Biodiesel production,characterization, and performance: A hands-on project for first-year students

Biodiesel fuel production and use has been used as the focal point of a semester-long, project-based introductory engineering course at Rowan University. Students worked in teams to conduct a series of laboratory investigations through which they explored the engineering aspects of biodiesel production and purification, properties characterization, quality control and performance testing. The experiments were designed to be cost–effective and transferrable.The laboratory experiments were conducted within the How People Learn framework. An assessment instrument was used as a pre- and post-evaluation method to assess learning outcomes. Students’ gained significantly in learning outcomes areas related to the application of mathematics, science and engineering principles; designing and conducting experiments; analyzing and interpreting experimental data, and solving engineering problems.     

Differential Scanning Calorimetric Study of Solidification Behavior of Monoacylglycerols to Investigate the Cold-Flow Properties of Biodiesel

Monoacylglycerols (MAG) are impurities present in biodiesel as a result of incomplete reactions. MAG often solidify in biodiesel even at room temperature because of their high melting points. This worsens the cold-flow properties such as the cloud point and pour point. We hypothesized that several types of MAG solidify simultaneously; therefore, we performed differential scanning calorimetry of binary mixtures of MAG to elucidate their interactions during solidification. Three thermodynamic formulas were then applied to the experimental results: (1) non-solid-solution, (2) solid-solution, and (3) compound formation models. Binary mixtures of MAG showed complicated liquidus curves with multiple upward convex shapes, with which only the compound formation model fitted well. This model was applied to multicomponent mixtures that consisted of MAG and fatty acid methyl esters (FAME) as surrogate biodiesel fuels. We confirmed that the model still worked well. The results show that the compound formation model has good potential for predicting the cold-flow properties of biodiesel.     

Continuous production of palm methyl esters

A system for continuous transesterification of palm oil was developed using a continuous stirred-tank reactor (CSTR) and pumps for continuous delivery of oil and catalyst and for continuous removal of product. Potassium hydroxide was used as the catalyst, the methanol-to-oil molar ratio was 6∶1, and reaction temperature was 60°C. The yield of methyl esters increased from 58.8% of theoretical yield at a residence time of 40 min to 97.3% at a residence time of 60 min. However, higher residence times decreased the production rate. During long-term continuous operation, the CSTR displayed steady state conditions in terms of product profile and methyl ester concentration. This process has good potential in the manufacture of biodiesel.     

Evaluation and Predictive Model Development of Oxidative Stability of Biodiesel on Storage

Biodiesel comprises mono-alkyl esters of long-chain fatty acid methyl esters (FAME) derived from a renewable lipid feedstock. A major technical issue with the use of biodiesel is that it is more prone to oxidation during storage, when compared to petroleum fuel, due to the high content of polyunsaturated methyl esters that are easily oxidizable to compounds such as acids, aldehydes, and alcohols. Biodiesel (Jatropha and Pongamia) and antioxidants (Turmeric and butylated hydroxytoulene) were used for this study. We found that the acid value and viscosity for pongamia biodiesel increased significantly by 41.17% and 44.0% and that for jatropha biodiesel increased by 31.5% and 37.0%, respectively, after being stored for 3 months. The impact of antioxidants on the storage stability of biodiesel was examined according to the ASTM D4625 12-week procedure, and best results were found at a concentration level of 2500 ppm. The specific objective of this investigation is to develop models to determine the viscosity of biodiesel at any time “t” during long-term storage based on these experimental trials for upto 12 weeks. In addition, the models were used to predict the level of antioxidants that are to be added to biodiesel in order to minimize the effects of oxidative degradation during storage. The developed model recorded an adjusted R² of 0.86 and a modeling efficiency of 0.88.     

Experimental Fuzzy/Split-Range Control: Novel Strategy for Biodiesel Batch Reactor Temperature Control

With respect to environmental concerns, biofuels have been used around the world, such as biodiesel, and any improvement in the biodiesel production process is desirable. This paper proposes three different control systems based on fuzzy logic and output control signal split-range. Regulating reaction temperature with low settling time and process variable oscillation are the process control aims, and smooth output control signal for actuators protection is also desired. An automated biodiesel production prototype was used and the experimental results demonstrate that a fuzzy/split-range structure with three input variables showed the best performance, resulting in process variable regulation in set-point value with small settling time and actuators premature wearing prevention.     

