Experimental study on the net efficiency of an Organic Rankine Cycle with single screw expander in different seasons

The present paper experimentally investigates the thermal performances of an Organic Rankine Cycle (ORC) using a self-developed single screw expander. Experiments were conducted to study the net efficiency of the ORC under different cooling water flows in different seasons. Taking the power consumed by the circulation pump, cooling water pump, cooling tower fan and lubricant oil pump into account, the experimental results showed that the maximum value of produced net power and net efficiency achieved 3.27 kW and 3.04%, respectively, obtained at a cooling water flow of 12 m3 h−1 in winter. The experimental results also reported that the shaft power and shaft efficiency of the expander increased gradually with growth of cooling water flow. Under the same evaporating temperature, the performances of the ORC system deteriorated with the increase of ambient temperature, and the net efficiency of the system in summer was decreased by more than 16.45% than that in winter. In addition, the power consumption by the cooling system was the largest factor restricting the net efficiency than the power consumption by other auxiliary machines. Therefore, reducing the power consumption by the cooling system can effectively enhance the net efficiency of the ORC system.