tailieunhanh - Modeling Tools for Environmental Engineers and Scientists Episode 6

Tham khảo tài liệu 'modeling tools for environmental engineers and scientists episode 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | CHAPTER 5 Fundamentals of Engineered Environmental Systems CHAPTER PREVIEW Applications of the fundamentals of transport processes and reactions in developing material balance equations for engineered environmental systems are reviewed in this chapter. Alternate reactor configurations involving homogeneous and heterogeneous systems with solid liquid and gas phases are identified. Models to describe the performances of selected reactor configurations under nonflow flow steady and unsteady conditions are developed. The objective here is to provide the background for the modeling examples to be presented in Chapter 8. INTRODUCTION CHAPTER 4 contained a review of environmental processes and reactions. In this chapter their application to engineered systems is reviewed. An engineered environmental system is defined here as a unit process operation or system that is designed optimized controlled and operated to achieve transformation of materials to prevent minimize or remedy their undesired impacts on the environment. The application and analysis of environmental processes and reactions in engineered systems follow the well-established practice of reaction engineering in the field of chemical engineering. While both chemical and environmental systems deal with processes and reactions involving liquids solids and gases some important differences between the two systems have to be noted. Environmental systems are often more complex than chemical systems and therefore several simplifying assumptions have to be made in 2002 by CRC Press LLC analyzing and modeling them. The exact composition and nature of the inflows are well defined in chemical systems whereas in environmental systems lumped surrogate measures are used . BOD COD coliform . The flow rates are often constant steady or predictable in chemical systems whereas in environmental systems they are not as a rule. Engineered environmental systems are built up of reactors. A reactor is defined here as any device