Ohmic heat

Inside the porous regions the temperature is assumed to be the same in gas and solid regions (local equilibrium). The source term includes ohmic heating, which is distributed throughout the current conducting regions and heat produced due to the... 

Ohmic heating of catalyst is often used as a simple method of igniting the chemical reaction during reactor startup, for instance, in the oxidation of ammonia on platinum-rhodium gauze catalysts. Another application is the prevention of cold-start emissions from automotive catalysts responsible for much of the residual pollution still produced from this source (21). The startup times needed for the catalyst to attain its operating temperature can be cut by a factor of 5 or more by installing an electrically heated catalyst element with a metallic support upstream of the main catalyst unit. Direct electrical catalyst heating permits facile temperature control but requires a well-defined catalyst structure to function effectively. 

As already mentioned, the induced current Ipl heats the plasma due to joule losses which are proportional to the plasma resistance. With increasing temperature the plasma resistance decreases and the ohmic heating becomes less effective. Theoretical analysis shows that the maximum temperature which can be reached in this way is below 2 keV, i.e. the plasma cannot enter the ignition region of 5 keV4. Therefore,... 

The most familiar thermoelectric effect is the generation of Ohmic heat due to current flow, discussed in Section 12.3.2. Less well known is the Thomson heat, produced or absorbed when a current flows in a temperature gradient. The Thomson coefficient, a, can be defined as... 

The efficiency of the plant is increased by 1.5%. The increase is a consequence of better matching of heat source temperature to HTE plant heat requirements. It is also a consequence of running the cell at a current density greater than thermal neutral so that significant ohmic heating is generated compared to thermal neutral operation. 

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