Error Analysis of the Normative Calculation Method of the Exhaust Emissions and Fuel Consumption in the Vehicles Fueled with Gaseous Fuels

Paulina Grzelak,Sławomir Taubert

doi:10.3390/en14071916

Paulina Grzelak, Sławomir Taubert

Open Access

https://doi.org/10.3390/en14071916

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Journal: Energies	Publication Date: Mar 30, 2021
Citations: 3	License type: CC BY 4.0

Affiliation: Instytut Transportu Samochodowego

Abstract

The methodologies for calculating exhaust emissions and fuel consumption, which are given in the normative documents, do not take into account the fact that vehicles equipped with liquefied petroleum gas (LPG) or compressed natural gas (CNG) systems are fueled with petrol after a cold start. When calculating exhaust emissions and fuel consumption of LPG or CNG-powered vehicles, it is assumed that they result from the combustion of gaseous fuel only. This simplification leads to an incorrect determination of the emissions and fuel consumption values, as the formulas for calculating these values differ depending on the fuel type. This article presents the results of tests aimed at checking how that factor affects the value of emissions and fuel consumption calculated in the driving cycles used in the type-approval tests. In order to estimate the error resulting from this simplification, the tests of exhaust emissions and fuel consumption of a vehicle equipped with an LPG system were carried out. The tests were carried out on a chassis dynamometer in the worldwide harmonized light vehicles test cycle (WLTC) used in the type approval tests. In the tested vehicle, the CO, total hydrocarbons (THC), NOx and CO2 emissions calculated with the normative method were approx. 7% lower than the values calculated with the corrected method. For this reason, there is a need to develop a measurement method that allows for a separate analysis of the phase in which the vehicle is fueled with gasoline. This will allow the elimination of errors in the current normative method of calculating pollutant emissions from the exhaust system and fuel consumption of vehicles fueled with gaseous fuels.

Highlights

When calculating the pollutant emissions from the exhaust systems of bi-fuel cars, i.e., cars fueled with gasoline and gaseous fuel (liquefied petroleum gas (LPG) or compressed natural gas (CNG)), it is assumed in the normative documents [1,2,3], that the emission of pollutants and fuel consumption result only from the combustion of gaseous fuel
The fact that after the cold start-up the engine is initially fueled with gasoline is not taken into account, and for this phase the formulas suitable for gaseous fuels are used instead of those suitable for gasoline
The Low phase carbon dioxide emissions of the worldwide harmonized light vehicles test cycle (WLTC) cycle calculated according to the corrected method were 6.7% higher on average than the value calculated according to the normative method

Summary

Introduction

When calculating the pollutant emissions from the exhaust systems of bi-fuel cars, i.e., cars fueled with gasoline and gaseous fuel (liquefied petroleum gas (LPG) or compressed natural gas (CNG)), it is assumed in the normative documents [1,2,3], that the emission of pollutants and fuel consumption result only from the combustion of gaseous fuel. The fact that after the cold start-up the engine is initially fueled with gasoline is not taken into account, and for this phase the formulas suitable for gaseous fuels are used instead of those suitable for gasoline. In the methodology of calculating exhaust emissions and fuel consumption, there are formulas in which the values of some variables depend on the fuel composition In the case of vehicles with spark ignition engines with indirect gasoline injection, it is 90 s for the Euro 5 emission level or lower and 60 s for Euro 6 level.

Methods

Results

Discussion

Conclusion