Characteristics of the Heat Transfer Associated with Water Jet Impingement onto Structured surfaces

Abstract

Experimental investigations have been conducted on hot horizontal stainless-steel flat plate by sub-cooled liquid water. The cooling rates have been studied on different parameters such as initial temperature (between 350°C and 450°C), coolant temperature (degrees of sub-cooling between 20°C and 70°C), jet velocity (Vj = 1.85, 4.11 and 6.4 m/s) and surface shape (flat, groove1, groove2, square groove).The coolant was impinged from single jet with diameter Dj= 4 mm to the center of the specimen. The jet was 10 cm above the specimen in the vertical direction. It was noticed that increasing the initial temperature, decreasing ΔTsub, decreasing the jet velocity leads to decrease the cooling curve slope, Heat flux and the single phase heat transfer is lagged Also the film boiling took longer time. Increasing the slope of the boiling curve and heat flux are the main purpose of the structured surface modification. So artificially modified surfaces are fabricated with using milling machine and their performance in enhancing surface heat flux and surface temperature cooling curve are measured. Structured surfaces increased the cooling curve sloop and heat flux.