A Numerical Procedure for the Preliminary Design of a ORC Power Plants with Positive Displacement Expanders
نویسندگان
چکیده
Organic Rankine Cycle power plants use organic, high molecular mass fluids to allow heat recovery from lower temperature sources such as industrial waste heat, geothermal heat, solar etc. The expansion process is usually carried out by axial or radial turbines. However, when the available thermal power is less than 1000 kW, the usage of positive-displacement expander becomes more suitable. In the present investigation, only Scroll expanders have been taken into account. A model has been developed to evaluate the efficiency and the performance of both the overall ORC power plant and the positive displacement expander. A multi-objective genetic algorithm is used for the optimization of the power plant to select the main design parameter of the plant like evaporator pressure, overheating, thermal recovering, mass flow rate etc. The power plant has been optimized based on the local radiating solar energy distribution obtained by statistical data on the local site (Lecce Italy) during the year 2007. Several alternative refrigerants, such as R123, R245fa and R134a have been taken into account. Key-Words: ORC, positive displacement expander, multi-objective optimization , solar energy.
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