External Tank Research Articles

Mathematical model of a thermosyphon integrated storage solar collector

Abstract Thermosyphon solar collectors are popular in warm climates since their initial and operating costs are lower compared to forced-circulation units. Recently new types of thermosyphon collector with integrated storage, without any external tank, to meet law requirements about solar applications in restricted areas (e.g. old town of particular architectural significance) are put in the market. Such a collector is modelled in this paper using the software MATLAB Simulink. This model is able to describe the transient behavior of the natural circulation phenomenon and it requires a much lower computational effort compared to CFD codes. The present mathematical model has been validated using ad-hoc experimental tests and numerical simulations. The validated model has been run varying the tilt angle, the geometry and the working conditions to analyze the solar thermosyphon performance. It can predict the minimum inclination and solar radiation that is needed to promote the flow circulation.

Simulation and design of a three-stage metal hydride hydrogen compressor based on experimental thermodynamic data

A semi-empirical method was developed to design a three stage Metal Hydride Hydrogen Compressor (MHHC) through the determination of thermodynamic properties of several hydrides. As a first step, three AB2-type alloys that satisfy operation conditions were selected from published thermodynamic data entailing over 200 single plateau hydrides. These alloys were synthetized by arc melting and characterized by X-Ray Powder Diffraction (XRPD), Scanning Electron Microscopy (SEM) and Energy Dispersion X-ray spectroscopy (EDX). Absorption and desorption Pressure-composition-Isotherms (P-c-I) were determined between 23 and 80 °C to characterize their thermodynamic properties. Subsequently, an algorithm that uses these experimental data and a real equation of state for gaseous H2 was implemented to simulate the volume, alloy mass, pressure and temperature of operation for each compressor stage, while optimizing the compression ratio and total number of compressed H2 moles. Optimal desorption temperatures for the three stages were identified within the range of 110–132 °C. A system compression ratio (CR) of 92 was achieved. The number of H2 moles compressed, the alloy mass and volume of each stage depend linearly on the volume of the external tank in which the hydrogen is delivered.

Physiological Assessment of Engagement during HRI: Impact of Manual vs Automatic Mode

Physiological Assessment of Engagement during HRI: Impact of Manual vs Automatic Mode

Investigation of solid nitrogen for cryogenic thermal storage in superconducting cable terminations for enhanced resiliency

Low heat capacity of helium makes the helium gas cooled high temperature superconducting (HTS) power devices susceptible to large temperature rises during unexpected heat loads such as electrical faults or cryogenic system failures. Cryogenic thermal storage in the form of solid nitrogen designed in the terminations is explored as a means to increase the thermal stability and operational time of HTS power cables in the event of unexpected heat loads. An external tank containing activated charcoal is used as an adsorption buffer tank for nitrogen gas. The use of activated charcoal minimizes the volume of the buffer tank and prevents pressure rises during melting and boiling of the solid nitrogen. Calculations of the cryogenic thermal storage needed and a description of the experimental setup used to understand the design constraints are discussed.

Cathodic Protection Design Algorithms for Refineries Aboveground Storage Tanks

Storage tanks condition and integrity is maintained by joint application of coating and cathodic protection. Iraq southern region rich in oil and petroleum product refineries need and use plenty of aboveground storage tanks. Iraq went through conflicts over the past thirty five years resulting in holding the oil industry infrastructure behind regarding maintenance and modernization. The primary concern in this work is the design and implementation of cathodic protection systems for the aboveground storage tanks farm in the oil industry.
 Storage tank external base area and tank internal surface area are to be protected against corrosion using impressed current and sacrificial anode cathodic protection systems. Interactive versatile computer programs are developed to provide the necessary system parameters data including the anode requirements, composition, rating, configuration, etc. Microsoft-Excel datasheet and Visual Basic.Net developed software were used throughout the study in the design of both cathodic protection systems.
 The case study considered in this work is the eleven aboveground storage tanks farm situated in al-Shauiba refinery in southern IRAQ. The designed cathodic protection systems are to be installed and monitored realistically in the near future. Both systems were designed for a life span of (15-30) years, and all their parameters were within the internationally accepted standards.

