© Photo | ebm-papst, Gernot Walter

A tough job in agriculture

A wide variety of ventilation, air-conditioning and drive technologies are used in the agricultural sector. They must perform well while consuming the least possible energy


High-tech on the farm? This may not fit our idyllic notions of a small agricultural operation. Nevertheless, today’s farmer makes use of satellite-guided tractors in the fields, fully automated milking machines for milk production, electronic ovulation monitors in the pig farm – and energy-efficient ventilation and air-conditioning in the barn. This helps not only to better cope with the all-important everyday factor of the weather, but also to save costs in the process – while also protecting the environment.

Barn climate control

Well ventilated poultry farm in Denmark

To succeed in animal husbandry, fattening and dairy production in different regions and in every season on a large scale, farmers make use of sophisticated barn climate control systems. In addition to the extremely diverse legal requirements regarding the size and type of assignment of the barns, each country has preferred architectures and different systems for each species, which have to be modified according to the stocking – the number of animals per square meter.

Cows can handle colder temperatures well. Therefore, their barns are usually outfitted with free ventilation in which the wind enters through openings in the wall and escapes via a chimney or flue in the roof due to thermal lift. Only on extremely hot summer days when the air does not move at all are “Cow Coolers” used, which are fans installed on the ceiling that provide circulation.

Poultry farmers use tunnel ventilation for fattening and egg production. In these systems, fans located on one front side of the barn suck the air from one side to the other through the barn. The fans have flaps installed that serve as an intake. In hot countries, these flaps are fitted with humidifiers that cool off the air. The system requires uniform flow of air through the barn. Axial fans are primarily used in this application.

Centrifugal fans are also used in special applications, such as drying chicken manure. In large chicken barns, the manure is evacuated, dried and used as fertiliser. Along with a large company of the agricultural production industry, ebm-papst has implemented a system of this type with energy saving fans.

For pig breeding and fattening the tasks are similarly demanding. For one, a controlled climate has a great effect on the well-being and performance of the sensitive animals. For another, substances that damage the building and health – known as room loads – must be discharged. Particularly stringent requirements exist for fresh air supply in heavily stocked barns. In summer, the ventilation must protect the animals from heat stress; in the winter, it must prevent condensation and excessive quantities of ammonia, hydrogen sulphide and carbon dioxide in the air – while heating up the room air.

Cross section of a pig barn

For pig farmers, what is called compartment ventilation is the ideal solution. In these systems, fans provide exhaust for individual sections of the barn via a chimney or flue. For this purpose, decentralised solutions exist in which the fans are distributed over the entire barn. In the centralised solution, fan groups are located in a pressure chamber and draw the exhaust air from the barn via ducts in the floor or ceiling. Additionally, air purification via filter systems is possible. This is used primarily by animal husbandry operations on the outskirts of town to keep unwanted odours for nearby residents to a minimum. Especially for this purpose, ebm-papst offers both the low-pressure versions of the fans, which are ideally suited for chimney and tunnel exhaust, and more high-performance fans that are used in these downstream purification systems. In these systems, the air is pushed through chopped biomass, bark or special granular material to absorb part of the odour.

Pig farming operations now also use exhaust systems that work with heat recovery, which are common in building ventilation systems. In doing so, the outflow of air gives off its heat to the inflowing air in cooler regions or in winter. This saves heating costs for the operation. Depending on the size and the configured minimum air rate, the animals cannot warm up the room with their own heat; additional heating is required. This is usually gas heating – which incurs corresponding costs.

Saving energy therefore is becoming increasingly important in agriculture. One factor is the EU fan directive that is taking effect. The agricultural fans in common use today – even in new buildings – are mostly voltage-controlled, consume a large amount of electricity and thus are inefficient. On the other hand, farmers are subject to increasing cost pressure, and GreenTech EC fans pay for themselves relatively quickly. Compared to conventional systems, enormous energy savings are possible over the course of the year.

Søren Pedersen checks the savings at the meters of the ventilation system of his pig barns

Søren Pedersen’s farm is a good example of this. The pig farmer from Bjerringbro, Denmark, had initially switched to GreenTech EC fans in one barn. After just one month, a direct comparison with another barn that is still being ventilated with conventional fans showed up to 70 percent less energy consumption. Therefore, Pedersen is now converting all his pig barns. This investment will have paid off for him in three years.

The barn ventilation is a real endurance test for the fans. In most of these applications, the output of the fans must be controlled with high accuracy, whether it be via temperature, humidity, carbon dioxide content or more than one of these parameters at once. EC technology has a significant advantage for demand-oriented air supply due to its integrated, highly accurate control and high efficiency, particularly in the partial load range. Therefore, it is ideal for use in each of the application areas – and pays for itself quickly.

The fans are also meeting another challenge: they withstand environmental stresses from aggressive substances and influences such as scraped-off bristles, skin parts and feed dust. For this purpose, ebm-papst engineers have worked with the customer to ensure specially sealed bearings, corrosion protection of the metallic parts, use of stainless steel as a reinforcing material and additional protection of the motor.

Storage

Cross section of a potato warehouse

Fans are also used in storing fruit and vegetables. Apple warehouses are a good example of particularly complex air-conditioning of facilities in which fruit is stored. The fruits are kept from perishing for an entire year by storing them close to the freezing point, with a maximum difference of plus/minus one degree. In addition, CO2 is injected into the air. These measures prevent the spoilage process.

Sales engineer Alexey Vinnik of ebm-papst Belarus visits the completely renovated potato warehouse

Storing potatoes is a bit simpler: the tuber rests in bulk on a lattice for six to eight months and is enveloped by an air flow to keep the temperature fluctuation over the course of day within a range of 0.5 degrees Celsius. This slows down the loss of moisture and thus the loss of quality. ebm-papst implements solutions of this type with Belarus-based AgroMaster. The air volume in the plant is metered with precision using sensors, software and GreenTech EC fans. Compared to the outdated standard in the ex-Soviet countries, the state-of-the-art plant not only increases the shelf life of the vegetable by some 45 percent, but also lowers energy consumption by one-half at the same time.

Tractor

Best air-conditioning for cabs in the Fendt 900 series

ebm-papst fans are also used outside buildings. So that a tractor has enough power even in heavy soil and on slopes, suppliers use engines with charge air cooling that increases the output and efficiency. In the new models from John Deere, the charge air coolers have an extremely flat axial fan mounted on the top, which was originally used in bus climate control systems. A couple of adaptations were required for the application in the tractor: for example, the emergency stop shuts down everything – including the cooling. However, the heated charge air cooler still radiates heat. Therefore, the specially selected material of the wall ring withstands temperatures as high as 130 degrees Celsius without deformation. In addition, the Mulfingen-based team modified its shape so that the fan develops both an axial and a centrifugal air flow and thus cools down the heated charge air cooler even more efficiently. The control system also has the additional “reversing the direction of rotation” feature, which allows it to purge the radiator grille of the charge air cooler clean of dirt.

The fan in the cab air-conditioning systems of Fendt and John Deere also has to withstand quite a bit: vibration, shock, dust and large temperature differences are a part of everyday life. All of this is intended to ensure that even in searing heat, the farmer can work on the field without suffering due to the weather.

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Axial fans

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