Numerical study on coupled fluid flow and heat transfer process in parabolic trough solar collector tube

Journal Article · Fri Oct 15 00:00:00 EDT 2010 · Solar Energy

DOI:https://doi.org/10.1016/J.SOLENER.2010.07.012· OSTI ID:21350417

Tao, Y B; He, Y L ^[1]

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1. State Key Laboratory of Multiphase Flow in Power Engineering, School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049 (China)

A unified two-dimensional numerical model was developed for the coupled heat transfer process in parabolic solar collector tube, which includes nature convection, forced convection, heat conduction and fluid-solid conjugate problem. The effects of Rayleigh number (Ra), tube diameter ratio and thermal conductivity of the tube wall on the heat transfer and fluid flow performance were numerically analyzed. The distributions of flow field, temperature field, local Nu and local temperature gradient were examined. The results show that when Ra is larger than 10{sup 5}, the effects of nature convection must be taken into account. With the increase of tube diameter ratio, the Nusselt number in inner tube (Nu{sub 1}) increases and the Nusselt number in annuli space (Nu{sub 2}) decreases. With the increase of tube wall thermal conductivity, Nu{sub 1} decreases and Nu{sub 2} increases. When thermal conductivity is larger than 200 W/(m K), it would have little effects on Nu and average temperatures. Due to the effect of the nature convection, along the circumferential direction (from top to down), the temperature in the cross-section decreases and the temperature gradient on inner tube surface increases at first. Then, the temperature and temperature gradients would present a converse variation at {theta} near {pi}. The local Nu on inner tube outer surface increases along circumferential direction until it reaches a maximum value then it decreases again. (author)

• OSTI ID: 21350417
• Journal Information: Solar Energy, Vol. 84, Issue 10; Other Information: Elsevier Ltd. All rights reserved; ISSN 0038-092X
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
FORCED CONVECTION
THERMAL CONDUCTION
PARABOLIC TROUGH COLLECTORS
THERMAL CONDUCTIVITY
TUBES
NUSSELT NUMBER
NUMERICAL ANALYSIS
FLUID FLOW
TEMPERATURE GRADIENTS
RAYLEIGH NUMBER
SURFACES
TWO-DIMENSIONAL CALCULATIONS
SPATIAL DISTRIBUTION
FLUIDS
PERFORMANCE
VARIATIONS
SOLIDS
NATURAL CONVECTION
SIZE
Mixed convection
Coupled heat transfer
Local Nusselt number