Tales from a Ventilation Lunatic

[rvpopeye]

I know musicians that would envy how many fans you have.....
Ba dooom tsssssh

[sternwake]

Using the twin 140mm fans on the workbench aimed at my belly on a hot day..reveals the fake Delta to be the less effective fan, by a good margin. Even if I turn it up way higher than the BDS, its flow is not hitting my belly, but more like my neck and off to the sides.

Perhaps if this fake delta fan with the lesser angled longer forward jutting scythe like blades, were attached to blow into a restriction, like a busy finned heatsink, it would perform better in comparison, but in free unrestricted air the steeper more numerous blades of the BDS clone, are far more effective in velocity and column like flow.

The hubs steering vanes of the fake delta are also not angled as steeply. Everything about this fan says it is designed for high static pressure as opposed to high airflow, but even when I stick my hand closely in front of either fan at the same free airflow levels, the BDS fan seems less annoyed by the restriction. but this is far from an ideal static pressure test. and perhaps the BDS scavenging air right next to the fake delta is much more detrimental to the delta's flow than the other way around.

I think the fake delta's design would be good for my restrictive mushroom ceiling vent, but I am not going to make a 140 to ~102mm step down ring for it ,and the 120mm delta up there is very effective already, and much closer in blade design to the BDS.

Seems the fake delta threw a piece of balancing tape as well. It can achieve rather insane rpms. I have used a 5 K ohm 10 turn potentiometer on it and it is rather annoying to have to turn it 7 to 8 full turns to get it from minimum to maximum speed.

Need more potentiometers......

[sternwake]

Tried another test...... holding a piece of wood, about 130mm wide, in front of either of the 140mm fans, making about the same noise at the lower end of their available speeds. I can easily push the wood up against the face of the BDS fan and hear fan blades stall with little air being forced around the edges.

Doing the same to the fake delta, and it takes about 3 times as much force to flatten the piece of wood against the face of the fan, and much more air squirts around the edges. While the fake delta fan sounds different than when not restricted, it does not change note/tone nearly as much as the BDS and its fully stalled blades.

This was expected, the only thing surprising was my estimation of the force required to flatten wood against fan's face. I expected it to be not quite 2x, but requiring 3x or more was surprising.

Obviously this is an estimation and I also do not know the fans rpm and didn't bother to test amp draw to make teh 'test' more scientific, as its just not that important, and nobody is paying me to do it.

When the fans are making about the same noise unrestricted, the BDS fan is moving a lot more air, and these tests were done with fans making same amount of noise, and While I could measure the sound, well again, its not that important.

At higher fan speeds the fake delta pushes itself backwards away from wood, while I can still flatten it against the BDS without it moving.

I have a slider window where my feet go while sleeping, opposite of where my 3 fan intake shroud lies. I think if I really wanted to employ the fake delta fan, It would excel exhausting through the screen and chicken wire security mesh on that foot slider. It would likely be good for sucking air through that dual barrier too, but The 52mm thick 140mm 24v delta fan sucks more air when restricted by both of those, AND my activated charcoal filter material, compared to how much the unrestricted fake delta pushes without restrictions.

Honestly in terms of sheer power, the 24v 140mm x 52mm Delta 'mother of all fans' has no equal that I care to pay for, and 2nd place is way far away.

Can't remember the last time I opened that 'foot' window. If I ever get a bad case of incurable stink foot, then I have a great fan for keeping the stank out of the rest of the van.

It would also be pretty good if attached to an tightly finned Aux transmission cooler as a pusher fan, but I do not know how much my amazing goop and nail polish ministrations increased its ability to handle moisture and resist circuit board corrosion.

Pretty pathetic I have more fans, than uses/needs, for them.

Anyway fans with blades jutting forward at lesser angles excel in forcing air through restrictions, but shorter more numerous blades angled steeper move significantly more unrestricted air and at a higher velocity.

Not a Eureka revelation, by any means, but perhaps valuable info to the reader.

[Roadtripp]

I did a search for swamp cooler and did not find any experiments with mini swamp coolers? Do you think this idea is worth pursuing? I suppose water is in scarce supply so maybe not.
The other thing I wonder about is why are swamp coolers such huge fans?! Maybe lots of surface area is required to evaporate the water.

[sternwake]

There are small household evaporative coolers available, with extra special marketing claims..

here's the first link I came across:

https://www.amazon.com/HAPPEEY-Personal-...4554129011

I've only done a few evaporative cooling experiments, and only one where I actually tried to collect data. I was aiming a fan at a very damp hanging bath towel, and measuring the temperature downstream of the airflow. I can't remember the numbers, I think downstream objects were~ 2.5f cooler than upstream and the damp towel itself 10f cooler than a dry towel hanging nearby.

It does work, and works better the less humidity is in the air.

Before I achieved violent windtunnel status, on the extra hot days, which around here are usually super dry, I would dip a sarong into some water and spread it over my body, and if it was 95F outside this sarong would get as low as 67f and suck the heat out of my body, at least until it dried. I'd actually be able to get the chills and goosebumps on the hottest of dry days, and have to limit how much of my body was in contact with the sarong, or how much fan flow was directly hitting the sarong, or both.

When I would redip the sarong in a large coffee container half filled with water on the floor and squeeze out the extra, i would feel all this heat squeeze out, and run up my arms.

There's some physics outside my existing grasp here,......but, the heat has to go somewhere.

