Methodology for assessing the consequences of switching to a closed-circuit hot-water supply in district heating systems

As of 1 January 2022, the transition to a closed-circuit hot-water supply in district heating systems will begin in Russia. This work proposes a methodology for assessing the consequences of this transition. The procedure is as follows: determining specific operational consumption of district water for hot water supply with manual direct water intake when the outside temperature changes; developing the required mode of closed hot-water supply; analysis of the practically possible mode of manual consumption in the heat supply system; determining the operational specific consumption of hot-water supply in manual hot water systems with direct water intake, including the characteristics of the heat supply source; calculating the flow rate of direct water for water circulation in manual hot water supply systems; analysing the hydraulic regime before and after the transition to a closed circuit; offering recommendations. The method for assessing the consequences associated with the transition to a closedcircuit hot-water supply in district heating systems showed that the amount of make-up water consumption from a heat source is affected by a change in the actual consumption of hot-water supply and the temperature of cold and hot water. Based on the research results, it can be concluded that there is no technical possibility of an overall transition to a closed circuit. To prepare technical reports and performance charts, it is recommended to use the actual values of heat consumption for the hydraulic calculations; to use the metered values and consider a significant number of manual hot-water supply systems in calculating the hot-water supply consumption standard; to include the loss of heat energy on heating towel rails, domestic losses of building services systems under a four-pipe heat supply system in the distribution pricing.

1. Lipovka YuL, Venin AS, Mikhailova AS. Hydraulic mode of the heat network when transiting with open to closed heat supply system. Energosberezhenie i vodopodgotovka. 2019;6(122):53-56. (In Russ.).

2. Guelpa E. Impact of thermal masses on the peak load in district heating systems. Energy. 2021;214:118849. https://doi.org/10.1016/j.energy.2020.118849.

3. Stepanov KI, Mukhin DG. Analysis of the efficiency of an absorption lithium bromide thermotransformer with two-stage absorption in the composition of gasified power plants. Teploenergetika. 2021;1:43-51. (In Russ.).

4. Lezhanin MV. Implementation of solar heaters in hot water supply system of buildings in Sakha republic (Yakutia). Energetik. 2019;8:22-25. (In Russ.).

5. Chicherin S, Zhuikov A, Junussova L, Yelemanova A. Multiple-fuel District Heating System of a Transportation Facility: Water Performancebased View. Transportation Research Procedia. 2021;54:31-38. https://doi.org/10.1016/j.trpro.2021.02.044.

6. Ivanko D, Sørensen AL, Nord N. Splitting measurements of the total heat demand in a hotel into domestic hot water and space heating heat use. Energy. 2021;219:119685. https://doi.org/10.1016/j.energy.2020.119685.

7. Fitó J, Hodencq S, Ramousse J, Wurtz F, Stutz B, Debray F, et al. Energyand exergy-based optimal designs of a low-temperature industrial waste heat recovery system in district heating. Energy Conversion and Management. 2020;211:112753. https://doi.org/10.1016/j.enconman.2020.112753.

8. Kristensen MH, Hedegaard RE, Petersen S. Long-term forecasting of hourly district heating loads in urban areas using hierarchical archetype modeling. Energy. 2020;201:117687. https://doi.org/10.1016/j.energy.2020.117687.

9. Alkhasov AB, Alkhasova DA. Comprehensive utilization of low-potential geothermal waters of southern Russia for heat and water supply and solution of environmental problems. Teploenergetika. 2019;5:82-88. (In Russ.). https://doi.org/10.1134/S0040363619050011.

10. Braas H, Jordan U, Best I, Orozaliev J, Vajen K. District heating load profiles for domestic hot water preparation with realistic simultaneity using DHWcalc and TRNSYS. Energy. 2020;201:117552. https://doi.org/10.1016/j.energy.2020.117552.

11. Chicherin S, Mašatin V, Siirde A, Volkova A. Method for Assessing Heat Loss in A District Heating Network with A Focus on the State of Insulation and Actual Demand for Useful Energy. Energies. 2020;13(17):4505. https://doi.org/10.3390/en13174505.

12. Zhuikov AV, Kolosov MV, Radzyuk AYu, Chicherin SV. Research of energy efficiency of temperature control systems in buildings. AIP Conference Proceedings. 2021;2337(1):030014. https://doi.org/10.1063/5.0046540.

13. Samarin OD. Analysis of reliable and safe heat supply of residential buildings using waste water after DHW heat exchangers. Nadezhnost' i bezopasnost' energetiki = Safety and Reliability of Power Industry. 2020;13(1):41-47. https://doi.org/10.24223/1999-5555-2020-13-141-47. (In Russ.).

14. Livchak VI. On the rationing of utility services for hot water supply in apartment buildings. Santekhnika. 2019;1(1):32-39. (In Russ.).

15. Livchak VI. Proposal for changing the standard of communal services in thermal energy for hot water supply of apartment buildings and hotels. Santekhnika. 2019;2:52-55. (In Russ.).

16. Vankov YuV, Zapolskaya IN, Izmailova EV, Zagretdinov AR, Plotnikova LV. Energy consumption reduction during transition to hot water supply from individual thermal points. Vestnik Kazanskogo gosudarstvennogo energeticheskogo universiteta. 2019;11(1):19-27. (In Russ.).

17. Vankov YuV, Zapolskaya IN, Gaponenko SO, Mukhametova LR. Improving the reliability of heat energy transportation to consumers in the context of the hot water supply system modernization. Vestnik Kazanskogo gosudarstvennogo energeticheskogo universiteta. 2020;12(4):29-37. (In Russ.).

18. Wirtz M, Kivilip L, Remmen P, Müller D. 5th Generation District Heating: A novel design approach based on mathematical optimization. Applied Energy. 2020;260:114158. https://doi.org/10.1016/j.apenergy.2019.114158.

19. Volkova A, Krupenski I, Ledvanov A, Hlebnikov A, Lepiksaar K, Latõšov E, et al. Energy cascade connection of a low-temperature district heating network to the return line of a high-temperature district heating network. Energy. 2020;198:117304. https://doi.org/10.1016/j.energy.2020.117304.

20. Farouq S, Byttner S, Bouguelia MR, Nord N, Gadd H. Large-scale monitoring of operationally diverse district heating substations: A referencegroup based approach. Engineering Applications of Artificial Intelligence. 2020;90:103492. https://doi.org/10.1016/j.engappai.2020.103492.