Calculate the mass transfer coefficient, ky, during the spray drying of soluble coffee. The average air temperature during drying is 110C and the air flows with velocity of 0.51m/s countercurrently to atomize coffee droplets which are 150m in diameter. Assume that the droplets are uniform in size, neither swell nor shrink and DAB=2.6105m2/s. Air density and viscosity can be taken as 0.922kg/m3 and 22.17106Pa.s(ky=0.0165kgmol/m2.s)