Evaluation and Modification of Constant Volume Sampler Based Procedure for Plug-in Hybrid Electric Vehicle Testing

Zhang, Li; Brown, Tim; Samuelsen, G. S.

doi:10.4271/2011-01-1750

Cited by 4 publications

(6 citation statements)

References 7 publications

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“…However, compared to the magnitude of the CO 2 difference exhibited here, the DF error from the water condensation does not have a significant influence on the CO 2 measurement. 3 Some literature also suggests that the water condensation in the exhaust system and the CVS connecting tube can lead to a non-negligible lower CO 2 value. 13–15 However, the reason of that has not been explained explicitly.…”

Section: Resultsmentioning

confidence: 99%

“…Figure 4 shows that one possible reason for this phenomenon may lie in the volume of the vehicle tailpipe and the CVS sampling line before the RMT. As stated in the previous study, 3 for a vehicle soaked for more than 12 h, the exhaust gas from the previous vehicle operation has time to diffuse out of the exhaust system and the CVS sampling line, allowing both volumes to fill with ambient air. Until the engine starts in UDDS1, the condition is not changed.…”

Section: Test Preparationmentioning

confidence: 91%

“…Figure 1 shows the CVS-based emission sampling system configuration used for this testing, which is the same as the previous testing, 3 as well as a FFM used as a secondary fuel consumption measurement. As a third measurement point, the engine injection pulse was also recorded in order to calculate the fuel flow rate.…”

Section: Test Preparationmentioning

confidence: 99%

“…Figure 2 shows the continuous CO 2 mass measured by the CVS and the FFM in the tests implemented in 2010 on a prototype Prius Plug-in. 3 In the first of the four UDDS cycles, 8 a cold start CD cycle, the engine starts six times, with the first start occurring at the 1040th second. Figure 3 shows the CO 2 mass difference for each intermittent period of engine operation between the FFM and the CVS continuous sampling methods.…”

Section: Test Preparationmentioning

confidence: 99%

“…Plug-in hybrid electric vehicles (PHEVs) present difficulties for the constant volume sampler (CVS) system, which has served as a robust emission sampling system for the automobile for more than 40 years. Recent research 1–4 has been undertaken to address the issues associated with new vehicles due to their extremely low exhaust generation and the intermittent work pattern of the engine in the charge-depleting (CD) cycle. 5 Toyota Technical Center (TTC), Gardena, California; Horiba Automotive Division (HAD), Ann Arbor, Michigan, and the University of California, Irvine (UCI), California, have collaborated to implement emission testing on a TOYOTA prototype Prius Plug-in to improve the emission sampling system.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of the constant volume sampler on plug-in hybrid electric vehicle cold start emission testing

Zhang

Brown

Samuelsen

2013

International Journal of Engine Research

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Previous study shows that the constant volume sampler incorrectly measures some of the exhaust gas when testing a plug-in hybrid electric vehicle in the cold start condition when comparing the CO 2 results from constant volume sampler and fuel flow meter. The main reason is likely associated with the exhaust left in the vehicle tailpipe and constant volume sampler sampling line. Other factors, such as fuel line expansion and water condensation in the exhaust system, are also considered to have contributions. This article evaluates these issues quantitatively by testing a Toyota Prius hybrid electric vehicle on the industry standard constant volume sampler system combined with both a fuel flow meter measurement and an electronic control unit record for fuel consumption. Cold start test cycles and test cycles with a system pre-purge event show that the constant volume sampler has a significant delay in measuring the exhaust, and the estimated exhaust losses for the test car are 15 g CO 2 . Tests with a purge event at the end of the driving cycle show that there are approximately 7 g of CO 2 trapped in the exhaust system and the constant volume sampler sampling line, and the possible reasons for the discrepancy of the above two points (15 and 7 g) are evaluated. The expansion and air bubble influence the fuel flow meter, and the impact of water condensation on CO 2 and CO appears to be negligible.

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