A review of recent advancements in the crystallization fouling of heat exchangers

A wide range of industrial processes (i.e., evaporation and condensation in desalination process, steam power plant, solar plant, etc.) involve heat transfer among the fluids. During the process of  evaporative and cooling heat transfer, undesirable materials from the fluids accumulate on the surfaces, which critically reduces the performance of heat exchangers and creates one of the biggest challenges in energy transfer. Though the various studies on prediction and removal of fouling was conducted by numerous scientists, this problem is still unresolved in industrial process and is responsible for huge environmental damage and economic losses. This investigation provides a comprehensive overview of crystallization fouling in heat exchangers. Various factors affecting the deposition of crystallization foulaning such as fluid temperature, flow velocity, surface material and roughness, concentration and boiling are systematically reviewed. Accuracy and uncertainty of different equipment and experimental studies are discussed. In addition, fouling modelling is comprehensively discussed from earlier fundamental model to recent computational fluid dynamic and artificial neural networks model. Furthermore, mitigation of fouling with off-line and online approaches are chronologically discussed. Finally, an overview from environmental and economic prospective of fouling in heat exchangers are discussed. The future directions for crystallization fouling in heat exchangers are emphasized, which will support the researchers and industries to retard fouling and achieve economic benefits.