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The fuel combustion in diesel engines can be improved by adding nanomaterials to the fuel which result in an reduction in pollutant emissions and enhance the quality of fuel combustion. The engine performance and soot nanoparticles characteristics were evaluated in this study with adding nanoparticles of copper oxide (CuO2) to the rapeseed methyl ester (RME) and diesel under variable engine speeds. The addition of CuO2 to the RME significantly improve brake thermal efficiency (BTE) and decline the brake specific fuel consumption (BSFC) by 23.6% and 7.6%, respectively, compared to the neat RME and diesel fuel. The inclusion CuO2 nanoparticles into the RME and diesel led to decrease the concentration and number of particulate matter (PM)by 33% and 17% in comparison with neat RME and diesel without nano additives, respectively. Moreover, PM is significantly decreased by 31.5% during the RME combustion in comparison with neat RME and diesel under various engine speeds. It was also obtained that the number of emitted particles (npo) reduced by 23.5% with adding nanoparticles to the RME in comparison with diesel, while the diameter of soot nanoparticles (dpo) increased by 8.6% in comparison with diesel. Furthermore, the addition CuO2 to the RME decreased the size and number of particles more than to the diesel fuel.

Wind turbine farms require efficient operation and maintenance strategies to ensure long-term profitability and cost-effectiveness. However, temperatures and dust accumulation can significantly affect turbine performance and increase maintenance costs. This study investigates the impact of air filter clogging on wind turbine nacelle temperature and performance by collecting data from the Supervisory Control and Data Acquisition (SCADA) system of wind farms in southern Jordan, including temperature, wind speed, and power generation. The findings demonstrate that uncleaned air filters can lead to inefficient heat dissipation, higher nacelle temperatures, and reduced power production. Turbines with uncleaned filters experienced an average nacelle temperature increase of 15.44 °C compared to 13.30 °C for turbines with clean filters, resulting in a difference in the power production of 66.54 kW.

The developments in the field of nano-additives have increased in the recent years due to the desire to reduce the level of exhaust emissions in diesel engines. The soot characteristics of particulate matter (PM) and nitrogen oxides (NOX) were experimentally investigated using two concentrations of titanium dioxide (TiO2) as nano-additives (25 ppm and 40 ppm) blended with C20D (composed of 20% castor oil methyl ester and 80% diesel fuel) and 30% exhaust gas recirculation (EGR). The combustion of C20D + TiO2 increases brake thermal efficiency (BTE) by 2.8% in comparison with neat C20D, while a significant reduction was obtained in BSFC 6.5% and NOX emissions were maintained at a level parallel with diesel. The results indicated that the technique involving a high EGR rate and the addition of 25 ppm and 40 ppm of TiO2 nanoparticles to the C20D exhibits better reductions in NOX emissions by 17.34% and 21.83%, respectively, compared to the technique comprising the use of C20D + TiO2 and C20D. The reduction in the total concentration of PM via the addition of TiO2 nanoparticles to the C20D was 26.74% greater than neat C20D and diesel. In contrast, the incorporation of a high rate of EGR with C20D +TiO2 increased the PM concentrations by 16.85% compared to the technique without EGR. Furthermore, the high concentrations of TiO2 nanoparticles (40 ppm) in the C20D produced 19 nm smaller soot nanoparticles compared to the 23 nm larger soot nanoparticles produced from the low concentrations of TiO2 nanoparticles (25 ppm) added into the C20D. The current investigation reveals that the reduction in NOX emissions and the production of soot nanoparticles notably improved due to the synergic effect of EGR, the TiO2 nanoparticles, and biodiesel.

Both electrical and thermal efficiencies combine in determining and evaluating the performance of a PV/T collector. In this study, two PV/T systems consisting of poly and monocrystalline PV panels were used, which are connected from the bottom by a heat exchanger consisting of a spiral tube through which a nanofluid circulates. In this study, a base fluid, water, and ethylene glycol were used, and iron oxide nanoparticles (nano-Fe2O3) were used as an additive. The mixing was carried out according to the highest specifications adopted by the researchers, and the thermophysical properties of the fluid were carefully examined. The prepared nanofluid properties showed a limited effect of the nanoparticles on the density and viscosity of the resulting fluid. As for the thermal conductivity, it increased by increasing the mass fraction added to reach 140% for the case of adding 2% of nano-Fe2O3. The results of the zeta voltage test showed that the supplied suspensions had high stability. When a mass fraction of 0.5% nano-Fe2O3 was added the zeta potential was 68 mV, while for the case of 2%, it reached 49 mV. Performance tests showed a significant increase in the efficiencies with increased mass flow rate. It was found when analyzing the performance of the two systems for nanofluid flow rates from 0.08 to 0.17 kg/s that there are slight differences between the monocrystalline, and polycrystalline systems operating in the spiral type of exchanger. As for the case of using monocrystalline PV the electrical, thermal, and total PV/T efficiencies with 2% added Fe2O3 ranged between 10% to 13.3%, 43–59%, and 59 to 72%, respectively, compared to a standalone PV system. In the case of using polycrystalline PV, the electrical, thermal, and total PV/T efficiencies ranged from 11% to 13.75%, 40.3% to 63%, and 55.5% to 77.65%, respectively, compared to the standalone PV system. It was found that the PV/T electrical exergy was between 45, and 64 W with thermal exergy ranged from 40 to 166 W, and total exergy from 85 to 280 W, in the case of using a monocrystalline panel. In the case of using polycrystalline, the PV/T electrical, thermal, and total exergy were between 45 and 66 W, 42–172 W, and 85–238 W, respectively. The results showed that both types of PV panels can be used in the harsh weather conditions of the city of Baghdad with acceptable, and efficient productivity.

This study provides a meta-analysis of renewable landscape energies in Iran. In order to do this effectively, we identify and estimate the amount of wind, solar, geothermal, biomass and tidal energy in Iran, identifying the potential for exchanging RE with neighboring countries, and methods for utilizing these energies in architectural design and landscape design. Data used are collecting from local and world databases and presented for analysis using descriptive and inferential statistics. The results show that the level of achievements of the stated goals is generally low. The plurality of RE documents and offices, lack of operational programs and sub-optimal use of private sector capacity are the main weaknesses. It is further concluded that if conditions were more conducive to private sector participation and appropriate operational and action plans were adopted, Iran could supply solar energy to Azerbaijan, wind energy to Turkmenistan and Afghanistan, and can supply Iraq with hydropower. Ultimately it is proposed that the adoption of a comprehensive and integrated RE policy which minimizes the number of policy documents and concentrates RE management in a small number of offices is an important factor in facilitating the success of renewable energies in Iran.

