Numerical And Experimental Investigation Of Flow And Heat Transfer In Primary Surface Recuperators

For saving the fuel and increasing the efficiency of gas turbine cycle, recuperator is used to warm-up the air entering the combustion of gas turbine by absorbing the heat of exhaust in recuperation cycle. It makes the efficiency of cycle 10% higher and even more by using recuperated cycle. Recuperator, as the key part in recuperated cycle, plays the important role in efficiency increasing of gas turbine. It must be a kind of recuperator which has small volume, light weight, high recuperated effectiveness and high reliability for using on micro gas turbine. Investigation indicates that the CC type primary surface recuperator (PSR) can satisfy these demands, so it's the preferred structure of recuperator of micro gas turbineModeling software Gambit is used to model the three units of PSR under different cross angles and the 0° entire flow passages PSR. Numerical simulation software Fluent is used to simulate the flow and heat transfer in these models and the periodic boundary condition is used to simplify the model and simulate the fully developed flow field. Simulation results indicate that the flow in 0° unit is typical laminar flow, but in 60° and 120° units, the turbulence of flows caused by cross angle 6 is observed obviously and it's much stronger in 120° unit. These evidence explained why both heat transfer and pressure loss are getting higher and higher from 0°, 60° to 120° unit.The heat transfer coefficients and pressure loss of entire flow passage at the cross angle of 60° and 120° are predicted based on the simulation of three units under the different Tw and 0° entire flow passages. Larger cross angle 6 can make heat transfer coefficient bigger but also bring the higher pressure loss, so it must be careful to choose the cross angle 6 in designing the PSR.The experiments of 120° PSR are conducted. Meanwhile, the machining method of PSR is explored. Two schemes of PSR are designed and the key technique of machining is discussed. The experiment data is acquired and the results are compared with the simulation results. The modification indicates that the influence of leakage and dissipation heat loss on experiment results is considerable.