ABSTRACT: New technologies in the fuel injection system have improved the performance of the CI engine. Even though the biodiesel is universally accepted as a suitable alternate fuel for the CI (compression ignition) engine, there have been limited study reported on its utilization for single cylinder CRDI (common rail direct injection) engine. Use of biodiesel with diesel in a CRDI engine reduces proportionate consumption of diesel. In the present study, performance and combustion tests were carried out with the CRDI engine using the B20 blend of mahua methyl ester in diesel on volume basis called (B20 MOME). This study was conducted on a CRDI converted variable compression ratio engine with toroidal shaped cavity in the piston adopted. The tests were carried out at three injection pressures of 400 bar, 600 bar and 800 bar and for three injection timings of 15° BTDC, 20°BTDC and 25°BTDC, respectively. The results of the combustion and performance tests with the CRDI engine were compared with the performance of a CI engine at specified operating conditions with mechanical injection system using diesel as the fuel. The results indicated significant increase in the performance of the engine with increase of injection pressure. At 800 bar injection pressure, brake thermal efficiency of 29.98%, 27.61%, and 26.98% was attained at 15BTDC, 20BTDC and 25BTDC, injection timing respectively using B20 MOME.

ABSTRACT: This study assesses the environmental impact of bauxite mining and the attempts at managing those impacts around the three different bauxite mining communities “zones” (Sangarédi, Boké, Fria) in the western Guinea. Mining sector is important to the country’s economy; it represents 75 to 85% of resources exports by year, especially bauxite and figures prominently in the government's development priorities, evidenced by the broad movement of reforms undertaken by the authorities since 2010. In this context, these reforms aim both to minimize the risks while maximizing the benefits of the mining activity. This implies among other things, a better distribution of income from the mine, strict compliance with environmental standards, to record activity in a sustainable development perspective. To better understand these reforms and scope, this research evaluates the existing framework and innovations of the new reforms in the context of sustainable development. The researcher conducted a data collection, a series of interviews with resource persons (The local communities, the Ministry of Mines, mining companies and NGOs working in the mining sector), to analyze the Environmental and Socio-economic impact of mine. The results showed that the mining code of 1995 was both inadequate and very rarely applied in the field. In contrast, the 2011 code contains advanced Transparency important for equitable sharing of benefits and stringent measures for environmental protection. Thus, this 2011 mining code is more attractive and oriented towards sustainable development.

ABSTRACT: Environmental degradation is an increasing problem in many parts of the world and the type of ecology prevalent in an area is a major factor that determines the extent to which the area should be degraded. This study examined spatial dimension of environmental degradation prevalent in the coastal areas of south west, Nigeria. It also puts into consideration the level of severity of the environmental problems and the various ecological zones in which the surveyed communities in the study area are located. Environmental degradation is the major concept in this study and the DPSIR framework was used in understanding the concept. Mixed-method approaches, involving qualitative and quantitative methodology for data collection were used. The main techniques for primary data collection were questionnaire survey. The questionnaire was administered proportionally to 1,782 respondents who are coastal dwellers that are involved in different economic activities within the coastal areas. Both descriptive (such as frequencies, percentages, charts) and inferential (One-away Analysis of Variance and Person correlation) statistics were used for data analysis as well as cartographic analysis (map). Result shows that there is a significant variation in the spatial dynamics of environmental degradation across the sampled settlements (p<0.05). Flooding was ranked as the most severe environmental problem by larger percentages of respondents in strand ecological zone (67.0%), in deltaic swamp ecological zone (52.0%) and in mangrove ecological zone (54%). The study concludes that flooding, water hyacinth invasion and pollution which include both sewage pollution in water bodies and open refuse dumping in drainages and along road sides was reported are the most common environmental problems reported by most of the communities, whereas flooding is the most severe environmental problem that cut across the study area. Therefore, the study recommends that, rigorous community efforts are needed to provide leadership and modalities for the management of environmental challenges such as flooding in coastal communities.

ABSTRACT: The study of engine performance under different fuel injection timing of a CNG direct injection engine was carried out in a retrofitted car engine. The experiment was performed on a 1297cc, 4-stroke, four cylinder SI engine having compression ratio 9. The base gasoline engine was converted into bi-fuel engine by installing both CNG port injection (CNG-PI) and CNG direct injection (CNG-DI) system in a single gasoline engine. The injection timing was varied from early injection (EI) timing at 220° BTDC to a late injection (LI) timing of 120° BTDC. The experimental study was limited by an engine speed upto 2700 rpm due to high thermal loading at higher speed. The results indicate that, the late injection timing 120° BTDC gives 10-12% higher brake power at a lower engine speed upto 1800 rpm as the volumetric efficiency is better at a lower speed. The optimal injection timing 160° BTDC produces higher performance over the entire speed range from 1200 rpm to 2500 rpm due to sufficient and optimum time available for preparation of CNG-air mixture. The early injection timing 210° BTDC gives very good engine performance for engine speed above 2700 rpm which accelerates better air-fuel mixing at a higher speed.

ABSTRACT: In refrigeration cycles, ejectors are employed as thermo-compressors. To improve their performance, the operational conditions and geometrical parameters could be evaluated. In this numerical study firstly, the effects of refrigerants R1234ze(E) and R1234yf as replacements for R134a are investigated. Results showed that using R1234yf, the entrainment ratio and the coefficient of performance (COP) increase 10% and 1.7% respectively. When R1234ze is used, the entrainment ratio and the COP decrease 3.4% and 7% respectively compared with R134a. For the boiler operating temperature, an optimum value was found at which the entrainment ratio and the COP are maximum. However, the entrainment ratio and the COP enhance by increment of the evaporator temperature. In the second part, the effect of the mixing chamber convergence angle is studied. Results illuminated that by increment of the converging angle up to a certain value, the entrainment ratio and the COP enhance, but beyond the optimum angle, a reverse behavior is observed. However, by increment of the convergence angle, the critical back temperature declines continually. By increase of the convergence angle, the flow field inside the ejector is affected, and weaker shock waves are established at the end of mixing chamber that influence the critical back temperature.

ABSTRACT: This experimental study mainly focused on the investigation of CRDI diesel engine powered with palm oil methyl ester (POME) biodiesel and diesel fuels. The Toroidal Re-entrant combustion chamber shape (TRCC) and 6 holes CRDI injector were selected for experiment. The current research engine operated with constant CR 17.5 and speed 1500 rpm. In the first phase of work, the injection timing (IT) varied from -25 °BTDC to 5 °ATDC with interval of 5 degree during the experiments. The injection time-10 °BTDC has been optimized for higher engine efficiency. In the second phase of work, the injection opening pressure (IOP) has been varied form 600 bar to 1000 bar with increment of 100 bar interval during the experiments. The IOP of 900 bar has been optimized with constant fuel IT -10 °BTDC. Finally, the end results of experiments were reported that combined effects of IT (-10 °BTDC) and IOP (900 bar) enhanced the engine output in terms of brake thermal efficiency (BTE), also minimizing the pollutants using TRCC shape and 6-hole CRDI injector for CRDI diesel engine at 80% load.