System performance diagnostic to evaluate potential system failures by evaluating the thermal energy transferred across the chiller heat exchanger

摘要

The invention describes a method of determining if there is adequate heat transfer through a chiller type heat exchanger to diagnosis it the vehicle thermal system is operating as intended. The detection method is to ensure the state of fluid following through the refrigerant and coolant loops are stable or as steady state as possible by assessing changes in speed and/or flowrate (1). The energy though the condenser as well as the chiller should also be as stable as possible by assessing changes in temperature and/or energy thresholds (2). Once the system is in a detectable state the calculated chiller power (Q = mass flow (3) • coolant specific heat * (T1-T2) (4)) on the coolant side is compared to the requested chiller power from the vehicle controls. When the comparison of the powers deviates beyond an acceptable limit, it will be determined that there is insufficient energy being transferred through the chiller. This results in an indication of reduced chiller thermal performance.