What is a charge air cooler?

TECHNICAL

INTRODUCTION

What is

a charge air cooler?

A charge air cooler is used to cool engine air after it has passed through a turbocharger, but before it enters the engine.
This is their main function. The idea is to return the air to a lower temperature,
for the optimum power from the combustion process within the engine.
More specifically, it is a heat exchange device used on turbocharged and supercharged (forced induction) internal combustion
engines to improve their volumetric efficiency by increasing intake air-charge density through isochoric cooling.
A decrease in air intake temperature provides a denser intake charge to the engine and allows more air and fuel to be
combusted per engine cycle, increasing the output of the engine. See our brilliant range of Charge Air Coolers here!

Our Charge air coolers

The charge air cooler is designed to cool the charged air from something in the region of 180°C
to 220°C, down to around 40°C. It achieves this by using cooling water.
Charge air coolers range in size depending on the engine. The smallest are most often referred to as intercoolers
and are attached to automobile or truck engines. The largest are often used on huge marine diesel engines
or in power plants. They can weigh several tonnes in these circumstances.

Most are still associated with diesel engines, but Vestas aircoil manufactures specialist air coolers for gas engines too.
The first marine diesel engine charge air cooler was built by Vestas aircoil A/S in 1956. Look at our history here.
The phrase “charge air cooler” is an all-encompassing term, meaning that
it cools the turbo’s charged air before it is routed into the engine.

More Information

Find it right here:

Standard “EK” charge air coolers

Vestas produces its charge air coolers using a range of fin geometries.

There are details here of our Ultra Compact, Compact & Premium Tin Coated geometries.

Perfect for 2-stroke engines.

From 1956 to around the millennium, all Vestas charge air coolers used our Premium Tin Coated LK geometry.

The name “standard” is perhaps a little dull, but it just means we use the same layout, but without the tin coating. Why? – to reduce the cost. Today most engine builders prefer a more economic design than the older Premium versions. Vestas continues to offer the choice of both for its clients!

15mm diameter tubes combined with an infinite range of fin pitches make bespoke designs for each cooling requirement easily achievable. There is a range of surface options from low pressure drop plain finish to heavily corrugated surfaces designed to produce powerful turbulence and thus improve heat transfer.

The air coolers can be manufactured from a number of materials, also combined with coatings where required.

Premium tin soldered charge air coolers

Unique to Vestas aircoil A/S this procedure provides the ultimate bond between the fins and the tubes.

Tubes and fins are assembled, then coated entirely in tin. The element effectively becomes one piece and heat transfer is therefore very efficient.

This premium method of construction is simply more robust than “standard” construction coolers. They last longer!

The tin coating is used in some of our range of gas engine charge air coolers. The coating provides protection from the contamination present within the gas. Pure copper, though ideal from the perspective of heat transfer, is not perfect in the aggressive atmosphere of the gas/air mixture of these engine types. Vestas aircoil needs to consider a material that would cater for the required heat transfer and survive in this hostile environment.

Underneath the tin coating are the same high-quality materials (Copper fins and CuNi 90/10 tubes).

The method is used extensively, both for new engines and within our aftermarket department for replacement coolers.

At Vestas aircoil, this process has been used for decades for OEM supplies and to this day provides an alternative for both new and old engines.

Tin coating can be applied to most of our tube and fin geometries

Compact charge air coolers

Vestas produces its charge air coolers using a range of fin geometries.

There are details here of our Ultra Compact, Standard & Premium Tin Coated geometries.

Minimum space, maximum performance

Extremely efficient & compact so that it is perfect for use with 4-stroke high performance engines.

10mm diameter tubes combined with an infinite range of fin pitches make bespoke design for each cooling requirement easily achievable. There is a range of surface options from low pressure drop plain finish to heavily corrugated surfaces designed to produce powerful turbulence and thus improve heat transfer.

Compact coolers can be manufactured from a number of materials, also combined with coatings where required.

Ultra-compact charge air coolers

Vestas produces its charge air coolers using a range of fin geometries.

There are details here of our Compact, Standard & Premium Tin Coated geometries.

High performance for high speed engines

Extremely efficient & compact so that it is perfect for use with high speed engines and other air/gas cooling environments.

7.5mm diameter tubes combined with an infinite range of fin pitches make bespoke design for each cooling requirement easily achievable. There is a range of surface options from low pressure drop plain finish to heavily corrugated surfaces designed to produce powerful turbulence and thus improve heat transfer.

