2. A feed solution of 4000 kg/hr at 45°C containing Na2CO3 is cooled to 30°C to produce sodium car- bonate monohydrate crystals. The average heat capacity of the feed can be assumed 2.93 kJ/kg-K. How many units of Swenson-Walker crystallizer will be needed? Assume the area as 2m2/m length and U = 400 W/m2-K.