Malick Kane, Yolaine Adihou
Proceedings of ECOS 2020 - The 33rd International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, 29 June - 3 July 2020, Osaka, Japan
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Low temperature district heating networks can provide a highly efficient low carbon heat supplier with great potential in improving heat distribution while minimizing exergy losses. However the interest in performing exergy analysis is hardly comprehensive for industry as it rarely gives explicit details on district heating systems design and operation. Moreover, most of exergy assessments are based on the assumption of neglecting pressure losses whereas low temperature district heating networks usually operate at low differential temperature corresponding to high flow rates and then significant pressure losses. Consequently, the latter are no longer negligible when compared to thermal losses. An exergy formulation as function of thermal and pressure losses is therefore essential to assess low temperature DH networks. This paper presents an exergy-based methodology to design low temperature networks for an optimal thermo-hydraulic flow distribution. It addresses an explicit analytic expression of exergy losses as a function of geometric and thermo-hydraulic parameters. A detailed exergy model is performed to identify influencing parameters and conclude on a simplified formulation of exergy losses. The method is tested on the conception of the evolving thermal network for the BlueFactory site in Fribourg (Switzerland) composed of 11 buildings with a total surface area of 74500 m2 .