Construction and dynamic test of a small-scale organic rankine cycle

The fundamentals of a newly constructed kW-scale Organic Rankine Cycle (ORC) system on the use of R123 were illustrated. A specially designed and manufactured turbine was innovatively applied to this system. Formulations were developed to examine the heat transfer and power conversion processes of the ORC. Unlike water pumping, the vapor pressure of the pumped fluid in the ORC system was much higher, and cavitation was more easily facilitated. A technology was introduced to address this issue without a large height difference between the tank and the pump. A preliminary test of the constructed system under varying conditions was conducted. The mass flow rate through the pump was found to be unequal to that through the turbine during the converter frequency adjustment process. The two mass flow rates were influenced in different ways by the evaporator pressure. The experiment results show that a turbine isentropic efficiency of 0.65 and an ORC efficiency of 6.8% can be obtained with a temperature difference of about 70 °C between the hot and the cold sides. Overall, the turbine has demonstrated adequate performance by operating at off-design conditions, which underscores its potential for application in small-scale ORCs.

► A specially designed and manufactured turbine is used. ► The turbine has demonstrated adequate performance. ► Dynamic test of the ORC is conducted. ► A method to prevent cavitation in the pump is presented.