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dallan
28-09-2005, 10:24 PM
Found one of these plants on a site I was doing some other stuff on, can anyone explain the theory behind it.

frank
28-09-2005, 11:01 PM
have a look here or e-mail them direct http://www.star-ref.co.uk/news_and_info/news_casestudies.html

rbartlett
29-09-2005, 07:39 PM
I think Andy is by far the best here to answer this question..

cheers

richard

US Iceman
05-10-2005, 05:29 PM
I would like to find out more information on this system.

Can anyone provide a flow diagram of how this system is put together?


It's just a pumpless overefeed system. The huge levels of subcool don't increase energy efficiency on their own but they facilitate the overfeed.

It sounds like what we in the US call a controlled pressure system.

Thanks in advance for any information.

ecclesk
10-10-2005, 06:47 PM
If my memory serves me correctly they are something like the attached drawing

We have 12+ of these on one site running coldstores, chill stores & blast freezers and I think most of them are most of them are over 20 years old, a lot of them were R502 which are now running on R22 and a couple use R411B.

I have not worked on these systems a great deal but from what I have seen they are very reliable and efficient, obviously for the systems which have been retrofitted to R22 this has caused a reduction in capacity/efficiency but they still perform well and deliver the required temps with ease, the reverse cycle defrosting seemed to work very well.

The design of the vessel has changed over the years, on the old systems we have, the oil return/rectification was taken care of inside the vessel, I think the newer installs have a separate system.

One thing I do remember is that all valves & controls are within the plant room which makes things a bit easier when working on the system

Years ago one of our LPR vessels was replaced, I think it was to do with a problem with oil return, our engineer on site cut the old vessel open as he had always been intrigued by the internal arrangements of the LPR, see the attached drawing he made.

They are a minimal charge system and require significantly less refrigerant than many other systems, also I think head pressures float with ambient temps.

Star did run an LPR training course for us on the site mentioned above , I think I still have the notes if they would be of interest to you let me know and Iíll dig them out.