Preliminary thermal analysis of a solar assisted micro-cogeneration system

In this work, three solar assisted thermodynamic cycles for a micro-cogeneration system are studied. The thermodynamic cycles are based on the organic Rankine cycle (ORC) and the operating temperatures of solar thermal collectors are 80ºC, 100ºC-150ºC and 200º-250ºC, for cycles 1, 2 and 3, respectively. Several researchers have investigated the application and performance of ORCs. They have shown that organic fluids can be used to generate power using low-temperature energy sources (solar or waste heat). The main work objective is the modelling of the selected cycles for optimisation according to the temperature range. Micro-cogeneration, or micro-CHP, is the combination of micro-generation of electricity with useful heat. In this case, the micro-CHP system under analysis uses a micro-turbine and an electric generator with a power output of 5 kW. The turbine inlet temperatures are 80ºC, 120ºC and 230ºC, respectively for cycles 1, 2 and 3. The performance of several fluids was evaluated from a thermal and an economical point of view, taking into account also fluid toxicity. The integration of the micro-CHP system with solar thermal collectors was evaluated and the solar fraction was obtained for climatic conditions of Almeria (Spain), Tunis (Tunis) and Cairo (Egypt).