Cooling things in water vs air

In summary, the conversation discusses the cooling process of a pressure cooker after cooking beans. The question is whether the cooker will cool faster if left in a sink full of water or if taken out of the sink. One person suggests that removing the cooker from the water and splashing cold water on it will result in maximum cooling. Others mention the factors such as thermal balance, insulation, and surface-volume ratio that may affect the cooling rate. However, it is generally agreed that the pot will cool faster outside of the sink due to the difference in thermal mass.
  • #1
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Hi everyone

After I've cooked beans in a pressure cooker, I put the cooker (with beans inside) into a sink full of water to help it cool down. After a while, the water heats up. At this point, would the cooker cool faster if I left it in the sink or if I took it out again?

I'm guessing it would be the latter because the air would be cooler than the water (the water feels lukewarm after it's absorbed heat from the cooker).

Is this correct, or am I looking at things too simply?

I'm just interested in the theory behind it. I pretty much leave the cooker out all day to cool. Either way will probably make little difference. Thanks
 
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  • #2
If after the initial cooling in water, you remove the cooker from the water, it will then cool by evaporation until the surface dries. Each time you splash water on the cooker it will cool again.

Running a slow steady stream of cold water over the cooker, and then down the drain, will probably give the maximum cooling rate.

For the same temperature difference, the transfer of heat to air will probably not be as fast as the transfer of heat to water, but the temperature difference equilibrium point is going to be hard to calculate.
 
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  • #3
If when you want to remove the pot it has the same temperature as the sink, (thermal balance), then leaving it inside will have a time that depends on how the water in the sink evaporates and how the sink is isolated from the environment. But if you remove it, only the water around the pot evaporates and the cooling speed of the place where you place it will depend, the lower the air temperature the faster the pot will cool. Without more data on the insulation of the sink, we will only be guessing, if it is the same environment, whose air is renewed, if the water in the sink is not renewed, then the cooling speed will depend on the surface-volume ratio for both the pot and the for the sink and the possibility of convective air currents forming around it. Everything would indicate that it would most likely cool faster out of the sink, but this depends on many experimental factors that are not established, to be able to say exactly.
 
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  • #4
Richard R Richard said:
the surface-volume ratio for both the pot and the for the sink
Theoretically, that is the main point.
Volume increase faster than surface area.
Within the sink the thermal mass that has to decrease in temperature is that of the pot and the water in the sink.
Out of the sink, the thermal mass is just that of the pot.
Having a greater surface area/ volume, the pot on its own should cool faster after having being cooled down from being placed with the sink.

As you say though, about experimental factors ...
 
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