A study on heat storage sizing and flow control for a domestic scale solar-powered organic Rankine cycle-vapour compression refrigeration system

This paper presents the off-design modelling of a domestic scale solar organic Rankine cycle (ORC) and vapour compression cycle (VCC) in a coupled operation in different operating modes by using evacuated flat plate (EFP) collectors. Thermodynamic and parametric studies of such coupled system in literature usually assume that the isentropic efficiencies of expander and compressor and the heat exchanger pinch temperature differences are constant. Moreover, studies for directly coupling the ORC-VCC system with solar collectors are somewhat rare. Transient performance of the solar ORC-VCC considering the off-design behaviour of the system components needs to be investigated. A simulation for a period of 24?hrs is conducted by considering the electricity and cooling demand of a 60?m2 office building during a typical day in July for Istanbul. The effect of heat storage capacity on meeting the demand is investigated for a given area of EFP collectors. Moreover, the water flow rate to the boiler is controlled periodically to provide the demanded electricity and cooling. The required EFP collector area and heat storage unit volume have been determined to be 80?m2 and 9.4?m3, respectively. For these design parameters, 25.6?kWh cooling and 18.76?kWh electricity can be generated during a typical day in July. Finally, a simulation is given for such design on a sunny winter day in February, 5.5?kWh electricity and 104?kWh heat can be produced