开敞空间内甲醇蒸发特性研究

This article presents the spatiotemporal evolution characteristics of methanol pool evaporation, obtained through a self-designed experimental platform. It elucidates the influence mechanisms of pool diameter (0. 5 m, 1. 0 m, 1. 5 m, and 2. 0 m) and ground temperature (30 60 ℃) on the evaporation characteristics of methanol in open spaces. Building on this data, we modified the standard Mackay-Matsugu evaporation formula with adjusted coefficients. The findings reveal that increasing the diameter of the liquid pool significantly accelerates the kinetics of methanol evaporation, establishing a direct proportionality between the evaporation rate and the surface area of the liquid pool. Furthermore, as the evaporation temperature rises, the impact of the liquid pool diameter on the evaporation rate gradually diminishes. However, the evaporation process is hindered by saturated vapor, resulting in the volume fraction of the methanol gas cloud experiencing a rapid increase initially, followed by a gradual slowdown over time. Consequently, while increasing the diameter of the liquid pool can reduce the time needed for the methanol vapor cloud to achieve saturation equilibrium, it does not affect the final vapor volume fraction or the equilibrium pressure. All operating conditions achieve dynamic equilibrium after approximately 2 000 s. However, the saturated vapor pressure of methanol is solely determined by its temperature. An increase in temperature raises the saturated vapor pressure of methanol and enhances the kinetic energy of the liquid molecules, enabling more molecules to overcome the surface energy barrier and escape from the liquid phase, thus accelerating the evaporation rate. Consequently, the impact of temperature on the methanol evaporation process is more comprehensive and significant compared to the diameter of the liquid pool. Additionally, utilizing the observed variations in the methanol vapor cloud volume fraction from the experiments, we calculated the average evaporation rate of methanol under different initial conditions. Building on this data, we modified the classical Mackay-Matsugu evaporation model, successfully reducing the prediction error of the modified model to 6. 7% . This enhanced model effectively predicts the evaporation rate of the methanol pool throughout the experimental process.