The fruit of the date palm (Phoenix dactylifera L.) is one of the most abundant fruits in the world. Hundreds of varieties having different texture, color, and flavor are available for valorization ...and adoption in food processing operations. Such utilization should be based on the fruit valuable characteristics; mainly its richness in dietary fiber and phenolic antioxidants.
This review article complements these existing reviews by primarily addressing the chemistry and processing of date fruits pulp and seeds with particular emphasis on dietary fiber and antioxidants as linked to important fruit processing and utilization features.
Date fruits contain 6.5–11.5% total dietary fibers (of which 84–94% insoluble and 6–16% soluble dietary fiber) and is very rich in phenolic antioxidants (1–2%) especially condensed tannin pigments based on (−)-epicatechin oligomers. Date seeds contain about 15% of fiber, characterized by a high level of water-insoluble mannan fibers. Date fruits are widely available in the global market, mainly at mature Tamr stage, but there is still room for improvement. It has been suggested that date fruits and seeds can be exploited in some food applications utilizing their high levels of fiber and antioxidants. The incorporation of date fruits and seeds as food ingredients is still growing with the aim to promote the presence of dates in the modern's consumer shopping basket.
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Purpose - The purpose of this paper is to develop an effective methodology for implementing lean manufacturing strategies and a leanness evaluation metric using continuous performance measurement ...(CPM).Design methodology approach - Based on five lean principles, a systematic lean implementation methodology for manufacturing organizations has been proposed. A simplified leanness evaluation metric consisting of both efficiency and effectiveness attributes of manufacturing performance has been developed for continuous evaluation of lean implementation. A case study to validate the proposed methodology has been conducted and proposed CPM metric has been used to assess the manufacturing leanness.Findings - Proposed methodology is able to systematically identify manufacturing wastes, select appropriate lean tools, identify relevant performance indicators, achieve significant performance improvement and establish lean culture in the organization. Continuous performance measurement matrices in terms of efficiency and effectiveness are proved to be appropriate methods for continuous evaluation of lean performance.Research limitations implications - Effectiveness of the method developed has been demonstrated by applying it in a real life assembly process. However, more tests applications will be necessary to generalize the findings.Practical implications - Results show that applying the methods developed, managers can successfully identify and remove manufacturing wastes from their production processes. By improving process efficiency, they can optimize their resource allocations. Manufacturers now have a validated step by step methodology for successfully implementing lean strategies.Originality value - According to the authors' best knowledge, this is the first known study that proposed a systematic lean implementation methodology based on lean principles and continuous improvement techniques. Evaluation of performance improvement by lean strategies is a critical issue. This study develops a simplified leanness evaluation metric considering both efficiency and effectiveness attributes and integrates it with the lean implementation methodology.
Abstract
It is widely accepted that student learning is significantly affected by assessment methods, but a concrete relationship has not been established in the context of multidisciplinary ...engineering education. Students make a physiological investment and internalize learning (deep learning) if they see high value in their learning. They persist despite challenges and take delight in accomplishing their work. As student deep learning is affected by the assessment system, it is important to explore the relationship between assessment systems and factors affecting deep learning. This study identifies the factors associated with deep learning and examines the relationships between different assessment systems those factors. A conceptual model is proposed, and a structured questionnaire was designed and directed to 600 Queensland University of Technology (QUT) multidisciplinary engineering students, with 243 responses received. The gathered data were analyzed using both SPSS and SEM. Exploratory factor analysis revealed that deep learning is strongly associated with learning environment and course design and content. Strong influence of both summative and formative assessment on learning was established in this study. Engineering educators can facilitate deep learning by adopting both assessment types simultaneously to make the learning process more effective. The proposed theoretical model related to the deep learning concept can support the key practices and modern learning methodologies currently adopted to enhance the learning and teaching process.
