CNG Buses Research Articles

Simultaneous Reduction of CH 4 and NOx of NGOC/LNT Catalysts for CNG buses

Simultaneous Reduction of CH 4 and NOx of NGOC/LNT Catalysts for CNG buses

Characteristics on De-CH 4 /NOx according to Ceramic and Metal Substrates of SCR Catalysts for CNG Buses

Characteristics on De-CH 4 /NOx according to Ceramic and Metal Substrates of SCR Catalysts for CNG Buses

Assessment of GHG mitigation and CDM technology in urban transport sector of Chandigarh, India.

The increase in number of vehicles in metropolitan cities has resulted in increase of greenhouse gas (GHG) emissions in urban environment. In this study, emission load of GHGs (CO, N2O, CO2) from Chandigarh road transport sector has been estimated using Vehicular Air Pollution Inventory (VAPI) model, which uses emission factors prevalent in Indian cities. Contribution of 2-wheelers (2-w), 3-wheelers (3-w), cars, buses, and heavy commercial vehicles (HCVs) to CO, N2O, CO2, and total GHG emissions was calculated. Potential for GHG mitigation through clean development mechanism (CDM) in transport sector of Chandigarh under two scenarios, i.e., business as usual (BAU) and best estimate scenario (BES) using VAPI model, has been explored. A major contribution of GHG load (~50%) in Chandigarh was from four-wheelers until 2011; however, it shows a declining trend after 2011 until 2020. The estimated GHG emission from motor vehicles in Chandigarh has increased more than two times from 1065Gg in 2005 to 2486Gg by 2011 and is expected to increase to 4014Gg by 2020 under BAU scenario. Under BES scenario, 30% of private transport has been transformed to public transport; GHG load was possibly reduced by 520Gg. An increase of 173Gg in GHGs load is projected from additional scenario (ADS) in Chandigarh city if all the diesel buses are transformed to CNG buses by 2020. Current study also offers potential for other cities to plan better GHG reduction strategies in transport sector to reduce their climate change impacts.

Research on Improvement of CH 4 Reduction Performance of NGOC for CNG Bus

Research on Improvement of CH 4 Reduction Performance of NGOC for CNG Bus

Fracture Analysis of CNG High Pressure Container using Fractography and Measurement of Property

Bursting accidents of pressure containers due to design and manufacturing defects are frequently occurring. Due to high-pressure gas or harmful substances, when this vessel is fractured, it can lead to catastrophic disasters. Especially, in the event of bursting accident of composite pressure vessel for CNG bus, many unspecified people can be damaged. Most of the accidents were caused by problems in the manufacturing process. The manufacturing process for TYPE2 pressure vessel is very complicated such as three drawing processes, two ironing processes and one spinning process. In the middle of process, various heat treatments are performed for imparting toughness and removing residual stresses. It should cause a serious problem such as bursting and fragmentation of the pressure container due to defects of this process. In this research, the fracture cause of CNG vessel is evaluated through fractography and measuring material property using IIT and analysis of chemical composition.

CNG 버스의 CH4저감용 NGOC의 de-CH4특성

CNG 버스의 CH₄저감용 NGOC의 de-CH₄특성

Environmental assessment of 9 European public bus transportation systems

The transportation sector is one of the largest sources of EU’s greenhouse gas emissions. In 2011, transportation represented approximately 25 percent of total EU’s greenhouse gas emissions. Urban mobility accounts for 40% of all CO2 emissions of road transport and up to 70% of other pollutants from transport. As, transportation and mobility play a crucial part both in urban economics and the quality of life, it is of great significance to ensure a low carbon transportation sector, so as to deal with the threat that climate change poses to urban areas. This study examines the factors that affect the production of carbon dioxide (CO2) as well as of air pollutants, in 9 major European cities, aiming to provide a comprehensive overview of the actual knowledge on the atmospheric pollution from public transportation systems. CO2 emissions as well as air pollutants, such as CO, HC, PM, NOx are calculated for the diesel and CNG bus fleets of the European cities under study. Finally the environmental benefits, in terms of CO2 and CO, HC, PM, NOx emissions reductions, from the penetration of different biodiesel blends (from B10 to B100) to the bus fleets are estimated.

