Heat exchanger

1. A heater core comprising:

first and second header tanks spaced apart from each other;

a plurality of flat heat exchange tubes which are disposed between the first and second header tanks at predetermined intervals along a longitudinal direction of the header tanks with a width direction of the heat exchange tubes intersecting a longitudinal direction of the header tanks so as to coincide with an air flow direction, and opposite end portions of each heat exchange tube being connected to the first and second header tanks respectively; and

a plurality of corrugate fins each being disposed between respective adjacent heat exchange tubes, and each of the plurality of corrugate fins including wave crest portions, wave trough portions, and connection portions connecting together corresponding wave crest portions and wave trough portions, wherein each connection portion having a plurality of louvers which extend in a width direction of the connection portion and are arranged in a longitudinal direction of the connection portion,

wherein the pitch of the louvers formed on each connection portion of each corrugate fin is between 0.4 mm to 0.8 mm,

wherein an inclination angle of the louvers in relation to the connection portion is 20° to 30°,

a thickness of the corrugated fin is 0.02 to 0.1 mm, and

wherein the wave crest and wave trough portions of each corrugate fin each have a semicircular transverse cross section, and the following relation is satisfied:

Hf=D+ 2 R

where Hf represents a fin height of the corrugate fin, which is the direct distance between the wave crest portions and the wave trough portions, D represents the length of the louvers, and R represents the curvature radius of the wave crest and wave trough portions in the transverse cross section.

2. The heater core according to claim 1 , wherein the width of each heat exchange tube is between 24 mm to 30 mm, an inner height of the heat tube is 0.7 to 1.2 mm and the wall thickness of the heat exchange tube is 0.1 to 0.4 mm.