To analyze the operating characteristics of the distributed organic Rankine cycle(ORC) system driven by low-medium temperature heat source(such as the geothermal and solar thermal heat source) under various conditions

a 4 kW ORC prototype using R245fa as working fluid was tested. The dynamic and steady state operating performance of the ORC test rig were analyzed. The results show that

the influence of heat source temperature variation on the temperatures and pressures at the inlet/outlet of the expander as well as the shaft power was more significant than that of the heat source fluid flow rate

due to the redundancy design of the evaporator and the relatively small temperature drop of the heat source. The ORC system needed more time to approach the next steady state after step change of the heat source temperature than the heat source fluid flow rate. The output work of the ORC unit was sensitive to the changes of heat source temperature and working medium flow

during the test

the maximum shaft power(about 3 800 W) and highest thermal efficiency(5.12%) were achieved at the heat source temperature of 150 ℃.