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Cooling Systems in Commercial Vehicles


It can be difficult to choose between direct and indirect cooling systems, but this article will help you better understand the advantages of indirect systems.

Cooling Systems in Commercial Vehicles

Nowadays, the most popular cooling systems seen in commercial vehicles on the market are direct ones. Nevertheless, the more technologically advanced and innovative option for cargo-trucks — the indirect cooling system — is often overlooked or used in conjunction with two-stage turbocharging. The potential of these systems is indeed massive, and we believe they can be a great asset for truckers, who are searching for optimal cooling solutions that can keep their vehicles up to date. One of the most important questions truckers ask is how long to get hazmat endorsement for their vehicles. So we advise you to study the article from HMD Trucking.

Pros and Cons of Direct Cooling Systems


Let’s dive into the details about direct cooling systems. These systems use several distinct components – a radiator, a charge air cooler and a condenser – that all work together to provide cooling effectively. Even with the introduction of the Euro VI emission standard, the core structure of these systems stayed the same. However, this new standard did bring in significant modifications. The components were upgraded to increase their power density, the accuracy of the fan drivers was also improved and a new Visco® drive was added.


Despite exchanging various components and making various adjustments, the inherent issues of direct cooling systems, ultimately, remain unchanged. The composition of the system is intricate and can often vary by truck type, to involve cooling either the transmission oil or the compressed air. Looking ahead, the range of duties of this system is liable to continue expanding and may even comprise components related to power electronics and various batteries. As a result, one tends to incorporate additional coolers that necessitate their own auxiliary fans.

Hence, the system does not only consist of multiple mutually-affiliating components, but also uses up an appreciable amount of fuel. As the assortment of elements is increased, the consumption of fuel rises proportionately. At the same time, it requires additional effort and resources to involve more heat sources into the system. Should the system experience a breakdown, it requires more substantial investments for repairing and sustaining it, owing to its complex architecture.

Indirect Cooling Systems

The indirect cooling system is not only straightforward, but it also offers several major benefits. This system consists of only a low-temperature radiator and a high-temperature radiator, with the former cooling the coolant to ambient temperature. That coolant then passes through a charge air cooler, which is an essential component in an engine, and is distributed amongst the various other components that need cooling. This approach has the advantage of improving the ratio between the cooling capacity and resulting pressure loss, since the paths travelled by the coolant are shorter. Additionally, the number of heat sources that can be added to the system is practically limitless, as they don’t necessarily require cooling at the same time.

Moreover, thanks to the pairing of a charge air cooler and a low-temperature radiator, the installation depth for the cooling module is reduced, which does not only allow for a greater throttling of the flow, but for the fan to be switched less often because it starts to work at a higher torque. This translates into a more reliable system with an extended lifespan.

We can also highlight the improvements in fuel consumption which are direct consequences of using an indirect cooling system in an engine. Recent tests with an Euro VI engine revealed a one percent decrease in fuel consumed and, interestingly, Euro V engines have shown a shocking two percent decrease. This is mostly due to the inclusion of charge air cooling, which was not possible in the engines of previous generations.


In conclusion, it can be highlighted that indirect cooling systems have been established as an exceptional technology that provides a more uncomplicated, cost-effective, and efficient cooling process. What is more, the cooling circuit involved with this cooler is clearly more straightforward than that of a direct cooling system resulting in a more affordable production cost.

In addition, the simple manufacturing and running of the indirect cooling system presents the opportunity for new applications to easily cool additional thermal sources. For that reason, it will stay close to the cutting edge even with the consequent introduction of electric- and battery-powered vehicles.

Furthermore, its performance is increased as the cooling block is built with a more compressed unit as well as an improved flow rate. This allows the engine output to experience a notable development whereas the fuel saving can range between 1-2% varying upon the type and scale of the engine.

Given all the amazing benefits it could bring, it is without doubt that the addition of indirect cooling systems on heavy vehicles can enable superior security and outstanding affordability for truck owners and drivers.

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