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This paper aims to improve the previous fuel scrubbing model and find out the relationship between bubble diameter and scrubbing efficiency (ƞ).

A fuel tank scrubbing test bench was established to verify the accuracy of this model. Ullage and dissolved oxygen concentration were measured, and images of bubble size and distribution were collected and analyzed using image analysis software.

The bubble diameter has a great influence on ullage and dissolved oxygen concentration during the fuel scrubbing process. The scrubbing efficiency (ƞ) has an exponential relationship with bubble diameter and decreases rapidly as the bubble diameter increases.

The variation of the ullage and dissolved oxygen concentration predicted by this model is more accurate than that of the previous model. In addition, the study of bubble size can provide a guidance for the design of fuel scrubber.

This study not only improves the previous fuel scrubbing model but also develops a method to calculate scrubbing efficiency (ƞ) based on bubble diameter. In addition, a series of tests and analyses were conducted, including numerical calculation, experiment and image analysis.

Determining the variation law of the oxygen concentration in the ullage space of the fuel tank is the key to the design of the inert system. Among various factors affecting the oxygen concentration in the ullage space of the fuel tank, the temperature difference between day and night shows particular importance while relevant analysis and calculation are scarce.

This study establishes a theoretical simulation model of the central wing fuel tank of an aircraft according to the relevant provisions of day-night temperature variation in FAR25 airworthiness regulations, verifies the model with the existing experimental data and discusses the corresponding relationship between the oxygen concentration in the ullage space of the fuel tank and the day-night temperature difference. The influence of day and night temperature difference, fuel type, fuel load rate, initial oxygen concentration, dissolved oxygen evolution and other factors on the oxygen concentration in the ullage space of the fuel tank were analyzed, and the limit of initial oxygen concentration of the fuel tank before the shutdown at night meeting the requirements of the airworthiness provisions was proposed.

The results show that the temperature difference between day and night, fuel load rate, initial oxygen concentration and other factors have different effects on the oxygen concentration in the ullage space of fuel tank. The initial oxygen concentration limit before shutdown shall be 2% below the 12% oxygen concentration stipulated by FAA.

The research results in this paper will be of good reference value to the design of the inert system and the calculation of the flammability exposure evaluation time. This paper aims to be good reference of the design of the inert system and the calculation of the flammability exposure evaluation time.

The research results of this paper can provide practical guidance for the current civil airworthiness certification work.

The objective of this study is to model the propagating front in the interaction of gases in an aircraft fuel tank. To this end, we introduce a nonlinear parabolic operator, for which solutions are shown to be regular.

The authors provide an analytical expression for the propagating front, that shifts any combination of oxygen and nitrogen, in the tank airspace, into a safe condition to avoid potential explosions. The analytical exercise is validated with a real flight.

According to the flight test data, the safe condition, of maximum 7% of oxygen, is given for a time t = 45.2 min since the beginning of the flight, while according to our analysis, such a safe level is obtained for t = 41.42 min. For other safe levels of oxygen, the error between the analytical assessment and the flight data was observed to be below 10%.

The interaction of gases in a fuel tank has been little explored in the literature. Our value consists of introducing a set of nonlinear partial differential equations to increase the accuracy in modeling the interaction of gasses, which has been typically done via algebraic equations.

Sustainable atmospheric management today involves a complex set of issues arising from the deliberate or inadvertent use of the atmosphere as a repository for waste products arising from human activities. Urban pollution affects human health, building materials and vegetation. Acidic emissions and excess nutrients produce both acid rain and dry deposition that affect terrestrial, freshwater and ocean chemistry and ecosystems. The production and effects of atmospheric pollution can transcend national boundaries and thus mitigation will require cooperation on regional and global levels, as well as local action. Global pollution includes greenhouse gases and atmospheric particles which are changing the global climate and affecting human health. While technological solutions will play an important part, the large reductions in emissions necessary to achieve sustainability will involve adopting lifestyles that conserve energy and minimise pollution. These concerns were foreshadowed in the writings of Fritz Schumacher.

This chapter outlines the potential market of methane (especially LNG) as vehicle fuel in Europe and China.

A comprehensive report on the existing framework in terms of market capacity, regulations, and incentives is presented. Moreover, the feasibility of using biogas as environmental friendly source gas is considered.

The transport sector represents a major element in the global balance of greenhouse gas (GHG) emissions. Natural gas is considered the alternative fuel that, in the short-medium term, can best substitute conventional fuels in order to reduce their environmental impact, because it is readily available at a competitive price, using technologies that are already in widespread use. It can be used as compressed gas (CNG) or in the liquid phase (LNG). The former is more suitable for light vehicles, while the latter for heavy-duty vehicles. Some barriers need to be overcome for the diffusion of this alternative fuel, especially concerning the supply problem. The incentive policy has been shown to cover a major influence in the feasibility evaluation.

This work shows the state of the art of natural gas as fuel, especially from biogas source, in Europe and China and assesses the incentive scheme necessary to make liquefied biomethane feasible on the basis of the existing scenario in Italy.

Sulphur dioxide, a dangerous atmospheric pollutant, is a major concern with the increasing use of coal as a combustion fuel in thermal power plants. Numerous efforts were made through these years to minimize the emission of sulphur dioxide and one such effort is the desulphurization of the flue gas generated during combustion, commonly termed as flue gas desulphurization (FGD). However, the materials of construction used for FGD systems, usually of type 316L stainless steel were reported to be failed due to the localized corrosion attack by the aggressiveness of the environment, mainly of chloride, fluoride, acidity and temperature encountered during the scrubbing of SO2.

The emission of SO2, a dangerous atmospheric pollutant, is the major problem with increasing the use of coal as fuel in various industries, particularly in thermal power plants. A variety of methods for minimizing the SO2 emission have been reported in the literature, among which the desulphurization of the flue gas, generated by combustion of coal receives much attention and is termed as flue gas desulphurization (FGD). FGD scrubbers have found widespread use in thermal power plants, smelters, incinerators and various refining operations. The scrubber parts must resist corrosion from solution which have a varying degree of acidity and erosion, besides containing substantial concentrations of chlorides and SO2, and the unfavourable conditions of fluctuations in temperature. The currently‐used type 316L stainless steel material in many FGD installations, were reported to have failed, due to the localized corrosion attack by the aggressiveness of the environment encountered during scrubbing of SO2. Normally, the improvement in corrosion performance of the construction materials can be achieved by:

WHILE the general principles of gas‐fuel propulsion for airships have been enunciated in a former article, there remain to be considered both the gases available and the means whereby they can be procured.

A piston‐and‐cylinder friction type vibration damper 16 is disposed between each pair of adjacent rotor blades 10 of a helicopter rotor. There is no damper provided at the drag hinge 14 between each blade 10 and the hub structure 13 of the rotor. The damper 16 comprises a scrubbing action with vibration damping and it provides constant damping for normal blade‐to‐blade oscillations and an increased degree of damping when abnormal oscillations take place. As shown in fig. 1, the damper provides resistance to compression movements only. Another damper is described which is double‐acting.

THE GENERAL ELECTRIC TF34‐GE‐2 turbofan engine was designed and developed specifically to fulfil the powerplant requirements of the S‐3A. Consequently, engine design considerations included both anti‐submarine warfare mission requirements and compatibility with a carrier‐based environment. To meet both, the engine features high thrust‐to‐weight, low fuel consumption over a wide power range, low noise and smoke, and corrosion resistant materials throughout.