Simulation study on evaporation process characteristics of aqueous alumina nanofluid droplets

As a new and efficient energy transport fluid,nanofluids can significantly improve the heat transfer performance of air conditioning heat exchangers.The study on the evaporation characteristics of nanofluid droplets can provide theoretical support for its enhanced heat transfer application in evaporators.The simulation study on the evaporation of nanofluid droplets can save experimental resources and quickly analyse the influence laws of various factors on droplet evaporation.Considering the two evaporation modes of constant contact radius (CCR) and constant contact angle (CCA) in the process of droplet evaporation comprehensively,an evaporation model of nanofluid droplets based on dynamic contact angle is established.The effects of the initial mass fraction of nanoparticles,substrate type and substrate temperature on the evaporation characteristics of droplets during the evaporation process of aqueous alumina nanofluid droplets are simulated.The results show that the larger the nanoparticle initial mass fraction,the more nanoparticles depositing at the three-phase line,the smaller the range of contact radius,the stronger the thermal conductivity of the droplets,and the faster the evaporation rate.The evaporation process of nanofluid droplets on the PDMS substrate includes two modes of CCR and CCA,while only CCR mode exists on the Al substrate.The average evaporation rate of nanofluid droplets on the Al substrate is 2.3 times that of the PDMS substrate.Compared with the initial mass fraction of nanoparticles,the substrate temperature has a more significant effect on the evaporation rate.When the substrate temperature increases by 5 ℃ from room temperature,the average evaporation rates of droplets on the PDMS substrate and Al substrate increase by 33% and 43%,respectively.