Experimental Study of HFE-7000 Flow Boiling Heat Transfer and Pressure Drop in a Mini Channel Heat Sink for High-Power Defense Applications

Computing technology demands high-performance cooling systems for defense applications due to the high-power consumption. While controlling temperature distribution and flow fluctuations under high heat flux conditions presents a significant challenge, there exist limited experimental analyses addressing the impact of flow boiling heat transfer on temperature distribution and flow patterns within uniformly heated microchannels. The primary objective of this study is to dissipate elevated heat fluxes using two-phase flow boiling of dielectric fluid. The experimental investigation focuses on flow boiling heat transfer performance in a multi-channel Aluminum heat sink with 8 hotspots subjected to uniform heating. The flow boiling of HFE-7000 engineered fluid at the mass flux of 500 kg/m²s was investigated in a mini channel with a cross-section of (14 x 3 mm²) divided into three regions by two subchannels and machined staggered elliptical pins with 3mm height (No tip clearance) on each hotspot and distribution pins at the channel inlet. The collected data from temperature and pressure sensors and flow rate were used to assess the heat transfer performance during the experiments. Additionally, High-Speed Camera recordings of flow visualization were analyzed to investigate variations in the heat transfer coefficient along the length of the channel. The temperature and flow instabilities were discussed for the input power of 678 W.