Biodiesel production from fryer grease

Biodiesel is a renewable, biodegradable, environmentally benign fuel for use in the diesel engines. It can be produced from renewable sources such as vegetable oils or animal fats. Although this fuel has gained worldwide recognition for many years, it is not being widely commercialized mainly because it is more expensive than petroleum diesel. A cheaper feedstock, such as fryer grease, may be used to improve the economics of biodiesel. Methanol is the most common alcohol used in the transesterification process due to its low cost. However, recently, ethanol has been promoted as an alcohol for use in transesterification since it can be produced from renewable resources such as switchgrass, corn and wood, thereby reducing the dependency on petroleum sources (Pimentel and Patzek, 2005). A mixture of methanol and ethanol is hypothesized to take the advantages of both methanol and ethanol. The present work is focused on the production of biodiesel from fryer grease via transesterification with various mixtures of methanol and ethanol. Also, the kinetics of transesterification from fryer grease was studied. Since fryer grease contains a high concentration of free fatty acids (FFA) (5.6 wt. %) and water (7.3 wt. %), a two-step acid/alkaline transesterification process was used to produce the esters. Sulfuric acid and potassium hydroxide were used as acid and alkaline catalysts, respectively. The methanol to ethanol molar ratio was varied from 3:3 to 5:1, whereas alcohol to oil molar ratio was maintained at 6:1. After the fryer grease was transesterified, all esters met ASTM standard D-6751. The viscosity of these esters ranged from 4.7 to 5.9 mm2/s. The heating value of the esters was approximately 10% less than that of petroleum diesel. The cloud point and pour point were in the range of 1 to -1 oC and -3 to -6 oC, respectively. When the mixed alcohol was used ethyl esters were also formed at a lower concentration along with methyl esters. The dominant fatty acid in fryer grease esters was found to be oleic acid. The lubricity of kerosene fuel was improved by as much as 33 % through the addition of these esters at rates as low as 1 %. For the kinetic study of alkali-catalyzed transesterification of fryer grease, the alcohol to oil molar ratio, the reaction temperature, and the catalyst loading were varied as 6:1, 9:1, 12:1; 30, 40, 50 oC; and 0.5, 1.0, 1.5 %, respectively. The ester concentration was found to rise with an increase in the catalyst loading or the reaction temperature and with a decrease in the alcohol to oil molar ratio. The overall forward and backward reaction orders were assumed to follow first and second order kinetics, respectively. The kinetic parameters were calculated using MATLAB. The conversion of triglyceride to diglyceride was found to be the rate determining step (RDS) of the overall reaction, with an activation energy of 36.9 kJ/mol

Development of Biodiesel Production Processes from Various Vegetable Oils

Biodiesel is an alternative fuel to petroleum diesel that is renewable and creates less harmful emissions than conventional diesel thus the use of this fuel is a shift toward “sustainable energy”. Biodiesel can be produced from vegetable oil, animal fat, and organisms such as algae or cyanobacteria. Since vegetable oils are the major source for current commercial biodiesel, they are the focus of this thesis. The main objective of this Ph.D. research is to develop processes suitable to produce biodiesel from various vegetable oils especially for those of non-edible oils such as used cooking oil, canola oil from greenseed, and mustard oil. An additional objective is to understand the relationship between the parent vegetable oils and the corresponding biodiesel properties. Used cooking oil was the first vegetable oil investigated in this research. Initially, oil degradation behavior was monitored closely during frying. During 72 hours of frying, acid value and viscosity of the oil increased from 0.2 to 1.5 mgKOH•g-1 and from 38.2 to 50.6 cP, respectively. It was found that ester yield was improved by addition of canola oil to used cooking oil, i.e. addition of 20% canola oil to used cooking oil increased methyl ester yield and ethyl ester yield by 0.5% and 12.2%, respectively. At least 60% canola oil addition is needed to produce ASTM grade ethyl ester biodiesel. The optimum reaction conditions to produce biodiesel are 1% KOH loading, 6:1 alcohol to oil ratio, 600 rpm stirring speed, and either 50°C reaction temperature for 2 hr or 60°C reaction temperature for 1.5 hr for methanolysis and 60°C reaction temperature for 2 hr for ethanolysis. Among non-edible vegetable oils, greenseed canola oil can be used in the most simple biodiesel production process. In this case, an addition of fresh vegetable oil is not required, because chlorophyll contained in this oil did not play a crucial role in the reaction activity. Methyl ester yields derived from greenseed canola oil without and with 94.1 ppm chlorophyll content are 95.7% and 94.8%, respectively. In contrast, erucic acid contained in mustard oil created difficulties in the production process. Ester yield derived from mustard oil using the conditions mentioned above was only 66% due to the present of unconverted monoglyceride. To obtain a deeper understanding on mustard oil transesterification, its reaction kinetics was studied. In the kinetic study, transesterification kinetics of palm oil was also investigated to study the effect of fatty acid chain length and degree of saturation on the rates of the reactions. It is shown in this research that the rates of mustard monoglyceride transesterification (rate constant = 0.2-0.6 L•mol-1•min-1) were slower that those of palm monoglyceride transesterification (rate constant = 1.2-4.2 L•mol-1•min-1) due to its lower molecular polarity resulting from the longer chain of erucic acid. The activation energy of the rate determining step (in this case, conversion of triglyceride to diglyceride reaction step) of mustard transesterification was, however, 26.8 kJ•mol-1, which is similar to those of other vegetable oils as reported in literature. Despite the presence of unconverted monoglyceride, distillation can be used to obtain a high purity ester. Several ester properties are determined by characteristics of the parent oil and choice of alcohol used in transesterification. Chlorophyll contained in greenseed canola oil, for example, has an adverse effect on biodiesel oxidative stability. The induction time for methyl ester derived from treated greenseed canola oil (pigment content = 1 ppm) was enhanced by 12 minutes compared to that derived from crude greenseed canola oil (pigment content = 34 ppm). The optimum bleaching process involves the use of 7.5 wt.% montmorillonite K10 at 60°C and stirring speed of 600 rpm for 30 minutes. In addition, it was found that induction time of treated greenseed canola ethyl ester (1.8 hr) was higher than that of methyl ester (0.7 hr), which suggests a better oxidative stability of esters of higher alcohols. Furthermore, the use of higher alcohols instead of methanol produced materials with improved low temperature properties. For example, the crystallization temperatures of monounsaturated methyl, ethyl, propyl, and butyl esters prepared from mustard oil were -42.5°C, -51.0°C, -51.9°C, and -58.2°C, respectively. In contrast, the lubricity of biodiesel is mainly provided by its functional group which is COOCH3 for methyl ester. The use of higher alcohols in transesterification results in a less polar functional group in the corresponding ester molecule, which leads to reduction in ester lubricity. Methyl ester provided the highest lubricity among all esters produced, i.e. wear reduction at 1% treat rate of methyl ester, ethyl ester, propyl ester, and butyl ester are 43.7%, 23.2%, 30.7% and 30.2%, respectively. The outcomes of this research have been published in several scientific journals and presented at national and international conferences. The published articles and conference presentations are listed at the beginning of each chapter in this thesis

