SUBCRITICAL LIQUID OXYGEN STORAGE AND CONVERSION SYSTEM FOR OMNIGRAVIC OPERATION

In this paper, the performance of a 2000-ton hybrid AIP system submarine is investigated by analyzing the weight, volume and efficiency of its propulsion system. The engine of the investigated AIP system employs a low temperature polymer electrolyte membrane fuel cell which makes use of the hydrogen and oxygen as the reactants. More specifically, the reactants of fuel cell in this study are considered from the combination of three fuel storage systems, methanol (MeOH), liquid hydrogen (LH_2) and metal hydride (MH_2), and two oxidant storage systems, liquid oxygen (LOX) and compressed oxygen (O_2). Based on the assumed various daily propulsion load consumptions, a propulsion system of a 3500 kW diesel generator, a 300 kW fuel cell, and a 7500 kWh energy capacity Li-ion battery bank is determined. With the system installed in the submarine, the maximum designed endurance can reach a total of 26 days for the fuel cell using the combination of reactant LH_2+LOX, and the minimum designed endurance can be up to 10 days for using the reactant MH_2+O2. For submarine cruising at zero speed, the submerged endurance of the AIP system using reactant LH2  LOX plus battery bank is 22.8 times of that using battery bank alone. This value will increase to 25.0 times for submarine cruising at 7.4 knots. At the cruising speed of 5.5 knots, the maximum submerged range of submarine increases a factor of 24.1 for fuel cell using the reactant of LH_2+LOX as compared with operation on battery bank alone. Therefore, the submerged endurance is substantial enhanced for using the combination of fuel cell and battery. In addition, the indiscretion ratio is zero for the AIP system submarine with a cruising speed below 7.1 knots; this can greatly reduce the submarine vulnerability. Based on the weight and volume analysis of the submarine equipped with a hybrid AIP system, the usage of the reactant LH_2+LOX is well suited for a small- to medium-sized 2000-ton submarine with a fuel cell system. Furthermore, using the reactant MeOH+LOX has the advantage for large-sized LT-PEMFC AIP system submarines.

A quasi-2D thermodynamic model for performance analysis and optimization of liquid hydrogen storage system with multilayer insulation and vapor-cooled shield

Overheating of Li-ion cells and battery packs is an ongoing technological challenge for electrochemical energy conversion and storage, including in electric vehicles. Immersion cooling is a promising thermal management technique to address these challenges. This work presents experimental and theoretical analysis of the thermal and electrochemical impact of immersion cooling of a small module of Li-ion cells. Significant reduction in both surface and core temperature due to immersion cooling is observed, consistent with theoretical and simulation models developed here. However, immersion cooling is also found to result in a small but non-negligible increase in capacity fade of the cells. A number of hypotheses are formed and systematically tested through a comparison of experimental measurements with theoretical modeling and simulations. Electrochemical Impedance Spectroscopy measurements indicate that the accelerated cell aging due to immersion cooling is likely to be due to enhanced lithium plating. Therefore, careful consideration of the impact of immersion cooling on long-term performance may be necessary. The results presented in this work quantify both thermal and electrochemical impacts of a promising thermal management technique for Li-ion cells. These results may be of relevance for design and optimization of electrochemical energy conversion and storage systems.

Design and testing of a high performance liquid phase cold storage system for liquid air energy storage

Liquid hydrogen storage, thermal management, and transfer-control system for integrated zero emission aviation (IZEA)

The objective of this paper is to assess the thermo-economic performance of different cycle configurations for pumped thermal electricity storage (PTES), including the effects of charging electricity cost. Reversible turbomachinery is employed to reduce the capital cost. Brayton cycles with different working fluids and a subcritical Rankine cycle operating with ammonia are compared. Liquid thermal energy storage systems are used. For the Brayton cycle, also packed bed storage systems are considered as an alternative. A new cost correlation for turbomachines, initially developed for organic Rankine cycles, is adapted for compressors and reversible machines. This correlation is based on the number of stages and physical size of the machine, which are estimated considering thermodynamic as well as mechanical limitations on the enthalpy difference that can be attained per stage. The results indicate that for a plant size of 50 MW and a discharge duration of 8 hours, the Brayton system with liquid storage and helium as a working fluid has the lowest levelized cost of storage at 0.138 $/kWh, mainly due to the high thermal conductivity of the fluid. Packed bed systems were found to be more expensive than liquid storage systems due to the large cost of the pressure vessels, with cost parity reached at a discharge duration of 4 hours. However, at this duration lithium ion batteries are likely to be cheaper. The results suggest that the levelized cost of storage for the Rankine cycle is slightly higher, 0.151 $/kWh. In addition, the Rankine cycle has disadvantages related to the higher storage volume and less flexibility for part load operation.