Wind turbine blades perform the most important function in the wind energy conversion process. It plays the most vital role of absorbing the kinetic energy of the wind, and converting it to mechanical energy before it is transformed into electrical energy by generators. In this work, National Advisory Committee for Aeronautics (NACA) 4412 and SG6043 airfoils were selected to design a small horizontal axis variable speed wind turbine blade for harvesting efficient energy from low wind speed areas. Due to the low wind profile of the targeted area, a blade of one-meter radius was considered in this study. To attain the set objectives of fast starting time and generate more torque and power at low wind speeds, optimization was carryout by varying Reynolds numbers (Re) on tip speed ratios (TSR) values of 4, 5, and 6. The blade element momentum (BEM) method was developed in MATLAB programming code to iteratively find the best twist and chord distributions along the one-meter blade length for each Re and tip speed ratio (TSR) value. To further enhance the blade performance, the twist and chord distributions were transferred to Q-blade software, where simulations of the power coefficients (Cp) were performed and further optimized by varying the angles of attack. The highest power coefficients values of 0.42, 0.43, and 0.44 were recorded with NACA 4412 rotor blades, and 0.43, 0.44, and 0.45 with SG6043 rotor blades. At the Re of 3.0 × 105, the blades were able to harvest maximum power of 144.73 watts (W), 159.69 W, and 201.04 W with the NACA 4412 and 213.15 W, 226.44 W, 245.09 W with the SG6043 at the TSR of 4, 5, and 6 respectively. The lowest cut-in speed of 1.80 m/s and 1.70 m/s were achieved with NACA 4412 and SG6043 airfoils at TSR 4. At a low wind speed of 4 m/s, the blades were able to harness an efficient power of 79.3. W and 80.10 W with both rotor blades at the TSR 4 and 6 accordingly.

In the present study, the effects of graphene oxide (GO) nano-particles on performance and emissions of a diesel engine fueled with Oenothera lamarckiana biodiesel was investigated. Biodiesel was used in the blend of B20. The GO nano-particles with concentrations of 30, 60, and 90 ppm were considered for each fuel blend. Experiments were performed at a constant speed of 2100 rpm at loads of 0%, 25%, 50%, 75%, and 100%. Various parameters, such as power, exhaust gas temperature (EGT), carbon monoxide (CO), carbon dioxide (CO2), unburned hydrocarbons (UHCs), and nitrogen oxides (NOx), were investigated. Results showed that by using GO, power and EGT significantly increase. Furthermore, by using GO nano-particles, significant reductions in CO (∼5%–22%) and UHCs (∼17%–26%) were observed. However, under similar conditions, a slight increase in CO2 (∼7%–11%) and NOx (∼4%–9%) emissions observed. Finally, it can be concluded that nano-graphene oxide can be introduced as a suitable alternative fuel additive for Oenothera lamarckiana biodiesel blends.

As the global search for new methods to combat global warming and climate change continues, renewable fuels and hydrogen have emerged as saviours for environmentally polluting industries such as aviation. Sustainable aviation is the goal of the aviation industry today. There is increasing interest in achieving carbon-neutral flight to combat global warming. Hydrogen has proven to be a suitable alternative fuel. It is abundant, clean, and produces no carbon emissions, but only water after use, which has the potential to cool the environment. This paper traces the historical growth and future of the aviation and aerospace industry. It examines how hydrogen can be used in the air and on the ground to lower the aviation industry’s impact on the environment. In addition, while aircraft are an essential part of the aviation industry, other support services add to the overall impact on the environment. Hydrogen can be used to fuel the energy needs of these services. However, for hydrogen technology to be accepted and implemented, other issues such as government policy, education, and employability must be addressed. Improvement in the performance and emissions of hydrogen as an alternative energy and fuel has grown in the last decade. However, other issues such as the storage and cost and the entire value chain require significant work for hydrogen to be implemented. The international community’s alternative renewable energy and hydrogen roadmaps can provide a long-term blueprint for developing the alternative energy industry. This will inform the private and public sectors so that the industry can adjust its plan accordingly.

With its unique qualities, such as infinite supply, high octane number, and capacity to cut greenhouse gas emissions, alcohol is a viable alternative fuel for SI engines. This review article aims to reveal to readers the effects of alcohol on the performance, combustion behavior, and emission characteristics of SI engines by collecting the outcomes from previous research. This article looks at methanol, ethanol, and butanol fuel qualities. The performance of SI engines with butanol, ethanol, and methanol combined with gasoline is investigated in terms of brake torque, brake power, fuel consumption, thermal efficiency, volumetric efficiency, mean effective pressure, and coefficient of variation under various conditions. Second, in-cylinder pressure, mass fraction burnt, ignition delay, pressure increases, and heat release rates are also used to evaluate the combustion characteristic. Finally, the article discusses pollutant emissions such as CO, CO2, NOx, UHC, and exhaust gas temperature. Methanol, ethanol, and butanol mixed with gasoline increased fuel consumption and lowered spark-ignition engines’ thermal efficiency. When alcohol was combined with gasoline, most research found that CO, NOx, and UHC emissions were reduced due to improved combustion.

The objective of this review is to provide a deep overview of liquid biofuels produced from sugarcane bagasse and to address the economic challenges of an ethanol and acetone-butanol-ethanol blend in commercial processes. The chemistry of sugarcane bagasse is presented. Pretreatment technologies such as physical, chemical pretreatment, biological, and combination pretreatments used in the fermentation process are also provided and summarised. Different types of anaerobic bacteria Clostridia (yeast) are discussed to identify the ingredient best suited for sugarcane bagasse, which can assist the industry in commercializing ethanol and acetone-butanol-ethanol biofuel from biomass sugarcane. The use of an acetone-butanol-ethanol mixture and ethanol blend in internal combustion engines is also discussed. The literature then supports the proposal of the best operating conditions for fermentation to enhance ethanol and acetone-butanol-ethanol plant efficiency in the sugar waste industry and its application in internal combustion engines.

The widespread COVID-19 epidemic and political instability worldwide caused a significant transformation in the world’s fuel market [...]

