(Solved): An aqua-ammonia system similar to that in Fig. \( 5.19 \) operates as follows: high-side pressure ...

An aqua-ammonia system similar to that in Fig. \( 5.19 \) operates as follows: high-side pressure \( =200 \) psia; \( t_{3}=190^{\circ} \mathrm{F} ; t_{7}=140^{\circ} \mathrm{F} ; t_{4}=210^{\circ} \mathrm{F} ; m_{7}=100 \) \( \mathrm{lbm} / \mathrm{min} \). Assume equilibrium conditions for states 3,4 , and 7. Find (a) the \( \mathrm{lbm} / \mathrm{min} \) of strong solution leaving the absorber, and (b) the \( \mathrm{lbm} / \mathrm{min} \) of cooling water required for the dephlegmator if the water-temperature rise is \( 15^{\circ} \mathrm{F} \). You may make the same assumptions with regard to the rectifying column as made in part \( (d) \) of Example 5.4. 2 Rework Ex. \( 5.5 \) but omit the heat exchanger between states \( 8,9,11 \), and 12. Compare the results with those of Ex. 5.5. Should the heat exchanger be retained in the system? 9 Rework Ex. \( 5.5 \) with \( t_{3} \) changed to (a) \( 180^{\circ} \mathrm{F} \) and (b) \( 160^{\circ} \mathrm{F} \). All other parameters and assumptions remain as before. Comment on the importance of the heat exchanger used to preheat the liquid that enters the rectifying column. Figure 5.19 Industrial aqua-ammonia absorption system.