Design and test of smart heat exchanger based on shape memory alloys

For heat exchangers in an aero-engine, additional valves with sensors control the performance of heat exchangers to match the operating conditions. However, these valves and sensors bring extra weight and volume. To remove these parts, a smart heat exchanger based on shape memory alloy is developed in this study, whose heat transfer capacity can automatically vary with the requirement. The smart heat exchanger has two typical working modes. The heat exchanger will be composed of straight subchannels to provide low flow resistance (standby mode), whereas the heat exchanger can transfer to latticework channels when the heat transfer requirement is high (high-performance mode). The flow and heat transfer characteristics of the smart heat exchanger are studied by both experiments and numerical simulations. The Reynolds number varies from 500 to 5,500 in this research. The results show that the heat exchanger can save 70% pump power in standby mode, while 80% heat transfer capacity enhancement will be achieved in high-performance mode. Moreover, the effect of the Reynolds number on transition status is similar to the two typical modes. The best thermal performance is observed when the Reynolds number is around 3,000 for all working states.