Experimental Study on The Effect of Initial Liquid Droplet Size on The Evaporation in a Heterogeneous Droplet

In the present work, we experimentally investigated the effect of initial liquid droplet size on the evaporation in the heterogeneous droplet. Spherical carbon and water were used for particle and liquid droplet comprising the heterogeneous droplet. four initial droplet volumes of 1, 2, 3 and 4 mu l were considered when the diameter of the particle was 5 mm. The heterogeneous droplet was suspended with a rod at 20 cm away from the radiator which surface temperature was fixed to 473 K. Ambient temperature and relative humidity remained 296 K and 40 %, respectively, during the experiment. As the results, the evaporation rate of 4 mu l case increased about 1.8 times compared with that of 1 mu l case. The evaporation rate increased almost linearly with the volume ratio, and that is related closely with the contact surface between particle and water droplet. Contact surface area remained almost constantly with time, whereas it increased with the initial volume of water droplet. The energy from radiator can be accumulated at the contact surface at the side of particle, thereby intensifying the evaporation of water droplet because more heat transfers from particle to droplet through the contact surface. Consequently, the initial volume of liquid droplet is one of the influence factors on the evaporation rate in the heterogenous droplet.