Novel Thermal Management for Airborne Radar Systems : An Investigation on the Feasibility to use Metal Alloys as Phase Change Materials for Electronics Cooling

Sammanfattning

This thesis investigates the feasibility of using metal alloys as phase change material (PCM) for thermal management in airborne radar systems. Due to the increasing power density and miniaturization of electronic components, efficient heat dissipation is a critical challenge, especially in an aircraft’s electronic system(avionics), where environmental and structural constraints limit conventional cooling methods. Metallic PCMs as an indirect contact cooling approach is explored to store thermal energy during high-load operation. When the materials reach the melting point and begin to melt, a significant amount of thermal energy is absorbed. In an optimal scenario, there is no increase in temperature during the melting process, providing a cooling effect. Three different metal alloys with varying thermal conductivities and melting points were evaluated as PCMs through numerical simulations using ANSYS Fluent. Four geometric concept configurations were analysed. The concepts impact on thermal distribution, hot spot tempera-ture and melt progression were determined. The results show that the integration of PCM into the existing cooling system enabled the absorption of approximately 30 % of the total heat generated. This resulted in a lower average temperature of the entire domain. The use of an aluminum lid between the heat source and PCM resulted in minimal temperature reduction at the hot spot. Instead, changing the material of the lid to copper led to approximately 32 °C reduction of hot spot temperature. This reduction extended the duration of flight roughly 30 seconds for the airborne radar system. Additional design enhancements, such as the inclusion of thermal fins, provided modest improvements in heat transfer and contributed to structural reinforcement. While the modifications resulted in a weight increase of 20–40 %, the overall thermal management performance was significantly enhanced. To verify the numerical simulations, a prototype of the simulation model was constructed which proved successful. Indicating that the simulation models and the results presented in this thesis are valid. These outcomes demonstrate the opportunities of PCM-based cooling strategies for electronic cooling and offer Saab valuable insights for future development of thermal management techniques.