PDA

View Full Version : xdx valves



chefid
06-04-2007, 04:44 AM
has anybody else had to deal with these and if so what do you think of them i am not a rep. so be honest

lana
06-04-2007, 09:25 AM
I have not used them. I have seen the commercials about it but I don't know how these work. Anybody ?:confused:
As far as know these are installed after the TEV and before the evaporator.
Also this XDX makes the flow of liquid refrigerant Annular in the tubes so the heat transfer is improved.
I would love to know more about what they do?
Cheers

US Iceman
06-04-2007, 03:06 PM
I would love to know more about what they do?


And that makes two of us who would like to know how these work. Annular flow sounds sexy, but how do they get it with a "black box"?

NoNickName
06-04-2007, 03:06 PM
I'm quite reluctant in understanding the working principle.

lana
06-04-2007, 03:11 PM
I'm quite reluctant in understanding the working principle.

Why for crying out loud? :eek: :eek: :confused: :confused:

Brian_UK
06-04-2007, 07:51 PM
I haven't read the website yet but it's very "sexy" in advertisers parlance.

They have various video downloads to show the effects.

http://xdxusa.com/index.php

Dan
07-04-2007, 01:03 AM
They are heavily marketed (overly promised) but do change the refrigerant flow so you have a thin layer spinning (annular flow) at the very beginning of the evaporator. The advantage of this flow is that more work is being accomplished at the beginning of the evaporator, and that the higher rate of flow means less volume per square inch and that makes superheat control more easily and effectively accomplished, thus you are using more of the latter part of the evaporator more effectively. Or so the theory goes, anyway.

Since you are making better use of the evaporator surface area due to the annular flow and better wetting of the tubing, the frost pattern is spread more evenly, requiring fewer defrosts, and the suction pressure can operate more efficiently, etc. etc.

Everyone that I have seen installed has been cut out. Each installation was a "trial" installation and covered 3 different supermarket chains as well as a produce storage facility.

I cut one apart and looked in it. There is nothing in there. I was amazed. I am of the opinion that it does something interesting and worthwhile but its benefits are oversold, and it has sufficient problems at least at the technician level as to be one more device that eventually becomes eliminated after initial testing. It's objective is worthy, just as an inverter's objective has always been worthy, but until recently, every inverter I saw had been disabled... and I am talking about a lot of inverters. :) Microchannel tubing and some of the other heat exchangers appeal to me more as accomplishing improvements in surface to air heat transfer.

US Iceman
07-04-2007, 01:09 AM
They are heavily marketed (overly promised) but do change the refrigerant flow so you have a thin layer spinning (annular flow) at the very beginning of the Evaporator (http://www.refrigeration-engineer.com/forums/glossary.php?do=viewglossary&term=70). The advantage of this flow is that more work is being accomplished at the beginning of the Evaporator (http://www.refrigeration-engineer.com/forums/glossary.php?do=viewglossary&term=70), and that the higher rate of flow means less Volume (http://www.refrigeration-engineer.com/forums/glossary.php?do=viewglossary&term=105) per square inch and that makes superheat Control (http://www.refrigeration-engineer.com/forums/glossary.php?do=viewglossary&term=144) more easily and effectively accomplished, thus you are using more of the latter part of the Evaporator (http://www.refrigeration-engineer.com/forums/glossary.php?do=viewglossary&term=70) more effectively. Or so the theory goes, anyway.

Since you are making better use of the Evaporator (http://www.refrigeration-engineer.com/forums/glossary.php?do=viewglossary&term=70) surface area due to the annular flow and better wetting of the tubing, the frost pattern is spread more evenly, requiring fewer defrosts, and the suction pressure can operate more efficiently, etc. etc.


I thought I was reading their marketing brochure until I got the next part.



Everyone that I have seen installed has been cut out.


That raises a lot of questions. Did they work or didn't they. Or, is there another simple answer?

I would love to see the unit that was cut apart Dan. Any pictures?

NH3LVR
07-04-2007, 02:00 AM
Hate to be this way but they sound like "Snake Oil" to me.
For those who do not understand this expression due to their language or culture it means "A worthless preparation fraudulently peddled as a cure for many ills".

chefid
07-04-2007, 03:02 AM
i have installed a few of them but it seems you have to go against a few basic rules of refrigeration to do so. it also seems it is marketed to people who are easily fooled by fancy charts and curves

Dan
07-04-2007, 03:35 AM
easily fooled by fancy charts and curves

Actually the pressure enthalpy chart. It's why I hate it. Willis Carrier's psychrometric chart, to me is a miracle of understanding. The refrigeration pressure enthalpy chart has always struck me as obtuse, inaccurate, and easily used to tell lies or exaggerate. I blame it all on Entropy. Willis was wise enough to ignore it. :)

Dan
07-04-2007, 04:11 AM
That raises a lot of questions. Did they work or didn't they. Or, is there another simple answer?

It does raise a lot of questions. For example, in one case, the device failed to perform when I inherited a store... but there was also a refrigerant change-out between the installation and its failed performance. It might never have performed, or it might have stopped performing. But it became one more device to have to ponder when things were not feeding properly.

In the Produce cooler, the promise was that the coil nearest the door would not frost up as rapidly. This simply did not pan out. There was also several attempts at making a blast cooler work better, and again it took several attempts (experiments?) at sizing distributor orifices to vain conclusion. I am not remembering in detail, but the XDX is used as a "pre-distributor" and thus loads can affect the performance.

In the early days of discussions in Marc's discussion group, and perhaps here, too, Professor Sporlan seemed to take the theory, if not the design, as a valid concept.

Me? I enjoy seeing new things even when they don't work and are not practical. I know they are the future once they become simplified. In America, Fulton and Watt argued and consorted to invent the steam engine, if we are allowed plausible history. Fulton was the technician, and Watt was the inventor, perhaps.

I have heard that it was the invention that preceded the theory... and I believe it. Watt refined his theory after Fulton made a steam ship. But I also know there has to be a theory to precede invention.

In sum. A good idea in theory, must be tested and refined more thoroughly than these weak attempts with large promises, and rather become a strong attempt with small promises.