Method for optimal design of pipes for low-energy district heating, with focus on heat losses

Alessandro Dalla Rosa, Hongwei Li, Svend Svendsen

Research output: Contribution to journalJournal articleResearch

Abstract

The synergy between highly energy-efficient buildings and low-energy district heating (DH) systems is a promising concept for the optimal integration of energy-saving policies and energy supply systems based on renewable energy (RE). Network transmission and distribution heat loss is one of the key factors in the optimal design of low-energy DH systems. Various pipe configurations are considered in this paper: flexible pre-insulated twin pipes with symmetrical or asymmetrical insulation, double pipes, and triple pipes. These technologies represent potential energy-efficient and cost-effective solutions for DH networks in low-heat density areas. We start with a review of theories and methods for steady-state heat loss calculation. Next, the article shows how detailed calculations with 2D-modeling of pipes can be carried out by means of computer software based on the finite-element method (FEM). The model was validated by comparison with experimental measurements, analytical formulas, and data from the literature. We took into account the influence of the temperature-dependent conductivity coefficient of polyurethane insulation foam, which enabled us to achieve a high degree of accuracy. We also showed the influence of the soil temperature throughout the year. Finally, the article describes proposals for the optimal design of pipes for low-energy applications and presents methods for decreasing heat losses.
Original languageEnglish
JournalEnergy
Volume36
Issue number5
Pages (from-to)2407-2418
ISSN0360-5442
DOIs
Publication statusPublished - 2011

Keywords

  • Heat loss
  • District heating
  • Thermal conductivity
  • Finite-element method
  • Steady-state simulation
  • Low energy

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