Utilization of compressed natural gas for the production of carbon nanotubes

The present work aims at utilizing compressed natural gas （CNG） as carbon source for the synthesis of carbon nanotubes （CNTs） over CoO-MoO/Al2O3 catalyst via catalytic chemical vapor deposition （CCVD） method. The as-produced carbonaceous product was characterized by thermal gravimetric analyzer （TGA）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and Raman spectroscopy. The experimental finding shows that CNTs were successfully produced from CNG while carbon nanofibers （CNFs） were formed as the side products. In addition, the catalytic activity and lifetime were found sustained and prolonged, as compared with using high purity methane as carbon source. The present study suggests an alternative route which can effectively produce CNTs and CNFs using low cost CNG.

Performance,combustion,and emission characteristics of on a diesel engine fuelled with hydrogen compressed natural gas and Kusum seed biodiesel

Renewable fuels have many advantages over fossil fuels because they are biodegradable and sustainable,and help mitigate social and environmental problems.The objective of the present study is to evaluate the performance,combustion,and emission characteristics of a compression–ignition engine using hydrogen compressed natural gas(HCNG)-enriched Kusum seed biodiesel blend(KSOBD20).The flow rate of HCNG was set at 5 L/min,10 L/min,and 15 L/min,and the injection pressure was varied in the range of 180 bar to 240 bar.Brake thermal efficiency(BTE)and brake-specific fuel consumption(BSFC)were improved when HCNG was added to the KSOBD20.Combustion characteristics,namely,cylinder pressure(CP)and net heat release rate(NHRR),were also improved.Emissions of carbon monoxide(CO),hydrocarbons(HC),and smoke were also reduced,with the exception of nitrogen oxides(NO_(x)).The higher injection pressure(240 bar)had a positive effect on the operating characteristics.At an injection pressure of 240 bar,for KSOB20+15 L/min HCNG,the highest BTE and the lowest BSFC were found to be 32.09%and 0.227 kg/kWh,respectively.Also,the CP and NHRR were 69.34 bar and 66.04 J/°.CO,HC,and smoke levels were finally reduced to 0.013%,47×10^(-6)and 9%,respectively,with NO_(x)levels at 1623×10^(-6).For optimum results in terms of engine characteristics,the fuel combination KSOBD20+15 L/min HCNG at FIP 240 bar is recommended.

Gaseous emissions from compressed natural gas buses in urban road and highway tests in China

The natural gas vehicle market is rapidly developing throughout the world, and the majority of such vehicles operate on compressed natural gas （CNG）. However, most studies on the emission characteristics of CNG vehicles rely on laboratory chassis dynamometer measurements, which do not accurately represent actual road driving conditions. To further investigate the emission characteristics of CNG vehicles, two CNG city buses and two CNG coaches were tested on public urban roads and highway sections. Our results show that when speeds of 0-10 km/hr were increased to 10-20 km/hr, the CO2, CO, nitrogen oxide （NOx）, and total hydrocarbon （THC） emission factors decreased by （71.6 ± 4.3）%, （65.6 ± 9.5）%, （64.9± 9.2）% and （67.8 ± 0.3）%, respectively. In this study, The Beijing city buses with stricter emission standards （Euro IV） did not have lower emission factors than the Chongqing coaches with Euro II emission standards. Both the higher emission factors at 0-10 km/hr speeds and the higher percentage of driving in the low-speed regime during the entire road cycle may have contributed to the higher CO2 and CO emission factors of these city buses. Additionally, compared with the emission factors produced in the urban road tests, the CO emission factors of the CNG buses in highway tests decreased the most （by 83.2%）, followed by the THC emission factors, which decreased by 67.1%.

Integration Possibility of Urban Public Bus System and Cable Car in Maribor

Combination of a bus system and cable car system can reduce the overall congestion of traffic in urban areas, where surrounding hills or mountains hold larger settlements or tourist and recreational infrastructure. With this kind of integration number of individual car trips can be significantly reduced. In this paper, the authors present an analysis of the pilot project implementation, which was held in Maribor. The authors conducted a limited test trial of two means of transportation, combining them into a single operating transport offer for inhabitants and tourists. Combined transport option proved to be a good starting point for reduction of traffic and parking congestion during winter tourist season and beyond. Method used in the research, in order to gain actual potential of integrating two systems and improving public transport offer, was establishment and implementation of the pilot project in Maribor during January 2011. Data was gathered through interviews of two interest groups. The first covered the users who were brought to the foothills of Pohorje＇s ski center by bus. The second covered the cable car users that were traveling to the top of Pohorje. For a limited time period, a trial principle of a single ticket was established, which gave ski-pass holders free bus ride on bus line No. 6. With the aim of reducing CO2, test drives of hybrid bus and compressed natural gas bus were conducted alongside many promotional activities with which users were informed of importance of environmentally friendly mobility options.

