Heat internal

Externally heated/cooled to internally heated/cooled... 

Thor, Scandinavian god of war) Discovered by Berzelius in 1828. Much of the internal heat the earth produces has been attributed to thorium and uranium. Because of its atomic weight, valence, etc., it is now considered to be the second member of the actinide series of elements. 

Much of the internal heat of the earth is thought to be attributable to the presence of uranium and thorium. 

Ferrites aHowing for operation at frequencies well above 1 MH2 have also become available, eg, 3F4 and 4F1 (Table 6). Other newer industrial power ferrites are the Siemens-Matsushita N-series (28,97) the TDK PC-series (28,100), and the Thomson B-series (28,103). While moving to higher frequencies, the ferrites have been optimized for different loss contributions, eg, hysteresis losses, eddy current losses, and resonance losses. Loss levels are specified at 100°C because ambient temperature in power appHcations is about 60°C plus an increase caused by internal heat dissipation of about 40°C. 

Fig. 2. Multipurpose fluidized bed where 1 represents the sheU 2, soHd particles 3, the blower 4, the gas distributor 5, the heat exchanger for fluidizing gas 6, internal heating or cooling 7, external heating or cooling 8, cyclones 9, the soHds feeder 10, soHds offtake 11, Hquid feed 12, the freeboard 13, the...

Fig. 5. Internal heating-element convection furnace cross section.

P. Vin2 and C. A. Busse, "Axial Heat Transfer Limits of Cylindrical Sodium Heat Pipes Between 25 W/cm and 15.5 kW/cm, " International Heat Pipe Conference, Stuttgart, Germany, 1973. 

Low Temperature Carbonization. The Lurgi Sptlgas process was developed to carbonize brown coal at relatively low temperatures to produce tars and oils (Fig. 5). A shaft furnace internally heated by process-derived fuel gas (Spblgas) is used. The product can range from a friable coke breeze to hard lump coal depending on the quality of the briquettes used in the feed. The briquettes, made in normal extmsion presses, break down into smaller sizes during carbonization. 

Reactions are either endothermic and require heating to complete the reaction, or exothermic and raise the temperature, thus requiring some type of cooling such as quenching or an internal heat exchanger to remove reaction heat. The reactors are provided with various types of internals to support the catalyst and distribute the reaction components uniformly across the catalyst area collection internals remove the products and other distribution. 

L. W. Florschuetz and A. R. Khan, Fourth International Heat Transfer Conference, Paris, Prance, 1970. 

The passing of the Clean Air Act in the United Kingdom in 1956 resulted in a revival of interest in low temperature carbonization to produce a very reactive coke suitable for open fires. In the CoaUte process, the coal is heated at 600—650°C for 4 h in small retorts each hoi ding 6—7 metric tons (5). The Rexco process employed large internally heated retorts in which charges of 34 metric tons were heated to 700—750°C for 6 h, but is no longer in operation in the United Kingdom (6). 

The generated water vapor rises through a screen (demister) placed to remove entrained saline water droplets. Rising further, it then condenses on the condenser tube bank, and internal heat recovery is achieved by transferring its heat of condensation to the seawater feed that is thus being preheated. This internal heat recovery is another of the primary advantages of the MSF process. The energy performance of distillation plants is often evaluated by the performance ratio, PR, typically defined as... 

At first, batchwise horizontal retorts were used for smelting, and later continuous vertical retorts, both externally fired. Continuous, internally heated furnaces such as the electrothermic furnace followed, and the last important development was the Imperal Smelting blast furnace. 

Geochemical Stage. The conversion of peat to bituminous coal is the result of the cumulative effects of temperature and pressure over a long time. The sediment covering the peat provides the pressure and insulation so that the earth s internal heat can be appUed to the conversion. The temperature increase is about 4 to 8°C for each 100 m of depth. The changes in plant matter are termed normal coalification. 

Temperature of Fresh Solvent The temperature of the entering solvent has surprisingly httle influence upon the degree of absorption or upon the internal-temperature profiles in an absorber when the heat effects are due primarily to heat of sohition or to solvent vaporization. In these cases the temperature profile in the hquid phase apparently is dictated solely by the internal-heat effects. 

Reaction/Ignition or thermal decomposition due to high temperature at unwetted internal heating element surface. Possibility of runaway reaction, vapor phase deflagration or thermal decomposition. 

---