Conceptual thermodynamics question

AI Thread Summary
The discussion revolves around understanding the differences between various types of heat engines, specifically in the context of a Carnot engine. The user is confused about questions 16, 17, and 18 from a practice set, particularly regarding the implications of different temperatures (Tc) and the classification of the engines as reversible or irreversible. They express uncertainty about the concept of Carnot engines, which ideally should avoid irreversible processes, and note that the answers to some questions indicate the engines are a "hoax." The user seeks clarification on how to interpret thermal efficiencies that are less than 1 in these scenarios. Understanding the principles of thermodynamics and the definitions of heat engine types is crucial for answering these questions accurately.
kuahji
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http://wps.prenhall.com/esm_giancoli_physicsppa_6/0,8713,1115091-,00.html (under practice questions)

On questions 16,17, & 18 I'm trying to figure what is the difference between them (Clearly Tc is different, but how does that change the problem?). The question asks
The heat engine shown above is

a) a reversible (Carnot) heat engine.
b) an irreversible (Carnot) heat engine.
c) a hoax.
d) none of the above.

I'm guessing I just don't understand the concepts, as I thought a Carnot engine was suppose to avoid irreversible processes, like an idealization. Anyway, the answer to 17 & 18 are "a hoax." They all seem to have thermal efficiencies of less than 1, so how should I look at these questions?
 
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Hi kuahji,

kuahji said:
http://wps.prenhall.com/esm_giancoli_physicsppa_6/0,8713,1115091-,00.html (under practice questions)

On questions 16,17, & 18 I'm trying to figure what is the difference between them (Clearly Tc is different, but how does that change the problem?). The question asks
The heat engine shown above is

a) a reversible (Carnot) heat engine.
b) an irreversible (Carnot) heat engine.
c) a hoax.
d) none of the above.

I'm guessing I just don't understand the concepts, as I thought a Carnot engine was suppose to avoid irreversible processes, like an idealization. Anyway, the answer to 17 & 18 are "a hoax." They all seem to have thermal efficiencies of less than 1, so how should I look at these questions?


For a heat engine operating between two heat reservoirs, what is the maximum efficiency possible?
 

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