The term cryogenics derives from the Greek kryos, for icy cold. The upper limit that characterizes the cryogenic region of the temperature scale is subjective. If the delimitation criterion takes into consideration practical reasons, then this upper limit can be established at a higher than usually declared value (120 K) in order to include natural gas fuel liquefaction. The cryogenics region of the temperature scale 0–120 K can be divided into sub regions according to the criteria of the cryogenic method and refrigerant (known as crycoolers) as follows: (more…)

The idea of using an absorption fluid as a refrigerant carrier derived from the drawback of VCR (vapor–compression refrigeration) systems that the gas compression requires a high work input. A pump that requires practically no work to increase the pressure in the refrigeration system replaces the complicated and work-consuming compressor. There are two major advantages of absorption refrigeration systems (ARSs) compared with VCRs (vapor–compression refrigeration): No CFCs or HCFCs are used as refrigerants, and they use heat from different sources, such as combustion, industrial processes, waste heat (an economical solution for recovery), or solar heat. (more…)