Research On Data Center Thermal Management Based On Phase Change Material/pulsating Heat Pipe Coupling Module

With the continuous development of electronic technology,the heat dissipation power and heat dissipation density of electronic devices are increasing.The conventional air-cooling system is insufficient to supply cooling capacity for high-performance cabinets with the increase in the power density.To ensure the cooling requirement and reduce the energy consumption of the data center lead to considerable challenges to the thermal management of a data center.In solve these problems,this paper proposed a new cooling method for electronic devices by using phase-change materials coupled with three-dimensional oscillating heat pipes.Combined with theoretical method,numerical method,and experimental method,the heat transfer mechanism,heat transfer performance,and energy-saving characteristics of the oscillating heat pipe were studied at the component level.The data center thermal evaluation was performed at the system level.The pressure-veloctiy model was optimized,the airflow and temperature distributions were studied seriouly.This paper provides a research basis for data center thermal management,energy conservation,and evaluation.Firstly,a number of theoretical models including equivalent thermal resistance,equivalent thermal conductivity,driving force and thin film evaporation model are derived in the research,and various factors such as sensible heat transfer,phase change heat transfer and expansion work are fully considered.The heat pipe heat transfer mechanism was studied based on the theoretical model.The theoretical model is transformed into a correlation with velocity,which can provide empirical formula using visual experiments.Secondly,a multi-function test platform was built to study the performance of oscillating heat pipes in data center environment.The experimental investigation on the heat transfer performance of oscillating heat pipes was carried out,and the optimal design parameters of oscillating heat pipes with different structures were obtained.A new type of three-dimensional oscillating heat pipe was designed based on the flow structure found in nature and its thermal performance under different air supply directions was studied in detailed.The results show that the leaf-shaped three-dimensional pulsating heat pipe achieves the best cooling performance when the wind direction is parallel to the petiole.Thirdly,a new cooling method using phase-change material coupled with three-dimensional oscillating heat pipe was proposed for electronics cooling,which can effectively solve the problems of high contact thermal resistance of oscillating heat pipe and low thermal conductivity of phase change material.Combined with the optimized design of three-dimensional oscillating heat pipe,the cooling effect of phase change material/leaf-shaped oscillating heat pipe coupling module was studied firstly.The results show that the phase change material/leaf-shaped oscillating heat pipe coupling module achieves the best cooling performance when the air supply direction is parallel to the petiole direction.The cooling effect is optimal and higher than the typical three-dimensional oscillating heat pipe.Then the cooling effect of three-dimensional oscillating heat pipes with different working fluids coupled with phase change materials was studied.The results show that the three-dimensional oscillating heat pipe using methanol as the working fluid with a filling ratio of 34% has the best cooling performance,which reduces the thermal resistance by approximately 50% compared with the traditional underfloor air distribution system.The temperature of electronic devices were greatly decreased as a result.The cooling performance of the PCM/3D-OHP module was studied by proposing a thermal resistance model for the phase change material/three-dimensional pulsating heat pipe coupling module.Based on the model,the empirical formulas of the thermal resistance of the module under different air supply speeds and supply air temperatures are fitted.The module is used as an auxiliary heat sink to save electricity of 186 kwh per year while reducing the thermal resistance of 42.5% to ensure that the temperature of the electronic device does not exceed the recommended maximum junction temperature.Finally,at the system level,a typical data center was built,the thermal evaluation system was proposed including a regional thermal evaluation index to study the feasibility of energy lending.It provides mathematical method for the design of distributed load and auxiliary heat dissipation.Then the airflow characteristics of the static pressure plenum were studied,an empirical formula of the resistance loss coefficient of the orifice plate was obtained.Based on the formula,the one-dimensional ideal pressure-velocity coupling model was optimized.The optimization method of airflow and temperature distribution in room-level and cabinet-level model was studied by using CFD method,and various improvement were proposed.