摘要
根据有限时间热力学理论,分析了变温热源条件下不可逆回热式等温加热修正Brayton循环的功率、效率的全局特性和最优特性。研究发现,计入外部传热不可逆性后,分别存在最佳的循环压比使得循环无因次输出功率和效率取得最大值,而且,一般来说,前一最佳压比更大;回热对循环的输出功率影响极小,对循环效率的提高也只在较低压比时起作用;为提高循环的输出功率和效率,常规燃烧室(RCC)有效度、RCC中热源的入口温度和热容率应取较小的值,而收敛型燃烧室(CCC)有效度、CCC中热源的入口温度和热容率应取较大的值。详细讨论了循环热力参数对最大无因次输出功率及其对应的最佳压比和效率、最大效率及其对应的最佳压比和无因次输出功率的影响,指出了已有文献的错误。研究结果对燃气轮机装置的评估和最优设计具有一定的指导意义。
The global and optimal characteristics of power and efficiency of an irreversible regenerated modified Brayton cycle with isothermal heat addition coupled to variable - temperature reservoirs are analyzed by using finite-time thermodynamics. The results indicate that there exist optimal cycle pressure-ratios respectively, which lead to maximum dimensionless power output and maximum efficiency, and the former optimal pressure-ratio is always larger than the latter one in general, with the consideration of irreversibility of external heat transfer. It is also concluded that the effect of regeneration process on the dimensionless power output is less significant and only at the small cycle pressure-ratio can regeneration process improve the cycle efficiency. It is also found that the effectiveness of regular combustion chamber （ RCC）, the inlet temperature ratio and the heat capacity rate of heat reservoir in RCC should be relative larger value and the effectiveness of converging combustion chamber （CCC）, the inlet temperature ratio and the heat capacity rate of the heat reservoir in the CCC should be relative smaller value for the enhancement of dimensionless power output and efficiency. The effects of thermodynamic parameters of the cycle on the maximum dimensionless power output and corresponding optimal pressure-ratio and efficiency, the maximum efficiency and corresponding optimal pressure-ratio and dimensionless power output are discussed in detail and the overs!ghts of previous literature are pointed out. The results obtained herein can provide some guidelines for the evaluation and optimal design of gas turbine plant.
出处
《热力透平》
2013年第2期112-118,共7页
Thermal Turbine
基金
国家重点基础研究发展计划(973)项目(2012CB720405)
国家自然科学基金(10905093)
关键词
有限时间热力学
等温加热修正Brayton循环
功率特性
效率特性
finite-time thermodynamics
modified Brayton cycle with isothermal heat addition
power characteristic
efficiency characteristic
