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Radiation Thermal Resistance Formula

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Thermal resistance of Heat Flow is a heat property and a measurement of a temperature difference by which an object or material resists a heat flow. Check FAQs

R h = \frac{1}{ε \cdot [Stefan-BoltZ] \cdot A base \cdot (T 1 + T 2) \cdot (({(T 1)}^{2}) + ({(T 2)}^{2}))}

R_h - Thermal Resistance of Heat Flow?ε - Emissivity?A_base - Base Area?T₁ - Temperature of Surface 1?T₂ - Temperature of Surface 2?[Stefan-BoltZ] - Stefan-Boltzmann Constant?

Radiation Thermal Resistance Example

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Here is how the Radiation Thermal Resistance equation looks like with Values.

Here is how the Radiation Thermal Resistance equation looks like with Units.

Here is how the Radiation Thermal Resistance equation looks like.

0.0076 = \frac{1}{0.95 \cdot 5.7E-8 \cdot 9 \cdot (503 + 293) \cdot (({(503)}^{2}) + ({(293)}^{2}))}

0.0076K/W = \frac{1}{0.95 \cdot 5.7E-8 \cdot 9m² \cdot (503K + 293K) \cdot (({(503K)}^{2}) + ({(293K)}^{2}))}

0.0076 = \frac{1}{0.95 \cdot 5.7E-8 \cdot 9 \cdot (503 + 293) \cdot (({(503)}^{2}) + ({(293)}^{2}))}

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Radiation Thermal Resistance Solution

Follow our step by step solution on how to calculate Radiation Thermal Resistance?

FIRST Step Consider the formula

R h = \frac{1}{ε \cdot [Stefan-BoltZ] \cdot A base \cdot (T 1 + T 2) \cdot (({(T 1)}^{2}) + ({(T 2)}^{2}))}

Next Step Substitute values of Variables

∴

R h = \frac{1}{0.95 \cdot [Stefan-BoltZ] \cdot 9m² \cdot (503K + 293K) \cdot (({(503K)}^{2}) + ({(293K)}^{2}))}

Next Step Substitute values of Constants

∴

R h = \frac{1}{0.95 \cdot 5.7E-8 \cdot 9m² \cdot (503K + 293K) \cdot (({(503K)}^{2}) + ({(293K)}^{2}))}

Next Step Prepare to Evaluate

∴

R h = \frac{1}{0.95 \cdot 5.7E-8 \cdot 9 \cdot (503 + 293) \cdot (({(503)}^{2}) + ({(293)}^{2}))}

Next Step Evaluate

∴

R h = 0.00764701436299724K/W

LAST Step Rounding Answer

∴

R h = 0.0076K/W

Radiation Thermal Resistance Formula Elements

Variables

Constants

Thermal Resistance of Heat Flow

Thermal resistance of Heat Flow is a heat property and a measurement of a temperature difference by which an object or material resists a heat flow.

Symbol: R_h

Measurement: Thermal ResistanceUnit: K/W

Note: Value can be positive or negative.

Formulas to find Thermal Resistance of Heat Flow

Emissivity

Emissivity is the ability of an object to emit infrared energy. Emissivity can have a value from 0 (shiny mirror) to 1.0 (blackbody). Most organic or oxidized surfaces have emissivity close to 0.95.

Symbol: ε

Measurement: NAUnit: Unitless

Note: Value should be between 0 to 1.

Formulas to find Emissivity

Base Area

The Base Area refers to the area of one of the bases of a solid figure.

Symbol: A_base

Measurement: AreaUnit: m²

Note: Value should be greater than 0.

Formulas to find Base Area

Temperature of Surface 1

Temperature of Surface 1 is the temperature of the 1st surface.

Symbol: T₁

Measurement: TemperatureUnit: K

Note: Value can be positive or negative.

Formulas to find Temperature of Surface 1

Temperature of Surface 2

Temperature of Surface 2 is the temperature of the 2nd surface.

