Another important conclusion is that mass deposit increases almost linearly with time. The parameter estimation results are also verified independently by considering the calculated overall heat transfer coefficient profile with time against the results of Delplace et al. (1994). The comparison is shown in Fig. 6. Note that the simulation results underestimate the heat transfer coefficient in the first 3.8 h of operation while there is a good agreement in the last stages of fouling. The initial induction period, in which the overall heat transfer coefficient is constant is very difficult to be predicted by our model and by any other model in the literature. Overall the agreement with experimental work can be considered satisfactory.
Typical profilesof the deposit masses for plates1}4are shown in Fig. 7 over a simulation time of 6.66 h. Note that fouling is not uniform and increases with the plate number (according to the numbering in Fig. 2). This can be explained based on the temperature profile. It is worthwhile to notice that fouling is not the same even for plates delimiting the same channel (e.g. plates 1 and 2)