Hacker News Reader

Comment by droopyEyelids | Hacker News Reader

What liquid has 4x the specific heat of water? Water is 4.1 J/g°C

I dont think much else even comes close

so i put on my scientist hat and started to write a reply going through the mechanics of beating water's heat capacity, first pointing out that what you want for these types of systems is likely high volumetric heat capacity rather than gravimetric. then i went on to discuss the density of room temp ionic liquids (RTILs), only to find myself digging into their heat capacity numbers and man, you're right! I forgot how well water stores heat compared to other liquids. RTILs vol. heat capacity has trouble breaking 2 J/cm3-K![1]

[1] Table 4, https://www.researchgate.net/publication/231542196_Heat_Capa...

To beat water's specific heat, you have to cheat and use a phase change material (special wax) that melts near the desired water temp, or a bit higher if you use a cold water mixing value.

Wax

Paraffin is 2.1 Kj/whatever

https://www.researchgate.net/publication/336006577_Comparing...

That’s missing the phase change energy, which is in the zone we’re looking at here.

Not necessarily. If you're trying to heat water to 120º you may not want the paraffin to phase change at all. Because then you have a problem transferring heat from liquid->solid->pipe->liquid.

Phase change seems to work better for trying to maintain an ambient temperature. The input side is always going to be cold, and at some times of year far colder than others.

Reply on news.ycombinator.com