from the washin'-dishes-and-baby-clothes dept.
Washing Dishes with Superheated Steam More Effective, Earth-Friendly:
Conventional dishwashers often do not kill all the harmful microorganisms left on plates, bowls, and cutlery. They also require long cycle times that use large quantities of electricity, and the soap pumped in and out is released into water sources, polluting the environment.
Superheated steam dishwashers could provide a more effective, environmentally friendly solution. In Physics of Fluids, by AIP Publishing, researchers from the Technical University of Dortmund and the Technical University of Munich simulated such a dishwasher, finding that it killed 99% of bacteria on a plate in just 25 seconds.
[...] "Steam comes out of the nozzle at a very high velocity. We can see shocks, and the turbulent flow that is created has eddies and vortices," said author Natalie Germann, of the Technical University of Dortmund. "We also include heat transfer, which shows how the heat changes in the simulation box and the condensation on the solid surfaces."
[...] The superheated steam dishwasher would initially cost more but would pay off in the long run with savings on water, electricity, and detergent. It would be ideal for use in restaurants, hotels, and hospitals, which must meet high hygienic standards.
"We confirmed that the dishwasher application using superheated steam is promising," said Germann. "This is the first work combining fluid dynamics and heat transfer with phase change and bacterial inactivation. It thus lays the foundation for future computational research and further technical work."
Journal Reference:
L. Abu-Farah and N. Germann. Simulations of thermal phase changes and bacterial inactivation in a superheated steam dishwasher [open], Phys Fluids, 2022. DOI: 10.1063/5.0090418
(Score: 4, Insightful) by Runaway1956 on Wednesday September 07 2022, @10:36AM (6 children)
Dishwashers of various designs have worked pretty well for killing germs and bacteria for a long time. Some work better than others, but they are mostly pretty good at killing pathogens. Dishwashers don't work especially well at removing food, especially egg residue from breakfast. That heat tends to cook the egg residue onto the material, rather than removing it. Superheated steam? Hmmmm . . . I'll bet such a dishwasher would work really well at burning inattentive people who snap the door open and reach inside.
I think I'll stick to very hot water, thank you very much. Or, at least wait until the dishwasher people have come up with idiot proof safety interlocks. Good luck with that!!
Abortion is the number one killed of children in the United States.
(Score: 3, Insightful) by Anartech Systems on Wednesday September 07 2022, @12:04PM (3 children)
My washing machine physically prevents me from opening the lid during its spin cycle with a solenoid that latches the lid shut. I'm sure a similar hard mechanical lock could be used to hold the cavity closed until the inner temperature reduces to a reasonable temperature.
(Score: 2) by deimtee on Wednesday September 07 2022, @01:50PM (2 children)
Pretty much any front loader washing machine locks the door as soon as you push the start button and won't unlock until it's finished.
No problem is insoluble, but at Ksp = 2.943×10−25 Mercury Sulphide comes close.
(Score: 2) by Mykl on Thursday September 08 2022, @03:26AM (1 child)
Our Miele dishwasher (3 years old) will quite happily let you open the front door while it's mid-wash and spray water everywhere.
(Score: 2) by deimtee on Thursday September 08 2022, @05:40AM
Dishwashers, yes. The ggp was referring to some clothes washers locking the lid during spin cycles. I was just pointing out that all front-loading clothes washers lock the door.
No problem is insoluble, but at Ksp = 2.943×10−25 Mercury Sulphide comes close.
(Score: 2) by MostCynical on Wednesday September 07 2022, @12:22PM
Your dishwasher will just bake on any left-over food, so every time you wash them, you will get new patterns!
"I guess once you start doubting, there's no end to it." -Batou, Ghost in the Shell: Stand Alone Complex
(Score: 3, Interesting) by JoeMerchant on Wednesday September 07 2022, @02:39PM
>I'll bet such a dishwasher would work really well at burning inattentive people who snap the door open and reach inside.
