Fouling mitigation on different heat exchanging surfaces materials used in the hybrid cooling tower test facility

Abstract

Fouling problems are of major concern to many industries using water and heat, especially in cooling processes. Once scale forms on a heat transfer surface, at least two major problems associated with the scale occur. The first problem is the deterioration of the heat transfer equipment performance due to the much lower thermal conductivity of scale compared to that of pipe materials. The second major problem is that a small change in the tube diameter substantially increases the pressure drop across the water piping system. The fouling for cooling towers in CSP plants is an influential factor on whether the equipment is performed or not. Beside the water cooling quality, the tube material surfaces are being allowed increasing attention to evaluating the fouling phenomena. Those parameters can in fact highly affect the performance of a cooling tower; hence, it is central to evaluate how the used heat exchanger tube materials will be impacted by fouling factors. Although fouling can have an impact on a cooling tower performance through various ways, including water flow, air/water temperatures, water quality, and tubes materials. In this paper, we are focusing our attention to the fouling scale and its effect on the overall heat transfer coefficient, heat transfer and fouling resistance of deposits fouling through a comparative study based on SEM images, X-ray diffraction analysis and experimental results of polymers and galvanized heat surface materials. In order to understand the fouling behavior, an apparatus scale unit of a hybrid cooling tower designed for CSP plants was installed in the Green Energy Park (GEP) research platform, located in Benguerir, Morocco, in the framework of the MinwaterCSP project (supported by EU H2020). In this scope, the fouling deposits on the polymer and galvanized steel tubes were investigated.