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.
