Project ForgePlant Design & Economics
Cost Estimation
GATE 2016
Hard
A cylindrical tank (flat roof/bottom) stores 150m³ ethylene glycol (10% vapor space). Wall cost=Rs.6000/m², roof=Rs.2000/m², bottom=Rs.4000/m², accessories=10% of wall cost. The optimum tank diameter (m) is
- A3.5
- B3.9
- C7.5
- 7.8
Explanation
Total volume needed=150/0.9=166.67m³, H=166.67/(πD²/4). Cost=6600πDH+1500πD² (wall+accessories in series, plus roof+bottom). Substituting H and minimizing over D gives D³≈466.9 ⟹ D≈7.76≈7.8m.
Source: GATE CH 2016 (2016)
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