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DESIGN OF A SCROLL EXPANDER FOR AN ORC APPLICABLE TO A PASSENGER CAR FOR FUEL CONSUMPTION IMPROVEMENT
Hyun Jin Kim, Je Seung Yu
Session: Poster Session and Sponsors Exhibition
Session starts: Thursday 22 September, 14:00
Hyun Jin Kim (University of Incheon)
Je Seung Yu (University of Incheon)
Abstract:
Application of an organic Rankine cycle to a passenger car has been considered to improve fuel consumption by recovering engine coolant heat, which usually amounts to about one third of the fuel energy. The high-side and low-side temperatures of the ORC were limited by the engine coolant and radiator temperatures, respectively. The evaporator and condenser temperatures of the ORC were set at TH=93oC and TL=60oC, respectively, for the vehicle speed of 120km/hr. At this temperature condition, theoretical efficiency of the Rankine cycle with R1234yf as the working fluid was 7.23%. A scroll expander was designed for energy conversion from thermal energy of the working fluid in the ORC to useful shaft power. For axial compliance, a back pressure chamber was provided on the rear side of the orbiting scroll. Lubrication oil was to be delivered by a positive displacement type oil pump driven by the expander shaft. Performance analysis on the designed scroll expander showed that the expander efficiency was 68.6%. It extracts the shaft power of 1.7 kW out of engine coolant waste heat (plus some portion of the exhaust gas heat) of 32.1 kW. This amount of the expander output is equivalent to the fuel consumption improvement of about 8% for the passenger car under consideration at the vehicle speed of 120km/hr. With decreasing vehicle speed, the scroll expander efficiency was calculated to decrease accordingly: it turned out to be 38.4% at 60km/hr, resulting in about 4.5% improvement in the fuel consumption.
REFERENCES
Endo T., Kawajiri S., Kojima Y., Takahashi K., Baba T., lbaraki S., Takahashi T., Shinohara M., 2007, Study on Maximizing Exergy in Automotive Engines, 2007 SAE 2007-01-0257.
Diego A., Arias, Timothy A., Shedd and Ryan K., Jester, 2006, Theoretical Analysis of Waste Heat Recovery from an Internal Combustion Engine in a Hybrid Vehicle, 2006 SAE 2006-01-1605.