Good article on cooling systems


Lots of good info. Note tho that he confuses “specific heat” with “heat exchange coefficient” so his numbers re. the relative advantages of water, anti-freeze and mixes are wrong. Specific heat is how much heat energy can be absorbed. Heat exchange coeficient is how easily something absorbs or dumps heat. How well something works as a heat exchange medium is related to both.

Maybe he didn’t so much confuse the two as simply neglect the role of heat exchange coefficient.

Something with a high specific heat, but low heat exchange coeficient can carry a lot of heat energy, but then doesn’t want to dump it. Think of iron. Lots of heat energy but slow to dump it.

Something with a low specific heat but high heat exchange coeficient will rapidly dump heat, but since it doesn’t have much heat to dump, it’s temp drops quickly. Since heat exchange is relative to delta T, once there isn’t much temperature difference, heat stops moving. Think of hot air. Doesn’t really contain much heat energy, but will dump it in a hurry.

The charm of water as a heat exchange medium is not only that it will absorb a lot of heat (high specific heat), but also that it is happy do dump the heat in a hurry (high heat exchange coef). Pure water is a better heat exchange medium then a 50/50 mix, but the difference isn’t as much as the author states, due to neglecting heat exchange coef.