Abstract: Because of the high price of copper, a small tube-diameter evaporator is one of the most efficient technologies to reduce the cost of the dehumidifier. The performance characteristics and cost of dehumidifiers using 7.0 mm/5.0 mm tube diameter evaporators are analyzed based on experiments, and the optimization design methods of 5.0 mm tube diameter evaporators are compared. The results show that under the same test conditions, the overall operating power of dehumidifiers with 7.0 mm/5.0 mm tube evaporators has a negative correlation with the amount of refrigerant. However, the dehumidification capacity and EF (Energy Factor) symbolled as the energy efficiency of the dehumidifier shows a trend of first increasing and then decreasing with the decrease of the refrigerant amount. There is an optimal refrigerant amount. The optimal refrigerant amount of the dehumidifier using a 5.0 mm tube diameter evaporator is at least 4.76% lower than that of the 7.0 mm tube diameter evaporator. The split flow design has the most obvious advantages in improving the dehumidification capacity and EF of the dehumidifier, which can be increased by 11.04% and 10.98% respectively. Under the condition of meeting the design requirements of the same dehumidification capacity and EF, the total cost of a 5.0 mm tube evaporator is 9.66% lower than that of a 7.0 mm tube evaporator.

Key words: Dehumidifier, Small tube diameter evaporator, Performance characteristics, Optimal design, Cost analysis