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energy

Computes the total energy radiated by a body with given parameters.
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Interface

C++
Excel

Energy

 
doubleenergydoubleT
doublee = 1.0 )[inline]
This module calculates the total energy radiated by a body per unit surface area in unit time.

The total radiative energy E_0 of a black body is given by the Stefan-Boltzmann law where I(\lambda) is the radiative intensity of the black body.

In practice, the following formula due to Kirchoff is used where C_0 is the emissivity constant of the black body \displaystyle \left(C_0 \approx 5.669 \left[\frac{W}{m^2 K^4}\right]\right), e is the emissivity factor of the body (0 < e \leq 1) and T is its absolute temperature.

Example 1

The following example calculates the total radiative energy emitted by the Wolfram filament of an incandescent light bulb at 3573.16 degrees Kelvin.
#include <codecogs/engineering/heat_transfer/radiation/energy.h>
#include <stdio.h>
 
int main()
{
  // the temperature of the Wolfram filament
  double T = 3573.16;
 
  // emissivity factor of the filament
  double e = 0.39;
 
  // display the total radiative energy
  printf("Energy = %.5lf kW per sq. meter\n",
  Engineering::Heat_Transfer::Radiation::energy(T, e)/1000.0);
 
  return 0;
}

Output

Energy = 3603.96794 kW per sq. meter

Note

A table with the emissivity factors of various materials at different temperatures can be found at the following link http://www.monarchserver.com/TableofEmissivity.pdf

References

Dan Stefanescu, Mircea Marinescu - "Termotehnica"

Parameters

Tthe absolute temperature of the body (Kelvin)
eDefault value = 1.0

Returns

the total radiative energy emitted by the body (Watt per square meter)

Authors

Grigore Bentea, Lucian Bentea (November 2006)
Source Code

Source code is available when you buy a Commercial licence.

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