What is maximum temperature in Otto cycle?
An ideal Otto-cycle works between minimum and maximum temperatures of 300 K and 1800 K.
What is the formula of Otto cycle?
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 do you calculate heat supplied in Otto cycle?
In the Otto cycle, there is no heat transfer during the process 1–2 and 3–4 as they are isentropic processes. Heat is supplied only during the constant volume processes 2–3 and heat is rejected only during the constant volume processes 4–1.
What is the maximum efficiency of Otto cycle?
However the compression ratio of Otto cycle engines is limited by the need to prevent the uncontrolled combustion known as knocking. Modern engines have compression ratios in the range 8 to 11, resulting in ideal cycle efficiencies of 56% to 61%.
What is the formula for compression R ratio of the Otto cycle?
Explanation: This is the expression for efficiency of Otto cycle and rk=compression ratio=Vmax/Vmin.
What are the 4 stages of the Otto cycle?
The four-stroke Otto cycle is made up of the following four internally reversible processes: 1–2, isentropic compression; 2–3, constant-volume heat addition; 3–4, isentropic expansion; and 4–1, constant-volume heat rejection.
How is Otto cycle efficiency calculated?
Efficiency of Otto and Diesel engines vs compression ratios. (3.17) η = 1 – r 1 – γ r c γ – 1 γ ( r c – 1 ) , where r c ≡ V 3 ′ / V 2 (Figure 3.8) is called the cutoff ratio and is the expansion ratio during the combustion period.
Why is Otto cycle more efficient?
The simple answer is ,In the otto the energy available is fully used to raise the pressure in the cylinder. Higher the pressure implies larger work done. But in diesel cycle, Part of the energy is added only during the expansion, So it does not contribute to the work. Hence Otto cycle is more efficient.
What is K in Otto cycle?
Thermodynamic analysis of the Otto cycle produces a simple relationship among the thermal efficiency of the Otto cycle ηth, Otto, compression ratio r, and specific-heat ratio k: (3) The influence of compression ratio and specific-heat ratio on the thermal efficiency of the Otto cycle is shown in Fig.
How do you find the maximum theoretical efficiency?
Since temperatures are given for the hot and cold reservoirs of this heat engine, EffC=1−TcTh E f f C = 1 − T c T h can be used to calculate the Carnot (maximum theoretical) efficiency. Those temperatures must first be converted to kelvins.
What limits the use of high compression ratio in Otto cycle engines?
In practice, the working fluid in the SI engine is an air–fuel mixture during the compression process. This places practical limits on the compression ratio due to preignition of hydrocarbon fuels commonly used in SI engines.
Which is more efficient Otto cycle or Diesel cycle?
Although for a given compression ratio the Otto cycle has higher efficiency, because the Diesel engine can be operated to higher compression ratio, the engine can actually have higher efficiency than an Otto cycle when both are operated at compression ratios that might be achieved in practice.
How do you calculate the thermal efficiency of the Otto cycle?
Thus, for the Otto cycle, we have V2 = V3, V4 = V1, CR = V1 / V3, and PR = p3 / p1. The thermal efficiency of the Otto cycle is  Fig. 5.3. A p – V diagram of the Otto cycle. Applying the first law to the adiabatic compression process 1 → 2 gives T 1 T 2 = V 1 V 2 1 − γ. Thus, Eq. (5.13) may be rewritten as
What is the volume of the chamber in an Otto cycle?
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. For this engine all required volumes are known: V 1 = V 4 = V max = 500×10 -6 m 3 (0.5l)
What is the task number for the Otto cycle?
Otto Cycle Efficiency Task number: 1288 Determine the efficiency of the Otto cycle consisting of the four following processes: The adiabatic compression from the volume V1to the volume V2. The isochoric temperature increase from the temperature T2to the temperature T3.
What is the compression ratio of Otto cycle?
Compression ratio of Otto cycle is defined as the ratio of volume before expansion to volume after expansion In this cycle Compression ratio is generally 6 – 10. It is limited to 10 because of knocking in the engine.