| Vacuum Insulation Panel(VIP) is an A1-Class non-combustible ultra-efficient insulation material whose thermal conductivity can reach 1 ~ 3m W/(m·K). Its insulation resistance is 20 times of other normal thermal insulation materials and more with the same size specifications. VIP is based on the theory of vacuum insulation with the rule-the lower the internal pressure, the better the insulation performance. VIP is called finished product after the making process which starts with putting dried porous core material into high gas permeability membrane, then goes to vacuuming and sealing it making the internal parts isolated from the external environment. VIP is widely used in fridges, freezers, cold storage, building wall insulation, ships, automobiles, electric water heaters and other areas. Because of its poor mechanical and physical properties and special structure, nondestructive detection method must be used to its full inspection. Existing detection methods are inefficient. As the needs of VIP from all the areas are growing, the contradiction that quality control can not catch up with the production has become increasingly prominent.A VIP internal pressure prototype tester of which the detection only takes 8s~12s each panel is introduced in this paper. The testing efficiency is 10 times or more of the existing detection methods. As the checkout testing, it shows that the range of error is 12.42%. There is certain significance in application that the testing method does nothing harmful to physical properties and heat insulation performance and the testing efficiency meets and exceeds the needs of production. The VIP internal pressure tester is based on reverse vacuum principle creating the same or even lower pressure outside a VIP than pressure inside it, the envelopes will break away from the core materials and with a laser range finder catching the pumping action, we replace the internal pressure equally with the pressure outside tested by Pirani gauge at that time. The pumping action corresponds to the point of inflexion the distance curve. After designing and making mechanical, electrical and software parts, choosing the corresponding laser rangefinder, solenoid valve, vacuum gauges, vacuum gauge, and bar code printers and other accessories and installating, an electric instrument is accomplished.Internal pressure and thermal conductivity of fumed silica VIPs are tested separately by the tester and NETZSCH HFM436 heat flow thermal conductivity device. Theoretical minimum coefficient of thermal conductivity of fumed silica VIP is 4.2622 m W/(m·k) according to the relationship and function between internal pressure and thermal conductivity of fumed silica VIPs. |
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