Kröger Eq. 5.5.9 against Wu's measured friction factor
Tier 2: measurement on a controlled rig.
- What was compared
- The air-side pressure drop of Kröger's Eq. 5.5.9 (Ganguli), as an Euler number, against a measured friction factor at seven points over Re 1176-4813 on a three-row staggered bundle of annular finned tubes.
- Against
- The friction factor Wu et al. (2024, Eq. 49) fitted to their own measurements on that bundle, 131 heated tests and an isothermal series, with a stated fitting deviation of 3.95%; a measurement on a rig.
- The agreement
- Eq. 5.5.9 agrees with the measured fit to within -4.3% to +1.1% across the whole range, with a mean absolute deviation of 2.8%. Every point lies within 5%, inside the case's tolerance of 10%.
- What it shows
- The agreement gives Eq. 5.5.9 a measured accuracy of 4.3% within its declared bounds, the first measured accuracy for a bundle loss relation in the catalogue. It is evidence about one closure on a rig and not about a system, and it does not apply below Re 800, where the Gatton tower runs.
- Source
- Y. Wu, Y. Liu, Z. Zhang, Q. Xiang, Y. Sun, X. Yang, S. Jiang, 'A quick measurement method of heat transfer coefficient and friction factor for finned tube bundle of the air cooler under large temperature difference', International Journal of Heat and Mass Transfer 227 (2024) 125556Table 1 (bundle I), Eq. (44) for the friction/acceleration split, Eq. (49) with its stated 3.95% and Re 1176-4813, and the sentence stating each compared correlation's applicability. Figs. 18-23 are the paper's own plots and are not digitised.