Multi-split refrigeration system design method, electronic equipment and readable storage medium

Abstract

The invention relates to the field of refrigerating system design, in particular to a multi-split refrigerating system design method, electronic equipment and a readable storage medium, and the multi-split refrigerating system design method comprises the following steps: S1, building a refrigerating system, and simultaneously driving n refrigerating equipment to operate through a single compressor; s2, supposing that the outlet air temperature of an evaporator of the refrigeration equipment is as follows; s3, calculating the thermal load Q of the refrigeration equipment; s4, calculating the heat exchange coefficient of the evaporator and the logarithmic average temperature difference of the evaporator according to the heat exchange coefficient and the logarithmic average temperature difference assumed in the step S2; s5, the heat exchange area U of the evaporator is determined according to the heat load Q of the refrigeration equipment, the logarithmic average temperature difference of the evaporator and the heat exchange coefficient of the evaporator; and S6, the heat exchange amount Q of the refrigeration equipment is calculated. According to the method, the running number range of the freezing and refrigerating equipment in the multi-split refrigerating system can be determined, and the optimal running number of the freezing and refrigerating equipment under the corresponding demand condition can be determined.

Description

Technical Field

[0001] This invention relates to the field of refrigeration system design, specifically a method for designing a multi-channel refrigeration system, an electronic device, and a readable storage medium. Background Technology

[0002] The increasing demand for refrigeration equipment in storage sectors such as grain silos has led to the emergence of multi-unit refrigeration systems, which offer a highly efficient and flexible cooling solution for centralized refrigeration and temperature control. However, because multiple refrigeration units share a single refrigeration system, factors such as differences in refrigeration load, door opening frequency, and changes in product display among the different units cause significant fluctuations in the overall system's cooling demand, placing higher demands on the accuracy and stability of temperature control. Existing multi-unit refrigeration systems lack intelligent decision-making capabilities and cannot determine a range of operating units that satisfies both cooling requirements and ensures stable and efficient system operation based on dynamically changing operating conditions, nor can they further pinpoint an optimal number of units within that range. Current systems can only simply increase or decrease the number of operating units based on upper and lower pressure limits. Under low-load conditions, operating too many devices can lead to excessively low evaporation pressure, increased compressor pressure ratio, and a sharp deterioration in energy efficiency, potentially even triggering low-pressure protection. In this case, the number of operating devices exceeds the upper limit of the reasonable range. Conversely, under high-load conditions, operating too few devices results in ineffective cooling and prolonged high-load operation of the compressor, also exceeding the lower limit of the reasonable range. The existing system cannot assess this, forcing it to operate at suboptimal or even harmful device counts. The system cannot determine the optimal range of operating refrigeration and cold storage equipment for the specific operating conditions, nor does it possess the ability to find the optimal number of devices operating under corresponding requirements within this range. This results in the system operating under conditions of high energy consumption and poor stability for extended periods, thus requiring urgent resolution. Summary of the Invention

[0003] To avoid and overcome the technical problems existing in the prior art, this invention provides a design method, electronic device, and readable storage medium for a multi-split refrigeration system. This invention can determine the range of the number of refrigeration and cold storage units operating in a multi-split refrigeration system, and determine the optimal number of refrigeration and cold storage units operating under corresponding demand conditions.

[0004] To achieve the above objectives, the present invention provides the following technical solution: A design method for a multi-split refrigeration system includes the following steps: S1. Build a refrigeration system, driven simultaneously by a single compressor. n The refrigeration equipment is in operation; S2. Assume the outlet air temperature of the evaporator in the refrigeration equipment is... ; S3. Calculate the heat load of the refrigeration equipment. Q ; S4, assuming the outlet air temperature of the evaporator in step S2 Calculating the heat exchange coefficient of the evaporator and the logarithmic mean temperature difference of the evaporator ; S5, determining the heat exchange area of the evaporator according to the heat load of the refrigeration equipment Q , the logarithmic mean temperature difference of the evaporator and the heat exchange coefficient of the evaporator U : ; S6, calculating the heat exchange amount of the refrigeration equipment Q 换 : ; Verifying the matching degree of the heat exchange amount of the refrigeration equipment Q 换 with the heat load of the refrigeration equipment Q , verifying whether the outlet air temperature of the evaporator meets the set temperature, verifying whether the temperature fluctuation of the refrigeration equipment meets the design requirement, and if the above conditions are met, entering S7, otherwise returning to S2 to re- assume the outlet air temperature of the evaporator of the refrigeration equipment S7, on the basis of the refrigeration equipment n , the number of refrigeration equipment is increased or decreased, and after increasing or decreasing the refrigeration equipment, it is judged whether each refrigeration equipment meets the design requirement at the same time, so as to determine the upper and lower limit range of the number of refrigeration equipment S8, the optimal number of refrigeration equipment in the upper and lower limit range of the number of refrigeration equipment is determined by dynamic weight optimization.

