Publications (3)2.04 Total impact

  • P. Bernada · S. Stenstrom · S. Mansson ·
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    ABSTRACT: A spin-echo MRI sequence has been employed to measure moisture profiles during the drying of industrial never-dried pulp samples and was able to detect moisture even at very low:moisture content (6%). For the first time, moisture profiles have been measured for pulp samples approximately 2.5 mm thick with a spatial resolution of 0.15 mm under quite severe drying temperatures (up to 87 degrees C). The results highlight strong moisture gradients near the sample surfaces and no classical constant mass flux period, which leads to the conclusion that the evaporation at the surface is never fully compensated by the internal capillary flow during our drying experiments.
    Journal of Pulp and Paper Science 12/1998; 24(12-12):380-387. · 0.68 Impact Factor
  • P. Bernada · S. Stenström · S. Mansson ·
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    ABSTRACT: Due to its real advantages in terms of spatial resolution, the MRI technique has been chosen in order to study the internal moisture in 2.5 mm thick industrial pulp samples. A spin-echo sequence with very short echo-time (TE = 2 ms) has been designed to measure moisture content inside highly hygroscopic materials and was able to detect moisture even at very low moisture content (6%). In order to enhance the spinlattice relaxation process, and thus reduce the total scanning time of an image, the pulp samples were wetted with solutions containing contrasting agents such as copper sulphate. The optimized value of the copper sulphate concentration was finally found to be around 0.5 gL-1. A calibration curve was utilized to transform the signal intensity into moisture content values. A slight curvature probably due to shrinkage effects appears in the calibration curve.
    Journal of Pulp and Paper Science 12/1998; 24(12-12):373-9. · 0.68 Impact Factor
  • L. Nilsson · S. Mansson · S. Stenström ·
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    ABSTRACT: A magnetic resonance imaging method was employed to measure moisture distributions in pulp samples. A calibration experiment shows that, in the range of moisture contents up to 1.4 g water/g dry substance, the MRI signal is linearly proportional to the mass of moisture of the pulp sample. The in-situ drying of a pulp sheet approximately 4 mm thick was then studied. The resolution in the thickness direction was 0.39 mm. It was found that, even at the very low drying rates employed in the present study (the average drying rate was 0.3 kg/m2/h), a gradient in moisture developed across the sheet as drying progressed.
    Journal of Pulp and Paper Science 02/1996; 22(2-2):48-52. · 0.68 Impact Factor