Heat exchangers are an important part of industrial processes as they handle a major portion of total energy consumption. Fouling could have serious impact on their performance and hence affect the economic performance of the process plant. The aim of this work was to simulate the crystallization fouling process in a heat exchanger by developing a C++ program and adopting UDF functions through Fluent software; and hence evaluate all the given models and consequently implement the model which would best suit our particular case. The finding of this work would enable us to evaluate the thickness and fouling rate in the heat exchangers. Furthermore, the effect of pulsating flow on the crystallization fouling of calcium sulfate (CaSO4) in the heat exchanger was also investigated, and the effect of operation of different amplitude of the oscillations (10-70) and frequencies (1.59-12.73 Hz) on the fouling of this compound was studied.