Archis's Blog

December 22, 2011

Proud owner of the world’s most advanced kitchen beverage heater

Filed under: Uncategorized — Tags: , , , , , , , — archisgore @ 6:11 am

I’m kiddish, and do stupid stuff to pass the time. Pretty proud of it too. Of all the stuff I do, once in a while, something interesting comes of it. This time, what started as a mis-communication with a friend over why it takes more than five minutes to heat wine (and 2 months later, when I did the math, it makes sense why), I decided the world could do better. Surely with all of man’s ingenuity, we’d have a device that allows us to heat stuff fast, and keep it at a temperature we desire. Thermostats aren’t new – but you’d be hard-pressed to find a kettle or heating rod that’ll do this even today.

As is bound to happen, I began building something of my own. It’s not until you do the math that you realize just how much specific heat water has. It’s a miracle we get it to boil at all. Pumping in that much energy into a thermodynamic system that fast was a problem. My heating elements would have to heat up too rapidly and I needed some way to control them.

The next step was obvious. A trip to radio shack, an Arduino and a fast-switching MOSFET, turned into a pulse-wave modulated heating element  - beyond which the original intentions of heating wine fast no longer mattered – I was chasing some crazy high.

I ended up building a device that gets multiple feedback readings plots them on a logarithmic function, and injects heat at the rate at which said liquid can absorb safely, without the boundaries over-heating, and can compute the rate of heat loss from the system through radiation or evaporation (before you ask, yes, at that point I was caught up in the feature-hole – just adding stuff because I could.) Microcontrollers in the hands of a software engineer are dangerous. Once you have one, you find yourself with limitless power and the ability to add frivolous sensors and features, for cheap.

Anyway, a quick survey among friends (which is a pretty biased sample – since they always tell you what you want to hear)  indicated that it may be quite a nifty little thing for home use. There are plenty of liquids that needs to be regulated in a small temperature window. Thermostats are typically fairly brutal in their operation – they turn on and suddenly heat up your elements rapidly, and abruptly shut off. You can’t really regulate them to say turn on 1/5th of a second, each second, so that you don’t get the massive temperature variance.

It’s been quite an adventure, and I practically burnt through my life savings. I am a trained programmer, but electronics has been a hobby. I’m worse still when it comes to fabrication. Fabrication is an art, and as such cannot be objectively studied. As much as I’d like to be, I’m not MacGyver. My initial tools of choice were test tubes, and beakers – stuff you’d find easily, but not stuff that makes a good product. I learnt a hard lesson – material science is a “thing”, and one that deserves more respect than I had given it for a long time. Finding a material with all the thousand properties that make a good food-safe barrier between your electronics, and… well, food, is a challenge.

So I stand here today – owner of the world’s arguably most advanced device ever possessed for the purpose of heating wines – and one that I dare not use, for fear of accidentally starting fires.

As I mentioned above, when you really do the math, it takes about 4 KJ to heat 1 liter of water by 1 degree C. Assuming you want it at near boiling (say 95C) from room temperature of say, 30C, you’re looking at a 65C difference. You need about 230 KJ to heat it up. That’s about 230 watts per second for a thousand seconds (about 16 minutes) not counting any heat losses. No way do I have the guts to  run that kind of power through anything I built at home. I have some experience with microelectronics, but those who handle power electronics are in a different league altogether. It’s a wonder we live such safe lives given how much power circulates through our grids around us at every moment.

I am however, looking for investors. I’ve filed a provisional patent, and would welcome any contacts, startups, large companies, kitchen appliance companies to revolutionalize the world of… heating wine?

Until my next project then….

January 13, 2010

Medical Capsule dilution experiment

Filed under: 1 — Tags: , , — archisgore @ 12:13 pm
Picture of Capsule Dilution experimental setup

Capsule Dilution Experimental Setup (click image for larger version)

So… once in a while you want a controlled release of certain substances in a solvent, and the easiest method with minimal chances of failure is to have a capsule that slowly dissolves in the solvent, thereby unleashing whatever awesomeness you have stored inside.

Timing with capsules can be quite a feat, and for some upcoming big plans, I needed to have a controlled release of large capsules simultaneously. This experiment was designed to study that.

The picture above shows the experimental setup. The capsules used are B-Complex vitamin supplements. I opened one of the capsules to replace the stuff inside with a colourant (thereby allowing me to visually see when the capsule got broken), but since all my solvents were colourless, and the stuff inside was a yellowish powder, I figured it would suffice to use them as-is.

I wanted all this on video, but I left my handicam DVDs in Pune with my parents, and had forgotten to buy new ones, with very little chance of me getting them at 1:30 am in the morning.

Let’s get to the contents of each of the containers – they’re all labelled in the picture. We’ll refer to each container combination as Ci where i=1 to 5.

C1 Water
C2 Water
C3 Isopropyl Alchohol
C4 Diluted Ethanol (Vodka)
C5 Citric Acid + Acetic Acid

Now I’ll get to a table with the timeline as per my log entries and you’ll know just what happened.

 1:35 Capsules were inserted in C1, C3 and C5 to test water, alchohol and acid . All 3 capsules float on all liquids.
 1:35:30  Water bowl (C1) immediately shows dissolution. The capsule’s outer shell is dissolving. I wonder if the width of the bowl was a factor that the achohol and acid didn’t have, so I start to setup C2 with a narrow tumbler.
 1:40:40  C5 shows signs of dissolution, yet mild. C1 is dissolving significantly.
 1:42  C2 is started – starts dissolving within seconds and at 1:42:30 has colours diffusing in the water. The capsule floats.
 1:43:30 C5 is slightly dissolving. Constant rate. Slow. C2 is rapid. C3 has NO CHANGE. I mean this is shocking – the capsule might as well be in an inert fluid. I decide to determine whether the type of alchohol matters. I begin setting up C4 with ethanol (knowing very well that vodka isn’t pure alchohol and my ethanol supplies having run out, I would have to make allowances for the water content in Vodka being responsible for a significant portion of the dissolution)
 1:46:30  C4 started. The capsule floats. C1 is almost broken. C2 is a close 2nd. C5 is now visibly dissolving – the colourants from the capsule’s outer shell are mixing evenly (unlike in water where they were breaking off and sinking to the bottom). C3 – NO CHANGE! C4 is going pretty fast.
 1:48:31  The picture you see above was taken.
 1:49:30  C1 broke. The contents within it sank to the bottom. C2 is almost broken. C3 NONE. C4 catching up fast. C5 broken. C5 seems to have been broken a while ago, but it’s contents weren’t coming out of the capsule. This may have something to do with the fact that these were vitamin tablets containing all acids and perhaps the water had already been saturated with an acid.
 1:52 C2 almost there…. C4 close behind. 
 1:54  C2 the capsule is shrivelled but the contents are not yet exposed to the solvent.
 1:60  C2 broke with contents now exposed to the solvent and started diffusing.
 1:59  C4 still in the race. Given up on C3 it had NO CHANGE!
 2:16  C4 broke. (many logs between 1:59 and this entry have been omitted that only record “no change”)

Each solvent’s start and end time is presented below

  Start Time End Time Duration
C1 1:35 1:49:30 19:30
C2 1:42 1:60 18
C3 1:35 practical infinity infinity
C4 1:46 2:16 30
C5 1:35 1:49:30 (maybe upto 30 seconds before) 19

 

Conclusion: Alchohol in water is a good way to control the dissolution timing of each capsule. Given capsules that are thinner, we could start with a base-line water-dissolution lower than whatever we want, and then mix enough alchohol in the water to fine-tune the time.

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