Factors affecting the drying quality of veneers

1. Hot air temperature

As the hot air temperature increases, the moisture content gradient, pressure gradient, water vapor diffusion coefficient and moisture conductivity coefficient all increase, and the evaporation rate of moisture in the veneer increases.

In the constant speed drying stage, the drying rate is almost linearly related to the dry bulb temperature or the dry-bulb and wet-bulb temperature difference; in the deceleration drying stage, the effect of the dry bulb temperature on the drying rate is greater than the dry-bulb and wet-bulb temperature difference.

2. Relative humidity of hot air

When the dry bulb temperature is constant, the dry-bulb and wet-bulb temperature difference is large, then the drying rate is large;

The moisture content of the veneer is high, the dry-bulb and wet-bulb temperature difference has a large impact, and vice versa.

When the dry bulb temperature is high, the relative humidity has a small impact on the drying time; when the dry bulb temperature is low, the relative humidity has a large impact on the drying time.

3. Hot air wind speed

For convection dryers, the wind speed is 1 to 2 m/s, and the wind speed exceeds 2 m/s, which has little effect on the drying rate. If the wind speed is increased further, the power consumption will increase greatly.

For the jet dryer, the wind speed must reach 15-20m/s to effectively destroy the critical layer on the surface of the veneer and achieve the effect of increasing the evaporation rate of water.

4. Hot air injection method

The high-speed airflow is sprayed vertically on the surface of the veneer to improve the heat conduction efficiency, accelerate the diffusion of internal water, and shorten the drying time.