Size transverse

Despite the small gap size, transverse temperature and concentration gradients may exist in microchannels. These gradients depend on the rates of heat and mass transfer versus the rate of reaction. Da, as discussed above, provides an estimate of transport effects but cannot be used for quantitative modeling. The Nusselt number (Nu) and Sherwood number (Sh) provide the heat and mass transfer coefficients, respectively, between a surface and the bulk gas, in the direction perpendicular to the flow. They are defined as ratios of heat or mass flux at the boundary to the net flux between the bulk and the surface ... 

Eor an impact strength of 34 J (25 ft-lbf) the equivalent fracture toughness (150) is approximately 120 MPay. The fracture toughness dictates the critical size of crack above which fast fracture intervenes, so the smaller its value the smaller the critical crack and hence the greater significance of the transverse impact requirement specified by Manning. 

In addition to chemical analysis a number of physical and mechanical properties are employed to determine cemented carbide quaUty. Standard test methods employed by the iadustry for abrasive wear resistance, apparent grain size, apparent porosity, coercive force, compressive strength, density, fracture toughness, hardness, linear thermal expansion, magnetic permeabiUty, microstmcture, Poisson s ratio, transverse mpture strength, and Young s modulus are set forth by ASTM/ANSI and the ISO. 

The other detonability length scale is the detonation cell width, X (also called cell size) which is the transverse dimension of diamond shaped cells generated by the transverse wave stmctnre at a detonation front. It has a fish scale pattern (see Figure 4-4). Detonation cell widths are nsnally measured by the traces (soot) deposited on smoke foils inserted in test vessels or piping surfaces. The more reactive the gas-air mixture, the smaller is the cell size. The same is tme for chemical indnction length as a qualitative measure of detonability. The cell width, X, is a parameter that is of practical importance. The transition from dehagration to detonation, propagation, and transmission of a detonation, can to some extent be eval-... 

Nominal Pipe Size Inches Outside Diam- eter Inches Thick- ness Inches Inside Diameter Inside Diameter Funct (In Inches) ions Transverse Internal Area ... 

The following is extracted by permission from ACS Bulletin B-129 (Apr. 1992). Typical HETP is 3 in. compared to ACS product ST-100 of 7 in. Approximate comparison data are AP as low as 0.1-in. water/theoretical tray turn-dovm ratio about 20 1. Special series S construction recommended for smaller columns, and transverse Series X for larger ones. The suggested preliminary sizing procedure is ... 

With decreasing cell size, the temperature difference between the wall of the cell and the eatalyst partiele in the cell would decrease to zero. For sufficiently small cell dimensions, we may assume the two temperatures are the same. In this case, the heat conduction through the wall becomes dominant and affects the axial temperature profile. As the external heat exchange is absent and the outside of the reactor is normally insulated, the temperature profile is flat along the direction transverse to the reactant flow, and the conditions in all channels are identical to each other. The energy balance is... 

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