This study aimed to develop simple empirical equations to predict flaxseeds properties. The first part of the present study deals with the physical, aerodynamic and solid flow properties of flaxseeds which were evaluated as a function of change in moisture content from 8.60 to 23.90% dry basis (d.b.); the dimensions of the length, width and thickness varied from 4.14 to 4.32 mm, 2.03 to 2.13 mm and 0.88 to 0.93 mm, respectively. As the moisture content increased from 8.60 to 23.90% d.b., the bulk density, true density and porosity were found to decrease from 46.65 to 44.89 kg/m3, 1,244 to 1,176 kg/m3 and 46.65 to 44.89%, whereas angle of repose and terminal velocity were found to increase from 27.6 to 35.80 and 2.46 to 3.56 m/s, respectively. The static coefficient of friction on various surfaces, namely plywood, stainless steel, galvanized iron, iron and internal also increased linearly with the increase in moisture content. The results of the experimental investigation may help to optimize some engineering parameters of separation equipment. The present work was carried out to separate flaxseed from light impurities (chaff, other debris from threshed flaxseed since the introduction of harvesting machine). It is difficult to separate seeds from straw and other foreign materials by using primary separation equipment. The difficulty comes from the narrow size and shape, angle for both of natural slope and friction between foreign materials and seeds. The second part was carried out on a series of experiments to specify the optimum conditions of separating operations which insure the highest grade of separation efficiency with minimum losses. Pneumatic separation equipment was manufactured and tested under different combinations of the following factors: airstream velocity, feed rateand sample moisture content. The performance of the equipment was evaluated by using the indices separation efficiency and percentage of seed losses. The results of the equipment performances showed that the combinations of airstream velocity, feed rate and sample moisture content affected significantly the separation efficiency and grain losses. Airstream velocity of 2–6 m/s combined with 8.5 kg/h feed rate and 8.6% moisture content can be considered the most favorable combination values of these variables. They gave the highest grades of separation efficiency and the minimum grain losses. PRACTICAL APPLICATIONSThere are several applications of the physical properties data. Physical attributes and aerodynamic properties are required in the design of combines as well as cleaning and grading equipment. Information about solid flow properties is needed to design handling equipment. Physical properties data are needed for the development of sensors to control machines and processes, as well as detect quality. Physical properties of crops are requisite for better design of storage and ventilation system. The physical properties that we are investigating include: (1) physical attributes such as dimensions and densities; (2) aerodynamic properties such as terminal velocity and drag coefficient; and (3) solid flow properties like angles of repose and internal friction.

Zero boil-off (ZBO) storage of cryogenic liquids can be used both for an integrated cold source combined with mechanical cryocoolers, and long-term lossless storage of cryogenic propellants such as liquid hydrogen and oxygen. A ZBO system for space application should be less weight and high efficiency. Pulse tube cryocoolers with linear compressors for space application are used as the cold source to compensate heat inputs to the ZBO dewar which have a variety of new insulation technologies. This paper describes an evaluation method for evaluating the systematic characteristics of the ZBO system. For different cryogenic liquids, different solutions comprised of the cryocooler with different cooling capacity and the dewar with different adiabatic means, are analyzed and evaluated from feasibility, average power consumption, working mode and fluctuations of the temperature and pressure. The results show that the solution of the ZBO dewar matched with a single-stage cryocooler is preferred for liquid oxygen and nitrogen storage, and the intermittent working mode is more power efficient than the continuous working mode, while its temperature and pressure fluctuations are a little larger. The solution of the ZBO dewar with a cryocooler cooled screen matched with a multi-stage cryocooler is preferred for liquid neon, hydrogen and helium storage, and the continuous working mode is more feasible.

We started a feasibility study of high-end computing systems as a 2-year national project in 2012 for exa-scale computing era. In order to realize the exa-scale system, it is extremely important to design a large scale storage system with high bandwidth.We made a conceptual design of a mass storage system with high-speed I/O technology by studying future I/O requirements from simulations for disaster prevention and mitigation research. We concluded that a distributed and parallel file system with multiple meta-data servers is required, because a meta-data server (MDS) using in the Lustre file system is apparently insufficient to handle a large scale file system. In this paper, the storage system architecture and its performance are presented.

