Calculate evaporator capacity from liquid flow, density, specific heat, and entering/leaving temperature.
Why it matters: Explicit fluid properties improve field capacity estimates for nonstandard water or glycol conditions.
ΣCALCULATE · VERIFY · INTERPRET
Calculated result
Engineering evaluation
Physical evaporator temperature direction confirmed
Calculated evaporator capacity (Qc)208.6 ton
Fluid mass flow (ṁ)
250,400 lb/h
Evaporator temperature drop (ΔT)
10 °F
Engineering interpretation
The physically directed evaporator temperature drop is 10 °F, representing approximately 208.6 ton of cooling capacity.
Important limitations
Confirm flow-meter location, fluid concentration, sensor calibration, stability, and simultaneous readings. Compare with refrigerant-side and electrical data separately.
Confirm entering evaporator fluid is warmer than leaving fluid.
Calculate fluid mass flow from volumetric flow and density.
Multiply mass flow by specific heat and the signed cooling temperature drop, then convert units.
Equation legend
Inputs and calculated quantities
Qw
Evaporator liquid flow — gpm or L/s
T1
Entering liquid temperature — °F or °C
T2
Leaving liquid temperature — °F or °C
ρ
Fluid density — lb/gal or kg/L
cp
Fluid specific heat — Btu/(lb·°F) or kJ/(kg·K)
Qc
Calculated evaporator capacity — ton
ṁ
Fluid mass flow — lb/h
ΔT
Evaporator temperature drop — °F
Applications
How this calculation is used
Building design
Screen evaporator capacity from scheduled fluid conditions.
Construction
Check installed flow and temperature instrumentation basis.
Commissioning
Calculate field capacity from simultaneous evaporator measurements.
Quality controls
Assumptions and limitations
Assumptions
Entered values represent one stable operating condition and use consistent measurement boundaries.
Fluid and air properties are representative of the evaluated condition.
Limitations
This is a preliminary evaluation and field-verification tool, not a final sizing or code-compliance determination.
Manufacturer data, adopted codes, project criteria, and professional engineering review remain controlling.
Field use
Verification procedure
Confirm measurement boundaries, operating mode, and instrument calibration.
Stabilize the system and record simultaneous readings.
Compare the calculation with project requirements and manufacturer data before disposition.
Common engineering mistakes
Mixing values from different operating conditions.
Using nominal rather than measured flow, temperature, power, or fluid properties.
Technical basis
References and source standards
ASHRAE Handbook—FundamentalsPsychrometrics, heat transfer, load relationships, and HVAC calculation context; verify the licensed current edition during professional review.
These engineering tools are provided for educational, preliminary evaluation, field verification, and commissioning support. Results depend on the accuracy of user-entered information and the assumptions stated for each calculation. Every colored status and comparison is a screening indicator only; project criteria, contract requirements, applicable codes, manufacturer instructions, measurement uncertainty, and authorized engineering judgment govern. The tools do not replace project-specific engineering analysis or the judgment of a licensed professional engineer.