Activated Sludge Mineralization and Solutions in the Process of Zero-Valent Iron Autotrophic Denitrification

We studied the inoculation of activated sludge from domestic sewage treatment plants. The reaction of reducing nitrate by zero-valent iron was started in the up-flow anaerobic reactor. After 52 d of operation, a nitrogen removal rate of 29.3 g·(m3·d)-1 was achieved. Ferric iron and iron oxide coated on the sludge formed in the operation process caused the mineralization and slowly decreased the sludge activity. The methods of the "supplement and replacement of the sludge in the reactor" and "changing the reflux mode of the reactor" were applied. Using the method of the supplement and replacement of the sludge in the reactor, by discharging a part of the sludge in the reactor and adding the extra dosage from the anaerobic denitrifying sludge for the treatment of wastewater, after 22 d of operation, the conversion rate of nitrate-nitrogen was 33.0 g·(m3·d)-1 and the concentration of nitrite-nitrogen was 16.50 mg·L-1. The effluent average concentration of ammonia-nitrogen decreased from 12.38 mg·L-1 to 3.58 mg·L-1 and the nitrogen removal rate was recovered from 9.9 g·(m3·d)-1to 15.0 g·(m3·d)-1. The biological reaction weakened the chemical reduction of nitrate by zero-valent iron. Using the method of changing the reflux mode of the reactor, the reflux tank was arranged outside the reaction column using hydraulic circulation. The increase in the erosion of the upper layer of the sedimentation tank would bring out ferric iron and iron oxide with the outflow water and they would be deposited in the reflux tank. The corresponding ferric iron of transformation of nitrate settled in the external reflux tank was 58% at the ascending velocity of 3.49 m·h-1. The nitrate-nitrogen conversion rate was 34.3 g·(m3·d)-1, the effluent concentration of nitrite-nitrogen was 0.22 mg·L-1, and ammonia-nitrogen was 0.75 mg·L-1. Ammonia and nitrite did not extensively accumulate. The nitrogen removal rate was 33.4 g·(m3·d)-1, which solved the problem of the mineralized sludge in the long-term reactor operation. In summary, the method of reforming the reflux mode of the reactor performed better than the method of the supplement and replacement of sludge in the reactor.

Estimation of Design Parameters of Single-Phase Distribution Transformers From Terminal Measurements

In this paper, a novel method is proposed for the estimation of the design parameters of single-phase distribution transformers using data acquired from terminal measurements along with nameplate data and external tank dimensions. Transformer parameters that can be measured from terminals, for example, leakage inductance, saturation inductance, and winding resistance, are considered first. These parameters are analytically correlated with the geometrical information of the transformer structure. A system of nonlinear equations is derived accordingly. Winding dimensions and the number of turns are computed with acceptable engineering accuracy. The core dimensions (including its cross-sectional area) are calculated using winding information. The obtained data can be utilized to develop white- or gray-box models to be used in the investigation of the thermal and/or electromagnetic behavior of power transformers as presented in several research studies published to date. Examples on laboratory and utility-grade transformers are shown for illustration and validation of the proposed design parameter estimation method.

New MEG injection system with a seabed storage tank assisted by ship transportation

This study develops a new concept for a mono-ethylene glycol (MEG) injection system with ship-based transportation to provide an alternative to conventional MEG injection systems with pipeline-based transportation. An economic analysis is performed to prove the feasibility of the suggested concept, which consists of a seabed storage tank, MEG carrier, and a floater. A novel pressure-balancing concept is presented for application in the seabed storage tank in which seawater can both enter and exit so the internal and external tank pressures are balanced. The seabed storage tank consists of a storage unit, ballast unit, and seawater cleaning unit. An assessment of the economic feasibility of the proposed concept is performed, revealing that it is economically feasible for shipping distances greater than 200km. Sensitivity studies demonstrate that a decrease in the shipping fuel costs significantly decreases the threshold shipping distance, but a decrease in the production rate increases the threshold shipping distance.

Study on Intelligent Fire Fighting System for Large External Floating-roof Tank

Fire on sealing ring is the main fire form of large external floating-roof tanks. Once fire occurs on the large-scale external floating-roof tank ring, the existing fixed fire extinguishing equipment cannot put out the fire quickly and efficiently, which would result in giant losses. The fire signal can be detected, the fire source can be located automatically and the fire can be extinguished precisely through the combination of the applicable imagine fire monitoring system of the intelligent fireextinguishing system and the automatically fire-fighting gun control system. The capacity of self-explosion prevention and control, fire control and extinguishing of the large scale oil tank will be promoted by extinguishing the fire at the early stage, which will ensure the safety of the operation of the large scale oil tank storage base.

