Recent development in the production of third generation biodiesel from microalgae

© 2019 The Authors. Published by Elsevier Ltd. Increasing global energy demand at a rate faster than the population growth has led the researcher to look for alternative fuel. Amongst the options, biodiesel is an environmentally sustainable substitute of diesel fuel being renewable, biodegradable and have similar properties of fossil diesel. Among the biodiesel sources, microalgae is a potential third generation biodiesel feedstock which can be produced throughout the year and its oil yield is higher than any other crops. This paper reviews recent development in microalgae biodiesel in terms of its oil extraction technics, challenges of oil extraction, production of biodiesel from microalgae oil and its fuel properties. Finally, the paper discusses the performance and combustion analysis of diesel engine fuelled with microalgae biodiesel. This paper provides a clear understanding of the potential use of microalgae biodiesel as an alternative source to fossil diesel for diesel engines

Exergy analysis of a diesel engine with waste cooking biodiesel and triacetin

This study uses the first and second laws of thermodynamics to investigate the effect of 18 oxygenated fuels on the quality and quantity of energy in a turbo-charged, common-rail six19 cylinder diesel engine. This work was performed using a range of fuel oxygen content based 20 on diesel, waste cooking biodiesel, and a triacetin. The experimental engine performance and 21 emission data was collected at 12 engine operating modes. Energy and exergy parameters were 22 calculated, and results showed that the use of oxygenated fuels can improve the thermal 23 efficiency leading to lower exhaust energy loss. Waste cooking biodiesel (B100) exhibited the 24 lowest exhaust loss fraction and highest thermal efficiency (up to 6% higher than diesel). 25 Considering the exergy analysis, lower exhaust temperatures obtained with oxygenated fuels 26 resulted in lower exhaust exergy loss (down to 80%) and higher exergetic efficiency (up to 27 10%). Since the investigated fuels were oxygenated, this study used the oxygen ratio (OR) 28 instead of the equivalence ratio to provide a better understanding of the concept. The OR has 29 increased with decreasing engine load and increasing engine speed. Increasing the OR 30 decreased the fuel exergy, exhaust exergy and destruction efficiency. With the use of B100, 31 there was a very high exergy destruction (up to 55%), which was seen to decrease with the 32 addition of triacetin (down to 29%)

Massive stars as thermonuclear reactors and their explosions following core collapse

Nuclear reactions transform atomic nuclei inside stars. This is the process of stellar nucleosynthesis. The basic concepts of determining nuclear reaction rates inside stars are reviewed. How stars manage to burn their fuel so slowly most of the time are also considered. Stellar thermonuclear reactions involving protons in hydrostatic burning are discussed first. Then I discuss triple alpha reactions in the helium burning stage. Carbon and oxygen survive in red giant stars because of the nuclear structure of oxygen and neon. Further nuclear burning of carbon, neon, oxygen and silicon in quiescent conditions are discussed next. In the subsequent core-collapse phase, neutronization due to electron capture from the top of the Fermi sea in a degenerate core takes place. The expected signal of neutrinos from a nearby supernova is calculated. The supernova often explodes inside a dense circumstellar medium, which is established due to the progenitor star losing its outermost envelope in a stellar wind or mass transfer in a binary system. The nature of the circumstellar medium and the ejecta of the supernova and their dynamics are revealed by observations in the optical, IR, radio, and X-ray bands, and I discuss some of these observations and their interpretations.Comment: To be published in " Principles and Perspectives in Cosmochemistry" Lecture Notes on Kodai School on Synthesis of Elements in Stars; ed. by Aruna Goswami & Eswar Reddy, Springer Verlag, 2009. Contains 21 figure

Confining Domains Lead to Reaction Bursts: Reaction Kinetics in the Plasma Membrane

