Let's also talk about the design of the engine's cooling system

Recently, I read an article titled "The Mystery of Arab Robes" in the 7th issue of Reader's 2006, which gave me a lot of insights and led me to think about the design of construction machinery products.

The article mentions that in the height of summer, the temperature in the desert area can reach 40 to 50 degrees Celsius. However, local residents, dressed in loose Arabian robes, walk calmly and nonchalantly on the scorching desert.

The article also conducted a comparative experiment. When tourists walked in the desert wearing white shirts and shorts, they felt extremely hot. Then, changing into an Arabian robe, there was an indescribable sense of coolness and comfort. It may sound hard to believe that a wide robe is cooler than a short one, but there is indeed a convincing scientific reasoning behind it.

1. Chimney effect. The Arabian robe is wide and can cover the entire body. When the wind from outside blows into the robe, it can quickly spread from top to bottom, sweeping away the dampness in the body.

2. Heat insulation The Arabian robe can block direct sunlight from shining on the body surface, and the air filling the robe also has a good heat insulation effect, thus making people feel cool and comfortable.

3. Create a suitable microclimate. The design of the robe plays a good regulatory role in creating a comfortable microclimate inside the robe. The air temperature inside the robe is always maintained at 3.1 to 33 degrees Celsius in winter and summer, and the relative humidity is 40-60%.

4. The fabric of the robe. When making long robes, choose fabrics with good heat absorption and heat dissipation, such as linen, silk, cotton fabrics, etc.

5. The color of the robe. Most of them choose light colors, usually white, light blue and light green, to minimize heat absorption as much as possible.

The thermal balance problem of the engine cooling system for construction machinery products has long been a major and difficult issue that has not been fundamentally resolved for many years. The author believes that apart from the correct matching of the heat dissipation system (for instance, the tourist should be a healthy person), the creation of a microclimate environment (the role of the robe) is also crucial and an inseparable part of the heat dissipation system; otherwise, it is impossible to achieve good results. Just as tourists wearing white shirts and shorts (and some even bare-chested) would feel unbearably hot when walking in the desert. Now, I would like to share my thoughts on the design concept of the cooling system (non-independent cooling system).

The "chimney effect" is of great significance. That is to say, the heat dissipation system should have a well-ventilated air duct design, similar to a "long robe", to form a "chimney effect". Cold air can be drawn in smoothly and hot air can be discharged smoothly without forming vortices.

Whether the air duct design of the engine is reasonable and whether the intake and exhaust air volumes are sufficient directly affect the heat dissipation efficiency. The author has noticed that some well-known foreign brand products pay great attention to the design of the air duct when designing the heat dissipation system. Whether it is the suction type or the blowing type, the design of the air duct is very meticulous and is very worthy of our learning and reference. The first impression given to the author is that the engine cooling system cover of foreign products is "very tightly covered", yet the cooling effect can meet the usage requirements in hot and sweltering heat. There is still a gap in domestic products in this regard. Some products do not take the air duct design into account in the engine cooling system, with air intake and exhaust everywhere, and cold and hot air mixed together. Only simple sheds are installed around the engine cooling system to provide shelter from wind and rain. Some are even without any cover, just like naked tourists basking in the sun in the desert.

It is recommended to carefully study and draw on the air duct design technology of the cooling system of products such as Caterpillar, Komatsu, Volvo, BMW, and Dynabac. The air duct design technology of different types and different usage conditions of products varies, fully demonstrating the adaptive countermeasures made by different machines for different working objects and working environments. Careful appreciation is sure to bring some gains.

2. The isolation effect between cold and hot air is very obvious. The purpose of isolation is, first, to ensure that the inhaled air is fresh air at the ambient temperature, and second, to prevent hot air from flowing back and being sucked into the radiator again. The hot air coming out of the radiator has considerable resistance. The hot air may flow back from the sides of the radiator to the suction side of the fan, raising the temperature of the cooling air and reducing the heat dissipation efficiency. The isolation measure is to seal the gap between the radiator's periphery and the inner side of the hood, completely separating the area in front of the radiator from the engine compartment. This can effectively reduce the recirculation of this hot air.

The air intake on the hood should face the radiator fan directly, ensuring sufficient air intake and minimizing air intake resistance as much as possible. The discharge of hot air should be smooth, without forming hot air vortices. Try to prevent hot air from reheating other components, such as oil pumps and hydraulic oil tanks. If necessary, an insulation layer can be set up.

3. To create a suitable "microclimate", the design of the internal and external structures of the hood, the material of the hood, and the color of the outer surface are all very meticulous. The hood itself is like an "Arabian robe", which not only needs to be aesthetically pleasing on the outside but also take into account the functions it can achieve inside.

The materials used to make the hood include metal and non-metal materials. The heat insulation and sound insulation effects of metal materials are not as good as those of non-metal materials. The outer surface of the hood should be smooth and coated with light-colored topcoat, which can reduce heat absorption. The inner surface should also be smooth and clean, minimizing wind resistance and avoiding the formation of vortices. Sound-absorbing materials should also be adhered to reduce working noise.

The above is a bit of the author's reflection on the design of the product's heat dissipation system. Maybe it's just a joke. In fact, the design of the "long robe" and the air duct design of the hood. The connotations of the two are interlinked, and both follow the scientific principle of survival of the fittest. Hopefully, the author's little understanding and insight can be of some help to product design and improvement.