Microchannel Coils



    Microchannel heat exchanger


We manufacture innovative, next-generation aluminium microchannel heat exchangers that provide high heat transfer performance, excellent flexibility, lower internal volume, and smaller size and weight: features and capabilities not found in traditional finned tube heat exchangers.

Microchannel technology offers improved performance by increasing air-side heat transfer between fins and ambient air, heat conduction between fins and flat tubes, and refrigerant-side heat transfer between tubes and refrigerant resulting in 20 to 40 percent higher overall performance compared to finned tube designs.

Importantly, our microchannel heat exchangers perfectly match any application, be it condenser coil, evaporator, water coil, or coil for use in heat pumps – owing to innovative design based on extensive research and development.


Microchannel coils present significant advantages over traditional finned tube coil design in every respect, including heat transfer efficiency, operating reliability, environmental safety, measurements, and cost:

  • 20% to 40% higher heat transfer performance
  • Lower airside pressure drops
  • 10% to 30% smaller coil face upon design conditions
  • Up to 60% less weight
  • Higher corrosion resistance
  • Robust construction
  • Less refrigerant charge – up to 60%
  • Optimized raw material cost
Microchannel air-to-water coil


Microchannel coil is all-aluminum, integrally brazed in a controlled-atmosphere brazing (CAB) furnace; the coil assembly includes the following elements:

  1. Flat, multi-port microchannel tubes and fin strips
  2. Refrigerant inlet manifold
  3. Refrigerant outlet manifold
  4. Refrigerant connections
  5. Reinforcement frame
  6. Mountings

Design Highlights


The coil design incorporates flat microchannel tubes and fins strips, brazed integrally, and resulting in high heat transfer performance. Depending on the application, tubes can be oriented horizontally or vertically to ensure predictable heat exchanger performance. State-of-the-art fin design, louvered or flat, provides low airside pressure drops and high heat transfer, as well as easier water condensate shedding due to using capillary forces and gravity to pull condensate off the coil.


For evaporator and heat pump coils, an inbuilt DX distributor helps to evenly spread the incoming refrigerant across the width of the coil. This provides assured coil performance and efficient part-load operation. DX distributor eliminates the need for an external distributor with complex piping.

Outlet manifold of condenser coils serves as a mini-receiver, which accumulates and holds the liquid refrigerant, helps to reduce critical refrigerant charge issues, and provides easy system charging. The lower header has an internal outlet baffle, which prevents gaseous refrigerant from leaving the condenser.


Microchannel coils are available with different types of connections, and with custom orientations. The special plastic/rubber inserts prevent the contact of aluminium and dissimilar metals to avoid galvanic corrosion.


The coil itself is a robust frame that provides airtight flush mounting, thereby eliminating unnecessary framing components while preventing air bypass.


Condenser coils can be designed for horizontal or vertical refrigerant flow, in single- or multi-pass configuration for exacting performance.

Condenser coils can be configured in small dimensional increments in height and width, up to as large as 6000x2000mm.

Coil models with design working pressures of 32 bar or 45 bar are available for the full range of refrigerants, including environmental-safe low-GWP mixtures and natural refrigerants.


Direct expansion evaporator coils are based on innovations in refrigerant flow distribution, combined with a water-shedding design with a vertical tube arrangement.

Coils are fit for evaporator and heat pump applications with sizes up to 6000x2000mm and design working pressures at 20 bar, 32 bar, and 45 bar.

Coils are suitable for use with HFC- and lower GWP HFO-based refrigerants, as well as for natural refrigerants.

DX distributor

Refrigerant Distributor: How It Works

The primary function of the DX distributor integrated into the inlet manifold of the evaporator coil is uniform refrigerant spreading across the length of the coil, over a wide range of operating conditions and equipment designs. The distributor provides:

  1. Liquid/gas separation of the mixture delivered to the distributor
  2. Injection of liquid refrigerant into distributor orifices and creation of pressure drop to propel the refrigerant and to spread out the liquid substantially evenly along the length of the inlet manifold
  3. Injection of liquid refrigerant into the tube chambers
  4. Prevention of refrigerant flow between refrigerant tube chambers before entering the microchannel tube ports


For water, glycols, and special fluids, we offer microchannel coils that perfectly fit cooling, heating, and general-purpose applications.

