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Session: Poster session & Sponsor Exhibition
Session starts: Monday 07 October, 14:00

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Hideharu Yanagi (Cyclect Electrical Engineering Pte Ltd)
Michael Khong (Cyclect Electrical Engineering Pte Ltd)
Gayle Tan (Cyclect Electrical Engineering Pte Ltd)

Abstract:
Current available ORCs on the market are in MW power range and very few are actually made for the kW scale. For ocean voyage ship application, a moderate scale of ORCs is demanded. Current available ORC machines are generally composed of turbo expander or scroll Expander (1-10kWe), shell & tube evaporator and condenser. They are not suitable for installing on board ships under accelerating load of pitching and rolling under marine condition. Turbo expanders are considered to be inappropriate to use and also evaporators with flooded working fluid are not suitable. Employment of screw expander is key issue in an ORC unit for marine use. Authors are planning to develop a modular ORC unit of 200kW which can be recovered from the marine vessel exhaust of both the main engine and auxiliary engine at about 250°C and released at 180°C, thus its electric output of 200kW can replace the use of an auxiliary generator or about 500,000 litres of diesel annually. For a ship with a 1MW auxiliary generator, this represents a 20% increase in electrical efficiency or a potential fuel savings of 20%. This paper presents a proposal system of 20kW for bench scale testing equipment with two stage screw expander for dual purpose operation under high or low temperature heat source. Fig.1 shows the ORC system applying for a SES 36 as a working fluid with cycle efficiency of 18% in high temperature (pressure) operation under an evaporating temperature of 170°C, an inlet pressure of 1st stage of 25.07bar,an outlet of 2nd stage expander of 1.12bar and a condensing temperature of 35.64°C, respectively. Figure also shows a method for operating an ORC system with a high-pressure expander and a low-pressure expander. Therein, the ORC system comprises a bypass line that extends, in a flow direction of the working fluid, from a branching point before the high-pressure expander to the low-pressure expander. In a high temperature operating mode the bypass line is closed and the input control valve of 1st stage expander is opened. In a low temperature operating mode the bypass line is opened and the input control valve of 1st stage expander is closed, and is operated in 2nd stage expander.