Cooling vest for hot&humid conditions

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thunderstorm80   1 kW

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Cooling vest for hot&humid conditions

Post by thunderstorm80 » Feb 07 2018 7:10am

Hi,
After reading some threads here where different vests were briefly mentioned, I thought it would be effective to start a dedicated thread for it.
The problem with reading about different vests on different websites is that they are based on subjective opinions and the full technical specs are disclosed, so you can't tell if they are really good for your application.
For example, with one company (I already forgat which as it was many months again) they phrase their product for ALL sport conditions, but after long and excruciating Google work, I have found reviews that say that their vests are only good for stationary workers who don't need high-capacity cooling as cyclists or runners.
Since there are so many companies who makes different kind of vest nowadays, it would be much more effective just to ask here for personal reviews of certain products. I trust ES members to give their objective opinion :)

So:
1. I am looking for a solution for humid conditions, so evaporative vests won't work. (and in dry conditions I can just use a wet T-shirts as it's free and available)
2. The vest should be passive, that is, with no external electricity required/pumps/etc.
3. It should have significant cooling-capacity for several hours of hard cycling work in hot&humid weather. I don't mind if it needs to be heavy because of that. I assume that only phase-changing gels (or ice) can have such heat-capacity which can only be achieved thanks to the heat-latency of phase changing materials.
4. It should still allow me to wear a backpack.
5. Less important, but It would be nice if I could "recharge" it in minutes: If it's gel based to soak it in icy water, and if it's ice-based to be able to replace the warmed water with fresh ice.
6. Even less important but that kind of contradicts #3 - if it was slim enough so I could wear it to my work everyday. I am a science teacher and at times we have lessons outdoors. (in the summer - even early mornings are already hot&humid enough so I sweat like an animal :twisted:) Maybe I can buy one thick vest for long exercises, and a slim one for more official duties.

And last - maybe one of you have built something by yourself? I was thinking if I could make a shirt that has several ice pockets in the chest area, but there would need to be a bit of small insulation so your skin isn't exposed directly to zero degrees Celsius. (and a thick insulation towards the externals where the wind blows while you ride)

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amberwolf   100 GW

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Re: Cooling vest for hot&humid conditions

Post by amberwolf » Feb 07 2018 11:51am

If you want it to be passive, yet absorb heat for hours, then to "recharge" it in minutes the temperature differential you'll have to have to pull out all that heat energy will need to be quite large (meaning, placing it within something VERY cold, (well below water's freezing point; perhaps not quite as cold as liquid nitrogen though :lol:) which will need to continuously circulate all over it to quickly remove the heat).

Another issue is the amount of heat-absorption needed vs the mass of the substance used to absorb it. For instance, if you used the water-crystal type gel packs, you'd either have to deep-freeze them before placing them in the vest (or have a freezer capable of holding the entire vest if they're built-in to it), or have multiple times the mass of gel in them vs simply making a smaller mass colder to start with.

To make it last the longest, you'll also have to add a good insulating jacket or vest over the outside of the cooling vest to prevent the heat from the environment soaking into the vest from outside. This will probably make the vest too bulky to be practical, as it will probably be several inches thick in all directions at this point. ;) Plus it will prevent airflow from cooling you at all in those areas, so *only* the ice packs will be doing that.


I've experimented with gel-pack-holding vests/jackets here in Phoenix over the years (especially before I added motors to the bikes, but still do this sometimes during peak heat when it's humid), and as long as you can simply swap out the hot packs with pre-deep-frozen ones (rather than rechilling the vest as-is) at your destination or along the way, then this can work ok, if you're really exerting yourself and getting too hot, especially when it's too humid for simply wetting your clothes down to work. But they won't last nearly as long if you don't have insulation on the outside so that only your body heat is being absorbed, and not environmental heat.

thunderstorm80   1 kW

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Re: Cooling vest for hot&humid conditions

