Soot Deposition Research Articles

Determination of the Perpetrator-Victim Position in a Case of Severe Traumatic Brain Injury due to a Less-Lethal Weapon Projectile, Based on Brain Injuries

Less-lethal (or non-lethal) weapons cause lethal and non-lethal injuries; this depends on many factors, including the shot distance and the modifications made to the operation of the weapon and the projectiles. This type of weapon has a similar shape to a firearm, shares the same physical and chemical operating principle and uses the combustion of a chemical substance to eject the projectile. In technical terms, the only difference is the projectile. Currently with the changes in weapons and projectiles, it is difficult to make a correlation. Just like lethal firearm projectiles and due to their operation, they leave macroscopic gunshot residues such as powder tattooing or soot deposition, only occasionally a contusion ring. In addition, there is a variety in the appearance of the entrance wounds. Therefore, it is very important to process the scene and carefully dissect the external wound and the surrounding area and, if possible, the recovery of the projectile. We present a case where a non-penetrating superficial injury to the skull produced trauma consistent with a coup contrecoup brain injury, which allows us to identify the perpetrator-victim position.

Application of a Discrete AlGaN/GaN HEMT Sensor for in‐situ Regenerative Soot Particulate Detection

AbstractAn in‐situ regenerative soot particulate matter sensor for automotive exhaust systems based on a discrete AlGaN/GaN high electron mobility transistor (HEMT) was developed and tested, where charge‐sensitive AlGaN/GaN HEMT was utilized to detect the signal variations caused by the presence of soot particulate matters, and the micro‐hotplate serves as soot deposition, while the self‐heating unit was used for sensing and in‐situ regeneration. The two parts were connected for electrical signal transmission. Soot particulate were generated by a laminar diesel flame with an adsorption rate of 23.29 μg cm−2 min−1 on the sensor surface, resulting in 1.32% sensing response after 20 s deposition and reached saturation after a 12 minute deposition of soot. After soot deposition, the sensor was successfully regenerated when a voltage of 2 V was applied to the micro‐hot plate, causing in‐situ heat‐up to reach 600°C for 30 seconds. Moreover, benefiting from the advantage of discrete structure, the sensor exhibited consistent and stable response characteristics even after undergoing more than 10 consecutive regeneration cycles, and the replaceable micro‐hotplate could further extend the service life of the sensor. These results show that the discrete AlGaN/GaN HEMT sensor can be a promising soot particulate sensing platform for automotive exhaust systems.

Intraoral gunshot injury associated with soot in the deep airways

In suicidal gunshots to the head, the oral cavity ranks among the preferred entrance sites. If the weapon’s muzzle end is located within the mouth, it is to be expected that the cartridge discharge residues are deposited on the buccal and palatal mucosa, the tongue and the pharynx, often in combination with tears of the lips due to the expanding combustion gases. Ensuing from the bullet entrance wound and any concomitant injuries, blood is released into the upper airways and subsequently aspirated into the lung periphery provided that respiration continues for at least a short time. Evidently, this impedes the detection of additional soot deposits in the trachea, bronchi and alveoli. Using the example of an intraoral gunshot with a revolver cal. 357 Magnum, the paper points out that in individual cases it may be possible to prove the presence of gunshot residues in the deep airways.

Investigating the formation of soot in CH4 pyrolysis reactor: A numerical, experimental, and characterization study

Methane pyrolysis is a promising method for eco-friendly hydrogen production, but soot formation and carbon interaction pose challenges for scaling up. Therefore, understanding the dynamics of soot formation and carbon deposition is crucial. This study delves into the intricacies of soot formation in methane pyrolysis under industrially relevant conditions, namely operations at atmospheric pressure, employing a H2:CH4 ratio of 2 and exploring a range of hot zone temperatures (1473 K, 1573 K, 1673 K, and 1773 K) with a 5 s residence time. Utilizing a detailed gas-phase kinetic model with direct carbon deposition reactions, the research adopts the method of moments coupled with a one-dimensional plug flow reactor model to simulate soot formation. The model is validated by characterizing soot particles that were produced in a pyrolysis reactor by means of transmission electron microscopy, Dynamic light scattering (DLS), and Raman spectroscopy. Results show that lower temperatures lead to nucleation-dominated growth, whereas higher temperatures significantly restrain particle growth due to carbon deposition. DLS data indicate a complex balance between particle growth and deposition processes. These findings provide insights into operational parameters that can enhance reactor performance and sustainability in hydrogen production processes by mitigating soot and carbon deposition.

