The video here shows a lot more about the fridge and a little about the cooler:
1. The whole cooler is heated, the pressure throughout rises, and the liquid water surrounding the inner chamber evaporates.
2. The water vapor moves into the (presumably much larger) other chambers, distributing itself equally.
3. The inner chamber is sealed while the others are opened to atmosphere. The device returns to normal pressure and that cooling drops the inner chamber pressure well below atmospheric.
4. Liquid water which has now re-condensed in the other chambers is allowed into the inner chamber in a controlled manner, evaporating due to the pressure and cooling the chamber.
To be clear, the inner chamber in my understanding would be a thin shell around the actual payload compartment. The vaccines or what have you obviously don't get wet and don't get exposed to low pressure.
I suspect "water" is some other working fluid in the sealed system, ah maybe ammonia-water mentioned below:
> The conditions in Vanuatu make vaccine distribution a tough challenge. Today, shipments are flown from the three major islands (which have cities and airports and such) to small rural islands in 9-seater planes. When a plane rolls to a stop on the grass airstrip, it’s met by someone from the local health clinic—but that’s assuming that one of the few trucks on the island is available and in working order.
The health worker picks up the vaccines, which are packed in ice, and hurries back to the clinic to stash the precious vials in a refrigerator—but that’s assuming the fridge and the clinic’s solar power system are working. Any breakdown is a serious problem, because spare parts can take weeks to arrive. And the whole operation is very expensive.
Vanuatu's residents are looking into skipping the remote refrigerators and transporting vaccines by drone. An ideal solution seems to be a combination of both, giving flexibility in both transport and storage. How much do these weigh - could they be transported by drone easily?
This is ideal because you don't need a heavy, expensive refrigeration unit to keep vaccines cool for days of travel, thus decreasing the cost and expense of vaccination.
Obviously this won't work everywhere; extreme weather, like storms or even high winds, may make drone delivery impossible for much of the year. But it appears that the more we can deliver vaccines by drone, the better.
The technology I'm referring to (a ramjet) is unfortunately not too efficient, but the low-tech nature of it, at least as far as manufacture is concerned (design benefits greatly from modern computational fluid dynamics), makes the manufacturing cost of it, including a fuel tank, come in at about 10-100$. It's basically a fancy shaped pipe with something like a fuel pipe or so coiled around it (for cooling and to ensure sufficient temperature of the fuel), which can just be hydroformed from a seamless section of stainless steel pipe. They guzzle fuel, but as long as you either have an electronic valve a microcontroller can adapt to e.g. a simple flow meter or pressure sensor, along with a temperature probe, they only need the fuel to contain enough butane/propane or so to self-pressurize, and otherwise require the fuel to not tar/char/soot up any of the fuel nozzles and such.
Theoretically, though one might prefer to run it on liquid hydrogen in that case, the same technology, but with different tuning could run a similarly rather cheap Mach 2~3 (at surface level) reaching thing light enough to be lifted by a pair of movers or similarly build men. That would be hard to do without going for the hydrogen, and that is unlikely to be prevalent on a small pacific island.
Both of these potential things do fall under the category "Your scientists were so preoccupied with whether or not they could they didn't stop to think if they should.", the latter even under the category "ITAR want's to have a word with what you made there.", due to the necessary automatic navigation and speed, as well as technological level of materials used, as high-tech airframes are expensive.
The LH2 ramjet could probably be made to launch from a <100m long catapult, I once did a few calculations and UHMWPE fibers should allow accelerating within iirc. 50m to Mach 0.7 with something like a large (half-ton, due to the energy density) steel coil spring (like in a watch, just a "little" larger) at the muzzle and that coiling up the rope pulling an iirc. 100 kg aircraft with a sled or so, due to the ramjet not delivering enough thrust at lower speeds. The side effect would be that because they gain thrust with speed (up to a point, for the LH2 constellation somewhere over Mach 3), there would be plenty of thrust to spare, and combined with the high structural strength necessary for the catapult, and the lack of vertebrae on board, turns up to about 30~50 G are feasible, all at near ground level.
While there is certainly an appeal to this, and the technology being sufficiently low-tech for a home shop (I am just going to refer to Sam Zeloof's garage wafer fab), any attempts at building something like it as a large hobby project would be futile for there being no way to test it outside of a remote desert area or the ocean, both rather inhospitable to a one-man flight crew. There are reasons supersonic aircraft are not tested over inhabitation. It would not be nice to a street it could technically fly through, unless the buildings are already blast proof.
And a hobby project of that scale you can't even play with will not be worth it.
(If you happen to know how to play with something like this despite the supersonic-over-land ban, please divulge your secret.)
I think it doesn't matter a great deal, the value of vaccination is so high that each cooler can cost quite a bit and have a bunch of entities (governments, non profits, etc) happy to pay for it.
Also, I'm just impressed with Bill Gates. Here is a man who had everything and and decided to do as much good as possible with it.
In sub-saharan africa it's mostly logistics, in western countries it's cultural (anti-vaxxers), in some other countries it's political e.g. fear of western interventionism and harm under guise of humanitarianism… sadly justified: the CIA organised fake vaccination campaigns in Pakistan to pinpoint OBL, and while officially that program was shut down who'd trust these claims?
"In its zeal to identify bin Laden or his family, the CIA used a sham hepatitis B vaccination project to collect DNA in the neighborhood where he was hiding."
"The deadly consequences have already begun. Villagers along the Pakistan-Afghanistan border chased off legitimate vaccine workers, accusing them of being spies. Taliban commanders banned polio vaccinations in parts of Pakistan, specifically citing the bin Laden ruse as justification. Then, last December, nine vaccine workers were murdered in Pakistan, eventually prompting the United Nations to withdraw its vaccination teams. Two months later gunmen killed 10 polio workers in Nigeria—a sign that the violence against vaccinators may be spreading."
Who are the specific people that came up with this idea, pitched it, agreed to it, and executed it?
Names are needed.
Vaccines need to be kept at 2C-8C before they are used to be effective. This is a problem in Africa because power can be inconsistent and villages are remote. Two improvements have been developed.
MetaFridge is a new fridge that can keep vaccines cool for up to five days without power. It can also display how long the vaccines are still god for and transmit data to a service team if needed.
Indigo is a new type of cooler that can be carried on your back. It works by heating it up which puts water into a high pressure compartment. This is sealed by a valve. Once the valve is flipped, the Indigo can keep the vaccines cool for up to 5 days with no ice or power.
MetaFridge is in the field with a solar power option in the works. Indigo is in field trials with results suggesting 4x as many places can be reached.
You can ship t-shirts and plastic chairs from western countries and make yousrelf feel good because you're "helping". But what about solving the real problems like infrastructure? The west invested in infrastructure in china. Now china is investing in africa.
Do you have any evidence that this is true? As far as I can tell, China invested in infrastructure in China. "West" just buys products. Your statement is equivalent to claiming that Apple invested in infrastructure in China when the reality is that Foxconn invested in infrastructure in China and Apple just buys the output.
There ain't much cause for counterfeiting though, vaccines are cheap to produce, widely available and annoying to conserve, there's little incentive to counterfeit them or sit on a batch of vaccine waiting for the prices to rise to fence it.