Refrigeration-free vacuum cooling method and system based on double-threshold control

Abstract

The invention discloses a refrigeration-free vacuum cooling method based on double-threshold control. The refrigeration-free vacuum cooling method comprises the steps that the steam temperature # imgabs0 # and the pressure # imgabs1 # of an outlet of a vacuum cabin are monitored in real time; a temperature threshold value # imgabs2 # and a roots pump pressure threshold value # imgabs3 # are set; when # imgabs 4 # or # imgabs 5 # is met, the steam is directly communicated with the condenser through a bypass pipeline; when the requirements of # imgabs 6 # and # imgabs 7 # are met, steam is compressed through a roots pump and then enters a condenser; the condenser utilizes an environment cold source to dissipate heat, and condensed gas is discharged out of the system through the backing pump set. According to the invention, the equipment investment is saved, the use of a compression refrigeration system and Freon is omitted, the energy consumption of the system is greatly reduced, the cooling efficiency of the system is higher, and the equipment is more reliable.

Description

Technical Field

[0001] The present invention belongs to the technical field of industrial thermal management, and specifically relates to a refrigeration-free vacuum cooling method and system based on dual-threshold control. Background Art

[0002] Traditional cooling methods often rely on air or water cooling, which can be slow, energy-intensive, and prone to bacterial growth. Vacuum cooling technology, on the other hand, reduces the pressure in a vacuum chamber containing the material being cooled, lowering the boiling point of water. This allows for rapid cooling of the material through the evaporation of a small amount of water within the material, absorbing a significant amount of evaporation heat. This technology offers advantages such as rapid cooling, uniform cooling of the material's interior and exterior, and controllable temperature. However, traditional vacuum cooling equipment relies on refrigeration units, resulting in large equipment investments, complex systems, high energy consumption, low efficiency, and high maintenance costs. Fixed pump control results in poor adaptability to high and low temperature conditions, and a single steam path results in low efficiency at low temperatures. Currently, vacuum cooling technology is primarily used for the rapid cooling of food, and its application in other fields has yet to be effectively expanded. However, vacuum cooling is well-suited for many production scenarios with high temperature sensitivity and strict moisture content control, such as biopharmaceutical and new energy material production. The market urgently needs a new, energy-efficient and adaptable vacuum cooling solution. Summary of the Invention

[0003] In order to solve the above problems existing in the prior art, the present invention provides a refrigeration-free vacuum cooling method and system based on dual-threshold control, which saves equipment investment, greatly reduces system energy consumption, has higher system cooling efficiency, and makes the equipment more reliable.

[0004] The technical solution to achieve the above purpose is: One of the present inventions is a refrigeration-free vacuum cooling method based on dual-threshold control, comprising: Step S1: Real-time monitoring of the steam temperature at the vacuum chamber outlet and pressure ; Step S2: Setting the temperature threshold and Roots pump pressure threshold ; Step S3: When the or When , the steam goes directly to the condenser through the bypass line; Step S4: When the and When the steam is compressed by the Roots pump, it enters the condenser; In step S5, the condenser uses the ambient cold source to dissipate heat, and the condensed gas is discharged from the system by the front-stage pump group.

[0005] Preferably, in step S1, the temperature of the steam at the vacuum chamber outlet is collected by a temperature sensor, and the pressure of the steam at the vacuum chamber outlet is collected by a pressure sensor.

[0006] Preferably, in step S2, the temperature threshold Set to ambient cold source temperature +10~35℃, Roots pump pressure threshold Set to 5-15kPa, determined according to the technical requirements of the specific Roots pump.

[0007] Preferably, the bypass line and the Roots pump are arranged in parallel, and are connected to the vacuum chamber through a pneumatic switching valve respectively. The other ends of the bypass line and the Roots pump are connected to a condenser for receiving high-temperature and high-pressure steam, and the other ends of the condenser are connected to an ambient cold source for achieving zero refrigerant cooling and a front-stage pump group for discharging the condensed gas.