Analysis of Soot Deposition Effects on Exhaust Heat Exchanger for Waste Heat Recovery System

This study investigates the thermal–hydraulic behavior and deposition characteristics of a shell and tube exhaust heat exchanger using a CFD-based predictive model of soot deposition. Firstly, considering the influences of thermophoretic, wall shear stress, and other deposition and removal mechanisms, a predictive model is developed for long-term performance of heat exchangers under soot deposition. Then, the variations in exhaust heat exchanger performance during a 4 h deposition period are simulated based on the model. Subsequently, the variation of deposition distribution and different deposition velocities are also evaluated. Finally, an analysis of the long-term performance of the exhaust heat exchanger under varying gas velocities and temperature gradients is conducted, revealing the performance variations under all engine-operating conditions. Results show that the deterioration in normalized relative j/f1/2 varies from 5.26% to 24.91% under different work conditions, and the exhaust heat exchanger with high gas velocity and low temperature gradient exhibits optimal long-term performance.

Guldborgsund Arson House Fire Experiment and Numerical Investigation

AbstractThis paper describes the Guldborgsund arson house fire experiment performed in Denmark and the subsequent numerical investigation. Gas temperatures were measured with four thermocouple trees, and smoke detector activation times were recorded in all rooms. A two-step approach was used to perform the numerical modelling for reproduction of the fire scene. The measured temperatures in the room of fire origin were used as an input for back calculating the Heat Release Rate (HRR) with the two-zone model Argos. As a next step, this HRR was used in the Fire Dynamic Simulator (FDS) to predict the temperatures and the smoke detectors’ activation times in other rooms. The FDS model was partly build using output files from the laser scanning. A sensitivity analysis is presented, where the effect of nine input parameters was investigated, including HRR, the material properties, the height of the fuel bed, the fire area, level of geometrical detail of the first item ignited etc. This study showed that the measured soot deposition heights on the walls differed from the heights of measured sharp temperature gradients used to indicate the hot smoke layer. The numerical simulations resulted in less than 50% error for most of the temperature measurement points during the fuel-controlled stage of the fire and results were the most sensitive to the input HRR. Material properties in FDS had a significant influence on the computed upper-layer gas temperatures at late stages of the fire.

Numerical investigation of mixing and heat transfer in a 7.9 m JP-8 pool fire

The response of objects engulfed in, and adjacent to, large-scale pool fires is of interest in accident and safety assessments. In this study, Fuego, a low-Mach turbulent reacting flow code was used to study conjugate heat transfer in a 7.9 m diameter JP-8 pool fire. Simulations were designed to replicate past experimental measurements (Blanchat et al., 2006) of incident heat flux to three cylindrical calorimeters in and around the pool fire. Two turbulent combustion models were compared directly - the eddy dissipation concept and a more recently developed unsteady flamelet model. First and second order spatial and temporal discretization schemes were also compared to assess the performance of low-dissipation numerical operators. Heat flux predictions to the transportation size calorimeter outside the fire were within experimental uncertainties. Inside the fire, experimental measurements were higher than predicted values and may have been a consequence of soot deposition and augmented participating media radiation from soot and fuel vapor. Simulation predictions improved in cases where turbulent kinetic energy and mixing were more resolved. This work, and others referenced herein, suggest that spatial resolution on the order of 0.5–1.0 cm may be required to fully resolve fluid instabilities, vortex production between fire plumes and crosswind, soot production, and fuel-air mixing. This presents a substantial computational challenge for safety assessments of engulfed objects in fully turbulent pool fires.

