Burning fuel and a motor's efficiency

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SUMMARY

The discussion focuses on calculating the efficiency of a motor that burns 20 liters of fuel per hour, with a combustion heat of 6.6E6 cal/liter, producing 40 horsepower (Hp). The conversion of horsepower to watts reveals that the motor outputs 107,424,000 Joules per hour. The total energy supplied by the fuel, converted from calories to Joules, amounts to 31,533,684 Joules per hour. The calculations demonstrate that the energy supplied by the fuel is less than the motor's output, indicating inefficiency.

PREREQUISITES
  • Understanding of horsepower to watt conversion (1 Hp = 746 W)
  • Knowledge of energy conversion from calories to Joules (1 cal = 4.186 Joule)
  • Basic principles of thermodynamics related to motor efficiency
  • Familiarity with fuel combustion heat values
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  • Research the principles of thermodynamic efficiency in motors
  • Learn about fuel combustion heat values and their impact on motor performance
  • Explore methods for improving motor efficiency
  • Study the relationship between fuel consumption and power output in engines
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Engineers, automotive technicians, and students studying mechanical engineering or thermodynamics who are interested in motor efficiency and fuel consumption analysis.

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Homework Statement


A motor burns 20 liter per hour. the fuel's combustion heat is 6.6E6[cal/liter] (i don't know if it's kcal or cal, but i assume it's cal). the motor produces 40 [Hp], what's the efficiency.

Homework Equations


1[Hp]=746[W]. 1[W]=[Joule/sec]
1[cal]=4.186[Joule]

The Attempt at a Solution


40[Hp]x746x3600=107,424,000[Joule/hour]
20[liter]x6.6E6[cal/liter]=13.2E7[cal/hour]
13.2E7[cal/hour]/4.186=31,533,684[Joule/hour]
The fuel supplies less power the the motor's output. not true
 
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1[cal]=4.186[Joule]

13.2E7[cal/hour]/4.186...
 
Thanks
 

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