Heat generation from the electronic components is increasing continuously with increase in number of junctions. Conventional method of heat management such as forced air cooling, heat pipes etc. are not capable of removing high heat flux from the next generation electronic devices. Therefore, development of heat transfer enhancement techniques is essential to alleviate the problem due to ever-increasing heat generation in electronic components. Liquid based thin film evaporative cooling systems can be a suitable candidate to tackle such high heat flux systems [1, 2]. Thin film evaporative cooling has an advantage over the two-phase boiling heat transfer systems as latent heat of vaporization can be utilized below the normal boiling point. This can avoid the difficulties associated with large pressure drop and flow instabilities. No significant temperature change is observed in liquid vapor mixture during phase change process leading to small temperature difference. The coolant requirement is also low in an evaporation-based cooling system due to utilization of latent heat of vaporization resulting in lower overall coolant mass requirement of the system. Hence, thin film-based evaporation cooling systems are ideal for aerospace and space applications.
Evaporation of liquid has potential applications in several fields such as electronic cooling, biological lab on chip applications, thin-film evaporative cooling, drying, painting, etc. This phenomenon has been studied extensively for almost half a decade. Narayan et al  studied gas-assisted thin-film evaporation from confined spaces for the thermal management of hot spots with local heat flux exceeding 600 W/cm2. Eloyan and Zaitsev  studied the evaporating thin layer of liquid film, moving under the action of the gas flow in a flat channel. This system was able to remove heat flux of the order of 1 kw/cm2. Several aspects of the evaporation process such as substrate properties, liquid properties (Single, binary, or nanofluid), heated/non-heated surface, and effect of ambient conditions such as relative humidity have been studied . Vapor phase transport in the gas phase was studied to explore the vapor concentration driven evaporation phenomenon [4–9]. Further research is required to understand the gas-phase transport physics for exploring the possibility of minimizing mass transfer resistance for enhancing the potential of thin film evaporation-based cooling system.
Application of electrohydrodynamic (EHD) is one of the approaches to enhance thin film evaporation process. Electrohydrodynamics has shown great success in the applications of fluid flow, convection, boiling and condensation heat transfer with the advantages in cost saving and environmental friendliness [10, 11]. Vancauwenberghe et al  reviewed the existing literature on the influence of electric field on contact angle, shape, and enhancement of evaporation rate of sessile drops. Takano et al [13–16] investigated the evaporation of sessile droplet above the Leidenfrost point under the applied voltage varying from 0 to 2000 V, where the droplet is in contact with the electrode and substate is non conducting. The applied voltage was set at 300 V and the substrate temperature was set at 300°C for ethanol and cyclohexane and 400°C for water. Maximum enhancement rate (which is defined as the ratio of evaporation time with electric field to the evaporation time without electric field) for ethanol, cyclohexane and water were equal to 20, 1.3 and 3 respectively. In subsequent study ethanol and R113 were studied with maximum applied potential equals to 200 V and 2000 V respectively. The maximum enhancement rate achieved were 7.6 and 2.8 for ethanol and R113, respectively . Authors qualitatively observed that the effect of electric field on non-polar liquids is lower compared to that of polar liquids. This may be attributed to the larger charge relaxation time for former. To further investigate the matter, author studied the critical voltage and response time necessary to render the surface instability of horizontal free surface of non-polar liquid with long relaxation time. They concluded that response time for the surface instability at some critical voltage is shorter than the charge relaxation time [14, 15]. Bateni et al.  studied the effect of electric field on contact angle and surface tension of the sessile droplets. Droplet is placed within the parallel plate capacitor arrangement and electric field is applied between electrodes. They observed increase in the contact angle of polar liquids such as alcohols. However, no significant change is observed in the non-polar liquids such as alkanes with increase in the electric field. Stronger change in contact angle is observed for liquids with long molecules. Polarity of the electric field is not found to be an underlying factor.
Deng et al.  studied the charged droplet impact and evaporation on a conducting substrate produced by electro spraying of ethanol. They concluded that image force experienced by the droplet plays significant role on the post impact history if sufficient residual charge is available in the droplet after impact. If substrate temperature remains at or above boiling point, then this image force prevents the rebound and lead to the flattened sessile droplet which increases the evaporation rate. When substrate temperature reaches above the Leidenfrost point, image force prevents the bouncing of the droplet from the surface. Scaling analysis revealed that the advantage of image force in case of charge droplet does not always helps in preventing the rebound. It is only useful for smaller size pico liter droplets not for larger, nano liter droplets.
Gibbons et al  studied the local heat transfer effect of a sessile droplet placed on a heated substrate under a static electric field. The electric field strength is varied as 0, 5, 10 and 11 kV/cm. With increase in the electric field, decrease in the contact angle is observed while cooling profile, peak convective heat flux, and the radial location of this peak are independent of the applied electric field. Fan et al  studied the evaporation of charged droplets with different electrical conductivity on the hydrophobic substrate. Droplet is placed between 2 parallel plate electrodes where lower electrode is hydrophobic, and voltage is applied at lower electrode and upper electrode is grounded. They observed increase in evaporation rate with increase in applied electric field and evaporation of charged droplet can be divided into two stages: the stationary and accelerated stage. At the same applied voltage evaporation time of water droplet is almost double compared to the hydrochloric acid (HCl) droplet.
Xu et al  studied the water droplet evaporation on heated Teflon coated copper surface in the presence of non-uniform electric field generated by needle and plate configuration. They observed that both increase in external electric field strength and surface temperature enhance droplet evaporation with a maximum enhancement ratio of 6.8. Enhancement in evaporation is attributed to the mechanism of non-uniform electric field due to corona wind blowing, surface tension weakening and molecular orientational alignment. External convection produced by the corona wind is a promising enhancement method in drying applications due to its lower energy consumption [22–24]. The mechanism of this enhancement is attributed to a secondary flow induced by the electric body force. When a high electric field is maintained between two electrodes with dissimilar curvature (i.e., one is sharp and the other is blunt), air molecules near the sharp electrode become ionized. The ions are accelerated under the intense electric field and move towards the collecting blunt electrode. This migration leads to further collision between ions and neutral air molecules, transferring momentum from ions to neutral air molecules. A bulk of air flow is thus created, which is customarily called ionic wind or corona wind . Bin et al  studied the effect of external horizontal air flow on the evaporation of methanol droplets of different radius placed on the Teflon surface. The evaporation rate increases with increase in air velocity.
The above literature review shows that most of the studies performed till date on the effect of electric field on droplets are mainly focused on electrowetting phenomenon where droplet is placed on a non-conducting substrate. Two configurations are primarily used. In one configuration, a needle electrode is in contact with the droplet placed on a non-conducting substrate. In the other configuration droplet is placed between two parallel plates of a capacitor and the plate on which droplet is placed is kept insulated. It is observed that presence of electric field increases the wettability and anchors the shape of a droplet. Lower contact angle leads to higher evaporation rate.
From the above literature review, it can be concluded that effect of non-uniform electric field induced corona wind on the evaporation of a volatile and non-polar hydrocarbon of microliter volume cavities is not available in literature. The understanding of thin film evaporation phenomenon and vapor phase transport under the effect of external flow is also not well understood. Therefore, the present study investigates the effect of corona wind induced external convection on the evaporation and vapor phase transport of heavy hydrocarbon (cyclohexane) from a microliter circular well cavity. Digital holographic interferometry and particle image velocimetry have been used for characterization of concentration and velocity field respectively. Vapor cloud of liquid evaporating from the well cavity under the influence of corona jet is compared to the natural evaporation case to understand the physics of mass transfer in the presence of external convection.