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ideal air standard otto cycle
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AIR STANDARD CYCLE:

In true sense, internal combustion engines in which combustion of fuels occurs inside the engine cylinder can not be defined as cyclic heat engines. The temperature generated during combustion is very high so that engines must be water cooled to prevent the damage of the engine due to thermal shock. The working fluid here is a mixture of air and fuel that undergoes permanent chemical changes due to combustion and the products of combustions must be exhausted and driven out of the cylinder so that fresh charges can be admitted. Therefore, it does not complete a full thermodynamic cycle.

A real thermodynamic analysis of such an engine quite complex. Hence, we simplified the operation of an I.C. Engine by introducing somewhat idealized version of a real thermodynamic processes occur inside an IC Engine, and this idealized thermodynamic cycles are called "Air standard cycle." In an air standard cycle, a certain mass of a perfect gas like air operates in a complete thermodynamic cycle, where heat is added and rejected reversibly with external heat reservoirs, and all the processes in the cycle are reversible. Air is assumed to behave like a perfect gas, and like a perfect gas, its specific heats are assumed to be constant (although they are certain functions of temperature). These air standard cycles are conceived in such a manner that they may correspond to the operations of internal combustion engines.

Although, there are numerous such air standard cycles, the important of them are

a) Otto Cycle (used for petrol engine)
b) Diesel Cycle (used for diesel engine)
c) Mixed, limited pressure or Dual Cycle (used for hot spot engine)
d) Stirling Cycle
e) Ericsson Cycle

To make the analysis simpler, certain assumptions are made during the analysis of air standarad cycle. They are as following,
i) The working substance is a perfect gas obeying the gas equation pV = mRT.
ii) The working fluid is a fixed mass of air either contained in a closed system or flowing at a constant rate round a closed cycle.
iii) The physical constants of the working fluid will be those of air.
iv) The working medium has constant specific heats.
v) The working media doesn't undergo any chemical change throughout the cycle.
vi)


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