Liquefied natural gas (LNG) is one of the most influential fuels of the 21st century, especially in terms of the global economy. The demand for LNG is forecasted to reach 400 million tonnes by 2020, increasing up to 500 million tonnes in 2030. Due to its high mass and volumetric energy density, LNG is the perfect fuel for long-distance transport, as well as for use in mobile applications. It is also characterized by low levels of emissions, which is why it has been officially approved for use as a marine fuel in Emission Control Areas (ECAs) where stricter controls have been established to minimize the airborne emissions produced by ships. LNG is also an emerging fuel in heavy road and rail transport. As a cryogenic fuel that is characterized by a boiling temperature of about 120 K (−153 °C), LNG requires the special construction of cryogenic mobile installations to fulfill conflicting requirements, such as a robust mechanical construction and a low number of heat leaks to colder parts of the system under high safety standards. This paper provides a profound review of LNG applications in waterborne and land transport. Exemplary constructions of LNG engine supply systems are presented and discussed from the mechanical and thermodynamic points of view. Physical exergy recovery during LNG regasification is analyzed, and different methods of the process are both analytically and experimentally compared. The issues that surround two-phase flows and phase change processes in LNG regasification and recondensation are addressed, and technical solutions for boil-off gas recondensation are proposed. The paper also looks at the problems surrounding LNG installation data acquisition and control systems, concluding with a discussion of the impact of LNG technologies on future trends in low-emission transport.

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Abstract. The 27 km circumference LHC underground tunnel is a space in which the helium cooled LHC magnets are installed. The vacuum enclosures of the superconducting magnets are protected by over-pressure safety relief devices that open whenever cold helium escapes either from the magnet cold enclosure or from the helium supply headers, into this vacuum enclosure. A 3-m long no stay zone around these devices is defined based on scale model studies, protecting the personnel against cold burns or asphyxia caused by such a helium release event. Recently, several simulation studies have been carried out modelling the propagation of the helium/air mixture, resulting from the opening of such a safety device, along the tunnel. The released helium flows vary in the range between 1 kg/s and 0.1 kg/s. To validate these different simulation studies, real life mock-up tests have been performed inside the LHC tunnel, releasing helium flow rates of 1 kg/s, 0.3 kg/s and 0.1 kg/s. For each test, up to 1000 liters of liquid helium were released under standard operational tunnel conditions. The data recorded include oxygen concentration, temperature and flow speed measurements, and video footage used to assess qualitatively the visibility. These measurements have been made in the up-and downstream directions, with respect to the air ventilation flow, of the spill point. This paper presents the experimental set-up under which these release tests were made, the effects of these releases on the atmospheric tunnel condition as a function of the release flow rate. We discuss the modification to the personnel access conditions to the LHC tunnel that are presently implemented as a result of these tests.