What is the effect of cut off ratio on the efficiency of diesel cycle?
In diesel engines the fuel cut off ratio depends on the output and therefore unlike the otto cycle the efficiency of the diesel cycles depends on the output. When the cut-off ratio of diesel cycle increases, the air standard efficiency of the cycle is decreased when compression ratio is kept constant.
How the efficiency of diesel engine varies for different cutoff ratio?
9-53C Cutoff ratio is the ratio of the cylinder volumes after and before the combustion process. As the cutoff ratio decreases, the efficiency of the diesel cycle increases.
When cut off ratio is dash the efficiency of diesel cycle approaches the efficiency of Otto cycle?
For the practical cutoff ratio, the extra term in the efficiency formula of the Diesel cycle is always greater than one. The extra term in the efficiency formula of the Diesel cycle will approach unity when the cutoff ratio approaches unity, which is quite impractical.
How does cut off ratio affect the thermal efficiency of an air standard diesel cycle at fixed compression ratio and G )?
The cutoff ratio is the ratio of the volume after combustion to the volume before combustion. From the above equation, it is observed that, the thermal efficiency of the diesel engine can be increased by increasing the compression ratio, Ro, by decreasing the cut-off ratio, rc, or by using a gas with large value of γ.
Which cycle is more efficient with respect to the same compression ratio?
Explanation: Otto cycle is more efficient than Diesel cycle for a given compression ratio. 6.
What is the thermal efficiency of diesel engine?
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.
What is the efficiency of Otto cycle?
7.4. Variation of the normalized power output and the thermal efficiency of the irreversible Otto cycle with the compression ratio, γ = 1.4, ηcom = 0.85, and ηexp = 0.90.
What is the efficiency of Carnot cycle?
The efficiency of carnot’s engine is 50%.
What type of ignition system does a diesel engine use to ignite fuel?
compression-ignition engines
Diesel engines are sometimes called compression-ignition engines because initiation of combustion relies on air heated by compression rather than on an electric spark. In a diesel engine, fuel is introduced as the piston approaches the top dead centre of its stroke.
What would happened when the compression ratio is constant in a Diesel cycle?
In this case when the compression ratio is the same, more heat can be added in Otto cycle (at almost constant volume) than that of the Diesel (almost at constant pressure), the heat rejected to atmosphere is the same for both cycles, because of that Otto will have better efficiency than Diesel.
Is the Diesel cycle reversible?
4.7. 3.2 Internally Reversible Gas Power Cycles. The main three internally reversible gas power cycles are the Otto, Diesel, and Brayton cycles. All three cycles are suitable for internal combustion engines and therefore engine-driven power generation applications.