Simultaneous momentum, heat, and mass transfer: alternate boundary conditions (Fig. 20B.7). The dimensionless profiles II (η, Λ, K) in Eq. 20.2-43 are applicable to a variety of situations. Use Eqs. 20.2-49 to 52 to obtain equations for the evaluation of the dimensionless net mass flux K for the following cases: 

(a) Evaporation of pure liquid A from a saturated porous plate into a gaseous stream of A and B. Substance B is insoluble in liquid A. 

(b) Instantaneous irreversible reaction of gas A with a solid plate of C to give gaseous B, according to the reaction A + C → 2B. The molecular weights of A and B are equal. 

(c) Transpiration cooling of a porous-walled hollow plate, as shown in the figure. The fluid is pure A throughout, and the injected fluid is distributed so as to maintain the whole outer surface of the plate at a uniform temperature T₀.

Transcribed Image Text:

Approaching stream of gas A at temperature T and velocity v Injection velocity v, (x) Surface at uniform temperature To Porous wall Gas A at uniform temperature T, +- Gas A in Porous wall-