Shell & Tube Heat Exchanger Sizing
Thermal Summary
Geometry ()
Performance
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Your preliminary design calls for a - exchanger with - tubes.
Request Engineering ConsultationCalculations use the Kern Method (1950) for preliminary shell and tube heat exchanger sizing. Standard TEMA shell sizes are iterated to find the smallest standard shell meeting the required area. Tube-side heat transfer via Dittus-Boelter (turbulent) or Sieder-Tate (laminar). Shell-side via Kern jH correlations. LMTD correction factor (F) from standard 1-2N analytical formula. Pressure drops via Darcy-Weisbach (tube) and Kern (shell). Front/Rear Head and Shell Type affect TEMA designation only; final mechanical design requires HTRI and ASME VIII verification.
Preliminary sizing only. For professional engineering design, contact Heating Formula.
Shell And Tube Heat Exchanger Sizing Calculator
How to Use the Shell & Tube Heat Exchanger Sizing Calculator
This free online tool performs preliminary thermal sizing of shell and tube heat exchangers using the Kern Method (1950) — the same engineering basis used by process engineers worldwide for conceptual design and equipment budgeting.
Follow the steps below to get your results in under 60 seconds.
Step 1 — Enter Hot Side Conditions
Fill in the Hot Side panel on the left:
| Field | Description | Typical Example |
|---|---|---|
| Fluid | Select the hot process fluid from the dropdown | Water, Thermal Oil, Steam |
| Inlet Temp | Temperature of the hot fluid entering the exchanger | 90 °C |
| Outlet Temp | Required temperature of the hot fluid leaving | 70 °C |
| Flow Rate | Mass flow rate of the hot fluid | 5 kg/s |
| Location | Whether the hot fluid flows through the shell or tubes | Shell Side |
Tip: Corrosive fluids (e.g. sea water) should typically be placed on the tube side so that only the tubes — not the shell — need to be made from expensive alloy.
Step 2 — Enter Cold Side Conditions
Fill in the Cold Side panel on the right:
| Field | Description | Typical Example |
|---|---|---|
| Fluid | Select the cold process fluid | Water, 30% EG-Water |
| Inlet Temp | Temperature of cold fluid entering | 30 °C |
| Outlet Temp | Required temperature of cold fluid leaving | 50 °C |
| Flow Rate | Mass flow rate of the cold fluid | 7 kg/s |
Note: You do not need to enter the cold side location — it is automatically assigned as the opposite of the hot side.
Step 3 — Choose Flow Configuration
The Flow Configuration dropdown beneath the schematic diagram controls how the two streams interact:
| Option | Description | When to Use |
|---|---|---|
| 1-2N Multi-pass | Hot and cold streams make multiple tube passes. An F-factor correction is applied to the LMTD. | Most common. Standard industrial STHE design. |
| Pure Counterflow (1-1) | Single shell pass, single tube pass, streams flow in opposite directions. F = 1.0. | Maximum thermal efficiency per unit area. |
| Co-current / Parallel (1-1) | Streams flow in the same direction. Least efficient. | Specialised cases only (e.g. condensers with close approach temperatures). |
Step 4 — Set Design Parameters
Expand the Design Parameters section and adjust as needed. Default values represent typical carbon steel tubing per TEMA standards.
| Parameter | Default | Description |
|---|---|---|
| Tube OD | 19.05 mm (¾ in) | Outer diameter of individual tubes |
| Tube Wall | 2.11 mm (14 BWG) | Tube wall thickness |
| Tube Length | 6.0 m | Standard available tube lengths: 4, 6, 8 ft or 2, 4, 6 m |
| Pitch Ratio | 1.25 | Ratio of tube pitch to tube OD. Minimum is 1.25 per TEMA. |
| Layout | Triangular (30°) | Triangular gives more tubes per shell. Square (90°) is easier to clean. |
| Tube Passes | 2 | Number of times the tube-side fluid travels the full shell length. More passes = higher velocity but higher pressure drop. |
| Baffle Spacing Ratio | 0.5 | Ratio of baffle spacing to shell diameter. Typical range: 0.2 to 1.0. |
| Assumed Ud | 600 W/m²·K | Initial estimate for the overall heat transfer coefficient. See table below. |
Typical Ud starting values:
| Service | Ud (W/m²·K) |
|---|---|
| Water–Water | 800–1500 |
| Steam–Water | 1000–3000 |
| Oil–Water | 200–500 |
| Gas–Liquid | 50–200 |
| Oil–Oil | 100–400 |
Step 5 — TEMA Designation (Optional)
The TEMA Designation fields (Front Head, Shell Type, Rear Head) allow you to specify the mechanical configuration of the exchanger for procurement purposes. These selections do not affect the thermal calculation — they only generate the TEMA type code shown in the results (e.g. BEM, AEL, CFU).
