The solar refrigerator, developed by NPI, is a simplified and improved version of prior solar adsorption-desorption refrigerators ---refrigerators developed in recent years in Germany, France, and the U.S. All of these solar refrigerators have no moving parts. Water is used as the working fluid. The naturally occurring, highly porous silicon compounds (zeolites) are used as adsorbers. NPI's unique solar powered refrigerator produces about 5 lbs. of ice daily per cu. ft. of storage space.
NPI's seeks to help meet food storage needs for Third World families, with locally constructed solar refrigerators having the following parts:
1. An insulated, open-top solar collector box, about 7 ft. x 7 ft. (painted black), with
two-layers of glass (or other glazing) attached to the open-top. This box is used to collect solar heat via exposure to direct sunlight. A single 2 1/16-inch hole is drilled, on one side, to allow the exit of a 2-inch PVC pipe (see drawing).
2. A container, for zeolites, made of 6-inch PVC pipe generally forming a square