Design and evaluation of renewable energies-based multi-generation system for hydrogen production, freshwater and cooling

Abstract

In this study, a new combination of a multi-generation system based on solar energy is presented and studied from the perspective of energy and exergy. The system includes parabolic trough solar collectors (PTSCs) to collect solar radiant heat, and storage tanks to keep the system operational at all hours of the day (considering three operating modes for the system according to the intensity of solar radiation during the day). Also, a geothermal energy system has been coupled with this system to improve its usability. In this system it was tried to use most of the dissipated heat. The system includes solar parts, a regenerative organic Rankine cycle (RORC), two organic Rankine cycle (ORC), three humidification-dehumidification (HDH) desalination cycles, and a single-effect absorption chiller (SE-ARC). The system was studied from a thermodynamic view point, and for these three modes, the energetic efficiency index of the entire system was calculated to be 121.9, 57.28, and 77.68, respectively, while the exergetic efficiency index of the entire system was calculated as 7.696, 3.374, and 4.922, respectively. The highest amount of fresh water and hydrogen production occurs in solar mode and for cooling load in storage mode, which are equal to 6.068, 3.569 and 538.7, respectively. Compared to similar studies, the efficiency of the system has improved due to the better utilization of the dissipated heat as well as the use of geothermal energy. It was also concluded that the highest destruction rate exergy among all the components of the system occurs in PTSC in solar and solar with storage mode and in the storage mode evaporator 1 has the most exergy damage, which is equal to: 1275, 4233 and 390.4 kW, respectively.