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skhan855
10-02-2015, 02:25 AM
Hi

I am new to refrigeration and looking to build up a cold room. I have different people saying different capacity and needs clarification to how much KW refrigeration capacity would be required for below:

Length 10.9728 meter
Width 12.192 meter
Height 7.3152 meter

Fruits to be stored: 205 Tons
Insulation: 100 mm Polystyrene

Fruits entering temperature 15 C
Target temperature 04 C
Time to cool down: 24 hours

Refrigerant to be used: R717

Would appreciate if someone can help me with this.

Regards
Salman Khan

alroy
12-02-2015, 07:55 AM
approx 62 kW

skhan855
12-02-2015, 12:06 PM
Hi

Many thanks for kind email.

I would appreciate if you can let me know how you calculate it

Regards
Saleem Khan

sterl
19-02-2015, 11:03 PM
Presuming this is a load-unload type of process, you might question your 24-hours available to cool but....

Total Heat to be Removed: Q

Q=m Cp Delta-T where
m is the mass of product
Delta-T is the temperature change you are trying to effect (11-deg. in this case...)
Cp is the sensible heat of the product: you only said fruit, the ASHRAE refrigeration manual has 44 Cp values for fruit: For fresh fruit, they basically fall between .82 and .91.

You then divide that number by the time (24-hours) to get a rate at which heat needs to be removed....

That is the big portion of the load...The enclosure load includes some transmission through the walls, maybe a few percent of the total; the heat associated with the internal equipment, which may simply be lighting, the heat and moisture yielded by the occupants...All that amounts to not a lot; the big item associated with the enclosure is the air exchange rate which is dependent on the size of the doors and how long it is open; and the condition (temperature and humidity) of the entering air. With a small enclosure and a big door in a wet climate, this may well effect your pull down rate because the finned coil is going to frost pretty quickly should there be a lot of air exchange and of course when its being defrosted its not refrigerating....

So get your product heat identified, then consider how you are going to load and unload that 205 tons...At that scale of enclosure, with that much product turnover, you are probably looking at 6 to 8 air changes a day...maybe more.

And I anticipate its higher than the 68 KW.