Cryogenic fluids

Several types of fluids are used as refrigerants in mechanical compression systems ammonia, halocarbon compounds, hydrocarbons, carbon dioxide, sulfur dioxide, and cryogenic fluids. A wide temperature range therefore is afforded. These fluids boil and condense isotherm ally. The optimum temperature or pressure at which each can be used can be deterrnined from the economics of the system. The optimum refrigerant can be deterrnined only... 

NISTELUIDS NIST STN programs for calculating thermophysical and transport properties of cryogenic fluids... 

NASA is also considering a more advanced aircraft such as Mach 5 to cut Pacific travel time to about three hours, but in this case kerosene fuel is no longer acceptable, and Hquefted natural gas or Hquefted hydrogen would be needed to provide the necessary cooling and stabiUty. However, a completely new fueling system would be required at every international airport to handle these cryogenic fluids. 

In contrast to other cryogenic fluids, liquid oxygen is slightly magnetic. It is also chemically reactive, particularly with hydrocarbon materials. Oxygen thus presents a safety problem and requires extra precautions in handling. 

Past experience has shown that cryogenic fluids can be used safelv in industrial environments as well as in typical laboratories provided all facihties are properly designed and maintained, and personnel handling these fluids are adequately trained and supeiwised. There are many hazards associated with ciyogenic fluids. However, the principal... 

R.T. Jacobsen, S.G. Penoncello, E.W. Lemmon Thermodynamic Properties of Cryogenic fluids, Plenum Press, New York (1996)... 

Standard on Fire Protection for Laboratories Using Chemicals Recommended Practice on Materials, Equipment and Systems Used in Oxygen-Enriched Atmospheres Standard for the Storage, Use, and Handling of Compressed Gases and Cryogenic Fluids in Portable and Stationary Containers, Cylinders, and Tanks Liquefied Petroleum Gas Code... 

Zabetakis, M. G., Safety with Cryogenic Fluids, London, Heywood, 1967... 

For further discussion of heat transfer in cryogenic fluids, see R. J. Donnelly, Cryogenics, Physics Vade Mecum, ed. H.L. Anderson, AIP, NY (1981). For a recent discussion of contact resistance see also H. Jones, L. Cowey, and D. Dew-Hughes, Cryogenics 29 795 (1989). 

To presume that thermal insulation is always necessary is false. For example, when cryogenic fluids arc transported from a supply suurce to a vessel, even in bright sunshine, it is usually most economical not to insulate the line at all. The reason for this Is twofold (I) lor the short time of transport the area of the pipe exposed to the surt is much smaller than the area that would be exposed if it were insulated and (2i the heat that would be in the insulation when the transport starts would have to be removed by the cryogenic fluid. The combination of these two factors often makes the use of insulation undesirable for this type of cold fluid transport system. Moreover, the rapid formation of ice crystals front moisture in the air constitutes a thermal insulation. 

Vortex meters are being employed increasingly because of their accuracy, range, precision and relative insensitivity to fluid properties. They can be used for gases, saturated and superheated steam, low viscosity clean and dirty liquids, and cryogenic fluids 6 . They are not recommended for use when Re < 104. 

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