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A new axisymmetric CFD model capable of describing pumping loss is proposed for free piston Stirling engine. Inclusion of clearance seals, bounce space, heater, cooler, and regenerator in a single model is the unique strength of this work. For transient simulation of engine, dynamic mesh was utilized for catering needs of moving boundaries. The model was validated with 12.5 kW component test power converter and successfully predicted indicated power, efficiency, pressure amplitude, pressure drop, and gas temperature in expansion and compression space at different piston amplitudes with 6% maximum deviation. The results showed that the heat exchange at heater and cooler was minimized at each flow reversal and was strongly influenced by oscillating gas-flow rate. The results also present optimum displacer and piston seal clearance at different charge pressure and operating frequencies. The displacer seal clearance could be increased up to 125 pm without compromising power, however, engine output was severely affected with increasing piston seal gap. [ABSTRACT FROM AUTHOR]

The current work applies L9 (33) Orthogonal Array (OA) of Taguchi design to obtain an optimum combination of nature of fuel, speed of engine, and load for DI- CI diesel engine that is alternatively fueled with waste cooking oil (WCO) based pure biodiesel (B100) & 20% blend of biodiesel with neat diesel (B20) with an objective to achieve maximum reduction in smoke and NOx emissions and to enhance the output parameters like engine's heat release, cylinder pressure and brake power with the conceivable dwindling of brake specific fuel consumption of the engine at various load conditions. The optimal input parameters (nature of fuel as B100, speed as 2300 rpm and load as 100%) were specified by the grey relational analysis in such a way that the preferred output results are successfully accomplished. Furthermore, analysis of variance (ANOVA) technique showed that the nature of fuel is the major leading factor with 44.28% impact on the output parameters. The experimental and ANN simulated results at the predicted optimal combination ensured the significant improvements of output response factors, thus validating the use of Grey-Taguchi method in reducing emissions and improving combustion and performance simultaneously. [ABSTRACT FROM AUTHOR]

For compression ignition (CI) engines, two of the fuel injection parameters affecting the engine's performance and emissions formation, are fuel injection timing (FIT) and injector opening pressure (IOP). Other such parameters include the number of injections, rate of injection and injection pattern, etc. In the present study, a multi-cylinder, turbocharged, four-stroke, direct injection (DI) diesel engine was used to investigate the combined influence of FIT and IOP on performance and emissions characteristics. The experimentation was conducted for two IOPs (250 and 300 bar) with four FITs such as 20°, 23°, 26°, and 29° before top dead center (BTDC) at different engine speed and load conditions. To obtain the emissions characteristics, the engine was tested in accordance with the 8-mode steady-state cycle. Moreover, 250 bar and 23° BTDC were the original IOP and FIT, respectively. For all IOP conditions, in comparison to the results with the original FIT, the advancement or retardation in FIT provided the negative results in terms of brake thermal efficiency (BTE) and brake specific fuel consumption (BSFC). Increasing the IOP from 250 to 300 bar, improved the performance parameters for retarded and original FITs (20° and 23° BTDC) and caused the deterioration in performance for advanced FITs. In terms of emissions characteristics, filter smoke number (FSN) and emissions of carbon monoxide (CO) and unburned hydrocarbon (UHC) decreased on advancing the FIT and increasing the IOP. On the other hand, oxides of nitrogen (NOx) and carbon dioxide (CO2) increased on advancing the FIT and increasing the IOP for all experimental conditions. The maximum improvement in the performance of the engine was observed at increased IOP with the original FIT. The original IOP with retarded FIT resulted in the minimum NOx and CO2 with a significant reduction in performance. Furthermore, improvement in performance and reduction in emissions were observed when the engine was operated at higher IOP and retarded FIT. [ABSTRACT FROM AUTHOR]

