Exergo-economic assessment and sensitivity analysis of a solar-driven combined cooling, heating and power system with organic Rankine cycle and absorption heat pump

Abstract

District energy systems based on renewable resources help to reduce greenhouse-gas emissions and fossil-fuel use. Here, a multi-generation energy system combining cooling, heating, and power is realized by employing organic Rankine cycle (ORC) and absorption heat pump (AHP) technologies, which enable cascading the utilization of solar heat. The AHP can operate steadily providing cooling, heating and hot water from solar thermal and geothermal sources. A modelling approach presented to evaluate the energy, exergy, economic, and exergo-economic performance of the above system. The results show that the AHP could reach a coefficient of performance (COP) between 1.38 and 2.37 depending on the mode of operation. The yearly energy and exergy efficiency of the tri-generation system is 56.5% and 9.6%, respectively. Compared to a separate system, the simple economic payback time of the tri-generation system is 3.5 years. The specific exergo-economic cost of electricity produced is 0.12 $/kWh, whereas the cost of hot water is much higher, or 0.31 $/kWh. The sensitivity analysis performed shows that the inlet and outlet temperatures of the AHP together with the yearly solar irradiance have the highest impact on the performance. This study provides a new direction on cost-effective utilization of renewable sources in district energy systems.