Improve an Air Cooler with spraying water 1

[aatara]

Hello to everybody.

I am studying the viability of spray water before an induced air cooler to reduce DBT air entering. My doubts are next ones:

1. Do you know experiences positives with this solution?

2. How could I estimate the real reduction of the DBT spraying a quantity of fine drops water?

3. What distance I need between the spray nozzles and the fined tubes to minimized the arrival of water non evaporated?

4. Quality of the spray water

5. Effect of non evaporate drop on the fined tubes of the AC

Thanks in advance.

 

[quark]

1. This was extensively discussed in a past thread. You have to weigh individual responses and then decide.

2. Consider the efficiency to be 80% maximum. The temperature drop can be calculated by making an enthalpy balance.

3. Rather playing on distances, it is better to go with a wetted surface cooler.

4. As good as practical (keep the hardness below 5ppm and check the absence of silicates and suspended particles). This was also discussed in past threads.

5. Corrosion.

 

[dcasto]

Do not even think about it. I've seen boiler feed water used and you still pick up so much corrsion and fin fouling that you'll replace the whole bundle in two years.

 

[aatara]

Thanks quark and dcasto

quark, I have this comments about your answers:

1. Could you indicate me what past threads are more useful for this topic? I didn´t find its.

3 & 5. The Air cooler was not prepared to wetted surface and then to suffer corrosion. Is there any recomendation to avoid this problem? (eg. orientation of spray nozzle, distant ...).

dcasto:

If I don´t allow wetted surface, coud I avoid the corrosion and fouling?

Thanks for your help.

 

[zdas04]

I see this done as a seasonal stop-gap for summer operation in low-humiditiy operations pretty often. It mostly feels like a desperation move to compensate for poorly sized equipment. It can work, but the two things that you need to be most concerned about are water purity (any dissolved solids will plate out) and droplet size. Below about 50 micron diameter, evaporation becomes a body function instead of a surface function, so if you gan get into the aersol flow regime you will have much better heat transfer and a lot less mess around the cooler.

David

 

[Montemayor]

aatara:

I hate to see any engineer break his back and his equipment in the process of trying to make a "trombone" type cooler work.

The best advice you've received is from dcasto. Take what he states seriously. I would not try what you are proposing; it's destined for failure and a lot of grief. You requested experienced comments, and I'm giving you a straight response resulting from personal experience. Fortunately it happened to me 2 years out of university, so I didn't break my back - but I sure had a sore backache for days. However, if you want to produce and sell a lot of calcium carbonate (although impure), go at it! But give up on ever operating your "cooler" successfully.

If you're interested, I still have black & white photos of me and my "crew" beating and scraping all the solids off the "coolers" that we were told were going to save us a lot of money by simply spraying water on them. That, I'm sure, will convince you not to go there.