Reliable and safe heat supply of residential buildings using wastewater after heaters for hot water supply

Abstract

A modified scheme of heat supply of residential buildings with dependent connection to external heating networks is considered, providing reliability of heat supply and the necessary comfort in the premises due to mixing in some of wastewater after hot water supply (DHW) heaters at an outdoor temperature exceeding the break point of the temperature graph. The main equations describing the dependence of the water temperature in the supply line on the outside air temperature are analyzed, and a review of possible ways of regulating the heat supply and preventing "overflows" near the beginning and the end of the heating period is carried out, taking into account the requirements of the current regulatory documents of the Russian Federation. Calculations are made to determine the required proportion in the mixture for water consumption after the heaters of hot water supply in the conditions of the application of the scheme of connection of buildings to the heating network. The analysis of obtained results is given, and conclusions are drawn concerning expediency of application of the considered scheme. It is established that, from the power point of view, mixing of wastewater after heaters of DHW in the calculated quantity will allow to provide reliability of heat supply of the main group of residential buildings and safety of activity of people at high temperatures of outside air. It is shown that, at the same time, that the higher the current outdoor temperature, the greater the share of wastewater in the mixture, with the above dependence close to linear, and its numerical coefficients associated only with the calculated outdoor temperature in the construction area for the cold season. It is noted that the introduction of the proposed scheme is possible with a minimum reconstruction of existing units and structures without significant capital costs, and also gives a system-wide effect in the form of increased electricity generation in thermal power plants on thermal consumption.