Numerical Investigation of an RCCI engine fueled with natural gas/dimethyl-ether in various injection strategies

Copyright: © 2021 by the authors. Reactivity control compression ignition engines illustrated suitable abilities in emission reduction beside high thermal efficiency. In this research, nine various direct fuel injection strategies were studied numerically: three cases with single injection strategy and six cases with split injection and different start of injection (SOI). In all simulated cases, equivalence ratio kept constant (i.e., 0.3). Among various strategies, single injection showed higher IMEP as a factor of efficiency with about 5.39 bar that occurred at SOI = 60 before top dead center (bTDC), while lower efficiency was observed for split injection case with 50%-50% injections of fuel in each injection stage. Start of combustion (SOC), burn duration and CA50 as factors for combustion characteristics were affected with SOI changes. In single SOI strategies, more advanced injection caused more advanced SOC where there was about 1.3 CAD advancing from 40 to 80 bTDC injection. Spilt SOI showed more advanced SOC, which, also more advanced, was allocated to 50%-50% split injection strategy. There was also the same trend in CA50 changes during change in SOI. Burn duration variations were insignificant and all of them approximately close to 4.5 CAD. According to the emissions researched in this study (Nitrogen Oxides (NOx), monoxide carbon (CO) and unburned hydro carbons (UHC)), all of these pollutants are below euro six diesel standards. Contours of emissions show that there were appropriate SOI for each case study, which were 45 degree bTDC for single strategy, 48 degree bTDC for 80%-20% mass injection and 70 degree bTDC for 50%-50% cases

Design of the Organic Rankine Cycle for High-Efficiency Diesel Engines in Marine Applications

Data Availability Statement: Data available on request due to privacyCopyright © 2023 by the authors. Over the past few years, fuel prices have increased dramatically, and emissions regulations have become stricter in maritime applications. In order to take these factors into consideration, improvements in fuel consumption have become a mandatory factor and a main task of research and development departments in this area. Internal combustion engines (ICEs) can exploit only about 15–40% of chemical energy to produce work effectively, while most of the fuel energy is wasted through exhaust gases and coolant. Although there is a significant amount of wasted energy in thermal processes, the quality of that energy is low owing to its low temperature and provides limited potential for power generation consequently. Waste heat recovery (WHR) systems take advantage of the available waste heat for producing power by utilizing heat energy lost to the surroundings at no additional fuel costs. Among all available waste heat sources in the engine, exhaust gas is the most potent candidate for WHR due to its high level of exergy. Regarding WHR technologies, the well-known Rankine cycles are considered the most promising candidate for improving ICE thermal efficiency. This study is carried out for a six-cylinder marine diesel engine model operating with a WHR organic Rankine cycle (ORC) model that utilizes engine exhaust energy as input. Using expander inlet conditions in the ORC model, preliminary turbine design characteristics are calculated. For this mean-line model, a MATLAB code has been developed. In off-design expander analysis, performance maps are created for different speed and pressure ratios. Results are produced by integrating the polynomial correlations between all of these parameters into the ORC model. ORC efficiency varies in design and off-design conditions which are due to changes in expander input conditions and, consequently, net power output. In this study, ORC efficiency varies from a minimum of 6% to a maximum of 12.7%. ORC efficiency performance is also affected by certain variables such as the coolant flow rate, heat exchanger’s performance etc. It is calculated that with the increase of coolant flow rate, ORC efficiency increases due to the higher turbine work output that is made possible, and the condensing pressure decreases. It is calculated that ORC can improve engine Brake Specific Fuel Consumption (BSFC) from a minimum of 2.9% to a maximum of 5.1%, corresponding to different engine operating points. Thus, decreasing overall fuel consumption shows a positive effect on engine performance. It can also increase engine power output by up to 5.42% if so required for applications where this may be deemed necessary and where an appropriate mechanical connection is made between the engine shaft and the expander shaft. The ORC analysis uses a bespoke expander design methodology and couples it to an ORC design architecture method to provide an important methodology for high-efficiency marine diesel engine systems that can extend well beyond the marine sector and into the broader ORC WHR field and are applicable to many industries (as detailed in the Introduction section of this paper).This research received no external funding

Comparative Assessment of sCO2 Cycles, Optimal ORC, and Thermoelectric Generators for Exhaust Waste Heat Recovery Applications from Heavy-Duty Diesel Engines

