Chilled Water Loop with Branches & AHUs
Problem
Design and simulate a chilled water loop with:
- Central pump and chiller
- Main distribution header
- 5 branch lines, each feeding 5 AHUs (Air Handling Units) in series
- Return headers combining flow back to the expansion tank
Demonstrates handling large network topologies, fixed diameters, and multiple equipment elements.
The network is built with add_node and add_edge, so the engine solves it as a graph: the flow in each edge comes from the mass balance at the nodes, and the five branches between Main_Out and Return_Header share the flow so that the pressure drop is the same through each of them (four loops). The closed circuit is opened at the tank: Tank (the pump suction) is the inlet node, the only node no edge enters, and Return_Tank is the outlet node, the only node no edge leaves. The governing drop from Tank to Return_Tank is then the drop around the whole circuit, pump included.
Code
from processpi.pipelines.engine import PipelineEngine
from processpi.pipelines.pipes import Pipe
from processpi.pipelines.network import PipelineNetwork
from processpi.pipelines.pumps import Pump
from processpi.pipelines.vessel import Vessel
from processpi.pipelines.equipment import Equipment
from processpi.units import *
from processpi.components import Water
# ---------------- Create Network ----------------
net = PipelineNetwork("Chilled Water Loop")
# ---------------- Nodes ----------------
net.add_node("Tank", elevation=0) # tank outlet: the inlet node
net.add_node("Pump_In", elevation=0)
net.add_node("Pump_Out", elevation=1)
net.add_node("Chiller_Out", elevation=1)
net.add_node("Main_In", elevation=1)
net.add_node("Main_Out", elevation=1)
# Branch and AHU nodes
for b in range(1, 6):
net.add_node(f"Branch_{b}_In", elevation=1)
for a in range(1, 6):
net.add_node(f"AHU_{b}_{a}_PipeOut", elevation=1)
net.add_node(f"AHU_{b}_{a}_EqOut", elevation=1)
net.add_node(f"Return_{b}", elevation=0)
net.add_node("Return_Header", elevation=0)
net.add_node("Return_Tank", elevation=0) # tank return: the outlet node
# ---------------- Components ----------------
pump = Pump(
name="Pump1",
pump_type="Centrifugal",
inlet_pressure=Pressure(101325, "Pa"),
outlet_pressure=Pressure(201325, "Pa")
)
vessel = Vessel("ExpansionTank")
chiller = Equipment("Chiller", pressure_drop=0.2)
# ---------------- Build Network ----------------
# Tank → Pump → Chiller
net.add_edge(Pipe("TankPipe", length=Length(5, "m")), "Tank", "Pump_In")
net.add_edge(pump, "Pump_In", "Pump_Out")
net.add_edge(chiller, "Pump_Out", "Chiller_Out")
# Chiller → Main header
net.add_edge(Pipe("MainPipe", length=Length(15, "m")), "Chiller_Out", "Main_In")
net.add_edge(Pipe("MainPipe_Out", length=Length(5, "m")), "Main_In", "Main_Out")
# Branch inlets
for b in range(1, 6):
net.add_edge(Pipe(f"MainToBranch_{b}", length=Length(3, "m")), "Main_Out", f"Branch_{b}_In")
# ---------------- AHU pipes (fixed diameters) ----------------
ahu_diameters = [Diameter(3, "in"), Diameter(4, "in"), Diameter(4, "in"),
Diameter(5, "in"), Diameter(6, "in")]
ahu_flows = [VolumetricFlowRate(8, "m3/h"), VolumetricFlowRate(10, "m3/h"),
VolumetricFlowRate(10, "m3/h"), VolumetricFlowRate(12, "m3/h"),
VolumetricFlowRate(15, "m3/h")]
for b in range(1, 6):
for a in range(1, 6):
dia = ahu_diameters[(a - 1) % len(ahu_diameters)]
in_node = f"Branch_{b}_In" if a == 1 else f"AHU_{b}_{a-1}_EqOut"
pipe_out = f"AHU_{b}_{a}_PipeOut"
eq_out = f"AHU_{b}_{a}_EqOut"
# Pipe
net.add_edge(Pipe(f"AHUPipe_{b}_{a}", nominal_diameter=dia, length=Length(5, "m")), in_node, pipe_out)
# AHU equipment
pd = 0.05 + 0.01 * (ahu_flows[(a - 1) % len(ahu_flows)].to("m3/h").value / 10)
net.add_edge(Equipment(f"AHU_{b}_{a}", pressure_drop=pd), pipe_out, eq_out)
# Branch returns
for b in range(1, 6):
last_ahu_out = f"AHU_{b}_5_EqOut"
net.add_edge(Pipe(f"BranchReturnPipe_{b}", length=Length(5, "m")), last_ahu_out, f"Return_{b}")
# Returns → Return header → Expansion tank
for b in range(1, 6):
net.add_edge(Pipe(f"ReturnPipe_{b}", length=Length(10, "m")), f"Return_{b}", "Return_Header")
net.add_edge(vessel, "Return_Header", "Return_Tank")
# ---------------- Fluid & Flow ----------------
fluid = Water(temperature=Temperature(10, "C"), pressure=Pressure(101325, "Pa"))
flow_rate = VolumetricFlowRate(300, "m3/h")
# ---------------- Engine ----------------
model = PipelineEngine()
model.fit(fluid=fluid, flow_rate=flow_rate, network=net)
results = model.run()
# ---------------- Results ----------------
results.summary()
results.detailed_summary()
Output
# Summary
🔄 Auto-sizing network pipe diameters...
