Selected Publications
Metal hydrides (MH) are known as one of the most suitable material groups for hydrogen energy storage because of their large hydrogen storage capacity, low operating pressure, and high safety. However, their slow hydrogen absorption kinetics significantly decreases storage performance. Faster heat removal from MH storage can play an essential role to enhance its hydrogen absorption rate, resulting in better storage performance. In this regard, the present study aims to improve heat transfer performance to positively impact the hydrogen absorption rate of MH storage systems. A novel semi-cylindrical coil is first designed and optimized for hydrogen storage and embedded as an internal heat exchanger with air as the heat transfer fluid (HTF). The effect of novel heat exchanger configurations is analyzed and compared with normal helical coil geometry, based on various pitch sizes. Furthermore, the operating parameters of MH storage and HTF are numerically investigated to obtain optimal values. ANSYS Fluent 2020 R2 is utilized for the numerical simulations. Results from this study demonstrate that MH storage performance is significantly improved by using a semicylindrical coil heat exchanger (SCHE). The hydrogen absorption duration reduces by 59% compared to a normal helical coil heat exchanger. The lowest coil pitch from SCHE leads to a 61% reduction of the absorption time. In terms of operating parameters for the MH storage with SCHE, all selected parameters provide a major improvement in the hydrogen absorption process, especially the inlet temperature of the HTF.
2022
P. Larpruenrudee, N.S. Bennett, Y.T. Gu, R. Fitch, and M.S. Islam, "Design optimization of a magnesium-based metal hydride hydrogen energy storage system", Sci Rep 12, 13436 (2022);
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Hydrogen Energy Storage: Metal Hydride Technique
Metal hydrides (MH) have recently attracted significant interest for hydrogen storage as they provide large storage capacity and a high degree of safety. The main disadvantage, however, is that storage speed is compromised by their low rate of hydrogen absorption. One possible way to accelerate the absorption reaction, and thus improve storage performance regarding incoming hydrogen transfer speed, is to increase the heat transfer rate inside the storage system. Among internal heat exchangers, using helical coil and semi-cylindrical coil heat exchangers significantly improves the heat transfer performance inside the storage system because of the secondary circulation. However, the central area of the storage system still has a lower heat transfer rate as this area is far away from the heat transfer fluid. For this purpose, the development of a heat exchanger structure is considered for the new achievement of this study. A semi-cylindrical coil heat exchanger incorporating a central return tube (SCHE-CR) is first developed from a semi-cylindrical coil heat exchanger (SCHE) to improve heat exchange rate at the MH central area. The tube size's effect on absorption is analysed. Further, a combination of internal and external heat exchangers is considered for further improvement of MH storage performance. The operating parameters of the heat transfer fluid for various heat exchanger configurations are investigated to determine optimal values. Results from numerical simulations indicate that absorption duration reduces by 30 % in the SCHE-CR case compared to the SCHE. Increasing the tube diameter of SCHE-CR results in a 40 % faster absorption reaction. Using SCHE-CR with a cooling jacket reduces the absorption duration by 51 % compared to the SCHE-CR. Among other operating conditions, the operating temperature of the cooling fluid is found to significantly affect the hydrogen absorption reaction with up to a 36 % enhancement of the absorption rate. However, the heat transfer coefficient between cooling fluid and MH, is not found to have a significant effect, as the improvement of the absorption rate is only 8 %. The new MH reactor configuration would be beneficial to improve heat exchange in MH storage applications.
2023
P. Larpruenrudee, N.S. Bennett, Z. Luo, R. Fitch, E. Sauret, and M.S. Islam, "A novel design for faster hydrogen storage: A combined semi-cylindrical and central return tube heat exchanger", Jornal of Energy Storage 71, 108018 (2023);
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Metal hydride storage system (MHSS) has been widely used mostly because of its large storage capacity and high degree of safety. The improvement of the heat transfer performance is one of possible techniques to enhance the overall MHSS performance. The well arrangement of the heat exchanger structure from a semi-cylindrical coil heat exchanger with central return tube (SCHE-CR) significantly reduces the hydrogen absorption duration. However, the modelling of the thermal behaviour for the SCHE-CR during desorption process is missing in the literature. Therefore, this study aims to develop a model for both hydrogen absorption and desorption processes and analyse the thermal performance during the cycle. Phase change material (PCM) is incorporated with the heat exchanger for further improvement of the MHSS performance. The storage is designed under three different PCM configurations, including PCM jacket, pool bed, and capsule. The numerical results report that the duration of the absorption-desorption cycle is reduced by over 50% when using SCHE-CR instead of a helical coil. The PCM configurations, especially the PCM capsule, increase the MHSS performance, especially during the absorption. The duration of one cycle is decreased by at least 39% when combining the SCHE-CR with PCM. The HTF temperature significantly affects the MHSS performance, especially during the desorption. Reduction in HTF temperature reduces the absorption duration by at least 15%, while increasing the HTF temperature reduces the desorption duration by at least 25%. The new MHSS configuration would be beneficial to enhance the heat exchange during the absorption-desorption cycle of industrial MHSS applications.
