Refrigerant cooling capacity calculator
Solve for cooling capacity (kW), refrigerant mass flow rate or evaporator enthalpy difference from the other two — Q = mass flow × Δh, an exact energy balance, not an approximation.
How to use this calculator
- Choose which value to solve for — capacity, mass flow or Δh.
- Enter the two known values, or the evaporator inlet/outlet enthalpies for Δh.
- Read the cooling capacity from the exact Q = mass flow × Δh energy balance.
What this calculates — and its one input you have to supply yourself
Cooling capacity is a first-law energy balance across the evaporator — exact, not an approximation, given the refrigerant mass flow rate and the enthalpy rise across it:
Q̇ = ṁ × Δh
Q̇ = cooling capacity, kW
ṁ = refrigerant mass flow rate, kg/s
Δh = h1 − h4 = enthalpy rise across the evaporator, kJ/kg
Any one of capacity, mass flow or Δh follows from the other two.
Why Δh isn't auto-filled
Every refrigerant-cycle tool on this site draws a line between numbers with a bounded, reasonably predictable range (like vapour density near a given saturation temperature — see the Refrigerant Pipe Pressure Drop Calculator's typical-value table) and numbers that depend on the whole cycle design. Evaporator enthalpy difference is firmly in the second category — it depends on evaporating pressure, superheat, subcooling and the expansion device, not just "which refrigerant." Auto-filling a plausible-looking number here would be guessing at exactly the figure the calculation depends on most, so this tool asks for it directly instead, either as Δh itself or as h1 and h4 separately (read straight off your own P-h chart or refrigerant software — the "Derive Δh" section below does the subtraction for you).
This deliberately stops short of simulating the full refrigerant cycle end to end (which would need a complete equation of state this site has no verified source for) — the same boundary already drawn on the COP / EER and Compressor Power calculators.
Where the mass flow comes from
If you're sizing the suction line for this same system, the Refrigerant Pipe Pressure Drop Calculator uses the identical mass flow rate — worth keeping the two consistent. And once you know both this capacity and the compressor's electrical power input, the COP / EER is the natural next step.