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Thread: Question about calculating BTU
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29-11-2010, 11:57 AM #1
Question about calculating BTU
Hi, I do have a couple of question, let's say I have a pond with 1000 liter of water and I'd like to bring the temperature down to 4 degree Celsius, how much BTU do I need? And how do I calculate the diameter and length of the caliper pipe?
Thank you in advance!
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29-11-2010, 04:42 PM #2
Re: Question about calculating BTU
It depends what temperature the pond is before starting cooling
1 BTU is the energy necessary for cooling 1 pound of water by 1°F.
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29-11-2010, 06:50 PM #3
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29-11-2010, 06:58 PM #4
Re: Question about calculating BTU
That's easy. Split systems are sold by the BTU/h, which is an awful habit and should be deemed as unlawful in EU
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29-11-2010, 07:29 PM #5
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29-11-2010, 08:06 PM #6
Re: Question about calculating BTU
One btu will change the temperature of one liter of water by 1.23 degrees C. So to cool 1000 liters from 15 to 4C will require removing about 9000 btu from the water. Unfortunately, I have no idea what a caliper pipe is.
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29-11-2010, 10:21 PM #7
Re: Question about calculating BTU
Caliper Pipe probably equals a capillary tube, use Dancap.
http://www.danfoss.com/BusinessAreas...ils/DanCap.htmBrian - Newton Abbot, Devon, UK
Retired March 2015
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29-11-2010, 10:27 PM #8
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30-11-2010, 07:27 AM #9
Re: Question about calculating BTU
Let's do it in metric.
1000 Kg x 1 Kcal/KgK x 11K = 11000Kcal = 43651 BTU.
If you want to cool it in one hour then you need a chiller by the capacity of 43651 BTU/h or 12.4 kW.
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30-11-2010, 11:15 AM #10
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01-12-2010, 11:29 AM #11
Re: Question about calculating BTU
Another question, is it possible to bring the temperature of 1000 liter of water down around 4-8°C with 9000 BTU chiller? Ambient temperature is around 30-31°C.
If it is, any tips and trick to do so? Or is it too much for a 9000 BTU chiller? Thanks and sorry for the basic question
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01-12-2010, 11:54 AM #12
Re: Question about calculating BTU
I think you mean BTU/H e not BTU.
Yes, it is possible, but instead of taking one hour, it will take 43651/9000= slightly more than 5 hours
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02-12-2010, 11:35 AM #13
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02-12-2010, 11:57 AM #14
Re: Question about calculating BTU
It means that the insulation is not enough or that the unit is not performing as declared.
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02-12-2010, 11:39 PM #15
Re: Question about calculating BTU
What are the dimensions of the pond? is it long and shallow having a large contact area with the air, or short and deep with a small contact area with the air, and what is the RH of the air? And what method of heat exchanger are you using? Ie a direct pump system thats capable of moving the total volume of water very quickly via a cooling tower then through a double walled evaporator, or an evaporator directly submerged in the pond, or a glycol/brine coil/loop submerged directly in the pond?
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03-12-2010, 09:54 AM #16
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03-12-2010, 11:27 AM #17
Re: Question about calculating BTU
It also depends at what conditions the cooling capacity is declared.
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03-12-2010, 04:23 PM #18
Re: Question about calculating BTU
Nonickname's calculation is correct. My unfamiliarity with SI led me to an error. Glad it was picked up.
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