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Free Engineering Tool

Vacuum Drying Time Calculator

Estimate how long a jacketed mixer/dryer will take to dry your product — from bulk density, moisture content, product temperature limit and vacuum level. Built on contact-drying heat-transfer physics (U·A·ΔT/λ), the same first-pass calculation our applications engineers use before a trial.

Inputs · Your Product & Machine

Estimate Your Drying Cycle

The Physics

How This Calculator Works — And Where It Stops

Contact drying is heat-transfer limited: water leaves as fast as the jacket can push heat into the bed. The evaporation rate is U · A · ΔT / λ — the wall heat-transfer coefficient, the heated area, the temperature difference between your product limit and the boiling point at the operating pressure, and the latent heat of vaporisation. Vacuum wins because it moves the boiling point: at 30 mbar water boils near 24 °C, so even a 60 °C product limit leaves a strong driving force.

What It Models

Sensible heat-up, constant-rate drying at the boiling point, and a falling-rate tail below ~8% moisture at reduced flux. Heated area scaled from vessel volume; wall coefficients from agitated vacuum-dryer practice (60–125 W/m²K).

What It Can't Know

Your material's critical moisture, bound-water behaviour, stickiness through the drying curve, foaming, and vapour-line limits. These move real cycles ±30–50% against any calculation — ours or anyone's.

How We Close the Gap

A pilot trial measures your actual drying curve — evaporation rate, endpoint, product temperature profile — and the measured cycle is written into the machine order as acceptance criteria.
FAQ

About This Estimate

How accurate is the drying time estimate?Treat it as an engineering estimate within roughly ±30–50%. The heat-transfer physics is well established, but material-specific behaviour — critical moisture, bound water, stickiness — can only be measured, not calculated. That is what the pilot trial is for.
Why does "no vacuum" show such a long time?Below 100 °C at atmospheric pressure, water cannot boil — drying relies on purge-gas humidity gradients and is typically 3–10× slower than boiling under vacuum. If your product cannot tolerate high temperature, vacuum is not an option; it is the process.
Which mixer geometry does this assume?A jacketed agitated vessel with wall area scaled from volume — representative of ribbon, paddle and plow vacuum dryers. Tumble dryers (double cone, V-blender) run at similar flux per area; the heated-agitator option models hollow-shaft executions that add up to 45% area.

The Calculator Estimates. The Trial Proves.

Send us the material, the solvent and the target moisture — we'll run your product on a pilot machine and quote a cycle time we'll warrant at FAT. Book a Pilot Trial