Confinement of molecules in specific small volumes and areas within a cell is likely to be a general strategy that is developed during evolution for regulating the interactions and functions of biomolecules. The cellular plasma membrane, which is the outermost membrane that surrounds the entire cell, was considered to be a continuous two-dimensional liquid, but it is becoming clear that it consists of numerous nano-meso-scale domains with various lifetimes, such as raft domains and cytoskeleton-induced compartments, and membrane molecules are dynamically trapped in these domains. In this article, we give a theoretical account on the effects of molecular confinement on reversible bimolecular reactions in a partitioned surface such as the plasma membrane. By performing simulations based on a lattice-based model of diffusion and reaction, we found that in the presence of membrane partitioning, bimolecular reactions that occur in each compartment proceed in bursts during which the reaction rate is sharply and briefly increased even though the asymptotic reaction rate remains the same. We characterized the time between reaction bursts and the burst amplitude as a function of the model parameters, and discussed the biological significance of the reaction bursts in the presence of strong inhibitor activity

Influence of second generation biodiesel on engine performance, emissions, energy and exergy parameters

Nabi, M ORCiD: 0000-0002-4087-930X; Rasul, M ORCiD: 0000-0001-8159-1321The present study compares diesel engine performance, emissions, energy and exergy parameters of three non-edible biodiesels blends and a reference diesel. The three biodiesel blends were prepared so as to keep the blend oxygen percentage at around 3.3 wt%. Considering the economy and availability, waste cooking and macadamia (Macadamia integrifolia) biodiesels were chosen for all the engine experiments. A commercial diesel was used as a reference fuel to compare the performance and emissions with those of the biodiesel blends. To keep the oxygen percentage of the blends approximately the same as for the reference diesel, around 30% waste cooking biodiesel was added to 70% reference diesel to make the first blend. Similarly, around 30% macadamia biodiesel was mixed with 70% reference diesel to make the second blend. In addition, 10% macadamia biodiesel and 20% waste cooking biodiesel were mixed with the 70% reference diesel to make the third blend with similar oxygen content. The macadamia blend is designated as MaD, the waste cooking blend is termed WcD, and the blend with macadamia and waste cooking biodiesel is abbreviated as MaWcD. This study aimed to investigate the influence of the fuel-oxygen on engine performance, emissions, energy and exergy parameters. A well-instrumented, 4-cylinder, 4-stroke, naturally aspirated direct injection (DI) diesel engine was used for the experiments. The engine was loaded and coupled with an eddy current dynamometer. Performance, emissions, energy and exergy parameters for the three biodiesel blends were compared with those of the reference diesel. Without significant reduction in engine performance, a significant reduction in total unburnt hydrocarbon (THC), carbon monoxide (CO), and particulate matter (PM) emissions with a penalty of increased nitrogen oxides (NOx) emissions were realised with all three biodiesel blends. © 2018 Elsevier LtdAssociated Grant:The current investigation was supported by funding from the Deputy Vice Chancellor Research (DVCR), Central Queensland University

Corrigendum to “Influence of second generation biodiesel on engine performance, emissions, energy and exergy parameters” [Energy Convers. Manage. 169 (2018) 326–333](S0196890418305430)(10.1016/j.enconman.2018.05.066)

Nabi, M ORCiD: 0000-0002-4087-930X; Rasul, M ORCiD: 0000-0001-8159-1321© 2018 Elsevier Ltd The authors regret Original Fig. 11 caption was “Fig. 11. Variations of exergetic efficiency with four fuels”, which needs to be changed to “Fig. 11. Variations of in-cylinder pressure with four fuels.” Original Fig. 12 caption was “Fig. 12. Variations of exergetic efficiency with four fuels”, which needs to be changed to “Fig. 12. Variations of RoHR with four fuels.” The authors would like to apologise for any inconvenience caused

Model development for performance analysis of a spark ignition engine fueled with propane and octane

Nabi, M ORCiD: 0000-0002-4087-930X© 2017 IEEE. The main objective of this study was to develop a model for performance analysis of a spark ignition engine fueled with propane and octane. GT-Suite software was used to develop the model for a single cylinder 4-stroke gasoline engine having a bore of 85 mm and a stroke of 85 mm with a capacity of 0.48 litres. A one-dimensional gas dynamics was considered for heat transfer model development for different engine components. Different sub models including flow in the intake and exhaust system, port fuel injection, throttle, combustion, heat and energy transfer were combined to produce different engine performance parameters. The model was run for 12 different rotational speeds ranging from 500 rpm to 6000 rpm at a wide open throttle position. The influence of compression ratio of 8 to 10 for the port fuel injection on different engine performance parameters was also investigated in this study. It was found that propane has a considerable potential to be an alternative fuel for a gasoline engine

