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Unique service:  Saving energy in fruit and vegetable refrigeration

Line of Busi-ness:

Industrial Refrigeration

Application: Fruit and Vegetable Cooling

Country / City: Germany / Wülfrath

Fluid: R507, R507A, R134a

Product: Ceiling unit cooler DHN, Wall/ceiling unit cooler GHN, Con-denser GVH

In two recent large projects for fruit and veg-etable refrigeration, the companies Frigotech-nik Handels GmbH, Wülfrath, in co-operationwith Kälte-Klima Peters from Meerbusch andGüntner, Fürstenfeldbruck, yet again broughtproof of their competence in the refrigera-tion of foodstuffs. In both cases, the buildingswere fitted with Güntner evaporators and con-densers. After commissioning of the systems,as a special, additional service, the wholesaler,together with ISS Krefeld (Engineering OfficeSven Schulte) offers his customers individualenergy-consumption analyses, thus promotingenergy- and cost-saving operation of the sys-tems. The refrigeration of fruit and vegetables

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in the import-export business is one of themost demanding areas in foodstuff refrigera-tion, because the quality of the most sensi-tive fresh goods must be reliably maintainedthroughout all transit stations. For the equip-ment of one completely new storage shed eachfor Rosenland Fruit Import in Mönchenglad-bach, Germany, and for the Günaydin fruit andvegetable export company in Alasehir, Turkey(see separate reference project "Günaydin - Fitfor Europe-wide export"), however, it was notthe value of the goods alone that made thehighest demands. The high volume of goods intransit required special energy- and cost-sav-ing equipment.

85 tonnes throughput daily

For the fruit importer Rosenland inMönchengladbach, the architectural office ofVouille fitted out a completely new warehousewith a total of 3,760 m2 of refrigerated floorspace and around 800 m2 of office space in on-ly eight months’ construction time, starting inMay 2002. Rosenland’s main product is trop-ical fruit, so the quality of the very perishablegoods must be assured both in storage and infurther transport. As a rule, the goods are de-livered at a temperature of 25 to 28 °C, makinggentle cooling down to +2 to +4 °C over a peri-od of 10 to 12 hours necessary. And at Rosen-land, these requirements apply to a through-put of 85 tonnes a day.

Steady storage temperature

When choosing the refrigeration equipment,the planning team decided on Güntner com-ponents throughout, supplied by interconnect-ed Bitzer semi-hermetic screw compressors.This has the advantage that each compressorcan be controlled individually in four stages viathe system’s PLC controls. The only refrigerantused is R507. A total of 700 kg of it are neededfor the whole system.

New warehouse for fruit importers Rosen-land in Mönchengladbach, Germany

So for the main store alone, eight dual dis-charge unit coolers type DHN 066D/37, ex-hausting to both sides, were selected. Opti-mised for a total power of 403.2 kW, this ver-sion ensures a continuous optimum room tem-perature, especially in large refrigerated rooms.Refrigeration expert Christoph Peters explains:“The compact construction of the units favoursoptimum utilisation of the storage space. Stor-age of fruit and vegetables also requires ex-tremely high humidity, so these componentshave a large heat exchanger surface, and causelittle draught. This means that little moistureis extracted from the air and the refrigeratedgoods, so that the latter stays fresh longer. Fur-ther decisive advantages are the hygienic de-sign and the high resistance to corrosion.”

Efficient hot-gas defrosting

To achieve time-saving defrosting process-es under operating conditions, Kälte-KlimaPeters used the DHN standard connectionsfor energy-saving hot-gas defrosting, whichis programmed in the controls as defrost-ing as necessary. Rosenland Fruit Import re-quires smooth-running logistics, so, in consul-tation with the architect’s office of Vouille inMönchengladbach, separate refrigeration ar-eas were created for delivery, consignment andcontingency.

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Güntner aircooled condenser (axial) GVH:Powerful, with a total capacity of 1,050 kW

IIn the contingency area, the Peters compa-ny mounted four GHN unit coolers, version051C/27, with hot-gas defrosting. In the deliv-ery area, four type S-DHN 066C/27 dual dis-charge unit coolers ensure the quality of theproduce. These units were specially adaptedfor processing rooms, where they provide qui-et, draught-free air flow. Their hygienic designfavours operation free of drips and corrosion,and easy, quick cleaning. In the working areas,an upstream pump and water heater ensureenergy- and cost-saving air-conditioning.

