Help with Induction heating for steam

Thread Starter

mike schwarcz

Joined Apr 4, 2007
2
Hi,

I'm working on a project that would require the ability to heat water into steam via electric induction, preferably DC or via AC converter if necessary.

I'm thinking a monotube design with an induction coil surrounding it that could produce steam from 2 quarts of water in say 30 seconds or less.

Anyone here have experience with that kind of design?

Thanks,

Mike Schwarcz
 

thingmaker3

Joined May 16, 2005
5,084
Induction heating won't happen at DC. You need a changing magnetic field in order to induce current in the target conductor.

Water is not a very good conductor. Water also has unity permeability.

I suggest inductive heating of a ferrous metal container (martensitic or ferritic, not austenitic), in turn heating the water by conduction. (Heat conduction, not electrical conduction.) This is how the induction heater rice-cookers work.

Converting 2 liter of water into steam in thirty seconds will require industrial power input. (Those pesky Laws of Thermodynamics always spoil everybody's fun.) Expect no more than 50% efficiency - plan on half your i/p electrical watts going into the workpiece as heat.

I need to head off to work - I'll babble more on this later today.

What's a "monotube" in this context?
 

Thread Starter

mike schwarcz

Joined Apr 4, 2007
2
Induction heating won't happen at DC. You need a changing magnetic field in order to induce current in the target conductor.

Water is not a very good conductor. Water also has unity permeability.

I suggest inductive heating of a ferrous metal container (martensitic or ferritic, not austenitic), in turn heating the water by conduction. (Heat conduction, not electrical conduction.) This is how the induction heater rice-cookers work.

Converting 2 liter of water into steam in thirty seconds will require industrial power input. (Those pesky Laws of Thermodynamics always spoil everybody's fun.) Expect no more than 50% efficiency - plan on half your i/p electrical watts going into the workpiece as heat.

I need to head off to work - I'll babble more on this later today.

What's a "monotube" in this context?
Thanks for your response!

Monotube would be a single tube water supply. I was visualizing a water supply tube or tubes surrounded in by induction coils to generate steam on a mobile platform without a power plug in or burning fuel.

What 'm thinking of is something like a steam boiler. In the steam boiler case you would have multiple tubes of water being heated or sometimes just one coiled tube that the water travels in on it's way to becoming superheated into steam by the application of heat.

I had read that induction heat can heat a metal object to say 1,700 degrees
in just a few seconds. This technology is commonly used to attach sprockets or gears to shafts for example.

I cannot get any info on the amount of power required but as you said it's probably pretty substantial. If it's on the order of 1-3 kilowatts, that's doable with a good 24 V deep cycle battery and an inverter.

My concept is based on the ability to generate steam very quickly and induction seemed to be the way to go. The engineering trick is to get the most steam for the least energy of course. And of course the challenge of making it mobile.

My basic problem is being able to do the calculations to arrive at a power need. I've buried myself in Joules, henries, and the molar heat of
vaporization and in the process have come to realize I'm no engineer.

Mke
 

recca02

Joined Apr 2, 2007
1,214
as far as water to steam conversion calculations are concerned they wud depend on the pressure value you are aiming, try using steam tables to get the value of enthalpy change you wud be required to produce.or i can help u with that if u give me the values. again as mr thingmaker said expect low efficiency from the heat exchanger and all. so you wud require to take many considerations into account for calculation of power input to the induction
coils. i have less idea about induction coil calculations.
 
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