Intelligent Intrusion Detection of Grey Hole and Rushing Attacks in Self-Driving Vehicular Networks

Vehicular ad hoc networks (VANETs) play a vital role in the success of self-driving and semi self-driving vehicles, where they improve safety and comfort. Such vehicles depend heavily on external communication with the surrounding environment via data control and Cooperative Awareness Messages (CAMs) exchanges. VANETs are potentially exposed to a number of attacks, such as grey hole, black hole, wormhole and rushing attacks. This work presents an intelligent Intrusion Detection System (IDS) that relies on anomaly detection to protect the external communication system from grey hole and rushing attacks. These attacks aim to disrupt the transmission between vehicles and roadside units. The IDS uses features obtained from a trace file generated in a network simulator and consists of a feed-forward neural network and a support vector machine. Additionally, the paper studies the use of a novel systematic response, employed to protect the vehicle when it encounters malicious behaviour. Our simulations of the proposed detection system show that the proposed schemes possess outstanding detection rates with a reduction in false alarms. This safe mode response system has been evaluated using four performance metrics, namely, received packets, packet delivery ratio, dropped packets and the average end to end delay, under both normal and abnormal conditions

Availability and End-to-end Reliability in Low Duty Cycle Multihop Wireless Sensor Networks

A wireless sensor network (WSN) is an ad-hoc technology that may even consist of thousands of nodes, which necessitates autonomic, self-organizing and multihop operations. A typical WSN node is battery powered, which makes the network lifetime the primary concern. The highest energy efficiency is achieved with low duty cycle operation, however, this alone is not enough. WSNs are deployed for different uses, each requiring acceptable Quality of Service (QoS). Due to the unique characteristics of WSNs, such as dynamic wireless multihop routing and resource constraints, the legacy QoS metrics are not feasible as such. We give a new definition to measure and implement QoS in low duty cycle WSNs, namely availability and reliability. Then, we analyze the effect of duty cycling for reaching the availability and reliability. The results are obtained by simulations with ZigBee and proprietary TUTWSN protocols. Based on the results, we also propose a data forwarding algorithm suitable for resource constrained WSNs that guarantees end-to-end reliability while adding a small overhead that is relative to the packet error rate (PER). The forwarding algorithm guarantees reliability up to 30% PER

RITA: RIsk-aware Trust-based Architecture for collaborative multi-hop vehicular communications

