'Pollutant Extraction from Parking Garage - Editorial Demo' simulation project by vaibhav_s


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I created a new simulation project called 'Pollutant Extraction from Parking Garage - Editorial Demo':

Pollutant Extraction from Parking Garage - Editorial Demo


More of my public projects can be found here.


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Description


 


 

 
Technological strides in the automotive industry have resulted in motor vehicles to be the major source of air pollution in urban areas. In fact, they account for 70% of oxides of nitrogen (NOx) emissions, 52% of volatile organic compounds (VOC) emissions and 23% of particulate (PM) emissions.
 
Carparks are constructed to provide a certain number of car spaces for visitors, shoppers and/or clients of a commercial facility. The required ventilation system design is generally based on standards provided by local authorities. The ventilation of underground car parks has to fulfill two key requirements:
 

  1. Remove the pollutants emitted by cars.
  2. In the case of a fire, control the hot fumes and gases produced by the fire, protecting the escape routes and easing access for the emergency teams.
     
    Ducted ventilation systems, extract fans and jet fan ventilation systems are mechanical ventilation systems for day-to-day ventilation in underground car parks. Their major role involves the extraction of harmful exhaust gases from an underground car park such as Carbon Monoxide (CO), Nitrogen Oxides (NOx) and Sulphur Oxides (SOx) which cause poor air quality.

CO is one of the most harmful pollutants due to its degree of toxicity and detrimental impact on human health. This gas is colourless and odourless but highly toxic. Therefore, CO poisoning is the most common type of fatal air poisoning. If mechanical or natural ventilation is not sufficient in the enclosed environments, exhaust gas concentrations are hazardous to humans and can even lead to death. Carbon Monoxide (CO) is fractionally lighter than air. It lingers at a cerain level and gradually rises toward the ceiling or roof space of a car park.
 
The exposure limits for CO are:

  1. 30 PPM as a time-weighted average (TWA) over an 8-hour working period known as the Long-Term Exposure Limit (LTEL).
  2. 200 PPM as a TWA over a 15 minute period, known as the Short Term Exposure Limit (STEL).
     
    Maintaining air quality while satisfying safety requirements is a key challenge for car park ventilation.
    Although natural ventilation may be sufficient for open and semi-open parking lots, channelled mechanical or jet fan ventilation systems should be used in underground and closed parking garages.
     

Project Goals


 
The jet fan ventilation system is the most widely used ventilation system for the purpose of carbon monoxide extraction in underground car parks. The aim of this study is to undertake computational fluid dynamic (CFD) modelling of a car park to simulate how jet fans can help in CO concentrations reduction without the need for a complex duct system.
 
This project evaluates ventilation performance in an underground car parking space and verifies whether jet fan ventilation system causes a reduction in CO concentration levels.
 
Therefore, two scenarios are simulated:

  1. Without Jet Fans (Only Supply and Exhaust Fans Opening)
  2. With Jet Fans
     

Geometry


 


 

Meshes


 


 

Simulations


 
CFD simulations are performed to examine velocity and CO concentrations distribution for the two scenarios.
 

  1. The computational domain consists of a parking garage of height 3.5 m having total volume of 23642 m2.
     
  2. Boundary Conditions
  • Fresh Air Inlets [ 4 X 18000 CMH = 72000 CMH]
  • Exhausts Opening [ 3 X 28800 CMH = 86400 CMH]
  • Jet Fans
  • Open Boundary (Ramp for Entry/Exit)
     

     
  1. CO Source Term Calculation
    Total Number of Vehicles Parked - 200
    % of Moving Cars (Entering/Exiting the Garage In Peak Hours - worst case scenario) - 40
    Total moving cars - 80
    CO emission rate per vehicle (mg/s) - 8.1944
    Total Volumetric CO source (Kg/m^3-s) - 2.77E-08
     

Results and Conclusions


 
CO Concentration in PPM at 1.8 m height


Scenario: Without Jet Fans
 

Scenario: With Jet Fans
 
Regions with CO concentration above 60 PPM

Scenario: Without Jet Fans
 

Scenario: With Jet Fans
 
Velocity Contours at Jet Fans Height

Scenario: Without Jet Fans
 

Scenario: With Jet Fans
 
Simulation results indicate that addition of jet fans immensely helps in reduction of CO concentrations. Hence, it can be observed from the simulation results that placement of jet fans at optimum locations helps in significant reduction of CO concentration levels by eliminating dead zones.
 

 

References

[1] https://www.researchgate.net/profile/Charbel_Habchi/publication/281409304_ASHRAE_Leb-Car-Park-FDS-EBD14-Revised/links/55e5dcdc08aecb1a7ccd5e3a/ASHRAE-Leb-Car-Park-FDS-EBD14-Revised.pdf?origin=publication_detail
[2] https://link.springer.com/article/10.1007/s12273-015-0249-0
[3] https://www.sciencedirect.com/science/article/pii/S0379711212000318![chart|690x376]