which compressor should I use?

[chemi-cool]

Hi all.

I wanted to start this new thread about compressors.

The international market is offering many types of compressors, hermetics, scrolls, semi hermatics, open, screw and centrifugal.

Give us your opinion: which?, what kind?, what make? What would you use for each application? And why?

Chemi

[Andy]

Hi chemi-cool
I would say compressor selection is down to application, and to some extent what is hot at the moment. Take scrolls, two stage semi's are much more effecient that liquid injected scrolls, but the scrolls are what is being fitted. Anyway I would rather change out a 10hp scroll any day than a 10 hp two stage semi.
Industrial refrigeration again goes with fashions. Recips are the most effecient for many applications, especially where part load use is envisaged, but we use screws, mainly as they are relatively maintainess free and offer good efficiencies at full load.
Even screws suffer from fasion, with twin screws being widely used at present, not the mono screw which was seen to be better at one time. Me I can see the mono screw having a come back, mainly due to the good work of Vilter, and to a lesser extent JE Hall.
Centifugal compressor were once used for a/c, not so much now, but they have still maintained their market on large petro chem jobs, the tide will again turn and we will see them used again as preferance on a/c chillers.
Kind Regards. Andy

[Peter_1]

Hi Chemi-cool, Andy

Just my toughts:
We prefer Bitzer instead of Copeland: less noise and less vibrations. Bitzre is even a little cheaper.

never use the Maneurop machines anymore since Danfoss took over the company. They removed the inner deflector plate (Alu or steel plate) wich acted as sort of a liquid reciever. We encountered on several machines a lot of vibrations, even with braking off the spot welded fixtures.

I don't like the big Carrier( Carlysle?) machines because you have to remove the whole compressor, remowe the lower sump plate before you can clean a simple oil filter.

In the market cars we often do, we always recommend semi-hermetic machines but have to install mostly hermetic Unithé Hermétique machines due to the lower price. Semi-hermetic machines are more rigid and can withstand more severe vibrations.

Same for the gasses; we follow the recommendations of the manufacturer or what is prescribed by the client. We more and more change from R404a to R507.

Evaporator and condensor story - perhaps not your question - we always use Eurovent certified coolers.

BTW, did you know that Goedhart can deliver stainless steel evaporators at in my opninion very low prices?

Profroid has in his delivery program a very quit condensing unit with hermetic compressors, everything prewired, pressure modulated fan, a very good product.

[angryk]

How come R507A over R404A Peter?

[Peter_1]

Originally posted by angryk
How come R507A over R404A Peter?

For the same compressor, you have more cooling capacity and the COP is also better.

Bitzer 4V-6.2Y, -10°C/45°C, 5K Subcooling, ,10°C suction
R404a:
17,05 kW cooling capacity,
7,46 Power input
COP/EER : 2,28

R507a:
17,5 kW cooling capacity,
7,46 Power input
COP/EER : 2,34

[angryk]

Good to know, thanks peter.

[chemi-cool]

well peter,

please go back to bitzer software and check it one more time.

R-404A is a little bit better (acording to bitzer software) but both of these refrigerants are s....t.

no refrigerant gets close to R-12, R22 and R-502!!

maybe one day we will have here an overall debate about " LOOK WHAT THEY HAVE DONE TO MY REFRIGERANT!!!"

CHEMI

[Latte]

R12 what a fantastic gas.
High temp, medium temp & low temp works on all of them.

I don't know how the power consumption figures worked out for each temp but at least it was easy.

Why do we have all these new gases available especially when you consider a lot of them contain much the same (R134 in R404)
Could it not be possible to the manufactures to standardise gases or is it just a ploy to have lots of them & keep the price up


Regards

Raymond

[Andy]

Hi
R12 was a easy gas to work with, but it was never efficient
I remember working with R12 deep freeze cabinets, and all I remember was melting ice cream and negative evaporator pressures.
Pipe sizes was another issue, when used in industrial systems the pipes were huge and the leaks common, oil return was good, but that's about all I can think off.
Some of the low temperture intrim gases are quite good, even more effecient than R502, especially those with hydro carbons in them.
Low medium and high temp gases are to increase efficiency at the required range, there would be little point using a HFC that didn't harm the ozone layer if it was in-effecient and adding to gobal warming
Industrial users have the answer NH3, good or better than commonally available refrigerants at nearly all ranges, life is simple for an industrial tech, mainly only one gas to worry about, one which everyone tells you where the leak is

Regards. Andy.

[Peter_1]

Originally posted by chemi-cool
well peter,

please go back to bitzer software and check it one more time.

R-404A is a little bit better (acording to bitzer software) but both of these refrigerants are s....t.
CHEMI

Strange, I got another answer Chemi from the software.
I will recalculate it tomorrow and will take then contact again.

I'm having real troubles now with my HD. For the moment, I need to read all this on the computer of my son.

I installed already yesterday evening a complete new Windows XP Home Edition on a new HD via the computer of my son with my original XP Home Edition OEM version. (mY new HD was Master HD)

I'm putting this new HD - correct functioning in the computer of my son as a master HD - in my computer and it don't work anymore.
Is there somewhere a connection between hardware and software hat I need to change.
Installed via my computer a new windows in a different folder and I can't connect via/through the router for the internet.

Ohhh, computers can be a real nightmare. Try tomorrow further.

[herefishy]

Hi Peter_1,

I performed a HD c/o for my dad last weekend. What size is the new drive? if you are going from a 6-10GB drive to a 40GB say, and you have an older bios (machine), you may have to change settings in the bios to make it work (some of the older bios - 4/5 years ago - don't automatically support drives which may be over say 30GB). If this is the case, you will manually set the HD settings in the bios. You would probably need to get the installation instructions to properly configure.

