How does the thermal efficiency of ideal Otto cycle change with the compression ratio of the engine?

an ideal thermodynamic combustion cycle, as follows: a compression at constant entropy; a constant-volume heat transfer to the system; an expansion at constant entropy; and a constant-volume heat transfer from the system. The thermal efficiency of the ideal Otto cycle increases with an increasing compression ratio. 2.

How does compression ratio affect thermal efficiency?

The thermal efficiency increases and the brake specific fuel consumption decreases with the increase of compression ratio. The higher compression ratio results in higher in-cylinder pressure and higher heat release rate as well as lower ignition delay.

What will be the effect on the efficiency of an Otto cycle having compression ratio 8 if CV increases by 1.6\% CV specific heat?

what will be the effect on the efficiency of an Otto Cycle having compression ratio 8, if C V increases by 1.6\% C V , specific heat? Otto cycle efficiency is given by, Therefore there is decrease in 1.026 \% of efficiency with increase in 1.6 \% specific heat at constant volume.

How is thermal efficiency of Otto cycle calculated?

In this equation, the ratio V1/V2 is known as the compression ratio, CR. When we rewrite the expression for thermal efficiency using the compression ratio, we conclude the air-standard Otto cycle thermal efficiency is a function of compression ratio and κ = cp/cv.

How does the thermal efficiency of an ideal Otto cycle change with the specific heat ratio of the working fluid?

How does the thermal efficiency of an ideal Otto cycle change with the compression ratio of the engine and the specific heat ratio of the working fluid? It increases with both of them. The fuel is injected into the cylinder in both engines, but it is ignited with a spark plug in gasoline engines.

Does compression ratio affect volumetric efficiency?

Higher compression ratios suffer less loss of volumetric efficiency as the pressure ratio increases. Of course as the pressure ratio decreases the lower compression ratio engines see a higher \% increase in volumetric efficiency.

What is the efficiency of diesel cycle?

A typical diesel automotive engine operates at around 30\% to 35\% of thermal efficiency. About 65-70\% is rejected as waste heat without being converted into useful work, i.e., work delivered to wheels. In general, engines using the Diesel cycle are usually more efficient than engines using the Otto cycle.

How do you calculate thermal efficiency with compression ratio?

Thermal Efficiency for Otto Cycle In this equation, the ratio V1/V2 is known as the compression ratio, CR. When we rewrite the expression for thermal efficiency using the compression ratio, we conclude the air-standard Otto cycle thermal efficiency is a function of compression ratio and κ = cp/cv.

What is the volumetric efficiency of compression?

The volumetric efficiency of a compressor is defined as the ratio of actual volume sucked by the compressor at the inlet to the swept volume. volumetric efficiency is given by, η v = 1 + c − c ( P 2 P 1 ) 1 n.

What is the thermal efficiency of the Otto cycle?

The air-standard Otto cycle thermal efficiency is a function of compression ratio and κ = cp/cv. Thermal efficiency for Otto cycle – κ = 1.4 It is very useful conclusion, because it is desirable to achieve a high compression ratio to extract more mechanical energy from a given mass of air-fuel mixture.

What is the compression ratio of Otto cycle engine?

In general, it is desired to have a high compression ratio, because it allows an engine to reach higher thermal efficiency. For example, let assume an Otto cycle with compression ratio of CR = 10 : 1. The volume of the chamber is 500 cm³ = 500×10 -6 m 3 (0.5l) prior to the compression stroke.

What is the relationship between thermal efficiency and compression ratio?

The air-standard Otto cycle thermal efficiency is a function of compression ratio and κ = cp/cv. It is very useful conclusion, because it is desirable to achieve a high compression ratio to extract more mechanical energy from a given mass of air-fuel mixture.

What is the relationship between specific heat and thermal efficiency?

For a given specific-heat ratio, thermal efficiency increases dramatically with increasing compression ratio at low values of r. Beyond r = 10, however, thermal efficiency curves flatten out, and the benefit of operating at higher and higher compression ratios lessens.