Gas migration characteristics in vehicle tank under different ventilation conditions

In recent years, due to the frequent occurrence of accidents in confined space operations, horizontal ammonia tank trucks with higher accident frequencies were selected for numerical simulation research through comparative analysis. The ammonia concentration variation characteristics of horizontal ammonia tank cars were simulated under four conditions: natural ventilation with 0 degrees incoming air, natural ventilation with 45 degrees incoming air, mechanical ventilation with extraction, and mechanical ventilation with compression. The results indicate that natural ventilation requires 48 h to reduce the ammonia concentration to a safe range for operation, while mechanical ventilation reduces the ammonia concentration to infinity and approaches zero within 30 min according to regulations, making the working environment safer; Set up monitoring points inside the tank to monitor the gas disturbance inside the tank at different wind speeds. Based on the ammonia concentration cloud map and the monitoring point wind speed, it can be concluded that local ammonia accumulation is more likely to occur on both sides of the tank due to poor ventilation. Comparing and analyzing the simulated values with theoretical calculations and experiments, it was found that there are differences in the degree of gas change but the overall trend is the same. This indicates that ventilation simulation and the determination of ammonia migration characteristics have practical significance for guiding on-site operations.