[cold as ice]

Hey Boys!

I was at a conference in Urbana Illinois where a paper was presented by a consultant to the Department of Energy. He presented 3 case studies that were independently monitored of which 2 were done by OEM's. The information is available through IIR (International Institute of Refrigeration) and had "HVFT" in the title. High Vapor Fraction- Turbulent I think.

Anyway, after that conference, I tried it in chiller. Put the valves in downstream of the TXV on a shell and tube evap where we had a series on compressor losses due to liquid overfeed in low load conditions. The customer had oil fluctuation and logging with high head temperatures. This process application had very high load at one time of the year, and very low load at another time, with corresponding SST variations.

It was a bit undersized before putting in these valves, and afterward, seems like the evaporators are able to pulldown to temperature in high load about twice as fast, at least a third faster. In low load, seems about 15% faster. We got oil back and oil level is now consistent.

We have had the utility company, 4 consultants, and now about 6 corporate maintinence know-it-alls come through. No one can explain the gain.

They can't because they didn't read the paper or literature.
Heat transfer is improved through the inner film. Simple fluid dynamics. More surface area to boil makes it all faster and more responsive.

We have now installed a few others with air side benefits that we didn't see in the chiller related to frost films instead of bridging.

 

[cold as ice]

look at supplymike's post 10/2001

Andy wrote:
The XDX product claims to improve evaporator heat exchange effectiveness by inducing two-phase refrigerant flow which better wets the insides of the evaporator tubes. That's fine, and no doubt if this is the case it will increase suction pressure, reduce coil TD, and reduce the number of defrosts for refrigeration applications.

Any is right... Imagine that I just said that a man was right... #%&*$%!

I saw two things of great interest, 1 on the website, 1 at ASHRAE
1)the first was a graph showing the surface of the evaporator in a freezer where the coil was warmer than the dew point of the air after the retofit to XDX. They had the freezer, a standard reach-in from a big name OEM... I don't remember whose it was... It ran at ASHRAE in January with a digital video on the coil and electronic monitoring showing the box as at minus 10F for 4 days without a defrost... the coil frosted, but only as a fine glaze... We have all seen coils sized for less than ten degree TD, XDX has found that uniform coil temp lets the frost form evenly... spreading out defrost... The end result is that when it shuts off and satisfies, the film, or part of it, goes back into the air... even at minus 10F... It explains what we saww in an icecream plant where we reduced defrost to 1/4 of the time it needed before.
2) the second was a letter that some engineer showed me from STANDARD refrigeration (They make chiller barrels) saying that in their lab, this valve got to temperature twice as fast as without it, during the pull-down.

the defensive remarks about selling back power? ... I haven't seen claims like that anywhere...

There is a post from 10/2001 on this thread of interest...

Clearly something here... I wouldn't discount it too fast , boys... Its a money maker... I have resolved a couple of capacity issues by fine tuning the evap performance with this thing... I made $ on installing it, and looked good afterward.

I will be at two trade shows this month and will update everyone if they have new info