Biodiesel from cotton seed oil and its effect on engine performance and exhaust emissions

The use of biodiesel is rapidly expanding around the world, making it imperative to fully understand the impacts of biodiesel on the diesel engine combustion process and pollutant formation. Biodiesel is known as the mono-alkyl-esters of long chain fatty acids derived from renewable feedstocks, such as, vegetable oils or animal fats, for use in compression ignition engines. Different parameters for the optimization of biodiesel production were investigated in the first phase of this study, while in the next phase of the study performance test of a diesel engine with neat diesel fuel and biodiesel mixtures were carried out. Biodiesel was made by the well known transesterification process. Cottonseed oil (CSO) was selected for biodiesel production. Cottonseed is non-edible oil, thus food versus fuel conflict will not arise if this is used for biodiesel production. The transesterification results showed that with the variation of catalyst, methanol or ethanol, variation of biodiesel production was realized. However, the optimum conditions for biodiesel production are suggested in this paper. A maximum of 77% biodiesel was produced with 20% methanol in presence of 0.5% sodium hydroxide. The engine experimental results showed that exhaust emissions including carbon monoxide (CO) particulate matter (PM) and smoke emissions were reduced for all biodiesel mixtures. However, a slight increase in oxides of nitrogen (NOx) emission was experienced for biodiesel mixtures. © 2008 Elsevier Ltd. All rights reserved

The effect of triacetin as a fuel additive to waste cooking biodiesel on engine performance and exhaust emissions

This study investigates the effect of oxygenated fuels on engine performance and exhaust emission under a custom cycle using a fully instrumented 6-cylinder turbocharged diesel engine with a common railinjection system. A range of oxygenated fuels based on waste cooking biodiesel with triacetin as an oxygenated additive were studied. The oxygen ratio was used instead of the equivalence ratio, or air to fuelratio, to better explain the phenomena observed during combustion. It was found that the increased oxygen ratio was associated with an increase in the friction mean effective pressure, brake specific fuel consumption, CO, HC and PN. On the other hand, mechanical efficiency, brake thermal efficiency, CO2, NOx and PM decreased with oxygen ratio. Increasing the oxygen content of the fuel was associated with a decrease in indicated power, brake power, indicated mean effective pressure, brake mean effective pressure, friction power, blow-by, CO2, CO (at higher loads), HC, PM and PN. On the other hand, the brakespecific fuel consumption, brake thermal efficiency and NOx increased by using the oxygenated fuels. Also, by increasing the oxygen content, the accumulation mode count median diameter moved toward the smaller particle sizes. In addition to the oxygen content of fuel, the other physical and chemical properties of the fuels were used to interpret the behavior of the engine

Diesel engine emissions with oxygenated fuels: A comparative study into cold-start and hot-start operation

As biofuels are increasingly represented in the fuel market, the use of these oxygenated fuels should be evaluated under various engine operating conditions, such as cold-start. However, to-date quantification has been mostly done under hot-start engine operation. By using a custom test designed for this study, a comparative investigation was performed on exhaust emissions during cold- and hot-start with diesel and three oxygenated fuels based on waste cooking biodiesel and triacetin. This study used a six-cylinder, turbocharged, after-cooled diesel engine with a common rail injection system. The results during cold-start with diesel showed lower NOx (up to 15.4%), PN (up to 48%), PM1 (up to 44%) and PM2.5 (up to 63%). However, the oxygenated fuels during cold-start showed a significant increase in NOx (up to 94%), PN (up to 27 times), PM1 (up to 7.3 times) and PM2.5 (up to 5 times) relative to hot-start. The use of oxygenated fuels instead of diesel during hot-start decreased the PN, PM2.5 and PM1 (up to 91%) while, during cold-start, it only decreased PM1 and PM2.5 at some engine operating modes and increased PN significantly up to 17 times. In both cold- and hot-start, the use of oxygenated fuels resulted in an increase in NOx emission. For cold-start this was up to 125%, for hot-start it was up to 13.9%. In comparison with hot-start, the use of oxygenated fuels during cold-start increased nucleation mode particles significantly, which are harmful. This should be taken into consideration, since cold-start operation is an inevitable part of the daily driving schedule for a significantly high portion of vehicles, especially in cities