Abstract: Ejector-type pressure recovery system plays an important part in the application of chemical lasers. For improving ejector efficiency and reducing system size, an important method is to reduce the temperature of gas mixture out from laser cavity. The feasibility of implementing this method using heat exchanger through numerical simulation is investigated. The thermophysical properties of gas mixture are calculated first, and then modeling methods and numerical simulation conditions are given here. Based on the comparison of heat exchanger performances in different simulation conditions, it is found that the heat transfer efficiency and pressure drop are much smaller than that in common industrial heat exchanger. That's because the density of gas mixture is too low. To enlarge tube size and