Thermal conduction through a house wall

Thermal conductivity (Fourier’s law)

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Thermal conductivity is a measure of how well or poorly a material conducts heat energy (measure of the strength of heat conduction)! You can read more about this in this article. This...
Temperature distribution along a heated thin rod

Derivation of heat equation (diffusion equation)

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The heat equation describes the temporal and spatial behavior of temperature for heat transport by thermal conduction. Read more about it in this article. This article provides answers to the following questions,...
Convection current for radiators placed below a window

Why are radiators usually located under a window?

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Central heating systems use the principle of thermal convection. The water is heated by a central heater and then transferred to the radiators by means of pumps. It is thus a...
Velocity gradients in a laminar and turbulent boundary layer

Hydrodynamic boundary layer

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The hydrodynamic boundary layer of a flow has a decisive influence on heat and mass transport. Learn more about it in this article. This article provides answers to the following questions, among...
Experimental setup for the measurement of thermal conductivity

Experimental setup for determining thermal conductivity

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In this article you can learn more about the experimental determination of the thermal conductivity of materials using steam and ice. This article provides answers to the following questions, among others What...
Sun as a blackbody with a surface temperature of 5778 K

Heat transfer by thermal radiation

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With thermal radiation, heat is transferred by electromagnetic waves without the presence of a substance! You can read more about this mechanism in this article. The mechanisms of thermal convection and thermal...
Definition of the thermal boundary layer (temperature boundary layer)

Thermal and concentration boundary layer

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In addition to the hydrodynamic boundary layer, the thermal boundary layer and the concentration boundary layer also have a decisive influence on the entire heat and mass transport in a flow....
Convective heat transfer at a flat plate with laminar-turbulent flow

Calculation of the Nusselt numbers for forced flows over plates and in pipes

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In this article you will find formulas for calculating the local and average Nusselt numbers for forced flows over plates and in pipes with circular cross sections. This article provides answers to...
Design of a Laser-Flash-Analyzer (LFA) for the determination of thermal diffusivity conductivity

Laser-Flash method for determining thermal conductivity (LFA)

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With the Laser-Flash method (Laser Flash Analyser, LFA), the thermal conductivity is determined by the temperature rise in a test sample that is heated by a short laser pulse from one...
Design and principle of a thermos (vacuum flask), how does work

How does a thermos work? Design of a vacuum flask!

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The reason why hot tea or coffee stays warm for so long in a thermos is the special design of the flask. This design limits the different mechanisms of heat transfer...
Heat flow through a wall by thermal convection and thermal conduction

Difference between thermal conductivity, diffusivity, transmittance, resistance and heat transfer coefficient

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Learn more in this article about the differences and importance of thermal conductivity, thermal diffusivity, heat transfer coefficient, thermal transmittance and thermal resistance, etc. Thermal conductivity Thermal conductivity (lambda) describes the heat transfer...
Heat transfer using the example of a central heating system

Heat transfer by thermal convection

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With heat transfer by thermal convection, heat is transported with a flowing substance. Convection only occurs in fluids, i.e. gases and liquids. You will find more information in this article. This article...
Design of a Heat-Flow-Meter for determining thermal conductivity (HFM method)

Heat-Flow-Meter method for determining thermal conductivity (HFM)

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With the Heat-Flow-Meter method (HFM) the thermal conductivity is determined by comparative measurement of the heat flow using a reference sample. Learn more about this absolute measurement method in this article. This...
Convective heat transfer between a heated pipe and a fluid flowing through it

Prandtl number

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The Prandtl number is a dimensionless similarity parameter to describe the transport of heat and momentum. Learn more about it in this article. This article provides answers to the following questions, among...
Mean free path in a thin gas with low pressure and a dense gas with high pressure

Thermal conductivity of gases

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The thermal conductivity of ideal gases is not dependent on pressure for gases that are not too strongly diluted. This is no longer the case for gases with low pressure. Learn...
Why does metal feel colder or warmer than wood depending on the temperature?

Why does metal feel colder than wood (human thermal response)

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Find out in this article why metal feels colder than wood of the same temperature, while at higher temperatures the metal suddenly feels warmer than wood. The property of an object to...
Experiment to demonstrate heat transport by thermal conduction

Heat transfer by thermal conduction

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Heat transfer by thermal conduction means that heat is conducted through a material. Heat energy is transferred from molecule to molecule at the atomic level. More information on this topic can...
Principle of thermal conduction in solids by oscillation of the atoms

Thermal conduction in solids and ideal gases

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The thermal conductivity in crystalline, non-metallic solids first increases and then decreases again with increasing temperature. Learn more about this behavior in this article. This article provides answers to the following questions,...
Lewis number as a measure for the ratio of the thickness of the thermal boundary layer and the concentration boundary layer

Lewis number

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The Lewis number is a dimensionless similarity parameter to describe heat and mass transport. Learn more about it in this article. This article provides answers to the following questions, among others What does...
Mixing temperature when pouring cold milk into a cup of hot coffee

Heat and thermodynamic equilibrium

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In thermodynamics, heat is the transport of energy due to a temperature difference. Heat in this respect is never "contained" in an object! Learn more about the thermodynamic concept of heat...
Forestville (Canada) and Karlsruhe (Germany) at 49° North

Gulf Stream & global ocean conveyor belt

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The Gulf Stream is an ocean current in the Atlantic Ocean which, as part of the earth's global conveyor belt, has a decisive influence on the climate in Northern and Western...
Hydrodynamische Grenzschicht, thermische Grenzschicht und Konzentrationsgrenzschicht

Dimensionless numbers of the boundary layers (Prandtl, Schmidt and Lewis number)

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To describe the heat and mass transport, dimensionless numbers are introduced to describe the processes within the boundary layers. Learn more about this in this article. This article provides answers to the...
Heat flow from a hot object to a cooler one

Rate of heat flow: Definition and direction

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The rate of heat flow refers to the heat energy transferred per unit of time ("heat output"). The drive for the heat flow is a temperature difference. Learn more about the...
Assembly of a building wall to calculate the U-value

Thermal transmittance (U-value)

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The thermal transmittance (U-value or U-factor) describes the heat transfer through a solid object, which is located between two fluids (gas or liquid) with different temperatures. Learn more about it in...
Determination of thermal conductivity with the Transient Hot Wire method (HTW)

Transient-Hot-Wire method method for determining thermal conductivity (THW)

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With the Transient-Hot-Wire method (THW), the thermal conductivity is determined by the change in temperature over time at a certain distance from a heating wire. Learn more about the experimental determination...
Temperature profile through the wall of a cylindrical pipe

Temperature profiles and heat flows through different geometries

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In this article we discuss temperature curves and heat flows through a plane wall, through a cylindrical pipe and through a hollow sphere. This article provides answers to the following questions, among...