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Shell & Tube Heat Exchanger Design Calculator

Preliminary thermal sizing using LMTD and preliminary Kern-method correlations. References TEMA, API 660, and ASME requirements for engineering context.

Introduction to Shell & Tube Heat Exchanger Design

This free engineering calculator performs a preliminary thermal design of a shell-and-tube heat exchanger. Enter hot- and cold-fluid flow rates, temperatures, and thermophysical properties to calculate heat duty, LMTD, correction factor, tube-side and shell-side Reynolds numbers, heat-transfer coefficients, overall heat-transfer coefficient, required heat-transfer area, and estimated pressure drop.

The calculation uses the LMTD method and preliminary Kern-method shell-side correlations. The results are intended for educational and preliminary process-design evaluation and should be checked against project-specific TEMA requirements, detailed exchanger rating software (e.g., HTRI, HTFS), and applicable mechanical design codes before equipment fabrication.

Design Calculation Flow — 12-Step Method

Step 1
Input Data

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Step 2
Hot Fluid

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Step 3
Cold Fluid

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Step 4
Heat Duty

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Step 5
Tube Side

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Step 6
Shell Side

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Step 7
LMTD & F

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Step 8
HTC & U

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Step 9
Area Calc

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Step 10
U Check

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Step 11
Pressure Drop

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Step 12
Feasibility Check

Step 1: Input Data Collection — Process & Design Parameters

Gather all process data: temperatures, flow rates, design pressure, and exchanger configuration

Process Configuration

Application / Service Type (Overall) Heating (Sensible) Heating with Phase Change Cooling (Sensible) Cooling with Phase Change (Condenser) Subcooling (Sensible + Latent) Exchanger Type (TEMA Classification) BEM - Fixed Tube Sheet BEU - U-Tube AES - Floating Head BKU - Kettle Reboiler Flow Arrangement Counter Flow Parallel Flow Cross Flow Fluid Allocation (Which fluid in tubes?) Cold Fluid in Tubes / Hot Fluid in Shell Hot Fluid in Tubes / Cold Fluid in Shell

Design Conditions

Design Pressure (bar) Design Temperature (°C) Allowable Tube Side Pressure Drop (kPa) Allowable Shell Side Pressure Drop (kPa) Initial U Estimate for Preliminary Sizing (W/m²·°C) Starting estimate only — replaced by calculated U after geometry evaluation. Typical: Water-Water: 800-1500 | Oil-Water: 250-500 | Gas-Water: 50-200

Step 2: Hot Fluid Properties & Allocation

Define hot fluid properties. Leave unknown fields blank for estimation. ⚠ Dashed border = estimated value

Hot Fluid Identification

Hot Fluid Name Hot Side Service Type Sensible Heating/Cooling Phase Change (Boiling/Condensing)

Mass Flow Rate (kg/s) [Leave blank to estimate] Inlet Temperature — T_hot,in (°C) [Leave blank to estimate] Outlet Temperature — T_hot,out (°C) [Leave blank to estimate]

Mass Flow Rate (kg/s) [Leave blank to estimate] Temperature (°C)

Hot Fluid Thermal Properties

Specific Heat Cp (kJ/kg·°C) Density ρ (kg/m³) Dynamic Viscosity μ (Pa·s) Thermal Conductivity k (W/m·K) Latent Heat λ (kJ/kg) — for phase change Fouling Resistance R_f (m²·°C/W)

Hot Side Quick Check: Enter data to verify

Step 3: Cold Fluid Properties & Allocation

Define cold fluid properties. Leave unknown fields blank for estimation. ⚠ Dashed border = estimated value

Cold Fluid Identification

Cold Fluid Name Cold Side Service Type Sensible Heating/Cooling Phase Change (Boiling/Condensing)

Mass Flow Rate (kg/s) [Leave blank to estimate] Inlet Temperature — T_cold,in (°C) [Leave blank to estimate] Outlet Temperature — T_cold,out (°C) [Leave blank to estimate]

Mass Flow Rate (kg/s) [Leave blank to estimate] Temperature (°C)

Cold Fluid Thermal Properties

Specific Heat Cp (kJ/kg·°C) Density ρ (kg/m³) Dynamic Viscosity μ (Pa·s) Thermal Conductivity k (W/m·K) Latent Heat λ (kJ/kg) — for phase change Fouling Resistance R_f (m²·°C/W)

Cold Side Quick Check: Enter data to verify

Energy Balance Verification

Both sides must balance (0.00% error) before proceeding to design calculations

Enter hot and cold fluid data to check energy balance.

