Air-to-fuel heat exchanger for high mach flow turbine engines

In pursuit of gas turbine engines that are capable of meeting the requirements of high Mach propulsion applications, cooling the engine cooling air with engine fuel is an important area of technology development. Several heat exchanger designs have been proposed to extract the heat from the cooling air with varying degrees of success. This study focuses on the testing and analysis of a new multi-pass modular heat exchanger, where the modules are arranged in an annular configuration. In the process of analyzing the heat exchanger, a theoretical model was developed that could be applied to heat exchangers of various sizes and other design envelopes. To confirm the accuracy of the theoretical heat exchanger model, the newly designed heat exchanger was represented by a single module that was tested experimentally and analyzed theoretically. First, an experimental facility was designed and constructed to test the heat exchanger module under simulated engine conditions. Air and water were used as working fluids through a 1.52 cm (0.6 in) wide and 6.6 cm (2.6 in) long module that incorporated both micro-channel liquid passages and short airside fins. Simultaneously, the theoretical model was constructed to predict the heat transfer and temperature drop across the heat exchanger module for each fluid stream. With these tools in place, comparisons were made between experiment and theory, which showed good overall agreement in heat transfer rate and exit temperatures. This study shows the theoretical model is a reliable foundation for predicting the performance of heat exchanger modules under actual fuel and air turbine engine conditions