| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1733473 | Energy | 2012 | 8 Pages |
The concept studied in this work is a low power ORC–ORC heat pump system (providing about 20 kW heat at the condenser) and that is composed of an ORC power cycle driving a reversed ORC heat pump cycle, both cycles using the same fluid. The centrifugal compressor and the radial in-flow turbine are directly coupled on the same shaft rotating on self-acting refrigerant vapor bearings. The system has the advantage of being oil-free, fully hermetic and with low maintenance costs. The paper presents the development of an ORC–ORC prototype, with HFC-134a as working fluid. The main critical parts of the system are the compressor-turbine unit, the supercritical evaporator and the pump. The selected type of heat exchanger for the supercritical evaporation is the double tube coil (DTC). A first experimental setup has been built to test the pump and the supercritical evaporator. A comparison between the results obtained with an in-house supercritical evaporator simulation program and measurements made on the DTC is presented. The design steps of the compressor-turbine are briefly presented. The compressor-turbine unit has been balanced and tested, with air, at speeds up to 140,000 rpm.
► Development of a Rankine cycle driven heat pump for residential applications. ► A high speed oil-free compressor-turbine unit rotating on gas bearings is used. ► The evaporation of the ORC power cycle is supercritical. ► Measurements of R134a supercritical evaporation have been carried out. ► Validation of an in-house supercritical evaporator simulation tool.
