CASE57 · Manufacturing · Dual-temperature load allocation
Balancing 5°C and 13°C chilled-water loads with chiller and pump staging
Historical demand, valve, ΔT and staging data motivate a temperature-level and load-sharing test. The plan checks OAC and process conditions before deciding how many chillers and pumps should run.
01 · CASE ANALYSIS
Match temperature level to actual need
Some loads require low-temperature cooling or dehumidification; others may accept a higher-temperature supply. Evaluate each use rather than reducing the 5°C fraction indiscriminately.
Chiller and pump effects must be considered together because changing temperature or load allocation can change required flow.
02 · CASE ANALYSIS
Historical operating observations
Representative January, April and July periods had around 50% average load, versus approximately 75% in October. A separate annual analysis reported roughly 63% mean load and one or two extra operating units.
An example January demand around 5,000 RT was served by approximately 8,000 RT online capacity. Different analysis windows explain why these load figures should not be combined as one identical record.
| Indicator | Source observation |
|---|---|
| Separate annual mean load | Approximately 63% |
| Additional online capacity | 1–2 units; approximately 2,000–4,000 RT |
| Example January demand / online capacity | 5,000 / 8,000 RT |
| Average 5°C / 13°C load split | Approximately 60% / 40% |
| Average bypass opening | Approximately 12% |
03 · CASE ANALYSIS
Load-sharing and hydraulic clues
Historical average load split was approximately 60% at 5°C and 40% at 13°C, with winter 5°C share above 70%. The observations do not themselves prove that this split was wrong.
The 5°C ΔT was often below the 10°C design value; the 13°C ΔT was often below 5°C. Bypass was open much of the time, averaging around 12%.
04 · CASE ANALYSIS
The actual test plan
The project planned a 15–50% closing adjustment of OAC 13°C valves, checking whether the 13°C operating count could fall and then defining management criteria.
Other plan material specified a one-unit 13°C shutdown test with outdoor dew point at or below 22°C. This is a project test condition, not a universal control rule.
| Action/condition | Verification |
|---|---|
| OAC 13°C valve closing adjustment: 15–50% | Coil conditions and actual load redistribution |
| One 13°C chiller shutdown | Service stability and remaining-unit loads |
| Outdoor dew point ≤22°C in specified test | Project applicability condition |
| Whole-plant evaluation | Chiller + chilled-water and condenser-water pump power |
05 · CASE ANALYSIS
Evaluate the complete response
Measure coil leaving/dew-point conditions, cleanroom temperature/humidity, both systems’ RT/flow/ΔT and chiller/pump power after stabilization.
No isolated final saving amount is assigned to this activity. Preserve actual plan language rather than rewriting a planned valve action into a completed successful result.
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