Water-cooled condenser & receiver relative heights

[desA]

I have a few questions regarding a water-cooled condenser, with liquid outlet to a receiver.

What height should the receiver be relative to the condenser?

Should it be lower than the condenser, or does this not matter?

Would liquid logging in the condenser affect system performance?

[nike123]

DesA, check Alfa laval book!
http://rapidshare.com/files/12059657...nual_4thEd.pdf

[desA]

Thanks so much, nike. That is an excellent resource.

I see in that book, that the receiver is positioned such that the outlet from the condenser free flows into the receiver, which positioned below this condenser outlet. This is shown in many diagrams. This would make sense, in my view.

Has anyone seen examples where the receiver is positioned higher than the condenser outlet? If so, what effect does this have on the condenser fluid backup?

[nike123]

Check picture at page 105. Right lower corner of picture!

[desA]

Check picture at page 105. Right lower corner of picture!

Excellent eye you have. Perfect.

Question answered.

[Gary]

Check picture at page 105. Right lower corner of picture!

That shows an equalized condenser, which is a different animal. When the condenser and receiver pressures are equalized, liquid feeds down to the receiver by gravity. This is commonly used where the condenser is outdoors in cold ambients and the receiver indoors in warm ambients. The pressure in the condenser can drop below the pressure in the receiver, holding the liquid in the condenser.

If an equalizer line is installed from the top of the receiver to the top of the condenser, then the pressures are equal and the liquid can flow by gravity from the condenser to the receiver. In order to move the liquid by gravity the receiver must be below the condenser.

In a non-equalized system there is a pressure difference to move the liquid and the relative height makes very little difference aside from the added dP needed to lift liquid (roughly ~ 1psi for 2ft of lift).

[desA]

Thanks, Gary.

In a non-equalized system there is a pressure difference to move the liquid and the relative height makes very little difference aside from the added dP needed to lift liquid (roughly ~ 1psi for 2ft of lift).

How will this affect the condensing process itself?

In my view, excessive back-pressure will cause the condensed liquid to back up inside the condenser, reducing condensing surface & raising condensing pressure (Tc,sat). I would think that the exit of the condenser wants to be as free as possible.

Page 103 discusses an upward liquid loop to set the condensate level in the condenser. There would, however, have to be a practical limit to this.

[Gary]

Sorry, Des... I was editing my post while you were writing yours. Perhaps the edited version will be clearer.

[nike123]

In arrangement on right side of that picture I don't see equalization line.
Also paragraf 3 said that is not recomended but it may be mounted above.

[Gary]

In arrangement on right side of that picture I don't see equalization line.
Also paragraf 3 said that is not recomended but it may be mounted above.

I'll let the ammonia folks explain vented receivers. Again... a different animal.

[Aik]

Thanks, Gary.



How will this affect the condensing process itself?

In my view, excessive back-pressure will cause the condensed liquid to back up inside the condenser, reducing condensing surface & raising condensing pressure (Tc,sat). I would think that the exit of the condenser wants to be as free as possible.

I agree with your point of view. Generally receiver is below or on same level. If receiver higher then preasure in receiver will be less at dp=density of liquid * g (acceleration free fall =9.8 m/s^2) * relative height.

[desA]

Thanks, Aik.