Article
Engineering, Aerospace
Yongchao Sun, Mingbo Sun, Dan Zhao, Yong Chen, Guangwei Ma, Minggang Wan, Yuze Sun, Jiajian Zhu
Summary: In this study, systematic experiments and numerical simulations were conducted to investigate the interaction between a premixed methane/air flame and acoustic disturbances in a longitudinal combustor, with a focus on blow-off characteristics. The results showed that the flame height increment was significantly affected by the evolution of vortices in the unburnt gas, leading to flame blow-off at an excitation frequency of 260 Hz. Experimental and numerical findings shed light on the fundamental physics of a premixed flame response to acoustic disturbances.
AEROSPACE SCIENCE AND TECHNOLOGY
(2021)
Article
Thermodynamics
Myunggeun Ahn, Taesung Kim, Youngbin Yoon
Summary: A comparative study was conducted on the response characteristics of non-premixed and premixed flames under acoustic excitation conditions. The study found that the flame fluctuation amplitude in non-premixed flames is influenced by the forcing frequency and velocity perturbation intensity, while in premixed flames, there is a linear correlation between flame height and Strouhal number and FTF gain. Furthermore, introducing flame height perturbation parameters can simplify the analysis of heat-release rate.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2022)
Article
Thermodynamics
A. Aniello, D. Laera, S. Marragou, T. Poinsot, T. Schuller, L. Selle
Summary: This study investigates the impact of localized pilot hydrogen injection on the Flame Transfer Function (FTF) of a premixed methane-air swirled flame using Large Eddy Simulation. The results show that hydrogen injection leads to a global redistribution of the heat release rate, resulting in a reduction of the FTF gain over the entire frequency range. In addition, hydrogen injection affects the characteristic time lag of the flame response.
COMBUSTION AND FLAME
(2023)
Article
Mechanics
C. J. Nicholls, K. Chakravarthy, B. M. T. Tang, B. A. O. Williams, M. Bacic
Summary: Shear layers can demodulate amplitude modulated, acoustic perturbations. A half-wave rectification model represents the relationship between the excitation waveform and the vorticity signal of large-scale structures. Overmodulating the excitation signal amplitude can double the demodulated response frequency. Experimental setups validate the predictions of the model and overmodulation can be used for practical applications.
Article
Thermodynamics
Eirik Aesoy, Hakon T. Nygard, Nicholas A. Worth, James R. Dawson
Summary: This study investigates how targeted interference between two well-characterized sources of hydrodynamic disturbances can modify the response of premixed bluff-body stabilized H-2/CH4 flames with and without swirl. The Flame Transfer Function (FTF) can be modulated at targeted frequencies by placing different shaped bodies upstream of the flame and varying the distance from the dump plane. The flame response shows that modulations in the fluctuating global heat release rate are caused by linear superposition along the flame front, leading to changes in flame surface area and amplitude of the fluctuating global heat release rate.
COMBUSTION AND FLAME
(2022)
Article
Engineering, Aerospace
Alexey Kiverin, Ivan Yakovenko
Summary: This paper focuses on the numerical analysis of reactive mixture explosion during accidents at a launch site, emphasizing the development of compression waves and thermo-acoustic instability due to intrinsic flame instability. This leads to the formation of strong shock waves and even detonation in highly reactive mixtures.
Article
Thermodynamics
Liang Yu, B. Aravind, Deanna A. Lacoste
Summary: This paper demonstrates that nanosecond repetitively pulsed discharges can reduce the response of lean methane-air swirl flames to acoustic excitations at pressures up to 3 bar. The flame transfer functions with and without plasma discharges were studied in the frequency range of 48-380 Hz at pressures of 1.2, 2.0, and 3.0 bar. The results show that the plasma discharges can decrease the gain of the flame transfer functions by up to 50%, regardless of the pressure. The mechanisms responsible for this effect are discussed.
COMBUSTION AND FLAME
(2023)
Article
Energy & Fuels
Chen Yang, Yong Liu, Xiang Zhang, Hao Li, Xinkun Ge, Feng Jin, Chongyang Liu
Summary: This study conducted experimental research on a swirl stabilized gas flame model combustor and studied the heat release response characteristics of the swirl combustor through the flame transfer function. The results showed that the flame transfer function of the non-premixed swirl flame exhibited a significant bimodal shape, and two oscillation modes of the flame near the gain peaks were identified. The coupling degrees between velocity fluctuations, fuel pressure fluctuations, and heat release fluctuations were analyzed, revealing a lack of complete feedback loop between the combustor and the fuel pipeline in the acoustic-induced vortex mode.
