The Exergetic, Environmental and Economic Effect of the Hydrostatic Design Static Pressure Level on the Pipe Dimensions of Low-Energy District Heating Networks

Abstract

Low-Energy District Heating (DH) systems, providing great energy savings by means of very low operating temperatures of 55 °C and 25 °C for supply and return respectively, were considered to be the 4th generation of the DH systems for a low-energy future. Low-temperature operation is considered to be used in a low-energy DH network to carry the heat produced by renewable and/or low grade energy sources to low-energy Danish buildings. In this study, a comparison of various design considerations with different levels of maximum design static pressures was performed, and their results evaluated in terms of energetic, exergetic, economic, and environmental perspectives

Effects of boosting the supply temperature on pipe dimensions of low-energy district heating networks: A case study in Gladsaxe, Denmark

“…Hence pressure drop calculations were carried out only for the peak winter period of the CS, in which mass flow rates are certain to be observed with high values due to higher heat load in comparison to the FS, being used as the limit defined in the constraint of the optimization method applied. The study [43] presented the comparison of heat loss effect and the effect of pump electricty consumption in low-energy DH systems. The exergetic value of heat loss is substantially more than the exergy consumption by the increased pumping power (exergy analysis is out of the scope of this paper however the exergy is the only way to compare two different energy forms).…”

Sustainable Heating and Cooling Management of Urban Quarters

“…The 4th generation (4GDH) works with flow temperatures between 50-70 • C, which makes it possible to feed in high-temperature regenerative energy sources (solar thermal energy) [24]. In some cases, the 4th generation also works with flow temperatures of maximum 55 • C [25], but in this case, the hot water is heated decentral. The 4th generation also enables the bi-directional low-temperature grid, where heat can either be taken from the grid or added to the grid as needed [26].…”