A house with a 15.3 × 103 ft2 floor area and 8.00 ft high ceilings is to be heated with propane. How m

Question

A house with a 15.3 × 103 ft2 floor area and 8.00 ft high ceilings is to be heated with propane. How many kilograms of propane would be needed to raise the temperature of the air inside the house from 59.0 oF to
72.0 oF ?. In this calculation your are ignoring the temperature of the walls etc.



The moloar specific heat of the air inside the house is 30.2 J mol −1 oC −1
The average density of air over this temperature range can be estimated to be 1.22 g/L.
The molar mass of air is 29.1 g/mol.
There are 28.317 liters in a cubic foot.
The molar heat of combustion of propane is −2220.047 kJ/mol

Answer 1

First compute the total energy needed:
Multiply 15.3 * 103 * 8. This is VF3, the air volume in ft^3.
Multiply VF3 by 28.317. This is VL, the air volume in liters.
Multiply the deg F temperature change (from 59 to 72) by 5/9. This is DTC, the deg C temp. change.
Subtract 32 from 59, multiply the result by 5/9, and add 273.15.
This is TK, the air temp in deg K.
Multiply 22.4 * (TK - 273.15). This is MVA, the volume of 1 mole of air at 59F.
Divide VL by MVA. This is MA, the number of moles of air.
Multiply MA by 30.2. This is J1A, the Joules of heat required to raise the air temp by 1 deg C.
Multiply J1A by DTC. This is TE, the total required energy in Joules.
Now compute the amount of propane needed to supply the total energy:
Divide TE by 2,220,047. This is MP, the number of moles of propane needed.
Calculate MWP, the molecular weight of propane.
Multiply MP * MWP / 1000. This is the answer, kg of propane required.

I hope you can do this easy math yourself, and some point-hungry weed doesn't come and do it for you..

Answer 2

Setting asside all the technical lingo. You need no less than 35,000 btu's to heat this area. Weither it be a 35,000 btu furnice or 2 17,500 btu open face heaters, this will get the job done. If you are using the open face heaters, may I suggest using the ceramic heaters and not the blue flame type. Blue flames use more fuel. Ceramics are more efficient.