The Impact of the Micro-Structure within Passivated Layers on the Performance of the a-Si:H/c-Si Heterojunction Solar Cells Energies - - 2023
Lee, Sunhwa, Park, Jinjoo, Pham, Duy Phong, Kim, Sangho, Kim, Youngkuk, Trinh, Thanh Thuy, Dao, Vinh Ai, Yi, Junsin
This study investigated the correlation between the degree of disorder of the post-hydrogen plasma treatment (HPT) of the intrinsic hydrogenated amorphous silicon (a-Si:H(i)) and the device characteristics of the a-Si:H/c-Si heterojunction (HJ) solar cells. The reduction in the degree of disorder helps to improve interface defects and to enhance the effective carrier lifetime of the a-Si:H/c-Si heterojunction. The highest effective minority carrier lifetime of 2.08 ms was observed in the film with the lowest degree of disorder of 2.03. The devices constructed with HPT a-Si:H(i) having a lower degree of disorder demonstrated higher device performance in terms of open-circuit voltage (Voc), fill factor (FF), and subsequent conversion efficiency. An a-Si:H(i) with a lower degree of disorder (2.03) resulted in a higher Voc of 728 mV and FF of 72.33% and achieved a conversion efficiency of up to 20.84% for the a-Si:H/c-Si HJ silicon solar cell.
Experimental Research of High-Temperature and High-Pressure Water Jet Characteristics in ICRC Engine Relevant Conditions Energies - Tập 12 Số 9 - Trang 1763
Zhe Kang, Zhehao Zhang, Jun Deng, Liguang Li, Zhijun Wu
The internal combustion Rankine cycle (ICRC) concept provides a potential solution for future high thermal efficiency and low emission powertrains, and direct water injection (DWI) proved to be the key parameter for ICRC optimization. This paper was dedicated to investigating the fundamental mechanisms of water spray characteristics under different water injection control parameters. In order to do so, an experimental test system was carefully designed and built based on the Bosch and Schlieren methods: the Bosch method is utilized to measure the effect of injection and ambient pressure on water injection characteristics, and the Schlieren method is utilized to investigate the impact of water injection and ambient temperature on water spray and evaporation processes. The experimental results indicate that both control parameters show important effects on water injection and spray characteristics. The water injection and ambient pressure show significant impacts on steady-state flow quantity and cyclic water injection quantity, and the water injection and ambient pressure affect the evaporation ability of water vapor within the spray which leads to a different variation trend during the initial, developing, and developed water spray stages. The results of this work can be used as fundamental supplements for ICRC, steam assistant technology (SAT), and DWI-related ICEs experimental and numerical researches, and provide extra information to understand the DWI process within engine-relevant conditions.
Anaerobic Co-Digestion of Sludge and Organic Food Waste—Performance, Inhibition, and Impact on the Microbial Community Energies - Tập 11 Số 9 - Trang 2325
Alexander Keucken, Moshe Habagil, Damien J. Batstone, Ulf Jeppsson, Magnus Arnell
Anaerobic co-digestion allows for under-utilised digesters to increase biomethane production. The organic fraction of municipal solid waste (OFMSW), i.e., food waste, is an abundant substrate with high degradability and gas potential. This paper investigates the co-digestion of mixed sludge from wastewater treatment plants and OFMSW, through batch and continuous lab-scale experiments, modelling, and microbial population analysis. The results show a rapid adaptation of the process, and an increase of the biomethane production by 20% to 40%, when co-digesting mixed sludge with OFMSW at a ratio of 1:1, based on the volatile solids (VS) content. The introduction of OFMSW also has an impact on the microbial community. With 50% co-substrate and constant loading conditions (1 kg VS/m3/d) the methanogenic activity increases and adapts towards acetate degradation, while the community in the reference reactor, without a co-substrate, remains unaffected. An elevated load (2 kg VS/m3/d) increases the methanogenic activity in both reactors, but the composition of the methanogenic population remains constant for the reference reactor. The modelling shows that ammonium inhibition increases at elevated organic loads, and that intermittent feeding causes fluctuations in the digester performance, due to varying inhibition. The paper demonstrates how modelling can be used for designing feed strategies and experimental set-ups for anaerobic co-digestion.
