Heat and Mass Transfer

, Volume 54, Issue 3, pp 875–882 | Cite as

Effect of various refining processes for Kenaf Bast non-wood pulp fibers suspensions on heat transfer coefficient in circular pipe heat exchanger

  • Syed Muzamil Ahmed
  • S. N Kazi
  • Ghulamullah Khan
  • Rad Sadri
  • Mahidzal Dahari
  • M. N. M. Zubir
  • M. Sayuti
  • Pervaiz Ahmad
  • Rushdan Ibrahim
Original
  • 73 Downloads

Abstract

Heat transfer coefficients were obtained for a range of non-wood kenaf bast pulp fiber suspensions flowing through a circular pipe heat exchanger test loop. The data were produced over a selected temperature and range of flow rates from the flow loop. It was found that the magnitude of the heat transfer coefficient of a fiber suspension is dependent on characteristics, concentration and pulping method of fiber. It was observed that at low concentration and high flow rates, the heat transfer coefficient values of suspensions were observed higher than that of the heat transfer coefficient values of water, on the other hand the heat transfer coefficient values of suspensions decreases at low flow rates and with the increase of their concentration. The heat transfer were affected by varying fiber characteristics, such as fiber length, fiber flexibility, fiber chemical and mechanical treatment as well as different pulping methods used to liberate the fibers. Heat transfer coefficient was decreased with the increase of fiber flexibility which was also observed by previous researchers. In the present work, the characteristics of fibers are correlated with the heat transfer coefficient of suspensions of the fibers. Deviations in fiber properties can be monitored from the flowing fiber suspensions by measuring heat transfer coefficient to adjust the degree of fiber refining treatment so that papers made from those fibers will be more uniform, consistent, within the product specification and retard the paper production loss.

Keywords

Heat transfer Non-wood pulp fiber Fiber suspension flow Fiber flexibility Bleaching Fiber processing 

Nomenclature

D

Internal diameter of the tube, m

f

Friction factor

hc

Heat transfer coefficient, W/m2. K

l

Length of the tube, m

X

Length of thermocouple tip along the flow direction, m

L

Heated length, m

k

thermal conductivity, W/m. K

Nu

Nusselt number

Pr

Prandtl number

\( \overset{\cdotp }{q} \)

heat flux, W/m2

Re

Reynolds number

T

Temperature, K

u

Velocity, m/s

Greek symbols

λ

Wall thermal conductivity, W/m. K

δ

Distance of thermocouple from the inner surface of pipe

Subscripts

b

Bulk

in

Inlet

out

Outlet

s

Surface

tc

Thermocouple

Notes

Acknowledgements

This research has been financially supported by High Impact Research (MOHE-HIR) grant UM. C/625/1/HIR/MOHE/ENG/45, UMRG RG161-15AET, Bantuan kecil penyelidikan BK 009-2016, Faculty of Engineering, University of Malaya and the authors are also grateful to the Forest Research Institute of Malaysia for support to conduct this research work.

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Copyright information

© Springer-Verlag GmbH Germany 2017
corrected publication October/2017

Authors and Affiliations

  1. 1.Department of Mechanical Engineering, Faculty of EngineeringUniversity of MalayaKuala LumpurMalaysia
  2. 2.Department of Electrical Engineering, Faculty of EngineeringUniversity of MalayaKuala LumpurMalaysia
  3. 3.Pulp and Paper Branch, Forest Research Institute Malaysia (FRIM)KepongMalaysia
  4. 4.Department of PhysicsAbbottabad University of Science and TechnologyHavelian KPPakistan
  5. 5.Department of Chemical EngineeringBalochistan University of Information TechnologyQuettaPakistan

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