How Do You Calculate Qh for a Non-Carnot Heat Engine?

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To calculate Qh for a non-Carnot heat engine with a hot reservoir at 600K and a cold reservoir at 300K, the efficiency is defined as W/Qh, where W is the work output. Given that the engine produces 0.5 J of work for every J of thermal energy extracted, the efficiency is 0.5. The relationship between Qh, W, and Qcold is established by the equation Qhot = W + Qcold. The discussion emphasizes that the Carnot efficiency is not necessary for this calculation, and combining the equations will yield the required value for Qh. Understanding the first and second laws of thermodynamics is crucial for these calculations.
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1. Thot reservoir= 600K, Tcold reservoir= 300K, Output= 0.5 J of work for every J of thermal energy extracted from the hot reservoir. What is Qh?



2. efficiency= W/Qh; Carnot efficiency= 1- (Tcold/Thot);



3. I have found the Carnot efficiency to be 0.50. I don't know where to go after this.
 
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physics.stu said:
1. Thot reservoir= 600K, Tcold reservoir= 300K, Output= 0.5 J of work for every J of thermal energy extracted from the hot reservoir. What is Qh?



2. efficiency= W/Qh; Carnot efficiency= 1- (Tcold/Thot);



3. I have found the Carnot efficiency to be 0.50. I don't know where to go after this.

1. what is the 1st law?
2. what is the 2nd law? (the assumption seems to be that you're running a Carnot engine.)
3. what is the definition of efficiency? oops, you have that equation already I see ...

3 equations, 3 unknowns.
 
First Law: dU = Q-W; dU=0.0J because it returns to initial state (cyclic engine)

I am NOT running a Carnot engine, it's the only thing that I could solve for.
Second Law: thermal energy will flow spontaneously from a hot object to cold object but cannot spontaneously flow from cold to hot object.

More on efficiency:
Qhot= W + Qcold
Efficiency= 1-(Qcold/Qhot)
 
physics.stu said:
Output= 0.5 J of work for every J of thermal energy extracted from the hot reservoir
So what is the efficiency?
 
physics.stu said:
First Law: dU = Q-W; dU=0.0J because it returns to initial state (cyclic engine)

I am NOT running a Carnot engine, it's the only thing that I could solve for.
Second Law: thermal energy will flow spontaneously from a hot object to cold object but cannot spontaneously flow from cold to hot object.

More on efficiency:
Qhot= W + Qcold
Efficiency= 1-(Qcold/Qhot)

You're right - you don't need to make the Carnot assumption. Answer Dr Claude's question!
Combine your two equations above and you have the answer!
 
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