Re: [EnergyPlus_Support] Re: Pipe:Indoor Pipe Fluid against Ambient Heat Transfer Rate

["'jeannieboef@xxxxxxxxx' jeannieboef@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx>]

Re: 2) the embedded pipe (lowtemperatureradiant) model in e+ can't handle being placed between thin (highly conductive) layers of a construction. It needs the thermal diffusivity to be high enough for numerical stability. I thought was that perhaps the same is true for your pipe. 

I suggest testing it with a thick steal pipe, and further testing with different plastic pipe thicknesses to see how it behaves. Further than looking into the source code and contacting helpdesk support, I have not more to offer for tips.

Goodluck,

Jean

Mit freundlichen GrüÃ?en- Sent from my iPhone (excuse the brevity)

i. A.

Jean Marais

b.i.g. bechtold

Tel.   +49 30 6706662-23

On 19.05.2015, at 15:35, "robertogrilloait@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

 

Thank you again for your input!

1) I have following figures: pipe length: 13.1 m. Max water flow rate: 0.15 kg/s =1.5 10^-4 m3/s. Pipe inside diameter: 0.05 m, pipe section 2.0 10^-3 m2. Hence, Max water speed: 0.075 m/s. So I comply with the requirement â??fluid cannot manage to pass through the pipe section within a timestepâ?? for a timestep of 1/20 hour, and the particle would stay in the pipe for three timesteps for a timestep of one minute.

With these timesteps, I do get rid of HVAC convergence warnings. However, the curves of pipe ambient/fluid heat transfer rates still look similar (attached screenshots).

 

2) I am not sure what you mean here? Given the material, the thermal diffusivity of the pipe should not be so high:

 

Material,

                distribution-SHSpace Heating  pipe construction plastic,

                Smooth,

                0.004,

                0.4,

                900,

                1200,

                .9,

                .7,

                .7;

 

Material,

                distribution-SHSpace Heating  pipe construction insulation,

                MediumRough,

                0.016667,

                0.035,

                15,

                1500,

                .9,

                .7,

                .7;

 

Construction,

                distribution-SHSpace Heating  pipe construction,

                distribution-SHSpace Heating  pipe construction insulation,

                distribution-SHSpace Heating  pipe construction plastic;

<pipe-ambient-heat-transfer-rate-timestep-60.PNG>

<pipe-fluid-heat-transfer-rate-timestep-60.PNG>

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Posted by: "jeannieboef@xxxxxxxxx" <jeannieboef@xxxxxxxxx>

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