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Because of environmental problems, it becomes necessary to develop alternative fuels that give engine performance at par with diesel. Among the alternative fuels, biodiesel and its blends hold good promises as an eco-friendly and the most promising alternative fuel for Diesel engine. The properties of biodiesel and its blends are found similar to that of diesel. Many researchers have experimentally evaluated the performance characteristics of conventional Diesel engines fueled by biodiesel and its blends. However, experiments require enormous effort, money and time. Hence, via finite-time thermodynamics simulation, an air-standard Diesel cycle model with heat transfer loss and variable specific heats of working fluid is analyzed to predict the performance of Diesel engine. The effect of compression ratio, cut-off ratio and fuel type on output work and thermal efficiency is investigated through the model. The fuels considered for the analysis are conventional diesel, rapeseed oil biodiesel and its blend (20 % biodiesel and 80 % diesel by volume). Numerical simulations showed that the output work and thermal efficiency of the engine decrease with increase of cut-off ratio for all fuels. Also, the model predicts similar performance with diesel and biodiesel blend which means that the biodiesel blend (20 % biodiesel and 80 % diesel by volume) could be a good alternative and eco-friendly fuel for conventional Diesel engines without any need to modify the engine.

Effective mechanical properties of nanocomposites reinforced with multiwalled carbon nanotubes (MWCNTs) have been determined using Finite Element Analysis (FEA). The effects of several parameters on nanocomposite effective mechanical properties are investigated. First, FEA models are created consisting of MWCNTs with different spring constants to investigate the effects of the interlayer van der Waals forces. Next, the reinforcing efficiency of MWCNTs in different matrices is investigated using models consisting of matrices with different moduli of elasticity. In addition, the effects of MWCNT volume fraction are investigated. Finally, models were created to determine effective mechanical properties of nanocomposites reinforced with Single-Walled Carbon Nanotubes (SWCNTs). Comparison of the results suggests that SWCNTs are more efficient in strengthening the matrix than MWCNTs. Also, Young's modulus prediction for multiwalled carbon nanotube in a propylene matrix is compared to experimental data investigated by Andrews et al. (2002), and good agreement is observed.

Carbon nanotubes (CNTs) possess exceptional mechanical properties and are therefore suitable reinforcements for composite materials. Nanotube efficiency in reinforcing the matrix depends on the CNT alignment, volume fraction and configuration, as well as matrix properties. In this investigation, finite element method (FEM) is used to investigate the effects of nanotube waviness ratio, volume fraction, and matrix modulus on properties of CNT based polymer nanocomposites. Nanocomposite mechanical properties are evaluated using a 3D nanoscale representative volume element. Models consisting of CNTs with different waviness ratios are created to investigate the effects of nanotube configuration on nanocomposite mechanical properties. Next, the effect of nanotube volume fraction on nanocomposite moduli of elasticity is investigated. Finally, the effects of matrix modulus are investigated by analysing models consisting of matrices with different moduli. The results of this investigation are compared with those found in the literature and good agreement is observed.