General heat transfer correlations for flow boiling of zeotropic mixtures in horizontal plain tubes

Abstract

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Assessment of predictive methods for the heat transfer coefficient during flow boiling of R50 and R170 mixtures

“…The GW87 [22], the SH [8] and the modified Zhang et al [12] correlations are the best ones from the MARD point of view. The GW87 [22] underperforms slightly considering the PCT30 and PCT50 values compared to the others.…”

“…Recently, Zhang et al [12] introduced a new correlation specifically designed for binary mixtures. The model considers that the temperature glide plays a major role since a large value leads to a great suppression of nucleate boiling, hence to a dominant contribution of convective boiling.…”

“…As a representative sample, the phase diagram at 0.3 MPa is reported in Figure 1. All the 13 correlations listed in Table 1 have been tested against this database by evaluating the mean absolute relative deviation (MARD), the mean relative deviation (MRD), the percentage of data points within ±15% deviation (PCT15), the percentage of data points within ±30% deviation (PCT30) and the percentage of data points within ±50% deviation (PCT50): It is worth noting that all the experimental conditions are characterized by T * >0.22, which would imply only convective boiling according to Zhang et al [12] (see Eq. 12).…”

“…This approach was successful in predicting an 878 points database from 21 independent studies, except for LNG data taken from only one source [11]. One of the most recent approaches is provided by Zhang et al [12] giving a physics-based correlation, in which a suitable formulation is derived according to the value of the ratio between the temperature glide and the saturation temperature. The correlation has been tested against 2091 data from 22 independent research groups, showing a mean absolute percentage deviation of 29.0%.…”

Investigation on the cycle performance and the combustion characteristic of two CO2-based binary mixtures for the transcritical power cycle

“…Therefore, many researchers performed a lot experimental study to test the heat transfer of many zeotropic mixtures [9]. Also many computational model were proposed based on experimental and theoretical results [10].…”