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Numerical investigation on turbulent forced convection and heat transfer characteristic in spirally semicircle-grooved tube
International Journal of Mechanical and Materials Engineering Pub Date : 2016-10-27 , DOI: 10.1186/s40712-016-0062-2
Pitak Promthaisong , Amnart Boonloi , Withada Jedsadaratanachai

Turbulent forced convection and heat transfer structure in the spirally semicircle-grooved tube heat exchanger are numerically examined. The computational problem is solved by finite volume method (FVM) with the SIMPLE algorithm. The influences of groove depth and helical pitch on heat transfer, pressure loss, and thermal performance are investigated for turbulent regime, Re = 5000–20,000. As a result, the swirling flow is found through the test section due to the groove on the tube wall. The flow structure in the spirally semicircle-grooved tube can separate into two types: main and secondary swirling flows. The main swirling flow is found in all cases, while the secondary swirling flow is detected when DR ≥ 0.06. The swirling flow disturbs the thermal boundary layer on the tube wall that is an important reason for heat transfer augmentation. In range studies, the enhancements on heat transfer and friction loss are around 1.16–1.96 and 1.2–10.8 time above the smooth tube, respectively. The optimum thermal performance is around 1.11, which detected at DR = 0.06, PR = 1.4, and Re = 5000. The correlations of the Nusselt number and friction factor for the spirally semicircle-grooved tube with PR = 1.4 are produced to help to design the tube heat exchanger.

中文翻译:

螺旋半圆管湍流强迫对流换热特性的数值研究

对螺旋半圆管式换热器的湍流强迫对流换热结构进行了数值研究。用SIMPLE算法通过有限体积法(FVM)解决了计算问题。研究了在湍流状态下凹槽深度和螺旋螺距对传热,压力损失和热性能的影响,Re = 5000–20,000。结果,由于管壁上的凹槽,通过测试部分发现了旋流。螺旋半圆管中的流动结构可以分为两种类型:主旋流和副旋流。在所有情况下都可以找到主旋流,而当DR≥0.06时,可以检测到副旋流。旋流扰动了管壁上的热边界层,这是增加传热的重要原因。在范围研究中,传热和摩擦损失的提高分别比光滑管高1.16-1.96和1.2-10.8倍。最佳热性能约为1.11,在DR = 0.06,PR = 1.4和Re = 5000时检测到。为PR = 1.4的螺旋半圆管制成的Nusselt数和摩擦系数之间的相关性可以帮助设计管式热交换器。
更新日期:2016-10-27
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