Exhaust Ventilation Research Articles

Comparative analysis of different CFD turbulence models for a diesel pool combustion event in an underground mine: a case study

ABSTRACT Underground mine fires are dangerous, consume resources, and emit pollutants. Therefore, acquiring in-mine data for fire research is hazardous and expensive due to unsteady temperature changes and toxic gas emissions. Computational fluid dynamics (CFD) models are often developed to mimic airflows and combustion-associated heat transfer. However, research on the performance evaluation of the CFD turbulence models to mimic fire events is limited. This paper summarises the modelling results for a diesel pool fire event in an experimental underground mine that uses an exhaust ventilation system. A fire dynamics simulator (FDS) model was developed to show the spatio-temporal temperature evolution. Reynolds-Averaged Navier-Stokes and large eddy simulation (LES) models were developed using ANSYS Fluent to model species transportation in the transient-state combustion event. LES models showed the closest agreement with the experiments but required the most computing resources. Similar exercises will assist the mine operators in emergency preparedness and in training their safety teams.

Numerical study on smoke temperature and exhaust efficiency in electric cable tunnel

Cable tunnels are the lifeline of cities. Once a serious fire occurs on cables, the toxic smoke generated by cable combustion spreads and escapes, causing serious harm to the surrounding environment and personnel. The heat generated can also ignite nearby combustibles, causing casualties and property damage. Based on the above issues, using fluid dynamics methods, fire dynamic simulation was used to simulate cable tunnel fire scenarios under four variables: wind speed, fire source power, smoke outlet height, and smoke exhaust airflow. The temperature distribution law of the ceiling smoke layer inside the cable tunnel, smoke generation law, tunnel smoke exhaust efficiency, and other factors were clarified, revealing the impact mechanism of the above factors on tunnel fire smoke exhaust efficiency and smoke performance improvement methods. The research results indicate that the combination mode of exhaust air volume and ventilation air speed can effectively control tunnel fire smoke, providing a reference for the fire prevention design of cables in urban cable tunnels.

Semi-quantitative health risk assessment of heavy metal dust exposure among nail technicians using the SQRA technique and Monte Carlo simulation.

Nail technology, including the application of artificial nails and nail care, is a developing sector of the global beauty industry. Nail technicians are exposed to a variety of chemical substances through inhalation, as they spend extended periods of time in close proximity to these materials. This study aimed to evaluate the semi-quantitative health risk of dust-containing heavy metals among nail technicians. This analytical descriptive study employed the risk assessment method provided by the Singapore Occupational Health Department to evaluate the health hazards of lead, cadmium, nickel, chromium, and manganese. Dust samples from nail filing were collected from the respiratory zone of 20 nail technicians following the NIOSH 7300 method. The samples were analyzed using ICP-OES instrumentation. Monte Carlo simulation was utilized to characterize the risk and its uncertainties. Manganese and cadmium had the highest and lowest mean concentrations, respectively. The risk scores of the metals ranked from highest to lowest were as follows: . All five metals had risk rankings below 2.8, signifying a minimal risk level. Sensitivity analysis using Spearman's correlation coefficient demonstrated a positive relationship between concentration, daily hours of exposure, and the number of workdays per week with the risk score (RR) and exposure level (ER). Conversely, the variable of weekly working hours (W) showed a negative correlation with these parameters. Despite the low-risk level of the examined metals, continuous exposure and potential long-term effects on nail technicians warrant preventive measures. Recommendations include implementing local exhaust ventilation systems, using table fans, establishing work-rest cycles, wearing N95 dust masks, and using reputable and high-quality nail polishes.

