▎ 摘　　要

A novel hybrid nanofluid is prepared, and its effects on the heat transfer performance of flat rectangular loop heat pipe are experimentally investigated for possible application in cooling of electronic devices. The hybrid nanofluid is prepared by dispersing copper nanoparticles and graphene nanoplatelets in water using ultrasonication and addition of surfactant Cetyl trimethyl ammonium bromide. The copper nanoparticles have a mean diameter of 30-50 nm, and graphene nanoplatelets have a particle diameter of less than 2 microns. Hybrid nanoparticles of copper-graphene nanoplatelets of two mass ratios, namely 30:70 and 70:30, are prepared, and water-based hybrid nanofluids are prepared with both the ratios of nanoparticles having a volume fraction of 0.01% and 0.02%. The temperature responses are measured for 0.01% and 0.02% volume concentrations of copper-graphene nanoplatelets hybrid nanofluids over a wide range of heat loads (40-320 W) and with a filling ratio of 33% of the working fluid in the loop heat pipe. The hybrid nanofluids in miniature loop heat pipe are found to exhibit 24.42% decrement in thermal resistance with 32.4% higher effective thermal conductivity over water. An enhancement of 7.6% in merit number is observed indicating the higher performance of hybrid nanofluid than that of water. The results show that the capillary limit for hybrid nanofluids increases by 36.97% and a decrement of 9.8% in evaporator wall temperature is observed for 0.02% volume concentration than water. The lowest thermal resistance of 0.1 K W-1 is obtained for 0.02% hybrid nanofluid containing 30:70 copper-graphene hybrid nanoplatelets.