Not just burning, very hot water already does that, no: superheated steam will strip the skin off your face. Source: dad got hit with a burst of superheated steam in the cheek area: 9 months' recovery time, but: skin looked 10 years younger after it grew back (only because it was!)
Україна досі не є частиною Росії Слава Україні🌻 https://news.stanford.edu/2023/02/17/will-russia-ukraine-war-end
(Score: 2, Insightful) by Anartech Systems on Wednesday September 07 2022, @12:01PM (5 children)
And how does super heated steam go at breaking down greasy residues? Car part washers use crazy hot steam but still need a surfactant to break down oils. Sterile or not, I'd rather not have greasy plates.
(Score: 3, Informative) by anubi on Wednesday September 07 2022, @12:31PM (4 children)
We used steam at the refinery to clean valves. And JOY. It worked great.
I think our valves were probably as full of baked on muck and oil as anything you would find in an eatery.
Of course, like most anything else, not knowing how to do the work often has substantial risk of injury.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
(Score: 1) by Anartech Systems on Thursday September 08 2022, @02:11AM (3 children)
And it works without the sudsy-make-smell-nice juice? Got some keywords or process names I can google? Sounds like neat technology.
(Score: 1) by anubi on Thursday September 08 2022, @04:25AM (2 children)
Mea culpa! I forgot this is an international forum.
JOY is a brand of dishwashing detergent sold in USA. We found that particular brand worked quite well for grease removal.
Another brand I hear a lot is DAWN brand, but it wasn't around during my refinery days in the 70's.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
(Score: 2, Insightful) by Anartech Systems on Thursday September 08 2022, @08:01AM (1 child)
Ha! I thought you were just stoked at the prowess of your scrubulator. (Now) makes perfect sense.
(Score: 1) by anubi on Thursday September 08 2022, @08:36AM
This was at an oil refinery in the Coastal Mississippi ( a kinda backwards southern state ) in the 70's.
We didn't have anything fancy. Most everyone had farms, cows, goats, pigs, chickens, several dogs and cats. Maybe a horse or two just in case the car broke down. Most raised corn. But the people were just as good as they came.
And even if we did have anything fancy, no one would know what it was or how to fix it.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
(Score: 5, Insightful) by anotherblackhat on Wednesday September 07 2022, @12:22PM (3 children)
“99% of bacteria” sounds like a lot, but how does it compare to just rinsing with cold water?
At best, I'd call this a dish sanitizer, not a dish washer.
Seems to me you'll need a wash cycle before the super heated steam cycle.
I wonder how many "dishwasher safe" plastic dishes would survive super heated steam.
(Score: 2) by JoeMerchant on Wednesday September 07 2022, @02:43PM (2 children)
The age-old question: how much do you rinse your dishes before you put them in the washer...
We just installed a "super quiet 38dB" residential kitchen dishwasher - if you put the plates too close to each other you'll hear them clanking, but otherwise it's hard to tell the thing is on - it's quieter than the refrigerator. The water going down the sink drain at the end of the cycle is significantly louder than the wash cycle. Aaaand: it heats the water really really hot. So far it does a really nice job on the dishes. We had been hand washing for a few months before installing it, and that tended to use warm water - the hot water definitely strips away some haze that had accumulated on the glass, and especially clear plastic, items during hand wash only living.
Україна досі не є частиною Росії Слава Україні🌻 https://news.stanford.edu/2023/02/17/will-russia-ukraine-war-end
(Score: 2) by acid andy on Wednesday September 07 2022, @03:32PM (1 child)
For me, the most unpleasant aspect of washing dishes is separating off any chunks of waste food so that they don't end up blocking the drain or staining the sink. Dish washers don't solve that because you still have a filter to clean. I know people have waste disposal units but those things are scary and it's better to compost the food waste.
Master of the science of the art of the science of art.
(Score: 2, Funny) by anubi on Thursday September 08 2022, @11:47AM
One of my friends has two dogs, one is named "soap", the other's name is "water".
