基于广义原理的对流换热热阻计算方法及检验

Convection thermal resistance calculation method and validation based on generalized theory

使用积耗散与广义热阻原理分析对流换热中耗散与广义换热温差间的关系,提出了控制体内三种广义热阻值计算方法的表达形式,并在二维平行通道层流换热中进行检验,与传统热阻计算方法作比较后发现传统的表面传热系数不能准确体现研究区域内的热导(阻)能力,三种广义热阻计算方法的表达形式相互吻合,结果一致,且对流换热退化为热传导时与定义式和热传导计算结果统一,表明是可靠的对流热阻计算方法;使用该方法研究二维平行通道内入口段的对流换热,发现广义热阻值的普遍趋势是随流动发展热阻增大,符合对流换热的基本理念,定义式热阻则表现变化很大,受温差与壁面热流量影响明显;检验中发现了广义式热阻与定义式热阻的差异是由于定义式热阻为简化表达导致。

The entransy dissipation and generalized thermal resistance theory is utilized in researching dissipation and generalized transfer temperature difference in convection.Three computing forms of heat transfer resistance for control volume is proposed and validated by two-dimensional laminar convection in parallel channels.Traditional surface heat transfer coefficient does not accurately reflect the thermal conductivity(resistance)capabilities of control volume while compare with it.The generalize resistance method is reliable for two reasons,first is that three forms of expression consistent with others perfectly, second is that the thermal resistance consistent with conduction while convection degenerate to conduction. The validation of convection in parallel flow shows that the basically general trend of generalized thermal resistance increases with flow development,consistent with basic idea of convective heat transfer.On the while,the definition style of thermal resistance does not increase with flow in several circumstance and influenced by temperature and transfer quantity obviously,due to the definition type simplify the expression of thermal resistance construction.