Data Availability Statement: Data available on request due to privacy.Copyright © 2023 by the authors. This study aimed to investigate the potential of supercritical carbon dioxide (sCO2), organic Rankine cycle (ORC), and thermoelectric generator (TEG) systems for application in automotive exhaust waste heat recovery (WHR) applications. More specifically, this paper focuses on heavy-duty diesel engines applications such as marine, trucks, and locomotives. The results of the simulations show that sCO2 systems are capable of recovering the highest amount of power from exhaust gases, followed by ORC systems. The sCO2 system recovered 19.5 kW at the point of maximum brake power and 10.1 kW at the point of maximum torque. Similarly, the ORC system recovered 14.7 kW at the point of maximum brake power and 7.9 kW at the point of maximum torque. Furthermore, at a point of low power and torque, the sCO2 system recovered 4.2 kW of power and the ORC system recovered 3.3 kW. The TEG system produced significantly less power (533 W at maximum brake power, 126 W at maximum torque, and 7 W at low power and torque) at all three points of interest due to the low system efficiency in comparison to sCO2 and ORC systems. From the results, it can be concluded that sCO2 and ORC systems have the biggest potential impact in exhaust WHR applications provided the availability of heat and that their level of complexity does not become prohibitive.This research received no external funding

Electric Vehicle Modelling for Future Technology and Market Penetration Analysis

Data Availability Statement: The original contributions presented in the study are included in the article/Supplementary Material, further inquiries can be directed to the corresponding author.The transportation sector is generally thought to be contributing up to 25% of all greenhouse gases (GHG) emissions globally. Hence, reducing the usage of fossil fuels by the introduction of electrified powertrain technologies such as hybrid electric vehicle (HEV), battery electric vehicle (BEV) and Fuel Cell Electric Vehicle (FCEV) is perceived as a way towards a more sustainable future. With a seemingly more significant shift towards BEV development and roll-out, the research and development of BEV technologies has taken on increasing importance in improving BEV performance and ensuring its competitiveness. Numerical simulation, using MATLAB, is performed as a tool to investigate and to improve the overall performance of BEVs. This study provides an overview of the possible technology outcome and market consequences for future compact BEVs along with HEVs, FCEVs and internal combustion engine vehicles (ICEV). The techno-economics of BEVs, market projection and cost analysis up to 2050 are investigated, as are important BEV characteristics alongside those of other types of vehicles. Well-to-wheel analysis of BEVs is also studied and compared with HEV, FCEV and ICE

Numerical Study on Hydrogen–Gasoline Dual-Fuel Spark Ignition Engine

Data Availability Statement: This study did not report any data.Copyright © 2022 by the authors. Hydrogen, as a suitable and clean energy carrier, has been long considered a primary fuel or in combination with other conventional fuels such as gasoline and diesel. Since the density of hydrogen is very low, in port fuel-injection configuration, the engine’s volumetric efficiency reduces due to the replacement of hydrogen by intake air. Therefore, hydrogen direct in-cylinder injection (injection after the intake valve closes) can be a suitable solution for hydrogen utilization in spark ignition (SI) engines. In this study, the effects of hydrogen direct injection with different hydrogen energy shares (HES) on the performance and emissions characteristics of a gasoline port-injection SI engine are investigated based on reactive computational fluid dynamics. Three different injection timings of hydrogen together with five different HES are applied at low and full load on a hydrogen–gasoline dual-fuel SI engine. The results show that retarded hydrogen injection timing increases the concentration of hydrogen near the spark plug, resulting in areas with higher average temperatures, which led to NOX emission deterioration at −120 Crank angle degree After Top Dead Center (CAD aTDC) start of injection (SOI) compared to the other modes. At −120 CAD aTDC SOI for 50% HES, the amount of NOX was 26% higher than −140 CAD aTDC SOI. In the meanwhile, an advanced hydrogen injection timing formed a homogeneous mixture of hydrogen, which decreased the HC and soot concentration, so that −140 CAD aTDC SOI implied the lowest amount of HC and soot. Moreover, with the increase in the amount of HES, the concentrations of CO, CO2 and soot were reduced. Having the HES by 50% at −140 CAD aTDC SOI, the concentrations of particulate matter (PM), CO and CO2 were reduced by 96.3%, 90% and 46%, respectively. However, due to more complete combustion and an elevated combustion average temperature, the amount of NOX emission increased drastically.This research received no external funding

Challenges and opportunities confronting female-headed households in Iran: a qualitative study

