A vertical cylindrical tank with a flat roof and bottom is to be const...
10% of tank volume to be kept free as vapour space
90% of tank volume to be used for liquid storage
h →height of tank
r→radius of tank
View all questions of this test
A vertical cylindrical tank with a flat roof and bottom is to be const...
To find the optimum diameter for the tank, we need to consider the cost of materials and fabrication for the tank wall, roof, and bottom, as well as the cost of accessories, piping, and instruments.
1. Calculate the volume of the tank:
Given that 10% of the volume needs to be kept free as vapor space, the actual volume of liquid storage will be 90% of the total volume.
Let V be the total volume of the tank, then the volume of liquid storage is 0.9V.
Given that the volume of liquid storage is 150 m^3, we have:
0.9V = 150
V = 150 / 0.9
V = 166.67 m^3
2. Calculate the surface area of the tank:
The surface area of the tank is the sum of the areas of the wall, roof, and bottom.
Given that the tank is cylindrical, the surface area of the wall is given by:
A_wall = 2πrh
Given that the roof and bottom are flat, their surface areas are given by:
A_roof = πr^2
A_bottom = πr^2
3. Calculate the cost of the tank:
The cost of the tank is the sum of the costs of the wall, roof, and bottom, as well as the cost of accessories, piping, and instruments.
Given that the cost of the wall is Rs 6000 per m^2, the cost of the roof is Rs 2000 per m^2, and the cost of the bottom is Rs 4000 per m^2, we have:
Cost_wall = A_wall * 6000
Cost_roof = A_roof * 2000
Cost_bottom = A_bottom * 4000
Cost_accessories = 0.1 * (Cost_wall + Cost_roof + Cost_bottom)
Total_cost = Cost_wall + Cost_roof + Cost_bottom + Cost_accessories
4. Optimize the diameter:
To minimize the cost, we need to find the diameter that minimizes the total cost.
Since the volume of the tank is fixed, we can express the height h in terms of the diameter d:
V = πr^2h
h = V / (πr^2) = 166.67 / (π(d/2)^2) = 166.67 / (πd^2/4) = 666.67 / (πd^2)
Substitute this expression for h into the equation for the surface area of the wall and simplify:
A_wall = 2πrh = 2π(666.67 / (πd^2)) = 1333.33 / d
5. Substitute the expression for the surface area of the wall into the equation for the cost of the tank and simplify:
Total_cost = (1333.33 / d) * 6000 + πd^2 * 2000 + πd^2 * 4000 + 0.1 * ((1333.33 / d) * 6000 + πd^2 * 2000 + πd^2 * 4000)
Total_cost = (3999.99 / d) * 6000 + 3 * πd^2 * 2000 + 3 * πd^2 * 4000 + 0.1 * ((3999