This deliverable investigates the possibility of implementing a heat recovery system in the distribution pipes of a district heating network. The aim with the multimedia pipes is to minimise the heat losses from the distribution pipes.

Choice of pipes

The LTDH distribution system consists in a combination of pipes with different temperatures as well as different media, which must fulfil different functions. The aim with the multimedia pipes is to minimise the heat losses from the distribution pipes and reach a zero energy loss or even negative heat loss. To achieve that, the multimedia pipes will include one or more collector pipes, which collect the heat loss from the media pipes and eventually absorb extra heat from the surrounding ground. Afterwards, the heat is returned to the media pipes using a heat pump.

The investigation evaluated the relation between the geometry of the heat recovery system and the recovery potential, highlighting which geometry can optimize the heat intake from the DH pipe and the surrounding soil. Furthermore, the temperature in the recovery pipes was investigated to understand its influence on the recovery potential. However, the final choice of the multimedia pipes system had to consider its feasibility and the installation process, since a complicated geometry could affect the installation cost and make the solution less interesting. As result of the investigation, it was found that the final geometry has an average heat uptake approximately equal to 20 W/m.

Implementation of the solution

Different solutions were evaluated to install the heat recovery pipe on the DH pipe in a real scale installation without affecting the installation cost and ensuring an easy installation method.. The solution will be applied in a distribution pipe of the new network in the Østerby district, where real-scale measurements will monitor the performance of this new solution.

Learn more

Since this is a confidential deliverable it is not available for download. However, if you are interested in learning more, please contact Emanuele Zilio, engineer at COWI A/S.

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