Hazardous particles during diesel engine cold-start and warm-up: Characterisation of particulate mass and number under the impact of biofuel and lubricating oil

The increasing share of using biofuels in vehicles (mandated by current regulations) leads to a reduction in particle size, resulting in increased particle toxicity. However, existing regulations disregarded small particles (sub-23 nm) that are more toxic. This impact is more significant during vehicle cold-start operation, which is an inevitable frequent daily driving norm where after-treatment systems prove ineffective. This study investigates the impact of biofuel and lubricating oil (as a source of nanoparticles) on the concentration, size distribution, median diameter of PN and PM, and their proportion at size ranges within accumulation and nucleation modes during four phases of cold-start and warm-up engine operation (diesel-trucks/busses application). The fuels used were 10% and 15% biofuel and with the addition of 5% lubricating oil to the fuel. Results show that as the engine warms up, PN for all the fuels increases and the size of particles decreases. PN concentration with a fully warmed-up engine was up to 132% higher than the cold-start. Sub-23 nm particles accounted for a significant proportion of PN (9%) but a smaller proportion of PM (0.1%). The fuel blend with 5% lubricating oil showed a significant increase in PN concentration and a decrease in particle size during cold-start.

The emission factor adjustments of the passenger cars in multi-story car parks under drive modes

The drive mode is an important factor that affects the adjustment requirements for emission factors of the conventional simulation methods in multi-story car parks. In order to propose comprehensive emission factor adjustments for passenger cars based on the drive modes, the present study is aimed to investigate the effects of different drive modes on emission factors for multi-story car parks. Thus, to achieve this aim, the tailpipe emissions based on the on-board measurement and international vehicle emission (IVE) model are obtained. The results indicate that the drive modes significantly affect the emissions. Accordingly, the change in drive mode from minimum to maximum leads to an increase in the vehicle-specific power (VSP) by 106%. Furthermore, the results of emission factors show the discrepancy between on-board measurement and IVE model with the maximum and minimum adjustment factors by 3.28 and 1.28 for carbon monoxide (CO) and carbon dioxide (CO₂), respectively.

Analysis of cold-start NO2 and NOx emissions, and the NO2/NOx ratio in a diesel engine powered with different diesel-biodiesel blends

In the transportation sector, the share of biofuels such as biodiesel is increasing and it is known that such fuels significantly affect NOx emissions. In addition to NOx emission from diesel engines, which is a significant challenge to vehicle manufacturers in the most recent emissions regulation (Euro 6.2), this study investigates NO₂ which is a toxic emission that is currently unregulated but is a focus to be regulated in the next regulation (Euro 7). This manuscript studies how the increasing share of biofuels affects the NO₂, NOx, and NO₂/NOx ratio during cold-start (in which the after-treatment systems are not well-effective and mostly happens in urban areas). Using a turbocharged cummins diesel engine (with common-rail system) fueled with diesel and biofuel derived from coconut (10 and 20% blending ratio), this study divides the engine warm-up period into 7 stages and investigates official cold- and hot-operation periods in addition to some intermediate stages that are not defined as cold in the regulation and also cannot be considered as hot-operation. Engine coolant, lubricating oil and exhaust temperatures, injection timing, cylinder pressure, and rate of heat release data were used to explain the observed trends. Results showed that cold-operation NOx, NO₂, and NO₂/NOx ratio were 31-60%, 1.14-2.42 times, and 3-8% higher than the hot-operation, respectively. In most stages, NO₂ and the NO₂/NOx ratio with diesel had the lowest value and they increased with an increase of biofuel in the blend. An injection strategy change significantly shifted the in-cylinder pressure and heat release diagrams, aligned with the sudden NOx drop during the engine warm-up. The adverse effect of cold-operation on NOx emissions increased with increasing biofuel share.

Evaluation of Heating and Irradiation Methods for Production of Purified Protein Derivative (PPD) of Mycobacterium Tuberculosis

Tuberculin skin test, also known as the tuberculin or purified protein derivative (PPD) test, is an extensively applied diagnostic test for the detection of primary infection with Mycobacterium tuberculosis (Mtb). The production of PPD is accompanied by some difficulties that require a series of modifications in the production and purification processes. The present study aimed to determine the facilitation level of the manufacturing process by modifying evaluation methods for the production of PPD tuberculin. Mtb strains were cultured in Lowenstein-Jensen media, and the cultured strains were inoculated into the Dorset-Henley liquid medium by the biphasic medium of potato-Dorset-Henley. After incubation, flasks containing cultured strain were selected for bacterial inactivation, and the optimal gamma radiation dose(s) was determined. Tuberculoproteins were precipitated by ammonium sulfate (AS) and Trichloroacetic acid (TCA). Protein concentration was determined using the Bradford and Kjeldahl protein assay methods. Finally, the lymphocyte transformation test and potency test were performed. Based on the results, the Dorset-Henley liquid medium is suitable for the massive growth of the bacterium. The transferal of Mtb from solid to liquid medium was directly carried out without intermediate culture. It was found that during tuberculoprotein production, heating at 100°C for 3 h would be safe for killing mycobacterium. Furthermore, the simultaneous use of heating and gamma irradiation (8 kGgy) killed all of the mycobacteria, while doses of 1, 1.5, and 7 kGy decreased a significant number of bacterial cells. The results also indicated that the concentration of tuberculoprotein extracted by TCA precipitation method was higher than that obtained by AS precipitation. The tuberculoproteins which were produced by these two methods in the lymphocyte transformation test were not significantly different in terms of potency (P>0.05). Moreover, due to the high volume of produced protein, the protein measurement was more efficiently carried out by the Kjeldahl method, compared to the Bradford method. Finally, the results of the present study demonstrated that in addition to the novel approach of gamma irradiation, optimum methods are efficient and applicable in the production of PPD tuberculin.

Energy and exergy analysis of a novel turbo-compounding system for supercharging and mild hybridization of a gasoline engine

Number of hybrid vehicles has increased around the world significantly. Automotive industry is utilizing the hybridization of the powertrain system to achieve better fuel economic and emissions reduction. One of the options recently considered in research for hybridization and downsizing of vehicles is to employ waste heat recovery systems. In this paper, the addition of a turbo-compound system with an air Brayton cycle (ABC) to a naturally aspirated engine was studied in AVL BOOST software. In addition, a supercharger was modeled to charge extra air into the engine and ABC. The engine was first validated against the experimental data prior to turbo-compounding. The energy and exergy analysis was performed to understand the effects of the proposed design at engine rated speed. Results showed that between 16 and 18% increase in engine mechanical power can be achieved by adding turbo-compressor. Furthermore, the recommended ABC system can recover up to 1.1 kW extra electrical power from the engine exhaust energy. The energy and exergy efficiencies were both improved slightly by turbo-compounding and BSFC reduced by nearly 1% with the proposed system. Furthermore, installing the proposed system resulted in increase in backpressure up to approximately 23.8 kPa.