A theoretical benchmark for bypass controllers in a residential district heating network

Abstract

Bypass valves in district heating substations are a compromise between efficiency and quality of service. On the one hand, they are required to ensure that each building (no matter the distance to the heat source) has warm water within an acceptable time. On the other hand, they form a short-circuit between the warm supply and cold return line and their use can increase the return temperature substantially. Therefore, a good control of these bypass valves is critical to limit the drawback of their use. In this context, this paper compares two commonly used control strategies (manual control and thermostat control) to a new theoretical benchmark that provides an upper boundary for the performance of bypass controllers. This theoretical benchmark ensures a justin-time delivery of warm water by taking into account time delays in the network. In a simulation case study of a small neighbourhood in Genk, Belgium, the benchmark shows that substantial improvement regarding bypass control is possible.

Grouped Charging of Decentralised Storage to Efficiently Control Collective Heating Systems: Limitations and Opportunities

“…The focus of this research is on optimising the supply-temperature-control strategy for 2-pipe collective heating systems in apartment buildings. In the absence of appropriate supply-temperature-control strategies, the T sup;SP is usually fixed at the hottest demand, and decentralised storage is only used to reduce waiting times and to eliminate the need for bypass valves between supply and return [38]. In this respect, the contributions of the presented research are twofold:…”

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“…In A Theoretical Benchmark for Bypass Controllers in a Residential District Heating Network[42], Vandermeulen et al compare two commonly used control strategies (manual control and thermostatic control) to a new theoretical benchmark that provides an upper boundary for the performance of bypass controllers. This theoretical benchmark ensures a just-in-time delivery of warm water by taking into account time delays in the network.In Technical Assessment of Electric Heat Boosters in Low-Temperature District Heating based on Combined Heat and Power Analysis[43], Cai et al provide a technical assessment of electric heat boosters (EHBs) in low-energy districts and demonstrate that lower supply temperatures and intelligent components can improve system efficiency and turn the district heating network into an integrated part of sustainable energy systems.…”