© 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.


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.


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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