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Corresponding Author

Sokar, Mohamed

Subject Area

Mechanical Power Engineering

Article Type

Original Study

Abstract

This paper discusses the influence of paraffin wax inoculated with ZnO-nanorods on the latent heat of thermal energy storage (LHTES) of solar water heating system. The main objective of the experimental study is to determine the percentage increase in thermal storage capacity of using paraffin wax with 0.15 wt.% ZnO-nanorods as nano-composite phase change material (NCPCM) to the raw paraffin wax as base phase change material (PCM). The experiments were performed by 33-liter insulated stainless-steel storage shell TES tank containing 21 copper tubes 5/8-inch in diameter. The TES tank is filled with circulating water and the tubes are filled with either the pure PCM or NCPCM. The water is the heat transfer fluid (HTF) in the TES tank. The experiments were done at different HTF flow rates to study the best flow rate that increases both the amount of heat transfer and melting rate of PCM. It was found that 0.15 wt.% ZnO NCPCM decreases the charging and discharging time compared to the pure PCM, and a percentage increase is achieved in thermal energy storage by 20% when using 0.15 wt.% ZnO nanorods. The results also reveal that the maximum discharge energy was raised from 266 kW for pure paraffin wax to 306 kJ for 0.15 wt.% ZnO NCPCM. The NCPCM at 6 l/min HTF flow rate provides the highest energy recovery ratio (ERR), while the smallest occurs at 9 l/min.

Keywords

Thermal energy storage (TES); Solar heating system; Nanocomposite PCM

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