Question

If Da is diffusivity, CT is tracer concentration and UT is overall heat transfer coefficient, then the pulse tracer balance with dispersion is obtained as ____

(a) (frac{∂^2 C_T}{∂z^2} – frac{∂U_T}{∂z} = frac{∂C_T}{∂z} )

(b) Da(frac{∂^2 C_T}{∂z^2} – frac{∂U_T}{∂z} =frac{∂C_T}{∂z} )

(c) Da(frac{∂^2 C_T}{∂z^2} + frac{∂U_T}{∂z} =frac{∂C_T}{∂z} )

(d) Da(frac{∂C_T}{∂z^2} – frac{∂U_T}{∂z} =frac{∂C_T}{∂z} )

Answer 1

Correct choice is (a) (frac{∂^2 C_T}{∂z^2} – frac{∂U_T}{∂z} = frac{∂C_T}{∂z} )

Explanation: The equation (frac{∂^2 C_T}{∂z^2} – frac{∂U_T}{∂z} = frac{∂C_T}{∂z} ) is obtained by a combination of mole balance on inert tracer and the molar flow rate of tracer by both convection and dispersion.