Heat release analysis for rapid compression machines: Challenges and opportunities

Heat release analysis (HRA) is commonly used in combustion studies to derive understandings of chemical and physical processes in situations where direct measurement is not practical. In internal combustion engines, it is typically based on crank-angle resolved pressure diagnostics. However, it has not been applied extensively to rapid compression machine datasets. There are various challenges associated with rigorous application of HRA, including a reasonable accounting of physical processes that occur during the test period, such as heat loss. Limitations associated with transducer robustness and data acquisition system fidelity also exist. On the other hand, there is potential to extract a wealth of information from pressure-time histories via HRA, such as quantifying the evolution and trends of preliminary exothermicity, e.g., low- and intermediate-temperature heat release, across a range of thermodynamic conditions; detecting the existence of non-uniform ignition phenomena during a test; and providing additional targets for the evaluation and improvement of chemical kinetic models. This work discusses such opportunities, and some approaches towards resolving various challenges.