Transport phenomena in enclosed porous cavities

Abstract

Natural convection within enclosures filled with porous media has been studied extensively during the past two decades because of its widespread engineering applications, including geothermal systems, underground spread of pollutants, storage of nuclear waste materials, solidification of casting, thermal insulation, electronic cooling, petroleum reservoir modeling, burying of drums containing heat generating chemicals in the earth, design of chemical catalytic reactors, powder metallurgy, ceramic engineering, and food and medical industries. Natural convection in porous cavities is widely applied in engineering and therefore getting accurate results for a system is very important to the design of such a system. The problem of natural convection in a porous annulus among horizontal cylinders has important applications to thermal insulation engineering and energy storage system. Most of the early theoretical studies on this problem assume that the horizontal cylinders are concentric and that Darcy's law is applicable. In practical applications, two objectives are required for thermal insulation engineering––namely, (1) to prevent heat loss from a pipe that is transporting heated fluid, (2) to prevent heat input to a pipe thatis transporting cooled fluid. The chapter also discusses the problem of transient natural convection in a porous annulus between concentric and eccentric horizontal cylinders at uniform, but different, temperatures.