How to Build a Microwave boiler controlled by raspberry pi?

I am looking to build a milk boiler with in pH sensor to  study the quality of milk at various temperatures.

sort by: active | newest | oldest
steveastrouk3 months ago

Why microwave ? It seriously complicates things

ArvindhS3 (author)  steveastrouk3 months ago
I choose Microwave because it can boil the milk in seconds and I read in a post that microwave can heat uniformly without disturbing the milk proteins. So I thought why not build a boiler with microwave and monitor the milk health using pH sensor.

I sorry if I miss something here

I think the complication is that your sensor wires (i.e. pH and temperature) are stuck into the middle of a microwave field. The sensor wires, and the electronics these wires are connected to, are going to tend to get cooked, along with the milk.

So, if you really want to cook with microwaves, you will have to put some serious thought into methods for to keep your sensors, and connected electronics, protected from microwaves.

What if you circulate the milk using a pump. The milk could be pumped thru plastic tubes to allow the microwaves to penetrate then, in a different part of the circuit, put your sensors.

Yeah. That might work. It might require some kind of tube-through-a-shield kind of bulkhead fitting. Or maybe just an ordinary bulkhead fitting, that looks like a short length of metal tube, solidly, electrically, connected to the metal oven wall it punches through.

Actually I think there is some mojo like this on the wires that carry the filament current into the body of the oven's magnetron tube. Those wires are insulated from the rest of the metal body of the tube. Essentially the filament is cathode. The metal body is anode.

I should probably draw some pictures of this, but I might not bother.

What I mean by tube through-through-a-shield, is I am imagining some sort of mesh, with small holes, kind of about the same spacing as the mesh used for the see-through area in the oven's door. This mesh is in the middle of the fitting, and the milk has to flow through it.

But the mesh might not be needed, if a short length of metal tubing can act like a waveguide,

with a lowest allowable frequency (c/(2*d) where d is inner diameter of the tube) that is much higher than that of the actual microwaves bouncing around in the oven.

Although, I don't know how long that short length of waveguide has to be.

It might be that the reason the holes in the see-through mesh, in the oven door, are so tiny is because they have no depth. Those holes are not lengths of waveguide, because they have no length. If that kind of hand-waving argument makes any sense.

By the way, I do not have any real experience designing waveguides, or antennas, or shieldy things. So any advice I give on this topic is totally in the domain of wild-ass-guess.

So can almost any hob. Don't make things more complex than they have to be.

iceng3 months ago

Steam heating of food (Milk) is the most efficient heat transfer... Used by major casinos all over the world and coffee milk frothing machines also all over the world..

Microwaves cause molecular friction between the water atoms that are a major constituent of milk and may damage individual milk molecules that are so carefully manufactured in a multi stomached bovine... So I would expect a full bio chemistry PHD detective would need to assist you in evaluating how dangerous you would make your friendly nourishing white liquid with energetic radio waves....

ArvindhS3 (author)  iceng3 months ago
Thanks much for the inputs iceng. I will look for steam based boilers and see how it works.