TY - JOUR
T1 - Thermal performance of compound heat transfer enhancement method using angled ribs and auxiliary fins
AU - Chang, S. W.
AU - Jian, Y. R.
N1 - Publisher Copyright:
© 2016 Elsevier Ltd
PY - 2017
Y1 - 2017
N2 - Detailed Nusselt number (Nu) distributions over two opposite endwalls of two parallelogram channels roughened by 45° ribs without/with in-line auxiliary fins are measured using steady-state infrared thermography method at 5000 ⩽ Re ⩽ 15,000. Pressure drop measurements are individually performed at isothermal conditions to detect the Fanning friction factors (f) for thermal performance factors (TPF) evaluations. Relative heat transfer and f augmentations for this type of passive compound heat transfer enhancement (HTE) method are assessed by comparing with the Nusselt numbers (Nu∞) and f factors (f∞) of smooth plain tube references at the same Reynolds number (Re). With present in-lined auxiliary fins on two opposite ribbed endwalls, the channel averaged HTE ratios fall between 4.43 and 4.21 with the corresponding f/f∞ratios in the range of 6.5–3.35; giving rise to the TPF values between 2.37 and 2.81. As the comparative HTE ratios, f/f∞values and TPF values for the similar ribbed channels without auxiliary fins are in the respective ranges of 3.93–3.61, 1.63–1.53 and 2.41–2.35, the present compound HTE method further elevates the Nu/Nu∞ratios with the associated f amplifications but can still improves the TPF values in general. It is concluded that the present compound HTE method using angled ribs and auxiliary fins is applicable for improving thermal performances of turbulent channel flow.
AB - Detailed Nusselt number (Nu) distributions over two opposite endwalls of two parallelogram channels roughened by 45° ribs without/with in-line auxiliary fins are measured using steady-state infrared thermography method at 5000 ⩽ Re ⩽ 15,000. Pressure drop measurements are individually performed at isothermal conditions to detect the Fanning friction factors (f) for thermal performance factors (TPF) evaluations. Relative heat transfer and f augmentations for this type of passive compound heat transfer enhancement (HTE) method are assessed by comparing with the Nusselt numbers (Nu∞) and f factors (f∞) of smooth plain tube references at the same Reynolds number (Re). With present in-lined auxiliary fins on two opposite ribbed endwalls, the channel averaged HTE ratios fall between 4.43 and 4.21 with the corresponding f/f∞ratios in the range of 6.5–3.35; giving rise to the TPF values between 2.37 and 2.81. As the comparative HTE ratios, f/f∞values and TPF values for the similar ribbed channels without auxiliary fins are in the respective ranges of 3.93–3.61, 1.63–1.53 and 2.41–2.35, the present compound HTE method further elevates the Nu/Nu∞ratios with the associated f amplifications but can still improves the TPF values in general. It is concluded that the present compound HTE method using angled ribs and auxiliary fins is applicable for improving thermal performances of turbulent channel flow.
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U2 - 10.1016/j.applthermaleng.2016.11.071
DO - 10.1016/j.applthermaleng.2016.11.071
M3 - Article
AN - SCOPUS:85006821413
SN - 1359-4311
VL - 114
SP - 1325
EP - 1334
JO - Applied Thermal Engineering
JF - Applied Thermal Engineering
ER -