Local composition shift of mixed working fluid in gas–liquid flow with phase transition

Xu, Xiongwen; Liu, Jinping; Cao, Le; Li, Zeyu

doi:10.1016/j.applthermaleng.2012.01.064

Cited by 21 publications

(3 citation statements)

References 8 publications

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“…Many researchers suggested adding a correction factor to calculate the actual void fraction. Xu et al proved that for propane/isobutane, the value of composition shift calculated by Smith void fraction model was in good agreement with the experimental data. Therefore, Smith void fraction model is selected to calculate composition shift in this paper, which is given by:

normalε = \frac{1}{1 + ((), \frac{1 - X}{X}) \frac{{normalρ}_{normalv}}{{normalρ}_{normall}} S},

S = K + ((), 1 - K) {[\frac{\frac{{normalρ}_{normall}}{{normalρ}_{normalv}} + K ((), \frac{1 - X}{X})}{1 + K ((), \frac{1 - X}{X})}]}^{1 / 2},

where X is the vapor quality and K = 0.4 is the recommended value by Smith.…”

Section: System Descriptionmentioning

confidence: 63%

“…For refrigeration system using R23/R152a, the calculated value using Hughmark void fraction model was in good agreement with the experimental data. On the basis of Navier‐Stokes equation, Xu et al put forward a new method to calculate composition shift. As the simulation results and performance analysis showed, when using Smith void fraction model, the calculated value matched the experimental data well for selected propane/isobutane mixture.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Composition shift in zeotropic mixture-based organic Rankine cycle system for harvesting engine waste heat

Tian

Shu

et al. 2018

Int J Energy Res

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Summary Zeotropic mixture–based organic Rankine cycle (ORC) is a promising technology for harvesting engine waste heat as the property called temperature glide can efficiently improve the temperature mismatch between working fluid and varying temperature heat source. However, a phenomenon called composition shift appearing as different fractions between circulating composition and charge composition accompanies in zeotropic mixtures–based ORC system, which affects system performance directly. To investigate the influence of composition shift on system performance, this paper establishes the thermodynamic model and composition shift model of ORC system. On the basis of simulation results for selected alkanes/R123 zeotropic mixture, the circulating fraction of R123 is higher than its charge fraction, which results in a lower performance of ORC system. For cyclohexane/R123 mixture, the actual mass fraction of R123 increases from 0.5 to 0.52, leading to a maximum decrease of net power by 3%. The factors affecting composition shift such as charge fraction, evaporation pressure, and charge quality are discussed. By increasing the charge fraction of R123, the composition shift can be alleviated within the limitation of safety boundary in this paper. Higher evaporation pressure and larger charge quality can also mitigate the composition shift. Besides, the results indicate that composition shift and temperature glide have similar changing trends, thus temperature glide could be used as predicting the degree of composition shift.

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