| 摘要 |
PURPOSE:To control the composition of the air in an ice box and maintain the freshness of groceries, particularly vegetables, by separating nitrogen in the air on the basis of the output of a sensor for detecting an oxygen gas density and controlling the discharge of nitrogen gas or the air containing much nitrogen gas into the ice box. CONSTITUTION:A nitrogen separator 25 has in its inside a bundle of a plurality of hollow threads and separates nitrogen gas and oxygen gas from each other by utilizing a phenomenon that a penetrating speed is different depending on the kind of a gas. Oxygen gas or the air O containing much oxygen is discharged from a discharge tube 26 and nitrogen gas or the air N containing much nitrogen gas is discharged into an ice box from a supply tube 27. When an oxygen density in the ice box is reduced to, for example, 2%, a controller 28 stops the operation of fluid control means 22. When the oxygen gas density is increased to, for example, 4% by the inflow of the air due to opening or closing a door 12 or 14 or the like, the controller 28 operates the fluid control means 22. Thus, an air composition in the box is controlled and the freshness of vegetables, fruits and the like can be maintained. |