Physicochemical analysis of deterioration affecting the darkening of rock art in Maros-Pangkep, South Sulawesi, Indonesia

This study investigates the darkening processes affecting Maros-Pangkep rock art through a comprehensive multianalytical approach. We integrate in-situ color index measurements using Nix color Pro 2 with various physicochemical characterization techniques, including optical microscopy, XRF, SEM-EDS, Raman spectroscopy, and FTIR. By examining microbial, geochemical, and anthropogenic factors on rock art pigment samples, we establish a clear correlation between the formation of blackish-gray layers and reduced chromaticity values, indicating a significant darkening process. The shift in pigment color from vibrant red or purple to a prevailing blackish-gray hue is attributed to surface accumulation. Surface morphology analysis reveals distinct blackish deposits and delicate white fibrous structures on darkened rock art. Elemental composition analysis demonstrates heightened blackish deposit formation and increased phosphorus content in darkened samples. SEM-EDS characterization exposes gypsum morphology, with filament-like structures prevailing in heavily darkened samples, highlighting the role of both geochemical and microbial factors in deposit layer formation. FTIR spectra results confirm the presence of gypsum minerals, which are attributed to the substrate minerals and/or mineral weathering product, and unveil the existence of organic compounds, indicating microbial activity. Additionally, Raman spectroscopy reveals the anthropogenic contribution, notably soot deposition produced by human activities, to the darkening of rock art. This study underscores the need for a holistic preservation approach addressing natural, human, and microbial impacts on cultural heritage sites. Further research is also needed to conduct cross-sectional stratigraphical analysis to understand the accurate mechanism of the deterioration process on the rock art. Moreover, excavation measures regarding the possible relationship of soot deposition with human activities are also important to be carried out at the sites.

Pathological alterations and COHb evaluations as tools for investigating fire-related deaths in veterinary forensic pathology.

Fire-related deaths are usually a consequence of carbon monoxide (CO) poisoning or shock from thermal injuries. In humans, high levels of carboxyhemoglobin (COHb) concentrations in the blood can support a diagnosis of CO poisoning. In veterinary medicine, few studies investigated the pathological changes and blood COHb% in fire victims, and no data are available on post-mortem changes in blood gas composition due to fire. This study aims to investigate the pathological changes and COHb levels in both animal victims of fire and cadavers experimentally exposed to fire. For this purpose, dogs were selected and subdivided into three groups. Group A comprised 9 adult dogs, and Group B comprised 7 puppies that died under fire-related conditions. Group C was represented by 4 dog cadavers experimentally exposed to heat and smoke. A complete macroscopic, histological, and COHb evaluation were performed on each animal. Animals in Groups A and B showed cherry-red discoloration, thermal-injuries and soot deposits along the respiratory tract. Animals in Group C showed thermal injuries and soot deposits limited to the upper respiratory tract. The mean COHb% values in cadavers in Group C were lower than those observed in the other groups but higher compared to the values detected before the heat and smoke treatment. These findings suggest that both pathological changes and COHb analysis are valid tools for investigating fire-related deaths in dogs. However, the increase of COHb levels in cadavers exposed post-mortem to heat and smoke highlights how the COHb analysis should always be evaluated together with macroscopical and microscopical findings to avoid significant misjudgments in investigating fire-related fatalities in veterinary forensic practice.

Contribution To the Evaluation of Soot Deposit Thickness Evolution and Its Impact on Heat Transfer Within Heavy Diesel Engines: An Innovative Simplistic Procedure

This study deals with a numerical procedure designed and built to evaluate the evolution of soot deposits thickness and their impact on heat transfer for a high-pressure common rail 16V280 marine diesel engine piston. Using a combination of 3D numerical computations and an iterative calculation algorithm, this work reveals the complex relationship between soot deposit, temperature distribution, and piston thermal dynamics. Non-uniform soot deposit distribution is observed, concentrated at the piston bowl peripheral regions. This distribution aligns with theoretical expectations, indicating the influence of the swirl effect. The presence of soot deposits alters the temperature distribution, implying displacement of high-temperature zones towards the bowl region of the piston. The reduction in surface temperature of approximately 14%, is attributed to the lower heat transfer coefficient of deposited layers. This greatly influences the distribution of thermo-mechanical stresses of the piston. The proposed procedure offers an approach to assess the impact of soot deposit on heat transfer. In addition, this study contributes to a better understanding of realistic piston conditions and addresses the challenges introduced by soot deposits in heavy-duty diesel engines by combining the proposed procedure with investigations based on CFD software tools.

Health-related quality of life 1 year after a large-scale industrial fire among exposed inhabitants of Rouen, France: 'The Post Fire 76 Health' study.

