Knowledge deep freeze evaporator - PDF English.pdf

Gntner Knowledge

Gntner ...keep(s) your quality.

Evaporator fordeep-freezestore rooms

- Even air distribution in the cold store

- Even temperature in the rack area

- Low connected electrical load (D-mode)

35_0426_TK_Verd_Wissen_e_2.qxd 03.02.2006 10:28 Uhr Seite 1

2Optimum temperature distribution in the deep-freeze storage room: Gntner Evaporator for deep-freeze store rooms

Geometry of a deep-freeze stroage room with

3 deep-freeze storage room evaporators installed in

air inflow shafts.

The new deep-freeze storage room evaporator from Gntner: efficient performancecombined with a low speed and electrical power consumption.

Deep-freeze storage room with fully-automatic operation, with low thermal load of reefer cargo

air flows heat flows

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Hans Gntner GmbHwww.guentner.deD-82256 Frstenfeldbruck


High bays built to heights of up to 30 mare increasingly used to make full use ofthe area available in deep-freeze storagerooms. In these rooms, their height meansthat thermal currents occur that normallycause vertical temperature layering.Besides this, in these large rooms that areoften up to 80 m long it is also difficult todistribute the cold air throughout theentire room. Uneven temperature distri-bution and product quality reduction arethe result. Even air distribution can onlybe achieved with very high-powered fanswhen the usual air-cooling technology isused. The Gntner deep-freeze storageroom evaporator does not work againstthermal currents in the same way as con-ventional coolers. Instead it makes cleveruse of the natural thermal currents: Thecold air is blown downwards at lowspeed.There it spreads and forms a reser-voir of cold air.The heat carried in fromthe walls heats the air, which then risesand is again sucked in by the air coolerdirectly on the ceiling. Since the heat in adeep-freeze storage room does not occureverywhere but mainly forms on theouter walls, linear temperature layeringacross the entire room height does notoccur as one might expect. Rather, thelocally occurring warm air rises quicklyand forms a relatively thin warm layerunder the ceiling.With simulation calculations and mea-surements it has been possible to showthat a temperature deviation of onlymaximum 2 K occurs over the entire areain which the deep-freezed produce isstored.

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Temperature distribution in 2 vertical sections by the two external evaporators: an even store room

temperature, "warm air" only under the ceiling.

-25.90-26.05-26.20-26.35-26.50-26.65-26.80-26.95-27.10-27.35-27.40-27.55-27.70-27.85-28.00-28.15-28.30-28.45-28.60-28.75-28.90 C

Flow patterns (speed of the cooling air) in a vertical section by the middle evaporator: Cooling air spread

through the entire room.

0.500.470.450.430.400.380.350.320.300.280.250.220.200.170.150.130.100.080.050.030.00 m/s

Temperature distribution in one horizontal section at a height of 1 m. Creation of the cold air reservoir.

-25.90-26.05-26.20-26.35-26.50-26.65-26.80-26.95-27.10-27.35-27.40-27.55-27.70-27.85-28.00-28.15-28.30-28.45-28.60-28.75-28.90

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4Measurements in the cold store from 16th - 27th September 2004

Evaporator for deep-freeze storage rooms

Cold store:

Dimensions (L x W x H): 45 x 28 x 13 m, Commissioning area: 45 x 7 x 4 m

Room volume: 17,640 m2

Air circulation: 6.3 times per hour, referred to the empty room

Room temperature: -24 C

Lighting: 10 kW, switched on from 07.00 to 15.30

Forklifts: 3, each 7.5 kW, operating time of all forklifts combined approx. 12 hours/day

Defrosting: Hot gas

Accessoriews: Double-insulated tray, defrosting flap

Defrosting times: 1 x daily. Each refrigerator defrosts individually.

Measurement curves of

the temperature patterns

over 10 days (16 sensors)

Loading produce via the lock

Produce: Palleted fruitProduce handled during the measurements in pallets: IN: 1.280; OUT: 562Pallets: Fruits, weight 675 kg per pallet, pre-cooled

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5Flooded evaporator 3 x S-GHS 081E/212/20P

Power 50,0 kW Refrigerant NH3(1)

Volumetric air flow 37,160 m3/h Evaporation temperature -36 C

Air inlet -26.4 C 95% Pump rate 2.5 times

Air outlet -29.6 C 100%

Fans 2, 3-400V 50Hz Sound press. level 71 dB(A)(2)

Data per motor at intervals 1.0 m

Speed 890 rpm Sound power 89 dB(A)

Power 1.40 kW

Power consumption 2.7 (A)(3) Hair-frost 0.5 mm

Housing Galvanised steel HE pipes hot-galvanised

Exchange area 386 m2 Fins hot-galvanised

Fin pitch 12.00 mm Intake socket

Empty weight 1,600 kg

Unit length 3,896 mm

Unit width 1,260 mm

Unit height 1,290 mm

Number of suspensions 4

Evaporator for deep-freeze storage rooms with fitted defrosting flap.The flap is closed by a motor during the defrosting

phase. Fan housing with air blown out downwards..

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6Floor plan: Sensor placement

Vertical plan: Sensor placement

Cold store

Verladezone

Schleuse

24 2221

23

2519

20

Fhl

er10

-14

Fhl

er15

-18

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st

Reg

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Schnellauftor

Schnellauftor

Rega

lefa

hrba

r

Rega

lefa

hrba

r

quick-closing door

lock

loading zone

senso

r

por

table

shel

ves

quick-closing door

por

table

shel

ves

senso

r

Luftkhler

24

Luftleitblech

14

13

12

11

1019

18

17

16

15

22

21

23

20

12 m11 m

8 m

4,5 m

1 m

8 m

4,5 m

1 m

4m

13m

28 m

8,70

m

5 m 7 m

air cooler

air baffle plate

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Energy-saving operation

Since the Gntner deep-freeze storageroom evaporator supports the naturalthermal currents rather than workingagainst thermal currents, much lower airspeeds are possible than is the case withthe usual types of air coolers.

This enables slow-rotating fans to beused. In order to compensate for the redu-ced k value arising from this, the coolersmust be designed with a somewhat larger heatexchange area, but the fans require amuch lower drive power.

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Temperature layering in the deep-freeze storage room: Measured values over one day

Messwerte: gemittelt ber gesamten Messzeitraum (10 Tage).

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dGntner HeadofficeGermanyHans Gntner GmbH Industriestrae 14 D-82256 FrstenfeldbruckPhone +49 (0) 81 41 2 42-0Fax +49 (0) 81 41 2 42-155

heatXchangeA special publication from the Hans Gntner GmbH

The Gntner customer magazine was produced as a joint product by members of the Gntner group.

The statements represent the opinion of the authors. A legal obligation for theHans Gntner GmbH company cannot be derived from them.

The customer magazine is available inGerman and English language versions.

Masthead

Publisher:Hans Gntner GmbH Industriestrae 14 D-82256 FrstenfeldbruckPhone +49 (0) 81 41 2 42-0Fax +49 (0) 81 41 2 42-155www.guentner.de

Editorial office:Roland Handschuh, Dr. Franz Summerer,Martin Winzer

With support by:Wickertsheim Advertising Agency,Munichwww.wickertsheim.info

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Knowledge deep freeze evaporator - PDF English.pdf

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