The effect of flexible tube vibration on pressure drop and heat transfer in heat exchangers considering viscous dissipation effects |
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Authors: | H Shokouhmand F Sangtarash |
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Institution: | (1) Department of Mechanical Engineering, Faculty of Engineering, University of Tehran, Tehran, Iran |
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Abstract: | The pressure drop and heat transfer coefficient in tube bundle of shell and tube heat exchangers are investigated considering
viscous dissipation effects. The governing equations are solved numerically. Because of temperature-dependent viscosity the
equations should be solved simultaneously. The flexible tubes vibration is modeled in a quasi-static method by taking the
first tube of the row to be in 20 asymmetric positions with respect to the rest of the tubes which are assumed to be fixed
and time averaging the steady state solutions corresponding to each one of these positions .The results show that the eccentricity
of the first tube increases pressure drop and heat transfer coefficients significantly comparing to the case of rigid tube
bundles, symmetrically placed. In addition, these vibrations not only compensate the effect of viscous dissipations on heat
transfer coefficient but also increase heat transfer coefficient. The constant viscosity results obtained from our numerical
method have a good agreement with the available experimental data of constant viscosity for flexible tube heat exchangers. |
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Keywords: | |
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