# Questions tagged [heat-engine]

The tag has no usage guidance.

356 questions
Filter by
Sorted by
Tagged with
44 views

### Will a Modified Maxwellian Demon Experiment Using Charged Particles Be Able to Recycle Heat?

(If necessary this experiment can be conducted in an environment where gravity is negligible to avoid gravitational effects.) Two adjacent containers are filled with a homogenous gas composed of ...
3k views

### Do thermodynamic cycles occur only in human-made machines?

Intuitively, it seems like heat engines and refrigerators require a good bit of technology to make a working substance pass through different thermodynamic states and then finally return to the ...
• 325
797 views

• 128
236 views

### Why is the number of thermodynamic systems (that do not do work) in this scenario two?

The hardest thing for me about studying thermodynamics, is connecting the formal theory with actual problem instances. Here is an example: In Callen’s Thermodynamics and an Introduction to ...
• 3,369
1 vote
277 views

### Why does heat engine efficiency use absolute zero rather than thermal differential?

Carnot's theorem calculates efficiency of a heat engine versus absolute zero. I read the question Why can Carnot efficiency only be 100% at absolute zero? But I don't feel it addresses it precisely. ...
1 vote
1k views

### Why can't a heat engine have 100% efficiency?

Using the idea of isotherms and adiabats, I came up with the following argument to convince myself. First imagine the working gas within the system being heated along an isochore (hence all heat ...
• 57
1 vote
116 views

### Distinction between "types of heat" in thermal efficiency

The definition of thermal efficiency I see in several sources is "total work" divided by "heat input". Wikipedia, for example, says: "For a heat engine, thermal efficiency is ...
• 628
138 views

### Should I put my freezer in the middle of the living room? [duplicate]

There is a freezer in my kitchen. It has frozen fish fingers and spinach and potato waffles and leftovers. The food stays below freezing temperature using the principle of latent heat. The freezer ...
• 309
602 views

### How can we say that work done by carnot engine in a cycle equals net heat released into it even when it is operated b/w 2 bodies and not 2 reservoir?

When a carnot engine is operated between 2 reservoir then after each cycle it return to its initial state so change in internal energy is zero and so work done by it equals net heat released into it. ...
• 353
62 views

### Thermoacoustic mechanism for a thermoacoustic engine

How exactly does a thermoacoustic engine work? (I don't mean the engineering part) I understand the part on the Brayton cycle occurring and all, but how might we measure the numerical efficiency for ...
148 views

### How does an internal combustion engine reduce the heat produced by burning fuel?

If I understand correctly, any heat produced by an internal combustion engine can be considered "waste heat"; energy from the fuel that did not get converted to mechanical energy. But if you ...
77 views

### The suction and thrust of an aircraft engine

Does only the air sucked in (not the air that is ejected at the back of the engine) by an airliner engine (turbofan engine) causes a thrust forward or in other words pull the engine forward? and why ? ...
1k views

### Does isothermal expansion not beat the efficiency of Carnot Heat Engine?

Ques: If I just take the 1st step of a Carnot Heat Engine (CHE) than it turns out to be more efficient than the CHE itself. Explanation: The 1st step of a CHE is the pure isothermal expansion of (...
1 vote
157 views

### Vapor Compression Refrigeration Cycle

My question here is, why do we need point 2 to be on the saturated liquid line, i.e. why do we need a saturated liquid for the throttling process? Why can we not use it in the liquid region or ...