An experimental and numerical study of cooling by air/water mist jet impingement at low mist loading fraction

Abstract

The air/water mist jet impingement phenomenon on a flat target with constant heat flux has been studied experimentally and numerically. The effects of various operational variables on the heat transfer characteristics of the mist jet have been analyzed through an experimental study. These variables are the air Reynolds number (Re_a = 5305–10297), the mist loading percentage (f = 0 %–1.5 %), and the nozzle-to-plate spacing ratio (H/D_o = 20–40). Additionally, the computational study investigates the effects of the nozzle ratio parameter (D_i/D_o = 0.1–0.3) and droplet diameter (2 μm–100 μm) on mist jet impingement. A comparison between Eulerian-Eulerian and Eulerian-Lagrangian modeling techniques for simulating the air/water mist jet has been provided. The current computational findings based on the Eulerian-Eulerian method accord well with the experimental data, with an accuracy of 15 %; however, numerical predictions using the Eulerian-Lagrangian approach deviate significantly from the experimental results, with errors of up to 65 %. The increase in Re_a results in a greater improvement in the stagnation point Nusselt number, up to 85.32 %, compared to 34.99 % with an increase in f. Furthermore, a rise in f causes a greater spread of the mist jet flow in the domain and on the target impingement surface than an increase in Re_a. When D_i/D_o increases from 0.1 to 0.3, the stagnation point Nusselt number increases by approximately 55.67 %. In addition, the spread of the mist jet flow in the domain increases as the D_i/D_o ratio increases. Experimental correlations have been developed based on studied parameters for calculating the Nusselt number values on the flat target.