Patent ID: 7231962

Claim:
A heat exchanger comprising: a plurality of tubes arranged spaced apart from one another at regular intervals in such a fashion that both ends of each tube are fixed to upper and lower headers, respectively, for flowing a heat exchange medium therethrough; an upper tank including a first tank coupled to the upper header and a second tank housed in the first tank, the first tank having inlet and outlet pipes formed at one side thereof, the second tank having an array of distribution holes formed on a top thereof and a collecting hole formed at one side thereof; a first opening and closing means slidably installed inside the upper tank for opening and closing the array of the distribution holes; a control means rotatably installed inside the upper tank for receiving an external power to operate the first opening and closing means; and a lower tank coupled to the lower header, the lower tank being fluid-communicated with a lower end portion of each tube and fluid-communicated with the upper tank through a return pipe.