Article
Engineering, Civil
Xueqiang Shi, Yutao Zhang, Xiaokun Chen, Yuanbo Zhang, Qian Ma, Guocheng Lin
Summary: The combustion tests on an ethanol pool fire perturbed by acoustic waves revealed that the acoustic perturbance can both suppress and promote the fuel consumption rate of the pool fire, while maintaining the shape of flames in stable or disordered state. The dimensionless combustion rate of fuel for the pool fire increases quasi-linearly with the amplitude of sound-induced local periodic displacement.
FIRE SAFETY JOURNAL
(2021)
Article
Energy & Fuels
Jun Cheng, Bo Zhang
Summary: This study investigates the explosion characteristics and flame instability of ammonia-air/oxygen mixtures and provides fundamental research on the combustion characteristics, which can serve as an experimental reference for the development of chemical reaction mechanisms for ammonia combustion in oxygen-rich environments. The results also offer data support for the possibility of using ammonia fuel as a propellant for hypersonic vehicles in the future.
Article
Energy & Fuels
Sergey V. Golovastov, Grigory Yu. Bivol, Victor V. Golub
Summary: The study focused on the flame front propagation patterns in methane-air and acetylene-air gas mixtures in a half-open channel with a porous inner coating. The results showed that flame front velocities and pressures were influenced by the composition of the mixture and the pore size of the coating.
Article
Chemistry, Physical
Li Guo, Ming Zhai, Shijie Xu, Qianhao Shen, Peng Dong, Xue-Song Bai
Summary: The study demonstrates that the addition of hydrogen can widen the stable combustion range of methane/air flames in micro confined spaces, increase the frequency and maximum propagation velocity of FREI flames, and decrease the quenching distance of CH4/H2/air flames.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2022)
Article
Mechanics
Tomoaki Watanabe, Koji Nagata
Summary: This study investigates the perturbation response of small-scale shear layers in turbulence using direct numerical simulations (DNS). The analysis of shear layers in isotropic turbulence reveals that the typical layer thickness is approximately four times the Kolmogorov scale ?. The response for sinusoidal perturbations is examined for an isolated shear layer, which represents the mean flow around shear layers in turbulence. The results show that the vortex formation in the shear layer is most effectively promoted by perturbations with a wavelength divided by the layer thickness of about 7. This highlights the efficient promotion of small-scale shear instability in turbulence by velocity fluctuations with a wavelength of about 30?.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Engineering, Environmental
Lu-Qing Wang, Dai-Guo Chen, Hong-Hao Ma
Summary: The laminar burning velocity and cellular instabilities of premixed flame in H2-N2O mixtures were experimentally studied at different equivalence ratios and initial pressures. It was found that both the laminar burning velocity and Markstein length increase with the equivalence ratio. The most unstable flames were observed at phi= 0.4-0.6 due to the combined effects of thermal-diffusion and hydrodynamic instabilities. At lower initial pressure, the flame front is smooth, while at higher initial pressure, diffusion-thermal and hydrodynamic instabilities dominate the cellular structure of the flame front.
PROCESS SAFETY AND ENVIRONMENTAL PROTECTION
(2023)
Article
Chemistry, Physical
I. S. Yakovenko, A. D. Kiverin
Summary: This study focuses on the numerical analysis of combustion wave propagation in a confined vessel filled with a lean 15% hydrogen-air mixture containing suspended micro-droplets of water. The research shows that the flame can be accelerated in the presence of suspended micro-droplets with a diameter larger than 50 mm, leading to flame instability and small-scale flame front wrinkling. It is found that the interaction between the flame and droplets intensifies the combustion process.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2021)
Article
Energy & Fuels
Harun Yilmaz, Omer Cam, Ilker Yilmaz
Article
Thermodynamics
Harun Yilmaz, Omer Cam, Ilker Yilmaz
Summary: The study looked at the combustion and emission characteristics of H-2/CO/CH4/CO2 blends, investigated stable operating ranges of different mixtures, and found that the addition of CH4 improves rich flammability limits and emissions. Under externally modified acoustic conditions, flame behavior slightly altered but pollutant emissions improved in a more environmentally friendly manner.
COMBUSTION SCIENCE AND TECHNOLOGY
(2021)
Article
Energy & Fuels
Harun Yilmaz, Omer Cam, Ilker Yilmaz
Article
Energy & Fuels
Bugrahan Alabas, Guven Tunc, Murat Tastan, Ilker Yilmaz
Article
Energy & Fuels
Bugrahan Alabas, Guven Tunc, Murat Tastan, Ilker Yilmaz
Summary: This study investigates the instability changes of oxygen-enriched fuel mixtures under acoustic enforcement in a premixed and swirl supported system. Experimental results show that increasing oxygen enrichment up to 24% ratio can increase stability by enhancing the laminar flame speed, but stability decreases at 26% oxygen content in the oxidizer. Additionally, the addition of oxygen increases NOx emissions due to higher adiabatic temperature, while reducing CO emissions.
