Gas Throughput Research Articles

Optimization of Upstream Natural Gas Compression Processes based on Sensitivity Analysis of Gas Throughput

Optimization of Upstream Natural Gas Compression Processes based on Sensitivity Analysis of Gas Throughput

Effect of Temperature-Induced Aging on the Gas Permeation Behavior of Thin Film Composite Membranes of PIM-1 and Carboxylated PIM-1.

Polymers of intrinsic microporosity (PIMs) are a class of promising gas separation materials due to their high membrane permeabilities and reasonable selectivities. When processed into thin film composite (TFC) membranes, their high gas throughput aligns closely with industrial requirements, but they are prone to physical aging and plasticization effects. TFC membranes based on the prototypical PIM-1 and its carboxylated derivative cPIM-1 exhibit temperature-dependent gas permeation behavior, which has not been extensively studied before. In single CO2 permeation tests, measurable physical aging occurred when the temperature was raised to 55 °C within a period of 90 min, and the aging rate accelerated as temperature was raised further. TFC membranes prepared from cPIM-1 exhibited a faster aging rate compared to PIM-1 at the same temperature. The decreased permeance could be at least partially recovered through a 5 day methanol vapor treatment. In mixed gas experiments, all membranes showed decreased permselectivities at elevated temperatures. The plasticization pressure of TFC membranes occurred at around 1 bar of CO2 partial pressure, independent of temperature. Significant plasticization was particularly evident for cPIM-1 TFC membranes under CO2/CH4 conditions with increasing temperature, which resulted in increased gas permeance for both components.

Case Study: Advanced Technology Underpins Efficiency and Climate-Related Goal Gains

_ Today’s gas-compression operators are under increasing pressure to reduce greenhouse gas (GHG) emissions. Fortunately, multiple technologies are available that can support that objective while enabling operators to move more gas cost-effectively. Embracing such advancements can positively impact a reduced-carbon future without compromising operational efficiency or profitability. To choose the right technologies for a gas-compression package, it’s critical for operators to have a clear understanding of their business and GHG emissions-related goals. Operators also need clarity concerning the impact of evolving requirements on total cost of ownership (TCO) as well as potential financial ramifications. Producing more gas at a lower cost with lower GHG emissions is possible with new technologies. Operators can support their success by choosing the right engine driver for a gas-compression package based on their unique needs and site conditions. It’s critical to consider an engine’s power density and TCO, as that informs an operator’s selections and can lower a gas-compression package’s operating cost in terms of dollars per thousand cubic feet ($/Mcf) of gas throughput. An engine, such as the Cat G3600 A4 Gen 2, that can deliver a 10% power increase compared to the previous model can allow operators to use fewer engines to perform the same amount of work. This advantage can lower capital requirements, reduce operating expenses, and decrease fuel consumption. Fewer engines operating in the field may also contribute to lower GHG emissions. Modernizing Existing Assets Operators prioritize flexibility, durability, and lower TCO. They can support those objectives by choosing an engine platform that allows performance upgrades across the life of the engine. This enables operators to apply advanced technology in their existing fleet year after year without incurring the substantial cost of purchasing a new engine. Engine upgrade kits offer operators an option to maximize and modernize active assets in a streamlined way, as the upgrades can be applied conveniently and cost-effectively at the time of a scheduled overhaul to minimize disruption. For example, by using an upgrade kit for an A4 Gen 1 engine model referenced above, operators can lower volatile organic compounds up to 32%, formaldehyde up to 24%, carbon monoxide up to 13%, methane emissions up to 33%, and total GHG emissions up to 5% on a grams per brake horsepower-hour (g/bhp-hr) basis* while saving the traditional capital expenditure of a new engine. (*Site conditions: Same power level between the G3600 A4 Gen 1 and Gen 2, 85MN, 905 BTU/scf, 100% load, 25°C ambient, 500-ft altitude.) Such updates are relatively cost neutral when applied as part of a scheduled major overhaul and require minimal or no change to the compression package. This makes upgrade kits a wise choice to ensure equipment keeps pace with industry demands.

