Patent ID: 6796139
Filing Date: 2004-09-28
Classification: A63C,E02D,E21B,E21D,F25B

Abstract:
Ground freezing apparatus comprising:a high stage refrigeration system and a low stage refrigeration system arranged in a cascade relationship; a first heat exchanger using a first refrigerant in said high stage refrigeration system to extract heat from a second refrigerant in said low stage refrigeration system; a plurality of freeze pipes in the ground; a circulation path extending through said freeze pipes having a low temperature heat transfer fluid circulating therein to freeze the ground in proximity to said freeze pipes; and a second heat exchanger through which said circulation path passes, said second heat exchanger using said second refrigerant to extract heat from said heat transfer fluid for cooling thereof, said heat transfer fluid comprising aqua ammonia cooled to a temperature less than about âˆ’52Â° C. when passed through said second heat exchanger.