Modeling Airborne Virus Concentrations in Filtered Swine Barns with Negative-Pressure Ventilating Systems

2018 ◽  
Vol 61 (3) ◽  
pp. 1089-1099
Author(s):  
Kevin A. Janni ◽  
Montserrat Torremorell ◽  
Larry D. Jacobson ◽  
Carmen Alonso ◽  
Brian P. Hetchler
Keyword(s):  
Particulate Matter ◽  
Pressure Drop ◽  
Virus Particle ◽  
Negative Pressure ◽  
Reduction Factor ◽  
Respiratory Syndrome Virus ◽  
Fan Performance ◽  
Infiltration Rates ◽  
System Pressure ◽  
Filter Area

Abstract. Porcine reproductive and respiratory syndrome virus (PRRSV) is an economically significant pathogen in the swine industry that can spread through the air. Many swine gestation and farrowing barns with negative-pressure ventilating systems filter the inlet air to manage airborne PRRSV transmission using MERV 8 pre-filters in series with either MERV 14 or MERV 16 filters. Recent research reported air infiltration rates for a new 3,000-sow gestation/farrowing swine barn at several static pressure levels. The barn infiltration data and supplier-provided airflow versus pressure drop data for the filters, a fan, and an evaporative cooling pad were used to model steady-state virus particle concentrations inside a well-mixed barn. Other model inputs included the inside temperature, design ventilating rate, a fan performance factor, filter area, a filter airflow reduction factor due to particulate matter accumulation, and ambient virus particle concentration distributions. For the conditions used, model results indicated that higher barn virus concentrations were obtained with lower mechanical ventilating rates and higher barn infiltration rates. Improved fan performance reduced the number of fans needed but had little impact on barn virus concentrations. Increasing the filter area reduced the pressure drop that the fans had to overcome at higher ventilating rates and correspondingly reduced the unfiltered infiltration rates and barn virus concentrations. Reduced airflow due to particulate matter accumulation on the filters increased the system pressure drop, increased the number of fans running, and increased the barn virus concentrations. Model results indicated that filter combinations that reduced overall virus penetration reduced barn virus concentrations by 57% to 80% for the conditions modeled. More work is needed to assess the model results and the importance of the adjusted factors for other barn and equipment conditions. Keywords: Biosecurity, Filtered barn, Infiltration, Model, Swine, Ventilation, Virus.

Analysis of the precipitation reactor-separation equipment system. Continuous reactor and the rotary vacuum filter operating at the selected negative pressure drop

1981 ◽  
Vol 46 (10) ◽  
pp. 2364-2370 ◽  
Author(s):  
Otakar Söhnel
Keyword(s):  
Pressure Drop ◽  
Negative Pressure ◽  
Continuous Reactor ◽  
Vacuum Filter ◽  
Continuous Precipitation ◽  
Derived Relations ◽  
Filtration Area ◽  
Separation Equipment ◽  
Unit Output ◽  
Rotary Vacuum

An analysis has been performed of the continuous precipitation reactor - rotary vacuum filter system (operating at the selected negative pressure drop) on the basis of the unit output. Filtration area necessary for separation of the product from the precipitation reactor is a function of the mean residence time of suspension in the reactor, concentration of the precipitating solutions, porosity of the filtration cake and the filtration negative pressure drop. Application of the derived relations is demonstrated on the continuous precipitation of Mg(OH)2.

Application of neural networks in predictions of brake wear particulate matter emission

2021 ◽  
pp. 095440702110363
Author(s):  
Saša Vasiljević ◽  
Jasna Glišović ◽  
Nadica Stojanović ◽  
Ivan Grujić
Keyword(s):  
Neural Network ◽  
Neural Networks ◽  
Particulate Matter ◽  
Traffic Control ◽  
World Health ◽  
Vehicle Speed ◽  
System Pressure ◽  
The Neural Network ◽  
Vehicle Systems ◽  
Brake Wear

According to the World Health Organization, air pollution with PM10 and PM2.5 (PM-particulate matter) is a significant problem that can have serious consequences for human health. Vehicles, as one of the main sources of PM10 and PM2.5 emissions, pollute the air and the environment both by creating particles by burning fuel in the engine, and by wearing of various elements in some vehicle systems. In this paper, the authors conducted the prediction of the formation of PM10 and PM2.5 particles generated by the wear of the braking system using a neural network (Artificial Neural Networks (ANN)). In this case, the neural network model was created based on the generated particles that were measured experimentally, while the validity of the created neural network was checked by means of a comparative analysis of the experimentally measured amount of particles and the prediction results. The experimental results were obtained by testing on an inertial braking dynamometer, where braking was performed in several modes, that is under different braking parameters (simulated vehicle speed, brake system pressure, temperature, braking time, braking torque). During braking, the concentration of PM10 and PM2.5 particles was measured simultaneously. The total of 196 measurements were performed and these data were used for training, validation, and verification of the neural network. When it comes to simulation, a comparison of two types of neural networks was performed with one output and with two outputs. For each type, network training was conducted using three different algorithms of backpropagation methods. For each neural network, a comparison of the obtained experimental and simulation results was performed. More accurate prediction results were obtained by the single-output neural network for both particulate sizes, while the smallest error was found in the case of a trained neural network using the Levenberg-Marquardt backward propagation algorithm. The aim of creating such a prediction model is to prove that by using neural networks it is possible to predict the emission of particles generated by brake wear, which can be further used for modern traffic systems such as traffic control. In addition, this wear algorithm could be applied on other vehicle systems, such as a clutch or tires.