Investigations on Hydrogen Isotope Separation Factor Employing Palladium-Based Solid Metallic Membranes

At present, there are several methods for hydrogen isotope separation (in elemental form), the most important being cryogenic distillation, thermal diffusion, and gas chromatography. However, these methods have a series of drawbacks, namely, high complexity, high energy consumption, and associated costs. Taking into account these disadvantages, a promising separation method is the one based on solid metallic membranes because of its advantages like low energy consumption and reduced complexity. This method uses the difference between some of the isotopes’ properties, namely, solubility; diffusivity; and, implicitly, permeability. This work envisages the integration of an isotopic separation module, based on membrane permeation, on the exhaust gas line from the current experimental rigs employed at ICSI, to recover and store the hydrogen isotopes. We obtained a maximum separation factor of 5.66 for the lowest studied concentration of deuterium in the hydrogen isotopic mixture (0.05 atomic fraction). The results show that hydrogen isotope separation is possible using palladium/silver membranes. Still, the throughput of the permeated gas is very low, and a significant number of stages will be necessary to obtain the desired purity (above 99.5%).

Full time-dependent SOLPS-ITER simulation of the SPARC tokamak: actuator design for particle and divertor condition control *

This paper presents the application of full time-dependent SOLPS-ITER simulations for actuator design in the SPARC tokamak. This study employs both the EIRENE module, a neutral solver, and the B2.5 plasma module in a time-dependent mode. This is in contrast to most SOLPS simulations, which focus on steady-state solutions, where the neutral distribution is evolved without any time limit or for a time step of 1 ⋅10−3 second, which is several orders of magnitude larger than the fluid plasma time step. The time-dependent EIRENE was tested with a fixed B2.5 background and compared with a simple conductance based model in a simplified pump chamber geometry. This comparison aimed to verify the reliability of the neutral relaxation timescale derived from the time-dependent EIRENE. Subsequently, a full time-dependent simulation was performed in a realistic geometry, with the Monte-Carlo neutral time step synchronized with the plasma fluid time step. The numerical setup of the code, including relative time steps and the size of the census data used to store Monte-Carlo particle information is considered. The full-time dependent simulations are then applied to inform the design of the SPARC louver structure, which affects divertor plasma parameters by regulating the neutral conductance from the divertor to the pump. The response of the plasma and neutral parameters was captured on a timescale that enables the design of the actuator to consider time-dependent control capability. It was found that changing the louver opacity has an equivalent effect as varying the gas throughput via puff actuation. Therefore, equivalent divertor plasma conditions can be obtained from both actuators, while the neutral pressure distribution in the pump and divertor differs for each actuator.

Assessment of a Full-Electric Floating Liquefied Natural Gas Concept for Harsh Sea State Conditions at Remote Ultra-Deepwater Locations

_ This work describes an offshore gas monetization solution for harsh environmental conditions at ultra-deepwater and remote locations, as an alternative to conventional onshore plants associated with long subsea pipelines for Greenfield projects. Although gas-to-liquids and marine compressed natural gas are initially evaluated, associated gas is supposed to be exported from deepwater floating production storage and offloading units to a central floating liquefied natural gas (FLNG) facility for additional treatment, fractionation, and liquefaction, producing liquefied natural gas (LNG) and liquefied petroleum gas (LPG) for further tandem offloading. To demonstrate the technical feasibility of the proposed FLNG, its key technologies are reviewed, including liquefaction process selection, cargo containment system, station-keeping, offloading, and power generation. A full-electric FLNG is proposed, replacing conventional feed gas power generation systems with inner hull nuclear power modules, envisaging neutral CO2 emissions and earlier first LNG drop milestone achievement. The FLNG general arrangement is developed, along with its internal cargo tanks layout, for preliminary LNG and LPG production rundown and feed gas throughput. Numerical analyses are carried out to show that static and dynamic tilt criteria can be met, even for harsh sea states. Gas import riser configurations for the challenging ultra-deepwater location are outlined, after appropriate FLNG station-keeping analyses, in addition to a feasibility assessment of seawater intake risers, aiming for an overall gas plant efficiency increase. Keywords FLNG; FPSO; LNG/LPG; associated gas; design (general)

