Study on Influence of Microwave Electric Field Direction on Evaporation Based on Molecular Dynamics

Microwave-assisted evaporation technology is widely used today, but its molecular mechanism is not fully understood. To investigate the molecular mechanism of the influence of microwave electric field direction on water evaporation, this paper designed experiments to measure the microwave energy required to evaporate each gram of water with electric field directions parallel and perpendicular to the water surface. The temperature rise curve of the water is controlled to be consistent in both cases, and the temperature distribution of the water is made uniform by stirring. We found a stable difference in the energy absorbed by the two situations, indicating that the direction of the microwave electric field has an effect on water evaporation. In this article, the evaporation behavior of water molecules under different directional electric fields was then studied by molecular dynamics. The SPCE water molecule model, which simulates pure water systems well, was selected for this calculation. Based on the GROMOS force field, the evaporation enthalpy and surface tension of water under various conditions at constant temperature were calculated and the conclusions were analyzed. The calculated results are in agreement with the experimental results, and the influence of the evaporation enthalpy of water molecules is related to the direction of the microwave electric field.