Effect of particle size and solid holdup on heat transfer performance of a SiC/water three-phase closed thermosyphon

The purpose of this study is to find a kind of appropriate inert solid particles, which is added into two-phase closed thermosyphon (TPCT) to build a new three-phase closed thermosyphon (THPCT), aiming to improve the thermal performance of TPCT. For this purpose an experimental device is designed and built and SiC solid particles are selected as target particles. A range of experimental investigations are carried out by varying solid holdup (5-20%) and heat flux (4.82-19.28 kW·m−2) at the filling ratio (ϕ) of 80%. Three sizes of particles with equivalent diameters (de) of 0.275 mm, 0.325 mm and 0.460 mm are studied, respectively. Experimental results show that adding SiC particles into the TPCT significantly affects the heat transfer performance and the results depend on the particle size. In the domain of the particle sizes considered in the experimental work, the maximum evaporation convective heat transfer coefficient is obtained with de = 0.275 mm. Compared with TPCT with pure water, evaporation convective heat transfer coefficient is improved by up to 6.0%, and overall thermal resistance is reduced by 6.1% at solid holdup εs = 15% and heat flux q = 9.64 kW·m−2, which correspond to 28.9 W·m−2·°C−1 and 0.002 °C·W−1, respectively. In addition, the thermal performance of THPCT is also closely related to solid holdup. There is an corresponding optimal solid holdup under different particle size and heat flux.