Adsorption refrigeration
Adsorption refrigeration was invented by Michael Faraday in 1821, even though the basis of artificial modern refrigeration dates back to 1748 with William Cullen's experiments. Adsorption is sometimes referred to as solid sorption. It is very similar to absorption refrigeration (note that the second letter is different). The difference is that in adsorption refrigeration, the refrigerant or adsorbate vapour molecules adsorb onto the surface of a solid instead of dissolving into a liquid. In an adsorption system, an adsorber adsorbs the refrigerant vapour into a solid, while in an absorption system, an absorber absorbs the refrigerant vapour into a liquid. Adsorption refrigeration also includes a generation process where refrigerant vapour molecules desorb from the solid. In this process, there is no use of CFC's or ammonia the thermally driven cooling process is environment friendly. The characteristics of the adsorbate/refrigerant pair is crucial in determining the system performance of an adsorption refrigeration system. The typical system performance indicators for an adsorption refrigeration system are the coefficient of performance and the specific cooling effect. The refrigerants used in absorption systems are ammonia, water, or methanol, etc, which all experience phase changes between the vapor and liquid states - the same as in