Transfer Of Cryogenic Propellants Research Articles

Modeling of cryogenic heated-tube flow boiling experiments of hydrogen and helium with the Generalized Fluid System Simulation Program

Accurate modeling of cryogenic boiling heat transfer is vital for the development of extended-duration space missions. Such missions may require the transfer of cryogenic propellants from in-space storage depots or the cooling of nuclear reactors. Purdue University in collaboration with NASA has assembled a database of cryogenic flow boiling data points from steady-state heated-tube experiments dating back to 1959, which has been used to develop new flow boiling correlations specifically for cryogens. Computational models of several of these experiments have been constructed in the Generalized Fluid System Simulation Program (GFSSP), a network flow code developed at NASA’s Marshall Space Flight Center. The new Purdue-developed universal correlations cover the full boiling curve: onset of nucleate boiling, nucleate boiling, critical heat flux, and film boiling. These correlations have been coded into GFSSP user subroutines. The fluids modeled in this study are liquid hydrogen and liquid helium. Predictions of local wall temperature and pressure drop are presented and compared to the test data.

Parametric analysis of the Charge-Hold-Vent method for cryogenic propellant tank chilldown

In the absence of external heat exchangers, the on-orbit transfer of cryogenic propellants requires the receiver tank to first be quenched to a sufficiently low energy state to allow for a continuous no-vent fill to avoid unnecessary venting of liquid. One proposed method for tank chilldown that minimizes the potential for venting liquid is the charge hold vent (CHV) method. CHV follows a cyclic process that gradually removes thermal energy from the receiver tank by injecting liquid with the vent valve closed and allowing the fluid and wall to reach near-thermal equilibrium before venting the superheated vapor. However, the CHV method must be optimized to minimize complexity, mass, and time. This paper presents a modular CHV analytical model used to quantify the number of cycles and propellant mass consumed based on first principles. The model is used to examine the effect of eight parameters: receiver tank material, volume, mass, maximum expected operating pressure, and initial pressure, liquid injection pressure and temperature, and the target temperature. The model is validated against the only two available CHV datasets. Based on results, the tank mass-to-volume ratio is the most important factor in determining the number of CHV cycles and thus degree of difficulty in tank chilldown. The model can easily be used for early-stage design, sizing, and analysis of cryogenic propellant transfer systems.

Modeling of cryogenic heated-tube flow boiling experiments of nitrogen and methane with Generalized Fluid System Simulation Program

Accurate modeling of cryogenic boiling heat transfer is vital for the development of extended-duration space missions. Such missions may require the transfer of cryogenic propellants from in-space storage depots or the cooling of nuclear reactors. Purdue University in collaboration with NASA has assembled a database of cryogenic flow boiling data points from heated-tube experiments dating back to 1959, which has been used to develop new flow boiling correlations specifically for cryogens. Computational models of several of these experiments have been constructed in the Generalized Fluid System Simulation Program (GFSSP), a network flow code developed at NASA’s Marshall Space Flight Center. The new Purdue-developed correlations cover the full boiling curve: onset of nucleate boiling, nucleate boiling, critical heat flux, and post-critical heat flux boiling. These correlations have been coded into GFSSP user subroutines. The fluids modeled are nitrogen and methane. Predictions of wall temperature are presented and compared to the test data.

Development of a surface cryogenic propellant transfer concept for Martian operations

NASA is currently evaluating architectures to support human missions to Mars. A multitude of concepts are being traded and associated sensitivities are being analyzed. Mars Ascent Vehicle (MAV) propellant supply is a key consideration. Mass constraints for the Mars descent system and in-space transportation present significant architectural challenges that may preclude landing a fully fueled MAV for crew use. In such a case, to ensure the ability of the crewed mission to meet its objectives, propellant should be supplied to the MAV prior to the arrival of the crewed mission from Earth. A concept to robotically transfer liquid oxygen from a separate storage tanker across the surface to the MAV is proposed. This concept makes use of an unpressurized rover and is optimized to maximize the amount of propellant conveyed per trip.

An advance in transfer line chilldown heat transfer of cryogenic propellants in microgravity using microfilm coating for enabling deep space exploration

The extension of human space exploration from a low earth orbit to a high earth orbit, then to Moon, Mars, and possibly asteroids is NASA’s biggest challenge for the new millennium. Integral to this mission is the effective, sufficient, and reliable supply of cryogenic propellant fluids. Therefore, highly energy-efficient thermal-fluid management breakthrough concepts to conserve and minimize the cryogen consumption have become the focus of research and development, especially for the deep space mission to mars. Here we introduce such a concept and demonstrate its feasibility in parabolic flights under a simulated space microgravity condition. We show that by coating the inner surface of a cryogenic propellant transfer pipe with low-thermal conductivity microfilms, the quenching efficiency can be increased up to 176% over that of the traditional bare-surface pipe for the thermal management process of chilling down the transfer pipe. To put this into proper perspective, the much higher efficiency translates into a 65% savings in propellant consumption.

