Abstract
A taper microgap is a wedge-shaped cavity placed over a heater surface for enhancing pool and flow boiling heat transfer. Extensive experimental, numerical, and theoretical investigations show that the tapered microgap augments vapor bubbles and liquid movement to enhance critical heat flux and heat transfer coefficient. The current work studies the effect of bubble squeezing with simulated air flow where a bubble grows near the diverging end of a 5° tapered microgap. The bubbles are air-injected at flowrates of 3, 15, and 30 ml/min, and their movement is studied numerically and validated experimentally using a newly developed Arduino Mega 2560-based electromechanical test bench. Qualitative experimental testing validates the numerical method and finds air-injected bubbles leaving from the diverging end of the tapered microgap while drawing working fluid in its wake. In an actual heat transfer system equipped with a tapered microgap, the drawn working fluid will create a flow-like macroconvective current over the heater surface that enhances heat transfer. Results from the current study can be used to expedite tapered microgap development.
