Experimental Study of Quenching Progression on a Heated Flat Dimpled Surface with Water Jet Impingement

Abstract

Quenching progression on a flat surface and heat transfer enhancement with an impinging jet over smooth and dimpled surface modification is presented in this manuscript. With rapid advancements in today’s electronic, electrical, and mechanical systems, the need for the removal of the associated heat generation rates is also increasing. Achieving that by jet impingement provides an economical and fast solution. A smooth flat plate is quenched repeatedly from three different initial temperatures of 300,350 and 400° C. The results in terms of re-wetting parameters viz., Re-wetting temperature, and wetting delay are reported. Parallelly, the effect of the hemispherical dimpled (array) surface with a pitch of 3 mm, and diameter of 2 mm with varying depths of 0.5 mm(d/t=10) and 1mm(d/t=5) are studied. The results are then compared to that of a smooth surface. Water is used as a coolant at a temperature of 17 ±2°C. A large deviation in results is reported when the plate surface was subjected to repeated trials due to a change in the metallurgical properties of the surface. The results of a dimple depth of 0.5mm show a higher heat transfer rate as compared to that of both the smooth surface and the dimple depth of 1 mm. A maximum of 40% and a minimum of 26% enhancement in heat transfer rate is reported for dimple depth 0.5mm compared to 1mm. Further, a 59.76% of heat transfer efficiency was recorded for the experimental setup and this efficiency was found to be increasing with an increase in the water pump pressure.

Keywords

• jet impingement
• rewetting temperature
• flow boiling
• heat transfer augmentation
• wetting front