Thermosyphon piping

[JIM ROBERTS]

Hi All,
I've seen return lines from oil cooler thermosyphons go either to the condenser inlet or into the receiver, what is the preffered way?

[Segei]

Receiver.Return line has mixture of liquid and vapour. Liquid is not good for condenser performance.

[Mark Selby]

Segei in correct unless there is a large enough thermosyphon vessel.

[Magoo]

Hi Jim Roberts.
generally liquid feed to cooler off the bottom and vapour return back at the top of receiver, remember with ammonia you need at least 2 metre vertical head separation between thermo/cooler and liquid receiver, liquid into bottom of thermo and leaving at the top.

[Lodiev]

I am busy designing a NH3 plant for one of our fishing vessels. Normally the gas return would go back to the top of the receivers if u pump the liquid into the thermosyphon coolers. but if u use gravity to feed the liquid it is best to bring the return back to the top of the receiver.
Think of it this way: What is the pressure drop over the condenser to the receiver ?
U do not want the return to have a higher pressure than the feed on the thermosyphon coolers becourse then u will have insufficient cooling of your oil.

[JIM ROBERTS]

Thanks for your comments Lodiev, it makes sense to me, I just can't work out why some contractors pipe it to the condenser inlet, most of the installations I've seen do it this way.

[Magoo]

Hi Jim Roberts.
generally the compressor discharge has branch tee'd off to the top of liquid receiver, therefore the whole high side is at the same effective pressure, the vent line from thermo/ oil cooler will go back to the closest peice of plant, either the receiver top entry, or the condenser. Six of one or half dozen of the other. Gravity does the rest.

[Josip]

Hi, JIM ROBERTS

Hi All,
I've seen return lines from oil cooler thermosyphons go either to the condenser inlet or into the receiver, what is the preffered way?

My preferred way is to connect return lines from thermosyphon coolers as possible close to condenser's inlet pipe.

You can search RE forums for "thermosyphon" and you will find a lot of info...

Best regards, Josip