Cleaner Engineering and Technology最新文献

This study aimed to enhance the efficiency of the solar water heater (SWH) due to the increasing demand of renewable energy. It compared use three different solar collector models, namely Model A (square-shaped polycarbonate), Model B (v-corrugated zinc), and Model C (trapezoidal aluminium) to identify the most cost-effective configuration. The models were subjected to experiments in real operating conditions during the summer season in Indonesia. Various parameters, including solar radiation intensity, wind speed, inlet and outlet temperatures, and flow rate, were measured every 10 min from morning to afternoon. Additionally, the study employed a trickle and one-way flow rate system. The results showed that Model B achieved the highest total efficiency at 50%, followed by Models A and C at 47% and 34%, respectively. The 120 Lph flow rate exhibited better performance in absorbing useful heat energy than the 240 Lph flow rate. Based on these findings, all three models were recommended for the household-scale SWH applications. Model A showed the most promising economic value but had a shorter lifespan due to the tendency of polycarbonate to deform. In contrast, Model B and Model C, using zinc and aluminium, offered longer lifespans.

3D printing in construction presents numerous advantages, such as geometric flexibility, potential cost and time savings, the incorporation of recycled and sustainable materials, and reduced waste, thereby reducing the construction sector's environmental impact. Despite these advantages, the widespread adoption of AM in construction faces hurdles, primarily due to the prohibitive costs of large-scale concrete printers — typically ranging from $180,000 to over $1 million — and technological constraints that impede research and development efforts within the construction sector. To address these challenges, our study focuses on designing, developing, calibrating and evaluating an affordable lab-scale 3D printer specifically tailored for cement-based materials, aiming to lower the entry barrier for AM research in construction. This paper presents a proof-of-concept for a simple, yet functional printing technology that meet the requirements for research studies. The study details the development process, from the conceptual design to the calibration of printing parameters. The development process included the assessment of preliminary extrusion system designs integrated with the motion systems of a fused deposition modeling 3D printer. Subsequently, material studies were carried out to determine optimal material mix compositions and ratios. A comprehensive calibration of printing parameters using statistical analysis was proposed to ensure consistent and quality printing. The printability and applicability of the proposed small-scale 3D printer were assessed by printing samples and testing their thermal properties. Cost analysis showed that the proposed 3D printer, costing $273, offers benefits compared to existing market alternatives. The study illustrates the potential of small-scale 3D printers to facilitate construction research and practices, thereby promoting the development of sustainable construction methods.

In the agricultural industry, coconut shells are one of the most generated wastes worldwide. In particular, studies in the Philippines show that the maximum capacity of the organic decomposition processes of agricultural products is exceeded due to the increasing agricultural activities. On the other hand, in the construction industry, cement production accounts for billions of tons of carbon dioxide emissions yearly. To address the said biowaste disposal problem, and environmental implications of the growing construction industry, this study evaluated the potential of utilizing coconut shell ash (CSA) and coconut shell granules (CSG) in concrete production as alternatives to cement and sand, being the conventional aggregates, respectively. Additionally, coconut coir (CC) was incorporated as fiber reinforcements in concrete. The experiment consisted of 15 mix designs using different proportions of CSA and CSG, ranging from 0% to 20%, and CC fiber reinforcements, ranging from 0% to 2%. The tests conducted on fresh concrete involved measuring its slump and unit weight, while the 28-day cured samples were tested for compressive and tensile strengths. Results showed that high concentrations of CSA, CSG and CC, when combined in the concrete mix, leads to poor workability; on the other hand, the modified mixes generally had lower unit weights than the conventional concrete. These are associated to the higher absorption rate, but lower density of the said agri-wastes than the conventional aggregates. In terms of the compressive and tensile strengths, all modified mixes produced lower strengths than the conventional concrete. Nonetheless, Response Surface Methodology (RSM) was utilised to model the relationship between the different independent variables considered in the study, namely CSA, CSG and CC contents, and their corresponding response to the compressive and tensile strengths. Based on the generated RSM Model, the optimum combination for obtaining the maximum strength consisted of 2% CC, resulting in a compressive and tensile strength of 23.046 MPa and 3.315 MPa, respectively. Overall, CSG-CSA coconut coir reinforced concrete is found to be a viable sustainable alternative for structures requiring low-strength, non-structural concrete, such as concrete slab patios and pathways.

This study presents a conceptual design of an Internet of Things (IoT) communication system for monitoring power generation systems in Colombian Non-Interconnected Zones (NIZs), which lack IoT connectivity due to complex geographical factors. The proposed system aims to ensure the proper operation and energy efficiency of off-grid systems while tracking the variables that influence their performance.

The methods used in this study include identifying the needs of such a system, identifying requirements, obtaining technical specifications, and developing a conceptual design. The study also analyses and compares various technologies, including Wi-Fi, Bluetooth, LoRa and ZigBee, to determine which ones are best suited for IoT system design.

The conceptual design of the proposed IoT monitoring system considers the geographical, communication and coverage characteristics of the NIZs and the technical characteristics of the energy projects to provide a complete functional system that can connect approximately 2 million people located in these isolated and vulnerable zones. Finally, the defined system can serve as a precedent for building prototypes in various NIZs, and research on IoT technologies suitable for NIZs can help us seek the technologies that are most suitable for these areas. Depending on the application and conditions of the energy project, the most appropriate technology can be determined on a case-by-case basis.

