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[EnergyPlus_Support] Re: Simulation of a water pipe

Hi, I'm still working on this simulation: I'm simulating with only water in the pipe and trying to model the real situation of the heat exchange by varying the waterflow, as you suggested. 
I found out that the outdoor pipe simulates only a convective heat exchange: in the Engineering Reference (page 687) the equation that describes the model uses the film convective resistance, but ignores the pipe's material conductivity. In fact, if I change the material's lambda value, the heat loss value does not change. 
Is this correct?
How can I simulate the pipe with both convective and conductive losses?

Thank you

Stefano






--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Edwin Lee <leeed2001@...> wrote:
>
> 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@...>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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