Indirect Evaporative Cooling an H13 Hexayurt

[HarryN]

Complete air exchange every 1 to 3 minutes, and you're cool.

Design accordingly!!!

Hi - I know from reading your threads and posts that you have made a long term, key contribution to the development of the bucket coolers / direct evaporation - and I completely acknowledge this.

This particular thread is about "indirect evaporation", which is slightly different.

Honestly - would you really want everyone who is interested in a topic to be a "conformist" in a BM forum? I am definitely not. I build my own stuff all of the time regardless of BM or not, and definitely enjoy taking the path less followed. I don't mind failing - really good at it.

[Canoe]

... The bucket cooler is a fun little gadget for people playing around on the playa. At the same time, it is pretty far away from what is required to be comfortable in those conditions. ...

Hi - I know from reading your threads and posts that you have made a long term, key contribution to the development of the bucket coolers / direct evaporation - and I completely acknowledge this.
This particular thread is about "indirect evaporation", which is slightly different.
Honestly - would you really want everyone who is interested in a topic to be a "conformist" in a BM forum? I am definitely not. I build my own stuff all of the time regardless of BM or not, and definitely enjoy taking the path less followed. I don't mind failing - really good at it.

If you don't see it now, I don't think we can help you.

[Plumitt]

Well, we're back. Nice to see some further action on this thread.

I psuesoburned in '21, and tried a few things, most of which didn't work.

1) added another evaporative cooler, replaced the existing cooler. Both started from standard ice chests/coolers.



I tried using hollow lids for water distribution to avoid PVC by plumbing water into the lidsl tops and then drilling holes for water distribution. One lid burst before I left and switched to PVC water distribution. The other burst on playa when I gave the pump (accidently) full power. It's a bad idea, don't do it.

2) changed the airflow so there is no internal recirculation -- outside air gets cooled twice via heat exchange and is split into half product air (cools the space) and working air (is evaporatovely cooled twice & exhausted).

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Balancing the airflows was hard, and either a) my parallel fan arrangement got way less than 3x the power of one fan, or b) I was trying to pull too much of a volume of air. I was more or less unable to get sufficient air flow back through the system, So I ended up cutting out the second cooler.

3) rebuilt my heat exchanger to a more typical "stack of diamonds" with two zig-zag flows through 3 crossflow stages (rather than the S plus straight flows previously. This worked.

4) added an incoming air dust filter, which now that I look at it, should have just been on the cool air output. It contributed a lot of volume to the space, particularly after the fans which may have been a problem with the airflow.


5) added a shade cloth to the H13 yurt with a pretty simple frame.

[Plumitt]

other pics.

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[Plumitt]

one mo

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[HarryN]

one moScreenshot_20220316-143226_copy_360x271.png

Thank you for the update and info. I am still studying your updated design and approach.

In my mind, one of the big challenges with evaporative cooling is underestimating the amount of water that needs to be evaporated in order to be as comfortable as possible.

I used several methods to estimate this amount including some simplified engineering calculations (2 methods) , info about trees, two different commercial evaporative coolers, and a simplified test in my driveway.

Pretty consistently, on a hot dry day (100 + F) , it will take ~ 1 gallon of water to be evaporated / per day / per square foot.

So a 10 x 10 space will need ~ 100 gallons of water evaporated per day to be really comfortable.

It might be that your design might need to use an aluminum or similar heat exchanger to get the transfer rates up.

I am very impressed by your continued efforts in this area, even though it isn't working perfectly.

Let me know if there is a way that I can be helpful to your work.

Harry

[Plumitt]

I'm consistently able to keep an h13 hexayurt under 80° even on 100° days using only about 3 gallons a day. perhaps four. Your calculations must be off somewhere as an h13 hexayurt has about 180 ft².

also, regarding heat transfer in the heat exchanger, an engineering guide to heat recovery ventilators suggest that the material used for the air-to-air heat transfer is not the primary driver of the efficiency. I don't know how true that is if the material is two orders of magnitude less efficient than aluminum however. (aluminum ~170, coroplast prolly ~3).

[HarryN]

I was trying to figure out the large difference in your water use vs my calculations and tests.

Then it occurred to me. You are cooling an area inside of a highly reflective space / tent with insulation.

My setup was based on cooling a similar size space - but completely out doors with no walls or roof.