knowledge deep freeze evaporator - pdf english.pdf
TRANSCRIPT
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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)
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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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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
Reg
alfe
st
Reg
alfe
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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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8Mas
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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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