DETERMINING THE INFLUENCE CHARACTERISTICS ON HEAT TRANSFER TO SUPERCRITICAL FLUIDS UNDER ORC’S CONDITIONS
Marija Lazova, Alihan Kaya, Michel De Paepe
Session: Poster session & Welcome drinks
Session starts: Wednesday 13 September, 17:30
Marija Lazova ()
Alihan Kaya ()
Michel De Paepe ()
Utilisation of a low-grade temperature heat from various sources for electricity production is a reality today and is possible with an organic Rankine cycle (ORC). Even though this technology has advanced in the recent years there is still place for improvements. The main focus of this study is based on improving the efficiency of an ORC by ensuring supercritical heat transfer in the heat exchanger. The advantage of working with supercritical heat exchanger is the possibility of having a better thermal match between the heat source and the working fluid temperature profiles.
In order to determine the influence characteristics on heat transfer to supercritical fluids in large diameter tubes the organic fluid R125 was selected to be tested under ORCs conditions. This working medium has favourable thermodynamic properties and low critical pressure and temperature of 36.6bar and 66°C respectively. During the measurements the heat source temperature varied between 80°C-100°C, ensuring supercritical heat transfer to the working fluid in the horizontally positioned test section with a total length of 4m.
Determining the overall heat transfer coefficient was possible from the temperature and pressure measurements at the inlet/outlet of the test section and is reported in this work. Furthermore, from the measurements a new heat transfer correlation is proposed. An accurate heat transfer correlation has a strong asset and novelty by implementing them in practice for designing a heat exchanger suitable to work in supercritical regime.