Fundamental and Applied Studies in Modular and System-Level Novel Drying Technologies

Asar Sarikaya, Munevver Elif

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Fundamental and Applied Studies in Modular and System-Level Novel Drying Technologies

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Industrial drying is critical in manufacturing pulp, paper, food, and chemical products. It requires massive amounts of energy, produces greenhouse gases, can be a limiting factor in throughput and can affect product quality. Therefore, studying innovative drying methods is essential for reaching the next-level manufacturing processes, especially with minimal energy consumption and carbon footprint. For this purpose, novel drying mechanisms have been studied to fill the gaps in knowledge for fundamental understanding and application-based solutions at modular and system levels. The novel drying methods studied in this dissertation are (1) convective air-drying with a special nozzle called slot jet reattachment (SJR) nozzle, (2) ultrasonic (US) drying by removing moisture from the moist, porous media in the form of a mist, (3) drying in the presence of an electrically driven vapor extraction force called dielectrophoresis (DEP) mechanism. First, a new drying model is developed to be able to numerically study porous media with excess water and extend previous drying models’ capabilities. That is because developing next-generation drying technologies (e.g., with US and DEP mechanisms) may require an understanding of removing moisture from a fully saturated porous material with excess water. As a result of this study, a fundamental understanding of heat and mass transfer is provided for a fully saturated porous medium with excess water. Second, US drying is assessed numerically for developing next-generation drying technologies for the paper industry. As a result of this study, the potential impact of an ultrasonic mechanism is shown when they are installed or retrofitted in various places of a dryer section of a paper machine. Third, the isothermal turbulent flow field of the SJR nozzle(s) is studied numerically, where the SJR nozzle(s) are targeted on a moving perforated surface with/without product from above (and below). This work shows the SJR nozzle’s flow characteristics when used for industry applications to dry/bake finite-sized products moving on a mesh-type conveyor belt. In addition, the non-isothermal turbulent flow of arrays of SJR nozzles is studied numerically to understand the interactions of nozzles. It shows how the array and SJR nozzle design influence the flow field and heat transfer performance of the array of SJR nozzles. This study also outputs required convective heat transfer coefficient information to study the SJR nozzles on a broader perspective than modular-level, on a system-level, which is an important step forward to implement various drying mechanisms together. Moreover, a unique experimental set-up called the Smart Dryer is introduced, where the listed novel drying methods and baseline methods (drying with perforated plates and infrared emitters) can be studied in combination with each other on a system-level. In addition, a drying model is uniquely designed for the Smart Dryer, how to model each drying mechanism in the Smart Dryer is outlined, and benchmark results are presented. This study assists with the demonstration of the optimized combination of drying technologies/modules at a pilot scale for various moist, porous media. That’s because the drying model designed for the Smart Dryer can later be used to understand how to combine drying modules to achieve optimized results (i.e., lower energy consumption and drying time) using machine learning algorithms. In other words, the outcome of this study, a system-level drying model, can be used as a physics-based model to develop machine learning/ artificial intelligence algorithms. Additionally, the Smart Dryer is characterized by an oven thermal profiler sensor with perforated plates, infrared emitters and SJR nozzle modules. The preliminary experimental investigation is provided as an appendix.

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