Post by thunderstorm80 » Feb 07 2018 4:41pm

amberwolf wrote:
Feb 07 2018 11:51am
If you want it to be passive, yet absorb heat for hours, then to "recharge" it in minutes the temperature differential you'll have to have to pull out all that heat energy will need to be quite large (meaning, placing it within something VERY cold, (well below water's freezing point; perhaps not quite as cold as liquid nitrogen though :lol:) which will need to continuously circulate all over it to quickly remove the heat).
This is partly true - heat transfer via air convection or conduction with skin are much much slower than conduction with direct cold water. We all know the "shock" when we enter a body of cold water at vs the much milder shock if we entered naked into an industrial fridge with the same air temperature. But I guess they are lying when they are saying you can recharge it in minutes.
And let's say we dump the passive thing - What about a tiny A/C unit which would get it's power from your E-bike's battery? (using a fail-safe connector that will come loose if you fall off the bike while the vest you wear is connected to the battery)
How much a portable A/C unit which can pump 200W of heat would weight? I assume too much, but I have no clue here.
amberwolf wrote:
Feb 07 2018 11:51am
Another issue is the amount of heat-absorption needed vs the mass of the substance used to absorb it. For instance, if you used the water-crystal type gel packs, you'd either have to deep-freeze them before placing them in the vest (or have a freezer capable of holding the entire vest if they're built-in to it), or have multiple times the mass of gel in them vs simply making a smaller mass colder to start with.
Can you give me an order of magnitude, for example for the water-crystal gel packs - how long can they last (and what is the weight of the material more or less) assuming you are insulating the pack from the outside air as well, and with extensive exercise which requires absorbing around 200W-300W of heat from the body?
amberwolf wrote:
Feb 07 2018 11:51am
To make it last the longest, you'll also have to add a good insulating jacket or vest over the outside of the cooling vest to prevent the heat from the environment soaking into the vest from outside. This will probably make the vest too bulky to be practical, as it will probably be several inches thick in all directions at this point. ;) Plus it will prevent airflow from cooling you at all in those areas, so *only* the ice packs will be doing that.
This is a strong debate and I have been thinking about it too - On hot&humid summer day (around 30-32 degrees Celsius), wearing an insulating winter jacket (without any cooling vest) will decrease your heat-conductance path so significantly that you will overheat in minutes. Air-cooling still do a lot even at those temperatures. (think of riding at the speed of a tail-wind at those temperatures)
Having a cooling vest to absorb excess body heat will need first of all to absorb that missing air-convection cooling heat (if you wear an insulation layer), but then again - from the vest's point of view this condition is better since that external air convection "robs" it's "coolness". Did somebody did the math here to see more or less how things weight out? :)
amberwolf wrote:
Feb 07 2018 11:51am
I've experimented with gel-pack-holding vests/jackets here in Phoenix over the years (especially before I added motors to the bikes, but still do this sometimes during peak heat when it's humid), and as long as you can simply swap out the hot packs with pre-deep-frozen ones (rather than rechilling the vest as-is) at your destination or along the way, then this can work ok, if you're really exerting yourself and getting too hot, especially when it's too humid for simply wetting your clothes down to work. But they won't last nearly as long if you don't have insulation on the outside so that only your body heat is being absorbed, and not environmental heat.
Which product would you recommend me to buy? I can only rely on user experiences, as we witness that the official "specs" or "reviews" are subjective. (It can be a non-passive unit if you think that's more effective in my case, as long as I can wear it and have a standard backpack too)

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Re: Cooling vest for hot&humid conditions

Post by Raisedeyebrows » Feb 08 2018 2:11am

I'm suprised no one has come up with a 12v cooler coat that provides actual refrigerated cooling since there are products such as this on the market,

https://www.amazon.com/dp/B01N1WQNYM/re ... il_4?psc=1

Cooler garments with forced air cooling:

http://www.mycoolingstore.com/alphacool-airvest.html

https://www.amazon.com/Octocool-Air-Con ... B01312XKFA
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Re: Cooling vest for hot&humid conditions

