Journal of Energy Research and Reviews

Aims: Analyze the thermal quality provided by the building elements of Huichol vernacular housing concerning the climatic conditions of San Andrés Cohamiata, Jalisco.

Study Design: The analysis was performed through a simulation of computer housing, for which the characteristics of the materials and EPW (Energy Plus Weather) data of 2018 from the study area were applied to the model, analyzed in programs such as 2D Sun-Path, 3D Sun-Path and Opaque.

Place and Duration of Study: Universidad Autónoma de Querétaro, Graduate of Architecture, Faculty of Engineering, between January and March 2019.

Methodology: First, a bibliographic and field study was carried out to verify the materials and construction processes of Huichol housing. The computer housing model was designed to apply the characteristics of the materials, as well as the location and orientation handled by the Huichol ethnic group. Subsequently, EPW (Energy Plus Weather) data from the study area were introduced to opaque software to perform thermal analysis of the house and various factors are studied such as thermal mass and insulation, heat gain/loss, direct radiation, diffuse, dry bulb temperature, among others. Also, in software such as 2D Sun-Path and 3D Sun-Path, the study of sunbathing and shadows of the house was carried out.

Results: The orientation of the house allows them to make better use of solar radiation at different times of the year. Its construction elements (wall thickness, material, and ceiling structure) decrease the overheating of the space in summer. Adobe walls have a thermal delay of 4 hours, and internal conditions are optimal to maintain thermal comfort in summer and winter. Internal temperatures during the year range from 20 to 25°C.

Conclusions: Huichol culture has important knowledge in the construction with natural materials, as these allow positive thermal behaviour in the face of the climatic conditions of the area throughout the year. These housing characteristics may apply to other ethnic groups in the region with limited economic resources, to improve their living conditions.

The fossil energy sources used in the world are gradually decreasing and limited. Fossil fuels cause environmental pollution, and the unit price is constantly increasing. For this reason, demand for cheaper and renewable energy sources that do not pollute the environment is increasing day by day. The sweet sorghum plant has attracted attention in recent years with its high biomass yield, sugar content and bioethanol yield. In this study, it was aimed to determine the bio-fuel potential of some sweet sorghum genotypes in semi-arid climatic conditions. The experiment was set up in randomized complete block design with 4 replicates. Research was carried out in 2015 under Harran Plain (36^o 42’ N and 38^o 58’ E) second crop conditions, Sanliurfa, Turkey. In the study 49 genotypes of sweet sorghum were used. Stalk yield, juice yield, syrup yield, brix, sugar yield and theoretical ethanol yield were determined in the study. Significant differences were found between the genotypes for tested characteristics (P≤0.01). Stalk yield ranged from 7110.0 kg da^-1 to 24262.5 da^-1, juice yield from 2550.0 L da^-1 to 12187.5 L da^-1, syrup yield from 291.4 L da^-1 to 2242.5 L da^-1. Also, brix value varied between %7.0 and %18.87, sugar yield between 247.7 da^-1 and 1906.1 da^-1, Theoretical ethanol yield between 131.9 L da^-1 and 1014.8 L da^-1. Considering to stalk yield, juice and syrup yield, brix, sugar yield and theoretical ethanol yield; Nebraska sugar, Topper 76, Smith, M81E and Corina genotypes were found as the best. As a result of research, 21 genotypes with better performance than the others were selected for further studies.

The present work was focused on the experimental investigation of a double air pass solar collector which was designed and constructed at the Laboratory of Energetic and Thermal Applied of the National School of Agro-Industrial Sciences of the University of Ngaoundere. It consists of a double glazed cover with a surface of 0.47 m², an absorbent plate and a layer of thermal insulation. It allows simultaneous circulation and the same flow direction of the working fluid (air) on both side of the absorber. The experimental tests were conducted outdoor, in natural environment of Ngaoundéré city, during one month period, from 4 to 30 of April, between 9:00 am and 5:00 pm, local time. The research aim was to characterize, on one hand, the local weather conditions (solar radiation, ambient temperature, relative humidity and wind velocity), and on the other hand the collector performance. The solar collector was permanently oriented towards the South and tilted by 45° with respect to the horizontal plane. The analysis of the temperature profiles of different components  of the collector showed that the maximum temperature was reached at 2:30 pm, when solar radiation was 1217 W/m² and they were 73.9°C, 61.7°C and 44.7°C for absorber, inner glass  and outer glass, respectively. As concerning the outlet temperature of the heat transfer fluid, the analysis of the results shows that it goes up to 58.4°C and 52.2°C, while thermal efficiency was as high as 47.81% and 65.57% when the air flow velocities were setup at 0.5 m/s and 1.5 m/s, respectively.

This work concerns the energy efficiency study and analysis of a gas roasting oven developed by a local craftsman. The oven energy efficiency was determined by the Water Boiling Test (WBT) method. The temperatures of the walls as well as the ambient temperature were recorded to evaluate the heat losses by convection towards the environment. The energy balance of the oven then allows to calculate the heat losses from the fumes. The results show that the heat losses by fumes through the chimney are the greatest (50% of the energy consumed). Losses through the walls are relatively low (15%). The oven efficiency is around 35%, which is relatively low. These results show that optimization work must be carried out in order to improve the energy efficiency of the equipment.

La₂Ti_2-xNb_xO₇ (x = 0.00, 0.05, 0.10, 0.15, 0.20, 0.25) powders were synthesised via solid state reaction method, followed by sintering at 1673 K in a reducing atmosphere of 5% H₂/N₂ gas. The crystal structure, microstructure and thermoelectric (TE) properties of the pure and Nb-doped La₂Ti₂O₇ ceramics were investigated. All compositions were single phase with porous microstructures consistent with their low experimental densities. Thermoelectric results of Nb-doped compositions showed improved properties in comparison to pure La₂Ti₂O₇, suggesting that cation doping has the potential to improve the thermoelectric properties. Generally, the TE results obtained are not suitable for thermoelectric applications. However, the high Seebeck coefficient (≥190 μV/K) and glass-like thermal conductivity ( ≤2.26 w / m.k )  values achieved have opened a new window for exploring the thermoelectric potentials of La₂Ti₂O₇ and other related oxides.