Heat exchangers are used in industrial processes to recover heat between two process fluids. Although the necessary equations for heat
transfer and the pressure drop in a double pipe heat exchanger are available, using these equations the optimization of the system cost is
laborious. In this paper the optimal design of the exchanger has been formulated as a geometric programming with a single degree of
difficulty. The solution of the problem yields the optimum values of inner pipe diameter, outer pipe diameter and utility flow rate to be
used for a double pipe heat exchanger of a given length, when a specified flow rate of process stream is to be treated for a given inlet to
outlet temperature.