Anhydrous Gypsum as Diesel Ash Surrogate and Sensitivity to Ash Particle Size in Accelerated Ash Loading Studies 2021-01-0585

Accelerated ash loading studies provide a cost-effective means of investigating the long-term impacts of ash accumulation in diesel particulate filters (DPFs). Despite a variety of methods adopted in previous studies for accelerated ash loading, evaluation of their impact on DPF behavior has been limited primarily to pressure drop response (with & without soot), and characterization of properties of the resulting ash deposits for comparison with samples from field testing. In the current study, the potential to use ash recovered from field DPFs to perform accelerated ash loading studies is explored. Additionally, anhydrous gypsum as a surrogate for diesel ash was investigated. Benefits of using gypsum include low cost and easy access, safety during handling and testing, and consistency from test to test. Narrow control of particle sizing and composition can help compare performance over a wide range of filter sizes and applications. The ash surrogate was mixed with Printex-U soot to minimize re-agglomeration and introduced into a temperature and flow-controlled exhaust stream upstream of a DPF, using an in-house auger setup. The ability to control ash accumulation pattern in the DPF using parameters such as particle size and gypsum loading rate (g/h) was explored. Additionally, the impact of ash particle size on ash layer and plug characteristics and therefore pressure drop and filtration performance was also studied. The results were compared with field DPFs to evaluate the effectiveness of the accelerated ash protocol to mimic DPF performance on the field.