Efficiency of Heating Air vs Cooling
Efficiency of Heating Air vs Cooling
(OP)
If i have this correct, it takes 1BTU of heat to raise the temp of 1lb of water by 1 deg.
Is it the same for cooling, is the efficiency still the same, 1BTU to lower the Temp by 1 deg?
I am specifically looking for the equation for how many BTU's of heat required to heat 1 cubic meter of Air by 5deg.
Also then how to work the equation correctly for lowering the temp--cooling.
Thanks
Is it the same for cooling, is the efficiency still the same, 1BTU to lower the Temp by 1 deg?
I am specifically looking for the equation for how many BTU's of heat required to heat 1 cubic meter of Air by 5deg.
Also then how to work the equation correctly for lowering the temp--cooling.
Thanks





RE: Efficiency of Heating Air vs Cooling
Your definition of a BTU is essentially correct. Water at around 60 F has a specific heat of 1.0, but it's a bit higher at higher temperatures. However the specific heat of air is around .24 (.242 is probably more accurate) at temperatures below about 150 F.
To answer your question, you need to know the density of the air, which really depends on both the pressure and the temperature. Once you know the density, you can calculate the mass of air (in pounds mass) in a cubic meter. The amount of heat added or removed for a 5 degree F range is the same, as long as there is no water condensing in the cooling range. If your degrees are in Celcius, then the answer is 1.8 times as large.
Regards,
Speco
RE: Efficiency of Heating Air vs Cooling
Although the heats gained and lost are the same, the COP values may differ. See, for example,
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RE: Efficiency of Heating Air vs Cooling
RE: Efficiency of Heating Air vs Cooling
The thermomechanical process by which you heat or cool the air may have drastically different efficiencies, since they are often accomplished with different technologies. In the case of a residential home, the heating is done with burning natural gas, while cooling is done with compression and expansion of a refrigerant.
TTFN
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RE: Efficiency of Heating Air vs Cooling
RE: Efficiency of Heating Air vs Cooling
TTFN
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