Showing papers on "Ullage published in 2013"

Investigation of Tank Pressurization and Pressure Control—Part II: Numerical Modeling

Abstract: A multizone model is used to predict both the self-pressurization and pressure control behavior of a ground-based experiment. The multizone model couples a finite element heat conduction model of the tank wall to the bulk conservation equations in the ullage and the liquid. Comparisons are made to the experimental data presented in a companion paper. Results suggest that the multizone model can predict self-pressurization behavior over a variety of test conditions. The model is also used to predict the pressure control behavior when a subcooled axial mixing jet is used to thermally destratify and cool the bulk liquid. For fast jet speeds, the multizone model does a reasonably predict the pressure collapse behavior. Comparisons were also made between the data and a homogeneous thermodynamic model. These comparisons highlight the deficiencies of the homogeneous modeling approach.

Fuel vapor removal methods and systems for flammability reduction

Abstract: FUEL VAPOR REMOVAL METHODS AND SYSTEMS FOR FLAMMABILITY REDUCTION A fuel vapor removal method includes removing fuel vapor from ullage of a fuel tank of a vehicle, adsorbing the fuel vapor removed from the ullage onto adsorption media on the vehicle, and desorbing the fuel vapor from the adsorption media while on the vehicle. A fuel vapor removal method includes purging fuel vapor from ullage of a fuel tank using air added into the ullage, reducing a fuel-air ratio in the ullage using the air purging, and adsorbing the purged fuel vapor onto adsorption media. A fuel vapor removal system includes a fuel tank having ullage, an adsorption system including fuel vapor adsorption media fluidically connected to the ullage and to an ullage purging system, and a controller. The controller includes a flammability determination system and is configured to start fuel vapor removal by the purging system from the ullage onto the adsorption media before the ullage exhibits flammability. 50 38 - - FIGURE 4 40 -- 108 ADSORPTION AND DESORPTION 59 8 SYSTEM (ADS) FIGURE 5 70 80 ------ ------ 44 90-H FUEL-VAPOR FUEL-VAPOR FUEL-VAPOR TREATMENT TREATMENT TREATMENT SYSTEM OR SYSTEM OR SYSTEM (EMBODIMENT A), (EMBODIMENT B), (EMBODIMENT C), (FTSA) FIGURE 6A (FTSB) FIGURE 6B (FTSC) FIGURE 6C CONTROL AND FUEL TANK F-UE- 7 INDICATION PANEL -FIGURE7 FIGURE 3 _ _ _14 20-\ CONTROL AND INDICATION 34- 12 FI.18

Time domain reflectometry aircraft fuel gauge

Abstract: An aircraft fuel tank system comprising an aircraft fuel tank and a time domain reflectometry (TDR) fuel gauge for measuring a filling level of fuel in the aircraft fuel tank (1, 2). The TDR fuel gauge comprises an electromagnetic signal generator (30) and a cable (20, 22), the cable comprising a first cable part (20) and a second cable part (22) which are coupled in series to the signal generator. The first cable part extends downwardly within the fuel tank and the second cable part extends upwardly within the fuel tank. The first and second cable parts are arranged such that for at least one filling level the first cable part extends down into the fuel from an ullage space at a first location and the second cable part extends up out of the fuel into an ullage space at a second location which is spaced apart from the first location.

Dynamic Ullage Control System for a Cryogenic Storage Tank

Abstract: A dynamic system for determining an optimal liquid fill level and ullage space for a cryogenic liquid storage tank based on the temperature of the liquid being dispensed into the tank, and the desired operating pressure for an application. A means for selecting a desired operating pressure, such as a dial, is located external to the storage tank. A temperature sensor measures the temperature of the cryogenic liquid being dispensed. An optimal fill level and ullage space is calculated, and communicated to a liquid level sensor and flow control valve.

Experimental Studies of Liquefaction and Densification of Liquid Oxygen

Abstract: The propellant combination that offers optimum performance is very reactive with a low average molecular weight of the resulting combustion products. Propellant combinations such as oxygen and hydrogen meet the above criteria, however, the propellants in gaseous form require large propellant tanks due to the low density of gas. Thus, rocketry employs cryogenic refrigeration to provide a more dense propellant stored as a liquid. In addition to propellant liquefaction, cryogenic refrigeration can also conserve propellant and provide propellant subcooling and propellant densification. Previous studies analyzed vapor conditioning of a cryogenic propellant, with the vapor conditioning by either a heat exchanger position in the vapor or by using the vapor in a refrigeration cycle as the working fluid. This study analyzes the effects of refrigeration heat exchanger located in the liquid of the common propellant oxidizer, liquid oxygen. This study predicted and determined the mass condensation rate and heat transfer coefficient for liquid oxygen.

