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Iron ore is generally transported using a traditional method that releases significant amounts of dust into the environment. In contrast, the pipeline transportation of slurry is noticeably a sustainable approach for efficiently transporting iron ore by reducing the environmental pollution. The interparticle interaction of the iron ore particles should be mutually repulsive for steady dispersion. Surfactants and polymers adsorb efficiently at the solid/liquid interface due to their amphiphilic character, rendering the surface hydrophilic or hydrophobic to create a stable dispersion. The present review discusses the interaction of surfactants on the stabilization of solid particles for the ease of pipeline transportation using various types of stabilization mechanisms. In addition to the effect of surfactant alone, its combination with some other parameters such as particle size distribution, temperature, solid concentration, etc. has been discussed. The review also describes the detailed classification of iron ore, surfactant, and characteristic properties of surfactants.

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Preservation of food and vegetable products is an age-old practice for the retention of flavor, appearance, and quality. From ancient times, driers for drying food grains work on direct sun rays, firewood, fossil fuels, and coals causing carbon release. These available methods are expensive, unreliable, and unhygienic; thereby the use of a solar dryer working on free and clean energy is better for higher value addition to food preservation. The objective of this exploration is to study the recent developments in the use of different types of solar dryers for drying foods, vegetables, seafood, etc. There exist many studies on the effects of the parameters such as temperature, relative humidity, and speed of air, turbulence effect, sun irradiation, and the latitude of the location in the solar drying process. The findings show that the climate conditions such as solar radiation and atmospheric air play an important role in the drying efficiency of the solar dryer. A phase change material stores thermal energy during the daytime and releases heat during the nighttime. This process improves thermal efficiency and reduces heat loss during the drying period. On the one hand, a hybrid dryer integrated with a solar panel produces electricity for the operation of a DC blower circulating hot air inside the drying chamber for better drying. In addition, a critical review has been performed on the usage of different absorbing plates increasing heat transfer rate, use of various phase change materials for heat storage, and analysis of CFD simulation.

India like other developing countries adopts many food preservation technologies using fossil fuels. But the fossil fuel resource depletes over the years and is non-renewable. Therefore, solar drying technology is preferred as a sustainable method for food preservation. The present study is aimed at a sustainable livelihood initiative for drying fruits and vegetables through solar technology intervention using an indirect forced convection type solar dryer. Such a dryer of 15 kg capacity has been designed and fabricated for drying mangoes. Performance indicators such as instantaneous collector efficiency, drying efficiency, drying rate, coefficient of performance, heat utilization factor, and moisture content on a dry basis are evaluated as 59%, 32.25%, 0.15178 kg/hr, 0.77, 0.229, and 2.55 respectively by considering maximum outlet collector temperature, drying chamber temperature and atmospheric temperature. Economic indicators such as payback period and cost-benefit ratio are also evaluated as 1.439 and 2.0008 respectively. The dryer can be used by rural people of Odisha for earning their livelihood.

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