List of top Chemical, Thermal and Polymer Engineering Questions on Mass Transfer asked in GATE Chemical Engineering

A wet solid of 100 kg containing 30 wt% moisture is to be dried to 2 wt% moisture in a tray dryer. The critical moisture content is 10 wt% and the equilibrium moisture content is 1 wt%. The drying rate during the constant rate period is 10 kg/(h m²). The drying curve in the falling rate period is linear. If the drying area is 5 m², the time required for drying ___________ h (rounded off to 1 decimal place).

Solute \(A\) is absorbed from a gas into water in a packed bed operating at steady state. The absorber operating pressure and temperature are 1 atm and 300 K, respectively. At the gas-liquid interface, \(y_i = 1.5 x_i\), 
where \(y_i\) and \(x_i\) are the interfacial gas and liquid mole fractions of \(A\), respectively. At a particular location in the absorber, the mole fractions of \(A\) in the bulk gas and in the bulk water are 0.02 and 0.002, respectively. If the ratio of the local individual mass transfer coefficients for the transport of \(A\) on the gas-side (\(k_y\)) to that on the water-side (\(k_x\)), \(\frac{k_y}{k_x} = 2\), then \(y_i\) equals _________ (rounded off to 3 decimal places).