View Full Version : New Capacity Control Solution

06-12-2003, 06:09 PM
Hello Everyone,

My name is Emilio Brown, president of Tri-County Refrigeration Inc in Miami, Florida. I have been a refrigeration contractor and engineer for over 20 years. In dealing with parallel reciprocating compressor systems and racks I found myself trying to use inadequate means for smooth capacity control as provided by compressor manufacturers so we decided to design and build our own system. Im looking for some feedback and to speak with some engineers that might have a use for this system in current or future projects. Please feel free to post any questions or comments or contact me directly.

Capacity Control System Kit (Cylinder Loader/Unloader) for Reciprocating Compressors

Here it is..

To provide a complete system (Kit) to control Cylinder Loaders/Un-loaders in Reciprocating Compressors of any brand or manufacture. The system will accommodate any number of Loading and Un-loading Stages per compressor and will also accommodate multiple compressors. The system shall operate with all types of refrigerants (NH3, Halocarbons, etc.).

The complete system, to be named Complete Capacity Control Kit, shall consist of the Mechanical Section and the Controller Section. The Mechanical Section shall incorporated a perforated metallic block and solenoid valves to achieved the conveyance of pressurized oil when specific cylinders are required to “Load” and return the oil to the crankcase when specific cylinders are required to “Un-load”. The Controller Section shall be manufactured in two (2) different forms. The first form is the Electromechanical Controller which shall be manufactured using conventional relays, timers, and only two (2) pressure switches and is designed to sequentially control the stages for loading and/or unloading of cylinders, in multiple compressors, within a minimal (6-8PSI) pressure differential. The second form is the Microprocessor Based Controller which shall be manufactured using the latest microprocessor control technology. The Microprocessor Based Controller, using one (1) Pressure Transmitter, is capable of controlling the sequential loading and/or un-loading of cylinders, in multiple compressors, with pressure differential as low as practical and tolerable by the process. When multiple compressors are used, the system will periodically sequence the operation of the compressors in order to promote equal wear of each compressor. The Microprocessor Controller can be extended to control Condensing Temperature by cycling and/or modulating fans and pumps for the system related Condenser. The Microprocessor Controller can even be extended to control entire processes.

1 – Complete Capacity Control Kit with Electromechanical Controller for all reciprocating
2 – Complete Capacity Control Kit with Microprocessor Controller for all reciprocating
3 – Electromechanical Controller for reciprocating compressors that have the factory installed Un-
Loader Heads and Solenoid Valves.
4 – Microprocessor Controller for reciprocating compressors that have the factory installed Un-
Loader Heads and Solenoid Valves.
5 – Electromechanical Controller for On/Off control of Pumps and Fans in Condensers.
6 – Microprocessor Controller for Modulating and On/Off control of Pumps and Fans in

Below is a link to a picture of the equipment.

06-12-2003, 07:02 PM
Hi embrown:)
are you looking to sell us something or give some technical input into something you are developing:confused:
Kind Regards. Andy:)

06-12-2003, 07:45 PM
Hi Andy:

I have developed and tested all aspects of the capacity control system and would like to both share the information and see if there is any commercial interest for this type of product.

07-12-2003, 02:24 PM
Hi Emilio:)
nice to see someone trying to improve something we all take for granted.
What is unusual to me is the idea of supplying the loading solinoides with the controller. ALL the compressor I have worked with in the UK and Irish market have their own loading mechanism built in. Are you aiming you product at compressor manfacturers:confused:
Kind Regards. Andy:)

09-12-2003, 01:13 AM
Hmmm. A manifold and a control panel? I personally wouldn't choose to redesign a compressor with all of my great ideas.:) I have seen how much trouble the manufacturers get into all by themselves when they introduce any of their long-tested and fool-proof improvements.

Like Andy, I enjoy new ideas, but I worry your idea is too young to walk on its own, just now.:)

09-12-2003, 08:19 PM
Hi Andy and Dan,

I appreciate the time taken to read and comment on the capacity control system.

I may need to adjust my explanation since both of you apparently understand that I plan to modify or add physical unloaders to reciprocating compressors. That is not the case.

My idea is to make efficient use of the mechanical unloaders already install by compressor manufacturers by providing the signal (usually hydraulic), from my manifold, to load or unload desired cylinders. The stages in the manifold will respond to the elctrical signals from the control panel which responds to a mechanical signal such as pressure.

09-12-2003, 09:10 PM
The hydraulic unloaders i know are mostly installed on NH3 machines (Grasso, Mycom...)
On the smaller machines like Copeland, it is mostly electrically controlled. We use on packs the signal from a pressure sensor with a dead band. On packs, only one compressor with unloader valves, the others allways 100% or full capacity.
I don't know which system or control mechanism you will use but will it give such a big gain in energy efficiency and are the presnet-day systems so bad?

