HPE GB200 NVL72 secondary-loop design flow, guide heat-balance derivation for its ~115 kW liquid load at OCP's 7.5–12 °C cold-plate rise
~140–220 L/min (water); ~144–230 L/min PG25derived
| Value kind | derived — Derived values are guide calculations; their result is only as fixed as the stated inputs, scope, and method. |
|---|---|
| Scope | Guide water-property heat balance at OCP's 7.5–12 °C rise; a design illustration, not an OEM flow requirement. The PG25 band applies OCP's 1.25–2.0 L/min per kW. The separate QCT 45 °C inlet and 65 °C return maxima do not prescribe this rise. |
| Caveat | The operating flow must also satisfy the selected rack and CDU pressure/flow operating limits. |
| As of | 2026-10 |
| Source | HPE GB200 NVL72 data sheet (PSN1014890104MYEN, October 2026), p.2: 132 kW total, 115 kW liquid, 17 kW air; OCP OAI System Liquid Cooling Guidelines §1.3 (2023-03-03 update) for the 7.5–12 °C rise and PG25 flow rule; guide water-property calculation. · HPE PDF p.2, Advanced Direct Liquid Cooling from HPE; OCP OAI guidelines §1.3 (printed p. 7); guide Q = mass flow × heat capacity × temperature rise |
| Derivation | Water at 1.00 kg/L and 4.18 kJ/(kg·K): 115 × 60/(4.18 × 12) = 137.6 L/min, rounded to ~140; 115 × 60/(4.18 × 7.5) = 220.1 L/min, ~220. PG25 at OCP §1.3's 1.25–2.0 L/min per kW: 115 × 1.25 = 143.75 ≈ 144; 115 × 2.0 = 230 L/min. Use the approved formulation's properties for the glycol actually supplied. |
| Review | checking…review by 2026-12-22 · standard cadence |
| Recorded changes | last 2026-10-19 · 5 revisions tracked |
| Claim id | nvl72-coolant-flow-guide-derivation-1-25-2-0-l |
Where the guide uses it
- 5.4 Direct-to-Chip Liquid Cooling (DLC) — Architecture, Fluid & Thermal Design
- 5.6 CDUs & the Secondary Loop
- 5.13 Facility Piping & Pressure-System Mechanical Engineering
- 7.13 The Rack as Integration Unit
← Full numbers register — every date-stamped figure in the guide, with revision history.