Abstract—A 3D-conjugate numerical investigation was conducted to predict heat transfer characteristics in a rectangular cross-sectional micro-channel employing simultaneously developing Tow-phase flows. The sole purpose for analyzing two phase flow heat transfer in rectangular micro channel is to pin point what are the different factors affecting this phenomenon. Different methods and techniques have been undertaken to analyze the equations arising constituting the flow of heat from gas phase to liquid phase and vice versa. Different models of micro channels have been identified and analyzed. How the geometry of micro channels affects their activity i.e. of circular and non-circular geometry has also been reviewed. To the study the results average Nusselt no plotted against the Reynolds no has been taken into consideration to study average heat exchange in micro channels against applied heat flux. High heat fluxes up to 140 W/cm2 were applied to investigate micro-channel thermal NOMENCLATURE H : Channel height, μm Cp : Specific heat, kJ/kg K Dh : Hydraulic diameter, μm K : Thermal conductivity, W/m K L : Channel length, mm Nu : Nusselt number (Nu = hDh/k) Nuave : Average Nusselt number q¨ : Heat flux, W/m2 Re : Channel Reynolds Number (Re = ρuDh/μ) T : Temperature, K U : Velocity, m/s W : Channel width, μm X : x-coordinate, mm Y : y-coordinate, mm Z : z-coordinate (axial distance), mm Greek Symbols α : Channel aspect ratio (α = b/w) ρ : Density, kg/m3 μ : Dynamic viscosity, Ns/m2 Subscripts Avg : Average I. INTRODUCTION HE significance of micro-channels substantially grew because of their high-level heat exchange coefficient and diminishing size. Micro-channels submit amplify heat Ahmed Jassim Shkarah, Mohd Yusoff Bin Sulaiman, MdRazali bin HjAyob are with Faculty of Mechanical Engineering, Universiti Teknikal Malaysia Melaka (UTeM), Melaka, Malaysia (e-mail: ahmedshkarah@gmail.com). transferring surface and bigger surface area to volume ratio facilitating a higher heat exchange per unit of volume than the channels of usual sizes. Heat exchange in micro channels attracted much limelight due to their impending in many practical applications like lowering temperature of powerful microelectronics, biomechanical and aerospace applications as well. The geological requirements of the channel are remarkably influential on convection heat exchange features leading to the outline of an efficiently micro create important parameters like the shape of the channel, diameter of hydraulic, channel quantity, material of channel, the working fluid and it’s flow rate along with few other distinctive parameters. This is to be taken into account extracting the accurate possible values of these parameters to ensure the system is effective and cost efficient. The growth in development of micron sized devices is increasing the depth of understanding the thermal as well as hydrodynamic features of flow occurring in micron sized tubes and micron sized channels. The setbacks are taken into account that is associated with conducting experiments in the micro-channel specifically for micro geometries. This is another reason why it is suitable to develop dependable numeric models that demonstrate the flow and also the heat in the micro channels. These numeric models provide significant description of combined effect of the drop in pressure and thermally sensitive performance. So, these models can be used for optimizing the fluidic micro systems without the fabrication of apparatus and the experimental data. The ever increasing development in the production of micro-channel systems, specifically in the field of the MEMS i.e. the Micro Electro Mechanical Systems, have resulted in the creation of exclusive and distinctive devices of mechanical importance as well as electromechanical importance, only on a thin layer of silicone. These MEMS are generically explained as units having a distinctively minute length of 1 mm and just 1µm. They are heat exchanging units, micro-channel reactors, micro-channel sensors, micro-channel pumps that are used for printers, blood analyzing units, laser diode, environmental testing and so on. [1], [2] The two phase flow constituted in micro-channels sink is essential for analyzing its utility to science and technology like micromechanical, electromechanical systems, electronic cooling process, chemical engineering, genetics, bio engineering and many more [3]. Various arenas of the two- phase flow and exchange of heat in micro channel heat sink has been studied, [4]-[7]. Lee has efficiently studied the heat exchange characteristics of the Two-phase flow of micro channel heat sink and published a letter [4] The use of R134a as a flowing fluid under controlled heat flux was used ( Analysis of Boiling in Rectangular Micro Channel Heat Sink Ahmed Jassim Shkarah, Mohd Yusoff Bin Sulaiman, Md Razali bin Hj Ayob T characteristics. Keywords—Two Phase flow, Micro channel, VOF. World Academy of Science, Engineering and Technology International Journal of Mechanical, Aerospace, Industrial and Mechatronics Engineering Vol:8 No:4, 2014 784 International Science Index Vol:8, No:4, 2014 waset.org/Publication/9998801