Air at 80F, 1 atm, 80 relative humidity, and a superficial velocity of 100 ft min passes through a 5 ft high bed of 2 8 mmdiameter spherical particles of silica gel (b 39 lb ft3) The adsorption equilibrium isotherm at 80F is given by qH 2 O 15 9pH 2 O where q is in lb H 2 O lb gel and p is in atm T...

First determine the moisture content of the entering air From a psychrometric chart the entering humidity for 80 RH 80 o F and 1 atm is 00177 lb H2Olb ...

Air at 80F, 1 atm, 80% relative humidity, and a superficial velocity of 100 ft/min passes through

Question:

Air at 80°F, 1 atm, 80% relative humidity, and a superficial velocity of 100 ft/min passes through a 5-ft-high bed of 2.8-mmdiameter spherical particles of silica gel (ρb = 39 lb/ft3). The adsorption equilibrium isotherm at 80°F is given by

qH₂O = 15.9pH₂O

where q is in lb H₂O/lb gel and p is in atm. The overall mass-transfer coefficient can be estimated from (15-106), using an effective diffusivity of 0.05 cm2/s and with kc estimated from (15-65). Using the approximate concentration-profile equations of Klinkenberg, compute a set of breakthrough curves and determine the time when the humidity of the exiting air reaches 0.0009 lb H20/lb dry air. Assume isothermal and isobaric operation. Compare the time to breakthrough with the time for the equilibrium model. At breakthrough, what is the approximate width of the mass-transfer zone. What is the average loading of the bed at breakthrough?