When designing a new machine with an AGCO Power engine, like a tractor or any other off-road machine, whether for forestry, construction or agricultural use, it is always more than just taking an off-the-shelf engine and bolting it on. It is an involved project with many tweaks aimed to ensure good integration, efficient operation, low emissions and other desired properties. The CORE Insights article series sheds light on the various areas that can be optimized. Account Manager Jussi Hyvärinen opens the game by telling how fine-tuning the cooling system can save fuel in agricultural and forestry work.
Heat is an unavoidable by-product of all internal combustion engines. In practice, a large amount of fuel energy is converted into waste heat instead of work. With some advanced thermal management design, we can make sure the engine always works at optimal temperature and no energy is wasted for unnecessary cooling.
Getting rid of heat
Cooling system is a necessary part of any engine. It gets rid of the excess heat and prevents the engine from overheating. The cooling system itself uses some of the engine power by circulating water, blowing cool air to the radiator etc. The amount of cooling needed depends on the work at hand: Heavy work creates more excess heat than light work. So, when doing light work, the engine could do with less powerful cooling, saving fuel.
This brings us to the problem at hand: the cooling system in most vehicles must be able to handle the worst-case scenario of working with full revs and load in the heat of Sahara. However, this seldom happens in normal usage. The lower end of the temperature scale gets far less attention. When the engine runs cool, the Sahara-ready cooling fan might try and cool the already cold radiator, consuming energy.
Adjust the fan, not the radiator
What happens under light load in many engines is that the thermostat cuts some of the coolant circulation to the radiator to avoid excess cooling. This cools down the radiator significantly, reducing its efficiency. The better solution is to be able to optimize the power of the radiator cooling fan. By turning down the cooling fan the whole of the radiator stays in optimal operating temperature and remains efficient.
In general, it is much more energy efficient to adjust the cooling fan power than to let the engine thermostat adjust the power of the radiator itself. So much so, that actively optimizing the cooling fan power can save a significant amount of fuel. For example, saving 4 kW of power translates to reducing fuel consumption for about 1 liter per working hour. For the machine manufacturers, the little extra cost of adding a controllable fan means lower lifetime costs.