Hydraulic Network Sizing

A physics-based approach for automated mass flow calculation and pipe sizing in district heating networks.

Quick Start

import uesgraphs as ug
import uesgraphs.systemmodels.utilities as sysm_ut

# 1. Load your network
graph = ug.UESGraph()
graph.from_json("network.json", network_type="heating")

# 2. Set demand data and temperature differences
for node in graph.nodelist_building:
    if not graph.nodes[node].get("is_supply_heating", False):
        graph.nodes[node]["input_heat"] = 15000  # W (example: 15 kW peak load)
        graph.nodes[node]["dT_Network"] = 30.0   # K

# 3. Size the network
sized_graph = sysm_ut.size_hydronic_network(
    graph=graph,
    catalog="isoplus",
    load_scenario="peak_load"
)

# 4. Analyze results
for edge in sized_graph.edges:
    data = sized_graph.edges[edge]
    print(f"Pipe {edge}: {data['DN']}, {data['m_flow_peak_load']:.3f} kg/s")

Note

The function accepts both scalar values and time-series for input_heat:

Scalar: graph.nodes[node]["input_heat"] = 15000 (single peak load value)
Time-series: graph.nodes[node]["input_heat"] = [1000, 5000, 15000, ...] (automatically extracts peak/average based on load_scenario)

Prerequisites

Your graph needs these node attributes:

input_heat: Thermal demand [W] at each consumer node
dT_Network: Temperature difference [K] between supply and return
is_supply_heating: Boolean flag to identify supply nodes

How it Works

1. Demand-Based Mass Flow Calculation

The system calculates mass flows starting at consumer nodes using the fundamental equation:

\[\dot{m} = \frac{Q}{c_p \cdot \Delta T}\]

Where:

Q: Thermal load [W]
cp: Specific heat capacity (4184 J/kg·K for water)
ΔT: Temperature difference [K]

2. Flow Path Aggregation

Mass flows are aggregated backward through the network:

Identifies all supply-to-demand paths
Accumulates flows along each path
Applies maximum flow principle for robust sizing

3. Catalog-Based Pipe Selection

Matches calculated flows to real pipe diameters:

Uses manufacturer catalogs (e.g., Isoplus)
Selects next larger pipe if no exact match
Adds DN (nominal diameter) and diameter [m] attributes to edges

Core Functions

Mass Flow Calculation

# Calculate mass flows based on demand
graph = sysm_ut.estimate_m_flow_demand_based(
    graph=graph,
    network_type="heating",
    demand_attribute="input_heat",
    load_scenario="peak_load",  # or "average_load"
    dT_attribute="dT_Network"
)

Key features:

Scenario-based calculations (peak vs. average load)
Individual temperature differences per node
Robust path-based flow aggregation

Complete Hydraulic Sizing

# Full workflow: mass flows + pipe diameters
graph = sysm_ut.size_hydronic_network(
    graph=graph,
    catalog="isoplus",
    dT_attribute="dT_Network",
    network_type="heating",
    load_scenario="peak_load"
)

Output Attributes

After sizing, edges contain:

m_flow_peak_load or m_flow_average_load: Mass flow [kg/s]
DN: Nominal diameter designation (e.g., “DN50”)
diameter: Inner pipe diameter [m]

Learn More

For detailed examples, see the comprehensive tutorial notebook: Examples (Example 14: Hydronic Sizing).

Advanced Features

Custom pipe catalogs: Add your own manufacturer data
Multiple scenarios: Compare peak vs. average sizing
Temperature flexibility: Different ΔT per building type
Visualization: Integrated diameter plotting with uesgraphs.visuals

Note

This feature replaces the deprecated estimate_m_flow_nominal() function with a more accurate demand-based approach.