Ultra-stable hollow nanotube conjugated microporous polymer incorporating fluorenyl moieties for Co-capture of PM and CO2

Conjugated microporous polymers have a highly delocalized π-π conjugated porous skeleton connected by covalent bonds, which can combine their excellent stability with high adsorption, in order to be applied to the study of co-capture of harmful particulate matter (PM) and carbon dioxide (CO2) under high temperature and high humidity conditions. In this paper, fluorene-based coupled conjugated microporous polymers (D-CMPs) with functionalized hollow nanotubes and abundant microporous structures were proposed. Through mechanism exploration and molecular electrostatic potential (MESP) calculation, the capture efficiency, adsorption capacity and selectivity of PM and CO2 in the waste gas stream of carbon-based combustion were analyzed. The results indicate that D-CMPs, with their rigid carbon-based π-conjugated framework, exhibit excellent tolerance under prolonged high-humidity conditions, with a capture efficiency exceeding 99.87% for PM0.3 and exceeding 99.99% for PM2.5. Meanwhile, based on its chemical/thermal stability, it can realize the recycling of adsorption-regeneration. On this basis, the "slip effect" induced by the open three-dimensional hierarchical porous structure of D-CMPs significantly enhances airflow dispersion and improves gas throughput (with a minimal permeation resistance of only 15 Pa). At a pressure of 1 bar and a temperature of 273.15 K, D-CMP-2 exhibited a CO2 adsorption capacity of up to 2.69 mmol g−1. The fitting results of three isothermal adsorption models demonstrate that D-CMPs exhibit an outstanding equilibrium selectivity towards CO2. Therefore, prior to the widespread adoption of low-carbon and clean energy technologies, porous solid materials exhibiting excellent structural stability, equilibrium selectivity, environmental tolerance, and high adsorption capacity emerge as optimal candidates for the treatment of industrial waste gases.

Assessment of methane emissions from pressure regulation stations in China

Pressure regulation stations are responsible for transporting natural gas downstream and are an indispensable part of the gas supply chain. In recent years, countries and enterprises have attached increasing importance to methane emission accounting. However, methane emissions from pressure regulation stations are still not comprehensively understood and accounted for. In this study, methane emissions from 21 pressure regulation stations under normal conditions were quantified using the Environmental Protection Agency's (EPA's) “Other Test Method 33 A” (OTM 33 A) in three regions of China: the eastern, northern, and central regions of China. The results showed that the emission rate from pressure regulation stations generally lied in the order of 10−1-10−3 kg/h, whereas the measured methane emission rate (MMER) with 95% confidence interval (95%CI) was 0.671 (0.066, 3.040) (kg/h), which was determined from the bootstrapping measurements from all pressure regulation stations. The MMER (95%CI) values were 0.051 (0.026, 0.102) for East China, 2.263 (0.095, 8.317) for North China, and 0.004 (0.003, 0.005) (kg/h) for Central China, showing a relatively obvious skewed distribution. Overall, MMER had a diminutive correlation with gas throughput and pipeline pressure. In contrast, the degree of correlation of pipeline pressure was higher than that of gas throughput.

(Invited) Parametric Investigation of Electrochemical Hydrogen Compression: An Experimental Study

