Effects of pin-finned array and porous surface on two-phase confined jet-impingement cooling

Two-phase boiling heat transfer can improve the performance of array jet cooling in higher heat flux density heat dissipation situations. Based on the promotion of phase transformation by ribbed structure, two kinds of ribbed surfaces were proposed. Related experimental research on the heat transfer and flow characteristics of the optimized heat sink were carried out. The two ribbed surface structures are: smooth cutting pin fins (SL1), rough needle ribs coated with sintered porous layer (SL2). The pin fins are all 0.6mm×0.6mm×1mm (length× width × height), and for SL2 the particle sizes ranging between 120μm and 150μm with a thickness of about 2 times the particle diameter. The distributed array orifice plate constitutes a 5×5 jet unit, each unit corresponding to a 4×4 pin fin array. The total heat source area is 30mm×30mm and the total number of pin fins is 400. Anhydrous ethanol was used as the working fluid. The boiling curves and heat transfer curves of the heat sink were obtained at the fluid flow rate of 2.6-12.7mL/s and the inlet temperature of 283-313K. The results showed that the two pin-finned structures can effectively realize the transition from single-phase forced convection heat transfer to two-phase boiling heat transfer. Increasing the inlet temperature or reducing the fluid flow rate can effectively promote the phase transition. When using the same fluid flow rate and temperature, SL1 has better single-phase heat transfer performance than SL2. With the increase of heating heat flux density, SL2 can achieve subcooled boiling at lower wall superheat and better heat transfer characteristics, but SL1 achieves higher critical heat flux. © 2019, Chemical Industry Press. All right reserved.