Analysis of Heat and Moisture Transfer Characteristics on the Air Side of a Refrigerated Air Dryer Evaporator

The demand for efficient dehumidification in evaporators has become one of the key technical challenges restricting the high-quality development of the refrigerated air dryer industry. To investigate the effects of fin structure on the air-side heat transfer and dehumidification performance of finned-tube evaporators applied in refrigerated air dryers under the operating conditions of 50 °C, RH = 85%, numerical heat and mass transfer models for the air side of evaporators with plain fins and wavy fins were established based on the Ansys Fluent software 2022R1. The study found that wavy fins possess superior heat transfer and moisture removal capabilities. Key performance indicators, including the air-side heat transfer rate (Q), moisture removal amount (Δm), friction factor (f), and the nusselt number (Nu), were all higher for wavy fins compared to plain fins. Building upon this, three types of vortex generators (VGs) were introduced to further optimize the performance of the wavy fins, aiming to balance heat transfer enhancement and flow resistance control. At an attack angle of 30°, the comprehensive performance factor (JF) showed the highest improvement, reaching 43% with the Delta Winglet vortex generators. The 15° configuration also showed improvement, while 45° led to the worst performance due to increased flow resistance. The results indicate that for typical high-temperature and high-humidity environments, the wavy fin is recommended as the preferred choice due to its superior overall performance and simple structure. For applications requiring higher dehumidification capacity, wavy fins equipped with vortex generators can be selected to achieve the most efficient dehumidification. This study provides valuable insights for the design and application of finned-tube evaporators in dehumidification systems under high-temperature, high-humidity conditions for refrigerated air dryers.