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Spray cooling technology offers high levels of uniform heat removal with very low fluid volumes and has found recent application in relatively small-scale use cases. Since it is a complex process, research can enable spray cooling to be applied more widely and at larger scales, such as in HVAC, as a means to operate more efficiently. Weather conditions are one of the main parameters that directly affect the effectiveness of spray cooling. This study investigates the spray cooling performance for temperature and humidity conditions in six Australian cities. ANSYS Fluent (2021 R1) software is applied for the numerical simulation. The numerical model is first validated with the available literature before a numerical simulation is conducted to assess each city throughout the year. These include Adelaide, Brisbane, Darwin, Melbourne, Perth, and Sydney. The spray cooling pattern, temperature, and humidity distribution, as well as the evaporation effect on different regions in Australia, is simulated and analysed based on the CFD technique. The results from this study indicate that weather conditions influence spray cooling for all cities, especially in summer. Along the wind tunnel, the temperature significantly drops at the spray cooling area, while the humidity increases. Due to the effect of spray cooling inside the wind tunnel, the temperature at the outlet is still lower than the inlet for all cases. However, the humidity at the outlet is higher than the inlet for all cases. [ABSTRACT FROM AUTHOR]

The continuum and discrete phase interaction could significantly affect the inhaled particle's transport behaviour. The accurate analysis of continuum and discrete phase interaction needs computational fluid dynamics (CFD) and Discrete Element Method (DEM) simulation, which is computationally expensive. Therefore, this study aims to develop a novel machine learning (ML) prediction model from CFD-DEM data to predict pharmaceutical aerosol transport in airways accurately. This study uses the CFD model for the continuum and DEM for the discrete phases. A soft sphere approach was used to calculate the overlap of the colliding particles. Proper validation was performed to ensure the accuracy of the present model. The CFD-DEM model analysed the particle transport in an idealised and realistic airway model, and different methods were used to analyse the transport behaviour. As the flow rate increased from 15 to 60 lpm, the deposition efficiency (DE) significantly improved due to particle interaction, rising from 20 % to 42 % without interaction and from 50 % to a remarkable 76 % with interaction, demonstrating the critical role of particle interaction in enhancing DE across varying flow rates. During the particle-particle interaction, a stagnation point and a high-pressure zone were observed at the airway model's carinal angle. Finally, a ML prediction model is developed from CFD-DEM data, which accurately predicts the pharmaceutical aerosol deposition in airways. The ML prediction model predicts the deposition pattern for different flow rates and particle sizes without CFD-DEM simulations. The present findings and more case-specific investigation would advance the knowledge of aerosol transport in airways and benefit more efficient targeted drug delivery devices. [Display omitted] • An advanced CFD-DEM-ML model for particle transport in airways; • Spring constant significantly influences the flow fields; • Deposition efficiency increases with the flow rate and particle diameter; • Particle-particle interaction significantly increase with the spring constant; • Deposition efficiency is significantly higher at the upper part of the airway. [ABSTRACT FROM AUTHOR]

The efficient generation of high concentrations of fine-particle, pure surfactant aerosols provides the possibility of new, rapid, and effective treatment modalities for Acute Respiratory Distress Syndrome (ARDS). SUPRAER-CATM is a patented technology by Kaer BiotherapeuticsTM, which is a new class of efficient aerosol drug generation and delivery system using Compressor Air (CA). SUPRAER-CA is capable of aerosolizing relatively viscous solutions or suspensions of proteins and surfactants and of delivering them as pure fine particle dry aerosols. In this Computational Fluid Dynamics (CFD) study, we select a number of sites within the upper 17 generations of the human respiratory tract for calculation of the deposition of dry pulmonary surfactant aerosol particles. We predict the percentage of inhaled dry pulmonary surfactant aerosol arriving from the respiratory bronchioles to the terminal alveolar sacs. The dry pulmonary surfactant aerosols, with a Mass Median Aerodynamic Diameter (MMAD) of 2.6 µm and standard deviation of 1.9 µm, are injected into the respiratory tract at a dry surfactant aerosol flow rate of 163 mg/min to be used in the CFD study at an air inhalation flow rate of 44 L/min. This CFD study in the upper 17th generation of a male adult lung has shown computationally that the penetration fraction (PF) is approximately 25% for the inhaled surfactant aerosols. In conclusion, an ARDS patient might receive approximately one gram of inspired dry surfactant aerosol during an administration period of one hour as a possible means of further inflating partly collapsed alveoli. [ABSTRACT FROM AUTHOR]

