Operating temperature range

Fig. 3. Comfort 2ones at 6% of population predicted dissatisfied from ref 4. RH lines are valid only when the air temperature equals the average temperature of the surfaces, (a) Operative temperature range where ET is effective temperature as defined in text, (b) Comfort 2one detail. To convert...

Thermal Properties. Modified ETFE copolymer has a broad operating temperature range up to 150°C for continuous exposure (24). Cross-linking by radiation improves the high temperature capabiUty further. However, prolonged exposure to higher temperatures gradually impairs the mechanical properties and results in discoloration. 

The most widely used and best known resistance furnaces are iadirect-heat resistance furnaces or electric resistor furnaces. They are categorized by a combination of four factors batch or continuous protective atmosphere or air atmosphere method of heat transfer and operating temperature. The primary method of heat transfer ia an electric furnace is usually a function of the operating temperature range. The three methods of heat transfer are radiation, convection, and conduction. Radiation and convection apply to all of the furnaces described. Conductive heat transfer is limited to special types of furnaces. 

Therminol Heat-Transfer Fluids. Monsanto Chemical Co. manufactures a series of synthetic heat-transfer fluids that offer a wide operating temperature range. AH of these fluids, except for Therminol VP-1 and Therminol LT, are intended for Hquid-phase operation only. Monsanto also offers the two natural petroleum oil-based heat-transfer fluids discussed. 

This reaction is commonly known as the CO or water gas shift reaction. The conversion of CO by this reaction is slightly exothermic and favored by lower temperatures. The lower practical operating temperature range for this reaction is between 180 and 200°C (8). 

Continuous-flow stirred-tank reactors ia series are simpler and easier to design for isothermal operation than are tubular reactors. Reactions with narrow operating temperature ranges or those requiring close control of reactant concentrations for optimum selectivity benefit from series arrangements. 

Freeze Point Depression. The slight heat-transfer penalty incurred when an antifreeze is added to the aqueous heat-transfer fluid is necessitated by the need for increased operating temperature range in most internal combustion engines. Because most parts of the world achieve temperatures below freezing during some time of the year, an antifreeze fluid is required to keep equipment operational in these subfreezing temperatures. 

In catalytic toluene hydrodealkylation, toluene is mixed with a hydrogen stream and passed through a vessel packed with a catalyst, usually supported chromium or molybdenum oxides, platinum or platinum oxides, on siHca or alumina (50). The operating temperatures range from 500—595°C... 

The precious-metal platinum catalysts were primarily developed in the 1960s for operation at temperatures between about 200 and 300°C (1,38,44). However, because of sensitivity to poisons, these catalysts are unsuitable for many combustion apphcations. Variations in sulfur levels of as Httle as 0.4 ppm can shift the catalyst required temperature window completely out of a system s operating temperature range (44). Additionally, operation withHquid fuels is further compHcated by the potential for deposition of ammonium sulfate salts within the pores of the catalyst (44). These low temperature catalysts exhibit NO conversion that rises with increasing temperature, then rapidly drops off, as oxidation of ammonia to nitrogen oxides begins to dominate the reaction (see Fig. 7). 

In ae off-line eonverters, aluminum eleetrolytie eapaeitors are used as the input filter eapaeitor. They have proven to be more rugged than any other type of eapaeitor in the hazardous environment existing on the ae line. Choosing the final eapaeitor depends mostly upon the expeeted operating temperature range, quality level, and ease dimensions. 

Proper fluid must be chosen and used in the system. It must have the best viscosity, operating temperature range and other characteristics that are conducive to proper operation of the system and lowest possible friction component. 

Selection and care of the hydraulic fluid for a machine will have an important effect on how it performs and on the life of the hydraulic components. During the design of equipment that requires fluid power, many factors are considered in selecting the type of system to be used-hydraulic, pneumatic, or a combination of the two. Some of the factors required are speed and accuracy of operation, surrounding atmospheric conditions, economic conditions, availability of replacement fluid, required pressure level, operating temperature range, contamination possibilities, cost of transmission lines, limitations of the equipment, lubricity, safety to the operators, and expected service life of the equipment. 

In considering these benefits, the user should not overlook the constraints in using such fluids. They can be summarized as limited wear and corrosion protection (especially with certain metals), increased leakage due to its low viscosity, limited operating temperature range and the need for additional mixing and in-service monitoring facilities. 

A summary of the chemical and abrasion resistances, and approximate operational temperature ranges of elastomers is given in Table 18.16. Further details of specific chemical resistances are given in Table 18.17. The maximum temperature of use will always be dependent on the chemical conditions prevailing. Abrasion resistance can be affected by the chemical environment if the exposed surface properties are changed by adsorption or chemical attack. The rate of material loss by abrasion will also vary according to temperature as the resilience etc. is dependent on prevailing temperature conditions. 

The battery, which features a high (3.6 V) operating voltage and wide operating temperature range (-55 to 85 °C) can serve as a memory backup power source. Table 9 shows their specifications (381. 

A final, obvious but important, caution about catalyst film preparation Its thickness and surface area Ac must be low enough, so that the catalytic reaction under study is not subject to external or internal mass transfer limitations within the desired operating temperature range. Direct impingement of the reactant stream on the catalyst surface1,19 is advisable in order to diminish the external mass transfer resistance. 

The table also gives the catalyst material, the operating temperature range, the maximum (for A>1) or minimum (for A<-1) measured A value and the maximum (for p>l) or minimum for (prate enhancement, p, value. It also provides the maximum measured promotion index, PIi5 value. An asterisk in the p column indicates that electrochemical promotion causes also a change in product selectivity. 

The type of initiator used affects the molecular weight and conversion limits in a reactor of fixed size and the molecular weight distribution of the material produced at a given conversion level. The initiator type also dictates the amount of initiator which is necessary to yield a given conversion to polymer, the operating temperature range of the reactor and the sensitivity of the reactor to an unstable condition. Clearly, the initiator is the most important reaction parameter in the polymer process. 

For the practical use of this CO removal reactor, the microchannel reactor should be operated carefully to maintain operating temperature ranges because the reaction temperature is critical for the microchannel reactor performance such as CO conversion, selectivity and methanation as disclosed in the above results. It also seems that the present microchannel reactor is promising as a compact and high efficient CO remover for PEMFC systems. 

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