Abundant availability of low rank coals in some developing countries has a great potential for socio-economic development. Pakistan, as a developing country, has taken a number of initiatives some of which are at an advanced stage. Thus, a critical study of regional and local geology of Salt Range and Trans Indus Range coals located in the Kohat–Potwar geologic province is presented in this paper. Permian coal is the oldest coal, which is located in the Western Salt Range in limited quantity while Palaeocene coal is the younger coal and it is mined from the Hangu and Patala formations. The Palaeocene coal is available in abundance and is mined in the Eastern and Central parts of the Salt Range and Trans Indus Range. Additionally, this study presents the thermo-chemical analyses of the coal samples collected from thirty coal mines of Salt Range and Trans Indus Range. The samples were analyzed for ash composition, ash fusion temperatures (AFT), proximate analysis, ultimate analysis and calorific value from two different Labs, i.e. SGS Pakistan and Changsha University of Science and Technology (CUST), China. The average AFT of the samples analyzed is > 1350 °C, which reveals that the coal is non-slagging. On average the coal has low slagging index, medium fouling index, good combustion characteristic parameters and indices. The coal samples have high ash (14–50%), ultra-high sulfur (3.3–11.1%), low moisture (3–10%), high volatile matter (VM, 24–41%), low carbon (23–57%) with low to medium gross calorific value (GCV, 10.2–25.7 MJ/kg). The data gathered from an extensive campaign is compared with the already published data. The study has provided a knowledge on utilization of coal reserves to meet the projected energy demand in Pakistan as well as in other developing countries. [ABSTRACT FROM AUTHOR]

An integrated performance analysis of a vanadium-based urea-SCR system used for the reduction of exhaust emissions from a diesel engine was carried out. The engine was run on an AC electrical dynamometer in accordance with an 8-mode steady-state cycle. The number-size distribution of particles and carbonyls was analyzed using an electrical low pressure impactor (ELPI) and high performance liquid chromatography (HPLC), respectively. It was found that conversion and/or reduction efficiency (RE) of the SCR were highly affected by the catalyst temperature and space velocity (SV). The NO~ pollutants were greatly reduced with the decrease in SV within the load modes of cyclic speeds. The SCR exhibited an RE of more than 50% for NO~ emissions at 321-435 °C, while the maximum RE was 80.5%. Total hydrocarbon (HC) emissions were also increased with the decrease in load for both cyclic speeds, while the RE varied from 38.7% to 71.1%. Significant increases in upstream and downstream carbon monoxide (GO) emissions were noticed with the decrease in engine load. Reluctance to reduction or a negative RE, ranging from 1.5% to 72%, was observed for CO emissions with the SCR. In addition, nanoparticles were greatly reduced, whereas particles of the size range 57-255 nm showed less reduction. The number-size distribution of particles was shifted from smaller to larger sizes with the SCR retrofit. Furthermore, a substantial conversion of up to 55.3% was obtained in the case of carbonyl emissions. The maximum RE was 58%, 67%, 50%, and 64% for formaldehyde, acetaldehyde, acrolein and acetone, and propionaldehyde, respectively. [ABSTRACT FROM AUTHOR]

• Novel and non-metallic Graphite nano fuel additives are introduced to replace Fe 2 O 3. • Graphite results in higher Cetane index and fuel conversion efficiency than Fe 2 O 3. • Compared to Fe 2 O 3 , G blends result in higher BTE and lower bsfc at 95% confidence. • Graphite nanodiesel produce 17% lower NO x emissions than Fe 2 O 3 blends. Increased menacing engine emissions and threat to human health from metallic combustion catalysts demand a shift towards the application of non-metallic fuel additives. Therefore, the current study is an effort, conducted to introduce a new, less toxic and non-metallic graphite (G) nano diesel-fuel additive, by investigating its effects on the performance and regulated gaseous emissions of a four-cylinder, water-cooled, compression ignition (CI) engine. The experiments were also repeated with Iron oxide (Fe 2 O 3) nanoparticles and statistical analyses were implemented to have a comparison with graphite nanoparticles. The G and Fe 2 O 3 nanoparticles, in concentrations of 50, 100 and 150 mg per litre (mg/l), were mixed with neat diesel by magnetic stirring to prepare homogeneous fuel blends. The physicochemical properties of the fuel blends were determined. A maximum decrease of 4.9% in viscosity and an increase of 3.26% in Cetane index was observed for graphite blends. The investigated parameters include torque (T), brake power (BP), brake specific fuel consumption (bsfc), brake thermal efficiency (BTE), carbon monoxide (CO) and nitrogen oxides (NO x) emissions at engine speed varying from 1500 to 3000 rpm with an interval of 300 rpm at full load. The results revealed that at a confidence level of 95% (significance level α = 0.05), G-blends indicated a higher increase in torque, power, BTE and a greater decrease in bsfc than Fe 2 O 3 blends. Graphite blends produced significantly lower NO x emissions than Fe 2 O 3 treated blends. The increase in T, BP and BTE was 2.4%, 8.9% and 3.9% respectively, with 150 mg/l Fe 2 O 3 blends and 2.9%, 9.6% and 4.1% respectively, with 150 mg/l G-blends. Graphite blends resulted in a 2.6% reduction in bsfc. The increase in NO x emissions was 34.7% with Fe 2 O 3 and 29.2% with G at concentrations of 150 mg/l. The CO increased by 14.2% with G blends. A negative statistical correlation was observed for CO emissions between G and Fe 2 O 3 blends. We conclude that G nanoparticles are more environmentally friendly fuel additives than Fe 2 O 3; however, their application is more recommended for large turbocharged CI engines with improved oxygen density in inlet compressed air. [ABSTRACT FROM AUTHOR]