Compatibility of integrated physical barriers and personal exhaust ventilation with air distribution systems to mitigate airborne infection risk

This study investigated the effectiveness of integrating desk partitions and personal exhaust ventilation to mitigate airborne infection risks in areas where people sit closely together. Experiments were conducted in a test chamber equipped with different air distribution systems, including two different mixing and one displacement ventilation. N2O tracer gas was utilized to study airborne transmission between occupants. Results showed effectiveness of preventive measures varied depending on air distributions. In the absence of preventive measures, mixing ventilation systems exhibited higher infection risk compared to displacement ventilation. After the introduction of physical barriers, N2O concentration increased at two measurement points in presence of one of the mixing ventilation systems. In contrast, the other mixing ventilation and displacement ventilation showed a reduction in N2O concentration, up to 63 % and 43 %, respectively, depending on measurement points. Combination of physical barriers and personal exhaust ventilation consistently reduced N2O concentration by 34 % to 83 %, depending on measurement point's location and type of air distribution. Furthermore, higher airflow rates of personal exhaust increased efficiency of proposed strategy in limiting infection risk. This study supports employing physical barriers and personal exhaust ventilation to reduce airborne infection risks. Tailoring preventive measures to specific air distribution system is crucial.

Greenhouse Gas Payback Time of Different HVAC Systems in the Renovation of Nordic District-Heated Multifamily Buildings Considering Future Energy Production Scenarios

The European Union (EU) has implemented several policies to enhance energy efficiency. Among these policies is the objective of achieving energy-efficient renovations in at least 3% of EU buildings annually. The primary aim of this study was to offer a precise environmental comparison among four similar district-heated multifamily buildings that have undergone identical energy efficiency measures. The key distinguishing factor among them lies in the HVAC systems installed. The chosen systems were as follows: (1) exhaust ventilation with air pressure control; (2) mechanical ventilation with heat recovery; (3) exhaust ventilation with an exhaust air heat pump; and (4) exhaust ventilation with an exhaust air heat pump with a Photovoltaic (PV) panel. This study involved a life cycle assessment that relied on actual material data from the housing company and energy consumption measurements. This study covered a period of 50 years for thorough analysis. A sensitivity analysis was also conducted to account for various future scenarios of energy production. The findings revealed that the building with an exhaust air heat pump exhibited the lowest greenhouse gas emissions and the shortest carbon payback period (GBPT), needing only around 7 years. In contrast, the building with exhaust ventilation without heat recovery showed the highest emissions and the longest carbon payback period (GBPT), requiring approximately 11 years. Notably, the results were significantly influenced by future scenarios of energy production, emphasizing the crucial role of emission factors in determining the environmental performance of distinct renovation scenarios.

Airborne Benzene Concentrations Increase Trans, Trans-Muconic Acid (tt-MA) Levels and Liver Function in Workers in The Manufacturing Industry

The use of benzene as a solvent in the manufacturing industry can be dangerous because it is volatile, toxic, and carcinogenic. Exposure to benzene occurs through inhalation of the chemical in the air, which can enter the human body through the respiratory system. The levels of trans, trans-Muconic Acid (tt-MA), which is used to metabolize benzene, can be affected by the amount of exposure to the chemical. This study aims to determine the differences in exposure to benzene in the air by measuring the tt-MA indicators and liver function of workers in the manufacturing industry. This research uses an observational and cross-sectional approach, with a population of 158 employees from both administration and production units. The sample size for the study is 16 respondents, selected using the consecutive sampling technique. The research instrument uses a questionnaire and examines urine samples using the in-house method. Blood samples are examined using IFCC 37 C. The data is processed using the independent-sample t-test and Pearson correlation. The results show that the level of benzene in the air is below the threshold of 0.5 ppm. However, there is a significant difference in the results of tt-MA and SGOT (p<0.05), while the levels of SGPT (p>0.05) show no significant differences. In conclusion, there are differences in the tt-MA and SGOT exposure levels between workers in the production and toxicity units, while SGPT does not show significant differences. It is recommended that the industry maximizes the use of local exhaust ventilation and prohibits smoking.

