Study on the flow boiling characteristics of novel pin fin heat sinks in a two-phase mechanically pumped cooling loop

Abstract

As a new thermal control technology, a two-phase mechanically pumped cooling loop (MPCL) holds promise in addressing cooling issues of avionics. The heat sinks in MPCL can remove heat from avionics to refrigerant. Since previous research focused primarily on conventional heat sinks, three novel pin fin heat sinks (PFHSs) were investigated based on an MPCL. With increasing heat flux, heat transfer coefficient (HTC) and frictional pressure drop (FPD) increase. With the inlet state from subcooled to saturated and then to two-phase, HTC and FPD increase. Increasing inlet saturation temperature yields an increase in HTC and heating wall temperature (Tw). An increase in flow rate inhibits heat transfer deterioration while inducing significant growth in FPD. When heat flux is below 150 kW/m2, the petaloid I PFHS has the best temperature control performance, while the honeycombed PFHS has the best FPD. When heat flux exceeds 150 kW/m2, HTC decreases rapidly after reaching the peak. Increasing average vapor quality leads to a slight decrease in Tw but an increase in FPD. When heating load is started, flow rate decreases and Tw and pressure drop increase significantly, but they can gradually stabilize. These findings have significant implications for optimizing the MPCL.