The Revenge of the Hot Water Bottle
The Revenge of the Hot Water Bottle
Imagine a personal heating system that works indoors as well as outdoors, can be taken anywhere, requires little energy, and is independent of any infrastructure. It exists – and is hundreds of years old.
Cool article. I love my hot water bottle, don't know what I'd do without it in winter.
Naturally a hot water bottle can get quite hot, but it is anything but energy efficient. Water is the substance with the highest caloric value . Naturally a hot water bottle can get quite hot, but it is anything but energy efficient. Water is the substance with the highest caloric value (4.196 J/gK, Copper has only 0.382), that is, it takes a lot of energy to heat a liter of water and in the bottle in les than 1 h it's ambient temperature
More efficient are chemical solutions, which heat for many hours with simple and environmentally friendly ingredients. These are mainly used in these thermal patches, which heat up in combination with air and provide heat up to 50ºC for 12 hours and more.
The ingredients could not be simpler, iron filings, sawdust and activated carbon, that is, practically waste. This mixture, with the humidity of the air, produces this heat by the oxidation of the iron. Later, when they are spent, it can be used even as a nutrient component in the soil for plants.
This makes no sense. Being able to store a lot of heat energy is exactly what you want. Of course it takes more energy to heat water than a sheet of aluminum, but which one is going to stay hotter for longer. Any chemical solution isn't going to magically get you more energy out than you put in.
A water bottle (~1 liter Water) need a lot of energy to heat the Water and stores the heat for1 Houre, not more. This patches don't need any energy to heat, no more than the humidity of the environment, to start an exothermic process that lasts between 8-12 Hours, depending on the size of the patch. It requires no more energy than taking it out of the package so that it starts to heat up on its own. It does not require any external energy input, such as heating water electrically, with gas or other fuel, to heat it first, as is the case with the hot water bottle.