Research On Modeling Method Of Thermodynamic Calculation For Heat-Supply Network

Distributed heating in cities may pollute the environment indirectly when consuming energy. Moreover, as people’s life quality continues to improve, the demand of heating is also growing. Therefore, in order to increase the energy efficiency and improve the atmospheric environment around city, district heating has been developed rapidly. However, as the scale of district heating increases gradually, more and more complex heating management and operating adjustment, which becomes more difficult accordingly, bring about much more effect on users’heating quality. Hence, thermodynamic verifying calculation and scientific management have great importance for the purpose of guiding the operation and adjustment of heat-supply network.Firstly, three arrangement forms of heat-supply network, i.e., overhead laying, trench laying and directly buried laying, were studied respectively according to the heat transfer characteristics and principle of heat balance in this paper. Then a method for calculating and analyzing the thermal resistances of various layers, the per-heat loss and the temperature drop was obtained. Secondly, based on the method of thermodynamic calculation of heat-supply network, a model was established using the graph theory and with respect to the hydraulic calculation model. Finally, taking a directly buried heat-supply network with hot water the medium for example, both the spatial database and the property database were founded applying GIS software and Microsoft Access database, respectively. Furthermore, a program for thermodynamic verifying calculation of heat-supply network based on GIS was developed employing the object-oriented programming language-Visual Basic, achieving functions such as click enquiries, property data updates and thermodynamic verifying calculations. In addition, every substation’s temperature was obtained through the calculation, and the relative error between calculation and operating data was less than10percent. Thermodynamic verifying calculation is in good agreement with operating data, which can be applied in guiding the operation and adjustment of heat-supply network with hot water.