Kendal under crosswind: the printed method against a full-scale plant, and against its own author's model
Tier 1: measurement on an operating plant. Used at Tier 3, because its source states no uncertainty.
System: Indirect dry cooling, natural draft, horizontal array
- What was compared
- The rise in the water outlet temperature with wind of one Kendal natural-draft dry-cooling tower, a horizontal arrangement of radial A-frames, at a constant heat transfer rate of 650 MW, with Kröger's crosswind method as printed.
- Against
- Full-scale measurements on one of the six Kendal towers, several hundred readings binned per m/s, with Du Preez's numerical prediction for the same tower (Kröger, Vol. 2, Figs. 9.2.13 and 9.2.14, after Du Preez and Kröger, 1995). The readings are digitised from the figures, and the source states no measurement uncertainty.
- The agreement
- As printed, the model over-predicts the measured rise by a factor of 1.75 at 4 m/s, 1.45 at 6 m/s and 1.71 at 8 m/s. A multiplier of 0.24 on the pressure coefficients Cpi and Cpo reproduces the measurements over 4-9 m/s to 0.16 K RMS.
- What it shows
- The case shows that, on the arrangement it was fitted for, Kröger's crosswind method as printed over-states the effect of wind on this plant by 45 to 75%, and that it carries no dependence on the bundle arrangement. It is admitted at Tier 3 weight, because the source states no measurement uncertainty and the tower is stated only in part.
- Source
- D. G. Kröger, 'Air-cooled Heat Exchangers and Cooling Towers', Vol. 2, PennWell (2004), Figs. 9.2.13 and 9.2.14, after A. F. du Preez and D. G. Kröger, 'The effect of the heat exchanger arrangement and wind-break walls on the performance of natural draft dry-cooling towers subjected to cross-winds', J. Wind Eng. Ind. Aerodyn. 58 (1995) 293-303; the tower from Vol. 1 §1.2 (Trage, Ham and Vicary, ASME 90-JPGC/Pwr-25, 1990) and Vol. 2 Fig. 7.3.4Vol. 2 §9.2, Figs. 9.2.13 (five arrangements, wind at tower outlet height) and 9.2.14 (Kendal full-scale measurements, wind at 96 m); §1.2 of Vol. 1 and Fig. 7.3.4 for the tower