Optimizing Solar Drying: A Critical Review of Shapes, Orientation, and Future Prospects for Hybrid Solar Dryers

This comprehensive review focuses on the performance of solar dryers, with a specific emphasis on their structural shape and orientation. Researchers have extensively examined these design parameters, often employing Computational Fluid Dynamics (CFD) to assess thermal attributes and predict temperature distribution, airflow patterns, and temperature profiles within the structures. Geographical location significantly influences solar dryer shape preferences, with the parabolic shape finding favor in tropical regions for its superior solar radiation capture and storm resistance, while even-span and Quonset shapes are popular elsewhere. Solar dryer orientation is another crucial factor, with east-west alignment consistently proving optimal due to its ability to maximize year-round solar radiation absorption and, consequently, enhance drying efficiency. Economic considerations, however, fall beyond the scope of this review, which predominantly focuses on thermal aspects. This investigation reveals diverse global preferences for solar dryer shapes and orientation, highlighting the necessity of considering geographical factors in design choices. While CFD and shape/orientation dynamics have provided valuable insights, there remains room for future research to expand into transient state simulations under various conditions, contributing to a more comprehensive understanding of solar dryer performance. Such insights promise to promote sustainable and efficient drying processes, benefitting agricultural and drying applications across the globe.

Dissemination paradox:how contextual realities influence smallholder farmers'modifications of agroforestry technologies in Uganda's Mt.Elgon region

This study was intended to understand how smallholder farmers’modifications improved agroforestry technologies’usability in Uganda’s Mt.Elgon region.We used a case study approach to understand how smallholder farmers’contextual realities informed their modifications and enhanced the usability of agroforestry technologies.Data was collected over four months of frequent and regular interaction with the cases using formal and informal methods that included in-depth interviews,conversations,discussions,and direct observations.Emerging themes and patterns were identified from the comprehensively reduced data.In addition,respondents’direct quotes were used to emphasize the reasons for the modifications.The findings showed that smallholder farmers modified the recommended technologies to suit their biophysical and socio-economic realities.Differences and similarities in modifications existed among cases across the agroforestry technologies.The modifications were mainly done to diversify tree uses,optimize space utilization,and minimize production costs for farming households.These findings imply a need to critically examine the smallholder farmers’modifications to make agroforestry technologies applicable and compliant to their contexts.This will inform the re-invention of technologies that will quickly diffuse into the community for broader impact.Findings also emphasize the need to rethink the linear model of technology transfer mainly applied in agroforestry technology development and dissemination because it offers limited space for the much-needed feedback from smallholder farmers.

Variation of basic density,calorific value and volumetric shrinkage within tree height and tree age of Ugandan grown Eucalyptus grandis wood

Insufficient knowledge on Ugandan grown Eucalyptus grandis W.Hill ex Maiden wood properties,high demand,and processing challenges led to a study into its physical properties.We obtained the variation of basic density(BD),calorific value(CV)and volumetric shrinkage(VS)within tree height and tree-age of E.grandis,and its appropriate use based on these properties.Trees with good boles were harvested from Kabarole District in western Uganda to produce specimens as prescribed by British Standards and ASTM standard wood testing procedures.Secondary data reviews and statistical analysis using ANOVA,Tukey’s test and multivariate analysis were done to obtain property estimates and their variation within trees and amongst tree ages.The mean BD of E.grandis is 413.6,380.5,471.0,and 501.1 kg m^(−3)at 3,6,9,and 12 years,respectively,showing significant increase with tree age(p=0.003).The pattern of BD with tree height showed a reduction with tree height although with higher values in the middle portion of the tree.The CV increases(p=0.014)with tree age and reduces with tree height with values of 14,560.32,15,447.3,16,079.11,and 16,932.6 kJ kg^(−1)at 3,6,9,and 12 years,respectively.The percentage VS was 11.02,9.84,12.31,and 14.45 for 3-,6-,9-,and 12-year-old trees,respectively,and it did not vary significantly(p=0.088)with tree height.Basing on these property values,E.grandis wood could be used for scaffolding,light constructions and fuel wood production.Its seasoning needs to be longer with well monitored drying schedules to reduce seasoning defects caused by the high VS.Further studies on strength properties,seasoning schedules,panel products properties and tree-age chemical variations would improve the knowledge about its wood quality and would enhance its efficient utilization.