Solar collectors may receive significantly more solar radiation if some kind of Sun tracking is utilised. Optimal collector tilt angles, however, depend on the geographic location and other parameters including solar insolation for the site. In this study, daily, monthly, biannual and annual optimum tilt angles are calculated using a tilt angle-latitude relation model. The data are then used to obtain monthly and yearly optimum tilt angles through weighted averages considering the yearly fluctuations in solar radiation. The optimum annual tilt angle for Dar es Salaam is found to be 5.3° northwards, whereas biannual tilt angles due south and north are 10.5° and 18.9°, respectively. Analysis on the energy collection by a north-south tracking solar collector revealed an improvement of about 5% with optimum daily and monthly tilting, 4.3% with biannual tilting and about 0.8% with annual tilting, compared to a fixed horizontal collector. The results from this study provide optimal tilt angles for Sun tracking in Dar es Salaam and significant gain in energy collected by the solar collector may be realized through daily, monthly or biannual tracking of the Sun.

This study evaluates the heat transfer and performance characteristics of a solar air heater (SAH) equipped with spring-wire turbulators using a 3D verified CFD simulation process. Five different shapes of spring-wire (as shown in the graphical abstract) are investigated and compared to a flat SAH (without turbulator). The effects of helical diameter, pitch, and wire diameter on the performance of the system are comprehensively analyzed for all five mentioned geometries. The results reveal that the turbulator significantly enhances the thermal efficiency of the SAH within the absorber section. Rectangular cross section shape shows higher enhanced Nu number compared to the other cross section shapes. However, considering both heat transfer and pressure drop, the circular turbulator exhibits the optimal performance. Larger helical diameter, helical pitch and wire diameter, augments, decreases and increases the value of Nu/Nu_s respectively. Generally, higher increased Nu number also shows higher pumping power as well and that is why thermohydraulic performance parameter (THPP) is considered as well. Larger helical diameter, and helical pitch decreases and increases thermohydraulic performance respectively. For instance, the circular turbulator's THPP rises by approximately 17.5% as the pitch increases from 50 mm to 250 mm. However, the impact of wire diameter on THPP does not show a unified curve trend and depends on the shape of the turbulator. This study is remarkably useful for optimizing the performance of SAHs with turbulators, paving the way for enhanced device efficiency.

The aim of the study is to produce a solid biofuel of high physico-mechanical and energetic quality from heat-treated cashew nut shells. Raw cashew nut shells are heat treated at 300 °C for 120 min at a heating rate of 1 °C/s. The resulting biochar is milled to 74 μm. Sugar cane molasses was incorporated into the biochar powder at a rate of 10% without the addition of water. The mass yields of solid, liquid and gaseous products obtained were 46.5%, 27.6% and 25.9% respectively. The solid biofuel produced has slightly improved physicochemical and energy properties over biochar, except ash and moisture content. Thus, the addition of binder and densification increased the ash and moisture content of the solid biofuel compared to the biochar obtained. With a higher calorific value of 33.02 MJ/kg, the solid biofuel has high water resistance and meets the quality requirements of class A1 of the NF EN ISO 17225-6 standard in terms of density and mechanical strength. Solid biofuel is ideal for use in households and biomass power stations.

Due to rapid urbanization and uncontrolled population growth, solid waste management has become a rising issue in developing nations like Bangladesh. Khulna ranks third among Bangladesh's metropolitan cities. The existing system of Khulna City for transporting municipal solid waste lacks route planning and depends exclusively on the driver's expertise. Hence, this study aims to minimize the length of the present travel paths and assess the advantages of using optimized routes. Secondary datasets like a list of vehicles, financial information, and a list of secondary transfer stations have been collected from the municipality. A field survey was conducted to capture the coordinates of secondary transfer stations. Multiple GPS devices have been installed for monitoring the current paths, stops, and travel time of 31 waste collector vehicles for 10 months. A network database has been prepared and modified by integrating driver's perceptions and field inspection. Network analysis of ArcGIS Pro has been used for finding the optimized routes. The optimized route minimizes the travel distance by 9.40%. By following the optimized routes, about 11.6% of fuel costs can be reduced. This research has the potential to make a significant contribution to the waste management of Khulna City and beyond.

In Indonesia, rapid population growth has increased energy demand, especially in the transportation and power generation sectors. The Indonesian government has been active in promoting the use of renewable energy, but the transition from fossil energy is still faced with various challenges, including limited technology and adequate infrastructure. Apart from that, Indonesia's large potential in coal is the main factor slowing down this energy transition. One promising alternative is to convert coal into Dimethyl Ether (DME) through the gasification process, which is a thermochemical process for converting solid fuel into gas, producing syngas containing H₂, CO, and CH₄. Synthesis purification is essential to produce high-purity DME. This process involves the use of filter materials such as zeolite and rice husk charcoal to remove contaminants such as sulfur. Zeolite, with its chemical absorption properties and regular pore structure, is effective in absorbing H₂S from syngas. Meanwhile, rice husk charcoal, which is an agricultural waste rich in silica and has a porous structure, has shown potential as an absorbent material to reduce H₂S content in gas. In research on the use of various filter material compositions in the up-draft type coal gasification process with CuO–ZnO–Al₂O₃ and ZSM-5 catalysts, it was found that a 3:7 ratio for zeolite and rice husk charcoal provided optimal performance. This ratio not only increases CH₄ and CO levels in syngas, but is also effective in reducing H₂S content. The research results showed that the highest DME production reached 90.10% at a ratio of 3:7, while at a ratio of 2:8 and 5:5, production was 81.61% and 73.64% respectively. These findings emphasize the importance of using diverse filter materials in improving syngas quality and DME synthesis efficiency, strengthening steps to accelerate the energy transition towards more sustainable solutions in Indonesia.