The rising global demand for energy has been primarily met by fossil fuels resulting in environmental threats like global warming and climate change. Hydrogen can play a key role in combating climate change because it represents a carbon-free energy pathway when it is produced renewably. The chemical energy in hydrogen can be converted with high efficiency to electricity using fuel cells with water as the only byproduct. However, the establishment of the hydrogen infrastructure still poses significant challenges, particularly in the area of storage. Due to its low density, hydrogen is difficult to store either as a compressed gas or a liquid. Mechanical compressors are typically used to compress hydrogen, but their complex design and maintenance requirements add to their cost.Electrochemical compression (ECC) represents a viable alternative to mechanical compressors due to its higher efficiency, lack of moving parts, noiseless and vibration-free operation, and modularity. ECC is an electrochemical device that employs a proton exchange membrane (PEM) to compress hydrogen. It operates by applying a voltage across the PEM while supplying low-pressure hydrogen to the anode. The applied voltage initiates the oxidization of hydrogen into protons and electrons. The protons migrate through the PEM towards the cathode, while the electrons are directed towards the cathode through the external circuit by the power source. Upon reaching the cathode, the protons and electrons recombine to produce hydrogen at a higher pressure. Furthermore, ECC offers additional advantages such as the ability to separate and purify hydrogen from a gaseous mixture.For the successful commercialization of ECC, it is essential to achieve high performance with minimal energy consumption. This work presents a detailed parametric investigation of electrochemical hydrogen compression conducted experimentally using a single cell ECC apparatus. The effects of key parameters including voltage, temperature, membrane thickness, and relative humidity on ECC performance are examined for two outlet variables, viz. discharge pressure and gas throughput. We also elucidate the adverse effect of back diffusion due to the high pressure differential between cathode and anode compartments on the overall ECC performance. Various ECC performance metrics such as output pressure, current density, net flux, and compression efficiency are investigated as a function of the operating parameters. The results show that tradeoffs are required to achieve different objectives. For example, operating at a higher voltage is favorable for both discharge pressure and gas throughput but at the cost of reduced ECC efficiency due to increased back diffusion. The results also show that a lower operating temperature favors higher discharge pressures, whereas a higher temperature favors higher gas throughput. Similarly, thinner membranes facilitate a higher gas throughput due to reduced ohmic resistance, while thicker membranes can mitigate back diffusion thereby yielding higher discharge pressures. Furthermore, operating at higher RH is beneficial for both the discharge pressure and gas throughput.These results provide valuable insights on the effect of various operating parameters on ECC performance. This study confirms that back diffusion plays a deleterious role in ECC operation and must be given careful consideration in stack design. Also, novel PEMs with low hydrogen permeability should be identified to optimize ECC performance. The results suggest that ECC is a promising alternative to conventional technologies for hydrogen compression.

Membrane-Fabric Composite Filter Media for Continuous Cake Filtration without Gas Throughput Using Paste Dot Coating with Adhesive.

In the field of liquid filtration, the realization of gas throughput-free cake filtration has been investigated for a long time. Cake filtration without gas throughput would lead to energy savings in general and would reduce the mechanically achievable residual moisture in filter cakes in particular. The reason why gas throughput-free filtration could not be realized with fabrics so far is that the achievable pore sizes are not small enough, and that the associated capillary pressure is too low for gas throughput-free filtration. Microporous membranes can prevent gas flow through open pores and cracks in the filter cake at a standard differential pressure for cake filtration of 0.8 bar due to their smaller pore size. Since large-scale implementation with membranes was not yet successful due to their inadequate mechanical strength, this work focuses on the development and testing of a novel composite material. It combines the advantages of gas throughput-free filtration using membranes with the mechanical stability of fabrics. For the production of the composites, a paste dot coating with adhesive, which is a common method in the textile industry, was used. Based on filtration experiments, delamination and tensile tests, as well as µCT analysis, it is shown that this method is suitable for the production of composite filter materials for gas throughput-free cake filtration.

BFSF: A secure IoT based framework for smart farming using blockchain

Many smart applications, including smart cities, healthcare, smart agriculture, manufacturing, etc., have widely adopted the Internet of Things (IoT). Smart Farming (SF) integrates a set of technologies, such as cloud and edge computing and greenhouse concepts, to improve agricultural processes. Due to its capacity to generate fresh agricultural products at an incredible pace of development and output, the greenhouse business has recently attracted the attention of the farming community. However, the cost of labor and energy consumption causes the greenhouse’s production cost to rise by roughly 40%–50%. To avoid this, SF concepts have been introduced. Data management in SF has received a lot of attention in recent years due to its high potential for more accurate and cost-effective agriculture. Traditional client–server and cloud-based data management systems are plagued by single faults, data protection, centralized data management, and system vulnerabilities. In this paper, an IoT-based framework is proposed for SF to improve the productivity of crops. AI-based precision model is introduced in the framework, which can be integrated with remote sensor data for correct prediction of crop growth in smart agriculture. The result shows that the random forest model works better with 97% accuracy compared to Support Vector Classifier (SVC) have 93%, K-Nearest Neighbors (KNN) have 90%, and Logistic Regression 84%. This technology helps to reduce costs while also improving the overall quality of the agricultural process and product management with blockchain-based supply chain management to enhance farmers’ economic backdrop. The blockchain performance is evaluated on gas consumption, execution time, throughput and latency.

