Following the announcement of a new service to deliver more accurate on-road vehicle exhaust testing and analysis, David Meek spoke to ATTI about Intertek’s new portable emissions measurement system
David Meek started his career with Ford of Europe and worked at senior engineering levels with Cosworth Technology and Gibbs Technologies before becoming the project manager at engineering consultancy Integral Powertrain, where his expertise in hybrid and EV motors and test systems was developed. Meek has led the development of electric racing and hybrid supercar eMotor programs, including the development of ultra-high speed test rigs for machine validation.
How does the new portable emissions measurement system (PEMS) work?
It’s essentially a miniaturized emissions lab that can be fitted externally onto the tailpipe of (or even inside) any size of road going vehicle. The PEMS equipment measures full exhaust mass flow to calculate the regulated and non-regulated exhaust emissions of the test vehicle much in the same way that the vehicles would be tested in the laboratory environment. Fuel consumption is inferred from the CO? emissions measured by the PEMS.
The one obvious difference between chassis dynamometer testing of the vehicle and the use of PEMS is that this testing is conducted ‘on the road’ and therefore the vagaries of the real-world affect the results far more than the highly controlled environment of the test laboratory. In order to compare the results and make fair comparisons, PEMS introduces a huge amount of mathematical data post-processing to ‘normalize’ the results. This should in theory mean that results from different tests on the same vehicle will be very similar and comparisons between different vehicles are fair.
How much time was spent developing it?
We’ve been working on understanding the new legislation since the end of 2014 and this work has continued to gather momentum as the European legislation that drove the investment in this new testing capability has become more clearly defined.
How vast is the difference between officially published laboratory testing data and real-world figures on fuel consumption and exhaust emissions?
It’s difficult to quantify the differences in emissions and fuel consumption between real-world emissions and laboratory based testing as the drivecycles and driving conditions are totally different. You are not comparing like-for-like!
RDE and PEMS have been introduced to address the discrepancies between lab-based results and real world experience. The legislators are currently focusing on NOx and CO? as a first step, as the former has been shown to have the biggest discrepancy, especially for diesel engines, and the latter is the ongoing focus on greenhouse gasses.
The main reasons for the discrepancies are differences in engine load and speeds. Most customers tend to use higher load (have a heavier right foot) than is necessary to drive a lab-based test cycle. This often leads to higher NOx emissions on a diesel engine and higher CO? emissions on all engines. RDE legislation will result in a much bigger workload for powertrain calibration engineers as they will have to work to minimize NOx and CO? emissions across a much wider range of speeds and loads. This may even demand significant changes to emissions hardware if legislative limits are set at a low level.
What are the unique driver aids and route management tools you are developing?
To aid the understanding of the emissions results that we are gaining from the PEMS equipment, we have worked hard on the post test analysis of the acquired data. We have been able to combine multiple video camera inputs as well as highly accurate GPS that is combined with our PEMS emissions results. This gives us the opportunity to get a good documented visual understanding of the emissions results as well as combining that with the feedback from our test drivers. We are also focusing on an in-vehicle driver display to help the driver avoid potential traffic jams, which would invalidate the test. This will be a bit like sat-nav, but with information relating to PEMS testing instead.
Can you elaborate on details of Intertek’s investment in low carbon vehicle, high performance electric machine and hybrid testing cells?
With the ever increasing pressure on vehicle manufacturers, local authorities and vehicle operators to reduce carbon emissions and to minimize the detrimental effects on air quality from fired engine propelled machinery, we saw the need to invest in not just conventional fired engine test equipment, but to further invest in new test equipment and expertise to test and development non-fired vehicle technology.
The driveline test cells have two 550kW axle speed transient dynos and 1000V / 300kW battery simulators to enable us to test very high specification hybrid drivelines. Combined with the multi-channel electrical power analyzers and numerous other pieces of instrumentation for electrical system data acquisition and analysis we are confident that our new test cells, which are due to open in October 2015, will be among the finest commercially available hybrid driveline test facilities in Europe.
August 7, 2015