🔍 Pipe TankPipe: No available DP provided. Showing candidates:
8.0 in -> 2.58 m/s, 1309.13 Pa
10.0 in -> 1.64 m/s, 420.66 Pa
12.0 in -> 1.14 m/s, 172.13 Pa
🔍 Pipe MainPipe: No available DP provided. Showing candidates:
8.0 in -> 2.58 m/s, 3927.38 Pa
10.0 in -> 1.64 m/s, 1261.98 Pa
12.0 in -> 1.14 m/s, 516.40 Pa
🔍 Pipe MainPipe_Out: No available DP provided. Showing candidates:
8.0 in -> 2.58 m/s, 1309.13 Pa
10.0 in -> 1.64 m/s, 420.66 Pa
12.0 in -> 1.14 m/s, 172.13 Pa
🔍 Pipe MainToBranch_1: No available DP provided. Showing candidates:
4.0 in -> 2.03 m/s, 1144.52 Pa
5.0 in -> 1.29 m/s, 371.32 Pa
6.0 in -> 0.89 m/s, 149.82 Pa
🔍 Pipe MainToBranch_2: No available DP provided. Showing candidates:
4.0 in -> 2.03 m/s, 1144.52 Pa
5.0 in -> 1.29 m/s, 371.32 Pa
6.0 in -> 0.89 m/s, 149.82 Pa
🔍 Pipe MainToBranch_3: No available DP provided. Showing candidates:
4.0 in -> 2.03 m/s, 1144.52 Pa
5.0 in -> 1.29 m/s, 371.32 Pa
6.0 in -> 0.89 m/s, 149.82 Pa
🔍 Pipe MainToBranch_4: No available DP provided. Showing candidates:
4.0 in -> 2.03 m/s, 1144.52 Pa
5.0 in -> 1.29 m/s, 371.32 Pa
6.0 in -> 0.89 m/s, 149.82 Pa
🔍 Pipe MainToBranch_5: No available DP provided. Showing candidates:
4.0 in -> 2.03 m/s, 1144.52 Pa
5.0 in -> 1.29 m/s, 371.32 Pa
6.0 in -> 0.89 m/s, 149.82 Pa
🔍 Pipe BranchReturnPipe_1: No available DP provided. Showing candidates:
4.0 in -> 2.03 m/s, 1907.53 Pa
5.0 in -> 1.29 m/s, 618.87 Pa
6.0 in -> 0.89 m/s, 249.70 Pa
🔍 Pipe BranchReturnPipe_2: No available DP provided. Showing candidates:
4.0 in -> 2.03 m/s, 1907.53 Pa
5.0 in -> 1.29 m/s, 618.87 Pa
6.0 in -> 0.89 m/s, 249.70 Pa
🔍 Pipe BranchReturnPipe_3: No available DP provided. Showing candidates:
4.0 in -> 2.03 m/s, 1907.53 Pa
5.0 in -> 1.29 m/s, 618.87 Pa
6.0 in -> 0.89 m/s, 249.70 Pa
🔍 Pipe BranchReturnPipe_4: No available DP provided. Showing candidates:
4.0 in -> 2.03 m/s, 1907.53 Pa
5.0 in -> 1.29 m/s, 618.87 Pa
6.0 in -> 0.89 m/s, 249.70 Pa
🔍 Pipe BranchReturnPipe_5: No available DP provided. Showing candidates:
4.0 in -> 2.03 m/s, 1907.53 Pa
5.0 in -> 1.29 m/s, 618.87 Pa
6.0 in -> 0.89 m/s, 249.70 Pa
🔍 Pipe ReturnPipe_1: No available DP provided. Showing candidates:
4.0 in -> 2.03 m/s, 3815.06 Pa
5.0 in -> 1.29 m/s, 1237.74 Pa
6.0 in -> 0.89 m/s, 499.40 Pa
🔍 Pipe ReturnPipe_2: No available DP provided. Showing candidates:
4.0 in -> 2.03 m/s, 3815.05 Pa
5.0 in -> 1.29 m/s, 1237.74 Pa
6.0 in -> 0.89 m/s, 499.40 Pa
🔍 Pipe ReturnPipe_3: No available DP provided. Showing candidates:
4.0 in -> 2.03 m/s, 3815.05 Pa
5.0 in -> 1.29 m/s, 1237.74 Pa
6.0 in -> 0.89 m/s, 499.40 Pa
🔍 Pipe ReturnPipe_4: No available DP provided. Showing candidates:
4.0 in -> 2.03 m/s, 3815.05 Pa
5.0 in -> 1.29 m/s, 1237.74 Pa
6.0 in -> 0.89 m/s, 499.40 Pa
🔍 Pipe ReturnPipe_5: No available DP provided. Showing candidates:
4.0 in -> 2.03 m/s, 3815.05 Pa
5.0 in -> 1.29 m/s, 1237.74 Pa
6.0 in -> 0.89 m/s, 499.40 Pa
=== Pipeline Result 1 (N/A) ===
Mode: Network
Nominal Pipe Size: 10 in
Internal Diameter: 254.46 mm
Inlet Flow: 0.083 m3/s
Outlet Flow: 0.083 m3/s
Total Pressure Drop: 0.00 kPa
Total Head Loss: 0.00 m
Total Power Required: 0.00 kW
Velocity: 0.000 m/s
Reynolds Number: 0 (dimensionless)
Friction Factor: 0.0000 (dimensionless)