A large amount of energy is consumed by heating and cooling systems to provide comfort conditions for commercial building occupants, which generally contribute to peak electricity demands. Thermal ...storage tanks in HVAC systems, which store heating/cooling energy in the off-peak period for use in the peak period, can be used to offset peak time energy demand. In this study, a theoretical investigation on stratified thermal storage systems is performed to determine the factors that significantly influence the thermal performance of these systems for both heating and cooling applications. Five fully-insulated storage tank geometries, using water as the storage medium, were simulated to determine the effects of water inlet velocity, tank aspect ratio and temperature difference between charging (inlet) and the tank water on mixing and thermocline formation. Results indicate that thermal stratification enhances with increased temperature difference, lower inlet velocities and higher aspect ratios. It was also found that mixing increased by 303% when the temperature difference between the tank and inlet water was reduced from 80 °C to 10 °C, while decreasing the aspect ratio from 3.8 to 1.0 increased mixing by 143%. On the other hand, increasing the inlet water velocity significantly increased the storage mixing. A new theoretical relationship between the inlet water velocity and thermocline formation has been developed. It was also found that inlet flow rates can be increased, without increasing the mixing, after the formation of the thermocline.
The Kingdom of Saudi Arabia (KSA) has witnessed a huge increase in construction during the last two decades. However, many projects experienced time delays, cost overruns and the generation of ...massive amounts of waste. To address these challenges, lean construction has been introduced into the Saudi construction industry; however, it is still in its infancy. This study therefore investigates the current state of lean construction implementation in the construction industry in the KSA. The objectives are to identify: the types of construction waste, level of use of tools that support the implementation of lean construction, stages of application of lean methods, and the benefits of lean construction. To achieve these objectives, a structured questionnaire survey of 282 construction professionals was carried out. After the analysis of the collected data using mean score and Anova test, the following conclusions were made. In the construction industry in the KSA, waiting is the most common type of waste, while Computer Aided Design (CAD) is the conventional tool supporting the implementation of lean construction. Furthermore, the data suggests that lean construction is most commonly used in the construction stage of projects while customer satisfaction is the main benefit derived from lean construction practices. This study concludes that the level of implementation of lean construction in the KSA construction industry is increasing. The results will help benchmark the current state of lean construction implementation, which will enable the construction industry to identify strategies to implement lean construction in Saudi Arabia in accordance with their needs and project goals, to achieve better productivity.
•Thermodynamic model and experimental validation of v-groove solar dryer.•Optimum flow rate of air within the collector was obtained for maximum efficiency.•SEC was 3.01 kWh/kg at 0.041 kg/s with ...59 % energy saving for apple drying compared with electricity driven heating.•Sustainability indices of the solar air collector and dryer are 1.50 and 1.047 respectively.•Energy payback period for the system is less than 1 year.
Optimised solar air dryers, in terms of efficiency and performance, can solve some major concerns in the agro-industrial processing sector. Solar air dryers can reduce the large share of energy costs of a final product and can provide sustainable energy in rural areas where access to energy is often limited. In this study, a pilot scale v-groove double pass solar air collector has been analysed thermodynamically with real time solar radiation and mass flow rate (0.021–0.061 kg/s) inputs and validated experimentally in terms of first and second law efficiencies. Performance of the process was assessed using experimental drying measures including final moisture content, drying rate and exergy efficiency for drying of Pink Lady apples. Energy payback time and specific energy consumption were calculated to reveal the techno-economic value of the system. The maximum thermal efficiency of the collector was observed to be 88.8 % at 0.061 kg/s having exergy efficiency of 6.6 % which shows an efficient sourcing for the operation. In terms of the performance of the dryer, mass flow rate of 0.041 kg/s offers a higher moisture removal. Specific energy consumption (SEC) was 3.096 kWh/kg. Thermodynamic model was validated with matching experimentation with acceptable RMSE for the range of investigated measures. Energy payback period time calculated by the embodied energy of the system was obtained to be 0.78 years which implies that the system is capable of addressing a large capacity drying if it is to be scaled-up.
Supply disruptions, uncertainty, and unprecedented price rises of fossil fuels due to the recent pandemic and war have highlighted the importance of using renewable sources to meet energy demands. ...Solar air collectors (SACs) are major types of solar energy systems that can be utilized for space and water heating, drying, and thermal energy storage. Although there is sufficient documentation on the thermal analyses of SACs, no comprehensive reviews of the exergetic performance or qualitative insight on heat conversion are available. The primary objective of this article is to provide a comprehensive review on the optimum conditions at which the thermal performance of diverse types of solar air collectors is optimized. The effect of operating parameters such as temperature rise, flow rate, geometric parameters, solar radiation, and the Reynolds number on the thermal performance of SACs in terms of thermal hydraulic performance, energy, and exergy efficiencies has been reviewed adaptively. Beyond the operating parameters, a deep investigation is outlined to monitor fluid dynamics using analytical and computational fluid dynamics (CFDs) methodologies in the technology of SACs. In the third phase, thermodynamic irreversibility due to optical losses, thermal losses between absorber and environment, heat losses due to insulation, edge losses, and entropy generation are reported and discussed, which serve as the fundamental tools for optimization purposes.
