Cleaner Energy Systems最新文献

Compression ignition CI engine are versatile engines required for both industrial and domestic purposes. CI finds application in household mill, transportation and as components in energy plants. Operating the CI engine with biodiesel and its combination with fossil-based diesel is being encouraged to combat environmental menace of using only fossil diesel. This current work seeks to probe into comparison between the use of biodiesel and its emulsion to improve the performance CI engine. Methyl esters was synthesized from blends of three nonedible oils; Tevetia Peruviana, Honne and Neem (THN) using catalyst made from three bio wastes mixture. The production process was optimized using Taguchi tool. The THN methyl esters (THNME) obtained was assessed for fuel properties. Box Behnken tool was adopted to generate 17 investigational steps to explore the effect of THNME 100 and parts containing 20% and 60% of THNME on the fuel efficiency and safety of the CI engine. These fuel mixes were used as fuel in an unmodified single cylinder CI engine. The engine was operated on three engine loads (EL) 25%, 50% and 75% as well as engine speeds (ES) 1500, 2500 and 3500 rpm (rpm). The result obtained showed that blend of THNME with fossil diesel has the minimum exhaust gas temperature EGT. ANOVA of the performance result shows that the model developed is suitable to predict the behaviour of brake power and exhaust gas temperature only. This work conclude that B20 is moderately fuel efficient and safer for the unmodified engine in terms of EGT and BSFC.

Novelty: Emulsion of THNME B20 is a preferred fuel for the safety of the unmodified CI engine because of low EGT

Internal short circuit of cells is one of the main causes of thermal runaway in electric vehicle battery systems. Therefore, one of the most effective ways to prevent thermal runaway is to detect and identify internal short-circuit lithium-ion batteries before thermal runaway using a battery management system. This paper investigates the detection and identification of internal short circuits in batteries by proposing a multi-variable stepwise analysis (MSA) method. The MSA method is proposed for detecting and identifying faulty batteries by combining horizontal and vertical comparison methods and aging cells' ohmic internal resistance variation characteristics. A less consistent pack containing aging cells was designed to perform internal short-circuit experiments. Based on setting the appropriate threshold and moving the window frame horizontally, comparing the deviation degree of the ohmic internal resistance of each cell in the battery pack and the average ohmic internal resistance of the normal battery, the aging battery in the battery pack can be effectively identified. State of health (SOH) is the percentage remaining of the battery's actual maximum capacity value. The deviation degree of ohmic internal resistance of aging batteries with SOH of 92% and 80% is maintained at more than 15% and 45%. For early internal shorts with an equivalent internal short-circuit resistance of 100 Ω, the internal short-circuit detection time is 3896 s. For the short circuit in the middle and later periods (<10$\Omega$), the MSA algorithm can achieve rapid internal short-circuit detection within the 50 s window, reducing the risk of thermal runaway. The results verified that the method could effectively identify aging cells within the battery pack and detect internal short circuits for other cells, reducing false positives and effectively preventing thermal runaway.

Achieving local sustainable development often depends on consumers' incentives to efficiently utilize energy and resources. In this paper, Local sustainable communities (LSC) are introduced as a combination of sustainable communities and local energy communities to promote local energy and resource utilization. Business models on technology and service provision and those on promoting sustainable resource utilization are developed, which are then applied to a community in Austria. A modeling framework on sector coupling in community operations, that also considers resource utilization is developed to assess the impact of the business models. LSC business models promote participation and sustainable operation in an LSC as 31% of electricity and 34% of heat can be covered by LSC purchase. The implementation of energy recovery business models and the availability of sufficient decentralized technologies have the greatest impact on LSC operations, reducing external electricity grid coverage to 58%. The consideration of resource business models can positively contribute to a local resource utilization efficiency, reducing the water pipeline coverage by 43%. The introduction of an LSC has a positive impact on the United Nations Sustainable Development Goals and can therefore efficiently contribute to the development of a cleaner energy system.

Although the role of nuclear power in the energy mix is being discussed from various aspects, studies on nuclear power in the energy security narrative are still limited. In this context, the role of nuclear energy in energy security is examined from a vulnerability-based approach. First, causal linkages between various terms of energy security, including vulnerability, threat, hazard, and resilience were conceptualized. Amongst these terms, we further focused on resilience and explored it from the viewpoint of its robustness, flexibility, redundancy, diversification, adaptability, and interdependency. Finally, considering these six components of resilience, nuclear power as a part of the energy supply system was analyzed in the context of energy security. This reiterated the necessity to balance the positive effect of strengthening the resilience and the negative effect of generating hazards and threats associated with nuclear power. This study is the first to discuss pros and cons of nuclear power from the perspective of its interaction with energy system in energy security. This approach differs from existing approaches in which nuclear-specified issues are alone considered in the narrative of nuclear safety. Since energy security has become an important driver of energy policy in recent years, the developed concept of nuclear power in energy security shall act as an essential stepping stone in determining its future use.

