It can be heated in hot water after it becomes cold, and it can be used for secondary use when the hand warmer becomes transparent, as long as the hand warmer is not hot, it can be put into hot water for heating, but it cannot be put into water higher than 60 degrees for heating.
The principle of breaking the heat hand warmer is a physical and chemical phase change, that is, the phenomenon of heat release by dissolving or precipitating the process. As long as the small iron piece of the hand warmer is broken, momentum will be generated, and the process of liquid solidification is that momentum is converted into heat. However, if the temperature is too high, if it is close to the skin for warmth, it may burn the skin.
The bag contains the supersaturated solution sodium acetate, and the metal sheet inside is actually applied friction to eliminate the unstable "stable" state of the supersaturated solution, so that the solution forms tiny crystal nuclei on the surface of the metal sheet and grows rapidly, consuming the supersaturated part of the solute in the solution until the solution enters a stable saturated state, at which time the "hand warmer" is released.
Hand warmers can be roughly divided into three types:
1, with heating water to heat, that is, we commonly known as hot water bottle, different from the traditional hot water bottle, electric hot water bottle saves the trouble of adding water, as long as the power plug and wait for 10 minutes can heat up, in fact, the water inside boiled, so the general temperature will be very high.
2, through chemical reaction to heat up, the hand warmer on the market is of this type, through the contact of the chemicals inside, the heat generated, the temperature is about 40 °C.
3, is the use of lithium battery function, internal heating sheet heating, the use of USB interface charging and discharging, similar to hand warming mouse pad, because lithium battery can charge and discharge function, generally can also be used as mobile power. Small size, easy to carry around, the temperature can reach about 50 °C.
principle
Appearance: A sealed plastic bag filled with transparent liquid with a metal sheet in the liquid.
1. Use - gently bend the metal sheet in the bag, and the liquid in the bag will appear crystalline (blue translucent) and harden into a solid. The heating temperature is about 50 degrees (about 1 hour).
2. Reserve - after use, put it in boiling water and boil for 10 minutes until the crystal completely recovers to a transparent liquid, and after cooling, it can be used again.
3. The product can be used repeatedly according to the above methods.
4. In the hot summer, you can change to cold treasure, use it like an ice pack, prevent heat and cool down, but you need to freeze it in the refrigerator before use.