A large-scale industrial fire occurred in Rouen, France, in 2019. This study assessed the health-related quality of life of people exposed to its consequences 1 year later. The study population comprised inhabitants of the exposed area and a non-exposed area. A representative sample was randomly selected using a stratified design. Data were collected using a standardized questionnaire to describe fire exposure and to calculate three health-related quality of life scores according to the SF12-v2 scale. After adjustment, descriptive and multivariate analyses were conducted. The sample comprised 4773 participants (response rate 47.7%). In the exposed area, the average mental, physical and overall health scores were 47.5, 52.0 and 73.8 out of 100, respectively. Mean mental and overall health scores were higher in the non-exposed area (49.0 and 76.0, respectively). After adjustment, a lower mental health score was associated with a higher number of perceived types of exposure, reaching -3.72 points [-5.41; -2.04] for five or more different types of perceived exposure. A lower mental health score was associated with soot deposits (-1.04 [-1.70; -0.39]), perceiving odours [(-2.04 [-3.22; -0.86]) up to the day of data collection], and having seen, heard or been awakened by the fire (-1.21 [-1.90; -0.52]). A slightly lower physical health score was associated with soot deposits (-0.57 [-1.07; -0.08]). This study highlighted associations between exposure to the consequences of the industrial fire in Rouen and a deterioration of perceived health-related quality of life 1 year later, particularly the mental health dimension.

Methane pyrolysis for hydrogen production: Modeling of soot deposition by computational fluid dynamics and experimental validation

Methane pyrolysis is an attractive technology to reduce greenhouse gas emissions, since the carbonaceous part of the hydrocarbon is captured into a solid, easier to store than carbon dioxide. In this framework, computational fluid dynamics (CFD) is an excellent tool to simulate the catalyst deactivation and the complex phenomena arising on the carbon surface. We investigated thermal and catalytical pyrolysis of methane in a tubular quartz reactor with an internal diameter of 3.8cm. We modeled soot deposition and added a new surface mass balance that parametrize bed porosity as time-dependent variable. Our model predicts occlusion (clogging) time for empty and packed bed reactor: operating at 1373 K, an empty bed clogs in 15 d, which is coherent with industrial operations. The model well predicts methane conversion in the empty reactor even after 24h time on stream. When a packed bed is used, the experimental conversion follow the predicted activity decay, with deviations due to the size distribution of the carbon during experiments. Radiation is the main heat transfer mechanism (86% of the total heat absorbed by the system), compared to the others involved in this system, i.e., conduction, which is more than 50 times smaller, natural convection, more than 18 times smaller, and forced convection, more than 300 times smaller.

Investigating the Potential of Ghee Precursor-Derived Carbon Nano Onions for Enhancing Interfacial Bonding in Thermoplastic Composites.

In this study, we employed a straightforward flame synthesis process to produce carbon soot containing carbon nano onions (CNOs) using easily accessible ghee oil as a precursor. The ghee oil, with a molecular composition rich in more than 50 carbon atoms, served as an effective source for generating CNOs. The synthesized CNO particles underwent comprehensive characterization through high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) analyses, providing a detailed account of their physicochemical properties. In addition, we explored the direct deposition of CNOs on carbon fiber (CF) surfaces for 5 and 10 min via a soot deposition process. The resulting freeze-fracture images obtained from scanning electron microscope (SEM) offered insights into the morphology of the CNO-deposited CF. Our study aims to shed light on the potential applications of CNOs, focusing on their characterization and the possible benefits they may offer in diverse fields, including but not limited to enhancing interfacial bonding in thermoplastic composites.

Increased black carbon (soot) accumulation during the Anthropocene in a less-developed region of Xinjiang, northwestern China

Records of environmental changes at regional or continental scales in less-developed regions may aid clarification of the onset of the Anthropocene. A sediment core was collected from Bosten Lake in Xinjiang Province, northwestern China, to investigate historical variations of combustion indicators of black carbon (BC), char and soot and to reflect human influences over the past 150 years. Results show that a rapid increase in soot fluxes (over 1.5 times on average) happened after 1950, consistent with the Great Acceleration period as well as establishment of the People's Republic of China, following a rapidly developing economy. Soot flux peaked around the 1960, coincident with wasteland reclamation in Xinjiang Province, decreasing after the year 2000 owing to environmental protection requirements such as desulfurization. Average char/soot ratios before and after 1950 were 0.56 and 0.37, respectively, such low ratios suggest a predominant contribution of soot from long-range transport, while the industrialization in China since the 1950 s may have caused further reduction in the ratios. Sedimentary soot deposition flux in less-developed areas thus recorded key anthropogenic activities occurring in China and supports the onset of the Anthropocene in the mid-20th century, as proposed by the Anthropocene Working Group.

