FINS AND TUBES HEAT EXCHANGER
The BOIXAC fins and tubes heat exchanger is designed to maximise heat transfer between air or process gases and a high-conductivity thermal fluid such as water, water-glycol mixtures, steam, thermal oil or diathermic fluids.
The continuous fin increases the air-side exchange surface, typically the limiting side, improving the overall heat-transfer coefficient and reducing the required exchanger size.
Mechanical tube expansion ensures perfect contact between tubes and fins, guaranteeing high thermal efficiency and mechanical stability.
Design of finned-tube heat exchangers
At BOIXAC we develop custom finned-tube heat exchangers according to process needs and fluid characteristics. Our design combines advanced thermal calculation, materials selection and maintainability criteria to ensure performance and durability.
Key design decisions:
- Tube selection: diameter, thickness and material according to pressure, chemical compatibility and corrosion risk (carbon steel, stainless steel AISI 304, AISI 316, copper, titanium, special alloys).
- Fin material and spacing: aluminium, pre-coated aluminium, hydrophilic, hydrophobic, galvanised steel, stainless steel AISI 304 and AISI 316, copper and titanium; spacing optimised for fouling, freezing and condensation/evaporation regimes.
- Bundle geometry: staggered (higher turbulence and U-value) vs. inline/grid (lower pressure drop and easier cleaning).
- Headers and fluid boxes: sized according to the fluid (water, oil, steam, …) and operating pressure.
- Protections and treatments: internationally referenced coatings (Blygold, Heresite, Electrofin or Aqua Aero).
All BOIXAC heat exchangers comply with the European Pressure Equipment Directive 2014/68/EU, ensuring safety and quality. Also available in ASME.
Technical configuration of tube bundle
Tube arrangement and fin pattern determine performance, pressure drop and maintainability.
Staggered arrangement
Increases turbulence and the overall heat-transfer coefficient (U); recommended for high heat-duty processes (combustion air preheat, recuperators, furnaces). Advantage: more heat transfer per unit area; drawback: higher pressure drop.
| Tubes Material | Cu, Cu,Ni, Fe, AISI 304, AISI 316, Titanium |
|---|
| Fins Material | Al, AlMg2.5m, AlEpoxy, AlHy, Cu, AISI 304, AISI 316 |
| Observations | Fins pitch from 1.6 to 6.0 mm and fins thickness from 0.11 to 0.23 mm |
| Tubes Material | Cu, CuNi, Fe, AISI 304, AISI 316, Titanium |
|---|
| Fins Material | Al, AlMg2.5m, AlEpoxy, AlHy, Cu, AISI 304, AISI 316 |
| Observations | Fins pitch from 1.6 to 6.0 mm and fins thickness from 0.11 to 0.23 mm |
| Tubes Material | Cu, CuNi |
|---|
| Fins Material | Al, AlMg2.5m, Epoxy, Cu, AISI 304, AISI 316 |
| Observations | Fins pitch from 1.6 to 6.0 mm and fins thickness from 0.11 to 0.23 mm |
Inline / grid / square arrangement
Provides lower pressure drop and easier cleaning; recommended for environments with moderate dust.
| Tubes Material | Cu, CuNi |
|---|
| Fins Material | Al, AlMg2.5m, AlEpoxy, AlHy, Cu, AISI 304, AISI 316 |
| Observations | Fins pitch from 1.6 to 8.0 mm and fins thickness from 0.11 to 0.23 mm |
Options and alternatives to finned exchangers
Each project has an optimal solution in terms of efficiency and operability. For instance, if the application presents a high risk of particle deposition (severe fouling) or abrasive particles, consider alternatives to continuous fins such as:
- Helical finned tubes: increased turbulence and heat transfer.
- Smooth tubes (no fins): high mechanical strength and resistance to fouling.
- Pillow plate: high robustness, low fouling sensitivity, and high performance.
Additionally, we can include numerous options such as; fans, droplet separators, humidifiers, electric defrost heaters, automatic cleaning systems, thermal insulation or pressurised shell.
Typical ROI
3-12 months
Efficiency
up to 90%
Warranty
2 years
Welding
up to 70% less
When are continuous fins appropriate and when are they not?
Continuous fins are appropriate when:
- The fluid side (liquid or steam) has high conductivity and air is the limiting side.
- Maximum surface per volume is required (space-restricted installations).
- The process allows periodic maintenance and accessible cleaning.
They are not recommended when:
Air/gas contains abrasive particles or a high concentration of fine dust causing severe fouling and fin blockage; continuous fins require complex cleaning and are not always robust against abrasion. In such cases, the optimal solution may be helical fins, smooth-tube exchangers or pillow plate exchangers.
Typical applications
Continuous fin-and-tube heat exchangers, custom-built for new projects or replacements, can be implemented in hundreds of applications. The main ones are grouped into:
- Industrial air and gas treatment.
- Water treatment and refrigeration systems.
- HVAC; air handling units (AHU/CTA).
Data required for sizing an air-to-fluid finned coil
At BOIXAC we analyse multiple factors such as available space and operating conditions. From these we size and propose the optimal solution. The data required for the study include:
To size the water exchanger coil we need you to confirm 5 of the following values as well as the maximum available dimensions.
– Calorific capacity (kcal/h or kW)
– Air flow (m3/h)
– Air inlet temperature (ºC) and relative humidity (%)*
– Air outlet temperature (ºC) and relative humidity (%)
– Water flow (l/h or l/min.)
– Water inlet temperature (ºC)*
– Water outlet temperature (ºC)
– Maximum available sizes (length x height x depth)
To size the condenser we will need you to confirm 5 of the following values as well as the maximum available dimensions.
– Calorific capacity (kcal/h or kW)
– Air flow (m3/h)*
– Air inlet temperature (ºC)*
– Air outlet temperature (ºC)
– Refrigerant*
– Condensation temperature (ºC)*
– Maximum available sizes (length x height x depth)
To size the evaporator we will need you to confirm 5 of the following values as well as the maximum available dimensions.
– Calorific capacity (kcal/h or kW)
– Air flow (m3/h) *
– Air inlet temperature (ºC) and relative humidity (%)
– Air outlet temperature (ºC) and relative humidity (%)
– Refrigerant *
– Evaporation temperature (ºC) *
– Maximum available dimensions (length x height x depth)
To size the steam battery we will need you to confirm 4 of the following values as well as the maximum available dimensions.
– Calorific capacity (kcal/h or kW)
– Air flow (m3/h)
– Air inlet temperature (ºC)
– Air outlet temperature (ºC)
– Steam pressure (Kg/cm2 atm. or bar)*
– Maximum available dimensions (length x height x depth)
What is a diathermic fluid?
A diathermic fluid is a thermal fluid specifically formulated for heat transfer at medium to high temperatures (150–350 ºC or higher), with high thermal stability and without requiring high pressures.
They are used in closed circuits for industrial heating, reactors, furnaces, thermofluids and continuous thermal processes. Typical commercial examples include synthetic thermal oils, mineral heat transfer oils or glycol-based fluids specialised for high temperatures.
Why choose BOIXAC?
With extensive experience in finned-tube heat exchanger design, we hold excellent references in sectors such as food, metallurgy, oil & gas, pulp & paper, plastics and chemicals.
Our design is based on advanced thermal calculations and accurate sizing, combined with high-quality materials, advanced manufacturing processes and a close client approach that allows us to understand each project’s needs. This enables us to propose the best technical, efficient and customised solution for each client.
Finned tubes heat exchanger
Smooth tubes heat exchanger
Dimple plate heat exchanger