This research addresses the hydrodynamics of two-phase flow (gas and liquid) through a packed column in zero-gravity. The gas and liquid flow simultaneously through the interstices of a column packed with 3 mm diameter spheres. The information from this experiment is needed to design equipment for mass and/or heat transfer where gas and liquid flow simultaneously in zero-gravity.Principal Investigator(s)
ZIN Technologies Incorporated, Cleveland, OH, United States
National Aeronautics and Space Administration (NASA)Sponsoring Organization
Technology Demonstration Office (TDO)Research Benefits
Information PendingISS Expedition Duration:
Information PendingPrevious ISS Missions
Currently, there are no design methodologies for two-phase flow in packed beds in zero-gravity. Consequently, two-phase flow equipment for space applications cannot be optimally designed, leading to excess weight and energy consumption from overdesign.
Our results will provide engineers with rules to design more efficient equipment for heat/mass transfer in space.
The impact of this research is scientific, technological and economic. Scientifically and technologically, it will allow for more optimally designed equipment for reactors, strippers, scrubbers and other common chemical engineering units to be used in, for example, water recovery, planetary surface processing and oxygen production. Availability of this equipment will permit planners to conceive longer duration space missions not possible today. On the economic side, optimal designs are lighter and more efficient, thus leading to savings in launch, energy use and maintenance costs.
A basic understanding of two-phase flows through porous media is of interest in many chemical and biological processing systems as well as many geophysical applications. NASA technologies include adiabatic two-phase flows or two-phase flows with heat transfer that are relevant to life support systems, fuel cells, in-situ resource utilization, heat pipes, materials processing, production of pharmaceutical grade water, and transport of nutrients in soils. A very important unit operation that involves gas-liquid flow through porous media is the fixed Packed Bed Reactor (PBR). Examples of current space systems in which a fixed PBR is used include the Volatile Removal Assembly (VRA), the Integrated Advanced Water Recovery System (AWRS), and IntraVenous Water GENeration system (IVGEN). NASA is currently operating systems with packed bed reactors for ground and flight-based testing with little understanding of how the reduced gravity environment affects the performance and reliability of these reactors. This is especially critical when gas-liquid flows are involved. The expected outcome of this research effort is to develop a set of guidelines and tools to enable engineers to reliably design and operate packed bed reactors for microgravity as well as the lunar and Martian environments.
Existing approaches for predicting the flow regimes and pressure drop for gas-liquid flow through a PBR are valid only for 1-g, and are based on liquid (or gas) holdup within the bed. Initial microgravity tests conducted in the reduced gravity aircraft and drop tower clearly show that the liquid holdup is significantly influenced by gravity. Furthermore, most of these models have only been verified using the "trickle flow" regime which does not exist in microgravity. Basic hydrodynamic models developed specifically for reduced gravity have been partially validated within the constraints of aircraft and ground facilities. However, typical flow ranges used for real systems require up to several minutes to develop fully which is far beyond the time scales available for ground tests. In addition, instabilities and hysteresis effects that may exist require long testing durations to establish new operating conditions. Thus, testing on the ISS is required for complete validation of the semi-empirical models.
The flight experiment will provide critical hydrodynamic information for a project with a broader scope which includes reduced gravity aircraft and ground-based (1-g) experiments. The main objective of the overall project is to develop and validate macroscopic equations that can be used in partial and microgravity conditions to accurately predict flow pattern transitions; pressure drops; and mass transfer rates in chemical and biological reactors in which gas-liquid flows occur through randomly packed beds. The hydrodynamic investigations addressed in this experiment will focus on the transitions between flow regimes (e.g., bubbly-to-pulse flow transition) and the associated pressure gradients over the range of relevant operating regimes of the PBRs (e.g., liquid and gas flow rates, particle sizes, and fluid viscosities). These design tools will provide a fundamental understanding of these phenomena in low gravity.
The results will be used to formulate design methods for gas-liquid packed bed operations in zero gravity. By making the operations more efficient, reductions in weight, energy consumption and maintenance time can be achieved.Earth Applications
The insight gained from our zero-gravity investigation of two-phase flow through packed columns will increase the physical understanding of two-phase flow in general, thus benefitting earth-bound design and manufacturing as well.
Information PendingOperational Protocols
Balakotaiah , Kamotani Y, Motil BJ. Gas-Liquid Two-Phase Flows Through Packed Beds in Microgravity. American Institute of Chemical Engineers Journal. 2003 Mar; 49(3): 557-565. DOI: 10.1002/aic.690490303.
Revankar ST, Olenik DJ, Jo D, Motil BJ. Local Instrumentation for the Investigation of Multi-Phase Parameters in a Packed Bed. Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering. 2007 November 1; 221(4): 187-199. DOI: 10.1243/09544089JPME142.