Microchannel water coils feature large-diameter manifolds for best performance and increased tube wall thickness to ensure reliable operation and long lifespan.

Water coils are available up to 6000mm wide and 2000mm tall, rated for up to 20 bar.


The corrosion potential of the all-aluminium microchannel coils is significantly lower than in multi-metal coils as there are no dissimilar metals to initiate galvanic corrosion. This makes microchannel coils an inherently better solution for seashore installations, installations in polluted areas, or any application where corrosion may be a concern.

Microchannel coils require only one braze operation in the controlled environment, significantly reducing the likelihood of leaks when compared to manually brazed heat exchangers.

The advanced technology, accurate material selection, and use of modern braze furnaces guarantees the highest quality of our products, which is confirmed by both SWAAT tests and field experience.

Seawater Acetic Acid Test

SWAAT test is used to determine the resistance to corrosion of aluminum alloys when exposed to a changing climate of acidified synthetic seawater spray, followed by high humidity and elevated temperature. The test is also applied to determine how varying surface treatments affect corrosion behavior.

In accordance with ASTM G-85 Annex A3 (SWAAT), a test specimen is placed in a chamber and exposed to a changing atmosphere that comprises the repeating cycle at a constant chamber temperature of 49°C:

  • 30 minutes exposure to a continuous indirect spray of acidified (pH 2.8 to 3.0) synthetic seawater solution, which falls-out on to the specimens at a rate of 1.0 to 2.0 ml/80cm²/hour
  • 90 minutes of exposure to high humidity (98%) air​

Numerous corrosion resistance tests demonstrate that performance of microchannel coil drops significantly slower compared to the results for traditional finned tube coil.

SWAAT results: microchannel coils vs finned tube coils


While all-aluminum microchannel coils are not subject to galvanic corrosion as traditional multi-metal finned tube coils, some installations may require the highest level of protection. For ensured long service life in petrochemical installations, adiabatic systems, installations in highly polluted areas or maritime atmospheres, we recommend using microchannel heat exchangers with electrocoating protection.

E-coating offers ultimate corrosion and chemical resistance, provides excellent salt spray and humidity resistance, and exhibits outstanding performance over uncoated aluminium.

As electrocoats are very susceptible to sunlight that may break down the coating causing it to fail, Kaltra offers a UV-protective topcoat as standard.

Selection software


Microchannel coil selection software includes condenser, evaporator, heat pump, and water coils, making it a complete selection and calculation tool for refrigeration professionals.

The software provides selections and ratings for microchannel heat exchangers which enables the user to select the best-suited product based on several deciding parameters such as heat exchanger application, cooling capacity, refrigerant, evaporation and condensation temperatures, airflow and air temperature and other critical variables in refrigeration systems.

Microchannel heat exchanger brazing

Kaltra breaks new ground with microchannel coils for A2L refrigerants

Kaltra expands its line of microchannel heat exchangers for A2L refrigerants, including R290 propane, with higher performance designs.
MCHE made from AA 3F05

Kaltra deploys new aluminum alloy for microchannel heat exchangers

The new aluminum alloy AA3F05 boosts the corrosion resistance of Kaltra's microchannel heat exchangers.
MCHE assembly

Superhydrophobic microchannel heat exchanger for heat pump performance enhancement

Superhydrophobic coating delays frost formation and makes microchannel heat exchangers a beneficial choice for outdoor evaporators in heat pump systems.
Controlled-atmosphere brazing furnace

MCHE brazing process in detail

Brazing of microchannel heat exchangers: detailed description of state-of-the-art process practiced by Kaltra.
MCHE factory machinery

Kaltra improves delivery time for heat exchangers

Facility expansion has been successfully completed by Kaltra, reducing manufacturing time and expanding production capacity for microchannel heat exchangers (MCHE).
MCHE replacement coils for York chillers

Kaltra supplied replacement coils for large chiller installation in Florida, USA

With careful material selection, thorough production technology compliance and proper anti-corrosion treatments, microchannel coils by Kaltra guarantee long lifespan - even in high-corrosivity areas.
Controlled-atmosphere brazing furnace

Two more CAB furnaces for MCHE brazing are to be installed in Q1 2023

Kaltra expands MCHE manufacturing potential by installing extra controlled-atmosphere brazing (CAB) furnaces of semi-continuous type.
E-coated microchannel heat exchanger

What is and how works e-coating?