Calculation of a heat exchanger using heat pipes in the exhaust air heat recovery system

Objective. The purpose of the work is to develop practical recommendations for the design and manufacture of a heat exchanger using heat pipes, which could find widespread use in heating, ventilation and air conditioning systems at facilities for various purposes. Method. The research is based on methods of thermodynamic analysis, full-scale and computational modeling of processes and objects of refrigeration and cryogenic technology, air conditioning and life support systems. Result. The implementation of the practical recommendations studied in the work on the use and design of heat exchangers using heat pipes in ventilation, heating and air conditioning systems will provide significant savings in energy spent on heating and/or cooling the air supplied to the room served by the HVAC system. To reduce heat loss in a building, it is rational to maintain air balance and compensate for the exhaust air with an organized influx of outside air, to heat which the heat of the removed exhaust air is utilized. Conclusion. Compared to a heat exchanger based on a glycol recuperator, a regenerator using heat pipes is less energy-intensive, requires virtually no maintenance, and is also more energy efficient due to the absence of a pumping device that requires electricity in the design. At the same time, the ability to completely separate the supply and exhaust ventilation flows of the regenerator on heat pipes is preserved, which is extremely in demand in medical institutions, due to the need to comply with strict sanitary standards.

Health and Safety Executive research on wood dust exposure controls in British manufacturing.

To generate new intelligence on occupational exposure to wood dust in woodworking manufacturing activities in Britain, the Health and Safety Executive (HSE) performed 22 occupational hygiene site visits to assess exposure and exposure controls between 2014 and 2017. The work aimed to characterise good practice and therefore sites with a poor health and safety record, as identified from HSE inspection records, were not invited to participate. Sites selected covered furniture production, joinery, saw milling, and boat building and repair. Twenty-three follow-up telephone interviews were also carried out across 15 of the companies with supervisors and managers to explore how they tried to promote good practice among the workforce, and if there are any potential challenges encountered. The aim of the interviews was to gain a better understanding of how to enable organisations to improve the management of wood dust exposure. This study found that 6.0% of all wood dust exposure measurements (15 out of 252) were above 5 mg/m³, and 17.6% of exposures to hardwood dust or mixtures of hardwood and softwood dust (38 out of 216) were above 3 mg/m³ (the then current and future workplace exposure limits). Sanding, cleaning, and maintenance activities were of particular concern. Improvements to exposure controls are required, in particular, improvements to local exhaust ventilation controls for hand-held power tools and hand sanding. The management, selection, and use of respiratory protective equipment were poor. All the managers and supervisors recognised that exposure to wood dust can pose serious health risks, and that controls were crucial to protecting workers' health. The findings from the telephone interviews suggest that supervision and provision of information about the health effects of exposure to wood dust were common approaches that organisations used to raise awareness and promote good practice, in relation to managing wood dust exposure. Worker attitudes towards controls, such as perceptions that they hinder task completion and habitual ways of working, were identified as factors influencing the use of controls. Risk communication approaches that focus on increasing workers' awareness of their susceptibility to ill-health using credible sources, such as peers, can help enhance the uptake of messages on the use of controls. Financial constraints were identified as a challenge to improving the control of wood dust, particularly for small companies.

ПРЕДПОСЫЛКИ К РАЗРАБОТКЕ СИСТЕМ ОБЕЗЗАРАЖИВАНИЯ ВОЗДУХА СВИНОВОДЧЕСКИХ ПОМЕЩЕНИЙ С ПОМОЩЬЮ ЭЛЕКТРОФИЛЬТРОВ

Studies of microclimate parameters have shown the influence of microbial contamination on the productivity, growth and development of young pigs. It is known from the literature that exceeding the level of microbial contamination by 5 percent led to a decrease in the growth of piglets at weaning by 13.3 percent, in fattening pigs - to a decrease in live weight at slaughter by 3.7 percent. In addition, infectious diseases caused by pathogenic microorganisms affect the productivity of animals. For example, pneumogastroenteritis, transmitted aerogenically, affects from 30 to 95 percent of suckling piglets and weaning piglets. The damage caused by animal disease takes form of loss in productivity, death of sick animals and forced slaughter, as well as treatment costs. One of the promising and effective ways to clean the ventilation air in pig-breeding premises is the use of electrofiltration, including a wet electrofilter. There is little information in the scientific literature on the issues of disinfection of the air environment of pig-breeding premises from microbial contamination using electrofilters, which necessitates a more thorough consideration of this issue. (Research purpose) The research purpose is substantiating the prerequisites for the development of a methodology for determining the effectiveness of air disinfection with wet electrostatic filtering. (Materials and methods). The available studies on supply and exhaust ventilation systems and methods for determining the effectiveness of air purification by electrofilters from microorganisms were reviewed. Cited their shortcomings. (Results and discussion). It was found that wet electrostatic precipitators in the process of air purification generate ozone into the air, which is capable of destroying up to 95-99 percent of the population of dangerous microorganisms. It has been shown that by modernizing the air purification system in terms of improving the mechanisms for controlling ozone generation with a wet electrostatic precipitator, it is possible to improve the quality of the air environment by disinfecting the air with ozone. (Conclusions) It was determined that the effectiveness of cleaning the air of pig-breeding premises from microorganisms using wet electrostatic precipitators is relevant, further theoretical and experimental studies are needed.

