Analysis of Fouling on Nanocomposite Surfaces in Plate Heat Exchangers

Abstract

In the application of plate heat exchangers (PHEs), fouling has always been an intractable problem that results in decreasing the heat transfer efficiency and increasing the associated pressure drop. Plate heat exchangers are employed in solar energy systems to transfer the solar heat to a working fluid that can be used for heating or power generation applications depending on the amount of heat collected per unit surface area. The work upon which this article partially reports presents analyses of the factors influencing the antifouling performance of two types of nanocomposite surfaces, namely, Ni-P-PTFE and Ni-P-TiO2. In this work, the flow and thermal fields in PHEs are numerically analyzed. Then, experiments are conducted to verify the numerical results. The influencing factors of fouling are theoretically analyzed employing the Kern–Seaton fouling model and the von Kármán analogy. Results of the work performed here show that the friction factor f, the mass transfer coefficient Km, and the shear stress τs of the Ni-P-TiO2 and Ni-P-PTFE nanocomposite surfaces all decrease compared with an uncoated surface. Results also indicate that the deposit bond strength ζ of the Ni-P-TiO2 and Ni-P-PTFE coatings decrease by 42.1% and 30.5%, respectively. Furthermore, the Ni-P-TiO2 coating was found to increase the probability P of sticking to the surface by 24.9%, while the Ni-P-PTFE coating decreased the sticking probability P by 2.7%.