Study On The Optimization Of PCHE Regenerator For Micro Gas Turbine

In the context of energy saving and emission reduction,micro gas turbines are increasingly used in various fields due to their various advantages,and the installation of regenerators with high thermal efficiency and low pressure loss can greatly improve its efficiency.The printed circuit heat exchanger(PCHE)is a highly efficient and compact heat exchanger,and the airfoil channel PCHE has better flow and heat transfer performance than other channel types of PCHE.This article aims to optimize the channel structure of the thermal core and the flow distribution structure in the head to obtain better flow and heat transfer performance of PCHE.In this thesis,the physical model of the airfoil channel PCHE is simplified,a local fluid geometric model is constructed,and the reliability of the numerical model is verified using ANSYS 19.0.Through numerical simulation and comparison study,it is proved that the flow and heat transfer performance of the airfoil channel PCHE is better than that of the Z-shaped channel PCHE which is currently widely used.Using heat transfer coefficient,pressure drop per unit length and compactness coefficient as performance indicators,explored the effect of airfoil channel structure parameters(arc height,the maximum position of arc height,thickness,horizontal spacing,longitudinal spacing)on the flow heat transfer performance of the airfoil channel PCHE.The response surface method was used to design a three-factor and six-level test plan,and the values of three performance indicators were obtained by numerical simulation.The correlation between the performance indicators of the cold or hot channel and the channel structure influence factor was obtained through multivariate nonlinear fitting.The significance of the influence can be obtained by the coefficient of each influence factor.The multi-objective optimization of each factor for three performance indicators is performed to obtain the Pareto optimal boundary of the hot and cold channel.It is considered that under the working conditions of the micro gas turbine,the cold side airfoil is NASA 1312,the lateral spacing is 4mm,and the longitudinal spacing is1 mm,while the hot side airfoil type is NASA 3313,the horizontal spacing is 3mm,and the longitudinal spacing is 1mm,the flow and heat transfer performance of the airfoil channel PCHE is the best.We can observe the fluid flow in the head through the velocity cloud diagram,and draw a conclusion that the flow and heat transfer performance of the simplified airfoil channel PCHE model is increasing with the decrease of the flow unevenness coefficient α at the inlet,and when α≤0.7,the flow uniformity hasn’t have significant effect on the flow and heat transfer performance of PCHE.Comparing the flow distribution effect of the three types of orifice plates of 3×3,4×4,and 5×5,it is found that when the 3×3 orifice plate is installed in the head,the fluid can reach the state of α=0.7 when the distance is the shortest(Z=150mm).At this moment,the heat transfer coefficient of PCHE is increased by 22.46% and the pressure drop per unit length is reduced by 47.2% compared to when no orifice plate is installed in the head.