A heat exchanger comprising: a body part made of heat conductive material, the body part comprising a first surface; and a cooling fin system having an inlet end and an outlet end spaced apart from each other in a longitudinal direction, the inlet end of the cooling fin system is adapted to receive a coolant flow in a coolant flow direction parallel to the longitudinal direction, and the cooling fin system is adapted to provide a flow path for the coolant flow through the cooling fin system in the longitudinal direction, the cooling fin system has a plurality of cooling fins (41, 42) spaced apart from each other in a width direction perpendicular to the longitudinal direction, each of the cooling fins (41,42) is made of a heat conductive material, is thermally conductively connected to the first surface of the body part, has a first fin surface and a second fin surface located at opposite sides of the cooling fin, and has at the inlet end of the cooling fin system an inlet edge adapted to first encounter the coolant flow entering the cooling fin system in the coolant flow direction, wherein the coolant flow is adapted to enter the cooling fin system through an inlet surface of the cooling fin system, the inlet surface being defined by the inlet edges of the plurality of cooling fins (41, 42), together with auxiliary lateral curves each extending on a corresponding basic plane defined by the longitudinal direction and the width direction, and connecting the inlet edges of adjacent cooling fins by a straight line segment, wherein the inlet surface of the cooling fin system is a non-planar surface, characterized in that each inlet edge has a centre curve defined by centre curve points each located at equal distance from the first fin surface and the second fin surface, the centre curve of the inlet edge of each of the plurality of cooling fins (41, 42) has a centre curve projection on a first plane parallel to the longitudinal direction, and perpendicular to the width direction, and the plurality of cooling fins (41, 42) comprises a first set of cooling fins having at least one first cooling fin, and a second set of cooling fins having at least one second cooling fin, wherein the centre curve projections of the first cooling fins coincide with each other, the centre curve projections of the second cooling fins coincide with each other, and the centre curve projections of the first cooling fins differ from the centre curve projections of the second cooling fins, and the centre curve projections of the first cooling fins define a first wave, and the centre curve projections of the second cooling fins define a second wave. a body part made of heat conductive material, the body part comprising a first surface; and a cooling fin system having an inlet end and an outlet end spaced apart from each other in a longitudinal direction, the inlet end of the cooling fin system is adapted to receive a coolant flow in a coolant flow direction parallel to the longitudinal direction, and the cooling fin system is adapted to provide a flow path for the coolant flow through the cooling fin system in the longitudinal direction, the cooling fin system has a plurality of cooling fins (41, 42) spaced apart from each other in a width direction perpendicular to the longitudinal direction, each of the cooling fins (41,42) is made of a heat conductive material, is thermally conductively connected to the first surface of the body part, has a first fin surface and a second fin surface located at opposite sides of the cooling fin, and has at the inlet end of the cooling fin system an inlet edge adapted to first encounter the coolant flow entering the cooling fin system in the coolant flow direction, wherein the coolant flow is adapted to enter the cooling fin system through an inlet surface of the cooling fin system, the inlet surface being defined by the inlet edges of the plurality of cooling fins (41, 42), together with auxiliary lateral curves each extending on a corresponding basic plane defined by the longitudinal direction and the width direction, and connecting the inlet edges of adjacent cooling fins by a straight line segment, wherein the inlet surface of the cooling fin system is a non-planar surface, characterized in that each inlet edge has a centre curve defined by centre curve points each located at equal distance from the first fin surface and the second fin surface, the centre curve of the inlet edge of each of the plurality of cooling fins (41, 42) has a centre curve projection on a first plane parallel to the longitudinal direction, and perpendicular to the width direction, and the plurality of cooling fins (41, 42) comprises a first set of cooling fins having at least one first cooling fin, and a second set of cooling fins having at least one second cooling fin, wherein the centre curve projections of the first cooling fins coincide with each other, the centre curve projections of the second cooling fins coincide with each other, and the centre curve projections of the first cooling fins differ from the centre curve projections of the second cooling fins, and the centre curve projections of the first cooling fins define a first wave, and the centre curve projections of the second cooling fins define a second wave.