Hydraulic transient modeling and analysis of the district heating network

The hydraulic transients are obvious during the operation and adjustment of large-scale district heating (DH) network. Hydraulic transient modeling and simulation methods can provide basis for efficient operation of the DH network. In this paper, two hydraulic transient models, the distributed parameter model (DPM) and lumped parameter model (LPM), were established for DH network. Efficient numerical algorithms were presented for the two models. The proposed DPM and LPM were both applied to a DH network to simulate and analyze the network hydraulic transients caused by the valve and pump operations. Results indicate that with the increase of the distance from the adjustment location, the transient time for the flow rate and pressure gets longer. As the adjustment duration decreases, the transient time increases. Comparison of the simulation performances between the two models indicates that the DPM can capture the high-frequency hydraulic transients subtly. With the decrease of adjustment duration, more severe high-frequency hydraulic transients will occur. However, only the average hydraulic fluctuations can be described by LPM. The computation time of LPM is shorter than DPM because of the vectorizable calculation procedure and the less data to record, since the LPM neglects the pressure waves and the fluid compressibility