Heating Room Calculation

[purplehaze2004]

hi guys,

looking for some help double checking my calculation.

i want to heat a room in the Plant to 130F (sterilization process). The temp of surrounding rooms is 70F. If my room dimensions are LxWxH = 178'x69'x20', the cubic volume of my room is 245,640.

Delta T=60F

We know 1 BTU is sufficient to heat 55cu.ft of air by 1F.

I've calculated 21.8 BTU/sq.ft is required. However, I'm not sure how to calculate the BTU/HR required (I calculated a really large value that seems ridiculous) so that I can spec out & purchase the appropriate electrical heaters to accomplish the job.

Any help is appreciated...

 

[IRstuff]

BTU/hr is the RATE, so how fast do you want to heat it up?

And, don't forget that as you heat it up, there will be thermal losses to the surroundings that the heater must also supply.

TTFN

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[purplehaze2004]

IRstuff

within a couple hours would be ideal.

 

[chicopee]

Figure out the heat loss thru walls, ceiling and floor + heat requirement for air infiltration thru cracks and whenever your open the door to remove sterilized productss+ heat requirement for whatever item you intend to sterilize.
The heat loss thru the structure will be in BTU/HR; Heat requirement for infiltration can be done by knowing some constants or by estimating the mass flow rate of the air and the result will be in BTU/HR; the heat requirement to sterilize will require a time element to determine the rate of temperature rise in the items in order to get BTU/HR during the batching process and for continuous process mass rate of the items to be sterilized will be required for a BTU/HR determination.

 

[purplehaze2004]

Chicopee,
I understand the info you're requesting, but don't have all of it. Can't I simplify this down and just make some assumptions? I found a site online Heater Shop that provides a BTU calculator.....It's calculating 4,605,750 BTU/HR based on the information I originally stated. That's seems HUGE! Then again, the volume of the room is quite large!.......

 

[sspeare]

Please see the attached PDF file. You seem to be hung up on "rules of thumb." Using "Rules of Thumb" is no way to design. In the attached calc, I tried to keep to the basics. Hope this helps.

 

[purplehaze2004]

great! got it. understand. appreciate greatly you spending time putting this together, sspeare.

 

[sspeare]

Glad it worked out. Watch out for those rules of thumb. They can hurt you. Go back to the basics.