The thermal insulation materials commonly used in refrigerated cars mainly include polystyrene foam, polyurethane foam and a new type of phenolic core material.
1.Polystyrene foam. It is a microporous honeycomb structure foam material, which is made of expandable polystyrene particles containing low boiling liquid foaming agent, heated and pre foamed, and then heated in a mold. Only the bonding process can be used to form the compartment insulation layer. The ordinary polystyrene foam is used as the heat insulation material for refrigerated vehicles, which has been basically eliminated in western countries; However, due to low prices, some small factories in China are still using them.
2. Polyurethane foam. Its main physical and mechanical properties are: thermal conductivity 0.03 W/(mK), tensile strength 2.5 GPa, compressive strength 2.0 GPa, and adhesion to steel plate 2.9 GPa. However, it shrinks at high temperatures, has poor fire resistance, and is relatively expensive
3. A new type of phenolic core material requires not only good thermal insulation, but also light weight. Only with light weight can the vehicle reduce its own mass and improve its carrying capacity;
Its advantages are:
(1) Good thermal insulation performance, heat transfer coefficient of 0.023 W/(m2. K)
(2) High strength, high compressive strength
(3) Non hygroscopic, corrosion resistant
Whether foreign or domestic, advanced refrigerated and insulated vehicles have high requirements for insulation materials:
(1) Uniform foaming, low density;
(2) The thermal conductivity should be as small as possible, with a general requirement of less than 0.045 W/(mK); Phenolic core material can reach 0.023
(3) Good stability for temperature changes, and within the temperature range of – 40 to 70 ℃, the use performance should meet the specified requirements; Phenolic core materials have excellent dimensional stability and will not shrink or deform under any environment.
(4) It has a certain mechanical strength, and can withstand the vibration and impact of vehicles under adverse road conditions without damage or deformation;
(5) Low water absorption and moisture absorption, good frost resistance; Phenolic insulation board is light in weight, and its unit weight is generally 30-80Kg/m. At the same time, the phenolic insulation board does not absorb water and is not afraid of rain.
(6) Non toxic and odorless, with low permeability. When the thermal insulation material is burned, it shall not decompose into toxic and harmful gases;
(7) Low price, easy to shape, can use filling, pouring, spraying and other processes to form a compartment insulation layer.
Phenolic foam core material can achieve these characteristics well.
Post time: Mar-24-2023