Mixture Preparation and Combustion of CNG Low-Pressure Compound Direct Injection Spark-Ignited Engines

A set of compressed natural gas (CNG) multi-point direct injection system of spark-ignited engines and the corresponding measurement and data acquisition systems were developed in this paper. Based on different injection modes, the mixture formation and combustion of CNG low-pressure direct injection (LPDI) engines were studied under varying factors such as air/ fuel ratio, injection timing. Meanwhile, three-dimensional simulations were adopted to explain the mixture formation mechanisms of CNG low-pressure compound direct injection (LPCDI) mode. On the basis of test results and simulation of the mixture homogeneous degree, the conception of injection window was proposed, and the LPCDI mode was proved to be more beneficial to the mixture concentration stratification formation in cylinder under lean-burning conditions, which resulted in effective combustion and stability.

Polycyclic Aromatic Hydrocarbons in Water: A Review of the Sources, Properties, Exposure Pathways, Bionetwork and Strategies for Remediation

Polycyclic aromatic hydrocarbons (PAHs) are by-products arising from incomplete combustion. These organic chemicals substances are found almost everywhere and pose a risk to human health because of their potentially hazardous nature and bioavailability in the environment as determined by several regulatory agencies such as US Environmental Protection Agency (US-EPA), US Department of Health and Human Services (DHHS), International Agency for Research on Cancer (IARC) and the National Agency for Food and Drug Administration and Control (NAFDAC). The paper is aimed at studying polycyclic aromatic hydrocarbons in water. The possible sources, chemistry, risk and remediation strategies for polycyclic aromatic hydrocarbons in water have been considered. Studies have shown that exposure to PAHs at levels above the maximum contaminant level for relatively short periods will cause damage to the red blood cells leading to anaemia;suppressed immune system. Long-term exposure to Benzo(a)pyrene at levels above the maximum contaminant level has the potential to cause developmental and reproductive defects as well as cancer. US-EPA, IARC and DHHS has sets a maximum contaminant level (MCL) for benzo(a)pyrene, the most carcinogenic PAH, at 0.0002 mg/L, 0.0001 mg/L for benz(a)anthracene, 0.0002 mg/L for benzo(b)fluoranthene, benzo(k)fluoranthene, and chrysene. 0.0003 mg/L and 0.0004 mg/L have been set for dibenz(a,h)anthracene and indeno (1,2,3-c,d)pyrene respectively. Sustained barn on smoking in public places and burning of word, use of concretes in road construction as against the traditional surfacing of roads using coal tar as well as cars running on compressed natural gas (CNG) or liquefied petroleum gas (LPG) can form part of the preventive strategies.

Numerical study of CNG engine combustion using CFD with detailed chemical kinetics

A three dimensional model which considers the effects of turbulence and detailed chemi cal kinetics is built to simulate the combustion process of engine fueled by compressed nature gas （CNG）. The model is accomplished by integrating CFD software KIVA3V and chemical kinetic soft- ware CHEMKINII. Meanwhile, a turbulence combustion model which is suitable for describing the reaction rate under the coupled simulation is developed to balance the effects of turbulence and de tailed chemical kinetics. To reduce the computation time, subsequent development of the simulation code is realized, which enables the simulation code to have the function of parallel computing and run on parallel computing facility based on message passing interface （MPI）. The coupled software is used to simulate the combustion process of spark ignition CNG engine. The results show that sim ulation data have a good consistency with experimental results and parallel computing has good effi ciency and accelerate ratio.