BACKGROUND: Female-headed households are one of the most vulnerable groups of society that confront many problems and challenges. Therefore, the present study aimed to explore the challenges and opportunities confronting female-headed households in Iran. METHODS: This qualitative study was conducted among female-headed households in Kermanshah, West of Iran, in 2019. The data were collected through Semi-structured interviews with 26 female-headed households who were selected by purposeful and theoretical sampling. Data analysis was done through conventional qualitative content analysis, and the software MAXQDA-12 was used for the management of data. The four criteria of Goba and Lincon, including credibility, confirmability, dependability, and transferability, were observed to evaluate the quality of research results. RESULTS: After analyzing the data, 4 main categories and 13 subcategories were obtained as follows: individual problems (role overload, role conflict, end of love, psychological problems), intra-family problems (declined independence, intra-family tension, poverty reproduction and family disability), social problems (stigma of being unattended, social insecurity, social isolation, social exclusion), positive outcomes (positive self-concept, social maturity). CONCLUSION: Female-headed households face many challenges that can become a big threat or an opportunity. Therefore, their health improvement can be achieved through training and helping them to adapt to new and multifaceted roles, providing more economic support and helping them raise their social status

Experiences and challenges of Prostitute Women in Iran: A phenomenological qualitative study

Background: Prostitutes in Iran are faced with many challenges and problems that pose risks to their health. Objective: The present study is an attempt to identify and narrate the challenges and experiences of Iranian prostitutes based on a qualitative approach. Methods: This qualitative study was conducted with a phenomenological approach in (2018) in Tehran, Iran. The data were collected through semi-structured interviews with 22 prostitutes who were selected using a snowball sampling method and analyzed with Colaizzi's method. In order to examine the quality of findings, Guba and Lincoln's measures were used. Results: Data analysis results were classified into five main categories and 14 subcategories. The main issues are: The experience of violence, Heath risk, social ostracism, objectifying, and lack of social and legal supporting structures. Conclusion: Prostitutes in Iran experience numerous problems at personal and social levels. By providing social, economic, and legal supports for them such as social services (e.g. educations on how to use contraceptives, how to have safe sexual intercourse, and free counseling services for mental support), we can improve their health and welfare. © 2020 The Author(s

Experimental investigation of thermal balance of a turbocharged SI engine operating on natural gas

This paper experimentally investigates the thermal balance and performance of a turbocharged gas spark ignition engine. The First Law of Thermodynamics was used for control volume around the engine to compute the output power, transferred energy to the cooling fluid, exhaust gases and also unaccounted losses through convection and radiation heat transfer. Thermal balance tests were performed for various operational conditions including full and half loads and different cooling fluid temperatures. Results indicate that by increasing engine load and coolant temperature, the percentage of transferred energy to the exhaust gases increased while the percentage of coolant energy decreased. Also, experimental data reveals that using gaseous fuel and a turbocharger (TC) in the engine leads to 4.5% and 4% more thermal efficiency than gasoline and natural aspirated (NA), respectively. Also, second law analysis reveals that using a turbocharger leads to a 3.6% increase in exergetic efficiency of the engine, averagely. Based on experimental results, an empirical correlation was suggested for computing the energy of exhaust gases which shows good agreement with the experimental data for the majority of operating conditions

Towards fossil-free fuels in sustainable powertrain; alcohol-fueled low-temperature combustion (LTC)

Abstract Low-temperature combustion (LTC) engines are able toreduce nitrogen oxides (NOx) and particulate matter (PM) emissions, simultaneously. LTC engines suffer from higher amounts of unburned hydrocarbon (uHC) and carbon monoxide (CO) emissions, particularly in low-load operating conditions of the engine. The existence of oxygen molecules in the alcohol fuels not only results in more combustion completeness but also leads to lower CO and uHC emissions

INVESTIGATION OF THE EFFECT OF ADDITIVES TO NATURAL GAS ON HEAVY-DUTY SI ENGINE COMBUSTION CHARACTERISTICS

This work investigates the implications of natural-gas composition on the combustion in a heavy-duty natural-gas engine and on the associated pollutant emissions. Natural gas is injected in ports and mixes with air before entering the cylinder. For the ignition source, both a spark plug and diesel pilot, which is injected before the top-dead center in the cylinder, are used. The effect of additives such as hydrogen, ethane and nitrogen on the output power and efficiency of the engine and emission levels are examined. The results indicate that these additives had no significant effect on the engine’s power or fuel consumption. Emissions of unburned fuel are reduced for all additives through either enhanced ignition or combustion processes. Adding ethane and H2 to the fuel increases the in-cylinder pressure and NOx emission, while fuel dilution with N2 has a critical amount. Black carbon particulate matter emissions are increased by ethane, but are virtually eliminated by including nitrogen or hydrogen in the fuel. The results show the higher flame speed of ethane compared to hydrogen, and hydrogen compared to methane. Thus, to reach the MBT condition, the spark time of ethane is the most retarded one and for methane it is the most advanced