Article
Energy & Fuels
Oscar Tenango-Pirin, Sierra Espinosa, Juan Carlos Garcia, Jose Alfredo Rodriguez
Summary: Gas turbine combustors are prone to combustion instabilities due to changes in operating conditions and components, which can affect exhaust emissions. This study focuses on numerically simulating non-premixed combustion to analyze exhaust gases and temperature fields under unsteady inlet airflow conditions. The results show that the temperature and pressure in the combustor are highly sensitive to the inlet air pressure condition, and emissions of flue gases like CO and NOx are also affected. The study suggests that pressure oscillations can lead to flashback effects and impact the combustion and emissions in gas turbine combustors.
Article
Thermodynamics
Daewook Kim, Jae Jun Jang, Hyungseok Nam, Jae Young Kim, Yooseob Won, Seung-Yong Lee, Byung Wook Hwang, Yujin Choi, Hana Kim, Jeom-In Baek, Ho-Jung Ryu
Summary: This study experimentally investigated the flow characteristics in the dipleg of a 3 MWth scale CLC system, verifying design and operating conditions while predicting the amount of gas mixing. The study found that the upward and downward gas flowrates in the dipleg increased as the solid circulation rate increased.
Article
Engineering, Aerospace
Jianbin Li, Jianhan Liang, Mingbo Sun, Zun Cai, Lin Zhang
Summary: This study experimentally investigates the effect of inlet distortion on the combustion process in a direct-connect test environment. The results show that blockage at the entrance of the isolator can accurately mimic the inlet distortion. Combustion enhancement is achieved in cases with blockage, with wider lean blowoff limits in the combustor. The stronger oblique shock wave and additional background shock wave caused by the inlet distortion are the main causes of combustion enhancement in these cases.
AEROSPACE SCIENCE AND TECHNOLOGY
(2023)
Article
Engineering, Aerospace
V. Kirubakaran, R. Naren Shankar
Summary: This study predicts the effect of combustor inlet area ratio on the lean blowout limit of a swirl stabilized can-type micro gas turbine combustor. The results show that the LBO equivalence ratio decreases with an increase in inlet velocity, but decreases significantly at low inlet velocities with a decrease in CIAR.
AIRCRAFT ENGINEERING AND AEROSPACE TECHNOLOGY
(2021)
Article
Energy & Fuels
Abdulkadir Bektas
Summary: This study aims to explore the possible ways of using ammonia as a clean and sustainable fuel. The findings suggest that oxy-ammonia combustion has higher temperature and lower NOx emissions, indicating better combustion performance compared to air-methane combustion. The use of cyclone combustors improves mixing quality and combustion residence time.
INTERNATIONAL JOURNAL OF ENERGY RESEARCH
(2022)
Article
Engineering, Environmental
Clemens F. Patzschke, Matthew E. Boot-Handford, Qilei Song, Paul S. Fennell
Summary: The study found that copper manganese spinel oxides are promising oxygen carriers for the CLOU and CLAS processes due to their high O-2 release capacity and fast release kinetics. Material properties of oxygen carriers can be improved by adjusting Cu:Mn ratios and synthesis conditions to optimize performance. After extended cycling tests, the oxygen carriers showed excellent stability and high resistance to attrition.
CHEMICAL ENGINEERING JOURNAL
(2021)
Article
Thermodynamics
Danyal Mohaddes, Davy Brouzet, Matthias Ihme
Summary: Predictive high-fidelity simulations of turbulent spray combustion require the consideration of complex chemistry, multiphase evaporating flow, and spray-flame interactions. The Pareto-efficient combustion (PEC) framework is applied to dynamically assign combustion models based on local cost and accuracy metrics for spray combustion. The extended PEC formulation is tested in the simulation of a realistic gas turbine combustor and demonstrates its ability to adapt to changing conditions and control modeling errors.
COMBUSTION AND FLAME
(2023)
Article
Energy & Fuels
Md Azazul Haque, Medhat A. Nemitallah, Ahmed Abdelhafez, Esmail M. A. Mokheimer, Mohamed A. Habib
Summary: This study investigates the characteristics and emissions of premixed oxy-combustion flames in a combustor, comparing the effects of different fuels. The results show that increasing the equivalence ratio improves certain parameters important for gas turbine combustion, but also leads to higher CO emissions. Among the fuels studied, oxy-methane flames have the highest flame thicknesses and lowest CO emissions, while oxy-propane flames have higher values of temperature, flame speed, power density, and thermal power.
