Use of a water plenum and thermosiphon to control peak temperature in outdoor cabinets

Tests conducted at a Bellcore thermal test facility demonstrate that the temperature in a typical 12-ft³ unpowered telecommunications power supply cabinet, with 3 inch thermal insulation and a 20 gallon water plenum and thermosiphon, can be held to between 30 and 80°F. The upper limit of 80°F was not exceeded even after a week of sunny days and peak outdoor temperatures approaching 95°F. In wintertime tests, water temperature did not go below 32°F, and the air temperature inside the cabinet did not go much below 30°F. There was enough water to prevent complete freezing. These measured results tracked well with predicted inside temperatures determined using a previously developed thermal model and support the use of the model to predict results in other climates and for other cabinet parameters, such as size and amounts of insulation