Characterization of the Ultrafine and Nano Particle Emissions on Modified Indian Driving Cycle for Passenger Cars Operating on CNG Phase Wise Analysis

The ultrafine and nano particles compared to larger particles are gaining high importance because of their vulnerable effects to environment and human health causing respiratory problems, cardiovascular disease, and various types of cancers leading to premature death [1]. WHO report points out that approximately, two thirds of the global burden of disease due to urban outdoor air pollution is mostly from the developing countries in Asia (Cohen et al. 2004)[2]. By number, nearly all of the particles emitted by a diesel engine are nanoparticles which are also true for gasoline engines [3]. This is addressed by new UN Regulations by introducing the emission norms for diesel and GDI vehicles for particle number and PM2.5 as 6 x 10 11 and 4.5 mg/km respectively [4]. However, other S.I. engines like CNG, even though they look clean as there is no visible smoke but emitting large number of particles is necessary to investigate. This research paper focuses on characterization of ultrafine and nano particle emissions from CNG vehicle on Indian driving cycle and it covers experimental Investigation to identify the significance of different operating phases viz. idling, acceleration, deceleration and cruising for their contributions to particle number and size distribution pattern over urban as well as on extra urban part of the cycle. CNG passenger car shows large peak of PN emissions during cold starting phase at the beginning of the test cycle which is almost twice that of diesel vehicle. However, this concentration peak will decrease near to 25% on light operating loads during urban part of the cycle, but during acceleration and cruising operation on extra urban cycle under heavy load the PN emissions from CNG car are higher in magnitude. The particles emitted from CNG buses are too small to contribute to PM10 as they are of ultrafine and nano size range.

The Possibility of Using Knowledge from Unconventional Financing of Suburban Bus Transport as an Innovative Tool for Cost Reduction in Logistics

The paper deals with the possibility of using knowledge from unconventional financing of bus transport as an innovative tool for cost reduction in logistics. The first part provides an overview of financing road transport including public passenger transport in Slovak republic (with dividing on railway transport, bus transport and urban public transport). Other part of paper describes option of using CNG fuel in suburban bus transport in particular company (SAD Zilina). Also this part contains economic comparison between diesel and CNG buses.

Can propulsion and fuel diversity for the bus fleet achieve the win–win strategy of energy conservation and environmental protection?

China is facing serious issues involving energy sufficiency, greenhouse gas (GHG) emissions and air pollution caused partly by the rapid growth of vehicles. In order to relieve those problems, new energy vehicles are introduced into the bus and car market. We adopt life cycle analysis to evaluate the well-to-wheels (WTW) energy consumption, CO2 emissions and pollutant emissions from the traditional diesel bus and new energy buses, including diesel hybrid electric vehicles (HEVs), compressed natural gas vehicles (CNGVs) and battery electric vehicles (BEVs). This study reports the current situation and projects future scenarios for the BEV bus for several regions in China due to significant regional differences in the power generation mix. Compared to the diesel bus, the HEV bus can reduce petroleum, fossil fuel use and CO2 emissions by about 20%, and, at the same time, produce stable reduction benefits for all air pollutants. The CNG bus achieves reductions of WTW primary PM2.5 emissions by 70% over its diesel counterpart and, of course, uses little petroleum; but increases fossil fuel consumption moderately and has no benefit in GHG emissions. The BEV bus can deliver a substantial petroleum consumption advantage and greatly reduce the WTW NOX, VOC and CO emissions; but, if the electricity is generated from burning coal, the BEV bus has no PM2.5 emission benefit compared to the conventional diesel bus. Currently, the BEV bus increases fossil energy use and CO2 emissions in the coal-dominated regions; but, in the future, it can achieve substantially lower fossil energy use and CO2 emissions with more penetration of clean electric energy. To reach the win–win strategy, a city’s initial reliance on diesel buses for the public fleet has to give way to a mixture of these new energy buses; and the fleet mix should be diversified over the region and modified over time to accommodate changes in these energy and environmental parameters.

