PRESENTATION OUTLINE
BACKGROUND INFO
- Dating back to 1920s
- Did not become popular until 50s
- Japanese soldiers used these in War
- Can last from 30 minutes to 24 Hr.
- Created by Niichi Matoba
TYPES OF HANDWARMERS
- Air Activated
- Supersaturated Solution
- Lighter Fuel
- Charcoal
- Battery and USB operated
Air Activated
Includes various chemicals (activated carbon, salt, water, iron, etc.) As the disposable packet is opened, oxygen crosses the permeable cover and reacts with iron, this causes heat between 1-10 hours.
Supersaturated Solution
Traditionally it is sodium acetate but others can be used (calcium nitrate.) The salt must be more soluble in hot than cold water. There is a stainless steel strip and as it is bent, crystallization starts and heat is generated. Usually lasting 30 minutes to 2 hours. These are reusable hand warmers because the packets can be boiled in water and return to its original state.
Lighter Fuel
Platinum (glass fiber gauze) is used to promote the oxidation reaction of lighter fuel in air, generating frameless heat. This is also reusable, which can stay at 140-160 degrees Fahrenheit for up to 24 hours.
Non-chemical
Most popular type of non chemical devices are battery operated. A hand warmer that connects to a computer USB slot has been developed. Hand warmers with batteries generate heat through a resistance converting electrical energy from the batteries into thermal energy. Can last up to 6 hours and are rechargeable.