Numerical Simulation of Low Salinity Water Flooding on Core Samples for an Oil Reservoir in the Nam Con Son Basin, Vietnam Energies - Tập 14 Số 9 - Trang 2658 - 2021
Hien, DoanHuy, Giao, Pham Huy, Ngoc, Pham Quy, Quy, Nguyen Minh, Dung, Bui Viet, Huy, Dinh Duc, Giang, Pham Truong, Long, Hoang
Low-salinity water flooding (LSWF) is environment-friendly and operates similarly to conventional waterflooding without the need for synthetic chemical materials. The application of LSWF makes sense in Vietnam as HC production has steadily declined since 2002, and the majority of main oil fields have become near mature and mature fields. In the next years, Enhanced Oil Recovery (EOR) should be a top priority for Petro Vietnam to boost its oil production, for which the key issue is how to select a suitable EOR technology. In this study, LSWF of the Lower Miocene sand using low salinity water from Lower Oligocene sand was investigated. Previously at the Ruby field in the Cuu Long Basin, an LSWF feasibility study was carried out based on a conventional core flooding experiment, which is time-consuming and costly. This study targets the Chim Sao field in the Nam Con Son Basin, for which a cheaper and faster assessing method is required. As a result, a numerical code written in Matlab was developed and successfully validated with the core flooding experiment results obtained at the Ruby field. The LSWF simulation was conducted using the multiple ion-exchange mechanisms (MIE), and the results obtained showed an increase in the oil recovery factor by 2.19% for the Lower Miocene Sand. Another important outcome of this study is the innovative proposal and successful simulation to use the abundant low salinity water from the underlying Lower Oligocene sand as a natural LSW source to inject into the Lower Miocene oil reservoir that can be a decisive factor to help apply LSWF in practice on a wide scale not only for Chim Sao but also other similar oil fields in southern offshore Vietnam.
A Practical Approach to Launch the Low-Cost Monitoring Platforms for Nearly Net-Zero Energy Buildings in Vietnam Energies - Tập 15 Số 13 - Trang 4924 - 2022
VU, Thi Tuyet Hong, DELINCHANT, Benoit, PHAN, Anh Tuan, BUI, Van Cong, NGUYEN, Dinh Quang
Buildings with solar rooftops have become vital objects in the energy transition in Vietnam. In this context, the demand for research on energy management solutions to use energy efficiently and increase PV energy absorption capacity is rising. In this paper, we present a practical route to developing a low-cost monitoring platform to meet the building energy management in the country. First, our project built a monitoring architecture with high-density wireless sensors in an office building in Vietnam. Next, we discussed the influence of significant obstacles such as technical issues, users, and cost on the resilience and reliability of the monitoring system. Then, we proposed essential solutions for data quality improvement by testing sensors, detecting wireless sensor network errors, and compensating for data losses by embedding machine learning. We found the platform’s potential in developing a rich database of building characteristics and occupants. Finally, we proposed plans exploiting the data to reduce wasted energy in equipment operation, change user behaviors, and increase auto-consumption PV power. The effectiveness of the monitoring platform was an approximate 62% energy reduction in the first year. The results are a cornerstone for implementing advanced research as modeling and real-time optimal control toward nearly zero-energy buildings.
Data Compensation with Gaussian Processes Regression: Application in Smart Building’s Sensor Network Energies - Tập 15 Số 23 - Trang 9190 - 2022
Phan, Anh Tuan, Vu, Thi Tuyet Hong, Nguyen, Dinh Quang, Sanseverino, Eleonora Riva, Le, Hang Thi-Thuy, Bui, Van Cong
Data play an essential role in the optimal control of smart buildings’ operation, especially in building energy-management for the target of nearly zero buildings. The building monitoring system is in charge of collecting and managing building data. However, device imperfections and failures of the monitoring system are likely to produce low-quality data, such as data loss and inconsistent data, which then seriously affect the control quality of the buildings. This paper proposes a new approach based on Gaussian process regression for data-quality monitoring and sensor network data compensation in smart buildings. The proposed method is proven to effectively detect and compensate for low-quality data thanks to the application of data analysis to the energy management monitoring system of a building model in Viet Nam. The research results provide a good opportunity to improve the efficiency of building energy-management systems and support the development of low-cost smart buildings.
Investigation of Ecosystem Services and Circular Economy Interactions under an Inter-organizational Framework Energies - Tập 12 Số 9 - Trang 1734
Vasilis C. Kapsalis, Grigorios L. Kyriakopoulos, Konstantinos Aravossis
Nowadays, the conceptualization of circular economy is an attractive managerial tool among governments and businesses throughout the word, while ecosystem services are a contentious issue due to the particular needs of humans’ well-being. At this review the interactions between the principles of ecosystem services and the circular economy were investigated in the light of inter-organizational systems. This evaluation was based on more and more complex processes, while the integration of the growing circular economy concept within the shrinking parent ecosystem unveiled challenges and constraints for products’ end of life and quality. It was argued that: (a) The existence of social and people-related barriers can be considered under three groups, namely, the “sustainable provision and modeling schemes”, “socio-cultural appreciation and payment schemes”, and “regulatory and maintenance schemes”, (b) The impacts of circular economy—ecosystem services toward an inter-organizational functional stream model associated with distinguished proactive and post treatment risk values (c) The functionality and the accountability of the technosphere are the two critical components to support the restorative and the regenerative perspectives of the biosphere. The aforementioned findings unveiled new emerging paths to be further investigated, offering a deeper appraisal of circular economy under the inter-organizational perception.
