In the present study, 3 dimensional numerical analysis of helically coiled tube is carried out using commercial CFD tool ANSYS CFX 12.1. It is very difficult and time consuming if these analyses could be carried out experimentally and hence in the present work, efforts are taken to optimize the helically coiled tube with respect to heat transfer and flow parameters for various coil pitch. Analysis of heat exchanger is done using conjugate heat transfer. The 3-dimensional flow through the helically coiled tube is considered which would overcome the anisotropic flow properties that would arise due to complex turbulence phenomenon and flow deviations. The flow field through the helically coiled tube is simulated by solving the appropriate governing equations: conservation of mass, momentum and energy. The turbulence is taken care by Shear Stress Transport (SST) k-ε model of closure. SST k-ε has a blending function which acts as standard k-ε in the main stream flow and as Standard k-ωl near the boundary layer where the gradient is much steeper. The numerically predicted results are compared with the experimental data available in the literature and a very good agreement exists between the experimental and numerically predicted data. © 2006-2014 Asian Research Publishing Network (ARPN).