A new type of heat pipe called roll heat pipe (RHP) is considered in this study. In RHP, the evaporator and the condenser are separated in the radial direction, and the energy is moved in radial direction. RHP is composed of two concentric annular pipes of unequal diameter, wick structure, and bridge wicks, which provide the return path of the working fluid to evaporator. A heat source is inserted in the inner pipe, which works as the evaporator region. RHP can be applied as heat roll in the laser printers or copy machines where isothermal heating as well as rapid response is desired. Three RHP samples are fabricated and tested in this work. They differ in the number of bridge wicks and inner tube diameter. The length of all samples is 300 mm. In this paper, the transient thermal characteristics of RHP samples are investigated experimentally and compared with numerical analysis results. Also, the effects of fill charge on the performance of RHP samples are studied. By using infrared thermography camera, we observed that the level of temperature uniformity on the outer surface of heat roll is very good in comparison with real heat roll.
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