Multilayer insulation technique engineering in thermal blankets and insulation materials

The drawings above show the thermal conductivity (arrow) or the thermal resistance of single layer and multilayer insulation materials. The first drawing on the left shows a single layer insulation material (A) with thickness (M) and a certain thermal conductivity or thermal resistance which is shown by the inclination of the arrow. The steeper the inclination of the arrow, the higher the conductivity or the lower the thermal resistance of the material. When we take a closer look at the first drawing we can also see that the arrow is starting very steep until it reaches the material. The arrow is declining and creating a more horizontal line meaning that the thermal energy or the temperature is experiencing more resistance when it is penetrating the material. At the end of the material we can see that a thermal energy of W/m.K has penetrated through the material. Ones penetrated, the thermal heat is experiencing lesser resistance so the arrow is steeper again.

The second drawing shows a multilayer insulation set-up consisting out of two materials (A) and (B) with a combined thickness of again (M). The arrow shows also the thermal conductivity through the materials where the drawing shows that the thermal conductivity of material (B) is bigger (steeper arrow) than material (A). This also means that this combination has a lower thermal resistance than the single layer material meaning that the single layer insulation material is a better insulator than the multilayer composition. The goal of this combination is clearly not to create better insulation performances.

The last drawing on the right shows a special multilayer insulation material where a air-cavity was created between both individual materials (A) and (B). This air-cavity offers the big advantage that the penetrating thermal energy cannot flow directly from (A) to (B) through conduction, but needs to change into radiation (Ra) to reach material (B). This phenomenon creates a big slow-down or delay in the speed of the thermal energy transfer or travel and creates a big increase in the thermal resistance of the total composition being (material A + B + air-cavity). This delay or slow-down of the traveling of thermal energy can even be extra delayed when a passive or active ventilation technique is implemented in the air-cavity.