Re: Mass Flow Rate with Big Condenser
OK, let me try this a different way...
If the intention is TO flood the condenser for winter pressure control, this is something different.
If you have multiple condensers in parallel then the only way you can GRAVITY DRAIN them is to ensure the outlet pressures of EACH outlet branch connection exist at the same pressure. However you have to do this to make the condensers attain their rated heat rejection capacity is what is required.
And...more often than not, incorrect piping practices cause this.
Re: Mass Flow Rate with Big Condenser
Quote:
Originally Posted by
US Iceman
OK, let me try this a different way...
I was thinking of flooding as a problem not as a solution too.
In order to gravity drain in all condensers with different pressure drops across would need inverted siphons on the ones with less pressure drop.
Maybe you design your systems too good and never had these problems us mere mortals with smaller systems do.
Re: Mass Flow Rate with Big Condenser
Quote:
Originally Posted by GXMPLX
In order to gravity drain in all condensers with different pressure drops across would need inverted siphons on the ones with less pressure drop.
How do you know which one will have the lowest pressure drop? This can change during operation if one condenser receivers colder air, or any other number of factors. Therefore to be safe you would have to determine what a maximum allowable pressure loss would be and design the liquid seal trap accordingly.
Re: Mass Flow Rate with Big Condenser
Quote:
Originally Posted by
US Iceman
How do you know which one will have the lowest pressure drop?
I like simple questions they lead to simpler answers: Not using the sense of smell, of course!.
If you want place a sight glass on each output.
I see you optimize too much, try a hypothetical problem: Installing an air cooled with one circuit in parallel to a cooling tower (refrigeration side of course), both with the same capacity, different pressure drop.
Re: Mass Flow Rate with Big Condenser
Quote:
Originally Posted by GXMPLX
I see you optimize too much,...
No, I would rather have the system work properly the first time. That's why I look at all of the potential issues I know about.
I agree with what you're saying about the two different types of condenser. There the pressure drop could be considerably different between the two.
But... it's the same problem on evaporative condenser coils also. And there the low pressure drops found can cause excessive liquid back-up in the condensers and cause you to loos heat rejection capacity.
Same problem, just different devices...
Re: Mass Flow Rate with Big Condenser
OK, fine for me. Check CP though.
Re: Mass Flow Rate with Big Condenser
Quote:
Originally Posted by
US Iceman
How do you know which one will have the lowest pressure drop? This can change during operation if one condenser receivers colder air, or any other number of factors.
Or fans switching on and off. Installing them high enough and installing siphons is how we do t.
What do you mean with an inverted siphon?
2 Attachment(s)
Re: Mass Flow Rate with Big Condenser
Like this one with 1 condenser double the size as the other one.
Re: Mass Flow Rate with Big Condenser
Quote:
Originally Posted by
Peter_1
... no oil floats, no oil separators, no oil tanks, no interconnection between the compressors.
As long you respect the proper guidelines, you don't need all these fancy tricks.
Great congratulations! But I think you must count luck in your side too, I wouldn’t recommend this though obviously can be done!
Quote:
Originally Posted by
Peter_1
…
So no VFD needed and still able to regulate a preset LP very precise.
Of this you don’t have to convince me!
DISCLAIMER: I am not talking against VSD/VFD in the following (they do have several advantages):
VFD/VSD vendors always compare their system application in a refrigeration system that is grossly oversized and it is obvious ANY form of capacity control would improve efficiency too!
Never seen a study of one compressor with VSD against a rack, or compressor with VSD against a compressor with capacity control. I don’t think these studies haven’t been done.
Not letting head pressure float or suction pressure float may be energetically inefficient. It does have other important advantages like simplifying control, correcting power factor, and in some situations save energy too, etc.
Re: Mass Flow Rate with Big Condenser
Quote:
Originally Posted by
GXMPLX
Great congratulations! But I think you must count luck in your side too, I wouldn’t recommend this though obviously can be done!
Luck?? At least 6 to 8 packs made this way, all before 1995 and all are still running, most even with the original compressors.
Does so much luck excist?
Re: Mass Flow Rate with Big Condenser
Quote:
Originally Posted by
Peter_1
Does so much luck excist?
Ask the lady who won 50 millon in the lottery!
I see many system with small hermetic compressors in parallel, and no equalization ... still wouldn't recommend to do this.
If you have the right maintenance guy anything can be done!