Transient Response of a Co-current Heat Exchanger to an Inlet Temperature Variation with Time Using an Analytical and Numerical Solution

Abstract

In this article, we examine the transient response of a co-current double-pipe heat exchanger with respect to the inlet temperature change. For this investigation, a method whose main feature is analytical solution of the energy equation for one element of the heat exchanger is developed. The governing equations are linearized with respect to space and time in one element, and the temperature distribution for the element is obtained. Finally, the obtained temperature distribution for one element is utilized numerically for the whole length of the heat exchanger. Various boundary conditions (ramp, exponential, and sinusoidal) are applied, and the responses are investigated with respect to various parameters. A comparison of the results with data from previous studies shows that the method applied in this article is capable of predicting transient behavior accurately. In addition, because the energy equation is solved analytically, the present method has higher accuracy than those previously utilized, and the calculation time declines noticeably.