TEKNIK PERMESINAN KAPAL II (Minggu – 3) LS (3 SKS) Jurusan Teknik Sistem Perkapalan ITS Surabaya Gas Cycles Carnot Cycle T2 Heat Q 2 3 Work. The air-standard Otto cycle thermal efficiency is a function of compression ratio are adiabatic and for an adiabatic process the following p,V,T formula is valid. Air-standard efficiency of Otto cycle: It is defined as the ratio between work done during Otto cycle to the heat supplied during Otto cycle.


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Otto Cycle Derivation

Compression ratio r is the ratio of total cylinder volume to the clearance volume. Now that we know the basic terms, let us derive expressions for T2 and T3.


Otto cycle derivation expressions will be useful for us to derive the expression for air-standard efficiency of otto cycle. For finding T2, we take process and for finding T3, we take process As the piston is capable of moving along the cylinder, the volume of the air changes with its otto cycle derivation in the cylinder.

The compression and expansion processes induced on the gas by the movement of the piston are idealised as reversible, i. Energy is added to the air by the combustion of fuel.

Useful work is extracted by the expansion of the gas in the cylinder.

After the expansion is completed in the cylinder, the otto cycle derivation heat is extracted and finally the gas is exhausted to the environment. Useful mechanical work is produced during the expansion process and some of that used to compress the air mass of the next cycle.

The useful mechanical work produced minus that used for the compression process is the net work gained and that can otto cycle derivation used for propulsion or for driving other machines.

The relevant equations of state, internal energy and adiabatic process for air follow: However they are all functions of temperature, and with the extremely high temperature range experienced in internal combustion engines one can obtain significant errors.

In this problem we use a typical average cycle temperature of K taken from the table of Otto cycle derivation Heat Capacities of Air. We now go through all four processes in order to determine the temperature and pressure at the end of each process, as well as the work done and heat transferred during each process.

Note that the pressure P4 as well as P2 above could also be evaluated from the adiabatic process equation.

Chapter 3d - The First Law - Closed Systems - Otto Cycle Engines (updated 4/22/12)

We do so below as a vailidity check, however otto cycle derivation find it more convenient to use the ideal gas equation of state wherever possible.

As the compression ratio,increases, increases, but so does. If is too high, the mixture will ignite without a spark at the otto cycle derivation location in the cycle. The heat input is given by where is the heat of reaction, i.