Thermos Flask

Thermos Flask

A thermos flask is a device that applies all three methods of heat transfer. It has a double glass bottle. The inner surface of the outer wall and the outer surface of the inner wall are very polished. The space between the walls has been vacated. The entire system is encased in a metal case that provides a cork at the bottom and a felt pad in the neck for protection. Glass is a faulty heat conductor where air, cork, felt, etc. used in thermos flasks all have heat conductors. Therefore, they prevent any damage caused by carrying. When a hot liquid is kept in a bottle, it stays hot longer. Any radiation of heat from a hot liquid is reflected from the inner surface of the outer wall. Also, due to the space between the walls, heat cannot escape from the liquid through correction or convection. Thus all three heat transfer processes fail to transfer heat. The energy of radiation transmission, transport or heat from outside cannot reach the liquid due to any kind of surface and the space between them.