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1、 DESIGN AND EXPERIMENTAL STUDY OF ORGANIC RANKINE CYCLE (ORC) AND RADIAL TURBINE Seok Hun Kang*Korea Institute of Energy Research Daejeon, Korea Dae Hun Chung Korea Institute of Energy Research Daejeon, Korea *Corresponding author: Tel.: +82-42-860-3545. E-mail address: shkangkier.re.kr (S. H. Kang)
2、 ABSTRACT The Organic Rankine Cycle (ORC), which generates electric power by using a low temperature heat source, is developed and an experimental study is conducted. A radial turbine and high speed DC generator are also designed and developed in this study. R245fa is adopted as a working fluid, con
3、sidering the operation conditions of the cycle and its environmental friendly characteristics. Experiments are conducted to analyze the operation characteristics and performance of the developed ORC. The efficiencies of the cycle and turbine, electric power and temperature versus entropy diagram of
4、the developed ORC with respect to the operation condition are investigated through experiments. The factors that influence the efficiency of the developed ORC are analyzed and discussed. INTRODUCTION Recently, oil prices have been fluctuating dramatically and environmental regulations concerning the
5、 greenhouse gas emissions are become severer. Under these circumstances, research on high efficiency energy technology including the organic Rankine cycle (ORC) is garnering more attention. The ORC generates electricity by utilizing low temperature heat sources without emitting any environmental pol
6、lutants or exhaust gases such as CO, CO2, NOX, etc. The ORC is structurally similar to a typical Rankine cycle but uses organic fluids as a working fluid instead of water. Organic fluids are suitable for the ORC because their specific vaporization heat is much lower than that of water. This enables
7、the ORC to produce electricity by using low temperature heat sources. The ORC is mainly used as a power generation system utilizing low-grade heat sources such as geothermal energy and solar and waste heat, the available temperature range of which is from 60 to 200 1, 2, 3, 4. Yamamoto et al. design
8、ed an ORC by using an electric evaporator instead of an external heat source 3. R123 and water were used as a working fluid and experiments were conducted to compare each fluid. The maximum cycle efficiency and electric power were shown to be 1.25% and 150W, respectively. Hung et al. parametrically
9、analyzed the effects of various working fluids such as benzene, ammonia, R11, R12, and R134a on the efficiency of the ORC. They showed that the slopes and shapes of the saturation vapor curves of the fluids primarily affected the system efficiency 5, 6. Hettiarachchi et al. presented a cost-effectiv
10、e optimum design criterion for ORCs utilizing low-temperature geothermal heat sources. The optimum cycle performance was compared for working fluids of ammonia, HCFC123, n-Pentane, and PF5050 7. Larjola developed an ORC using a high-speed oil free turbogenerator-feed pump in which turbomachines (tur
11、bine and pump) and electric generator are directly coupled 8. In the present study, an ORC that generates 30kW electric power is designed and developed. R245fa is selected as a working fluid on the basis of the following characteristics. It is not subject to greenhouse gas emission regulations and i
12、t is developed to replace R123 which has limitation on the regulations. And it is suitable for cycle operation conditions, that is, the evaporation and condensation pressures and temperatures, and is non-flammable and non-toxic. Table I shows the thermodynamic properties of R245fa 9. A radial turbin
13、e is used as an expander and is designed by considering the thermodynamic properties of the working fluid and the operation conditions of the cycle. A high speed synchronous generator is also developed and is directly coupled with a turbine rotor blade. Experiments to analyze the performance and ope
14、ration characteristics of the developed ORC are conducted. The cycle, turbine efficiencies, and electric power of the developed ORC with respect to the operation conditions are analyzed through Proceedings of ASME Turbo Expo 2011 GT2011 June 6-10, 2011, Vancouver, British Columbia, Canada GT2011-461
15、52 1 Copyright 2011 by ASMEDownloaded From: http:/asmedigitalcollection.asme.org/ on 03/23/2016 Terms of Use: http:/www.asme.org/about-asme/terms-of-use experiments. The factors that influence the efficiency of the developed ORC are analyzed and discussed. Table I: Properties of R245fa (HFC-245fa).
16、Molecular name Molecular weight Critical pressure Critical temperatureCF3CH2CHF2 134 g/mol 3640 kPa 427.2 K The designed ORC is developed for the experimental study, so it is tested in design and off-design points before considering its application to the real site. Most of the commercial ORCs whose working fluid temperature range in evaporator is from 100 to 150 use R245fa instead of R123 in these days. But there is no journal paper that deals with experimental
