Heat and Mass Transfer

, Volume 52, Issue 12, pp 2687–2695 | Cite as

Effect of bend separation distance on the mass transfer in back-to-back pipe bends arranged in a 180° configuration



The mass transfer to turbulent flow through back-to-back pipe bends arranged in a 180° configuration with different lengths of pipe between the bends was measured using a dissolving gypsum test section in water. The measurements were performed for bends with a radius of curvature of 1.5 times the pipe diameter (D) at a Reynolds numbers of 70,000 and Schmidt number of 1280. The maximum mass transfer in the bends decreased from approximately 1.8 times the mass transfer in the upstream pipe when there was no separation distance between the bends to 1.7 times when there was a 1D or 5D length of pipe between the bends. The location of the maximum mass transfer was on the inner sidewall downstream of the second bend when there was no separation distance between the bends. This location changed to the inner wall at the beginning of the second bend when there was a 1D long pipe between the bends, and to the inner sidewall at the end of the first bend when there was a 5D long pipe between the bends.


Gypsum Test Section Secondary Flow Sherwood Number Maximum Enhancement 

List of symbols


Initial concentration difference (g/l)


Bulk flow concentration (g/l)


Pipe wall concentration (g/l)


Gypsum diffusivity in water at 25 °C (m2/s)


Pipe inner diameter (m)


Roughness height (m)


Relative roughness


Relative roughness scale


Mass transfer coefficient (m/s)


Length of pipes between pipe bends (m)


Pipe bend radius of curvature (m)


Reynolds number


Schmidt number


Sherwood number


Experimental time (s)


Local distance along a pipe (m)


Streamwise distance from the start of the first pipe bend (m)


Local instantaneous pipe surface wear (mm)


Modified time (s)


Gypsum density (kg/m3)


Pipe circumferential angle (°)


Angle along pipe bend (°)



First pipe bend


Second pipe bend


Downstream pipe


Intermediate pipe



The support of CANDU Owners Group (COG) and the Natural Sciences and Engineering Research Council of Canada (NSERC) is gratefully acknowledged.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  1. 1.School of Mechanical EngineeringNanjing University of Science and TechnologyNanjingPeople’s Republic of China
  2. 2.Department of Mechanical EngineeringMcMaster UniversityHamiltonCanada

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