モデルコンデンサによる凝縮熱伝達特性実験

(冷却管材質の影響)

抄録

In this paper, the condensation heat transfer performance on a horizontal bundle of three tubes in a vertical row is investigated experimentally.
In these tube banks with a downward steam flow, the inside of the each tube is cooled by the city water. The condenser tubes of 16.0 mm O.D, and of 1000 mm heat transferring length used here are titanium tubes of 15.4 mm I.D., Albrac tubes of 13.6 mm I.D., sea water resistance stainless steel tubes of 14.4 mm I.D., and composite tubes of 11.8 mm I.D. The composite tube consists of Albrac tube fixed into a stainless steel tube.
For each kind of these tubes, the Reynolds number of cooling water is varied in the range from 1.1×10⁴ to 6.0×10⁴, with the Reynolds number of steam being 496.0, 610.4 and 689.7, respectively. And, the mean air content in the steam is less than 1.62×10^-2 kgf/kgf.
The values for the mass flow rate of condensates, the overall heat transfer coefficients in the model condenser, and the mean heat transfer coefficients on the steam side and on the cooling water side, are compared for each tube bank.
The mean value for the titanium tubes is 7.6% higher, and the mean values for the stainless steel tubes and for the composite tubes are 11.8%, 16.1% lower respectively than the mean value for the Albrac tubes, with respect to the overall heat transfer coefficients within the limits of this experiment.
Now, the overall heat transfer coefficients calculated by the heat flux and the logarithmic mean temperature difference agree well with those calculated by the heat conductivities of the tube materials and the heat transfer coefficients on the steam side and on the cooling water side.