Experimental study of paper drying with direct-contact ultrasound mechanism

A systematic-study is conducted using an innovative technology for paper drying by applying ultrasound mechanism. The advantages include greater energy efficiency, lower drying time and temperature, improvement of the product quality, and it is considered a green technology. The effects of initial moisture content, thickness, and refining condition are studied for different types of pulps (hardwood and softwood) using 2(3) factorial design of experiments. Analysis of Variance show that in the range of the studied parameters, thickness has the maximum effect on ultrasonic drying time followed by the initial moisture content. In addition, using a linear regression model, a relationships for the total time of drying is provided. The results confirmed that ultrasonic drying is more efficient at higher moisture content and higher thickness of the sample. These results are related to the structural characteristic of the samples such as porosity, pore distribution, and surface roughness.