Partial Vacuum Chamber for making clear, dense ice cubes
Original Publication Date: 2002-Mar-31
Included in the Prior Art Database: 2003-Jun-20
PROBLEM: Regular ice cubes made from tap water and frozen in consumer freezer compartments bulge with clouds of trapped air. Due to the increase in surface area (as these micro-bubbles become successively exposed to the drink the ice cube is in) the ice melts quickly; also the odors in the trapped gas are transmitted to the drink. SOLUTION: This invention is a rigid (probably rectangular, possibly stainless steel) chamber with an air-tight lid (air-tight against negative pressure) into which a consumer can place one or two ice trays filled with tap water. A check-valve is tapped into the chamber with a fitting for attaching a vacuum pump (either manually or electrically operated). Pumping some of the air out of the chamber has the effect of reducing the partial pressure on the gasses trapped in the water and inducing the trapped gasses to be released from the water more quickly as the temperature drops to the freezing point. The chamber is placed in a suitable freezer and the result is a denser, clearer, more effective ice cube. ELABORATION FOR INDUSTRIAL USE: A larger chamber (with appropriately higher gauge and stronger material) is constructed and a removable rack is constructed to fit in the chamber. In addition to the air-tight lid and check-valve, the chamber has a drainage hole (with stop-valve) at the bottom. The rack holds an array of ice trays. The ice trays are perhaps fabricated of some flexible material (for easy ice cube removal by twisting) but the material must have a specific gravity greater than 1 (so they won’t float). The empty trays are placed on the rack and the rack is lowered into the chamber. Tap water is poured into the chamber, filling it to the top. All the ice trays are thus submerged. The stop-valve at the bottom of the chamber is opened to drain away the excess water and then re-closed. This drain-down leaves the ice trays filled with water. The chamber is sealed and pumped-out as with the consumer version. Either implementation could be combined with insulation of the chamber (the subject of patent 5,676,875, held solely by author John F. Kelley) which would allow more time for the trapped gasses to escape from the water before it freezes to a very cold temperature yielding even more perfect ice cubes. In the industrial version, the chamber might incorporate the freezing coils and condenser; if so, electronic timing circuits can create the same graduated lowering of temperature (slow reduction to the point where the ice sets and then rapid cooling to a very cold temperature).