Global warming is directly related to heavy-duty vehicle fuel consumption and greenhouse gas (CO2 mainly) emissions, which, in China, are certified on the vehicle chassis dynamometer. Currently, vast amounts of vehicle real-road data from the portable emission measurement system (PEMS) and remote monitoring are being collected worldwide. In this study, a binning-reconstruction calculation model is proposed, to predict the chassis dynamometer fuel consumption and CO2 emissions with real-road data, regardless of operating conditions. The model is validated against chassis dynamometer and PEMS test results, and remote monitoring data. Furthermore, based on the proposed model, the fuel consumption levels of 1408 heavy-duty vehicles in China are analyzed, to evaluate the challenge to meet the upcoming China fourth stage fuel consumption limits. For accumulated fuel consumption based on the on-board diagnostic (OBD) data stream, a predictive relative error less than 5% is expected for the present model. For bag sampling results, the proposed model’s accuracy is expected to be within 10%. The average relative errors between the average fuel consumption and the China fourth stage limits are about 3%, 8%, and 0.7%, for current trucks, tractors, and dump trucks, respectively. The urban operating condition, with lower vehicle speeds, is the main challenge for fuel consumption optimization.
In order to study the feasibility of the low load cycle (LLC) condition applied to China’s heavy-duty trucks, this paper selects a China Ⅵ heavy-duty trucks with 100% load to study the pollutant emission and driving condition characteristics of LLC, C-WTVC and CHTC-HT on chassis dynamometer. Vehicle specific power (VSP) is adopted as analysis method. The results show that the emission of pollutants (NOX, PN, CO2) under LLC cycle is higher than that under C-WTVC and CHTC-HT. the NOx emission and PN emission of the LLC are about 1 order of magnitude and 3 orders of magnitude higher than those under C-WTVC and CHTC-HT respectively. Compared with C-WTVC and CHTC-HT, CO2 emission of the LLC has the highest total emission performance, while the average emission rate of each VSP interval has the lowest performance, about 3.7g/s.
Hybrid-electric vehicles can achieve low fuel consumption and emission by optimal combination of electrical energy and internal combustion engine power. There are four main test method of energy consumption and emission for heavy-duty HEVs, including traditional engine bench test, powertrain test, HILS and chassis dynamometer test. The tradition engine operating conditions are distinguished from that in HEVs, which can’t reflect the performance of HEVs. Powertrain test can achieve braking energy regeneration, but need bulky installation on testbed. HILS test solves the problem that the engine test cycle is different from the actual operating condition on road and is cost-effective. However, it requires a lot of effort to monitor the HILS simulation input parameters and carry out vehicle validation. Chassis dynamometer test method can better reflect the real-road driving condition. But it is nearly impossible to test all different HEVs types on chassis dynamometer and the test cost is very expensive. By comparing different heavy-duty HEVs energy consumption and emission test methods, the advantages and disadvantages are identified, which provides guidance for the formulation of the next-stage standards of heavy-duty HEV, and promotes the healthy and orderly development of the HEV industry.
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