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Abstract. An infrared explosion puffing dryer was developed to achieve the process control of pressure. A three-dimensional model was developed to simulate the flow field of pressure relief process. The model accounts for the atmosphere mode and vacuum mode and predicts the flow field evolution with time in drying chamber. The simulation was performed at atmosphere mode and vacuum mode with initial pressure of 300 kPa. The flow field evolution and distribution in drying chamber and vacuum tank were explored. Results showed that the pressure relief process could be divided into two stages, namely, constant rate stage and decreasing rate. When the vacuum valve was opened, the air in drying chamber is rushed into the vacuum tank. This results in lower pressure in the drying chamber and higher pressure in the vacuum tank. The pressure relief rate between the atmosphere and vacuum modes is very similar in the early stage. Removing the air in the drying chamber by atmosphere firstly is helpful to improve the pressure relief rate. The findings of current work provide theoretical basis to better design and control of the process as it elucidates the flow field characteristic and illustrates the pressure relief process.