热漏对热机功率效率特性的影响分析

An Analysis of the Power Versus Efficiency Characteristics of Heat Engines with Different Heat Leak

在以往文献的基础上,对定常态流不可逆卡诺热机的热漏模型进行了改进,将热机热漏分为外热漏和内热漏两种方式,分析两种热漏方式对不可逆热机最优性能的影响。分析得出内热漏对热机功率效率特性的影响不同于外热漏,也与摩擦,涡流和非平衡等各种不可逆效应不同,内热漏应单独作为影响热机特性的一种因素。并导出存在热阻和两种热漏损失的热机存在最佳功率和最佳效率两种工作状态,两种工作状态分别对应不同的面积比。所得结果对热机设计具有一定指导意义。

This paper presents a irreversible Carnot engine model in which heat leak is divided into external heat leak（ device heat leak） and internal heat leak（fluid heat leak）. The model is different from the so-called ＂irreversible cycle＂ models provided by some other authors. The influence of the two kinds of heat leak on the optimal performance of heat engine is analyzed. This paper points out that the influence of internal heat leak on the power versus efficiency characteristics of heat engines is different from that of external heat leak and is also different from that of other internal irreversibilities, such as friction, turbulence etc. Heat engine with different heat leak exists two kinds of optimal working state, the optimum power and optimum efficiency cann＇ t be attained at the same heat-transfer solace-area ratio. Numerical examples illustrate the effectiveness of the new medal and some useful results are drawn.