Transient response of multipass plate heat exchangers with axial thermal dispersion in fluid (Q1590487)

This paper presents a method for transient simulation of multipass plate heat exchangers with axial dispersion of heat in fluid, and with phase lag effect. The method can be used to simulate the exit temperature for both the fluids for arbitrary inlet temperatures. The method also takes into account the phase-lag inside the distribution part, and analyzes the multipass plate heat exchanger by considering it as an assembly of single-pass plate heat exchangers. Examples of computation are given for responses of 1-2 and 2-2 pass configurations. The 1-2 pass exchanger is solved by analyzing the successive modules of heat exchanger, whereas the 2-2 pass heat exchanger is simulated by iterating the responses of two smaller heat exchangers into which it has been divided. The method involves Laplace transform with temporal variable, solution in space domain, and numerical inversion of Laplace transform back to the time domain. The authors show that the axial dispersion in fluid has a strong effect on the transient response.