How do self heating devices work?

Answer 1

Electric heaters work because electric current is forced through wires that have a good deal of electrical resistance. When electric current flows through any resistance, it generates heat. Remember that moving electrons can be treated as moving waves, and the destructive interference of the atoms in the current path result in the scattering of electrons. This results in the generation of heat. All materials except superconductors have some electrical resistance. When more elctricity is flowing through a wire than it's capapcity, the wire will get hot. This is why the larger the current, the bigger the wire you need. If you ever try to use a small extension cord to power something like a vacuum cleaner or microwave oven, you will notice that the cord gets hot. Electric heaters work the same way. They push a lot of current through very thin specially made wires that have a lot of resistance. Hairdryers, irons, curling irons, portable heaters, toasters and toaster ovens, etc., all work like this. These devices use a lot of power, and you will often notice that using more than one on a single circuit will often trip the breaker. They have no insulation on the heater wires because the insulation would catch fire. Since the wire is bare, you can see it glow. Incandescent light work the same way, but the wire is very, very thin so not as much power is needed to light them up and they rarely trip breakers. They average about 75 watts where a hair dryer can be 1500-2000 watts. A toaster can be up to 3000 watts sometimes.

Answer 2

It consists of 2 chambers and lid: 1 for solid component; 1 for liquid. All process is exotermical chemical reaction. When you pierce the lid, liquid component mixed with the solid one and starts a reaction. The most common chemicals for the self heating can is Al + Mg + Zn or CaO (solid component), and HCl or H2O as liquid. That's all. Simplier than a bike. Just don't buy Ontech - they blowing up :) try to Google Wolfgang pack, really funny!

Answer 3

A can which you push a button on the bottom to mix two chemicals together, which undergo an exothermic reaction which releases heat hence heats up the (coffee) to the perfect drinking temperature.

Answer 4

It is simple really. As the temperature of an NTC (Negative temperature coefficient) thermistor decreases, the resistance increases this causes more friction to occur between the flow of electrons and the thermistors's material. Therefore thermal energy is dissipated/ given off.

Answer 5

self heating cans carry out a exothermic reaction when the button at the bottom of the can is pressed. The chemicals it contains are harmless but it flammable and the chemicals can also vary.