Currently, the existing condition-based maintenance (CBM) diagnostic test practices for ultrasound require the tester to interpret test results manually. Different testers may give different opinions or interpretations of the detected ultrasound. It leads to wrong interpretation due to depending on tester experience. Furthermore, there is no commercially available product to standardize the interpretation of the ultrasound data. Therefore, the objective is the correct interpretation of an ultrasound, which is one of the CBM methods for medium switchgears, by using an artificial neural network (ANN), to give more accurate results when assessing their condition. Information and test results from various switchgears were gathered in order to develop the classification and severity of the corona, surface discharge, and arcing inside of the switchgear. The ultrasound data were segregated based on their defects found during maintenance. In total, 314 cases of normal, 160 cases of the corona, 149 cases of tracking, and 203 cases of arcing were collected. Noise from ultrasound data was removed before uploading it as a training process to the ANN engine, which used the extreme learning machine (ELM) model. The developed AI-based switchgear faults classification system was designed and incorporated with the feature of scalability and can be tested and replicated for other switchgear conditions. A customized graphical user interface (GUI), Ultrasound Analyzer System (UAS), was also developed, to enable users to obtain the switchgear condition or classification output via a graphical interface screen. Hence, accurate decision-making based on this analysis can be made to prioritize the urgency for the remedial works.

The demand for fossil fuels is increasing because of globalization and rising energy demands. As a result, many nations are exploring alternative energy sources, and hydrogen is an efficient and practical alternative fuel. In the transportation industry, the development of hydrogen-powered cars aims to maximize fuel efficiency and significantly reduce exhaust gas emission and concentration. The impact of using hydrogen as a supplementary fuel for spark ignition (SI) and compression ignition (CI) engines on engine performance and gas emissions was investigated in this study. By adding hydrogen as a fuel in internal combustion engines, the torque, power, and brake thermal efficiency of the engines decrease, while their brake-specific fuel consumption increase. This study suggests that using hydrogen will reduce the emissions of CO, UHC, CO2, and soot; however, NOx emission is expected to increase. Due to the reduction of environmental pollutants for most engines and the related environmental benefits, hydrogen fuel is a clean and sustainable energy source, and its use should be expanded.

The use of insects as a biofuel feedstock has received limited research, and little is known about the fuel characteristics of insect biofuel. Fuel properties characterization can guide researchers focused on renewable fuel for the internal combustion engine. Therefore, this investigation focused on the physical-chemical properties modification of Hermetia illucens larvae oil (HILO) and diesel fuel blends, which could highly become an alternative renewable fuel. Five test fuel blends of HILO and diesel fuel were prepared at 0%, 25%, 50%, 75%, and 100% on a volume basis. Fuel properties such as chemical composition, density, viscosity, heating value, cetane number, and flash point of the test fuel blends were analyzed and compared to the diesel fuel. The main physical-chemical properties of HILO-diesel fuel blends were determined following the ASTM standards. Based on the results, the density, viscosity, cetane number, and flash point of the diesel fuel-HILO fuel blends were increased by 11.28%, 740.30%, 16.92%, and 86.67%, respectively, with the addition of HILO, except for the heating value reduced by 13.66%.

Although water is the second most important fluid, after air, found on the Earth, there is a vital problem in the availability of water for many organisms, and this problem faces the whole world. As a result, scientists have developed many methods of purifying the saline/brackish water to be suitable for different uses in addition to the purpose of drinking. Fortunately, solar distillation is very rewarding in terms of operating costs and costs for a liter of freshwater distillated with using clean and environmentally friendly energy. Solar distiller is one of the solar distillation systems devices, which is simple in construction, cheap, and easy to use but it has the drawback of low productivity. This article aims to provide a summary of the different ideas and works on solar stills through different variables that affect the performance of distillers. In contrast to the review papers dealing with this topic, this paper contains comprehensive and complete details and careful reviews of all the variables that affect the performance of distillers. Therefore, it is like a ladder in front of the authors until they reach the recent of what has been studied on the distillers in a simplified way to save time and effort, which will help them to come up with different ideas that were not easily studied. Thus, this paper introduces an overview on the detailed parameters affecting the performance of solar stills. These parameters are climatic, design, and operating factors. Climatic factors consist of solar radiation, ambient temperature, air speed, and dusty and cloudy weather. While the design factors include the evaporative and exposure surface areas, glazing cover material, inclination, and thickness, distiller material, and of insulating material and thickness. Whist, the operating parameters consist of the water temperature, feed water temperature, applying vacuum, temperature difference between water and glass cover, and hybrid systems. From the extensive literature, it is concluded that the climatic, design, and operating factors significantly affect the performance of the solar still. Finally, some points are proposed for further investigation.

The isomers of butanol have slightly different properties, which can be exploited to improve combustion characteristics. To investigate the potential of this concept, normal-butanol (nB) and iso-butanol (isoB) were blended together in four different ratios (5% of each, 10% of each, and 7% plus 13% of each in both variations, by volume) with conventional diesel. The experimental data were analyzed via analysis of variance to evaluate significant differences between engine parameters. Brake power for the 5% isoB–5% normal-butanol–90% diesel blend was slightly improved while specific fuel consumption was increased with the increase in all dual blends. The high blend ratios of isoB (10% and 13% isoB) produced higher peak in-cylinder pressures and heat release rates as well as a substantial reduction in carbon monoxide emissions. The higher blend ratios of nB (10% and 13% nB) produced much lower unburnt hydrocarbon emissions because the energy required to crack the C–H bonds of nB is less than that required for isoB. Therefore, the hydrocarbons are more easily oxygenated. A slight reduction was found in NOx emissions when increasing either nB or isoB, with nB being slightly more effective. Therefore, a blend of n- and isoB could be a promising alternative to a single isomer additive (iso/nB) to optimize engine performance.

In recent years, biodiesel has been demonstrated to offer a suitable level of reliability and attracted the attention of many researchers. Accordingly, various studies have been carried out to account for the biodiesel production and application, producing valuable reports and findings. In this research study, the effects of biodiesel on engine noise were studied on the basis of a time–frequency analysis. To do so, the acquired acoustic signal was initially filtered and denoised. Then the signal was transferred to the time–frequency SPL domain using short-time Fourier transform. In the A weighted signal, the SPL of all treatments were compared using an innovative visual technique. In this novel approach, the values of area percentages of the obtained SPL in the time–frequency domain were used to compare the propagated noise due to variables. The method revealed a consistent trend for all fuel blends at all engine rotational speeds. The analysis results showed that B10 (10% methyl/ethyl ester and 90% diesel fuel) and B30 had the lowest and highest A-Weighted SPL, respectively. Additionally, it was found that the engine had a maximum sensitivity for all fuel blends at an engine rotation speed of 1600 RPM. Moreover, Z-weighted (linear) signal processing was used to investigate what happens in a complete thermodynamic cycle at 1600 RPM. The developed time–frequency methodology successfully exposed all of the important acoustic events of the engine. The results of this study showed that the most effective acoustic events in engine noise were combustion, piston slap, and outlet valve closing. Furthermore, higher percentages of biodiesel blends resulted in longer combustion duration.

