制冷用水平管降膜蒸发器的研究进展及新技术

Review of prior research and new technology for horizontal-tube falling-film evaporator used in refrigeration

针对制冷系统中使用的水平管降膜蒸发器,进行了包括管间流型、管外绕流成膜特征、气流、表面传热系数等流动和换热机理的综述性报道,回顾了水平管降膜蒸发器的技术进展。在批判继承前人研究成果的基础上,提出了可以解决水平管降膜蒸发器内部流动稳定性、均匀性,有效避免局部干涸等难题的新型技术——带有导流和二次布液装置的水平管降膜蒸发器技术。

A review of the prior research on horizontal-tube falling-film evaporator used in refrigeration is presented.The review mainly includes falling film flow and heat transfer mechanism,such as intertube flow modes,falling film characters,film thickness over the horizontal tubes,flowing refrigerant gas,heat transfer and so on.Except for,the technology for flow uniformity and stability and methods of avoiding dryout had been summarized.On the base of prior study,a new technology to improve flow uniformity and stability and avoid dryout had been introduced,which includes the flow-leading and second liquiddistributing. The flowing-leading technology could give a steady liquid flowing without gas interference by fixing different enlarged fins on the under-side of the horizontal tube,and the second liquid-distributing technology could ensure the liquid distributing uniformly without dryout by collecting and distributing the liquid along the gas channel.The new technology has been proved to ensure liquid flowing steadily and distributing uniformly along the horizontal tubes without dryout efficiently.