A double-pipe heat exchanger, in its simplest form is just one pipe inside another larger pipe. One fluid flows through the inside pipe and the other flows through the annulus between the two pipes. The wall of the inner pipe is the heat transfer surface.

In this project, a double-pipe heat exchanger was designed and fabricatedwith a copper pipe having a diameter of 15mm with length of 2m and a galvanized steel pipe diameter 40mm with length of 1.92m. The experimental analysis was conducted by passing hot water in inner pipe and cold water in the annulus. The experiment was performed with both parallel and counter flow configurations under the same mass flow rates conditions. Inlet and outlet temperatures were measured by using thermometers.

The data or values got were used to calculate the log mean temperature difference, heat transferred and the overall heat transfer coefficient for both parallel and counter flow arrangement. And from the results, it was observed that counter flow is more effective than parallel flow.