Heat exchanger method

The rapid fission of a mass of or another heavy nucleus is the principle of the atomic bomb, the energy liberated being the destructive power. For useful energy the reaction has to be moderated this is done in a reactor where moderators such as water, heavy water, graphite, beryllium, etc., reduce the number of neutrons and slow those present to the most useful energies. The heat produced in a reactor is removed by normal heat-exchange methods. The neutrons in a reactor may be used for the formation of new isotopes, e.g. the transuranic elements, further fissile materials ( °Pu from or of the... 

HBT HCP HDTV HEM heterojunction bipolar transistor hexagonal close packed high definition television heat exchanger method... 

Various tool architectures have addressed the problem in different ways. Fixed platen architectures often control the temperature of the platen through a recirculated heat exchange method (Figure 1.29), and sometimes they also control the temperature of the slurry being transported to the pad surface. 

In order to maintain or restore efficiency it is often necessary to clean heat exchangers. Methods of cleaning may be classified into two groups on-line and off-line cleaning. 

If the heat-transfer surface becomes severely fouled it is necessary to enter a jacketed vessel in order to clean it while coils can be withdrawn and a heat exchanger can be replaced without vessel entry. For all these reasons, an external jacket is seldom the best heat-exchange method in solvent recovery. 

The following heuristics are useful in selecting an initial basis for the heat exchange method and the operating conditions. Details of heat exchanger selection and design are presented in Chapter 13. 

FIGURE 20 Heat-exchange methods for bioreactors (a) jacket, (b) full Internal coll, (c) recirculation of broth through an external heat exchanger, (d) ringlet coil. Cooling water (CW) enters and exits the heat exchange devices, as shown. 

---