Energy-effi­cient fans for refrig­er­a­tion tech­nology

From 2013 onwards, the ERP (eco-design) direc­tive will enter into force for fans, This direc­tive pursues in partic­ular the objec­tive of improving the energy effi­ciency of prod­ucts and thus to realise Euro­pean climate protec­tion targets. For many elec­tri­cally powered fans in use in refrig­er­a­tion and air-condi­tioning tech­nology, this means that they will have to satisfy the statu­tory limits stip­u­lated in this direc­tive. The result is a twin benefit: Impact on the envi­ron­ment is reduced and poten­tial energy savings are felt in the pocket of the consumer. The sample calcu­la­tions described below apply to refrig­er­a­tion and air condi­tioning equip­ment typi­cally found in super­mar­kets and they supply the neces­sary proof.

Since air-condi­tioning and refrig­er­a­tion systems are oper­ated with high duty cycles, energy savings are partic­u­larly notice­able in this area. However, there are consid­er­able differ­ences between appli­ca­tions. For example, the large condensers that are usually attached to the outsides of super­mar­kets have different require­ments to the fans that are used in refrig­er­a­tion coun­ters and refrig­er­a­tors. For each of these fields of appli­ca­tion, “customised” energy-effi­cient EC fans now exist that feature outstanding reli­a­bility, maximum effi­ciency and low-noise perfor­mance.

Better than what is “required”

The broad product port­folio of the motor and fan specialist ebm-papst includes energy-effi­cient fans for prac­ti­cally every power range that could be used in refrig­er­a­tion and air-condi­tioning tech­nology. Even today they already exceed by far the effi­ciency values stip­u­lated in the ERP (eco-design) direc­tive. Thanks to the successful inter­ac­tion of motor tech­nology, elec­tronics and aero­dy­namics, EC fans do not just convince with respect to their energy effi­ciency. They also work extremely quietly thanks to their opti­mised commu­ta­tion tech­niques and the aero­dy­namic config­u­ra­tion of the impellers. And on top of every­thing, they also convince with their dura­bility and reli­a­bility.

In refrig­er­a­tion and air-condi­tioning tech­nology, the change to modern EC tech­nology is worth­while on many accounts, espe­cially as the stip­u­la­tions of the direc­tive are not only ecolog­i­cally rational, they are also econom­i­cally highly inter­esting for the user. Even on compar­a­tively small refrig­er­a­tion units, the low energy consump­tion can bring about substan­tial savings compared to conven­tional fans that usually work with shaded-pole motors. One example is the so-called bottle coolers that can be found every­where where chilled drinks or snacks are sold, from kiosks or filling stations to super­mar­kets.

Energy-saving motors for refrig­er­a­tion units and coun­ters

Compar­ison of ESM/shaded-pole motor curves

If, for example, there are two fans fitted in a refrig­er­a­tion unit that are powered by conven­tional 30W shaded-pole motors, and if these are in oper­a­tion 12 hours a day, they will consume around 262 kWh in a year. However, if the fans were to be oper­ated with energy-effi­cient 10W EC motors from the energy-effi­cient ESM motor line from the ebm-papst product range, which boast the same air perfor­mance, this consump­tion would fall to about 88 kWh. There are two reasons for this: Firstly, the effi­ciency of the EC motor is vastly supe­rior. At the oper­ating point with a typical speed of 1300 rpm, the energy-saving motor has a maximum effi­ciency of more than 65%, allowing power input to be reduced by around 1/3 compared to a conven­tional shaded-pole motor. Secondly, less energy needs to be consumed from the very outset for the cooling process because less heat is lost to the envi­ron­ment during oper­a­tion.

From the resulting differ­ence in energy consump­tion of 174 kWh and assuming a price for elec­trical power of 11.69 euro cent/kWh (average elec­tricity price for industry in Germany, status January 2010 / Source: VEA, BDEW), there is an imme­diate annual saving of about 20 euro for each refrig­er­a­tion unit. The energy-saving solu­tion thus enables payback periods of less than 12 months. That makes this invest­ment worth­while not just for the envi­ron­ment, but also for the wallet of the user, espe­cially when the compa­rably long service life of the EC fans (approx. 40,000 oper­ating hours) is taken into account.

