Previous models published in the literature are concerned with obtaining the steady state performance of plate heat exchangers using numerical solution of the differential equations describing the heat transfer process. The new numerical model, namely the 'cinematic' model developed by the authors has been used to simulate the dynamic behaviour of countercurrent systems such as fluidized beds (C. Lakshmanan and O. E. Potter, Ind. Engng Chem. Res. 26, 292-296 (1987)). This work reports the application of the 'cinematic' model to simulate the dynamic performance of plate heat exchangers. It is shown that the 'cinematic' model requires a very minimum amount of computations in accurately simulating the dynamics of plate heat exchangers. Also, it computes the dynamic and steady state profiles in one sweep, thus offering an easy and accurate approach to the design problems considered by others. It is also shown that representing a plate heat exchanger with an even number of channels by an equivalent true countercurrent system does not result in any significant errors as far as the steady state outlet temperatures are concerned.