A review of fuel additives' effects and predictions on internal combustion engine performance and emissions

<abstract> <p>In recent years, there has been an increasing interest in additives for fuel research in the field of internal-combustion engine. Many studies have been conducted to improve the performance and emissions of the engine. Many kinds of additives in the form of solid, liquid, and gas have been used. The objective of this review is to examine the effects of having additives on the performance and emission of internal combustion engine. Additives such as alcohol, hydrogen, and metal oxides are proven to be successful to improve performance or reduce emission. Results from selected papers are discussed and summarised in a table. With the new development in nanotechnology, many researchers have shown an increased interest in carbon-based. In recent years, there has been an increasing interest in additives for fuel research in the field of internal-combustion engines. Many studies have been conducted to improve the performance and emissions of the engine. Many kinds of additives in the form of solids, liquids, and gases have been used. The objective of this review is to examine the effects of having additives on the performance and emissions of an internal combustion engine. Additives such as alcohol, hydrogen, and metal oxides are proven to be successful in improving performance or reducing emissions. Results from selected papers are discussed and summarised in a table. With the new developments in nanotechnology, many researchers have shown an increased interest in carbon-based nanoparticles such as multi-walled carbon nanotubes (MWCNT) and single-walled carbon nanotubes (SWCNT). Lately, with the discovery of graphene production techniques, graphene nanoplatelets (GNP) have also been applied as fuel additives. In addition to understanding the effects of the additives on the engine performance and emissions, researchers extended the research to predict the outcome of the performance and emissions. nanoparticles such as multi-walled carbon nanotube (MWCNT) and single-walled carbon nanotube (SWCNT). Lately, with the discovery of graphene production techniques, graphene nanoplatelets (GNP) also has also been applied as fuel additives. In addition to the understanding the effects of the additives to the engine performance and emissions, researchers extended the research to predict the outcome of the performance and emissions. The experiments involving the predictions efforts are summarised in a table. From the summary, it is found that the prediction of the GNP as fuel additive effects to the performance and emissions has not yet been explored. This gap is an opportunity for researchers to explore further.</p> </abstract>

Parametric design analysis of elliptical shroud profile

<abstract> <p>Parametric design analysis for Eccentric Rotated Ellipsoid (ERE) shroud profile is conducted whereas the design model is validated experimentally. A relation between shroud inlet, length and exit diameter is established, different ratios related to the wind turbine diameter are introduced, and solution for different ERE family curves that passes on the inlet, throat, and exit points is studied. The performance of the ERE shroud is studied under different wind velocities ranging from 5–10 m/s.</p> <p>The method used in creating the shroud profile is by solving the ERE curve equations to generate large family of solutions. The system is modeled as axisymmetric system utilizing commercial software package. The effect of the parameters; shroud length, exit diameter, inlet diameter, turbine position with respect to the shroud throat, and wind velocity are studied. An optimum case for each shroud length, exit diameter and location of the shroud with respect to the wind turbine throat axis are achieved.</p> <p>The simulation results show an increase in the average wind velocity by 1.63 times of the inlet velocity. This leads to a great improvement in the wind turbine output power by 4.3 times of bare turbine. One of the achieved optimum solutions for the shroud curves has been prototyped for experimental validation. The prototype has been manufactured using 3D printing technology which provides high accuracy in building the exact shape of shroud design curve. The results show very good agreement with the experimental results.</p></abstract>

Overview of hydropower resources and development in Uganda

<abstract> <p>Even though hydropower plants are currently the most dominant source of electricity in Uganda, the rate of development of these resources for power generation remains low. Using a semi-systematic review approach, this paper seeks to understand why there is a slow rate of hydropower development in Uganda (challenges) and thereby provide potential solutions to these challenges. With current total capacity of about 1011 MW, findings indicate that there is a higher future prospect for hydropower generation in Uganda, with an estimated potential of over 4500 MW. In terms of number of projects, small-scale hydropower plants dominate power plants in Uganda, currently accounting for 19 out of 35 grid-connected power plants. However, with 855 MW installation capacity, large hydropower plants dominate the power generation plants landscape in Uganda. This study found that the challenges to hydropower development in this country are multi-dimensional including technical, economic, environmental, and social factors, and shows that the cross-cutting challenge is lack of human capacity that possess adequate skills to handle hydropower projects in the country. Furthermore, this study discussed practical solutions to address the identified problems facing hydro power in Uganda.</p> </abstract>

