Cooling sorption

Introduction of the Si specimens into a vacuum chamber should be done carefully. When the specimen is in the atmosphere, H Si(lll) and organic-modified Si are not positively contaminated within a short period. The largest chance of contamination is when the surface is in the stage of initial vacuum pumping. The residual gas in the vacuum generated by oil rotary pump is water and oil, and the latter causes severe hydrocarbon contamination. It is necessary to use an oil-free pump, such as liquid-nitrogen cooled sorption pump or helium cooled cryopump, for evacuation from atmospheric pressure. After quick, clean evacuation from the atmospheric pressure to Torr, the... 

In an open sorption storage system air is transporting water vapor and heat in and out of the packed bed of solid adsorbents (see Figure 235) or a reactor where the air is in contact with a liquid desiccant. In desorption mode a hot air stream enters the packed bed or the reactor, desorbs the water from the adsorbent or the salt solution and exits the bed cooler and saturated. In adsorption mode the previously humidified, cool air enters the desorbed packed bed or the... 

The self cooling beer keg is based on the principle of closed sorption systems shown in chapter Y2 Figure 8. Figure 244 shows the beer keg from the outside and the inside. 

The application of open sorption systems can provide dehumidification by the adsorption of water vapor and sensible cooling by adiabatic humidification (after a cold recovery for the dried air) at temperatures between 16 °C and 18 °C. Conventional systems have to reach temperature as low as 6 °C or lower in order to start dehumidification by condensation. For comfort reasons this cold air has to be heated up to about 18 °C before released into the building. This shows that open sorption systems can provide in general an energetically preferable solution. 

In a sorption pump, the gas is trapped within the adsorbing material (zeolites or active charcoal) called molecular sieve. Zeolites are porous aluminium silicates which adsorb large amount of gas when cooled to low temperature (usually 77K). The pump is filled with zeolite and put in a bucket containing liquid nitrogen (see Fig. 1.11). 

Dunne, S.R. and Behan, A.S. (1995) Adsorbent composites for sorption cooling process and apparatus. US Patent 5,518,977. 

An all-glass apparatus was used for gravimetric sorption measurement with benzene as adsorbate. Prior to the measurement, the sample was heated to 360 C at a rate of 5 C/ min with simultaneous evacuation to 1.3 10 Pa, and further degassed at that temperature for 3 h. Then the sample was cooled down to 32X3, at which the benzene adsorption isotherm was measured. 

In addition to substantial differences in the sorption behavior of products, the moisture distribution in each vial of one charge must be considered when the SD process is developed. Pikal and Shaw [1.59] studied this distribution in dextran 40, human serum albumin (HSA), bovin somatotropin (BST) and glycine. Thirty vials where filled with 10 or 20 mm cake thickness, loaded on shelves at 5 °C, cooled to -40 °C and frozen in 30-45 min. Tc was determined for all products as >-12 °C. In Table 1.10.6 the water content of four products is shown in four different positions... 

Sorption, Kinetics and Transport. If wood is immersed directly in liquid ammonia at ambient pressure, convection of the liquid is inhibited by the presence of air, and if the wood is at ambient temperature, it must be cooled to less than -30° C before liquid can flow into the pore structure. Nevertheless, under the best of circumstances much of the wood substance must be reached by diffusion rather than convection because a variety of physical restrictions inhibit liquid flow in wood (37,38). 

Sorption effects in the macroscopic scale are usually used for non-continuous pumping. They contain a highly porous sorption material like activated carbon or zeolites with a huge inner surface. The sorption material is usually cooled down by liquid nitrogen. They are regenerated by heating the sorption material to temperatures of several hundred degrees Celsius after a disconnection of pump and vacuum-chamber. 

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