The other day it was proposed (Lennart Thornros) that a small steel plate could be placed above an induction heating stove top to intercept a significant quantity of magnetic flux for fuel heating. I decided to make a quick estimate of the power required if this were to be used to raise the plate temperature to 1200 C(1474.15 K).
My preference is to continue the experimental designs using a heating element consisting of high temperature wires. They allow the experimenter to measure the input power much easier than induction techniques. They are also smaller and less expensive. But, in the interest of science it is important to keep an open mind as far as possible hence this discussion. I chose a rough surface steel plate that is 5 cm by 5 cm by .2 cm and assumed it is lying flat upon the induction coil. The only path I calculated for the escape of heat is by radiation. Any additional convection or conduction would increase the total power required. There are 6 total radiating areas in this assumed structure with a total area of .0054 square meters. I used an emissivity of .45, which may need some adjusting at the operational temperature. Using Boltzmann's constant of 5.67*10^-8 I arrived at a power requirement of 651 watts. The formula is P=.45 x .0054 x 5.67 * 10^-8 x 1474.15 ^4. This level of power is within the ratings of a typical induction heating element provided that the steel plate intercepts a sufficient amount of magnetic flux. If a larger steel surface area is required, then the power goes up in direct proportion to the area increase. I read the specifications of some of these inexpensive devices and they appear to make a determination that there is a sufficient load before attempting to apply power into it. This of course will set limits upon the size and type of material used to heat the fuel. And, if the steel plate is raised above the element surface less magnetic flux will be encountered and thus a larger plate may be needed. Most of the water calorimeters along with some type of interface between the steel plate and the water take vertical space. With these requirements in mind I picture a relatively small(5x5x.5 (cm)) milled out block of steel having a cavity just large enough to hold the fuel plus any required extra room. A carefully cut piece of ICE high temperature head gasket material can be used as a seal between the lower milled out steel block and a steel cover that is screwed on. This should yield an air tight design but I am confident that hydrogen will escape easily given enough time. At least this should keep water vapor from getting to the fuel. I have not come up with a good method of interfacing the steel fuel chamber to the water bath of the calorimeter. The outer surface of that interface box(?) is at 100 C while it receives radiation from the steel chamber being held within it. Parkhomov used a steel pot to make the transition. In our case the material needs to be transparent to changing magnetic flux(alumina?). Take this posting as just a beginning concept so please add your ideas. I can see that it is going to be a challenge to get all the pieces to work together with this type of system, but challenges are what makes life interesting. Dave
