Chemical Engineering - Process Equipment and Plant Design - Discussion
Discussion Forum : Process Equipment and Plant Design - Section 1 (Q.No. 19)
19.
To keep the power input constant for a stirred vessel operating under fully developed turbulent flow conditions (constant power number), if the impeller diameter is increased by 20%, the impeller speed should be decreased by a factor of
Discussion:
2 comments Page 1 of 1.
S P said:
5 years ago
How to calculate this? Please explain me.
Omkar ks said:
2 years ago
P = N^3D^5.
N1^3D1^5 = N2^3*(1.2D1)^5 (D2 will be 20% of D1)
divide by 3 in power then.
N1D1^5/3 =N2.*1.2^5/3*D1^5/3.
If we cancel D1 on both sides then,
N1 = 1.2^5/3 N2 (Speed will be decreased)
N1^3D1^5 = N2^3*(1.2D1)^5 (D2 will be 20% of D1)
divide by 3 in power then.
N1D1^5/3 =N2.*1.2^5/3*D1^5/3.
If we cancel D1 on both sides then,
N1 = 1.2^5/3 N2 (Speed will be decreased)
(1)
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