Factors affecting the effect of insulation pipes for automobiles

In the automotive industry, automotive insulated aluminum foil bellows can be used for shifter cables, speed indicator cables, hydraulic systems, power cables and liquefied petroleum gas systems for copper tubes for protection purposes. So, what are the factors that affect the use of insulated pipes for automobiles? We have sorted out this issue and have drawn important reasons for the following points.

1. Temperature has a direct influence on the thermal conductivity of various thermal insulation materials. The temperature increases and the thermal conductivity of the material increases. As the temperature increases, the thermal motion of the solid molecules of the material increases, and the heat transfer of the air in the pores of the material and the radiation between the walls of the pores also increase. However, this effect is not significant in the temperature range of 0-50 ° C. Only for materials at high temperature or negative temperature, the influence of temperature should be considered.

2. At room temperature, the thermal conductivity of loose particulate materials decreases as the particle size decreases. When the particle size is large, the size of the voids between the particles increases, and the thermal conductivity of the air inevitably increases. In addition, the smaller the particle size, the smaller the thermal conductivity is affected by temperature changes.

3. In heat insulation materials, most of the heat is conducted from the gas in the pores. Therefore, the thermal conductivity of the insulating material is largely determined by the type of filling gas. If helium or hydrogen is filled in cryogenic engineering, it can be used as a first-order approximation. The thermal conductivity of the insulating material is considered to be comparable to the thermal conductivity of these gases because the thermal conductivity of helium and hydrogen is relatively large.