OICC Press International Journal of Energy and Environmental Engineering 2251-6832 3 1 (December 2012) 2012 09 19 CFD based analysis of flow distribution in a coaxial vacuum tube solar collector with laminar flow conditions 10.1186/2251-6832-3-24 EN Abdul Waheed Badar Institut für Energietechnik, KT 2, FG Maschinen- und Energieanlagentechnik, Technische Universität Berlin, Berlin, 10587, DE Reiner Buchholz Institut für Energietechnik, KT 2, FG Maschinen- und Energieanlagentechnik, Technische Universität Berlin, Berlin, 10587, DE Yongsheng Lou Institut für Energietechnik, KT 2, FG Maschinen- und Energieanlagentechnik, Technische Universität Berlin, Berlin, 10587, DE Felix Ziegler Institut für Energietechnik, KT 2, FG Maschinen- und Energieanlagentechnik, Technische Universität Berlin, Berlin, 10587, DE Journal Article 2012 09 19 Abstract A computational fluid dynamics (CFD) analysis has been conducted to find the pressure losses for dividing and combining fluid flow through a tee junction of a solar collector manifold. Simulations are performed for a range of flow ratios and Reynolds numbers, and equations are developed for pressure loss coefficients at junctions. A theoretical model based on successive approximations then is employed to estimate the isothermal and non-isothermal flow distribution in laminar range through a collector consisting of 60 vacuum tubes connected in parallel in a reverse (U-configuration) and parallel (Z-configuration) flow arrangement. The results are in reasonable agreement with the available experimental results for U-configuration. The proposed CFD based strategy can be used as a substitute to setting up and performing costly experiments for estimating junction losses.