Evaporative cooler that cools below wetbulb temperature

[SAK9]

The claim is that fresh air can be cooled below wet bulb temperature without refrigeration.Has anyone on here used/come across this product?

http://www.climatewizard.com/

 

[berkshire]

I have not used this particular product , but indirect evaporative cooling units have been around for decades. A regular swamp cooler in conditions of low humidity can throw ice crystals. So they do have the capability of getting a heat exchanger duct down to below wet bulb temps. If there is a way of draining condensation out of the heat exchanger duct.
B.E.

You are judged not by what you know, but by what you can do.

 

[simangunsong]

Hmm.. New technology to me..
Tried to follow this the thread..

 

[LittleInch]

If you look at this page and click on technical explanation

http://www.climatewizard.com/tech-spec/

it becomes a bit clearer.

Essentially it is a two stage process as far as I can figure out. Initial cooling of the air take place by standard evaporative cooling inside a membrane honeycomb structure separated into wet side and dry side. Some of the dry side air returns into the wet side and because it is already at a lower temperature it further cools the dry side air.

Hence the amount of air eventually emerging as dry cool air is maybe 50% of the air entering the dry side with that air plus the original "wet air" exhausted out the top.

As with all evaporative coolers though, the diagrams in the brochures start with hot dry air (RH 20%), compared to what you might actually get, which appears to be 60-70% in say New York, Florida etc.

So somewhere like Riyadh ( RH of <20% in the really hot months) it would appear to be good, but lots of other places - e.g. Dubai on the Gulf coast - not so good as RH is generally around 60%. It looks like anything higher than 35C and 30% RH won't get you below 20C outlet air. however each system and location is different and if it just lowers the inlet air into a standard AC machine by 10 to 15C then it might be worth it.



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[SAK9]

Extract from the tech explanation:

In the example shown in Figure 3, air has entered an indirect cooler typical of the
construction type used for Climate Wizard at the nominal design condition of 38C
DB/21C WB corresponding to a humidity ratio of 8 g/kg. Cooling has taken place along
a constant humidity ratio line with the final delivered air condition of 16C DB/13C WB
and the humidity ratio still 8 g/kg. Note that the final delivered temperature is actually
below the entering Wet Bulb temperature, resulting in a wet bulb effectiveness of greater
than 100%. In the limit, with ideal heat exchange and evaporation, the temperature
delivered can approach the Dew Point of the incoming air.

I can not understand how the air can reach 16C without the aid of mechanical cooling.In order for air to get to 16C,the heat exchange surface needs to get to at least 14C to satisfy laws of thermodynamics.What is the process that drives heat exchanger surface to such a low temperature as 14C or thereabouts?

 

[LittleInch]

As far as I can figure it out (I'll remain to be corrected), some of the initial warm air gets cooled by the water evaporation which then cools the warm dry air in their super efficient HX. Some of this cooler dry air then essentially goes into a second HX and gets further cooled using evaporation and cools the remainder of the cool air and is then exhausted with the original cooler wet air. Remember this air is still at the same moisture amount as it was when it came in - maybe higher RH, but still capable of being cooled by evaporative cooling.

So if the total air in is say 100 units, then 50 units is used cooling 50 units of dry air. This leaves 50 units. This then splits into 25 units which is used to further cool the remaining 25 units (all numbers are nominal but I think you get the drift...)

Their trick is that this second cooling stage using now cooler, but still dry air occurs in the same HX, but I think it just comes back down the same pipes and the two air flows meet in the middle and get exhausted out the top.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[IRstuff]

I still don't get how the temperature gets below the wet bulb temp of the original air stream

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

[LittleInch]

Because they are doing it in two stages.

Look at the diagrams in the technical explanation. figure 1 - First pass goes from 38C @20% to 23C air at 75%. This cool air is used to cool dry air in their high efficiency HX to say 25C

Look at Fig 2 - some of the cold dry air is being returned into the "wet" channels.

figure 3 - In essence this 25 C air at approx. 40%RH is then subjected to evaporative cooling to approx. 17C at 75% RH. This cool wet air is used to cool the remainder of the cool air via the HX and hence it emerges at approx. 17C at 70% RH. 17 C is less than the wet bulb temp of the air you started with, but needs starting air at 20%RH and some very efficient heat exchangers. Also because it is all actually being undertaken inside a single unit the air entering the second stage is actually at a lower temp than my 25C air assumption. how they get that to work effectively is clearly their IP. It would work if they did it in two stages, but clearly would be a less efficient / effective.

But it all starts with 20% RH air! Even at 30% it would seem to suffer issues and 40% is not going to work for a A/C type usage. It would reduce heat load, but not be effective on its own.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[berkshire]

The key is that the air supplied to the building is not the saturated low temp air, that air is run across a heat exchanger then exhausted, the now cooled dryer air, is now sent to the building, if the heat exchanger goes below the dew point, humidity will condense on the walls of the heat exchanger enabling further cooling by re hydration further down the line.
B.E.

You are judged not by what you know, but by what you can do.