GIFSQ Tools · Module 17 — Food Processing, Thermal Engineering & Utilities · Tool 332 of 500
Work out the heating or cooling duty of a heat exchanger from the mass flow, specific heat and temperature change of one stream.
Try sample values — fills the form with the worked example below.
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Duty (kW)
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Duty (MJ/h)
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Temperature change (°C)
Equation: Q = ṁ × cp × (Tout − Tin), with ṁ in kg/s and cp in kJ/kg·K giving Q in kW; MJ/h = kW × 3.6.
Method: Sensible-heat balance for one stream of a heat exchanger, standard chemical engineering practice (Incropera and DeWitt, Fundamentals of Heat and Mass Transfer).
Assumptions: specific heat is constant over the temperature range; no phase change; steady state with no heat loss to surroundings.
Limitations: this gives the duty of one stream only; sizing the exchanger area also needs the log mean temperature difference and overall coefficient — see the Heat Transfer Coefficient Calculator.
Rounding: duty to 2 decimal places, temperature change to 1; intermediates unrounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Method: Sensible-heat balance for one stream of a heat exchanger, standard chemical engineering practice (Incropera and DeWitt, Fundamentals of Heat and Mass Transfer).
Assumptions: specific heat is constant over the temperature range; no phase change; steady state with no heat loss to surroundings.
Limitations: this gives the duty of one stream only; sizing the exchanger area also needs the log mean temperature difference and overall coefficient — see the Heat Transfer Coefficient Calculator.
Rounding: duty to 2 decimal places, temperature change to 1; intermediates unrounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Worked example: 2 kg/s of water (cp 4.18 kJ/kg·K) heated from 20 °C to 80 °C: duty = 501.60 kW (1805.76 MJ/h), a 60.0 °C rise.
Enter values above to see results.
Water cp is 4.18 kJ/kg·K; milk about 3.9, vegetable oil about 2.0, fruit juice about 3.6–4.0. Tool 332 of 500 — GIFSQ
