Viewer Challenge - Water cooled Blanket

That's a really cool idea (pun intended). I think the biggest hurdle in a project like that would probably be the hose. Rubber or plastic doesn't conduct heat well enough and metal tubing is inflexible. It probably wouldn't be very comfortable either. You'd also need a material that could withstand the pressure of body weight without obstructing water flow, this most likely would require thicker walls which would compound the issue. Perhaps a sleeping mat instead of a blanket? Using a foam mat (like a yoga mat or a camping sleeping pad) for a base you could use metal tubing with multiple S bends to maximize surface area (think something like a higher frequency sine wave) embedding it in the foam so it's flush. Use metal tape to cover the top of the mat, it's somewhat flexible and will help conduct your body heat into the tubing. Box on the ground could contain the peltiers, the pump, an arduino with a thermistor for heat control, LCD for display, and some buttons for temperature control. Plastic flex tubing links the mat and the box. Peltiers can be set up in a hexagonal pattern cold side out hot side in, use CPU heatsinks inside the hexagon for heat transfer and 2 200mm case fans to provide air flow through the sinks. Metal tubing in a tight wrap can be wound around the outside of the peltiers for heat transfer to be connected to the plastic flex tubing and the pump. Toggle switch to provide switching from cooling to heating. This design still wouldn't be very flexible but you could cut the mat into 6 inch sections and use flex tubing to connect each section together, keeping the S bends to ~4 inches peak to peak, 550 paracord running through all the sections on the left, right and center could help hold it all together, providing increased flexibility and easier storage.

Anyone else have any thoughts?

*To make bends in metal tubing without kinks fill the tubes with a fine grit sand before bending. Your best option for metal tubing would probably be aluminium, copper gives better heat transfer and is more durable but aluminum is cheaper, although if you go with aluminum you'd need to go with an inhibited glycol or dielectric fluid over water. I'd probably go with propylene glycol and water (PGW) as a heat transfer liquid for this application. Your other option is stainless steel, in which case I'd go with deionized water as a heat transfer liquid. Whatever you do don't use tap water! It may be cheap but the impurities can clog your pipe.

I was thinking about the same thing as you described: cpu water blocks with the peltiers to chill the water and heat sinks on the other side of the peltiers with fans to disperce the heat. The arduino idea is great, but if you dont want to get too fancy i guess you could just use a potentiometer to regulate the power going to the peltiers.

As for the tubeing. I dont believe metal tubing will be very comfortable to lay on. Maybe some kind of padding/foam between the "S's" of the plastic tubeing? 

colecago - I understand your logic but would like to make this out of parts readily availible - and some elbow grease! What you said about the multiple pathways is interesting though. Maybe make tube junctions at various points in the mat? Would that affect circulation?

Peltier coolers are a very poor choice for this kind of device. There is a reason that real fridges don't use them - they are inefficient and expensive. I suspect that if water is readily available then an evaporative cooler would be the cheapest solution - you need a pump for the water and a fan to work the evaporative cooler.

If you are in reasonable health by far the cheapest way to keep cool is to use the one built into your body - drink the water and use a fan to blow air over you.

The evaporative cooler uses the same principle but a machine to deal with the water. The biggest pitfall with such machines is preventing the water from becoming contaminated.

MK

pshlos wrote:

 

I was thinking about the same thing as you described: cpu water blocks with the peltiers to chill the water and heat sinks on the other side of the peltiers with fans to disperce the heat. The arduino idea is great, but if you dont want to get too fancy i guess you could just use a potentiometer to regulate the power going to the peltiers.

As for the tubeing. I dont believe metal tubing will be very comfortable to lay on. Maybe some kind of padding/foam between the "S's" of the plastic tubeing? 

 

colecago - I understand your logic but would like to make this out of parts readily availible - and some elbow grease! What you said about the multiple pathways is interesting though. Maybe make tube junctions at various points in the mat? Would that affect circulation?

I don't know, I was kind of envisioning something like air mattresses do, maybe a bit more control though.  As for plastics, I had envisioned something soft like like that crappy wrap they put on wire harnesses in vehicles.  That should be pliable enough for a blanket.  I agree it's not out of something available.  But hey, I'm sure a window mounted AC unit would be cheaper and easier than anything we come up with.

pshlos wrote:

 

I was thinking about the same thing as you described: cpu water blocks with the peltiers to chill the water and heat sinks on the other side of the peltiers with fans to disperce the heat. The arduino idea is great, but if you dont want to get too fancy i guess you could just use a potentiometer to regulate the power going to the peltiers.

As for the tubeing. I dont believe metal tubing will be very comfortable to lay on. Maybe some kind of padding/foam between the "S's" of the plastic tubeing? 

 

colecago - I understand your logic but would like to make this out of parts readily availible - and some elbow grease! What you said about the multiple pathways is interesting though. Maybe make tube junctions at various points in the mat? Would that affect circulation?

I don't know, I was kind of envisioning something like air mattresses do, maybe a bit more control though.  As for plastics, I had envisioned something soft like like that crappy wrap they put on wire harnesses in vehicles.  That should be pliable enough for a blanket.  I agree it's not out of something available.  But hey, I'm sure a window mounted AC unit would be cheaper and easier than anything we come up with.

  But hey, I'm sure a window mounted AC unit would be cheaper and easier than anything we come up with.

This thing would be quite portable - sorta - kinda. I guess you can roll up the end result and throw it in the car when going on vacation.

idk if i can keep it under $100.  roll it up and put it in the cooler