Symbol: T₂

Measurement: TemperatureUnit: K

Note: Value can be positive or negative.

Formulas to find Temperature of Surface 2

Stefan-Boltzmann Constant

Stefan-Boltzmann Constant relates the total energy radiated by a perfect black body to its temperature and is fundamental in understanding blackbody radiation and astrophysics.

Symbol: [Stefan-BoltZ]

Value: 5.670367E-8

Other formulas in Basics of Modes of Heat Transfer category

Go Heat Transfer through Plane Wall or Surface

q = - k 1 \cdot A c \cdot \frac{t o - t i}{w}

Go Total Emissive Power of Radiating Body

E b = (ε \cdot {(T e)}^{4}) \cdot [Stefan-BoltZ]

Go Radial Heat Flowing through Cylinder

Q = k 1 \cdot 2 \cdot π \cdot ΔT \cdot \frac{l}{\ln (\frac{r outer}{r inner})}

Go Radiative Heat Transfer

Q = [Stefan-BoltZ] \cdot SA Body \cdot F \cdot ({T 1}^{4} - {T 2}^{4})

How to Evaluate Radiation Thermal Resistance?

Radiation Thermal Resistance evaluator uses Thermal Resistance of Heat Flow = 1/(Emissivity*[Stefan-BoltZ]*Base Area*(Temperature of Surface 1+Temperature of Surface 2)*(((Temperature of Surface 1)^2)+((Temperature of Surface 2)^2))) to evaluate the Thermal Resistance of Heat Flow, Radiation Thermal Resistance is represented as the reciprocal of the product of the radiative heat transfer coefficient and the surface area of the object that generates heat. Thermal Resistance of Heat Flow is denoted by R_h symbol.

How to evaluate Radiation Thermal Resistance using this online evaluator? To use this online evaluator for Radiation Thermal Resistance, enter Emissivity (ε), Base Area (A_base), Temperature of Surface 1 (T₁) & Temperature of Surface 2 (T₂) and hit the calculate button.

FAQs on Radiation Thermal Resistance

What is the formula to find Radiation Thermal Resistance?

The formula of Radiation Thermal Resistance is expressed as Thermal Resistance of Heat Flow = 1/(Emissivity*[Stefan-BoltZ]*Base Area*(Temperature of Surface 1+Temperature of Surface 2)*(((Temperature of Surface 1)^2)+((Temperature of Surface 2)^2))). Here is an example- 0.007647 = 1/(0.95*[Stefan-BoltZ]*9*(503+293)*(((503)^2)+((293)^2))).

How to calculate Radiation Thermal Resistance?

With Emissivity (ε), Base Area (A_base), Temperature of Surface 1 (T₁) & Temperature of Surface 2 (T₂) we can find Radiation Thermal Resistance using the formula - Thermal Resistance of Heat Flow = 1/(Emissivity*[Stefan-BoltZ]*Base Area*(Temperature of Surface 1+Temperature of Surface 2)*(((Temperature of Surface 1)^2)+((Temperature of Surface 2)^2))). This formula also uses Stefan-Boltzmann Constant .

Can the Radiation Thermal Resistance be negative?

Yes, the Radiation Thermal Resistance, measured in Thermal Resistance can be negative.

Which unit is used to measure Radiation Thermal Resistance?

Radiation Thermal Resistance is usually measured using the Kelvin per Watt[K/W] for Thermal Resistance. Degree Fahrenheit hour per Btu (IT)[K/W], Degree Fahrenheit Hour per Btu (th)[K/W], Kelvin per Milliwatt[K/W] are the few other units in which Radiation Thermal Resistance can be measured.

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Radiation Thermal Resistance Formula

Radiation Thermal Resistance Example

Radiation Thermal Resistance Solution

Radiation Thermal Resistance Formula Elements

Other formulas in Basics of Modes of Heat Transfer category

How to Evaluate Radiation Thermal Resistance?

FAQs on Radiation Thermal Resistance

Variable Name