Heat Rejection and PUE
This series publishes working engineering analysis from K&K's data center program. Numbers are labeled [TARGET], [MODELED], [SENSITIVITY] or [FACT]; nothing here is field-measured data, and no article is a sealed engineering document. Each article states its own limits and open items.
- KK-DCL-041Heat-Rejection Weather File Was Built for the Wrong StateA substation name was read as a city, the weather chain was built in the wrong state, and every downstream temperature became a template.
- KK-DCL-042786 kW Between PUE Metering Points Moves PUE by 6.6 PointsElectrical loss aggregated across transformers, UPS and distribution converts directly into PUE points once the denominator is fixed.
- KK-DCL-043Heat Rejection Is Not Secondary Loop HeatPrimary-side rejection adds air-side residual heat, primary pump work and an unquantified power-room share on top of the secondary loop figure, so sizing rejection plant on the secondary figure understates the duty by about 6.5 per cent.
- KK-DCL-044Secondary Supply Temperature Is the Entire Rejection ChoiceThe secondary supply temperature band spans nearly the whole feasible space of primary rejection routes, so freezing it freezes the route.
- KK-DCL-045Adiabatic N+1 Without Spray-Train Redundancy Reverts to Dry CoolingAn adiabatic unit counted as N+1 reverts to dry performance when the spray train has no redundancy of its own.
- KK-DCL-046100.1 m3/h at 348 kPa Is a Requirement, Not a Pump CurveThe review recorded a calculated duty point for each loop and no manufacturer curve, power, efficiency, suction-head requirement or nameplate, so no pump has been shown to meet it.
- KK-DCL-04750 kW of Fans Was Counted Twice in the Generator StepThe same 50 kW of air-side fan load was carried in two load-step registers, inflating the generator staging total and overstating the cooling side's share of it.
- KK-DCL-048A Modeled PUE of 1.177 Is Not Robust With a 275 kW ResidualA modeled PUE result carrying a residual term of a few hundred kilowatts is not a robust figure at the precision it is quoted to.
- KK-DCL-049Weather Margins Must Be Line Items, Not Hidden in Dry-Bulb or Wet-BulbDesign margin folded into dry-bulb and wet-bulb inputs cannot be audited, so margin must appear as its own line item.
- KK-DCL-050Do Not Freeze Heat-Rejection Model Numbers Before Supply Temperature ExistsReserving manufacturing capacity is reversible; freezing a model number before the supply temperature is decided is not.