ORC test rig

Organic Rankine Cycle, or ORC, is a term used to describe steam power processes which use organic fuels as a working medium. Due to the lower boiling point, organic mediums are better for the generation of power at low temperatures (geothermal, waste heat, ...). The current state of technology is to apply geothermal technology in facilities >100 kW. Combined heat and power, or the use of waste heat in the low power range, is, however, also feasible. For such applications, a high level of efficiency, as well as low investment costs, are of the highest importance for an economical operation of such a facility. A way to achieve both of these goals is to adapt compressors used in air conditioning technology, and use them as expanders. Furthermore, through the use of various working mediums, the system can be adjusted to the appropriate temperature range. In order to determine the efficiency, partial-load performance, etc. of such systems, the Institute for Energy Systems created the test rig described below.

Testing Facility

The testing facility makes the survey of various cooling methods and engines possible. The testing facility, on the pilot scale, presents an organic rankine cycle. The steam generator, heated through hot water, has an output of 36 kW. The working medium is extracted out of a fluid collector using a pump. The  refrigerant vapor created there can then be used in an engine. The engine is mounted on a mounting board, and is connected to the generator. Through the measurement of the mass flow, as well as the in- and outgoing temperatures and pressures of the working medium, as well as the output of the generator measured through torque and speed, the inner efficiency of the engine can be determined. Through the variation of the mass flow, partial-load efficiency can be determined as well.