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Effect of vibration on heat transfer and pressure drop in a heat exchanger with turbulator
Case Studies in Thermal Engineering ( IF 6.4 ) Pub Date : 2021-12-02 , DOI: 10.1016/j.csite.2021.101680
Azeez Majeed Mohammed , Sinan Kapan , Murat Sen , Nevin Celi̇k

In the present study effects of forced mechanical vibration on a concentric pipe heat exchanger with turbulator inside it, is experimentally analyzed. Three different zigzag shaped turbulators are used in the concentric type heat exchanger. Air is preferred as the working fluid with inlet Reynolds numbers varying from ∼10,000 to ∼55,000. The effect of vibration on heat transfer and pressure drop is tested by using a mechanical vibration test unit. The variable parameters of the vibration phenomena are considered to be acceleration (amplitude) (a = 100, 300 and 600 m/s2), frequency (F = 100, 300 and 600 Hz) and signal type (sine, chirp and random noise).

Effects of the vibration on heat transfer are shown by means of thermal performance factor (η) which includes Nusselt number and friction factor in the same formula. As a result, it is observed that, regardless of the variation of the frequency, acceleration or signal type, applying vibration to the turbulator increases the heat transfer and pressure loss simultaneously. For example, the highest heat transfer enhancement is found as 116% whilst the maximum enhancement percentage of the friction factor is about 95%. It is also found that increasing frequency has more effect than increasing acceleration or changing signal types.



中文翻译:

振动对带湍流器换热器传热和压降的影响

在目前的研究中,强制机械振动对内部带有湍流器的同心管换热器的影响进行了实验分析。同心式换热器中使用了三种不同的锯齿形湍流器。优选空气作为入口雷诺数从~10,000到~55,000变化的工作流体。振动对传热和压降的影响是通过使用机械振动试验装置来测试的。振动现象的可变参数被认为是加速度(振幅)(a  = 100、300 和 600 m/s 2)、频率(F  = 100、300 和 600 Hz)和信号类型(正弦、啁啾和随机噪声) )。

振动对传热的影响通过热性能系数 (η) 来表示,其中包括同一公式中的努塞尔数和摩擦系数。结果,可以观察到,无论频率、加速度或信号类型如何变化,对湍流器施加振动都会同时增加传热和压力损失。例如,最高传热增强为 116%,而摩擦系数的最大增强百分比约为 95%。还发现增加频率比增加加速度或改变信号类型更有效。

更新日期:2021-12-02
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