Experimental Study on the Organic Rankine Cycle for Recovering Waste Thermal Energy

Abstract

The organic Rankine cycle (ORC) has been using to covert renewable energy, such as waste heat, solar energy, geothermal energy, biomass, ocean energy and so on, to mechanical energy or electrical energy. In general, these kinds of renewable energies cannot be constantly supplied, and so the ORC should operate at various working conditions. For example, waste energy at a factory is usually varied depending on the type of production process, and solar energy also widely varies depending on weather and time. Hence, the ORC must be operated at off-design points due to the fluctuation of the available thermal energy. Its performance at off-design points can be worse than expected, since the components used in the ORC system are matched to the design point. When the ORC system is operated at a far off-design point, its output does not reflect its actual performance. This study investigated the performance of an ORC operating at far off-design points with components that were appropriately matched to its operating condition. In order to investigate the effect of the components used in the ORC system, the experimental results were compared with the performance of the ORC that was designed with components matched to the design point. The compared results showed that the efficiency of the ORC system at far off-design points could be greatly improved when the components used in the ORC system were matched appropriately to the actual ORC operating condition.