Experimental Study of Fouling in Hybrid Cooling Tower Used in CSP Plants: Effects of the Polymer and galvanized steel tubes

Concentrating solar power (CSP) plants require cooling systems, which are typically operated using either water resources that are scarce in arid regions or dry cooling which impacts the overall efficiency of the system. To ensure a higher sustainability of solar-electric facilities, hybrid cooling is promising solution for higher system efficiency with lower water consumption. However, fouling of cooling components can contribute to several operation issues, such as the reduction of heat transfer, precipitation on heated tubes, and increasing the maintenance cost. It can also be influenced by many parameters, namely the surface proprieties, and operating conditions (such as temperature, water and air flow rates, relative humidity....). To assess the fouling process in the hybrid cooling system, a fouling test facility with a dynamic monitoring system was built its operational performances were experimentally investigated on the basis of a long-term test of 108 days. To explore the influence of the surface materials, the hybrid towers were equipped with polymer and galvanized steel tubes. Based on fouling data, test results indicated that the influence of the tubes positioning on fouling deposition was at least as significant as the influence of tube materials. Generally, the heated tubes at the bottom positions in the test facilities were subject to severe fouling for both tube's materials. As for the polymer heated tubes, an asymptotic fouling resistance value was achieved 22 days before the galvanized ones. Finally, the cleaning method showed that the fouling deposits on polymer tubes were cleaned easily compared with the galvanized tubes.