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A new technology i have seen is fallin film evaporators. This has a small pup which pumps the liquid refrigerant in the bottom of the evap to a distributor plate on the top which coats the tubes in refrigerant by dripping the refrigerant like a shower head. This raises the efficiency of heat transfer and uses less refrigerant.
Can you get some links? pics?
This sounds just a spray chiller.;)
Hi All
There is more info on falling film heat transfer in the Perries Chemical Encylopedia. This is probly old hack but has not been applied to many systems, along with vortex technology.
Trane's newer screw chillers (C-series onwards iirc) use falling film. You'd think it ws simple, but I've seen the distributor plates in the factory. When you look closely, you see the holes aren't evenly spaced, or even the same shape. This is to get an even spread of refrigerant along the whole coil length. It's pretty interesting stuff.
B”H
I would like very much to find a small and reliable refrigerant pump.
The advantage of the falling film evaporator is that you reach almost the same efficiency as with flooded models but with less refrigerant (charge). The distribution of the liquid refrigerant evenly accross the entire htx length is the secret which you have to reveal. This takes a lot of effort in testing and desinging. This technology is used since decades in LiBr Absorption chillers. It is the same like Microchannel htx they trying now to promote as state of the art hvac technology but basically its the same as a 100 year old car engine radiatior.
I think this is old technology, this is being used mostly in water chiller which the temperature is very close to freezing point (eg. +1C). This is also used in carbo cooler of softdrinks industry.
You are right,Entropie.Quote:
Originally Posted by Entropie
The falling film evaporator is not a new technology, it's quite common in chemical industry. In HVAC field, it is something like the Centrifugal Water Chillers, the refrigerant falls from the top of the evaporator, across the tubes and down to bottom.
There's not much problem in Centrifugal Water Chillers coz there are no lubricant return problem, but in screw chiller, you need to figure out the best way to return the oil.
Trane develop this kind of chiller several years ago, but it seems not too many manufactures follow their step and their sales of falling film chiller seems not so good. There got to be some reason. But I don't know why.
Falling film to me means falling water film over plates, didn't Chester Jenson marketed a similar multiplate system years ago.
For high efficiency evaporators, try high liquid regeneration liquid flow with sub-cooled high pressure liquid at condenser pressure. The evaps are super efficient.
magoo
No thats really old tech, The falling film im talking about they use a pump to pump the refrigerant from the bottom of the evap to a distribution plate on top this then distributes the refrigerant across the tube bundle making the gas easier to release and the refrigerant charge lower.
Refrig Side Falling Film nowhere near new, and there are lots of water chillers out there using it...as Iceman noted. Redwater chillers as utilized in the poultry industry in particular. Also certain styles of brewery and wine chillers. Often to achieve close approach to freezing, but also to permit "open heads" on the fluid side thus permitting cleanout of tubes & passages.