Step 4: Heat Duty Calculation — Service-Based Method

Calculate heat duty based on service type after energy balance is confirmed

Complete energy balance verification first, then click "Run Design Calculation".

Step 5: Tube Side Design — Geometry, Velocity & Flow Calculations

Select tube dimensions, calculate number of tubes, velocity, Reynolds number

Tube Geometry

Tube Outer Diameter 12.7 mm (1/2" OD) 15.88 mm (5/8" OD) 19.05 mm (3/4" OD) 25.4 mm (1" OD) 31.75 mm (1-1/4" OD) 38.1 mm (1-1/2" OD) Tube Wall Thickness — BWG Standard 1.24 mm (BWG 18) 1.65 mm (BWG 16) 2.11 mm (BWG 14) 2.77 mm (BWG 12) Tube Length 3.0 m (10 ft) 4.88 m (16 ft) 6.0 m (20 ft) 7.32 m (24 ft) Tube Passes 1 Pass 2 Passes 4 Passes 6 Passes 8 Passes Tube Material Thermal Conductivity (W/m·K) SS: 16 | Carbon Steel: 45 | Copper: 390 | Titanium: 20

Tube Side Results

Complete energy balance and run calculation for tube side results.

Step 6: Shell Side Design — Layout, Diameter & Baffle Configuration

Select tube layout pattern, calculate shell diameter, baffle spacing

Shell & Tube Layout

Tube Layout Pattern Triangular 30° Rotated Triangular 60° Square 90° Rotated Square 45° Tube Pitch (mm) Typically 1.25 × Tube OD Shell Passes 1 Shell Pass 2 Shell Passes 3 Shell Passes 4 Shell Passes 6 Shell Passes 8 Shell Passes Baffle Cut (%) Standard: 20-35% of shell diameter

Shell Side Results

Complete energy balance and run calculation for shell side results.

Step 7: LMTD Calculation & Correction Factor

Calculate Log Mean Temperature Difference and apply correction factor

Step 8: Heat Transfer Coefficients — h_i, h_o, and Overall U

Calculate tube-side and shell-side heat transfer coefficients

Step 9: Heat Transfer Area Calculation

Calculate required area using Q = U × A × ΔT_m

Step 10: Overall U Check — Clean vs Dirty Comparison

Compare initial U estimate with calculated U

Step 11: Pressure Drop Calculations — Tube Side & Shell Side

Calculate pressure drops using Kern method

Tube Side ΔP:
ΔP_t = [(4fLN_p/d_i) + 4N_p] × (ρv²/2)   [Pa]

Shell Side ΔP (Kern Method):
ΔP_s = f × G_s² × D_s(N_b+1) / (2ρD_e)   [Pa]

Step 12: Design Feasibility & Optimization Check

Verify all constraints, provide optimization recommendations

Preliminary Thermal Design Summary

What Does This Heat Exchanger Calculator Calculate?

• Heat duty and energy balance verification
• Log Mean Temperature Difference (LMTD) and correction factor (F)
• Tube-side velocity, Reynolds number, Prandtl number, and heat-transfer coefficient
• Shell-side Reynolds number, Prandtl number, and heat-transfer coefficient
• Overall heat-transfer coefficient (clean and dirty, outside area basis)
• Required heat-transfer area and preliminary tube count
• Bundle diameter and shell inside diameter
• Baffle spacing and number of baffles
• Tube-side and shell-side pressure drop estimates

