Zeotropic mixtures study in plate heat exchangers and ORC systems. (25th January 2023)

• Record Type: Journal Article
• Authors: Blondel, Quentin; Tauveron, Nicolas; Lhermet, Guillaume; Caney, Nadia
• Is Part Of: Applied thermal engineering. Volume 219(2022)Part A
• Publication Date: 2023-01-25
• Subjects: ORC -- Zeotropic mixture -- Heat exchanger; Heat engineering -- Periodicals; Heating -- Equipment and supplies -- Periodicals; Periodicals; 621.40205
• DOI: 10.1016/j.applthermaleng.2022.119418
• Languages: English
• ISSNs: 1359-4311

Abstract

Highlights: Advances of the use of zeotropic mixture in ORC systems. Investigation on plate heat exchangers used for evaporation and condensation of HFE type fluids. Experimental campaign with a mixture of NOVEC649 TM and HFE7000. Semi-empirical model of zeotropic HFE fluid mixture behaviour during two-phase heat exchange. Abstract: Based on the known scientific literature, there are no correlations in the scientific literature to predict the two-phase heat transfer coefficients of Hydrofluoroethers pure fluids and zeotropic mixtures used in plate heat exchangers. This work has allowed the development of evaporation and condensation correlations for such fluids. Correlations based on dimensionless numbers and working fluids critical properties gave promising results, with a prediction of the two-phase heat transfer coefficient around 15% for heat source and 50% for cooling source which led respectively to a prediction of 4% and 6% for the global thermal power exchanged. The behavior of the organic Rankine cycle heat sources and the working fluids used within was also been studied. For this purpose, the influence of the heat sources flow rates variation on the performance of the hot and cold exchangers was analyzed. Results obtained showed a similar behavior and performance variation of the heat exchangers both when using pure fluids and zeotropic mixtures. Zeotropic mixtures working fluids in ORC system are often supposed in the literature to significantly increase the performance of this thermodynamic cycle due to better heat transfer at the hot source. Nevertheless, the great majority of these studies are numerical and do not take into account the interactions and system effects existing within the thermodynamic cycle when using a mixture instead of a pure fluid. This work has allowed to highlight this complexity and to provide a better understanding of the use of zeotropic mixtures.