Enhanced flow boiling heat transfer with jet impingement on micro-pin-finned surfaces

摘要

Experiments were conducted to study the performance of subcooled flow boiling heat transfer with jet impingement of FC-72 over silicon chips (10 × 10 × 0.5 mm~3). Four kinds of micro-pin-fins with dimensions of 30 × 60, 30 × 120, 50 × 60, 50 × 120 μm~2 (thickness t× height h) were fabricated on the chip surfaces by using the dry etching technique. The experiments were made at two different liquid subcooling (25℃ and 35℃), three different crossflow velocities V_c (0.5, 1,1.5 m/s) and three different jet velocities V_j (0,1, 2 m/s). A smooth surface was also tested for comparison. The results show that both the microstructure and impingement give a large enhancement on heat transfer. The maximum allowable heat flux increases with the velocity and liquid subcooling. For a fixed V_c, the enhancement degree increases with V_j especially for V_c = 0.5 m/s, V_j = 2 m/s. As V_c increases, the heat transfer enhancement of jet impingement weakens and the increase rate of CHF (the critical heat flux) also decreases. The largest value of q_(max) (the maximum allowable heat flux) can reach 167 W/cm~2 for chip with the fin dimension of 50 × 120 μm~2 at the condition of V_c = 1.5 m/s, V_j = 2 m/s and liquid subcooling of 35℃.