Smokers are at a higher risk of laryngeal cancer, which is a type of head and neck cancer in which cancer cells proliferate and can metastasize to other tissues after a tumor has formed. Cigarette smoke greatly reduces the inhaled air quality and can also lead to laryngeal cancer. In this study, the upper airway of a 70-year-old smoker with laryngeal cancer was reconstructed by taking a CT scan using Mimics software. To solve the governing equations, computational fluid dynamics (CFD) with a pressure base approach was used with the help of Ansys 2021 R1 software. As a result, the maximum turbulence intensity occurred in the larynx. At 13 L/min, 55 L/min, and 100 L/min, the maximum turbulence intensity was 1.1, 3.5, and 6.1, respectively. The turbulence intensity in the respiratory system is crucial because it demonstrates the ability to transfer energy. The maximum wall shear stress (WSS) also occurred in the larynx. At 13 L/min, 55 L/min, and 100 L/min, the maximum WSS was 0.62 Pa, 5.4 Pa, and 12.4 Pa, respectively. The WSS index cannot be calculated in vivo and should be calculated in vitro. Excessive WSS in the epiglottis is inappropriate and can lead to an airway obstruction. Furthermore, real mathematical modeling outcomes provide an approach for future prevention, treatment, and management planning by forecasting the zones prone to an acceleration of disease progression. In this regard, accurate computational modeling leads to pre-visualization in surgical planning to define the best reformative techniques to determine the most probable patient condition consequences. [ABSTRACT FROM AUTHOR]

In this article, a novel multiscale modeling method is proposed for transient computational fluid dynamics (CFD) simulations of the human airways. The developed method is the first attempt to incorporate spatial coupling and temporal coupling into transient human airway simulations, aiming to improve the flexibility and the efficiency of these simulations. In this method, domain decomposition was used to separate the complex airway model into different scaled domains. Each scaled domain could adopt a suitable mesh and timestep, as necessary: the coarse mesh and large timestep were employed in the macro regions to reduce the computational cost, while the fine mesh and small timestep were used in micro regions to maintain the simulation accuracy. The radial point interpolation method was used to couple data between the coarse mesh and the fine mesh. The continuous micro solution–intermittent temporal coupling method was applied to bridge different timesteps. The developed method was benchmarked using a well‐studied four‐generation symmetric airway model under realistic normal breath conditions. The accuracy and efficiency of the method were verified separately in the inhalation phase and the exhalation phase. Similar airflow behavior to previous studies was observed from the multiscale airway model. The developed multiscale method has the potential to improve the flexibility and efficiency of transient human airway simulations without sacrificing accuracy. [ABSTRACT FROM AUTHOR]

The major problem in understanding the therapeutically targeted drug delivery system in the deeper airways of the human lung is the lack of adequate data of particle transport and deposition (TD) in the transitional and respiratory zones (deeper airways) of the human lung. An understanding of the morphometry of the pulmonary airways and the lungs forms the primary step in a study of pulmonary aerosol deposition. The present study is the first-ever approach to explore the pulmonary aerosol TD in a digital 17-generation human pulmonary airway model. The present numerical study achieved the lack of the particle TD data in the deeper airways of the human lung. This paper presents a 3-D (3-dimensional) CFD (Computational Fluid Dynamics) study of an anatomically realistic 17-generation lung bronchial tree model based on the high-resolution computer tomography (HRCT) data by Schmidt et al. (2004). Physical morphometry is necessary for sufficiently calculating air and particle dynamics in human pulmonary airways with available data on a large number of generations. A Lagrangian-based Discrete Phase Model (DPM) is used to study the particle TD in the 17-generation of the lung airways. The numerical results demonstrate that inertial impaction is dominant in the upper airways and a large percentage of particles is deposited in the upper airways. The numerical results also illustrate that a large percentage of smaller diameter particles leaves through the airway outlet boundary at the 17th generation irrespective of breathing patterns. The escaped particles are considered to continue to follow the airway flow field further downstream after the 17th generation till the 23rd generation and some of them will reach the alveolar sacs region. This computational model could potentially aid in overcoming the nanobiotechnology toxicity problem for drug delivery in the deeper airways. [ABSTRACT FROM AUTHOR]

