Undergrad Help me understand heating/cooling principles

[lavalin]

Hello

I have a closet with two double doors. There’s a 3mm gap between the doors and a 10mm gap down the bottom. I have a few fans mounted above the doors in the wall.

Ambient air is always 2-3deg cooler than inside the closet due to some electrical equipment I have running in there.

I have 2 shelves in the closet. On each shelf there’s a temperature sensor which are closely calibrated. Between the shelves and the doors is a 150mm gap.

When I orientate the fans to blow ambient air in, the lower shelves are about 2 degrees hotter than the upper shelves. When I orientate the fans to extra air out of the closet, the top shelf is about 2 degrees hotter than the bottom shelves.

Just curious to understand the science behind why this is happening.

Also if I pull air into the cabinet which is 2deg cooler than inside the cabinet, what happens to the warm air inside the cabinet? Does it simply mix and just cool down over time? Or is there another explanation

 

[A.T.]

I have a few fans mounted above the doors in the wall.

... inside the closet due to some electrical equipment I have running in there.

When I orientate the fans to blow ambient air in, the lower shelves are about 2 degrees hotter than the upper shelves. When I orientate the fans to extra air out of the closet, the top shelf is about 2 degrees hotter than the bottom shelves.

Just curious to understand the science behind why this is happening.

When the fans blow air in at the top, the outflow of the heated up air is at the bottom.
When the fans blow air out at the top, the outflow of the heated up air is at the top.