I believe in my hanging wet towel test with fan aimed at it. the heat released from towel and water within rises quickly to roof and the cooler air falls. If this heat is not sucked out of ceiling efficiently it likely just gets sent back and reduces efficacy.

My 3 powerful intake fans by my bed, I use these to levitate all my bedding for an hour or 3 depending on where my battery and solar is at, by hooking the elastic bottom sheet over the fan bodies, and all subsequent bedding levitates upto 10 inches off the mattress. If I shower/bathe, then lay my damp towel over this levitating bedding, it gets very much noticeably cooler in the bed area, quickly, and the towel itself gets downright cold.

I've considered various methods to either keep a hanging towel damp using gravity or perhaps wicking, but have yet to pursue it, as air exchange alone in my location is more than sufficient 98% of the time, and I can likely exchange all the air inside my van several times a minute with all intake and exhaust fans cranked up.

I think the small swamp coolers marketed all over the internet at the start of summer are using some sort of wicking fabric, that a fan forces air through/around, and have a reservoir of water that needs to be replenished every so often. The other option would be a small pump raising water over some sort of fabric through which the fan blows.

I suspect in a Closed off room, they just make the roof hotter and the floor cooler, and add more humidity all around.

The more surface area, and the more water evaporating that can be accomplished, the more heat can be extracted and sent to ceiling, and cooler air to pool on the floor. At some point that heat on the ceiling reaches the cooler air on the floor, so sucking the heat from ceiling would seem to be very important to keep the cycle going, but then this exhausted air needs to be replenished from elsewhere.

Maybe indoor swamp coolers can simply be considered humidifying air stratifiers.

Add one to a completely enclosed room where everywhere is 75F and after X amount of time, the roof becomes 85F where the floor becomes 65f, and humidity raises from 50% to 60%. At some point the ceiling gets no hotter, the floor no cooler, but humidity in the room keeps rising making the process less and less efficient as it does.

So strategy of employment is as important as the actual physics of evaporative coolers, in an enclosed area. Hot air exhausted from up high, should be replenished from the coolest possible source down low.
This should be done anyway, with or without some sort of swamp cooler present, it's just with it, the heat is extracted and sent to ceiling faster than it would otherwise stratify.

I wonder if there could be some sort of heat extracting 'snorkel' just above an enclosed swamp cooler to send right to the exhaust fan and help increase their efficiency.

That heat running up the insides of my arms when redipping the dry sarong in super low humidity...needs some more thought.

[Roadtripp]

Stimulating ideas. Maybe with a snorkel the space can slowly fill with cooler air. 
 Perhaps a dehumidifier and evaporative cooler running simultaneously? 
 Just tossing out thoughts. I just started reading about evaporative cooling. 
 I miss the misters I had in my plant nursery years ago. They felt awesome on a hot day. Similar to a damp sarong I would imagine.

[sternwake]

Misters do work well too, when the droplets, which cool as they evaporate in their route to the ground, that land downstream are of no consequence.

The thin damp sarong in low humidity works amazingly well to suck heat from one's body. It's like an ice blanket. A thicker cotton towel with a fan preAimed at it for a period of time, is even more effective when laid on an overheated portion of skin. If one does not feel overheated, then one need not expend a lot of energy trying to cool the immediate surroundings.

[sternwake]

I just got a text from the dual 120mm Jaro fan recipient, thanking me.

Says he's never slept better, and now does not know how he lived without air movement previously.

He's pretty clueless about batteries and their charging and was wondering how much battery juice he was using, How long he needs to idle his engine in the morning to replace what he used overnight.

The correct answer of course, would make his head explode.

I'm gonna hook him up with a digital voltmeter inside a ciggy plug.
It's one I pulled from my own dash after a few years service. Green, too bright, only shows tenths of a volt.

I'll see what he can grasp, then make his head explode....

He really needs a small solar panel to give his battery a chance at a decent life. but.........

[rvpopeye]

As I watch my clueless neighbors play that idling game several times daily...(with their headlights on !)
I remember them telling me that they have been boondocking for 5 YEARS and really know what they're doing now.
At least your newb doesn't have a closed mind.
He's got a chance !
Don't blow his mind just yet.....Skuh kuh kuh kuh kuh

[sternwake]

Your genius professional  boondocker neighbors were likely told that turning on the headlamps kicks the alternator into high gear.

Many people give the alternator's voltage regulator and alternator itself, mystical powers of enlightenment and capability.  Its rather astounding the level of ignorance concerning vehicle charging systems by the general public.  Its like old wives tales on steroids, but more like grandpa's delusional ignorance repeated until chiselled into stone

I guess on some vehicles it is possible that a load on headlamp circuit tells the VR to seek higher voltages.  Whether this higher voltage makes up for the load of the headlamps depends on the alternator's capability at idle.

Most vehicles the 15 amps feeding the headlamps and signal lights is 15 amps not going into the depleted battery. 
 It's kind of like throwing a blanket over 280 watts of solar near noon and saying:
"That will get 'er done,  Yup." while looking around to see who noticed them being so smart, not dumb, but very beautifully smart.

The Jaro recipient is no brain surgeon, but seems to have a good heart, and has done me no wrong. I've met some good people through him, and known who to avoid, rather than finding out the hard way.

I am liking the ciggy voltmeter in daylight in my rig. passing low clouds I can easily see voltage drop the same time it gets darker outside then shoot to 14.7v when it gets brighter.  In absorption...7.6 amps into battery at 14.7v.