Flat plate solar collectors can easily be termed as the most vastly studied alternative energy transforming and generating technology of the twenty-first century. As the world is racing towards the fourth industrial revolution (Industry 4.0), more and more energy is being consumed for mega projects to be materialized. Electronic devices are not only confined to conventional intermittent and costlier electric energy, but also fuel. Solar energy is now being shared to work smart devices, transform electric energy, and operate automobiles, aeronautics, water heating, and space heating. Traditional flat plate solar collectors can only occupy 50–60% of their thermal efficiency, resulting in less heat generation and a low thermal performance because of using a common absorber made of copper tubing compared to a high conductive metal sheet (copper or aluminum). To ameliorate the thermal efficiency of the solar collector, it is imperative to find a superior alternative heat exchanger that will result in improved thermal performance of the solar collector. In this study, light has been shed in terms of substituting conventional heat absorbers with crystal nano-cellulose (CNC) and a graphene hybrid. An empirical comparison has been drawn by comparing the familiar 0.3% base fluid, 0.5% graphene, and CNC separately, as well as 0.3%, 0.5% CNC, and graphene hybrids at different temperatures. Remarkably, this work has proven that a CNC and graphene hybrid fluid with a volumetric fraction of 0.5% concentration and at a high temperature of 80 °C, gave astounding results for improved thermal conductivity, viscosity, and other parameters. CNC and graphene hybrid nanofluid can be a superior substitute for a conventional base fluid, resulting in prolific thermal performance.

Because of its potential to directly transform solar energy into heat and energy, without harmful environmental effects such as greenhouse gas emissions. Hybrid nanofluid is an efficient way to improve the thermal efficiency of solar systems using a possible heat transfer fluid with superior thermo-physical properties. The object of this paper is the study the latest developments in hybrid applications in the fields of solar energy systems in different solar collectors. Hybrid nanofluids are potential fluids with better thermo-physical properties and heat transfer efficiency than conventional heat transfer fluids (oil, water, ethylene glycol) with single nanoparticle nanofluids. The research found that a single nanofluid can be replaced by a hybrid nanofluid because it enhances heat transfer. This work presented the recent developments in hybrid nanofluid preparation methods, stability factors, thermal improvement methods, current applications, and some mathematical regression analysis which is directly related to the efficiency enhancement of solar collector. This literature revealed that hybrid nanofluids have a great opportunity to enhance the efficiency of solar collector due to their noble thermophysical properties in replace of conventional heat transfer working fluids. Finally, some important problems are addressed, which must be solved for future study.

In recent years, leveraging the amount of energy loss occurring in different fields of human activity has captured the attention of researchers. Harvesting and drying processes can be integrated in order to reduce energy losses. The present research work seeks to pinpoint the association between the harvesting and drying processes as well as to make optimal use of both processes so as to decrease the level of energy loss and apply the renewable energies to the food supply chain. The olive harvesting machine was designed and evaluated, and the olives harvested in the solar dryer were placed in the solar dryer as the input materials. To obtain the evaluation of the experimental tests’ purpose, Mari cultivar was used. Following this trend was the evaluation of the olive harvesting machine and its comparison with the manual harvesting method. Having separated the olives from the tree through use of the harvesting machine designed and made, a solar dryer was used to accommodate the olives in order to make the final examination concerning any damage to olives. Findings of the study indicated up to 92% separation of the olive fruits by the olive harvester. It was also found that there is a 29.47 harvest efficiency for the olive harvester. In addition, evaluation of the solar dryer emphasized that an increase in the temperature and velocity of the inlet air results in a rapid decrease in the olive moisture.

The present study investigated the effect of graphene oxide (GO) nanoparticles, as novel fuel additives, on the engine performance and emission characteristics of a diesel engine. The GO nanoparticles were mixed with B0, B10, and B20 Ailanthus altissima biodiesel blends. The graphene oxide nanoparticles, at concentrations of 30, 60, and 90 ppm, were dispersed into each fuel blend by ultrasonication. Throughout this study, engine testing was performed at a constant speed of 2100 rpm and loads of 0%, 25%, 50%, 75%, and 100%. Performance and emission characteristics, including power, torque, specific fuel consumption (SFC), exhaust gas temperature (EGT), and CO, CO2, unburned-hydrocarbon (UHC), and NOx emissions, were investigated. study revealed that, under the same conditions, most performance characteristics, such as power, torque, and EGT, significantly increased through the addition of GO to fuel blends, while SFC significantly decreased. The GO-nanoparticle additives facilitated significant reductions in CO and UHC emissions (approximately 7–20% and 15–28%, respectively); however, under the same conditions, slight increases in CO2 and NOx emissions (approximately 6–10% and 5–8%, respectively) were observed. On the basis of the experimental results, we conclude that fuel blends composed of nanographene oxide, Ailanthus altissima biodiesel, and diesel can be introduced as environmentally friendly fuels.

In this study, a small dish concentrator with a cylindrical cavity receiver was experimentally investigated as the heat source of a dryer. The system was examined for operation with pure thermal oil and Al2O3/oil nanofluid as the working fluids in the solar system. Moreover, the design, the development, and the evaluation of the dried mint plant are presented in this work. Also, the solar dryer system was simulated by the SolidWorks and ANSYS CFX software. On the other side, the color histogram of the wet and dried mint samples based on the RGB method was considered. The results revealed that the different temperatures of the solar working fluids at the inlet and outlet of the cavity receiver showed similar trend data compared to the variation of the solar radiation during the experimental test. Moreover, it is found that the cavity heat gain and thermal efficiency of the solar system was improved by using the nanofluid as the solar working fluid. Furthermore, the required time for mint drying had decreased by increasing the drying temperature and increasing air speed. The highest drying time was measured equal to 320 min for the condition of the air speed equal to 0.5 m/s and the drying temperature of 30 ���C. A good agreement was observed between the calculated numerical results and measured experimental data. Finally, based on the color histogram of the wet and dried mint samples, it was concluded that intensity amount of the red color of the mint increased with the drying process compared to intensity amount of the red color of the wet mint sample. �� 2019 by the authors.

Environmental, economic and political pressures have driven the interest towards the search of sustainable feedstock for biofuel production. At present, macroalgae (green, brown and red marine seaweed) is getting growing consideration as an alternative resource for sustainable biomass to produce biofuels, biochemical and food. The unique chemical composition and wide variation in the availability create various opportunities and also challenges for bio-based energy production. Recently, numerous studies have taken place in the exploitation of seaweed as carbon sources for the bioethanol production. Thus, this paper attempts to highlight the characteristics, processing techniques and potential applications of the seaweed. The present review also focuses on recent innovative approaches for the sustainable production of bioenergy from seaweed.

