Car Environment Conditions vs. Thermal Chamber Conditions

In the automotive industry, the design validation tests and product validation tests are performed in thermal chamber conditions. During these tests, only the ECU (Electronic Control Unit) is tested, without considering surrounding parts, solar radiation, and real-life convection conditions. Inside thermal chamber conditions, there is an unknown turbulent airflow behavior, which varies from one type of thermal chamber to another type of thermal chamber. Also, it depends on the relative ECUs position inside the thermal chamber and by how many ECUs are tested at the same time.The thermal chamber conditions are different than extreme real-life conditions. In extreme real car environment conditions, there are surrounding parts, like brackets and protection covers, which reduce the forced convection conditions significantly. There is exterior ambient temperature, solar radiation, wind speed or car speed, and Air Conditioning (AC) velocity and temperature, which influence the thermal behavior considerably. The relative position to gravity and the mounting location in the car influence the same thermal response. In most of the cases, solar radiation is the most important parameter among the external parameters.The current paper analyzes the difference between these conditions and explains why these conditions do not substitute each other. It is essential to analyze both situations and to take the right conclusions for both cases, being aware of the limitations.