NDDCS design point

Direct natural-draft tower, vertical bundles

Tier T: a textbook worked example - a published answer, not a measurement.

What was compared: The air mass flow rate and the steam-side heat transfer rate of the reference direct natural-draft dry cooling tower at its windless design point. The tower is 165 m high and carries 96 delta bundles of the reference finned tube, whose air-side characteristic is that of Kröger's Example 8.1.4, with saturated steam at 50 °C and an ambient temperature of 20 °C.
Against: The steady design-point values of the reference tower published by Strydom et al. (2026, Table 6), a published calculation and not a measurement.
The agreement: The heat transfer rate is 0.48% above the published value (923.3 MW against 918.9 MW) and the air mass flow rate 3.5% above it (45 545 kg/s against 44 016 kg/s), both within the case's tolerance of 5%.
What it shows: The agreement verifies that the model reproduces the published design point of the reference tower within the stated tolerance. It is a check against a published calculation and says nothing about the model's accuracy against a measured plant.
Source: Kröger, D.G., Air-Cooled Heat Exchangers and Cooling Towers: Thermal-Flow Performance Evaluation and Design (PennWell, 2004)Vol. 2, Example 8.1.4's tube on the reference tower