[0005] As a further scheme of the present application: in step S3, the heat load of the refrigeration equipment is Q : ; ; ; ; wherein, is the door opening heat load of the refrigeration equipment; is the internal equipment heat load of the refrigeration equipment; is the internal goods heat load of the refrigeration equipment; is the safety margin coefficient; is the external surface area of the refrigeration equipment;​ The internal temperature of the refrigeration equipment; The external temperature of the refrigeration equipment; The heat transfer coefficient of the inner surface of the refrigeration equipment; The heat transfer coefficient of the outer surface of the refrigeration equipment; The thickness of the insulation layer in the refrigeration equipment; Thermal conductivity of the insulation layer for refrigeration equipment; The volume of the refrigeration equipment; The average number of times the refrigeration equipment is turned on per unit time; air density; This is the enthalpy difference of air; For the first in the refrigeration equipment Power of internal equipment; For the first in the refrigeration equipment The influence coefficient of the internal equipment of the platform on the heat load; Specific heat capacity of goods inside the refrigeration equipment; For the quality of goods inside the refrigeration equipment; This represents the temperature change of goods inside the refrigeration equipment per unit time.

[0006] As a further aspect of the present invention: in step S5, the performance bottleneck stage of the evaporator is determined, and the dehumidification coefficient of the evaporator at the performance bottleneck stage is used as the basis for further analysis. Calculate the heat transfer coefficient of the evaporator ,

[0007]

[0008]

[0009]

[0010]

[0011]

[0012] in, Heat transfer coefficient on refrigerant side of evaporator; Surface area of fins per meter length of evaporator finned tube; Area of outer tube wall not covered by fins per meter length of evaporator finned tube; Total heat transfer area of air per meter length of evaporator finned tube; Outer surface area of evaporator finned tube calculated as outer diameter of tube; Inner surface area of evaporator finned tube calculated as inner diameter of tube; Thickness of fins of evaporator finned tube; Thermal conductivity of fins of evaporator finned tube; Air side dust layer thermal resistance of evaporator finned tube; Contact thermal resistance of tube wall to fins of evaporator finned tube; Heat transfer coefficient on air side of evaporator; Dry surface heat transfer coefficient of evaporator finned tube; Surface heat transfer coefficient of evaporator finned tube with liquid phase alone flowing inside tube; Average surface heat transfer coefficient of evaporator finned tube; Finned surface efficiency of evaporator finned tube; Moisture extraction coefficient of evaporator; Finned efficiency; Liquid phase Froude number; Liquid phase Prandtl number; , , All are air property parameters; Air velocity at narrowest cross section between tube bundles of evaporator finned tube; Characteristic number; When < 0.65, = 1.136; = -0.9; = 667.2; = 0.7; = 0.3; When ≥ 0.65, = 0.6683; = -0.2; = 1058; = 0.7; = 0.3; is the Fourier number; is the boiling characteristic number; is a dimensionless number depending on the refrigerant properties; is the Reynolds number; is the inner diameter of the evaporator finned tube.

[0013] As a further scheme of the present application: when the wet heat coupling factor of the evaporator is greater than a threshold value, and the evaporator tube wall temperature is lower than the air dew point temperature for more than a set time, the evaporator reaches a performance bottleneck; ; ; ; wherein, is the wet-out coefficient of the evaporator; is the pressure drop change rate of the evaporator; is the evaporator inlet air enthalpy; is the evaporator outlet air enthalpy; is the specific heat capacity of water; is the evaporator inlet air temperature; is the evaporator outlet air temperature; is the actual operating pressure drop of the evaporator; is the design operating pressure drop of the evaporator.

[0014] As a further scheme of the present application: in step S4, the logarithmic mean temperature difference of the evaporator is: ; wherein, is the evaporator inlet air temperature; is the evaporator outlet air temperature; is the evaporator temperature.

[0015] As a further scheme of the present application: in step S7, S71, increasing the number of refrigeration equipment one by one; S711, judging whether the refrigeration equipment meets the following design requirements at the same time: ; S712, when S711 is met, continue to increase the number of refrigeration equipment and repeat S711; S713, when S711 is not met, the following test is performed:

[0016] S714, when any test condition in S713 is met, the number of refrigeration equipment reaches the upper limit; when any test condition in S713 is not met, the compressor failure mode is diagnosed and optimized, and returns to S713 for retesting; S72, reducing the number of refrigeration equipment one by one; S721, judging whether the refrigeration equipment meets the following design requirements at the same time:

[0017] S722, when S721 is met, continue to reduce the number of refrigeration equipment and repeat S711; S723, when S721 is not met, the following test is performed:

[0018] S724, when any test condition in S723 is met, the number of refrigeration equipment reaches the lower limit; when any test condition in S723 is not met, the compressor failure mode is diagnosed and optimized, and returns to S723 for retesting.

