Drying of Moist Porous Materials with Innovative Impinging Jet Nozzles

Impinging jets have many applications, including the heating or drying of food, paper, printer’s ink, tissue, textiles, chemicals, film, and the cooling of electrical equipment, turbine, and combustor components. They are also used in glass, metal, and plastics processing. The advantages of impinging jet systems include the ability to control local heat transport rates by varying not only flow rate and temperature, but also geometric parameters such as jet diameter, jet-to-jet spacing, and jet-to-surface distance.

The RJR and SJR nozzles are ideal for drying, heating, cooling, and baking of fragile moist porous materials due to their controllable exerted force on the reattachment surface. The RJR technology has been successfully transferred globally to pulp and paper industry sector. Specifically, RJR nozzles are used in the dryer sections of paper-making machines. Significant enhancements in the drying rates is achieved with these RJR nozzles (e.g., Thiele et al., 1995). Furthermore, the installment of these nozzles in drying section of paper machines eliminates sheet fluttering and allows control of the moisture content within the paper sheet in the cross-direction of the machine. This moisture profiling capability allows the paper sheet reach the desired moisture content of about 5 percent without over-drying which is very energy intensive at this falling drying rate stage.