Energy Conversion and Management-X最新文献

In this study, an experimental assessment of the performance of carbon black nanofluids in a direct absorption solar collector was conducted. Unlike traditional direct absorption solar collectors, the laboratory setup in the present work utilized stationary nanofluids for solar absorption, which later heated a secondary fluid (water). This approach enabled the elimination of the need for pumping nanofluids within the system, thus reducing pumping costs and maintenance requirements. The efficiency of various nanoparticle concentrations was investigated and evaluated under identical conditions. Among the six nanofluids examined in the experimental analysis, ranging from 0.0015 to 0.05 wt.%, the most effective concentration was found to be 0.01 wt.% with a thermal enhancement of 42%, as compared to the reference distilled water values.

The primary aluminium industry stands as one of the most energy-consuming and, at times, the most inefficient, with approximately 50 % of energy being lost in the form of waste heat. The multiplicity of wasted heat sources in aluminium smelters presents a challenge in how to recover and integrate them, given their variations in both quantity and temperature levels. In this context, the study adopts the Parallel Two-stage Organic Rankine Cycle (PTORC) to separately integrate the wasted heat from the cathode sidewalls and the exhaust gases within a unified recovery system. The influence of primary and secondary evaporation temperatures, their pinch points, the number of integrated aluminium pots, and the working fluid on the thermodynamic performance and economic feasibility of PTORC are examined. At a given design condition, the findings indicate that decreasing the primary evaporation temperature while increasing the secondary evaporation temperature achieves the optimal operating condition of the system, resulting in a significant improvement in both output power and economic performance, while also reducing exergy destruction. At the primary evaporation temperature of 111.5 °C and the secondary evaporation temperature of 78.5 °C, the net output power reaches the optimal value of 3,840 kW. Furthermore, maintaining a lower pinch temperature difference in both evaporators proves advantageous for enhancing PTORC performance. Pentane, R236ea, and isopentane demonstrate outstanding maximum net power output at a constant secondary evaporation temperature, respectively. Meanwhile, R236ea and isobutane emerge as the most suitable working fluids for PTORC from an economic standpoint.

Biomass makes a substantial contribution to Italy’s renewable energy mix. In 2018, 19,235 GWh of energy were created, continuing a trend that began three years earlier. Italy’s demand for biofuel is expected to reach 2.8 million tonnes of oil equivalent by 2025 and remain constant until 2040. Biomass combustion frequently generates high temperatures (900–1000 °C), which justifies the construction of high-temperature heat recovery units such as steam Rankine or supercritical carbondioxide (SCO2) cycles. However, these methods are only economically practical on a medium to large scale. Small-scale units have high component costs because of the high specific volume of steam, while high turbomachinery costs mostly hamper small sCO2 systems. So, another alternative way is to use an organic Rankine cycle (ORC). This study uses thermodynamic analysis to determine how much power can be achieved in terms of energy, exergy, economy and what impact on sustainability is achieved at the Bologna ORC plant. From the study results, it was found that the Bologna unit has a capacity of 150 kWe. When data was collected, the maximum power obtained was 85 kW at a temperature and pressure of 153 °C and 1.84 MPa, respectively. Biomass-ORC investment is economically competitive, with NPV and LCOE values of 238 kE and 0.93 E/kWh, respectively, and a simple payback period of 24 years for residents with yearly energy needs of 2000 h.

The influence of vacuum pressure applied on H₂ separation from a palladium membrane is explored in this study. Three factors with three levels are considered, including the membrane chamber temperature with levels 320 °C, 350 °C, and 380 °C; the retentate-side total pressure with levels 1, 2, and 3 atm; and the permeation-side vacuum pressure with levels 0, 25, and 50 kPa. The Taguchi, response surface methodology (RSM), and multivariate adaptive regression splines (MARS) methods are employed to analyze the effects of the three parameters on hydrogen separation and predict their optimal combination. The retentate-side total pressure exhibits the highest impact on H₂ permeation, following the permeation-side vacuum pressure and then the membrane chamber temperature. The maximum H₂ flux is 0.226 mol∙s⁻¹∙m⁻², with H₂ recovery of 91 % obtained at the optimal conditions with a temperature of 380 °C, a total pressure of 3 atm, and a vacuum pressure of 50 kPa. The improvement in H₂ flux reaches 21.6 % compared with the case without the imposed vacuum pressure at the same temperature and total pressure. This result shows the imposed vacuum pressure is an efficient way to enhance H₂ permeation. The maximum relative errors between the experimental data and the predictions from the Taguchi, RSM, and MARS methods are 6.74 %, 3.37 %, and 8.08 %, respectively. The RSM method presents higher accuracy than Taguchi and MARS, perhaps due to a more precise analysis of the interaction terms. The smaller amount of input data and ignoring the temperature effect in MARS could be the reason for the lower accuracy. Nevertheless, the MARS method still demonstrates acceptable results. The cost of the Taguchi method is lower than that of the RSM method since it requires fewer experimental cases. In a word, the choice of the prediction method depends on the desired accuracy and the experimental cost.