Savings poten­tial by the metre and straight­for­ward conver­sion

Energy-effi­cient tech­nology for refrig­er­a­tion coun­ters: energy-saving fans as a system solu­tion for refrig­er­a­tion coun­ters (left), IQ motors allow a straight­for­ward 1:1 exchange of the conven­tional shaded-pole motors for effi­cient cooling (right)

The more fans there are in oper­a­tion, the greater the savings poten­tial. Refrig­er­a­tion coun­ters are a good example. There are usually two fans for every metre in length. In a typical super­market, there are some 100 m of refrig­er­a­tion coun­ters, making 200 EC energy-saving fans of size 200. The energy saving compared to conven­tional shaded-pole motors is 70%, equating to 38 MWh per year. For the envi­ron­ment, this means more than 22 tonnes less CO₂ being produced on the basis of today’s energy mix. At the same time, the user will save more than 4,400 euro at an elec­tricity price of 11.69 euro cent/kWh.

By no means are users only able to benefit with new instal­la­tions. A conver­sion of existing instal­la­tions is possible and straight­for­ward. In this case, ebm-papst offers energy-effi­cient iQ motors, which are mechan­i­cally compat­ible with existing shaded-pole motors, and which have a high effi­ciency of up to 65% and the same instal­la­tion dimen­sions, allowing a straight­for­ward 1:1 exchange. Axial impellers with a diam­eter of 154 to 254 mm can be fitted in the same way on the iQ motor to create an energy-effi­cient solu­tion. The intel­li­gent elec­tronics regu­late voltage fluc­tu­a­tions so that the speed remains constant. Today, count­less well-known super­market chains are making use of this ecolog­i­cally and econom­i­cally rational 1:1 exchange option.

High-perfor­mance energy-saving fans for condensers and evap­o­ra­tors

The indi­vidual curves illus­trate the power input of controlled AC/EC motors in compar­ison

Compa­rable energy savings can be achieved in many other appli­ca­tions. For example, ebm-papst has set stan­dards with its energy-effi­cient HyBlade® fans for condensers and evap­o­ra­tors. Thanks to modern EC tech­nology and aero­dy­nam­i­cally opti­mised vane geom­etry, the EC fans, which are avail­able in sizes 172 to 990 mm diam­eter, convince with energy savings of up to 50% compared to AC fans. This applies not only in full-load oper­a­tion, but also and espe­cially in partial-load oper­a­tion. In addi­tion, the speed can be controlled for EC tech­nology. In other words, it can be adjusted to the respec­tive cooling require­ments, which provides further poten­tial savings. The result is substan­tially lower energy costs which are quickly felt in prac­tical oper­a­tion. The different curves illus­trate the power input of controlled AC/EC motors in compar­ison. In all speed ranges, energy costs are vastly lower with EC motors than with voltage-regu­lated or frequency-inverter-fed asyn­chro­nous motors. Depending on require­ments, between two and twelve of these fans are typi­cally used in such condensers.

Example of a schematic illus­tra­tion of compo­nents on a condenser

If you take a condenser with six HyBlade® axial fans of size 800 with EC tech­nology and compare these with six AC axial fans in the same power cate­gory, each with an air perfor­mance of 11,000 m³/h at 85 Pa, the six AC fans will need a total of 5,400 W, while the EC fans will have a power input of just 3,900 W. In this instance, the EC fans consume a total of 1,500 W less energy, repre­senting a saving of 28%. Further savings can be achieved by simply networking the EC fans via a BUS system, linking them to the higher-order manage­ment systems (see Fig. 7). Low noise levels, dura­bility and the low weight resulting from the robust plas­tics used are further bene­fits of these axial fans. In addi­tion, the inte­grated power elec­tronics are config­ured for country-specific mains volt­ages, allowing world­wide use, regard­less of whether the power frequency is 50 or 60 Hz.