Finned Tube Evaporator|Finned Tube Evaporator Coil

Products Description

Finned Tube Evaporator & Evaporator Coil

Custom-built finned tube evaporators and evaporator coils for refrigeration, HVAC, chemical, petrochemical, and power applications. Tube diameter, fin pitch, circuiting, materials, and design code are configured to the process datasheet — not forced into a catalogue size.

Tube OD 12.7 – 38.1 mm Fin pitch 4 – 12 FPI ASME / TEMA / EN 13445 / API 660 Carbon steel · SS · Cu · CuNi · Ti Hydro & helium leak tested

What Is a Finned Tube Evaporator?

A finned tube evaporator is a heat exchanger in which a refrigerant or process fluid evaporates inside tubes while the extended fin surface on the outside absorbs heat from air, water, or another process stream.

The finned surface compensates for the low heat-transfer coefficient on the gas or air side. By extending the effective area — typically 8 to 20 times the bare tube area — a finned tube evaporator achieves a compact footprint at far lower material cost than an equivalent bare-tube bundle. Depending on the service, the unit may be a shell-and-tube evaporator with finned tubes, an air-cooled evaporator coil, or a flooded or dry-expansion coil in a refrigeration or process duty.

Finned tube evaporator with helically wound fins on a bare tube bundle — Typical finned tube evaporator bundle with helically wound fins on the process tubes.

What Is a Finned Tube Evaporator Coil?

A finned tube evaporator coil is the coil assembly — tubes, fins, return bends, headers, and refrigerant distributor — through which refrigerant evaporates while air or a secondary fluid is cooled across the finned face.

In most HVAC and refrigeration systems the coil is the component that actually absorbs heat from the conditioned space or process stream. The coil is defined by its face area, number of tube rows, fin pitch, circuiting, and refrigerant distribution. Those four parameters, more than tube material alone, determine capacity, air-side pressure drop, and defrost behaviour.

Coil Construction — What Determines Performance

Tube & Fin Bond

Mechanical expansion, hydraulic expansion, or tension winding bonds the fin to the tube. A consistent bond limits contact resistance and keeps capacity stable through thermal cycling.

Circuiting & Refrigerant Distribution

Circuit count and distributor selection control refrigerant velocity, pressure drop, and feed balance. Poor circuiting causes uneven frost, hot spots, and capacity loss.

Face Area & Row Depth

Face area sets the face velocity; row depth sets the air-side contact time. Deep coils raise capacity but increase air-side pressure drop and fan power.

Fin Pitch

Denser fins add surface but trap frost and dust. Wider pitches are standard for low-temperature, frosted, or particulate-laden duty.

Headers & Return Bends

Brazed or welded headers, with brazed or welded U-bends, are selected to suit the refrigerant, pressure rating, and site repair capability.

Coil Casing

Galvanised, stainless, or coated steel casings with drain pans and lifting points, sized to fit the air handling unit or cooler enclosure.

Common Evaporator Coil Configurations

Coil Type	Typical Tube / Fin Material	Typical Service
Copper tube / aluminium fin	Copper tube, aluminium fin	General HVAC, commercial refrigeration, chillers
Aluminium tube / aluminium fin	All-aluminium	Lightweight coils, ammonia and CO₂ systems where compatible
Copper tube / copper fin	Copper tube, copper fin	Corrosive atmospheres, marine and coastal installations
Stainless steel tube / SS fin	SS 304 / 316L	Food, pharmaceutical, hygienic and wash-down areas
Cupronickel or titanium tube	CuNi 90/10, 70/30, titanium	Brine, seawater, high-chloride duty
Carbon steel tube / CS or SS fin	SA179, SA192, SS fins	Process and refinery evaporator service

Refrigerants and Operating Envelope

Common refrigerants: R-410A, R-32, R-134a, R-404A, R-407C, R-513A, R-744 (CO₂), R-717 (ammonia), and R-290 where local regulations permit.
Refrigerant charge: dry-expansion, flooded, and pumped-recirculation circuits are each available depending on system architecture.
Defrost method: hot-gas, electric, or off-cycle defrost — coil fin pitch and circuit layout are adjusted to suit the chosen method.
Ambient and process temperature: the coil is rated for the actual entering air or fluid condition, not a nominal catalogue point.

