laws:raco
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laws:raco [2019/06/25 13:54] helene created |
laws:raco [2022/01/21 16:42] (current) helene [Meaning] |
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| |CONVEC|Convection coefficient at temperature T (h)| | |CONVEC|Convection coefficient at temperature T (h)| | ||
| |RADIA| Radiation coefficient at temperature T (σε with σ=Boltzmann's constant; ε=emissivity)| | |RADIA| Radiation coefficient at temperature T (σε with σ=Boltzmann's constant; ε=emissivity)| | ||
| + | |||
| + | === Remarks about emissivity ε === | ||
| + | RADIA = $\sigma\varepsilon$ but sometimes $\varepsilon -> 1-\varepsilon$ | ||
| + | |{{ :laws:raco_1.png?400|}}| \[\frac{2\varepsilon}{2-\varepsilon}\] $\varepsilon$ no RAYON (ECHRA) elements | | ||
| + | |{{ :laws:raco_2.png?400 |}}| \[\frac{1}{\frac{1-\varepsilon}{\varepsilon}+1}=\frac{\varepsilon}{1-\varepsilon+\varepsilon}=\varepsilon\] with RAYON (ECHRA) elements (leak flow)| | ||
| + | |{{ :laws:raco_3.png?400 |}}|\[\frac{1}{2\frac{1-\varepsilon}{\varepsilon}+1}=\frac{\varepsilon}{2-2\varepsilon+\varepsilon}=\frac{\varepsilon}{2-\varepsilon}\] Between 2 surfaces: \[\varepsilon_{12}^*=\frac{\varepsilon_1\varepsilon_2}{\varepsilon_1+\varepsilon_2-\varepsilon_1\varepsilon_2}\] \[\text{If }\varepsilon_1=\varepsilon_2=\varepsilon => \varepsilon_{12}^*=\frac{\varepsilon^2}{2\varepsilon-\varepsilon^2}=\frac{\varepsilon}{2-\varepsilon}\] with unique RAYON (ECHRA) element -> view factor = 1| | ||
| + | |{{ :laws:raco_4.png?400 |}}|\[\frac{1}{2\frac{1-\varepsilon}{2\varepsilon}}=\frac{\varepsilon}{2-\varepsilon}\] $\varepsilon_1=\varepsilon_2$ without RAYON (ECHRA) element| | ||
| + | |{{ :laws:raco_5.png?600 |}}__General case__: \[q_{pi}=\frac{A_i\varepsilon_i}{1-\varepsilon_i}\sigma(T_i^{*4}-T_p^4)\] \[q_{ij}=\sigma A_i F_{ij}(T_j^{*4}-T_i^{*4})\] With $A_i F_{ij}$ computed by ECHRA \\ $T^*$ = Fictitious temperature taking into account the computation of radiosity || | ||
| ===== Stresses ===== | ===== Stresses ===== | ||
| ==== Number of stresses ==== | ==== Number of stresses ==== | ||
| 1 | 1 | ||
| ==== Meaning ==== | ==== Meaning ==== | ||
| - | |SIG(1)|Heat flow exchanged by convection and radiation| | + | |SIG(NPI)|Heat flow exchanged by convection and radiation| |
| ===== State variables ===== | ===== State variables ===== | ||
laws/raco.1561463644.txt.gz · Last modified: 2020/08/25 15:35 (external edit)
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