Charge Air Coolers
What is a charge air cooler? The charge
air cooler (or scavange air intercooler) is located between the turbo
charger and the engine air inlet manifold. The purpose of the charge
air cooler is to reduce the air inlet temperature thereby increasing
air density thus giving an increase in engine efficiency. Typically
the charge air cooler will cool air from 200 ºC to 45 ºC with high
air velocities. It is obviously important to meet the required performance
but with the high air velocities, it is imperative that the construction
has high integral strength. Seawater is usually used as the cooling
medium and so high quality materials are needed to ensure a long serviceable
life. Leaking or damaged charge air coolers can cause loss of power,
increased emissions, increased fuel consumption and increased exhaust
temperatures leading to excessive engine wear/damage. The air cooler
is therefore an integral part of any turbo charged diesel engine.
How are they built? Historically,
replacement air coolers purchased from replacement suppliers were
produced using separate "spiral wound" finned tubes. One can still
purchase these from many sources around the world. This process
is however expensive and time consuming. More importantly, it is
very difficult to predict the thermal properties of an air cooler
manufactured in this way. Often, a charge air cooler manufactured
using "sprial wound" tube produce a high pressure drop,
thereby starving the engine of air at higher speeds.
AMI Exchangers addressed this issue many years
ago when we developed the "block fin" method of construction
- now an industry standard.
 |
| Cassette
type charge air cooler received at our workshops |
What is block fin? "block fin" is a
method whereby a single fin, encompassing several tubes, is assembled
in one complete operation. This method is quick to manufacture,
cost effective, extremely efficient and offers superior mechanical
strength. Once tested, the thermal properties can be used to accurately
predict the air cooler characteristics when in service. Because
dimensions are fixed, each type of block fin will have individual
heat transfer characteristics and this is why we at AMI have developed
many fin types, each offering a different thermal performance. Our
coolers are fitted with full intermediate support plates within
the fin block to give additional stability against vibration.
 |
Cassette
type charge air cooler replacement made by
AMI Exchangers |
What options are available? The original
charge air cooler's thermal properties vary depending upon many
factors such as original manufacturer, air quantity, temperatures,
etc. It is therefore impossible to satisfy all requirements with
only one type of fin - some of our competitors will try to convince
you they can.
How many fin types do AMI have? We at
AMI have built up the largest selection of "block fin" within our
industry. We currently have SEVEN thermally different fin
options available and we are continuing to develop more. Each
of our fin types is specifically designed to provide a unique thermal
performance in order to meet the individual needs of specific engines.
No other supplier is better equipped to provide proven thermally
engineered solutions to their clients.
 |
| Frame
type charge air cooler frame received at our workshops |
Are AMI Charge Air Coolers equivalent to OEM?
Due to the quantity of fin types available to us, we always have
a fin option that will allow us to build an air cooler that has
thermal specifications equal to or better than the original unit.
Occasionally, clients are unhappy with the original air cooler performance
and in these circumstances we can offer to build a new cooler with
improved efficiency or reduced pressure drop. The dimensions of
the air cooler can be obtained from our extensive database of drawings,
surveys onboard or from samples sent to our workshops.
 |
Frame
type charge air cooler using salvaged frame and water chambers
fitted with new tubes, fin and
tube plates. |
What about the new NOx regulations?
The NOx emissions of your engine are effected by the condition of
the charge air cooler. In coming years, vessels will need to prove
that the air cooler manufacturer has offered a cooler with the same
performance as the original. Technical files are now being prepared
on new vessels and regulations are in place to ensure charge air
cooler thermal data exists within this file. Our fin types have
been tested at independent test facilities and results used within
our complex thermal design software. If we are supplied with the
original thermal data, we can offer ACURATE thermal specifications
of our cooler - thereby satisfying NOx Requirements!
What about quality? We manufacture
air coolers using high quality materials. We buy these materials
in bulk direct from European manufacturing mills. This enables us
to better control the quality of materials. All charge air coolers
are available with material certificates. Our quality procedure
includes full traceability of material and workmanship. The air
cooler is checked at various stages of production ensuring quality
throughout all areas of manufacture. Some examples of customer
comments can be found on this site.
What quality assurances can you give?
We can arrange certification by most internationally recognised
independent classification societies (Lloyds Register, ABS, DNV,
NKK, G. Lloyds, etc).
Please feel free to contact our sales team direct or use the enquiry
form that can be found on this site.
AMI Exchangers Ltd, Apex Workshops,
Graythorp Industrial Estate, Hartlepool, UK TS25 2DF
Tel: +(44)1429 860187 Fax: +(44)1429 860673
E-mail: sales@ami-exchangers.co.uk |