Re: [EnergyPlus_Support] Simulation of a water pipe

[Edwin Lee <leeed2001@xxxxxxxxx>]

Not sure if you are still working with this issue or not.  The pipe heat transfer object can definitely only handle one fluid running through it.  You may be able to make a good estimate at the loss by running a custom fluid through the pipe using manually generated glycol data for density, specific heat, and conductivity.  This could be a weighted average assuming the air and water are close to isothermal at each point along the length of the pipe.  The work to generate this data may not be worth it, so you may also consider running the pipe with a large flow of water, and then with a very small flow of water.  Look at the bounds of the heat loss and make an estimate.  This neglects the air, but should get in the ballpark.

Edwin

On Fri, Apr 10, 2009 at 3:02 AM, Stefano Galli <ste_gallo82@xxxxxxxxx> wrote:

Hello, I am trying to calculate the thermal loss of an external pipe installed in an aquatic amusement park.
The pipe is not totally filled with water: just a small amount of water flows in it. The rest of the pipe's section is occupied by air: the water is heated and has a fixed temperature. There is no control on the air temperature in the pipe.
I need to calculate the thermal loss in order to size the heating plant and to evaluate the option of installing some sort of thermal insulation on the pipe.
Is it correct to simulate the pipe with a pipe:outdoor ? Is it possible to simulate just the small waterflow or pipes can only be totally filled with just one fluid?

Thank you!

Stefano

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