Joule’s heating

Besides the reversible production of heat at the junctions, there is an evolution of heat all round the circuit due to frictional resistance, this Joule s heat being proportional to the square of the current, and hence not reversed with the latter. There is also a passage of heat by conduction from the hotter to the colder parts. But if the current strength is reduced, the Joule s heat, being proportional to its square, becomes less and less in comparison with the Peltier heat, and with very small currents is negligible. We shall further assume that the reversible thermoelectric phenomena proceed independently of the heat conduction, so that the whole circuit may be treated as a reversible heat... 

In Rayleigh s treatment of the Boussinesq s problem, we realized that Joule s heat equivalent had to be cancelled, because in this problem the liquid was supposed to be an ideal one. This is - of course - as with many problems arising in the areas of... 

If electrolysis is to proceed at a higher temperature Joule s heat evolved during the flow of the current through the electrolytic cell is utilized for warming up the electrolyte to the temperature required. 

Should this prove insufficient, or in cases where Joule s heat cannot be used for some reasons, special heating devices must be employed. Heating devices installed outside the electrolyzer are suitable for open containers and not too high temperatures. Such heaters are installed before the first cell in an arrangement of cascades with a circulation of the electrolyte. The electrolytic cell can also be provided with a steam heating jacket. 

If an electrolytic cell operates with current 1 at terminal voltage E it accepts a total amount of 0.86 El keal. per hour. A part of this energy equalling 0.86 Eg)t I = 0.86 1.48 I is consumed in the isothermal decomposition of water and the remnant Qu is the heat liberated within the cell in the form of Joule s heat ... 

The amount of heat generated in a given time varies directly as the product of the resistance of the conductor into the square of the current strength. This relation is called Joule s 1 law, named after its discoverer. The heat which is thus derived only from the current quantities, but not from chemical changes, is also called Joule s heat. 

Temperature Adjustment (1) Designing heating and cooling capacity (2) Selection of heat exchanger (3) Measuresagainst Joule s heat by recycle... 

A characteristic feature of all electrophoretic separation procedures is the fact, that when the electric current is passing through a solution. Joule s heat is generated. If R represents the electrolyte resistance in a column of length L and diameter S, through which, within a time period t, passes the electric current /, then for Q it holds that... 

Figure 6. The conductance course of the pH-gradients pH 3-6 and pH 7-10 are very even. The gradient pH 5-8 contains the low conductivity ampholytes around 7 and shows a more uneven conductance course. This gradient is consequently more sensitive for thermal convection caused by Joule s heat in the low conductance region. Generally, the conductance course is more even when shorter pH ranges are used.

As follows from the obtained data, the contribution of ionic conductivity decreases as the temperature increases. It seems that such regularity is common for all similar systems. The effectiveness of the electrochemical decomposition (the expected current efficiency) essentially depends on the current density of electrolysis and approaches the ionic conductivity part only asymptotically. The calculations show that the current efficiency for the decomposition reaction should smoothly increase with the current density increase. However, in many cases the current density values could be too large to observe such behaviour. In particular, the additional Joule s heat at large current densities should result in the temperature increase and, hence, the decrease in ionic conductivity part that would result in a current efficiency decrease. Hence, the dependence of the current efficiency on the... 

Since the input impedance of the following amplifier has to be larger than R, this puts an upper limit on R. Because any fluctuation of i causes a noise signal, the current i through the bolometer has to be extremely constant. This and the fact that the temperature rise due to Joule s heating should be small limits the maximum current through the bolometer. 

When an alternating magnetic field is applied to a ferromagnetic material, it induces an electromotive force, denoted emf, in volts, which generates an eddy current. The Joule s heating, that is, the power released per unit mass of magnetic material, denoted P, due to the eddy current is termed eddy-current losses also known as Foucault-current losses and it is expressed in W/kg. For a low frequency, /, expressed in Hz, the flux penetration into the material is complete and proportional to / and to the reciprocal of the electrical resistivity. 

The choice of the electrolyte is one of the most important tasks in designing a cell for a battery. The electrolyte electronically separates the electrodes from reacting directly in a chemical reaction, it transports electrochemically active species to/from the electrodes, and it is responsible for the Ohmic resistance of the cell that determines Joule s heating and the loss in power and usable electrical energy. In several cell types, the electrolyte takes even its own part in the main electrochemical reactions of the cell. Then, the electrolyte is defined by the specific cell reaction. In other cases, only concentrations of the electrolyte components can be varied within a limited range. Even if the electrolyte does not take part in the main electrochemical reactions, it still has a strong impact on the performance of the cell. Its chemical and electrochemical properties including... 

Mechanical data for as-rolled steels are rarely available and, therefore, experiments must be performed. For this reason tensile tests, realized at the Gleeble 3500 , are analyzed for the temperatures 20 °C, 100 °C, 300 °C, 600 °C, 1100 °C and 1200 °C, cf. Figure 11. Here specimen heating follows from the electrical resistance and Joule s (heat) effect, viz ... 

SAM is a representative method of the surface analysis aimed at below the micron area. The micro structure of the native oxide film might be able to observe by means of SAM method. However, the severe electron beam-induced damage might be arisen on a silicon oxide film by the high electron current density of primary electron beam (3-7). The silicon oxide is reduced to the elemental silicon due to Joule s heat in an ultra high vacuum analyzer chamber of SAM equipment. The conditions to reduce the reduction of the silicon oxide film due to the electron beam-induced damage have been preferred by the investigations on the compulsive reduction of the silicon oxide film. 

In contrast, the imaginary part e" accounts for the amount of dissipated electrical energy in the dielectric either due to (Ohmic) conduction or molecular fiiction related to molecular or charge relaxation processes. Dielectric losses thus lead to Joule s heating and are undesired phenomena for EAP applications. 

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