Search

The transition of existing second-generation district heating networks (DHN) towards lower temperature levels for operation can lead to energy savings and to fewer constraints for the pipes and substations. However, retrofitting measures on the distribution network are often inevitable in order to still guarantee heat demand satisfaction. This paper presents a methodology to efficiently identify and alleviate existing limitations for temperature lowering in the design of a DHN distribution network. After having identified the most restrictive assets through existing methods, we apply a multi-objective optimization on a dynamical thermal hydraulic simulator for selecting the most efficient modifications on the DHN to attain our target. We apply the developed methodology on a test case representing real DHN operation, and featuring 60 consumers and 260 pipes. The maximum operating temperature is decreased significantly and various modifications for retrofitting are proposed as a set of optimal solutions, forming a Pareto front approximation. This work, through the combined use of a non-linear, dynamic simulator, and a multi-objective optimization framework, allows also to consider a variety of assets (exchangers, pumps, pipes ...) as retrofitting targets and, thus, potentially identifies interesting solutions beyond common practices. • Lowering the supply temperature in district heating network can require the modification of the network. • The modifications of pipes, substations or pumps can be optimum using multi-objective optimization. • A dynamic thermohydraulic simulation is needed to ensure the optimality of a solution. [ABSTRACT FROM AUTHOR]

The efficiency of a District Heating (DH) network depends among other things on the quality of its design and more precisely on the sizing of the distribution network pipes. Providing DH designers with relevant methodology to select appropriate pipes is crucial to maximize the utility of those systems. This paper presents a methodology focusing on the optimal sizing of pipe diameters in DH networks: the methodology uses a genetic algorithm to generate a set of Pareto-optimal sizing choices. An implementation of the methodology is presented, and is validated on three test cases, each of them corresponding to an elementary configuration, which can be encountered in real-world DH network. As a result, the performance of the results provided by the optimization for each test case are as good or better than the best reference solutions we could provide. The last part of this paper addresses the scalability of the proposed sizing methodology. The interest of the presented methodology is lies in the typology of optimal solutions provided for the test cases that could not be devised with traditional sizing methods and by the scalability of the method that makes it suitable for optimal sizing at city scale. • An optimal sizing methodology for the pipes of district heating networks is presented. • The methodology is based on multi-objective optimization and simulation. • A validation and verification workflow for optimal design of the distribution of district heating network is presented. • The methodology can tackle district heating networks up to 200 consumers. [ABSTRACT FROM AUTHOR]