Effect of Residual Noncondensables on Pressurization and Pressure Control of a Zero-Boil-Off Tank in Microgravity

Abstract: The Zero-Boil-Off Tank (ZBOT) Experiment is a small-scale experiment that uses a transparent ventless Dewar and a transparent simulant phase-change fluid to study sealed tank pressurization and pressure control with applications to on-surface and in-orbit storage of propellant cryogens. The experiment will be carried out under microgravity conditions aboard the International Space Station in the 2014 timeframe. This paper presents preliminary results from ZBOT's ground-based research that focuses on the effects of residual noncondensable gases in the ullage on both pressurization and pressure reduction trends in the sealed Dewar. Tank pressurization is accomplished through heating of the test cell wall in the wetted and un-wetted regions simultaneously or separately. Pressure control is established through mixing and destratification of the bulk liquid using a temperature controlled forced jet flow with different degrees of liquid jet subcooling. A Two-Dimensional axisymmetric two-phase CFD model for tank pressurization and pressure control is also presented. Numerical prediction of the model are compared to experimental 1g results to both validate the model and also indicate the effect of the noncondensable gas on evolution of pressure and temperature distributions in the ullage during pressurization and pressure control. Microgravity simulations case studies are also performed using the validated model to underscore and delineate the profound effect of the noncondensables on condensation rates and interfacial temperature distributions with serious implications for tank pressure control in reduced gravity.

Apparatus and method to limit slosh and ullage in a liquid container

Abstract: A plurality of balloons are disposed inside a liquid container to take up space as liquid is removed from the container. The balloons can be connected to a gas injection system to inject gas into the balloons to keep the liquid fill level in the container to a filled level. This results in little or no sloshing of the liquid inside the container. The balloons can be secured in place by one or more positioning boxes disposed along the container's inside periphery. One or more strings can interconnect the balloons to the positioning boxes.

Centaur space vehicle pressurized propellant feed system tests

Abstract: Engine firing tests, using a full-scale flight-weight vehicle, were performed to evaluate a pressurized propellant feed system for the Centaur. The pressurant gases used were helium and hydrogen. The system was designed to replace the boost pumps currently used on Centaur. Two liquid oxygen tank pressurization modes were studied: (1) directly into the ullage and (2) below the propellant surface. Test results showed the two Centaur RL10 engines could be started and run over the range of expected flight variables. No system instabilities were encountered. Measured pressurization gas quantities agreed well with analytically predicted values.

Electronic system for calculating crude oil loss

Abstract: Provided is an electronic system for calculating the crude oil loss. The system is composed of a technical framework and a total service framework and can describe loss of all links during an oil refining process. Furthermore, the electronic system can calculate the comprehensive loss of all links from crude oil ullage to product outgoing.

An Assessment of Helium Evolution from Helium-Saturated Propellant Depressurization in Space

Abstract: Helium evolution from the transfer of helium-saturated propellant in space is quantified to assess its impacts from creating two-phase gas/liquid flow from the supply tank, gas injection into the receiving tank, and liquid discharge from the receiving tank. Propellant transfer takes place between two similar tanks whose maximum storage capacity is approximately 2.55 cubic meters each. The maximum on-orbit propellants transfer capability is 9000 lbm (fuel and oxidizer). The transfer line is approximately 1.27 cm in diameter and 6096 cm in length and comprised of the fluid interconnect system (FICS), the orbiter propellant transfer system (OPTS), and the International Space Station (ISS) propulsion module (ISSPM). The propellant transfer rate begins at approximately 11 liter per minute (lpm) and subsequently drops to approximately 0.5 lpm. The tank nominal operating pressure is approximately 1827 kPa (absolute). The line pressure drops for Monomethy1hydrazine (MMH) and Nitrogen tetroxide (NTO) at 11.3 lpm are approximately 202 kPa and 302 kPa, respectively. The pressure-drop results are based on a single-phase flow. The receiving tank is required to vent from approximately 1827 kPa to a lower pressure to affect propellant transfer. These pressure-drop scenarios cause the helium-saturated propellants to release excess helium. For tank ullage venting, the maximum volumes of helium evolved at tank pressure are approximately 0.5 ft3 for MMH and 2 ft3 for NTO. In microgravity environment, due to lack of body force, the helium evolution from a liquid body acts to propel it, which influences its fluid dynamics. For propellant transfer, the volume fractions of helium evolved at line pressure are 0.1% by volume for MMH and 0.6 % by volume for NTO at 11.3 lpm. The void fraction of helium evolved varies as an approximate second order power function of flow rate.