Bifurcation-like transition of divertor conditions induced by X-point radiation in KSTAR L-mode plasmas *

Density ramps with ion grad B drift directed into lower single null KSTAR L-mode plasmas are associated with a simultaneous and abrupt reduction of the divertor particle flux on both low- and high-field-side targets when the mid-plane line averaged electron density reaches a given level. Target embedded Langmuir probe signals show a clear ‘cliff edge’ behavior similar to that observed in the divertor target electron temperature in DIII-D H-mode plasmas (Eldon et al 2017 Nucl. Fusion 57 066039; McLean et al 2015 J. Nucl. Mater. 463 533–6). The collapse of the particle flux is observed along the whole divertor target area (from private flux region to the far scrape-off layer (SOL)). The critical upstream density of this target flux cliff is invariant under fuel gas throughput modulation. The transition along the cliff occurs in tens of milliseconds. With the cliff, carbon impurities and deuterium neutrals transported through the X-point to the core produce a strong radiation spot near the X-point, seen on bolometric signals, and increase the upstream density. The experimental observations are consistent with time-dependent SOLPS-ITER simulations, which also demonstrate an abrupt transition of the target flux and upstream density with the increase in X-point radiation. The timescale of the cliff predicted by SOLPS-ITER is consistent with the experiment, although, it is influenced by gas throughput or time-dependent numerical methods. In the L-mode phase space of separatrix electron density and temperature, branches are divided based on target temperature, because the latter is strongly coupled to the radiation front and ionization front due to the monotonic characteristic of the parallel electron temperature distribution. Since the H-mode condition operates at a much higher upstream density and electron temperature in phase space, dissipation from sputtered carbon alone leads to the density limit before reaching the X-point radiation condition. This is therefore consistent with the fact that cliffs have never been observed in H-mode KSTAR experiments.

0050 Pediatric OSA and neurodevelopment

Abstract Introduction Pediatric OSA and its associated sleep disorders occur in up to 7% of children. Whereas the sequelae of the disease are well characterized, the underpinnings of its phenotypes are poorly understood. This is mainly because of a lack of comprehensive model of the disease in the young. Here I present the neurobehavioral phenotype of pediatric OSA utilizing a preclinical murine model. Methods This proposal represents a departure from prior models and is embedded in the sculpting of the IH model. 1) Human polysomnographic data: We studied human data in children with OSA 2) Murine oximetry data: we create murine oximetry curves 3) Cross Species Curve Fitting: We cross fit those across species 4) Optimization of hypoxic gas throughputs: We then optimized this for the hypoxia chamber we are using Results We examined 4 behavioral tasks over a number of time periods to establish the temporality needed for hippocampal task ablation, as the hippocampus is the center of learning and memory in mammals. 2 tasks were hippocampal dependent: a) Novel object recognition b) Object place recognition. 2 tasks were hippocampal independent: 1) Hot plate: 2) OFA. We utilized 3 time periods initially: exposure from p14 to p23 (9 days acute), to p35 (21 days intermediate), and p70 (56 days, chronic). There was no deterioration in hippocampal tasks from p14 to p35, however at p70 we noted task ablation. We therefore systematically worked backwards, until we discovered the 'tipping point' where hippocampal task ablation is observed is p49 (35 days of exposure). Prior to this, we note no task ablation, however after this time point, hippocampal task ablation is preserved. Conclusion We have demonstrated a tractable, temporal model for pediatric OSA over a systematic set of time points to show when hippocampal deficits from the OSA stimulus manifest phenotypically. We have further isolated these deficits to the hippocampus of developing mice, which is the mammalian center of learning, memory, and retrieval. Support (if any) Arvind has previously received support from AASM and BCM OOR. He is currently supported by 1K08HL161263-01 from NHLBI.

