Quizzes & Puzzles7 mins ago
Pressure Rise v heat input
How do I calculate the rise in pressure of a contained volume of water, for a given temperature rise?
I have a 10 Litre tank filled to the brim with water and then sealed off. What happens to the pressure inside the tank if the water inside is heated?
Answers
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For more on marking an answer as the "Best Answer", please visit our FAQ.You are testing two properties of water, here: The coefficient of thermal expansion and its elasticity.
At 20 degrees C, water expands by 200 parts per million for each degree rise in temperature, rising to 300 ppm / C at 30C.
The elasticity is about 50 parts per million for every additional atmosphere of pressure.
Suppose you heat your 10 litres up from 20 to 30C it will try to expand by about 4 cc, but this will be resisted by the steel container, creating a pressure of 12 atmospheres equivalent to a depth of 120 metres.
Even at the bottom of the ocean, 4km down the water is only compressed by 1.8%, which you would reach before your experiment hit 50C. This is a pressure of 6000 lb/sq in, Three tons per square inch!
Your steel container would have to be made to extreme specs to handle this, although it's volume would also expand as it got warmed up by the water, which would take off some of the strain.