[0019] As a further scheme of the present application: in S8, ; wherein, is the optimal number of refrigeration equipment; is the total refrigeration capacity of the refrigeration system; E is the 24-hour power consumption of the refrigeration system; is the cooling rate of the refrigeration system; , , All are optimization coefficients; + + =1; The normalized function representing the total cooling capacity; The normalized function representing the system's energy consumption; A normalized function representing the cooling rate; When rapid cooling is required, As the highest priority, Secondary priority E Adjust as the lowest priority , , To obtain the optimal number of refrigeration devices to maximize refrigeration performance; When the demand for cooling performance is balanced with energy efficiency, E As the highest priority, Secondary priority Adjust as the lowest priority , , The optimal number of refrigeration units is obtained when refrigeration performance and energy efficiency are balanced. When the highest security is required, As the highest priority, with Secondary priority E Adjust as the lowest priority , , The optimal number of refrigeration devices is obtained when the highest safety is achieved.

[0020] As a further aspect of the present invention: In step S1, the compressor is selected according to the design operating conditions. When any of the following conditions occur, the compressor is selected as a variable frequency compressor; otherwise, the compressor is selected as a fixed frequency compressor: .

[0021] An electronic device includes a processor, an input device, an output device, and a memory, wherein the processor, the input device, the output device, and the memory are connected in sequence, the memory is used to store a computer program, the computer program includes program instructions, and the processor is configured to call the program instructions to execute the aforementioned design method for a multi-channel cooling system.

[0022] A readable storage medium storing a computer program, the computer program including program instructions that, when executed by a processor, cause the processor to perform the aforementioned design method for a multi-channel cooling system.

[0023] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention, through a closed-loop operation of design, verification, and iteration, verifies the outlet temperature and temperature fluctuations and feeds them back to the evaporator for redesign, ensuring the stability and temperature control accuracy of a single refrigeration unit under dynamic operating conditions. After completing the evaporator design, the range of the number of refrigeration and cold storage units operating in a multi-unit refrigeration system can be determined, and the optimal number of refrigeration and cold storage units operating under corresponding demand conditions can be determined, achieving a global optimal balance of the refrigeration system in the three core indicators of safety, performance, and energy efficiency.

[0024] 2. This invention decomposes the heat load into components such as door opening, equipment, and goods, and introduces a safety margin coefficient to establish a reliable heat load model, ensuring the accuracy of system design. The introduction of the performance bottleneck stage ensures that the evaporator is designed under the worst operating conditions of the system, guaranteeing that the evaporator can meet the core heat exchange requirements under any operating conditions.

[0025] 3. By adding or removing equipment one by one and testing critical conditions, this invention accurately determines the upper and lower limits of the number of refrigeration devices that a single compressor can stably support through a combination of experimentation and diagnosis. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the multi-split refrigeration system in this invention.

[0027] In the diagram: 1. Gas-liquid separator; 2. Compressor; 3. Bypass solenoid valve; 4. Check valve; 5. Oil separator; 6. Condenser; 7. Liquid receiver; 8. Dryer filter; 9. Liquid injection solenoid valve; 10. Capillary tube; 11. Sight glass; 12. Thermal expansion valve; 13. Evaporator. Detailed Implementation

[0028] 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.

[0029] Please see Figure 1 In this embodiment of the invention, a design method for a multi-device cooling system, an electronic device, and a readable storage medium include the following steps: S1. Build a refrigeration system that uses a single compressor to drive n refrigeration devices simultaneously. The refrigeration system in this embodiment is as follows: Figure 1 As shown, the compressor unit includes a compressor 2, a gas-liquid separator 1, and an oil separator 5. The gas-liquid separator 2 is located before the suction port of the compressor 2 and is used to separate and prevent liquid refrigerant or lubricating oil from directly entering the compressor cylinder, ensuring the safe operation of the compressor. The oil separator 5 is connected to the discharge port of the compressor and is used to separate and recover the lubricating oil entrained in the compressed gas. The one-way valve 4 is usually located on the discharge side of the compressor 2 or after the oil separator 5 to prevent refrigerant backflow.

[0030] The condensation and storage module includes a condenser 6 and a storage tank 7. The condenser is used to condense the high-temperature and high-pressure refrigerant gas into a liquid; the storage tank is connected to the condenser outlet and is used to store the liquid refrigerant from the condenser.

[0031] The dryer filter 8 is connected to the outlet of the liquid reservoir 7 and is used to adsorb moisture in the system and filter impurities.

[0032] The throttling and pressure-reducing device includes a capillary tube 10 and a thermostatic expansion valve 12. The capillary tube 10 is used to throttle and reduce the pressure of the high-pressure liquid refrigerant; the thermostatic expansion valve 12 is used to precisely control the refrigerant flow rate entering the evaporator 13. The evaporator 13 corresponds one-to-one with the refrigeration equipment.

[0033] The auxiliary monitoring and control system includes a sight glass 11, a liquid injection solenoid valve 9, and a bypass solenoid valve 3. The sight glass 11 is used to observe the refrigerant flow status and water content indication. The liquid injection solenoid valve 9 is connected between the outlet of the liquid receiver 7 and the suction port or intermediate chamber of the compressor 2, and is used to inject liquid refrigerant into the compressor to reduce the exhaust temperature when needed. The bypass solenoid valve 3 is usually connected in parallel to the compressor 2 or connected to the suction and discharge sides, and is used to bypass part of the refrigerant gas under specific operating conditions to adjust the system load or protect the compressor.