LES and RANS Assessment of Rib Cooled Channel Related to SGT-800 Combustor Liner

2011 ◽  
Author(s):  
Daniel Lo¨rstad
Keyword(s):  
Pressure Drop ◽  
Cooling System ◽  
Large Temperature ◽  
Internal Cooling ◽  
Low Frequencies ◽  
System Pressure ◽  
Model Size ◽  
Periodic Boundaries ◽  
Combustor Liner ◽  
Simulation Time

The main parts of the annular combustor liner walls of the Siemens gas turbine SGT-800 are convectively cooled using rib turbulated cooling. Due to the serial system of cooling and combustion air there is a potential of further reduction of total combustor pressure drop by improvements of the cooling system. Apart from the rib cooling, also the cooling channel bypass entrance is related to a significant part of the total cooling system pressure drop. In this study, an investigation is performed for a rib cooled channel which is related to the considered combustor liner and where empirical correlations are available in order to evaluate the methodology used. The study includes an assessment of the Reynolds Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) models available within commercial Computational Fluid Dynamics (CFD) codes and includes also an investigation of model size when using periodic boundaries for LES simulations. It is well known that a small geometrical distance in the direction of the periodic boundaries may have a strong effect on the flow field but is often neglected in practice in order to speed up LES calculations. Here the effect is assessed in order to show what size is required for accurate results, both for time averaged and transient results. In addition too small domains may be affected by spurious low frequencies originating from the periodic boundaries requiring additional simulation time for time converged statistics, but also the averages may be significantly affected. In addition the simulation period for time converged statistics is evaluated in order to show that larger model size in the periodic direction does not necessarily require longer practical simulation time, due to the fact that larger volumes may be used for the combined time and space averaging. The aim is to obtain practical guidelines for LES calculations for internal cooling flows. Then the study is extended step by step to investigate the importance due to high Reynolds number, variable fluid properties and large temperature gradients in order to cover the ranges and specifics required for SGT-800 engine conditions.

Design Considerations for Flow Noise in Automotive Air Handling Systems

1999 ◽  
Author(s):  
David W. Warner ◽  
Niranjan G. Humbad ◽  
Basem Alzahabi ◽  
Robert A. Porada
Keyword(s):  
Pressure Drop ◽  
Predictive Model ◽  
Design Process ◽  
Heat Exchangers ◽  
Test Results ◽  
Noise Levels ◽  
Flow Noise ◽  
Design Considerations ◽  
System Pressure ◽  
Noise Data

Abstract Noise from automotive air handling systems is an important issue for driver and passenger comfort. This study was undertaken to quantify the flow noise from the blower and remaining system, and to develop an analytical predictive model for airflow noise. Tests were conducted on four different vehicle Air Handling Systems (AHS) comprised of blower, heat exchangers, ducts and panel registers. Flow and noise data were measured. Test results suggest that overall noise is dominated by blower noise. A predictive model for airflow noise was developed. This model suggests system pressure drop (Δp) and system airflow (q) being dominant parameters in the noise predictions. The noise variation scales as flow velocity to the power 5.75. The developed model for flow noise can be very useful in the design process to estimate noise levels for new systems from CFD/CAE analyses.

Performance of Plate Heat Exchangers Used as Refrigerant Liquid-Overfeed Evaporators

2010 ◽  
Author(s):  
Jianchang Huang ◽  
Thomas J. Sheer ◽  
Michael Bailey-McEwan
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Pressure Drop ◽  
Mass Flux ◽  
Heat Exchangers ◽  
Strong Dependence ◽  
Nucleate Boiling ◽  
Small Range ◽  
Plate Heat ◽  
System Pressure

The heat transfer and pressure drop characteristics of plate heat exchangers were measured, when used as refrigerant liquid over-feed evaporators. The three units all had 24 plates but with different chevron-angle combinations of 28°/28°, 28°/60°, and 60°/60°. R134a flowing upwards was used as the refrigerant, in a counter-current arrangement with water flowing on the other side. Heat transfer and pressure drop measurements were made over a range of mass flux, heat flux and corresponding outlet vapour fractions. The effect of system pressure on the evaporator performance was not evaluated due to the small range of evaporating temperature. Experimental data were reduced to obtain the refrigerant-side heat transfer coefficient and frictional pressure drop. The results for heat transfer showed a strong dependence on heat flux and weak dependence on mass flux and vapour fraction. Furthermore, the chevron angle had a small influence on heat transfer but a large influence on frictional pressure drops. Along with observations that were obtained previously on large ammonia and R12 plate evaporators, it is concluded that the dominating heat transfer mechanism in this type of evaporator is nucleate-boiling rather than forced convection. For the two-phase friction factor, various established methods were evaluated; the homogeneous treatment gives good agreement.

