Influence of Different Operating Conditions of a District Heating and Cooling System on Heat Transportation Losses of a District Heating Network
Ryszard Zwierzchowski, Olgierd Niemyjski
This paper deals with different operating conditions of a District Heating and Cooling (DHC) System and its influence on heat transportation losses of a District Heating Network (DHN). The different operating conditions of the DHC System’s mean different flow rate and temperature of the network water flowing in the DHN. These different operating conditions of the DHC System result in the DHNs having variable transportation losses. The analyzed DHC System consists of the Heat Only Boilers (HOB) plant and the DHN with substations and chambers. The DHNs in Poland are usually installed as underground, traditionally insulated piping placed in concrete ducts (large diameter and main pipelines) or pre-insulated piping placed directly in the ground. The result of the analysis was used to verify calculation methods of fluid flow and heat transportation losses of the DHN, when cold for consumers is generated using either absorption or adsorption chillers. The total heat transportation losses of the DHN differ according to individual systems and depend on the size of the DHC System, its heating loads and quality of insulation of the piping. This paper presents the results of the numerical calculation of the temperature distribution in the soil around the piping channel using an FDA model. The results of the numerical simulation of water and heat flow through the DHN allow to determine the total heat transportation losses of the DHN for different operating conditions of the DHC System.