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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]

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]

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]

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]