Use of thermodynamic limits in energy researches

The article considers the possibility of using thermodynamic indicators of ideal (similar to the Carno heat machine) and idealized analogs to study real processes in various sectors of economy. These indicators include ideal and idealized efficiency coefficients, theoretical and minimum required energy/exergy costs of process implementation. The methods of their determination are presented and it is shown how these indicators can be used to estimate the thermodynamic efficiency of the process, theoretical potential and resources of energy saving when improving it and making long-term predictions (more than 20 years) of energy costs. The developed methods are illustrated by the examples of researches of metals and some inorganic and organic substances production. The analysis is given to the tendencies in the change of specific energy consumption for aluminium production by the Hall-Heroult method during the whole period of its use. The given graphs prove that process current energy costs are asymptotically close to the costs of its ideal analog (real efficiency is close to the efficiency of the ideal process). This means that the process should be replaced, i.e. it is necessary to switch to a new aluminum production technology. The calculation procedure of the minimum required and maximum (maximum degree of process idealization) energy (exergy) costs per product is shown by the example of metal and chemicals production by different technologies. The subsequent extrapolation of the efficiency of these processes allows to make a long-term prediction of the volume and structure of their energy consumption in the absence of reliable statistics. Such forecasts provide quite accurate results, since they are based on the fundamental laws of thermodynamics. The involvement of the second principle of thermodynamics using the concept of "exergy" in these studies further increases the level of reliability and significance of the results obtained.

thermodynamic methods, exergy analysis, ideal and idealized efficiency coefficients, metallurgical processes, transition to new technologies, long-term forecasting of energy consumption

1. Stepanov V.S. Analysis of energy efficiency of industrial processes. Heidelberg: Springer-Verlag, 1992. 187 p.

2. Степанов В.С., Степанова Т.Б., Старикова Н.В. Эксергетический анализ систем генерирования, транспорта и потребления энергии. Иркутск: Изд-во Иркутского государственного технического университета, 2016. 276 с.

3. Stepanov V.S., Stepanov S.V. Energy use efficiency of metallurgical processes // Energy Conversion & Management. 1998. Vol. 39. No. 16-18. P. 1803-1809.

4. Степанов В.С., Степанова Т.Б., Старикова Н.В. Химическая энергия и эксергия веществ: методы расчета, область применения, справочные данные. Иркутск: Изд-во Иркутского государственного технического университета, 2017. 217 с.

5. Степанов В.С., Степанов С.В. Термодинамические исследования металлургических процессов: энергетические балансы, эксергетический анализ. Иркутск: Изд-во Иркутского государственного технического университета, 2013. 380 с.

6. Szargut J., Morris D.R., Steward F.R. Exergy analysis of thermal, chemical and metallurgical processes. New York: Hemisphere, 1988.

7. Rant Z. Exergie, ein neues Wort für “technische Arbeitsfähigkeit” // Forsch. Ing. Wes. 1956. Vol. 22, Nо. 1. Р. 36-37.

8. Бродянский В. М. Эксергетический метод термодинамического анализа. М.: Энергия, 1973. 296 с.

9. Groscurth H.M., Kümmel R., Van Gool Thermodynamic limits to energy optimization // Energy. 1989. Vol. 14. No. 5. P. 241-258.

10. Багров О.Н., Клешко Б.М., Михайлов В.В. Энергетика основных производств цветной металлургии. М.: Металлургия, 1979. 376 с.

11. Бялковская В.С. Перспективное планирование направлений технического прогресса. М.: Экономика, 1973. 191 с.

12. Янч Э. Прогнозирование научно-технического прогресса. М.: Прогресс, 1974. 586 с.

13. Belyaev L.S., Marchenko O.V., Filippov S.P., Stepanova T.B. World energy and transmission to sustainable development. Dordrecht/Boston/London: Kluwer Academic Publishers. 2002. 264 p.

14. Баймачев Е.Э. Определение минимальных затрат эксергии на отопление и естественную вентиляцию жилых зданий // Известия вузов. Строительство. 2014. № 7. С. 67-73.