Effectiveness-NTU Heat Exchanger Calculator

Your details

Performance mode: you know the exchanger (UA) and inlet temps; find how much heat is transferred. Design mode: you specify the effectiveness target; find the required UA.
The geometry of the exchanger determines which effectiveness formula applies. Counter flow always achieves the highest effectiveness for given NTU.
Mass flow rate of the hot-side stream in kg/s.
kg/s
Specific heat capacity at constant pressure for the hot fluid. Water = 4186 J/(kg·K).
J/(kg·K)
Inlet temperature of the hot stream (degrees Celsius).
degC
Mass flow rate of the cold-side stream in kg/s.
kg/s
Specific heat capacity at constant pressure for the cold fluid. Water = 4186 J/(kg·K).
J/(kg·K)
Inlet temperature of the cold stream (degrees Celsius).
degC
Overall heat transfer coefficient combining both convective resistances and wall conduction.
W/(m²·K)
Total heat transfer surface area of the exchanger.
m²
Effectiveness (epsilon)Low effectiveness
0.2951

Fraction of the maximum possible heat that is actually transferred (0 to 1)

NTU0.398
Capacity ratio (Cr)0.75
Actual heat rate (q)111,176.3W
Maximum heat rate (q_max)376,740W
Hot-fluid outlet temperature66.72degC
Cold-fluid outlet temperature37.71degC
Hot-side heat capacity rate (Ch)8,372W/K
Cold-side heat capacity rate (Cc)6,279W/K
0.2951
Low<0.4Moderate0.4-0.7Good0.7-0.9Very High0.9+

Effectiveness is 29.5% for this counter flow exchanger.

  • The exchanger transfers 111.18 kW out of a theoretical maximum of 376.74 kW.
  • Hot stream exits at 66.7 degC; cold stream exits at 37.7 degC.

Next stepFor Counter flow at NTU = 0.398, effectiveness is 29.5%. To increase it, raise the UA product (larger area or better U) or switch to counter flow.

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