A study of flow boiling heat transfer with refrigerant mixtures

An Assessment of Transport Property Estimation Methods for Ammonia–Water Mixtures and Their Influence on Heat Exchanger Size

“…In this study, the Shah [38] correlation was used including mixture properties. The correlation was not specially developed for mixtures, but has been shown to agree reasonably well for refrigerant mixtures [7]. However, it does not include the nucleate boiling suppression due to mass diffusion.…”

“…The specific geometry of the HRB is according to the case study by Stecco and Desideri [6] and listed in Table 1, whereas the applied heat transfer and pressure drop correlations are shown in Table 2. The two-phase boiling heat transfer correlation was originally developed for pure fluids, but has been shown to agree reasonably well for refrigerant mixtures [7]. The boiling heat transfer effect is recommended as further study in the discussion of the paper.…”

“…In turn, the required heat transfer surface area might increase because of a smaller temperature difference between the fluids and influence negatively in the eventual economic advantage of a more effective plant [6]. Additionally, the mixture boiling heat transfer coefficients are typically less than their pure counterparts [7,8], thus leading to an even higher required heat transfer surface area and cost. The boiling heat transfer degradation is mainly due to the additional mass transfer resistance in the nucleate boiling region and changes in the transport properties in the convective boiling region [7].…”

“…Additionally, the mixture boiling heat transfer coefficients are typically less than their pure counterparts [7,8], thus leading to an even higher required heat transfer surface area and cost. The boiling heat transfer degradation is mainly due to the additional mass transfer resistance in the nucleate boiling region and changes in the transport properties in the convective boiling region [7]. A reliable estimation of the transport properties and thus the heat exchanger sizes are therefore imperative for a full economic comparison of an ammonia-water based system with other systems.…”

Heat Transfer of Refrigerant Mixtures

“…Heat transfer characteristics of binary mixtures have beenstudied by several researchers [1 .;..·,·15], with the general finding that mixture heat transfer coefficients are lower than the linear interpolation of pure component heat transfer coefficients, This is due to the effect of mixing on physical properties such as thermal conductivity, and the mass transfer resistance occuring during evaporation [12]. correlations-have been reported by Jung et al [12,13,14] for calculating evaporation heat transfer coefficients of flowing binary mixtures.…”