The present thesis is a part of an ongoing project at Leonardo S.p.A, which focuses on improving the preliminary design phase of an aircraft Thermal Management System. The underlying need of this work stems from the urgent imperative to reduce the environmental impact of aviation, which leads to the implementation of innovative and sustainable technological solutions. In particular, the transition toward more electric propulsion systems significantly alters the onboard energy balance. As electrical power demand increases and conventional hydraulic and pneumatic systems are progressively replaced, the number and density of onboard heat sources rise accordingly. Consequently, thermal management becomes a critical design driver, requiring advanced strategies to ensure efficient heat dissipation, system reliability, and overall aircraft performance.