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 insulation layer of the carriage. 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 its low price, some small factories in China are still using it.
(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) The new type of phenolic core material not only needs good insulation performance, but also needs to be lightweight. Only with light weight can the weight of the entire vehicle be reduced and the load-bearing capacity be improved;
Its advantages are: (1) good insulation performance, heat transfer coefficient of 0.023 W/(m2. K) (2) high strength and compressive strength
(3) Non hygroscopic, corrosion-resistant.
Both domestically and internationally, advanced refrigerated vehicles have high requirements for insulation materials:
(1) Uniform foaming and 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) The stability of temperature changes should be good, and the performance should meet the specified requirements within the temperature range of -40~70 ℃; Phenolic core materials have excellent dimensional stability and will not experience shrinkage, deformation, and other conditions regardless of the environment.
(4) Having a certain mechanical strength, able to withstand the vibration and impact of automobiles under harsh road conditions without damage or deformation;
(5) Low water absorption and moisture absorption, good frost resistance; Phenolic insulation board has a light weight and a unit weight of 30-80Kg/m. At the same time, phenolic insulation boards do not absorb water and are not afraid of rain.
(6) Non toxic and odorless, with low breathability. When the insulation material burns, it must not decompose into toxic and harmful gases;
(7) Low price, easy to shape, and can be formed by filling, pouring, spraying and other processes to form a compartment insulation layer.
Post time: Aug-30-2023