Thermal analysis of a serpentine flat plate collector and investigation of the flow and convection regime

Abstract

A special kind of flat plate collectors was examined in detail through CFD analysis. The distinctiveness of the current model has to do with the piping system was applied which is a serpentine flow conduit. The operation of the collector was examined at four different inclination angles (0°, 15°, 30°, and 45°) and several values of the inlet water temperature (10-80 °C per 10 °C) by providing the same heat perpendicular to the cover in each case. The thermal efficiency as well as the temperature fields of the collector was determined first. Furthermore, the overall heat losses were calculated and compared to these arisen from the Cooper-Dunkle assumption while the mean divergence between these two solutions was around 5%. Moreover, the natural convection inside the gap as well as the tube to water convection was examined and the heat transfer coefficients were validated from theoretical models in horizontal position. In particular, the simulation results found to diverge from the theoretical ones about 12.5% and 7% as regards the pipe flow and the air-gap, respectively. In addition, a remarkable flow phenomenon was observed at the bends of the pipe and the nature of it was explained in detail. Last but not least, the inclination angle seems that affects significantly the collector's performance since the higher the slope the lower the convection losses. Solidworks and its simulation program Flow Simulation were used to design and simulate the whole collector.

Energetical and Exergetical Analyses of a Concentrating PV/T Collector: A Numerical Approach

“…As stated in Section 2.3.2, the coefficient took a constant value of 5 W/m 2 /K, which is deemed appropriate for such enclosed spaces. Comparable values are documented in relevant studies [30,42].…”

Thermal and Optical Analyses of a Hybrid Solar Photovoltaic/Thermal (PV/T) Collector with Asymmetric Reflector: Numerical Modeling and Validation with Experimental Results

“…From Equation (10) the heat-transfer coefficient of the wind was calculated and took the value of 13.3 W/m 2 /K. As mentioned in Section 2.3.3, the convective heat-transfer coefficient of the enclosed air gap was assumed to be constant and equal to 5 W/m 2 /K, which is a reasonable value for such closed areas while similar values could be found in studies [3,36]. The thermal simulation operating conditions are, also, available in Table 6.…”

“…SolidWorks [45] is a widely used simulation package which has been applied in numerous studies regarding energy systems and especially in solar thermal collectors' applications [3,8,16,46,47]. The program supports design and it is suitable for a wide range of applications by ensuring flow, optical, and thermal simulations are conducted either separately or simultaneously, while it has been validated with experimental results in numerous studies [17,18,48].…”

“…The slope of the collector, several riser and tube diameters as well as distances between the top of the collector to the bottom side of the storage tank were analyzed. Korres and Tzivanidis [3] performed a computational fluid dynamic (CFD) analysis on a flat plate collector with a serpentine flow system and examined the effect of the inclination angle and the effect of the natural convection in the air. Subiantoro and Ooi [4] developed analytical methods for the calculation of the heat losses from the top of the collector.…”