Thesis (Ph. D.)--Institute of Paper Chemistry, 1956. / Includes bibliographical references (p. 95-97).

Thesis (Ph. D.)--Institute of Paper Science and Technology, 1986. / Includes diagram of a drying apparatus, p. 14. Bibliography: leaves 102-103.

A pulsating jet generated by a pulse combustor has been experimentally demonstrated as a technique for impingement heat transfer enhancement relative to a steady jet. The enhancement factor was as high as 2.5. Despite such potential, further studies of this technique have been limited, let alone industrial applications. The ultimate goal of the Pulsed Air Drying project at the Institute of Paper Science and Technology is to develop this technique to commercialization for industrial applications such as paper drying. The main objective of the research in this dissertation is to provide a fundamental basis for the development of the technology. Using CFD simulations, the research studied the characteristics of pulsating single-slot-nozzle jet impingement flows and heat transfer on stationary and moving surfaces. In addition, in order to understand basic flow characteristics of pulse-combustor jets, a simplified model of Helmholtz pulse combustors was developed. The model was used to recommend a strategy to generate a pulsating jet having large amplitude of velocity oscillation. And based on this model, pulsating jets in the simulations were characterized as those at the tailpipe exit of a pulse combustor. The impingement conditions were similar to those in conventional impingement hoods for paper drying. Parameter studies included the effects of jet velocity oscillation amplitude, pulsation frequency, mean jet velocity, tailpipe width, and impingement surface velocity. Simulation results showed that the amplitude of jet velocity oscillation was the most important parameter for heat transfer enhancement, in which two mechanisms were identified: high impinging jet velocity during the positive cycle and strong re-circulating flows in the impingement zone during the negative cycle of jet velocity oscillation. As for the improvement by the pulsating jets relative to steady jets, the maximum heat transfer enhancement and energy saving factors were 1.8 and 3.0, respectively, which were very encouraging for further development of the technology.

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2007. / Banerjee, Sujit, Committee Member ; Orloff, David, Committee Member ; Patterson, Tim, Committee Co-Chair ; Ahrens, Fred, Committee Co-Chair.

No description available.

In about 30 years of experiments and development, impulse drying is now considered as a well known technology and a good candidate in the constant effort to save energy in the paper industry. The drying section is indeed the most expensive section in the process of paper production. However, this potential technology has a major disadvantage, stopping its implementation in the industry. Paper, which is a porous material with a variable compressibility, experienced a sudden release of energy at the nip opening during impulse drying. Under these conditions of high intensity process (both in temperature and pressure), the fiber mat has a tendency to delaminate. This web disruption is a critical issue against impulse drying. This thesis comes up with a new approach to the problem. These last years, the technology itself has been addressed in this issue and many improvements have been reached in terms of energy release (heat transfer control, material coating ). The novel idea is then to investigate the inner structure of the paper once it has been coated with starch to a large extent (up to 10 or 20% of the relative basis weight). Starch is known for its large use in industry, but also its capability to expand under high temperature. Hence, both relative strength and bulking effects are investigated in this thesis, using numerous experiments with variable temperatures and pressures, along with ultrasonic testing and image analysis. We have the opportunity to appreciate the phenomenon of heat transfer and mass transport in the coated medium, while reaching promising results in terms of strength and bulk. These are finally investigated using scanning electron microscopy as a first step toward a pore expansion model for starch imbued handsheets.

This specific-purpose mathematical model was developed for the drying process in a multi-cylinder drying section. The unsteady state of one-dimensional heat conduction equation has been applied to mathematical model of both, cylinder shell and paper web. The internal mass transfer of the paper web has not been included in this work. The calculations of the simulation program use an implicit numerical method. The drying path length along the machine direction has been divided into 4 drying phases for each drying cylinder. Each drying phase has been divided in small sub-elements. In each sub-element, the heat and mass transfer across boundary conditions have been solved simultaneously in the simulation program, which runs with MatLAB®.

This specific-purpose mathematical model was developed for the drying process in a multi-cylinder drying section. The unsteady state of one-dimensional heat conduction equation has been applied to mathematical model of both, cylinder shell and paper web. The internal mass transfer of the paper web has not been included in this work. The calculations of the simulation program use an implicit numerical method. The drying path length along the machine direction has been divided into 4 drying phases for each drying cylinder. Each drying phase has been divided in small sub-elements. In each sub-element, the heat and mass transfer across boundary conditions have been solved simultaneously in the simulation program, which runs with MatLAB®.