Experimental study on heat transfer in forced convective boiling with a submerged wall jet flow

Boiling is highly effective for cooling applications due to its ability to dissipate high heat fluxes at low temperature differences. In this study, the wall jet flow boiling over plain and coated surfaces using deionized water at atmospheric pressure has been experimentally investigated. The scalable coated surface was developed using thermal spray coating method. The effect of wall jet velocity and surface to nozzle distance were examined. The wall jet flow enhances the heat transfer performance in the low heat flux regime for both surfaces. At higher heat fluxes, the boiling curves for different jet velocities coincide and they overlap the pool boiling curve for both surfaces. Hence, it can be concluded that nucleate boiling predominantly governs the heat transfer in this regime. However, The wall jet flow significantly delays the CHF limit for both surfaces, which shows a linear relationship with wall jet velocity. At a wall jet velocity of 2 m/s, the plain surface exhibited 1.8 fold increase in HTC and 2.1 fold enhancement in CHF, while the coated surface achieved 3.2 fold and 2.7 fold improvements in HTC and CHF, respectively, compared to 56.4 kW/m²K and 1167.3 kW/m² obtained for the pool boiling over the plain surface.