# How does a thermal resistor work?

### How does a thermal resistor work?

The thermal resistance is usually indicated by the letter R and expressed in m². K/W (Kelvin per Watt). It informs about the capacity of the insulation thermal resist cold and heat: the more the thermal resistance is higher, the more the insulation is effective.

### How is the heat flux expressed?

The unit of F is the Js-1, i.e. the watt: we also call F the power thermal. the heat flux which crosses a section S of the medium at time t is given by Fourier’s law: the coefficient l is called conductivity thermal middle. He expresses himself in Wm-1.

### What is the difference between thermal resistance and thermal permeance?

The concept of thermal permeance is little used. It makes it possible to introduce and better understand thermal resistance (R), which is the inverse of thermal permeance. > It is expressed in m²K/W. It is the measure of insulating performance of the layer of material. The higher the thermal resistance, the more insulating the layer.

### How to calculate thermal resistance?

In order to calculate the Thermal Resistance you must know the thickness of the material and its thermal conductivity called lambda λ. Then you divide the thickness in meters (m) of this material by its thermal conductivity λ: R = ep / λ The Thermal Resistance / Wall & Floor Calculator

### What is the inverse of thermal resistance?

The inverse of thermal resistance (1/ ) is thermal transmittance. Depending on the nature of , a surface thermal transmission coefficient (in watts per square meter-kelvin W/(m 2 ·K)) or unit (in W/K) will thus be defined.

### What is the difference between thermal and surface resistance?

Thermal resistance is expressed in kelvins per watt (K/W). Surface thermal resistance This last is used more in the case of flat surfaces, particularly in the field of thermal building. is the thermal conductance or thermal transmittance. The inverse of the surface thermal resistance