低温空气源热泵室外换热器翅片优化研究进展

Research progress in optimization of fins for outdoor heat exchangers of low-temperature air source heat pumps

关键词:  空气源热泵  换热器翅片  湿工况  干工况  冷凝结霜

Key words:  air source heat pump  heat exchanger fins  wet conditions  dry conditions  condensation frosting

摘要:

在中国空调产业持续增长及气候变化的背景下,热泵型空调以其高效节能的优势成为实现“双碳”目标的关键。然而,翅片在湿工况下易结露、结霜,导致翅片换热效率下降及系统能耗提升。为实现低温空气源热泵室外换热器翅片的多目标优化,分别对换热器翅片的性能评估指标及在干工况和湿工况下优化设计方法进行了综述与分析。结果表明,空气源热泵室外换热器翅片性能可从材料性能、换热流动性能和排水性能3方面进行综合评价。干工况下换热器翅片的优化主要聚焦于翅片结构的改进以强化传热。既有针对湿工况下单翅片的性能提升策略主要集中在微米级表面形貌设计与浸润性调控领域,通过激光刻蚀或化学沉积构建微米级的沟槽网络,在维持换热性能前提下降低压降。基于涡流诱导原理开发的翅片表面凸起和凹坑结构高度为0.6~1.61 mm,使努塞尔数提升19.03%。在翅片表面设置结构以实现湿工况下的诱导成核并结合仿生学原理实现快速排水是未来的发展趋势。此外,结合亲疏水表面特性的优势,设计混合表面可延缓结霜并促进翅片排水。进一步指出该领域的重点研究方向,以期提升换热器的换热效率、流动与排水性能,满足现代工业与民用领域对高效、节能换热设备的需求。

Abstract:

Against the backdrop of sustained growth in China′s air conditioning industry and climate change, heat pump air conditioners have emerged as a key solution for achieving the "dual carbon" goals due to their high energy efficiency. However, fins are prone to condensation and frost formation under humid operating conditions, leading to reduced heat transfer efficiency and increased system energy consumption. To achieve multi-objective optimization of low-temperature air-source heat pump outdoor heat exchanger fins, this study reviews performance evaluation metrics and optimization methodologies for fins under both dry and wet conditions. Results indicate that air-source heat pump outdoor heat exchanger fin performance can be comprehensively assessed across three dimensions: material properties, heat transfer flow characteristics, and drainage performance. Optimization under dry conditions primarily focuses on enhancing heat transfer through structural improvements. Existing strategies for enhancing single-fin performance under wet conditions primarily concentrate on micrometer-scale surface topography design and wettability control. Techniques such as laser etching or chemical deposition create micrometer-scale groove networks to reduce pressure drop while maintaining heat transfer efficiency. Fin surface protrusions and pits developed based on vortex induction principles, with heights ranging from 0.6 to 1.61 mm, increase the Nusselt number by up to 19.03%. Future trends involve integrating surface structures for induced nucleation in wet conditions while leveraging biomimetic principles for rapid drainage. Additionally, designing hybrid surfaces combining hydrophilic and hydrophobic properties can delay frost formation and enhance fin drainage. This paper further identifies key research directions to improve heat exchanger efficiency, flow dynamics, and drainage performance, meeting modern industrial and civil demands for high-efficiency, energy-saving heat transfer equipment.