.Buildings.Obsolete.Fluid.FixedResistances.PlugFlowPipe

Information

Pipe with heat loss using the time delay based heat losses and transport of the fluid using a plug flow model, applicable for simulation of long pipes such as in district heating and cooling systems.

This model takes into account transport delay along the pipe length idealized as a plug flow. The model also includes thermal inertia of the pipe wall.

Implementation

Heat losses are implemented by Buildings.Fluid.FixedResistances.BaseClasses.PlugFlowHeatLoss at each end of the pipe (see Buildings.Obsolete.Fluid.FixedResistances.BaseClasses.PlugFlowCore). Depending on the flow direction, the temperature difference due to heat losses is subtracted at the right fluid port.

The pressure drop is implemented using Buildings.Fluid.FixedResistances.HydraulicDiameter.

The thermal capacity of the pipe wall is implemented as a mixing volume of the fluid in the pipe, of which the thermal capacity is equal to that of the pipe wall material. In addition, this mixing volume allows the hydraulic separation of subsequent pipes. Thanks to the vectorized implementation of the (design) outlet port, splits and junctions of pipes can be handled in a numerically efficient way.
This mixing volume is not present in the PlugFlowCore model, which can be used in cases where mixing volumes at pipe junctions need to be added manually.

Assumptions

• Heat losses are for steady-state operation.
• The axial heat diffusion in the fluid, the pipe wall and the ground are neglected.
• The boundary temperature is uniform.
• The thermal inertia of the pipe wall material is lumped on the side of the pipe that is connected to ports_b.

References

Full details on the model implementation and experimental validation can be found in:

van der Heijde, B., Fuchs, M., Ribas Tugores, C., Schweiger, G., Sartor, K., Basciotti, D., Müller, D., Nytsch-Geusen, C., Wetter, M. and Helsen, L. (2017).
Dynamic equation-based thermo-hydraulic pipe model for district heating and cooling systems.
Energy Conversion and Management, vol. 151, p. 158-169. doi: 10.1016/j.enconman.2017.08.072.

Revisions

• July 12, 2021, by Baptiste Ravache:
  This class is obsolete and replaced by Buildings.Fluid.FixedResistances.PlugFlowPipe.
  This is for IBPSA, #1494.
• April 14, 2020, by Michael Wetter:
  Changed homotopyInitialization to a constant.
  This is for IBPSA, #1341.
• March 6, 2020, by Jelger Jansen:
  Revised calculation of thermal resistance R by using correct radiuses. See #1310.
• October 23, 2017, by Michael Wetter:
  Revised variable names and documentation to follow guidelines. Corrected malformed hyperlinks.
• July 4, 2016 by Bram van der Heijde:
  Introduce pipVol.
• October 10, 2015 by Marcus Fuchs:
  Copy Icon from KUL implementation and rename model. Replace resistance and temperature delay by an adiabatic pipe.
• September, 2015 by Marcus Fuchs:
  First implementation.