The development of affordable and non-noble-metal-based reversible oxygen electrocatalysts is required for renewable energy conversion and storage systems like metal-air batteries (MABs). However, the nonbifunctionality of most of the catalysts impedes their use in rechargeable MAB applications. Moreover, the loss of active sites also affects the long-term performance of the electrocatalyst toward oxygen electrocatalysis. In this work, we report a simplistic yet controllable chemical approach for the synthesis of dual transitional metals such as cobalt, nickel, and nitrogen-doped carbon (CoNi-NC) as bifunctional electrode materials for rechargeable zinc-air batteries (ZABs). The spatially isolated Ni-N4 and Co-N4 active units were rendered for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), respectively. The individual efficacy of both reversible reactions enables an ΔE value of ∼0.72 V, which outperforms several bifunctional electrocatalysts reported in the literature. The half-wave potential (E1/2) and overpotential were achieved at 0.83 V and 330 mV (vs RHE) for ORR and OER, respectively. The peak power density of ZAB equipped with the CoNi-NC catalyst was calculated to be 194 mW cm-2. The present strategy for the synthesis of bifunctional electrocatalysts with dual active sites offers prospects for developing electrochemical energy storage and conversion systems.

Thermal degradation behavior of 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide modified epoxy resin with liquid oxygen compatibility

UTRC lead the development of the Simulink Framework model that enables a comparison of different hydrogen storage systems on a common basis. The Simulink Framework model was disseminated on the www.HSECoE.org website that is hosted by NREL. UTRC contributed to a better understanding of the safety aspects of the proposed hydrogen storage systems. UTRC also participated in the Failure Mode and Effect Analysis of both the chemical- and the adsorbent-based hydrogen storage system during Phase 2 of the Hydrogen Storage Engineering Center of Excellence. UTRC designed a hydrogen storage system with a reversible metal hydride material in a compacted form for light-duty vehicles with a 5.6 kg H2 storage capacity, giving it a 300 miles range. It contains a heat exchanger that enables efficient cooling of the metal hydride material during hydrogen absorption in order to meet the 3.3 minute refueling time target. It has been shown through computation that the kinetics of hydrogen absorption of Ti-catalyzed NaAlH4 was ultimately limiting the rate of hydrogen absorption to 85% of the material capacity in 3.3 minutes. An inverse analysis was performed in order to determine the material property requirements in order for a metal hydride based hydrogen storage system to meet the DOE targets. Work on metal hydride storage systems was halted after the Phase 1 to Phase 2 review due to the lack of metal hydride materials with the required material properties. UTRC contributed to the design of a chemical hydrogen storage system by developing an adsorbent for removing the impurity ammonia from the hydrogen gas, by developing a system to meter the transport of Ammonia Borane (AB) powder to a thermolysis reactor, and by developing a gas-liquid-separator (GLS) for the separation of hydrogen gas from AB slurry in silicone oil. Stripping impurities from hydrogen gas is essential for a long life of the fuel cell system on board of a vehicle. Work on solid transport of AB was halted after the Phase 1 to Phase 2 review in favor of studying the slurry-form of AB as it appeared to be difficult to transport a solid form of AB through the thermolysis reactor. UTRC demonstrated the operation of a compact GLS in the laboratory at a scale that would be required for the actual automotive application. The GLS met the targets for weight and volume. UTRC also reported about the unresolved issue associated with the high vapor pressure of fluids that could be used for making a slurry-form of AB. Work on the GLS was halted after the Phase 2 to Phase 3 review as the off-board regeneration efficiency of the spent AB was below the DOE target of 60%. UTRC contributed to the design of an adsorbent-based hydrogen storage system through measurements of the thermal conductivity of a compacted form of Metal Organic Framework (MOF) number 5 and through the development and sizing of a particulate filter. Thermal conductivity is important for the design of the modular adsorbent tank insert (MATI), as developed by Oregon State University (OSU), in order to enable a rapid refueling process. Stringent hydrogen quality requirements can only be met with an efficient particulate filtration system. UTRC developed a method to size the particulate filter by taking into account the effect of the pressure drop on the hydrogen adsorption process in the tank. UTRC raised awareness about the potential use of materials-based H2 storage systems in applications outside the traditional light-duty vehicle market segment by presenting at several conferences about niche application opportunities in Unmanned Aerial Vehicles (UAV), Autonomous Underwater Vehicles (AUV), portable power and others.

Loofah-based self-powered triboelectric nanogenerator-supercapacitor for an integrated self-charging energy system

Safety investigation of hydrogen energy storage systems using quantitative risk assessment

Thermal Energy Storage systems (TES) for a Direct Steam Generation (DSG) solar plant feature preferably three stages in series including a latent heat storage module so that steam can be recovered with a limited temperature loss. The storage system designed within the Alsolen Sup project is characterized by an innovative combination of sensible and latent modules. A dynamic model of this three-stage storage has been developed and applied to size the storage system of the Alsolen Sup® plant demonstrator at CEA Cadarache. Results of this simulation show that this promising concept is an efficient way to store heat in DSG solar plants.