Chilled-water setpoint optimization through Test & Adjust

01 · CASE ANALYSIS

Operating question

Producing colder water than the load requires can increase compressor lift. However, chilled-water temperature directly affects process quality, AHU coils, humidity control and dehumidification.

The objective is to find the temperature that minimizes system kW/RT while meeting all service constraints, rather than simply choosing the highest possible water temperature.

02 · CASE ANALYSIS

Field data & measurement boundary

Review chiller status, cooling load, entering/leaving water temperatures, leaving-temperature setpoint, chilled-water flow, condenser-water conditions and chiller/pump power.

The source includes a representative 2,000 USRT rated-capacity example with approximately 17°C entering water, 7°C leaving water, a 7°C setpoint and 630 m³/h flow. Other units show different actual temperature and flow conditions despite similar rated capacity.

Metering checks precede optimization: cooling-load calculation requires measured flow and temperature difference. Whole-plant evaluation also requires pump and cooling-tower fan power.

03 · CASE ANALYSIS

Stepwise Test & Adjust

Confirm downstream process and AHU/dehumidification requirements and agree on an allowable range. Establish the baseline, adjust the setpoint in small steps, allow the system to stabilize, and collect comparable-load data.

At each step, check supply/return temperatures and ΔT, flow, calculated cooling load, chiller kW/RT, process quality, temperature/humidity and dehumidification. Evaluate system power as well as chiller-only efficiency.

Leaving-water temperature adjustment was managed as an action item alongside condenser-water temperature and efficient-unit loading tests. Isolate each test’s comparison conditions when attributing effects.

04 · CASE ANALYSIS

Performance evaluation

Chiller kW/RT = chiller power (kW) ÷ actual cooling load (RT). A fall in kW alone may reflect a lower cooling load and does not prove efficiency improvement.

System power includes chiller, chilled-water pumps, condenser-water pumps and tower fans. Choose the operating point that meets process, comfort, dehumidification and stability constraints with the lowest system kW/RT.

CASE53 does not publish a quantified savings percentage for this individual setpoint action. No such rate is invented in this English edition.

05 · CASE ANALYSIS

Longer-term M&V & future extension

For sustained evaluation, build a baseline using cooling load, condenser-water temperature, outdoor conditions and setpoint where adequate data exist. Separate setpoint effects from load and weather changes.

Seasonal/load-based operating guides may later support dynamic setpoints and predictive control. This is a proposed extension; the documented evidence is field data and Test & Adjust.

Source figures · English edition

Figures correspond to those published in the Korean case. English titles, axes and legends are provided; published values and evidence boundaries are retained. Open a figure at full size to inspect small labels.