First time hearing the term micro bakery. Is there an equivalent for restaurants? Like a micro restaurant? Seems like a fun idea for my retired parents.
As a MechE turned SWE, always a fun read when SWE try hardware.
> Blink and you’ll get a different measurement.
This means your environment is not controlled enough. Also quality control is usually done in terms of statistics. You might want to read something called gauge R&R. That being said, you should be proud of being able to ship a physical product!
As for quality checks, software quality teams pales in comparison to hardware quality teams. Mainly as you said, there’s a lot checks you can do in software. For hardware, bigger companies have to have their vendors qualified. The vendors have to follow their customer guidelines and do outgoing inspection. Then the company has a division to do incoming inspection. There’s a traveler that follows the kit (of parts) and there’s usually subassembly quality checks. Then final full build checks before it leaves the door.
> terms of statistics. You might want to read something called gauge R&R
I think the first thing to focus on is the stats portion - do you have appropriate FAI/SPC/OQC with Cpk requirements defined? Gauge R&R plays a much smaller role, especially in something that is relative
A heat pump gets more heat from a given amount of electricity than if the electricity is use for resistive heating. So the ideal design is solar cell + sodium battery + heat pump.
Also when the temperature differential is lower, so ideal might be solar -> battery (to time shift to warmest outdoor temperature) -> heat pump -> thermal battery (to time shift to when you need heat).
Does seem like a lot of added complexity (and likely machinery cost) though.
The question is would it cost less over the long term than any other solution. My intuition is it would, at least for a lot of use cases, but it would need to be put into practice and studied to see if this is actually true.
I live in Switzerland where these are available. A Cowa 58 [0] costs CHF 4692 [1] and stores up to 13.5kWh. If you're heating the water with a heat pump, that's ~6kWh of electricity, so ~CHF 782/kWh.
I'm in the process of installing a 33kWh battery and the battery + inverter cost CHF 13600 in total for just the hardware, so ~CHF 482/kWh.
If you add solar panels, the inverter does double-duty producing AC from both the battery and the panels. The battery does double-duty producing both hot water and allowing you to use solar energy outside the times when the sun is shining.
That said, having ordered a heat pump recently and being in the process of having solar + batteries installed, the amount of electrical work needed for the solar/battery install is substantially higher than was needed for the heat pump and here, the labour costs quite a lot, pushing the upfront cost difference even higher.
I think that's where these heat storage things fit in: they have a much lower upfront cost. No matter how cheap the battery, for it to be useful in a Swiss residence, it needs to output a substantial amount of 3-phase power (3-phase is standard here, even in most apartments), which means you need to spend a couple thousand Francs on an inverter and electrical work. These heat storage devices are quite cheap and don't even need someone qualified to handle refrigerants, I imagine they could be installed by a normal plumber.
That reduced upfront cost makes them far more accessible than electrical batteries, at least for now.
Climates that need a hot tank of water to buffer for heat pumps, will not have meaningful solar panel output during winter. Or do you mean, just load the battery when electricity is cheap? A tank of water is 1k max, probably 10% of a sodium battery.
There’s also solar thermal panels that heat up a liquid circulating in the system and cut out the need for a battery - and can just store the heated liquid.
Efficiencies and effects are at the point where taking a photon, converting it into an electron, and using that electron to pump heat is more efficient than turning that photon perfectly into kinetic energy.
Similarly, in mild weather, it is more efficient to burn hydrocarbons and turn it into electricity to run a heat pump than use that hydrocarbon for it's heat energy directly.
Thermal solar panels have the advantage of being very simple and surprisingly effective. But if you're lacking space to put up both solar cells and thermal, you can use combined panels which have a solar cell with a backing thermal system. The interesting thing is that these combined panels outperform solar cells even when it comes to electricity generated because solar panels loose efficiency as they heat up, so cooling them actually improves efficieny. Combined panels are much more expensive, though.
The problem with thermal solar panels is that you can use its heated water only if it gets warmer than the water in your system, which is not always the case, especially in winter.
Compared to nearly 100% usable energy from normal solar panels.
Furthermore if you have a heatpump you can convert this electric energy into heat energy with a factor of >3 (COP).
Yeah but if you're in a northern climate your solar panels are only generating like 10% of their summer capacity in the winter anyway due to sun hours/angles... winter is just tough for capturing solar energy in general.
So…geothermal? I wish this was possible too but I don’t see how it will work scientifically. Water is one of the chemicals that have one of the highest thermal mass/specific heat (maybe 1/3 of salt hydrates). Even then, you have to bury a crapton of water underground. This design mentioned in the article is more for short term, like 12 hours storage (since they’re accommodating for solar in nighttime)
Geothermal needs either a horrifically expensive vertical bore hole going down a few hundred metres, or a good acre of land for laid-down piping. I have neither the money nor the horizontal space. So I am thinking something compact that needs to go only about 6-10m vertically into the ground (so I can hide it fully underground with about a metre of soil on top), and take up the horizontal space of 4 parked cars. I have more than enough room and cash to have that cube of space dug out.
And being on an alluvial plain, if I filter out all the rocks larger than a pea, a good 90+% of what is dug out can immediately be trucked away.
Is geothermal not the opposite of that? My understanding was that the geothermal MO is that there's virtually infinite thermal mass in the earth so it won't heat/cool, not that you heat/cool your local chunk
To a certain extent, yes. The reason why the water is there is because the thermal flux of the ground is low, so the large mass of water provides a strong buffer. But you can’t cheap physics. You would need a crap ton of salt hydrate to accommodate a whole season of heat needs, even if you don’t factor in thermal loss from the container.
Unfortunately it’ll be a lot harder for CAD because of all of the other lock in like PLM/ERP integration. A good PLM is half the product. I know a good amount of companies that do not use solidworks because their PLM is absolutely crappy (but I haven’t been a MechE for a couple years now so things could have changed)
True, but PLM is an area where the bar for UX is very low indeed. I think the main barrier to an OSS one is the will to make one and the large list of checkbox features they're often selected by.
It’s actually really easy to use mitmproxy as a…proxy. You set it up as a SOCKS proxy (or whatever) and point your network or browser to the proxy. I did this recently when a python tool was too aggressive on crawling the web and the server would reject me. Forced my session to limit 5 requests per second and it worked rather than finding the exact file to change in the library. Just do the same to your browser and then turn on the capture mode and you’ll see the requests
Actually intercepting the cleartext data is less trivial (not inherently - the browsers just make it more obscure than it could be) but it can be done.
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