Efficiency of Compact Organic Rankine Cycle System with Rotary-Vane-Type Expander for Low-Temperature Waste Heat Recovery

This paper describes the experimental efficiency of a compact organic Rankine cycle (ORC) system with a compact rotary-vane-type expander. The compact ORC system can be used for power generation from low-temperature heat sources such as waste heat from various small-scale heat engines, fuel cells, electric devices, and solar thermal energy. The purpose of this study is to develop an ORC system with a low power output of less than 1 kW with a hot temperature source ranging from 60°C to 100°C and a cold temperature source ranging from 10°C to 30°C. The power output of the system is rather less due to limited heat efficiency. Therefore, the system should have an economically optimal efficiency. In order to realize such a system, an efficient and low-cost expander is indispensable. An experimental ORC system was developed using the rotary-vane-type expander which is one of possible candidates of the expander. The experimental results revealed the expander performance for various rotation speeds, expander efficiencies, and thermal efficiencies. Approximately 30 W of expander power output with 48% expander efficiency and 4% thermal efficiency with a temperature difference between the hot and cold sources of 80°C was achieved.

Authors:

• Musthafah b. Mohd.Tahir
• Noboru Yamada
• Tetsuya Hoshino

Keywords:

• Organic Rankine cycle
• Thermodynamic cycle
• Thermal efficiency
• Turbine efficiency
• Waste heat recovery
• Powergeneration
• Low temperature heat engine.

References:

[1] H. Nasu, "Waste heat quantity assumption from overall Japan industries,"
(in Japanese), Energy Conservation Center of Japan, Press Release,
August 12, (1997).
[2] T. Yamamoto, T. Furuhata, N. Arai, and K. Mori, "Design and testing of
the organic Rankine cycle," Energy, Vol. 26, (2001), pp. 239-251.
[3] Free Power, "Introduction to Free Power ORC systems," June, (2005),
(http://www.freepower.co.uk). Date of access: April 29, 2009.
[4] H. Yamaguchi, X. R. Zhang, K. Fujima, M. Enomoto, and N. Sawada,
"Solar energy powered Rankine cycle using supercritical CO2," Applied
Thermal Engineering, Vol. 26, (2006), pp. 2345-2354.
[5] N. Yamada, A. Hoshi, and Y. Ikegami, "Performance simulation of
solar-boosted ocean thermal energy conversion plant," Renewable
Energy, Vol. 34, (2009), pp. 1752-1758.
[6] N. Inoue, T. Takeuchi, A. Kaneko, T. Uchimura, K. Irie, and H.
Watanabe, "Development of electric power units driven by waste heat,"
Transactions of the Japan Society of Refrigerating and Air Conditioning
Engineers (in Japanese), Vol. 22, (2005), pp. 357-368.
[7] T. Saitoh, N. Yamada, and S.-I. Wakashima, "Solar Rankine cycle system
using scroll expander," Journal of Environment and Engineering, Vol. 2,
(2007), pp. 708-719.
[8] NIST, "Reference Fluid Thermodynamic and Transport Properties
Database (REFPROP) Version 8.0," U.S. Department of Commerce,
Maryland, (2007).
[9] O. Badr, P. W. O'Callaghan, and S. D. Probert, "Rankine-cycle systems
for harnessing power from low-grade energy sources," Applied Energy,
Vol. 36, (1990), pp. 263-292.