INTERNATIONAL JOURNAL OF ENERGY RESEARCH
(2022)
Article
Energy & Fuels
Sonu Kumar, Pinak Mohapatra, Rushikesh K. Joshi, Matthew Warburton, Liang-Shih Fan
Summary: We propose a new low-temperature chemical looping combustion scheme for natural gas conversion into CO2 and NOx purification. The process utilizes NiO/ZrO2 as the oxygen carrier and operates at temperatures close to the flue gas temperature of 400-500 degrees C. Thermodynamic studies show that the presence of CO2 does not significantly affect NOx purification performance. Comparative analyses indicate improvements in exergy efficiency and effective thermal efficiency compared to conventional NOx selective catalytic reduction (SCR) processes.
Article
Energy & Fuels
Giovanny S. de Oliveira, Ciro E. S. Lobo, Carlos E. A. Padilha, Domingos F. S. Souza, Juan A. C. Ruiz
Summary: Brazil aims to reduce its CO2 emissions by utilizing glycerin in Chemical Looping Combustion (CLC). The study evaluates the feasibility of using glycerin in CLC and finds that the addition of ethanol improves combustion efficiency, while the addition of methanol reduces efficiency.
Article
Energy & Fuels
Zhongya Xi, Zundi Liu, Xiaoxiang Shi, Tianyou Lian, Xiaoyuan Yang, Jianguo Zhang, Bowen Mei, Yuyang Li
Summary: Adding dimethyl ether (DME) to biogas can improve flame stability and combustion intensity, while increasing CO2 content can raise the lean blowout limit. DME co-firing increases NO emissions, while increasing CO2 content decreases NO emissions.
Article
Thermodynamics
Zhihao Zhang, Xiao Liu, Hongtao Zheng, Guangpu Lv, Shengnan Li
Summary: The combustion characteristics of a gas turbine model combustor under air-inlet excitation are studied using Large Eddy Simulation (LES). The results show the presence of a precessing vortex core (PVC) structure, which alternately evolves into single and double helix branches during one forcing cycle. The rotation of the PVC causes periodic squeezing of the high-speed ring zone (HSRZ), resulting in large-scale vortex roll-up. The flame root structure is also significantly affected by the PVC, contributing to the fluctuation in heat release rate (HRR). The flame response can be divided into three parts with increasing forcing amplitude, characterized by a linear growth zone, saturation plateau, and secondary rising zone. The change in flame structures and flame front oscillation modes are identified as the apparent mechanism for the nonlinear flame response appearance.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART A-JOURNAL OF POWER AND ENERGY
(2022)
Article
Energy & Fuels
Jose Francisco Gonzalez Alvarez, Efren Alonso Fernandez
Summary: This study analyzes the flow field during combustion using oxy-combustion in conditions similar to Matiant combustion chambers. Methodology involves CFD simulations with detailed reaction mechanisms and models, considering different working fluids and pressures. Findings show that temperature differences decrease with increasing operating pressure in Matiant cycles.
Article
Green & Sustainable Science & Technology
Mohammad Saghafifar, Matthias A. Schnellmann, Stuart A. Scott
Summary: This paper studies the feasibility of using packed bed reactors in chemical looping air separation. By introducing a compressor and turbine, oxidizers can be operated at an elevated pressure and used to produce oxygen for combustion.
INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL
(2022)
Article
Engineering, Aerospace
Xiao Han, Dong Yang, Jianchen Wang, Chi Zhang
Summary: This paper experimentally investigates the effect of inlet boundaries on combustion instabilities in a spray combustor, with significant thermoacoustic instabilities observed in the case with no diffuser. The use of Rayleigh index maps and a low order network model helps explain the observed behaviors, and it is found that the stability of the thermoacoustic system is very sensitive to the length of the diffuser but not sensitive to its cross-sectional area.
