The complete design and fabrication of the parallel and counterflow heat exchanger were done. And the calculations of the double pipe heat exchanger have been done. - From the study the following conclusions have been drawn: - The overall heat transfer coefficient of the heat exchanger for counterflow was found to be U=1794.5 W/m2K - The overall heat transfer coefficient of the heat exchanger for parallel flow was found to be U=1539.1 W/m2K - From the above values, it is concluded that the heat transfer in counterflow arrangement is more than that of in parallel flow arrangement