Masao Fujii

Heat Transfer Performance of a Flexible Looped Heat Pipe Using R134a as a Working Fluid. A Proposal of a Method for Predicting the Maximum Heat Transfer Rate of FLHP.

This paper presents the heat transfer performance of a Flexible Looped Heat Pipe (FLHP) using R 134 a as a working fluid. In our evaluation system, an evaporator and a condenser are connected by long flexible tubes with diameter of 3 mm, and the total piping length of this loop heat pipe system is approximately 7500 mm. We selected porous teflon with effective pore diameter of 2γcw=1.2μm to overcome high gravitational heads. Elevation of the evaporator above the condenser (△H=He-Hc) were changed in 3 conditions ((1) Top heat mode (△H=+1m), (2)Horizontal mode (△H=0), (3)Bottom heat mode ((△H=-1m) considering the terrestrial application and the influence of gravity on the FLHP performance was investigated. FLHP provided high thermal transport capacities over long distances through small cross-sectional flexible tubes comparing with conventional heat pipes.

Enhancement of Natural Convection Heat Transfer from a Vertical Heated Plate by Using Inclined Fins

An enhancement technique is developed for natural convection heat transfer from a vertical heated plate with inclined fins, which are attached on the vertical heated plate to isolate a hot air flow from a cold air flow. Experiments are performed in air for inclination angles of the inclined fins in the range of 30 to 90 degrees measured from a horizontal plane, for height of 25 to 50 mm, and for fin pitch of 20 to 60 mm. The convective heat transfer rate for the vertical heated plate with inclined fins at the inclination angle of 60 degree is found to be 19% higher than that for the vertical heated plate with vertical fins. A dimensionless equation on the natural convection heat transfer of the vertical heated plate with inclined fins is presented.