โ๏ธ Combined Radiation & Convection
Compute parallel radiative and convective heat losses from solid surfaces to surrounding spaces. Quantify relative contribution split and compare transfer coefficients.
Combined Modes Dissipation
Almost all solid bodies operating in gas surroundings dissipate heat via parallel convection and radiation paths:
- Radiation component: Linearized with $h_r$, highly dependent on surface emissivity ($\varepsilon$) and $T^4$ absolute temperatures.
- Convection component: Calculated directly or determined using natural/forced convective correlation rules.
- Environment limits: Surroundings $T_{surr}$ and air $T_{\infty}$ can be set independently.
๐ Configuration
๐ Results & Contributions
Configure properties and click "Compute Combined Heat Transfer" to evaluate heat rates.
๐ Calculation Methodology
Mathematical Model
Total heat rate is the sum of convection and radiation components acting in parallel:
$$Q_{total} = Q_{conv} + Q_{rad}$$
Radiation (linearized):
$$Q_{rad} = \varepsilon \cdot \sigma \cdot A \cdot \left( T_s^4 - T_{surr}^4 \right) = h_r \cdot A \cdot (T_s - T_{surr})$$ $$h_r = \varepsilon \cdot \sigma \cdot (T_s + T_{surr}) \cdot (T_s^2 + T_{surr}^2)$$
Convection (Newton Cooling):
$$Q_{conv} = h_c \cdot A \cdot (T_s - T_{\infty})$$
Radiation (linearized):
$$Q_{rad} = \varepsilon \cdot \sigma \cdot A \cdot \left( T_s^4 - T_{surr}^4 \right) = h_r \cdot A \cdot (T_s - T_{surr})$$ $$h_r = \varepsilon \cdot \sigma \cdot (T_s + T_{surr}) \cdot (T_s^2 + T_{surr}^2)$$
Convection (Newton Cooling):
$$Q_{conv} = h_c \cdot A \cdot (T_s - T_{\infty})$$
Convective Correlations
Simplified convective formulas for air at normal pressure and temperature ranges:
- Vertical Plate (Natural): $h_c = 1.42 \cdot \left( \frac{\Delta T}{L} \right)^{0.25}$
- Horizontal Cylinder (Natural): $h_c = 1.32 \cdot \left( \frac{\Delta T}{D} \right)^{0.25}$
- Forced Air Convection: $h_c = 10.45 - v + 10 \sqrt{v}$