Calculate kW/ton and Coefficient of Performance for Water Cooled Chillers (uses deg F temperature TLs)
Applicable Systems
- Primary: CHLR
Objective/Method/Outcome
- Objective: Calculate kW/ton and Coefficient of Performance for Water Cooled Chillers [uses deg F temperature TLs]
- Method: Uses the temperature difference (entering and leaving temperatures in deg F), flow, and chiller kW to calculate the tonnage, coefficient of performance (COP), and kW/ton. The analysis is performed only when the chiller power is above a user-adjustable threshold (default is 2 kW). The results are stored in CTLs, and the rule does not trigger any insights. {CHLR}
- Outcome: CTL / No insight
Logic
The logic flow starts by normalizing all the inputs to hourly intervals. When chiller power is above threshold:
- BTU/hr = (GPM*Delta T*499.8)
- Tonnage = (BTU/hr)/12000
- EER = 12/(kW/ton)
- COP = EER/3.412
(Source: ASHRAE Handbook, Guide to Energy Management (Sixth Edition))
Calculate kW/ton and Coefficient of Performance for Water Cooled Chillers [uses deg F temperature TLs]
Description / Method
Uses the temperature difference (entering and leaving temperatures in deg F), flow, and chiller kW to calculate the tonnage, coefficient of performance (COP), and kW/ton. The analysis is performed only when the chiller power is above a user-adjustable threshold (default is 2 kW). The results are stored in CTLs, and the rule does not trigger any insights. {CHLR}
Rule Template Type
- Insight Type: Fault Detection
- Trigger Type: Low
Default Priority
Medium
TL Inputs
| Inputs | Units | Tags | Description |
|---|---|---|---|
| Entering (Return) Water Temperature | degF | water, temp, inlet | Temperature of water entering chiller |
| Leaving (Supply) Water Temperature | degF | water, temp, outlet | Temperature of water leaving chiller |
| Chiller kW | kW | chiller, power | chiller power consumption |
| Flow | US GPM | water, flow | outdoor air temperature |
Constants
| Inputs | Units | Default Value | Description |
|---|---|---|---|
| Fluid Factor (water) | (BTU/hr) / ( US GPM) | 499.8 | conversion from Gallons deg F/ minute to BTU/hr |
| Chiller kW Threhsold | kW | 2.0 | Threshold for Chiller power consumption to indicate ON |
Output Calculated Trend Logs
| Output CTL | Units | Frequency | Description |
|---|---|---|---|
| Chiller_kW_per_Ton | kW/ton | hourly | calculated efficiency |
| Chiller_Energy_Efficiency_Ratio | EER | hourly | calculated energy efficiency ratio |
| Chiller_Coefficient_of_Performance | COP | hourly | coefficient of performance |