Unlike the hydraulic model, the thermal model is dynamic allowing for transient behaviour modelling. The main equations involved are based on Newton’s Joule heating equation. Which can be solved as a first order ODE but depends on the pipe temperature. Therefore, the model is extended to include the pipe’s heat transfer. The heat transfer occurring in the pipes to its surroundings are modelled using water and pipe heat balance equation. The model also considers the pipe’s external surroundings and applies the Courant-Friedrichs-Lewy condition. The results data includes fluid and pipe temperature profiles for all of the links in the network.
Input Parameters:
Variable
Unit
Description
D
String
Unique ID for the DH network
Name
String
Name for the DH network
Initial supply/return temperature
Float/ [°C]
The temperatures assigned to the supply/return pipes of the DH network. The default value is 120/70 °C; min values are 0/0 °C; max values are 150/100 °C.
Nodes
List
List of the nodes in the DH network (not tree nodes like in HDSASA )
Links
List
List of links in the DH system that connects the nodes, defines the topology of the network; can contain an ordered list of link items such as pipes, pumps, fittings.
Supply units
List
A list of all the supply units in the district heating network.
Demand units
List
A list of all the demand units in the district heating network.
Maximum flow rate
Float/ [m3/hour]
The max flow rate that can occur in every link of the DH network but can be overridden for individual links. This is used to determine how to discretize the pipes (important for computation).
Default value in 50 m3/hour; min value is 0 /hour; max value is 1 000 000 m3/hour
