Staying cool at night without A/C

[Redbearded]

Hi All,

First time poster here! Sofar I am a couch commando on this stuff so if I miss something obvious please be kind

So I have been giving the problem of hot nights a bit of thought (I dislike being too hot), at least from a solar A/C system point of view. It is expensive, heavy and impractical for most people. The thoughts I had were that as long as you have enough solar during the day it may be possible to store that energy in another form, specifically ICE or some kind of fluid. Possibly a salt brine ([font=Roboto, arial, sans-serif]The lowest [/font][font=Roboto, arial, sans-serif]freezing point[/font][font=Roboto, arial, sans-serif] obtainable for NaCl [/font][font=Roboto, arial, sans-serif]brine[/font][font=Roboto, arial, sans-serif] is −21.1 °C (−6.0 °F) at 23.3wt% NaCl.)(wikipedia)[/font]

The way to get ice is from the sun directly, bypassing the need for PV panels. I haven't yet looked at the calculations for sizing a system yet but it may be possible and actually easy once it is set up.

My thought is to set up some kind of reservoir of coolant or water and chill that down during the day, then use a heat exchanger to pass the water/coolant through something under the sleeper on the bed. There would be no requirement for any electricity except for some kind of a tiny pump and maybe a temp circuit in case it gets too chilly. The heat transfer would be more efficient due to nearly direct contact. "[font=Roboto, arial, sans-serif]A resting [/font][font=Roboto, arial, sans-serif]human[/font][font=Roboto, arial, sans-serif] male gives off roughly 100-120[/font][font=Roboto, arial, sans-serif]Watts[/font][font=Roboto, arial, sans-serif] of energy" so that is what we would have to overcome[/font]

There is something on the market like what I am talking about but it is a plug in version but it is pretty pricy at about $1000 plus they sell extra cooling units, which is not terribly reassuring.

Thoughts?

 

[Minivanmotoman]

As Artie Johnson would say...
Video from Rowan & Martin's Laugh In.

 

[Trebor English]

The way to get ice is from the sun directly, bypassing the need for PV panels.

Do you mean something like an ammonia absorption system directly heated by a solar collector?

 

[John61CT]

2 pairs flooded Duracell GCs

As much solar as fits on your roof + matching controller

12V DC freezer

----
Homemade icy swampcooler

Polar tubes, two sets rotated between the two, ideally sized to fit just right in both.

____
All first three expensive components which cost much money are multi-purpose.

Last two cheap as chips

Time the swaps for when bank is 80% full, using a lot of "excess free" energy.

 

[Almost There]

In 16 years of full-timing it on the road I have only had a handful of nights where it was too hot to sleep!

Like a heat wave in July in OHio...

And that was when I was stuck in Ohio for the summer, today, I'd move to somewhere cooler if I was faced with a heatwave.

Solutions:

- open all doors and windows during the day to stop heat build up inside, turn off lights before dusk to stop attracting insects.
- stay up later...  
- turn 12V fan on directed at mid point on my body.
- use a wet wash cloth to wipe down naked skin, causing evaporative cooling.
- lay wet wash cloth on body where fan is blowing.
- and finallly, eat ice cream....

For the handful of nights that were a problem, I'd pass on an expensive solution.

 

[lenny flank]

For the handful of nights that were a problem, I'd pass on an expensive solution.

I agree. I spent a month in Vegas when it was 95-105 every day, with no AC. Have also been in Florida when it was 90-95. My solution was (1) don't be in the van during the day--be in an AC somewhere else and go back to the van after dark, and (2) soak a t-shirt in water, wear it, and point a small fan directly at you. Cools you for a couple hours until temp drops enough to be OK. Repeat if necessary. Total cost: zero.

The best solution, of course, is to move where it's cooler.  

 

[Thirsty Boots Nomad]

Depending on layout and energy availability; I also found sleeping by a window, even slightly open, with the fantastic fan in the roof (no matter it's location in the rig) on created enough of a "breeze" to cool me on most nights also.

