Shah's condensation correlation against Zhu's inclined small-tube air-cooler rig
Tier 2: measurement on a controlled rig.
- What was compared
- The in-tube condensation coefficient of Shah's correlation in its Regime I for steam in a 4 mm tube inclined at 30 to 90 degrees to the horizontal, over the reference's stated range of superficial liquid Reynolds number at its stated quality and saturation temperature.
- Against
- Zhu et al.'s fit to their own measurements on a circular-tube-bank-fin air cooler rig (Zhu et al., 2025, Eq. 43 with Tables 2, 4 and 5), with a stated uncertainty of 10.76% on the condensing Nusselt number. It is a measurement on a rig, and the case is Tier 2.
- The agreement
- Regime I lies within 30% of the measurement at all 30 points and below it at every one, from −4.8% at the top of the range to −28.9% at the bottom, with a mean absolute deviation of 17.3%. Shah's clause that selects Regime III at low liquid Reynolds and gas Weber numbers over-predicts the same measurement by 20% to 245%.
- What it shows
- The case supplies the measured accuracy of Shah's condensation correlation, and it shows that the correlation's lack of an inclination term costs under 6% from 30 to 90 degrees. It tests the tube-side relation alone, with no air side and no system.
- Source
- S.-Q. Zhu, L.-B. Wang, X. Na, Z.-M. Lin, X.-E. Zhang, 'Experimental study of the condensing heat transfer characteristics in a circular tube bank fin air cooler and the comparison to a flat tube bank fin air cooler', International Journal of Heat and Mass Transfer 244 (2025) 126974Table 2 (CTBFAC geometry), Table 4 (conditions), Table 5 (uncertainties), Eq. (43) and the statement 'x = 0.4 is used as the average vapor quality'. Figs. 8-10 are the paper's own plots of this comparison and are not digitised.