[0034] The following strategies can be followed when selecting a compressor: The compressor should be selected as a variable frequency compressor when any of the following conditions are met; otherwise, the compressor should be selected as a fixed frequency compressor. .

[0035] The initial value of n can be selected based on experience, or after determining the compressor type, the heat load of each refrigeration unit can be calculated, and the n value that meets the conditions can be determined based on the compressor model and heat load.

[0036] S2. Assume the outlet air temperature of the evaporator in the refrigeration equipment is... ; S3. Calculate the heat load of the refrigeration equipment. Q ; ; ; ; ; in, The opening heat load of the refrigeration equipment; The internal heat load of the refrigeration equipment; The internal heat load of goods in the refrigeration equipment; This is the safety margin factor, and its value ranges from 1.1 to 1.3. The external surface area of ​​the refrigeration equipment; The internal temperature of the refrigeration equipment; The external temperature of the refrigeration equipment; The heat transfer coefficient of the internal surface of the refrigeration equipment is typically 5 ~ 25 W / (m²·K); The heat transfer coefficient of the outer surface of the refrigeration equipment is typically 5 ~ 30 W / (m²·K); The thickness of the insulation layer in the refrigeration equipment; Thermal conductivity of the insulation layer for refrigeration equipment; The volume of the refrigeration equipment; The average number of times the refrigeration equipment is turned on per unit time; air density; The enthalpy difference of air reflects the heat load caused by the difference in enthalpy between the inside and outside air when the door is opened; For the first in the refrigeration equipment Power of internal equipment; For the first in the refrigeration equipment The influence coefficient of the internal equipment on the heat load was obtained by referring to the table. Specific heat capacity of goods inside the refrigeration equipment; For the quality of goods inside the refrigeration equipment; This represents the temperature change of goods inside the refrigeration equipment per unit time.

[0037] S4, based on the assumptions made in step S2 Calculate the heat transfer coefficient of the evaporator and the logarithmic mean temperature difference of the evaporator ; When the evaporator's moisture-heat coupling factor When the temperature exceeds the threshold and the evaporator tube wall temperature remains below the air dew point temperature for more than 10 minutes, the evaporator reaches its performance bottleneck. The dehumidification coefficient of the evaporator at this performance bottleneck stage is considered the threshold value. Calculate the heat transfer coefficient of the evaporator : ; ; ; in, The dehumidification coefficient of the evaporator; The rate of change of pressure drop in the evaporator; The enthalpy of the air at the evaporator inlet; This refers to the enthalpy of the air at the evaporator outlet. This is the specific heat capacity of water; This refers to the air temperature at the evaporator inlet. This refers to the air temperature at the evaporator outlet. This represents the actual operating pressure drop of the evaporator. The design operating pressure drop of the evaporator;

[0038]

[0039]

[0040]

[0041]

[0042]

[0043] in, The heat transfer coefficient on the refrigerant side of the evaporator; This refers to the surface area of ​​the fins per meter of tube length in the evaporator finned tube. The area of ​​the outer tube wall of the evaporator finned tube that is not covered by fins per meter of tube length; This refers to the total heat transfer area of ​​the air per meter of evaporator finned tube length. The outer surface area of ​​the finned tube is calculated based on the outer diameter of the evaporator finned tube. The inner surface area of ​​the finned tube is calculated based on the inner diameter of the evaporator finned tube. The fin thickness of the evaporator finned tube; The fin thermal conductivity of the evaporator finned tube; The thermal resistance of the air-side dust layer in the evaporator finned tube; The contact thermal resistance between the finned tube wall and the fins in the evaporator; The air-side heat transfer coefficient of the evaporator; The dry surface heat transfer coefficient of the evaporator finned tube; The surface heat transfer coefficient of the liquid phase flowing alone through the finned tube of the evaporator; The average surface heat transfer coefficient of the evaporator finned tubes; The fin surface efficiency of the evaporator finned tube; The dehumidification coefficient of the evaporator; For fin efficiency; For liquid phase Froude number; The Prandtl number for the liquid phase; , , All are air physical properties, obtained from tables; The wind speed at the narrowest cross-section between the finned tube bundles of the evaporator; The characteristic number; when <0.65, =1.136; = -0.9; =667.2; =0.7; =0.3; when ≥0.65, =0.6683; = -0.2; =1058; =0.7; =0.3; Fourier number This represents the boiling characteristic number; It is a dimensionless number that depends on the properties of the refrigerant; It is the Reynolds number; This refers to the inner diameter of the evaporator finned tube.

[0044] Logarithmic mean temperature difference of evaporator for: ; in, This refers to the air temperature at the evaporator inlet. This refers to the air temperature at the evaporator outlet. This refers to the evaporation temperature of the evaporator.