Article
Chemistry, Physical
Ilker Sivri, Harun Yilmaz, Omer Cam, Ilker Yilmaz
Summary: This study experimentally investigated the effects of fuel composition, swirl number, and hydrogen addition on combustion and emission characteristics of various biogas mixtures, and concluded that hydrogen addition can lead to changes in temperature distribution and emission characteristics of biogas mixtures.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2022)
Article
Chemistry, Physical
Bugrahan Alabas, Guven Tunc, Murat Tastan, Ilker Yilmaz
Summary: This study investigated the effects of hydrogen content and oxygen enrichment on synthetic gas mixtures. The results showed that increasing hydrogen content decreased the oxygen enrichment limit and caused flame instabilities. Furthermore, oxygen enrichment resulted in reduced CO emissions but increased NOx values for all synthetic gas mixtures.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2022)
Article
Energy & Fuels
Ilker Yilmaz, Yakup Cam, Bugrahan Alabas
Summary: The study found that the combustion stability of biogas mixtures increases with nitrogen ratio up to 30% N2, but decreases when exceeded. Nitrogen dilution helps the flame resist against 110 Hz frequency while increasing CO emissions and reducing NOx pollutants up to 20% N2, but NOx emissions increase after 20% N2.
Article
Energy & Fuels
Bugrahan Alabas, Guven Tunc, Murat Tastan, Ilker Yilmaz
Summary: The effect of enriching a low calorific biogas mixture with hydrogen and oxygen on combustion stability and exhaust emissions in a premixed burner was investigated. It was found that adding hydrogen to the biogas increased the heating value of the mixture and reduced instabilities. The mixture containing 20% H2 burned at the 23% O2 ratio showed the lowest emission and resistance to acoustic perturbation.
Article
Energy & Fuels
Ilker Yilmaz, Bugrahan Alabas, Murat Tastan, Guven Tunc
Article
Thermodynamics
Yong Cheng, Fukai Song, Lei Fu, Saishuai Dai, Zhiming Yuan, Atilla Incecik
Summary: This paper investigates the accessibility of wave energy absorption by a dual-pontoon floating breakwater integrated with hybrid-type wave energy converters (WECs) and proposes a hydraulic-pneumatic complementary energy extraction method. The performance of the system is validated through experiments and comparative analysis.
Article
Thermodynamics
Jing Gao, Chao Wang, Zhanwu Wang, Jin Lin, Runkai Zhang, Xin Wu, Guangyin Xu, Zhenfeng Wang
Summary: This study aims to establish a new integrated method for biomass cogeneration project site selection, with a focus on the application of the model in Henan Province. By integrating Geographic Information System and Multiple Criterion Decision Making methods, the study conducts site selection in two stages, providing a theoretical reference for the construction of biomass cogeneration projects.
Article
Thermodynamics
Mert Temiz, Ibrahim Dincer
Summary: The current study presents a hybrid small modular nuclear reactor and solar-based system for sustainable communities, integrating floating and bifacial photovoltaic arrays with a small modular reactor. The system efficiently generates power, hydrogen, ammonia, freshwater, and heat for residential, agricultural, and aquaculture facilities. Thermodynamic analysis shows high energy and exergy efficiencies, as well as large-scale ammonia production meeting the needs of metropolitan areas. The hybridization of nuclear and solar technologies offers advantages of reliability, environmental friendliness, and cost efficiency compared to renewable-alone and fossil-based systems.
Editorial Material
Thermodynamics
Wojciech Stanek, Wojciech Adamczyk
Article
Thermodynamics
Desheng Xu, Yanfeng Li, Tianmei Du, Hua Zhong, Youbo Huang, Lei Li, Xiangling Duanmu
Summary: This study investigates the optimization of hybrid mechanical-natural ventilation for smoke control in complex metro stations. The results show that atrium fires are more significantly impacted by outdoor temperature variations compared to concourse/platform fires. The gathered high-temperature smoke inside the atrium can reach up to 900 K under a 5 MW train fire energy release. The findings provide crucial engineering insights into integrating weather data and adaptable ventilation protocols for smoke prevention/mitigation.
Article
Thermodynamics
Da Guo, Heping Xie, Mingzhong Gao, Jianan Li, Zhiqiang He, Ling Chen, Cong Li, Le Zhao, Dingming Wang, Yiwei Zhang, Xin Fang, Guikang Liu, Zhongya Zhou, Lin Dai
Summary: This study proposes a new in-situ pressure-preserved coring tool and elaborates its pressure-preserving mechanism. The experimental and field test results demonstrate that this tool has a high pressure-preservation capability and can maintain a stable pressure in deep wells. This study provides a theoretical framework and design standards for the development of similar technologies.
