CFD For kitchen
 

I have a model of kitchen, with a LPG stove in it, With two burners. The kitchen has a window and a door. i want to know the species concentration or emissions of co or co2 in the room with door and window acting as inlets as well as outlets. and how to model the flow coming out of lpg stove.what are the boundary conditions i have to take. How to model it.

The emission of CO2 in your kitchen with that stove shouldn't be too much. If you want to make it less, a single burner stove would do it. If you're not sure which single stove burner to get just click here to learn the best ones available. The lowest price is only $30, but I would never go for the cheapest one.
These things are nice because you can put them where ever you need them. If you are concerned about the CO2 you can put it outside. I do this in summer, but my main concern is the smell. I never even thought about the CO2 emission in my kitchen. A single burner might be your solution...