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Pregled učinkovitosti obratovanja sistemov daljinskega ogrevanja temelji na poznavanju energijskih tokov. Za izvedbo analize stanja, ki omogoča določitev pomanjkljivosti energetskega sistema, je treba najprej postaviti fizikalno–matematični model, analiza stanja pa se nato izvede na podlagi meritev temperatur in pretokov. V diplomskem delu je predstavljen način za postavitev modela, ki omogoča analizo toplotnih tokov na sistemu daljinskega ogrevanja. Zaradi kompleksnosti ter obsežne narave takšnih sistemov je bila modelacija izvedena s pomočjo programske opreme Microsoft Excel. Modeliran je bil primarni tokokrog ene veje daljinskega ogrevanja v Mestni občini Ptuj. Postavitev modela zahteva geometrijske lastnosti cevovoda, sam izračun pa temelji na teoriji prenosa toplote in mehanike tekočin. Izdelan program daje vpogled v pretočno–tlačne razmere primarnega tokokroga ter toplotne tokove v stacionarnem stanju sistema. Nestacionarno stanje sistema lahko upodobimo s simulacijo zaporedja kratkotrajnih stacionarnih sosledij. Na podlagi rezultatov metode opisane v tem delu lahko izvedemo analizo za določitev šibkih točk na sistemu daljinskega ogrevanja. V okviru tega diplomskega dela takšne analize toplotnih izgub žal nismo mogli izvesti, saj bi potrebovali več meritev in podatkov, kot smo jih imeli na razpolago. A review of the efficiency of district heating network operation is based on the knowledge of the energy fluxes. To conduct a state analysis which would enable the determination of energy system deficiencies, it is necessary to develop a physical-mathematical model, and state analysis can then be conducted based on the obtained temperature and flow measurements. This part of the diploma thesis describes the method for setting up a model that will enable the analysis of the district heating system’s heat fluxes. Due to the complexity and the vast nature of such systems, modelling was performed using Microsoft Excel. We modelled the primary circuit of one district heating line in the Municipality of Ptuj. Such model development requires knowledge of the geometric characteristics of the pipeline, whereas the calculation is based on the heat transfer theory and fluid mechanics. The developed tool provides an insight into the flow and pressure situation of the primary circuit as well as the heat fluxes when the system is in steady state. The unsteady state of the system can be demonstrated by simulating a series of short steady-state sequences. The results of the method described in this part of the diploma thesis can then be used in an analysis to determine the weak points in the district heating system. In the scope of this diploma thesis, we were unfortunately unable to conduct this analysis due to the insufficient measurements and data available to us. |
