Application of exergy analysis to various psychrometric processes
Application of exergy analysis to various psychrometric processes
复制标题
DOI：
10.1002/er.933
复制
发表时间：
2003-10
影响因子：
4.6
通讯作者：
B. A. Qureshi;S. Zubair
中科院分区：
文献类型：
--
作者：
B. A. Qureshi;S. Zubair
功和熵生变化之间的关系源于第一和第二定律的同时处理，即可用能分析。在本文中，我们讨论了热力学分析的各种湿法过程使用的概念。对每个过程进行了参数化研究，以确定第二定律效率随质量流量、相对湿度和温度的变化。其他趋势，如温度随相对湿度的变化，也在适用的情况下显示。不可逆损失是通过在每个系统上应用一个能量平衡来计算的。在这方面，使用了工程方程求解器（EES）程序，这是独一无二的，因为它具有大多数热力学和输运性质的内置函数；不需要近似方程。在计算空气和水蒸气混合物的流动用能时，采用了热力部分和化学部分之和作为总用能的概念。研究表明，在某些过程中，增加进入气流的相对湿度可以提高第二定律效率。我们注意到，在绝热混合的情况下，新鲜空气（第二流）的质量流率的降低降低了该过程的第二定律效率。此外，还表明，在所研究的范围内，水和蒸汽的质量流量与相对湿度几乎呈线性关系。版权所有©2003 John Wiley & Sons， Ltd
The relation between work and changes in entropy generation arises from the simultaneous treatment of the first and second laws referred to as exergy (or available energy) analysis. In this paper, we discuss thermodynamic analysis of various psychrometric processes using the concept of exergy. A parametric study of each of the processes is carried out to determine the variation of second‐law efficiency as a function of mass flow rate, relative humidity and temperature. Other trends such as variation of temperature with relative humidity are also shown where applicable. Irreversible losses are calculated by applying an exergy balance on each system. In this regard, an engineering equation solver (EES) programme is used, which is unique because it has built‐in functions for most thermodynamic and transport properties; removing the need for approximate equations. The concept of total exergy as the sum of thermomechanical and chemical parts is employed in calculating the flow exergies for air and water vapor mixtures. It is shown for some processes investigated that an increase in the relative humidity of the incoming air stream increases second‐law efficiency. We notice that a decrease in mass flow rate of fresh air (second incoming stream) in the case of adiabatic mixing decreases the second‐law efficiency of the process. Also, it is shown that the mass flow rate (of both water and steam) has almost a linear relationship with relative humidity in the range investigated. Copyright © 2003 John Wiley & Sons, Ltd.