Calculate Radiation Heat Transfer

Radiation Heat Transfer Equation:

\[ Q = \sigma \epsilon A (T_1^4 - T_2^4) \]

Stefan-Boltzmann Constant (σ):

W/m² K⁴

Emissivity (ε):

dimensionless

Surface Area (A):

m²

Temperature 1 (T₁):

Temperature 2 (T₂):

Radiation Heat Transfer (Q):

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1. What Is Radiation Heat Transfer?

Radiation heat transfer is the energy emitted by matter in the form of electromagnetic waves due to the temperature difference between objects. Unlike conduction and convection, radiation does not require a medium to propagate and can occur in a vacuum.

2. How Does The Calculator Work?

The calculator uses the Stefan-Boltzmann law:

\[ Q = \sigma \epsilon A (T_1^4 - T_2^4) \]

Where:

\( Q \) — Radiation heat transfer rate (W)
\( \sigma \) — Stefan-Boltzmann constant (5.67×10⁻⁸ W/m² K⁴)
\( \epsilon \) — Emissivity of the surface (dimensionless, 0-1)
\( A \) — Surface area (m²)
\( T_1 \) — Hotter surface temperature (K)
\( T_2 \) — Cooler surface temperature (K)

Explanation: The equation calculates the net rate of heat transfer between two surfaces at different temperatures through thermal radiation.

3. Importance Of Radiation Heat Transfer Calculation

Details: Accurate calculation of radiation heat transfer is essential in thermal system design, building energy analysis, aerospace engineering, and understanding planetary energy balance.

4. Using The Calculator

Tips: Enter all values in appropriate units. Temperature must be in Kelvin. Emissivity values range from 0 (perfect reflector) to 1 (perfect black body).

5. Frequently Asked Questions (FAQ)

Q1: What is the Stefan-Boltzmann constant?
A: It's a physical constant that describes the power radiated from a black body in terms of its temperature (approximately 5.67×10⁻⁸ W/m² K⁴).

Q2: How does emissivity affect heat transfer?
A: Higher emissivity values result in greater radiation heat transfer. Real surfaces have emissivity values between 0 and 1.

Q3: Why use Kelvin instead of Celsius?
A: The Stefan-Boltzmann law requires absolute temperature (Kelvin) because it involves temperature to the fourth power.

Q4: Does this equation work for all surfaces?
A: The equation applies to ideal gray bodies. For real surfaces with wavelength-dependent properties, more complex models may be needed.

Q5: Can radiation be negative?
A: The net radiation heat transfer can be negative if T₂ > T₁, indicating heat transfer from surface 2 to surface 1.