ENGINEERING THERMODYNAMICS STUDY MATERIAL

Vishwatmak Om Gurudev College Of Engineering Thermodynamics DEC 2004 4. Liquid Octane at 30°C is burned with 400% theoretical air at 30°C in a steady flow process. Determine the adiabatic flame temperature. (10 M) MAY 2005 5. Ethane (C2H6) at 25°C is burned in a steady flow combustion chamber with 20% excess air at 127°C, but only 95% of the carbon is converted to CO2. If the products leave at 1200°K, calculate the heat transfer. The pressure remains constant at later. Use the following data: (12 M) (i) Enthalpy of formation (h0f) in kJ/k mol Ethane (g) = (— 84680) Carbon dioxide (g) = (— 393520) Carbon dioxide (g) = (— 110530) Water (g) = (— 241820) Water (L) = (— 285830) (ii) Enthalpy (h) in kJ/k mol at various temperatures V O G C E DEC 2005 6. A hydrocarbon fuel (C7 H16) has enthalpy of combustion — 4856920 kJ/kg mole. Find its value of enthalpy of formation. Take the values of enthalpy of formation of CO2 and H2O respectively as -393791 and —288136 kJ/kg mole. (12 M) Prof.S Venkatesh Rao 201

Vishwatmak Om Gurudev College Of Engineering Thermodynamics MAY 2006 7. One kg mole of methane gas (CH4) is burnt completely with 10% excess air in a constant volume container. Before combustion, both methane and air are at 25°C and 1atm. The combustion products are at 150°C at the end of combustion. Determine the heat transfer during the process. Given V O G C E (12M) DEC 2006 8. The products of combustion of an unknown hydrocarbon CxHy a have the following composition as measured by orsat apparatus CO = 8%, CO = 0.9%.,O2 = 8.8% and N2 = 82,3% Determine: (a) Composition of the Fuel (b) Air Fuel Ratio (c) Percentage excess air used (10M) MAY 2007 9. The dry products of combustion of hydrocarbon fuel have the following orsat analysis 8% C02, 01% CO, 08.8% 02, and 82.2% N2. Determine the actual as well as theoretical air-fuel ratio. The formula for hydrocarbon is of the form Cx Hy. Take molecular weight of air as 28.95. (12 M) 10. Fuel oil has following analysis by mass C — 85%, H2 — 12.5%, O2—2% and residue — 0.5%. The dry flue gas has following composition by volume — CO2—9%, CO — 01% O2 - 7.77%, N2 — 82.25%. Determine air fuel ratio. (12 M) Prof.S Venkatesh Rao 202

Vishwatmak Om Gurudev College Of Engineering Thermodynamics MAY 2008 11. Enthalpy of combustion at reference temperature T0 for benzene (C6 H6) is —3301000 kJ/ mole with the H20 in the liquid phase. Calculate enthalpy of combustion for the H20 in the vapour phase. (Take mfg = 2441.8 at reference temp. 25°C) (10M) DEC 2008 12. Liquid Octane C8 H18 is used in an internal combustion engine at steady state at the rate of 0.0024 kg/sec and is mixed with Stoichiometric air. The fuel and air enter at 25°C and 1 atm. Complete combustion takes place and products exhausts out at 600°C. The engine develops 40 kW. Determine the rate of heat transfer from the engine. (12M) MAY 2009 13. One kg mole of methane gas (CH4) is burnt completely with 10% excess air at constant volume container. Before combustion, both methane and air are at 200C and 1 atmospheric pressure. The combustion products are at 1500C at the end of combustion. Determine the heat transfer during the process. (12M) V O G C E DEC 2009 14. One kg of liquid octane (C8H18) is burnt completely with 50% excess air, in a constant volume container. Before combustion, both liquid octane and air are at 25 °C and 1 atmospheric pressure. The combustion products are at 1600 K at the end of combustion. Calculate the heat transfer per kg-mole of fuel. Use the following data :— Prof.S Venkatesh Rao (12M) 203

Vishwatmak Om Gurudev College Of Engineering Thermodynamics MAY 2010 15. Liquid octane C8H18 at 25°C is used as a fuel. Air used is 150% of theoretical air and is supplied at 25°C. Assume a complete combustion and the product leaves the combustion chamber at 1500 K. Calculate the heat transfer per kg mole of fuel. Use the following data (8M) V O G C E Prof.S Venkatesh Rao 204