The increasing demand for electrical and electronic equipment (EEE), particularly air conditioning (ACs), has caused a significant increase in energy demand. Improvements in energy efficiency increase material and carbon footprints under the production stage owing to the additional use of resources. Higher energy-efficiency models need to compensate for this rise before EEE reaches the end of its lifespan. Thus, the timing of offsetting, named breakeven point (BEP), was analyzed between two models of ACs manufactured in Japan with different energy efficiencies in this study, considering material and carbon footprints based on different lifestyles. Through the analysis, a contradictory relationship between energy efficiency and renewable energy was quantitatively identified; that is, the improvement of energy efficiency leads to a lower BEP, while the increase in renewable energy leads to a higher BEP. When the share of renewable energy in the energy mix reaches more than 40 % in the case of material footprint, the choice of low-efficiency appliances would be even preferable considering the lifespan of EEE and lifestyle. The developed concept contributes to optimal selection among different EEE efficiency from an environmental perspective.

Heat pumps will play a key role in the future provision of low carbon domestic heating and the re-use of industrial waste heat. Adsorption cycle heat pumps are advantageous in that they can use the existing natural gas network to avoid electricity supply limitations across the UK. A 2 kW domestic-scale ammonia/salt heat pump demonstrator is currently being tested at the University of Warwick as a replacement for a conventional condensing gas boiler. This paper describes analysis work in support of this testing which will lead to design refinements in follow-on developments.

A Matlab-based 2D transient simulation package was developed to study heat transfer and reaction rate within a pair of linked reactors. Heat conduction and sorption rate are modelled together with inter-reactor gas flows and parasitic heat loss. Novel features include the use of Matlab's linked ODE solvers for convergence (ODE15S was found to be fastest) and the script file input configuration which combines clear visibility of parameters with the ability to run multiple simulations to show the effect of parametric variations. The code facilitates rapid design optimisation.

Eleven cycle parameters have been investigated, including filling pressure, heat transfer coefficients, salt ratio, source temperatures, void space and heat capacity. The choice of cycle period involves a compromise between coefficient of performance and power output. A water/glycol heat transfer fluid gives better COP and output power than thermal oil. Insulation within the reactor shell has the potential to limit shell transient heat exchange but void space effects are likely to be more significant. The heat capacity of fluid in pipes and manifolds should be minimised.

COP = 1.31 is achieved at 45 °C delivery; 60 °C for hot water is possible but with lower COP. The best results for space heating are obtained with source temperatures above -5 °C.

Off-grid stand-alone solar PV systems have been given much attention for many years as they can provide clean and cheap electrical energy to communities in rural areas, particularly developing countries. However, due to their limited capacities, such PV systems are mainly used for primary and essential loads such as fans, lighting, cell phone charging, etc. In contrast, a considerable amount of excess energy is wasted every day due to insufficient battery storage. Therefore, peer-to-peer (P2P) interconnection between existing solar PV systems brings the opportunity to supply additional loads and make rural communities self-sufficient. Moreover, this innovative approach overcomes some obstacles that current mini/microgrids exhibit and plays a vital role in providing a reliable energy supply in rural areas. This paper investigates the feasibility of P2P solar energy sharing for such systems. In this regard, an IoT-enabled, cost-effective automated solar energy sharing system comprising three functional blocks has been proposed. The feasibility analysis in this paper indicates that the P2P application has increased the self-sufficiency and self-consumption of the community by 13.66% and 11.16%, respectively. As a result, a significant life cycle improvement enables the community by utilizing the proposed energy-sharing system benefits.

