Energy comparison analysis between direct and indirect dry saturated steam generation, thermally powered by EFPCs’ solar fields

Steam is a key energy vector in the industrial sector and each application requires it at a specific pressure and temperature. In this paper the production of low pressure dry saturated steam for industrial use through high-vacuum flat plate solar collectors (HVFPCs) is discussed. This technology can produce steam from solar energy, hybridizing it with existing fossil powered steam generators to obtain significant energy savings and reduce CO2 emissions. An energy comparison using the 0-D TRNSYS® software between numerical results of different plant configurations is made, which differ in the type of dry saturated steam production device. These devices are necessary as it is not possible to produce steam directly inside collectors. Two possible steam generation methods were analysed: direct steam production, using a Flash vessel, and indirect steam production, using a Kettle reboiler. Finally, each configuration was simulated by imposing a solar field ΔT of 10 °C and 20 °C. Dynamic results show that flash vessel configurations are generally the most efficient, with the same operating parameters, compared to the configurations with Kettle reboiler. Furthermore, configurations with certain ΔT, such as to determine lower operational solar field temperatures, lead to the best results due to the higher HVFPCs’ efficiency.