A novel twisted annulus between two counter-twisted oval tubes is proposed for a double-tube heat exchanger. The oval tubes of the annuli have same twist pitch, but twist with opposite twisting directions. The thermohydraulic performance of the annuli with different aspect ratios and twist ratios is numerically presented. The results indicate that strong secondary flow is generated in the twisted annulus, which can significantly promote the heat transfer. The maximum Nu and f of the twisted annuli are separately 157% and 118% larger than those of the corresponding straight annuli. The largest value of the thermal performance factor is 1.98 in the studied range of geometrical parameters. Correlations of Nu and f as a function of Re, twist ratio and aspect ratio are proposed with the deviations within ±10% and ±8%, respectively.

提出了一种用于双管式热交换器的在两个反向扭曲的椭圆形管之间的新型扭曲环。环的椭圆形管具有相同的扭曲螺距，但扭曲方向相反。数值表示了具有不同长宽比和扭曲比的环空的热工液压性能。结果表明，在扭曲的环空中产生了强烈的二次流，这可以显着促进热传递。扭曲环的最大Nu和f分别比相应的直环的最大Nu和f大157％和118％。在所研究的几何参数范围内，热性能系数的最大值为1.98。的相关性怒江和˚F之间的函数关系建议的Re，扭曲比和纵横比的偏差分别在±10％和±8％之内。