The Problem
Vaccines prevent disease and save lives every year. However, vaccines are extremelysensitive to temperature and must be kept within a range of 2-8 degrees Celsius. In rural areaswith extremely warm climates and unreliable electricity, keeping vaccines at their optimaltemperature is a challenge. According to the World Health Organization, vaccines prevent morethan 2.5 million child deaths a year, yet nearly 24 million children under one year of age are notbeing vaccinated. There is a need for an alternative way of refrigerating vaccines to help theserural regions.
Adsorption refrigerators use thermal energy to keep the contents of the refrigerator at a desiredtemperature. At night, the pressure and temperature in the refrigerant system decrease, andthe heat from the cold chamber evaporates the liquid refrigerant. The adsorbent material in thesolar collector then adsorbs this vaporized refrigerant. During the day, the heat is absorbed by a silica gel, causing the pressure and temperature of the refrigerant in the adsorbent materialto increase. The refrigerant is then released as a vapor, which then travels in a condenser,releasing heat to the environment before it condenses back into a liquid. The refrigerant returnsback to the evaporator, and the cycle can begin again.
The solar fridge team has been designing and building a prototype of an adsorption solarrefrigerator that could easily be built on site. Our design uses a solar collector and cold chamberinsulated with polyurethane. At this point, we are running evaporation tests and continuing towork on the prototype.
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