As a follow up and expansion to last week’s blog “Gauging the Best Heavy Duty Radiator Core”, this week we would like to address the more intricate details of the cooling process. Although anyone in the market for a heavy duty radiator already knows that the purpose is to cool the engine, they may not fully be aware of how this takes place or the options there are for the best cooling for their particular application.

The heat transfer in the radiator begins when the hot coolant is directed into the inlet tank and dispersed across the radiator core, which then flows into the tubes. As the coolant streams through the tubes the heat is transferred to the tubes, and then transmitted to the attached fins located between the tubes. The fins are a very important part of the process as it is the fins that have the capability to then discharge the heat into surrounding, or ambient, air. The amount of contact the fins have to the tubes has a direct effect to the efficiency of the heat transfer because they are subject to ram air and air flow from the fan to be cooled. We will be explaining this a little more clearly as we go along.

So, why does the makeup of the materials make a difference? Let’s first consider the importance of the tubes. Radiators are built with different types and sizes of tubes, as well as various tube spacing’s; meaning the amount of space placed between the tubes. Larger tubes, situated closer together will allow more flow of the coolant than smaller tubes with wider spacing. There are also dimpled or straight tubes. If the tube is a straight-flow type, the coolant does exactly what that sounds like; it flows straight through. Dimpled tubes are made with small indentations within it to turbulate and slow the flow of the coolant to be cooled more efficiently. Think about cooling a cup of hot cocoa, if you stir (turbulate) while blowing on it to cool, it will take less time (more efficiently) than only blowing on the surface of the cocoa. Initially, the dimpled tubes were more likely to be found in a Peterbilt, Kenworth, Freightliner, Volvo and other over the road trucks with a Cummins engine. Cummins referred to it as the “low flow” (also known as a “slow flow”) system beginning in 1986 and through the early 1990’s. However, today they are more widely used in a conventional radiator playing a key role in cores referred to as high efficiency types.

The contact of the fin to tube is the next item to consider. Because the fin is responsible for dissipating the heat, the more contact to the tube, the more efficient the cooling. In the last blog we noted that fins are identified by how many fins are in a one inch measurement; notably called “fins per inch” (FPI). If you have 10 FPI on one radiator core and 16 FPI on another, the one with 16 FPI has the greater amount of contact with the tubes thereby giving it more efficient cooling capabilities.

Just as the tubes offer assorted varieties, there are also many fin types used for different applications and purposes. A louvered fin is created with slits just as you might picture on a louvered door, which allows for more air flow through the core. This type is most often used on over the road trucks. However, the louvers are also subject to catching debris so a straight fin would be used in off-road applications such as Case tractor. For those extreme duty applications such as a Caterpillar or Komatsu excavator, one might choose a steel fin type. Although heat transfer is more effective with copper, brass, or aluminum, steel is better equipped to withstand a harsher environment.

Now that we’ve discussed the anatomy of a heavy duty radiator core, you are armed with the knowledge to choose the best and most efficient radiator for your application type. The staff of American Radiator is also available to you for any other questions you may have regarding material types or the benefits of using a high efficiency, heavy duty radiator or core. Feel free to contact us on our website, comment on the blog, through our Facebook page, or just give us a call!