Operational Study of a Solar Thermal Installation with Recirculation for Industrial Applications

The solar thermal collector network (SCN) and the thermal energy storage system (TES) represent 90% of the solar thermal installation (STI) total costs. STI occupies 30 hectares, and any reduction is significant for the environment. The proposed approach, which includes a solar thermal plant with recirculation, a mixer, and a heat exchanger, reduces investment costs and environmental impact. It facilitates mixing in a simple tank. The developed methodology reduces the number of collectors and the size of the storage system. An industrial-powdered milk process is the case study. Two scenarios and the base case were evaluated. The four seasons and critical meteorological conditions were considered. Scenario one, without a heat exchanger, presents energy surpluses in three seasons. The second scenario, with a heat exchanger, heats the feedwater and guarantees the heat load and target temperature on critical days of the year. In this second scenario, it is possible to reduce the tank filling time from 8 to 7 h. Up to five parallels were reduced in both scenarios, with mass flow of 0.125 kg/s and up to 3.75% of the total tank volume of 52.65 m3 (mass flow 0.075 kg/s). The optimized system is cost-effective, and 10.20% of the total cost was reduced. This methodology can be applied to any low-temperature STI.