Analysis of the operation of heat exchangers of the heating system during the heating season in the scheme of reliable and safe heat supply for civil buildings

The study examines the internal heat supply scheme for residential and public buildings, featuring an independent connection of the heating system to external heating networks through a surface heat exchanger. This configuration ensures the reliability of heat supply, stability of the hydraulic regime, and the necessary comfort within the premises. A mathematical model has been developed to describe the variable operating modes of the heaters of the heating system during the heating period, taking into account changes in the heat transfer coefficient of the device and the average temperature difference of the heat carriers. Calculations using this model revealed that the heat transfer coefficient of the heater decreases monotonically with an increase in outdoor air temperature. This decrease is attributed to changes in the physical properties of water when regulating its temperature according to the heating schedule, reaching approximately 20% at the beginning and end of the heating period. Additionally, it was shown that when using a typical heating schedule, the average logarithmic temperature difference of the heat carriers in the heater decreases significantly more slowly than the thermal load on the heating system and the heat transfer coefficient. As a result, the actual heat transfer in the heat exchanger at the boundaries of the heating season is also about 20% higher than required. This finding suggests that such devices should be calculated for the conditions at the breaking point of the temperature graph, similar to heaters in hot water supply systems, or that the introduction of a 20% margin to the calculated heating surface should be reconsidered 

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