How to Use the Shell & Tube Heat Exchanger Design Calculator

1. Verify Energy Balance: Enter hot and cold fluid flow rates and temperatures. Click "Verify Energy Balance" or "Auto-Estimate" to ensure a 0% error.
2. Select Configuration: Choose the exchanger type, flow arrangement, and which fluid goes in the tubes.
3. Input Properties: Enter the specific heat, density, viscosity, thermal conductivity, and fouling factors for both fluids.
4. Define Geometry: Select tube OD, wall thickness, length, passes, layout pattern, and pitch.
5. Run Calculation: Click "Run Complete 12-Step Design Calculation" to generate the thermal design results.
6. Review Feasibility: Check the "Design Feasibility & Optimization Check" for warnings about velocity, pressure drop, or area margins.
7. Iterate if Needed: If the design is undersized or pressure drops exceed limits, adjust tube count, passes, or baffle spacing and recalculate.

Calculation Method and Assumptions

• Thermal Method: Log Mean Temperature Difference (LMTD) with correction factor for multi-pass arrangements.
• Tube-side Correlation: Sieder-Tate for laminar flow (Re < 2100), Gnielinski for transition (2100 ≤ Re ≤ 4000), and Dittus-Boelter for turbulent flow (Re > 4000).
• Shell-side Correlation: Kern method for cross-flow over tube bundles. Note: For Re_s < 2100, this is a preliminary approximation only — the Kern correlation is validated primarily in the turbulent regime (Re_s > 2000).
• Geometry: Geometric bundle diameter calculation based on tube count, pitch, and layout pattern, plus standard TEMA clearance for shell ID.
• Overall U: Calculated on the outside tube area basis (U_o), including diameter-ratio scaling of inside resistance, tube wall resistance, and fouling factors.
• Pressure Drop: Standard Kern method for shell-side; combined frictional and return bend losses for tube-side.

Limitations of the Calculator

This tool provides preliminary thermal sizing only. It does not replace detailed engineering design. The following are outside the scope of this calculator:

• Detailed exchanger rating (e.g., HTRI, HTFS) with Bell-Delaware stream analysis and vibration checks.
• TEMA mechanical design, tube-sheet thickness, and ligament efficiency calculations.
• ASME Section VIII pressure vessel code calculations (MAWP, corrosion allowance, nozzle reinforcement).
• Thermal expansion analysis and floating head/bellows design.
• Fouling progression over time and detailed cleaning cycle planning.
• Shell-side pressure drop at low Reynolds numbers (Re_s < 2100) — results are preliminary estimates only.

Always verify preliminary results with project-specific requirements and certified mechanical design software before equipment fabrication.

Core Design Equations Reference

Heat Duty: Q = m × Cp × ΔT [kW]

LMTD: ΔT_lm = (ΔT₁-ΔT₂)/ln(ΔT₁/ΔT₂) [°C]

Heat Transfer: Q = U_o × A_o × F × ΔT_lm [W]

Reynolds Number: Re = ρvD/μ

Nusselt (Turbulent): Nu = 0.023 × Re^0.8 × Pr^0.4

Overall U (Outside Area Basis):
1/U_o = (d_o/d_i)·(1/h_i + R_fi) + d_o·ln(d_o/d_i)/(2k_w) + R_fo + 1/h_o

Prandtl Number: Pr = Cp×μ/k

Tube Count: N_t = A_o/(π×d_o×L)

Note on U-basis: The overall heat-transfer coefficient U_o is based on the outside tube area. The inside resistance (1/h_i + R_fi) is scaled by the diameter ratio (d_o/d_i) to convert it to the outside-area basis.

Industry Standard References

• Process Heat Transfer — D.Q. Kern (1950)
• Perry's Chemical Engineers' Handbook — 9th Edition
• Unit Operations of Chemical Engineering — McCabe, Smith, Harriott
• Tubular Exchanger Manufacturers Association (TEMA) — 10th Edition
• ASME Boiler & Pressure Vessel Code — Section VIII, Div. 1
• Heat Exchanger Design Handbook — Kuppan (2000)
• API 660 — Shell-and-Tube Heat Exchangers

Shell & Tube Heat Exchanger Design Calculator | Preliminary Thermal Sizing Tool

For Educational & Preliminary Design Purposes — Not a substitute for detailed TEMA/ASME mechanical design

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