Exergy is a quantity of the work potential of energy from a given thermodynamic condition. Unlike energy, exergy can be destroyed, and for gasoline engines, the major source of this destruction is during the combustion process. Therefore, to assess the quality of gasoline engines, the research team examined the effect of inlet temperature and spark timing on chemical, thermo-mechanical and total exergy of fuel using E0, E20, E40, E60 and E85 fuels. Results showed that by advancing the spark timing (20° bTDC), thermo-mechanical exergy has increased but chemical exergy and total exergy have decreased. In addition, advance or delay in spark timing had no effect on the fuel chemical exergy for the compression and expansion strokes. The effect of temperature on exergy parameters indicated that by reducing inlet temperature (320 K), exergy parameters increased. In other words, the fuel chemical exergy at 320 K for E0, E20, E40, E60 and E85 fuels, increased by 7%, 7.1%, 7.2%, 7.2%, 7.3%, respectively, than 350 K and increased by 14%, 14.3%, 14.4%, 14.4% and 14.5% than 380 K.

The increasing energy demand and more stringent legislation for engine pollutant emissions with the use of carbon-neutral fuels have forced to use alcohol. ABE, a combination of acetone, butanol, and ethanol, is a potentially fuel that can be produced from waste biomass via fermentation. Recently, this fuel has attracted researchers’ attention due to its better performance and less emission as a diesel blend when compared to ethanol. First, this article addresses past and recent research conducted in the field of biofuel (ABE) production from lignocellulosic materials. Second, the development in ABE production efficiency is reviewed and various methods of improving ABE production are presented. ABE from lignocellulosic materials (a green energy re- source) can be improved through metabolic engineering of the fermenting yeast (Clostridia) and/or pre-treat- ment techniques. Furthermore, the application of ethanol, butanol and ABE as biofuel blends is compared and summarised considering three aspects (1) combustion characteristics; (2) as an additive blend of diesel fuel in compression engines; and (3) as an additive blend of gasoline in spark ignition engines related to engine per- formance and emission levels. This study shows that ABE has the potential to become an important second-generation biofuel that can be blended with diesel and gasoline for the following reasons: it is cheaper to produce compared to butanol, it is possible to improve engine performance and it reduces exhaust gas emissions. Moreover, engine power is comparable to diesel, and at the same time ABE releases fewer emissions such as CO and NOx than other fuel blends.

Energy security and global warming concern are the two main driving forces for the global alcohol development that also have the effort to animate the agro-industry. Generally, alcohol and ether fuels are produced from several sources and can be produced locally. Almost all alcohol fuels have similar combustion and ignition characteristics to existing known mineral fuels. Mainly the ether fuels (MTBE and DME) are used as additives at low blending ratio to enhance the octane number and oxygen content of gasoline. The addition of alcohol and ether fuels to gasoline lead to a complete combustion due to the higher oxygen content, thereby leads to increased combustion efficiency and decreased engine emissions. The objectives of this paper are to systematically review the use of alcohols and ethers including butanol, methanol, ethanol, and fusel oil, MTBE, and DME as fuels in SI engine. Also, the current study has investigated the effects of performance (brake torque, brake power, BSFC, effective efficiency, and EGT), emissions (CO, CO2, NOx and HC) and combustion characteristics of SI engine with alcohol and ether. The increase in engine performance could be attained with an increased compression ratio along with the use of alcohol fuels which have a higher-octane value. Furthermore, alcohol and ether burn very cleanly than regular gasoline and produce lesser carbon monoxide (CO) and nitrogen oxide (NOx). On the other hand, the energy value of alcohol and ether fuels is approximately 30% lower than gasoline; thereby the specific fuel consumption (SFC) will increase simultaneously when using alcohol and ether as a fuel. Finally, this paper also discusses the impacts of alcohol on engine vibration, engine noise, and potential to be used as a gasoline octane enhancer. Alcohol can be used as a pure fuel in spark ignition engine, but it requires some modifications to the engine.

Local thermal equilibrium (LTE) is a frequently-employed hypothesis when analysing convection heat transfer in porous media. However, investigation of the non-equilibrium phenomenon exhibits that such hypothesis is typically not true for many circumstances such as rapid cooling or heating, and in industrial applications involving immediate transient thermal response, leading to a lack of local thermal equilibrium (LTE). Therefore, for the sake of appropriately conduct the technological process, it has become necessary to examine the validity of the LTE assumption before deciding which energy model should be used. Indeed, the legitimacy of the LTE hypothesis has been widely investigated in different applications and different modes of heat transfer, and many criteria have been developed. This paper summarises the studies that investigated this hypothesis in forced, free, and mixed convection, and presents the appropriate circumstances that can make the LTE hypothesis to be valid. For example, in forced convection, the literature shows that this hypothesis is valid for lower Darcy number, lower Reynolds number, lower Prandtl number, and/or lower solid phase thermal conductivity; however, it becomes invalid for higher effective fluid thermal conductivity and/or lower interstitial heat transfer coefficient.

In recent years, alternative fuel studies have been conducted thoroughly by researchers through their experimental work. Depletion of fossil fuel raised the attention of researchers to investigate renewable energy sources such as biodiesel and alcohol. There is a lack of literature review study on the viability of alcohol acting as additive in biodiesel-diesel fuel blends. Thus, this review paper studies on the effects of various alcohol additives in biodiesel-diesel fuel blends on combustion behaviour, performance and emission characteristics of diesel engines. The physicochemical properties of alcohol and biodiesel are rigorously discussed, in which they are the main factors in determining the quality of the blended fuel. The aim of this paper is to identify the potential of alcohol fuel as an additive in the blended biodiesel and diesel fuel in correspond to the type of alcohol, blending ratio and engine operation conditions. Wide range of results from previous research studies with different types of compression-ignition engine, different engine operation conditions and varieties of alcohol-biodiesel-diesel fuel blending ratios were collected in this literature review study. Combustion behaviour such as coefficient of variations (COV), in-cylinder pressure, ignition delay, heat release rate and combustion duration are presented. Low cetane number and high latent heat of vaporization of alcohol cause a longer ignition delay, produce higher rate of heat release and lower in-cylinder pressure when compared with that of diesel fuel. Low density and viscosity of alcohol improve the spray characteristics and enhance air-fuel mixing process. In terms of engine performance analysis, the presence of oxygen in alcohol fuel promotes a more complete combustion; hence, resulting in an increase of thermal efficiency. In turn, emissions of carbon monoxide (CO), hydrocarbon (HC) and particulate matter (PM) are decreasing.

