A lid includes a first surface defining a cavity, a first joint defining an inlet, a second joint defining an outlet, a center hole communicating with the inlet, a circular channel communicating with the outlet and extending along a periphery of the first surface, and a number of branch channels radially extending from the center hole to the circular channel. The first surface includes a screen plate retained within the cavity, capable of letting the side-effect particles adhere thereon. Each of the plurality of branch channels communicates with the center hole and the circular channel, allowing liquid of a predetermined temperature to circulate within the lid.