Assume that the water of problem 6.20 is treated by an ion exchange process (hardness after ion exchange is zero). the desired level of hardness is 80 mg/l as caco3. the community uses 200,000 gallons of water each day. a. calculate the flow through the ion exchange units and the bypass flow required to meet the desired hardness level. b. list all of the ions in the water and indicate if their concentration will increase, decrease, or not change after ion exchange treatment c. how would using the lime-soda precipitation process for softening affect ion concentrations?

Asteel tube (k=50 w/mk) of inner and outer diameter di = 20mm and do=26mm, respectively, is used to transfer heat from hot gases flowing over the tube (h-hot = 200w/m2k) to cold water flowing through the tube (h-cold = 8000 w/m2k). what is the cold-side overall heat transfer coefficient uc? to enhance heat transfer 16 straight fins of rectangular profile are installed longitudinally along the outer surface of the tube. the fins are equally spaced around the circumference of the tube, each having a thickness of 2mm and a length of 15mm. what is the corresponding overall heat transfer coefficient uc? *solve for uc in both cases*