[0045] S5. Based on the heat load of the refrigeration equipment Q Logarithmic mean temperature difference of evaporator and the heat transfer coefficient of the evaporator Determine the heat exchange area of ​​the evaporator. U :

[0046] Once the heat exchange area of ​​the evaporator is determined, the number of tube rows in the evaporator can be determined based on the area, thus completing the design of the evaporator. S6. Calculate the heat exchange capacity of the refrigeration equipment. Q 换 : = ; The specific heat capacity of air; .

[0047] Verify the heat exchange capacity of the refrigeration equipment Q 换 Heat load of refrigeration equipment Q Check if the matching degree difference is less than the set value, which is usually 5%. Verify whether the outlet air temperature of the evaporator meets the set temperature and whether the temperature fluctuation of the refrigeration equipment meets the design requirements. If the above conditions are met at the same time, proceed to S7. If the above conditions are not met at the same time, return to S2 and re-assume the outlet air temperature of the evaporator of the refrigeration equipment. S7, inn Based on the existing refrigeration equipment, the number of refrigeration equipment is increased or decreased one by one. After increasing or decreasing the refrigeration equipment, it is determined whether each refrigeration equipment meets the design requirements at the same time, thereby determining the upper and lower limits of the number of refrigeration equipment. S71. Increase the number of refrigeration units one by one; S711. Determine whether the refrigeration equipment simultaneously meets the following design requirements: ; S712. When the condition in S711 is met, continue to increase the number of refrigeration equipment and repeat S711. S713. If condition S711 is not met, perform the following test:

[0048] S714. When any of the test conditions in S713 are met, the number of refrigeration devices reaches the upper limit. If any test condition in S713 is not met, the compressor error mode is diagnosed and optimized, and then returned to S713 for retesting. S72. Reduce the number of refrigeration units one by one; S721. Determine whether the refrigeration equipment simultaneously meets the following design requirements:

[0049] S722. If the condition in S721 is met, continue to reduce the number of refrigeration equipment and repeat S711. S723. If condition S721 is not met, perform the following test:

[0050] S724. When any of the test conditions in S723 are met, the number of refrigeration devices reaches the lower limit. If any test condition in S723 is not met, the compressor error mode is diagnosed and optimized, and then returned to S723 for retesting.

[0051] S8. Determine the optimal number of refrigeration equipment within the upper and lower limits of the number of refrigeration equipment through dynamic weight optimization.

[0052] ; in, The optimal number of refrigeration units; This refers to the total cooling capacity of the refrigeration system. E This refers to the 24-hour power consumption of the refrigeration system. The cooling rate of the refrigeration system; , , All are optimization coefficients; + + =1; The normalized function representing the total cooling capacity; The normalized function representing the system's energy consumption; A normalized function representing the cooling rate; normalization function f(x) = ( x - X_min) / (X_max - X_min) ; When rapid cooling is required, As the highest priority, Secondary priority E Adjust as the lowest priority , , To obtain the optimal number of refrigeration devices to maximize refrigeration performance; When the demand for cooling performance is balanced with energy efficiency, E As the highest priority, Secondary priority Adjust as the lowest priority , , The optimal number of refrigeration units is obtained when refrigeration performance and energy efficiency are balanced. When the highest security is required, As the highest priority, with Secondary priority E Adjust as the lowest priority , , The optimal number of refrigeration devices is obtained when the highest safety is achieved.

[0053] Taking a certain freezer as an example, the external dimensions of the refrigeration equipment are 1726 mm long, 728 mm wide, and 2425 mm high. The indoor temperature in summer is 24°C, the target temperature is 4°C, the allowable temperature fluctuation range of the freezer is 2~5°C, the external surface area of ​​the cabinet is 14.41 m², the internal volume of the cabinet is 3.18 m³, and the system uses a certain fixed-frequency compressor.

[0054] Calculate the heat load Q of a single freezer. The thermal conductivity of the insulation layer is 0.028 W / (m·℃), the insulation layer thickness is 0.04 m, the heat transfer coefficient of the inner surface is 10 W / (m²·℃), the heat transfer coefficient of the outer surface is 10 W / (m²·℃), the average number of door openings is 5 times / hour, and the air density is 1.225 kg / m³. There is one evaporator fan with a power of 12.4 W. There are two LED tubes with a power of 9 W each, and the influence coefficient of the tube position on the heat load is 0.5. The heating wire power is 150 W, and the influence coefficient of the heating wire position on the heat load is 0.2. The mass of the internal goods is 8.75 kg, and the specific heat capacity of the internal goods is 4.19 kJ / (kg·℃). The calculated heat load Q is... The initial selection was six freezers with a total cooling capacity of 3895.26W. However, since the freezers do not meet the three conditions requiring the use of inverter compressors, fixed-frequency compressors can be used instead. The refrigeration system will use R404A as the refrigerant, with a condensing temperature of 40℃ and an evaporating temperature of -5℃. Under the design conditions, the compressor's cooling capacity will be 4006W and its power consumption will be 1201W.

