I don't have them on my car (CRD) but it looks like part of the air-conditioner. The air con pipes run in that area and one of them has a little extension coming off the side with a plastic cover. That may be used to re-gas the system. Do you have a picture showing more of the engine bay?
Follow the lines and if they go into the front of the car into the air con radiator then they will be part of the system. Are the canisters plastic or metal?