Plate heat exchangers (PHEs) have become the most popular type of heat exchangers (HEs) for a wide range of daily applications due to their compactness and high thermal performance. The present study aims to expand the understanding of the thermal performance of the basic flat PHE (FPHE) and to develop a more efficient FPHE as well. A new flow arrangement is proposed in order to enhance the thermal performance of the FPHE (modified FPHE). The new flow mechanism is fulfilled by changing the design of the gasket where the inlet and the outlet ports are located on the same side of the thermal plate. Computational fluid dynamics (CFD) has been used to conduct the numerical simulations. The overall simulations have been performed on two FPHEs; the basic and the modified one. Both HEs have identical geometrical dimensions and physical test conditions. Nusselt number (Nu), Stanton number (St), Colburn factor j, friction factor (f), and JF factor are employed to evaluate and compare the thermal performance of the presented HEs. Heat transfer data are collected for single phase (water-water), and for Reynolds number (Re) spans from 250 to 2000. The numerical findings have been validated with benchmark experimental data from the literature. The results show that, Nu and f data of the modified FPHE are respectively up to 70% and 4.4 times those of the basic FPHE. The critical Reynolds numbers (R e c r ) for the modified FPHE are identified. Moreover, JF data of the modified FPHE shows ~0.7%–9% enhancement in the thermal performance with respect to the basic FPHE, hence it could save material and energy for the same heat duty. The findings of the present study have also developed the corresponding correlations for the Nu and f for all cases. [ABSTRACT FROM AUTHOR]

• Newly modified corrugated plate heat exchanger (CPHE) is proposed. • Thorough comparison among the modified CPHE and other PHEs is carried out. • The resulted turbulence kinetic energy of the modified channel is the highest. • Overall thermal performance of the modified CPHE is the best. • The best performance of the modified CPHE takes place at Re=1600. Corrugated plate heat exchangers (CPHEs) have been extensively adopted especially for systems that require high thermal efficiencies such as aerospace and gas turbine power plants. According to several factors (i.e. required heat duty), CPHEs can be optimized to meet the application requirements. However, the number of the required thermal plates (N p) could be very large (N p >40) which in turn would cause several disadvantages (i.e. sever flow maldistribution). Therefore, the present study aims to introduce an innovative modification that can boost the thermal performance of the basic CPHE which in turn would reduce the number of required plates for the same heat duty. The thermal performance of the modified CPHE has been numerically investigated by using Computational Fluid dynamics (CFD) software. The numerical data have been validated with experimental measurement from the literature. The impact of the new modification has been studied on Nusselt number (Nu), fanning friction factor (f), Stanton number (St), Turbulence kinetic energy (TKE), flow maldistribution, j factor, and quality index factor (JF). The result has been compared with previously reported data of the basic corrugated and flat PHEs. At the same mass flow rate, Nu, f , and TKE of the modified CPHE are respectively 1.3, 1.7, and 3.5 times greater than those of the basic CPHE. Moreover, JF data of the modified CPHE are 1.4, and 64 times greater than those of the basic corrugated and flat PHEs, respectively. In addition to the superior thermal performance, the present modification offers larger contact area between the plates which could boost the overall mechanical integrity of the heat exchanger. Thus, this modification could pave the way for CPHEs to be incorporated in new applications that require more compact and durable HEs. The heat transfer correlations of the modified CPHE have been developed. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new cutting method is developed to simulate particle TD in lung airways. • 20 μm particles are mostly deposited in G0-G5 but do not pass through G7. • Over 48% of 5 μm particles can pass through G14 and enter the deeper lung airways. • Escaping rate in each generation decreases with the increase of age. • The total deposition efficiency increases with the increase of age. Understanding the transportation and deposition (TD) of inhaled aerosol particles in human lung airways is important for health risk assessment and therapeutic efficiency of targeted drug delivery. The particle TD into a human lung depends on lung anatomy, breathing pattern, as well as particle properties. The breathing capacity and lung airway diameters can be reduced by about 10% every 10 years after the age of 50. However, the age-specific particle TD in human lungs, particularly in the aged, has not been well understood in literature. This study investigates the particle TD in the lungs of people aged 50–70 years, using computational fluid dynamics (CFD). A new cutting method that splits the lung model into different sections has been developed as a feasible CFD method to simulate the particle TD in G0 to G14 lung airways. The inhalation of micron scale particles with three diameters (5 μm, 10 μm and 20 μm) and a constant air flow rate in inhalation is considered. It is found that different sized particles are deposited in different generation airways. Nearly 100% of 20 μm particles are deposited in the upper lung airways (G0-G5) and no particles pass through G7. Particles can go into deeper airways as their diameter decreases. When the particle size is decreased to 5 μm, over 48% of particles can pass through G14 and enter the deeper lung airways. An increase in age causes more particles to deposit in the upper airway and fewer particles to enter the deeper airways. [ABSTRACT FROM AUTHOR]

