Condenser Design — Benzene Vapor Condensation

Problem

Design a horizontal shell & tube condenser to condense saturated benzene vapor using cooling water under the following operating conditions.

• Hot fluid: Benzene Vapor
• Mass flow rate: 12,000 kg/h
• Condensing temperature: 95°C
• Operating pressure: 1.2 bar
• Latent heat of condensation: 394 kJ/kg
• Cooling medium: Water
• Cooling water inlet temperature: 30°C
• Cooling water flow rate: 50,000 kg/h
• Maximum allowable shell-side pressure drop: 0.5 bar
• Maximum allowable tube-side pressure drop: 0.5 bar
• Heat exchanger orientation: Horizontal
• Design method: Bell–Delaware

---

Code

from processpi.units import *
from processpi.components import *
from processpi.streams import MaterialStream
from processpi.equipment.heatexchangers import HeatExchangerEngine


# ============================================
# DEFINE COMPONENTS
# ============================================

benzene = Benzene()
water = Water()


# ============================================
# DEFINE PROCESS STREAMS
# ============================================

hot_in = MaterialStream(
    "benzene_vapor_in",
    component=benzene,
    phase="vapor",
    temperature=Temperature(95, "C"),
    pressure=Pressure(1.2, "bar"),
    mass_flow=MassFlowRate(12000, "kg/h"),
)

hot_out = MaterialStream(
    "benzene_liquid_out",
    component=benzene,
    phase="liquid",
    temperature=Temperature(95, "C"),
)

cold_in = MaterialStream(
    "cw_in",
    component=water,
    phase="liquid",
    temperature=Temperature(30, "C"),
    pressure=Pressure(1, "bar"),
    mass_flow=MassFlowRate(50000, "kg/h"),
)

# Outlet temperature calculated automatically
cold_out = MaterialStream(
    "cw_out",
    component=water,
)


# ============================================
# CREATE CONDENSER MODEL
# ============================================

hx = HeatExchangerEngine(
    method="bell_delaware"
)

hx.fit(
    hx_type="condenser",

    hot_in=hot_in,
    hot_out=hot_out,

    cold_in=cold_in,
    cold_out=cold_out,

    latent_heat=394000,

    shell_dp=Pressure(0.5, "bar"),
    tube_dp=Pressure(0.5, "bar"),

    orientation="horizontal",
    mode="design",
)

results = hx.run()


# ============================================
# OUTPUT
# ============================================

print(results.summary())

# Complete engineering report
results.detailed_summary()

---

Output

Heat Exchanger Summary
------------------------------
Type                  : condenser
Method                : bell_delaware
Heat Duty             : 1313.333 kW
Area                  : 47.275 m²
U Calculated          : 466.475 W/m²·K
Tube Velocity         : 0.575 m/s
Shell Velocity        : 0.905 m/s
Tube Pressure Drop    : 0.000 psi
Shell Pressure Drop   : 0.000
Tube Count            : 264
Tube Length           : 3.0 m
Status                : UNKNOWN

Engineering Insights
------------------------------
• Heat-transfer coefficient within acceptable range.
• Tube-side velocity acceptable but below ideal turbulent range.
• Shell-side velocity acceptable.

Warnings
------------------------------
• Tube velocity low (0.58 m/s)
• Area slightly undersized — acceptable.
• [HYDRAULIC_WARNING] Thermal area pushes tube count above hydraulic velocity target; using capped thermo-hydraulic count.
• [CONVERGENCE_WARNING] Geometry stagnation detected.

---

Discussion

This example demonstrates the design of a horizontal shell & tube condenser using the Bell–Delaware shell-side analysis method.

Unlike a conventional heat exchanger, the hot process stream undergoes phase change from vapor to liquid. The required heat duty is therefore calculated primarily from the latent heat of condensation, while the cooling water absorbs the released energy.

The HeatExchangerEngine automatically performs:

• Phase-change energy balance
• Condenser sizing
• Heat-transfer area calculation
• Bell–Delaware shell-side corrections
• Tube bundle sizing
• Tube count optimization
• Tube and shell velocity calculations
• Hydraulic validation
• Engineering assessment and recommendations

Design Results

Parameter	Value
Heat Exchanger Type	Condenser
Design Method	Bell–Delaware
Orientation	Horizontal
Heat Duty	1313.33 kW
Required Area	47.27 m²
Calculated Overall U	466.48 W/m²·K
Tube Count	264
Tube Length	3.0 m
Tube Velocity	0.575 m/s
Shell Velocity	0.905 m/s

The calculated overall heat-transfer coefficient is within the expected range for a shell-and-tube condenser operating with water as the cooling medium.

The shell-side velocity is acceptable for efficient heat transfer. The tube-side velocity is lower than the preferred turbulent range, and the engine highlights this through engineering warnings while still producing a feasible design.

Engineering Assessment

The generated warnings indicate that the thermal design required a relatively large number of tubes, reducing the tube-side velocity. Rather than sacrificing thermal performance, ProcessPI applies a thermo-hydraulic balancing strategy to produce a practical design and clearly reports the associated engineering considerations.

The convergence warning indicates that the geometry optimization reached a stable solution without further meaningful improvements, which is common during iterative equipment sizing.

For a complete engineering report, use:

results.detailed_summary()

To inspect every calculation performed by the engine, use:

results.trace()

For diagnostic information including warnings, optimization actions, and convergence details, use:

results.debug_summary()