AN EXPERIMENTAL STUDY OF FLOW BOILING HAT TRANSFER IN A MICRO CHANNEL

Abstract

The need for compact, efficient, robust and integrated electronic cooling has given way for the development of microscale cooling techniques. Liquid forced convection with and without phase change in microchannels is an effective cooling option for high performance electronics. Micro-channel liquid cooling is the subject that has been studied extensively by many researchers, but there remains controversy over the mechanism involved in the microscale dimensions. To design effective micro heat sinks, it is necessary to know the relationships among key design parameters such as pressure required to pump the cooling liquid, flow rate, heat transfer rate, and temperatures of the liquid and the channel wall. Therefore, fundamental understanding of fluid flow and convection heat transfer in microchannels is required. The experimental studies in the literature showed that many- phenomena in microscale flow and heat transfer cannot be explained by conventional theories of transport phenomena. Though, the capabilities of microchannel cooling system as an efficient cooling system have been recognized, the understanding of flow behavior on a microscale, has not yet been fully explained. In the endeavour to find optimal cooling solution for electronic devices, microscale cooling technique employing microchannels has emerged as an exciting new field both for researchers and packaging engineers. Much research has undergone in this area which gave new findings and understanding of flow and heat transfer phenomena at microscale. The present experimental study is an attempt to study the various heat transfer and pressure drop phenomena in the microchannels used specifically for cooling of electronics by developing an experimental facility. In the process of developing such facilities we have incorporated some of very innovative ideas to make the things feasible. III The experimental study involves studying the influence of various heat inputs and flow rate on heat transfer and flow characteristics of water flowing through the microchannel of 508 μm ID. The study was aimed to understand the heat transfer characteristics and pressure drop at heat inputs ranging from 12.7 to 80.6 W/cm2. the flow rate of water ranged from 3.15 ml/min to 4.8 ml/min. The Reynold number ranged between 243 to 515. IV