The Appropriate Technology Collaborative (ATC), working with a team of engineering students and professors from Michigan State University, has devised a solar vaccine refrigerator for Create the Future Design Contest 2010 that could be of tremendous help to physicians serving in rural parts of Africa and Asia. The refrigerator, dubbed as ATC Solar Vaccine Refrigerator, can be created anywhere with a little knowledge of the material used in fabrication.
Made from simple materials like steel, charcoal and ethanol or methanol, the freezer can run on biofuels if there is no sunshine. Else, the steel box – painted black for maximum light absorption – filled with activated charcoal, some pipes with cooling fins and a container of ethanol utilizes solar energy alone. The solar collector gathers ample solar energy to make the charcoal reject the ethanol vapor. The rejected ethanol vapor flows into the condenser, where it condenses into a liquid. Then gravity leads the liquid to flow into the evaporator – located inside an insulated box. Cool charcoal absorbs ethanol vapor and forces the liquid ethanol to adsorb back into charcoal at night. The ethanol left in the evaporator cools the insulated box down to 0 to -10 degrees Celsius.