Enter operating data
Sample operating points
These examples are illustrative. Always align measurements in time.
| Case | Capacity (kW) | Total Power (kW) | COP | kW/ton | CHW Sup/Ret (°C) | Cond In/Out (°C) |
|---|---|---|---|---|---|---|
| Rated day | 700 | 140 | 5.00 | 0.70 | 6.7 / 12.2 | 29 / 34 |
| High lift | 700 | 175 | 4.00 | 0.88 | 6.7 / 12.2 | 32 / 38 |
| Part load | 350 | 65 | 5.38 | 0.65 | 7.0 / 11.0 | 28 / 32 |
Core equations
- Water-side cooling: Q = ṁ × Cp × ΔT (kW), where ṁ = ρ × V̇.
- COP: COP = Qcool / Ptotal.
- EER: EER ≈ COP × 3.412.
- Tons of refrigeration: TR = kW / 3.517.
- kW per ton: kW/ton = Ptotal / TR.
- Condenser-derived cooling: Qcool ≈ Qrej − Ptotal.
- IPLV COP (optional): IPLV = 1 / Σ(wi / COPi).
Use consistent units and simultaneous readings. For glycol solutions, verify Cp and density at your operating temperature.
Steps
- Select the mode that matches your available measurements.
- Enter power input and optional ancillary kW.
- Provide capacity directly, or enter flow and temperatures.
- Enable the part-load table only if you have points.
- Click Calculate to view results above the form.
- Download CSV or PDF for sharing and archiving.
If Combined mode flags a large mismatch, recheck sensor calibration, timing, and unit conversions before making decisions.
Common questions
1) What does COP represent for a chiller?
COP is cooling output divided by total electrical input. Higher COP means more cooling per kW. Compare COP only at similar lift and flow conditions for a fair assessment.
2) Why do engineers use kW per ton?
kW/ton expresses electrical demand per refrigeration ton. It is easy to benchmark across plants and load levels. Lower kW/ton generally indicates better overall efficiency.
3) When should I use chilled-water side calculations?
Use water-side calculations when you trust flow and temperature sensors. This method reflects delivered cooling to the system. Ensure measurements are taken simultaneously and the fluid properties match your mixture.
4) What is condenser-derived cooling and its limitation?
It estimates cooling as heat rejected minus electrical input. It can be useful when chilled-water instrumentation is weak. Errors grow if condenser flow or temperatures are noisy, or if heat gains exist in piping.
5) What is IPLV and why is it helpful?
IPLV is a weighted part-load efficiency metric. It estimates performance across typical operating loads instead of one point. It helps compare machines when most hours occur below full load.
6) Why might my COP look low on a hot day?
Higher condenser water temperature increases lift, raising compressor work. Fouled tubes, low flow, and control issues also worsen lift. Check approach temperatures, tower performance, and setpoints before concluding the chiller is failing.
7) How accurate is the savings estimate?
It is a screening estimate based on ton-hours and kW/ton difference. Real savings depend on load profile, staging, tower and pump interactions, and tariff structure. Use it to prioritize deeper measurement and verification.
8) What inputs matter most for reliable benchmarking?
Power input, chilled-water ΔT, and verified flow drive the result. Capture stable conditions, avoid transient start-up periods, and record condenser water temperatures. Repeat measurements across seasons for a complete picture.