Search

Solar thermal systems have been widely used to increase energy efficiency in residential sector, since it became one of the top priorities in many countries to mitigate the electricity shortage. Thus, for better deployment of solar thermal systems in the residential sector it is important to understand the household electricity consumption and energy usage for domestic hot water, though developing countries lack this type of accurate data. This work assesses a domestic hot water technology transition to solar thermal systems in the urban areas of developing countries, taking as case study Maputo city, in Mozambique. First, a survey was made to the domestic hot water needs, demand and usage, in 700 households, 28 neighbourhoods of Maputo, having identified the sources and technologies used to heat water and quantified the domestic hot water needs. Then, the impact on energy demand, cost and CO2 emissions of domestic hot water technology change to solar thermal systems was modelled as well as the impact on electricity grid. The survey results point that the predominant energy sources used for domestic hot water in urban areas are electricity and biomass with nearly 46% and 41% shares, respectively. Further, results show that the domestic hot water technology used depends on household income, being the electric water heaters mostly used in households with relatively high-income. The technology transition to solar thermal systems results in a positive impact on the grid by reducing up to 65.7% the domestic hot water electricity demand and 78.7% of the CO2 emissions, while the economic savings are up to 244 USD/household/year. However, peak load is expected to increase by 11%, suggesting the need for load management policy implementation.

The isomerization of α-terpineol (1) catalyzed by heteropoly acid H3PW12O40 (PW) in homogeneous and heterogeneous systems yields 1,8-cineole (2) and 1,4-cineole (3), both useful for flavoring and pharmaceutical applications. In the homogeneous system, 2 and 3 were obtained with 25% and 23–27% selectivity, respectively, at 50–90% α-terpineol conversion (in a nitrobenzene solution, 40 °C). In the heterogeneous system, 35% of 2 and 25% of 3 were obtained at 70–100% conversion in a cyclohexane solution at 60 °C using silica-supported PW as a solid acid catalyst, and the catalyst could be recycled. PW showed a higher catalytic activity and selectivity than conventional acid catalysts such as H2SO4 and Amberlyst-15.

A novel one-pot catalytic synthesis of diisobornyl ether directly from camphene (1) has been developed. The reaction occurs under near ambient conditions in the presence of dissolved or silica-supported heteropoly acid H3PW12O40 (PW) as a catalyst to give diisobornyl ether (2) with up to 90% selectivity at 50–60% conversion, along with isoborneol (3). Ether 2 appears to be a new compound; it was isolated as a mixture of meso and dl stereoisomers and fully characterized by MS-GC, NMR and IR spectroscopy. The supported PW catalyst can be easily separated and reused; no PW leaching from support was observed during the reaction. Conventional acid catalysts such as H2SO4 or Amberlyst-15 showed no activity in this reaction.