A Lithium/Polysulfide Battery with Dual-Working Mode Enabled by Liquid Fuel and Acrylate-Based Gel Polymer Electrolyte

The low density associated with low sulfur areal loading in the solid-state sulfur cathode of current Li-S batteries is an issue hindering the development of this type of battery. Polysulfide catholyte as a recyclable liquid fuel was proven to enhance both the energy density and power density of the battery. However, a critical barrier with this lithium (Li)/polysulfide battery is that the shuttle effect, which is the crossover of polysulfides and side deposition on the Li anode, becomes much more severe than that in conventional Li-S batteries with a solid-state sulfur cathode. In this work, we successfully applied an acrylate-based gel polymer electrolyte (GPE) to the Li/polysulfide system. The GPE layer can effectively block the detrimental diffusion of polysulfides and protect the Li metal from the side passivation reaction. Cathode-static batteries utilizing 2 M catholyte (areal sulfur loading of 6.4 mg cm-2) present superior cycling stability (727.4 mAh g-1 after 500 cycles at 0.2 C) and high rate capability (814 mAh g-1 at 2 C) and power density (∼10 mW cm-2), which also possess replaceable and encapsulated merits for mobile devices. In the cathode-flow mode, the Li/polysulfide system with catholyte supplied from an external tank demonstrates further improved power density (∼69 mW cm-2) and stable cycling performance. This novel and simple Li/polysulfide system represents a significant advancement of high energy density sulfur-based batteries for future power sources.

Electrolyte Pumping Optimization in Already Manufactured Vanadium Redox Battery Based on Experimentally Determined Electrical and Hydrodynamic Losses

AbstractHerein is presented an optimization of electrolyte pumping systems in industrial vanadium redox flow batteries (VRBs). The main advantages of the VRB relate to its prolonged service life, outstanding dynamic response, and flexible controllability during charge/discharge processes. In spite of their exceptional electrical parameters, VRBs suffer from significant energy requirements in the hydraulic pumping system needed for circulation of electrolyte from external tanks to battery cells. The industrial VRB equipped for this purpose with centrifugal driven by controllable electric motors hydraulic pumps were made from plastic components and able to work in the aggressive acid electrolyte. Electrolyte flow is carried out through the entire hydraulic system and battery cells containing carbon electrodes and providing electrochemical reduction-oxidation reactions of vanadium ions. Currently, electrodes in the VRB are made from carbon felt material because its porous structure possesses high specific su...

