Constructal entransy dissipation rate minimization for "volume-point" heat conduction at micro and nanoscales

A "volume-point" heat conduction model with rectangular element at micro and nanoscales is reoptimized by taking the minimization of 'entransy' dissipation rate as optimization objective. The optimal constructs of the model with local optimization and global optimization constructal design methods under the effect of size effect are obtained. The results show that the size effect has remarkable effects on the optimal construct of the model. For the local optimization constructal design method, the optimal constructs of the rectangular second order assembly based on the minimizations of the entransy dissipation rate and hot spot temperature are different. The optimal construct of the rectangular second order assembly based on the minimization of entransy dissipation rate can reduce the average temperature difference better than that based on the minimization of the hot spot temperature, and improves the heat transfer ability simultaneously. The global heat transfer performances of the rectangular assemblies are evidently improved by adopting the global optimization constructal design method. The rectangular heat conduction model at micro and nanoscales is more generalized, and the results obtained by the constructal optimization of this model include those not only at micro and nanoscales but also at conventional scale. (C) 2014 Energy Institute. Published by Elsevier Ltd. All rights reserved.