The aircooled condenser (axial) Type GVH092B/2x6n (D), which is mounted outside, pro-vides a total condensing capacity of 1,050 kW.

Optimum regulation

The core of the system is the controls. Thesehave been fitted with a Siemens S7 PLC, andwith an individual program from the ISS com-pany of engineer Sven Schulte in Krefeld. Thecontrol system is designed for the entire refrig-eration plant, and registers suction, air pres-sure and condensing pressure as analogue val-ues. If a sensor should fail, the system switch-es over to a redundant sensor. The analoguetemperatures registered are those of all rooms,switch cabinets and suction gas. The temper-atures are gathered via ELREHA MiniMEP da-ta loggers – devices that conform to the legalrequirements on the archiving of temperaturesin foodstuff storage and processing. Depend-ing on the ambient temperature, the defrostingof the evaporator is carried out with circulatedair or hot gas. In the latter case, the hot-gasdefrosting is stored for 30 days with date andtime. The triggering of the condenser is con-

trolled by pressure, and the speed of the fans isregulated. Should the speed regulator fail, thefans are regulated in stages directly, dependenton the pressure. The system stores both thecompressor run times and the switching puls-es for 30 days, allowing optimal savings in en-ergy costs to be achieved.

Secure online controls

Fitting the control system with a password-pro-tected modem provides additional service. Thismakes it easy to implement parameter se-curity, adjustment of the set-points and pro-gram alteration online. Faults in the plant aredisplayed in text messages at a user-friendlytouch screen. Every fault message is sent asan SMS to a registered mobile-phone number.The control system automatically distinguish-es relevant and irrelevant faults. A list of thelast 100 fault messages with timestamp can beviewed on site at the operator panel, or online.All system states can be reconstructed veryquickly at the display or online. Important plantparameters (pressures, machine run times perday, etc.) are also stored for a selected periodof time.

Quick amortisation through energy evalua-tion

As a special service ISS and Frigotechnik of-fer their customers, on request, an evaluationof the actual energy consumption in operation.Ten plant operators at present benefit from thisservice, including Rosenland and the fruit andvegetable exporter Günaydin. The operatingparameters suction pressure, oil temperature,room temperature, room humidity, condenserpressure and intake and outlet temperature areregistered at regular intervals, and evaluatedwith regard to optimum control. “This service isunique in the sector,” Frigotechnik Branch Of-fice Manager Penno confirms. “Experience hasshown that it is possible to keep below the orig-inal cost-efficiency calculation when the con-trols are optimised on this basis. So plant op-erators can significantly speed up amortisationof their investment.”

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Main cold store at Rosenland: 8 DHN 066D/37 dualdischarge unit coolers, total capacity 403.2 kW 

Special feature: Large heat exchang-er surface, .i.e. low dehumidification

This is important for fruit and vegetable re-frigeration:

• Right temperature level between +1and +4 °C with a relative humidity of95 %

• Cooling speed of items to be refriger-ated

• Heat to be removed per tonne ofgoods stored, e.g. apples:

° cooling phase 235 W° storage phase 8 W° heat removal per tonne 0,9 %

• Temperature-stable storage• Maintenance of quality through re-

duced transpiration• Use of modern technologies, e.g.:

° Güntner evaporators° mech./electrical injection

valves° Siemens SPC controls° optimised energy consumption

Source: C.-Dieter Penno, Frigotechnik HandelsGmbH, Wülfrath, Germany

Europe-wide: Wholesale and system plan-ning for refrigeration and air-conditioningequipment

Frigotechnik Handels GmbH is one of the lead-ing wholesale companies in Germany and Eu-rope in the refrigeration and air-conditioningsector. The company combines trading andservice functions on top of a solid, estab-lished company structure. Frigotechnik’s rangeof products combines tried products from na-tional and international manufacturers for theentire refrigeration and air-conditioning sector.In addition to sustained high, innovative prod-uct quality, the wholesaler’s quality standardsinclude long-term availability of the solutions,including accessories and replacement parts.Where necessary, the supplier manufacturescomplete system solutions in his own work-shops. Co-operation with experienced partnersin manufacturing and allied trades ensuresthat the solutions are professional and state-of-the-art. The offering of Frigotechnik is round-ed off by a comprehensive range of services,from personal consulting through storekeep-ing, delivery and collection services, to con-struction-site services.