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Thread: Chem Eng. student design help
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27-01-2010, 11:32 PM #1
Chem Eng. student design help
Hello, I am a senior design student and as part of my design I need to freeze a large amount of pharmaceutical over the course of a year, Approx. 1.5 million liters at -20°C. This design will never be built, just on paper. I needed a pall park capital cost and utility cost. Are there any references I can find that will have tables with very rough numbers? Actually designing the freezer system is out of the scope of the project, I just need a rough estimate on costs.
Thanks
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27-01-2010, 11:41 PM #2
Re: Chem Eng. student design help
There are a few other things we need to know.
Pharmaceutical = what?? all products have a specific
heat value per Kg (water = 4.19 kJ per Kg).
Will you put the product in the cold store at -20 or
will you be frezzing it from + temps down to - temps?
When you know your product and the temp the calculation
to store it is easy. The callculation to freeze the product is
a little bit more complicated be still easy enough.
Once you know how much work the system needs to do you
can then size the equipment to suit.
taz.
.
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27-01-2010, 11:56 PM #3
Re: Chem Eng. student design help
Hi Taz,
I am freezing an antibody suspended in water. I assume it will essentially have the specific heat of water. It will be entering not frozen, about 25°C. For these calculations, I think it is safe to say once the product enters at 25°C and will be frozen to -20°C for a year. I can calculate the energy needed. Is there an efficiency typically used for a large scale freezer?
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28-01-2010, 12:25 AM #4
Re: Chem Eng. student design help
Hello.
Ok you need to work out a few things.
Specific heat of water = Specific heat capacity, water: 4.187 kJ/kg
Specific heat of ice = Specific heat capacity, ice: 2.108 kJ/kg
You have 1.5 million ltrs or Kg of water that needs cooling from +20 to 0
Then you need to freeze ice from 0 to -20
Then you finaly need to hold the ice at -20 for 360 days.
Now your problem is time.
Do you want to freeze the water in 1 hour, 24 hours or 1000 hours because removing
the heat is done over time, storing the ice is simple and will take a fraction of the size
of equipment that it would take to freeze the water in the first place.
taz
.
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28-01-2010, 03:53 AM #5
Re: Chem Eng. student design help
Not really a biggy, 50grams a second (must be a busy sperm bank)
room would be at 50% full about 3000m3, load 30odd kw plus room losses say 20kw do not know where the theory place is) Plenty change out of US100,000
system COP about 2 so roughly 25kw powerdraw.
Unless time changes
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28-01-2010, 02:49 PM #6
Re: Chem Eng. student design help
ok I calculated hoe much energy I need to cool this stuff to -20. Cooling in 24 hrs should be sufficient. Also, I am not freezing all 1E6 liters at once. The product will be frozen over the course of the year, I will deposit about 8000L every 1.9 days.
Also, I need to calculate energy losses to environment to calculate the energy to keep the product frozen. I will assume ambient conditions for my location. Lets keep it at 20°C. How much energy loss is typical for a warehouse style freezer room?
Thanks all for the help!
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28-01-2010, 06:46 PM #7
Re: Chem Eng. student design help
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