Dynamic simulation of temperature and humidity fields in a frost-free refrigerator

To tackle the essential issue of precisely predicting humidity field in frost-free refrigerators, this study introduces a comprehensive dynamic simulation framework. The framework synergizes computational fluid dynamics simulations with custom-developed programming to predict the humidity field effectively. Firstly, a physical model is formulated referred to a specific refrigerating cabinet. Secondly, the mathematical model of the evaporator was developed to calculate the heat transfer, pressure loss, and frost accumulation as moist air flows through the evaporator using porous media model and distributed parameter method. The mathematical model of humidifier and fan were also established to reflect the real operational conditions. Thirdly, a coupling program was written based on the temperature and humidity control strategy to couple each component. Results indicate that the proposed method can accurately predict the dynamic change of relative humidity in the refrigerating cabinet. During an on–off cycle, the average temperature and relative humidity deviation was less than 0.7 ℃ and 5.1 %. Moving the humidifier from the top to the middle of the door would reduce the humidity variation coefficient. When the airflow increased from 2 m³·h⁻¹ to 6 m³·h⁻¹, the humidity coefficient of variation and average relative humidity increased by only 8.9 % and 10.3 %, respectively.