Prototype of a thermally driven heat pump based on integrated Organic Rankine Cycles (ORC)
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.
Keywords: thermally driven heat pump, ORC, supercritical evaporator, gas bearings, residential heating, oil-free, high speed ; Thermally driven heat pump ; Orc ; Supercritical evaporator ; Gas bearings ; Residential heating ; Oil-free
Record created on 2011-11-01, modified on 2016-08-09