Selection tip: frost forms fastest at the coil face nearest the entering air. If the application runs below roughly 0 °C coil surface temperature, specify a wider fin pitch and confirm the defrost strategy before the coil is built.

Core Advantages of Our Finned Tube Evaporators and Coils

Higher surface-to-volume ratio. Extended fin area increases heat transfer per unit of bundle or coil volume, allowing a smaller, lighter exchanger for the same duty.
Optimised fin-to-tube bond. Helically wound, tension-wound, extruded, or expanded constructions maintain consistent contact pressure and limit contact resistance over thermal cycling.
Independent material pairing. Tube and fin materials are selected separately so the wetted side meets corrosion and code requirements while the fin side stays cost-efficient.
Custom geometry and circuiting. Tube diameter, fin height, fin pitch, tube length, rows, circuits, and pass arrangement are configured to the duty.
Serviceability. Removable bundles, accessible headers, and generous cleaning lanes where fouling is expected.
Documentation for project procurement. Material traceability, inspection hold points, and test reports arranged to the purchase specification.

Technical Specifications

The table below shows typical ranges. Final values are confirmed against the process datasheet, the applicable design code, and the mechanical design calculation for each unit.

Parameter	Typical Range / Options
Tube outside diameter	12.7 mm to 38.1 mm (0.5 in to 1.5 in)
Tube wall thickness	0.9 mm to 3.0 mm, depending on pressure and corrosion allowance
Tube length	Up to approximately 12 m, subject to shipping and handling limits
Fin height	6 mm to 20 mm
Fin pitch	4 to 12 fins per inch (approx. 157 to 472 fins per metre); 6 to 14 FPI available for coil duty
Fin thickness	0.3 mm to 1.2 mm
Fin type	Helically wound (L-foot, KL, overlap), tension wound, extruded, embedded, or plate-fin
Coil rows	2 to 12 rows, typical range
Coil face velocity	Typically 1.5 to 3.5 m/s, confirmed against allowable carry-over and pressure drop
Tube side design pressure	Typically up to 10 MPa, depending on material, wall thickness, and code
Design temperature	Approximately −60 °C to +400 °C, limited by the selected materials and joint design
Design codes	ASME BPVC Section VIII Div. 1, TEMA, API 660, EN 13445, PED 2014/68/EU, GB/T 151 — as specified
Connection types	Flanged, welded, threaded, brazed, or grooved per project specification
Surface finish	As-welded, pickled and passivated, painted, or coated on request

Note: The values above are indicative engineering ranges, not a guarantee of performance. Each evaporator and coil is thermally rated and mechanically designed to the actual project conditions.

Materials and Standards

Tube materials

Carbon steel (e.g. SA179, SA192, SA106)
Stainless steel (304/304L, 316/316L, 321, duplex and super duplex grades)
Copper and copper alloys (copper, admiralty brass, 90/10 and 70/30 cupronickel)
Titanium and nickel alloys for aggressive or high-chloride services

Fin materials

Aluminium and aluminium alloys for air-side duty
Copper for high-conductivity refrigeration coils
Stainless steel or carbon steel for high-temperature or corrosive environments

Applicable standards

Mechanical design: ASME BPVC VIII-1, EN 13445, GB/T 151
Heat exchanger practice: TEMA class R, C, or B; API 660 for shell-and-tube refinery service
Welding and brazing: ASME Section IX, EN ISO 9606, with WPS/PQR documentation
Non-destructive examination: RT, UT, PT, MT, and helium or hydrostatic leak testing as agreed

Application Industries

Oil & Gas

Gas processing, dew-point control, stabiliser reboilers, and low-temperature separation trains.

