翼型通道换热器在燃机系统中流动换热性能的数值研究

Numerical Study on Flow and Heat Transfer Performance of Airfoil Channel Heat Exchanger in Gas Turbine System

为提高动力循环性能,将印刷电路板式换热器(printed circuit heat exchanger,PCHE)应用于间冷回热燃气轮机循环,采用数值模拟方法对变物性烟气和水在翼型通道内的流动换热性能展开研究。基于热力学第一定律与第二定律分析翅片横向和纵向间距对流动传热性能的影响,通过正交实验分析各个因素的影响权重并提出传热流动关联式。结果表明,两种工质下,换热器的综合性能随着纵向间距的增大而提高。当工质为水时,随着横向间距的减小,PCHE的综合性能提高,而当工质为烟气时,横向间距在2.4~3.6mm之间的综合性能最佳。传热强化和速度与温度梯度之间协同作用的增强密切相关,增大横向间距和纵向间距可以有效减少换热过程中的不可逆损失。不同横向和纵向间距会影响边界层的发展,进而影响换热器的流动换热性能。研究结果对在燃气轮机循环中翼型印刷电路板式换热器的优化设计具有一定的指导意义。

In order to improve the power cycle performance,a printed circuit heat exchanger(PCHE)is applied to the intercooled recuperated gas turbine.The flow and heat transfer performance of variable physical properties of flue gas and water in the airfoil channel of the printed circuit heat exchanger is numerically studied.Based on the first and second laws of thermodynamics,the influence of the lateral and longitudinal pitches of fins on the flow and heat transfer performance is analyzed.The influence weights of various factors are analyzed by orthogonal experiments,and the heat transfer and flow correlations are proposed.The results show that the comprehensive performance of the printed circuit heat exchanger increases with the increase of the longitudinal pitch under the two working fluids.When the working fluid is water,the comprehensive performance of the heat exchanger increases with the decrease of the lateral pitch.The comprehensive performance of the heat exchanger with the lateral pitch of 2.4~3.6mm is best for the flue gas.The heat transfer enhancement is closely related to the synergistic effect between the velocity and temperature gradient.Different longitudinal and lateral pitches could affect the development of the boundary layer,thereby affecting the flow and heat transfer performance of the heat exchanger.Increasing the lateral and longitudinal pitches could effectively reduce the irreversible loss in the heat transfer process.The present work could provide guidance for the optimal design of airfoil printed circuit board heat exchanger in gas turbine cycle.