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This study is the first report in the literature of exergetic, economic, and environmental (3E) analysis for low cost solar heaters (LCSH). In this context, 3E analyses were performed for two LCSH configurations, tubes of the absorber plate connected in series and parallel. The mean exergy efficiency of the LCSH in parallel was 2.56% while for the LCSH in series it was 2.01%. The parallel collector presented lower rates of exergetic destruction and entropy generation, besides a higher overall efficiency. The use of alternative materials in the construction of the LCSH made it possible to achieve low values of embodied energy and embodied carbon emission and consequently excellent environmental indicators. It was found that the simple payback period (SPP) and the leveled heating cost (LCOH) found were 0.38 years and 0.014 US$ kWh−1 for the collector in parallel and 0.42 years and 0.016 US$ kWh−1 for the collector in series. Based on the analyses performed, the LCSH in parallel proved to be the most attractive alternative among the evaluated ones and is indicated for operations where high efficiencies and high temperatures are not required and the cost factor is important.

This study aimed to evaluate the Ultraviolet-C (UV-C) radiation effects on the physiological and sanitary quality of seeds of two soybean cultivars (BRS7380 and M7739). We used a completely randomi...

Pequi is one of the most important fruits of Cerrado biome, and it is very consumed mainly by the population of west central of Brazil. The pequi is composed of bark, pulp and seeds, the bark of the ripe fruit correspond to approximately 84% of its weight, being the great majority discarded as garbage, causing environmental impact. On this, this research had as objective to characterize the barks of the pequi, aiming its use as biomass. For this purpose, moisture content analyzes were performed, and ashes, volatile materials, fixed carbon, specific mass, thermogravimetric analysis (TGA), grain size, and higher calorific value analysis as well, according to Brazilian standards ABNT NBR 8112 and 8633. The analyses showed that the bark of the in natura pequi has a high moisture content, around 73%, and 2.2% of ash content. The higher calorific value obtained to the pequi bark was around 15 MJ kg-1 being similar to other agricultural leavings used to generate electrical power. The thermogravimetric analysis showed that the pequi bark has a high percentage of lignin being about 50% compared to 30% in the eucalyptus bark, the higher the amount of lignin the higher the calorific value. The results obtained showed that the pequi bark presents high using potential as a biomass to generate electrical power.

Castor oil plant is a very important crop, known worldwide for its seed oil quality. However, the crop shows serious issues with pathogens that may affect seed quality. Thus, this study aimed to evaluate the Ultraviolet-C (UV-C) radiation effects on the physiological and sanitary quality of seeds of two castor oil plant cultivars (Agima and Tamar). We used a completely randomized design in a 2 × 5 factorial scheme with four replicates. The treatments consisted of two castor oil plant cultivars: Tamar and Agima and five UV-C radiation doses: 0 – control; 10.4; 20.7; 31.1; 41.4 kJ m−2. To characterize the physiological and sanitary qualities of the seeds, we performed moisture content, germination, first counting, accelerated aging, electrical conductivity, radicle and hypocotyl length, dry mass of radicle and hypocotyl and sanity test (Blotter test). The 41.4 kJ m−2 dose of UV-C radiation reduced the incidence of Aspergillus spp. Fungus in 44.8 and 100% for Agima and Tamar, respectively. However, it has caused a reduction in the physiological quality of both cultivars. The dose of 20.7 kJ m-2 resulted in the germination increase in 66% for Agima and 50% for Tamar. Thereby, the dose 20.7 kJ m-2 provided better physiological quality results of Agima and Tamar, presenting better germination (93 and 86%, respectively), accelerated aging (43 and 65% respectively), radicle length (5.5 and 5.2 cm, respectively), hypocotyl length (1.5 and 1.7 cm, respectively), and lower electrical conductivity (54.2 and 45.2 μS cm-1 g-1, respectively). UV-C radiation can be used to better physiological and sanitary quality results of castor oil plant seed up to the dose of 20.7 kJ m−2, from which UV-C radiation negatively influences seed vigor.

Flat plate solar collectors have been widely used in low temperature thermal applications (

The quality of sesame (Sesamum indicum L.) seeds is directly influenced by their physical characteristics, which are seldom studied notwithstanding their extreme importance in the entire production chain. Therefore, the objective of this study was to quantify the physical properties of two types of sesame seeds, collected at three points in the plant with different maturation levels, measured with digital caliper, and to evaluate the feasibility of using a digital image to determine their physical characteristics. The seeds were initially evaluated for water content and mass of 1000 seeds, and later with the data of the characteristic dimensions A (length), B (width), and C (thickness), obtained by a caliper and digital images, we determined their sphericity, circularity, projected area, and geometric diameter. We observed that water content did not affect the physical properties of the cream (CNPA G4) and black sesame cultivars. In addition, seeds of the black cultivar presented higher results than the seeds of the cream cultivar for the mass of 1000 seeds (2.7 ± 0.08 g), sphericity (58.8 ± 0.47%), projected area (4.03 ± 0.12 mm2), and geometric diameter (1.65 ± 0.03 mm). Seed batches harvested after 70% maturation had the highest mass of 1000 seeds (2.7 ± 0.12 g). The results of the physical analyses of sesame seeds performed with caliper and digital image are equivalent, which shows that digital images can be used as tools to obtain the physical properties of seeds.