Chemical & Petrochemical

Distillation reboilers, concentrators, process chillers, and solvent recovery.

Power Generation

Condenser air removal, flue gas cooling, and auxiliary cooling circuits.

HVAC & Refrigeration

Air-handling unit coils, flooded chillers, cold rooms, blast freezers, and industrial refrigeration.

Food & Beverage

Brine chilling, hygienic process cooling, and controlled-temperature evaporation.

Pharmaceutical

Solvent recovery, clean-room cooling, and controlled evaporation duty.

Desalination & Water

Brine and vapour-side duty in thermal processes and water treatment.

Marine & Offshore

Corrosion-resistant coils for coastal, offshore, and shipboard installations.

How to Select a Finned Tube Evaporator or Evaporator Coil

Selection starts with the duty, not the geometry: define the heat load, the temperature programme, the flow rates, and the allowable pressure drop first, then size the surface and choose the fin configuration.

Define the duty. Heat load (kW), inlet and outlet temperatures, mass or volumetric flow on both sides, and the phase change expected on the evaporating side.
Fix the allowable pressure drop. Tube-side and air-side limits determine the number of passes, circuit count, and the fin pitch that can be tolerated.
Choose tube and fin materials. Match the wetted material to the fluid chemistry and corrosion allowance; match the fin material to the external environment.
Select the fin configuration. Denser fins add surface area but accelerate fouling and raise air-side pressure drop. For particulate-laden or frosting streams, a wider pitch is usually the better commercial choice.
Set the circuiting. Confirm refrigerant velocity, feed balance, and oil return, particularly for dry-expansion coils and low-temperature duty.
Check the mechanical design. Verify tube wall thickness against design pressure, and confirm thermal expansion and tube-to-tubesheet or header joint design.
Plan for cleaning and defrost. Decide between chemical cleaning, high-pressure water, or mechanical cleaning, and confirm the defrost method and access paths before the layout is frozen.
Confirm the code and documentation package. Agree on inspection hold points, material certificates, and test reports before fabrication begins.

Fin Type Comparison

Fin Type	Typical Use	Considerations
Helically wound L-foot	Air-side heating and cooling at moderate temperature	Good contact at moderate temperatures; not suited to severe thermal cycling
KL / overlap wound	Higher-temperature air-side duty	Better fin retention under expansion; slightly higher cost
Extruded	Corrosive or high-vibration service	Fin is integral with the tube surface; limited to compatible tube materials
Embedded / grooved	High-temperature and high-cycling duty	Strong mechanical bond; requires thicker tube wall at the groove
Plate fin / expanded coil	HVAC and refrigeration coil assemblies	High surface density; requires consistent expansion for bond quality

Evaporator vs. Condenser Coil — Quick Reference

Characteristic	Evaporator Coil	Condenser Coil
Heat flow	Absorbs heat from the process stream	Rejects heat to the ambient or cooling medium
Refrigerant state change	Liquid to vapour	Vapour to liquid
Moisture behaviour	Condensate forms; drain pan required	Generally dry operation
Frost risk	Yes, below roughly 0 °C coil surface	No
Typical fin pitch	6 to 12 FPI, wider for low temperature	10 to 14 FPI
Cleaning access	Critical — fouling and bio-film risk	Important, mainly dust and debris

Quality Control and Inspection

Incoming material verification against mill certificates, with heat-number traceability where required.
Dimensional inspection of tube diameter, wall thickness, fin height, fin pitch, row depth, and bundle or coil length.
Welder and brazer qualification with WPS/PQR documentation to ASME Section IX or EN ISO 9606.
Non-destructive examination — radiographic, ultrasonic, dye penetrant, and magnetic particle — applied per the agreed inspection plan.
Hydrostatic or pneumatic pressure testing, with helium leak testing available for high-integrity duty.
Fin-to-tube contact and bond inspection on sampled tubes.
Final documentation package: material certificates, test reports, NDT records, and as-built drawings.

