Liquid Blend Time Calculator (95% Homogeneity)

Q: What is 95% blend time (θ95) in chemical engineering?

The 95% blend time is the duration required from injecting a miscible tracer or reagent until the concentration fluctuations throughout the entire tank volume stay within ±5% of the final fully blended mean concentration.

Q: Why does blend time scale with (T/D)²?

A larger impeller relative to the tank diameter (higher D/T ratio) drastically shortens the circulation loop path and accelerates mixing. Because the circulation path length scales with tank diameter T and the impeller swept diameter is D, blend time is proportional to (T/D)².

Q: How does fluid viscosity affect blend time in turbulent flow?

In fully turbulent flow (Re > 10,000), fluid viscosity has virtually zero effect on blend time. Macroscopic turbulent eddy diffusion and bulk convective flow dominate mixing rather than molecular diffusion.

Calculate turbulent liquid blending time (θ95) to achieve 95% homogeneity, required turnover count, and complete miscible fluid dispersion duration.

Tank Volume & Agitator Dimensions

Tank Inside Diam T (ft):

Impeller Diam D (ft):

Agitator Speed (RPM):

Target Homogeneity:

Impeller Class & Fluid

Impeller Style:

Liquid Viscosity (cP):

Liquid Blending Results

95% Blend Time (θ95)

-- sec

-- minutes

Dimensionless Time

N · θ95 (Shaft Revolutions)

Tank Turnovers

-- turnovers

Volume circulations

D/T Impeller Ratio: --

Mixing Performance: Fast Blending (< 45 sec)

In turbulent mixing, blend time is independent of fluid viscosity and depends solely on agitator RPM, impeller Power Number, and the D/T tank ratio.

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Frequently Asked Questions

What is 95% blend time (θ95) in chemical engineering?

The 95% blend time is the duration required from injecting a miscible tracer or reagent until the concentration fluctuations throughout the entire tank volume stay within ±5% of the final fully blended mean concentration.

Why does blend time scale with (T/D)²?

A larger impeller relative to the tank diameter (higher D/T ratio) drastically shortens the circulation loop path and accelerates mixing. Because the circulation path length scales with tank diameter T and the impeller swept diameter is D, blend time is proportional to (T/D)².

How does fluid viscosity affect blend time in turbulent flow?

In fully turbulent flow (Re > 10,000), fluid viscosity has virtually zero effect on blend time. Macroscopic turbulent eddy diffusion and bulk convective flow dominate mixing rather than molecular diffusion.