AEROSPACE SCIENCE AND TECHNOLOGY
(2021)
Article
Thermodynamics
Szabolcs Szima, Carlos Arnaiz del Pozo, Schalk Cloete, Paolo Chiesa, Angel Jimenez Alvaro, Ana-Maria Cormos, Shahriar Amini
Summary: This paper presents a techno-economic assessment of flexible power and hydrogen production from VRE, using gas switching combustion and membrane assisted water gas shift technologies. The study shows that these advanced plants can provide a higher annual rate of return compared to traditional benchmark plants during times of abundant wind and sun, demonstrating their promise for balancing VRE.
ENERGY CONVERSION AND MANAGEMENT
(2021)
Article
Thermodynamics
Florian Pruvost, Schalk Cloete, Jan Hendrik Cloete, Chaitanya Dhoke, Abdelghafour Zaabout
Summary: A techno-economic assessment of molten salt pyrolysis process reveals that moderate pressure and limited reactor size can achieve high efficiency and promising economics. In the long-term, turquoise hydrogen can serve as a promising alternative to blue hydrogen in regions with public resistance to CO2 transport and storage. In the medium-term, expensive first-of-a-kind plants can produce carbon that can access smaller high-value markets, ensuring profitable operation even for first movers.
ENERGY CONVERSION AND MANAGEMENT
(2022)
Article
Green & Sustainable Science & Technology
Ambrose Ugwu, Carlos Arnaiz del Pozo, Abdelghafour Zaabout, Shareq Mohd Nazir, Nimet Uzun Kalendar, Schalk Cloete, Szabolcs Szima, Szabolcs Fogarasi, Felix Donat, Geert van Diest, Jan Hendrik Cloete, Angel Jimenez Alvaro, Knuth Albertsen, Ana-Maria Cormos, Calin-Cristian Cormos, Shahriar Amini
Summary: Gas switching technology (GST) has been widely applied in the conversion of fossil fuels and biomass, enabling integrated CO2 capture with minimal energy penalty and demonstrating the feasibility and potential energy and cost savings of the technology.
INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL
(2022)
Article
Thermodynamics
Carlos Arnaiz del Pozo, Angel Jimenez Alvaro, Juan Jose Roncal Casano, Schalk Cloete
Summary: This study presents an exergoeconomic assessment of integrating two-phase expanders (TPE) in cryogenic air separation units. The results show that the integration of TPE in the ASU configurations can increase exergy efficiency and reduce specific power consumption. From an economic perspective, the total liquid pumping scheme with TPE presents a significant cost reduction compared to the configuration with gas compressors.
Article
Thermodynamics
Carlos Arnaiz del Pozo, Schalk Cloete
Summary: This study evaluates the prospects of blue and green ammonia as future energy carriers and compares them with conventional technologies. The results show that blue ammonia is more economically attractive, while green ammonia has higher costs in technology integration and energy.
ENERGY CONVERSION AND MANAGEMENT
(2022)
Article
Thermodynamics
Carlos Arnaiz del Pozo, Schalk Cloete, Angel Jimenez Alvaro
Summary: Growing concerns about climate change have led to increased interest in alternative energy carriers to fossil fuels. Methanol shows promise as a potential solution for transportation and storage challenges, with an existing infrastructure and scalable synthesis process. This study assesses the techno-economic viability of producing methanol from natural gas and renewable energy with direct air capture (DAC). The results indicate that both natural gas and renewable methanol have their advantages and costs, and the deployment of renewable methanol at scale will require strong policy support.
ENERGY CONVERSION AND MANAGEMENT
(2022)
Article
Green & Sustainable Science & Technology
Schalk Cloete, Oliver Ruhnau, Jan Hendrik Cloete, Lion Hirth
Summary: This study explores trade channels between energy exporters and importers and recommends fossil fuel exporting countries to consider transitioning to a mix of blue hydrogen and climate-neutral industrial base products.
JOURNAL OF CLEANER PRODUCTION
(2022)
Article
Thermodynamics
Schalk Cloete, Carlos Arnaiz del Pozo, Angel Jimenez Alvaro
Summary: This study analyzes the effects of significant advances in CO2 capture and storage (CCS) technologies on future energy systems, and finds that CCS-enabled pathways offer benefits in the hydrogen sector, including reducing hydrogen prices and enabling negative CO2 emissions. Advanced blue hydrogen technologies can also reduce total system costs and increase efficiencies. Co-gasification of coal and biomass is identified as an important enabler of these results. The study suggests that CCS decarbonization pathways can incorporate substantial shares of renewable energy to reduce fossil fuel dependence and increase system resilience.