In clinical assessments, the correlation between atmospheric air pollution and respiratory damage is highly complicated. Epidemiological studies show that atmospheric air pollution is largely responsible for the global proliferation of pulmonary disease. This is particularly significant, since most Computational Fluid Dynamics (CFD) studies to date have used monodisperse particles, which may not accurately reflect realistic inhalation patterns, since atmospheric aerosols are mostly polydisperse. The aim of this study is to investigate the anatomy and turbulent effects on polydisperse particle transport and deposition (TD) in the upper airways. The Euler-Lagrange approach is used for polydisperse particle TD prediction in both laminar and turbulent conditions. Various anatomical models are adopted to investigate the polydisperse particle TD under different flow conditions. Rossin-Rammler diameter distribution is used for the distribution of the initial particle diameter. The numerical results illustrate that airflow rate distribution at the right lung of a realistic model is higher than a non-realistic model. The CFD study also shows that turbulence effects on deposition are higher for larger diameter particles than with particles of smaller diameter. A significant amount of polydisperse particles are also shown to be deposited at the tracheal wall for CT-based model, whereas particles are mostly deposited at the carinal angle for the non-realistic model. A comprehensive, polydisperse particle TD analysis would enhance understanding of the realistic deposition pattern and decrease unwanted therapeutic aerosol deposition at the extrathoracic airways. [ABSTRACT FROM AUTHOR]

Continuous deposition of workplace pollutant particles on lung airways during respiratory actions seriously threatens the lung health of persons performing tasks in polluted environments. This study aims to analyze the exhalation-driven deposition of fine and coarse occupational pollutant particles in polydisperse form. Computer simulations are conducted to study the patterns of deposition of grain dust, coal fly ash, and bituminous coal particles. Key findings include the observation of early emergence of secondary flows in the real model, a notable shift in deposition patterns towards the post-bifurcation zones, and influence of physical activity intensity on particle deposition. Additionally, deposition primarily occurs near cranial ridge during inhalation, while exhalation leads to deposition in pre- and post-bifurcation zones. PM2.5 deposition is minimal and random in idealized model but becomes more significant and consistent in real model. This research underscores the increased risk of lung diseases for workers in polluted environments during vigorous activity. [Display omitted] • Analysis of exhalation-driven deposition informs pollutant health risks. • Active physical conditions increase deposition. • Deposition comparison of fine (PM2.5) and coarse (PM2.5–10) particles. • High density particles influence lungs health more. • Gravity impact: strong at low flow, weak at high flow when normal to gravity. [ABSTRACT FROM AUTHOR]

