预热型S-CO_(2)布雷顿循环(火用)效率分析与优化  

Exergy Efficiency Analyses and Optimization of Preheated S-CO_(2) Brayton Cycle

作　　者：金晴龙 夏少军[1] 王超[1] JIN Qinglong;XIA Shaojun;WANG Chao(College of Power Engineering,Naval University of Engineering,Wuhan 430033,Hubei Province,China)

机构地区：[1]海军工程大学动力工程学院,湖北省武汉市430033

出　　处：《中国电机工程学报》2023年第3期1072-1083,共12页Proceedings of the CSEE

基　　金：国家自然科学基金项目(51576207,51976235)。

摘　　要：预热型超临界二氧化碳布雷顿循环在燃气轮机余热回收应用领域中具有较高的发展潜力,对其开展性能分析与优化研究具有重要意义。应用有限时间热力学理论,建立变温热源条件下存在有限温差传热、不可逆压缩、不可逆膨胀等不可逆因素的预热型超临界二氧化碳布雷顿循环模型,并对其进行数值模拟;分析工质质量流率、压缩机和透平效率、压比、换热器热导率以及分流系数对循环(火用)效率的影响;在总热导率一定的约束下,以(火用)效率最大为目标对预热器、加热器、回热器和冷却器的热导率分配比进行优化。结果表明:随着工质质量流率的增大,可通过降低加热器和回热器热导率、提高冷却器和预热器热导率的方式提升循环(火用)效率,且在考虑4个换热器热导率分配比的情况下,(火用)效率最大所对应的工质质量流率范围在92~95kg·s^(-1),功率可达到11.8~12.05MW;经由优化后,循环(火用)效率相比于初始设计点可提高17%以上,其所对应的循环热效率可达到34%以上,循环净功率可达到10.98MW以上。模型具有一定的普适性,研究结果可为实际工程装置的设计与运行提供理论指导。The preheated supercritical carbon dioxide Brayton cycle has a high development potential in the application of gas turbine waste heat recovery, and it is of great significance to carry out its performance analysis and optimization. Based on the theory of finite time thermodynamics, a preheated supercritical carbon dioxide Brayton cycle model with the irreversibility factors of finite temperature difference heat transfer, irreversible compression,irreversible expansion under the condition of variable temperature heat source is established and simulated by numerical methods. Then, the influences of the working fluid mass flow rate, compressor and turbine efficiencies, pressure ratio, the thermal conductance of heat exchangers and shunt coefficient on cycle exergy efficiency are analyzed. Moreover,under the constraint of a total heat exchange inventory, the heat conductance distribution ratios of the preheater, the heater, the regenerator, and the cooler are optimized for the maximum exergy efficiency. The results show that with the increase of the working fluid mass flow rate, the cycle exergy efficiency can be improved by reducing the thermal conductance of the heater and the regenerator, and increasing the thermal conductance of the cooler and the preheater;the working fluid mass flow rate for the maximum exergy efficiency is in the range of 92~95kg·s^(-1)considering the thermal conductance distribution ratios of the four heat exchangers, and the net power output could reach 11.80~ 12.05MW. The cycle exergy efficiency after optimization could be improved by more than 17% compared with the initial design point, the corresponding cycle thermal efficiency could reach more than 34%, and the cycle net power output could reach more than 10.98MW. The model in this paper has a certain universality and the obtained results can provide theoretical guidance for the design and operation of actual engineering devices.

关 键 词：预热型超临界二氧化碳布雷顿循环 有限时间热力学 (火用)效率 

分 类 号：TK115[动力工程及工程热物理—热能工程]