Compact coolers can be manufactured from a number of materials, also combined with coatings where required.

EGR Coolers

We use Ultra Compact geometry for our range of exhaust gas recovery coolers too. The same layout but with specialized materials and no fins!!

Aftermarket Charge Air Coolers & Heat Exchangers

In 2000, Vestas came to the conclusion that we were losing too many orders for the replacement of our own charge air coolers to unlicensed “copy” companies.

A new department was set up dedicated to winning the business back and offering shipowners and power plant operators the chance to purchase approved equipment, but at an economically attractive price.

The team was assembled from engineers experienced in the “grey market”, but who were enthusiastic to promote a more professional approach to business.

The department is situated Birmingham, England. From this hub all aftermarket business is handled worldwide, regardless of the client location or indeed the place of manufacture. A network of agents and distributors support the team.

By centralizing our aftermarket business, we introduce consistency of design standards, unified commercial profile and offer our clients a single point of contact.

The team also handle small quantity special product heat exchanger requirements and are especially capable of dealing with complex pressurized enclosures and the requirements of DIRECTIVE 2014/68/EU Pressure Equipment Directive (PED)

Vestas can also offer cleaning services and repairs.

All heat exchanger requirements are welcome.

Charge air cooler – Generator air coolers – TEWAC – Compressor coolers – Shell & tube – Special products – Dry cooler radiators – Crane coolers – A/C Coils

With the approval of the engine builders, Vestas aircoil provides replacements for all brands of charge air coolers and all engines:

Supported brands:

ABB
Astra
Bloksma
Brown Boveri
Dong Hwa
GEA
GEA Bochum
GEA Kawasaki
GEA WuHu
Hubie Deng Feng
Kawasaki
Kelvion
Poccnr
Rumia
Seo Koatsu
Serck
Smam
Suction Gas
Young Radiator

Fin & Tube heat exchangers – How to purchase a good quality air cooler

A working principle for charge air coolers:

A charge air cooler manufactured by Vestas aircoil will feature within it a series of tube and fin elements. Fins are mechanically bonded to the outer surface of the tube. The principle is simple. By increasing the surface area, there is a consequent increase in the cooling surface, providing the bond between the tube and the fin is sufficiently strong to allow energy (heat) to pass. The same principle is used in reverse in a water heater (radiator).

The materials of construction are important: it’s all too easy to cut corners here. Of course, the prudent engineer wishes to purchase at the best possible price, but consider the lifetime you expect from the replacement and how an air cooler company achieves your requirements.

You should expect, first of all, that the construction materials are of suitable quality and that the supplier can prove the case. Copies of material certificates should be available for inspection by you if you wish. 90/10 copper nickel tubes are the optimum choice, but there are higher grades too if appropriate. As for the fins, copper is the correct material. If a company offers aluminium fins, you can expect a very short operational life.

The replacement cooler should be constructed in a way, which accounts for all the physical stresses that it will encounter. Of course, the cooler has no moving parts and is therefore often considered of less importance, but what happens if the cooler begins to fall apart in your engine?

Its design should allow for the stress of uneven expansion and contraction caused by a temperature difference in excess of 150°C across it. It should also be rigid enough to withstand sometimes significant vibration.

A full tube support mechanism is therefore essential. Integral tube supports plates, positioned at intervals along the length of the air cooler are recommended. These plates are in effect intermediate tube plates and allow every tube to be mechanically bonded to every other tube, not just at either end of the cooler but throughout its entire length. If individual tubes or rows of tubes are allowed to float free or simply clamped with bars on the outside face of the cooler fins, then there is nothing to stop early mechanical failure caused by vibration. Our advice would be to question any potential supplier on this specific point in detail.

How are the fins attached to the tubes? By expanding the diameter of the tube beyond its point of elasticity; thus gripping the fins to it. Both methods are effective but the coated versions have advantages in contaminated environments.

There is a significant advantage if the number of separate components is kept to a minimum. A “monoblock” fin and tube element, encompassing as many tubes as possible, is preferable. The lifetime of the product will be longer where the possibility of separate components interacting against each other is removed.

Vestas has extended its maximum fin width to 77 tubes wide, big enough for almost all sizes of coolers – we call it a “MonoBlock” element. A MonoBlock combined with a full integral support plate means there is effectively a one-piece element. Fewer components means a more robust air cooler. Perfect where there is vibration.