Step 6 — Click “Calculate Design”
The calculator will:
- Look up fluid properties (Cp, ρ, μ, k, Pr) at the average film temperature
- Compute heat duty Q and LMTD
- Apply the F-factor correction (for 1-2N configuration)
- Iterate through standard TEMA shell sizes to find the smallest standard shell that satisfies the required area
- Rate the selected shell — calculating shell-side and tube-side film coefficients and pressure drops
- Converge on an overall heat transfer coefficient Ud
Results appear below the calculator with full thermal summary, geometry, and performance metrics.
Understanding Your Results
| Result | Description |
|---|---|
| Heat Duty (Q) | Total thermal power transferred, in kW or MW |
| LMTD / F-Factor | Log Mean Temperature Difference and correction factor |
| Required Area | Minimum heat transfer area needed |
| Selected Area (Excess %) | Area of the selected standard shell — always slightly larger than required |
| TEMA Designation | Three-letter code from TEMA standard (e.g. BEM) |
| Tube Count (Nt) | Number of tubes in the bundle |
| Shell Diameter | Internal diameter of the selected standard shell |
| Overall Ud | Fouled overall heat transfer coefficient (W/m²·K) |
| Clean Uc | Clean overall coefficient without fouling allowance |
| Tube ΔP / Shell ΔP | Pressure drops on each side. Typical limit: 35–70 kPa |
Green values are within acceptable engineering limits. Red values indicate the pressure drop exceeds typical allowable limits — consider revising the design (fewer tube passes, larger shell, or higher baffle spacing).
Frequently Asked Questions (FAQ)
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What engineering method does this calculator use?
This calculator uses the Kern Method, introduced by Donald Q. Kern in Process Heat Transfer (1950). It is the industry-standard preliminary sizing method for shell and tube heat exchangers and is suitable for conceptual design, equipment budgeting, and vendor specification. For final mechanical design and detailed rating, use HTRI Xchanger Suite or ASPEN Shell & Tube Exchanger.
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What does “1-2N Multi-pass” mean?
A 1-2N exchanger has 1 shell pass and 2 (or more) tube passes. This is the most common industrial STHE configuration. The hot or cold fluid travels through the tubes multiple times — increasing velocity and heat transfer — but an F-factor correction must be applied to the counterflow LMTD to account for the mixed flow arrangement.
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Why is my pressure drop showing as red?
A pressure drop above 70 kPa typically exceeds what pumps and compressors can provide at reasonable operating cost. To reduce pressure drop, try:
Reducing the number of tube passes
Increasing the baffle spacing ratio (e.g. from 0.5 to 0.7)
Selecting a larger tube OD or fewer tubes per pass
Adding a second shell in parallel -
What is the difference between Uc and Ud?
Uc (Clean overall coefficient) is calculated from the shell-side and tube-side film coefficients and the wall resistance only. This represents a brand-new, perfectly clean exchanger.
Ud (Dirty/Design coefficient) adds fouling resistances to both sides. This is the value you must use for sizing, because real exchangers accumulate scale, biofilm, and corrosion products over time. -
What is the TEMA designation (e.g. BEM, AEL)?
The TEMA designation is a three-letter code describing the mechanical configuration of the heat exchanger:
First letter — Front end (stationary head) type: A, B, C, N
Second letter — Shell type: E (most common), F, G, H, J, K, X
Third letter — Rear end (floating/fixed) type: L, M, N, P, S, T, U, W
For example, BEM = Bonnet front head + Single-pass E shell + Fixed M rear head. -
How accurate is this calculator?
This tool provides ±20–30% accuracy suitable for:
Feasibility studies and CAPEX estimates
Writing equipment data sheets for vendor RFQ
Checking vendor-quoted exchanger sizes
For detailed design (within ±5%), contact our engineering team for an HTRI-verified design. -
Why does the calculator always select a standard shell size?
Real shell and tube heat exchangers are built from standard pipe (for shells up to 24″) or rolled plate (larger shells). Manufacturers use fixed shell sizes: 6″, 8″, 10″, 12″, 14″, 16″, 18″, 20″, 24″, 30″, 36″, 42″, 48″, 60″. This calculator follows TEMA practice by selecting the smallest standard shell that provides at least the required heat transfer area — just like vendor sizing software does.
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Can I use this for steam condensers or reboilers?
Yes, with care. For steam condensers, set the hot fluid to “Saturated Steam” and leave the outlet temperature equal to or very close to the inlet (isothermal condensation). For kettle reboilers (TEMA K shell), the Kern method is less accurate due to nucleate boiling — please contact us for a detailed thermal design.
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What fluids are supported?
The current version includes: Water, Saturated Steam, Light Mineral Oil, Air (dry), 30% Ethylene Glycol-Water, Thermal Oil (Dowtherm A), Ethanol (95%), Propylene Glycol (50%), Sea Water, and Ammonia (Liquid). Properties are interpolated from published engineering data tables.
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Is this calculator free?
Yes — completely free for preliminary sizing. For detailed, HTRI-verified designs with mechanical drawings and ASME compliance review, contact our engineering team.