Proceed to the main room and go in front of the pipe.
Place a portal on the wall behind the pipe and the other on a wall near you, then pass through it.
Shoot the first portal under the High Energy Pellet Catcher, then go through the portal.
Put the other portal where the Pellet is bouncing, and come back in the test chamber entrance.
Look up to the vertical door. Place a portal on the white portion of the ceiling and the other on the floor.
Before passing through the portal, aim the white ledge above the vertical door. Then, fire your first portal on this place, after going through the portal.
Place the other portal under the vertical door and use momentum to reach the upper level.
Shoot a portal through through the pipes and pass through the other portal.