Numerical model of dusty-water bridge forming between neighbor fins of fin-and-tube heat exchangers

Abstract

Abstract A typical room air conditioner uses fin-and-tube heat exchanger as evaporator, and its performance may be dramatically deteriorated by the dusty-bridge between fins, which is resulted from dehumidification and dusty particle adhesion. Design of a fin-and-tube heat exchanger to avoid dusty-bridge need to predict the forming process of dusty-bridge between fins. In this paper, a numerical model is developed to simulate the dusty-water bridge formation between fins, which can well predict the shape of dusty-water bridge and mass of the dusty particles adhered by water bridges. Prediction of the dusty-water bridge shape is realized by calculating the mean curvature of the water bridge interface at first and then predicting the effect of air flow and gravity on the water bridge shape. The prediction method of the mass of the dusty particles adhered by water bridges between fins is to simulate the motion trajectories of all particles in the air flow at first and then to choose those particles intersecting with the water bridge surface as adhered. The validation results show that, the water bridge shape predicted by the model agrees well with the experimental image, and the predicted adhered particle mass agree with 92% of the experimental data within the deviation of ±20% and the mean deviation is 14.8%.