The main objective of this study is to determine the optimal blend ratio of fusel oil–gasoline before and after water extraction (FBWE10, FBWE20, FAWE10, and FAWE20) regarding the performance and emissions of spark ignition engine using response surface methodology (RSM). The multi-objective optimization is applied to maximize the brake power, brake thermal efficiency and minimize the brake specific fuel consumption (BSFC), NOx emission, HC emission and CO emission. The water content of fusel oil has been extracted by employing rotary extractor method. The experimental of this study has been carried out with different fusel oil–gasoline blends, different throttle valve opening position (15%, 30%, 45% and 60%) and different engine speed (1500, 2500, 3500 and 4500 rpm). All the developed models for responses were determined to be statistically significant at 95% confidence level. The study results reveal an improvement in heating value of fusel oil after water extraction with FAWE20 (80 vol% gasoline fuel, 20 vol% fusel oil after water extracted) as the optimally blended fuel. The best condition of engine parameters with FAWE20 were 55.4% of WOT for load and 4499 rpm engine speed. In additional of the optimal values with a high desirability of 0.707 were 62.511 kW, 241.139 g/kW h, 36%, 1895.913 ppm140.829 ppm and % for brake power, BSFC, BTE, NOx, HC and CO emissions respectively. The reduction of water content in fusel oil has a statistical significance influence to increases BTE, NOx emission and decreases the BSFC, HC and CO emissions.

Microalgae biodiesel has captured the attention as a clean renewable fuel for diesel engines due to their positive characterizations such as high productivity, fast growing rate and their ability to convert CO2 to fuel. This work investigates the use of microalgae biodiesel from Chlorella Protothecoides (MCP-B) as alternative fuel for Compression Ignitions (CI) engines. Engine performance and emissions along with the fuel properties of the MCP-B100, MCP-B50, and MCP-B20 were evaluated and compared with petroleum diesel (PD). Analysis of variance statistical test (ANOVA) was conducted to evaluate the significance of the differences between the parameters means. The results showed that MCP-B100 produces less emission compared to PD. Statistically significant differences were found in the engine brake power, torque, BSFC, exhaust gas temperature, CO, O2 and NOx when MCP-B100 and its blends were used compare to PD. MCP-B100 showed a reduction of 7, 4.9, 6.1, 28, 4.2 and 7.4% in brake power, torque, exhaust gas temperature, CO, CO2 and NOx, respectively. Contrarily, the use of MCP-B100 resulted in an increase of 10.2 and 15.8% in BSFC and O2, respectively compared to PD.

Current estimates for world cotton production are about 25 million tonnes and accounting for 50 million tons of biomass waste. The options for utilising cotton biomass wastes include composting, gasification, pyrolysis, fermentation (ethanol), anaerobic digestion and direct incineration. Solid cotton gin waste cannot be directly reused on-farm due to farm hygiene risks. Composting either on-farm or at the gin is an accepted method for pathogen disinfection and pesticide degradation, although this option may face the problem of small market demand and possible disease concerns. On the other hand, on-farm cotton residues are fundamental for minimising losses in soil carbon, organic carbon content and surface protection. Converting these wastes to energy using various treatments such as gasification, pyrolysis and anaerobic digestion minimises the land required for processing, and the energy produced may offset the much higher capital costs involved. The scope of this study is to examine the size of cotton industry in Australia and the associated by-products produced. The strengths, weaknesses, opportunities and threats of different options for utilising cotton wastes throughout processing were examined. The technical, environmental and economic aspects of each waste management option have formed the basis of our conclusions and recommendations. It seems that pyrolysis of cotton stalks is a good option due to the potential revenue of $104 million dollars. Using cotton gin trash (CGT) for ethanol production is another option, and the average production would be around 33–47 million litres of ethanol for the entire industry. The revenue from this process can be $33–47 million ($1/L). Cotton stalk provides the highest burning efficiency and longest burn time compared to corn stover and soybean residues. The potential amount of energy produced from burning cotton stalks can be around 24.8 PJ which is equivalent to $97 million worth of coal.

As with other regions of Iran, due to excessive extraction of groundwater for intense agricultural activity, Ghorveh plain, a water-scarce irrigation district in the west of Iran, has faced a serious water crisis during the last decade. The present study investigates the impacts of two scenario policies, namely, non-price policy (as a supply-oriented policy) and water pricing policies (as a demand-oriented policy) on agricultural sector of Ghorveh Plain, using positive mathematical programming (PMP). The model was calibrated by using farm-level data for the crop years in 2016&ndash, 2017. Our findings indicate that applying water supply constraint policy will change the land use and cropping pattern to the crops with higher water productivity. The increase of water resource constraints can lead to the increase of water economic return which indicates a rising value of water resources shortage, warning the producers of the agriculture sector to allocate water to the crops with higher economic value under the water resources shortage conditions. In addition, the findings underline that in a situation where the price of irrigation water is low due to the low elasticity of water demand in the agriculture sector, formulating the economic instruments such as rising water prices does not solely suffice to achieve sustainable water resource management. However, mixed scenarios emphasized that the water distribution policies should be aligned with the increases in water cost.

In recent years, due to the favorable climate conditions of Iran, the cultivation of rapeseed has increased significantly. The aim of this study was to investigate the possibility of biodiesel production from one genotype of rapeseed (TERI (OE) R-983). An ultrasonic approach was used in order to intensify the reaction. Response surface methodology (RSM) was applied to identify the optimum conditions of the process. The results of this research showed that the conversion of biodiesel was found to be 87.175% under the optimized conditions of a 4.63:1 molar ratio (methanol to oil), 56.50% amplitude, and 0.4 s pulses for a reaction time of 5.22 min. Increasing the operating conditions, such as the molar ratio from 4:1 to 5.5:1, amplitude from 50% to 72.5%, reaction time from 3 min to 7 min, and pulse from 0.4 s to 1 s, increased the FAME (fatty acid methyl esters) yield by approximately 4.5%, 2.3%, 1.2%, and 0.5%, respectively. The properties of the TERI (OE) R-983 methyl ester met the requirements of the biodiesel standard (ASTM D6751), indicating the potential of the produced biodiesel as an alternative fuel.

In this study, the fuel properties and engine performance of blended palm biodiesel-diesel using diethyl ether as additive have been investigated. The properties of B30 blended palm biodiesel-diesel fuel were measured and analyzed statistically with the addition of 2%, 4%, 6% and 8% (by volume) diethyl ether additive. The engine tests were conducted at increasing engine speeds from 1500 rpm to 3500 rpm and under constant load. Optimization of independent variables was performed using the desirability approach of the response surface methodology (RSM) with the goal of minimizing emissions and maximizing performance parameters. The experiments were designed using a statistical tool known as design of experiments (DoE) based on RSM.

