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Heat Transfer Theoretical Analysis Experimental Investigations and Industrial Systems part 11

Tham khảo tài liệu 'heat transfer theoretical analysis experimental investigations and industrial systems part 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 390 Heat Transfer - Theoretical Analysis Experimental Investigations and Industrial Systems - n V ReRo 2n d2 23 The values of the rotational speed of the ring with minichannels varied between 100 and 534 revolutions per minute. Fig. 11. Influence of the rotation on the limiting current. Rotation caused intensification of the mass transfer process in the minichannel. The limiting current increased with the increase in the minichannel rotational speed. Examples of the voltammograms are shown in Fig. 11. Finally from the measurements the dimensionless mass transfer coefficients Sherwood numbers were calculated. The results are shown in Fig. 12 where the Rossby number rotation number occurs as a parameter. Based on Eqs 9 and 11 the results were obtained in the forms jM 0.31Re-0.48 24 for Ro 0 and jM 1.93Re0.67 25 for Ro 0.1. The electrochemical results were compared with the correlations described by Bieniasz Bieniasz 2010 for rotating short curved minichannels of cross-section varying in shape and surface area along the axis namely jM 0.282Re-0.437 2.48Re-0.732 Ro 26 and jM 0.351Re-0.418 2.20Re-0.703 Ro . 27 Bieniasz gave two correlations 26 and 27 depending on the kind of baffle applied in the test section Bieniasz 2010 . The comparison is shown in Fig. 13. 391 Application of Mass Heat Transfer Analogy in the Investigation of Convective Heat Transfer in Stationary and Rotating Short Minichannels I mA Fig. 12. Influence of rotation on the mass transfer in the circular short minichannel. Re 1 - circular minichannels d 1.5mm Eq. 25 2 - curved minichannels dh 2.36mm Eq. 27 3 - as previously Eq. 26 4 - circular minichannels d 1mm stationary conditions Eq. 24 . Fig. 13. Chilton-Colburn mass transfer coefficients in short rotating minichannels 6. Experimental uncertainties of the major parameters The average relative uncertainties of the complex quantities y y x1 X2 . Xi were calculated according to the general relation Ay y r dy 5 I yy-Axi L Xi 1 2 y2 28 where Axi - the .