Printable View
Dear Guys.... how r u..?
Does anybody know how to see the performance of screw compressor?
Also the screw compressor capacity is always drop 15% from 100% capacity, is it correct?
Its mean if the capacity indicator is 100% but actuallly performance is only 85%.
Please kindly advice and share...
many thanks
Faryuki;
If I understand your question correctly, you are questing the pumping capacity in relation to the Slide Valve Indicator.
At 100% indicated slide valve , the Compressor is 100% loaded. At 0% the compressor still retains some capacity (about 15%). This is a function of the design and cannot be changed. There are other factors involved as well.
The capacity stated by the compressor maker should be taken as correct for given conditions. The standard for fixed vi compressors is to allow 10F , 5.6 C superheat at suction conditions.
The efficiency is very dependant on the compressor being of the correct vi , if fixed, for the duty.
Note the duty and efficiencies are based on compressors on full load duty. Once the slide valve moves off 100% and certainly any thing below 85% then the power ratio to effective refrigeration becomes very inefficient.
Note new machines with variable vi such as the Frick compressor with a Quantum Controller over comes much of the conditions described above.
Dear Faryuki,
Some screw compressors have a support for the slide on the 100% side. It means that when the slide starts to inch forward towards full load, at around 85 to 90 % it rests against the support and the load goes from 85 to 100% . So it is like a jump in the capacity.
It moves from 25 to 85 in a stepless fashion but
it will jump by 15% once it is at 85 %.
And exactly reverse is also true when it unloads from 100%.
Thanks
Quote:
Originally Posted by faryuki
Hi, exyork :)
Please can you tell us exactly which screw compressors are constructed in that way-York, Frick, Sabroe, or.....and also can you explain ..."jump in the capacity"..."jump by 15%".... according to that we do not have stepless capacity change:confused:, why? please explain...Quote:
Originally Posted by exyork
...is that support maybe "Vi slide" or not.....are you speaking about real capacity position and calculated capacity position....
Best regards, Josip :)
....it's definitely about "Vi" position on compressor...
...just look on main many and if on screen is write 100% capacity,that is it....
guys,
i think you need to understand closely the manufacturing of the screw compressor well before giving such advice/s.
there is minimum load for screw compressor to be maintained during operation. some is 10% and some is 25%.
queston on drop of 15% ...
do you know you could calibrate physically the capcity indicator against the digital value?!
thus, 1st you must find out what your compressor baseline in operation and did anyone misalign the capacity indication.
others ... after you find out then we talk further.
hope that helps.
I think I caught a little bit of a superior tone there.:mad:Quote:
Originally Posted by hendry
This is a DISCUSSION Forum. We exchange ideas and discuss.
38 posts in your first three days. Shutting us off allready.
Have you applied as a Moderator yet?
Now, now NH3LVR...:D
No slight intended on our fine Mods.:DQuote:
Originally Posted by US Iceman
ya ... ya ...Quote:
Originally Posted by NH3LVR
:p
Quote:
Originally Posted by hendry
Hi Hendry:)
the reason the capacity indication jumps is the volume control slide is the end stop for the main slide. The volume slide moves forward with the capacity slide to shape the discharge port.
At different compression ratios the place where the two slides stop will be different, with the compressor creating different capacities at different VI or compression ratio, so the position of the slide will be different.
But the capcity indicator will always jump to 100% to show the maximum capacity available at the particular VI.
Hope this helps.
Kind Regards Andy:)
thank you, Mr.Andy.Quote:
Originally Posted by Andy
this has been acquired prior to joining this forum.
anyway, no harm for revision.