Cryogenic technologies vaporizers

Fig. 9.15 Saturation vapor pressure p of various substances retevant for cryogenic technology in a lemperalurerange ofT= 2-80 K...

Another factor augmectting the heat conductivuty of plastic foams under conditions is the absorbed moisture. For example, for CCljF-foamed polyurethane at 25 °C and a relative humidity of 65%, the ambient moisture diffusion rate is 10-20 g/m for 24 h. Especially strong is the effect of moisture on heat conductivity if the temperature differential across the sample is considerable. For example, in plastic foams used in cryogenic technology, the inner layers are exposed to low temperatures the water vapor first condenses and is then convected into ice. Since the thermoconductivity of water and ice are 0.5 and 1.5 kcal/m x h °C, respectively, even minor tunounts have a considerable detrimental effect of the heat insulating capacity of a foam material... 

Jazayeri, B. (1977). Impact cryogenic vapor explosions. S.M. Thesis, Chem. Eng., Massachusetts Institute of Technology. Cambridge. 

FIGURE 15.24 Three-stage flow path for the cryogenic preconcentration of VOCs from air and the removal of water vapor by microscale purge and trap, Entech Technologies, Inc. 

Since the compounds being separated are not normally reactive with each other and also because chemical reactions are extremely slow at cryogenic temperatures, cryogenic separation operations are purely physical. They follow the same vapor-liquid equilibria principles and system design technologies as commonly used for separating hydrocarbons that are liq-... 

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