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3 years ago

Doshisha University (Private)

Doshisha University (Private)

Heat transfer properties

Heat transfer properties of magnetic fluids due to natural convection This project researches the magnetic natural convection using temperature-sensitive magnetic fluids that can be controlled using magnetic fields and temperature. In a heat-transport device using temperature-sensitive magnetic fluids, buoyancy and magnetic body forces affect the flow behavior, and strong temperature dependency of magnetization is shown. For this reason, temperature-sensitive magnetic fluids are thought to be ideal for convection in the zero gravity of space or in the low gravity on the surface of the Moon. We are using testing and numerical simulations to investigate the effects of magnetic fields on the heat-transfer properties of temperature-sensitive magnetic fluids. Environmentally friendly energy-conversion systems using natural refrigerant (CO2) Recently, in an attempt to protect the environment, considerable research has been undertaken into energy-conversion systems using natural energy, such as solar and wind energy, to generate electricity. This project uses the boundless energy (heat) of the Sun and uses CO2 as a natural refrigerant to enhance the efficiency of a Rankine cycle system that generates electricity and usable heat. This system uses the carbon dioxide in a supercritical state at high temperature and high pressure. As our understanding of the properties in this supercritical state is still incomplete, we are investigating the properties of supercritical CO2 in addition to research into the overall system. Solar Rankine system using supercritical CO2 Recently, in an attempt to protect the environment, considerable research has been undertaken into energy-conversion systems using natural energy, such as solar and wind energy, to generate electricity. This project uses the boundless energy (heat) of the Sun and uses CO2 as a natural refrigerant to enhance the efficiency of a Rankine cycle system that generates electricity and usable heat. This system uses the carbon dioxide in a supercritical state at high temperature and high pressure. As our understanding of the properties in this supercritical state is still incomplete, we are investigating the properties of supercritical CO2 in addition to research into the overall system. Ultra-low-temperature heat-pump system using CO2 gas-solid two-phase flow Conventional refrigerators use Freon or hydrochlorofluorocarbons as the refrigerant. The destruction of the ozone layer and global warming are becoming increasingly serious, and the refrigerant Freon is one cause of these environmental problems. Research and development is being conducted on natural refrigerants that have a low environmental load. This project undertakes basic research into the fluid-dynamic behavior of a carbon dioxide solid phase formed in liquid carbon dioxide inside a cylindrical heating tube, and its heat transfer properties. In practice, the liquid carbon dioxide undergoes isentropic expansion in an expansion valve and its temperature drops due to the Joule-Thomson effect. As a result of the decrease in temperature, dry ice particles precipitate out and then sublimate and steal heat from the surroundings.

Keywords Group A (Prof. Jiro MIZUSHIMA) Flow stability Chaos Turbulence transition Fluid engineering Combustion fluid engineering Wind-energy power generation Pump Group B (Prof. Hiroshi YAMAGUCHI) Magnetic fluids Gas-solid two-phase flow Mixed-phase flow Supercritical CO2 Lattice Boltzmann Method Heat transport MHD Turbulence Flow analysis / computer simulations Flow calculation Prof. Katsuya HIRATA, Jiro FUNAKI Laboratory of Fluid Mechanics http://istc.doshisha.ac.jp/course/mechanical/labo_32.html