Bulletin of the American Physical Society
69th Annual Meeting of the APS Division of Fluid Dynamics
Volume 61, Number 20
Sunday–Tuesday, November 20–22, 2016; Portland, Oregon
Session R2: Industrial Application: General |
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Chair: Sara Rimer, University of Michigan Room: A106 |
Tuesday, November 22, 2016 1:30PM - 1:43PM |
R2.00001: Flow Control of Hazardous Contaminants to Protect Evacuees in Civil Infrastructure Emergency Scenarios Sara Rimer The threat of accidental or deliberate toxic chemicals released into public spaces is a significant concern to public safety, and the real-time detection and mitigation of such hazardous contaminants has the potential to minimize harm and save lives. Furthermore, the safe evacuation of occupants during such a catastrophe is of utmost importance. This research develops a comprehensive means to address such scenarios, through both the sensing and control of contaminants, and the modeling of and potential communication to occupants as they evacuate. A computational fluid dynamics model is developed of a simplified public space characterized by a long conduit (e.g. airport terminal) with unidirectional ambient flow that is capable of detecting and mitigating the hazardous contaminant (via boundary ports) over several time horizons using model predictive control optimization. An agent-based model is developed to simulate ‘agents’ (i.e. building occupants) as they evacuate a public space. The agent-based evacuation model is coupled with the computational flow control model such that agents must interact with a dynamic, threatening environment. Results demonstrate how flow control can be achieved via feedback sensing of location of occupants with desire to minimize contaminant exposure. [Preview Abstract] |
Tuesday, November 22, 2016 1:43PM - 1:56PM |
R2.00002: Computational study of liquid-gas cross-flow within structured packing cells Gianluca Lavalle, Mathieu Lucquiaud, Prashant Valluri Absorption columns used in the carbon capture processes and filled with structured packings are crucial to foster the exchanges and the transfers between the absorber liquid and the flue gas. However, flow reversal can occur under special flow conditions, resulting in a dramatic drop of the technological performances. We investigate numerically the liquid-gas pattern within a cross-flow packing cell. The cell is a complex geometry with two connected channels, where the two phases flow co- or counter-currently. We show that an increase of both the gas speed and the liquid load leads to an increase of the pressure drop. Particular focus is also given to the analysis of flow repartition and flooding delay. We reveal that tilting the unit cell helps to delay the flooding and extends the operational capability. The pressure drop of the cross-flow unit cell is also compared to the Mellapak packing which is widely used in carbon capture applications. Finally, we support this study by performing numerical simulations on simpler geometries by means of a low-dimensional film-gas model, in order to investigate the two-phase dynamics and predict the flooding onset with a low computational cost. [Preview Abstract] |
Tuesday, November 22, 2016 1:56PM - 2:09PM |
R2.00003: Design of container velocity profile for the suppression of liquid sloshing Dongjoo Kim In many industrial applications, high-speed position control of a liquid container causes undesirable liquid vibrations called `sloshing' which poses a control challenge in fast maneuvering and accurate positioning of containers. Recently, it has been shown that a control theory called `input shaping' is successfully applied to reduce the sloshing, but its success comes at a cost of longer process time. Therefore, we aim to minimize liquid sloshing without increasing the process time when a container moves horizontally by a target distance within a limited time. In this study, sensing and feedback actuation are not permitted but the container velocity is allowed to be modified from a given triangular profile. A new design is proposed by applying input shaping to the container velocity with carefully selected acceleration time. That is, the acceleration time is chosen to be the 1st mode natural period, and the input shaper is determined based on the 3rd mode natural frequency. The proposed approach is validated by performing numerical simulations, which show that the simple modification of container velocity reduces the sloshing significantly without additional process time in a feedforward manner. [Preview Abstract] |
Tuesday, November 22, 2016 2:09PM - 2:22PM |
