闭式简单燃气轮机循环生态学有效功率特性

Ecological Efficient Power Characteristics of Closed Simple Gas Turbine Cycle

内可逆闭式简单燃气轮机循环(Brayton循环)模型是基于有限时间热力学理论和已有文献建立的热力学循环模型。以生态学有效功率为优化目标,研究了该循环的性能特性,导出了生态学有效功率的表达式,分析了不同热源温比下该循环的无因次生态学有效功率与压比、效率和无因次功率的关系,比较了该循环的生态学有效功率与其他多个目标函数的性能差异。结果表明:无因次生态学有效功率与压比和效率的关系呈类抛物线型,存在最优压比使无因次生态学有效功率最大;无因次生态学有效功率与无因次功率的关系呈扭叶型,任一给定的无因次生态学有效功率值都对应2个无因次功率值,实际设计时,热机应选择功率较大的工况点;如果将热源温比提高,则无因次生态学有效功率及其目标下的无因次功率、效率和最佳压比均提高;追求生态学有效功率以牺牲热机的部分功率来提升循环的热效率,可大幅度降低熵产率。研究成果可以为Brayton循环热机的设计和优化提供参考。

The endoreversible closed simple gas turbine cycle(Brayton cycle)model is a thermodynamic cycle model based on finite time thermodynamic theory and existing literature.The cycle performance characteristics were studied with the ecological efficient power being taken as the optimization objective.The mathematical expression of ecological efficient power was deduced,and analysis was done on the cycle's relations among dimensionless ecological effective power and pressure ratio,efficiency and dimensionless power under various heat reservoir temperature ratios,accordingly,the performance distinctions of the ecological efficient power of the cycle from many other functions with different objective combinations were compared.The results demonstrated that the relation curve of dimensionless ecological efficient power versus pressure ratio and efficiency was parabolic-like,and there was an optimal pressure ratio to maximize the dimensionless ecological effective power;the relation curve of the dimensionless ecological efficient power versus the dimensionless power characteristic was loop-shaped,and for any given dimensionless ecological effective power value,there would be two dimensionless power values,so in actual design of the heat engine,the high-power working point should be chosen;with the cycle heat reservoir temperature ratio increased,the dimensionless ecological efficient power would be correspondingly raised,so would the dimensionless power,efficiency and optimal pressure ratio under its optimization objective;ecological efficient power could improve the thermal efficiency of the cycle by sacrificing part of the power of the heat engine,and could greatly reduce the entropy production rate.The research results can provide reference for the design and optimization of Brayton cycle heat engine.