Design and manufacture a thermos cup, how to make the hot water in the cup cool slowly? Tell me about your design scheme and the reasons for your design.

Water in thermos cups and kettles cools slowly, and there are three ways to spread heat: radiation, convection and conduction. The silver liner in the thermos cup can reflect the radiation of hot water, and the vacuum between the liner and the cup can block the heat transfer, while the bottle which is not easy to transfer heat can prevent the heat convection. Or use the material itself (plastic is more insulating than metal); Thickness of cup; Small cup mouth; "Overwritten".

Or raise the ambient temperature, such as putting it in warm water; And put the cup in a place where the air is not circulating, and put the cup on a warm surface (foam is better than wood and marble).

These methods can make the water in the cup cool slowly, depending on what you use, and it would be better if you had an insulated refrigerator.