OVERVIEW

Conventional power generation by Rankine Cycle uses water-steam as the process fluid. Organic Rankine Cycle, however, utilises organic fluids in its process cycle. Organic fluids have low boiling points and thus make it possible to extract energy from low temperatıre heat sources which was not possible or feasible previously by water-steam cycles. The possible low temperature heat sources can be solar, geothermal, biomass or waste heat.

In the ORC set-up in our laboratory, hot heat transfer oil is supplied to the system simulating the heat source. The hot heat transfer oil goes into the evaporator where this heat is transferred to the pressurized organic fluid causing a phase change from liquid to gas. The organic fluid at high presure and temperature state then goes into a rotating expander (presently scroll type and in future radial type) where this energy is converted into mechanical energy causing the rotation of the shaft which is connected to a generator producing electricity. Leaving the expander, the organic fluid goes into the condenser where it cools down and condenses. A chiller provides the required cooling water to the condenser. The condensed organic fluid is then pressurized by means of a pump feeding to the evaporator. Thus the cycle is completed.

In this ORC set-up, it is planned to use different heat sources, however priority is given to solar energy. Concentrated solar energy using parabolic trough collectors will be the first renewable energy heat source that will be studied in the Laboratory. Other low temperature heat sources such as geothermal, biomass or waste heat also fall in the research scope of BURET .

Research and development activities of BURET will cover the following areas:

  • Steady state and dynamic modelling of various organic Rankine cycles
  • Refrigerent performance evaluation
  • Cycle optimisation
  • Radial and scroll type turbine design
  • Heat transfer equipment from various heat sources to the organic fluid.

 

LABORATORY HARDWARE

The ORC set-up in the BURET Laboratory consists of both on-skid and off-skid equipments. On-skid equipments covers an overall  volume of 25 m3 (5m height x 2.5m width x 2m high) and consists of three pumps, one for each cycle, ( organic fluid, water and heat transfer oil), four heat exchangers ( evaporator, condenser, simulator and recuperator), two throttle valves to simulate the expander during the start up process, a condensed liquid collector at the suction side of the organic fluid pump, complete with interconnection piping, valves and instrumentation.

Off-skid equipments mainly consist of  a scroll type expander, chiller and air compressor units, an electric heater, an expansion vessel for heat transfer oil, a shell and tube heat exchanger to condense and recover the organic fluid that may be discharged from safety valves during operation.

The flow, pressure, temperature and level measurements are monitored and collected on-line by a data acquisition system.

The system’s design pressure and temperature is set to 30 bar and 2000C.