Two tons per hour of the dodecahydrate of sodium phosphate (Na3PO4 ∙ 12H2O) is to be crystallized by cooling, in a cooling crystallizer, an aqueous solution that enters saturated at 40°C and leaves at 20°C. Chilled cooling water flows countercurrently, entering at 10°C and exiting at 25°C. The expected overall heat-transfer coefficient is 20 Btu/h-ft2-oF. The average specific heat of the solution is 0.80 cal/g-oC. Estimate:

(a) The tons (2,000 lb) per hour of feed solution.

(b) The heat-transfer area in ft2.

(c) The number of crystallizer units required if each 10-ft-long unit contains 30 ft2 of heat-transfer surface.