Experimental study on the heat transfer performance of a phase change material based pin-fin heat sink for heat dissipation in airborne equipment under hypergravity

Abstract

Phase change material (PCM) based heat sinks are expected to cool airborne equipment effectively. However, aircraft often perform hypergravitational maneuvers, and heat transfer performance under hypergravity remains unclear, especially for pin-fin heat sinks (PFHSs). In this paper, experiments on the melting behaviors of n-docosane based PFHS and empty heat sink (EHS) were conducted under hypergravity of 0–6 g. The results reveal that hypergravity affect the melting process significantly and differently, but the effect weakens with increasing hypergravity. The heating wall temperature under hypergravity no greater than that without hypergravity. For EHS, the complete melting time decreases with increasing hypergravity, while for PFHS, this time increases, indicating that the heat transfer enhancement due to pin-fins is counteracted by their inhibition of heat convection of liquid PCM under hypergravity. For PFHS, the maximum difference in the complete melting time under hypergravity versus without hypergravity is 15.9%; for the corresponding heating wall temperature, the maximum difference is 8.6%; and for EHS, these differences are −18.4% and −17.5%. For a large heat flux, the complete melting time is shortened by adding pin-fins at any hypergravity, while for a small heat flux, this time is extended from a specific hypergravity. Moreover, the dip angle of liquid level and the width of unsubmerged area on the heating wall increase with increasing hypergravity, which might result in overheating damage, and more studies under wider ranges of hypergravity, heat flux and materials are needed to eliminate this damage.