Search

This article experimentally studies the thermal performance of latent heat storage in a two-phase thermosyphon solar water heater, which utilizes the superior heat transfer characteristics of boiling and condensation, and eliminates drawbacks found in the conventional solar water heater. Experimental investigations are first conducted to study the thermal behavior of tricosane (paraffin wax 116), water, and sodium acetate (NaC[H.sub.3]COO x 3[H.sub.2]O) used as energy storage materials. The results indicate that tricosane provides many advantages to be the energy storage material in the latent heat storage system. This study also examines the functions of charge and discharge thermal behaviors in a two-phase thermosyphon solar water heater The results show that the system gives optimum charge and discharge performance under 40% alcohol fill ratio and with tricosane used as the energy storage material, and displays an optimum charge efficiency of 73% and optimum discharge efficiency of 81%. [DOI: 10.1115/1.2147588] Keywords: energy storage material, two-phase thermosyphon, solar water heater

The efficient gas phase photocatalytic hydrogenation of CO2 into a desirable renewable fuel was achieved using a Cu-loaded TiO2 photocatalyst system. Enhancing the amount of Ti3+ relative to Ti4+ in a Cu-loaded TiO2 photocatalyst provided an excellent opportunity to promote the photohydrogenation of CO2. The coexistence of Cu and Cu+ species during the photoreaction was shown to efficiently enhance the photocatalytic activity by prolonging the lifetime of the electrons. To achieve the best photoactivity, the Cu species must be maintained at an appropriately low concentration (≤1 wt%). The highest CH4 yield obtained was 28.72 μmol g−1. This approach opens a feasible route not only to store hydrogen by converting it into a desirable renewable fuel, but also to reduce the amount of the greenhouse gas CO2 in the atmosphere. [ABSTRACT FROM AUTHOR]