R2.00004: Sloshing motion dynamics of a free surface in the draft tube cone of a Francis turbine operating in synchronous condenser mode Elena Vagnoni, Lo\"ic Andolfatto, Arthur Favrel, Fran\c{c}ois Avellan The penetration of the electrical grid by intermittent renewable energy sources induces grid fluctuations which must be compensated in order to guarantee the stability of the grid. Hydropower plants can supply reactive power to ensure the grid stabilization by operating in condenser mode. In this operating mode, the turbine operates with the tail water depressed to let the runner spin in air to reduce the power consumption. Pressurized air is injected in the draft tube cone to maintain the water level below the runner and this induces air-water interaction phenomena which cause important power losses. Flow visualization and pressure fluctuation measurements are performed in a reduced scale physical model of a Francis turbine operating in condenser mode to investigate the dynamics of the air-water interaction in the draft tube cone which causes the sloshing motion of the free surface. An image post-processing method is developed, enabling a quantitative description of the sloshing motion. The latter depends on the Froude number. By increasing the value of the Froude number, the amplitude of the sloshing motion decreases, as well as the amplitude of the pressure fluctuations. The frequency of the sloshing motion corresponds to the first natural frequency of the water volume. [Preview Abstract] |
Tuesday, November 22, 2016 2:22PM - 2:35PM |
R2.00005: Design and development of low pressure evaporator/condenser unit for water-based adsorption type climate control systems. ARJUN VENKATARAMANAN, Carlos A. Rios Perez, Carlos H.Hidrovo Electric vehicles (EVs) are the future of clean transportation and driving range is one of the important parameters which dictates its marketability. In order to increase driving range, electrical battery energy consumption should be minimized. Vapor-compression refrigeration systems currently employed in EVs for climate control consume a significant fraction of the battery charge. Thus, by replacing this traditional heating ventilation and air-conditioning system with an adsorption based climate control system one can have the capability of increasing the drive range of EVs.The Advanced Thermo-adsorptive Battery (ATB) for climate control is a water-based adsorption type refrigeration cycle. An essential component of the ATB is a low pressure evaporator/condenser unit (ECU) which facilitates both the evaporation and condensation processes. The thermal design of the ECU relies predominantly on the accurate prediction of evaporation/boiling heat transfer coefficients since the standard correlations for predicting boiling heat transfer coefficients have large uncertainty at the low operating pressures of~the ATB. This work describes the design and development of a low pressure ECU as well as the thermal performance of the actual ECU prototype. [Preview Abstract] |
Tuesday, November 22, 2016 2:35PM - 2:48PM |
R2.00006: Controlled evaporative cooling on a superhydrophilic surface: building a green wall Suin Shim, Sangwoo Shin, Forrest Meggers, Elie Bou-Zeid, Howard A. Stone We propose a way to design of an evaporative cooling device using continuous water flow on a superhydrophilic surface. Continuous flow helps prevent contaminant fouling on the surface of the cooler, which is a major challenge for conventional evaporative (swamp) coolers. A superhydrophilic surface leads to a reduced coolant flow rate, allowing for a maximum ratio of evaporative heat transfer to coolant thermal mass. Also, a staggered structure increases the surface area of the thin film flow of water which results in higher cooling efficiency. We performed both experimental and theoretical studies on the temperature change in the thin film flow of water. By keeping the water film thickness below 100 $\mu$m, $\sim$5 K of temperature drop in the device was achieved. The cooling device can be manufactured using conventional cost-effective processes, offering practical applications in energy-efficient buildings. [Preview Abstract] |
Tuesday, November 22, 2016 2:48PM - 3:01PM |
R2.00007: A new desalination technique using capacitive deionization Mohammad Sajjad Rostamy, Morteza Khashechi, Ehsan Pipelzadeh Capacitive deionization (CDI) is an emerging energy efficient, low pressure and low capital intensive desalination process where ions are separated by a pure electrostatic force imposed by a small bias potential as low as 1 V That funded by an external Renewable (Solar) power supply to materials with high specific surface area. The main objective of this configuration is to separate the cation and anions on oppositely charged electrodes. Various electrode materials have been developed in the past, which have suffered from instability and lack of performance. Preliminary experimental results using carbon black, graphite powder, graphene$\backslash $graphite$\backslash $PTFE (Active$\backslash $Conductive$\backslash $binder), show that the graphene reduced via urea method is a suitable method to develop CDI electrode materials with capacitance as high as 52.2 mg/g for free standing graphene electrode. The focus of these studies has been mainly on developing electrodes with high specific surface area, high capacitance, excellent electronic conductivity and fast charge discharge cycles for desalination. Although some progress has been made, production of efficient and stable carbon based electrode materials for large scale desalination has not been fully realized. [Preview Abstract] |
Tuesday, November 22, 2016 3:01PM - 3:14PM |
R2.00008: ABSTRACT WITHDRAWN |
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