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How To Calculate Heat Dissipation In Watts?

Heat dissipation is one of the deciding factors in designing heat transfer components. For example, the efficiency of a Heat exchanger is determined using its heat dissipation capabilities.


This article shows how to calculate the heat dissipation from a system using CFD analysis.


If you want to calculate the amount of heat dissipated from a hot fluid in Watts, then please make sure you have the following values ready:

  1. Fluid inlet temperature
  2. Fluid outlet temperature
  3. Mass flow rate of the fluid
  4. Specific heat of the fluid


Now lets see how CFD can help in calculating this. Usually, we get the fluid properties from the manufacturers as well as the inlet temperature and mass flow rate. With SimScale you can run a Conjugate Heat transfer analysis and get the outlet fluid temperature. Once when you have the outlet temperature, we are ready to calculate the amount of heat dissipated.

Heat dissipated = Q = m*Cp*ΔT [W]


Q – heat energy transferred [W] or [J/s]

m- Mass flow rate of the fluid [kg/s]

Cp-Specific heat of the fluid [J/Kg.K]

ΔT-Temperature difference ( between inlet and outlet) [K]

From the simulation, we would have got the outlet temperature. Now we can calculate the temperature difference ΔT. Using the formula above, we can calculate the Heat dissipated.


If you have a volumetric flow rate, then multiply this with the density of the fluid to get the mass flow rate.

Find tutorials here.

Last updated: January 21st, 2021

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