Article
Thermodynamics
Antonia Helf, Schalk Cloete, Florian Keller, Jan Hendrik Cloete, Abdelghafour Zaabout
Summary: This study investigates the prospects of a biomass-to-hydrogen process configuration for large-scale CO2 removal. The results show that the efficiency gains and the use of advanced gas treatment can significantly reduce the cost of hydrogen production. Moreover, high CO2 prices make this negative-emission technology economically attractive.
ENERGY CONVERSION AND MANAGEMENT
(2022)
Article
Thermodynamics
Carlos Arnaiz del Pozo, Angel Jimenez Alvaro, Schalk Cloete
Summary: This study provides a techno-economic assessment of methanol production from solid fuels, showing that methanol can be produced with reduced CO2 emissions through co-gasification with biomass. It is cost-competitive with gasoline and offers a solution for climate change and energy security in energy importing regions.
ENERGY CONVERSION AND MANAGEMENT
(2022)
Article
Green & Sustainable Science & Technology
Mohammed Nazeer Khan, Mark Lacroix, Coos Wessels, Miet Van Dael
Summary: Wastewater contains a significant amount of cellulose from toilet paper, which can be recovered and converted into useful products. A techno-economic assessment of the entire value chain suggests that under specific conditions, this value chain has potential and could be a promising business case for sludge treatment facilities.
JOURNAL OF CLEANER PRODUCTION
(2022)
Article
Energy & Fuels
Carlos Arnaiz del Pozo, Angel Jimenez Alvaro, Schalk Cloete, Jose Antonio Garcia del Pozo Martin de Hijas
Summary: The increasing share of wind and solar energy in decarbonized electricity systems has created a need for innovative power cycles using unconventional fuels. This study compared different large-scale power plants and their fuel supply infrastructure, specifically focusing on chemically recuperated cycles using MeOH and NH3 as fuels. The results showed that MeOH can be competitive with natural-gas-fired combined cycles at low capacity factors, while NH3 can compete with H2 at higher capacity factors. Liquid fuels present a superior solution when salt cavern storage is unavailable or multi-week fuel storage is highly valued.
Article
Thermodynamics
Carlos Arnaiz del Pozo, Schalk Cloete, Angel Jimenez Alvaro
Summary: This study investigates the potential of ammonia production from local coal and biomass resources with CO2 capture for negative emissions. Two innovative configurations are compared with a benchmark, and the results show lower and higher costs for the E-gas and MHI concepts, respectively. Benchmarking against alternative ammonia supply pathways indicates that the energy security offered by the E-gas configuration may be economically attractive to importers with rising CO2 taxes.
Article
Thermodynamics
Bart Tulkens, Schalk Cloete, Pfunzo Muvhali, Rob Bastiaans
Summary: Low-income communities face a cycle of causality between lack of energy services and insufficient income. This study proposes a novel energy system model to optimize the deployment and dispatch of energy supply and services in a South African village. The results show that optimized technology rollout can save each person over 1500 productive hours per year at a cost below 0.2 $/hour. The study also identifies the optimal order of technology deployment for driving economic development.
Article
Thermodynamics
Schalk Cloete, Carlos Arnaiz del Pozo, Jan Hendrik Cloete, Angel Jimenez Alvaro
Summary: Fuels accounted for 76% of global final energy consumption in 2021, and although efforts to electrify can reduce this share, fuels will still play a leading role in the global energy system. This study focuses on ammonia and methanol as low-carbon fuel alternatives to traditional petroleum fuels, as hydrogen faces challenges in storage and distribution. Four low-carbon fuel production pathways are compared, and it is found that electrolytic fuels struggle to compete with hydrocarbon fuels equipped with CCS. Ammonia or methanol from solid fuels are seen as attractive solutions for affordable carbon-negative energy security.
ENERGY CONVERSION AND MANAGEMENT
(2023)