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 .
Which of the following lists the four steps of the Otto cycle?
The four processes that make up the Otto cycle are (1) isentropic compression, (2) v = constant heat addition, (3) isentropic expansion, and (4) v = constant heat rejection . ... Because high compression ratios cause engine knock.
What are the major processes in the air standard Otto cycle?
The Otto cycle is an air-standard cycle which approximates the processes in petrol or diesel engines. It is based on constant volume heat addition (combustion) and heat rejection processes, and isentropic compression and expansion .
What is ideal Otto cycle?
In the ideal Otto cycle the fuel-air mixture is introduced during the induction stroke and compressed to a much lower compression ratio (around 8:1 ) and is then ignited by a spark. The combustion results in a sudden jump in pressure while the volume remains essentially constant.
What does air standard Otto cycle comprise of?
25. The air standard Otto cycle comprises a two constant pressure processes and two constant volume processes b two constant pressure and two constant entropy processes c. two constant volume processes and two constant entropy processes d.
Which cycle has more efficiency?
Explanation: Otto cycle is more efficient than Diesel cycle for a given compression ratio. 6. For constant maximum pressure and heat input, the air standard efficiency of the gas power cycle is in the order.
What is the difference between Otto cycle and Diesel cycle?
Otto cycle is used for petrol or spark ignition engine while diesel cycle is used for diesel or compression ignition engine. The main difference between Otto cycle and Diesel cycle is that in Otto cycle heat addition takes place at constant volume and in diesel cycle heat addition takes places at constant pressure.
What is constant pressure cycle?
CONSTANT PRESSURE CYCLE 95. COMBUSTION EFFICIENCY AND CLASSIFICATION. The liberation of heat energy in a gas engine depends for its. efficiency upon several conditions that can exist prior to ignition and. during the combustion period.
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.
What is Otto cycle with diagram?
The idealized diagrams of a four-stroke Otto cycle Both diagrams: the intake (A) stroke is performed by an isobaric expansion, followed by an adiabatic compression (B) stroke. ... The cycle is closed by the exhaust (D) stroke, characterized by isochoric cooling and isobaric compression processes.
What is K in Otto cycle?
Thermal Efficiency Derivation
A typical value for an air/fuel mixture is k = 1.35 .
What is meant by Otto cycle?
The Otto Cycle, describes how heat engines turn gasoline into motion . Like other thermodynamic cycles, this cycle turns chemical energy into thermal energy and then into motion. The Otto cycle describes how internal combustion engines (that use gasoline) work, like automobiles and lawn mowers.
What is Otto cycle process?
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 .
Which cycle is more efficient Otto or Diesel?
6 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.
Is Carnot cycle adiabatic?
The Carnot cycle consists of the following four processes: A reversible isothermal gas expansion process. ... A reversible adiabatic gas expansion process . In this process, the system is thermally insulated.
How do you calculate effective pressure?
Calculated from in-cylinder pressure over intake and exhaust portions of engine cycle (360° in a four-stroke, 0° in a two-stroke). Direct measurement requires cylinder pressure sensing equipment. PMEP = IMEP g – IMEP n .
