A thermos is a temperature-insulated container designed to keep beverages or food either hot or cold for an extended period. It works by having two walls with a vacuum layer in between, which minimizes heat transfer by conduction and convection. The inner surface is typically coated to reduce heat loss by radiation, and the container is sealed tightly to further maintain the temperature of its contents.
How a Thermos Works
- The vacuum between the two walls prevents heat transfer through conduction and convection since a vacuum lacks particles to carry heat.
- The inner surface often has a reflective coating that reduces heat loss by radiation.
- The lid or stopper is designed to fit tightly, minimizing heat exchange from openings.
History
- Invented in 1892 by James Dewar, originally called the Dewar flask.
- Commercialized later by Reinhold Burger who named it “Thermos” for consumer use.
- It was initially used by scientists to keep substances at stable temperatures before becoming widely used for keeping drinks and food hot or cold.
Common Uses
- Keeping coffee, tea, or soups hot.
- Keeping cold drinks like water or juice chilly.
- Used for food storage on camping trips or in daily life for temperature maintenance.
In summary, a thermos is a specialized vacuum flask that keeps liquids and foods warm or cold by preventing heat transfer through its vacuum-insulated walls and tight sealing.