Don't ask him about his dishwasher. He says his dishes are as clean as Soap and Water can get them.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
(Score: 3, Informative) by Adrian Harvey on Wednesday September 07 2022, @12:22PM (1 child)
Sounds more like a commercial steriliser (the kind of “dishwasher” they have in commercial kitchens). Where you typically have to rinse the plate first, then stack for a 3 minute cycle sterilise. As opposed to the home dishwashers we are more used to that take an hour or two, but deal with more dirt and are less intense.
(Score: 3, Interesting) by JoeMerchant on Wednesday September 07 2022, @02:45PM
Holiday Inn kitchen used the hotel boiler as input, a tray of dishes would run through and be "clean" in 90 seconds, but you couldn't touch the plates with bare hands for another 5 minutes after they came out.
Oh, except for French Onion soup bowls, that stuff is baked on forever.
Україна досі не є частиною Росії Слава Україні🌻 https://news.stanford.edu/2023/02/17/will-russia-ukraine-war-end
(Score: 3, Informative) by BlueCoffee on Wednesday September 07 2022, @12:41PM (2 children)
We actually did the same thing in microbiology class 30years ago. Just for fun we put dirty plates in an autoclave and compared the cultures we made before autoclaving and after autoclaving. FFS younger people, stop pretending that you just discovered fire or penicillin when you first learn something new.
(Score: 3, Interesting) by JoeMerchant on Wednesday September 07 2022, @02:50PM
The cultures you got off of the plates after autoclaving could also be called: experimental (or, more to the point, experimenter) error.
Saw a fun article about efficacy of Ketamine in mice for... I think it was depression, but anyway the fun part was: Ketamine was more effective in mice handled by male researchers. Apparently mice get more stressed by male human handlers than female, and that stress released some factor which interacted with the Ketamine making it more effective. So, if you run the experiment and segregate data from your mouse handlers male vs female, the two groups will get highly significantly differing results...
Україна досі не є частиною Росії Слава Україні🌻 https://news.stanford.edu/2023/02/17/will-russia-ukraine-war-end
(Score: 0) by Anonymous Coward on Wednesday September 07 2022, @03:00PM
You can get published now a days for reinventing the wheel ...
(Score: 2) by Opportunist on Wednesday September 07 2022, @01:49PM (1 child)
So instead of heating water to near-boiling level, we now heat it post-boiling level and that somehow magically uses less energy?
I'm intrigued. Tell me more.
(Score: 4, Interesting) by mhajicek on Wednesday September 07 2022, @04:03PM
If it works faster, you heat less water overall, and can have a lower total energy consumption.
The spacelike surfaces of time foliations can have a cusp at the surface of discontinuity. - P. Hajicek
(Score: 2) by isostatic on Wednesday September 07 2022, @03:04PM (1 child)
They also require long cycle times
How long? Why does that matter?
that use large quantities of electricity
How much?
How many kWh does a standard sized dishwasher use. How many does one of these use to clean the same amount. How many kWh is used to heat the water to wash the same amount of stuff by hand?
(Score: 2) by FatPhil on Wednesday September 07 2022, @03:55PM
Unless you don't, because you hate making things more ecologically sound.
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 2) by Entropy on Wednesday September 07 2022, @03:45PM (10 children)
"Super" heated steam/water actually takes a ton of energy to create because as far as materials goes water has a very high specific heat. It's true one may use less soap, but less energy is pretty doubtful. Also with all the talk of global warming how is converting more energy into more heat a good thing?
(Score: 2) by FatPhil on Wednesday September 07 2022, @03:56PM (7 children)
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 2) by JoeMerchant on Wednesday September 07 2022, @07:50PM (6 children)
I think superheated steam may melt your perspex.
