name: heat-exchanger-design description: Specialized skill for heat exchanger sizing, rating, and optimization per TEMA standards including shell-and-tube, plate, and air-cooled configurations allowed-tools:

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• Bash metadata: specialization: mechanical-engineering domain: science category: thermal-fluid-analysis priority: high phase: 6 tools-libraries:
  • HTRI Xchanger Suite
  • Aspen Exchanger Design and Rating

Heat Exchanger Design Skill

Purpose

The Heat Exchanger Design skill provides comprehensive capabilities for sizing, rating, and optimizing heat exchangers according to TEMA standards, enabling systematic thermal-hydraulic design of shell-and-tube, plate, and air-cooled heat exchanger configurations.

Capabilities

• Shell-and-tube heat exchanger design and rating
• Plate heat exchanger sizing
• Air-cooled heat exchanger configuration
• LMTD and effectiveness-NTU methods
• Fouling factor consideration
• Pressure drop calculations
• HTRI Xchanger Suite integration
• Thermal-hydraulic optimization

Usage Guidelines

Design Methods

LMTD Method

1. Log Mean Temperature Difference

   LMTD = (ΔT1 - ΔT2) / ln(ΔT1/ΔT2)
   
   Q = U × A × F × LMTD
   
   Where:
   F = Correction factor for non-counterflow
   U = Overall heat transfer coefficient
   A = Heat transfer area
   

2. LMTD Correction Factors

   • One shell pass, 2/4/6 tube passes
   • Two shell passes, 4/8 tube passes
   • Crossflow configurations

Effectiveness-NTU Method

1. Effectiveness Definition

   ε = Q_actual / Q_max
   Q_max = Cmin × (Th,in - Tc,in)
   

2. NTU Calculation

   NTU = UA / Cmin
   Cr = Cmin / Cmax
   

3. Effectiveness Relations

   • Counterflow: ε = (1-exp(-NTU(1-Cr)))/(1-Cr×exp(-NTU(1-Cr)))
   • Parallel flow: ε = (1-exp(-NTU(1+Cr)))/(1+Cr)
   • Shell-and-tube: Complex correlations by TEMA type

Shell-and-Tube Design

1. TEMA Designations

   Front End	Shell	Rear End
   A - Channel	E - One-pass	L - Fixed tubesheet
   B - Bonnet	F - Two-pass	M - Fixed tubesheet
   N - Channel	J - Divided flow	N - Fixed tubesheet
   -	X - Crossflow	P - Outside packed
   -	-	S - Floating head
   -	-	U - U-tube

2. Tube Layout

   • Triangular pitch (30°): Maximum tubes, poor cleaning
   • Square pitch (90°): Mechanical cleaning possible
   • Rotated square (45°): Higher turbulence

3. Baffle Design

   • Segmental: 20-45% cut
   • Double segmental: Reduced pressure drop
   • No-tubes-in-window: Vibration mitigation

Plate Heat Exchanger

1. Plate Selection

   • Chevron angle (25-65°): Trade-off h vs ΔP
   • Plate spacing: 2-5 mm typical
   • Pass arrangement: U or Z configuration

2. Design Considerations

   • Maximum pressure: 25-30 bar typical
   • Maximum temperature: 150-200°C (gaskets)
   • Fouling service: Not ideal

Air-Cooled Heat Exchanger

1. Configuration

   • Forced draft: Fan below bundle
   • Induced draft: Fan above bundle
   • Natural draft: No fan (limited duty)

2. Design Parameters

   • Face velocity: 2.5-3.5 m/s
   • Tube rows: 3-6 typical
   • Fin density: 275-435 fins/m

Fouling Considerations

Process Integration

• ME-012: Heat Exchanger Design and Rating
• ME-011: Thermal Management Design

Input Schema

{
  "design_type": "sizing|rating",
  "exchanger_type": "shell_tube|plate|air_cooled",
  "hot_fluid": {
    "name": "string",
    "flow_rate": "number (kg/s)",
    "inlet_temp": "number (C)",
    "outlet_temp": "number (C, for sizing)"
  },
  "cold_fluid": {
    "name": "string",
    "flow_rate": "number (kg/s)",
    "inlet_temp": "number (C)",
    "outlet_temp": "number (C, for sizing)"
  },
  "pressure_constraints": {
    "hot_side_max_dp": "number (kPa)",
    "cold_side_max_dp": "number (kPa)"
  },
  "fouling_factors": {
    "hot_side": "number (m2K/kW)",
    "cold_side": "number (m2K/kW)"
  }
}

Output Schema

{
  "duty": "number (kW)",
  "geometry": {
    "type": "string (TEMA designation or plate type)",
    "area": "number (m2)",
    "shell_diameter": "number (mm)",
    "tube_count": "number",
    "tube_length": "number (m)"
  },
  "thermal": {
    "LMTD": "number (C)",
    "F_factor": "number",
    "U_clean": "number (W/m2K)",
    "U_dirty": "number (W/m2K)"
  },
  "hydraulic": {
    "shell_side_dp": "number (kPa)",
    "tube_side_dp": "number (kPa)"
  },
  "performance": {
    "effectiveness": "number",
    "NTU": "number"
  }
}

Best Practices

1. Always include fouling factors appropriate for the service
2. Verify pressure drop constraints are met on both sides
3. Check for vibration potential in shell-and-tube designs
4. Consider maintenance access in configuration selection
5. Apply TEMA tolerances for manufacturing variations
6. Use conservative correlations for preliminary sizing

Integration Points

• Connects with CFD Analysis for detailed flow distribution
• Feeds into HVAC System Design for system integration
• Supports Thermal Analysis for component-level design
• Integrates with Process Design for plant-level optimization