Accurate information about solar radiation is regarded as the most important stage in determining the availability of solar energy. As well, it is considered the principal input for various applications of solar energy. Because solar radiation measurements are unavailable at many locations throughout the world, many solar radiation models have been developed to predict global solar radiation. In this regard, this study objects to develop accurate and quick Global Solar Radiation (GSR) models for new locations, which currently lack an accurate model. Additionally, assess the performance of a recently introduced model, one of the best temperature-based models for GSR estimation, in these five new sites. Moreover, the proposed model's generalization capacity is investigated over the whole zone, the Suez Canal Zone, and a comparative analysis of its performance is presented. Models’ estimation is compared to the observed values, and the most common performance indicators are obtained to assess models’ performance. The findings indicate that the developed models in this study can predict global solar radiation accurately. Where the Models’ performance, both the local and general models, are larger than 95 % at all sites except for the local one at Port Said City (coastal site), it is 91 %. Additionally, the developed models have good RMSE and MABE values which range from 0.8 to 1.8 (MJ/m² day⁻¹) and 0.7 to 1.7 (MJ/m² day⁻¹), successively. Besides, they have excellent performance with coefficient of determination (R²) values ranging from 0.95 to 0.98, whereas prior research's ranges are 0.884–0.895 for R² and 2.69–3.367 (MJ/m² day⁻¹) for RMSE. Therefore, the developed models in this study can be utilized for accurate GSR forecast, with their high applicability which may be achieved by combining them with various long- or short-term weather forecasting approaches, that are mostly used to reliably anticipate weather temperature. As well, these models' precise and speedy computation of GSR can also be employed in the design and performance evaluation of various solar applications.

Continuous flow microreactors have been shown to be effective for biodiesel production, and the Tesla-shaped microreactor, in particular, is one of the proposed microreactors for this application. However, its applicability in the industry is still limited. Therefore, comprehensive simulation studies that agree with the real processes need to be performed to allow a deep understanding of the process. A 2D CFD simulation model is constructed in COMSOL Multiphysics software to study the performance of a Tesla-shaped microreactor fabricated in-house- for biodiesel production from waste cooking oil (WCO). The model is thoroughly analyzed and validated experimentally at different operating conditions. The percentage yield values resulting from the simulation were found to be 84.13% at a temperature of 50 °C, 90.79% at a temperature of 55 °C, and 94.85% at a temperature of 60 °C, which deviated from the experimental values by 2.73%, 1.15%, and 1.98%, respectively. On the other hand, an alcohol-to-oil molar ratio of 12:1 resulted in a simulation percentage yield of 94.85% which deviates from the experimental values by 1.98%, while at a molar ratio of 9:1, the simulation yielded 93.67% with a deviation of 3.33% from the experimental results. At a lower ratio of 6:1, the simulation percentage yield was found to be 69.89%, and it deviated by 18.82% from the experimental results. This study presents a novel combination of simulation and experimental validation for the Tesla-shaped microreactor in biodiesel production from waste cooking oil., which is a topic with limited existing research although it significantly contributes to understanding the process at different operating conditions. The high agreement between simulation and experimental results demonstrates the accuracy and suitability of the simulation for studying the% conversion, and potential investigation such as the molar flow rate variations, and reaction rates under different conditions. This approach offers a cost-effective and efficient solution for optimizing biodiesel production, reducing the need for extensive experimental trials, and saving significant time and effort.

Environmental issues and air pollution in urban areas are driving forces behind the shift to electric vehicles (EVs). The energy storage element of the EVs can be used in many effective ways, such as increasing spinning reserve, shaving peak load, load levelling, voltage regulation etc. So, establishing a smart grid with several renewable energy sources along with the grid integration of EVs is the recent trend in power systems. One of the commonly observed essential phenomena in the smart grid including a PV system is partial shading (PS), which implicates the reduction of solar irradiation over the PV module, mainly due to leaves or branches of trees, clouds, and dust. Though most previous researchers were concerned about the steady state power reduction during PS, in this research, we focused on the reduction of transient impact on a grid-connected PV system using the controlled Vehicle to Grid (V2G) operation of the EVs. A small-scale microgrid consisting of a PV farm and a diesel generator is considered, where the PV farm experiences different degrees of shading varying from 30 to 70%. The simulation results show that due to the increase of the PS, the percentage overshoot (% OS) and settling time of rotor speed, active power and load current are increased. To mitigate this issue, we proposed the integration of plugged-in electric vehicles (PEVs), through the controlled V2G operation, which is done here by a PI controller. The proposed system improves the transient effects at both the load and generator sides. It has been found that the PS creates an oscillation in rotor speed, which is settled down by the governor system of the generator at the 20s, while the controlled V2G operation reduced this settling time to 10s. On the load side, the % OS of active power has been reduced from 4.24% to 0.44% and the settling time has been decreased from 28s to 18s by the controlled integration of the PEVs.