Abstract

The influence of the configuration of flat fins on the thermal characteristics of a finned-tube heat exchanger is experimentally investigated. The configurations fins of four shapes are studied: plain (P), nozzle (N), diffuser (D), and nozzle-diffuser (ND). The bend angles of the N-fins were 10° and 20°, and the D‑fins were 10°, 20°, 30°, and 40°. It has been established that the configuration of the finning and the angle of bending of the fins play an important role in increasing the thermal characteristics of the finned-tube heat exchanger. The main advantage of the proposed finning method in comparison with those used earlier is an increase in heat transfer practically without an increase in the coefficient of friction inside the heat exchanger tube. The scheme of the experimental setup and its main characteristics are described. The obtained experimental data on heat transfer are graphically presented. It is shown that small bending angles of the nozzle and diffuser fins significantly increase heat transfer, while angles of more than 40° lead to its deterioration. A formula for calculating the Nusselt number is presented, which generalizes the experimental data for all investigated finning configurations with an error of ±14%.

中文翻译：

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翅片结构和翅片角度对翅片管换热器热性能影响的研究。实验研究

摘要

实验研究了扁平翅片的配置对翅片管换热器热特性的影响。研究了四种形状的翅片配置：平面 (P)、喷嘴 (N)、扩散器 (D) 和喷嘴扩散器 (ND)。N-fins的弯曲角度为10°和20°，D-fins的弯曲角度为10°、20°、30°和40°。已经确定翅片的配置和翅片的弯曲角度在提高翅片管换热器的热特性方面起着重要作用。与之前使用的那些方法相比，所提出的翅片方法的主要优点是实际上增加了传热，而没有增加换热器管内的摩擦系数。描述了实验装置的方案及其主要特点。获得的传热实验数据以图形方式呈现。结果表明，喷嘴和扩散翅片的小弯曲角度会显着增加传热，而超过 40° 的角度会导致其劣化。给出了计算努塞尔数的公式，该公式概括了所有研究的翅片配置的实验数据，误差为 ±14%。