An Innovative Semi-Solid Lithium Redox Flow Air (O2) Battery Concept

Worldwide, national energy policies are based on fossil fuels, with subsequent concerns about CO2-related global warming. Efforts are hence devoted to promote an efficient use of renewable energy sources and a sustainable electric transportation. This in turns requires high efficiency, energy storage/conversion systems, like batteries. Li-ion batteries (LIBs) and Redox flow batteries (RFBs) are playing a key role for the development of electric vehicles and the exploitation of intermittent and decentralized sustainable energy sources. In order to increase energy and power of both LIBs and RFBs, advancements in materials, design and concepts with attention to costs, safety and reliability are hence required. Coupling an O2-cathode with a lithium anode gives one of the highest performing metal/air battery chemistry towards a next generation of battery. Furthermore, the need to decouple energy from power and to decrease the amount of inactive components is triggering the research in the development of semi-solid, fluidic electrodes where electroactive species are dispersed in the electrolytes instead to be included in a solid electrode. In Li/O2 batteries, O2 redox reaction (ORR) takes place at the solid electrode/electrolyte interface, involving the formation of insulating superoxide and peroxide of lithium that clog the electrode, highly increasing recharge overpotentials and determining battery losses. Cathode passivation by discharge products is one of the most serious drawbacks of such batteries, along with the slow O2mass transport, which in the case of air breathing cells, limits current densities to one order of magnitude lower than the values for commercial LIBs [1]. In order to obviate these issues, novel configurations of Li/O2 battery, like the Li Redox Flow Air Battery (LRFAB), are under development [2, 3]. The use of an O2- based catholyte that is continuously fed with O2, from air or from an external O2 tank, renders cell discharge capacity less dependent on catholyte volume with respect to conventional RFBs. Indeed, the electrolyte is only a carrier for O2and this is beneficial to size and weight reduction. The use of semi-solid electrodes has been shown to be successful for Li-ion, Li/polysulfides, Na-ion flow batteries and for flow supercapacitors [4-7]. These studies pointed to the demonstration that changing cell configuration by substituting solid electrodes with semi-solid, fluidic slurries is an effective strategy that improves battery rate response. Here, we report a new battery concept, a non-aqueous Semi-Solid Lithium Redox Flow Air (O2) Battery (SLRFAB) [8-9]. The catholyte is a suspension of high surface area carbon in O2-saturated non-aqueous electrolyte. Oxygen reduction takes place on the semi-solid electroactive particles dispersed in the catholyte, avoiding the electrode passivation, enhancing the capacity and, in turn, the delivered energy. Exceptionally high capacity is achieved at voltages >2.6 V vs Li/Li+ and high discharge rates (> 2.5 mA cm-2) of interest for practical applications. The results of the galvanostatic tests at different currents are here reported as well as the strategies to reach and overcome practical specific energies of 500 Wh kg-1are discussed. Aknowledgements Alma Mater Studiorum –Università di Bologna is acknowledged for financial support (RFO, Ricerca Fondamentale Orientata).

Influence of Tool Rotational Speed on the Mechanical Properties of Friction Stir Welded Al-Cu-Li Alloy

Aluminum-Lithium alloys have been found to exhibit superior mechanical properties as compared to the conventional aerospace aluminum alloys in terms of high strength, high modulus, low density, good corrosion resistance and fracture toughness at cryogenic temperatures. Even though they do not form low-melting eutectics during fusion welding, there are still problems like porosity, solidification cracking, and loss of lithium. This is why solid state friction stir welding is important in this alloy. It is known that using Al-Cu-Li alloy and friction stir welding to super lightweight external tank for space shuttle, significant weight reduction has been achieved. The objective of this paper is to investigate the effect of friction stir tool rotation speed on mechanical and microstructural properties of Al-Cu-Li alloy. The plates were joined with friction stir welding process using different tool rotation speeds (300-800 rpm) and welding speeds (120-420 mm/min), which are the two prime welding parameters in this process.

A Novel, Semi-Solid Li/O2 Redox Flow Battery

Li-ion batteries (LIBs) and Redox flow batteries (RFBs ) are playing a key role for the development of electric vehicles and the exploitation of intermittent and decentralized renewable energy sources. Efforts are being devoted to advancements in materials, concepts, and design for the increase of energy and power of both lithium batteries and RFBs with attention to costs, safety and reliability. Coupling an O2-cathode with a Lithium anode gives one of the highest performing metal/air battery chemistry and the need to decouple energy from power and to decrease the amount of inactive components has triggered research in the development of semi-solid, fluidic electrodes. Cathode passivation by discharge products is one of the most serious drawbacks of Li/O2 batteries, along with the slow O2 mass transport which in the case of air breathing cells limits current densities to one order of magnitude lower than the values for commercial LIBs [1]. In order to obviate these issues, novel configurations of Li/O2 battery, like the Li Redox Flow Air Battery (LRFAB), are under development [2, 3]. The use of an O2- based catholyte that is continuously fed with O2, from air or from an external O2 tank, renders cell discharge capacity less dependent on catholyte volume with respect to conventional RFBs. Indeed, the electrolyte is only a carrier for O2and this is beneficial to size and weight reduction. The use of semi-solid electrodes has been shown to be successful for Li-ion, Li/polysulfides, Na-ion flow batteries and for flow supercapacitors [4-7]. These studies pointed to the demonstration that changing cell configuration by substituting solid electrodes with semi-solid, fluidic slurries is an effective strategy that improves battery rate response. Here, we report a new battery concept, a non-aqueous semi-solid flow Li/O2 [8-9]. The catholyte is a suspension of high surface area carbon in O2-saturated non-aqueous electrolyte. Oxygen reduction takes place on the semi-solid electroactive particles dispersed in the catholyte, avoiding the electrode passivation, enhancing the capacity and, in turn, the delivered energy. Exceptionally high capacity is achieved at voltages >2.6 V vs Li/Li+ and high discharge rates (> 2.5 mA/cm2) of interest for practical applications. The results of the galvanostatic tests at different currents are here reported as well as the strategies to reach and overcome practical specific energies of 500 Wh kg-1are discussed. Aknowledgements Alma Mater Studiorum –Università di Bologna is acknowledged for financial support (RFO, Ricerca Fondamentale Orientata).

