Peculiarities Of Heat Transfer From In-line Tube Bundles To Upward Aqueous Foam Flow
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117 - 125
J. Gylys, S. Sinkunas, B. Sundén, I. Gabrielaitiene & T. Zdankus
Four in-line tube bundles with different geometry were investigated for establishing their performance in terms of heat transfer enhancement. Two-phase aqueous foam was used as a coolant. Such coolant was considered, because our previous research showed that large heat transfer intensity may be reached even at small mass flow rate of the foam. Spacing among the centres of the tubes across the first in-line tube bundle was 0.03 m and spacing along the bundle was 0.03 m. In the second case spacing among the centres of the tubes across the bundle was 0.03 m; spacing along the bundle was 0.06 m. In the third case spacing was accordingly 0.06 and 0.03 and in the last case spacing was accordingly 0.06 m and 0.06 m. During an experimental investigation it was determined a dependence of heat transfer intensity on flow parameters. The investigation of heat transfer from the bundle to upward vertical foam flow was provided for three different values of foam volumetric void fractions β=0.996÷0.998. The velocity of the foam flow was changed from 0.14 to 0.30 m/s. The heat transfer coefficient varied from 200 to 2000 W/(m2K) for the above mentioned foam flow parameters. Keywords: in-line tube bundle, aqueous foam, upward flow, heat transfer.
in-line tube bundle, aqueous foam, upward flow, heat transfer.