Question

4. -/2 points SerPSE10 21.5.P.018. B My A gasoline engine has a compression ratio of 9.00 and uses a gas for which y = 1.40. (a) What is the efficiency of the engine if it operates in an idealized Otto cycle? (b) If the actual efficiency is 17.0%, what fraction of the fuel is wasted as a result of friction and energy losses by heat that could by avoided in a reversible engine? (Assume complete combustion of the air-fuel mixture.) Need Help? Read it

Answer 1

Solution: (a) The efficiency of the ideal gasoline engine is given by Nidal =1- , where r. is the compression ratio and y=”the ratio of specific heat of the gasoline (fuel) at constant pressure and constant volume, respectively. Therefore, for the engine that operate as the idealized Otto engine for which r = 9.00 and y=1.4 the efficiency is Maks Flip Flops and p = 0.5848 (in fraction) or 1... (1. os x 100 =58.8% (b). The efficiency means useful work. If n is the efficiency of an engine then fraction of useful energy is n and the fraction of the energy loss or the energy waste is 1-n. For a given engine n=17%= . Therefore, the energy loss or the fraction of the fuel wasted F, that can be 100 avoided in the reversible engine is F =1_17 _ 83 100 100 (Here, it is assumed that the energy conversion of the fuel is directly proportional to the mass of the fuel used to produce the energy.)