Computational fluid dynamics as a tool for process engineering

Abstract

Modern engineering increasingly employs various computer software to develop products. The use of software to simulate product performance is known as computer-aided engineering (CAE). CAE supports the design process of a product by allowing the analysis of its virtual prototype. The present work concentrates on computational fluid dynamics (CFD) – one of the major CAE tools. Since its first developments in the late 1950s, CFD simulation has become an essential part of the engineering process in a range of industries due to its advantages, such as faster design workflow and lower costs.

The main objective is to bring new knowledge and create novel solutions by applying CFD methods to solving various research and engineering problems. The dissertation consists of four journal publications focusing on a set of problems from the field of process engineering. The importance of utilizing CFD modeling for the design, optimization and investigation of fluid flow systems is demonstrated. The size of the systems varies from macro- to micro-scale.

The first part of the dissertation is concerned with flows in milli- and micro-scale channels. Efficient mixing and heat transfer at milli- and micro-scales are challenging due to the dominance of viscous forces. CFD simulations were carried out to evaluate the mixing efficiency of milli-scale chemical reactors. The simulations enabled studying different channel geometries to determine an optimal design. The reactors were then fabricated using additive manufacturing (AM) technology, and the simulation results were validated experimentally. A process design method based on CFD and AM for milli-scale reactors was thus demonstrated. Further, CFD was also utilized to examine fluid flow and heat transfer in a serpentine microchannel. The analysis indicated the potential for thermal performance improvement. A novel CFD-driven microchannel configuration for heat transfer enhancement was then developed.

The second part is devoted to studying wastewater treatment techniques based on freeze crystallization. Two systems, namely suspension crystallization and layer crystallization, were investigated with the aid of CFD modeling to obtain more comprehensive knowledge about the factors affecting the purification process. The numerical results provided valuable information on the flow conditions that can be used for the optimization of the wastewater purification systems.