Conclusions
In this study, the asymmetric outward convex corrugated tube is
introduced as the metal tube of PTR (ACPTR) to increase the overall
heat transfer performance and reliability. An optical-thermalstructural
sequential coupled method was developed to study the
heat transfer performance and thermal deformation of tube
receiver for parabolic trough solar collector system. The following
conclusions have been drawn:
1) Mirror roughness errors and pointing errors decrease the peak
value of concentrated heat flux distribution on the bottom periphery
of PTR and broaden the region of absorbing concentrated
sunlight.
2) The usage of asymmetric outward convex corrugated metal tube
for PTR can enhance the heat transfer performance effectively
with the sacrifice of pressure drop.
3) The introduction of asymmetric outward convex corrugated
metal tube for PTR can enhance the overall heat transfer
Fig. 30. Effective Nusselt number in the metal tube variation with the increase of
Reynolds number for both the PTR and ACPTR (p/D ¼ 5.8, H/D ¼ 0.06) at different rl/D
values.
Fig. 31. Variation of pressure drop with the increase of Reynolds number for both the
PTR and ACPTR (p/D ¼ 5.8, H/D ¼ 0.06) with different rl/D values.
Fig. 32. Variation of fanning friction factor in the metal tube with the increase of
Reynolds number for both the PTR and ACPTR (p/D ¼ 5.8, H/D ¼ 0.06) at different rl/D
values.
Fig. 33. Variation of the overall heat transfer performance for ACPTR (p/D ¼ 5.8,H/
D ¼ 0.06) with increase of Reynolds number at rl/D values.
290 W. Fuqiang et al. / Energy 114 (2016) 275e292
performance effectively and the maximum enhancement of
overall heat transfer performance factor is 148%.
4) The maximum von-Mises thermal strain of the metal tube of
ACPTR is always smaller than that of the metal tube of PTR at all
Reynolds number conditions, and the maximum restrain of von-
Mises thermal strain by using ACPTR is 26.8%.