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Research Papers: Porous Media

The Effect of Varying Fiber Characteristics on the Simultaneous Measurement of Heat and Momentum Transfer to Flowing Fiber Suspensions

[+] Author and Article Information
S. N. Kazi

Department of Mechanical Engineering,
Faculty of Engineering,
University of Malaya,
Kuala Lumpur 50603, Malaysia
e-mail: salimnewaz@um.edu.my;
salimnewaz@yahoo.com

G. G. Duffy

Professor Emeritus
Department of Chemical and
Materials Engineering,
School of Engineering,
University of Auckland,
Private Bag 92019,
Auckland, New Zealand
e-mail: gg.duffy@auckland.ac.nz

X. D. Chen

Professor
Suzhou Key Lab of Green Chemical Engineering,
School of Chemical Engineering and Environmental Engineering,
College of Chemistry, Chemical Engineering and Material Science,
Soochow University, Jiangsu Province, China
e-mail: xdchen@suda.edu.cn

Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF HEAT TRANSFER. Manuscript received December 4, 2013; final manuscript received September 11, 2014; published online October 28, 2014. Assoc. Editor: Wilson K. S. Chiu.

J. Heat Transfer 137(1), 012601 (Oct 28, 2014) (9 pages) Paper No: HT-13-1619; doi: 10.1115/1.4028706 History: Received December 04, 2013; Revised September 11, 2014

Heat transfer and pressure loss measurements were obtained simultaneously for a range of wood pulp fiber suspensions flowing in a pipeline. Data were obtained over a selected range of flow rates and temperatures from a specially built flow loop. It was found that the magnitude of the heat transfer coefficient was above water at equivalent experimental conditions and at very low fiber concentrations, but progressively decreased until it was below water at slightly higher concentrations. Similar trends were obtained for the pressure drop measurements obtained simultaneously, showing good correspondence between the two sets of data. It was found that both heat and momentum transfer are affected in a closely similar way by varying fiber properties, such as fiber length, fiber flexibility, fiber chemical and mechanical treatment, the variation of fibers from different parts of the tree, as well as the different pulping methods used to liberate the fibers from the wood structure. Drag reduction increased and heat transfer coefficient decreased with increasing fiber flexibility as found by previous workers.

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References

Figures

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Fig. 1

(a) Schematic diagram of the experimental flow loop [14], (b) sectional view of the experimental test section [14]

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Fig. 2

Fanning friction factor f versus Reynolds number Re for water showing experimental and empirical values. Bulk temperature 30 °C and ΔT 15 °C [13].

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Fig. 3

Heat transfer coefficient hc as a function of Reynolds number Re for water showing experimental and empirical correlations. Bulk temperature 30 °C and ΔT 15 °C.

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Fig. 8

Fanning friction factor f as a function of velocity for water and four different fiber concentrations of bleached kraft pulp. Bulk temperature of 30 °C and ΔT 15 °C.

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Fig. 4

Heat transfer coefficient hc as a function of velocity for two separate fiber suspensions runs. Fiber concentration 0.15%, ΔT 5 °C, bulk temperature 30 °C.

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Fig. 5

Frictional pressure drop (ΔP/L) as a function of velocity for two separate fiber suspensions runs. Fiber concentration 0.15%, ΔT 5 °C, bulk temperature 30 °C.

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Fig. 6

Heat transfer coefficient hc as a function of velocity for water and fiber suspensions of five different concentrations of bleached kraft pulp fiber. ΔT 5 °C and bulk temperature 30 °C.

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Fig. 7

Frictional pressure drop as a function of velocity for water and fiber suspensions of four different concentrations of bleached kraft pulp fiber. Bulk temperature of 30 °C and ΔT 15 °C [14].

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Fig. 18

Frictional pressure drop as a function of velocity for water and fiber suspensions of two grades of fibers, EW and LW. Bulk temperature of 30 °C, ΔT 15 °C, fiber concentration of 0.4%.

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Fig. 12

Heat transfer coefficient as a function of velocity for water and fiber suspensions of two grades of TMP. Bulk temperature 30 °C, ΔT 15 °C, fiber concentration of 0.4%.

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Fig. 9

Drag ratio (ΔPsusp / ΔPwater) of fiber suspensions for four different concentrations of bleached kraft pulp. Bulk temperature 30 °C and ΔT 15 °C [14].

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Fig. 10

Heat transfer coefficient as a function of velocity for water, unbleached and bleached kraft pulp fiber suspensions. Bulk temperature 40 °C, ΔT 15 °C, fiber concentration 0.4%.

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Fig. 11

Frictional pressure drop as a function of velocity for bleached and unbleached kraft pulp fiber suspensions. Bulk temperature of 40 °C, ΔT 15 °C fiber concentration of 0.4%.

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Fig. 13

Frictional pressure drop as a function of velocity for water and fiber suspensions of two grades of TMP. Bulk temperature of 30 °C, ΔT 15 °C, fiber concentration of 0.4%.

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Fig. 14

Heat transfer coefficient as a function of velocity for water and fiber suspensions of three different grades of MDF (MDF low, MDF medium, and MDF high). Bulk temperature 30 °C, ΔT 15 °C, fiber concentration 0.4%.

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Fig. 15

Frictional pressure drop as a function of velocity for water and fiber suspensions of three different grades of MDF (low, medium, and high). Bulk temperature 30 °C, ΔT 15 °C, fiber concentration of 0.4%.

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Fig. 16

Fanning friction factor as a function of velocity for water and fiber suspensions of three different grades of MDF (low, medium, and high). Bulk temperature of 30 °C, ΔT 15 °C, fiber concentration of 0.4%.

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Fig. 17

Heat transfer coefficient hc as a function of velocity for water and fiber suspensions of two grades of fibers, EW and LW. Bulk temperature 30 °C, ΔT 5 °C, fiber concentration of 0.4%.

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