Abstract :
Solar liquid collectors are potential candidates for enhanced heat transfer, but there are just a few studies focused on this topic.
However, enhancement techniques can be applied to thermal solar collectors to produce more compact and efficient designs. This work
presents the study of heat transfer enhancement in a tube-on-sheet solar panel with wire-coil inserts, using TRNSYS as the simulating
tool. The numerical simulation methodology predicts the thermohydraulic flow behaviour of enhanced and standard tube-on-sheet solar
collectors, evaluating the local losses, friction coefficients and Nusselt numbers as functions of the operating parameters. The standard
and the enhanced collectors have been simulated under the same ambient, radiant and operating conditions. The standardized efficiency
curves according to the standard UNE-EN 12975-2 are provided. The enhanced collector increases the thermal efficiency values by 4.5%.
A parametric study was performed to relate the fluid and flow characteristics with the heat transfer enhancement by wire-coil inserts. The
simulations were performed for different working fluids (water and propylene glycol/water mixtures) in a mass flow rate range from 15 to
120 l/h m2.
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