THERMOSYPHON ANALYSIS USING THE PARTICLE IMAGE VELOCIMETRY METHOD (PIV)

Thermosyphons are devices used to transfer heat from a hot to a cold source beneting the eect of gravity. They consist of three main parts, namely, evaporator, condenser and adiabatic section. Working uid absorbs heat from the heat source and delivers it to the condenser section and releases it into the environment. Thermosyphones are able to transfer heat between the heat sources and sinks. Due to the high latent heat of the working uid, thermosyphones can transfer huge amounts of energy. Therefore, they are considered one of the best heat transfer devices. They are widely used in various industrial elds, such as in solar systems, microelectronic devices, CPU cooling and air conditioning. Most researchers in this eld focus only on heat transfer characteristics, and, due to practical considerations, rarely consider their hydrodynamic specications. Indeed, the hydrodynamic characteristics of thermosyphones considerably aect their performance. In this paper, the velocity prole in the liquid phase is determined via a particle image velocimetry technique (PIV). For this purpose, a typical thermosyphon has been designed and constructed with transparent up riser and down-comer sections. In this study, a circular thermosyphon is analyzed and water is used as a working uid in the circular thermosyphon. At the beginning, the velocity eld of the liquid phase is detected in the transparent thermosyphon using a high speed camera and an image processing technique. Subsequently, these pictures are used to generate the velocity proles and are combined with theoretical analyses to evaluate the performance of the thermosyphon. The results are compared with numerical investigations and show good consistency. The results indicate that the particle image velocimetry (PIV) truly determines the hydrodynamic and thermal characteristics of the thermosyphones. Moreover, in this study, the eect of input heat and the inclination angle of the thermosyphon are investigated numerically. It has been shown that the maximum eciency of thermosyphon is in a horizontal position.