Magnetic fluid, tube sealed with the magnetic fluid, and method for preventing snow accumulation using heat pipe or heat siphon constituted by the tube

摘要

PURPOSE:To melt snow on the ground by a heat pipe holding a magnetic fluid which contains a specified amount of metal oxide and which has an extremely large rate of change in magnetization at normal temperature. CONSTITUTION:Minute particles of ferromagnetic metal oxide coated with surfactant are dispersed in organic solvent or water to form a magnetic fluid. This wet magnetic metal oxide has a composition is represented by (MeO)X.(CaO)Y.(ZnO)O.Fe2O3 (Me is Mn, Fe, Co, Ni, Cu, or Mg; and 0.7=X=0.4, 0.02=Y=0.3, 0.3=Z=0.9, 0.8=X+Y+Z=1.5). A tube (a) containing the magnetic fluid is bent to an inverse L shape to form a heat pipe 21. The heat pipe is buried in the ground with its top close to the ground surface GL. A permanent magnet 22 is located near the lower part of the heat pipe. When there is a difference in temperature between the surface and deep part of the ground, the underground heat energy acts on the ground surface to prevent snow covering and freezing according to a magnetic change of the magnetic fluid and the magnetic field by the permanent magnet 22.