Hydrodynamic model of screen channel liquid acquisition devices for in-space cryogenic propellant management

Technologies that enable the storage and transfer of cryogenic propellants in space will be needed for the next generation vehicles that will carry humans to Mars. One of the candidate technologies is the screen channel liquid acquisition device (LAD), which uses a metal woven wire mesh to separate the liquid and vapor phases so that single-phase liquid propellant can be transferred in microgravity. In this work, an experiment is carried out that provides measurements of the velocity and pressure fields in a screen channel LAD. These data are used to validate a new analytical solution of the liquid flow through a screen channel LAD. This hydrodynamic model, which accounts for non-uniform injection through the screen, is compared with the traditional pressure term summation model which assumes a constant, uniform injection velocity. Results show that the new model performs best against the new data and historical data. The velocity measurements inside the screen channel LAD are used to provide a more accurate velocity profile which further improves the new model. The result of this work is a predictive tool that will instill confidence in the design of screen channel LADs for future in-space propulsion systems.

Autonomous Operations System: Development and Application

Autonomous control systems provide the ability of self-governance beyond the conventional control system. As the complexity of systems increases, there is a natural drive for developing robust control systems to manage complicated and emergency operations. By closing the bridge between conventional automated systems and knowledge based self-aware systems, nominal control of operations can evolve into relying on safety critical mitigation processes to support any off-nominal behavior. Current research and development efforts lead by the Autonomous Propellant Loading (APL) project at NASA Kennedy Space Center aims to improve cryogenic propellant transfer operations by developing an automated control and health monitoring system. As an integrated system, the center aims to produce an Autonomous Operations System (AOS) capable of integrating health management operations with automated control to produce a fully autonomous system.

Modeling and analysis of chill and fill processes for the cryogenic storage and transfer engineering development unit tank

NASA’s future missions may require long-term storage and transfer of cryogenic propellants. The Engineering Development Unit (EDU), a NASA in-house effort supported by both Marshall Space Flight Center (MSFC) and Glenn Research Center, is a cryogenic fluid management (CFM) test article that primarily serves as a manufacturing pathfinder and a risk reduction task for a future CFM payload. The EDU test article comprises a flight-like tank, internal components, insulation, and attachment struts. The EDU is designed to perform integrated passive thermal control performance testing with liquid hydrogen (LH2) in a test-like vacuum environment. A series of tests, with LH2 as a testing fluid, was conducted at Test Stand 300 at MSFC during the summer of 2014. The objective of this effort was to develop a thermal/fluid model for evaluating the thermodynamic behavior of the EDU tank during the chill and fill processes. The Generalized Fluid System Simulation Program, an MSFC in-house general-purpose computer program for flow network analysis, was utilized to model and simulate the chill and fill portion of the testing. The model contained the LH2 supply source, feed system, EDU tank, and vent system. The test setup, modeling description, and comparison of model predictions with the test data are presented.

Assessment of existing two phase heat transfer coefficient and critical heat flux correlations for cryogenic flow boiling in pipe quenching experiments

To enable efficient design and analysis of cryogenic propellant transfer systems, high accuracy models are required for predicting two phase flow boiling and heat transfer at reduced temperatures. The penalty for poor models translates into higher margin, safety factor, and ultimately cost in design. Recently, there has been a drive towards developing universal correlations to cover a broad range of fluids, tube diameters, and thermodynamic conditions for predicting heat flux and pressure drop. These correlations do not, however, cover cryogenic fluids like liquid hydrogen. Therefore the purpose of this paper is to apply popular two phase heat transfer correlations used in commercial codes against available flow boiling data for cryogenic fluids. Specifically, quenching test data for critical heat flux and two phase heat transfer coefficient are compared against the correlations. Results show that existing correlations over-predict heat transfer by as much as 20,000% and that significant model improvements are warranted.

Thermodynamic analysis of a demonstration concept for the long-duration storage and transfer of cryogenic propellants

In the development of a concept for an experimental platform for demonstrating technologies associated with the on-orbit handling, transfer and storage of cryogenic propellants, credibility is enhanced with simulations of operations using thermodynamic models. Predictions have further credibility if the modeling technique is verified against simulations of actual cryogenic fuel transfers during ground testing. This paper will demonstrate the capability of simulating the transfer of liquid hydrogen as preformed at NASA’s Glenn Research Center. Results of simulations of an experimental space mission developed at Ball Aerospace will then follow. The mission concept is intended to demonstrate the technologies and storage methodologies for supporting long-term storage and transfer of cryogenic fuels in space.

Geysering inhibiting research for single feeding-line in cryogenic propellant transfer system

The main purpose of this paper is to use an external recirculation pipe to inhibit geysering phenomenon in cryogenic propellant transfer system. Inhibiting geysering phenomena in the long vertical cryogenic feeding-line is very important to both the system designers and the operators because they may be latent catastrophic failure(s). Separated-flow model has been used in numerical simulation. Considered the numerical simulation results and the experimental conditions, an experimental set-up using liquid nitrogen (LN 2) as working fluid has been built to simulate the recirculation in the long vertical cryogenic feeding-line. From the experimental results, it is clear that the natural circulation occurs in the recirculation system utilizing the external recirculation pipe and geysering phenomenon is inhibited. Adding external recirculation pipe to normal feeding-line system can be an effective method to reduce or eliminate geysering in cryogenic propellant transfer system.

A thermodynamic system for zero-g venting, storage, and transfer of cryogenic propellants.

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