An investigation of resource recovery from biofuel production from microalgae is essential to increase the overall efficiency of the system. In this study, defatted biomasses of Scenedesmus obliquus BR003, with moisture contents of 2.5 and 32.5 wt%, were subjected to the slow pyrolysis process at a temperature of 450 °C under inert atmosphere and ambient pressure. The properties and yields of the products obtained by the pyrolysis process showed similar values for the two treatments. The bio-oil yield was 13.14 ± 0.87 and 16.75 ± 1,88 wt%, char yield was 45.79 ± 0.56 and 46.22 ± 0.42 wt%, and gases yield was 32.95 ± 0.72 and 31.33 ± 1.52 wt% for the treatments with lower and higher moisture content, respectively. The liquid phase presented an aqueous fraction five times greater in treatment with higher moisture content. The higher heating value (HHV) of bio-oils for treatments with 2.5 and 32.5 wt% of moisture content were 34.8 MJ kg−1 and 36.05 MJ kg−1, respectively. The bio-oil presented a low percentage of N compounds, which is a great advantage for use as fuels. Although the treatments showed negative energy balance, the use of biomass with higher moisture content, as used in this study, presents itself as an alternative to improve the production of microalgae biofuels, since it significantly reduces the energy required for drying before the pyrolysis process.

In this article, a parabolic trough solar collector (PTC) was built and evaluated in different configurations. The prototype was built to minimize the cost and complexity of construction and operation since these are the main difficulties related to the dissemination of this type of system. PTC was designed to operate stationary and the thermosyphon regime was used to eliminate pumping dependence. The evacuated glass receiver tube was connected directly to the thermal storage system, to avoid using additional connections. PTC was evaluated under different configurations, incorporating a concentrator or not, and using different heat transfer fluids (HTF): water and thermal oil. Parameters such as optical efficiency, thermal performance, and general coefficient of thermal loss were calculated. Despite reducing the thermal efficiency of the system, the use of the concentrator contributed to an increase of approximately 97% in the total useful energy gain. With the use of the concentrator, the maximum instantaneous efficiencies were obtained when the angle of solar incidence was close to zero and gradually reduces as the angle moves away from this value. The maximum overall heat loss coefficient of the system was 1.50 W K−1 demonstrating that the isolation of the PTC was adequate. The proposed system proved to be economically viable, with an average level heating cost of 0.035 US$ kWh−1. The proposed PTC is a high potential alternative for several medium temperature agro-industrial applications, where high efficiency is not necessary and ease of operation is important.

The reuse potential of passion fruit seeds to obtain functional ingredients can find many industrial applications. This requires knowledge of their physical properties for the design of conveyors and equipment. The objective of this study was to determine the physical properties of passion fruit seeds during drying and to evaluate the feasibility of using digital images to determine the dimensional properties of seeds in comparison to caliper. Passion fruit seeds with initial moisture content, in dry basis (d.b.), of 0.402 (decimal) were subjected to drying in a cylindrical tray dryer at 45 ± 2 °C to different moisture content levels and were characterized by their physical properties. Unit specific mass, mass of one thousand seeds, and seed size and shape were evaluated. The characteristic dimensions of the seeds were obtained by caliper and digital image processing. The digital image processing method was satisfactory to obtain the characteristic dimensions of passion fruit seeds. The dimensional properties did not show significant difference (P ≤ 0.05) during the drying process, indicating low contraction of the characteristic seed dimensions. The seeds presented volumetric contraction of approximately 4 %, which was represented by the Bala & Woods adapted model. The mass of one thousand seeds showed a reduction of approximately 21 % with the decrease of moisture content. The unit specific mass ranged from 1121 to 1022 kg m-3 for moisture contents of 0.402 and 0.047 (decimal, d.b.), respectively. These results indicate that the separation of passion fruit seeds as a function of moisture content should be performed by densimetric methods.

The conditions of temperature and airflow distribution in the mass of stored grains are highly influenced by the configuration of the aeration ducts. However, silos are large structures, and the physical experiments on them become expensive and slow. Thus, this study aimed model and evaluate the temperature and airflow distribution in a maize mass, stored in a metal silo with different geometries of aeration ducts, using CFD (computational fluid dynamic). CFD was used to model and evaluate aeration ducts of square, ring, double bar and single bar shape. The proposed model was validated from experimental data. The airflow distribution and temperature in the grain mass were analyzed at different points. The ducts of a square and a ring shape showed better distributions of airflow in the grain mass, with averages of 0.00236 m s-1 and 0.00275 m s-1, respectively. The square shape aeration duct, presented better temperature values in the middle layer of the grain mass during aeration, with average 25.09 °C. CFD can be used in decision making for the best design of a silo, saving financial resources and time, as long as the parameters used in the simulation are reliable and represent the reality.

To obtain quality milk, several hygiene measures must be taken during the milking process, especially cleaning the milking parlor and equipment using hot water. Thus, the objective of this study was to carry out the sizing and economic feasibility of two solar water-heating systems: flat plate solar collector (FPC) and evacuated tube solar collector (ETC) to clean milking parlors in the interior of Brazil. The sizing and economic feasibility of applicability of this study was carried out for a dairy farm located in the city of Anápolis-GO, Brazil. We calculate the energy produced by the solar collector, the necessary number of collectors, the net present value (NPV) and the time of return (RT) for all systems. The ETC presented higher energy produced per unit area (8590 to 12 979 kJ m-2 day-2) than the FPC (6472 to 8699 kJ m-2 day-2). Furthermore, it presented a total required area around 33.5% lower when compared to the FPC. The system that obtained the lowest total cost was the ETC with approximately US$ 34 441.00. The two systems had positive NPV, and for ETC, this value was 7.2% higher. The return times for FPC and ETC were 3 years and 2 months and 2 years and 10 months, respectively. Both systems have proven their economic viability for heating water from milk producing properties, and may be an option for regions without energy access. In addition, the use of these systems contributes to the reduction of production costs and environmental impacts.