不可逆狄塞尔热机输出功、效率及其参数优化

建立不可逆狄塞尔热机循环新模型。探索不可逆绝热过程对热机循环性能的影响，应用有限时间热力学方法．导出了输出功和效率与压力比、高低温比间的解析表式．揭示了这些重要热力学参量问的变化特性．研究结果表明，随着绝热不可逆程度的增大，输出功及效率均明显减小；输出功和效率随压力比的变化在一定范围内存在极大值．而输出功随高低温比的增大而单调增大．通过数值计算，还讨论了包括热机压力比、输出功和效率等优化工作区域及其界限、所得结论可为一类内燃机的最佳运行条件和优化设计提供理论参考．

Optimization on the Work Output, Efficiency and Other Performance Parameters of an Irreversible Diesel Heat Engine

A new cyclic model of irreversible Diesel heat engine is proposed. The influence of irreversible adiabatic processes on the cyclic performance of the engine is explored. By using the method of finite time thermodynamics, the relations among the work output, efficiency and the pressure ratio, high low temperature ratio are derived and the characteristics of these important thermodynamic parameters are revealed. It is shown that as the adiabatic irreversibility increases,the work output and efficiency significantly decrease and the work output and efficiency have their extremal values for the pressure ratio in some region,but the work output is monotonic increasing function of the high-low temperature ratio. By means of numerical calculation, the optimal operating ranges and bounds of the pressure ratio,work output,efficiency for the engine are further analyzed and discussed. The conclusions obtained here may provide some theoretical guidance for the optimal operating condition and the optimal design of a class of internal combustion engines.