This study investigates the evaporation characteristics of paired sessile droplets on a heated substrate. In particular, the evaporation time and contact line behaviors were analyzed based on the droplet-to-droplet distance and substrate temperature. The contact line behavior and volume variations were visualized using the shadowgraph method. It was observed that the contact diameter and contact angle exhibited similar behavior for both single and paired droplets regardless of the droplet-to-droplet distance and substrate temperature. The paired droplets demonstrated a longer evaporation time than the single droplet due to the vapor accumulation between the droplets. Furthermore, the scaled lifetime, defined as the ratio of evaporation time between paired and single droplets, increased as the droplet-to-droplet distance decreased and decreased as the substrate temperature increased, attributed natural convection.

In this research, a network model was developed to predict combustion instability in an annular gas turbine combustor (GT24) for power generation. The model consisted of various acoustic elements such as several ducts and area changes which could represent a real combustor with a complex geometry, applied mass, momentum, and energy equations to each element. In addition, a one-dimensional network model through a cylindrical coordinate system has been proposed to predict various acoustic modes. As a result of the analysis, the key resonant frequencies such as longitudinal, circumferential, and complex modes were derived from the EV combustor of GT24, and the reliability of the current model was verified through comparison with the 3D Helmholtz solver.

This study analyzes the flow characteristics and sponge ball recovery performance in a ball strainer according to vortex promoter design variables through flow-particle analysis based on actual experiments to derive a method for improving the recovery rate of cleaning sponge balls of CTCS applied to existing power plants. Based on the ball strainer in CTCS used in the power plant, the experiment was conducted by changing the design factor of the improved shape. In addition, flow and particle analysis were performed under the same conditions as the experiment to numerically the flow characteristics and recovery rate in the ball strainer according to the design factor of the vortex promoter. As a result of the study, it was confirmed that the recovery performance was improved by about 3% by changing the design height of the Vortex promoter. And when comparing the difference between maximum and minimum recovery rate, it was found that the effect on the recovery performance increased slightly according to the distance condition compared to the vortex promoter design height condition.

Electric field assisted combustion is a method that reduces instability in lean combustion. In this study investigated the effects of electrode position on propane-air flame characteristic using a ring electrode. Results showed that burning velocity was not affected by electrode position, but positive voltage expanded the flammability limit while negative voltage contracted it. The effect of voltage polarity on the flammability limit decreased as the electrode position increased. Expanding the flammability limit with a positive voltage can reduce NOx emissions.

Amidst the drive towards carbon neutrality, interest in renewable synthetic e-fuels is rising rapidly. These fuels, generated through the synthesis of atmospheric carbon and green hydrogen, offer a sustainable solution, showing advantages like high energy density and compatibility with existing infrastructure. The physical properties of e-fuels can be different from those of conventional gasoline based on manufacturing methods, which requires investigations into how the physical properties of e-fuels affect the fuel injection characteristics. This study performs a comparative analysis between conventional and Fischer-Tropsch (F-T) synthetic gasoline (e-gasoline) across various fuel temperatures, including the cold start condition. The fuel properties of F-T synthetic and conventional gasoline are analyzed using a gas chromatography-mass spectrometry technique and the injection rates are measured using a Bosch-tube injection rate meter. The F-T synthetic gasoline exhibited higher density and kinematic viscosity, but lower vapor pressure compared to the conventional gasoline. Both fuels showed an increase in injection rate as the fuel temperature decreased. The F-T synthetic gasoline showed higher injection rates compared to conventional gasoline regardless of the fuel temperature.

Cold-start emissions are given great importance under the Euro-7 emission standard due to their significant impact on overall vehicle emissions. When an engine is started from a cold state, the combustion process is not yet optimized, leading to higher emissions. Hybrid vehicles, in particular, may face additional challenges, as their engine may remain inactive for extended periods, causing their catalysts to cool down and potentially become less effective in reducing emissions. In the present study, the performance of an electric heater was investigated as a means to enhance the catalyst heating during the start-up time. A simulation tool was utilized to develop a model for the gasoline exhaust aftertreatment system. The result indicates that the heater was able to increase the three-way catalyst temperature to 500℃ in 4 s using 20 kW power. In addition, the implementation of a secondary air supply resulted in reduced temperature overshoot and improved conversion efficiencies.