Exploring the limits of current ventilation systems and the unexplored potential

This paper compares the current generation of ventilation systems: natural ventilation, exhaust ventilation, and balanced ventilation, and weighs them against an ideal benchmark case. To achieve this, a transparent, selfdeveloped evaluation framework is constructed. This assessment framework is used to calculate three different and distinct performance indicators, namely CO2, moisture, and energy losses. The performance indicators are used to show the weaknesses and strengths of the systems in terms of indoor air quality (IAQ) and energy consumption, which are used to introduce a novel concept in terms of air recycling to increase IAQ and reduce energy consumption.

Simulation-based assessment of natural and mechanical ventilation solutions for renovated apartment buildings in Denmark

Many European buildings require renovation, often involving window replacements and improved airtightness, leading to increased mold risk and indoor air quality (IAQ) issues. Solutions include adjustable air inlets with mechanical exhaust or balanced heat recovery ventilation. Using building performance simulations, we studied control strategies for renovated apartment building with natural or mechanical ventilation. CO2 - controlled air inlets proved most effective for IAQ and energy reduction. In different apartment positions, air inlet performance varied based on available stack effect. Mechanical exhaust cases were less affected by airtightness changes. Altogether, the mechanical ventilation was more robust, but all strategies were sensitive to closed doors.

Safe by process design (SbPD) strategies based on proper measures to mitigate nanoparticle exposure in industrial settings

Due to its potential to develop new added value products, a staggering number of nanoparticles (NPs) is already available on the market. Moreover, this increase is expected to continue in the future. However, there is a lack of knowledge on the level of exposure to nanoparticles, and the information related to possible adverse health effects is scarce. Furthermore, there is very little studies concerning the effect of risk management measures (RMMs) on the levels of exposure to nanoparticles at workplaces, compared to the number of exposure situations that can be distinguished.This study focuses on 5 case studies covering different types of materials, assessing the effectiveness of targeted mitigation strategies applied during the production process. Customized mitigation measures were applied in each industrial scenario to minimize exposure levels. The effects on the particle concentration levels using source enclosure, partial or full, combined with local exhaust ventilation systems (LEVs), was evaluated to generate new knowledge to support the definition of informed safe by process design approaches when dealing with NPs. This study demonstrates that technological advancements can significantly reduce work-related exposures. The findings underscore the importance of tailored mitigation measures due to the diverse range of potential sources and activities in industrial scenarios.

Effectiveness of Cadaver Tables with Local Exhaust Ventilation in Reducing Formaldehyde Levels

Formaldehyde, which is exposure in the workplace, is very dangerous for health, especially for students, staff and lecturers in the anatomy laboratory room. Cadaver tables with local exhaust ventilation (LEV) in previous studies were used to reduce formaldehyde levels in the anatomy room. This study aimed to determine the effectiveness of a cadaver table with local exhaust ventilation to reduce formaldehyde exposure. Using a pre-post study, this study showed that a cadaver table with local exhaust ventilation can reduce formaldehyde exposure significantly (p<0.001) with a confidence interval of 2.715–2.186. The percentage reduction in formaldehyde levels at each measurement point was 31% - 89% (min-max). This showed that the cadaver table with LEV was effective in reducing formaldehyde levels.

