• Energy Research
• Open Source close
• Embargo close
• other engineering and technologies close
• CN close
• FR close

Thermoacoustic technology emerges as a sustainable and low-carbon method for energy conversion, leveraging environmentally friendly working mediums and independence from electricity. This study presents the development of a multimode heat-driven thermoacoustic system designed to utilize medium/low-grade heat sources for room-temperature cooling and heating. We constructed both a simulation model and an experimental prototype for a single-unit direct-coupled thermoacoustic system, exploring its performance in heating-only, cooling-only, and hybrid heating and cooling modes. Internal characteristic analysis including an examination of internal exergy loss and a distribution analysis of key parameters was first conducted in the hybrid cooling and heating mode. The results indicated a positive-focused traveling-wave-dominant acoustic field within the thermoacoustic core unit, enhancing energy conversion efficiency. The output system performance was subsequently tested under different working conditions in the heating-only and cooling-only modes. A maximum output heating power of 2.3 kW and a maximum COPh of 1.41 were observed in the heating-only mode. Meanwhile, a cooling power of 748 W and a COPc of 0.4 were obtained in the typical cooling condition at 7 °C when operating in cooling-only mode. These findings underscore the promising potential of thermoacoustic systems for efficiently utilizing medium/low-grade heat sources for cooling and/or heating applications in the future.

The production of charcoal for its many uses requires a careful selection of biomass and pyrolysis conditions, especially temperature, to ensure suitable quality. To do so, physical, chemical, and mechanical energy must be considered. This study aimed to analyze the yields and properties of charcoal produced at different pyrolysis temperatures. Eucalyptus saligna wood was pyrolyzed in a reactor with final temperatures of 450, 550, 650, 750, 850 and 950 °C. The yields of charcoal, pyroligneous liquid and non-condensable gases were determined. Mass loss was determined for each temperature. Charcoal analysis included the determination of the apparent density, proximate analysis, heating value, mechanical strength, X-ray images for the internal visualization of its structure and hygroscopicity test. Relevant charcoal properties for the steel industry and barbecue, such as density, mechanical strength, heating value and hygroscopicity, show variable trends from pyrolysis at 650 °C. The results show that pyrolysis temperature had a great impact on the properties of charcoal. The apparent density of charcoal rose from 500 °C and had no relation to the breaking strength. When the pyrolysis temperature was raised, an increase in both apparent and true densities, internal fissures and cracks and fixed carbon content of charcoal was observed.