Theory of capilary tube

[nike123]

http://download301.mediafire.com/txy...2520Ehrens.pdf

[Peter_1]

Nike, you need a password to enter this site

[nike123]

Nike, you need a password to enter this site

Cheking! .....

Sorted.
You could delete this now!
Thanks!

[Peter_1]

some extractions out of the article which I disagree

'Liquid refrigerant flows faster than vapor'

'The colder the liquid ,the faster the flow'

Page 4, second paragraph, the example he describes is in my opinion not right. He sees a blocking condenser as something that always escalates till the compressor shuts out on its HP.

[Chef]

This description by Henry Ehrens is an adjunct to his previous paper but its size is too large to attach to this reply. If you send a PM I will send you a copy.
Or I can send it to a Moderater who can then post it.
Peter - I can send it to you?

It describes nicely the whole process and includes pressures and temps at various points for all conditions and is very good indeed. It covers low charge and high charge plus general understanding of how to troubleshoot systems.

I also agree some of the statements he makes are a little confusing like the 'liquid flows faster than vapour' and can only assume he is refering to mass flow for any given pressure drop otherwise it does not make sense. What is actually happening inside the tube is a topic of intense study.



Chef

[Peter_1]

You may mail it to my private email address Chef

[icecube51]

can you put it on the forum to or to my private mail ??.always in for something nice to read & learn.

thnx peter & chef

Ice

[The Viking]

If someone email it to me I will post it on my site for public download

[Chef]

Having looked again at this 'Theory article' it seems to be misleading.

When a cap tube is sized for a specific duty the two phase flow region provides most of the pressure drop. Lets assume this length is calculated to be 1 metre.

If we then add 0.5 metres for a total length of 1.5 metres then this extra lenth is the stability part and means the liquid must be subcooled as it enters the tube. This subcooloing is then lost (as a pressure drop) as it passes down the first 0.5 metres of the tube.

Once you've decided on a certain subcooling and hence length in the design the actual amount the subcooling varies is very little over the load ranges of a typical system. Perhaps just 2 or 3 degrees C and certainly not the 10C that the article invokes.

Generally though it gets the point across about the subcooled pressure loss zone and is good for that.

Really the only way to figure it all out is to connect the cap tube calculations to the system and include changing pressures and tempertures at the evap and condenser and the compressor power to see how it all moves together as a system, how it balances. Now there is a challenge! Anyone up for it?

Chef

[icecube51]

sounds to me it is something for someone ho is most of the time at sea ;-)) .

Ice

[Peter_1]

I placed the article Chief send me on an external server.
You can download it on http://www.megaupload.com/nl/?d=IK0AP453
Fill in 3 letter Antispamcode -> Download - > NEw Screen -> Free column, -> Countdown timer at the bottom of +/- 45 seconds -> Then button Free Download Appears instead of the countdown timer.

[nike123]

Or, you could download it here immediately!

Peter, try to use this server:
http://www.mediafire.com/