What is e-coating, how it works, and what is vital to know about e-coating for microchannel heat exchangers.
Hydrophilic-treated MCHE

Hydrophilic topcoat for microchannel heat exchangers

Hydrophilic coating for microchannel heat exchangers: increases performance under wet conditions, improves condensate drainage and enhances corrosion resistance.
Twin-slab microchannel condenser

Twin-slab condenser coils bring efficiency advantages

Twin-slab microchannel condensers with thin-core subcooler offer tangible benefits for OEMs manufacturing air-cooled chillers and other air-to-refrigerant systems.
Multiport tubes

Microchannel heat exchangers for refrigeration systems running on R32 and other flammable refrigerants

Transition to low-GWP refrigerants, many of which are flammable or toxic, is ongoing. Heat transfer with microchannel coils significantly extends the spectrum of cooling applications and the size of refrigeration systems.
Serpentine heat exchanger

Strong demand for compact microchannel coils triggered production capacity expansion at Kaltra

Kaltra has expanded production capacity for top-demanded compact, low-volume serpentine microchannel heat exchangers.
Microchannel evaporator coil

Dual-circuit microchannel evaporators to revamp performance of air-source heat pumps

Kaltra extends portfolio with high-performance, dual-circuit microchannel evaporators designed and optimized for air-source heat pumps, including reversible units.
Reefer containers

Microchannel coils for trailer and reefer container applications

Kaltra introduces microchannel condenser coils targeted for refrigerated containers and trailers - one of the most demanding cooling applications in terms of reliability under challenging operating conditions.
Microchannel heat exchanger for ammonia

Microchannel heat exchangers for ammonia refrigeration

Ammonia, a natural, environmentally-safe refrigerant, gains a second wind by incorporating low-charge microchannel heat exchangers into R717 refrigeration systems.
Microchannel coil

Microchannel coils: your best choice for propane applications

As a refrigerant, propane (R290) becomes hugely popular in many applications. Low charge and high heat transfer make microchannel coils perfectly suited for propane systems.
Microchannel evaporator

Optimized microchannel evaporator design boosts efficiency

Kaltra rolls out all-aluminum microchannel evaporators with optimized outlet manifold design to increase partial load efficiencies.
Air-source heat pump

Microchannel coils for air-source heat pumps

Air-source heat pumps based on MCHE offer remarkable advantages but are complicated in design: Kaltra presents its efficiency-improving solution.
Heat exchanger coating

Kaltra puts forward innovative high-tech coating to improve heat exchanger performance

Kaltra introduces a new high-tech surface coating that delivers improved heat transfer rates and anti-corrosion properties for microchannel heat exchangers.
Chiller with microchannel condenser coils

Microchannel condenser coil replacement project

Kaltra completed a service project for the replacement of condenser coils at a 6.5MW chilled water production plant.
Microchannel coil

Charging microchannel coils

Recommendations on the correct charging procedure of HVAC systems equipped with microchannel coils - based on the subcooling control.
Cooling plant

Kaltra improves terms for heat exchanger supplies

Kaltra continues to uphold its strategic customer-oriented principles and further improves terms and conditions for supplying of heat exchangers.
Microchannel coil

Experimental investigation for microchannel heat exchangers corrosion in the coastal environments

One of the biggest factors of the growing popularity of microchannel heat exchangers is the high corrosion resistance of aluminum, which is achievable through the careful selection of aluminum alloys, surface treatments, and other protective measures.
Fluid coils

Anti-corrosion treatment for microchannel dry coils

Kaltra starts offering protective coating for inner surfaces of its microchannel water coils developed for improved corrosion resistance and longer operating lifespan.
Controlled-atmosphere brazing furnace

Microchannel heat exchangers: fabrication process

Microchannel coils are a type of heat exchangers made from aluminium by brazing. This article goes through the manufacturing process of microchannel heat exchangers.
Refrigerant distributor

Optimization of refrigerant distribution for microchannel evaporators

Microchannel evaporators with optimized manifold design: uniform refrigerant distribution, improved heat transfer, higher capacity.
Microchannel condenser bank

