exergyflow 0.1.1

Sankey and Grassmann diagrams for energy and exergy analysis

ExergyFlow

Grassmann/Sankey diagrams for energy and exergy analysis

Install

python -m pip install exergyflow

Quickstart

from exergyflow import Diagram, DiagramConfig, RouteSegment
d = Diagram(DiagramConfig(auto_scale=True, auto_scale_target=1.0))
d.add_process("P1")
d.add_flow("F1", 10, source=None, target="P1")
d.add_flow("F2", 5, source="P1", target=None)
route1 = [RouteSegment(kind='rect', length=0.25, direction='right'),
          RouteSegment(kind='elbow', length=0.25, turn='rightup'),
          RouteSegment(kind='rect', length=0.5, direction='up')]
d.add_flow("F3", 2, source="P1", target=None, route=route1)
fig, ax = d.draw()
fig.savefig("diagram.png", dpi=300, bbox_inches="tight")

Real engineering example

A simplified Brayton flow sketch (values illustrative):

from exergyflow import Diagram, DiagramConfig, RouteSegment

cfg = DiagramConfig(flow_value_unit="kW", flow_value_format=".0f",
                    auto_scale=True, auto_scale_target=2.0)
d = Diagram(cfg)

# Processes
d.add_process("Compressor", direction="up", length=2.5,
              label_rotation=90, color="#59a2d3")
d.add_process("Combustor", direction="right", length=2.5, color="#59a2d3")
d.add_process("Turbine", direction="down", label_rotation=-90, color="#59a2d3")

# Routes
route_work_out = [
    RouteSegment(kind='rect', length=0.25, direction='down'),
    RouteSegment(kind='elbow', length=0.5, turn='downright'),
    RouteSegment(kind='rect', length=2.5, direction='right')
]
route_exhaust = [
    RouteSegment(kind='rect', length=1.5, direction='down'),
    RouteSegment(kind='elbow', length=0.5, turn='downright'),
    RouteSegment(kind='rect', length=2.6, direction='right')
]
route_air = [
    RouteSegment(kind='rect', length=3.5, direction='right'),
    RouteSegment(kind='elbow', length=0.5, turn='rightup'),
    RouteSegment(kind='rect', length=0.5, direction='up')
]

# Flows
d.add_flow("Work_out", 220, source="Turbine",
           target=None, label="W_t", route=route_work_out)
d.add_flow("Exhaust", 180, source="Turbine", target=None,
           label="E_exh", route=route_exhaust)
d.add_flow("Work_in", 80, source="Turbine",
           target="Compressor", label="W_c", cycle_breaker=True, label_dy=-0.3)
d.add_flow("Air", 280, source=None,
           target="Compressor", label="E_air", route=route_air)
d.add_flow("Compressed", 300, source="Compressor",
           target="Combustor", label="E_2", label_dy=0.2)
d.add_flow("Fuel", 700, source=None,
           target="Combustor", length=7.75, label="E_f")
d.add_flow("Hot_gas", 560, source="Combustor",
           target="Turbine", label="E_3", label_dy=0.2)
fig, ax = d.draw()
fig.savefig("brayton.svg", dpi=300, bbox_inches="tight")

Advantages

• Built for thermodynamic energy and exergy conventions, including imbalance triangles and process-aware flow direction rules.
• Auto-layout for fast drafts, manual routing for publication-grade control.
• Matplotlib-native output for crisp vector export (SVG/PDF) without extra tooling.
• Deterministic layout and explicit routing rules help reproduce figures consistently.
• Built-in unit formatting for labels keeps diagrams engineering-ready.

Details

• Supported Python versions: 3.9–3.14 (see pyproject.toml).
• flow_label_mode options: name_value_units (default), value_units, value_only.
• Units formatting: flow_value_unit, flow_value_format, flow_value_unit_sep.
• Auto-layout expects a DAG; use cycle_breaker=True on a process→process flow to break cycles.
• Manual routing must alternate rect and elbow segments and start/end with rect.
• Matplotlib-native output: export PNG, SVG, or PDF via fig.savefig(...).

Docs

• Step-by-step guide
• Cheatsheet

Advanced example

For an advanced example see: Example script