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The rapid exploitation of fossil fuels due to their indiscriminate use has brought us to a situation when we cannot sustain the use of fuels like petrol and diesel for more than 30 years from now. Governments and energy companies around the world are looking for some alternative source of energy to power the vehicles. A lot of research is being carried out in this field and many researchers have concluded that hybrid vehicles can be a boon to eradicating the dependence on conventional fuels and move towards battery-aided power trains for running the vehicles. Today, there are a few electric vehicles on roads but in the near future the roads are going to be flooded by them. To propel them, we need batteries which should be charged at some intervals. In absence of battery charging stations, we would need range extending devices on the vehicles itself. A Free Piston Linear Generator (FPLG) is an electric generator which produces electricity by virtue of oscillation of a free piston in a cylinder and it can be used as a range extending device and alternative energy converter in a hybrid vehicle. Using an FPLG will be a new approach to optimize combustion process and thus it can not only help in low exhaust emissions but also in using new renewable fuels due to their capability of variable compression ratios. This paper is a review on the design and development of FPLG system for hybrid vehicles as an inevitable source of energy in near future.

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Recent developments in ceramic-matrix composites and their successful use in combustor liners and shrouds have generated interest among researchers to adopt these materials in rotating gas turbine blades, especially in the first stages of high-pressure turbines where gas temperatures are highest. CMC blades have the potential of being retrofitted to replace superalloy turbine blades in operating gas turbines. In this paper, a comparative study on the thermodynamic performance of a marine gas turbine engine, LM 2500, featuring directionally solidified nickel superalloy blades versus novel CMC blades in the high-pressure turbine sections has been reported. Mathematical modeling of the gas turbine cycle components has been developed and then coded in C++ language. The effects of turbine inlet temperature on thermodynamic efficiencies, coolant mass flow rates, and work ratios on the two systems have been analyzed. Finally, the exergy analysis of the systems’ components has been done to identify the benefits of adopting CMC blades in the LM 2500 system. It has been observed that when compared to the directionally solidified bladed turbine system, the projected first law efficiency of CMC bladed LM 2500 gas turbines can be enhanced over 7% (from 34.17% to 41.21%). The projected work ratio can be improved by over 16% (from 0.49 to 0.57) at the turbine inlet temperature of 1725 K.

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