Parametric investigation of a theoretical organic rankine cycle

Abstract: The energy resource waste heat or low-grade thermal energy is available in vast quantities. Tapping into this resource and converting it to electrical energy would not only reduce energy waste but also has the potential to eliminate greenhouse gas emissions. One technology developed to utilize this resource is the ORC which uses an organic working fluid that has a low boiling temperature and thus can be vaporized at a low temperature. This work has been focused on evaluating a theoretical ORC system working with a constant net power output of 200 kW and heat source temperature of 80 °C. The assessment was conducted with a model developed within the scope of this work. The model was compared against the literature to ensure more reliable results. Assessment of the system was performed with a parametric investigation to assess how the pinch point temperature difference, Condenser cold fluid inlet temperature, and pressure ratio affect the system performance. For a low-temperature ORC system to achieve good performance the pressure ratio is the most impactful parameter to focus on. However, a low Condenser cold fluid inlet temperature allows for a larger pressure range and increases the system performance for any given pressure ratio. Lowering the cold condenser inlet temperature from 20 to 15 °C provides a large system efficiency gain.