Study On Thermal Efficiency Analysis And Diagnostic Methods Of Hot Water Central Heating System

Hot water central heating system is the main form of urban heating, mainly consists of three parts which are the heat source, the heating network and heat users, and includes four processes which are heat preparation, transformation, transportation and use. The varying degrees of heat loss of the various parts lead to the different energy consumption of the central heating system. With the promotion of the existing building energy saving and the energy efficiency standards of the envelope structures, building energy consumption will gradually reduce, and accordingly the proportion of the energy consumption of the heat source and heat network will increase. Therefore, in order to reduce heat loss of the system, this article is for the efficiency of the heat source and heat network of the hot water central heating system, and is divided into the following aspects:(1)Analyze the heating principle of the three typical heat source, identify the commonly used form of heat source in coal-fired and gas and the thermal efficiency indicators of the heat source to make them more suitable for the calculation of the operation efficiency of the heat source. Analyze the main impacting factors of the thermal efficiency and the heat loss of the various parts of the heat source. Calculate and analyze the influence degree of each factor with instances to provide an energy-saving direction for the operation and management of the heat source.(2)Contrast the heat loss of the heating pipe segment in three different way of laying methods, select the most accurate formula of each laying method, and determine the minimum heat loss in the same way of laying method. According to the most accurate results of the different laying methods’ calculation, get the heat loss’s linear equation with supply water and return water temperature, verify the accuracy of the fitting formula, and simplify the theoretical calculations of the heat loss’s calculation. (3)Analyze the proportion of the heat loss of actual thermal running network, focus on the analysis of the pipe insulation heat loss and heat loss exception segment diagnosis. Compare the method of unit temperature drop and the method of allowing the heat loss of pipe segments, determine the heat loss calculation model to calculate each node temperature, and use the method of allowing the heat loss to verify its correctness on the basis of the known pipe flow. The results of the study can be used as the theoretical basis of the pipe network design and transformation.(4) According to the method of allowing the heat loss and the different degree of insulation destruction, calculate the unit temperature drop of the pipe segment respectively. Analyze the curve of the temperature drop in abnormal heat loss, select the bassd temperature drop for the diagnosis of the abnormal heat loss tube segment. Assume one or multiple abnormal pipe sections are located in the main pipe or in the branch pipe segment, obtain the variation of temperature in each case. Analyze the variation of temperature with instances, Diagnose the pipe section of the abnormal heat loss, according to the node temperature change of design conditions and actual operating conditions.