A lottery draw machine-inspired movable air filter with high removal efficiency and low pressure drop at a high flow rate

2019 ◽  
Vol 7 (11) ◽  
pp. 6001-6011 ◽  
Author(s):  
Nara Han ◽  
Yo Seph Lee ◽  
Byung Kwon Kaang ◽  
Wooree Jang ◽  
Hye Young Koo ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Pressure Drop ◽  
Electric Field ◽  
Removal Efficiency ◽  
Flow Rate ◽  
Low Pressure ◽  
High Flow ◽  
High Electric Field ◽  
High Flow Rate ◽  
Air Filter

A lottery draw machine-inspired novel movable air filter (MAF) system is presented in which MAFs are vigorously moved or rotated to form a high electric field and capture particulate matter (PM) particles.

Experimental Analysis of Sudden Pressure Increase Phenomenon by Real-Time Internal Observation of Diesel Particulate Filter

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
Rui Fukui ◽  
Yuki Okamoto ◽  
Masayuki Nakao
Keyword(s):  
Particulate Matter ◽  
Pressure Drop ◽  
Diesel Particulate Filter ◽  
Operating Conditions ◽  
Particulate Filter ◽  
Exhaust Gas ◽  
Visualization Method ◽  
Diesel Particulate ◽  
Wide Perspective ◽  
Deposit Layer

As a way of reducing the amount of particulate matter (PM) contained in the exhaust gas, diesel particulate filter (DPF) is widely used. To keep the condition of DPF normal and effective, estimation of the amount of PM deposits in the DPF is important. The estimation is mainly conducted based on the value of pressure drop across the DPF. Occasionally, the value of the pressure drop rises suddenly and it leads to overestimation of the amount of PM deposits. In order to elucidate the cause of the sudden pressure drop increase phenomenon, this paper first reveals the engine operating conditions which invoke this phenomenon. The authors also have developed a visualization method to realize the wide-perspective internal observation of the DPF. The observation experiment has been conducted with a commercial engine and DPF under the revealed conditions. Experimental results make clear that the phenomenon is caused by PM deposit layer collapse and channel plugging.

Impingement Cooling of Electronics

1992 ◽  
Vol 114 (3) ◽  
pp. 607-613 ◽  
Author(s):  
B. R. Hollworth ◽  
M. Durbin
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Circuit Board ◽  
Test Model ◽  
Transfer Coefficients ◽  
Low Velocity ◽  
Heat Transfer Coefficients ◽  
Air Jets ◽  
System Pressure ◽  
Uniform Array

Experiments were conducted to determine the performance of a system of low-velocity air jets used to cool a simulated electronics package. The test model consisted of a uniform array of rectangular elements mounted to a circuit board. Each element was cooled by a cluster of four jets, and the spent fluid was vented at one end of the channel formed between the circuit board and the plate from which the jets were discharged. Reported are measurements of system pressure drop and convective heat transfer coefficients for elements at various sites within the array. Results indicate that (for the geometry tested) the largest portion of the total pressure drop occurs across the jet orifices. Further, the crossflow of spent air appears to enhance heat transfer for those elements near the exit end of the channel.

Pressure Drop in a Capillary Tube in Boiling Two-Phase Flow

2003 ◽  
Author(s):  
Fumito Kaminaga ◽  
Baduge Sumith ◽  
Kunihito Matsumura
Keyword(s):  
Pressure Drop ◽  
Vapor Phase ◽  
Mass Flux ◽  
Two Phase Flow ◽  
Capillary Tube ◽  
Flow Boiling ◽  
Phase Flow ◽  
Two Phase ◽  
System Pressure ◽  
Phase Pressure

Two-phase pressure drop is experimentally examined in a flow boiling condition in a tube of diameter 1.45 mm using water in ranges of pressure from 10 to 100 kPa, mass flux from 18 to 152 kg/m2s, heat flux from 13 to 646 kW/m2, and exit quality from 0.02 to 0.77. Also, pressure drop in an adiabatic air-water two-phase flow is measured at atmospheric pressure using the same test section and mass flux ranges of liquid and gas as those in the flow boiling. Decreasing system pressure the pressure drop significantly increases at a given mass flux. Influence of vapor phase on the pressure drop is found to be large both in the adiabatic and the diabatic conditions. The frictional pressure drop correlation for the adiabatic two-phase flow is developed and applied to predict pressure drop in the flow boiling. But it cannot give satisfactory predictions. The Chisholm correlation calculating a two-phase pressure drop multiplier is modified to account the influence of vapor phase in a capillary tube and the modified correlation can predict the pressure drop in the flow boiling within an error of 20%.

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