An improved Müller-Steinhagen and Heck model for two phase pressure drop modeling at high reduced pressures

Better understanding of two-phase fluid behavior is required to optimize the design models of the components containing a twophase refrigerant. This is important since applications increasingly seek to operate in the region of high reduced pressure values, for instance the vapor generator, which is a key heat exchanger in the Organic Rankine Cycle system and the high temperature heat pump. Implementations are carried out at high evaporation saturation temperatures where the refrigerant transformation to vapor occurs at temperatures higher than 90°C. Analysis of the literature analysis shows there is a gap in knowledge regarding two-phase flow for synthetic refrigerants at high saturation temperatures. Reliable prediction of pressure drop in two-phase flows is an important prerequisite for accurate optimization of thermal systems. The total pressure drop of a fluid derives from the variation of potential and kinetic energy of the fluid and friction on the channel walls or between the phases (60-120oC) and moderate reduced pressures (0.2-0.5). This paper presents a modification to the established Müller-Steinhagen and Heck (1986) model for two phase pressure drop in relation to high values of reduced pressures. Model validation has been done in comparison to reliable experimental data obtained by Charnay et al. (2015) for R245fa at reduced pressures above 0.5. The modification constitutes a significant improvement on the calculations presented in the literature, including by the authors of experimental data.

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Opracowanie rekordu ze środków MEiN, umowa nr SONP/SP/546092/2022 w ramach programu "Społeczna odpowiedzialność nauki" - moduł: Popularyzacja nauki i promocja sportu (2022-2023).