# Regarding efficiency of heat engines

• Nitin Gupta
In summary, the conversation is discussing the calculation of efficiency for an engine using two different methods: 1) Efficiency = (Net Work Done) / (Heat absorbed) and 2) Efficiency = 1 - (Temperature Lowest / Temperature Highest). The person is getting different results from the two methods and is unsure how this is possible. They are then asked to provide the complete problem statement and their work for further assistance.
Nitin Gupta
I tried to calculate the efficiency of a engine using the formula :
Efficiency = (Net Work Done) / (Heat absorbed)

And then I tried to calculate the efficiency of respective Carnot engine by two ways :
1) Efficiency = (Net Work Done) / (Heat absorbed)
2) Efficiency = 1 - (Temperature Lowest / Temperature Highest)

But the efficiency I am getting by the two methods different.How is this possible?

Nitin Gupta said:
I tried to calculate the efficiency of a engine using the formula :
Efficiency = (Net Work Done) / (Heat absorbed)

And then I tried to calculate the efficiency of respective Carnot engine by two ways :
1) Efficiency = (Net Work Done) / (Heat absorbed)
2) Efficiency = 1 - (Temperature Lowest / Temperature Highest)

But the efficiency I am getting by the two methods different.How is this possible?

Beats me.

This is exactly why the PF Rules state that the Homework Template should be filled out completely, so that HW helpers don't have to extract information piece by piece from users.

Please use the HW template and post the complete problem statement you are working on along with your work which has led to an irreconcilable result.

Nitin Gupta
SteamKing said:
Beats me.

This is exactly why the PF Rules state that the Homework Template should be filled out completely, so that HW helpers don't have to extract information piece by piece from users.

Please use the HW template and post the complete problem statement you are working on along with your work which has led to an irreconcilable result.

Sorry for the extremely late reply...check this out...here is what I attempted...

Sorry, it looks like your work didn't make it into your post.

## 1. What is the definition of efficiency in heat engines?

The efficiency of a heat engine is a measure of how well it converts thermal energy into mechanical work. It is calculated by dividing the work output of the engine by the heat input.

## 2. What factors affect the efficiency of a heat engine?

The efficiency of a heat engine is affected by several factors, including the temperature difference between the hot and cold reservoirs, the type of working fluid used, and the design and materials of the engine.

## 3. How does the Carnot cycle relate to the efficiency of heat engines?

The Carnot cycle is a theoretical cycle that represents the maximum possible efficiency for a heat engine operating between two temperatures. It serves as a benchmark for comparing the efficiencies of real heat engines.

## 4. Can the efficiency of a heat engine be greater than 100%?

No, the efficiency of a heat engine cannot exceed 100%. This would violate the laws of thermodynamics, which state that energy cannot be created or destroyed, only transferred or converted.

## 5. How can the efficiency of a heat engine be improved?

The efficiency of a heat engine can be improved by increasing the temperature difference between the hot and cold reservoirs, using more efficient working fluids, and optimizing the design and materials of the engine. Regular maintenance and proper operation can also help improve efficiency.

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