Low-temperature applications

Nickel alloys have two main properties good resistance to corrosion and high-temperature strength. There are alloys for medium-and low-temperature applications and for high-temperature conditions in which creep resistance is of main importance [24]. 

R-508B) CFC-13 for R-503 and CFC-13 in very low-temperature applications (less than —40° F)... 

Propane, propylene, and ethylene are used in large refrigeration tonnage and very low temperature applications. 

Used by permission Rehrig, P. Hydrocarbon Processing V. 60, No. 10, p. 137, 1981. Gulf Publishing Company, Houston, Texas. All rights reserved. Table 12-8D Impeller Material for Low-Temperature Applications ... 

No moving parts, hence little maintenance required may be mounted at considerable height or, in low-temperature applications, set flush into building structure. 

Pressure drops on the high-pressure side will be small enough to have little effect on the performance of the complete system. Pressure losses in the suction pipe and its fittings, especially if this is long, should be checked, and a correction made for the actual compressor suction pressure. For low-temperature applications, pipe sizes may have to be increased to avoid excessive frictional losses at these low pressures. 

Surface Studies with the Vacuum Microbalance Instrumentation and Low-Temperature Applications T. N. Rhodin, Jr. 

Finally, we have discussed the effect of incomplete Cj oxidation product formation for fuel cell applications and the implications of these processes for reaction modeling. While for standard DMFC applications, formaldehyde and formic acid formation will be negligible, they may become important for low temperature applications and for microstructured cells with high space velocities. For reaction modeling, we have particularly stressed the need for an improved kinetic data base, including kinetic data under defined reaction and transport conditions and kinetic measurements on the oxidation of Ci mixtures with defined amounts of formaldehyde and formic acid, for a better understanding of cross effects between the different reactants at an operating fuel cell anode. 

Cu-ZSM5, already above 250°C, a considerable amount of ammonia is not going into in the SCR reaction, which suggests that this catalyst is used more for low-temperature applications. 

Nowadays, most of the car manufacturers are interested to replace noble metals by cheaper active phases or at least to significantly lower their content without altering their tolerance to poisoning effects. Recent developments using gold and silver as active components specifically for low temperature applications could be promising, but their sulphur tolerance is questionable in those temperature conditions [12-14], Apparently, such an aspect may exclude an extensive development of those silver-based catalysts for NO abatement processes for stationary sources. 

The terpolymer is used in roller production and in many low temperature applications. 

Usually, silicon polymers have extremely low Tgs owing to the highly flexible Si—0 linkages in the main chain. Their low Tg s are very advantageous for low-temperature applications, whereas some other applications are limited. One approach to raise the Tg of silicon polymers is the introduction of aromatic rings into the polymer backbone. 

On the other hand, the presence of these esters in the electrolyte solutions raised concern over the longterm performance at room temperatures, because EIS studies indicated that the resistance associated with the SEI film increased at a much higher rate for ester-based electrolytes as compared with the compositions that were merely based on carbonates. The authors attributed this rising cell impedance to the reactivity of these esters toward the electrode active material, which resulted in the continued growth of the SEI film in the long term and suggested that alkyl esters, especially those of acetic acid, might not be appropriate cosolvents for low-temperature application electrolytes. ... 

The electrolyte is usually 20-28% aqueous solution of KOH. Solid-state compositions of KOH aqueous electrolyte obtained by addition of poly(ethylene oxide) [345] or polymer based electrolyte (based on polyacrylates) were also proposed [346]. For low temperature applications, higher concentrations of KOH were used, while for higher temperatures, sodium hydroxide was sometimes applied. The influence of the temperature from 0 to 200 °C, pressure and electrolyte concentration on the thermodynamic parameters of the cells, was studied in detail [347]. 

Diesel fuel and kerosene alone are not effective solvents for use in solubilizing most WCMs for low-temperature application. The low KB value of diesel fuel and kerosene makes these fuels ineffective at holding the WCM in solution for extended periods of time at low temperatures. Stratification and separation of the WCM from solution can lead to application problems such as filter plugging and inaccurate WCM treatment. 

In some cases, blade-type rotary compressors are used in low temperature applications as high volume, low stage, or booster compressor (Fig. 9). These booster compressors are applied at suction conditions varying from —87 to — 20°C with compression ratios of 7 1 using CFC-12, HCFC-22, or ammonia. 

Addition poly(imide) oligomers are used as matrix resins for high performance composites based on glass-, carbon- and aramide fibers. The world wide market for advanced composites and adhesives was about 70 million in 1990. This amounted to approximately 30-40 million in resin sales. Currently, epoxy resins constitute over 90% of the matrix resin materials in advanced composites. The remaining 10% are unsaturated polyester and vinylester for the low temperature applications and cyanate esters and addition poly(imides) for high temperatures. More recently thermoplastics have become important and materials such as polyimides and poly(arylene ether) are becoming more competitive with addition polyimides. 

For illustration, a number of high-temperature gas-phase processes are discussed in some detail in this and the following chapter. Low-temperature applications such as atmospheric chemistry are outside the scope of this book. High-temperature gas-phase reactions are important in combustion, incineration, flue gas-cleaning, petrochemical processes, as well certain processes in chemical synthesis and materials production. While the details of these systems may vary significantly, they share some characteristics that are common for all gas-phase reaction mechanisms. 

Therm alane L is a synthetic paraffin intended for low temperature applications. Therm alane 600 and Therm alane 800 are synthetic paraffins. 

---