There is a good news for those who has ever burnt their tongue on a boiling cup of coffee. A Stanford grad Dave Jackson and entrepreneurs Dave Petrillo are working on coffee joulies.
How coffee joulies work?
You drop the joulies into your cup, pour in the coffee, and the temperature drops to a drinkable level. The phase changing material inside each joulie then heats up the coffee once it’s gotten too cold, making the entire experience comfortable longer.
Each Joulie is a small metal shell filled with a phase-change material that melts at 140º Fahrenheit. (Some people might prefer 155º — perhaps there will be a version for us.) So the Joulies absorb heat from the coffee till they reach 140º, and then start emitting heat. The effect (if you put in enough Joulies for your volume of beverage) is to maintain the coffee at the desired temperature for long enough to savor it. Using an insulated cup is recommended also.
This amazing feat of thermodynamics happens thanks to a special non-toxic material sealed within the polished stainless steel shell. This material is designed to melt at 140 degrees Fahrenheit, and absorbs a lot of energy as it melts. This is how Joulies cool your coffee down three times faster than normal. Once it reaches this temperature, the special material begins to solidify again, releasing the energy it stored when it melted. This is how Joulies keep your coffee warm twice as long.