Also, sometimes the HD jumper settings for the master device on the HD aren't compatable either. Usually the HD mfgr will offer alternate jumper settings for the situations in which the standard jumper setting don't work.

Of course this might only apply if you have a machine (motherboard) that may be four years old (or more).

Cheers

[chemi-cool]

hi peter,

Agree with herefishy and more. I do my computer myself exept for installing windows. I always change all the parts so they fit with each other the best.
when I buy mother board, hard drive, memory, monitor card and sound card, I get the latest version so it makes once every two years. never have any problems. kids not allowed to download!!

windows XP proffesional is a lot better then home, recommend

try to find computer man and do his cooling needs and in return, he will do your computer needs.

best of luck with your machine.

chemi

[chemi-cool]

peter,
another thought, why not consult WEBRAM?

wait till he returns from his trip to the USA . the worst . he will say no, but I have a feeling he will be helpful.

the scots are wanderfull people. I have a family there. I know them.

chemi

[rbartlett]

i think i've found the problem ....

http://www.reuters.com/newsArticle.j...toryID=4111495

cheers

richard

[Peter_1]

Richard,

INdeed Richard, that was the problem,...potatoes.

Typing now from my office, 30 miles from my home.

Computer is 2 years old and the old HD has 40GB, Seagate.

Serious now, ....thanks I have my son and and he has a lot more patient then I have with these stupid things. (If I can't connect a manifold or a Voltage meter, it's not OK for me ) It is a new HD of 120 GB (very cheap +/- 160 €, Seagate) and he knows how to format it in FAT or NFTS( for me it's Chinese)

We restarted with a complete new format of the HD in 3 partitions and re-installed XP and now it is working. There is indeed somewhere a link between the hardware and the XP software. I found this via searches on the net.

As soon all my programs are installed I will reformat my old disk and make an image on it (new word/technique I learned from my son) so that I can save all these troubles in the future.
And also, new 40 GB cost +/- 100 €, for me cheap enough to avoid future problems.

Thanks for the responses my friends.

Till the next problems/chat.

Peter

[Peter_1]

Link to that new Copeland compressor. IN fact, it was new for me.

http://www.copeland-corp.com/cp_rf/p...scroll_dig.htm

[Peter_1]

Chemi,

Here I inserted the data from Bitzer

Data R404a

************************************************************
BITZER-Software Version 3.3
(c) 2002, BITZER, Germany. All data subject to change.
************************************************************

13/01/2004
------------------------------------------------------------
Compressor Selection: Semi-hermetic Reciprocating Compressors
Input Values:

Cooling capacity 20kW
Refrigerant R404A
Reference temperature Dew point temp.
Evaporating SST -10°C
Condensing SCT 45°C
Liquid subcooling 5K
Suction gas temperature 10°C
Power supply Standard 50Hz
Useful superheat 100%
Capacity regulator 100%
------------------------------------------------------------
Output:

Compressor type 4V-6.2Y 4T-8.2Y
Cooling capacity 17.05 kW 20.9 kW
Cooling capacity * 16.56 kW 20.3 kW
Evaporator capac. 17.05 kW 20.9 kW
Power input 7.46 kW 9.17 kW
Current (400V) 12.16 A 14.89 A
Condensing capacity 23.3 kW 28.6 kW
COP/EER 2.28 2.28
COP/EER * 2.22 2.22
Mass flow 515 kg/h 632 kg/h
Operating mode Standard Standard


------------------------------------------------------------
*according to EN12900 (20°C suction gas temp., 0K liquid subcooling)


DATA R507a

13/01/2004
------------------------------------------------------------
Compressor Selection: Semi-hermetic Reciprocating Compressors
Input Values:

Cooling capacity 20kW
Refrigerant R507A
Reference temperature Dew point temp.
Evaporating SST -10°C
Condensing SCT 45°C
Liquid subcooling 5K
Suction gas temperature 10°C
Power supply Standard 50Hz
Useful superheat 100%
Capacity regulator 100%
------------------------------------------------------------
Output:

Compressor type 4V-6.2Y 4T-8.2Y
Cooling capacity 17.50 kW 21.5 kW
Cooling capacity * 16.99 kW 20.9 kW
Evaporator capac. 17.50 kW 21.5 kW
Power input 7.46 kW 9.17 kW
Current (400V) 12.16 A 14.89 A
Condensing capacity 23.7 kW 29.1 kW
COP/EER 2.34 2.34
COP/EER * 2.28 2.27
Mass flow 548 kg/h 673 kg/h
Operating mode Standard Standard


Did you found other numbers?

Peter

[chemi-cool]

peter, I will check it again.

richard, that's a great story, I alway thought the germans had problems to see the difference between potatos and computers.

chemi

[chemi-cool]

peter,
my software version is 4.0.
thats the difference, doesn't make sense, it should be the same.

chemi

[DaBit]

R507 is slightly more efficient than R404a, from a compressor point of view. This is not necessarily valid for the system as a whole.

The small glide of R404a might increase evap/condenser efficiency somewhat. This could easily offset the 1-3% more efficient R507 alone.

No idea about other effects the change of refrigerants has. The only real way to test it is to put it into a real system, and measure with the same conditions.

[D.D.KORANNE]

Hi,
Try BOCK range of semi-hermetics for an evaporation temp of say -20 to -45 deg C in SINLE STAGE version ,HA series. Noiseless,offer a far superior performance without any liquid injection even for R-22 .

Besides, for any application between 10 deg & -20deg C , try HG series.

Besides, open machines BOCK series are known for good performance .

Contact me if you need further help !

Regards,

D.D.KORANNE

[Peter_1]

Hi,
Besides, open machines BOCK series are known for good performance .

And for oil leaks on the shaft-seal.