Food packag ing company receives 3MW cooling system and further improves efficiency

Food packaging company receives 3MW cooling system and further improves efficiency

When Aqua Cooling Solutions recently installed a 3MW cooling system with pump controls based on Danfoss drives, the overall energy efficiency was very satisfactory right from the outset. However,, as part of the installation, Aqua Cooliing asked an engineer from Greenviille Electrical, an experienced Danfoss Drives partner, to visit the site to see if there was any way efficiency could be improved even further. Here’s more on the results of the installation and site visit

in a experienced D F lutio s rece ly installe

onDanfoss dri es, the overal energy ow

rt o th installatio , A co in syste fro oss D ives partn r, to visit the site to see i there wa ollowing a site visit by Greenville

carefully examined the sys be improved even further,

making a small change to configuration, was success

Electrical to a food packaging specialist to see if there was any way efficiency could the engineer temand, by

ful in achieving the drive

further valuable improvements in the efficiency of the cooling system.

Aqua Cooling Solutions recently designed, manufactured and supplied a high performance 3MWcooling systemfor a maj

ajormanufacturer of food packaging products. The systemincludes two sets of pumps, one of which comprises two 45kW pumps, the other two 55kW

kWpumps. All of

the pumps in the cooling systemare controlled by Danfoss HVAC drives. As originally configured, each of the

satisfactory froman oper a While this arrangement i andmaintain the pressure

pumps in a pair operated independently of the other, with closed-loop speed control based on feedback fromits own individual pressure transmitter. This arrangement was chosen so that if one of the pumps failed, the other could continue to operate in the system. s perfectly tiona l

standpoint, a consequence of controlling the pumps independently is that, formost of the time, they will be running at different speeds in order tomaintain the required pressure.

An alternative arrangement is to operate the pumps inmaster-followermode. This means that the drives for the two pumps are interconnected with one being designated as themaster drive and the other as the follower drive.With thismode of operation the follower drive tracks the speed of themaster, whichmeans that both pumps run at the same speed and the speed of both is varied simultaneously to maintain the required delivery pressure. Based on their analysis of the plant operation and their wide experience with pumping systems, the engineers from


Greenville Electrical and Aqua Cooling Solutions suggested that efficiency improvements could be achieved by reprogramming the drives in the cooling systemformaster-follower operation. The drive configuration they suggested was one inwhich themaster drive would, in normal circumstances, operate in closed- loopmode with its speed controlled by the ressure transmitter. Under the follower drive

these conditions, signal fromthe p

operates ni open-loopmode and accuratel y tracks the speed of themaster drive.

Figure 1: Figure 1:

An engineer visits the site to see if there was any way efficiency could be further improved

An engineer visits the site to see if there was any way efficiency could be further improved

Figure 2: Figure 2:

3MW cooling system ncludes two sets of pumps, one of whic comprises two 45kW ,

3MW cooling system iincludes two sets of pumps, one of which comprises two 45kW pumps the other two 5 kW pumps

kW th co rols b se

gy efficiencyw very satis factory right fromthe outset . n

lle improved even furth r. H re’sm re on th results of the installation and site visit

If themaster drive fails or is turned off for any reason, the follower drive automatically reverts to closed-loop operation with its speed controlled by the signal fromthe pressure transmitter. Thi s means that, as was the case with the original arrangement, the plant can

continue to operate even if one pump in a pair is out of service.

Before themodification was carried out, the pumps in the set with two 45kW usually had the pumps running at different speeds. Under these conditions, the total load was typically around 58kW.With the new configuration, both pumps operate most of the time at around 40Hz, and this results in total load in the region of jus t 45kW


kW. This is a saving of 13kW– or in percentage terms, almost 25%. This equates to an impressive energy saving of 113,880kWh per year, assuming that the pumps run continuously.


pumps, the other two 55 modifications in place, they both now kW pumps

The results frompumps in the set with two 55kWdrives were equally impressive. Like the pumps in the other set, before the modification these ranmost of the time at different speeds, and this resulted in a total load in the region of 85kW.With th e

typically run at 4Hz, and produce a total load of 65kW. Here the saving is 20kW which is again close to 25%. This time the anticipated energy saving is 175,200kWh per year.

kW, In these days of high and constantly

increasing energy costs, the savings gained by this exercise are very significant. By seeking advice fromDanfoss or an

approved competence centre about how to optimise energy efficiency is an equall y wisemove that can bring big energy saving benefits, bymaking anything fromsmall to large scale adjustments that work towards amore effective practice. Danfoss

, T: 01234 364621 ENERG MANAGEMEN ENERGY MANAGEMENT | SPRI SPRING 201 2017 15 15 kWdrives trica , a w s anyw y efficiency could be

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