Forensic characteristic of damages caused by offensive grenades detonation

To determine the specific morphological features of damages on the cloth and biological simulator of the human body in the detonation of RGD-5 and RGN fragmentation hand offensive grenades. The study was carried out on the 12 targets from a biological simulator of the human body wrapped in cotton cloth by detonation of examined grenades at a distance of 50 cm and 1 m from the target. The character and features of damages of cloth and human body biological simulator, features of soot deposition made it possible to determine specific signs for each of examined offensive grenades types. The complex of obtained data allows to determine with high accuracy the detonation distance and the type of explosive device.

Study of Soot Deposits during Continuous Methane Pyrolysis in a Corundum Tube

Methane pyrolysis is one of the promising methods for producing low-carbon hydrogen, while one of the main problems of methane pyrolysis technology is soot clogging of the reactor space. In this work, soot deposits were studied during continuous methane pyrolysis in a corundum tube with an inner diameter of 50 mm. Experiments were carried out at temperatures of 1000 °C, 1050 °C, 1100 °C, 1200 °C and 1400 °C with methane flow rates of 1 L/min and 5 L/min. Each experiment lasted 1 h. The formed soot accumulated inside the reactor (corundum tube) and the connected filter, where the gaseous product of methane pyrolysis was separated from the soot. The gaseous product was studied by gas chromatography. The soot was studied by SEM, BET and ICP-MS. With an increase in the temperature of the pyrolysis process from 1000 to 1200 °C, the hydrogen yield increased from 28.64 to 92.74% and from 1.10% to 72.09% at a methane flow rate of 1 and 5 L/min, respectively. The yield of soot increased from 1.28 g at 1000 °C to 43.9 g at 1400 °C (at a methane flow rate of 1 L/min). With an increase in the flow rate of methane from 1 to 5 l/min, the yield of soot at 1200 °C increased by almost two times to 75.65 g. It was established that in the region of the reactor where maximum heating occurs, the accumulated soot sinters and forms dense growths. At 1050 °C, the particle size of soot varies from 155 to 650 nm, at 1200 °C—from 157 to 896 nm, and at 1400 °C—from 77 to 532 nm. The specific surface of soot was 3.5 m2/g at 1000 °C and 8.0 m2/g at 1400 °C. The purity of the produced carbon black was about 99.95%. This study is useful in the selection of materials and technical solutions for a pilot plant for methane pyrolysis.

PGM-free metal oxide nanoarray forests for water-promoted low-temperature soot oxidation

In this study, PGM free metal oxide based nanorod array (nanoarray) forests have been conformally integrated onto the millimeter-sized channel walls and microscale pores of SiC diesel particulate filter (DPF) substrates using scalable microwave-assisted hydrothermal and dip-coating methods. High-efficiency and robust low temperature soot oxidation is successfully achieved using such a new type of cDPFs as a result of i) promoted tight soot-catalyst contact through spontaneous soot deposits in-between nanorods, ii) highly dispersed loading of LaSrCoO3 perovskite oxidation catalysts onto ZnO nanorod arrays, effectively mitigating active site blockage by soot deposition. The light-off temperature of soot oxidation was lowered to 250 °C in oxygen, a 250 °C decrease compared to that of the commercial Pt based catalyst, due to the abundant oxygen vacancies enabled by the LaSrCoO3/ZnO (LSCO/ZnO) nanorod array catalysts. The performance of the catalyst was further enhanced to initiate the soot oxidation at ∼150 °C with co-fed gas of NO, due to the LSCO catalyzed NO2 formation and its favorable oxidation with soot at low temperature. Furthermore, the nanoarray supported perovskite catalyst shows excellent stability and activity after 120 h of hydrothermal aging at 650 °C. Soot oxidation Tmax is lowered from 542 °C to 510 °C under 6 % water steam condition due to the formation and promotion effect of oxidative -OH species. In situ DRIFTS study reveals that such -OH species form at various catalyst surfaces and interfaces, pointing to a potentially generic water promotion effect for solid/solid interfacial catalytic oxidation under humidity condition. Finally, the mechanistic soot oxidation pathways under O2, NO2, and H2O feeds are proposed for understanding the low-temperature soot oxidation behaviors over the nanoarray supported perovskite catalysts.

