Molecular speed ratio

Molecular speed ratio, S = Ma (7/2 )0-5, where /is the ratio of specific heats ... 

When free-molecule flow is encountered, Oppenheim [8] has given convenient charts for calculating recovery factors and heat-transfer coefficients for flow over standard geometric shapes. Figures 12-16 and 12-17 give samples of these charts. The molecular speed ratio S used in these charts is defined by... 

An inspection of Fig. 12-13 shows that the free-molecule range is encountered. Accordingly, we can make use of Figs. 12-16 and 12-17 to compute the heat-transfer parameters. The molecular speed ratio is calculated as... 

Step 3. Refer to Figure 4-7 and select an efficiency at a pressure ratio of 3 and a volume ratio, r of 2.44. The adiabatic efficiency is 74%. Now, from Figure 4-5, select a value of efficiency ratio using the tip speed ratio just calculated. Because the value is. 99+, round off to an even 1.0. With a multiplier of 1.0, the final adiabatic efficiency is the value read directly off the curve or T a = 74. The molecular weight correction for efficiency, per rule of thumb, is 0.6 for a final efficiency of 73.4. 

A mechanical pump providing even lower vacuum levels is the turbomolecular pump, in which one or more balanced rotors (turbine blades) spin at 20,000 to 50,000 rpm. At these rotation rates, the periphery moves at a speed that exceeds the mean molecular speeds of most molecules, and gas-rotor collisions impart a momentum component to the gas in the direction of the exhaust. Compression ratios up to 10 can be achieved as long as the outlet pressure is kept below about 0.1 Torr by a forepump. 

U Deposition Uniformity U = fjf = f ) f) Reactant Mean Molecular Speed X Transverse Position z Normalized Transverse Position (z = x/a) a Ratio of Diffusivities P Deposition Modulus A Reactant Mean Free Path Normalized Preform Thickness p Total Molar Density o Reactive Species Molecular Diameter ( ) Reaction Probability / Net Molar Yield of Deposition Reaction... 

Two gases effuse through a hole. Gas A has nine times the molecular mass of gas B. What is the ratio of the two molecular speeds ... 

Graham s law. Equation 10.24, approximates the ratio of the diffusion rates of two gases under identical conditions. We can see from the horizontal axis in Figure 10.18 that the speeds of molecules are quite high. For example, the rms speed of molecules of N2 gas at room temperature is 515 m/s. In spite of this high speed, if someone opens a vial of perfume at one end of a room, some time elapses—perhaps a few minutes— before the scent is detected at the other end of the room. This tells us that the diffusion rate of gases throughout a volume of space is much slower than molecular speeds. This difference is due to molecular collisions, which occur frequently for a gas at atmospheric pressure—about 10 times per second for each molecule. Collisions occur because real gas molecules have finite volumes. 

Fig. 2.2 Velocity distribution from effusive molecular beam (dot) and supersonic molecular beam solid line). Both curves are normalized to unity at the most probable velocity and are for helium at a reservoir temperature of 300 K. The curve for the supersonic molecular beam assumes the speed ratio v/Av =10...

A Ratio of peripheral speed of centrifuge to mean molecular speed,... 

Nitric acid being the solvent, terms involving its concentration cannot enter the rate equation. This form of the rate equation is consistent with reaction via molecular nitric acid, or any species whose concentration throughout the reaction bears a constant ratio to the stoichiometric concentration of nitric acid. In the latter case the nitrating agent may account for any fraction of the total concentration of acid, provided that it is formed quickly relative to the speed of nitration. More detailed information about the mechanism was obtained from the effects of certain added species on the rate of reaction. 

Tensile Properties. Tensile properties of nylon-6 and nylon-6,6 yams shown in Table 1 are a function of polymer molecular weight, fiber spinning speed, quenching rate, and draw ratio. The degree of crystallinity and crystal and amorphous orientation obtained by modifying elements of the melt-spinning process have been related to the tenacity of nylon fiber (23,27). 

Silicone acrylates (Fig. 5) are again lower molecular weight base polymers that contain multiple functional groups. As in epoxy systems, the ratio of PDMS to functional material governs properties of release, anchorage, transfer, cure speed, etc. Radiation induced radical cure can be initiated with either exposure of photo initiators and sensitizers to UV light [22,46,71 ] or by electron beam irradiation of the sample. 

Typical features of a plywood resole formulation are a formaldehyde-to-phenol molar ratio in the 2.0 1 to 2.5 1 range, programmed formaldehyde, an alkali content from 4 to 8 wt% (calculated as sodium hydroxide), and pan solids of 40-50%. Resins used for laminated veneer lumber (LVL) tend to be similar to plywood resins in composition and molecular weight, though they are often designed for high-end cure speed. 

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