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Originally Posted by Chris Y
That reminds me of a vaguely-related question that I've been meaning to ask for some time...
What's easier to change the temperature of - a gas like air, or a liquid like petrol? i.e. for the same volume.
I'm guessing the gas would be, due to lower density? Or am I barking up the wrong tree?
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'Fraid that's a bit of a nonsense of a question Chris. Think about it... a cubic meter of air weights 1.2kg, a cubic meter of petrol weights about 740kg. So when you say "easier" are you asking how big a heater you would need to change the temperature? Or how long it would take at a given heat transfer rate? Or how big a heat exchanger you would need to change the temperature at the same at the same rate?
Basically liquids conduct heat much better than gasses so can be heated/cooled more easily, but they're a lot more dense so need a lot more energy to effect the same temperature change.
