Analyses of an air conditioning system with entropy generation minimization and entransy theory

Abstract

In this paper, based on the generalized heat transfer law, an air conditioning system is analyzed with the entropy generation minimization and the entransy theory. Taking the coefficient of performance (denoted as COP) and heat flow rate Q out which is released into the room as the optimization objectives, we discuss the applicabilities of the entropy generation minimization and entransy theory to the optimizations. Five numerical cases are presented. Combining the numerical results and theoretical analyses, we can conclude that the optimization applicabilities of the two theories are conditional. If Q out is the optimization objective, larger entransy increase rate always leads to larger Q out , while smaller entropy generation rate does not. If we take COP as the optimization objective, neither the entropy generation minimization nor the concept of entransy increase is always applicable. Furthermore, we find that the concept of entransy dissipation is not applicable for the discussed cases.

Uniformity principle of temperature difference field in heat transfer optimization*

“…It is also very clear that the entransy dissipation minimization gives the minimum value of Eq. (43). When the optimization objectives in these systems are obtained, we have shown that the heat transfer temperature differences are uniform.…”

Role of entropy generation minimization in thermal optimization

“…For the two objectives, research showed that the applicability of the EGM is also conditional. [21,38] The effects from different heat transfer laws were analyzed, [38] and the conclusions still hold.…”

Analyses of entropy generation and entransy for a Stirling cycle system based on generalized heat transfer law

“…该原理表明, 在满足一定条件时, 系统的最大 损失 对 应 于 系 统 的 最 大 输 出 功 . 该 原 理 已 在 卡 诺 循 环 [29,44,49,51,56] 、热泵系统 [23,52] 以及奥拓循环 [53,54] 等多 种热力学系统中获得应用. 但与此同时, 也存在对 理 论科学性和应用价值的质疑, 认为 理论与熵理论在 热力学分析中并无区别 [57] .…”