Topic Taxonomy and Metadata to Support Renewable Energy Digitalisation Energies - Tập 15 Số 24 - Trang 9531 - 2022
Michiorri, Andrea, Sempreviva, Anna Maria, Philipp, Sean, Perez-Lopez, Paula, Ferriere, Alain, Moser, David
Research and innovation in renewable energy, such as wind and solar, have been supporting the green transformation of energy systems, the backbone of a low-carbon climate-resilient society. The major challenge is to manage the complexity of the grid transformation to allow for higher shares of highly variable renewables while securing the safety of the stability of the grid and a stable energy supply. A great help comes from the ongoing digital transformation where digitisation of infrastructures and assets in research and industry generates multi-dimensional and multi-disciplinary digital data. However, a data user needs help to find the correct data to exploit. This has two significant facets: first, missing data management, i.e., datasets are neither findable because of missing community standard metadata and taxonomies, nor interoperable, i.e., missing standards for data formats; second, data owners having a negative perception of sharing data. To make data ready for data science exploitation, one of the necessary steps to map the existing data and their availability to facilitate their access is to create a taxonomy for the field’s topics. For this, a group of experts in different renewable technologies such as photovoltaics, wind and concentrated solar power and in transversal fields such as life cycle assessment and the EU taxonomy for sustainable activities have been gathered to propose a coherent and detailed taxonomy for renewable energy-related data. The result is a coherent classification of relevant data sources, considering both the general aspects applicable to electricity generation from selected renewable energy technologies and the specific aspects of each of them. It is based on previous relevant work and can be easily extended to other renewable resources not considered in this work and conventional energy technology.
Comparative Analysis of Adjustable Robust Optimization Alternatives for the Participation of Aggregated Residential Prosumers in Electricity Markets Energies - Tập 12 Số 6 - Trang 1019 - 2019
Correa-Florez, Carlos Adrian, Michiorri, Andrea, Kariniotakis, Georges
Active participation of end users in energy markets is identified as one of the major challenges in the energy transition context. One option to bridge the gap between customers and the market is aggregators of smart homes or buildings. This paper presents an optimization model from the standpoint of an aggregator of residential prosumers who have PV panels, electric water heaters, and batteries installed at home level. This aggregator participates in the day-ahead energy market to minimize operation costs by controlling the settings of flexible devices. Given that energy prices, PV production, and demand have uncertain behavior, appropriate models should be used to include these effects. In the present work, Adjustable Robust Optimization (ARO) is used to include uncertainty in the optimization model, and a comparative study of modifications to this formulation is carried out to determine its potential and limitations. The comparative analysis is performed from the point of view of average cost and risk, after performing Monte Carlo simulation. Simulations show the advantages of using an ARO framework when compared to deterministic approaches and also allow us to conclude about the advantages of using the proposed alternative formulation to find more attractive solutions for an aggregator.
Heat Generation Characteristics of LiFePO4 Pouch Cells with Passive Thermal Management Energies - Tập 11 Số 5 - Trang 1243
Soham Neupane, Morteza Alipanah, Derek Barnes, Xianglin Li
This article experimentally investigates the heat generation characteristics and the effectiveness of passive cooling of commercially available LiFePO4 (7.25 mm × 160 mm × 227 mm, 19.5 Ah) cells using different cooling materials. The specific heat capacity and the entropy coefficient of the cell are experimentally measured. The heat generation rate of the cell at 1–4 C current rates are also determined using three different methods: (1) the heat absorption calculated from the temperature increase of cooling water; (2) the energy loss calculated from the difference between the operating voltage and open circuit voltage; and (3) the energy loss during a charge-discharge cycle calculated using the voltage difference between charging and discharging. Results show that the heat generation rate estimated from heat absorbed by the water can be underestimated by up to 47.8% because of the temperature gradient within the cell and on the surface. The effectiveness of different passive cooling materials is compared at discharge current rates of 1–3 C. The average increase of the cell surface temperature is 22.6, 17.1, 7.7, 7.2 and 6.4 °C at 3 C (58.5 A) using air, aluminum foam, octadecane, water with aluminum foam and water, respectively.
