IT-power feedforward halves pump energy in liquid-cooled data centres

Abstract Pump work in liquid-cooled data centres scales with the cube of flow rate, so the choice of controlled variable sets the achievable energy floor. Existing pump controllers regulate temperature — the result of the thermal balance — although the heat load (IT power), its cause, is directly readable from power distribution units. Here we show that replacing temperature feedback with a closed-form feedforward from IT power reduces pump work by 56.2% and peak junction temperature by 5.14 °C, against a temperature controller tuned over 90 parameter sets, in a 90 kW rack under a 30%→100% step. Conversely, a 300 s look-ahead increases pump work by 45.5% without changing peak temperature, because required flow is an instantaneous function of power. Inter-rack reallocation is likewise infeasible: each lower bound is set by its own load and cannot be transferred. The gain lies in the observed variable, not in algorithmic sophistication.