Design of a large nonevaporable getter pump for the full size ITER beam source prototype

An improvement for the vacuum system of the multidriver radio frequency (RF) prototype negative ion source SPIDER has been developed, to allow operating at high RF power, while minimizing the breakdown probability on the outside of the plasma source. A first-of-its-kind large nonevaporable getter (NEG) pump, based on a modular design of 384 cartridges totaling about 350 kg of ZAO® alloy (composed by Zr-Ti-V-Al) with an installed pumping speed at a room temperature of 330 m3/s for hydrogen, will complement the existing pumping system, based on eight cryogenic pumps and four turbomolecular pumps totaling about 90 m3/s in hydrogen. The vessel pressure during absorption is expected to be between 20 and 40 mPa, while during the getter regeneration, the peak operating pressure will be around 2 Pa. The NEG pump will use an additional vessel module, with integrated thermal shields to protect the in-vessel components during activation and regeneration of the pump, to be carried out at temperatures in the range of 550–600 °C. Integrated thermal analyses were carried out to verify the low heat load on pre-existing in-vessel components with a low limit of acceptable temperature, and to provide boundary conditions for the mechanical verifications of the pump structure. The scenario of cyclic hydrogen load was calculated considering the SPIDER operation modes, the expected gas throughput, and the cumulated load to the pump, to determine the regeneration temperature and auxiliary pumping necessary to make the regeneration duration compatible with the high availability of the system. The upgrade of the auxiliary pumping system is also described, as well as the mitigation of air or water exposure risk during regeneration of the NEG pump.

High sensitivity measurements of gas transport through films for food packaging and the O2 adsorption issue

New biodegradable polymers employed for food packaging require an accurate characterization of their O2 ultra-barrier permeation rates. Methods and procedures of gas transport measurements must guarantee high sensitivity and immunity to artefacts. Within this context, this paper reports two outcomes. The first one is to demonstrate the suitability of a specific high vacuum apparatus for challenging measurements of gas permeability on new polymers for food packaging. We show that our newly developed set-up is able to achieve a minimum detectable gas throughput 2×10-9mbarl/s , which is equivalent to permeability coefficient of 7×10−11cm2/s in case of 20 μm-thick polymer film with an area of 7×10−2cm2 under a 105Pa pressure differential. The second aim is to investigate the origin of its detection limits and possible measurement artefacts obtained with this instrument. In particular, we focus on the O2 adsorption effect on the inner surfaces of the set-up.

Development Design of Amine Sweetening Unit Plant of Natural Gas

Abstract: In addition to reduced equipment sizes, lower circulation rates, and greater overall amine concentration, selective amines have become more popular for gas sweetening. Selective amines absorb H2S from CO2 through thermodynamic or kinetic processes. Selective amine mixtures may enable a small quantity of CO2 to remain in the treated gas. Plant capacity margins for selective amine units are frequently small. Increasing the acid gas concentration or throughput might result in sweet gas that does not fulfill CO2 specifications. Increasing the amine concentration, employing combinations of amines, and altering the lean amine temperature were explored since adding new equipment may be costly. Compared to increasing reboiler or pumping capacity, these factors need little or no extra capital.

CO2 methanation with Ru@MIL-101 nanoparticles fixated on silica nanofibrous veils as stand-alone structured catalytic carrier

An important challenge in the valorization of CO2 and H2 into fuels is the development of a stable, reusable and easy to handle heterogeneous catalyst. Here, a silica nanofibrous membrane is investigated as carrier for Ru nanoparticles, themselves encapsulated inside the metal organic framework (MOF) Cr-MIL-101. The catalytic membrane is investigated for the Sabatier methanation reaction. The direct electrospinning of a tetraorthosilicate (TEOS) sol results in a highly thermal resistant silica nanofibrous structure (up to 1100 °C) with pores between the fibers in the µm-range, allowing a high gas throughput with low pressure requirements. A straightforward dip-coating procedure of the carrier was used to obtain a Ru@MIL-101 functionalized silica nanofibrous veil, avoiding Ru clustering. The obtained catalytic membrane exhibited an apparent turnover frequency of 3257 h-1 at 250 °C. This system therefore paves the way towards structured reactors for efficient CO2 hydrogenation processes.

