Abstract
The main task of energy-efficient heat supply is to ensure full compliance between the produced and consumed thermal power, subject to a minimum of reduced costs. To achieve this goal, various methods of central and local regulation are applied. Analysis of the thermal schemes of some cities in Russia showed that most of the heat sources of centralized heat supply systems are not able to support the design hightemperature graphs with central regulation. Therefore, the area of centralized qualitative method of regulation of heat load has decreased substantially. A perspective direction for the further development of heat supply systems is to appeal to the experience of foreign countries, i.e. the use of qualitative-quantitative and quantitative methods of central regulation and low-temperature heat supply. There is also an acute problem of the complete use of heat by consumers, since overstating of the temperature of the return water substantially reduces the efficiency of heat sources. A new formula has been obtained which makes it possible to predict the temperature of the return network water in variable operating modes of heating points. The resulting formula can be used to set up programmable regulators and will allow correcting irrational modes of operation of heat supply systems.
Highlights
One of the main problems of heat supply systems is the problem of efficient use of thermal power
The main ways of central regulation are: - qualitative regulation when the water temperature in the supply tp1 and return tp2 mains of the heating system change depending on the outdoor temperature tout with a constant flow of network water Gp; - quantitative regulation when the temperature of the water in the supply pipeline of the heating network tp1 is constant during the entire heating period and the flow rate of the supply water Gp varies depending on the outdoor temperature; - qualitative and quantitative regulation when the temperature and flow rate of the supply water are changing depending on the outside temperature
In modern conditions, heat sources are not able to maintain high-temperature central control graph, which led to the appearance of temperature graphs with an upper cut and a gradual abandonment of the high-quality control method
Summary
One of the main problems of heat supply systems is the problem of efficient use of thermal power. Heat power is determined by the flow rate and temperature difference of the coolant. Where Q is the thermal power, W; G is the coolant flow rate, m3/s; с and are specific heat capacity, J/(kg С) and density, kg/m3 of heat carrier; tp and tp are initial and final temperature of the coolant, С; W is the equivalent of the coolant flow rate, W/K. In order to increase the efficiency of using heat energy at the heat source, temperature control graphs are applied. The main ways of central regulation are: - qualitative regulation when the water temperature in the supply tp and return tp mains of the heating system change depending on the outdoor temperature tout with a constant flow of network water Gp; - quantitative regulation when the temperature of the water in the supply pipeline of the heating network tp is constant during the entire heating period and the flow rate of the supply water Gp varies depending on the outdoor temperature; - qualitative and quantitative regulation when the temperature and flow rate of the supply water are changing depending on the outside temperature
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