Advanced Modeling of New Batteries

Flow batteries, capable of storing large quantity of energy, have great potential to increase the flexibility of power systems and improve dynamic response to energy demand. Flow batteries are a rechargeable electrochemical energy system, in which electrolytes contain one or more dissolved electroactive species, and the chemical energy in electrolytes is reversibly converted to electricity. The fuel electrolyte is stored externally in a tank, and delivered to the reactor. Batteries can be recharged by replacing electrolytes, similar to conventional vehicles, or by external electric power that is similar to secondary batteries. Flow battery technology offers advantages in energy storage and conversion, including: 1.) large capacity (determined by the external tank volume); 2.) negligible degradation when left completely discharged for long periods; 3.) charge/recharge through electrolyte replacement or external power source; and 4.) no permanent damage when electrolytes are accidentally mixed. Among the major types of flow batteries, the vanadium redox flow battery is a type of rechargeable flow battery that employs vanadium ions at different oxidation states to store chemical potential energy. Lithium-based batteries have received a great deal of research attention in recent years owing to their relatively high efficiency and energy density. A major hurdle to their development, however, is the insufficient low energy capability as opposed to fossil fuels. The gasoline’s specific energy is about 13,000 Wh/kg, an order-of-magnitude higher than that of Li-ion batteries. Li-air batteries are an emerging area with a great promise of high specific energy storage. Their theoretical specific energy reaches around 11,680 Wh/kg, comparable to gasoline and higher than methanol. Their unique feature is that the cathode active material--oxygen is obtained from the ambient environment, and the anode uses lithium metal, rather than Li intercalated graphite (LiC6) as that in Li-ion batteries. Air cathodes are a major area of study in non-aqueous Li-air battery. In cathodes, Li compounds such as Li2O2 or Li2CO3 are produced during discharging. These substances in general have low solubility in major non-aqueous electrolytes, therefore precipitate at the reaction surface. They are also poor electric conductor, causing electrode passivation. As discharging proceeds, the precipitates accumulate inside the pore network, deteriorating voltage drop. In this talk, I will discuss the ongoing work of modeling development on RFBs and Li-air batteries at UCI. The models are formulated by rigorously accounting for the conservation of mass, momentum, species, charges, and energy, in conjunction with the electrochemical reaction kinetics of vanadium RFBs and Li-air batteries. I will emphasize the similarity and difference in modeling the two types of new battery systems. The models are validated against experimental data.

Investigation of Microstructure in Solid State Welded Al-Cu-Li alloy

Al-Li alloys have been extensively used in aerospace vehicle structure since the presence of lithium increases the modulus and reduce the density of the alloy. Especially the third generation Al-Cu-Li alloy shows enhanced fracture toughness at cryogenic temperatures so that the alloy has been used on the fuel tank of space launchers, like Super Lightweight External Tank of the Space Shuttle. Since the commercial size of the plate cannot accommodate the large tank size of the launcher, joining several pieces is required. However, lithium is highly reactive and its compounds can decompose with heat from conventional fusion welding and form different types of gases which result in formation of defects. In this study, the microstructure change is investigated after solid state welding process to join the Al-Cu-Li sheets with optical and transmission electron microscopic analysis of precipitates.