Particulate Characterization of CNG Fuelled Public Transport Vehicles at Traffic Junctions

ABSTRACTCompressed natural gas (CNG) is considered as cleaner fuel compared to gasoline and has emerged as an important alternate transport fuel in view of its abundant availability globally. CNG has been implemented in mass transport sector globally. This study explores the emission characteristics of two different classes of CNG operated vehicles used for public transportation in Indian Cities. One is a heavy-duty CNG bus and the other one is a light-duty CNG tempo. Both are very popular commuting vehicles in Indian cities. The number of such CNG vehicles is quite large therefore their emissions affect the health of traffic policemen, who are responsible for regulating the traffic during their long duty-hours. They are continuously exposed to harmful regulated and unregulated pollutants from such vehicles. Regulated gaseous emissions and particulate bound polyaromatic hydrocarbons (PAHs) were determined for both vehicles at different engine speeds at no load, which simulates typical traffic junction scenario. For the heavy-duty CNG operated bus, particulate number-size distribution and mass-size distributions were also evaluated. Carbon monoxide (CO), Hydrocarbons (HC) and nitric oxide (NO) emissions were found to be higher for the CNG operated bus compared to the CNG tempo. Particle bound PAHs were quite significant for CNG fuelled vehicles however they reduced at higher engine speeds. Particulate number emissions increased with increasing engine speed, especially in the accumulation mode (50–250 nm) for the heavy-duty CNG bus. Despite moderate increase in particle number emissions, particulate mass contributions of the accumulation mode particles increased significantly with increasing engine speed.

REDUCTION OF CARBON DIOXIDE AND NITROGEN OXIDES EMISSIONS FROM COMBUSTION ENGINES OF VEHICLES BY USING BIOMETHANE

This paper discusses generally the possibility of reduction carbon dioxide and nitrogen oxides emissions from internal combustion engines of vehicles by using biomethane. The road transport in Europe almost fully depends on fossil fuels. Diversification of the road transport fuels will be a key attribute for road transport in the coming years. Purified biogas is one of alternative renewable fuels. Actually, in Poland biogas is used for generating electricity and heat. In some countries (for example in Sweden), upgraded biogas to natural gas quality (biomethane) is used as a vehicle fuel too. In this paper estimated biogas production potential in Baltic See Region countries: Poland and Sweden. It was one of the purposes of European Project Baltic Biogas Bus, and it is taken into account in European Project More Baltic Biogas Bus realized presently. Comparative studies of exhaust emissions of carbon dioxide and nitrogen oxides from city buses powered by diesel and CNG engine were carried out. The study was conducted under real traffic conditions in southern Polish city Rzeszow. Due to the lack in-service city buses with emission level Euro V in Rzeszow, comparative studies of this type of city buses powered by diesel and CNG engine was conducted in SORT I test. Determined mean values of road emissions of carbon dioxide and nitrogen oxides in g/km for the city buses operated in Rzeszow. Estimated value of the total road emissions in the case that would be replaced half the fleet of city buses (40 CNG buses and about 35% of the diesel engine powered buses, meet Euro III emission standard) by the CNG-powered (biomethane) city buses, complying with Euro V (EEV) emission standard.

Environmentally Friendly Public Transport

The article "Environmentally Friendly Public Transport" deals with the impact of public transport on the environment by selected types of vehicles. Nowadays, many public transport operators face the necessity to renew their vehicle fleets and consequently decide how to acquire the best vehicle fleet composition with the lowest costs. They need to be competitive with other operators as well as with personal car transport; they need to provide sufficient comfort to passengers, be environmentally friendly, and last but not least, they need to have low operating costs. The renewal of the vehicle fleet traditionally strains an operator's budget. A good decision for a suitable alternative of operated vehicles, or a decision for a suitable mixture of operated vehicles, may have a crucial impact on operating costs and thus affect financial support from their founders. New alternatives are available thanks to the development of new technologies - traditional diesel buses meeting the emission standards of EURO 6, CNG buses, electric buses, trolleybuses, trams, buses with hydrogen fuel cells, etc. The presented work is trying to find the answer to the question of which alternative is ideal for operators from a short-term, medium-term and long-term perspective. The article presents a comparison of economic indicators of the operation of individual alternatives, their impact on the environment and their performance.

