and the other outlet is connected to the mixing point; The outlet of the mixing point is connected to the inlet pipe of the water trap; The outlet pipe of the water catcher is connected to the inlet of the circulation pump; The control unit is configured to control the system to switch between three modes: cold storage mode, cooling mode, and cooling + supplemental cooling mode.

2. The integrated phase change cold storage system for a vacuum cooling system according to claim 1, characterized in that, The connecting pipeline includes three connection paths, among which: a. Cold storage mode loop structure: The outlet of the circulating pump is connected to the inlet of the first three-way valve, and the A1 outlet of the first three-way valve is connected to the inlet of the evaporator of the refrigeration unit through a pipeline; the outlet of the evaporator of the refrigeration unit is connected to the inlet of the cold storage box, and the outlet of the cold storage box is connected to the inlet of the second three-way valve; one outlet of the second three-way valve is connected to the inlet of the circulating pump through a pipeline. b. Cooling mode loop structure: The outlet of the water trap is connected to the inlet of the circulating pump, the outlet of the circulating pump is connected to the inlet of the first three-way valve, and the outlet of the first three-way valve is connected to the inlet of the evaporator of the refrigeration unit through a pipeline; the outlet of the evaporator of the refrigeration unit is connected to the inlet of the cold storage box, and the outlet of the cold storage box is connected to the inlet of the second three-way valve; the outlet of the second three-way valve is connected to the inlet of the water trap through a pipeline. c. Cooling + Compensation Cooling Mode Loop Structure: c1, First branch: The outlet of the circulating pump is connected to the inlet of the first three-way valve; the A1 outlet of the first three-way valve is connected to the inlet of the evaporator of the refrigeration unit through a pipeline; the outlet of the evaporator of the refrigeration unit is connected to the inlet of the cold storage box; the outlet of the cold storage box is connected to the inlet of the second three-way valve; one outlet of the second three-way valve is connected to the mixing point through a pipeline. c2, Second branch: The outlet of the circulating pump is connected to the inlet of the first three-way valve, and the A2 outlet of the first three-way valve is directly connected to the mixing point through a pipeline; Main loop: The mixing point outlet is connected to the water trap inlet through a pipeline, and the water trap outlet is connected to the circulation pump inlet, ultimately forming a closed loop.

3. The integrated phase change cold storage system for a vacuum cooling system according to claim 1, characterized in that, The sealed phase change unit consists of a sealed tube containing water, a phase change material, and the outer surface of the sealed tube is provided with ribs.

4. A control method for a vacuum cooling system, applied to the system as described in any one of claims 1-3, characterized in that, The method includes: S1, Cold Storage Mode Steps: Control the first and second three-way valves to allow the refrigerant to flow into the flow path that avoids the water trap, and control the operation of the refrigeration unit to freeze the phase change material in the sealed phase change unit; S2, Vacuum Cooling Mode Steps: Control the first and second three-way valves to allow the refrigerant to flow into the flow path through the water trap, and start the vacuum pump; S3, Mode Switching Judgment Step: In the vacuum cooling mode step, the temperature value detected by the first temperature sensor is monitored; when the temperature value is lower than the first preset threshold, the system is controlled to enter the cooling + supplemental cooling mode. S4. Cooling + Cooling Supplement Mode Steps: In the cooling + cooling supplement mode, based on the different temperature ranges detected by the first temperature sensor, the opening of the first three-way valve is controlled, causing the refrigerant flowing from the circulating pump to be divided into a first branch and a second branch; the first branch flows sequentially through the refrigeration unit and the cold storage tank; the second branch bypasses the refrigeration unit and the cold storage tank; after the fluids from the first branch and the second branch are mixed, they are supplied to the water trap.

5. The method according to claim 4, characterized in that, The step of controlling the opening degree of the first three-way valve based on the temperature value detected by the first temperature sensor includes: When the temperature value is within the first temperature range, the first three-way valve is controlled to allow a first proportion of refrigerant to flow to the refrigeration unit. When the temperature value is in a second temperature range that is lower than the first temperature range, the first three-way valve is controlled to allow a second proportion of refrigerant to flow to the refrigeration unit, where the second proportion is greater than the first proportion. When the temperature value is in a third temperature range that is lower than the second temperature range, the first three-way valve is controlled to allow a third proportion of refrigerant to flow to the refrigeration unit, wherein the third proportion is greater than the second proportion.

6. The method according to claim 4, characterized in that, The cold storage mode step also includes a cold storage completion determination sub-step: Monitor the outlet temperature of the cold storage tank and the load indication parameters of the refrigeration unit; When the outlet temperature remains below a completion threshold and the load indication parameter indicates a significant reduction in the load of the refrigeration unit, the cold storage is deemed complete.

7. The method according to claim 6, characterized in that, The load indication parameter is one or more of the following: the operating power, operating current, suction pressure, or evaporation temperature of the refrigeration unit.

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