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Thread: Please help
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21-03-2009, 01:54 PM #1
Please help
Hi everyone!
I produce different frozen foods in New York and have been using regular walk in boxes for the last ten year, finally one month ago I bought a spiral freezer from Italy, they give me the box, spiral conveyor, evaporators, washing system for the belt and controls and of corse they install the whole think but the compressor is not included I have to buy it locally and install it. So I have contacted three different refrigeration companies and submitted them all the technical information that Italian company have sent me in connection with the refrigeration system, after a week I have received the quotation from the ref. companies and to my big surprise they all quoted me very different thinks, one said I need only 20 hp unit another said I need some kind of double system which will cost me somewhere 50k (just the unit, installation is another 20k) and the third company said that I need two 30hp units. I don't know what to do, and don't get me wrong I don't mind paying more its just I want to make sure that this system is going to work, so I found this website and hope someone will help me understand what I need. Bellow is the information that the Italians sent me, this is for one evaporator and the system will have two of them.
Thank you very much!
Operating ModeDirect Expansion Unit type Airmax II Model ILB562GType of calculation
Required Capacity 20.00 kW Margin 10.1 %
Calculated capacity 22.02 kWDimensionsLength 2580.0 mm Standard unit weight 330.0 kg
Height 1186.0 mm
Depth 960.0 mm
Packing Crate Shipping Volume 4.0 m³Thermal DataRefrigerant R404A
Air Temperature -35.0 °C / -37.4 °C
Relative humidity 80.0 %
Evaporating Temp. -42.0 °C
Temperature difference 7.0 KFan dataAir flow: 6.061 m³/s Number of Fans 2
Air throw 45.9 m Fan diameter 560.0 mm
Rotation speed 1220 rpm Voltage 400V
Total Nominal Power 2000.0W Power Supply 3pH
Total Nominal current(2) 3.60A Connection D
Total FLC (-30°C) 4.32 A
Sound Pressure Level (5.0 m) (1) 71 dB(A)
Sound Power Level 84 dB(A)
Coil dataTube material Copper Fin material Aluminium
Fin Spacing 12.0 mm Number of Circuits 20
Surface 155.7 m² Internal Volume 45.5 litres
Connections (In-Out) 35 - 64mm ConnectionSide Left - StandardFrame and caseworkStandard
Case material Galvanized steel painted
NOTES(1) By using the absorption area of 100m2 at distance of 5 m (Sabine)
(2) Nom. current at Tair=20°C. Variations occur due to different voltage or Tair
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23-03-2009, 11:24 PM #2
Re: Please help
well, a quick look at your specs shows that you need about 75749.5 btu's @ -43.6f
now, im no engineer and i dont work in imperial but i would say you would need about 30hp.. (2547btu = 1hp)
bear in mind that the are many variables in this and i would certainly be asking questions on how your fridgies have been making their selection!
that calculation is for one evaporator only and you will have to double that, so i would say that the company that quoted for 2 x 30hp units is close to the mark!!
NOTES1) By using the absorption area of 100m2 at distance of 5 m (Sabine)
(2) Nom. current at Tair=20°C. Variations occur due to different voltage or Tair
i would suspect your T air or Delta T is relative to condensor subcooling? the specs are a little sketchy.Last edited by fri11j; 23-03-2009 at 11:34 PM.
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25-03-2009, 08:22 AM #3
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Re: Please help
You need compressor of about 20kW cooling capacity at -42°C evaporation temperature and condensation temperature which is normal for your area.
Something like Bitzer semihermetic screw compressor HSN 6451-40-35P (with economizer 5K subcooling, 45°C condensation temperature and 10K superheat it is 19,34kW with R404A)
http://www.bitzer.de/eng/product/list/prod3/s-HSK-N/HSN6451-40
That is motor of 40 kW power (53,6HP). I really don't know what are they referring as 20HP or 30HP, cooling capacity or motor power.
If 20HP that is too low cooling capacity. And question is on what conditions they calculate that capacity.
If that is motor power, than definite too low for this type of compressor.
Could you post models they quoting to you.
I am not sure in your voltages so last 3 digits could be different for different voltages. This model is 60hz 3x380V, part winding start.Last edited by nike123; 25-03-2009 at 10:06 AM.
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07-04-2009, 06:17 PM #4
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Re: Please help
Some feedback would be polite.