Juhani Laurikko

Regulated and unregulated exhaust emissions from in-use catalyst cars at normal and low ambient temperatures

This paper presents and discusses test results obtained from a fleet of 44 current-technology passenger cars typical of European vehicles and employs three-way catalyst system with closed-loop air-fuel ratio control. The tested vehicles represented 15 different types and had been in normal use for one to four years and their odometer readings ranged from about 10 000 to over 80 000 km. Tests were performed at normal (+22°C) as well as at low (-7°C) ambient temperatures using the US FTP75 test procedure. Normal CVS-system was used for exhaust sampling and analysis, but a continuous sampling with second-by-second analysis has also been performed in some tests. In addition to the regulated emissions (CO, HC and NOx), some nonregulated compounds have also been measured using the latest high-speed on-line FTIR analysis equipment. Test results and discussion outlines the response of individual vehicles and their emission control equipment to low ambient temperatures. Unit emissions (g/km) are presented for the regulated and cumulative (in g[test] values for some nonregulated compounds (N20 and NH3).

High-Concentration Ethanol Fuels for Cold Driving Conditions

VTT has together with the Finnish energy company St1 tested different high-volume ethanol fuel (E85) samples in order to find the optimum composition for this fuel to perform satisfactorily in low ambient temperature driving conditions encountered in Finland quite frequently during the winter season. Altogether seven different fuel compositions were evaluated, with 70–85 % of anhydrous bioethanol, and various different mixes of regular petrol components and some specific species like ETBE, butane, iso-butanol etc. As a reference, new Euro-quality 95E10 petrol with 10 % ethanol was used. Fuel vapour pressure of each sample was adjusted according to test temperatures to match summer or winter condition and ensure effortless start-up. Test results showed that the composition of the fuel had marked influence on emissions. The lower the test temperature was, the more distinctive were the differences. Based on the results, about −15 °C would be the lower limit of operation with “straight” E85 mixture composed ethanol and petrol. On the other hand the more “engineered” fuels performed much better, and allowed starting as low as at −20 to −25 °C. Cold start and driving was possible at equal level of unburned hydrocarbons and other unwanted emissions (aldehydes, ethanol) at an ambient temperature more than 10 °C lower compared to “straight” E85 fuel.

Improving Energy Efficiency of Heavy-Duty Vehicles: A Systemic Perspective and Some Case Studies

Today’s advanced market economy relies in logistic operations that are both reliable and timely. Road transport is a major contributor to this daily logistics, but also a major consumer of fossil fuels, hence producing a lot of carbon emissions. Furthermore, most of the technologies recently introduced to cut down fuel use and emissions in passenger cars are not practical in heavy trucks running long-distances. This paper focuses on how to more systematically address the energy process and gives some case-examples of progress made in real-world HDVs. Several studies at VTT have been addressing energy use in HDVs. It has become evident that for real improvements in energy efficiency, the complete vehicle must be taken into consideration. We must have better understanding of the factors influencing the energy demand, and not just how to make engines more fuel efficient. For that purpose a break-down of energy use in a heavy truck-trailer combination has been made. The objective for this approach was to give proportions for the various contributors for the energy use, and be able to assess, what kind of progress in each field could be possible. Apart from the holistic and systemic approach, we need metrics to measure the energy consumption in such a way that the results reflect real-world situation as good as possible. Using a chassis dynamometer capable of taking a full-size vehicle and replicating its on-road driving operations has proven to be an excellent tool in terms of precision and repeatability of the results. Adding also road gradient (uphill/downhill) simulation further enhances the realism, and improves the accuracy how closely the duty-cycle is reflected in engine speed/load sequence compared to on-road driving. Eventually, this match is the measure for the success of the method. In case studies several areas of energy use has been addressed, and the potentials for savings in real-use has been determined. These include e.g., choice of tyres for optimum rolling losses without compromising safety and most recently aerodynamic improvements for the complete truck-trailer combination for reduced drag. The paper will portray the achievable energy savings identified in these studies. Test results demonstrate that energy efficiency of heavy trucks can be improved, but for a long-standing and substantial impact the complete design of the vehicle should be viewed from the energy efficiency perspective.

Improvements in Test Protocols for Electric Vehicles to Determine Range and Total Energy Consumption

As electric vehicles have entered the market fairly recently, test procedures have not yet been much adjusted to address their particular features. Mostly EVs are tested the same way as the ICE-driven cars with the exception that determining range is also part of the procedure. However, the current procedures address mainly primary energy consumption, i.e. energy needed to propel the vehicle, whereas the secondary energy, like energy used for cabin heating, cooling and ventilation, is not accounted properly. Main reason is probably the fact that a large proportion of this energy is catered by the waste or excess energy, but in an EV also this part of energy uses is drawn from the battery. Therefore, range of an EV may differ fairly strongly depending on ambient conditions, as in adverse conditions secondary energy use may rise considerably. Furthermore, unlike propulsion energy use that is mainly dependent on driving speed, secondary energy use is mostly dependent on ambient temperature and driving time, and energy is spend even when the vehicle is stopped. However, the challenge to determine a procedure that would more properly address the various parameters that affect range is quite substantial. Also any laboratory test procedure is always a compromise, because it is not possible in practice to replicate the real-life driving completely. Therefore, the authors call upon the engineering community to work on this subject. This chapter outlines our attempt to address this issue, and presents data from in-laboratory testing at normal and low ambient temperatures. It was found that cold driving at −20 °C ambient can shorten the range by about 20 %, even without cabin heating engaged, compared to normal ambient conditions. Using the electric cabin heater will shorten the range further by about 50 % in urban driving and some 20 % in road-type of driving with higher average speeds.