Experimental studies of performance and emissions in a 2/4-stroke engine

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel UniversityDirect Injection (DI) gasoline engines are staging a come-back because of its potential for improved fuel economy through principally the engine down-sizing by boosting, stratified charge combustion and Controlled Auto Ignition (CAI) at part load operations. The problem with the Spark Ignition (SI) engine is its inherent low part-load efficiency. This arises due to the pumping loses that occur when the throttle closes or partially opens. One way of decreasing the pumping losses is to operate the engine lean or by adding residual gases. It is not possible to operate the engine unthrottled with a very lean or diluted mixture at low loads due to misfire. However, the load can also be controlled by changing the valve timing. This reduce the pumping loses and hence increase the efficiency. Due to the limited time available for complete fuel evaporation and the mixing of fuel and air mixture, locally fuel rich mixture or even liquid fuel can be present during the combustion process. This causes a significant increase in Particulate Matter (PM) emissions from direct injection gasoline engines compared to the conventional port fuel injection gasoline engines, which are of major concern because of its health implications. In the meantime, depleting reserves of fossil fuels and the increasing environmental pollution caused by burning of fossil fuels, have paved the way for fuel diversification. Cleaner and renewable fuel is being introduced worldwide. The use of ethanol as an alternative transportation fuel shows promise for several reasons. While ethanol can be produced from several types of biomass, it offers properties such as high octane number, higher oxygen content and high heat of evaporation, which make it a most attractive alternative fuel, in particular for the direct injection gasoline engine. In this research, a single cylinder camless engine equipped with an electro-hydraulic valve train system has been used to study and compare different engine operation modes in the SI and CAI combustion. The fuel consumption, gaseous and particulate emissions of gasoline and its mixture with ethanol (E15 and E85) were measured and analysed at the same engine operating condition. The heat release analysis and performance characteristics of CAI and SI combustion were carried out by the in-cylinder pressure measurement. The effect of load and valve timings on the gaseous and Particulate Matter (PM) emissions was investigated for both 4-stroke SI and CAI combustion. Within the achieved CAI operational ranges, particle emissions were found to be dominated by smaller particles (<50nm). Hotter charge and better mixing are the main parameters affecting the soot particles in the exhaust irrespective of the combustion modes and valve timings. At part-load conditions investigated, it was found that the CAI combustion produced the lowest NOx emissions of 0.4g/KWh in all fuel blends and lower fuel consumption 223g/KWh with improved combustion efficiency of 94.7% in ethanol fuel E15 and E85. The positive valve overlap was found to produce lowest fuel consumption of 222.8 g/KWh in all fuel blend and respond better to ethanol fuel in E15 and E85 with improved indicated efficiency of 40.5% compared to the other modes investigated. The early intake valve throttled SI operation led to a moderate improvement in the fuel consumption of 243.5g/KWh over the throttled SI operation but it was characterised by the slowest combustion and highest CO (33.5g/KWh) and HC (16.8g/KWh) emissions . Less and smaller particles numbers were detected for Early Intake Valve Closure (EIVC) from the combustion of E0 and E15 (4.0E+07#/cm3 less than 50nm in diameter) fuel blends. The particulate emission results showed that soot was the dominant particles in the exhaust, which could be reduced by leaner mixture combustion .Tertiary Education Trust Fund and University of Portharcourt Nigeri

Analysis of Subsea Energy Supply Systems for Improved Maintenance Using ANFIS and TOPSIS

The maintenance plan for the subsea energy supply system during the operation was optimized by firstly training the Adaptive Neuro-Fuzzy Inference System (ANFIS) model with historical data of process variables of the system such as voltage, current, power, and pressure in MATLAB software and then predicting the optimum output of the process using the trained model, which showed a good prediction of operational data after two cycles of computational analysis. The outputs from the trained model, coupled with expert opinions on historical data, were used to develop a Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) multi-criteria algorithm to select the best maintenance strategy. The reliability-centred maintenance, with a performance score of 0.811, ranked best amongst the maintenance strategies under the studied scenario. The result shows that the procedure could be applied in condition monitoring of operational subsea energy supply systems to predict impending faults through deviation error and prevent failure by the application of an appropriate maintenance strategy. Keywords: ANFIS, TOPSIS, Maintenance plan, Fault prediction and Subsea power supply systems DOI: 10.7176/ISDE/12-2-02 Publication date: April 30th 202