[0008] Preferably, in step S4, the algorithm To select a Roots pump with a suitable compression ratio so that the compressed gas temperature is suitable for condensation and cooling by the natural cooling source; The lower limit of 10℃ is determined by the minimum effective condensing temperature difference; when The system is at risk under the following operating conditions: cooling water temperature fluctuation of +5℃ causes condensation efficiency to drop below 45%, equipment fouling causes heat transfer coefficient to drop by 20%, thus making the actual .

[0009] A second aspect of the present invention is a refrigeration-free vacuum cooling system based on dual-threshold control, comprising: A temperature sensor for collecting the temperature of the steam at the vacuum chamber outlet, and a pressure sensor for collecting the pressure of the steam at the vacuum chamber outlet; A control module for real-time monitoring of the steam temperature and pressure at the vacuum chamber outlet; A bypass pipe and a Roots pump for circulating steam, the bypass pipe and the Roots pump are arranged in parallel; Two pneumatic switching valves for connecting the vacuum chamber with the bypass line, and the vacuum chamber with the Roots pump respectively; The bypass line and the other end of the Roots pump are both connected to a condenser for receiving high-temperature and high-pressure steam; The other end of the condenser is connected to an ambient cold source for achieving zero refrigerant cooling and a fore-stage pump group for discharging the condensed gas.

[0010] Preferably, the control module includes: Monitoring unit, used to monitor the steam temperature and pressure at the vacuum chamber outlet in real time; Dual threshold judgment unit, used to set temperature threshold and Roots pump pressure threshold , collaboratively control the steam path so that the steam enters the condenser through the bypass pipe or Roots pump; Pump group matching algorithm unit, used to Limit the system vacuum pump group Pressure is matched to the cooling target temperature for use by the algorithm To select a Roots pump with a suitable compression ratio so that the compressed gas temperature is suitable for condensation and cooling by the natural cooling source; in, is the ultimate vacuum pressure of the system vacuum pump group, is the saturated vapor pressure corresponding to the target cooling temperature, is the target cooling temperature, is the outlet temperature of the Roots pump, is the condenser medium temperature, The value is , the vacuum pump group consists of a Roots pump and a foreline pump group; Calculated by Antoine equation: .

[0011] Preferably, a single Roots pump or multiple Roots pumps connected in parallel or in series are selected according to the temperature threshold and the pressure threshold.

[0012] Preferably, the environmental cooling source is a cooling tower water cooling system, an air cooling unit or a ground source heat exchange system.

[0013] Preferably, the front stage pump group is but not limited to one of a water ring vacuum pump, a dry screw pump, a claw pump or a rotary vane vacuum pump.

[0014] Compared with the prior art, the present invention has the following beneficial effects: the present invention fully utilizes the environmental cold source through a cooling tower, air cooling, etc. to condense and cool the high-temperature steam through a condenser; and utilizes the characteristics of a Roots pump with a high pumping speed and a high compression ratio to compress the volume of the low-temperature and low-pressure steam and increase the temperature, and then condenses and cools it through the condenser environment to dissipate heat, thereby completely realizing a cooling process without refrigeration. The entire system uses a temperature and pressure dual threshold to optimize the steam path, and combines the ultimate vacuum of the pump group with the cooling target temperature and optimizes the matching of the vacuum pump group according to the ambient cold source temperature, thereby saving equipment investment, greatly reducing system energy consumption, and achieving higher system cooling efficiency and more reliable equipment. The refrigerator is eliminated, and a natural cold source is used entirely, thereby reducing a large amount of refrigeration energy consumption. Moreover, each subsystem is precisely matched and operated, and the system operating energy consumption is greatly reduced. The refrigeration equipment and excessive redundant design are eliminated, and the equipment investment is greatly reduced, making the system simpler, increasing equipment reliability, reducing equipment maintenance costs, completely eliminating the use of refrigerants, and being very environmentally friendly. Under the algorithm principle, the flexible matching of pumps and controls can be widely applied to many places. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings: Figure 1 This is a flow chart of a refrigeration-free vacuum cooling method based on dual-threshold control according to the present invention; Figure 2 This is a module diagram of a refrigeration-free vacuum cooling system based on dual-threshold control according to the present invention; Figure 3 It is a specific module diagram of the control module in the present invention. DETAILED DESCRIPTION

[0016] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0017] like Figure 1 As shown, a refrigeration-free vacuum cooling method based on dual threshold control includes: Step S1: Real-time monitoring of the steam temperature at the outlet of the vacuum chamber 1 and pressure .

