ORC-DEMONSTRATION-PLANT WITH 1 KW SCROLL EXPANDER - DESIGN AND OPERATIONAL EXPERIENCES

asme-orc2015 Tracking Number 89

Within the framework of many projects and activities in the JRM-Institute and Laboratory for Energy Engineering at the University of Applied Sciences in Bremen, several practical and theoretical aspects of energy transformation using Organic-Rankine-Cycle have been investigated. The prior activities focused on two general optimization and designing tasks. A special procedure and program has been elaborated and developed in the area of universal theoretical analysis, which facilitates working fluid selection in Organic Rankine Cycle for waste energy recovery from potential low and medium temperature level sources. An essential part of the program is a wide range database of organic fluids and the elaborated tool should create a support by choosing an optimal working fluid for special applications and become a part of a bigger optimization procedure by different boundary conditions. The second main task is more practical and corresponds to the particular two-stage ORC-installation concept for waste heat recovery from combustion engines - especially from gas motors of biogas plant. Relating to the theoretical concept a special test bench has been developed and assembled in our laboratory. The main goal of this installation is testing the operation of expansion machines, especially screw engines. In this paper the current project – an ORC demonstration and test plant with an oil free expander - will be presented. The core of the micro power plant is a scroll-expander with a nominal power of 1 kW (Air Squared Inc., E15H22N4.25). In the future the installation will be coupled to solar collectors, which will provide the heat to keep the ORC process running. Alternatively the heat can be generated by an electric driven thermal heater rated at a nominal power of 17 kW to demonstrate the functionality of the ORC itself without using solar energy. Disregarding the source of the heat, it is transmitted by two plate heat exchangers to the working fluid (R245fa). This process ensures a complete vaporization of the working fluid and overheats it to a temperature of 115 °C at a pressure of 1,38 MPa. To simulate a working load, 15 halogen lamps with a nominal power of 100 W each are integrated in the system. The extensive measurement instrumentation will be able to evaluate the entire process and the components used for the installation, especially the effectiveness of the expansion device. REFERENCES [1] Hung, T.C., Shai, T. Y., Wang, S. K., A review of Organic Rankine Cycles (ORCs) for the recovery of low-grade waste heat, Energy, Vol. 22, No. 7, 1997, pp. 661 – 667. [2] Eicke, A., Smolen, S.: Screw Engine as Expansion Machine Applied in an ORC-Test-Installation – Lubrication System for a Screw Machine in Reverse Rotation, VDI-Berichte (Energy and Environment), International Conference on Screw Machines, TU Dortmund University - 2014, ISSN 0083-5560, ISBN 978-3-18-092228-7 [3] Smolen, S., Bandean, D.: Working Fluid Selection for Organic Rankine Cycle Applied to Heat Recovery Systems, WREC, World Renewable Energy Congress 2011, Sweden, Linköping, May 2011, www.wrec2011.com