Mass transfer simulation of biodiesel synthesis in microreactors

A coupled nonlinear mathematical model for the mass transfer of the species involved in the transesterification reaction between soybean oil and methanol in a parallel plates geometry microreactor is presented. The set of partial differential equations that governs the concentration profile of these species were obtained from the general mass balance equation for the case of isothermal flow and steady state with constant physical properties. The velocity profile was obtained from the Navier-Stokes equations assuming fully developed stratified laminar flow for two immiscible Newtonian fluids, with a plane interface between them, based on experimental observation of this flow pattern. The second order kinetic equations for the species were developed assuming homogeneous and reversible chemical reactions and these equations were written as source terms in the main equations. The mathematical model was solved using the hybrid method known as Generalized Integral Transform Technique (GITT). The simulation results were critically compared with those obtained by using the COMSOL multiphysics platform, showing a good agreement between the hybrid and fully numerical simulations. The effects of governing parameters such as residence time, temperature and microreactor dimensions were investigated. It was observed that higher triglycerides conversion rates occurred at higher temperatures and residence times and lower microreactor depths.     

Parameterisation of a biodiesel plant process flow sheet model

This paper presents results of parameterisation of typical input–output relations within process flow sheet of a biodiesel plant and assesses parameterisation accuracy. A variety of scenarios were considered: 1, 2, 6 and 11 input variables (such as feed flow rate or a heater's operating temperature) were changed simultaneously, 3 domain sizes of the input variables were considered and 2 different surrogates (polynomial and high dimensional model representation (HDMR) fitting) were used. All considered outputs were heat duties of equipment within the plant. All surrogate models achieved at least a reasonable fit regardless of the domain size and number of dimensions. Global sensitivity analysis with respect to 11 inputs indicated that only 4 or fewer inputs had significant influence on any one output. Interaction terms showed only minor effects in all of the cases.     

Improvement of fuel properties of cottonseed oil methyl esters with commercial additives

The low temperature operability and oxidative stability of cottonseed oil methyl esters (CSME) were improved with four anti‐gel additives as well as one antioxidant additive, gossypol. Low temperature operability and oxidative stability of CSME was determined by cloud point (CP), pour point (PP), cold filter plugging point (CFPP), and oxidative stability index (OSI). The most significant reductions in CP, PP, and CFPP in all cases were obtained with Technol®, with the average reduction in temperature found to be 3.9 °C. Gunk®, Heet®, and Howe's® were progressively less effective, as indicated by average reductions in temperature of 3.4, 3.0, and 2.8 °C, respectively. In all cases, the magnitude of CFPP reduction was greater than for PP and especially CP. Addition of gossypol, a polyphenolic aldehyde, resulted in linear improvement in OSI (R² = 0.9804). The OSI of CSME increased from 5.0 to 8.3 h with gossypol at a concentration of 1000 ppm.     

Comparison of open-air and semi-enclosed cultivation system for massive microalgae production in sub-tropical and temperate latitudes

This study compared open-air and semi-enclosed production system of the marine microalgae Nannochloropsis oculata in a sub-tropical region (32°S; 52°W) under uncontrolled environmental conditions. The semi-enclosed system was composed of 1.2 m³ circular tanks installed inside of a greenhouse. Water temperature was 4 °C higher in the indoor treatment than in the outdoor, mainly in winter although no difference was observed in warmer seasons. Moreover, variation in salinity was observed in the outdoor treatment due to rainfall (winter) and evaporation (spring), whereas indoor treatment experienced an increase (up to 100 PSU) due to evaporation only in warmer seasons. Light transmission was approximately 20% lower in the indoor treatment although cell densities and biomass yields were higher indoor during winter. As the temperature increased (spring) no differences were observed among treatments. In summary, partial control of temperature and salinity in the semi-enclosed system, especially during the colder and rainy season, allowed higher microalgae biomass production. Further experiments must be conducted with CO₂ addition, larger pH range and salinity control.     

Environmental and life cycle analysis of a biodiesel production line from sunflower in the Province of Siena (Italy)

The Directive 2009/28/EC established the overall target that 20% of energy consumption should be represented by renewable energy sources by 2020 in each European member state. Furthermore, the Directive sets a mandatory 10% minimum target for biofuels in the transport sector.Biofuels are potentially an important alternative to mineral diesel. We propose a pilot production line of biodiesel from sunflower on local scale in the Province of Siena (Tuscany) to research a possible reduction of fossil fuel consumption in the transport sector.This study might represent an opportunity to reduce petroleum dependence in the transport sector.Environmental Impact Indicators were provided by Material Flow Accounting, Embodied Energy Analysis and Emergy Accounting. Results showed that agricultural phase is the critical step in the production line.A comparative Life Cycle Assessment analysis for the biodiesel production line with mineral diesel production showed environmental advantages of the biofuel production, however requiring a higher land demand. Therefore, biodiesel may not the optimal solution on large scale but might be a good alternative to fossil fuel. This would depend upon the entire production cycle taking place in a limited area. This is necessary in order to fulfill the needs of local farms and small enterprises.