On-road measurement of regulated pollutants from diesel and CNG buses with urea selective catalytic reduction systems

In this study, emissions from 13 buses operated in Beijing, including two Euro-III diesel buses, four Euro-IV diesel buses, three Euro-V diesel buses and four Euro-V CNG buses, were characterized in real world conditions. All of the buses tested were fitted with selective catalytic reduction (SCR) systems except for the Euro-III diesel buses. A SEMTECH-DS was used for testing the gaseous pollutants, and an electric low pressure impactor (ELPI) was used for measuring of particle numbers and size distributions. A comparison was made based on emission performance of these buses by employing the VSP approach and fuel- based emissions factors. Diesel buses emitted less CO and THC but more NOx and PM pollutants than CNG buses. The NOx reduction efficiencies of the SCR systems for CNG buses were higher because of the high exhaust temperature and high NO2/NOx ratio, whereas the efficiencies for diesel buses were lower. This resulted in extremely low NOx emissions from CNG buses, but the high NO2/NOx ratio needs further study. Failures of urea injection in the SCR systems were detected in this research, which resulted in very high NOx emissions. The CNG buses also emitted smaller numbers of particles and less particle mass with the presence of oxidation catalysts. Diesel buses satisfying the Euro-V standard performed better than Euro-IV and Euro-III diesel buses in terms of emission performance, except for more nuclei mode particles. Most of time, the Euro-IV diesel buses show no advantages in CO and NOx emissions compared with the Euro-III diesel buses.

Comparative environmental assessment of Athens urban buses—Diesel, CNG and biofuel powered

Greenhouse gases (GHGs) emitted by road transport vehicles as a direct result of fossil fuel combustion and other environmental pollutants released throughout the life cycle of petroleum based fuels, encourage a shift towards alternative transport fuels. Within this frame, an environmental assessment was performed so as to evaluate the environmental implications of alternative fuels (natural gas and biofuels) penetration in the city buses of the city of Athens. The results are evaluated in terms of CO2, CO, HC, PM and NOx emissions. The findings show that CO2 emissions are significantly reduced in CNG buses compared to diesel powered buses. CO2 emissions can also be reduced by 7.85% in B10 blends and 78.45% in B100 blends, compared to diesel. The environmental assessment can be considered as a basis so as to investigate the viability of replacement of petroleum- based diesel with natural gas and biofuels in city transport buses. Concepts for sustainable bus transportation can be incorporated using the methodology defined in this study, in order to promote a sustainable transportation system and mitigate the climate change.

Air Quality and Climate Impacts of Alternative Bus Technologies in Greater London

The environmental impact of diesel-fueled buses can potentially be reduced by the adoption of alternative propulsion technologies such as lean-burn compressed natural gas (LB-CNG) or hybrid electric buses (HEB), and emissions control strategies such as a continuously regenerating trap (CRT), exhaust gas recirculation (EGR), or selective catalytic reduction with trap (SCRT). This study assessed the environmental costs and benefits of these bus technologies in Greater London relative to the existing fleet and characterized emissions changes due to alternative technologies. We found a >30% increase in CO2 equivalent (CO2e) emissions for CNG buses, a <5% change for exhaust treatment scenarios, and a 13% (90% confidence interval 3.8-20.9%) reduction for HEB relative to baseline CO2e emissions. A multiscale regional chemistry-transport model quantified the impact of alternative bus technologies on air quality, which was then related to premature mortality risk. We found the largest decrease in population exposure (about 83%) to particulate matter (PM2.5) occurred with LB-CNG buses. Monetized environmental and investment costs relative to the baseline gave estimated net present cost of LB-CNG or HEB conversion to be $187 million ($73 million to $301 million) or $36 million ($-25 million to $102 million), respectively, while EGR or SCRT estimated net present costs were $19 million ($7 million to $32 million) or $15 million ($8 million to $23 million), respectively.

