Potential for supply temperature reduction of existing district heating substations

Reducing operating temperatures is a crucial goal for transforming district heating networks into sustainable systems as it allows the integration of low exergy heat (e.g. renewable, waste heat). Many criticalities arise when reducing operating temperatures in existing networks that are not designed to operate in these conditions. The criticalities occur at different levels: in the building, in the thermal substations, in the pipelines and in the production plants. In this paper, the reduction of supply temperature in existing district heating substations is analyzed. A methodology including a model of the thermal substation and a data analysis software is developed to estimate the potential temperature reduction that could be applied to existing substations. The application of the model to an existing large-scale district heating network in Northern Italy shows that all the analyzed substations are currently able to shift their operation from 120 degrees C to 104 degrees C, and that district heating supply temperatures around 90 degrees C can be realistically achieved with few improvements on the system.

Automated summary

Reducing operating temperatures in district heating networks is crucial for integrating low exergy heat and achieving sustainability. This paper analyzes the potential temperature reduction in existing substations and develops a methodology to estimate the achievable temperature reduction. The results show that existing substations can shift their operation from 120°C to 104°C and achieve supply temperatures around 90°C with some improvements on the system.