Analysis of entropy generation and heat transfer performance of nanoliquids in an annular enclosure

Abstract

Natural convection in a sealed cavity with vertical sides that are cooled and newlineheated is a prototype of many industrial applications, such as reactor insulation, newlinecooling of radioactive waste containers, ventilation of rooms, solar energy newlinecollection and dispersion of waste heat in estuaries. Among the finite cavities, newlinean annular cavity formed by two vertical concentric cylinders is an important newlinephysical configuration aptly describing many practical applications. Thermal newlinemanagement becomes one of the major concerns for electronic devices and traditional newlineair cooling techniques fail to meet the requirement and thus different newlinecooling techniques have attracted much attention. Among them, the utilization newlineof a new class of heat transfer fluids, known as nanofluids produced by dispersing newlinenanoparticles in traditional heat transfer fluids has helped in overcoming newlinesuch a drawback. Along with heat transfer, entropy generation minimization newlinealso plays a prime role for the evaluation of quality in engineering applications, newlinebecause generation of entropy leads to loss of system s energy. In this thesis, newlinenumerical simulations have been performed to develop a basic understanding newlineof buoyant flow and entropy generation in a vertical annular geometry under newlinevarious external mechanisms. The prime objective of this thesis is to identify newlinethe situations to maximize the thermal transport and minimize the entropy generation newlinefor a given conditions. For non-uniform thermal distribution along the newlinevertical walls with different phase deviations and amplitude ratios, heat transfer newlineand entropy generation are numerically investigated. Effect of an inclined magnetic newlinefield on convective flow and entropy generation is also analyzed. Entropy newlinegeneration due to double-diffusive convection of nanofluids, effect of enclosure newlinetilt angle and solid circular block placed inside the geometry are also investigated newlineon the control of convective flow and entropy generation.