Abstract:
Spiral coil heat exchanger is a suitable terminal device for mine cooling systems. To address the challenges on simulating vapor condensation heat transfer in air and the high computational cost associated with commercial software, a simplified mathematical model of the spiral coil heat exchanger is established based on the theory of simultaneous heat and mass transfer. Through multiple regression analysis, empirical correlations for convective heat transfer inside and outside the spiral tube are obtained, and external mass transfer coefficients are derived using a heat and mass transfer analogy. A computational program is developed using the numerical difference method. The model is validated by mesh independence tests, simulation experiments, and field experiments, with deviations within 10%, confirming its accuracy. The influence of structural and operational parameters on heat transfer performance is analyzed. Results show that, with other parameters held constant, increasing the tube inner diameter from 4 mm to 15 mm can enhance the heat transfer rate by an average of 4.17 times. Increasing the spiral diameter from 40 mm to 80 mm can improve the heat transfer rate by 71%. The heat transfer rate will be reduced by 53% if the pitch is increased from 0.02 m to 0.06 m. Extending the shell-side length from 1.8 m to 3.0 m will increase the water-side temperature difference and heat transfer rate by 36%. Additionally, increasing the water velocity from 0.2 m/s to 1.0 m/s will raise the heat transfer rate by 1.35 times, while increasing the air velocity from 4 m/s to 8 m/s will enhance it by 54%. Except for the pitch, enlarging the tube inner diameter, spiral diameter, shell-side length, water velocity, and air velocity can improve its heat transfer performance. Lowering the water temperature and raising the air temperature contribute to increasing the heat transfer rate and slightly improving the heat transfer performance. However, increasing the air velocity reduces the air-side temperature difference. Therefore, the air velocity must be properly controlled to ensure a sufficiently low outlet air temperature.