Tent (yurt) swamp cooler v3: no soldering, with measured airflow vs noise

[alexdegtiar]

Long-form build guide plus a emperical odessey for a tent version of the classic yurt cooler
(v1: yurtcooler.com; v2 builds by Oskar Arvidsson and Joanna Ma; v3: this guide).

Core change: the 12V bilge blower and hand-wired PWM become a single EC inline duct fan (AC Infinity
CLOUDLINE H4) on a power station's AC outlet. No soldering, no electrical work - a hole saw and hose
clamps, 2-3 hours, about $225 before the battery. Same wick-in-tote evaporative core as v1.

Guide (7 tabs: build, power & water, on-playa routine, troubleshooting, measurements, credits):
https://docs.google.com/document/d/1HfC ... zDMwM/edit

Every raw reading, the method, and its known weaknesses:
https://docs.google.com/spreadsheets/d/ ... A3/pubhtml

Headline numbers - both fans on the same cooler, same wet wicks, minutes apart:

- Across 43-53 dB, the range you'd actually sleep in, the H4 moves 80-105% more air than the blower at
the same measured noise. At 47 dB, an exact match, more than double.
- Saturation efficiency about 80% (+/-15) with no speed trend I could resolve across all ten speeds, so
cooling scales with airflow and the dial is a noise-and-power choice rather than a cooling-quality one.
- 3 / 9 / 28 W at the wall at speeds 1/5/10, giving roughly 25 / 13 / 7 hours on a 288 Wh power station.
- 39 dB at speed 1 (my room's noise floor) rising to 57 dB at speed 10, about 2 dB per step.
- 1-2 gallons of water a day.

Absolute CFM is a manufacturer-anchored ballpark only (roughly +/-30%) - my hot-wire anemometer reads
about 5x low against the fan's free-air rating, so I report airflow as relative. Every caveat is in the
Measurements tab and the sheet.

This is the crowd I most want to hear from, so here is what I am least sure about:

1. Dry wicks restricted airflow MORE than wet ones. Consistently, both fans, every speed - wet passed
roughly a third more air. Fresh dense spares versus relaxed used media, or something else?
2. The anemometer reads about 5x low in a 4" duct. What is the right way to get absolute CFM without a
flow bench? I suspect the probe is not sampling the jet core.
3. Does about 80% saturation efficiency hold at a real 35 F playa depression? I measured indoors at only
9-12 F, so the playa figure is an extrapolation.
4. My daily power budget does not close on solar alone once an overnight air purifier is in it. Should I tweak the settings, just get a bigger battery/panel or just stop being a baby and snort some dust?

Method weaknesses are all listed in the sheet: single probe, closed room, small wet-bulb depression,
phone SPL meter. Tear it apart.

And if you're trying to build one before you leave this year, ask here and I'll answer fast. I'm around
all week til 9/1. If you're finding this thread later, my email is in the guide.