Creating an Energy Efficient Engine

Q. The above P-V diagram represents the thermodynamic cycle of an engine, operating with an ideal monoatomic gas. The amount of heat, extracted from the source in a single cycle is:

1. $P_o{V}_o$
2. $\left(\frac{13}{2}\right)P_o{V}_o$
3. $\left(\frac{11}{2}\right)P_o{V}_o$
4. $4P_o{V}_o$

Q. In a fuel cell, methanol is used as a fuel and $O_2$ is used as an oxidizer. The standard enthalpy of combustion of methanol is $-726{\text{kJmol}}^{-1}$. The standard free energies of formation of $C{H}_{3}OH\left(l\right)$, $C{O}_2\left(g\right)$ and $H_{2}O\left(l\right)$ are − 166.3, −394.4 and $-237.1{\text{kJmol}}^{-1}$ respectively. The efficiency of the fuel cell will be:

1. $96.8\%$
2. $66.2\%$
3. $41.3\%$
4. $85.1\%$

Q. Heat is transferred to a heat engine from a furnace at a rate of $80MW$. If the rate of water heat rejection to a nearby river is $50MW$,
determine the thermal efficiency for this heat engine.

1. 47.5 %
2. 27.5%
3. 37.5%
4. None of the mentioned