Analytical Study on Performance of a 250-kW Organic Rankine Cycle System under Off-Design Heat Source Temperatures by the Flow Rate Control Approach

A 250-kW organic Rankine cycle system comprised of a preheater, evaporator, condenser, turbine, generator, and pump was used to study its off-design performance and operational control strategy by the flow rate control approach of the working fluid R245fa. The net power output was 243 kW, and the system thermal efficiency was 9.5% under design conditions. The analytical results demonstrated that the flow rate of the working fluid increased with increasing the heat source temperature (TW,in); higher TW,in yielded better heat transfer performance of the designed preheater as well as a higher requirement for the evaporator’s heat capacity; and the net power output increased linearly with increasing TW,in.