Experimental Research On Heat Transfer Characteristics Of Nanofluids In Screen Heat Pipe

Nano-materials have special properties on the structure, photo-electric, magnetic and chemical peculiarity. Nano-materials used in fluid changed the structure of the fluid, and improved the energy exchange; increased the heat coefficient of the fluid. Therefore, Nanofluids technology, as a new enhanced heat transfer technique in recent years has broad application prospects.An experimental equipment for testing screen heat pipe was set up, In the same filing of 60%, at the different working pressure: 7.45kpa,12.38kpa,19.97kpa and the different Nanofluid concentration: 0%~2%, an experimental study was performed to study the heat transfer characteristics of CuO nanoparticles suspension (nanofluids) in the screen heat pipe. The experimental results show:1) When the concentration was lower than 1.0wt%, heat transfer coefficient and qmax increased with increasing nanoparticle concentration. But after the concentration surpassed the optimal value, heat transfer coefficient decreased and qmax kept steady. The experimental result showed that nanofluid can enhance the heat transfer and increase qmax significantly under subatmospheric pressure. When the pressure was 7.45kpa, heat transfer coefficient and qmax can increase by 250% and 25% respectively.2)The heat transfer coefficient of evaporator increased with the increases of the angle till the angle over 45o. And after that the heat transfer coefficient of evaporator decreased with the increasing of angle. The heat transfer coefficient of condenser is little affected by inclination angle. The heat transfer coefficient of condenser with the angle 90°raise less than 10% to the one with 0°. The qmax of heat pipe increased with the angle increases. Under the pressure of 19.97 kPa, at 1% concentration of CuO nano-fluid, at the angle of 90°,the qmax increased by 48% to the one at the angle of 0°.Nanoparticles suspension as a working fluid can significantly strengthen the heat transfer coefficient and the maximum power of screen heat pipe at low pressure condition. Nanofluid is a potential new kind of working fluid to enhance the heat transfer characteristics of heat pipe with high heat flux.