Methane $\left(\mathrm{CH}_{4}\right)$ is burned completely with the stoichiometric amount of air during a steady-flow combustion process. If both the reactants and the products are maintained at $25^{\circ} \mathrm{C}$ and $1 \mathrm{~atm}$ and the water in the products exists in the liquid form, Find the heat transfer from the combustion chamber during this process. What would your answer be if combustion were achieved with $100$ percent excess air?

n-Octane $\left(\mathrm{C}_{8} \mathrm{H}_{18}\right)$ is burned with 50 percent excess air. Calculate the mass fraction of each product and the mass of water in the products per unit mass of fuel burned. Also, calculate the mass fraction of each reactant.

In a combustion chamber, ethane $\left(\mathrm{C}_{2} \mathrm{H}_{6}\right)$ is burned at a rate of 8 kg/h with air that enters the combustion chamber at a rate of 176 kg/h. Determine the percentage of excess air used during this process.

Methane $(CH_{4})$ is burned with 300 percent excess air at an adiabatic constant-volume container. Initially, air and methane are at 1 atm and $25^{\circ} \mathrm{C}.$ Assuming complete combustion determine the final pressure and temperature of the combustion products.

Calculate the higher and lower heating values of a coal from Utah which has an ultimate analysis (by mass) of 61.40 percent C, 5.79 percent $H_{2},$ 25.31 percent $O_{3},$ 1.09 percent $N_{2},$ 1.41 percent S, and 5.00 percent ash (noncombustibles). The enthalpy of formation of $\mathrm{SO}_{2}$ is -297,100 kJ/kmol.

Ethane $\left(\mathrm{C}_{2} \mathrm{H}_{6}\right)$ is burned at atmospheric pressure with the stoichiometric amount of air as the oxidizer. Determine the heat rejected, in kJ/kmol fuel, when the products and reactants are at $25^{\circ} \mathrm{C},$ and the water appears in the products as water vapor.

Determine the enthalpy of combustion of methane (CH$_4$) at 25$^{\circ}$C and 1 atm, using the enthalpy of formation data from the table. Assume that the water in the products is in the liquid form. Compare your result to the value listed in the next table.

Refrigerant-134a enters an adiabatic compressor as saturated vapor at 100 kPa at a rate of $0.7 \mathrm{m}^{3} / \mathrm{min}$ and exits at 1-MPa pressure. If the isentropic efficiency of the compressor is 87 percent, determine (a ) the temperature of the refrigerant at the exit of the compressor and (b ) the power input, in kW. Also, show the process on a T-s diagram with respect to saturation lines.

Refrigerant-134a enters an adiabatic compressor as saturated vapor at 100 kPa at a rate of 0.7 m^3/min and exits at 1-MPa pressure. If the isentropic efficiency of the compressor is 87 percent, determine (a) the temperature of the refrigerant at the exit of the compressor and (b) the power input, in kW. Also, show the process on a $T-s$ diagram with respect to saturation lines.

Hydrogen $\left(\mathrm{H}_{2}\right)$ is burned with 100 percent excess air that enters the combustion chamber at $80^{\circ} \mathrm{F}$, 14.5 psia, and 60 percent relative humidity. Assuming complete combustion, determine (a) the air–fuel ratio and (b) the volume flow rate of air required to burn the hydrogen at a rate of 40 lbm/h.

A fuel is burned steadily in a combustion chamber. The combustion temperature will be the highest except when (a) the fuel is preheated. (b) the fuel is burned with a deficiency of air. (c) the air is dry. (d) the combustion chamber is well insulated. (e) the combustion is complete.

A fuel mixture of 60 percent by mass methane $\left(\mathrm{CH}_{4}\right)$ and 40 percent by mass ethanol $\left(\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}\right)$ is burned completely with theoretical air. If the total flow rate of the fuel is 10 kg/s, determine the required flow rate of air.

A certain natural gas has the following volumetric analysis: 65 percent $\mathrm{CH}_{4},$ 8 percent $\mathrm{H}_{2},$ 18 percent $\mathrm{N}_{2},$ 3 percent $\mathrm{O}_{2},$ and 6 percent $\mathrm{CO}_{2}.$ This gas is now burned completely with the stoichiometric amount of dry air. What is the air-fuel ratio for this combustion process?

Methyl alcohol $\left(\mathrm{CH}_{3} \mathrm{OH}\right)$ is burned with 50 percent excess air. The combustion is incomplete with 10 percent of the carbon in the fuel forming carbon monoxide. Calculate the mole fraction of carbon monoxide and the apparent molecular weight of the products.