Radiative Heat Flux Calculator: worked example
This example is generated from PROFENG's own default input set and the implemented relationship. It is not copied from a cited publication.
Relationship
q'' = εσ(T₁⁴−T₂⁴)
This calculator determines net radiative heat flux from emissivity, hot surface temperature, surroundings temperature. Use it to screen energy, temperature and heat-transfer relationships with explicitly stated properties and boundary conditions.
Inputs
- Emissivity (emissivity) = 0.9
- Hot surface temperature (hot) = 500 K
- Surroundings temperature (cold) = 300 K
Working
(0.9)*5.670374419e-8*(Math.pow((500),4)-Math.pow((300),4)) = 2,776.215 W/m²
Net radiative heat flux: 2,776.215 W/m²
Assumptions and limits
- Properties entered by the user are treated as constant over the calculation unless the formula explicitly varies them.
- Temperatures and temperature differences must use the unit convention shown by the calculator.
- The model is lumped or one-dimensional where implied by the displayed relationship.
- Temperatures are absolute.
- Surface is represented by the entered emissivity and the simplified exchange geometry.
- View factors, participating media and complex multi-surface radiation are not represented.
Formula source and acknowledgement
Theodore L. Bergman, Adrienne S. Lavine, Frank P. Incropera, David P. DeWitt, Fundamentals of Heat and Mass Transfer, 8th, 2018, Wiley. Credit belongs to the cited author(s)/publisher; PROFENG presents its own implementation and does not imply endorsement.
Automated verification passed – 30 September 2026 – six numerical cases checked, with dimensional checks and an independent implementation where applicable.
This worked example is for engineering screening and education. Replace defaults with traceable project data and confirm the method, assumptions, standards and equipment information before design, procurement or operation.