Hitachi Appliances Inc will release six new refrigerators including the "R-Y6000," which preserves food in the low-oxygen chilled room called "Vacuum Chilled Room," one by one from Sept 24, 2008 (Fig 1).
The new refrigerators are the successors of the products announced in September 2007, such as the R-X6000, but feature a newly-developed vacuum heat insulation material and a higher-efficient compressor for energy conservation.
The Vacuum Chilled Room sucks the air from the chilled room with a small vacuum pump and makes it hypoxic to prevent food from being oxidized (Fig 2).
The air pressure in the new chilled room is 0.8 atm, 0.1 atm higher than that of the previous models. The pressure was increased because aluminum foil lids, such as used for the containers of yogurt, tend to peel off in the Vacuum Chilled Room of the previous model. With the higher air pressure, the new models can preserve more types of food.
For other features, the chassis of the chilled room is made of fiber-glass reinforced plastic; as a result, its stiffness approximately doubled, its weight decreased by 60% and the area of its base increased by about 20% due to the eliminated need for reinforcement materials.
In the back of the Vacuum Chilled Room, the "Vitamin Cassette" emits antioxidant vitamins, which are oxidized in place of food. The residual ratio of the vitamin C contained in spinach, for example, increased by about 41% compared with the chilled room of the previous model. The residual rate of the DHA contained in a sardine improved by about 10%.
The Vitamin Cassette also has disinfection and deodorization functions to prevent odors from spreading and molds from growing.
The vacuum heat insulation material was newly developed to reduce the power consumption of the refrigerator (Fig 3, Fig 4). The degree of vacuum was enhanced by reducing the ratio of residual water, and the heat insulation property was improved by about 30%. In addition, the used area of the material was expanded to increase the energy efficiency.
The heat insulation material has a structure of an outer sack covering the inner sack that encloses fibrous glass. It is pliant because the inner sack freely moves inside an outer sack. It has been difficult to use heat insulation material at the bottom of a refrigerator, where a compressor is positioned. In the new models, however, the new material was bent and used at the bottom of them.
Furthermore, Hitachi Appliances adopted another vacuum heat insulation material whose core material was made by fiberizing the plastic recovered from used refrigerators' racks at an electric appliance recycling plant.
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