Dry cooler, plate-fin coil, induced draft
Cools water or an antifreeze solution in plate-fin coils, with fans above drawing the air through them.
The same plate-fin coils with the fans above them, drawing ambient air through the coil and discharging it upward, the arrangement of most packaged dry coolers. The coil receives ambient air, the fan handles the warm discharge, the draft chain is Eq. 8.1.17 in place of Eq. 8.1.9, and no maldistribution term applies. The air side is evaluated on the relations of Wang et al. (2000) or Rich (1973) on the coil's own dimensions.
Pack: Data-centre dry coolers. In the plans: Pro (as its one pack), Expert, Enterprise, Data Centre and Academic. Plans
The analyses it offers
- RatingThe plant at one condition, solved once.
- DesignFix a target and solve for one dimension.
- Parametric sweepThe rating repeated along one or more axes.
- Annual runThe rating once per weather point over a year.
- Transient simulationThe plant after an event.
The transient scenarios
- Fan start from rest
- Fan stop
- Step on one boundary channel
- Step in the ambient temperature
- The ambient temperature following a profile
What it predicts, and what that was compared with
The app's capability statement for this system, as every report prints it.
| Analysis | Predicts | Compared with | Agreement |
|---|---|---|---|
| Steady rating, and the sweep, design and annual runs built on it | Air mass flow rate, heat transfer rate, fan power and fluid outlet temperature of a plate-fin coil cooler | Wang, Chi and Chang's (2000) coil database; the draft side, fan and platform on Kröger's Examples 8.1.1 and 8.1.2 | 88.6% of the coil database within 15%; no measured dry cooler is reproduced |
| Discretised transient | Fluid outlet temperature, heat transfer rate and air mass flow rate through a fan ramp or a load change | Its own steady rating, the state it settles to; no measured start-up or run-down | Settles to the steady rating within 0.1% on the air mass flow rate and the heat transfer rate |
Its limits
Wind on a fan-driven bank is Kröger's Section 9.3 procedure on Duvenhage's CFD tables, held constant beyond 3 m/s at 5.7 m, without any representation of the site. Not modelled for this system: hot-air recirculation between streets, fouling that develops in service and degradation (a stated fouling resistance is carried as given), freezing and freeze protection, and the plume. Every correlation is a fit over a declared range; the report lists any excursion at the solved state, and a result outside a declared range is an extrapolation and not a prediction.