[0018] In the embodiment, the temperature of the steam at the outlet of the vacuum chamber 1 is collected by the temperature sensor 2 , and the pressure of the steam at the outlet of the vacuum chamber 1 is collected by the pressure sensor 3 .

[0019] Step S2: Setting the temperature threshold and Roots pump pressure threshold .

[0020] In step S2, the temperature threshold Set to ambient cold source temperature +10~35℃, Roots pump pressure threshold It is set to 5-15kPa, determined according to the technical requirements of the specific Roots pump 6.

[0021] Step S3: When the or When , the steam passes through the bypass line 5 directly to the condenser 8.

[0022] Step S4: When the and When the steam is compressed by the Roots pump 6, it enters the condenser 8.

[0023] In the embodiment, by the algorithm To select a Roots pump with a suitable compression ratio so that the compressed gas temperature is suitable for condensation and cooling by the natural cooling source; The lower limit of 10℃ is determined by the minimum effective condensing temperature difference when The system is at risk under the following operating conditions: cooling water temperature fluctuation of +5℃ causes condensation efficiency to drop below 45%, equipment fouling causes heat transfer coefficient to drop by 20%, thus making the actual .

[0024] In step S5 , the condenser 8 uses the ambient cold source 9 to dissipate heat, and the condensed gas is discharged from the system by the front-stage pump group 10 .

[0025] In the embodiment, the bypass line 5 and the Roots pump 6 are arranged in parallel and are connected to the vacuum chamber 1 through a pneumatic switching valve 7 respectively. The other ends of the bypass line 5 and the Roots pump 6 are connected to a condenser 8 for receiving high-temperature and high-pressure steam. The other ends of the condenser 8 are connected to an ambient cold source 9 for achieving zero refrigerant cooling and a fore-stage pump group 10 for discharging the condensed gas.

[0026] like Figure 2 As shown, a refrigeration-free vacuum cooling system based on dual-threshold control includes: a temperature sensor 2 for collecting the temperature of steam at the outlet of the vacuum chamber 1, and a pressure sensor 3 for collecting the pressure of steam at the outlet of the vacuum chamber 1; a control module 4 for real-time monitoring the temperature and pressure of steam at the outlet of the vacuum chamber 1; a bypass line 5 and a Roots pump 6 for circulating steam, the bypass line 5 and the Roots pump 6 being arranged in parallel; two pneumatic switching valves 7 for respectively connecting the vacuum chamber 1 with the bypass line 5, and the vacuum chamber 1 with the Roots pump 6; the other ends of the bypass line 5 and the Roots pump 6 are both connected to a condenser 8 for receiving high-temperature and high-pressure steam; the other ends of the condenser 8 are both connected to an ambient cold source 9 for achieving zero-refrigerant cooling and a front-stage pump group 10 for discharging the condensed gas.

[0027] like Figure 2 As shown, the control module 4 includes: The monitoring unit 41 is used to monitor the steam temperature and pressure at the outlet of the vacuum chamber 1 in real time; Dual threshold judgment unit 42, used to set the temperature threshold and Roots pump pressure threshold , cooperatively controlling the steam path so that the steam enters the condenser 8 through the bypass line 5 or the Roots pump 6; that is, the high-temperature and high-pressure steam enters the condenser 8 through the bypass line 5, and the low-temperature and low-pressure gas is compressed and the temperature is increased by the Roots pump 6, and then enters the condenser 8 to be condensed and cooled by the environmental cold source 9. This dual-threshold control fully and efficiently utilizes all components of the system.

