Adsorption refrigeration was invented by

Michael Faraday Michael Faraday (; 22 September 1791 – 25 August 1867) was an English scientist who contributed to the study of electromagnetism and electrochemistry. His main discoveries include the principles underlying electromagnetic inducti ...

in 1821, even though the basis of artificial modern refrigeration dates back to 1748 with

William Cullen William Cullen FRS FRSE FRCPE FPSG (; 15 April 17105 February 1790) was a Scottish physician, chemist and agriculturalist, and professor at the Edinburgh Medical School. Cullen was a central figure in the Scottish Enlightenment: He was ...

's experiments. Adsorption is sometimes referred to as solid sorption. It is very similar to

absorption refrigeration An absorption refrigerator is a refrigerator that uses a heat source (e.g., solar energy, a fossil-fueled flame, waste heat from factories, or district heating systems) to provide the energy needed to drive the cooling process. The system uses t ...

(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 Solid is one of the four fundamental states of matter (the others being liquid, gas, and plasma). The molecules in a solid are closely packed together and contain the least amount of kinetic energy. A solid is characterized by structural ...

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 The coefficient of performance or COP (sometimes CP or CoP) of a heat pump, refrigerator or air conditioning system is a ratio of useful heating or cooling provided to work (energy) required. Higher COPs equate to higher efficiency, lower energy ( ...

and the specific cooling effect. The refrigerants used in absorption systems are

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous wa ...

, water, or methanol, etc, which all experience phase changes between the vapor and liquid states - the same as in vapor compression refrigeration; while the adsorbent is a solid, such as

silica gel Silica gel is an amorphous and porous form of silicon dioxide (silica), consisting of an irregular tridimensional framework of alternating silicon and oxygen atoms with nanometer-scale voids and pores. The voids may contain water or some other l ...

, activated carbon, or

zeolite Zeolites are microporous, crystalline aluminosilicate materials commonly used as commercial adsorbents and catalysts. They mainly consist of silicon, aluminium, oxygen, and have the general formula ･y where is either a metal ion or H+. These p ...

. For example, an adsorption refrigeration device with

active carbon Activated carbon, also called activated charcoal, is a form of carbon commonly used to filter contaminants from water and air, among many other uses. It is processed (activated) to have small, low-volume pores that increase the surface area availa ...

fiber as the adsorbent and

as the refrigerant was designed. Adsorption refrigeration has been extensively researched in recent years because the technology is often noiseless, non-corrosive and environmentally friendly. The heat source for adsorption refrigeration can be fossil fuel, biomass fuel, nuclear fission, geothermal energy,

waste heat Waste heat is heat that is produced by a machine, or other process that uses energy, as a byproduct of doing work. All such processes give off some waste heat as a fundamental result of the laws of thermodynamics. Waste heat has lower utility ...

, or

solar thermal energy Solar thermal energy (STE) is a form of energy and a technology for harnessing solar energy to generate thermal energy for use in industry, and in the residential and commercial sectors. Solar thermal collectors are classified by the United St ...

. Adsorption refrigerators are available in the marketplace and are mainly used to produce chilled water from

. Gas adsorption

heat pump A heat pump is a device that can heat a building (or part of a building) by transferring thermal energy from the outside using a refrigeration cycle. Many heat pumps can also operate in the opposite direction, cooling the building by removing ...

s are not currently available in the UK, but are just being introduced in Europe as small water or ground source packaged units that provide domestic, low-temperature space heating.{{cite web , url=https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/787321/Gas_Drive_heat_pumps.pdf , title=Gas driven heat pumps , publisher=Department for Business, Energy & Industrial Strategy , location=London , date=September 2016

References

Refrigerants