Effects of ethanol on combustion and emissions of a gasoline engine operating with different combustion modes

The introduction of fuel economy and CO2 emission legislations for passenger cars in many countries and regions has spurred the research and development of more efficient gasoline engines. The pumping loss at part-load operations is a major factor for the higher fuel consumption of spark ignition (SI) gasoline engines than the diesel engines. Various approaches have been identified to reduce the pumping loss at part-load operations, leading to improved fuel economy, including Early Intake Valve Closing (EIVC), Positive Valve Overlap (PVO) and Controlled Auto-Ignition (CAI) combustion. On the other hand, in order to reduce the CO2 emissions from the fossil fuel, ethanol produced from renewable resources is becoming widely used in the gasoline engine. In this paper, the performance, combustion and emissions were measured, analyzed and compared between gasoline and its mixture with ethanol (E15 and E85) at a typical part-load condition when a direct injection gasoline engine was operated with the CAI combustion by means of the negative valve overlap (NVO) and SI combustion by means of the intake throttled, EIVC and PVO. An electro hydraulic actuated camless system enabled the engine to be operated with CAI combustion and SI combustion of different valve timings and durations at the same load. The results showed that the CAI combustion reduces NOx emissions by more than 90%. The PVO results in better mixture preparations and improved combustion efficiency and best fuel economy compared to all the other modes. The EIVC operation led to a moderate improvement in the fuel conversion efficiency over the throttled SI operation but it was characterised by the slowest combustion and worst HC and CO emissions. Fewer and smaller particles numbers were detected in EIVC using E0 and E15 fuel blends. Using ethanol blends reduces the knocking combustion in CAI modes by about 50%. The use of E85 resulted in an increased number of particulate emissions in EIVC but increased ISFC in all the modes. The particulate emission results showed that soot is the dominant particle in the exhaust

Multicriteria GIS-based assessment of biomass energy potentials in Nigeria

The understanding of the geographical variability of biomass energy is an essential requirement for the optimal location of biomass energy conversion plants. This research presents a multicriteria GIS-based assessment of biomass energy potentials and the appropriate siting of biomass plants in Nigeria. The study applies the weighted overlay multicriteria decision analysis method. Crop and forest areas, settlement (energy supply areas), shrub/grasslands, barren land, water bodies, distance from water sources, road accessibility, topography, and aspect are the criteria that were considered for locating a biomass facility in this study. The results suggest that the theoretical, technical, and economical energy potentials of crop residues are highest in the North-East region of Nigeria and estimated at 1,163.32, 399.73, and 110.56 PJ/yr, respectively, and lowest in the South-East at 52.36, 17.99, and 4.98 PJ/yr, respectively. The theoretical, technical, and economical energy potentials of forest residues are highest in the North-West, estimated at 260.18, 156.11, and 43.18 PJ/yr, respectively, and lowest in the South-East at 1.79, 1.08, and 0.30 PJ/yr, respectively. Although most areas were identified to be suitable for siting biomass plants across Nigeria, the most suitable areas are located in the northern part of the country and include Niger, Zamfara, the Federal Capital Territory, Nassarawa, Kano, Kebbi, Kaduna, and Borno State. The study supports the Nigerian bio-energy policy that proposes to effectively utilize Nigeria’s non-fuelwood as a substitute for the felling of trees. This is very important to strengthen its commitment at the COP26 International Climate Conference, which is to conserve and restore its forest. Furthermore, this study will serve as a good reference for policymakers to make well-informed decisions on tackling the energy insecurity in Nigeria

Optimal mapping of hybrid renewable energy systems for locations using multi-criteria decision-making algorithm

