Agitator Motor Power Calculation

Agitator Power Equation:

\[ P = N_p \rho N^3 D^5 \]

Power Number (N_p):

unitless

Density (ρ):

kg/m³

Rotational Speed (N):

s⁻¹

Impeller Diameter (D):

Power (P):

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1. What is Agitator Motor Power Calculation?

The agitator motor power calculation determines the power required to drive an agitator or mixer in fluid processing applications. It is essential for proper motor selection and efficient mixing system design.

2. How Does the Calculator Work?

The calculator uses the agitator power equation:

\[ P = N_p \rho N^3 D^5 \]

Where:

\( P \) — Power (W)
\( N_p \) — Power number (unitless)
\( \rho \) — Density (kg/m³)
\( N \) — Rotational speed (s⁻¹)
\( D \) — Impeller diameter (m)

Explanation: The power number depends on impeller type and flow regime, while the equation accounts for the strong dependence of power on both rotational speed and impeller diameter.

3. Importance of Power Calculation

Details: Accurate power calculation ensures proper motor sizing, prevents underpowering or overpowering, optimizes energy consumption, and ensures efficient mixing performance.

4. Using the Calculator

Tips: Enter power number based on impeller type and Reynolds number, fluid density in kg/m³, rotational speed in revolutions per second, and impeller diameter in meters. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What is the power number (N_p)?
A: The power number is a dimensionless parameter that characterizes the power requirements of different impeller types under various flow conditions.

Q2: How do I determine the power number?
A: Power numbers are typically obtained from experimental data or manufacturer specifications for specific impeller types and Reynolds numbers.

Q3: What are typical power number values?
A: For standard impellers in turbulent flow: Rushton turbine ~5.0, pitched blade turbine ~1.3-1.5, marine propeller ~0.3-0.6.

Q4: Does fluid viscosity affect power requirements?
A: Yes, viscosity affects the Reynolds number, which in turn affects the power number, especially in transitional and laminar flow regimes.

Q5: How accurate is this calculation?
A: The calculation provides theoretical power requirements. Actual power may vary due to mechanical losses, non-Newtonian fluid behavior, and vessel geometry effects.