Disposal tube

From Memory Alpha, the free Star Trek reference

The disposal tube is very similar to a trash tube. It is used to send something to a garbage deposit, to a security vault or directly ejected to space.

In 2266, Captain Kirk dropped a overloading phaser into the Enterprise's disposal tube after finding it hidden in the red alert light fixture, after he had declared a double red alert to evacuate that section of the ship after Spock heard the distinctive sound of a phaser on overload hidden inside Kirk's quarters. (TOS: "The Conscience of the King")

Later in 2266, during a confrontation between the Enterprise and a Romulan Bird-of-Prey the ship's commander loaded all of his ship's debris into disposal tubes and jettison the junk into space to fool the Enterprise crew into thinking the Romulan ship was destroyed. (TOS: "Balance of Terror")