10-12-2003, 06:20 PM
Hi Peter:
Thank you for your comments and inquiry about our capacity control system.

Hydraulic unloders, as you pointed out, are used in NH3 machines. The machines you pointed may also be used with halocarbons as well. There are other brands such as Carrier 5H & 5F series that also utilize hydraulic unloaders. Our system would provide the hydraulic signal to any of these compressors.

I would like to address the issue of how you handle packs, but befrore I address the issue, I would to see how you would handle the following scenario: Capacity control for a Medium Temp. pack consisting of three compressors in parallel, two compressors shall be used for normal duty and one for automatic back-up, each compressor has four cylinders (25% steps) and you must maintain constant TD (SST-Room Temp.). Additionally you must sequence the compressors daily for equal wear of all three compressors.


10-12-2003, 06:58 PM
Hi Emilio,
I think your idea was solved long time ago by Danfoss,
Please check the "compressor pack controller type AKC 25H5".
It does what you want and more.


10-12-2003, 08:28 PM
And also the EWCM900 of Eliwell (Invensys, which will be sold any time, probably to Danfoss I heard) at least even powerfull (i think even more) as the AKC and cheaper.
On the net you can find the comlpet manual http://www.climate-eu.invensys.com/UsersArea/796663044104698/EWCM_900_S.pdf
Perhaps I'm missing something.

11-12-2003, 06:44 PM
Hi Peter,
I have read your reply and have tried to look into the product you mentioned (EWCM900.) For some reason that link does not work for me and i was unable to find it on the site. I would like to see what that product actually does because I am not familiar with it.


11-12-2003, 07:13 PM
http://www.climate-eu.invensys.com/ then Commercial Refrigeration then EWCM 900 an then literature download or/and click also on the picture of the controller

11-12-2003, 07:58 PM
hi peter,
the ewcm 900 is by far less sophisticated then the danfoss akc25h5 not as friendly and deffinatly not as simple to program and operate.
i just prefer the danfoss to the eliwell when you need to control more then three compressors and up to 5 condenser fans.


13-12-2003, 08:47 PM
Hi Peter,
I have briefly looked over the information for the EWCM 900. Based on what I have read of the ewcm my product seems to be superior in many ways. I will be doing some more research on it so I can reply with an accurate comparison of the advantages of my system.

To Chemi:
I have not been able to locate information on the Danfoss Akc 25h5 on the Danfoss website. As soon as find it, I will do a compare its capabilities as well.

Thank you all for your time

13-12-2003, 09:34 PM
I have somwewhere the pdf files (on a CD) of the AKC.
I don't think you can find them on the net.
If interested, i can try to mail them.

14-12-2003, 01:33 PM

Yes, please e-Mail the files on the AKC so that I can evaluate the product.

Thank you

24-12-2003, 03:16 PM
Hello Guys,
Peter I have not recieved your email with the pdf on AKC so I can take a look at what its capabilities are before I explain the capabilites of my new system.


Happy Holidays to All!

24-12-2003, 04:08 PM

Sorry, forgot to do this. Did it right away after reading your last post.

Just mailed Emilio 5 different pdf files of the AKC 25.

If anyone else wants them, give me a call. They're to large to post here.


Merry Xmas and a Happy Newyear for all those who read this post. It jus tbegan to snow here in Belgium.

26-12-2003, 12:37 PM

Thank you for the info on the ACK-25.

I shall review it and post my reply.

Expect my reply after January 21 when
my busy season ends.

Merry Chriestmas and Happy New Year.


750 Valve
30-12-2003, 01:33 PM
What am I missing here?
Em Brown, you must be talking hydraulic unloading only. Not too many packs/racks have hydraulic unloaders - a four cylinder comp with normal unloading - (not hydraulic lifting of valves but by diverting pressure with a solenoid) have only 3 capacity steps per compressor... OFF(0%), 2 cyls unloaded (50%) and no cyls loaded (100%).
As far as your rack cycling question, if all comps are equal sizing, you ask for equal run times... the answer is easy- most electronic controllers on the market will do this out of the box. The more $$ you are prepared to pay the better they will do it. For supermarket racks we use Danfoss AKC55's, can run down to 1 psi dead band if you really want to, will auto rotate lead comp, delay timers, suction float and you can play for hours with PID settings to fine tune, CPC and Microm do the same too as does Carel, Dixell and Eliwell but on a smaller scale.