In the present book rectangular microchannel was fabricated and Graphene nanoplatlets nanofluid was prepared with different concentrations. The fluid flow and heat transfer analysis has been performed by both simulation & experimentation. The objective of the work is to study and analyse the Graphene nanoplatlets nanofluids considering different volume concentration of nanoparticles with varying flow parameters related to the flow field in rectangular microchannel for cooling. Based upon the analysis, the custom nanofluid and its use with the microchannel setup have been proposed. The effect of using these fluids on heat transfer coefficient, Nusselt number and Reynolds number has been studied. The CFD analysis for all these parameters was carried out in COMSOL multiphysics module. Further simulation model was validated via numerical tests and comparisons with benchmark experimental data sets.