Find out about the wall construction of the cabins of large commercial airplanes
ID: 1713621 • Letter: F
Question
Find out about the wall construction of the cabins of large commercial airplanes, the range of ambient conditions under which they operate, typical heat transfer coefficients on the inner and outer surfaces of the wall (including windows), and the heat generation rates inside. Determine the size of the heating and air-conditioning system that will be able to maintain the cabin at 20°C at all times for an airplane capable of carrying 400 people. Find out about the wall construction of the cabins of large commercial airplanes, the range of ambient conditions under which they operate, typical heat transfer coefficients on the inner and outer surfaces of the wall (including windows), and the heat generation rates inside. Determine the size of the heating and air-conditioning system that will be able to maintain the cabin at 20°C at all times for an airplane capable of carrying 400 people.Explanation / Answer
Wall construction of cabins of large commercial airplanes:-
Walls of cabins of commercial planes are constructed with fire retardant materials. Especially, sidewalls, stowbins and stowage compartment walls are constructed with use of such materials. Fire retardant insulation is used to keep outside fire away from airplane body. Generally, all these materials are light weight, so that it will not increase dead load of airplane, resulting in increase of carrying capacity of airplane.
Range of ambient conditions inside airplane:-
Partial pressure of oxygen is kept around 21 kPa. Cabin pressure is kept between range of 75-101 kPa. Temperature inside cabin ranges from 20-27°C.
Heat transfer coefficient on the inner and outer surfaces of wall & heat generation rate:-
About 74.1% heat is generated by passengers inside airplane. Ratio of this heat transfer of convection to radiation is 7:3.
effective emissivity of heat= 4.87 x 10^-8 kcal/hr.m2.°K^4
Considering 2000 sq.ft. 4 tiers in an commercial airplane, so total area is 8000 sq.ft. Divide it by 500 will give you 16.
16 x 12000 multiplication will be 192000
192000 + 400*380 = 344000 Btu
& for 50 windows 50*1000=50000Btu
means total of 394000 Btu capacity of air conditioning. 1 tonne AC unit is capable of 12000 Btu capacity. Which means 30 to 33 AC systems will be required to maintain 20°C capable of carrying 400 people.
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