This paper presents the optimal mapping of hybrid energy systems, which are based on wind and PV, with the consideration of energy storage and backup diesel generator, for households in six locations in the South-South geopolitical (SS) zone of Nigeria: Benin-city, Warri, Yenagoa, Port Harcourt, Uyo and Calabar. The optima hybrid energy systems are able to meet 7.23 kWh/day household's electrical energy demand. The hybrid energy system for each of the locations was optimally obtained based on HOMER software computation and TOPSIS multi-criteria decision-making algorithm that considers technical, economic, environmental, and sociocultural criteria. Wind energy potential was conducted for the six locations using the Weibull distribution function; the wind speed ranges between 3.21 and 4.19 m/s at 10 m anemological height. The wind speeds and the wind characteristics were extrapolated for 30 m and 50 m hub heights. The solar resource potentials across the six locations are also presented – ranges between 4.21 and 4.71 kWh/m2/day. The best hybrid system for the locations in Benin-city, Yenagoa and Port Harcourt is the Diesel generator-PV-Wind-Battery system; whereas the best hybrid system for the locations in Warri, Uyo and Calabar is the PV-Wind-Battery system. The hybrid systems in Benin-city, Yenagoa and Port Harcourt emit CO2, only 8.47%, 15.02% and 14.09% of the business as usual (the diesel generator). The payback time ranges between 3.7 and 5.4 years, using 0.893 US$/kWh cost of energy obtained for the business as usual. The cost of energy of the hybrid systems ranges between 0.459 and 0.562 US$/kWh, which compares well with available data in the public domain. The design parameters of the optima hybrid energy systems are also presented. The methodology presented here will serve as a design tool for renewable energy professionals

CAI combustion of gasoline and its mixture with ethanol in a 2-stroke poppet valve DI gasoline engine

This article has been made available through the Brunel Open Access Publishing Fund.Controlled Auto Ignition (CAI), also known as Homogeneous Charge Compression Ignition (HCCI), is one of the most promising combustion technologies to reduce the fuel consumption and NOx emissions. Currently, CAI combustion is constrained at part load operation conditions because of misfire at low load and knocking combustion at high load, and the lack of effective means to control the combustion process. Extending its operating range including high load boundary towards full load and low load boundary towards idle in order to allow the CAI engine to meet the demand of whole vehicle driving cycles, has become one of the key issues facing the industrialisation of CAI/HCCI technology. Furthermore, this combustion mode should be compatible to different fuels, and can switch back to conventional spark ignition operation when necessary. In this paper, the CAI operation is demonstrated on a 2-stroke gasoline direct injection (GDI) engine equipped with a poppet valve train. The results shown that the CAI combustion can be readily achieved in the 2-stroke cycle of a poppet valve engine and the range of CAI combustion can be significantly extended compared to the 4-stroke cycle operation. In addition, the effects of ethanol concentration on 2-stroke CAI operational range, combustion process, emissions and efficiencies are studied and presented. © 2013 Elsevier Ltd. All rights reserved

Performance and nutrient digestibility of broiler chickens fed graded levels of fermented and toasted Albizia lebbeck seed meal

This study was conducted to investigate the effects of fermented and toasted Albizia lebbeck seed meal (FTALSM), on the growth performance and nutrient digestibility of broiler chickens at the starter and finisher phases. One hundred and fifty (150) day old chicks (Abo acres) were used for this study and were divided into five treatments (with three replicate each containing 10 birds) using a completely randomized design (CRD) for eight weeks. The treatments were&nbsp;five diets containing0%(control), 5%,10%,15% and 20%of fermented and toastedAlbizia lebbeck seedmeal (FTALSM), respectively and were tagged Diet 1, 2, 3, 4 and 5. The diets were formulated to be isocaloric and isonitrogenous. The feed intake at the starter phase was significantly higher (p&lt;0.05) in Diets 3 and 4 which had 10 and 15% inclusion of FTALSM, respectively. Diets 2, 3 and 4 also differ significantly (p&lt;0.05) in final body weight and total weight gained from the control diets. The results at the finisher phase indicated that, there were significant differences (P&lt;0.05) in all the parameters measured except for mortality. Birds fed Diet 2 performed significantly better in weight gain (1453g) and feed intake (3087.25g) compared to the control group. Birds on the control and Diet 2 had similar feed efficiency, the values were however, better than those on the other treatments. The results of nutrient digestibility showed birds fed Diet 5 (20% FTALSM) recorded significantly (P&lt;0.05) low digestibility values in all parameters measured. The results showed that fermentation and toasting reduced phytase, oxalate and cyanide by 41.87, 26.67 and 99.94 % respectively. It can be concluded therefore, that FTALSM can be included up to 15%in broiler chickens starter diets and 5%in the finisher diet for optimum growth performance