Techno-energy-economic sensitivity analysis of hybrid system Solid Oxide Fuel Cell/Gas Turbine

<abstract> <p>The paper presents a wide and deep analysis of the techno-energy and economic performance of a Solid Oxide Fuel Cell/Gas Turbine hybrid system fed by gas at different compositions of H₂, CO, H₂O, CO₂, CH_4, and N₂. The layout of the system accounts for pressurizing of entering fluids, heat up to the set Solid Oxide Fuel Cell inlet conditions, Solid Oxide Fuel Cell thermo-electrochemical processing, Solid Oxide Fuel Cell—exhaust fluids combustion, turbo-expansion after heat up, and final recovery unit for cogeneration purposes.</p> <p>An ad hoc numerical modeling is developed and then run in a Matlab calculation environment. The influence on the system is evaluated by investigating the change of the fuel composition, and by managing the main operating parameters such as pressure and the fuel utilization factor. The analysis reports on the specific mass flowrates necessary to the purpose required, by assessing the SOFC outlet molar compositions, specific energies (work) at main system elements, specific thermal energies at main system elements, energy and technical performance for Solid Oxide Fuel Cell energy unit; the performance such as electric and thermal efficiency, temperatures at main system elements. A final sensitivity analysis on the performance, Levelized Cost of Energy and Primary Energy Saving, is made for completion. The first simulation campaign is carried out on a variable anodic mixture composed of H₂, CO, H₂O, considering the H₂/CO ratio variable within the range 0.5-14, and H₂O molar fraction variable in the range 0.1-0.4; used to approach a possible syngas in which they are significantly high compared to other possible compounds. While other simulation campaigns are conducted on real syngases, produced by biomass gasification. The overall Solid Oxide Fuel Cell/Gas Turbine system showed a very promising electric efficiency, ranging from 53 to 63%, a thermal efficiency of about 37%, an LCOE ranging from 0.09 to 0.14 ＄·kWh^-1, and a Primary Energy Saving in the range of 33-52%, which resulted to be highly affected by the H₂/CO ratio.</p> <p>Also, real syngases at high H₂/CO ratio are noticed as the highest quality, revealing electric efficiency higher than 60%. Syngases with methane presence also revealed good performance, according to the fuel processing of methane itself to hydrogen. Low-quality syngases revealed electric efficiencies of about 51%. Levelized Cost of Energy varied from 0.09 (for high-quality gas) to 0.19 (for low-quality gas) ＄·kWh^-1, while Primary Energy Saving ranged from 44 to 52%.</p> </abstract>

Can the 1.5 ℃ warming target be met in a global transition to 100% renewable energy?

<abstract> <p>First, we recognize the valuable previous studies which model renewable energy growth with complete termination of fossil fuels along with assumptions of the remaining carbon budgets to reach IPCC warming targets. However, these studies use very complex combined economic/physical modeling and commonly lack transparency regarding the sensitivity to assumed inputs. Moreover, it is not clear that energy poverty with its big present impact in the global South has been eliminated in their scenarios. Further, their CO₂-equivalent natural gas emission factors are underestimated, which will have significant impact on the computed greenhouse gas emissions. Therefore, we address this question in a transparent modeling study: can the 1.5 ℃ warming target still be met with an aggressive phaseout of fossil fuels coupled with a 100% replacement by renewable energy? We compute the continuous generation of global wind/solar energy power along with the cumulative carbon dioxide equivalent emissions in a complete phaseout of fossil fuels over a 20 year period. We compare these computed emissions with the state-of-the-science estimates for the remaining carbon budget of carbon dioxide emissions consistent with the 1.5 ℃ warming target, concluding that it is still possible to meet this warming target if the creation of a global 100% renewable energy transition of sufficient capacity begins very soon which will likely be needed to power aggressive negative carbon emission technology. The latter is focused on direct air capture for crustal storage. More efficient renewable technologies in the near future will make this transition easier and promote the implementation of a global circular economy. Taking into account technological improvements in 2^nd law (exergy) efficiencies reducing the necessary global energy demand, the renewable supply should likely be no more than 1.5 times the present level, with the capacity to eliminate global energy poverty, for climate mitigation and adaptation.</p> </abstract>