Experimental study on water boiling heat transfer characteristics of microchannel surface in distributed jet array impingement with effusion slots

Distributed jet array impingement can improve the uneven temperature distribution and achieve high heat flux cooling. This paper experimentally investigated the two-phase heat transfer and pressure drop characteristics in a distributed jet array impingement on the microchannel surface. The test operating conditions were mass flux of 100 ∼ 200 kg/m²s, subcooling degree of 20 ∼ 40 K, jet-to-target spacing of 2 ∼ 4 mm, and atmospheric pressure at the outlet. The experimental results show that lowering subcooling from 40 K to 20 K enhances the heat transfer coefficient between 45.4 % and 57.2 % and a growth in the average pressure drop of 25.5 %. Increasing mass flux causes inlet and outlet pressure to fluctuate more sharply due to enhanced condensation. The pressure drop of single-phase forced convection and that of two-phase nucleated boiling display an opposite trend as mass flux increases. Reducing jet-to-target spacing to 2 mm exhibits a noticeable enhancement in pressure drop of more than 2.5 times, and the standard deviation of inlet pressure declines instead, indicating that decreasing jet-to-target spacing can attenuate flow instability. The coefficient of performance can be raised by increasing subcooling and jet-to-target spacing and reducing mass flux in the whole heat flux range. Expanding jet-to-target spacing from 2 mm to 4 mm can produce 105.5 % to 141.7 % higher the average coefficient of performance.