Steady-state and transient dynamics for sweetening of LPG process

Amine treating is the most common system for gas sweetening that is used in petroleum, gas and petrochemical industries. Steady-state analysis of the process is conducted on the developed simulation-model using Aspen Hysys. For obtaining more accurate results, absorber internal specifications and feed gas conditions are taken from real industrial plant data. The effect of the system controlling parameters on concentrations of H2S and CO2 in sweet gas is inspected. The manipulated variables for the amine unit are Di-ethanolamine (DEA) solution circulation rate and temperature. Sour gas flow rate and H2S/CO2 mole ratio in feed become disturbance or load; whereas, the control variables are concentration and throughput of sour gas in exit sweet gas. The outcome of the sensitivity study is used to develop MIMO transient models with a first-order plus dead-time (FOPDT)structure for the control studies. Based on the developed model the model predictive control (MPC) and PID controls are implemented for 2 by 2 systems.

TrailChain: Traceability of data ownership across blockchain-enabled multiple marketplaces

Today massive amounts of data are generated from Internet-of-Things (IoT) sensors that can be streamed in real-time and utilized for building valuable services. As the demand for data sharing has increased, a new business model of data marketplace has emerged that allows individuals to sell their data to buyers for monetary gain. However, these data marketplaces are prone to various threats such as unauthorized data redistribution/reselling, tampering of data, dishonest data ownership claims, and trade of bogus data. The existing solutions related to data ownership traceability are unable to address the above issues due to ambiguous data ownership, undisclosed data reselling, and dispersal of data ownership across multiple marketplaces. In order to solve the above problems, we propose a novel blockchain framework, TrailChain, that uses watermarking to generate a trusted trade trail for tracking the data ownership spanning across multiple decentralized marketplaces. Our solution includes mechanisms for detecting any unauthorized data reselling within and across marketplaces. We also propose a fair resell payment sharing scheme that ensures the resell revenue is shared with the data owners over authorized reselling. We present a prototype implementation of the system using Ethereum. We perform extensive simulations to demonstrate TrailChain’s feasibility by benchmarking performance metrics including execution gas costs, execution time, latency and throughput.

Feasibility analysis of using a bubble column evaporator as a solvent swap device

A feasibility analysis was performed on the use of a bubble column evaporator (BCE) as a solvent swap device. Batch BCE simulations successfully proved that the BCE was capable of performing a solvent swap for both the dcm - methanol and the water - methanol systems with the aid of computational fluid dynamics (CFD). This was achieved by saturating the inlet gas with the new solvent which condensed inside the column. The old solvent then evaporated into the gas phase which exited via the column outlet. Progression of the solvent swap therefore caused the liquid mass fraction of the species to vary. The effect of bubble size, gas flowrate, gas inlet temperature and liquid mass fraction on the solvent swap efficiency was also investigated. The liquid mass fraction was found to have the greatest influence on the solvent swap efficiency. The evaporation rate decreased proportionately with the mass fraction of the evaporating species in the liquid phase which was a result of Raoult’s law. The thermodynamic model was used to validate the CFD solution and estimate the time required for a batch solvent swap. A smaller bubble size was found to enhance mass transfer in the solvent swap by increasing the evaporation and condensation thermodynamic efficiencies. The higher gas flowrate also improved the mass transfer in the system and reduced the time required for a solvent swap as there was a greater throughput of gas, however it resulted in a decreased evaporation efficiency due to a lower gas residence time in the column. The higher gas inlet temperature increased the rate of condensation and the time required for the a solvent swap. The increased condensation of the new solvent had a negative effect on the evaporation of the old solvent as a result of raoults law which resulted in a longer solvent swap operation. The increased gas inlet temperature also caused the evaporation rate to decrease because of the relationship between the density of an ideal gas and temperature. An increased inlet gas temperature resulted in a lower inlet gas density. There was therefore a reduced mass throughput of gas into the column and consequentially the rate of evaporation decreased. The liquid mass fraction was found to have the greatest influence on the solvent swap efficiency. The evaporation rate decreased proportionately with the mass fraction of the evaporating species in the liquid phase which was a result of Raoult’s law.