While the circular shape is currently the proven optimum design of the energy collection element (ECE) of a parabolic trough collector, that is yet to be confirmed for parabolic trough concentrating ...collectors (PTCCs) like trough concentrating photovoltaic collectors and hybrid photovoltaic/thermal collectors. Orientation scheme of the ECE is expected to have significant effect on the optical performance including the irradiance distribution around the ECE and the optical efficiency, and therefore, on the overall energy performance of the PTCC. However, little progress addressing this issue has been reported in the literature. In this study, a thorough investigation has been conducted to determine the effect of the orientation schemes of ECE on the optical performance of a PTCC applying a state-of-the-art Monte Carlo ray tracing (MCRT) technique. The orientation schemes considered are a flat rectangular target and a hollow circular, semi-circular, triangular, inverted triangular, rectangular and rectangle on semi-circle (RSc). The effect of ECE defocus, Sun tracking error and trough rim angle on the optical performance is also investigated. The MCRT study reveals that the ECE orientation schemes with a curved surface at the trough end showed much higher optical efficiency than those with a linear surface under ideal conditions. ECEs among the linear surface group, the inverted triangular orientation exhibited the highest optical efficiency, whereas the flat and triangular ones exhibited the lowest optical efficiency, and the rectangular one was in between them. In the event of defocus and tracking errors, a significant portion of the concentrated light was observed to be intercepted by the surfaces of the rectangular and RSc ECEs that are perpendicular to the trough aperture. This is an extended version of a published work by the current authors, which will help to design an optically efficient ECE for a parabolic trough concentrating collector.
The overall thermal performance of a Parabolic Trough Collector (PTC) depends on its optical performance, particularly the uniformity of the irradiance distribution and the resultant optical ...efficiency of the collector. Local Concentration Ratio (LCR), optical efficiency and average light concentration are three fundamental parameters of the optical performance of a PTC. These parameters are affected by various optical and physical factors. The effects of these individual factors on the performance parameters were investigated in this study using a verified Monte Carlo ray tracing optical simulation model. The investigation revealed that all three performance parameters are directly related to the optical properties of the collector components. The values decreased gradually with the increase of focal length of the mirror. Uniformity of the LCR profile was observed to decrease with increasing rim angle and geometric concentration. Defocus dislocation of the receiver was found to improve the uniformity of the LCR distribution by decreasing its peak concentrations, Cmax. Off-focus dislocation of the receiver, and inward angular deviation of the mirror profile were observed to increase the Cmax and decrease the uniformity of the LCR distribition. Out-focus dislocation of the receiver and solar tracking error distort the bi-symmetry of a normal LCR profile.
Food drying is a highly energy intensive process and therefore significantly contribute to carbon emission. Although solar air dryers are considered renewable, they are not fully emission free as ...conventional energy from grid is required to run the fan or blower. The solar air efficiency as well as fan power requirements are influenced by the mass flow rate of air, and therefore flow rate is essential parameter for evaluating solar air dryer performance in terms of thermal, drying and environmental parameters. It is essential to develop a framework to evaluate critical mass flow rate by considering the optimum thermal, drying, and environmental performance for benchmarking of zero-emission solar air dryer. However, such a framework is currently lacking. To address this issue, a novel study was conducted using V-groove double pass solar air heater (SAH) to experimentally analyse thermal, drying and environmental parameters to develop a methodology for zero emission solar air dryers based on critical flow rate for fan power consumption. The experiments were conducted at five different flow rates (0.021, 0.031, 0.041, 0.051, and 0.061 kgs−1). The maximum thermal efficiency achieved was 74.89% at 0.061 kgs−1. However, the average COP, average exergy efficiency, moisture ratio, and CO2 mitigation had optimum results at 0.041 kg/s mass flow rate as fan power consumption was reduced by 16% compared to 0.061 kgs−1. The critical flow rate evaluation is useful for predicting and minimising power consumption and progress towards zero emission system by using photovoltaics in future systems. The successful implementation of the proposed method can substantially contribute to the industrialisation and cutting of emissions of solar air heaters for drying applications.
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