Ideal Models of Engine Cycles

Differentiate between constant volume combustion and constant pressure combustion processes. Give examples.

How combustion efficiency of an IC engine is defined? Show the effect of fuel-air equivalence ratio ($\phi$) on spark ignition combustion efficiency.

Calculate the higher heating value of $CH_4(g)$. Consider bomb calorimeter is used. Given standard enthalpies of formation of $CH_4(g)$, $CO_2(g)$, $H_2O(g)$ and $H_2O(l)$ are $-74.87 \text{ MJ/kmol}$, $-393.52 \text{ MJ/kmol}$, $-241.83 \text{ MJ/kmol}$ and $-285.84 \text{ MJ/kmol}$, respectively. Given $T_o = 298.15 \text{ K}$ and $\bar{R} = 8314.3 \text{ J/kmol.K}$

Differentiate between indicated power and brake power.

How constant volume combustion and constant pressure combustion are differed from each other? Where do these combustion happen?

A four-stroke four-cylinder automotive engine develops 150 Nm brake torque at 3000 rpm. Assuming brake mean effective pressure to be 0.925 bar and mean piston speed to be 12 m/s. Find (i) brake power, (ii) displacement volume, (iii) stroke and (iv) bore.

What is the difference between scavenging and supercharging?

Why actual cycle is different from fuel-air cycle?

Calculate the higher heating value of $\text{CH}_4$. Assume the fuel is fully vaporized and bomb calorimeter is used. Standard enthalpies of formation of $\text{CH}_4(\text{g})$, $\text{CO}_2(\text{g})$, $\text{H}_2\text{O}(\text{g})$ and $\text{H}_2\text{O}(\text{l})$ are -74.87 MJ/kmol, -393.52 MJ/kmol, -241.83 MJ/kmol and -285.84 MJ/kmol respectively. Datum temperature $= 25^{\circ}\text{C}$, $\bar{R} = 8314.3 \text{ J/kmol.K}$.

Why actual cycle is different from fuel-air cycle?

What is combustion efficiency? How equivalence fuel-air ration affects diesel engine combustion efficiency?

Calculate the lower heating value of $\text{CH}_4$. Assume the fuel is fully vaporized and $\text{CH}_4$ is burned in a constant pressure process. Consider standard enthalpies of formation (at $25^\circ\text{C}$) of $\text{CH}_4(\text{g})$, $\text{CO}_2(\text{g})$, $\text{H}_2\text{O}(\text{g})$, $\text{H}_2\text{O}(\text{l})$ are $-74.87 \text{ MJ/kmol}$, $-393.52 \text{ MJ/kmol}$, $-241.83 \text{ MJ/kmol}$, $-285.84 \text{ MJ/kmol}$ respectively.

Why fuel-air cycle is different from actual cycle?

How does equivalence fuel/air ratio affect engine combustion efficiency?

Calculate the HHV of $CH_4$ considering the fuel is fully vaporized and bomb calorimeter is used. Standard formation of enthalpies for $CH_4$, $CO_2$, $H_2O(g)$ and $H_2O(l)$ are $-74.85$, $-393.5$, $241.82$ and $285.85$ kJ/mmol respectively. $R = 8.3143$ kJ/kmol-K.

Explain intake process of internal combustion engine for unthrottled operation ($P_i = P_e$), throttled operation ($P_i < P_e$) and supercharged operation ($P_i > P_e$).

Calculate the lower heating value of $\text{CH}_4\text{(gas)}$ when it is burned in a bomb calorimeter with air. The standard enthalpies of formation of $\text{CH}_4\text{(g)}$, $\text{CO}_2\text{(g)}$, $\text{H}_2\text{O(g)}$ and $\text{H}_2\text{O(l)}$ are $-74.87$ MJ/Kmol, $-393.52$ MJ/Kmol, $-241.83$ MJ/Kmol and $-285.84$ MJ/Kmol respectively. $\bar{R} = 8314.3\text{ J/Kmol.K}$, $T_0 = 298.15\text{ K}$