Ullage

About: Ullage is a research topic. Over the lifetime, 501 publications have been published within this topic receiving 4704 citations. The topic is also known as: headspace.

A Three Layer Model For Oil Tank Fires

Abstract: A three layer model for oil tank fires, which can be used to calculate heat transfer and burning rates more accurately, is studied theoretically and experimentally. It can also be used to explain the important role played by the ullage (or air space) in oil tank fires. The validity of this model has been established by burning jet fuel in an oil tank 1.6 m in diameter and 1.5 m high.

Feasibility of Scavenging Propellants from Lander Descent Stage to Supply Fuel Cells and Life Support

Abstract: A feasibility study consisting of both analytical and experimental work was performed to determine if the lunar lander vehicle can use residual propellants remaining in the descent stage tanks after landing to provide reactants to the fuel cell power system and oxygen to life support for a 7-day sortie mission. Initial results indicate that the residual hydrogen will last approximately 19 days at the poles and 15 days at the equator. The residual oxygen will last 21 days at the poles and more than 16.5 days at the equator. Excess hydrogen will need to be vented during the mission to prevent tank over-pressurization, while heat must be added to the oxygen tank at the poles. Tests performed on a liquid oxygen tank pressurized with helium demonstrate that the helium concentrations in the ullage gas can be reduced significantly with venting. Tests on a flow-through fuel cell stack indicate that they can tolerate significant amounts of helium contamination in the reactants without permanent

Fuel system ullage float assembly

Abstract: A fuel system ullage float valve assembly is provided for fuel tank and fuel fill line. This assembly is located near the intersection of the fuel fill line entering the uppermost top section of a fuel tank. A ullage float valve assembly includes a cage enclosure having an upper collar, a plurality of leg members and a base, essentially forming a frame-like structure. The upper collar is partially inserted into, and nest within, the fuel fill line as it enters the tank. The leg members extend downwardly into the tank in a generally vertical position. The assembly also includes a buoyant float chamber, having a generally cylindrical base and a generally converging, conical upper section. The float chamber is buoyant and it housed within the cage enclosure, and is slididly movable within the enclosure. During the fueling process as fuel fills the tank the ullage float assembly rises within the cage enclosure and to reach a sealing engagement with the upper collar of the assembly causing termination of the fueling process. The float assembly also includes a fuel bypass port.

Effects of ullage gas and scale on sloshing loads

Abstract: Gas–liquid density ratio (DR) is a key dimensionless number in sloshing assessment methodologies of membrane containment systems for LNG tanks of floating structures. Earlier studies on the effect of DR were mainly statistical and effects of DR were usually mixed with those of gas compressibility and ullage gas pressure but attributed only to DR. In an attempt to separately study such effects, Karimi et al. (2015) [11] studied the effects of DR far from impact zones (global effects of gas–liquid density ratio) which proved to be small in the studied range of DR (0.0002 to 0.0060). The effects of DR near impact zones and before detection of any compressibility effects are referred to as local effects and correspond to modifications of wave shape before impact. They were treated in Karimi et al. (2016). This paper studies the influence of ullage gas at the same scale as well as scaling of sloshing loads at different scales. The test setups were similar to those presented in Karimi et al. (2015) [11] and Karimi et al. (2016) and consisted of three 2D model tanks as transverse slices of tank 2 (out of 4) of a membrane LNG carrier with total capacity of 152000 m3 at scales 1:10, 1:20 and 1:40. All model tests were performed at a fill level corresponding to 20% of the tank heights. Water as liquid and different ullage gases of helium (He), air, two mixtures of sulfur hexafluoride (SF6) and nitrogen (N2), and pure SF6, all at atmospheric pressure with a range of DRs from 0.0002 to 0.0060 were used. Synchronized High-speed video cameras (@4000 fps) and arrays of piezo-electric PCB pressure sensors (@40 kHz) monitored and measured impacts on the tank walls. The study was mainly based on the definition of Impact ID based on impact coincidence. The results are presented at 4 main stages. First, in the same way that sloshing loads measured in irregular model tests are treated in the current methodologies, the measured pressure peaks are studied as statistical samples. Next by the notion of impact ID, the effect of change of ullage gas at the same scale is verified. Thirdly with the same notion of impact ID, impacts are tracked down through three scales to verify scaling. At last dominant impact IDs are introduced. It is shown that the most severe impacts are generated by only a few dominant IDs.