충청남도에서 CNG 버스로의 전환을 위한 비용-편익 분석

According to industrialization and urbanization the number of increasing cars is attributable to an explosive increase of the vehicle emissions. In this study, in consideration of the population and local transportation characteristics of South Chungcheong Province the environmental and economic cost-benefit analyses are performed to evaluate whether the CNG bus conversion gives what kind of effects. Based on the analysis result the expansion and distribution plan of CNG bus is proposed for South Chungcheong Province, and the local supply policy model is also proposed considering the acquisition and management of the economic situation of CNG charging infrastructure and the small transportation companies.

냉각팬 전자제어를 통한 시내버스의 연비 개선

Abstract : This paper focuses on cooling fan control by using a magnetic clutch type for the improvement of fuel economy on a heavy city bus. In general, Heavy duty vehicles use viscous clutch type cooling fan which has some disadvantages, such as slow response, wide temperature variation of engine coolant water. But a magnetic clutch type cooling fan can be controlled electronically so the engine coolant temperature can be precisely controllable and this effects could be used to reduce fuel consumption. A control system for applying the magnetic clutch type cooling fan was developed in this study and applied to the real field test and chassis dynamometer test. The result showed well controlled coolant temperature and enhancement of fuel economy. Key words : Vehicle thermal management system(능동형 열관리장치), Electronic clutch cooling fan(전자식 클러치 냉각팬), Viscous clutch cooling fan( 유체 클러치 냉각팬), CNG bus(CNG 버스), Fuel economy(연비) 1. 서 론 1) 2001년 11월 교토의정서 공표 이후 온실가스 배출량 감소를 위한 국제적 노력이 활발하게 진행되고 있으며 이에 따라 선진국들은 2008년부터 2012년까지 전체 온실가스 배출량을 1990년 대비 5.2% 감축하기로 합의하였다.

Size-resolved particle distribution and gaseous concentrations by real-world road tunnel measurement

Measurements of aerosol particle number (PN) size distributions (15–700 nm), CO and NOx were performed in a bus tunnel, Australia. Daily mean particle size distributions (PSDs) of mixed diesel/compressed natural gas (CNG) buses traffic flow were determined in four consecutive measurement days. Emission factors (EFs) of PSD of diesel buses and CNG buses were obtained by multiple linear regression (MLR) methods, particle distributions of diesel buses and CNG buses were observed as single accumulation mode and nuclei-mode separately. PSDs of mixed traffic flow were decomposed by two log-normal fitting curves for each 30-minutes interval mean scans, all the mix fleet PSD emission can be well fitted by the summation of two log-normal distribution curves, and these were composed of nuclei mode curve and accumulation curve, which were affirmed as the CNG buses and diesel buses PN emission curves, respectively. Finally, PSDs of diesel buses and CNG buses were quantified by statistical whisker-box charts. For log-normal PSD of diesel buses, accumulation mode diameters were 74.5−87.5 nm, geometric standard deviations were 1.89−1.98. As to log-normal PSD of CNG buses, nuclei-mode diameters were 21−24 nm, geometric standard deviations were 1.27−1.31.

Shearography를 이용한 Aluminum Liner 내부 결함의 변형량과 변형율 측정 및 FEM 검증

Today, environmental issues have become a matter of worldwide concern. In particular, automobile industries engage in considerable research and investment to develop high-efficiency and ecofriendly cars. Most ecofriendly cars use natural gas or hydrogen gas instead of fossil fuels. In this regard, low-weight and high-pressure vessels have gradually been developed to increase the driving distance of a car. However, most pressure vessels installed in cars develop many defects over time owing to shocks sustained when the car is being driven. Such defects can cause the explosion of the pressure vessel. Therefore it is important to prevent such explosions due to internal defects. The use of shearography for measuring the internal defects of objects afford many advantages. It is a non-contact and non-destructive method, and it is not limited by the object shape. In this study, the internal defect deformation and strain of an aluminum liner that is used in a CNG bus for the fuel storage tank is measured using shearography. It is important to measure the strain and deformation in order to detect defects and repair the pressure vessel. To verify the accuracy of the shearography measurement method, the measurement results of shearography, out-of-plane ESPI, and FEM are compared quantitatively.