|
Real-Time Oil Consumption Measurement Using Radioactive Tracer Technology
The oil consumption measurement is based on tritiation of the oil, followed by the measurement of radioactivity levels in continuous samples collected from the exhaust. Tritiation is the process of replacing some of the hydrogen atoms in the oil with radioactive tritium (3H) atoms through catalytic exchange. This is done in a sample of base stock, which is then mixed with the fully formulated oil prior to testing. If all hydrocarbon in the consumed lube oil is burned to completion, all hydrogen -- including the tritium -- will be converted to water. Consequently, activity of the water collected in the exhaust sample will be directly proportional to the mass of oil consumed in the engine during the sampling period. During testing, a continuous exhaust sample is taken at each engine operating condition. The sample is processed to obtain the total amount of water available. The radioactivity of this water is directly related to the mass of lubricant consumed during the sampling period, and is calculated mathematically from the data. Martin B. Treuhaft, Manager Filtration and Fine
Particle Technology |
The
ability of radioactive tracer technology to measure near real-time oil
consumption during engine operation provides a valuable tool for
evaluating overall engine performance with respect to hardware designs,
combustion technologies, engine operating strategies, and lubricant
chemistries. A major benefit of the radioactive tracer oil consumption
method, which measures oil concentration in the exhaust, is that it
provides reliable data for measurements taken over short periods of
time. This reduces cost and shortens development time by allowing many
parameters to be investigated quickly and accurately. This is especially
timely since oil consumption has been identified as a strong contributor
to diesel engine particulate emissions, complicating the NOx-particulate
tradeoff. The tie-in to engine wear is also significant, since
increasing ring and liner wear almost always leads to increasing oil
consumption. 