Integral Support

Vestas produces its charge air coolers using a range of fin geometries. There are details here of our Ultra-compact, Compact, Standard & Premium Tin Coated geometries. One-piece construction – peace of mind.

Any air cooler over a few hundred millimetres in length needs a proper support mechanism. The science behind the calculations that determine its requirements and position is complex, but the method is simple.

In the same way as the tubes are roller-expended into tube plates at either end of the charge air cooler, they are also mechanically bonded to support plates, strategically placed along the length of the air cooler.

The plates are then attached to the side panels. The precise position and method of attachment differs depending on the environment and is itself, the subject of complex design considerations. In combination with MonoBlock – Vestas coolers are the most robust available.

Monoblock Charge Air Coolers

Vestas produces its charge air coolers using a range of fin geometries. There are details here of our Ultra-compact, Compact, Standard & Premium Tin Coated geometries. Fewer parts = fewer problems.

Limitations on the maximum size a fin can be produced traditionally led to a restriction of the width of the fin. Thus, coolers in the past are built with multiple smaller fin “elements”. Vestas has extended its maximum fin width to 77 tubes wide, big enough for almost all size of coolers – we call it a “MonoBlock” element. A MonoBlock combined with a full integral support plate means there is effectively a one-piece element. Fewer components mean a more robust air cooler. Perfect where there is vibration.

FUNCTIONS

A charge air cooler cools the combustion air after it has been compressed in the turbo charger.
The process of turbo charging involves compressing the air which introduces energy in the form of heat.
The air is cooled to the correct temperature for efficient use in the engine.

The air cooling is made possible by passing cool water (sea water or fresh water)
through the charge air cooler tubes. There are fins attached the tubes that have the effect of increasing
the surface area of the outer surface of the tube. This improves heat transfer.

The thermal design of an air cooler is of course critical. The engine performance could be badly affected if the charge
air cooler is incorrectly designed. This is vital at new building, but equally so when the time comes for replacement.

Using OEM approved Vestas aircoil to replace an air cooler gives the owner a distinct advantage
since the relationship Vestas has with the engine builders is historically strong. Access to
data is vital. With data, one can make certain the design will work in the engine.

Charge air coolers range in size depending on the engine. The smallest are most
often referred to as intercoolers and are attached to automobile engines or truck engines.
The largest are reserved for use on huge marine diesel engines and can weigh over 2 tonnes.

TEMPERATURE

The charge air cooler is designed to cool the charged air from something in the region of
180°C to 220°C, down to around 40°C. (A little higher on medium and high speed engines).

It achieves this by using cooling water either from the sea (25°C “ambient” or 32°C “tropical”) or a
central cooling water system with fresh water at around 32°C.

If your air cooler is under-performing, contact our aftermarket department for advice.

Thermal design – replacement air coolers

Often the engine for which the charge air cooler is to be fitted is already 10-15 years old. It’s running conditions
may not match those specified at its design stage. In addition, engines are often re-rated to suit the vessels
optimum performance efficiency. It is essential then to recognize that a poorly thought out copy of the original may not only cost
you more time and money, but that it might not be the correct solution to your current problem.

All air cooler designs, original and replacement, represent a trade-off between heat transfer and pressure drop characteristics.
Improved performance can be obtained by increasing turbulence. The optimum design should provide you with an acceptable performance with minimal pressure drop. The design of the fin and its thermodynamic characteristics is most important. The surface
area of the fins alone is not as critical as you may think. The design of the fins that go to make up the surface area is a more
important factor. Other factors include, fin and tube density, tube geometry and material quality.

Check that the supplier has reviewed your coolers design and is proposing the correct thermal solution. There are suppliers who have
only one fin alternative and try to provide solutions for all engines with it. Clearly, they will be making design compromises
in order to win the order, so be careful and look for a company that has
design alternatives, not just one choice. Also, ask the supplier how he knows his proposed cooler design will satisfy
your thermal requirements. Has the fin arrangement been independently tested?

Our advice is that you should be as specific as possible about current operating parameters, that you take into
account the original design and lastly that you identify why you need to change the cooler i.e. what is the cause of the failure?
If you tell the potential supplier the problem, he has a good chance to provide you with the solution!

