In an engine that approximates the Otto cycle, gasolinevapor must be ignited at

Question

In an engine that approximates the Otto cycle, gasolinevapor must be ignited at the end of the cylinder's adiabaticcompression by the spark from a spark plug. The ignition temperature of 87-octanegasoline vapor is about 430 oC and, assuming thatthe working gas is diatomic and enters the cylinder at21oC, determine the maximum compression ratio of theengine. Vmax / Vmin = ? A typical gas engine has a compression ratioof 8:1, but I can't seem to find the correct answer. I think I have to use the equations: e = 1 -(TL/ TH) = 1 - (VA /VB)-1 Thanks for your help! In an engine that approximates the Otto cycle, gasolinevapor must be ignited at the end of the cylinder's adiabaticcompression by the spark from a spark plug. The ignition temperature of 87-octanegasoline vapor is about 430 oC and, assuming thatthe working gas is diatomic and enters the cylinder at21oC, determine the maximum compression ratio of theengine. Vmax / Vmin = ? A typical gas engine has a compression ratioof 8:1, but I can't seem to find the correct answer. I think I have to use the equations: e = 1 -(TL/ TH) = 1 - (VA /VB)-1 Thanks for your help! The ignition temperature of 87-octanegasoline vapor is about 430 oC and, assuming thatthe working gas is diatomic and enters the cylinder at21oC, determine the maximum compression ratio of theengine. Vmax / Vmin = ? A typical gas engine has a compression ratioof 8:1, but I can't seem to find the correct answer. I think I have to use the equations: e = 1 -(TL/ TH) = 1 - (VA /VB)-1 Thanks for your help!

Explanation / Answer

The idea is that you want to take air at 21 deg C =   294 K     and compress itadiabatically to 430 deg C = 703 K

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For an adiabatic compression, the initial and final temperaturesand pressures are related by:

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