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.

Analysis of Aircraft Fuel Tank Fire and Explosion Hazards

Abstract: : Under simulated flight environments, fuel/air ratios at various locations of the ullage space were determined using in-line gas chromatograph measurement. Using the shallow tank experimental data showed that during ascent and cruise portion of the flight profile, uniform fuel/air mixtures were found to exist within the entire ullage volume. Significant fuel/air gradients existed during the descent portion of the flight profile, with mainly air near the vent inlet. Evaporation lag was observed during ascent and level flight when liquid Jet A fuel was maintained at 80 degree F. When the liquid fuel temperature was increased to 120F, evaporation rate was found to be rapid enough that the evaporative lag phenomena was no longer observed. By vibrating the fuel tank, it greatly increased the rate of off-gassing of dissolved air in the liquid fuel. This in turn significantly changed the fuel/air ratio in the ullage space. Two separate and complementary models were developed to predict fuel/air concentrations within the ullage.

Control of vapor emissions from gasoline stations

Abstract: The present invention relates to a vapor recovery system for gas station that is capable of controlling vapor emission to less than 0.38 lbs/1000 gallons fuel dispensed. The system may include at least one canister containing adsorbents such as activated carbon, zeolite, activated alumina, silica, and other adsorbents for passive removal of hydrocarbon vapors in venting air. Additionally, the system may include a means to enhance vapor-liquid equilibrium in the ullage of the fuel tank and accordingly minimize vapor emission level.

Method and system for controlling the supply of nitrogen to electrical power handling equipment

Abstract: A system that controls nitrogen pressure in the ullage of a power transformer that has its windings submerged in oil. The pressure is controlled in a narrow range of approximately 0.5 psi to approximately 2.0 psi. A nitrogen generator supplies the nitrogen to a reservoir from which it is distributed to the ullage as well as to accessories such as a load tap changer or a control box. A temperature regulator is provided for substation installations that are located in climates with wide ambient temperature variations to control the pressure of the generated nitrogen in an acceptable range.

Numerical modeling of propellant boil-off in a cryogenic storage tank

Abstract: A numerical model to predict boil-off of stored propellant in large spherical cryogenic tanks has been developed. Accurate prediction of tank boil-off rates for different thermal insulation systems was the goal of this collaboration effort. The Generalized Fluid System Simulation Program, integrating flow analysis and conjugate heat transfer for solving complex fluid system problems, was used to create the model. Calculation of tank boil-off rate requires simultaneous simulation of heat transfer processes among liquid propellant, vapor ullage space, and tank structure. The reference tank for the boil-off model was the 850,000 gallon liquid hydrogen tank at Launch Complex 39B (LC- 39B) at Kennedy Space Center, which is under study for future infrastructure improvements to support the Constellation program. The methodology employed in the numerical model was validated using a sub-scale model and tank. Experimental test data from a 1/15th scale version of the LC-39B tank using both liquid hydrogen and liquid nitrogen were used to anchor the analytical predictions of the sub-scale model. Favorable correlations between sub-scale model and experimental test data have provided confidence in full-scale tank boil-off predictions. These methods are now being used in the preliminary design for other cases including future launch vehicles