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The objective of this study is to thermodynamically investigate the performance of solar dryers by delaying the airflow in the collector. For this reason, a triple air path on a single pass collector with the fan powered by a wind generator was developed and evaluated in a very humid climate. The evaluation parameters were drying efficiency, energy and exergy analysis, sustainability assessment, CO2mitigation ability and effective moisture diffusivity of dried product. The results showed that the collector efficiency of triple air passage path collector designs improved the direct passage collector by 119%. The overall collector and drying efficiencies were 8.43% and 2.6% higher than the direct flow path collector. The specific energy consumption was 1.1033 kWh/kg while the specific moisture extraction rate was obtained as 0.273 kg/kW, respectively. The average exergy efficiency ranged between 38.09 and 63.81% while the waste exergy ratio, improvement potential and sustainability index for the three dryers ranged from 0.00 to 1.13, 7.54 × 10–7to 2.003 kW and 0.00 to 11.47, respectively. Using the solar dryers instead of the coal-powered dryer will mitigate more CO2into the atmosphere in the range of 9741.334 to 21,481. 476 tons of CO2per year while using grid-based electricity will limit the least amount of CO2in the range of 12.981 to 14.153351.50 tons of CO2per year.

The paper presents the environmental sustainability of the Nigeria transport sector (NTPS) through the decomposition and decoupling analysis from 1988–2019. The study’s objective is to determine ways of saving energy in the NTPS and reduce carbon emission for a sustainable environment. The approach was based on the Logarithmic Mean Divisa Index (LMDI) and the Tapio approach, built on Kaya extended identity. Five decoupling indicators were considered based on the four energy carriers consumed in the NTPS. The indicators include economic activity, energy structure, economic structure, population and energy intensity. The results identified three decoupling states, weak negative decoupling, weak decoupling and strong decoupling. The energy intensity, economic activity, population and energy structure prevented decoupling during the study period, while the economic structure factor promoted decoupling. The overall impact of carbon emissions from NTPS was calculated at 44.45 million tonnes of CO2. The study suggests frameworks that will support policy makers to formulate broad base policies for environmental sustainability.

An analysis of review articles on solar drying of agricultural products is presented. The review also discusses detailed economic evaluation methods and market participation approaches for transitioning solar dryers from the workshop to the market. This study aims to serve as a model for future solar drying reviews. In addition to broad perspective reviews, most reviews focused on using thermal storage, hybrid technologies, solar greenhouses, 4E evaluations, software applications and crop quality. From most of the reviews, solar dryers with thermal storage are now a viable substitute for fossil energy source dryers and can provide the continuous temperature range of 40–60 °C required to dry food crops. When phase change material is deployed, the transition temperature should be at 5 °C above the desired drying temperature. However, all reviews included sections on types, classification, mode of airflow through the collector, and use of thermal storage in solar drying. Hence, the authors review nearly the same research material, but review gaps remain. Thus that aspect was covered by examining the economic and exergoeconomic analysis methods used in solar dryer evaluations. Again agribusiness inter-phasing between researchers and users, which will spore market participation of solar dryer fabricators lacking in the literature were presented. Therefore, for a more market-oriented development of solar thermal technologies, solar dryer producers must engage in market-oriented production. The nature of markets located at different places calls for better strategies to improve market orientation and access to solar dryers and fabricators.

The study presents a power-cooling organic Rankine cycle with an ejector system (ORCPCES). The objective is to determine the thermodynamic, economic and sustainability of the ORCPCES from the manufacturing, commissioning and decommissioning phases. Component-wise modelling was first performed based on the exergy concept. The system simulation was carried out using a developed source code in Engineering Equation Solver (EES). The refrigerant leakages and the material component impact on the environment were evaluated at all phases of the plant life cycle. The results indicate that the evaporator cooling rate (ECR) and the power-cooling efficiency (PCE) varied from 120.8 to 153 kW and 28.87 to 34.43 % across the refrigerants with the highest PCE and exergy efficiency obtained using R1234ze. The maximum power output was obtained using R1234ze. The overall environmental impact due to the components occurred at5.1×105mPts, 5.24×105mPtsand 5.4×105mPtsfor R245fa, R1234yf, and R1234ze, respectively, while 4.01×105mPts7.81×104mPtsand9.33×105mPtswas due to the working fluids in that order. The unit cost of electricity (UCOE) across the refrigerants varies from 0.181$/kWh to 0.2291$/kWh with the least UCOE, 0.181$/kWh obtained using R1234ze. The highest exergetic sustainability index of 0.56 was achieved using R1234ze.