Aero-Thermo Analysis of a Waste Heat Recovery Heat Exchanger

Abstract This study investigates the aerothermal performance and flow dynamics of a heat recovery heat exchanger for the WET cycle concept. A combined experimental and numerical approach is used to assess how flow turning influences heat transfer and pressure losses. The heat recovery unit comprises a radially distributed tube bank, with a length in excess of two meters, downstream of the turbine exhaust. The tested 30 degree sector, consists of 860 tubes. The selected heat recovery design, with the exhaust gases radially turned 90 degrees and flowing through the tubes, results in a highly non-uniform flow posing significant challenges for accurate performance assessment. The experimental evaluation was conducted at Chalmers University using a 1:1 scale model operating under engine representative conditions. Numerical RANS simulations were performed at GKN Aerospace Sweden using ANSYS Fluent on a computational domain of 65 million cells, with a detailed in-tube model for heat transfer evaluation. The overall aerothermal performance shows good agreement between experimental and numerical results; however, at a detailed level, notable discrepancies are identified. The effect of baffle spacing on flow stability and pressure loss distribution is discussed in detail. This study highlights the potential of the combination of relatively simple experimental configurations in combination with detailed numerical simulations provide insights into non-standard HEX configurations.