Dynamics of the metal jacket wall

In some cases, where the wall of the reactor has an appreciable thermal capacity, the dynamics of the wall can be of importance (Luyben, 1973). The simplest approach is to assume the whole wall material has a uniform temperature and therefore can be treated as a single lumped parameter system or, in effect, as a single, well-stirred tank. 

The heat flow through the jacket wall is represented in Fig. 3.8. 

The nomenclature is as follows Qm is the rate of heat transfer from the reactor to the reactor wall, Qj is the rate of heat transfer from the reactor wall to the jacket, and 

Um is the film heat transfer coefficient between the reactor and the reactor wall, Uj is the film heat transfer coefficient between the reactor wall and the jacket. Am is the area for heat transfer between the reactor and the wall and Aj is the area for heat transfer between the wall and the jacket. 

In some cases, it may be of interest to model the temperature distribution through the wall. 

---

Pre-plasticising is the term given to the conversion of uncured rubber to a hot, soft (relative), and homogeneous, plastic mass. This is achieved by the rotation of a metal screw within a heater-jacketed barrel. The relationship between the temperature of the pre-plasticised rubber and that of the jacketed barrel is dynamic, as the hot rubber exchanges frictional heat to the barrel walls or, depending on the heater setting, gains more heat. Rubber strip is fed to the throat, or inlet to the screw where it is sheared... 

---