finding co concentration(ppm) in car park ventilation system?

[revanth krishna]

hi to all,

am using (enjoying..) FDS from last 2months.i had experienced with Fire simulation to car park ventilation system.
But know i want do it for to know CO(Carbon monoxide) concentration in Car park Area.
input i know is

Total CO emittance by vehicles in the parking area (in mg/sec)

with this input can i find CO concentration in parking area (in ppm)  or i need something more to do this simulation?

i read the users guide but i didn't get it clearly am trying this from last 1 week but not able to succeed.....

can anyone experience with this type of simulation let me know..

looking forward for your help.....

thanku in advance 

[Kevin]

Determine the appropriate CO_YIELD for your case and add it to the
REAC line. Use QUANTITY='VOLUME FRACTION', SPEC_ID='carbon monoxide'
to get the concentration in mol/mol.

On Apr 13, 2:12 am, revanth krishna <revanth....@gmail.com> wrote:
> hi to all,
>
> am using (enjoying..) FDS from last 2months.i had experienced with Fire
> simulation to car park ventilation system.
> But know i want do it for to know CO(Carbon monoxide) concentration in Car
> park Area.
> input i know is
>

> *Total CO emittance by vehicles in the parking area (in mg/sec)
>
> *with this input can i find CO concentration in parking area (in ppm)  or i

[revanth krishna]

thanqu sir for replay

without using REAC, is their any way i mean to say....

i want to fill the parking area with air+co instead of air
 thanqu in advance

[Kevin]

I do not understand what you are trying to say. Read the User's Guide,
and ask specific questions about specific features.

> > > thanku in advance- Hide quoted text -
>
> - Show quoted text -

[revanth krishna]

ok sir i will check it out from user guide

[Alexej Goehring]

I guess this is the FDS forum and FDS is a transient solver... In my oppinion your problem seems to be better modelled as a steady-state simulation. It would save you the averaging etc.and would be significantly faster to simulate. However, if you wanted to model this case transiently, then you will have to introduce CO from the cars and wait until you have reached steady-state.

[daserra]

I do not understand the problem completely but I think FDS can be used
to model the CO concentration. Each running motor is a small HRRPUA
generating some CO. If you simulate the ventilation you will obtain
the transient or steady state CO concentration in the car park

On 13 Apr., 17:47, Alexej Goehring <alexej.goehr...@googlemail.com>
wrote:

> I guess this is the FDS forum and FDS is a transient solver... In my
> oppinion your problem seems to be better modelled as a steady-state
> simulation. It would save you the averaging etc.and would be significantly
> faster to simulate. However, if you wanted to model this case transiently,
> then you will have to introduce CO from the cars and wait until you have
> reached steady-state.
>

[revanth krishna]

hi Alexej and all,

thank u for your suggestions ...i had done better in steady state simulation(other CFD tools), just like that i want to do in FDS (transient)....

am trying in the same manner as u said introducing CO from the cars..let me know if their is any  trouble, i will be back with my quires

thanku to all for your valuable suggestions and support....

[Chris]

The CO-production rate of a car can be calculated without CFD-
programmes as well. It is easy to calculate it for a Car-Parking
without using any CFD-modelling.

Chris

[daserra]

I find this car park problem quite interesting: I would like to ask
for details of the original problem: If you have turbulent flow there
is no steady state. For most physical problems it is much easier to
calculate a transient which converges into a steady state than trying
to solve the steady state. This brings me back to my questions: What
is the geomety of the car park and which atmospheric flow is there?

[Alexej Goehring]

This is starting to turn into a methodology for car park modeling... My view on this is that car parks and the associated CO concentrations can be modeled in steady-state. What you are generally interested in is to find area where the CO ppm is greater than your threshold (can vary between 80-250ppm, depending on the time of exposure).
The time of exposure and your air change rates are the critical factors determining whether steady-state cfd is appropriate (if your exposure time is 15 mins and it would take longer to reach steady-state, then a transient simulation is less conservative and might be more appropriate).
What you mention below is the turbulence issue, but even if RANS models don't predict wakes and turbulent plumes well, you don't really care about this in car parks. Most of it is momentum driven and you're interested in the concentration in the various areas of your car park (this is why I think CFD is kinda needed and a hand calc is an over-simplification).

Those are my 2cents

[revanth krishna]

hi  to all,

first of all i want to introduce myself to u all am an Masters Student (M.Tech in CFD) doing Project for the fulfillment of Master degrees as part of my project i have chosen FDS for fire Simulation in car parking Area(or tunnels), as it was completed successfully know am trying to do for CO concentration(ppm) in carpark area...

coming  to the geometry of the problem  it is an 38.0 in length,26 in width, 2.8 in height

they are total of 16 cars in the parking area....

as per standards each car can emit CO on an average 42.6 mg/sec 

natural supply of air to domain and exhaust fan having 5m/sec capacity.

can anyone experienced with this type of car parking model? let me know how to solve this...

as i know it can be done in steady state condition but am interested to simulate in transient condition because in this case fresh air supply is natural air so it is to be transient in nature.

as am not having that much experience in this field i dont understand certain things in this discussion

1)how can we predict that the simulation reached to steady state(is it purely based on Time or CO(ppm) distribution in the parking area)
2) how to setup FDS case for this model .

my idea is to dont use combustion process in the FDS, as i know the CO emittance rate i want it to distribute in the domain .....like 
MASS_FLUX(1) and specifying &SPEC ID as carbonmonoxide.

thanku in advance.....

[Chris]

We calculate it like this:

CO-emission from a car: 4.37 mg/m CO. m is the distance the car is
driving inside the parking + if the car is parked there is a
additional emission of the starting process of the engine: Eks=Em(1-e^
(-2x)). x is again the distance from the start to the leaving point in
the parking. Em is 22g CO (at 15°C), 53 g CO (at 0°C) or 76 g CO
(at-15°C). (If the car is just parked for less than an hour we take
this not into account.)

I wonder how all this can be put together into a CFD-simulation as
well as the objects are driving!
All the best.

Chris