Transient response of plate heat exchangers considering effect of flow maldistribution

Plate heat exchangers have been playing important role in the power and process industries in the recent past. Hence, it is important to develop simulation strategies for plate heat exchangers accurately. This analysis represents the dynamic behaviour of the single pass plate heat exchangers, considering flow maldistribution from port to channel. In addition to maldistribution the fluid axial dispersion is used to characterise the back mixing and other deviations from plug flow. Due to unequal distribution of the fluid, the velocity of the fluid varies from channel to channel and hence the heat transfer coefficient variation is also taken into consideration. Solutions to the governing equations have been obtained using the method of Laplace transform followed by numerical inversion from frequency domain. The results are presented on the effects of flow maldistribution and conventional heat exchanger parameters on the temperature transients of both U-type and Z-type configurations. It is found that the effect of flow maldistribution is significant and it deteriorates the thermal performance as well as the characteristic features of the dynamic response of the heat exchanger. In contrast to the previous studies, here the axial dispersion describes the inchannel back mixing alone, not maldistribution, which is physically more appropriate. Present method is an efficient and consistent way of describing maldistribution and back mixing effects on the transient response of plate heat exchangers using an analytical method without performing intensive computation by complete numerical simulation.