[0055] The evaporator uses 9.52mm × 0.5mm copper tubes as heat transfer tubes, with a fin thickness of 0.14mm, a fin spacing of 3.5mm, and a tube center-to-center distance of 25mm on the air-facing side. The tube clusters are arranged in an equilateral triangular staggered pattern. Calculations... ; .

[0056] The required heat transfer area for the evaporator is U = 667 / (26.89 × 6.60) = 3.76 m² 2 The total length of the heat transfer tubes required for the evaporator is L = 12.72m. Assuming the evaporator width is 540mm and height is 200mm, the actual frontal area is 0.108m². 2 The number of pipe rows in the airflow direction is 5, and the windward width (effective single pipe length) is 0.54m. The pipe spacing perpendicular to the airflow direction has been selected as 25mm, therefore the number of pipe rows perpendicular to the airflow direction is 8. Determine the evaporator design.

[0057] The design of the condenser in this application is similar, therefore the design steps are omitted. The same calculations yield condenser dimensions of 700mm width, 600mm height, 4 rows, 24 columns, and 4 branch lines.

[0058] During the verification in S6, the condensing temperature was set to 35℃ and the evaporating temperature to -3℃. At this time, the compressor's cooling capacity was 4628W and the power was 1073W. The condensing load coefficient of R404A at a condensing temperature of 35℃ and an evaporating temperature of -3℃ was 1.18, so the condensing heat load was 5461W.

[0059] By reassuming the outlet temperature and iteratively solving the problem, it was verified that the difference between the heat exchange and heat load matching degree was less than 5%, and that the outlet temperature met the design temperature. When calculating the condenser, the final iterative calculation yielded an air outlet temperature of 28.33℃, at which point the calculated logarithmic mean temperature difference was 8.16K. = =21.65×31.3×8.16=5529.58W, when verifying the error rate, = =1.27×1005×(28.33-24)=5526.60W, which is 3.2% different from the calculated condensing heat load of 5.46kW. This is within the allowable error range and can meet the heat transfer requirements of the condensing load.

[0060] When calculating the evaporator, the final iterative calculation yielded an air outlet temperature of 1.85℃, at which point the calculated logarithmic mean temperature difference was 4.85K. = ==24.50×6.39×4.85=752.29W; = =0.35×1005×(4-1.85)=756.26W; the difference from the designed cooling capacity of 772W is 2.3%, which is within the allowable error range and can meet the heat transfer requirements.

[0061] After the multi-split system stabilizes, recalculate the heat load required for the freezer to maintain thermal balance. The heat load of the freezer at this point is... The process begins by adding freezers one by one, recalculating whether the system can complete the cooling process. This iterative calculation is repeated to obtain the final outlet temperature. At this point, all freezers are checked to ensure they reach the required temperature and the temperature fluctuation is less than 0.8℃ / 10min. If the temperature requirement and temperature uniformity are met, the system runs continuously for 24 hours. The average temperature of all freezers is then checked to ensure it is within ±1℃ of the required temperature and the maximum / minimum temperature difference does not exceed 3℃. If these conditions are met, the system can support one (n+i) freezers, and more freezers can be added. If the prerequisites are not met, the compressor needs to be tested for COP decay exceeding 15% or exhaust temperature exceeding the safety threshold. The presence of either indicates that the compressor has reached its limit. If the compressor limit is not reached but the required temperature or temperature uniformity is not achieved, error mode diagnosis is required. For example, uneven refrigerant distribution may cause some freezers to fail to meet the requirements. Optimization is then performed, and the above steps are repeated after optimization. Finally, the range of freezer quantity is calculated.

[0062] After determining the range of the number of freezers, the optimal number of freezers is then determined. For different freezer configurations, three independent optimization processes are performed: performance-oriented, balanced, and safety-oriented. The objective function is constructed as follows: ; For commercial refrigerated display cases, a performance-oriented approach can be chosen. By increasing the weight of cooling speed to meet the basic needs of commercial refrigerated display cases, the optimal number of refrigerated cases can be obtained by using this function for optimization.

[0063] Another embodiment of this application is an electronic device.

[0064] The electronic device can be the mobile device itself, or a standalone device that can communicate with the mobile device to receive the collected input signals from it and send the selected target decision behavior to it.

[0065] Electronic devices include one or more processors and memory.

[0066] A processor can be a central processing unit (CPU) or other form of processing unit with data processing and / or instruction execution capabilities, and can control other components in an electronic device to perform desired functions.

[0067] The memory may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may include, for example, random access memory (RAM) and / or cache memory. The non-volatile memory may include, for example, read-only memory (ROM), hard disk, flash memory, etc. One or more computer program instructions may be stored on the computer-readable storage medium, and the processor may execute the program instructions to implement a one-to-many cooling system design method of the various embodiments of this application described above.

