# Difference between carnot and rankine cycle (1 Viewer)

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#### abhishek_sai81

difference between carnot and rankine cycle.
pls give replys

#### Mech_Engineer

Science Advisor
Gold Member
abhishek_sai81 said:
difference between carnot and rankine cycle.
pls give replys
This question is easily answered in any Intro to Thermodynamics book. I suggest you start there.

#### abhishek_sai81

in carnot cycle condensation process is not complete but in rankine cycle condensation process is complete

#### Mech_Engineer

Science Advisor
Gold Member
It's more important to note the way that the heating of the working fluid is modeled.

#### Prometteus

The most important to say is: Carnot cycling is to simply to be used in the reality. I mean, is good to physics, to learn thermodynamics, but in real world you don´t just have a cold and a hot spot. (i don´t know the name in english..sorry..). So, the rankyne cicle is very used in vapor power system. In fact to know how good the process is you use the perfomance of carnot cycle and compare with the rankine cycle(off course , the rankine cycle is always smaller).

#### saad ahmed khan

i suggest you read up on cengel boles thermodynamics. theres plenty about the carnot and rankine cycle in it, advantages differences etc.

ebook is available

#### electrochemst

This question is easily answered in any Intro to Thermodynamics book. I suggest you start there.
C'mon Mech_Engineer, if its so easy to answer then just give him the answer. He posted the question to get a quick answer from someone who knows without having to look it up.

Here's the answer: The main difference between that Rankine Cycle and the Carnot Cycle is that heat transfer across the system boundary of Carnot Cycle is isothermal (constant temperature), and heat transfer across the system boundary in a Rankine cycle is isobaric (constant pressure). The Rankine cycle is a better model for most real systems because a constant pressure heat exchanger is a better approximation for how heat transfer is accomplished in most real systems than than heat transfer to/from constant temperature "heat reservoirs."

#### Midas1

The Carnot cycle is not practicable, but it is optimal and ideal.

Rankine cycle is practicable.

#### xxChrisxx

C'mon Mech_Engineer, if its so easy to answer then just give him the answer. He posted the question to get a quick answer from someone who knows without having to look it up.
This is immensly bold for somone to turn up with for their first post.

We're here to help people learn and undertand, people learn by working and thinking themselves, not by just having us spoonfeed them answers.

There is a huge difference between asking:
"what is the answer" and
"I don't understand why this is the answer"

One indicates they've put in effort the other doesn't.

#### Mech_Engineer

Science Advisor
Gold Member
C'mon Mech_Engineer, if its so easy to answer then just give him the answer. He posted the question to get a quick answer from someone who knows without having to look it up.
You misunderstand the purpose of this answer, its to get him actually find the answer himself...

Nice job waking up such an old thread btw.

#### xxChrisxx

Nice job waking up such an old thread btw.
****. We've been necrotrolled.

#### electrochemst

This is immensly bold for somone to turn up with for their first post.

We're here to help people learn and undertand, people learn by working and thinking themselves, not by just having us spoonfeed them answers.
I didn't mean any disrespect. I was under the impression that this site was a place where people could ask tough questions to get good answers from experts.

I am teaching thermo right now which is the only reason why I felt compelled to answer that question. When a student asks me a question my philosophy is to answer it as completely as possible. I feel like telling them to look it up right off the bat is somewhat of a cop out, but that is a matter of opinion. I think part of the art of teaching is being able to condense information from texts and concisely communicate it to people who want to learn but don't have time (or motivation) to read a chapter or two in text book. Suggesting further reading, especially with a direct citation, is always a good thing if someone is genuinely curious, but getting the ball rolling with a solid answer doesn't impede anyone's learning experience.

Again, just my opinion here, and sorry if the original post came off a little coarse.

#### matt222

with respect to the amount of heat added which one is the highest?
carnot
simple ranking
regenerative ranking

#### Vespa71

with respect to the amount of heat added which one is the highest?
carnot
simple ranking
regenerative ranking
I interprete the question to be which cycle require the most heat-in pr. work output, ergo is the least effective.
Carnot is the ideal, reversible heat-machine-cycle. The cycle requiring the least heat for a certain work would thus be accomplised by the carnot-cycle, or rather not since it is an impossible one. Any possible one would use more heat.
Regenerative rankine, or reheating, is a way for rankine to poorly impersonate carnot-cycle (performs a pseudo isothermal expantion, staged). Since it is done, I presume it is less ineffective, and therefore uses less pr.work-out heat than the simpler cycle. Answer available in un-necessarily difficult language.

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