2024
P. Larpruenrudee, N.S. Bennett, R. Fitch, E. Sauret, Y. Gu, and M.S. Islam, "Investigation of metal hydride hydrogen storage performance using phase change materials", International Journal of Hydrogen Energy 60, 996-1019 (2024);
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Air pollution is the leading cause of different respiratory diseases such as asthma and chronic obstructive pulmonary disease (COPD) that commonly affect respiratory health. Computational fluid dynamics (CFD) has been used to predict the airflow pattern and particle transport within human lungs under disease conditions like obstructed airways. Nevertheless, the combination of the obstructed airways and the aging impact on these diseases under the various flow rates and particle diameters, has not been considered in previous studies. This chapter provides a clear understanding of airflow characteristics and particle transport through obstructions and smaller airways due to aging based on an asymmetric lung model generating from the trachea to the fourth generation. Eight different lung models were used for the numerical simulation. The ANSYS Fluent 19.2 was employed to solve the problems under the finite volume discretization technique. Appropriate grid refinement has been performed for all cases. The results indicate that airflow pattern always changes at the stenosis area. The velocity significantly increases at stenosis area for the first two generations and the smallest diameter size. The maximum pressure drop was located at stenosis area for the first generation of right lung and the fourth generation for the smallest diameter case, whereas the highest pressure was found in the trachea for both conditions. Stenosis areas at first two generations significantly affect higher turbulence intensity while smaller diameters generate lower turbulent fluctuation. The deposition efficiency and deposition fraction were based on the airway volume, particle size, and flow rate. The results of this study enhance the knowledge of airflow characteristics and particle deposition within asymmetric human lungs with stenosis area and smaller diameters.
2021
Airflow Characteristics, Particle Transport and Deposition within the Human Lung Airways
Sydney Metro is the biggest project of Australia’s public transport, which was designed to provide passengers with more trains and faster services. This project was first implemented in 2017 and is planned to be completed in 2024. As presented, the project is currently in the construction stage located on the ground stations of the Sydney Trains Bankstown line (T3). Based on this stage, several construction activities will generate air pollutants, which will affect the air quality around construction areas. Moreover, it might cause health problems to people around there and also the passengers who usually take the train on the T3 line. However, there is no specific data for air quality inside the train that may be affected by the construction from each area. Therefore, the aim of this study is to investigate the air quality inside the train carriage of all related stations from the T3 line. A sampling campaign was conducted over 3 months to analyze particulate matter (PM) concentration, the main indoor pollutants including formaldehyde (HCHO) and total volatile organic compounds (TVOC). The results of the T3 line were analyzed and compared to Airport & South line (T8) that were not affected by the project’s construction. The results of this study indicate that Sydney Metro construction activities insignificantly affected the air quality inside the train. Average PM2.5 and PM10 inside the train of T3 line in the daytime were slightly higher than in the nighttime. The differences in PM2.5 and PM10 concentrations from these periods were around 6.8 μg/m3 and 12.1 μg/m3, respectively. The PM concentrations inside the train from the T3 line were slightly higher than the T8 line. However, these concentrations were still lower than those recommended by the national air quality standards. For HCHO and TVOC, the average HCHO and TVOC concentrations were less than the recommendation criteria.
Air Quality Analysis
The recent outbreak of the SARS CoV-2 virus has had a significant effect on human respiratory health around the world. The contagious disease infected a large proportion of the world population, resulting in long-term health issues and an excessive mortality rate. The SARS CoV- 2 virus can spread as small aerosols and enters the respiratory systems through the oral (nose or mouth) airway. The SARS CoV-2 particle transport to the mouth–throat and upper airways is analyzed by the available literature. Due to the tiny size, the virus can travel to the terminal airways of the respiratory system and form a severe health hazard. There is a gap in the understanding of the SARS CoV-2 particle transport to the terminal airways. The present study investigated the SARS CoV-2 virus particle transport and deposition to the terminal airways in a complex 17-generation lung model. This first-ever study demonstrates how far SARS CoV-2 particles can travel in the respiratory system. ANSYS Fluent solver was used to simulate the virus particle transport during sleep and light and heavy activity conditions. Numerical results demonstrate that a higher percentage of the virus particles are trapped at the upper airways when sleeping and in a light activity condition. More virus particles have lung contact in the right lung than the left lung. A comprehensive lobe specific deposition and deposition concentration study was performed. The results of this study provide a precise knowledge of the SARs CoV-2 particle transport to the lower branches and could help the lung health risk assessment system.
