How do you calculate stirrer speed?

How do you calculate stirrer speed?

The stirrer speed depends on the power number according to the definition: P = Np rho N^3 D^5. To calculate the speed you need the net power input. This can be measured inaccurately via the electric power (correction for system friction) or using strain gauges.

How do you scale a bioreactor?

The traditional method for scale-up of a fermentation process involves determining the reactor geometry, impeller speed, and aeration rate of the large-scale bioreactor on the basis of the experimental results of the lab-scale bioreactor.

What is mixing time in bioreactor?

One of the parameters most widely used to characterize stirring in a bioreactor is mixing time, which is defined as the time a liquid needs to be stirred to obtain a specific degree of homogeneity after adding a pulse signal of a tracer.

What is power number of a bioreactor?

It is well-known that the power number is a function of the Reynolds number (i.e. the turbulence) and becomes constant under fully turbulent conditions. The impeller Reynolds number is defined by Eq. 3, where ηL is the liquid viscosity.

How do you calculate tip speed ratio?

The tip speed ratio is given by dividing the speed of the tips of the turbine blades by the speed of the wind – for example if a 20 mph wind is blowing on a wind turbine and the tips of its blades are rotating at 80 mph, then the tip speed ration is 80/20 = 4.

What is meant by tip speed?

Definition of tip speed : the velocity of the outer edge of a wheel or the tip of a propeller.

How do you calculate volume and power?

P/V can be converted from the impeller power number using the following equation: P/V = (Np × p × N³ × d5)/V with Np being the impeller power number, p the density of water (1,000 kg/m³), N the agitation speed (rps), d the impeller outer diameter (m), and V the vessel’s full working volume (m³).

What is oxygen transfer rate in bioreactor?

The oxygen transfer rate (OTR) through an interface is calculated as the multiplicative product of the mass transfer coefficient, the specific transfer area, and the concentration driving force. In a bioreactor for cell cultivation, oxygen is typically supplied by blowing air into the culture medium through a sparger.

How do you calculate mixing time?

Typically, the mixing time is correlated with the specific power input and geometrical parameters, like the vessel diameter, the H/D ratio, the d/D ratio etc. with the following form: tm ~ (P/V)^-1/3*D^2/3*(d/D)^-1/3.

How do you calculate blend time?

For a typical pitched-blade turbine the dimensionless blend time for 99% uniformity is: 6.34 = Blend time x Rotational Speed x (Impeller Diameter/Tank Diameter)^2.3 x (Liquid Level/Tank Diameter)^-0.5 ;as shown in the attached dimensionless equation.

How do you scale tip speed?

Shaft Speed Scaling have to be done based on the Scaling exponent, which depends upon the way of Scale up. 2. Power number….S = ( V2 / V1 ) ^ (1/3).

How is power number calculated?

Power number can be obtained by using the power number curves that are corresponding to the related impellers or calculated by the correlations. The main correlations are the Nagata correlation and Kamei and Himoka correlation to calculate the power number.