Особенности газодинамики испытательного бокса для наземных испытаний микроразмерных турбореактивных двигателей

The features of testing microscale turbojet engines on the test bench of the D.F. Ustinov BGTU “VOENMEH” in different weather conditions and with different engine locations relative to the exhaust ventilation pipe are discussed. The problems that arise during testing of micro scale turbojet engines are identified, and the influence of climate conditions on engine operation and test stand operation is revealed.

Ventilation's role in adaptable school buildings: Comparing traditional and adaptable strategies through life cycle assessment

Adaptable buildings are a promising enabler in the transition towards a more circular economy, with the ambition of using materials as efficiently as possible. To exploit adaptable buildings to their full potential, HVAC designers should critically rethink how to design technical services and ventilation systems in particular. This case study illustrates how five ventilation strategies perform from an environmental point of view in a school building where the configuration of the floorplan changes every five years, each of the changes reflecting a pedagogical vision. Consequential LCA is used to assess the environmental impact. A decentralized balanced mechanical ventilation system, which requires almost no adaptations when the configuration changes, has the lowest environmental impact while mechanical exhaust ventilation has the highest. However, when the configuration of the floorplan layout alters more rapidly, the relative environmental impact of the latter decreases substantially. The main conclusion is that, in a flexible context, the material-related environmental impact gains importance over the energy-related impact. With respect to this conclusion, a key finding is that minimizing the material use of ductwork (rather than oversizing ductwork dimensions to decrease the energy consumption of the fan) is more sustainable from an environmental point of view. Finally, distributing the ductwork over two shafts offers more flexibility and results in a lower environmental impact as this allows for the use of smaller dimensions of ductwork.

Aerosol and surface contamination assessment of a novel ventilated infectious aerosol containment device.

Healthcare personnels (HCPs) are at risk of respiratory infectious diseases during patient care activities. HCPs rely primarily on personal protective equipment to prevent pathogen exposures, but there is a need to develop alternative, or complementary control strategies, including engineering controls. The objective of this study was to evaluate the ability of the 3 designs (denoted D1A, D1B, and D2) of the University of Utah Containment Ventilation for Exposure Reduction (U-COVER), a protective barrier enclosure device to contain respirable aerosols when placed over a simulated patient. The 2 primary performance metrics were the percent reduction in: (i) the concentration of respirable aerosols in the simulated breathing zone of an HCP, and (ii) surface contamination outside the device, which were tested using salt aerosols and fluorescein aerosols, respectively. Briefly, salt or fluorescein aerosols were generated as though expelled by a prone patient under 3 conditions: (i) no device (control), (ii) with the device but without exhaust ventilation, and (iii) with the device with exhaust ventilation. Device D2 was also tested under simulated use conditions, in which cardboard "arms" were placed inside the device ports. All 3 device designs showed the ability to reduce particle concentrations in the simulated HCP breathing zone and on surfaces by >99% with exhaust ventilation compared to the control condition. Without exhaust ventilation, device performance was lower and highly variable. Under simulated use conditions, device D2 reduced particle concentrations in the simulated HCP breathing zone by ≥91% and on surfaces by >99% relative to control for all combinations of "arms" tested. The U-COVER device demonstrates excellent aerosol containment and warrants further testing with dynamic simulated or actual use conditions.

A control banding method for chemical risk assessment in occupational settings in France.

This study describes a method whose aim is to help companies assess the chemical occupational risks related to labeled products and industrial chemical emissions. The method is intended to be used by industrial hygienists at the scale of one company. Both inhalation and cutaneous exposure routes are taken into account. The method relies on a control-banding scheme. A work situation is described by exposure parameters such as the process or the local exhaust ventilation and by the hazard of the product. Each possible value of the parameters is associated with a "band," which is associated with an integer value. The multiplication of these values results in a score, which represents a priority for intervention. The higher the score, the more the situation warrants investigation for implementing prevention measures, such as chemical substitution and the addition of local exhaust ventilation. To simplify communication, the priority is associated with a colored priority band: red for "very high priority," orange for "high priority," and green for "moderate priority." The priority bands are computed for all work situations performed in a company. An example of the use of this method is described in a French façade insulation company. A tool named Seirich was developed to implement this method and promote good practices for helping industrial hygienists in the prioritization of interventions for reducing chemical risk in France.