Article
Thermodynamics
Aolin Lai, Qunwei Wang
Summary: This study assesses the impact of China's de-capacity policy on renewable energy development efficiency (REDE) using the Global-MSBM model and the difference-in-differences method. The findings indicate that the policy significantly enhances REDE, promoting technological advancements and marketization. Moreover, regions with stricter environmental regulations experience a higher impact.
Article
Thermodynamics
Mostafa Ghasemi, Hegazy Rezk
Summary: This study utilizes fuzzy modeling and optimization to enhance the performance of microbial fuel cells (MFCs). By simulating and analyzing experimental data sets, the ideal parameter values for increasing power density, COD elimination, and coulombic efficiency were determined. The results demonstrate that the fuzzy model and optimization methods can significantly improve the performance of MFCs.
Article
Thermodynamics
Zhang Ruan, Lianzhong Huang, Kai Wang, Ranqi Ma, Zhongyi Wang, Rui Zhang, Haoyang Zhao, Cong Wang
Summary: This paper proposes a grey box model for fuel consumption prediction of wing-diesel hybrid vessels based on feature construction. By using both parallel and series grey box modeling methods and six machine learning algorithms, twelve combinations of prediction models are established. A feature construction method based on the aerodynamic performance of the wing and the energy relationship of the hybrid system is introduced. The best combination is obtained by considering the root mean square error, and it shows improved accuracy compared to the white box model. The proposed grey box model can accurately predict the daily fuel consumption of wing-diesel hybrid vessels, contributing to operational optimization and the greenization and decarbonization of the shipping industry.
Article
Thermodynamics
Huayi Chang, Nico Heerink, Junbiao Zhang, Ke He
Summary: This study examines the interaction between off-farm employment decisions between couples and household clean energy consumption in rural China, and finds that two-paycheck households are more likely to consume clean energy. The off-farm employment of women is a key factor driving household clean energy consumption to a higher level, with wage-employed wives having a stronger influence on these decisions than self-employed ones.
Article
Thermodynamics
Hanguan Wen, Xiufeng Liu, Ming Yang, Bo Lei, Xu Cheng, Zhe Chen
Summary: Demand-side management is crucial to smart energy systems. This paper proposes a data-driven approach to understand the relationship between energy consumption patterns and household characteristics for better DSM services. The proposed method uses a clustering algorithm to generate optimal customer groups for DSM and a deep learning model for training. The model can predict the possibility of DSM membership for a given household. The results demonstrate the usefulness of weekly energy consumption data and household socio-demographic information for distinguishing consumer groups and the potential for targeted DSM strategies.
Article
Thermodynamics
Xinglan Hou, Xiuping Zhong, Shuaishuai Nie, Yafei Wang, Guigang Tu, Yingrui Ma, Kunyan Liu, Chen Chen
Summary: This study explores the feasibility of utilizing a multi-level horizontal branch well heat recovery system in the Qiabuqia geothermal field. The research systematically investigates the effects of various engineering parameters on production temperature, establishes mathematical models to describe their relationships, and evaluates the economic viability of the system. The findings demonstrate the significant economic feasibility of the multi-level branch well system.
Article
Thermodynamics
Longxin Zhang, Songtao Wang, Site Hu
Summary: This investigation reveals the influence of tip leakage flow on the modern transonic rotor and finds that the increase of tip clearance size leads to a decline in rotor performance. However, an optimal tip clearance size can extend the rotor's stall margin.
Article
Thermodynamics
Kristian Gjoka, Behzad Rismanchi, Robert H. Crawford
Summary: This paper proposes a framework for assessing the performance of 5GDHC systems and demonstrates it through a case study in a university campus in Melbourne, Australia. The results show that 5GDHC systems are a cost-effective and environmentally viable solution in mild climates, and their successful implementation in Australia can create new market opportunities and potential adoption in other countries with similar climatic conditions.
Article
Thermodynamics
Jianwei Li, Guotai Wang, Panpan Yang, Yongshuang Wen, Leian Zhang, Rujun Song, Chengwei Hou
Summary: This study proposes an orientation-adaptive electromagnetic energy harvester by introducing a rotatable bluff body, which allows for self-regulation to cater for changing wind flow direction. Experimental results show that the output power of the energy harvester can be greatly enhanced with increased rotatory inertia of the rotating bluff body, providing a promising solution for harnessing wind-induced vibration energy.