An Otto cycle engine installed in a road vehicle has a volume compression ratio of 6 and provides a gas mileage of 15 mpg at the vehicle’s normal traveling speed of 40 mph. For purposes of this problem, the cycle can be assumed to be an ideal Otto cycle using air with fixed values of specific heats. The specific heat values are; ?? = 1004.0 ? ⁄?? ∙ ?, and ?? = 717 ? ⁄?? ∙ ?. Assume that the ratio of fuel mileage to cycle efficiency is constant. Evaluate the following, (assume that you have access to the fuel that will avoid problems such as auto-ignition at the proposed increased compression ratios): a. What gas mileage can be expected if the engine compression ratio is increased to 9? b. What gas mileage can be expected if the engine compression ratio is increased to 12? c. Based on this model, what is the feasibility of trying to achieve 30 mpg solely through an increase in the engine compression ratio?
An Otto cycle engine installed in a road vehicle has a volume compression ratio of 6 and provides a gas mileage of 15 mpg at the vehicle’s normal traveling speed of 40 mph. For purposes of this problem, the cycle can be assumed to be an ideal Otto cycle using air with fixed values of specific heats. The specific heat values are; ?? = 1004.0 ? ⁄?? ∙ ?, and ?? = 717 ? ⁄?? ∙ ?. Assume that the ratio of fuel mileage to cycle efficiency is constant. Evaluate the following, (assume that you have access to the fuel that will avoid problems such as auto-ignition at the proposed increased compression ratios):
a. What gas mileage can be expected if the engine compression ratio is increased to 9?
b. What gas mileage can be expected if the engine compression ratio is increased to 12?
c. Based on this model, what is the feasibility of trying to achieve 30 mpg solely through an increase in the engine compression ratio?
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