[0068] In one example, the electronic device may also include input and output devices, which are interconnected via a bus system and / or other forms of connection. For example, the input device may include various devices such as on-board diagnostics (OBD), cameras, industrial cameras, etc. The input device may also include, for example, a keyboard, a mouse, etc. The output device may include, for example, a monitor, speakers, a printer, and communication networks and their connected remote output devices, etc.

[0069] In addition, depending on the specific application, electronic devices may include any other suitable components.

[0070] Another embodiment of this application may be a computer program product, which includes computer program instructions that, when executed by a processor, cause the processor to perform the calculation steps described in the above-described method for designing a multi-channel cooling system according to various embodiments of this application.

[0071] The computer program product can be written in any combination of one or more programming languages ​​to perform the operations of the embodiments of this application. The programming languages ​​include object-oriented programming languages ​​such as Java and C++, as well as conventional procedural programming languages ​​such as C or similar languages. The program code can be executed entirely on the user's computing device, partially on the user's computing device, as a standalone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0072] Furthermore, embodiments of this application may also be computer-readable storage media storing computer program instructions that, when executed by a processor, cause the processor to perform a one-to-many cooling system design method as described in this specification.

[0073] The computer-readable storage medium may be any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may, for example, include, but is not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatuses, or devices, or any combination thereof. More specific examples of readable storage media (a non-exhaustive list) include: electrical connections having one or more wires, portable disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0074] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0075] The block diagrams of devices, apparatuses, devices, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

Claims

1. A design method for a multi-split refrigeration system, characterized in that, Includes the following steps: S1. Build a refrigeration system, driven simultaneously by a single compressor. n The refrigeration equipment is in operation; S2. Assume the outlet air temperature of the evaporator in the refrigeration equipment is... ; S3. Calculate the heat load of the refrigeration equipment. Q ; S4, based on the assumptions made in step S2 Calculate the heat transfer coefficient of the evaporator and the logarithmic mean temperature difference of the evaporator ; S5. Based on the heat load of the refrigeration equipment Q Logarithmic mean temperature difference of the evaporator and the heat transfer coefficient of the evaporator Determine the heat exchange area of ​​the evaporator. U : S6. Calculate the heat exchange capacity of the refrigeration equipment. Q 换 : ； Verify the heat exchange capacity of the refrigeration equipment Q 换 Heat load of refrigeration equipment Q Check if the matching degree difference is less than the set value, verify if the outlet air temperature of the evaporator meets the set temperature, and verify if the temperature fluctuation of the refrigeration equipment meets the design requirements. If all the above conditions are met, proceed to S7. If the above conditions are not met at the same time, return to S2 and re-assume the outlet air temperature of the evaporator of the refrigeration equipment. S7, in n Based on the existing refrigeration equipment, the number of refrigeration equipment is increased or decreased one by one. After increasing or decreasing the refrigeration equipment, it is determined whether each refrigeration equipment meets the design requirements at the same time, thereby determining the upper and lower limits of the number of refrigeration equipment. S8. Determine the optimal number of refrigeration equipment within the upper and lower limits of the number of refrigeration equipment through dynamic weight optimization.

2. The design method for a multi-split refrigeration system according to claim 1, characterized in that, In step S3, the heat load of the refrigeration equipment is Q : in, The opening heat load of the refrigeration equipment; The internal heat load of the refrigeration equipment; The internal heat load of goods in the refrigeration equipment; This is the safety margin factor; The external surface area of ​​the refrigeration equipment; The internal temperature of the refrigeration equipment; The external temperature of the refrigeration equipment; The heat transfer coefficient of the inner surface of the refrigeration equipment; The heat transfer coefficient of the outer surface of the refrigeration equipment; The thickness of the insulation layer in the refrigeration equipment; Thermal conductivity of the insulation layer for refrigeration equipment; The volume of the refrigeration equipment; The average number of times the refrigeration equipment is turned on per unit time; air density; This is the enthalpy difference of air; For the first in the refrigeration equipment Power of internal equipment; For the first in the refrigeration equipment The influence coefficient of the internal equipment of the platform on the heat load; Specific heat capacity of goods inside the refrigeration equipment; For the quality of goods inside the refrigeration equipment; This represents the temperature change of goods inside the refrigeration equipment per unit time.