Air-cooled condenser assemblies for end-customers and OEMs

Designed for low-GWP refrigerants, last-generation, low-volume Kaltra's condensers based on microchannel technology display higher heat transfer rates and superior corrosion protection.
E-coated microchannel coil

High-grade corrosion protection for heat exchangers

Kaltra offers microchannel heat exchanger anti-corrosion treatment for HVAC equipment to ensure highest level of protection.
Microchannel heat exchanger

Kaltra offers coil replacements for condensers and water applications

Kaltra offers heat exchanger replacements for end-customers and OEMs: microchannel coils featuring high performance and long service life.
E-coated microchannel coil

Heat exchanger protection with electrocoating

Electrocoating offers extremely high corrosion resistance for all-aluminum microchannel heat exchangers, making them the most suitable solution for use in extra-corrosive environments.
Serpentine coil

Serpentine coils for compact cooling systems

Microchannel serpentine coils for condenser and evaporator use: low-charge, compatible with HFC/HFO and natural refrigerants, suitable for any applications
Microchannel heat exchanger manufacturing plant

Microchannel coils in single-phase heat transfer applications

Features, advantages, and design considerations of single-phase microchannel heat exchangers for cooling and heating applications.
Microchannel heat exchanger

Microchannel heat exchangers as an advanced alternative to traditional HVAC coils

Advantages and benefits of new-generation microchannel heat exchangers for HVAC applications in comparison to traditional finned tube heat exchangers.
Precision air conditioner

Technology rally: microchannel vs. finned tube evaporator

A comparison for precision air conditioning system with finned tube evaporator and the system with microchannel evaporator: performance and ergonomic acpects.
Microchannel coil

Corrosion protection for microchannel heat exchangers

Corrosion resistance of the microchannel heat exchangers in highly polluted environments; protective coatings and special treatments.
Microchannel evaporator

Alcoil receives U.S. and international patents for microchannel evaporator design

Alcoil announces the issuance of US and European patents, which relates to an improved and advanced microchannel evaporator design.
Serpentine coil

Serpentine heat exchangers for small cooling applications

Kaltra offers the latest heat transfer technology based on serpentine coils for small and portable cooling applications.
Free cooling chiller

Microchannel coils in free cooling applications

Featuring microchannel heat exchangers as free cooling coils, modern chillers deliver significant energy savings in applications.
Microchannel evaporator

Advanced microchannel technology for HVAC and process cooling

Advantages and benefits of using microchannel heat exchangers for HVAC applications: from high thermal conductivity to improved anti-corrosion properties.
Microchannel heat exchanger

Methods of microchannel coils defrosting

Considering the methods and specificities of defrosting for microchannel heat exchangers: electric defrost, off-cycle defrost, and hot gas defrost.
Air-cooled chiller

V-shaped microchannel coils for chiller applications

V-shaped microchannel condensers: advantages and benefits for manufacturers of air-cooled chillers.
Microchannel heat exchanger

Microchannel coils add dimension for cooling systems

Microchannel heat exchangers: modern microchannel technology is more robust than the earlier finned tube designs, offering operational, performance and efficiency advantages.
Microchannel heat exchanger

Microchannel coil: fix or replace

Microchannel coils are constructed to reduce size, use less refrigerant, be more durable, transfer heat better and eliminate formicary corrosion.
Microchannel coil

The most advanced microchannel technology comes to Europe

Kaltra becomes a representative of Alcoil in the European HVAC market with advanced microchannel technology and products.
Microchannel heat exchanger

Formicary corrosion

One of the key advantages of microchannel coils is their resistance to formicary corrosion which causes the majority of leaks in finned tube heat exchangers.
Microchannel heat exchanger

Aluminum coils: recommendations for cleaning

Recommendation on cleaning methods for microchannel heat exchangers.
Microchannel coil

Microchannel coils fast becoming industry standard

The microchannel coil advantages are the future and rapidly becoming the norm because of the many benefits they provide in new HVAC equipment.
Microchannel coil

Field tests for evaluating microchannel heat exchangers with variable fin pitch

Innovative, variable-geometry microchannel heat exchanger design offers optimized airflow, improved performance and efficiency in applications.
Microchannel coil

Microchannel heat exchangers: advantages and benefits

Aluminium microchannel heat exchangers for condenser, evaporator, heat pump, and chilled water applications: features and benefits.