Energy and financial investigation of a cogeneration system based on linear Fresnel reflectors

Abstract

The objective of the present work is the investigation and the optimization of a cogeneration system with solar linear Fresnel reflectors. The examined system produces electricity by utilizing an organic Rankine cycle and cooling by utilizing a single-effect absorption chiller with the working pair lithium-bromide/water. The system is studied parametrically in steady-state conditions by using a developed model in Engineering Equation Solver which has been validated by literature data. The next step in this work is the optimization (with energy and financial criteria) in dynamic conditions for the climate conditions of Athens (Greece). Different combinations of collecting areas and storage tanks are applied in order to determine the best combination in every case. Moreover, critical parameters such as the working fluid in the organic Rankine cycle, the saturation temperature in the heat recovery system and the generator temperature level in the absorption chiller are studied. The best design according to net present value maximization includes 140 m2 collecting area, a storage tank of 1.4 m3 and toluene in the organic Rankine cycle with 290 °C saturation temperature. In this case, the net present value is around 8 k€, the yearly mean energy efficiency is 17.5%, the yearly mean exergy efficiency is 8.3% and about 18 MWhel are produced on a yearly basis.