CASE55 · Manufacturing · Chilled-water pump sizing
Re-matching chilled-water pumps to measured flow and head
Actual chilled-water demand and pump operating points are checked against original sizing. Control changes, impeller adjustment and pump replacement are compared at the required service level.
01 · CASE ANALYSIS
Original size versus current demand
Production, pipework and operating patterns can change after installation. A pump that once matched the design may later operate with unnecessary flow, head or throttling.
The source follow-up action was to select 5°C chilled-water pump specifications suited to actual use.
02 · CASE ANALYSIS
Source design and operating records
Representative design specifications for a 2,000 USRT 5°C chiller system were 150 kW motor, 605 m³/h flow and 60 m head.
Different source operating records show approximately 128.9–133 kW at 630 m³/h, and other records show 134 kW at 859 m³/h or 128.9 kW at 760 m³/h. These are different conditions, not a fabricated before/after pair.
| Source record | Power | Flow | Head |
|---|---|---|---|
| Representative design | 150 kW motor | 605 m³/h | 60 m |
| Operating-scenario records | 128.9–133 kW | 630 m³/h | Not supplied here |
| Separate operating record | 134 kW | 859 m³/h | Not supplied here |
| Separate operating record | 128.9 kW | 760 m³/h | Not supplied here |
03 · CASE ANALYSIS
Compare the available interventions
Measure flow, suction/discharge pressures and electrical input; locate the operating point relative to pump/system curves and best-efficiency region.
Compare valve/control correction, impeller trim, variable speed, parallel-pump dispatch and replacement. Ideal affinity relations Q ∝ N, H ∝ N² and P ∝ N³ are screening tools, not verified savings.
04 · CASE ANALYSIS
Potential and service verification
The in-progress item considered approximately KRW 70 million/year benefit. A smaller motor by itself is not proof of a successful improvement.
Confirm required flow and head, chilled-water temperature, ΔT, coil service and chiller kW/RT. The final comparison includes chiller and pumping energy.
| Option | Engineering purpose |
|---|---|
| Control/valve correction | Reduce avoidable throttling |
| Impeller adjustment | Re-match the pump curve |
| Variable speed | Respond to varying flow/head demand |
| Pump dispatch | Select efficient parallel combinations |
| Pump replacement | Select actual required Q–H capability |
05 · CASE ANALYSIS
Hydronic-system lesson
Review bypass and low-ΔT causes before assuming that high circulation flow requires a larger pump. Demand-based differential-pressure control may improve existing assets without replacement.
Define the actual service boundary and evaluate lifecycle economics under the site’s demand profile.
APPLY TO YOUR SITE
Connect your operating data to an actionable energy strategy.
Discuss the measurement boundary, data quality, operating constraints and verification approach for your facility.
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