Abstract
In an ongoing project, low-investment measures for the optimization of district heating systems are analyzed. The optimization strategies are collected in a catalog, which is the core of a guideline. The application of this guideline is demonstrated using two concrete district heating networks as examples. In this study, the improvement of an analog controlled district heating substation by an electronic controller is investigated. High supply temperatures and heat losses are often a challenge in district heating networks. The district heating substations have a major influence on the network return temperatures. The comparison of the two substation setups with analog and electronic controllers is carried out by laboratory measurement. It can be shown that the return temperatures can be reduced by an average of 20 K in winter and transition, as well as 16 K in summer. The district heating network losses are calculated for one of both specific district heating networks. They are calculated from the ratio of network losses to generated energy. The generated energy is the sum of network losses and consumer demand. The thermal losses of the network can be reduced by 3%. The volume flow in the heating network can be reduced to a quarter. Therefore, the pumping energy requirement drops sharply since these changes cubically affect the volume flow.
Highlights
The presented study is in the context of the transformation of existing district heating networks (DHNs) into so called fourth generation DHNs’ [1]
The cost of the energy system was reduced by about 3%, and total primary energy demand was reduced by 4.5%, which was achieved as a result of the better integration of industrial waste heat and heat pumps to DHNs
To ensure sufficient quality of the measurement data, the same boundary conditions must be met during the measurement. This includes that the constant supply temperature on the primary side of 75 ◦ C for the DHN emulation is met, as well as that the temperature decrease in the heating circuit corresponds to the setpoint of 40 ◦ C in case of ElecDHS and mand of the circulation pump allows for an extrapolation of the electrical energy savings
Summary
The presented study is in the context of the transformation of existing district heating networks (DHNs) into so called fourth generation DHNs’ [1]. Some studies have described this transformation [2,3] This transformation ensures the continued existence of DHNs in the future, as it aims for lower heat losses and allows the integration of low-temperature heat into DHNs, such as renewable-energy based heat sources or industrial excess heat. The cost of the energy system was reduced by about 3%, and total primary energy demand was reduced by 4.5%, which was achieved as a result of the better integration of industrial waste heat and heat pumps to DHNs. Averfalk and Werner [5] pointed out that in the case of heat generation from geothermal energy, industrial excess heat, solar thermal energy and heat pumps, the influence of lower network temperatures on heat generation costs is distinctive
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