Using renewable oxygenated fuels such as ethanol is a proposed method to reduce diesel engine emission. Ethanol has lower density, viscosity, cetane number and calorific value than petroleum diesel (PD). Microalgae oil is renewable, environmentally friendly and has the potential to replace PD. In this paper, microalgae oil (10%) and ethanol (10%) have been mixed and added to (80%) diesel fuel as a renewable source of oxygenated fuel. The mixture of microalgae oil, ethanol and petroleum diesel (MOE20%) has been found to be homogenous and stable without using surfactant. The presence of microalgae oil improved the ethanol fuel demerits such as low density and viscosity. The transesterification process was not required for oil viscosity reduction due to the presence of ethanol. The MOE20% fuel has been tested in a variable compression ratio diesel engine at different speed. The engine test results with MOE20% showed a very comparable engine performance of in-cylinder pressure, brake power, torque and brake specific fuel consumption (BSFC) to that of PD. The NOx emission and HC have been improved while CO and CO2 were found to be lower than those from PD at low engine speed.

Today, application of cavity receivers in solar concentrator systems is suggested as an interesting and novelty research subject for increasing thermal performance. In this research, a parabolic trough concentrator (PTC) with a rectangular cavity receiver was energetically investigated. The cavity receiver was studied with smooth and corrugated tubes. Different solar heat transfer fluids were considered, including water, air, and thermal oil. The effect of different operational parameters, as well as structural parameters, was investigated. The results showed that the linear rectangular cavity receiver with corrugated tube showed higher amounts of the absorbed heat and energy performance compared to the smooth tube as the cavity tube. Thermal performance of the rectangular cavity was improved using the application of water as the solar heat transfer fluid, which was followed by thermal oil and, finally, air, as the solar heat transfer fluid. Finally, it could be recommended that the rectangular cavity receiver with smooth tube using air as the solar heat transfer fluid is more appropriate for coupling this system with a Bryton cycle, whereas the rectangular cavity receiver with the corrugated tube using water or oil as the solar heat transfer fluid is recommended for achieving higher outlet temperature of the heat transfer fluid.

This research aims to develop an optimal continuous process to produce fatty acid methyl esters (biodiesel) from waste cooking oil using a series of shockwave power reactors. Response surface methodology (RSM) based on central composite design (CCD) was used to design the experiment and to analyze five operating parameters: ratio of rotor diameter to stator diameter (Dr/Ds), ratio of cavity diameter to rotor diameter (Dc/Dr), ratio of cavity depth to gap between rotor and stator (dc/∆r), rotational speed of rotor (N), and Residence time (Tr). The optimum conditions were determined to be Dr/Ds = 0.73, Dc/Dr = 0.06, dc/∆r = 0.50, 25,510.55 rpm rotational speed of rotor, and 30.10 s residence times under this condition. Regarding the results, the most important parameter in shockwave power reactor (SPR) reactors was ratio of rotor diameter to stator diameter (Dr/Ds). The optimum predicted and actual FAME yield was 98.53% and 96.62%, respectively, which demonstrates that RSM is a reliable method for modeling the current procedure.

In the present research work, a neural network model has been developed to predict the exhaust emissions and performance of a compression ignition engine. The significance and novelty of the work, with respect to existing literature, is the application of sensitivity analysis and an artificial neural network (ANN) simultaneously in order to predict the engine parameters. The inputs of the model were engine load (0, 25, 50, 75 and 100%), engine speed (1700, 2100, 2500 and 2900 rpm) and the percent of biodiesel fuel derived from waste cooking oil in diesel fuel (B0, B5, B10, B15 and B20). The relationship between the input parameters and engine cylinder performance and emissions can be determined by the network. The global sensitivity analysis results show that all the investigated factors are effective on the created model and cannot be ignored. In addition, it is found that the most emissions decreased while using biodiesel fuel in the compression ignition engine.

The household sector consumes a large amount of goods and services and is therefore a major source of global carbon emissions. This study aims to analyze per person household carbon emission (HCEs) patterns of urban and rural China over the period from 1995 to 2011. Annual macroeconomic data for the study were obtained from authentic Chinese government sources. Direct HCE estimates for each fossil fuel were obtained using the IPCC’s reference approach, and indirect HCEs were calculated by input-output analysis. In 1995, per person HCEs from direct sources for urban and rural China were 0.50 tCO2 and 0.22 tCO2, respectively, by 2011, these values had increased to 0.60 tCO2 and 0.61 tCO2, an increase of 20% and 177.27%, respectively. Similarly, in 1995, per person HCEs from indirect sources for urban and rural China were 0.43 tCO2 and 0.16 tCO2, respectively, by 2011, these values had increased to 1.77 tCO2 and 0.53 tCO2, respectively, an increase of 306% and 235%. The reasons for these differences and the sets of policies required to rectify increasing emissions are discussed. If current trends and practices continue, with a RMB1000 increase in per capita income from 2011 levels, per person HCEs in urban and rural China will increase by 0.119 tCO2 and 0.197 tCO2, respectively. This result indicates that the sector of society which is most vulnerable will contribute most to China’s increasing HCEs. Therefore, while developing energy consumption and emissions reduction policies and programs, principles of fairness and equity need to be followed.

This paper introduces the resource, status and prospect of solar energy in Iran briefly. Among renewable energy sources, Iran has a high solar energy potential. The widespread deployment of solar energy is promising due to recent advancements in solar energy technologies. Therefore, many investors inside and outside the country are interested to invest in solar energy development. Iran’s total area is around 1600,000 km 2 or 1.6×10 12 m 2 with about 300 clear sunny days in a year and an average 2200 kW-h solar radiation per square meter. Considering only 1% of the total area with 10% system efficiency for solar energy harness, about 9 million MW h of energy can be obtained in a day. The government’s goal on 2012 was to install 53,000 MW capacity plants for electricity generation. To reach this goal, it was assumed that the new gas-fired plants along with the hydroelectric and nuclear power generating plants could be financed by independent power producers including those of foreign investment. Based on the fifth 5 year Socio-economic and Cultural Development Plan, the private sector was expected to have a share of at least 270 MW in renewable energy development. The existing small capacity solar energy plants are in Shiraz, Semnan, Taleghan, Yazd, Tehran and Khorasan. Based on the specified available solar trough technology, solar area, average solar hours and average solar direct irradiation, the technical potential of solar electricity was estimated to be 14.7 TWe. Under the current energy policies, the combined solar, wind and geothermal power plants are economically viable. These huge RES’s potential can be realized assuming the availability of technology, investment capital, human expertise and the other resources along with a long-term driven renewable energy policy. Due to high growth rate of electricity demand in Iran, the nominal installed capacity has increased by 8.9% per annum during 2001–2007. In the reference scenario, the share of RES in total installed electricity capacity is expected to be about 2% in 2030. It is expected that the cumulative RES installed capacity will reach 2.8 GW in 2030. This requires more than 2800 million US dollar investment during 2010–2030.

