Dynamic Similarity of Inertial and Gravitational Forces  

For this scale-up method, you keep the Froude Number the same for both vessels.  Sounds easy enough, but what's Fr?  Fr = D*N^2/g    ;     g=gravitational acceleration

Will gravity change for the scaled up vessel?  Is the mixer for use on Earth, Space Station Alpha, or the Mars Colony?  It's probably for use on Earth, so assume gravity doesn't change much.  If g is constant, only the impeller diameter and rotation speed change.

You know the laboratory tank diameter and the rotation speed of the impeller.  You are the engineer who is deciding the scaled up vessel diameter.  You have everything you need.  Knowing the two tank diameters, you know the "scale-up ratio."  Therefore, you can calculate many of the parameters for the full size mixer.

Now you can calculate Re1, Re2, Fr1, and Fr2.   (Re = density*D^2*N/viscosity)

You can use these values and Figure 7.6 to find the Power Number (Np) and the Power (P) of the lab-scale and the full-scale mixer.

Report the power consumption and power per unit volume for both.