Analysis of thermal crack formation in water-charged air-cooled heat exchangers for heavy-duty vehicles

The non-uniform flow distribution at the inlet severely affects the thermal cycling loading of the watercharged air-cooled (WCAC) systems resulting in crack formation after periods and hence leakage in the internal coolant. These cracks are serious since having crucial effects on performance and durability. This work developed a custom thermal fatigue test rig and methodology to precisely determine the crack formation's location and cycle time in WCACs. The test rig was designed to reflect the vehicle's situation by simultaneously controlling the air and waterside of the WCAC continuously. The crack formation occurred by performing tests with different critical cycles on the test rig because a specific cycle was observed, and a thermal cycle profile was created. It was seen that the crack formation in the WCAC can be predicted at the same cycle time and exact location with this test rig compared to the vehicle tests. Moreover, the total cost, time, and man-hours per test decreased by 80 %,75 %, and 60, % respectively, compared to traditional vehicle tests. Subsequently, the modified WCAC design was proposed to prevent non-uniform flow distribution at the inlet of the WCAC. The thermal fatigue tests of the modified WCAC design were tested in a developed test rig for stressful operating conditions. The results showed that the modified WCAC design is more robust than the old design. There was no crack formation in the modified WCAC design under various stressful operating conditions.