GATE 2024 CH – Question 65
Consider a tray-column of diameter 120 cm. Each downcomer has a cross-sectional area of 575 cm$^2$. For a tray, the percentage column cross-sectional area not available for vapour flow due to the downcomers, rounded off to 1 decimal place, is _____________
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Correct answer: 5.07 to 5.13
Explanation
The column cross-section is $\frac{\pi}{4} \times 120^2 = 11310$ cm². The area of the downcomer is not available for vapour flow (the net area for the vapour is $A_t - A_d$), so the fraction is $\frac{575}{11310} = 0.0508$, that is 5.1%.