An Efficient Numerical Solution Method for Detailed Modelling of Large 5th Generation District Heating and Cooling Networks

Numerical simulations of district heating and cooling networks constitute a valuable tool for system design and optimization. This paper presents a novel thermo-hydraulic network model, which addresses particularly large 5th generation district heating and cooling (5GDHC) networks. We paid special attention on detailed modelling of pipe pressure drops and heat losses, which are calculated based on current flow regime and temperature dependent fluid properties. Yet, the performance of our implementation is considerably higher compared to simplified models of similar size that use generic equation solver, such as Modelica, as we avoid typical performance issues due to tight coupling and solution of large equation systems. We describe the solution procedure of the hydraulic system equations embedded into the transient differential equation solver, which is an error-controlled, adaptive time step, variable order integration method. Further, we compare our implementation against a model from literature and found partly good agreement. Deviations are due the consideration of convection in our model, which we proof using an analytical solution. Eventually, we demonstrate the impact of modelling assumptions on simulation results and performance given a real-world 5GDHC network. The implementation is made available as open-source project for reference and general usage.div.standard { text-align: left; }