Adsorption Refrigeration using Zeolite-Water pair on Pro-e and MATLAB

The methods of production of cold by mechanical processes are quite recent. Long back in 1748, William Coolen of Glosgow University produced refrigeration by creating partial vacuum over ethyl ether. The first development took place in 1834 when Perkins proposed a hand operated compressor machine working on ether. Then in 1851 came Gorrie’s air refrigeration machine, and in 1856 Linde developed a machine working on ammonia. The pace of development was slow in the beginning when steam engines were the only prime movers known to run the compressors. With the advent of electric motors and consequent higher speed of compressors, the scope of refrigeration widened. The pace of development was considerably quickened in 1920 decade when du Pont put in the market the family of new working substances, the fluoro-chloro derivates of methane, ethane, etc.- popularly known as choloro fluoro carbons or CFCs under the of Freons. Recent developments involve finding alternatives or substitutes of Freons, since it has been found that chlorine atoms in Freons are responsible for depletion of ozone layer in upper atmosphere. Another noteworthy development was that of ammonia- water vapour absorption machine by Carre. These developments account for the major commercial and industrial applications in the field of refrigeration. A phenomenon called Peltier effect was discovered in 1834 which is still not commercialized. Advances in cryogenics, a field of very low temperature refrigeration, were registered with the liquefaction of oxygen by Pictet in 1877. Dewar made the famous Dewar flask in 1898 to store liquids at cryogenic temperatures. Then followed the liquefaction of other permanent gases including helium in 1908 by Onnes which led to discovery of the phenomenon of superconductivity. Finally in 1926, Giaque and Debye independently proposed adiabatic demagnetization of paramagnetic salt to reach temperatures near absolute zero. Here the main focus is on Zeolite-Water Solar Adsorption Refrigeration, Environmental protection initiates by environmental agencies are necessitating the replacement of chlorofluorocarbons with benign working fluids. One of the sensitive areas affected is refrigeration and heat pump technology, where new working pairs are being developed as an alternative to the traditional CFCs. This will have less impact of the destruction of ozone layer. In the design of adsorption refrigeration and heat pump systems, it is important to analyse precisely the performance of the cycle. This is based on an accurate determination off the adsorbent-adsorbate performance. Therefore, the thermodynamics behaviour of adsorbent materials has to be studied in details using a number of physical models, which are widely accepted. Various kinds of sorption systems have been developed, mostly of activated carbon-ammonia, activated carbon-methanol, silica gel- water and Zeolite-Water pairs. Nowadays, the refrigeration sector is one of the most important in the process industry. It was realised in the mid- 1970s that CFCs allow ultraviolet radiation into the earth’s atmosphere by destroying the protective ozone layer, while preventing infrared radiation from escaping the earth, and thus contributing to the greenhouse effect. The discovery of the ozone- depleting properties of CFCs and HCFCs refrigerants, and of their global warming potential, led to the Montreal Protocol, which scheduled the end of 1995, and of HCFCs by 2030. The production of these refrigerants has fallen dramatically in recent years. Researchers have recently focused on development of new refrigerants to replace CFCs and HCFCs. These new working fluids are synthetic compounds namely hydro fluorocarbons (HFCs). Although the ozone depletion potential of some of them is zero, their global warming potential related to the greenhouse effect- can be large. An alternative to HCFs in the use of naturally occurring substances (refrigerants) like ammonia, carbon dioxide, methanol, water and air. Consequently, from the 1970s interest in solid-vapour adsorption systems was rekindled in view of their energy saving potential in air conditioning and heat pump applications. Along with a consideration for energy efficiency, increasing attention was given to the use of waste heat and solar energy. Adsorption technologies have been used also extensively for separation and purification of gases for the past few decades but their exploitation for refrigeration is still limited. This has led to sorption technology receiving renewed attention due to environmental concerns. New classes of adsorbent-adsorbate pairs, like zeolite, silica gel or activated carbon, are gaining importance because they can replace CFC refrigerants. The advantages of such systems in comparison with conventional compression systems are- • Adsorption systems are environmentally friendly • They can use heat rather than electricity as the primary energy source. • No moving parts • No solution pumps • Silent and easy to maintain

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