Thermogalvanic cell

The e.m.f. of a thermogalvanic cell is the result of four main effects (a) electrode temperature, (b) thermal liquid junction potential, (c) metallic thermocouple and (d) thermal diffusion gradient or Soret. 

Section 5.9.2. Thermogalvanic cells where electrical work is gained from heat transfer will not be considered in this book and the reader is advised to inspect Agar s monograph quoted on page 169. 

Refs. [i] Agar JN (1963) Thermogalvanic cells. In Delahay P (ed) Advances in electrochemistry and electrochemical engineering vot 3. Interscience, New York, pp 31-121 [ii] Newman, Thomas-Alyea KE (2004) Electrochemical systems, 3rd edn. Wiley Interscience, Hoboken, pp 317... 

Thermocell (thermogalvanic cell) — is a cell that comprises a reference -> half-cell maintained at constant temperature, and another half-cell under study whose temperature is varied in a controlled manner [i, ii]. The variation of the temperature for the half-cell under study allows determining the -> temperature coefficient. However, temperature differences between both half-cells may induce other undesired additional effects to the electrochemical reaction. The following figure shows a schematic diagram of a commonly used thermocell. 

Affect the electrochemical behaviour of the metal/liquid system. A galvanic cell may be established between areas on the same heat exchanger that are at different temperatures. The hotter regions may be anodic or cathodic to cooler areas. Problems may arise when the thermogalvanic cell gives rise to activity in one area and passivity in another, that may already exist or is in the process of being developed. 

Except for the use of classical thermodynamics in the treatment of galvanic cells at zero current (including thermogalvanic cells, for which some aspects of the thermodynamics of irreversible processes have to be brought in—a, topic not treated here— see Agar s recent review where a complete bibliography will be found) and for the introduction of thermodynamic quantities pertaining to the formation of activated complexes from reactants in electrode processes, little systematic use of thermodynamics has been made in the various areas of electrochemistry concerned with nonzero currents. 

Agar, Thermogalvanic Cells in Advances in Electrochemistry and Electrochemical Engineering, Ed. Delahay and Tobias, Vol. 3, pp. 31-121, Interscienoe Publishers Inc. and J. Wiley Sons, New York, 1963. 

Thermogalvanic cells featuring solid electrolytes have received little attention from scientists although they have many interesting features as compared with those using liquid electrolytes. ... 

With a thermogalvanic cell featuring 3 A 2 3 liquid sodium, between 0.3 and 0.4 volt open-circuit tension has been measured for overall temperature gradient of about 250°C (50). 

Agar JN (1963) Thermogalvanic cells. In Delahay P (ed) Advances in electrochemistry and electrochemical engineering. Interscience Publishers, London, pp 31-121... 

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