Understanding and Measuring Vitamix Horsepower | Hacker News Reader

Understanding and Measuring Vitamix Horsepower

joyofblending.com

19 pointsnkurz6 comments

To me, the most interesting statistic in the article is that the overall efficiency of heating water with a Vitamix blender is 68-69%. That is, more than 2/3 of the input wattage coming from the wall goes to heating the mixture being blended. The overall efficiency of heating a cup of water in a microwave oven, by contrast, is usually less than 50%.[1]

I find that to be a remarkably high efficiency. It's obviously less efficient than an immersion resistance heater (100% efficiency since all the "waste" heat is absorbed), but I wouldn't have guessed that the high speed motor would be that efficient in converting electricity into rotational motion.

[1] Tom Murphy measures 43% for a microwave oven here (as well as figures for other approaches): http://physics.ucsd.edu/do-the-math/2012/05/burning-desire-f...

OK, now I want to try boiling water with my Vitamix.

As an added bonus, after 11.5 minutes of listening to a Vitamix on high, you won't need that cup of coffee to wake up.

I know! Holy shit, I did not know that you could boil water purely by means of subjecting it to the motion induced by a blender.

Update: from the sound of things, it's the action of the blades and the friction induced by their interaction with the water[1], rather than the swirling motion of the water itself, which sounded kind of ridiculous.

[1] http://frozendrink.com/vitamix/household.html

There's blade-water friction as well as water-water friction. The link you provided does not quantify their relative contributions. [edit: Actually, I'm not even sure how much blade-water friction there is, due to the boundary layer effect.]

There is also heating from cavitation bubbles collapsing in the water. If you look up cavitation heaters you will find a wacky rabbit hole with unsubstantiated claims about achieving heating efficiencies over unity. However, apparently there are some industrial processes that benefit from cavitation heating by getting even liquid heating and avoiding heating elements that can develop scaling. More info: http://hydrodynamics.com/cavitation-technology/scale-free-he...

Do you not make hot soup with it already ?

We make hot porridge in ours too.

As for the noise - someone is on that http://www.whisperblend.com/

Indeed, in the early days, horsepower was used to describe how many draft horses a steam engine could replace.

Is this an example of engineering marketing? Probably: https://en.wikipedia.org/wiki/Horsepower#History_of_the_unit

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