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bintoito
08-03-2013, 05:57 PM
I know that these guys are some 30 to 40 years old, but I really needed to get a grasp of what their COP would be at about Tevap of -30 and Tcond of some >30șC, so...anyone out there that still has the necessary info?!

This was about all the info I could gather (from this forum)
GRASSO RC411 - NH3, 23 bar, 1000 rpm, 75 kW;
swept volume of approx 530 m3/h, 4 piston

Alternatively, from your experience for recips that old and to this temperature lift what would a reasonable figure be in terms of cop? 1,2 - 1,5 (basing this on a mycom screw that's only 4 or 5 years old that has a cop of about 2,2 in the same operating conditions.....)?!

Please help ;)

engrp
11-03-2013, 12:41 PM
sir, are you asking of grasso rc411 specs? you may want to visit grasso website. they are one of the compressor manufacturers(maybe the only one), where you can download all the information you need . but maybe, the information available is only for rc 412. rc411 is a very dated compressor. but we are still using this unit(under overhaul, at the moment). hope you can find what you are looking from the grasso website.

bintoito
11-03-2013, 01:06 PM
Hello dear engrp. Thank you for your reply. Grasso is now gea and i can't find it anywhere on their website.. Is 412 similar (I'm supposing it only varies in capacity). If so, could you be so kind as to send me whatever documents you may have regarding technical features? Best wishes,

Jeroen_NL
21-03-2013, 09:35 AM
Hello dear engrp. Thank you for your reply. Grasso is now gea and i can't find it anywhere on their website.. Is 412 similar (I'm supposing it only varies in capacity). If so, could you be so kind as to send me whatever documents you may have regarding technical features? Best wishes,

Please give me the conditions where it's running at and what kind of system setup so I can give you the data.

bintoito
21-03-2013, 10:00 AM
Hi Jeroen_NL,

I was told that they (one full load the other when the first can’t keep up to the demands) are running at an evaporating temperature of -30șC; condensing temperature unknown but they are linked to a new evaporative cooling tower in a place where the average annual temperature is 15,5șC and about 71% RH (+- 9,8șC dewpoint).
They’re some 20 or 30 years old so, not sure on their real operating conditions…
Thanks for any and all help you could give me,
cheers

engrp
21-03-2013, 12:47 PM
sir bintoito, pm me your email. i was able to find an old rc11 service manual, if you still need it

Jeroen_NL
21-03-2013, 05:21 PM
Hi Jeroen_NL,

I was told that they (one full load the other when the first can’t keep up to the demands) are running at an evaporating temperature of -30șC; condensing temperature unknown but they are linked to a new evaporative cooling tower in a place where the average annual temperature is 15,5șC and about 71% RH (+- 9,8șC dewpoint).
They’re some 20 or 30 years old so, not sure on their real operating conditions…
Thanks for any and all help you could give me,
cheers

Hi Bintoito,

I've atached a printscreen from our old internal selection program (I work at GEA).
But are you sure the compressor isn't connected to a intermediate pressure separator, beacause these conditions would result in a dischare temperature of 175 celcius degrees with is out of limmits for this compressor.

Please give me some more information about the suction-/intermediate pressure wich the compressor is running at.

And is the compressor direct driven or belt driven, do you know on how many RPM its running at your location.

Greets,

Jeroen

bintoito
21-03-2013, 09:57 PM
Hi Jeroen_NL

Many thanks for helping me.
Unfortunately at this moment I don't have much more data to give you with full certainty as these compressors are located in a secondary plant which I only visited briefly. The guy I'm dealing with (from the primary plant), doesn't seem to get along all that well from the guy from the 2nd plant lol, so info is scarce...

But assuming a similar functioning as in the primary plant, let's assume an economizer running at -10șC which helps keeping temperatures down (did they have economizers 20 or 30 years back?!)
As for the RPM's I don't know, but if it helps, in Portugal stuff runs at 50 Hz...(I'm hoping this is useful to you as I quite regularly see for internal combustion engines x RPM for 50 Hz and Y RPM for 60 Hz)
As for the transmission, if I'm not mistaken, they're direct driven...

As for your printscreen how confident are you in the COP result? I was quite surprised with the value and was expecting something more in the range on 1,5 to 2 (in comparison with a Mycom screw running at -33șC with thermosyphon oil cooling and economizer that has a stated COP, given by their software of 2,2 - This chiller's only 6 or 7 years old, max.)