SI Engine Fueled with Gasoline, CNG and CNG-HHO Blend: Comparative Evaluation of Performance, Emission and Lubrication Oil Deterioration

Hydroxy gas (HHO) is one of the potential alternative fuels for spark ignition (SI) engine,notably due to simultaneous increase in engine performance and reduction in exhaust emissions.However,impact of HHO gas on lubrication oil for longer periods of engine operation has not yet been studied.Current study focuses on investigation of the effect of gasoline,CNG and CNG-HHO blend on lubrication oil deterioration along with engine performance and emissions in SI engine.HHO unit produces HHO gas at 4.72 L/min by using 6 g/L of KOH in the aqueous solution.CNG was supplied to the test engine at a pressure of 0.11 MPa using an electronically controlled solenoid valve.Engine tests were carried out at different speeds at 80%open throttle condition and various performance parameters such as brake power (BP),brake specific fuel consumption(BSFC),brake thermal efficiency (BTE),exhaust gas temperature and exhaust emissions (HC,CO_(2),CO and NO_(x))were investigated.In addition,various lubrication oil samples were extracted over 120 h of engine running while topping for drain out volume and samples were analyzed as per ASTM standards.CNG-HHO blend exhibited better performance i.e.,15.4%increase in average BP in comparison to CNG,however,15.1%decrease was observed when compared to gasoline.CNG-HHO outperformed gasoline and CNG in the case of HC,CO_(2),CO and brake specific fuel consumption (31.1%decrease in comparison to gasoline).On the other hand,CNG-HHO produced higher average NO_(x) (12.9%) when compared to CNG only.Furthermore,lubrication oil condition(kinematic viscosity,water contents,flash point and total base number (TBN)),wear debris (Iron (Fe),Aluminum(Al),Copper (Cu),Chromium (Cr)) and additives depletion (Zinc (Zn),Calcium (Ca)) presented a significant degradation in the case of CNG-HHO blend as compared to gasoline and CNG.Lubrication oil analyses illustrated 19.6%,12.8%and 14.2%decrease in average viscosity,flash point and TBN for CNG-HHO blend respectively.However,average water contents,Fe,Al and Cu mass concentration appeared 2.7%,25×10^(-6),19×10^(-6),and 22×10^(-6) in lubrication oil for CNG-HHO respectively.

Catalytic performance of a Pt-Rh/CeO_2-ZrO_2-La_2O_3-Nd_2O_3 three-way compress nature gas catalyst prepared by a modified double-solvent method

A Pt-Rh three-way catalyst（M-DS） supported on CeO_2-ZrO_2-La_2O_3-Nd_2O_3 and its analogous supported catalyst（DS） were developed via a modified double-solvent method and conventional double-solvent method, respectively. The as-prepared catalysts were characterized by N_2 adsorption-desorption, X-ray diffraction（XRD）, CO-chemisorption, X-ray photoelectron spectroscopy（XPS） and hydrogen temperature-programmed reduction（H_2-TPR）. The preformed Pt nanoparticles generated using ethanol as a reducing agent on M-DS presented enhanced Pt dispersion regardless of aging treatment as confirmed by XRD and CO-chemisorption measurements. The textural properties and reduction ability of M-DS were maintained to a large extent after aging treatment. This result was consistent with those of the N_2 adsorption-desorption and H_2-TPR, respectively. Meanwhile, the XPS analysis demonstrated that higher Pt^0 species and larger Ce^（3＋） concentration could be obtained for M-DS. In the conversion of a simulated compressed natural gas（CNG） vehicle exhaust, both fresh and aged M-DS showed a significant enhancement in the activity and N_2-selectivity. Particularly, the complete conversion temperature（T_（90）） of CH_4 over the aged M-DS catalyst was 65 oC lower than that over the aged catalyst by conventional double-solvent method.

Network Modeling and Operation Optimization of Electricity-HCNG-Integrated Energy System

Hydrogen-enriched compressed natural gas(HCNG)has great potential for renewable energy and hydrogen utilization.However,injecting hydrogen into the natural gas network will change original fluid dynamics and complicate compressed gas's physical properties,threatening operational safety of the electricity-HCNG-integrated energy system(E-HCNG-IES).To resolve such problem,this paper investigates effect of HCNG on gas network dynamics and presents an improved HCNG network model,which embodies the influence of blending hydrogen on the pressure drop equation and line pack equation.In addition,an optimal dispatch model for the E-HCNG-IES,considering the“production-storage-blending-transportation-utilization”link of the HCNG supply chain,is also proposed.The dispatch model is converted into a mixed-integer second-order conic programming(MISOCP)problem using the second-order cone(SOC)relaxation and piecewise linearization techniques.An iterative algorithm is proposed based on the convex-concave procedure and bound-tightening method to obtain a tight solution.Finally,the proposed methodology is evaluated through two E-HCNGIES numerical testbeds with different hydrogen volume fractions.Detailed operation analysis reveals that E-HCNG-IES can benefit from economic and environmental improvement with increased hydrogen volume fraction,despite declining energy delivery capacityand line pack flexibility.