For respiratory health risk assessment, it is essential to evaluate the transportation and deposition (TD) of pollutant particles in human lung airways, which are responsible for lung diseases. Studies to date improved the knowledge of the particle TD in airways. However, the understanding of the TD of different pollutant particles in realistic airways has not been fully understood. This study investigates TD of three types of pollutant particles: traffic, smoke and dust, with various sizes ranging from nano- to micro-scales in the mouth–throat and tracheobronchial lung airways of a human lung using computational fluid dynamics (CFD). Three different physical activities are considered: sleeping, resting, and intense breathing, corresponding to inhalation flow rates of Q in = 15, 30 and 60 L/min, respectively. Nearly 99.8% of 10-μm traffic particles are deposited in the upper lung airways considered here. However, the TD efficiency of 10-μm dust particles is reduced to 64.28% due to the reduction in particle density. Nanoparticles have a much smaller deposition efficiency than microparticles because impaction effect of microparticles is stronger. Only less than 10% of 5-nm traffic particles are deposited in the airways for all three flow rates, allowing over 90% of particles to reach the deep lung. An important finding is that the effects of density on the particle TD of nanoparticles are much weaker than that of microparticles. At 15 L/min flow rate, the difference between the deposition efficiencies of the heaviest traffic particles and the lightest dust particles is only 3.5%. The effects of particle density on the deposition efficiencies of nano- and micro-particles are different from each other because impaction and diffusion dominate the TD of nano- and micro-particles, respectively. Density only affects impaction significantly but has little effect on diffusion. [Display omitted] • Particle density only affects impaction significantly but has little effect on diffusion. • Particle density affects particle TD of nanoparticles much less than that of microparticles. • Nanoparticles have a much smaller deposition efficiency than microparticles because impaction effect of microparticles is stronger. • The deposited nanoparticles are more evenly distributed in airways than microparticles. • More particles enter the left than the right side of lung, regardless of particle size and density. [ABSTRACT FROM AUTHOR]

• The velocity and pressure drop in the stenosis airway are significantly increased. • An increase in the diameter of microparticles increases the deposition efficiency. • An increase in the diameter of nanoparticles decreases the deposition efficiency. • The decrease of either particle size or flow rate weakens diffusion mechanism. • To make particles deposit in deep lung, very small, nanoscale particles are needed. The transport and deposition (TD) of inhaled aerosol particles in airways of human lungs are important for therapeutically targeted drug delivery in respiratory tracts. The airflow and particle TD depend on various aspects, including breathing pattern, geometry of lungs, particle properties and deposition mechanisms. In this paper, a computational fluid dynamics (CFD) study is conducted to understand the flow behaviour and PD of both nanoparticles and microparticles (particle diameter = 5 nm, 100 nm, 500 nm, 1 μm, 5 μm and 10 μm) in airways of mouth–throat and tracheobronchial of a human lung under the effect of stenosis. The contribution of impaction and diffusion mechanisms to the TD of particles with different diameters in human lung models with and without stenosis are investigated through numerical simulations using ANSYS FLUENT solver. The study was conducted under two flow rates of 15 L/min and 60 L/min. The stenosis at the right primary bronchi reduces the airway sectional by 75%. It is found that the pressure drop of the stenosis model increases by 83% compared to the healthy model. Over 75% of 10 μm particles are deposited in the mouth–throat and tracheobronchial airways. As the particle size is decreased to 5 nm, less than 10% of the particles are deposited in the airways, allowing over 90% particles to enter deeper part of the lung. The results suggest that the particle deposition efficiency in airways of mouth–throat and tracheobronchial increases with increasing the flow rate as well as the particle diameter because of the inertia impaction mechanism. The contribution of the diffusion mechanism is significantly decreased with the increase of either particle size or flow rate. The predicted particle deposition patterns in the airway with stenosis model would be useful to optimise a patient's treatment for drug delivery in the stenosis airway. [ABSTRACT FROM AUTHOR]