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In this paper, a novel concept of a finned piston system is presented and analyzed in which the compression heat is continuously extracted from the compression chamber. The resulting compression characteristic moves in the direction of an isothermal process, reducing the temperature of the compressed fluid in the compression chamber and reducing the necessary mechanical work required to carry out the process. The finned piston concept consists in an integrated heat exchanger inside of the chamber that is constituted of imbricated flat fins placed on the stator part and on the mobile piston. The internal heat exchange on the surface is strongly increased in comparison with a classical piston/cylinder. The energetic performance of the new system is evaluated with the help of simulation. The pressures, forces, and temperature of the compressed gas are simulated as well as the mechanical work needed. The different curves are compared with the system's adiabatic and isothermal characteristics. [ABSTRACT FROM AUTHOR]

Hydrogen powered vehicles use high-pressure reservoirs from which the gas is transferred to the low-pressure fuel-cell via a classical pressure reduction valve. In these systems no expansion work is recovered and the question is addressed of the potential to increase global efficiency by using an expansion machine between the reservoir and the electrochemical reactor. This paper investigates the feasibility of such an expansion machine, and evaluates the mechanical constraints in terms of forces, torques and produced power by numeric simulation. It further evaluates the energetic contribution to the whole conversion chain from the hydrogen reservoir to the common electrical network on board. A low-energy contribution of the expansion system addresses the question of the real benefit of such an investment. [ABSTRACT FROM AUTHOR]

A new electrically driven gas booster is described as an alternative to the classical air-driven gas boosters known for their poor energetic efficiency. These boosters are used in small scale Hydrogen storage facilities and in refueling stations for Hydrogen vehicles. In such applications the overall energy count is of significance and must include the efficiency of the compression stage. The proposed system uses an electric motor instead of the pneumatic actuator and increases the total efficiency of the compression process. Two mechanical principles are studied for the transformation of the rotational motion of the motor to the linear displacement of the compressor pistons. The strongly fluctuating power of the compressor is smoothed by an active capacitive auxiliary storage device connected to the DC circuit of the power converter. The proposed system has been verified by numeric simulation, including the thermodynamic phenomena, the kinetics of the new compressor drive and the the operation of the circuits of the power smoothing system. [ABSTRACT FROM AUTHOR]

In the context of the need to significantly reduce greenhouse gas emissions from personal transportation, a new process for the production of e-methanol is presented. It is a CO2 hydrogenation process, powered mainly by renewable energy sources such as photovoltaic electricity, with direct capture of carbon dioxide from the ambient air. With the main objective of estimating the feasibility and the impact of such a large-scale plant, the various components are evaluated in terms of masses and quantities necessary for an annual fuel production of 500,000 tons. The main reactor is analyzed to assess the required quantities of hydrogen and CO2. The production of hydrogen from the electrolysis of water is estimated, as well as the electrical power required and supplied by a large photovoltaic plant. The size of a realistic plant and its footprint are estimated. In addition, the mass of seawater to be desalinized and split in the electrolyser is calculated. The CO2 capture system is evaluated in the form of the mass of air to be extracted from the ambient air. The parameters of the system and its subcomponents are summarized for ease of understanding of the significance and size of the processing plant. [ABSTRACT FROM AUTHOR]