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Pressure loss coefficients for T-pieces (low Re numbers).mltbx (4.8 MB)

Pressure loss coefficients for T-pieces at low Reynolds numbers

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posted on 31.01.2017, 00:51 by Philip OhneweinPhilip Ohnewein
This Matlab toolbox contains 4 Matlab functions that serve to calculate pressure loss coefficients (zeta values) for 4 different cases (one function for each case). The pressure loss coefficients are relevant for T-pieces (junctions) of round pipes, and are especially interesting for low Reynolds numbers where hardly any reliable information can be found in literature (as of 2015).
Questions, remarks or other input is welcome. Please contact Philip Ohnewein, AEE INTEC (, email
This is a Matlab toolbox - other toolboxes (e.g. Java or Python) are available on request.

Licensing & Citing
This toolbox may be used under the Creative Commons Attribution-ShareAlike 4.0 International Public License (see file _license.txt).
For more information:

How to use the toolbox?
Flow in T-pieces can be combining of dividing. And pressure loss coefficient are calculated for both pipes that meet in the T-piece. A total of four different cases.
This toolbox contains one MATLAB function for each of these 4 cases:
- getComZetas.m    com = combining flow,  s = side pipe
- getComZetast.m   com = combining flow, st = straight pipe
- getDivZetas.m    div = dividing flow,   s = side pipe
- getDivZetast.m   div = dividing flow,  st = straight pipe

The toolbox was created in Matlab 2016a, but should run on older version of Matlab as well (tested on Matlab 2014b). No further MATLAB packages are required to run the functions.
To use the functions, you need not navigate to the containing folder because it is automatically added to the Matlab path.

Inputs & Outputs
All 4 functions require the same inputs. Currently, all functions only work with scalar inputs.
 Re_c [-]  Reynolds number
 QsQc [-]  Ratio of side to common pipe cross section area
 pdp  [mm] Penetration depth = how deep the side pipe protrudes
 Di_S [mm] Inner diameter of common pipe
 Di_A [mm] Inner diameter of side pipe
 success [boolean]
 errMsg  [string]
 zetaVal [numeric scalar]

The pressure loss coefficients (zeta values) calculated by the above functions are based on empirical measurements in the laboratory of AEE INTEC ( from 2011 until 2014 within the research project "ParaSol" (Hydraulikdesign von parallelen Kollektormodulen in solarthermischen Großanlagen). The zeta values can be calculated for a wide range of boundary conditions (Reynolds number etc., see inputs section above). All results are for T-pieces with an angle of 90° between the pipes.

Details about the experimental setup, evaluation, validation and neural-network-modelling of the original pressure loss data can be found in the final report of the ParaSol project which comes packaged with this toolbox.



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