空气标准等温加热修正Brayton循环:(1)功率效率特性分析

Air Standard Isothermal Heating Modified Brayton Cycle:(1)Analysis on Power and Efficiency Characteristics

在已有文献建立的闭式等温加热修正定常流式Brayton循环模型基础上,提出了一种新的五分支Brayton循环,即空气标准等温加热修正Brayton循环,并运用有限时间热力学理论建立了内可逆空气标准等温加热修正Brayton循环模型,导出了其功率效率表达式,分析了最大温比和预胀比对功率与效率、功率与压缩比和效率与压缩比特性关系的影响,以及传热损失对功率与效率特性关系的影响,并将修正后的Brayton循环性能与传统的Brayton循环性能进行了对比。结果表明:循环功率与效率的关系曲线呈扭叶形,而功率与压缩比和效率与压缩比的关系曲线均呈类抛物线形;随着预胀比和循环温比的增加,循环性能明显提升;与传统的Brayton循环相比,修正后的循环性能更优。

A new five-branch Brayton cycle,namely air standard isothermal heating modified Brayton cycle,was proposed based on the closed isothermal heating modified steady flow Brayton cycle model established in previous literatures.An endoreversible air standard isothermal heating modified Brayton cycle model was established using finite time thermodynamic theory.The expressions of power and efficiency were derived,and the effects of the maximum temperature ratio and pre-expansion ratio on the characteristics of power and efficiency,power and compression ratio,efficiency and compression ratio,as well as the effect of the heat transfer loss on the characteristics of power and efficiency were analyzed.The performance of the modified Brayton cycle was compared with that of the traditional Brayton cycle.The results showed that the relationship curve between cycle power and efficiency was loop-shaped,while the relationship curve between power and compression ratio and that between efficiency and compression ratio were parabolic-like;with the increase of the pre-expansion ratio and the cycle temperature ratio,the performance of the cycle improved significantly;the performance of the modified Brayton cycle was better compared with that of the traditional one.