Relative humidity effects mass transfer

The other variables tested, i.e. temperature, amount of Ca(0H)2 and S02 concentration have a lower impact on the reaction rate. The different effect of S02 concentration at low and high relative humidity can be explained by assuming that the reaction has zero order kinetics in SO2 and that at low relative humidity the reaction rate is mass transfer controlled while at high relative humidities the reaction is controlled by reaction kinetics. 

Your plant has available a countercurrent cooling tower 10 m high and 6 m in diameter. The tower packing has a surface area per volume of about 63 m. At present, it is effectively cooling water at 3200 kg/min from 66 °C to 20 °C, using air at 80 mol/m sec at 18 °C and 20% relative humidity, (a) What is the mass transfer coefficient in this tower (b) You need 1000 kg/min water at 15 °C or less to cool a new chemical reactor. By how much should you reduce the water flow to get this output ... 

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