A comprehensive understanding of airflow characteristics and particle transport in the human lung can be useful in modelling to inform clinical diagnosis, treatment, and management, including prescription medication and risk assessment for rehabilitation. One of the difficulties in clinical treatment of lung disorders lies in the patients’ variable physical lung characteristics caused by age, amongst other factors, such as different lung sizes. A precise understanding of the comparison between different age groups with various flow rates is missing in the literature, and this study aims to analyse the airflow and aerosol transport within the age-specific lung. ANSYS Fluent solver and the large-eddy simulation (LES) model were employed for the numerical simulation. The numerical model was validated with the available literature and the computational results showed airway size-reduction significantly affected airflow and particle transport in the upper airways. This study reports higher deposition at the mouth-throat region for larger diameter particles. The overall deposition efficiency (DE) increased with airway size reduction and flow rate. Lung aging effected the pressure distribution and a higher pressure drop was reported for the aged lung as compared to the younger lung. These findings could inform medical management through individualised simulation of drug-aerosol delivery processes for the patient-specific lung.
The recent outbreak of the COVID-19 causes significant respirational health problems, including high mortality rates worldwide. The deadly corona virus-containing aerosol enters the atmospheric air through sneezing, exhalation, or talking, assembling with the particulate matter, and subsequently transferring to the respiratory system. This recent outbreak illustrates that the severe acute respiratory syndrome (SARS) coronavirus-2 is deadlier for aged people than for other age groups. It is evident that the airway diameter reduces with age, and an accurate understanding of SARS aerosol transport through different elderly people’s airways could potentially help the overall respiratory health assessment, which is currently lacking in the literature. This first-ever study investigates SARS COVID-2 aerosol transport in age-specific airway systems. A highly asymmetric age-specific airway model and fluent solver (ANSYS 19.2) are used for the investigation. The computational fluid dynamics measurement predicts higher SARS COVID-2 aerosol concentration in the airway wall for older adults than for younger people. The numerical study reports that the smaller SARS coronavirus-2 aerosol deposition rate in the right lung is higher than that in the left lung, and the opposite scenario occurs for the larger SARS coronavirus-2 aerosol rate. The numerical results show a fluctuating trend of pressure at different generations of the age-specific model. The findings of this study would improve the knowledge of SARS coronavirus-2 aerosol transportation to the upper airways which would thus ameliorate the targeted aerosol drug delivery system.
Genetic variants of severe acute respiratory syndrome coronavirus (SARS-CoV-2) have been globally surging and devastating many countries around the world. There are at least eleven reported variants dedicated with inevitably catastrophic consequences. In 2021, the most dominant Delta and Omicron variants were estimated to lead to more severity and deaths than other variants. Furthermore, these variants have some contagious characteristics involving high transmissibility, more severe illness, and an increased mortality rate. All outbreaks caused by the Delta variant have been rapidly skyrocketing in infection cases in communities despite tough restrictions in 2021. Apart from it, the United States, the United Kingdom and other high-rate vaccination rollout countries are still wrestling with this trend because the Delta variant can result in a significant number of breakthrough infections. However, the pandemic has changed since the latest SARS-CoV-2 variant in late 2021 in South Africa, Omicron. The preliminary data suggest that the Omicron variant possesses 100-fold greater than the Delta variant in transmissibility. Therefore, this paper aims to review these characteristics based on the available meta-data and information from the first emergence to recent days. Australia and the five most affected countries, including the United States, India, Brazil, France, as well as the United Kingdom, are selected in order to review the transmissibility, severity and fatality due to Delta and Omicron variants. Finally, the vaccination programs for each country are also reviewed as the main factor in prevention.
Airway stenosis is a global respiratory health problem that is caused by airway injury, endotracheal intubation, malignant tumor, lung aging, or autoimmune diseases. A precise understanding of the airflow dynamics and pharmaceutical aerosol transport through the multi-stenosis airways is vital for targeted drug delivery, and is missing from the literature. The object of this study primarily relates to behaviors and nanoparticle transport through the multi-stenosis sections of the trachea and upper airways. The combination of a CT-based mouth–throat model and Weibel’s model was adopted in the ANSYS FLUENT solver for the numerical simulation of the Euler–Lagrange (E-L) method. Comprehensive grid refinement and validation were performed. The results from this study indicated that, for all flow rates, a higher velocity was usually found in the stenosis section. The maximum velocity was found in the stenosis section having a 75% reduction, followed by the stenosis section having a 50% reduction. Increasing flow rate resulted in higher wall shear stress, especially in stenosis sections. The highest pressure was found in the mouth–throat section for all flow rates. The lowest pressure was usually found in stenosis sections, especially in the third generation. Particle escape rate was dependent on flow rate and inversely dependent on particle size. The overall deposition efficiency was observed to be significantly higher in the mouth–throat and stenosis sections compared to other areas. However, this was proven to be only the case for a particle size of 1 nm. Moreover, smaller nanoparticles were usually trapped in the mouth–throat section, whereas larger nanoparticle sizes escaped through the lower airways from the left side of the lung; this accounted for approximately 50% of the total injected particles, and 36% escaped from the right side. The findings of this study can improve the comprehensive understanding of airflow patterns and nanoparticle deposition. This would be beneficial in work with polydisperse particle deposition for treatment of comprehensive stenosis with specific drugs under various disease conditions.
2022