Interstate electric power integration with the formation of interstate electric ties and power interconnection in Northeast Asia has been studied for several years. Research has examined the directions, indicators, costs, and systemic (integration) benefits (technical, economic, environmental, etc.) of forming such ties and grids. Studies conducted in different Northeast Asia countries have shown that despite the significant investments required to create an interstate electric ties infrastructure, which serves as the basis for interstate power grids and electricity markets development, participants of these interstate power grids and markets gain substantial benefits. These include reduced needs for installed and reserve generation capacity, lower electricity prices, increased overall flexibility of power resources, and accordingly, greater capability to integrate renewable energy sources. This results in reduced carbon dioxide (CO₂) emissions from fossil fuel power plants. The latter undoubtedly contributes to achieving the sustainable development goals set by the United Nations and reducing anthropogenic climate impact, which many countries globally (including Northeast Asia) have targeted via announced carbon neutrality by 2050–2060. The main target of the article is to conduct and present new multi-scenario study on forming a potential Northeast Asia’s interstate power grid under national and grid-wide (for the entire power system interconnection) carbon emission constraints. The mathematical model of electric power system expansion and dispatching was modified to account for carbon dioxide emission constraints and used for the study. The results of the study showed that the creation of interstate power grid in Northeast Asia accompanied by climate change collaboration among countries to control carbon dioxide emission would lead to effectively constraining of carbon dioxide emission in the subregion, which is the novelty of the study. The results of the study are useful and applicable for choosing particular ways, options, stages of formation and expansion of low-carbon power system interconnection in Northeast Asia.

Healthcare facilities in isolated rural areas of sub-Saharan Africa face challenges in providing essential health services due to unreliable energy access. This study examines the use of hybrid renewable energy systems consisting of solar PV, wind turbines, batteries, and hydrogen storage for the electrification of rural healthcare facilities in Nigeria and South Africa. The study deployed the efficacy of Hybrid Optimization of Multiple Energy Resources software for techno-economic analysis and the Evaluation based on the Distance from Average Solution method for multi-criteria decision-making for sizing, optimizing, and selecting the optimal energy system. Results show that the optimal configurations achieve cost-effective levelized energy costs ranging from $0.336 to $0.410/kWh for both countries. For the Nigeria case study, the optimal energy system includes 5 kW PV, 10 kW fuel cell, 10 kW inverter, 10 kW electrolyzer, and 16 kg hydrogen tank. South Africa’s optimal configuration has 5 kW PV, 10 kW battery, 10 kW inverter, and 7.5 kW rectifier. Solar PV provides more than 90 % of energy, with dual axis tracking yielding the highest output: 8,889kWh/yr for Nigeria and 10,470kWh/yr for South Africa. The multi-criteria decision-making analysis reveals that Nigeria’s preferred option is the hybrid system without tracking. In contrast, the horizontal axis, weekly adjustment tracking configuration is optimal for South Africa, considering technical, economic, and environmental criteria. The findings highlight the importance of context-specific optimization for hybrid renewable energy systems in rural healthcare facilities to accelerate Sustainable Development Goals 3 and 7.

