Tyhjiöpulloja

Tyhjiöpulloja, often translated as vacuum flasks or thermoses, are insulated containers designed to keep hot liquids hot and cold liquids cold for extended periods. Their design relies on minimizing heat transfer through conduction, convection, and radiation.

The core of a tyhjiöpullo is a double-walled vessel, typically made of glass or stainless steel. The space between these walls is evacuated, creating a vacuum. A vacuum is an excellent insulator because it contains very few molecules, thus significantly reducing heat transfer by conduction and convection. The inner and outer walls are usually silvered or coated with a reflective material. This reflective surface helps to reduce heat transfer by radiation, reflecting thermal energy back into the container if the contents are hot, or away from the container if the contents are cold.

The neck of the tyhjiöpullo is also designed to minimize heat loss. It is typically narrow and made of a material with low thermal conductivity, such as plastic or cork, to limit heat transfer by conduction. A tight-fitting stopper or lid further prevents heat exchange through convection and evaporation.

Tyhjiöpulloja are widely used for storing beverages like coffee, tea, and soup, as well as for keeping food warm or cold. Their effectiveness depends on the quality of the vacuum and the materials used in their construction. Older or damaged flasks may lose their insulating properties due to a compromised vacuum seal.