Heat transfer at supercritical state for organic Rankine applications.

In the last years, a lot of attention has been paid for developing technologies for low grade heat recovery. This work focuses on the possibilities to increase the performance of the Organic Rankine Cycle, by utilizing low grade heat source within a temperature range of 90°C - 200°C. One way to improve the performance is a proper selection and design of the components. On the other hand, a way of enhancing the overall cycle efficiency is introduced with supercritical heat transfer in the heat exchanger. The advantage is a better thermal match between the heat source and the working fluid temperature profiles in the heat exchanger. Because, correlations available from literature were used for designing of this component safety factor was also implemented to reduce the uncertainty level. In this work, results from measurement campaigns for a heat exchanger obtained at supercritical state are presented. It can be concluded that improving the design of the heat exchanger leads to better cycle efficiency and reducing the cost of an ORC installation.