Estimated time to freeze for a 12" carbon steel water line, if the water stopped moving. Parameters: 12" carbon steel water line, aboveground, 60F initial water temp when pumps stop working, 0F outside air temp, 5mph wind, assuming infinitely long pipe.
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ANSWERS: 3
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It depends greatly on how you intend on removing the heat... .. Dry Ice will rely on a gas phase heat trnsfer which is very slow.... liquid nitrogen can be much quicker. Practically speaking it will take about 30 minutes to freeze using liquid ... but If you haven't done this before use a service that has.... they will give better estimates.... be careful to not damage or split the line. (or spill cryogenic liquid on the skin... problem changed ignore above...
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YOu need to use the equation Q = hA(Twater - Tair) You should use the LMTD to calc (Twater - Tair) Calc h (total) as 1/h(total) = 1/h(convection) + 1/h(conduction) Calc h(convection) using equation from page 3 of this website http://s3.amazonaws.com/cramster-resource/1656_n_10245.pdf Reynolds number, Nusselt number equations are on the same site For fluid properties use the mean temp, or average of the water temp and air temp - so approx 0degC, properties available on this site http://www.engineeringtoolbox.com/air-properties-d_156.html and calc h(conduction) using h=k/x where k = thermal conductivity of the steel pipe and x = pipe wall thickness.
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AB error - accidentally posted a comment in answer window
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