Wei's wind tunnel on a Heller ring: the pressure coefficients want 0.62, the heat-side correction wants nothing
Tier 2: measurement on a controlled rig. Used at Tier 3, because its source states no uncertainty.
System: Indirect dry cooling, natural draft, vertical bundles
- What was compared
- The wind effect coefficient Cw, the fractional change in the heat transfer rate with wind, of a ring of standing radiator segments around the inlet of an indirect natural-draft tower, and its throat pressure coefficient, each against the ratio of the wind speed to the radiator velocity.
- Against
- Wind-tunnel measurements by Wei et al. (1995, Figs. 8, 9 and 11) on a 1/200 Froude-matched model of the Shanxi tower with heated radiators, a physical model with no stated measurement uncertainty.
- The agreement
- As printed, Kröger's crosswind method over-predicts the loss three- to fourfold: Cw is −20% at a velocity ratio of 2 and −30% at 3.2, against the measured −5.0% and −8.9%. With the heat transfer correction for wind αQ forced to 1, a multiplier of 0.615 on the pressure coefficients reproduces the measured curve over ratios of 1 to 4 to 1.26 points RMS, and the ring default of 0.5 to 1.8 points RMS.
- What it shows
- The case indicates that the draft side of the method transfers to a ring when its pressure coefficients are scaled by 0.5 to 0.6, as in the product's ring default of 0.5, and that the heat-side correction (Kröger, Eq. 9.2.10), which the default leaves unchanged, does not. The radiator, the water conditions and the site of the tower are declared, not measured.
- Source
- Q. Wei, B. Zhang, K. Liu, X. Du, X. Meng, 'A study of the unfavorable effects of wind on the cooling efficiency of dry cooling towers', Journal of Wind Engineering and Industrial Aerodynamics 54/55 (1995) 633-643Section 2 (the full-scale tower), 3.1 (similarity, the Froude number), 3.2 (models I and II), 4.1 and Fig. 8/9 (Cw), 4.3 and Fig. 11 (throat Cp)