The performance analysis of reversed Carnot cycle and reversed <italic>p</italic>-<italic>V</italic> cycle

Abstract

A reversed thermodynamic cycle is a cycle which consumes mechnical work and moves heat energy from a source with lower temperature to a source with higher temperature, and the coefficient of performance (COP) is generally applied to describe its performance. It has been widely accepted that within a certain temperature range, the reversed Carnot cycle has the best performance, i.e., it has the biggest COP. However, in this article it has been concluded that the COP of the reversed Carnot cycle is not the biggest within a certain temperature range from three different methods. Besides, a new reversed cycle is constructed in this article, which is called the reversed p-V cycle inspired by the derivation of Carnot cycle. The analysis presents that within the same temperature the COP of reversed p-V cycle is far larger than the COP of the reversed Carnot cycle. From this cycle it can be seen that the mechanical work also has the concept of quality, which is reflected by the pressure of the work source in the cycle. thermodynamic cycle, reversed Carnot cycle, coefficient of performance, Stirling cycle

Symmetry of reversible thermodynamics

“…根据正逆循环的对称性, 相对于正循环的卡诺循 环和卡诺定理, 提出在两个压力源下工作的逆p-V循环 及可逆逆循环的性能定理 [30,31] , 现简述如下: 卡诺循环 含有两个等温过程和两个等熵过程, 因而含有两个热 源和无穷多个功源. 逆p-V循环则是由两个等压过程与 图 5 (网络版彩色)各类输入输出对循环性能影响示意图 Figure 5 (Color online) Sketch of influences on the system performance by different inputs and outputs 1) 压缩空气制冷循环可采用回热, 但它的主要目的并不是改变制冷量, 而是减小压缩比 [25] .…”

“…它具有两个功源, 同 时为了保证工质与外界的热量交换过程为可逆过程, 需要有无穷多个热源与工质逐次接触. 这样构成的热 力正循环, 在现有文献中有时亦被称为矩形循环 [32,33] , 其对应的逆循环在本文作者先前的研究中被称为逆p-V循环 [30] . 正循环热效率η h 的定义是输出的净功量与输入总 热量之比, 如式 2…”