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Thread: Thermal Conductance (UA) ?
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31-01-2011, 08:30 PM #1
Thermal Conductance (UA) ?
Hi all,
I am new here. I am recently working on a school project which requires a temperature model of domestic fridge. I have gone through a few papers and I am sure I am going for a really simple model which applies the newton's law of cooling. In such model, all those papers use a parameter, Overall Thermal Conductance (UA), but I dont seem to be able to find the range of this UA value for domestic refrigerators. Some paper refer this value with the unit of (Btu/h·ft²·°F) and I think it is what is used in HVAC field.
I wonder if any of you know the range of this UA value and where can I find such value? I have tried to search the internet for a long time and dont seem to come across the useful information I need. Hopefully I can get some help here. Thanks a lot.
-klo
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31-01-2011, 10:25 PM #2
Re: Thermal Conductance (UA) ?
Hi klo and welcome to our forum.
Depending on where you are (imperial or metric) will determine which formula you use. Imperial (Btu/h·ft²·°F) = Metric (5.68W/m²K) or 1W/m²K = 0.176Btu/h·ft²·°F. These are for conductance (c). I think a cool room would be simpler due to the fridge often having the condenser and sometimes heaters on the outside.
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01-02-2011, 12:30 AM #3
Re: Thermal Conductance (UA) ?
Hmm.. I thought the UA refers to the fridge material? (the insulation or so?). In a paper I found this value ranges from 0.9 to 1.1 Btu/hr.ft2.°F. But there is no reference so that I am not sure if this range of value makes any sense at all. Any idea?? Thanks
-klo
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01-02-2011, 01:37 AM #4
Re: Thermal Conductance (UA) ?
Hi klo
Perhaps this calculation will help http://www.refrigeration-engineer.co...tion+cold+room understand UValues and other related parameters. I did a quick google search and didn't find much but I'm sure if you tried harder - maybe a manufacturer would be helpful.
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02-02-2011, 09:28 PM #5
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