Heat Transfer Rate ($Q_r$):

$$Q_r = \epsilon \cdot \lambda \cdot A \cdot T^4$$

Where:

• $Q_r$ is the heat transfer rate, in watts (W).
• $\epsilon$ is the emissivity.
• $\lambda$ is the Stefan-Boltzmann constant, $5.7 \times 10^{-8}$ W/m²-°K⁴.
• $A$ is the surface area, in square meters (m²).
• $T$ is the temperature of the surface, in kelvin (°K).