(574g) Entropy Creation, Waste Work and Thermodynamic Efficiency of Galvanic Cells: Effects of Discharge Current and Environment Temperature

In this work, knowledge of efficiency from the perspective of second law for chemical processes (Guha S. Environmental Progress and Sustainable Energy, 39(2), 2020; Guha S., International Journal of Industrial Chemistry, 11(2), 2020, Keenan, J., Thermodynamics, Wiley, 1941) has been applied to find out how environment conditions and discharge current affect critical performance parameters such as Waste Work, Thermodynamic Efficiency and irreversible Entropy Creation of any Galvanic Cell. Calculations have been carried out for Galvanic Cell discharge operation to evaluate magnitude of irreversible Entropy Creation, Waste Work and Thermodynamic Efficiency using second law efficiency as a basis rather than mere energy balance concept.

It is found that irreversible Entropy Creation, Waste Work and Thermodynamic Efficiency are all strongly dependent on environment temperature and discharge current.

Finally, for maximizing electrical energy output, a Galvanic Cell with exothermic discharge reaction should be operated at lower discharge current and at a cell operating temperature which is close to the environment temperature ensuring minimum difference between these two temperature values.

Similarly, a Galvanic Cell with endothermic discharge reaction should also be operated at lower operating current and at cell operating temperature which is close to the environment temperature maintaining minimum difference between these two temperatures for maximizing electrical energy output from the cell.

Lower cell discharge current and minimum difference between the cell and environment temperatures will ensure higher “availability" which in turn will lead higher Thermodynamic Efficiency.

As an example, Table-1 is presented where some cell chemistries are shown which will establish the facts stated.