Heat Transfer Enhancement in Air by Means of Acoustics in Microgravity Conditions

Abstract

On Earth, electronic circuits dissipate heat through convective flows driven by gravity, transferring energy from devices to the environment. In microgravity, the absence of buoyancy disrupts this mechanism, causing heat accumulation and potential damage. Here, we present an experimental study on enhancing heat transfer in air in microgravity via acoustic actuation. The setup consists of a test cell and subsystems for heat generation, acoustic actuation, and data acquisition. Experiments were conducted in five drops at the ZARM Drop Tower in Bremen (Germany), each providing 9.3 seconds of microgravity. Thermocouple data and high-speed videos were recorded per drop. We analyzed temperature evolution at different positions from the heat source and heat distribution inside the test cell using the Background Oriented Schlieren technique. Qualitative and quantitative results show that acoustic actuation distributes heat over larger regions, strengthening with increased pressure amplitude. Temperature increased when actuated at resonance frequency, with heat transfer along the actuation direction increasing at a rate of 0.44 K/s. Results confirm that acoustic actuation improves heat transfer in microgravity, likely due to convection-like flows induced by acoustic streaming. This study provides a foundation for new cooling techniques applicable to satellites and spacecraft.