Butane (c4h10) burns completely with 110% of theoretical air entering at 74°f, 1 atm, 50% relative humidity. the dry air component can be modeled as 21% o2 and 79% no on a molar basis. the combustion products leave at 1 atm. determine the mole fraction of water in the products, in lbmol(water)/bmol(products). there is a ±5% tolerance.

Apipe with an outside diameter of 15 cm is exposed to an ambient air and surrounding temperature of -20°c. the pipe has an outer surface temperature of 65°c and an emissivity of 0.85. if the rate of heat loss from the pipe surface is 0.95 kw per meter of length, the external convective heat transfer coefficient (h) is: (a) 12.5 w/m"k (b) 18.6 w/mk (c) 23.7 w/mk (d) 27.9 w/mk (e) 33.5 w/mk