Phase change from ice to water creates heat?

[ExEvolution]

So forgive me if I'm not understanding this correctly, but I was planning a build for a steam geyser tamer that outputs water cold enough to grow bristle blossoms and using oni-db for reference. Well I just noticed that ice has only ~50% of the heat capacity of water, so if I'm understanding correctly, phase changing between ice and water doubles the amount of energy in the water. Is this correct?

 

If so, does that mean that using box of ice connected to the geyser with a thermocouple as a heat sink is worse than a box of water if the same mass, and even worse if it's allowed to phase change back into water?

[mathmanican]

2 hours ago, ExEvolution said:

phase changing between ice and water doubles the amount of energy in the water.

There is even more going on than th his to generate heat. Here is a starting point. 

Here is a rabbit hole that stemmed from it. Back links will get you to @DonDegows post.

 

[DonDegow]

You guys definitely went overboard with it 

To answer your question simply, a ice heat sink will have less capacity than a water heat sink of the same mass.

At phase change, your heat sink will suddenly double its DTU available, it can be desired or not. (meaning if you inject 1000 DTU, it'll turn into ~2000 DTU)

For simpler systems, steam is usually the go-to heat sink material as it's directly convertible to power; using existing ice is definitely OK as it'll eventually turn into usable steam if all buildings in there can handle more than 125°C (steel basically).

[ExEvolution]

I've done full hot steam room builds that work well, but my use case here is specifically for making hot water cool enough for bristle blossoms and I was trying to make a really big heat sink out of ice, but when I realized ice was actually holding less energy than the equivalent amount of water, it means to me that I can't just dump a bunch of cold into ice as a buffer because when it phases to water during an active cycle of the cool steam vent, it is creating heat out of nothing.

I guess I can just keep it with ice and live with the inefficiency until I get access to super coolant, but even then, by the time that comes around, I probably won't need the bristles anymore