Process principle of pulsating vacuum drying oven

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Date: 2025-07-10Read: 7

The process principle of pulsating vacuum drying oven is an efficient drying technology that combines vacuum environment, pressure pulsation cycle, and indirect heating, especially suitable for materials that are heat sensitive, easily oxidized, or difficult to dry. The core process can be summarized as the following key steps:

1. Vacuum establishment (initial depressurization)

Principle: Firstly, the air inside the drying box is pumped out by a vacuum pump to create a low-pressure environment.

Function:

Reduce the boiling point of water, allowing the moisture in the material to evaporate rapidly at lower temperatures (to avoid damaging the thermosensitive components at high temperatures);

Reduce oxygen content to prevent material oxidation and deterioration;

Create a low-pressure environment to accelerate the migration of moisture from the interior to the surface of the material.

2. Indirect heating (heat conduction drying)

Principle: Steam/thermal oil is introduced into the interlayer or heating plate of the box, and heat is indirectly transferred to the material through the metal wall surface (the material does not directly contact the heat source).

Function:

Provide evaporative heat to vaporize water;

Uniform and gentle heating method reduces the risk of local overheating;

Temperature controllable (usually 40 ° C-80 ° C), suitable for thermal sensitive material requirements.

3. Pulse cycle (core link)

Principle: During the drying process, alternate the cycle operation of "vacuuming → filling with inert gas (such as nitrogen)" (i.e. "pressure pulsation"):

Vacuum stage: Extract water vapor and residual gas from the box, reduce partial pressure, and enhance water evaporation;

Inflation stage: Inject dry nitrogen/clean air to break the vacuum state.

Function:

Breaking the gas barrier layer: Injecting gas to destroy the static vapor layer on the surface of the material, accelerating the diffusion of internal moisture;

Strengthening heat and mass transfer: Pressure changes cause the internal pores of the material to repeatedly expand/contract, opening up channels for water migration;

Avoid crusts: prevent the surface of the material from quickly losing water and hardening, which hinders the escape of internal moisture;

Uniform temperature and humidity: Gas flow promotes uniform distribution of temperature and humidity inside the box.

4. Dehydration and endpoint determination

Moisture is continuously discharged from the box through a vacuum pump;

The drying endpoint is usually determined by temperature/pressure stabilization or weighing method (constant weight of the material indicates completion of drying).

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