层流对流换热中的势容耗散极值与最小熵产

在一定的约束条件下,存在一个最优的速度场,它能够使得温度场和速度场的协同程度最好,从而使得对流换热的整体传热性能达到最优。目前对传热效果的评价存在熵产最小化和势容耗散取得极值两种不同的准测。分别根据这两种优化准则,用变分方法推导了在粘性耗散一定的条件下,稳态无内热源的层流对流换热的场协同方程,并对方腔内对流换热问题进行了优化。数值计算结果表明,势容耗散取得极值时的换热效果优于熵产最小的结果,因此势容耗散极值原理更适合做为对流换热的优化准则。

POTENTIAL CAPACITY DISSIPATION EXTREMUM AND ENTROPY GENERATION MINIMIZATION IN LAMINAR CONVECTIVE HEAT TRANSFER

Under some constraint condition, there is an optimum velocity field which can make the synergy between temperature and velocity field, so as to optimize the whole capability in convective heat transfer. At present, entropy generation minimization and potential capacity dissipation extremum are the two principles to value heat transfer performance. Under the condition of constant viscous dissipation, the field synergy equations are induced for steady laminar convective heat transfer by the variational principle to optimize convective heat transfer in square cavity. The numerical results show that heat transfer rate obtained by potential capacity dissipation extremum is better.