Mineral oil resources are depleting rapidly, and the slower conventional oil biodegradation process results in environmental pollution. To resolve this issue, cupric oxide (CuO) nanoparticles (1% wt) were introduced into a base oil to improve the lubricating capability of castor oil. In addition, 1% wt. sodium dodecyl sulfate was also blended with the base oil in order to attain the maximum dispersion stability of CuO nanoparticles in the castor oil. Afterward, thermophysical property, atomic absorption spectroscopy, and Fourier transform infrared radiation (FTIR) testing of the lubricant oil sample were performed before and after 100 h of engine operations at 75% throttle and 2200 rpm for each lubricant sample in order to check the capability of the novel oil with mineral oil. Compared with the natural mineral oil, the behavior of the CuO-based lubricant has essentially the same physical features, as measured according to ASTM standard methods. The physicochemical properties like (KV)40 °C, (KV)100 °C, FP, ash, and TBN decrease more in the case of the synthetic oil by 1.15, 1.11, 0.46, 1.1, and 1.2% than in the conventional oil, respectively. FTIR testing shows that the maximum peaks lie in the region of 500 to 1750 cm−1, which shows the presence of C=O, C-N, and C-Br to a maximum extent in the lubricant oil sample. AAS testing shows that the synthetic oil has 21.64, 3.23, 21.44, and 1.23% higher chromium, iron, aluminum, and zinc content. However, the copper and calcium content in the synthetic oil is 14.72 and 17.68%, respectively. It can be concluded that novel bio-lubricants can be utilized as an alternative to those applications that are powered by naturally produced mineral oil after adding suitable additives that further enhance their performance. [ABSTRACT FROM AUTHOR]

In this study, Cu-10 wt.% Al-X wt.% Ag alloys (X = 0.0, 2.0, 2.5, 3.0, 4.0, 5.0, 5.5, 6.0) were synthesized through Powder Metallurgy. The effect of silver addition on microstructural, thermal and mechanical properties of the prepared alloys were investigated by using Scanning Electron Microscopy (SEM), Energy Dispersion Spectroscopy (EDS), X-rays Diffractometry (XRD), Transient Plane Source method (TPS), Rockwell hardness tester and Universal testing Machines. The XRD result of raw materials such as pure copper, pure aluminum, pure silver were qualified through JCPDS cards, and subsequently quantified. The microstructural analysis of all samples was carried out, with heating rate of 5 ̊C/min and annealed at room temperature. The results indicated that presence of silver in Cu-Al alloy offered better hardness up-to 3%Ag and compression strength increases up to 2%Ag in Cu-10 wt. %Al alloys which shows intermetallic structure in XRD analysis. Thermal conductivity and thermal diffusivity of the prepared alloys are investigated with help of TPS method in this work. It is observed that both thermal conductivity and thermal diffusivity increased with the increase of silver contents in the alloys owing to higher conductive behavior of silver. [ABSTRACT FROM AUTHOR]

Maritime transport has been playing a decisive role in global trade. Its contribution to the air pollution of the sea and coastal areas has been widely recognized. The air pollutant emission inventories of several harbors in China have already been established. However, the emission factors of local ships have not been addressed comprehensively, and thus are lacking from the emission inventories. In this study, on-board emission tests of eight diesel-powered offshore fishing ships were conducted near the coastal region of the northern Yellow Bo Sea fishing ground of Dalian, China. Results show that large amounts of fine particles (< 0.5 μm, 90%) were found in maneuvering mode, which were about five times higher than those during cruise mode. Emission rates as well as emission factors based on both distance and fuel were determined during the cruise and maneuvering modes (including departure and arrival). Average emission rates and distance-based emission factors of CO, HC and PM were much higher during the maneuvering mode as compared with the cruise mode. However, the average emission rate of Nitrous Oxide (NO x ) was higher during the cruise mode as compared with the maneuvering modes. On the contrary, the average distance-based emission factors of NO x were lower during the cruise mode relative to the maneuvering mode due to the low sailing speed of the latter. [ABSTRACT FROM AUTHOR]