Україна досі не є частиною Росії Слава Україні🌻 https://news.stanford.edu/2023/02/17/will-russia-ukraine-war-end
(Score: 3, Interesting) by FatPhil on Wednesday September 07 2022, @09:32PM (5 children)
The thought-experiment is unconvincing. Where's Mythbusters?
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 3, Interesting) by JoeMerchant on Wednesday September 07 2022, @09:45PM (4 children)
You bring up a cool point: pressure. So, yeah, make your generic perspex into 4" lexan (as used in bulletproof applications" and then raise the dishwasher pressure to 10atm while we're at it, raising the boiling point of water to ~175C... no plastic dishes please, but... anything that lives through a steam bath at that temperature should be cultured and studied... just need to hold the dishes in the heat soak long enough for all their bio-contaminatable surfaces to come up to temp, reminds me vaguely of flash pasteurization.
Hell, just barely boiling water at 10atm pressure would do the heat transfer faster than gaseous phase steam, even if the steam were much hotter, and "jet spray" action of the water should mechanically clean the dishes better than steam. Just need a pressure-rated vessel to contain the process in, and as mentioned elsewhere a heat-recovery process so all that lovely energy isn't wasted down the drain.
Україна досі не є частиною Росії Слава Україні🌻 https://news.stanford.edu/2023/02/17/will-russia-ukraine-war-end
(Score: 5, Funny) by deimtee on Thursday September 08 2022, @05:48AM (3 children)
That gives me a great idea for cleaning the dishes. Soak at boiling point at 10 atmospheres pressure, then just drop one side off the steam chamber. Explosive decompression should blow any food scraps right off the dishes.
No problem is insoluble, but at Ksp = 2.943×10−25 Mercury Sulphide comes close.
(Score: 3, Interesting) by JoeMerchant on Thursday September 08 2022, @10:27AM
Only slightly more seriously: commercial kitchen, two dish chambers, dirty dishes loaded and sealed with air at STP. Recently cleaned chamber 90% filled with water at 175C 150psig. Just open a valve between the chambers and you get spray action on the dirty dishes as the chambers equalize pressure, and the areas not under scalding water are hit with superheated steam as the 175C water flash boils with the pressure drop to ~75 psig. Finish the pumping / filtering / heating process to bring the newly filled chamber up to pressure, and any water remaining on the washed dishes should flash off due to the heat of the dishes themselves. Move the washed dishes aside to cool, and repeat.
Soap / surfactant input requirements should be minimal, and mostly recycled. As pointed out earlier, solar power makes cheap hot water, so just have enough dishes to save the washing until 10am to 2pm, and move to a cloudless area for best efficiency.
10 atm may be overkill, further study is warranted.
Україна досі не є частиною Росії Слава Україні🌻 https://news.stanford.edu/2023/02/17/will-russia-ukraine-war-end
(Score: 2) by acid andy on Tuesday September 13 2022, @01:25AM (1 child)
This is why i love SoylentNews. Thank you!
Master of the science of the art of the science of art.
(Score: 2) by deimtee on Tuesday September 13 2022, @10:35AM
If you try it out, let me know how well it works.
No problem is insoluble, but at Ksp = 2.943×10−25 Mercury Sulphide comes close.
(Score: 3, Interesting) by JoeMerchant on Wednesday September 07 2022, @07:50PM (1 child)
If the process is big enough, you can insulate the washing chamber and run heat exchangers to pre-heat incoming water with waste steam/water on the way out. It's not 100% recovery, but it's significant.
Україна досі не є частиною Росії Слава Україні🌻 https://news.stanford.edu/2023/02/17/will-russia-ukraine-war-end
(Score: 1) by anubi on Thursday September 08 2022, @11:59AM
Heat exchangers often provide quite significant energy savings. I often rue my not plumbing my bathroom shower to recover the heat from the drain water by a pipe-in-pipe exchanger to preheat my incoming "cold" water line.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
(Score: 2) by OrugTor on Wednesday September 07 2022, @04:16PM
... and we know that simulation is another word for confirmation bias.