Ex vivo expansion of hematopoietic stem cells in a proliferation chamber with external stirred conditioning tank: Sequential optimization of growth factors

The insufficient number of hematopoietic stem cells (HSCs) extracted from various cell sources creates the need for the use of growth factors in the culture systems. Numerous types and concentrations of growth factors have been reported in the literature. In this study, we investigated the effect of three important hematopoietic growth factors thrombopoietin (TPO), stem cell factor (SCF), and Fms‐like tyrosine kinase‐3 ligand (Flt‐3) as well as cell‐seeding density on ex vivo expansion of human HSCs using a factorial design. Sequential optimization was then followed by methods of steepest ascent and central composite design. The optimum concentrations of growth factors were 50, 90, and 34 ng/mL for SCF, TPO, and Flt‐3, respectively, at an initial cell density of 2.5 × 105 cells/mL. Effective expansion factor value (EEF) of HSCs increased considerably and revealed almost similar results when the cells were cultured in a 24‐well plate (EEF = 4.54 ± 0.43) and a proliferation chamber with an external stirred conditioning tank (PC‐ESCT; EEF = 5.1 ± 0.35) at seeding density of 2.5 × 105 cells/mL after 7 days. The cells did not show considerable changes in proliferation when they were cultured in medium containing serum or in a commercial serum‐free medium at the optimum concentrations of the growth factors. The present study demonstrated the optimum condition of hematopoietic growth factors as well as the potential of PC‐ESCT for ex vivo expansion of HSCs.

Experiments and simulations on a thermosyphon solar collector with integrated storage

This paper deals with the thermal behaviour of a new type of flat solar collector that integrates the fluid storage tank. Often the main limitation of the solar thermosyphon installations is the prohibition to adopt external storage tanks due to their impact, especially for historical centres of particular architectural significance. To avoid this issue, a new system, that includes the collector and the storage, has been developed. This new apparatus works as a thermosyphon: it is possible to take advantage of the natural convection to avoid using a pump. Experimental tests have been conducted in such a collector with and without the absorbing plate. Furthermore, CFD simulations are reported to analyze in detail the dynamic thermal performance of the innovative solar collector and a good-agreement with the experimental tests has been found. Finally, both in numerical simulations and in experimental data the thermosyphon effect has been verified, obtaining the desired water temperature for domestic applications.

Cell design concepts for aqueous lithium–oxygen batteries: A model-based assessment

Seven cell design concepts for aqueous (alkaline) lithium–oxygen batteries are investigated using a multi-physics continuum model for predicting cell behavior and performance in terms of the specific energy and specific power. Two different silver-based cathode designs (a gas diffusion electrode and a flooded cathode) and three different separator designs (a porous separator, a stirred separator chamber, and a redox-flow separator) are compared. Cathode and separator thicknesses are varied over a wide range (50 μm–20 mm) in order to identify optimum configurations. All designs show a considerable capacity-rate effect due to spatiotemporally inhomogeneous precipitation of solid discharge product LiOH·H2O. In addition, a cell design with flooded cathode and redox-flow separator including oxygen uptake within the external tank is suggested. For this design, the model predicts specific power up to 33 W/kg and specific energy up to 570 Wh/kg (gravimetric values of discharged cell including all cell components and catholyte except housing and piping).

Catholyte Development for Non-Aqueous Redox Flow Batteries

Non-aqueous redox flow battery is a promising large scale stationary energy storage technology. Unlike traditional battery systems, the active energy storage material is in mobile phase and stored in external tanks. The energy and power of RFBs thus can be decoupled and independently scaled, which offers remarkable design flexibility for applications with various energy-to-power ratios. Material development for this technology is crucial for practical implementation. Molecular engineer of organic redox active molecules could lead to tunable physical and electrochemical properties, including solubility in organic solvents, molecular mobility, redox potential, and electrochemical reversibility, which are key factors to energy storage applications. The dimethoxybenzene based catholyte molecules have been systematically developed and evaluated towards various purposes. For instance, ANL-8, ANL-9 and ANL-10 molecules were developed by incorporation of PEO chains with different lengths on one or both sides of the dimethoxy-di-tert-butyl-benzene based redox structure in order to afford higher solubility. Another category of the molecules, including JH-100 and JH-200, were developed by striping down the non-essential structures, such as tert-butyl groups and ether chains, in order to boost the intrinsic capacities. While many of these molecules can afford electrochemically reversible behavior, some new promising features are discovered. ANL-8 and ANL-9 molecules are found to be liquid at room temperature, which was hoped to function as co-solvent for NRFBs, thus leading to much improved energy density. JH-100 and JH-200 molecules, on the other hand, offer much enhanced intrinsic capacity (nearly two times as big as DBBB), which also is believed to be a key to further improve the energy density and lower the cost of NRFBs.