Parametric analysis and optimization of a solar driven trigeneration system based on ORC and absorption heat pump

In this study, a solar driven trigeneration system is investigated and optimized in energetic and exergetic terms. Parabolic Trough collectors (PTC) are used for supplying the demanded heat input in the present configuration which includes a storage tank, an Organic Rankine Cycle (ORC) module and an absorption heat pump operating with the LiBr-H2O working pair. The heat source from solar collectors drives the ORC which rejects heat to the generator of the absorption heat pump. This heat pump produces heating and cooling demand simultaneously, while electricity is produced from the ORC. The examined system is analyzed parametrically in steady state conditions with Engineering Equator Solver (EES) tool by keeping the collecting area equal to 1000 m2 in all the examined cases. Eight different working fluids are tested in the ORC, while six extra design parameters are studied. The inlet temperature in the heat recovery system, the superheating, the maximum pressure in ORC, the heat rejection temperature of ORC, the evaporating temperature of the heat pump, as well as the solar beam irradiation are the examined parameters. According to the final results, toluene is the working fluid which leads to maximum exergetic output with n-octane and MDM to follow with 29.42%, 28.50% and 28.35% respectively. In the optimum case, the electricity production of the system is 177.6 kWel, while the cooling and the heating outputs are 398.8 kW and 972 kW respectively.