Publications de Alfred Rufer | EPFL Graph Search

A four-cylinder pneumatic expansion motor with high efficiency

A four-cylinder pneumatic motor is proposed and analyzed as an expansion machine to be used in a compressed-air energy storage system. The motor uses a combination of displacement work at constant pressure followed by a sequence of expansion of the air. Th ...

Academia.edu Journals2025

Performance Evaluation of Static and Dynamic Compressed Air Reservoirs for Energy Storage

Alfred Rufer

The concept of static and dynamic reservoirs is presented, and their performances are evaluated. The static reservoir is a simple reservoir with constant volume, and the dynamic one has a volume which varies as a function of the position of an internal pis ...

MDPI AG2025

Towards the Isothermal Gas Compression—A Novel Finned Piston-Cylinder with Increased Efficiency

Alfred Rufer

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 proces ...

2024

ENERGETIC PROPERTIES OF THE (FAST) CHARGING AND DRIVING OF AN ELECTRIC VEHICLE – A RAGONE ANALYSIS

Alfred Rufer

The energy efficiency of EVs is analysed for the charging and for the driving process where real parameters of a product of the automotive industry are considered. The efficiency in the charging mode is analysed and represented in function of the charging ...

2024

Semi-rotary and Linear Actuators for Compressed Air Energy Storage and Energy Efficient Pneumatic Applications

Alfred Rufer

This text explains the use of compressed air for energy storage and efficient pneumatic applications. Chapters cover the elementary physical and engineering principles related to compressed air, including compression and expansion characteristics, adiabati ...

Taylor and Francis2023

Expansion Work Recovery of Hydrogen for a FC-Truck-Tentative Design of an Expansion Machine

Alfred Rufer

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 ...

MDPI2023

Increasing the Energy Efficiency of Gas Boosters for Hydrogen Storage and for Refueling Stations

Alfred Rufer

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 Hydrog ...

MDPI2023

Quantitative Design of a New e-Methanol Production Process

Alfred Rufer

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 pho ...

MDPI2022

On The Efficiency Of Energy Storage Systems - The Influence Of The Exchanged Power And The Penalty Of The Auxiliaries

Alfred Rufer

Storage is an important domain of the energy sector, with its traditional, classical solutions for smaller and larger amounts of energy. Energy storage has become of higher importance in relation with the development of alternative energy sources, leading ...

UNIV NIS2021

A High Efficiency Pneumatic Drive System Using Vane-Type Semi-Rotary Actuators

Alfred Rufer

A compressed air driven generator is proposed, where the pneumatic energy is converted into mechanical energy using two vane-type rotational actuators. The use of a second actuator with a higher displacement in order to produce a thermodynamic expansion al ...

UNIV NIS2021