Numerical parametric analysis of the decomposition and propagation of combustion products in a confined environment in the early stages of a fire

Numerical research findings are presented on the patterns of spread of thermal decomposition products of wood-based materials in confined spaces isolated from the external environment. Based on the experimental data, a physical problem statement was formulated and a mathematical model of heat and mass transfer was developed for rooms with the most typical sources of fire hazard. The experimental and numerical research findings were obtained for the conditions corresponding to compartments isolated from the external environment (e.g., rooms at dedicated facilities, like ships, small and medium-sized rooms) and to underventilated rooms. The performed experiments and calculations revealed satisfactory agreement in the findings and demonstrated the validity of the proposed model of heat and mass transfer. Wood was used as the main material in fires. A comparative analysis was also carried out for paper of different quality. The modeling was performed for the most frequent causes of fires: careless handling of fire, unsafe operation of heating equipment and electrical short circuits. The rates of growth of thermal decomposition product concentrations were determined for different distances from the material. The impact of a number of factors on the characteristics under study was determined. These are the fire and room sizes, fire cause, supply and exhaust ventilation. The data were extrapolated to the conditions corresponding to business, warehouse and residential premises.

Assessment of Occupational Health Risks for Maintenance Work in Fabrication Facilities: Brief Review and Recommendations

BackgroundThis study focuses on assessing occupational risk for the health hazards encountered during maintenance works (MW) in semiconductor fabrication (FAB) facilities. ObjectivesThe objectives of this study include: 1) identifying the primary health hazards during MW in semiconductor FAB facilities; 2) reviewing the methods used in evaluating the likelihood and severity of health hazards through occupational health risk assessment (OHRA); and 3) suggesting variables for the categorization of likelihood of exposures to health hazards and the severity of health effects associated with MW in FAB facilities. MethodsA literature review was undertaken on OHRA methodology and health hazards resulting from MW in FAB facilities. Based on this review, approaches for categorizing the exposure to health hazards and the severity of health effects related to MW were recommended. ResultsMaintenance workers in FAB facilities face exposure to hazards such as debris, machinery entanglement, and airborne particles laden with various chemical components. The level of engineering and administrative control measures is suggested to assess the likelihood of simultaneous chemical and dust exposure. Qualitative key factors for mixed exposure estimation during MW include the presence of safe operational protocols, the use of air-jet machines, the presence and effectiveness of local exhaust ventilation system, chamber post-purge and cooling, and proper respirator use. Using the risk (R) and hazard (H) codes of the Globally Harmonized System alongside carcinogenic, mutagenic, or reprotoxic classifications aid in categorizing health effect severity for OHRA. ConclusionFurther research is needed to apply our proposed variables in OHRA for MW in FAB facilities and subsequently validate the findings.

Assessing occupational exposure of airborne PMs and TVOCs in the nail salons in Tehran city, Iran

There are concerns about the health of nail salon technicians due to the inherently harmful agents such as volatile organic compounds (VOCs) and released particles in the salons. For this reason, this study was conducted to investigate the occupational exposure of nail salon technicians to VOCs and particulate matters (PMs) in the nail salons in Tehran, Iran. In this cross-sectional study, indoor air quality and measurement continually Total VOCs and PMs in the various size of PM1-PM10 using PhoCheck Tiger and particle counter device investigated, respectively. site observation, and an interview with the manager in 49 salons in Tehran. Data was analyzed using SPSS software (version 22). Mean concentrations of PM1 with 2.56 μɡ/m3 was the lowest amount and PM10 with 346.86μɡ/m3 had the highest concentration. Also, the mean concentration of TVOCs was equal 2.61 ppm. The results of the regression model showed that there is a statistically significant between the number of services with airborne PMs (PM2.5), (p-Value≤0.050). In salons only with nail activities, the concentration of PM4 was less than the others, although this correlation was statistically significant just for PM1 (p-Value = 0.010). By implementing effective local exhaust ventilation systems equipped with dust collectors and utilizing safe products, the emission of particles and chemical compounds within salons can be significantly reduced.