Abstract: On-road measurement is an effective method to investigate real-world emissions generated from vehicles and estimate the difference between engine certification cycles and real-world operating conditions. This study presents the results of on-road measurements collected from urban buses which propelled by diesel engine in Beijing city. Two widely used Euro III emission level buses and two Euro IV emission level buses were chosen to perform on-road emission measurements using portable emission measurement system (PEMS) for gaseous pollutant and Electric Low Pressure Impactor (ELPI) for particulate matter (PM) number emissions. The results indicate that considerable discrepancies of engine operating conditions between real-world driving cycles and engine certification cycles have been observed. Under real-world operating conditions, carbon monoxide (CO) and hydrocarbon (HC) emissions can easily meet their respective regulations limits, while brake specification nitrogen oxide (bsNOx) emissions present a significant deviation from its corresponding limit. Compared with standard limits, the real-world bsNOx emission of the two Euro III emission level buses approximately increased by 60% and 120% respectively, and bsNOx of two Euro IV buses nearly twice standard limits because Selective Catalytic Reduction (SCR) system not active under low exhaust temperature. Particle mass were estimated via particle size distribution with the assumption that particle density and diameter is liner. The results demonstrate that nanometer size particulate matter make significant contribution to total particle number but play a minor role to total particle mass. It is suggested that specific certified cycle should be developed to regulate bus engines emissions on the test bench or use PEMS to control the bus emissions under real-world operating conditions. [Copyright &y& Elsevier]

Abstract: Carbonyl compound emissions from two passenger cars fueled with different methanol/gasoline blends (M15 and M100) and operated with three-way catalytic converters (TWC) were investigated. The tests were performed on a chassis dynamometer with constant volume sampling over the New European Driving Cycle (NEDC). Carbonyls were trapped on dinitrophenylhydrazine (DNPH) cartridges. The hydrazones formed on the cartridge were analyzed by means of high-performance liquid chromatography (HPLC) and detected with a variable wavelength detector. The results show that when cars were fueled with methanol/gasoline blends, carbon monoxide (CO) and total hydrocarbon (THC) emissions decreased by 9–21% and 1–55% respectively, while nitrogen oxide (NO x ) emissions increased by 175–233%. Compared with gasoline vehicles, formaldehyde emissions with M15 and M100 were two and four times higher respectively, and total carbonyls with M15 and M100 increased by 3% and 104% respectively. With the use of the new TWC, both regulated gas pollutants and formaldehyde decreased. The new TWC caused a decrease of 5% and 31% in formaldehyde concentration for M15 and M100, respectively. Specific reactivity (SR) with the new TWC was reduced from 5.92 to 5.72 for M15 and from 7.00 to 6.93 for M100, indicating that M15 and M100 with the new TWC were friendlier to the environment. [Copyright &y& Elsevier]

Abstract: The characteristics of carbonyl compounds emissions were investigated on a direct injection, turbocharged diesel engine fueled with pure biodiesel derived from soybean oil. The gas-phase carbonyls were collected by 2,4-dinitrophenylhydrazine (DNPH)-coated silica cartridges from diluted exhaust and analyzed by HPLC with UV detector. A commercial standard mixture including 14 carbonyl compounds was used for quantitative analysis. The experimental results indicate that biodiesel-fueled engine almost has triple carbonyls emissions of diesel-fueled engine. The weighted carbonyls emission of 8-mode test cycle of biodiesel is 90.8mg(kWh)−1 and that of diesel is 30.7mg(kWh)−1. The formaldehyde is the most abundant compound of carbonyls for both biodiesel and diesel, taking part for 46.2% and 62.7% respectively. The next most significant compounds are acetaldehyde, acrolein and acetone for both fuels. The engine fueled with biodiesel emits a comparatively high content of propionaldehyde and methacrolein. Biodiesel, as an alternative fuel, has lower specific reactivity (SR) caused by carbonyls compared with diesel. When fueled with biodiesel, carbonyl compounds make more contribution to total hydrocarbon emission. [Copyright &y& Elsevier]