壁面加热热流密度对微柱群内部换热特性的影响

采用实验与数值模拟相结合的方法研究去离子水在不同加热热流密度下流过叉排排列微柱群内部时工质热物性对对流换热的影响规律.实验中采用电加热棒对一体化微柱群散热元件进行加热,测得不同加热功率下微柱群内部努塞尔数(Nu);同时建立考虑粗糙度影响的三维数学模型模拟了该实验段在不同热流密度下的温度场与换热特性,并与实验结果进行了对比.研究发现:工质热物性随着温度变化对微柱群换热特性有着较为明显的影响,且数值模拟结果略高于实验值;对流换热系数均随加热热流密度增加而略有增大,且低雷诺数(Re)下该现象更为明显;定义了不同的影响因子来对各热物性参数的影响进行定量分析,发现动力黏度对微柱群内换热特性影响最大,影响因子接近10%.

Influence of Wall Heat Flux on Heat Transfer Characteristics in Micro-cylinder-groups

Influence of thermal physical properties variation of de-ionized water with different heating flux on heat transfer characteristics in staggered arranged micro-cylinder-groups were experimentally and numerically investigated.The integrated micro-cylinder-group chip was heated by heating elements and the Nusselt number(Nu) was obtained by measuring temperatures in micro-cylinder-group chip.Besides,a 3-D numerical model considering the roughness effect on inner surfaces of micro-cylinder-groups was used to simulate the temperature fields and heat transfer characteristics with different heating flux.By comparing the calculation results with the experimental results,it was found that the thermal physical properties of working fluid changed with the temperature,and this variation brought out apparent influence on heat transfer characteristics in micro-cylinder-groups.In addition,the heat transfer coefficient was enhanced by increasing the heating flux,especially at low Reynolds number(Re).Different affecting coefficients were defined to quantitatively analyze the influence of thermal physical properties,and it was found that the affecting coefficient of viscosity was nearly 10%,which was much higher than that of the other properties.