Liquid Cooling Vest

Project maintained by frozenpoint Hosted on GitHub Pages — Theme by mattgraham
Liquid Cooling Vest


Background

This project spawned from a problem i have (well, a lot of problems). Notably:

  • I live in Florida (a wretched humid swamp filled with sadness and alligators)
  • I'm a really sweaty guy (show me a picture of sunshine and I'll soak my shirt through)
  • I ride a motorcycle and wear full gear (most of which is leather) year round

This typically means I'm hot, sweaty and disgusting whenever I go anyplace on my bike. To a degree, I've learned to live with this. However, it isn't something that you can every really get used to. The vast majority of people don't wear much gear around here because of the heat. I'd rather sweat than bleed so that's what I do...a lot.
I've tried towels that have a ton of surface area that cool off if you wave them around. These work great in places that aren't Florida since they rely on evaporative cooling. However, the apocalyptic levels of humidity here negate any evaporative cooling and make it so these just get you wet in addition to being hot.
I've contemplated textile/mesh gear but they don't protect as well as leather and it won't matter at a stop light where my engine fans blast me with with hot air with the sun blasts me from the top and the asphalt bakes me from the bottom.
Until now, I have just suffered through on my bike and made most of my traffic decisions based on whether I keep moving or have to wait at a light. However, I recently read a book that made me think about a better way (as an aside, the book was Seveneves by Neal Stephenson). In the book, the author waxes lyrical about the Orlan space suit, specifically it's cooling undergarment that removes the wearer's body heat and sinks it into space by circulating a coolant through a series of small flexible tubes. Since roughly 25 times more effective at stealing your body heat by conduction that air, space agencies use it to remove body heat the most effective way possible from astronauts.
I thought it'd be a cool idea to circulate cold water the same way in my motorcycle jacket. So, I did a little research to see if anyone had this idea already and surely enough, there are commercial products based on the same concept.
I'm certainly not creating anything new or revolutionary. I would have simply purchased one and saved myself the effort if they weren't asking $998 USD for a comparable product to the one I put together in a few weeks over nights and weekends. This project is definitely not meant to compete with commercial products, I'm simply sharing my code, parts and ideas in case anyone else want's to build something similar.
Layout

The complete unit is comprised of two major components: the vest and the "backpack."
The vest has 4 cooling circuits (small tubes), a manifold connector for those circuits and a waterproof temperature sensor on one of the return circuit lines to monitor the water temperature of the vest.
The backpack is a modified hydration backpack where the normal drinking line goes to a self priming diaphragm pump and which pushes ice-water through the vest.
I 3D printed all the fittings and parts from ABS plastic and have included the STL files as well as original Solidworks 2013 parts/assemblies in the repository with my controller firmware so others can modify and/or print them as well.
If you don't have a 3D printer, don't give up. Most of what I made can be created with epoxy and a drill or fittings from the hardware store. Nothing here is essential to be 3D printed, it's just what I have available and works for me.
Vest


The vest is very nearly a stock hunting/sport mesh vest. The one I used is linked in the Parts List section below. The make/model really doesn't matter that much. Mesh is good since it's lightweight and fits under a motorcycle jacket.
The important part of the vest is really the tubes. I used 2 25ft packs of silicone aquarium air line tubing. I cut each 25ft length in half and sewed it in the 4 quadrants of the vest. I kept each circuit the same length, even though some have to travel further away from the vest entry point at the left rear bottom to keep the flow resistance as equal as possible so I didn't end up with a "lazy" circuit.
I started each circuit at the same place on the vest with both ends sticking out so I was really was just sewing a long twisted loop onto the vest.
On one of the circuits, I also sewed a DS18B20 waterproof temperature sensor to the return end of the tube to measure the water temperature in the line after my body had heated it up. The sensor is sewed in place, taped with pipe insulation tape and sewed over with black fabric to keep the tape in place and provide an abrasion shield from any rubbing my the wearer or the outer jacket. The insulation tape is so it is measuring the tube rather than my jacket or skin temperature (mostly). The temperature sensor terminates in a MTA156 male 2-pin connector glued to the umbilical manifold connector (described below).
The Umbilical (Vest Side)

To allow disconnecting the vest from the rest of the unit, the umbilical connector is a two piece unit with a locking pin (in my case, just a sanded stainless #6 machine screw).
Here is a picture of the manifold side of the connector:
The cut-out is where the male MTA connector is glued for the 1-Wire bus that hosts the vest temperature sensor. The part of the far right of the picture is a strain relief and clamp for the cooling tubes that slides over the 8 hose barbs (with tubes on) to prevent accidentally breaking off one of the barbs (they're 3D printed ABS which, at this size is fairly fragile). This strain relief is held in place by friction (the tubes are pretty squishy).
The umbillical parts (well, the bits that see water) are sealed by acetone smoothing to make them waterproof and printed with 100% infill to make them as waterproof as possible before the smoothing).