Water predicted jacket

A verag evafae of% n2 °Jj e actUal Qnd predicted jacket water outlet temperatures. 

With no heat being transferred through the jacket, an accurate prediction of the jacket water outlet temperature should be possible by knowing the history of the jacket inlet temperature and the mixing characteristics of the jacket. Therefore, the difference between the actual and predicted outlet temperatures multiplied by the flow rate and specific heat of the water should also equal Q. 

One feasible network would correspond to the cold streams Cl, C8, and C9 diverted to suitable jacketed reactor compartments, as the simple network in Fig. 14 shows. The hot streams not shown in this network are matched directly with cooling water (CW), and the amount of steam used here is very small. Note that this network would require the same minimum utility consumption predicted by the solution of (PIO). It can be inferred that the network in Fig. 14 is equally suitable for both the simultaneous and sequential solutions. In fact, Balakrishna and Biegler (1993) showed that, for exothermic systems in which the reactor temperature is the highest process temperature, the pinch point is known a priori as the highest reactor temperature (in this case, the feed temperature) and the inequality constraints in (PIO), Qh 2h () ). F G P. can be replaced by a simple energy balance constraint. This greatly reduces the computational effort to solve (PIO). 

The double pipe, cocurrent heat exchanger is used to cool a distillate product using cold water circulating through the jacket as illustrated in Fig. 2.3. The overall heat transfer coefficient is taken to be U and the mass flow of distillate and water is and Wq, respectively. Under turbulent flow conditions, the fluid temperatures are taken to be uniform across individual flow cross sections. Find the relationship to predict how steady-state temperature changes with axial position, and from this, deduce an expression to compute the average AT... 

EXAMPLE 4.8-1. Rate of Heat Transfer in a Jacketed Kettle Water is being boiled at 1 atm abs pressure in a jacketed kettle with steam condensing in the jacket at 115.6°C. The inside diameter of the kettle is 0.656 m and the height is 0.984 m. The bottom is slightly curved but it will be assumed to be flat. Both the bottom and the sides up to a height of 0.656 m are jacketed. The kettle surface for heat transfer is 3.2-mm stainless steel with a /c of 16.27 W/m-K. The condensing steam coefficient fi, inside the jacket has been estimated as 10200 W/m"-K. Predict the boiling heat-transfer coefficient /iq for the bottom surface of the kettle. 

---