OPTIMISATION OF A DOMESTIC-SCALE SOLAR-ORC HEATING AND POWER SYSTEM FOR MAXIMUM POWER OUTPUT IN THE UK

asme-orc2015 Tracking Number 139

A model is presented of a domestic-scale solar combined heating and power (S-CHP) system, featuring an Organic Rankine Cycle (ORC) engine and a 15-m2 solar-thermal collector array. The system is configured for operation in the UK, incorporating high-efficiency non-concentrating solar collectors and an ORC working fluid buffer vessel to maintain continuous electrical power output during periods of intermittent solar irradiance. The solar collector array configuration and choice of ORC working fluid are examined, and the system electrical performance is optimised over an annual period of operation by simulating with London UK climate data. By incorporating a two-stage solar collector/evaporator configuration, a maximum net annual electrical work output of 1070 kWh yr-1 (continuous power of 122 W) and a solar-to-electrical efficiency of 6.3% is reported with HFC-245ca as the ORC working fluid and an optimal evaporation temperature of 126 °C. This is equivalent to ~32% of the electricity demand of a typical (average) UK home, and represents an improvement of more than 50% over a recent effort by the same authors based on an earlier S-CHP system configuration and HFC-245fa.