Illustrative c5 zone design basis
400 kW IT = 320 kW liquid + 80 kW airmodeled
| Value kind | modeled — Interpret this value according to its displayed kind, scope, source, and as-of date. |
|---|---|
| Scope | This teaching design assumes four identical 100 kW racks (specified to three significant figures), each rejecting 80.0 kW to liquid and 20.0 kW to air. Idealized water has density 1.00 kg/L and specific heat 4.18 kJ/(kg·K). At the CDU, TCS enters at 45.0 °C and leaves at 35.0 °C; FWS enters at 30.0 °C and leaves at 40.0 °C. Both streams have a 10.0 K rise across their respective heat loads. The required terminal approach is 5.0 K. For one 1.00 kW component, assume junction-to-case resistance 0.0150 K/W, case-to-inlet resistance 0.0250 K/W, an 85.0 °C junction limit and 5.0 K reserve. These inputs exercise the interfaces defined here and in 5.4; they are not an OEM design. This initial IT-only balance excludes auxiliary heat, which 5.6 adds explicitly. |
| As of | 2026-09 |
| Source | Guide calculation from expressly assumed teaching inputs. Primary reference supplies method or equipment context, not evidence that this design was built or tested. |
| Derivation | Trace. IT heat = 4 × 100 = 400 kW; liquid duty = 4 × 80.0 = 320 kW; air duty = 4 × 20.0 = 80.0 kW. Each water stream needs mass flow 320/(4.18 × 10.0) = 7.66 kg/s, or 459 L/min for the zone and 115 L/min per rack. Both heat-capacity rates are 32.0 kW/K. Cold-end approach = 35.0 − 30.0 = 5.0 K; hot-end approach = 45.0 − 40.0 = 5.0 K. Effectiveness = 320/[32.0 × (45.0 − 30.0)] = 0.667. Comparing the two outlets would test the wrong pair. Component temperature = 35.0 °C + 1,000 W × (0.0150 + 0.0250) K/W = 75.0 °C. Margin is 85.0 − 75.0 = 10.0 K, so the specified 5.0 K reserve remains. Select this operating point for the thermal design and carry the separate 80.0 kW air duty into room cooling; omitting that branch strands equipment outside the cold plates. Flip. At unchanged resistance and component heat, the reserve is exhausted at 85.0 − 5.0 − 40.0 = 40.0 °C inlet; warmer inlet fails. At fixed TCS temperatures, raising FWS inlet above 30.0 °C also fails the assumed 5.0 K cold-end approach requirement. A different exchanger selection or lower heat load must close the new point. OCP cold-plate qualification §1.3.2.1 defines the inlet reference; the balance remains canonical here. Hand heat and flow to 5.6 , external head to 5.13 , and installed acceptance to 13.5 . |
| Review | checking…cadence-derived review 2027-01-03 · standard cadence |
| Recorded changes | none recorded |
| Claim id | p5-c5-zone-design-basis |
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