Frossling equation

A. Solid particles suspended in agitated vessel containing vertical baffles, continuous phase coefficient -2 + 0.6Wi f,.Wi D Replace Osi p with Vj = terminal velocity. Calculate Stokes law terminal velocity [S] Use log mean concentration difference. Modified Frossling equation K, -< T.d,P. [97] [146] p.220... 

The well-known Frossling equation seems applicable, as Sh = 2+ 0.6Rep5 Sc1/3. Replacing the values gives Sh = 10 and ki = 2.37 x 10 5m2/s. The Mears criterion becomes ... 

A. Solid particles suspended in agitated vessel containing vertical baffles, continuous phase coefficient A = 2 + 0.6N tNS Replace vz [p with uT = terminal velocity. Calculate Stokes law terminal velocity c d lp,-pjg K 18 ic and correct 1 10 100 1,000 10,000 100,000 [S] Use log mean concentration difference. Modified Frossling equation = Vn "P ° Re (Reynolds number based on Stokes law.) V -vTdrP° A Re,r — (terminal velocity Reynolds number.) kl almost independent of dp. Harriott suggests different correction procedures. Range ki/k is 1.5 to 8.0. [74] [ 138] p. 220-222 [110] [74]... 

S] Use log mean concentration difference. Modified Frossling equation ... 

For the case of small particles and negligible shear stress at the fluid boundary, the Frossling equation, Equation (11-41)), is approximated by... 

In bubbling beds, researchers [30,19] had used the term voidage, e, to modify the Frossling equation. Basu and Subbarao [1] presented the following tentative equation of mass transfer in a turbulent fluidized bed. 

The polymer particles/aqueous phase mass-transfer coefficient can be determined through the Frossling equation [73], where Sh is the Sherwood number. Re the Reynolds number, and Sc the Schmidt number. 

Liquid velocity around a particle affects its mass transfer boundary layer (Figure 5.3) and hence the mass flux. In forced convection, the dependence of the mass transfer coefficient on hydrodynamics is given by the Frossling equation... 

The case of combustion of an entire spherical surface with forced convection has not yet been solved. Frossling (4) originally proposed a semi-empirical relation for the low-temperature evaporation of droplets in motion. Spalding (60) has applied the equation to his heterogeneous combustion data with some success by including the term containing the transfer number ... 

For the small bubbles, an expression for the calculation of Ay has been obtained by the equation proposed by Frossling [7] for dissolution of a rigid sphere. 

Equation (4.7) can be used to calculate the relaxation time for incorporation of HTO into raindrops (Chamberlain Eggleton, 1964). The transport velocity to a spherical drop is given by Frossling s equation ... 

Equation (5.38) is known as the Frossling [14] equation or the Ranz and Marshall [15] equation. The exponents 1/2 and 1/3 come from bound-ary-layer theory, and the 0.6 is an empirical constant that gives the average coefficient over the sphere surface. The local coefficient is two to three times higher at the front of the sphere than at the point of boundary-layer separation. 

Frossling [6] had earlier presented an almost identical equation and showed theoretically that the Sherwood number should take on a value of 2 in a stagnant fluid moreover, there were theoretical grounds for expecting the square root dependence on the Reynolds number that he had observed experimentally. Frossling s experiments concerned the evaporation of nitrobenzene, aniline, water, and napthalene into a hot air stream, within the Reynolds number range 2 < < 1300. 

The subject of mass transfer from solid spheres has recently been examined by Keey and Glen [11], who maintained that the exponent of the Reynolds number in an equation of the Frossling type should increase with increasing Reynolds number due to the changing importance of wake transfer with Reynolds number and due to the onset of turbulence in the boundary layer. Keey and Glen recommended a different correlation for each Reynolds number region. 

---