3. The design method for a multi-split refrigeration system according to claim 1, characterized in that, In step S5, the performance bottleneck stage of the evaporator is determined, and the dehumidification coefficient of the evaporator at the performance bottleneck stage is used as the basis for this determination. Calculate the heat transfer coefficient of the evaporator , in, The heat transfer coefficient on the refrigerant side of the evaporator; This refers to the surface area of ​​the fins per meter of tube length in the evaporator finned tube. The area of ​​the outer tube wall of the evaporator finned tube that is not covered by fins per meter of tube length; This refers to the total heat transfer area of ​​the air per meter of evaporator finned tube length. The outer surface area of ​​the finned tube is calculated based on the outer diameter of the evaporator finned tube. The inner surface area of ​​the finned tube is calculated based on the inner diameter of the evaporator finned tube. The fin thickness of the evaporator finned tube; The fin thermal conductivity of the evaporator finned tube; The thermal resistance of the air-side dust layer in the evaporator finned tube; The contact thermal resistance between the finned tube wall and the fins in the evaporator; The air-side heat transfer coefficient of the evaporator; The dry surface heat transfer coefficient of the evaporator finned tube; The surface heat transfer coefficient of the liquid phase flowing alone through the finned tube of the evaporator; The average surface heat transfer coefficient of the evaporator finned tubes; The fin surface efficiency of the evaporator finned tube; The dehumidification coefficient of the evaporator; For fin efficiency; For liquid phase Froude number; The Prandtl number for the liquid phase; , , All are air physical properties; The wind speed at the narrowest cross-section between the finned tube bundles of the evaporator; The characteristic number; when <0.65, =1.136; = -0.9; =667.2; =0.7; =0.3; when ≥0.65, =0.6683; = -0.2; =1058; =0.7; =0.3; Fourier number This represents the boiling characteristic number; It is a dimensionless number that depends on the properties of the refrigerant; It is the Reynolds number; This refers to the inner diameter of the evaporator finned tube.

4. The design method for a multi-split refrigeration system according to claim 3, characterized in that, When the evaporator's moisture-heat coupling factor When the temperature exceeds the threshold and the evaporator tube wall temperature remains below the air dew point temperature for a set period of time, the evaporator reaches its performance bottleneck. ； ； ； in, The dehumidification coefficient of the evaporator; The rate of change of pressure drop in the evaporator; The enthalpy of the air at the evaporator inlet; This refers to the enthalpy of the air at the evaporator outlet. This is the specific heat capacity of water; This refers to the air temperature at the evaporator inlet. This refers to the air temperature at the evaporator outlet. This represents the actual operating pressure drop of the evaporator. This refers to the design operating pressure drop of the evaporator.

5. The design method for a multi-split refrigeration system according to claim 1, characterized in that, In step S4, the logarithmic mean temperature difference of the evaporator for: in, This refers to the air temperature at the evaporator inlet. This refers to the air temperature at the evaporator outlet. This refers to the evaporation temperature of the evaporator.

6. The design method for a multi-split refrigeration system according to claim 1, characterized in that, In step S7, S71. Increase the number of refrigeration units one by one; S711. Determine whether the refrigeration equipment simultaneously meets the following design requirements: ； S712. When the condition in S711 is met, continue to increase the number of refrigeration equipment and repeat S711. S713. If condition S711 is not met, perform the following test: S714. When any of the test conditions in S713 are met, the number of refrigeration devices reaches the upper limit. If any test condition in S713 is not met, the compressor error mode is diagnosed and optimized, and then returned to S713 for retesting. S72. Reduce the number of refrigeration units one by one; S721. Determine whether the refrigeration equipment simultaneously meets the following design requirements: S722. If the condition in S721 is met, continue to reduce the number of refrigeration equipment and repeat S711. S723. If condition S721 is not met, perform the following test: S724. When any of the test conditions in S723 are met, the number of refrigeration devices reaches the lower limit. If any test condition in S723 is not met, the compressor error mode is diagnosed and optimized, and then returned to S723 for retesting.

7. The design method for a multi-split refrigeration system according to claim 1, characterized in that, In S8, ; in, The optimal number of refrigeration units; This refers to the total cooling capacity of the refrigeration system. E This refers to the 24-hour power consumption of the refrigeration system. The cooling rate of the refrigeration system; , , All are optimization coefficients; + + =1; The normalized function representing the total cooling capacity; The normalized function representing the system's energy consumption; A normalized function representing the cooling rate; When rapid cooling is required, As the highest priority, Secondary priority E Adjust as the lowest priority , , To obtain the optimal number of refrigeration devices to maximize refrigeration performance; When the demand for cooling performance is balanced with energy efficiency, E As the highest priority, Secondary priority Adjust as the lowest priority , , The optimal number of refrigeration units is obtained when refrigeration performance and energy efficiency are balanced. When the highest security is required, As the highest priority, with Secondary priority E Adjust as the lowest priority , , The optimal number of refrigeration devices is obtained when the highest safety is achieved.

8. The design method for a multi-split refrigeration system according to claim 1, characterized in that, In step S1, the compressor is selected according to the design operating conditions. When any of the following conditions occur, the compressor is selected as a variable frequency compressor; otherwise, the compressor is selected as a fixed frequency compressor: 。 9. An electronic device, characterized in that, The system includes a processor, an input device, an output device, and a memory, which are connected in sequence. The memory is used to store a computer program, which includes program instructions. The processor is configured to call the program instructions to execute a multi-channel refrigeration system design method as described in any one of claims 1 to 8.

10. A readable storage medium, characterized in that, The storage medium stores a computer program, which includes program instructions that, when executed by a processor, cause the processor to perform a design method for a multi-channel cooling system as described in any one of claims 1 to 8.

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