Cryogenic fluid management technologies for space transportation. Zero G thermodynamic vent system

Abstract: Long term storage of subcritical cryogens in space must address the problem of thermal stratification in the storage tanks, liquid acquisition devices, and associated feed systems. Due to the absence of gravity induced body forces, thermal stratification in zero-g is more severe than commonly experienced in a one-g environment. If left uncontrolled, the thermal gradients result in excessive tank pressure rise and the formation of undesirable liquid/vapor mixtures within the liquid bulk, liquid acquisition system, and propellant transfer lines. Since external heat leakage cannot be eliminated, a means of minimizing the thermal stratification in the ullage gas, liquid, and feed system is required. A subsystem which minimizes the thermal stratification and rejects the environmental heat leakage in an efficient manner is therefore needed for zero-g subcritical cryogenic systems. In ground based storage systems the ullage gas location is always known (top of the tank) and therefore direct venting of gases as a means of heat rejection is easily accomplished. In contrast, because the ullage location in a zero-g environment is not easily predictable, heat rejection through direct gaseous venting is difficult in space (requires liquid settling, or surface tension devices). A means of indirect venting through the use of a thermodynamic vent system (TVS) is therefore required. A thermodynamic vent system allows indirect venting of vapor through heat exchange between the vented fluid and the stored fluid. The objective is to ensure that only gas and not liquid is vented, in order to minimize the propellant losses. Consequently, the design of a TVS is a critical enabling technology for future applications such as solar thermal and electric propulsion, single-stage-to-orbit vertical landers and upper stages, and any space based operations involving subcritical cryogenics. To bridge this technology gap NASA MSFC initiated an effort to build and verify through ground tests a zero-g liquid hydrogen TVS. The primary objective of the zero-g TVS contract (Contract NAS8-39202) was to design a zero-g vent system that is innovative, simple, efficient, lightweight, and can be characterized through one-g tests. The TVS concept defined by Rockwell International was selected by NASA for further design evaluation. The 30 month activity was initiated in November 1991 and concluded on May 1994.

Design and FE Analysis of Anti-Slosh Baffles for Fourth Stage of PSLV

Abstract: Polar Satellites Launch Vehicle (PSLV) is the work horse of ISRO. It is used to launch 1000 kg satellites in polar orbits and upto 1600 kg satellites in low earth orbits. PSLV is a 4 stage vehicle weighing 315 tonnes. It uses liquid propulsion for second and fourth stages. The fourth stage propulsion tank is made up of Titanium Alloy (Ti6Al4V)(1335 mm dia). The configuration of tank is monocoque, with a common bulkhead to separate the fuel and oxidiser. The top compartment is used for fuel and bottom compartment is filled with oxidiser. Anti-slosh baffles (Ring Baffles) are used in both compartments to suppress slosh .Sloshing is a common phenomenon in partially filled liquid container. The rocket motor cases, filled with liquid propellants are left with an internal ullage volume (free volume) for the pressuring gas to stabilise. This creates a free surface of liquid. Sloshing is defined as the oscillation of the free surface of a liquid in a partially filled container due to external disturbances. Baffles are essentially "plates" fixed inside the container to arrest sloshing. The slosh waves, during the causes of travel, hits the plates breaks and dies out. This reduces the slosh forces on the walls of container. Presently the ring baffles are supported from top flange of tank for launching satellites up to 1200 kg. For this propellant loading is upto 2.5 t. Now a PS4 stage is reconfigured with 0.8 t loading to launch 500 kg satellites. In this tank the liquid levels are less. Hence ring baffles are supported from bottom flange of tank to reduce the total mass of the baffle system. So in this paper Structural design, Finite Element analysis and Modal Analysis are carried out.