This is the pre-peer reviewed version of the following article: Kerrache, C. A., Calafate, C. T., Lagraa, N., Cano, J. C., & Manzoni, P. (2016). RITA: RIsk‐aware Trust‐based Architecture for collaborative multi‐hop vehicular communications. Security and Communication Networks, 9(17), 4428-4442, which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1002/sec.1618/abstractTrust establishment over vehicular networks can enhance the security against probable insider attackers. Regrettably, existing solutions assume that the attackers have always a dishonest behavior that remains stable over time. This assumption may be misleading, as the attacker can behave intelligently to avoid being detected. In this paper, we propose a novel solution that combines trust establishment and a risk estimation concerning behavior changes. Our proposal, called risk-aware trust-based architecture, evaluates the trust among vehicles for independent time periods, while the risk estimation computes the behavior variation between smaller, consecutive time periods in order to prevent risks like an intelligent attacker attempting to bypass the security measures deployed. In addition, our proposal works over a collaborative multi-hop broadcast communication technique for both vehicle-to-vehicle and vehicle-to-roadside unit messages in order to ensure an efficient dissemination of both safety and infotainment messages. Simulation results evidence the high efficiency of risk-aware trust-based architecture at enhancing the detection ratios by more than 7% compared with existing solutions, such as T-CLAIDS and AECFV, even in the presence of high ratios of attackers, while offering short end-to-end delays and low packet loss ratios.This work was partially supported by both the Ministerio de Economia y Competitividad, Programa Estatal de Investigacion, Desarrollo e Innovacion Orientada a los Retos de la Sociedad, Proyectos I+D+I 2014, Spain, under Grant TEC2014-52690-R, and the Ministere de l'enseignement superieur et de la recherche scientifique, Programme National Exceptionnel P.N.E 2015/2016, Algeria.Kerrache, CA.; Tavares De Araujo Cesariny Calafate, CM.; Lagraa, N.; Cano Escribá, JC.; Manzoni, P. (2016). RITA: RIsk-aware Trust-based Architecture for collaborative multi-hop vehicular communications. Security and Communication Networks. 9(17):4428-4442. https://doi.org/10.1002/sec.1618S4428444291

Energy-aware simulation with DVFS

International audienceIn recent years, research has been conducted in the area of large systems models, especially distributed systems, to analyze and understand their behavior. Simulators are now commonly used in this area and are becoming more complex. Most of them provide frameworks for simulating application scheduling in various Grid infrastructures, others are specifically developed for modeling networks, but only a few of them simulate energy-efficient algorithms. This article describes which tools need to be implemented in a simulator in order to support energy-aware experimentation. The emphasis is on DVFS simulation, from its implementation in the simulator CloudSim to the whole methodology adopted to validate its functioning. In addition, a scientific application is used as a use case in both experiments and simulations, where the close relationship between DVFS efficiency and hardware architecture is highlighted. A second use case using Cloud applications represented by DAGs, which is also a new functionality of CloudSim, demonstrates that the DVFS efficiency also depends on the intrinsic middleware behavior

Adaptive multi-polling scheduler for QoS support of video transmission in IEEE 802.11e WLANs

The 802.11E Task Group has been established to enhance quality of service (QoS) provision for time-bounded services in the current IEEE 802.11 medium access control protocol. The QoS is introduced throughout hybrid coordination function controlled channel access (HCCA) for the rigorous QoS provision. In HCCA, the station is allocated a fixed transmission opportunity (TXOP) based on its TSPEC parameters so that it is efficient for constant bit rate streams. However, as the profile of variable bit rate traffics is inconstant, they are liable to experience a higher delay especially in bursty traffic case. In this paper, we present a dynamic TXOP assignment algorithm called adaptive multi-polling TXOP scheduling algorithm (AMTXOP) for supporting the video traffics transmission over IEEE 802.11e wireless networks. This scheme invests a piggybacked information about the size of the subsequent video frames of the uplink streams to assist the hybrid coordinator accurately assign the TXOP according to actual change in the traffic profile. The proposed scheduler is powered by integrating multi-polling scheme to further reduce the delay and polling overhead. Extensive simulation experiments have been carried out to show the efficiency of the AMTXOP over the existing schemes in terms of the packet delay and the channel utilization

Enabling connectivity for tactical networks in mountainous areas by aerial relays

A general modeling framework for realistic performance evaluations of tactical mobile ad-hoc networks deployed in mountainous areas is presented. The framework is easily extensible, and can be eventually automated. It can be also used to generate data for other network simulators. The framework utilizes the freely downloadable high resolution 3D terrain data to define time dependent trajectories of network nodes. The node speeds and directions are linked to the terrain profile which extends the previously proposed mobility models. The path-loss analysis along the node trajectories revealed the need for aerial relays to enable full network connectivity at all times. The network consisting of 5 cluster heads and a single stationary relay is considered as a case study. The relay location and its antenna height are optimized to achieve the line-of-sight connectivity over the whole mission duration. The antenna radiation pattern at the relay is incorporated in the analysis. The resulting star network topology is used by the cluster heads to broadcast their packets to all other cluster heads. Several relaying schemes including the amplify-and-forward and the decode-and-forward relaying are studied together with the go-back-N retransmissions to achieve the reliable data transfer