Effect of ash on temperature and particulate emission characteristics of diesel particulate filter during active regeneration

As one of the most effective devices to reduce particulate emission from diesel engines, the diesel particulate filter (DPF) has been widely used. However, long-term use of the DPF can cause a large amount of ash to deposit in it, which can significantly affect its performance. In this study, a burner was utilized to deposit ash, derived from four different lubricating oil additives (zinc dialkyl dithiophosphate (Zn-based), calcium sulfonate (Ca-based), magnesium sulfonate (Mg-based), and composite), into four DPFs with the same specification. The four ash-loaded DPFs and a fresh ashless DPF were subsequently tested for active regeneration on an engine bench at the same soot load. The temperature and particulate emission characteristics of the DPFs were measured using thermocouples and a particulate analyzer. The peak regeneration temperature of ash-loaded DPFs moved forward when compared to the fresh DPF, and the peak regeneration temperature of Mg-based DPF reached 694 °C and moved forward to the axial position of 71.5 mm. A low temperature zone appeared at the rear end of edge channels, forming a large temperature gradient up to 75.5 °C/cm. The emission of nucleation-mode particulates at each DPF outlet increased to different degrees during active regeneration, especially for the Zn-based DPF, whose particulate concentration even approached 108 #/cm3. The X-ray computed tomography (X-CT) images of ash-loaded DPFs showed that the distribution of ash in each DPF was quite different, and ash plugs or bridges appeared in the middle and front of some channels, forming a strong blocking effect. It is due to the presence of ash that the soot deposition position moved forward and the wall-flow velocity rose, which increased the local soot density, causing the peak regeneration temperature to rise and move forward. The increase in wall-flow velocity reduced the diffusion filtration efficiency of ash-loaded DPFs, so escaped particulates that were broken up from soot agglomerate burning increased.

Design of an Optimum Compact EGR Cooler in a Heavy-Duty Diesel Engine towards Meeting Euro 7 Emission Regulations

Exhaust gas recirculation (EGR) has been an efficient emission treatment strategy employed in internal combustion engines (ICEs) to cope with NOx emission limits since the introduction of Euro 4 regulations for heavy-duty commercial vehicles. A portion of the exhaust gas is fed back into the intake port, replacing O2 in the fresh air with inert CO2 from the exhaust gas, resulting in a reduction in the combustion temperature and, hence, a reduction in NOx emissions. Considering the high exhaust temperature, this process increases the charge mixture temperature and degrades the volumetric efficiency of the engine. EGR coolers have been introduced as vital parts of EGR exhaust treatment systems with the aim of reducing the intake port temperature to increase volumetric efficiency and further reduce combustion temperatures. EGR coolers are heat exchangers (HXs) that generally employ engine coolant to reduce the EGR temperature with effectiveness values around 0.7~0.85 and downgrade with engine usage owing to soot deposition. Increasing the effectiveness of the EGR cooler has a positive effect on engine volumetric efficiency and reduces NOx, particulate matter (PM), and fuel consumption. The current study involved the design of a microchannel HX for a 500 PS heavy-duty Euro 6 diesel engine EGR cooler. The mechanical and thermal-hydraulic design calculations of the proposed HX were performed using Mathematica software. The optimum HX dimensions for the required boundary conditions were determined, and the performance of the EGR cooler was analyzed for the current and proposed options. Furthermore, Diesel-RK software was used to model the engine performance with NOx, PM, CO2 emissions, and fuel consumption predictions. The results show that the newly proposed microchannel HX design improves NOx, PM, and specific fuel consumption by 6.75%, 11.30%, and 0.65%, respectively.

Studies on Performance Deterioration of a Low Bypass Turbofan Engine in Service

The performance deterioration of a low bypass turbofan engine is analyzed to find out its causes. The performance parameters are compared with their limitations for a specific throttle setting. Dirt buildup, soot deposit, de-twisting of turbine blades, malfunction of atomizers and fuel system accessories are found to degrade the engine health and performance before the intended service period. Periodic compressor wash and engine maintenance, cleaning or replacement of fuel filters and good assembly practices are found beneficial in addressing the issues and retaining the engine performance.