摘要

The availability of solar energy is of fluctuating nature. In order to obtain uninterrupted output, a thermosyphon heat pipe collector is developed with provision of the back layer as a thermal energy storage (TES) unit. The TES unit acts as an instantaneous heat storage medium offering sensible and latent heat storage. Entrapped air and phase-change material (PCM) are used as energy storage media. The TES unit has two identical collectors, consisting of three serpentine-type loop thermosyphons, of which one is integrated with the back container of the TES unit. Outdoor experiments are carried out to demonstrate the potential and influence of the TES unit in water heating application. These collectors are tested at 20–60° tilt angles. The performance of the integrated TES unit solar collector is better in comparison with the collector without the TES unit system. The highest efficiencies are obtained at the 50° tilt angle for both collectors. A TES unit with paraffin wax as PCM gives higher performance than that with entrapped air and without the TES unit, with an extended output of 3 to 4 h during an off-sunshine period. The plate temperature trend of integrated TES collectors is found to be higher and unfluctuating, compared to others. The TES unit in the back layer acts as a booster for energy with uninterrupted energy supply.