Flow Solver: graph, 4 loop(s), converged in 8 iteration(s)
Governing Outlet: Return_Tank (drop from inlet Tank: -38.49 kPa)
Outlet Flows: Return_Tank 300.00 m3/h
# Detailed Summary
=== Detailed Components for Result 1 (N/A) ===
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| Name | Type | Edge | Flow (m3/h) | Pressure Drop | Velocity | Reynolds | Friction Factor | Nominal Size | Internal Diameter |
+====================+===========+=================================+===============+=================+============+============+===================+================+=====================+
| TankPipe | pipe | Tank > Pump_In | 300 | 420.66 | 1.64 | 320192 | 0.0159 | 10 in | 254.46 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| Pump1 | pump | Pump_In > Pump_Out | 300 | -90195.8 | 0 | 0 | 0 | N/A | N/A |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| Chiller | equipment | Pump_Out > Chiller_Out | 300 | 20000 | 0 | 0 | 0 | N/A | N/A |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| MainPipe | pipe | Chiller_Out > Main_In | 300 | 1261.98 | 1.64 | 320192 | 0.0159 | 10 in | 254.46 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| MainPipe_Out | pipe | Main_In > Main_Out | 300 | 420.66 | 1.64 | 320192 | 0.0159 | 10 in | 254.46 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| MainToBranch_1 | pipe | Main_Out > Branch_1_In | 60 | 371.32 | 1.29 | 127108 | 0.019 | 5 in | 128.20 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| MainToBranch_2 | pipe | Main_Out > Branch_2_In | 60 | 371.32 | 1.29 | 127108 | 0.019 | 5 in | 128.20 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| MainToBranch_3 | pipe | Main_Out > Branch_3_In | 60 | 371.32 | 1.29 | 127108 | 0.019 | 5 in | 128.20 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| MainToBranch_4 | pipe | Main_Out > Branch_4_In | 60 | 371.32 | 1.29 | 127108 | 0.019 | 5 in | 128.20 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| MainToBranch_5 | pipe | Main_Out > Branch_5_In | 60 | 371.32 | 1.29 | 127108 | 0.019 | 5 in | 128.20 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHUPipe_1_1 | pipe | Branch_1_In > AHU_1_1_PipeOut | 60 | 7497.39 | 3.5 | 209127 | 0.0191 | 3 in | 77.92 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHU_1_1 | equipment | AHU_1_1_PipeOut > AHU_1_1_EqOut | 60 | 5000.22 | 0 | 0 | 0 | N/A | N/A |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHUPipe_1_2 | pipe | AHU_1_1_EqOut > AHU_1_2_PipeOut | 60 | 1907.53 | 2.03 | 159351 | 0.019 | 4 in | 102.26 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHU_1_2 | equipment | AHU_1_2_PipeOut > AHU_1_2_EqOut | 60 | 5000.28 | 0 | 0 | 0 | N/A | N/A |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHUPipe_1_3 | pipe | AHU_1_2_EqOut > AHU_1_3_PipeOut | 60 | 1907.53 | 2.03 | 159351 | 0.019 | 4 in | 102.26 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHU_1_3 | equipment | AHU_1_3_PipeOut > AHU_1_3_EqOut | 60 | 5000.28 | 0 | 0 | 0 | N/A | N/A |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHUPipe_1_4 | pipe | AHU_1_3_EqOut > AHU_1_4_PipeOut | 60 | 618.87 | 1.29 | 127108 | 0.019 | 5 in | 128.20 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHU_1_4 | equipment | AHU_1_4_PipeOut > AHU_1_4_EqOut | 60 | 5000.33 | 0 | 0 | 0 | N/A | N/A |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHUPipe_1_5 | pipe | AHU_1_4_EqOut > AHU_1_5_PipeOut | 60 | 249.7 | 0.89 | 105758 | 0.0193 | 6 in | 154.08 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHU_1_5 | equipment | AHU_1_5_PipeOut > AHU_1_5_EqOut | 60 | 5000.42 | 0 | 0 | 0 | N/A | N/A |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHUPipe_2_1 | pipe | Branch_2_In > AHU_2_1_PipeOut | 60 | 7497.38 | 3.5 | 209127 | 0.0191 | 3 in | 77.92 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHU_2_1 | equipment | AHU_2_1_PipeOut > AHU_2_1_EqOut | 60 | 5000.22 | 0 | 0 | 0 | N/A | N/A |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHUPipe_2_2 | pipe | AHU_2_1_EqOut > AHU_2_2_PipeOut | 60 | 1907.53 | 2.03 | 159351 | 0.019 | 4 in | 102.26 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHU_2_2 | equipment | AHU_2_2_PipeOut > AHU_2_2_EqOut | 60 | 5000.28 | 0 | 0 | 0 | N/A | N/A |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHUPipe_2_3 | pipe | AHU_2_2_EqOut > AHU_2_3_PipeOut | 60 | 1907.53 | 2.03 | 159351 | 0.019 | 4 in | 102.26 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHU_2_3 | equipment | AHU_2_3_PipeOut > AHU_2_3_EqOut | 60 | 5000.28 | 0 | 0 | 0 | N/A | N/A |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHUPipe_2_4 | pipe | AHU_2_3_EqOut > AHU_2_4_PipeOut | 60 | 618.87 | 1.29 | 127108 | 0.019 | 5 in | 128.20 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHU_2_4 | equipment | AHU_2_4_PipeOut > AHU_2_4_EqOut | 60 | 5000.33 | 0 | 0 | 0 | N/A | N/A |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHUPipe_2_5 | pipe | AHU_2_4_EqOut > AHU_2_5_PipeOut | 60 | 249.7 | 0.89 | 105758 | 0.0193 | 6 in | 154.08 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHU_2_5 | equipment | AHU_2_5_PipeOut > AHU_2_5_EqOut | 60 | 5000.42 | 0 | 0 | 0 | N/A | N/A |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHUPipe_3_1 | pipe | Branch_3_In > AHU_3_1_PipeOut | 60 | 7497.38 | 3.5 | 209127 | 0.0191 | 3 in | 77.92 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHU_3_1 | equipment | AHU_3_1_PipeOut > AHU_3_1_EqOut | 60 | 5000.22 | 0 | 0 | 0 | N/A | N/A |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHUPipe_3_2 | pipe | AHU_3_1_EqOut > AHU_3_2_PipeOut | 60 | 1907.53 | 2.03 | 159351 | 0.019 | 4 in | 102.26 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHU_3_2 | equipment | AHU_3_2_PipeOut > AHU_3_2_EqOut | 60 | 5000.28 | 0 | 0 | 0 | N/A | N/A |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHUPipe_3_3 | pipe | AHU_3_2_EqOut > AHU_3_3_PipeOut | 60 | 1907.53 | 2.03 | 159351 | 0.019 | 4 in | 102.26 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHU_3_3 | equipment | AHU_3_3_PipeOut > AHU_3_3_EqOut | 60 | 5000.28 | 0 | 0 | 0 | N/A | N/A |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHUPipe_3_4 | pipe | AHU_3_3_EqOut > AHU_3_4_PipeOut | 60 | 618.87 | 1.29 | 127108 | 0.019 | 5 in | 128.20 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHU_3_4 | equipment | AHU_3_4_PipeOut > AHU_3_4_EqOut | 60 | 5000.33 | 0 | 0 | 0 | N/A | N/A |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHUPipe_3_5 | pipe | AHU_3_4_EqOut > AHU_3_5_PipeOut | 60 | 249.7 | 0.89 | 105758 | 0.0193 | 6 in | 154.08 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHU_3_5 | equipment | AHU_3_5_PipeOut > AHU_3_5_EqOut | 60 | 5000.42 | 0 | 0 | 0 | N/A | N/A |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHUPipe_4_1 | pipe | Branch_4_In > AHU_4_1_PipeOut | 60 | 7497.38 | 3.5 | 209127 | 0.0191 | 3 in | 77.92 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHU_4_1 | equipment | AHU_4_1_PipeOut > AHU_4_1_EqOut | 60 | 5000.22 | 0 | 0 | 0 | N/A | N/A |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHUPipe_4_2 | pipe | AHU_4_1_EqOut > AHU_4_2_PipeOut | 60 | 1907.53 | 2.03 | 159351 | 0.019 | 4 in | 102.26 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHU_4_2 | equipment | AHU_4_2_PipeOut > AHU_4_2_EqOut | 60 | 5000.28 | 0 | 0 | 0 | N/A | N/A |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHUPipe_4_3 | pipe | AHU_4_2_EqOut > AHU_4_3_PipeOut | 60 | 1907.53 | 2.03 | 159351 | 0.019 | 4 in | 102.26 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHU_4_3 | equipment | AHU_4_3_PipeOut > AHU_4_3_EqOut | 60 | 5000.28 | 0 | 0 | 0 | N/A | N/A |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHUPipe_4_4 | pipe | AHU_4_3_EqOut > AHU_4_4_PipeOut | 60 | 618.87 | 1.29 | 127108 | 0.019 | 5 in | 128.20 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHU_4_4 | equipment | AHU_4_4_PipeOut > AHU_4_4_EqOut | 60 | 5000.33 | 0 | 0 | 0 | N/A | N/A |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHUPipe_4_5 | pipe | AHU_4_4_EqOut > AHU_4_5_PipeOut | 60 | 249.7 | 0.89 | 105758 | 0.0193 | 6 in | 154.08 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHU_4_5 | equipment | AHU_4_5_PipeOut > AHU_4_5_EqOut | 60 | 5000.42 | 0 | 0 | 0 | N/A | N/A |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHUPipe_5_1 | pipe | Branch_5_In > AHU_5_1_PipeOut | 60 | 7497.38 | 3.5 | 209127 | 0.0191 | 3 in | 77.92 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHU_5_1 | equipment | AHU_5_1_PipeOut > AHU_5_1_EqOut | 60 | 5000.22 | 0 | 0 | 0 | N/A | N/A |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHUPipe_5_2 | pipe | AHU_5_1_EqOut > AHU_5_2_PipeOut | 60 | 1907.53 | 2.03 | 159351 | 0.019 | 4 in | 102.26 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHU_5_2 | equipment | AHU_5_2_PipeOut > AHU_5_2_EqOut | 60 | 5000.28 | 0 | 0 | 0 | N/A | N/A |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHUPipe_5_3 | pipe | AHU_5_2_EqOut > AHU_5_3_PipeOut | 60 | 1907.53 | 2.03 | 159351 | 0.019 | 4 in | 102.26 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHU_5_3 | equipment | AHU_5_3_PipeOut > AHU_5_3_EqOut | 60 | 5000.28 | 0 | 0 | 0 | N/A | N/A |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHUPipe_5_4 | pipe | AHU_5_3_EqOut > AHU_5_4_PipeOut | 60 | 618.87 | 1.29 | 127108 | 0.019 | 5 in | 128.20 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHU_5_4 | equipment | AHU_5_4_PipeOut > AHU_5_4_EqOut | 60 | 5000.33 | 0 | 0 | 0 | N/A | N/A |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHUPipe_5_5 | pipe | AHU_5_4_EqOut > AHU_5_5_PipeOut | 60 | 249.7 | 0.89 | 105758 | 0.0193 | 6 in | 154.08 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| AHU_5_5 | equipment | AHU_5_5_PipeOut > AHU_5_5_EqOut | 60 | 5000.42 | 0 | 0 | 0 | N/A | N/A |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| BranchReturnPipe_1 | pipe | AHU_1_5_EqOut > Return_1 | 60 | -9185.31 | 1.29 | 127108 | 0.019 | 5 in | 128.20 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| BranchReturnPipe_2 | pipe | AHU_2_5_EqOut > Return_2 | 60 | -9185.31 | 1.29 | 127108 | 0.019 | 5 in | 128.20 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| BranchReturnPipe_3 | pipe | AHU_3_5_EqOut > Return_3 | 60 | -9185.31 | 1.29 | 127108 | 0.019 | 5 in | 128.20 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| BranchReturnPipe_4 | pipe | AHU_4_5_EqOut > Return_4 | 60 | -9185.31 | 1.29 | 127108 | 0.019 | 5 in | 128.20 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| BranchReturnPipe_5 | pipe | AHU_5_5_EqOut > Return_5 | 60 | -9185.31 | 1.29 | 127108 | 0.019 | 5 in | 128.20 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| ReturnPipe_1 | pipe | Return_1 > Return_Header | 60 | 1237.74 | 1.29 | 127108 | 0.019 | 5 in | 128.20 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| ReturnPipe_2 | pipe | Return_2 > Return_Header | 60 | 1237.74 | 1.29 | 127108 | 0.019 | 5 in | 128.20 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| ReturnPipe_3 | pipe | Return_3 > Return_Header | 60 | 1237.74 | 1.29 | 127108 | 0.019 | 5 in | 128.20 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| ReturnPipe_4 | pipe | Return_4 > Return_Header | 60 | 1237.74 | 1.29 | 127108 | 0.019 | 5 in | 128.20 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| ReturnPipe_5 | pipe | Return_5 > Return_Header | 60 | 1237.74 | 1.29 | 127108 | 0.019 | 5 in | 128.20 mm |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
| ExpansionTank | vessel | Return_Header > Return_Tank | 300 | 0 | 0 | 0 | 0 | N/A | N/A |
+--------------------+-----------+---------------------------------+---------------+-----------------+------------+------------+-------------------+----------------+---------------------+
+-------------+---------------+-------------------------+
| Outlet | Flow (m3/h) | Drop from Inlet (kPa) |
+=============+===============+=========================+
| Return_Tank | 300 | -38.49 |
+-------------+---------------+-------------------------+
Reading the results
- Each branch carries 60 m3/h (300 m3/h over five equal branches), so the 3 in AHU pipes run at 3.50 m/s and the branch pipes are sized for 60 m3/h (5 in, 1.29 m/s). Before the graph solve every pipe carried the full 300 m3/h: the 3 in AHU pipes ran at 17.48 m/s and the total drop was 1439.81 kPa.
- The pressure drop column is the start pressure minus the end pressure of each edge, static head included: the branch return pipes fall 1 m and gain 9.80 kPa, and the pump row is its 100 kPa gain less the 1 m it lifts the water.
- The circuit loses 61.51 kPa (6.27 m of water at 10 C). The pump's 1 bar is 38.49 kPa more than that, so the drop from
TanktoReturn_Tankis -38.49 kPa. The summary's Total Pressure Drop, Head Loss and Power Required cannot show a net rise, so they read 0; the governing outlet line andresults.results["summary"]["total_pressure_drop_Pa"]keep the sign.