Patented SANYO Vacuum Insulation Panel Technology
Patented vacuum insulation panel technology used in SANYO VIP™ freezers is developed and manufactured by SANYO for exclusive use in refrigerated cabinets.
- Cellular freezer construction of vacuum panels and polyurethane foam provides structural stability and the highest insulation values required for extreme temperature differential between the ambient and interior chamber.
- Independent panels are vacuum sealed, open-cell foam substrate enclosed within a barrier film; the substrate matrix strengthens the panel and eliminates hollow areas.
- Lamination of multiple insulation components creates an effective R-value-to-volume coefficient that reduces wall thickness by nearly 50% over conventional ultra-low techniques.
- Downflow evaporator coils are helium leak-tested and encased against the interior surfaces for efficient heat exchange.
- All components are CFC-free for environmental protection.
- Reference SANYO VIP Insulation Technology Patent, U.S. Patent No. US6,260,377 B1 July 17, 2001.
Individual vacuum panels are formed into a unitized composite of panel sections, sealed with reflective barrier film, arranged within the steel inner and outer walls, then pressure laminated with high-density, closed-cell injected foam to form the high-tech wall.
How Vacuum Insulation Works
From The Vacuum Insulation Association
Thermal insulation works by interfering with the transfer of heat between two substances at different temperatures. There are several mechanisms for the transfer of heat, with the physical situation and temperature determining which mechanism dominates. Vacuum insulation is designed to interfere with all of the heat transfer mechanisms.
- Conduction through solids is an important heat transfer mechanism. Some materials are better at conducting heat than others; metals are generally more conductive than plastic. For example, a metal spoon in a cup of hot coffee will be hotter to the touch than a plastic spoon in the same cup of coffee.
- Liquid or gaseous conduction occurs when a higher energy molecule collides with another and transfers some of its energy to the other molecule. Conduction increases in importance with the number of molecules that are present and with increasing temperature or molecular energy. In a high vacuum, this mechanism is less important,since the number of molecules available for energy-transferring collisions is vastly reduced.
- Convection moves heat by permitting gases or liquids to flow from one location to another. Home convection ovens use circulating hot air to bake foods quickly at a constant temperature. In a vacuum, minimal convection occurs because of the small amount of gas present.
- Radiation, or the emission of infrared heat waves from a surface, is a mechanism that increases in importance as the surface temperature rises. An example would be the heat that is radiated from a "red-hot" piece of metal.
- Under a vacuum, the mechanisms to transfer heat via convection and liquid/gaseous conduction are significantly reduced. In traditional insulation, the two mechanisms account for 60% to 70% of the heat transfer.
Note: In general, the term "high vacuum" is used when the internal pressure is less than 1 millibar (mbar), or less than one one-thousandth of atmospheric pressure.