THE DIFFERENCE

What is the difference between an intercooler, an aftercooler and a charge air cooler?
There is some confusion in the terminology.

The "inter" prefix in the device name originates from historic compressor designs. In the past, aircraft engines
were built with Charge Air Coolers that were installed between multiple stages of supercharging, thus the designation of “inter”.

Likewise, the “after” prefix refers to cooler placed at the end of supercharging chain.
While multi-stage turbocharger systems are still in use today, the terms intercooler and aftercooler are most often used synonymously,
even in single stage cooling devices where a single cooler sits between the turbo and the engine. Both terms are used interchangeably.

Thus, since an intercooler or aftercooler commonly cools charged air, they are both referred to as Charge Air Coolers.
Scroll down to find out the functions of a charge air cooler or how charge air coolers work.

HOW DO THEY WORK?

The function of a charge air cooler is to cool engine inlet air after it has passed through a turbocharger, but before it enters the engine.
The idea is to return the air to a lower temperature, for the optimum power for the combustion process within the engine.
As the air is compressed it absorbs energy. Energy equals heat, so the temperature of the air increases as the pressure increases.

Over time, the heat would dissipate, but for the engine, the air is required immediately. For this reason, the intercooler is designed to
cool the air quickly using cold water. The heat (energy) is exchanged from the hot air to the cool water as the two mediums pass by each other in the charge air cooler.

The cool water passes through multiple tubes within the unit. The tubes often have fins attached
to them that have the effect of extending the surface area of the outside of the tube. In this way, more of the outer surface of the tube is
in contact with the hot air. The heat energy passes from the air, into the fins, through the wall of the tube and into the water.

The tubes and fins are manufactured from material that is capable of conducting energy. It must also
withstand the water and the air, both of which often have contamination. Copper fins and copper nickel tubes are most often selected.

Integral Support – charge air coolers

Fin & Tube heat exchangers – How to purchase a good quality air cooler
A working principle for charge air coolers:

A charge air cooler manufactured by Vestas aircoil will feature within it, a series of tube and fin elements. Fins are mechanically bonded to the outer surface of the tube. The principle is simple. By increasing the surface area, there is a consequent increase in the cooling surface, providing the bond between the tube and the fin is sufficiently strong to allow energy (heat) to pass. The same principle is used in reverse in a water heater (radiator).

The construction materials are important: it’s all too easy to cut corners here. Of course, the prudent engineer wishes to
purchase at the best possible price, but consider the lifetime you expect from the replacement and how an air cooler company achieves your requirements.

You should expect, first of all, that the construction materials are of suitable quality and that the supplier can prove the case. Copies
of material certificates should be available for inspection by you if you wish. 90/10 copper nickel tubes are the optimum choice, but
there are higher grades too if appropriate. As for the fins, copper is the correct material. If a company offers aluminium fins, you can expect a very short operational life.

The replacement cooler should be constructed in a way, which accounts for all the physical stresses that it will encounter.
Of course, the cooler has no moving parts and is therefore often considered of less importance, but what
happens if the cooler begins to fall apart in your engine?

Its design should allow for the stress of uneven expansion and contraction caused by a temperature difference
in excess of 150°C across it. It should also be rigid enough to withstand, sometimes, significant vibration.

A full tube support mechanism is therefore essential. Integral tube supports plates, positioned
at intervals along the length of the air cooler are recommended. These plates are in effect intermediate tube plates and allow every tube to be mechanically bonded to every other tube, not just at either end of the cooler but throughout its entire length. If individual tubes or rows of tubes are allowed to float free or simply clamped with bars on the outside face of the cooler fins, then there is nothing to stop early mechanical failure caused by vibration.
Our advice would be to question any potential supplier on this specific point in detail.

How are the fins attached to the tubes? By expanding the diameter of the tube beyond its point of elasticity; thus gripping the fins to it. Both methods
are effective but the coated versions have advantages in contaminated environments.

There is a significant advantage if the number of separate components is kept to a minimum.
A “monoblock” fin and tube element, encompassing as many tubes as possible is preferable.
The lifetime of the product will be longer where the possibility of separate components interacting against each other is removed.

Vestas has extended its maximum fin width to 77 tubes wide, big enough for almost all sizes of coolers – we call it a
“MonoBlock” element. A MonoBlock combined with a full integral support plate means there is effectively a one-piece element.
Fewer components means a more robust air cooler. Perfect where there is vibration.