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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-474-8

ISBN Online: 978-1-56700-473-1

International Heat Transfer Conference 16
August, 10-15, 2018, Beijing, China

PRESENTATION OF A TEST-RIG FOR HEAT TRANSFER MEASUREMENTS OF A FLUID AT SUPERCRITICAL STATE FOR ORGANIC RANKINE CYCLE APPLICATION

Get access (open in a dialog) DOI: 10.1615/IHTC16.hte.024349
pages 5389-5396

Résumé

Results from the convection heat transfer measurements at supercritical pressures by using the fluid HFC-125 are presented in this paper. The tests were performed under transcritical organic Rankine cycle (ORC) conditions. This well-known technology efficiently converts the low-temperature heat ~100°C into electricity. Working with fluids at supercritical state in the heat exchanger at the hot side ensures better thermal match between the temperature glides of both fluids. This can yield to less exergy destruction and improve the efficiency of the ORC cycle. Therefore, determining the heat transfer mechanism of the organic fluids at these conditions, by considering a large tube diameter positioned horizontally is of high importance. Hence, the experiments were done in a test section with a horizontal flow, a total length of 4 m and an inner tube diameter of 24.8 mm. The heat flux varied in the range of 20-30 kW/m2, pressure between 38-46 bar and mass flow rate 0.2-0.3 kg/s. The influence of the wall temperature and the heat transfer coefficient with the enthalpy at various heat fluxes was analyzed. The results show that the heat flux has a significant effect on the heat transfer coefficient when the fluid temperature is near the pseudocritical temperature.