Exergy Analysis of Transiant Modes in Hot Water Storages


  • Volodymyr Voloshchuk Department of automation of thermal processes, National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute” http://orcid.org/0000-0003-0687-8968
  • Olena Nekrashevych Department of automation of thermal processes, National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute” http://orcid.org/0000-0003-2263-3549
  • Serhii Liubytskyi Department of automation of thermal processes, National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute” http://orcid.org/0000-0002-4419-6012




The paper demonstrates the importance of taking into account the accumulation of exergy in a control volume of a thermal storage during transient modes for evaluation of exergy-based parameters. The investigations are based on the exergy balance equation and mathematical model of the mode of simultaneous thermal energy addition and removal. It is found that for the specified parameters of the unit, when the exergy accumulation is not included, the error of estimation of exergy-base parameters can be large: in case of calculation of fuel of exergy and exergy efficiency this error can reach 80 %, the exergy destruction values are received with 130 % error. It is shown that these errors depend on the ratio of rates of cold and hot working fluids and decrease with increasing this ratio, but almost do not depend on the storage volumes and the initial temperatures of working fluids. Including accumulation of exergy within the control volumes during dynamic modes of thermal systems is necessary for implementation of exergy-based control strategies.


Sarbu I., Sebarchievici C. (2018), “A Comprehensive Review of Thermal Energy Storage”, Sustainability, vol. 191, no. 10(1), Jan, pp. 1–32, doi: 10.3390/su10010191.

(2011), Low Exergy Systems for High-Performance Buildings and Communities. Exergy Assessment Guidebook for the Built Environment. IEA ECBCS Annex 49 Final Report, Fraunhofer Institute for Building Physics IBP. Avaliable: https://www.ibp.fraunhofer.de/content/dam/ibp/ibp-neu/de/dokumente/publikationen/eer/summary-report-annex49.pdf. [Accessed 28 September 2020].

Sayadi S., Tsatsaronis G., Morosuk T. (2019), “Dynamic exergetic assessment of heating and cooling systems in a complex building”, Energy Conversion and Manage, vol. 183, Mar, pp. 561–576, doi: 10.1016/j.enconman.2018.12.090.

Picallo-Perez A., Sala J. M., Tsatsaronis G., Sayadi S. (2019), “Advanced Exergy Analysis in the Dynamic Framework for Assessing Building Thermal Systems”, Entropy, vol. 22, no. 1, Dec., p. 32.

Sayadi S., Tsatsaronis G., Morosuk T. (2020), “Splitting the dynamic exergy destruction within a building energy system into endogenous and exogenous parts using measured data from the building automation system”, Int. J. Energy Res., vol. 44, no. 6, Feb., pp. 4395–4410, doi: 10.1002/er.5213.

Sayadi S., Tsatsaronis G., Morosuk T., Baranski M., Sangi R., Müller D. (2019), “Exergy-based control strategies for the efficient operation of building energy systems”, J. of Cleaner Prod., vol. 241, no 118277, Dec., Art., doi: 10.1016/j.jclepro.2019.118277.

Sangi R., Müller D. (2019), “Application of the second law of thermodynamics to control: A review”, Energy, vol. 174, no. 1, May, pp. 938–953.

Razmara M., Maasoumy M., Shahbakhti M., Robinett R. D. III (2015), “Optimal exergy control of building HVAC system”, Appl. Energy, vol. 156, Oct., pp. 555–565, doi: 10.1016/j.apenergy.2015.07.051.

Jain N., Alleyne A. (2015), “Exergy-based optimal control of a vapor compression system”, Energy Conversion and Manage, vol. 92, Mar., pp. 353–365, doi: 10.1016/j.enconman.2014.12.014.

Raccanello J., Rech S., Lazzaretto A. (2019), “Simplified dynamic modeling of single-tank thermal energy storage systems”, Energy, vol. 182, pp. 1154–1172, doi: 10.1016/j.energy.2019.06.088.






Енергетичні та теплотехнічні процеси й устаткування