The performance of a natural gas fueled spark ignition engine was studied to investigate the effect of hydrogen enrichment on the engine operating range and combustion characteristics. A validated multi-dimensional CFD model coupled with detailed chemical kinetics mechanism was used to study the combustion process in Hydrogen/CNG engine. Results indicated that misfiring occurs in equivalence ratios of about 0.61, 0.48 and 0.42 for hydrogen fractions of 0%, 30% and 50% respectively. Also, combustion durations were 70, 47 and 45 degrees crank angle for hydrogen fractions of 0%, 30% and 50% respectively with same equivalence ratio (Ф ¼ 0.625). Regarding the emission, the maximum amount of break specific NOx was detected around Ф ¼ 0.83 (l ¼ 1.2), and this point is almost independent of the hydrogen fraction. It was found that hydrogen fraction decreases the emissions of CO, and HC and CO2. Adding 30% hydrogen reduced CO2 emission by10.2% while 50% hydrogen fraction led to 22.7% CO2 reduction.

This review article addresses wastewater treatment methods in the red meat processing industry. The focus is on conventional chemicals currently in use for abattoir wastewater treatment and energy related aspects. In addition, this article discusses the use of cleaning and sanitizing agents at the meat processing facilities and their effect on decision making in regard to selecting the treatment methods. This study shows that cleaning chemicals are currently used at a concentration of 2% to 3% which will further be diluted with the bulk wastewater. For example, for an abattoir that produces 3500 m3/day wastewater and uses around 200 L (3%) acid and alkaline chemicals, the final concentration of these chemical will be around 0.00017%. For this reason, the effects of these chemicals on the treatment method and the environment are very limited. Chemical treatment is highly efficient in removing soluble and colloidal particles from the red meat processing industry wastewater. Actually, it is shown that, if chemical treatment has been applied, then biological treatment can only be included for the treatment of the solid waste by-product and/or for production of bioenergy. Chemical treatment is recommended in all cases and especially when the wastewater is required to be reused or released to water streams. This study also shows that energy consumption for chemical treatment units is insignificant while efficient compared to other physical or biological units. A combination of a main (ferric chloride) and an aid coagulant has shown to be efficient and cost-effective in treating abattoir wastewater. The cost of using this combination per cubic meter wastewater treated is 0.055 USD/m3 compared to 0.11 USD/m3 for alum and the amount of sludge produced is 77% less than that produced by alum. In addition, the residues of these chemicals in the wastewater and the sludge have a positive or no impact on biological processes. Energy consumption from a small wastewater treatment plant (WWTP) installed to recycle wastewater for a meet facility can be around $500,000.

The problem of slaughterhouse waste water can be resolved by mixing it with serum from lacteal industry to produce a biogas. The effect of serum addition on the anaerobic co-digestion of solid and liquid slaughterhouse waste has been studied. The experimental device consisted of a continuous digester by recirculation of biogas produced in the anaerobic digestion. The input effluent was a mixture of slaughterhouse waste from Badajoz city (Spain) and animal serum in a proportion of 20%. The anaerobic digestion was developed in a complete mixing continuous digester with a capacity of 6.2 L at 37 °C and a feed rate of 350 mL/day. From the results obtained for the co-digestion of the feeding effluent of the slaughterhouse waste, without and with serum added, in the same operating conditions, comparative data about the biological depuration and biogas production have been obtained. A 10 L biogas production was obtained with the slaughterhouse waste and 18 L with the slaughterhouse waste with serum added. In conclusion, the highest energetic yield (97.52% higher) was obtained in the second case, due to the positive action of catalytic enzymes present in the animal serum.

A series of activated carbons were prepared by physical steam gasification under identical experimental conditions to compare the pore development from almond tree pruning chars and walnut shell activated carbons. The results obtained showed that steam gasification yields microporous carbons in both cases, and the rise in temperature causes an increase of the pore volumes of the activated carbons, up to a certain degree of burn-off. This effect was more marked for walnut shell, which gave rise to activated carbons with apparent surface values of up to 1434 m2 g−1. Also, a slight widening of porosity was found at low burn-off degrees. This pore widening was more marked in the case of activated carbons from almond tree pruning, which also have a high macropore volume. It was found that the lignocellulosic and porosity properties of the raw materials can cause this different behavior towards activation processes.

This research investigates ethanol production from waste lignocellulosic material (sugarcane bagasse). The bagasse was first pretreated using chemicals and ultrasound techniques. These pretreatment techniques were applied separately and combined. The pretreated bagasse was then fermented anaerobically for biofuel production without enzymatic hydrolysis. The results showed higher ethanol production than those reported in the literature. The maximum ethanol production of 820 mg/L was achieved with a combination of ultrasound (60 amplitude level, 127 W) and acid (3% H2SO4 concentration). The combination of two-step pretreatment such as an ultrasound (50 amplitude level, 109 W) with acid (3% H2SO4 concentration) and then an ultrasound with alkaline (23% NaOH concentration) generated 911 mg/L of ethanol.

Homogeneous charge compression ignition (HCCI) engine uses a relatively new mode of combustion technology. In principle, there is no spark plug or injector to assist the combustion, and the combustion auto-ignites in multiple spots once the mixture has reached its chemical activation energy. The challenges in developing HCCI engines are the difficulties in: controlling the auto-ignition of the mixture and the heat release rate at high load operations, achieving a cold start, meeting emission standards and controlling knock. At low engine speeds, early auto-ignition can occur, possibly leading to knocking, while late auto-ignition at high engine speeds will make HCCI susceptible to misfire. Hydrogen greatly reduces emissions levels but with reduced power. However, when hydrogen is combined with diesel in dual-fuel mode, low NOx, CO and particulate matter (PM) emissions levels can be achieved, and engine efficiency can be increased by 13–16%. Numerical methods are commonly used to predict HCCI engines' performance (i.e. emissions levels, brake thermal efficiency and combustion phasing), which is cost-effective compared to solely relying on experimentation. The multi-zone method promises better simulation results compared to the single-zone model by combining detailed chemical kinetics with simplified 3D modeling so that turbulence and inhomogeneity in the mixture are considered; good agreement between simulations and experiments have been achieved. Specific strategies used in the experimental method (e.g. fuel additives, inlet air heating, inlet air pressurizing, exhaust gas recirculation (EGR) and injection methods), and numerical method (e.g. single-zone and multi-zone models, mixing model, turbulence model and multi-dimensional model), and other issues associated with HCCI engines are discussed in this paper.