multistaging??? cascading????

[ank_gl]

why cant i make a post.
it always says
"You are only allowed to post URLs to other sites after you have made 15 posts or more."

[nike123]

why cant i make a post.
it always says
"You are only allowed to post URLs to other sites after you have made 15 posts or more."
You just made post!;)
Read forum rules!

[Brian_UK]

why cant i make a post.
it always says
"You are only allowed to post URLs to other sites after you have made 15 posts or more."
Why do you need to post a URL, try using a question first.:(

Don't complain, work around it like everyone else has done.

[ank_gl]

Why do you need to post a URL, try using a question first.:(

Don't complain, work around it like everyone else has done.

i didnt use a URL, i only typed my question, still it didnt get uploaded, anyways i ll try again. i typed everything, right from my problem to the answer, i think, but it didnt get posted. now i have to run to my college, ie, i have precisely 2 minutes. here goes
what is the difference between multistage and a cascaded refrigeration system? and when to go for multistaging and when for cascading?


And sir, not trying to be offensive, but i DID not use any URL, and it still showed that msg

[Gary]

what is the difference between multistage and a cascaded refrigeration system? and when to go for multistaging and when for cascading?


In a multi-stage system, the compressor cylinders are in series. The vapor is pumped by half of the cylinders, the discharge of which is then pumped by the other half of the cylinders. It is far more complex than this, but essentially that's how it works.

In a cascade system, there are two (or more) complete systems connected by an interstage heat exchanger. The interstage acts as a condenser for the low stage system and an evaporator for the high stage system. In other words, one system cools the other system which cools the product.

A multi-stage system can achieve lower temperatures than a conventional system, and a cascade system can achieve lower temperatures than a multi-stage.

[hendry]

i have attached something for you ...

to me, multistage has some drawback.
1] relatively high discharge pressure
2] relatively low suction pressure
3] uneven oil distribution

cascade overcomes the above. ...
the beauty is u came have different refrigerant for cascade.

but, you need to be careful on condenser/evaporator due to its temperature differences in between ...

hope that helps.

[Brian_UK]

Do you have a signature containing a URL ?

[ank_gl]

Thanks a lot Mr Gary and Mr Henry.
I actually first posted this question on physicsforums. there i didnt get any reply. i described it completely there. actually i was confused between three situation.
1-Multistaging = 2 cycles with same refrigerant coupled via a heat exchanger.
2-Multistaging = Single cycle with a multistage compressor(to increase the volumetric efficiency at higher pressure ratio)
3-Cascading = 2 Cycles with different refrigerant

And Mr Brian, i don't have any signature, all i did was type a long question, but it didn't get posted. Anyways thats not any issue.

I recently started working in refrigeration topic under my professor, so i hope this forum ll be more than helpful for me

[Peter_1]

In a multi-stage system, the compressor cylinders are in series. The vapor is pumped by half of the cylinders, the discharge of which is then pumped by the other half of the cylinders. It is far more complex than this, but essentially that's how it works.


It's mostly in an uneven proportion: 4 cilinders HS and 1 LS or 6/2. Mostly an interstage cooler between LP and HP to avoid high discharge temperatures.
Ank_Gl, regrading your last post, 1 is wrong only one cycle, 2 is correct and 3 is also correct