Heat Exchanger For (Ant)arctic Explorers

Cold weather is hostile, to most humans at least, although some peoples have adapted well to extreme environments. In the US, there are people living far north of the arctic circle where even the most enthusiastic of pizza menu delivery people dare not tread. Nevertheless, there are still environments too extreme for all but the most intrepid/daft humans. The depths of the Antarctic continent have punishing low temperatures, extreme winds, high altitudes, and formidable physical barriers. As such, people who find themselves there, tend to hunker down in research stations and apparently, drink an awful lot through the winter. Nevertheless, there are people who dream of the last remaining feats of exploration.

One such feat is a solo, unsupported transantarctic trek*. This is particularly tricky. Since the antarctic is big, cold, high and undulating, you need quite a lot of equipment. Significant clothing for insulation, additional sturdy tents and super thick sleeping bags, again for insulation. Fuel, to melt water and cook food and then the actual food. Lots of food. This is the only real energy source for the person doing all the moving and staying warm. This all has to be hauled along, usually on a sled. This is where the compromises creep in. You can take less stuff, and move faster, but should you be stuck in a storm you may run out of resources waiting and be unable to complete the trek. Or, you can take a lot, and move slower, sapping morale and increasing the likelihood of encountering a storm.

The energy needed to move is pretty invariant, humans tend to be similarly efficient. What remains is the fuel for cooking/water and the energy required to keep warm. Now, people with more motivation than brains have discovered that a diet high in fat** gets you a lot of dense calories, minimizing the excess weight, but we can do better.

There's quite a lot of research on how much heat people lose in cold environments, a reasonable example <link> suggests that at -40C up to 20% of working and 30% of resting metabolism is expelled with normal breathing. That is a large amount. And -40C is child's play compared to the temperatures and wind chill that a modest 5 day antarctic storm can dish out.

So, we solve it. Breathing in cold air, heating it up and humidifying it in the lungs and then breathing it out to the antarctic environment is a stupid waste of energy. So, lets breath through a heat exchanger. This can be a super simple device. Essentially a mouthpiece, a pair of counter current- arrangement tubes and a little flappy valve or two. The best arrangement will be a central tube with a spiral arrangement around the outside. Breath in through one, out through the other with the valve ensuring unidirectional flow. The system should have a couple of lungfuls of dead volume, this gives the air a few seconds to dwell and exchange temperature. Now, the air you breath out will warm the air coming in. You save an awful lot of heat.

The by product is a bit of condensed water, this should be collected and may be drunk at (slightly disgusting) leisure.

Now, there is prior art <link> but this is just some "media" read "stuff" that gets warmed during exhale and cooled during inhale. Similar principle but nowhere near as efficient as a proper heat exchanger. If they wanted to do a better job, the "media" should be thin tubes containing a eutectic substance at an appropriate temperature, although that would be difficult to get exactly right depending upon conditions.

* When that's been conquered, it will be a solo unsupported trek over the long axis, then in winter... until there are no people left who will sponsor such increasingly tenuous connections to unique achievement.

** fancy pants explorers with their fussy requirement for a separate fuel from their stove. Swap in the winter mix of my single battlefield fuel for extra efficiency.