Radiative Heat Transfer
Compute radiative heat rate Q from emissivity ε, area A and temperatures T1/T2 (K) via Stefan–Boltzmann.
Inputs
Formula
Fundamentals
Compute radiative heat rate Q from emissivity ε, area A and temperatures T1/T2 (K) via Stefan–Boltzmann.
This tool computes Radiative Heat Transfer from the formula: Q = ε·σ·A·(T1⁴−T2⁴), σ=5.67e-8
History
Fluid mechanics and heat transfer were established in the 18th–19th centuries with steam engines and thermodynamics.
Engineering applications
Used for piping, heat-exchange and hydraulic system estimates.
Glossary
| Emissivity ε | Input parameter |
| Area A | Input parameter |
| Hot T1 | Input parameter |
| Radiant heat Q | Output result |
How to use
- Fill in Emissivity ε, Area A, Hot T1, Cold T2 in the Inputs section (watch the unit on each field).
- Click Calculate; the tool evaluates the formula shown above.
- Read Radiant heat Q in the results area.
Formula · Worked Example · Knowledge
Formula
核心计算关系：Q = ε·σ·A·(T1⁴−T2⁴), σ=5.67e-8
输入变量：
- Emissivity ε
eps - Area A
A— m² - Hot T1
T1— K - Cold T2
T2— K
输出结果：
- Radiant heat Q
Q— W
假设/适用：Flow formulas assume steady, incompressible, continuous flow; correct for compressible/high-speed.
Worked Example
根据公式 Q = ε·σ·A·(T1⁴−T2⁴), σ=5.67e-8，取 Emissivity ε = 0.9；Area A = 1 m²；Hot T1 = 500 K；Cold T2 = 300 K。
代入计算得：Radiant heat Q = 2,776 W。
Key Points
- Flow formulas assume steady, incompressible, continuous flow; correct for compressible/high-speed.
- Reynolds Re sets laminar/turbulent; friction f depends on regime & roughness.
- Energy eqn includes elevation, pressure and velocity heads; keep units as length.
Parameters
Inputs
| Parameter | Symbol | Unit | Default |
|---|---|---|---|
| Emissivity ε | eps | 0.9 | |
| Area A (m²) | A | m² | 1 |
| Hot T1 (K) | T1 | K | 500 |
| Cold T2 (K) | T2 | K | 300 |
Outputs
| Result | Symbol | Unit |
|---|---|---|
| Radiant heat Q | Q | W |
Applications
- Pipe flow rate and pressure drop
- Hydraulic cylinder force/speed design
- Flow-meter selection and calibration