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The STCW Convention & the Manning Resolution NEED Amendment & Improvement F.R. Chowdhury

Chowdhury F.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2008

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Vol. 2, no. 2

207--211

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Heat transfer characteristics of water in a vertical small diameter tube at sub-atmospheric pressure

Chowdhury F., Kaminaga F.

Archives of Thermodynamics

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2002

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Vol. 23, no 3

43-57

EN

Boiling heat transfer characteristics of water has been experimentally and analytically examined in a vertical small diameter tube, D = 1.45 mm, L = 100 mm at sub-atmospheric pressures of 5, 11, and 22 kPa under natural circulation condition. Distinct S-shape boiling curves with three different slopes: a slope similar to pool boiling at a low heat flux, a negative slope at a medium heat flux and a slope smaller than that of pool boiling at a high heat flux, have been observed. Comparing the experimental vapour flux with the predicted one, the flow regime might have been annular within our experimental range. Pool boiling correlation of Stephan- Abdelsalam and a boiling correlation of Imura, et al. developed for a thermosyphon correlated well the measured data at low and medium heat flux regions. In the region of high heat flux a large boiling heat transfer enhancement is indicated in the form of S-shape curves. Predictions of heat transfer coefficient by conduction through the thin liguid film gave good results in the region of high heat flux.

3

Free convection across air gap between corrugated and flat plates

Chowdhury F., Alam S., Akhanda M., Islam A.

Archives of Thermodynamics

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2002

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Vol. 23, no 1-2

39-53

EN

Natural convection heat transfer across air gap between a lower hot semicircular corrugated plate and an upper cold flat plate has been studied experimentally for a range of corrugation aspect ratio (air gap to the amplitude of corrugation), 3.5 < A < 9.5, inclination angle, 0^0 < 0 < 45^0, and Rayleigh number, 3.4 x 10^4 Ra < 2.0 x 10^6. A corrugation plate has been formed with the multi-semicircular bars. The heat transfer coefficients are found to be a strong function of corrugation aspect ratio, inclination angle and Rayleigh number. The results are compared with the available information in the literature on natural convection and found to be about 10% and 20% higher than those for a gap between vee corrugated and flat plate and between two flat plates, respectively. Finally, a correlation has been developed for this configuration for a range of parameters studied herein.