A One drawback of the traditional Rushton impeller is that the ratio between aerated and unaerated power consumption falls rapidly with an increased aeration rate. The hydrofoil impeller, typically has a lower power number, but the aerated power consumption falls less rapidly with increasing aeration rate. For stirring speeds close to 300 rpm the ratio between aerated and unaerated power consumption is given in the figure for a Rushton turbine and a Prochem impeller. You are replacing a Rushton turbine in a 100 m reactor (dt = 3 m, ds = 1 m) by a Prochem impeller. Assume that the stirring rate should be maintained the same. a) What diameter of the Prochem impeller will give the same unaerated power consumption as the Rushton turbine? The values of Np for the Rushton turbine and the Prochem impeller are 5.2 and 1.0, respectively. b) How much higher (approximately) will the kLa-value be for the Prochem impeller at an aeration rate of 0.5 vvm under the conditions in problem a, (i.e. the same unaerated power consumption is achieved)? The kLa value for the same specific power input has been found to be identical for the two impeller types. Assume a non-coalescing medium.