The use of hydrogen as a source of fuel for marine applications is relatively nascent. As the maritime industry pivots to the use of alternate low and zero-emission fuels to adapt to a changing regulatory landscape, hydrogen energy needs to present and substantiate a technical and commercially viable use case to secure its value proposition in the future fuel mix. This paper leverages the technoeconomic and environmental assessment previously performed on HyForce, a hydrogen-fuelled harbour tug which has shown encouraging results for both technical and commercial aspects. This study aims to create a digital twin of HyForce to accurately predict her operability in real-world scenarios. The results from this study identify the strengths and drawbacks of the proposed use case. This is achieved by embedding the detailed design of HyForce in a virtual environment to further evaluate its operational performance through Computational Fluid Dynamics (CFD) simulations of realistic environmental conditions such as wind, wave, sea currents, and friction attributed to the properties of seawater. The results from this study indicate a base case power requirement of 93 kW to 1892 kW to achieve speeds of 5 to 12 knots in the absence of external environmental influences. Consequently, the speed of HyForce has a profound impact on total resistance peaking at 97.3 kN at 12 knots. Seawater properties such as low seawater temperature of 0 °C, and a high salinity of 50 g/kg increased friction. Additionally, wind speeds of 10 m/s acting on HyForce, delivered a resistance of 3 kN. However, these will be well mitigated through the design of the propulsion system which will be able to deliver a thrust power of 1892 kW and with assistance from the energy storage systems produce 2 MW of power to overcome the resistance experienced. The findings presented in this paper can serve as a foundation for constructing a robust model for the development of a predictive controller for future work. This controller has the potential to optimize the configuration of hydrogen and battery energy storage, aligning with desired cost functions.

This research examines distribution networks in detail, both underground and overhead, as well as the layout of distribution pipes. It takes into account both energy and economic aspects. Different installation methods and thermal insulation materials for pipelines are studied, while scientific aspects such as heat and pressure loss modelling, technological advances and strategies for improving cost-effective models are discussed. In addition, regulatory concerns, standards and policies relating to heat distribution are addressed, including Legionella contamination laws and pipe insulation thickness requirements. According to the study’s findings, underground pipes are generally better suited to district heating networks than above-ground pipes and the triple pipes can decrease heat losses by 45% compared to single pipes and by 24% compared to double pipes. This article offers readers a detailed comprehension of the technical, scientific, and regulatory elements of urban heating networks. It highlights the significance of optimizing these networks by employing innovative configurations and adhering to regulatory standards to improve energy efficiency and sustainability in urban areas.

Unlike the fixed wind turbines, the structure of Floating Offshore Wind Turbines (FOWT) have the added motions of six degrees of freedom induced by the wind, wave and tidal loads. These motions lead to vibration and the degradation of the structure. This paper presents a novel approach to model and stabilize the FOWT by employing the Oscillating Water Columns (OWC) as active structural control system. The innovative concept involves designing a new floating barge-type platform with integrated OWCs on opposite sides of the platform to mitigate undesired oscillations of the system. These OWCs counteract the bending forces caused by wind on the tower and waves on the barge platform. To synchronize the opposing forces with the system’s tilting, a proposed Particle Swarm Optimization with Decreasing Inertia-based Adaptive Neuro-Fuzzy Inference System (PSODI-ANFIS) airflow control strategy is employed. Through manipulation of the barge platform’s pitch angle, the PSODI-ANFIS airflow control system adjusts the valves on either side, opening one and closing the other accordingly. Simulation results, compared with the standard FOWT as well as the Fuzzy-based airflow control system, demonstrate the effectiveness of the PSODI-ANFIS airflow control. It is shown to be superior in reducing platform pitching and the fore-aft translation of the top tower.

The abundance of fossil fuels and their negative environmental effects, together with the substantial reduction in their investment prices, have made solar-biomass hybrid plants an increasingly appealing choice for supplying the world’s energy needs. This study evaluates the performance of a PV/biomass hybrid renewable energy system (HRES) that incorporates three distinct biomass processes, including pyrolysis, direct combustion, and gasification. The hybrid system is modeled employing the multi-objective genetic algorithm (MOGA). The most excellent layout is tabbed based on factors such as the largest proportion of green energy and the least amount of noxious emissions, as well as the minimum cost of energy (COE) and net present cost (NPC). The COE in the pyrolysis system is 17% and 38% lower than in scenarios 1 and 2, respectively. The decrease in NPC and overall system cost, which demonstrates 17% and 65% drops in NPC and 15% and 37.5% decreases in total system cost, respectively, as compared to scenarios 1 and 2. After comparing all the essential aspects, it is revealed that the HRES incorporating biomass pyrolysis is preferable to the most cost-effective option for making hybrid systems than other HRESs executed up of gasifier or direct combustion biomass technologies. This idea would improve the use of biomass resources in HRES by including the foremost biomass power production technology, making it simpler for researchers to identify the paramount hybrid renewable energy systems and create decisive HRES using biomass as the main source.