Visualization of Airflows in Push-Pull Ventilation Systems Applied to Surface Treatment Tanks

Jin

et al. 2020

IJERPH

A parallel-flow exhaust hood is an effective ventilation device to control dust and toxic pollutants and protect the occupational health of workers, whether it is used alone or combined with a uniform air supply hood in a push–pull ventilation system. Some scholars have studied the outside air flow characteristics of the conventional exhaust hood with non-uniform air speed at the hood face, but the law of velocity variation outside the parallel-flow exhaust hood is not clear at present. Therefore, this paper uses the dimensionless method to study the center-line velocity change regime in a parallel-flow square exhaust hood based on simulation and experimental data. The results show that the dimensionless center-line velocity has a good change law with the characteristic length of exhaust hood in a parallel-flow square exhaust hood, which can eliminate the influence of hood face velocity and the hood size on the velocity change regime; and the experimental data is basically consistent with the calculated data, which shows that the regression equation method is reliable.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Center-Line Velocity Change Regime in a Parallel-Flow Square Exhaust Hood

Jin

et al. 2020

IJERPH

“…One method commonly used to evaluate the capture efficiency of the LEV system is the quantitative capture test. Tracer gas release and measurement is a method used to quantitatively estimate the efficiency of industrial exhaust ventilation hoods [Hampl 1984;Hampl et al 1986;Marzal et al 2003b]. This method typically involves using a surrogate for the process-generated contaminant and requires the use of special measurement and dispersion equipment to conduct the test.…”

Section: Evaluating Ventilation Control Systemsmentioning

confidence: 99%

Current strategies for engineering controls in nanomaterial production and downstream handling processes.

Topmiller¹,

Dunn²

2013

Current Strategies for Engineering Controls in Nanomaterial Production and Downstream Handling Processes Hazards involved in manufacturing and processing nanomaterials should be managed as part of a comprehensive occupational safety, health, and environmental management plan. Preliminary hazard assessments (PHAs) are frequently conducted as initial risk assessments to determine whether more sophisticated analytical methods are needed. PHAs are important so that the need for control measures is realized, and the means for risk mitigation can be designed to be part of the operation during the planning stage. Engineering controls protect workers by removing hazardous conditions or placing a barrier between the worker and the hazard, and, with good safe handling techniques, they are likely to be the most effective control strategy for nanomaterials. The identification and adoption of control technologies that have been shown effective in other industries are important first steps in reducing worker exposures to engineered nanoparticles. Properly designing, using, and evaluating the effectiveness of these controls is a key component in a comprehensive health and safety program. Potential exposure control approaches for commonly used processes include commercial technologies, such as a laboratory fume hood, or techniques adopted from the pharmaceutical industry, such as continuous liner product bagging systems. The assessment of control effectiveness is essential for verifying that the exposure goals of the facility have been successfully met. Essential control evaluation tools include time-tested techniques, such as airflow visualization and measurement, as well as quantitative containment test methods, including tracer gas testing. Further methods, such as video exposure monitoring, provide information on critical task-based exposures, which will help to identify high-exposure activities and help provide the basis for interventions. This page left intentionally blank vii Current Strategies for Engineering Controls in Nanomaterial Production and Downstream Handling Processes

Indoor and Built Environment

“…Then, the general interest in the influencing factors of capture efficiency with push-pull ventilation systems [12][13][14][15][16] was gradually aroused with the development of advanced testing instruments and numerical simulation. Afterwards, design guidelines for push-pull ventilation systems [17][18][19] were proposed and further studied in surface treatment tanks.…”

Section: Introductionmentioning

confidence: 99%

Experimental study on one-side confined jets from a parallel-flow outlet in a push–pull ventilation system

Wang

Huang

Zhou

et al. 2013

This study conducted a series of experiments on the airflow characteristics of one-side confined jets from a parallel-flow outlet with a two-tier perforated plate and a honeycomb in a push–pull ventilation system. Maximum velocity, maximum temperature and airflow trajectory were analysed and compared with previous studies about different outlets. The results showed that the dimensionless turbulence coefficient of the parallel-flow outlet was smaller than either the cased axial fan with open grille’s or the swirl diffuser’s turbulence coefficients from isothermal condition. Different development laws for the parallel-flow outlet discharging a hot air jet (Ar0 = 0.024) on the floor were put forward. Furthermore, it was found that the velocity decay rate of the hot air jets with a parallel-flow outlet on the floor was slower than with the circular aperture over a flat surface. When Ar0 ranged from 0.024 to 0.044, a semi-empirical equation was established to describe the trajectory of the hot jets from a parallel-flow outlet in a push–pull ventilation system. In addition, the baffle height of the suction outlet could be determined and corrected appropriately.