IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308 _______________________________________________________________________________________ Volume: 03 Issue: 12 | Dec-2014, Available @ http://www.ijret.org 103 EXPERIMENTAL & NUMERICAL STUDY OF FORCED CONVECTION LAMINAR FLOW THROUGH COPPER MICRO CHANNEL HEATSINK S.Subramanian 1 , K.S.Sridhar 2 , C.K.Umesh 3 1 Microwavetube Research & Development center, Jalahalli, Bangalore, India 2 PESIT, 100 feet Ring Road, BSK III Stage, Bangalore, India 3 University visvesvaraya college of engineering, KR Circle, Bangalore, India Abstract A rectangular micro channels having 500 microns width & 1500 microns depth have been machined out of Oxygen free high conductivity Copper material on an area of 12.5mm X25mm. De-ionized water was used as a coolant. The thermal & fluid flow performances have been tested for the flow velocities ranging from 0.5m/s to 1.2m/s. Micro channels performances have been numerically simulated using commercially available computational fluid dynamics software ANSYS CFX. The simulated results have been validated with the experimental results and published literature. The effects of Temperature dependent material properties on simulation have been examined. Keywords: Metallic micro channels, Single phase laminar flow cooling, Thermal performance of micro channels, Electronics cooling --------------------------------------------------------------------***---------------------------------------------------------------------- 1. INTRODUCTION Metallic micro channels are widely opted due to its mechanical robustness and the higher value of heat transfer coefficient per unit coolant flow. Thermally high conductive materials such as silicon, aluminium & copper are generally preferred for the manufacture of metallic micro channels. Initially, the works of D.B Tuckerman & R.F.W Pease[1] brought the attraction on silicon substrate based micro channels. They had achieved a thermal resistance of 0.09 o C/W over one cm 2 area and had tested upto 790W/cm 2 . The substrate temperature rise was 71 o C above water inlet temperature. Various manufacturing processes like LIGA, Chemical etching, Stereo lithography, Micromachining & Diffusion bonding had been reported to be suitable for micro channel fabrication by Sean Asman et al [2]. Fabrication and testing of a micro channel cooling plate which is meant for microelectronic packaging cooling applications have been described by A. J. Pang', M.P.Y. Desmulliez et al [3]. The nickel-based micro-channel cooling plate was fabricated on a glass substrate using a two-layer electroforming process borrowed from the UV-LIGA process. Forced convection of air was used for the micro channel plate. The cooling plate was tested using a custom- made rig to measure the pressure head as a function of mass flow rate. Eason et al 2004 [4] investigated various manufacturing methods for micro channels fabrication, such as wet & dry etching in silicon, as well as precision mechanical sawing in silicon & thermo-set plastic. They described the experimental methods used for measuring the pressure flow characteristics of the manufactured channels. Both analytical [6-8] and numerical [9] methods were frequently used for the investigation of micro channels. A novel integral micro-channel heat sink was fabricated, directly on the back-metallization layer of copper brazed with ceramic substrate of the semiconductor junction by Fanghua Mei et al,[10]. Lijubisa D stevanovic et al,[11] reported that the micro channels manufactured by micro milling techniques performed better than laser ablated samples due to dimensional distortion. Ngotan Tran et al,[12] manufactured a rectangular cross section micro channel having 500 μm width and 210 μm depth using micro machining techniques. The heat sink was tested using water as coolant for the mass flow rates varying from 0.2 to 0.4 g/s. The pressure drop was reported to vary from 1761 to 4184 Pa. Generalized correlation [13] for predicting nusslets number in the thermally developing region has been developed using three dimensional numerical simulation. Temperature dependent material property models [14] have been used for three dimensional numerical simulation of oblique & plate fin types of micro channel heat sinks. The micro channels were cut on copper and were tested for the flow with Reynolds number ranging from 400 to 800. The simulated resulted have been validated with experimental results. Particularly the use of copper helps in spreading the heat uniformly around the micro channel, closely approximating the theoretical assumptions. Hence it is pertinent to study the copper based micro channels as it has potential use in electronics cooling. In this paper the thermal & fluid flow performance of copper based micro channel heat sink with a hydraulic diameter of 0.75mm have been studied numerically & experimentally. Experimental tests were performed for different flow rates where the reynolds number varied from 503 to 1197. The results were compared with the published data. The results of the simulation using the temperature dependent material properties are also presented.