Liquid octane $($C$8$H$18)$ at $77$ degree F$,1$ atm enters a combustion chamber operating at steady state and burns completely with $50\%$ excess dry air entering at $120$ degree F$,1$ atm. The products exit at $1600$ degree F$,1$ atm. Determine the magnitude of the rate of heat transfer between the combustion chamber and its surroundings, in Btu per lbmol of fuel entering. Kinetic and potential energy effects are negligible