Apparatus and method to limit slosh and ullage in a liquid container

Abstract: At least one balloon or bladder is disposed inside a liquid container to take up space as liquid is removed from the container. The balloon(s) can be connected to a gas injection system to inject gas into the balloon(s) to keep the liquid fill level in the container to a filled level. This results in little or no sloshing of the liquid inside the container. The balloon(s) can be secured in place by one or more positioning boxes disposed along the container's inside periphery. One or more strings can interconnect the balloon(s) to the positioning boxes.

A Comparative Analysis of Analog and Digital Gantries in Nigeria's Hydrocarbon Depot Management

Abstract: This study is focused on the comparative study of a Nigerian Independent Petroleum Company (NIPCO) digital depot operation and Consolidated Oil (CONOIL) analog depot operation in petroleum product supply chain. The analytical tools used in this study are; DEA Model and Censored Normal Regression Analysis. Censored Normal Regression Analysis was used to analyse the relationship between depot output (ullage savings) and gantry time. The result of the study suggests the following: Firstly, NIPCO is relatively more efficient than CONOIL. Secondly, the coefficient of gantry time is negatively related to output. This implies that increasing gantry input (time) will reduce the productivity of the depot output and vice versa. DOI: 10.5901/mjss.2013.v4n14p591

Fuel vapor removal method and system for flammability reduction

Abstract: PROBLEM TO BE SOLVED: To provide a fuel vapor removal method and a fuel vapor removal system that include: removing fuel vapor from ullage of a fuel tank of a vehicle; adsorbing the fuel vapor removed from the ullage onto adsorption media on the vehicle; and desorbing the fuel vapor from the adsorption media while on the vehicle.SOLUTION: A fuel vapor removal method includes: purging fuel vapor from ullage of a fuel tank using air added into the ullage; reducing a fuel-air ratio in the ullage using the air purging; and adsorbing the purged fuel vapor onto adsorption media. A fuel vapor removal system 1 includes: a fuel tank 100 having ullage; an adsorption system 5 including fuel vapor adsorption media; and a controller 3. The controller includes a flammability determination system and is configured to start fuel vapor removal from the ullage onto the adsorption media by the purging system before the ullage exhibits flammability.

Self-draining ullage fuel tank systems and related methods

Abstract: Self-draining ullage fuel tank system and related methods are described. An example fuel tank apparatus includes a fuel tank and a ullage tank positioned at an elevation relative to the fuel tank. The example fuel tank apparatus also includes a fluid path to fluidly couple a cavity of the fuel tank and a cavity of the ullage tank. The fluid path having a first end coupled to the cavity of the fuel tank. The fluid path having a second end extending through an opening of an upper wall of the ullage tank and having an opening positioned adjacent a bottom surface of the cavity of the ullage tank.

Ullage Temperatures In ‘Wet’ Spent Fuel Transport Flasks

Abstract: Calculation techniques for predicting the thermal and hydrodynamic conditions in spent nuclear fuel transport flasks have recently been extended to include computational fluid dynamic (CFD) modelling. This paper outlines the modelling methods used for predicting the thermodynamic conditions in the ullage space of wet transport flasks during normal transport and in a simulated fire event. The calculations include conjugate heat transfer, that is thermal transport through substantive solid volumes enclosing fluid spaces, radiative transport within and without the fuel element arrays and convective transport with phase change. Fuel pin temperatures have been shown by this method to be lower than previously calculated by other methods. In the worst case considered, representing the highest licensed thermal load in the hottest-running package, pin temperatures have been shown to remain far below temperatures that could cause cladding deterioration or autoignition of radiolysis gas products.

Efficiently effectively inserting inert gases into the entire volumes and ullage spaces of ships' steel ballast tanks to retard interior corrosion

Abstract: A (1) piping grid, nozzles and/or deflectors and/or diffusers placed on the piping at a certain intervals, and (2) header pipes connecting the piping grid to (3) an inert gas generator via (4) a compressor and (5) an optional cooler support efficient and effective injection of inert gases into all regions and volume of ships' steel ballast tanks, retarding or avoiding corrosion. Efficiency in use of generated inert gas, effective entrance of inert gas into ballast tank spaces that may be remote and/or difficult of access, and minimization of the elapsed time to fill the tank with inert gas while discharging essentially all oxygen-containing air previously within the tank, are all realized by progressive, staged, insertion of cooled inert gases from tank bottom to tank top, marshaling contained air and expelling it out the tank tops.