Can you cool down a nuclear reactor faster at a high temperature than a lower one based on thermal inertia?

Oak Ridge North

Just a question that came up at work, we have some theory to practice data but no real control. Is there any fact behind thermal inertia? Example a pot of hot water at 200F and a pot at 50F which will freeze first?



Hebron

Thermal inertia is another name for bulk heat capacityIn the formula:Q = m*c*deltaTthe m*c part is the "thermal inertia".Thermal inertia depends upon:1. mass of object of interest2. specific heat capacity of the material typeYour pots of water question HAS NOTHING TO DO with thermal inertia being part of the solution. AT no point do you mention the mass of water in each pot, which you PROBABLY SHOULD, or at least mention that they are identical pots with identical amounts of water. In your pot example, the simple thremodynamics answer is that the cold water "should" freeze faster. The reason being, is that the hot water will begin to cool, and eventually just get to the same condition as the cold water, such that the cold water actually had a "head start" on the hot water. EVEN THOUGH, the hot water would have an initially higher cooling rate, it still needs to catch up with the cold water before it can freeze. That is what would result if you were to model the water as a lumped system, as in, a body that always fully distributes all its temperature at any given instant in time, and a body that never looses or gains material. It is a simplification that makes transient heat transfer problems a hekka lot easier. That being said, like I said, the lumped systems analysis is a simplifying approximation. Reality however DOES NOT match these results. We give a name to this inconsistency, we call it the Mpemba Effect. http://en. wikipedia. org/wiki/Mpemba_effe…IF you read the article carefully, it says that "in certain specific circumstances, warmer water freezes faster than colder water".And it even specifies what those "certain specific circumstances" are. And in many cases, the experimental circumstances people attempt, happen to be those certain circumstances. It isn't always the case that hot water freezes faster than cold water...it just happens to be the case in many circumstances. In other circumstances, the result is the opposite.



Somerville

The pots are not quite a parallel with the reactor. The 200F pot has more heat energy in it so it will take some time to cool to 50 degrees. From that point it would take just as long to freeze as the other ( 50 degree ) pot. So it takes longer to freeze a 200 deg pot than a 50 degree pot. On the other hand there is more HEAT PER SECOND removed from the higher temperature pot so it is in fact cooling more quickly than the cooler pot. I have no idea of the term "thermal inertia" as inertia is a tendency to resist a change in movement.(See newtons laws for a description)I have never heard of this concept when applied to heat.



Lino Lakes

gintable FTW