Thermographic Observation of High-Frequency Ethanol Droplet Train Impingement on Heated Aluminum and Glass Surfaces

The present study investigates thermal gradients on the heated aluminum and glass surfaces during ethanol droplet train impingement in the surface temperature ranges of 140°C–240°C. The ethanol droplet impingement is applied with an incline of 63 degrees and the droplet diameter is 0.2 mm in both aluminum and glass surface experiments. Thermal gradients are observed with a thermographic camera. Compared to the glass, the aluminum surface has very small liquid accumulations and better evaporation performance thanks to its higher thermal conductivity. Low thermal conductivity of glass results in higher thermal gradients on the surface. The droplet impact area on the aluminum surface is extremely smaller than the impact area on the glass surface. It is found that the liquid accumulation area is not symmetrical like horizontal droplet train impingement studies as the inclined flow propagates the ethanol flow through its flow direction. Also, the droplet train impact area decreases by rising the surface temperature because higher temperature values achieve greater surface energy levels that accelerate the evaporation rate.