[0028] Pump group matching algorithm unit 43 is used to Select the appropriate Roots pump and backing pump combination to match the ultimate vacuum pressure of the system vacuum pump group with the cooling target temperature, so as to pass the algorithm To select a Roots pump with a suitable compression ratio so that the compressed gas temperature is suitable for condensation and cooling by the natural cooling source; in, is the ultimate vacuum pressure of the system vacuum pump group, is the saturated vapor pressure corresponding to the target cooling temperature, is the target cooling temperature, is the outlet temperature of the Roots pump, is the condenser medium temperature, The value is , the vacuum pump group consists of a Roots pump 6 and a foreline pump group 10; Calculated by Antoine equation: .

[0029] In the embodiment, a single Roots pump 6 or multiple Roots pumps 6 connected in parallel or in series are selected according to the temperature threshold and the pressure threshold.

[0030] In the embodiment, the environmental cold source 9 is a cooling tower water cooling system, an air cooling unit or a ground source heat exchange system, which not only reduces a large amount of refrigeration energy consumption and reduces equipment investment, but also eliminates the impact of refrigerant leakage on the environment, and completely solves the confusion brought to the development of the refrigeration industry by the lack of suitable environmentally friendly refrigerants.

[0031] In the embodiment, the fore pump group 10 is but not limited to one of a water ring vacuum pump, a dry screw pump, a claw pump or a rotary vane vacuum pump.

[0032] Example 1: Meat product cooling Materials: 1000kg marinated meat products parameter: , , (Environment 25℃+20℃), , Pump group configuration: two-stage Roots pump + water ring vacuum pump ( ), considering the high water content of marinated meat products, the front-stage pump group 10 is selected as a water ring vacuum pump. At the same time, considering that the pressure threshold of the vacuum pump group matches the target cooling temperature, and the outlet temperature of the Roots pump 6 matches the temperature threshold, a two-stage Roots pump is selected.

[0033] Operation process: The water ring vacuum pump starts and the pressure in vacuum chamber 1 decreases; When the pressure in vacuum chamber 1 drops to about 60 kPa, steam begins to evaporate and the temperature of the meat product decreases; When the temperature sensor 2 detects that the steam temperature is greater than 45°C, the steam passes directly to the condenser 8 and is condensed by the cooling tower (environmental cold source 9). The remaining gas is discharged by the water ring vacuum pump. When the steam temperature is lower than 45℃, the steam pressure 8kPa, close the through valve and open the first-stage Roots pump pneumatic valve. After the steam is compressed, the temperature rises to about 70℃ and then condensed by the condenser 8. The residual gas is discharged by the water ring vacuum pump.

[0034] When the steam temperature is lower than 30℃, the steam pressure 4kPa, close the through valve of condenser 8 and the bypass valve of Roots pump, open the two-stage Roots pump, the steam is compressed by the two-stage Roots pump and the temperature is raised to about 90℃, and then condensed by the condenser, and the residual gas is discharged by the water ring pump.

[0035] Effect: Actual temperature: 10.2℃ Total time: 28 minutes Energy consumption: 112kWh Example 2: Lithium battery electrode cooling parameter: , T, , Pump group configuration: three-stage Roots pump + dry screw pump, Cooling source: forced air cooling, Innovative applications: Nitrogen protection: oxygen content <100ppm, Moisture control: final value 45ppm, Effect: Cooldown time: 22 minutes (traditional 40 minutes), Energy consumption reduced: 48%.

[0036] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A refrigeration-free vacuum cooling method based on dual threshold control, characterized in that: include: Step S1, real-time monitoring of the steam temperature at the outlet of the vacuum chamber (1) and pressure ; Step S2: Setting the temperature threshold and Roots pump pressure threshold ; Step S3: When the or When , the steam passes through the bypass line (5) directly to the condenser (8); Step S4: When the and When , the steam is compressed by the Roots pump (6) and enters the condenser (8); In step S5, the condenser (8) uses the ambient cold source (9) to dissipate heat, and the condensed gas is discharged from the system by the front-stage pump group (10).

2. The refrigeration-free vacuum cooling method based on dual threshold control according to claim 1, characterized in that: In step S1, the temperature of the steam at the outlet of the vacuum chamber (1) is collected by the temperature sensor (2), and the pressure of the steam at the outlet of the vacuum chamber (1) is collected by the pressure sensor (3).

