Abstract: A ground freezing system includes a metal feed pipe for delivering refrigerant to the lower end of a freeze pipe installed in a bore in the ground. The feed pipe is supported on a compression spring which accommodates thermal contraction of the feed pipe while maintaining support of its weight.

Abstract: A ground freezing method and apparatus compensates for geothermal gradients by supplying more refrigerant to deeper parts of the earth. One or more metal freeze pipes are installed in a bore and equipped with one or more feed pipes. The feed pipes extend to different depths with the longer feed pipes being larger to supply more refrigerant to greater depths and achieve uniform top to bottom ground freezing despite the effects of geothermal gradients.

Abstract: A ground freezing system includes a metal feed pipe for delivering refrigerant to the lower end of a freeze pipe installed in a bore in the ground. The feed pipe is supported on a compression spring which accommodates thermal contraction of the feed pipe while maintaining support of its weight.

Abstract: A ground freezing method and system which circulates refrigerated heat transfer fluid through freeze pipes in the ground at a low temperature of at least −52° C. (−62° F.) to minimize drilling for the freeze pipe installation. The heat transfer fluid is preferably aqua ammonia (ammonium hydroxide) because of its beneficial characteristics in this application. The circulating heat transfer fluid is preferably cooled by a refrigeration system that includes low and high stage cycles arranged in a cascade relationship and using ammonia or another refrigerant in the high stage refrigeration system and carbon dioxide as the refrigerant in the low stage refrigeration system.

Abstract: A voice messaging system and method includes a voice recorder/playback device to store a plurality of voice messages associated with a respective plurality of incoming calls. A receiver receives call related information associated with each of the respective plurality of incoming calls. A controller is provided to organize the plurality of voice messages for playback by the voice recorder/playback device based on pre-stored groupings of expected call related information irrespective of an order in which voice messages are stored. In one aspect the pre-stored groupings relate to various priority levels for playback sequencing. In another aspect the pre-stored groupings relate to a specific voice mailbox or bin to receive the voice message. In yet another aspect, voice recognition techniques may be utilized to query the voice messaging system, either locally or remotely, for voice messages grouped in accordance with the principles of the present invention.