Resistant coefficient

Ki Resistance coefficient of conditioned filter fabric kPa/(m/min) in water/(ft/min) ... 

K, Resistance coefficient of dust cake on filter fabric kPa in water ... 

The specific resistance coefficient for the dust layer Ko was originally denned by Williams et al. [Heat. Piping Air Cond., 12, 259 (1940)], who proposed estimating values of the coefficient by use of the Kozeny-Carman equation [Carman, Trans. Inst. Chem. Fng. (London), 15, 150 (1937)]. In practice, K and Ko are measured directly in filtration experiments. The K and Ko values can be corrected for temperature by multiplying by the ratio of the gas viscosity at the desired condition to the gas viscosity at the original experimental conditions. Values of Ko determined for certain dfists by Williams et al. (op. cit.) are presented in Table 17-5. 

Lapple (in Periy, Chemical Engineers Handbook, 3d ed., McGraw-Hill, New York, 1950) presents an alternative form of Eq. (17-10) in which the gas-viscosity term is explicit instead of being incorporated into the resistance coefficients ... 

TABLE 17-5 Specific Resistance Coefficients for Certain Dusts ... 

The turbulent regime for Cq is characterized by the section of line almost parallel to the x-axis (at the Re" > 500). In this case, the exponent a is equal to zero. Consequently, viscosity vanishes from equation 46. This indicates that the friction forces are negligible in comparison to inertia forces. Recall that the resistance coefficient is nearly constant at a value of 0.44. Substituting for the critical Reynolds number, Re > 500, into equations 65 and 68, the second critical values of the sedimentation numbers are obtained ... 

The slope of the curve in the transitional zone changes from 135 to 180°. It shows that the exponent in changes as follows 0 a 1. This means that the friction and inertia forces are commensurable in the process of sedimentation. Several empirical formulas have been proposed for estimating the resistance coefficient in the transition zone. One such correlation is... 

Once the diameter is known, the Reynolds number. Re can be computed and the friction factor f obtained from Figure 21. Assuming a straight length of pipe for L = 5(X) ft, N (line resistance factor) can be calculated. Next Gj, is calculated based on the downstream pressure and G/G j evaluated. From Figure 20 the ratio Pj/Pfl can be obtained. Since Pj is known, Pq can then be calculated. The pressure at the inlet of the knock-out drum is given by Pq -I- 0.5 psi. Table 6 provides typical values of resistance coefficients for various pipe fittings. 

Table 6. Resistance coefficient K for various pipe fittings.

K l = specific dust/fabric filter resistance coefficient C, = inlet dust concentration (g/m- )... 

The rolling resistance coefficient of a tire depends on the construction of the tire carcass, the elastic characteristics of the tire material, the tread design, and characteristics of the roadbed. It increases with decreasing wheel diameter, tire underinflation, and roadbed compliance. It decreases as the operating temperature of the tire rises. 

Before the 1960s, the bias-ply tire exemplified standard construction. It had a typical rolling resistance coefficient of 0.015 on hard pavement. Since then, the radial-ply tire has emerged, offering a coefficient closer to 0.010. Coefficients as low as 0.008 to 0.009 have been claimed in tires suitable for use on passenger cars. Cutting the coefficient from 0.015 to 0.008 offers the opportunity for about a 10 percent reduction in fuel consumption. 

Rolling Resistance Coefficient of Various Tire Types... 

Typical ranges for the rolling resistance coefficients of passenger car and truck tires in normal seiw-ice (vs. a steel wheel) are given in Table 1. 

Truck tires are operated at about four times the inflation pressure of passenger car tires, which principally accounts for truck tires lower rolling resistance coefficients. 

Figure 2-12A. Resistance coefficients for fittings. Reprinted by permission, Hydraulic Institute, Engineering Data Book, 1st Ed., 1979, Cleveland, Ohio.

The head loss has been correlated as a function of the velocity head equation using R as the resistance coefficient in the equation. 

K Factor Table Representative Resistance coefficients (K) for Valves and Fittings... 

The resistance coefficient. Kb, for pipe bends other than qo° may be determined as follows ... 

---