基于燃气轮机的板翅式换热器特性分析及结构优化

Characteristic Analysis and Structure Optimization of the Plate-Fin Heat Exchanger in a Gas Turbine

针对微型燃气轮机板翅式换热器结构参数与燃气轮机性能之间的耦合关系,建立了板翅式换热器多目标分析和优化模型。在此基础上,分析了2种设计条件(定燃烧室吸热量和定涡轮出功)下板翅式换热器关键参数对板翅式换热器和燃气轮机性能的影响。结果表明:影响燃烧室吸热量和涡轮出功的主要因素为换热器压损而并非换热器效能,2种设计条件下各参数的变化趋势一致(除燃烧室吸热量和涡轮出功外);在对翅片结构进行优化后,涡轮出功增大了6.8%,燃烧室吸热量减少了5.1%;相对于基本参数,优化后翅片厚度、翅片间距和波纹角减小,翅片高度增加,保证了板翅式换热器具有较小的压损;采用[火积]耗散最小和采用熵产最小为优化目标时无明显区别。

A multi-objective analysis and optimization model was established for the plate-fin heat exchanger in a micro gas turbine, based on the coupling relationship between the structural parameters of the heat exchanger and the performance of the gas turbine. On that basis, the effects of key exchanger parameters on the performance of both the heat exchanger itself and the gas turbine were analyzed under two operating conditions(constant heat absorption in the combustion chamber and constant power output of the gas turbine). Results show that the main factor influencing the power output and heat absorption is the pressure loss but not the effectiveness of the heat exchanger. The variation trend of all parameters in above two operating modes keeps consistent(except for the heat absorption and power output). After optimization of the fin structure, the turbine power output is increased by 6.8%, and the heat absorption of combustion chamber is decreased by 5.1%. Compared with the original parameters, the optimized fin thickness, fin spacing and corrugation angle decrease, while the fin height increases, thus ensuring a small pressure loss of the heat exchanger. At the same time, it is found that there is no significant difference in the results when minimum entransy dissipation and minimum entropy production are taken as the optimization objectives.