 

[jimindenver]

The easy version of this is smaller water bottles frozen and rotated in front of a box fan. The fan needs power, so does the freezer which will run a lot and dump heat into the cabin if not placed outside.

 

[jacqueg]

Me too on the wet shirt. Nothing cheaper or easier.

 

[user 37446]

I've been looking up fans for usage in a minivan, theres 3 kinds:

1 - usb powered

2 - 12v ciggie lighter powered

3 - low wattage draw conventional plug in (needs inverter)


I looked up dozens of fans on Amazon and Walmart.com and read reviews till they basically all blurred together.  I did find 3 fans, one of each type above, that were high enough rated (4. something out of 5 stars) and a low enough amperage or wattage draw, and under $20-$30.  You'll want to check your own but an easier way to do it on Amazon is to filter out any items less than 4 stars, then look at the number of reviews and focus on those with several hundred or more. A couple have several thousand, so that's likely more trustworthy.  Then watch videos that some of made and posted on Amazon or YT so you can hear the noise levels.

If all this is too much work, well, buy whatever you want. I do find that there's some commonality - usb devices use very little amperage, like .2 to .3 an hour. Most of these are single speed 4" to 6" size, and a few have 2 speeds. Most are all plastic, a few have metal blades. Look for "brushless" motors. Most are fixed (non-oscillating or swiveling).

The 12V ones draw a more power but then give the motor more to work with, thus can be larger sized, multi-speed and can push more air than the USB.  Several models will oscillate and most adjust up and down.

Obviously the small ac powered ones are, well ac powered however if you need extra volume and have an inverter/decent battery, these work well.
The traditional, cheap, (less than $25) 3 speed box fans most consume 1 amp hour on low, tip over easily, take up a lot of room and are loud. That's probably not the greatest choice for a van dweller.

 

[John61CT]

Using a mains fan via inverter would not be efficient.

You left out the most important type, and a critical issue.

Fans with two leads designed to be wired into your 12V electrical system.

A fan circulating air within the van or pointed at your body, is one thing.

The ones that force your inside air out and drawn fresh air in are another matter, and much more important overall.

Search for Sternwake's posts on ventilation.

 

[Redbearded]

Sorry about the confusion of the first post, my links were edited out due to me not knowing the rules, lol. 

I was thinking about an ammonia absorption system Trebor. I am seeing that maybe I was overthinking the issue... evap cooling seems to be a much simpler solution as long as the humidity is amenable. Plus I keep forgetting the damn things are on wheels... I guess this upcoming mobile lifestyle will take some rethinking of things, lol.

I do like the idea of running cold water tubes under the sheets for cooling, just like using a heated mattress pad for winter makes sense. I just really hate being too hot... Cold I can handle (famous last words...)

 

[jonyjoe303]

at night time its when the swampcooler work the best, even in humid conditions. Actually when its a humid day is the only time I run a swampcooler at night. Less than 2 amps of power you can run it all night long. If anything you will turn the fan speed down when it starts getting too cold.

The only thing with swampcoolers, you have to build your own. I havent seen one they sell that is built for everyday use in a vehicule, you have to drain the water out of them before moving your vehicule otherwise they leak water everywhere.

This is one I built, never have to drain the water when driving around.

 

[Redbearded]

Good to know! How is the water usage on them, and is there an issue with mineral deposit buildup? I only ask because where I'm from the water hardness is kinda rough.

 

[John61CT]

Google "polar tubes", just glue-capped 2" PVC, cut to the right length and filled 85% full with seawater.

I plan to work out clips to hang them from a cooler lid, top of the space.

Rotate between the cooler and a freezer whenever generating excess solar power, or long trips off the Alt, "free energy" storage.

Will likely stay cold 6-8 days in a sealed box, certainly longer than open ice in a "polar cooler", no leaks, no water,more space efficient. . .

 

[Redbearded]

I was thinking about running some thin tubing through the bottom of my fridge with a temp probe at the bed controlling a pump regulating the flow.

I'll look into the polar tubes thing, thanks for the suggestion!