不可逆往复式变比热工质Brayton循环性能分析

Performance Analysis of Irreversible Reciprocating Brayton Cycle with Variable Specific Heat of Working Fluid

对不可逆往复式Brayton循环的有限时间热力学性能进行模型研究.在考虑工质变比热及压缩和膨胀过程的内不可逆损失基础上,导出了循环比功和循环热效率的解析表达式.在典型循环特性参数条件下,对上述模型进行了数值计算.研究结果表明,工质变比热及压缩和膨胀过程的内不可逆损失对循环性能有一定影响,其中压缩和膨胀过程的内不可逆损失对循环性能影响更显著.研究结果对实际内燃机性能的评估及改进有一定的指导意义.

The mathematical model for finite-time thermodynamics characteristics of an irreversible reciprocating Brayton cycle is analyzed.The analytical formulas of the specific work and the actual cycle thermal efficiency are derived by taking the variable specific heats of working fluid and the losses of internal irreversibility in the compression process and the expansion process into account.The model mentioned above is carried on the numerical calculus under typical circulation performance parameters.The research results show that the variable specific heat and the efficiencies of the losses of internal irreversible compression and internal irreversible expansion through the cylinder have a certain influence on the cycle performance , and the losses of internal irreversibility in the compression process and the expansion process through the cylinder have more remarkable influence on the cycle performance.The research results can provide a theoretical guide for the assessment and improvement of the performance of actual internal combustion engines.