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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-474-8

ISBN Online: 978-1-56700-473-1

International Heat Transfer Conference 16
August, 10-15, 2018, Beijing, China

EFFECT OF VARIOUS NANOFLUIDS ON THERMAL PERFORMANCE OF THE THERMOSYPHON

Get access (open in a dialog) DOI: 10.1615/IHTC16.hte.021821
pages 5173-5180

摘要

The two-phase closed thermosyphon is among the most efficient heat transfer devices being studied currently. Despite simple construction (straight tube containing evaporator, adiabatic, and condenser section), the underlying thermodynamics of occurring processes is complex. Even more so if the working fluids are two-phase suspensions of nanoparticles in a base fluid, i.e. nanofluids. The investigation of a thermosyphon filled with several water-based nanofluids: two gold (PVP and KOH stabilized), single-wall carbon nanohorns (SDS stabilized), and silica (KOH stabilized) is presented here. We found that both compounds, i.e. nanoparticles and surfactants used to stabilize the fluid, independently affect the thermal behavior of the device. Degree and intensity of the influence depend on the type of nanofluid, the heat load, and the operating conditions. The largest decrease of thermal resistance manifested itself at the lowest heat fluxes. We connect this effect to the deposition of nanoparticles on the surface of evaporator section. The increase of heat transfer performance was highest for the silica nanofluid. For high heat loads, the amount of transferred heat is almost the same for all tested fluids. No effects caused by nanofluids are found at the condenser surface. Some nanofluids prevent thermal instabilities (geyser boiling) occurring in the thermosyphon. This effect is caused mainly by the employed surfactant, which acts as a tenside and affects bubble formation. Even if it does not improve overall thermal performance of the device, it reduces the mechanical load of the thermosyphon.