The procedure to inflate a hot-air balloon requires afan to move an initial amount of air into the balloonenvelope followed by heat transfer from a propane burnerto complete the inflation process. After a fan operatesfor 10 minutes with negligible heat transfer with thesurroundings, the air in an initially deflated balloon achievesa temperature of 808F and a volume of 49,100 ft3. Next thepropane burner provides heat transfer as air continues toflow into the balloon without use of the fan until the air inthe balloon reaches a volume of 65,425 ft3 and a temperatureof 2108F. Air at 778F and 14.7 lbf/in.2 surrounds the balloon.The net rate of heat transfer is 7 3 106 Btu/h. Ignoringeffects due to kinetic and potential energy, modeling theair as an ideal gas, and assuming the pressure of the air insidethe balloon remains the same as that of the surrounding air,determine(a) the power required by the fan, in hp.(b) the time required for full inflation of the balloon,in min.
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