Exergy Analysis of a Semicircular Microchannel Heat Sink at a Fixed Heat Input

Abstract

— In this paper exergy efficiency or second law efficiency of a semicircular microchannel heat sink of diameter (350 micron) has been analysed for three different inlet temperatures of deionized water (19^oC, 23.5^oC, and 28.6^oC) at an ambient saturation temperature of 29^oC by varying mass flow rate from 0.006 kg/s to 0.028 kg/s and exit vapour quality from 0.1 to 0.9 at a fixed heat input of 72 W. It has been observed that exergy efficiency decreases with increase of mass flow rate with a maximum decrement of 17.05% for inlet temperature of 28.6^oC because of the rise in average surface temperature at higher flow rate of the test section when pressure drop is fixed. Exergy efficiency has been found to be increase with pressure drop, pumping power and exit vapour quality while at higher pressure drop, pumping power and vapour quality exergy efficiency becomes uniform when mass flow rate is fixed.

Keywords- Exergy efficiency, Semicircular microchannel,heat sink, Surface temperature, Mass flow rate,  Fixed heat input