Third-party inspection by a nominated agency can be arranged at defined hold points when the project specification requires it.

Packaging and Shipping

Tube ends and connection faces protected with caps and gaskets; all openings sealed against moisture and dust.
Bundles and coils braced inside a steel or timber cradle to prevent movement during road, rail, and sea transport.
Fin packs protected with edge boards; exposed fins shielded where handling risk is high.
Moisture barrier with desiccant for long sea voyages, with desiccant quantity matched to voyage duration.
Weather-resistant marking, packing list, and shipping documents fixed to the exterior of each package.
Lifting points and centre-of-gravity marked on the crate; lifting instructions supplied with the shipping documents.
Export packing to seaworthy standard, or to a client-specified packing specification where provided.

Frequently Asked Questions

What is the difference between a finned tube evaporator and a bare tube evaporator?

A finned tube evaporator carries extended surface on the outside of the tubes, so it delivers the same heat duty with fewer tubes and a smaller shell or casing. Bare tube units are simpler to clean and are often preferred for heavily fouling or high-temperature service.

What is a finned tube evaporator coil used for?

It is the coil that absorbs heat in an air-handling unit, chiller, cold room, blast freezer, or industrial refrigeration system. Refrigerant evaporates inside the tubes while air or a secondary fluid is cooled as it passes across the finned face.

How do I choose the right fin pitch?

Select the widest fin pitch that still meets the thermal duty. Dense fins raise the surface area but increase air-side pressure drop and make cleaning harder. For dust-laden, frosting, or fouling streams, a wider pitch is usually the more economical long-term choice.

How many coil rows do I need?

Row depth is set by the required capacity and the allowable air-side pressure drop. Adding rows increases capacity but also fan power and coil depth. For most comfort-cooling coils the practical range is 2 to 8 rows; deeper coils are used where the duty demands it.

Which materials are suitable for corrosive duty?

For chloride-bearing or acidic streams, stainless steel, duplex, titanium, or cupronickel tubes are common selections. The fin material is chosen separately because it contacts a different medium. Final selection depends on the fluid analysis, temperature, and required corrosion allowance.

What defrost method should be used for low-temperature coils?

Hot-gas defrost is common in industrial refrigeration; electric defrost is used where hot gas is unavailable. Off-cycle defrost suits light frosting duty. Fin pitch and circuit layout are adjusted to suit the chosen method.

Can the evaporator be designed to a specific code?

Yes. Units can be mechanically designed to ASME BPVC Section VIII Div. 1, EN 13445, PED 2014/68/EU, GB/T 151, TEMA, or API 660 as specified. Please state the design code, design pressure and temperature, and the required documentation package in your enquiry.

What information is needed to prepare a quotation?

Provide the heat load, both-side flow rates, inlet and outlet temperatures, allowable pressure drops, fluid or refrigerant type, design pressure and temperature, design code, connection sizes, and any space or weight limits. Drawings of the available envelope help shorten the review cycle.

What is the typical lead time?

Lead time depends on material availability, bundle or coil size, and the extent of third-party inspection. A firm schedule is confirmed after the technical review and material release.

Do you provide replacement finned tube bundles and coils?

Yes. Replacement bundles and coils can be manufactured to the original drawing or to reverse-engineered dimensions when drawings are not available.

Request a Finned Tube Evaporator or Coil Quotation

Send us your process datasheet — heat load, temperatures, flow rates, allowable pressure drop, refrigerant or fluid, materials, and design code — and our engineering team will review the thermal and mechanical design and return a technical proposal with a firm quotation.

Please include the design pressure and temperature, fluid composition, defrost or cleaning requirements, and any inspection or documentation requirements so that the offer reflects the full scope of supply.

Send Your Enquiry