# Heat

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### 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.

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### 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.

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### 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...

### 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...

### 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...

### Guarded-Hot-Plate method for determining thermal conductivity (GHP)

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With the Guarded-Hot-Plate method (GHP) the thermal conductivity is determined by the electrical power output of a hot plate with guided heat conduction. Learn more about this measurement method...

### 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.

### 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...

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### 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...

### 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...

### 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...

### 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...

### 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...

### Heat transfer (heat transport)

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Heat transfer is the transport of thermal energy from a warmer object to a cooler object. A distinction is made between thermal convection, thermal conduction and thermal radiation. You...