Post by thunderstorm80 » Feb 08 2018 4:45am

Raisedeyebrows wrote:
Feb 08 2018 2:11am
I'm suprised no one has come up with a 12v cooler coat that provides actual refrigerated cooling since there are products such as this on the market,

https://www.amazon.com/dp/B01N1WQNYM/re ... il_4?psc=1
Thermocouples are only few percent efficient, so you would need to spend ALOT of power if you want to reach cooling capacity of 200W for exercising cyclist vs the few watts needed to keep small amount of food cold.
I assume you didn't read the beginning of my post.... In hot&humid conditions, even riding into a strong front wind and with the best cycling clothes is too hot. The only thing that can work is either passive cooling of pre-cooled phase changing water-ice/gel, or A/C unit.
I know soldiers in tanks wear body A/C units, and even though they are quite heavy it's ok since they don't move much inside. I am assuming that some progress has been made since then towards outdoor workers, or anyone who suffers from the slowly but steady increasing summer temperatures due to global warming.
The film scene of people wearing suits to survive in extreme heat (in one star-trek genre series) is soon becoming a reality. Sadly :cry:

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Re: Cooling vest for hot&humid conditions

Post by dogman dan » Feb 08 2018 7:36am

You can get one thing for your needs, the vest with the popsicles inside. Actual popsicles can work, the kind in a tube you can suck on when they melt. You can sew your own vest of pockets.

But the gel pack vest will work better. Something like this. http://www.stacoolvest.com/stacool-unde ... gK2qPD_BwE

I have actually used them, and yes, they do work better if you are just standing or sitting around in 120f, vs riding hard making body heat. But they still do work better than evap when its humid. You don't wear a coat over it, unless its for a reason, like motorcycle armor. Skin, cold vest, then a t shirt or whatever.

Recharge in minutes? easy, once you are home. just swap out the popsicles for fresh frozen ones. One set is good for at least two hours. Once thawed, take it off.

Anything longer than that, you will just have to suffer.

Raisedeyebrows   1 kW

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Re: Cooling vest for hot&humid conditions

Post by Raisedeyebrows » Feb 08 2018 11:28am

thunderstorm80 wrote:
Feb 08 2018 4:45am
Raisedeyebrows wrote:
Feb 08 2018 2:11am
I'm suprised no one has come up with a 12v cooler coat that provides actual refrigerated cooling since there are products such as this on the market,

https://www.amazon.com/dp/B01N1WQNYM/re ... il_4?psc=1
Thermocouples are only few percent efficient, so you would need to spend ALOT of power if you want to reach cooling capacity of 200W for exercising cyclist vs the few watts needed to keep small amount of food cold.
I assume you didn't read the beginning of my post.... In hot&humid conditions, even riding into a strong front wind and with the best cycling clothes is too hot. The only thing that can work is either passive cooling of pre-cooled phase changing water-ice/gel, or A/C unit.
I know soldiers in tanks wear body A/C units, and even though they are quite heavy it's ok since they don't move much inside. I am assuming that some progress has been made since then towards outdoor workers, or anyone who suffers from the slowly but steady increasing summer temperatures due to global warming.
The film scene of people wearing suits to survive in extreme heat (in one star-trek genre series) is soon becoming a reality. Sadly :cry:

Well you might want to calculate the amount of juice it's going to take you to power thermocouples needed to cool you because it sounds like that's what you are after (after reading your parameters you desire). How about carrying enough batteries in a trailer to achieve your needs?
Yuba Mundo w/BBSHD
Specialized Hard Rock w/9c clone, statoraid, hubsink
Trek Fuel 90 w/BBSHD
Above all run on 14s4p 52v li-ion
Ecobike folder 36v
Currie Flyer scooter 24v on 24ah of SLA

Every trip made with electric bike is one less car trip, saves money, no toxic fumes, less noise, less impact on roads.

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