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Hitbychance
02-03-2009, 02:22 PM
Hey everyone let me break this down: I am designing an air conditioning system for a 450 x 450 foot building. It will be used for the storage of fruits and vegetables. The building breaks up into three rooms, each at a different temperature and humidity. I have calculated the amount of refrigeration i need in tons of refrigeration and i came out with numbers such as 1020 tons.
MY first question is, does that sound reasonable?
Also i researched and found out you should have 20 to 40 cfm per ton of produce and since there are 148 996 tons of produce in one room picking 30 (mid range) gives me a needed air flow rate of 4,469,889 CFM any ideas on what i should do?

TXiceman
02-03-2009, 03:51 PM
First off, A/C and refrigeration have two different set s of rules. With fruits and veggies, you need to be concerned with the heat of resperation and products like apples give of ethlene gas which causes other fruits to ripen faster. If you want tosee this, stick and apple in a plastic bag full of green bananas.

You need to go on the Larkin, Bohn or Krack sites and get a copy of their load estimating procedures. Since this is a first time for you on thid type load calculation, I would suggest it do the preliminary or rough calcs by hand and see what you are doing.

Depending on the entering product load, air infiltration, door opening, people entry and lighting, I would expect a lot less load.

Resources:
http://www.ishrae.in/journals_20042005/2005july/article06.html

http://www.elitesoft.com/web/newsroom/refrig1.htm

http://www.fao.org/documents/show_cdr.asp?url_file=/docrep/003/v3630e/V3630E09.htm

http://www.ba.ars.usda.gov/hb66/012heat.pdf


But you can not treat it as an air conditioning problem.

Ken

Hitbychance
02-03-2009, 04:53 PM
I have taken heat of respiration into account, and also ethylene control, if i were to omit my heat of respiration calculations i would only need a 70 ton unit. I have done all my calculations on paper and have included everything such as: conduction through walls, infiltration, lighting, people, machines.. etc.