Research On Heat Dissipation Characteristics Of Two-phase Circuit Driven By Scraper Pump In Outdoor Electric Control System Of Air Conditione

The size of the new electronic chip is getting smaller and smaller,the integration is getting higher and higher,and the heat flux density of the electronic chip is also increasing.A large amount of heat is concentrated on the electronic chip,which can easily lead to overheating damage of the electronic chip.The two-phase heat transfer technology controlled by the mechanical pump absorbs a large amount of heat based on the principle of gas-liquid phase change to dissipate heat.It is a research hotspot in the field of heat dissipation and is mostly used in the aerospace field.However,there are few applications and researches in the outdoor electronic control system of air conditioning.In this paper,a two-phase loop system driven by scraper pump is designed to dissipate heat from outdoor chips.The heat dissipation performance of the system is analyzed by numerical simulation and experimental comparison,which provides a reference for the application of pump-driven heat dissipation system in the field of air conditioning.The main contents of this paper are as follows.(1)The scraper pump is introduced and the flow characteristics of the scraper pump are studied.The theoretical average flow model of the scraper pump was established.The theoretical formula of the instantaneous flow of the elliptical rotor scraper pump was derived by using the area sweep method.The relationship between the flow pulsation rate,the area utilization coefficient and the elliptical axis ratio parameters was analyzed.With the increase of the elliptical axis ratio of the rotor,the flow pulsation rate gradually increases from 100 % to 200 %,and the area utilization coefficient gradually decreases from 100 % to 0.Aiming at the problem of large flow pulsation rate of a single elliptical rotor pump,a solution of two pumps in parallel is proposed.When the phase difference between the two pump rotors is π / 2,the flow pulsation rate is reduced to 33 %,which can effectively solve the problem of large flow pulsation rate of a single scraper pump.(2)According to the characteristics of the two-phase flow model,the relevant theoretical models and control equations are described,including multiphase flow model,turbulence model,evaporation and condensation model,etc.The finite element analysis model of the cold plate and chip virtual prototype and Fluent software is established.The inlet velocity is 0.1m / s,and the inlet temperature is313.15 K.The temperature characteristics,gas volume fraction distribution characteristics and pressure drop characteristics of the system are simulated and analyzed.(3)According to the existing air conditioning commonly used refrigerant usage,respectively,using R134 a and R410 A as the cooling medium in the cold plate,select the saturation temperature is313.15 K,the inlet flow rate is 0.3m / s to carry on the numerical simulation,the results show that the refrigerant for R410 A cooling effect is best;when the inlet temperature is 313.15 K,the heat dissipation is analyzed when the inlet flow rate is 0.2m / s ～ 0.5m / s,and it is concluded that the flow rate of 0.4m / s is the most suitable for heat dissipation.Considering the influence of temperature on the physical parameters,the polynomial fitting of the physical parameters of the refrigerant is carried out when analyzing the influence of the inlet temperature on the heat dissipation effect of the system.The results show that the inlet velocity of 0.4m / s can meet the heat dissipation requirements of the ambient temperature of 308.15 K ～ 323.15 k,and under the condition of a certain inlet velocity,the maximum temperature of the chip increases linearly with the inlet temperature.(4)A cooling plate heat dissipation experimental platform with R410 A as the refrigerant and an elliptical rotor scraper pump as the pump source was built.The relationship between the inlet flow rate of the cooling plate,that is,the output flow rate of the scraper pump,and the cooling performance of the cooling plate was tested.It is concluded that the chip temperature gradually decreases with the increase of the inlet velocity.The maximum temperature of the chip was monitored and compared with the simulation data under the condition of inlet velocity of 0.4m / s,inlet temperature of 313.15 K and system operation of 200 s.The results show that although the experimental data fluctuate,the trend is the same as the simulation results,which verifies the accuracy and effectiveness of the simulation model.