How Efficient is a 100-hp Car Engine Compared to Carnot Efficiency?

How many watts go into moving the car, and how many joules and kcal are exhausted in 1 hour?In summary, a 100-hp car engine operates at 15% efficiency, with a cold-temperature reservoir of 85 degrees Celsius and a thermal intake temperature of 500 degrees Celsius. The Carnot efficiency can be easily calculated, and the engine is achieving a fraction of the maximum possible efficiency. The remaining energy goes into moving the car, with the rest being exhausted in the form of joules and kcal in 1 hour.
  • #1
mmg0789
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A 100-hp car engine operates at about 15 percent efficiency. assume that the engine's water temperature is 85deg C is its cold-temperature (exhaust) reservoir and 500deg C is its thermal "intake" temperature (the temperature of the exploding gas/air mixture)

a)calculate its efficiency relative to its maximum possible (Carnot) efficiency

b) estimate how much power (in watts) goes into moving the car, and how much heat, in joules and in kcal, is exhausted to the air in 1 h.

--i'm not sure how to go about this problem any help is appreciated


Thanks in Advance
 
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  • #2
mmg0789 said:
A 100-hp car engine operates at about 15 percent efficiency. assume that the engine's water temperature is 85deg C is its cold-temperature (exhaust) reservoir and 500deg C is its thermal "intake" temperature (the temperature of the exploding gas/air mixture)

a)calculate its efficiency relative to its maximum possible (Carnot) efficiency

b) estimate how much power (in watts) goes into moving the car, and how much heat, in joules and in kcal, is exhausted to the air in 1 h.

--i'm not sure how to go about this problem any help is appreciated


Thanks in Advance
The Carnot efficiency is easily calculated. What percent of the maximum possible efficiency (the Carnot efficiency) is the engine achieving?

The 15% efficiency tells you what fraction of the input energy is going into moving the car. The rest goes out in the exhaust.
 

FAQ: How Efficient is a 100-hp Car Engine Compared to Carnot Efficiency?

What is the purpose of calculating efficiency?

The purpose of calculating efficiency is to measure how well a process or system is performing in relation to its intended goals. It helps us understand how much of the input is being converted into useful output, and whether there are any areas for improvement.

How is efficiency calculated?

Efficiency is typically calculated by dividing the actual output by the expected output and multiplying by 100 to get a percentage. For example, if a machine produces 90 units per hour but is expected to produce 100 units per hour, the efficiency would be 90/100 x 100 = 90%.

What factors can affect efficiency?

There are many factors that can affect efficiency, including the design and condition of the equipment, the skill level of the operators, the quality of the materials being used, and external factors such as temperature and humidity. It is important to identify and address these factors in order to improve efficiency.

How can efficiency be improved?

Efficiency can be improved by identifying and addressing any factors that may be causing a decrease in efficiency. This could involve making changes to the equipment or processes, providing training for operators, or implementing quality control measures. Regular monitoring and analysis of efficiency can also help identify areas for improvement.

What are some common applications of efficiency calculations?

Efficiency calculations are commonly used in various industries such as manufacturing, energy production, transportation, and agriculture. They can be applied to measure the performance of machines, processes, and systems, as well as to evaluate the effectiveness of new technologies and methods. Efficiency calculations are also used in research and development to compare different designs or processes and determine the most efficient option.

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