Heat exchanger

A heat exchanger comprising:

• a pair of tanks spaced from each other and having a plurality of holes disposed therein, each hole having a hole diameter;
• and
• a plurality of substantially parallel heat transfer tubes each having a wall with a uniform thickness over an entire length thereof, said tubes fluidly connecting said pair of tanks, each heat transfer tube comprising:
• a central portion having a substantially uniform central diameter;
• and
• two end portions each being integral with said central portion and comprising a straight portion and a tapered portion, said straight portion having a base diameter less than the substantially uniform central diameter and slightly less than the hole diameter, said tapered portion comprising a base and a tip and having a tapering diameter which decreases from the base diameter at said base to a tip diameter at said tip, wherein each end portion is inserted into one of said holes and brazed to one of said tanks.

A method of assembling a heat exchanger comprising a pair of tanks spaced from each other and having a plurality of holes disposed therein, said method comprising the steps of:

• providing a plurality of heat transfer tubes, each of said heat transfer tubes comprising a central portion having a central diameter, a first end portion comprising a first straight portion and a first tapered portion, said first straight portion having a first base diameter less than the central diameter, said first tapered portion comprising a first base and a first tip and having a first tapering diameter which decreases from the first base diameter at said first base to a first tip diameter at said first tip, and a second end portion comprising a second straight portion, each of said tubes having a wall with a uniform thickness over an entire length thereof;
• inserting said second end portions of said heat transfer tubes into holes in a first tank of said pair of tanks;
• positioning said straight portions of said second end portions in said holes of said first tank;
• inserting said first end portions of said heat transfer tubes into holes in a second tank of said pair of tanks;
• and
• positioning said straight portions of said first end portions in said holes of said second tank.