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less moving parts means it could work in contexts where moving parts demand lubrication, maintenance.

I felt it was a bit light on putting the system energy efficiency/losses up front. I am sure they're stated but it was hard to work out how it compared to normal PV efficiency, or steam turbine efficiency.

Heat exchangers are applicable to lots of things. I am skeptical that this is significant because almost any heat energy process does reclaim and preheat, and so the size of the thermal mass and efficiency here would be exceptionally well studied and if they have made improvements, they may be as, or more valuable as IPR overall. So while it looks amazing, unless they are spinning it out into wider industry it will be a small increment over things in deployment.

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enragedcacti 8 hours ago | parent | next [-]

I don't think they are claiming an efficiency breakthrough on their heat exchanger, just that they've made a competitive heat exchanger that also blocks light very effectively.

	▲	ggm 3 hours ago \| parent \| next [-]
		In context, an important innovation. Perhaps this technology can retrofit into hot gas heat exchangers like in steel works, but they use the thermal energy directly so it may be robbing Peter to pay Paul. Thanks for a clarification which makes sense.
	▲	DaniFong 2 hours ago \| parent \| prev [-]
		we're not aiming to break records with the absolute heat exchanger efficiency, which can get into the high 90s (%) if you're willing to devote a lot of space and mass, but we are innovating in the heat exchanger area. to capture more of the waste heat up to a higher temperature, and preheat the incoming air and possible fuel to a higher temperature, we have to exceed 1000 C and want to drive towards the 1600-1800C maximum working temperature of the high alumina 3d printed material we're using. Thankfully Formlabs has already done some of the preliminary development on the material, but it's bleeding edge both as a material and in use in heat exchangers.

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skykooler 4 hours ago | parent | prev | next [-]

I suspect this needs some moving parts to function - without a turbine's suction, you need some sort of a fan to pump air into the thing, and also a fuel pump. Most things with internal combustion require some kind of active cooling as well.

	▲	DaniFong 2 hours ago \| parent \| next [-]
		you need at least valves/regulators, but for self pressurized fuels like propane, butane, or even natural gas (CNG or LNG) you can probably get away with only that, and fans for air intake and cell cooling.
	▲	cryptonector 4 hours ago \| parent \| prev [-]
		If using compressed natural gas you might not need a fuel pump at all.

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detourdog 9 hours ago | parent | prev [-]

I read their statement of 40% efficiency would be compared to the currently available photovoltaics were generally 20% efficiency is normal.

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enragedcacti 7 hours ago | parent [-]

the 40% efficiency is a claim about how much energy contained in the fuel can be converted into electricity*. It would make the most sense to compare this against either combustion engines or hydrogen fuel cells. Compared to those 40% is not breaking any records but could be extremely useful given the size, flexibility, weight, power output, etc.

Basically big if true, but this thing's 40% and photovoltaics' 20% aren't comparable efficiency numbers.

* They say wire to wire, IDK exactly what that means, but if it includes the losses from green hydrogen production then it seems like pretty wild efficiency. This doesn't line up with the numbers though, as H2 with 1250Wh/L * 0.4 = 500 Wh/L claimed density.

	▲	cryptonector 4 hours ago \| parent [-]
		I agree that 40% "wire-to-wire" seems wild. But if it was 40% nat gas to wire that'd be quite nice considering how simple such a generator would be, and it might be more efficient (perhaps significantly more) than traditional internal combustion generators. I.e., if you ignore the green aspects of this it sounds quite nice. Though you have to supply sodium. Hmmm.