Arntjen - Centrifugal Big Fan

Those who implement the structural means necessary to avoid high shed temperatures, such as large-surface side openings, large shed volumes thanks to high eaves, a steep enough roof pitch, and an insulated roof membrane, can prevent the temperature inside the shed from exceeding the temperature outside. However, the cows require additional active cooling in the summer when daily temperatures rise above 20° centigrade. Such cooling is implemented by centrifugal fans. They provide the animals with relief from the heated atmosphere. If excessively dry, the air should be deliberately humidified.

Freely suspended centrifugal fans Fans with a diameter between 0.6 m and 2 m and powered directly or by a V-belt transport a stream of air along the length of the shed. They are hung vertically above the cows. Small fans must operate at higher speeds in order to generate a circulation that can still be felt after a distance of 10 meters. However, high speeds also require more electric energy. In the medium term, a small number of large fans is, therefore, more cost efficient than smaller size fans. In the summer time, cows can handle wind speeds between 6 m/s and 7 m/s while a sufficient cooling effect is already achieved at a wind speed of 1-2.5 m/s.

The downside of such a system is that it causes fairly high energy costs as many motors translate into great energy consumption due to the motors` own energy requirements. More extensive air movements also result in a greater noise level. Installing the fans is as easy as it can be.
An alternative option are oversized ceiling fans blowing a fresh breeze into the shed. This option involves fans with a diameter between 3 m - 7 m which are suspended in the center of the shed and used for circulating the air. An air current directed to flow down hits the ground and escapes towards all sides. The generated horizontal wind provides cooling to the animals at an air speed of 1 m/s - 2.5 m/s. Thanks to the low fan speed (75-140 rpm) the air is circulated in a very energy efficient manner. The magnet motor of an Arntjen® Fresh Air fan has no gearbox (no oil check) and has approximately the same power consumption as a small circulating fan. Regardless, the fan is capable of moving a significantly greater volume of air thanks to its gearless drive and affords the operator energy savings of up to 85%

Due to the long operating times of the fans the associated electricity costs are a decisive factor in the economic efficiency calculation. In contrast to small, freely suspended centrifugal fans, oversized ceiling fans circulate the entire air volume present in the shed. This type of circulation offers additional benefits: Heat will not be given an opportunity to become trapped under the roof; since they avoid vertical air movements, birds and flies will be kept away. Unlike their smaller counterparts which operate at high blade speeds and create a humming noise that dominates the entire shed, oversized fans run almost completely silently. If equipped with an infinitely variable control, the oversized fans can also be used during the winter time. When set to a low speed, the fans will push the heat produced by the animals back down, i.e. where the heat is needed during the cold season of the year.