3. The refrigeration-free vacuum cooling method based on dual threshold control according to claim 1, characterized in that: In step S2, the temperature threshold Set to ambient cold source temperature +10~35℃, Roots pump pressure threshold It is set to 5-15 kPa, determined according to the technical requirements of the specific Roots pump (6).

4. The refrigeration-free vacuum cooling method based on dual threshold control according to claim 1, characterized in that: The bypass line (5) and the Roots pump (6) are arranged in parallel and are connected to the vacuum chamber (1) through a pneumatic switching valve (7). The other ends of the bypass line (5) and the Roots pump (6) are connected to a condenser (8) for receiving high-temperature and high-pressure steam. The other ends of the condenser (8) are connected to an ambient cold source (9) for achieving zero refrigerant cooling and a front-stage pump group (10) for discharging the condensed gas.

5. The refrigeration-free vacuum cooling method based on dual threshold control according to claim 1, characterized in that: In step S4, the algorithm To select a Roots pump (6) with a suitable compression ratio so that the compressed gas temperature is suitable for condensation and cooling by the natural cooling source; The lower limit of 10℃ is determined by the minimum effective condensing temperature difference when The system is at risk under the following operating conditions: cooling water temperature fluctuation of +5℃ causes condensation efficiency to drop below 45%, equipment fouling causes heat transfer coefficient to drop by 20%, thus making the actual .

6. A refrigeration-free vacuum cooling system based on the refrigeration-free vacuum cooling method based on dual threshold control according to claim 1, characterized in that: include: a temperature sensor (2) for collecting the temperature of steam at the outlet of the vacuum chamber (1), and a pressure sensor (3) for collecting the pressure of steam at the outlet of the vacuum chamber (1); A control module (4) for real-time monitoring of the temperature and pressure of steam at the outlet of the vacuum chamber (1); A bypass pipe (5) and a Roots pump (6) for circulating steam, the bypass pipe (5) and the Roots pump (6) being arranged in parallel; Two pneumatic switching valves (7) for connecting the vacuum chamber (1) and the bypass line (5), and the vacuum chamber (1) and the Roots pump (6), respectively; The other end of the bypass line (5) and the Roots pump (6) are both connected to a condenser (8) for receiving high-temperature and high-pressure steam; The other end of the condenser (8) is connected to an ambient cold source (9) for achieving zero refrigerant cooling and a front pump group (10) for discharging the condensed gas.

7. The refrigeration-free vacuum cooling system according to claim 6, characterized in that: The control module (4) includes: A monitoring unit (41) is used to monitor the steam temperature and pressure at the outlet of the vacuum chamber (1) in real time; A dual threshold judgment unit (42) is used to set a temperature threshold. and Roots pump pressure threshold , cooperatively controlling the steam path so that the steam enters the condenser (8) through the bypass line (5) or the Roots pump (6); Pump group matching algorithm unit (43) is used to Match the ultimate vacuum pressure of the system vacuum pump group with the cooling target temperature for the algorithm to To select a Roots pump (6) with a suitable compression ratio so that the compressed gas temperature is suitable for condensation and cooling by the natural cooling source; in, is the ultimate vacuum pressure of the system vacuum pump group, is the saturated vapor pressure corresponding to the target cooling temperature, is the target cooling temperature, is the outlet temperature of the Roots pump, is the condenser medium temperature, The value is , the vacuum pump group consists of a Roots pump (6) and a fore-stage pump group (10); Calculated by Antoine equation: 。 8. The refrigeration-free vacuum cooling system according to claim 6, characterized in that: A single Roots pump (6) or multiple Roots pumps (6) are selected to be connected in parallel or in series according to the temperature threshold and the pressure threshold.

9. The refrigeration-free vacuum cooling system according to claim 6, characterized in that: The ambient cooling source (9) is a cooling tower water cooling system, an air cooling unit or a ground source heat exchange system.

10. The refrigeration-free vacuum cooling system according to claim 6, characterized in that: The fore-stage pump group (10) is but not limited to one of a water ring vacuum pump, a dry screw pump, a claw pump or a rotary vane vacuum pump.

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