Liquid Tank Research Articles

Thermodynamic Modeling and Analysis of Boil-off Gas Generation and Self-Pressurization in Liquefied Carbon Dioxide Tanks

<i>The importance of the safe transport of liquefied carbon dioxide (LCO<sub>2</sub>) is increasing owing to environmental issues. When transporting a low-temperature liquid, boil-off gas generation and self-pressurization occur due to heat ingress, affecting the holding time of a low-temperature liquid tank. This study developed and compared three thermodynamic self-pressurization models to estimate the holding time of LCO<sub>2</sub>: Thermal homogeneous model (THM), Thermal two-zone model (TTZM), and Thermal multi-zone model (TMZM). Thermodynamic differential equations were solved for THM, and software was used for TTZM. For TMZM, the parameters were optimized using experimental data to determine the heat ratio parameter f and heat transfer parameters K<sub>1</sub> and K<sub>2</sub>. THM and TTZM estimated an unreasonably long holding time, approximately 42 days. The TMZM, however, showed a satisfactory holding time of 12–13 days. These results can help predict the self-pressurization in the storage tanks of LCO<sub>2</sub> and be applied to actual LCO<sub>2</sub> carrier cargo handling systems, with the modeling results indicating that the 12–13 days of LCO<sub>2</sub> self-pressurization based on the TMZM appears to be the most suitable.</i>

Investigation of heat leakage calculations and experiments for a wide-mouth liquid nitrogen tank

ABSTRACT With the continuous development of biomedicine, the long-term low-temperature storage of biological samples has become essential. In order to meet the demand for long-term storage of liquid nitrogen to keep samples safe, a study on the evaporated gas recycling storage of liquid nitrogen tanks will be carried out. This research utilizes new approach to accurately calculate the heat leakage of the liquid nitrogen tank. The experimental results show that the theoretical heat leakage is 6.16 W, and the actual heat leakage is 7.07 W. By incorporating the insulating plug, the actual heat leakage was reduced by 61.2%, decreasing to 2.74 W, and the calculated heat leakage is 2.47 W. The error margin in both cases was approximately 10%. Furthermore, in contrast to existing investigations, this experiment with the 8W@77K pulse tube cryocooler for recovering nitrogen is conducted under environmental pressure rather than overpressure, and it also takes into account the sensible heat issues caused by ambient pressure. The ratio of 1.81 W of sensible heat to 2.74 W of latent heat is 2:3, indicating that under ambient pressure conditions, the impact of sensible heat cannot be ignored. The key improvement methods are given to improve the success rate of the experiment. The research results provide a useful reference for the re-cycling and storage of liquid nitrogen.

Optimization of atomization performance of external mixing air atomizing nozzle based on response surface agent model

Based on the finding that the atomization performance of the nozzle is affected by its structural parameters, a combination of finite element analysis and structural optimization calculations is used. Finite element analysis was performed through the VOF (Volume of Fluid) module of Fluent software to determine the structural parameters affecting the performance of the atomizing nozzle. The liquid cyclone tank inclination, the length of the flat section at the gas outlet, and the mixing chamber outlet diameter were used as optimization factors. The atomization cone angle and fuel atomization circumferential distribution uniformity index were used as the evaluation indexes of atomization performance. An orthogonal experimental design was carried out based on the above. Proxy model for atomization cone angle and fuel atomization circumferential distribution uniformity index based on response surface method. The optimal structure of the nozzle was obtained by optimization calculation of the agent model by genetic algorithm. The results show that the atomization performance is optimal when the inclination angle of the liquid rotating tank is 42.9, the length of the flat section at the gas outlet is 3.3, and the diameter of the mixing chamber outlet is 5.0. The atomization cone angle increased by 23.07 % compared with the original model, and the fuel atomization circumferential distribution uniformity index decreased by 45.06 %. A new solution for the design of externally mixed air atomizing nozzles is provided.

Research on the response of underwater explosion liquid tank structure based on RKPM method

Abstract This work establishes a three-dimensional fluid-structure coupling calculation model for the response of SPH-RKPM underwater explosion structures and verifies its effectiveness. Using the established numerical model, the dynamic response of the water-containing liquid tank structure under underwater explosion shock wave load was modeled and calculated, and the response characteristics of the water-containing liquid tank under different detonation distances were discussed. The response law of the water-containing liquid tank structure under shock wave load is summarized.

Heat transfer research on the cooling process of waxy crude oil storage in the vault tank based on VOF model

This paper focuses on the static cooling process for waxy crude oil stored in dome roof tanks. For the three phases of gas on top, liquid crude oil, and bottom water in storage tank, the VOF method is used to describe the evolution of physical quantities at the “oil–water”/“oil–gas” interface. The porous medium method is used to quantitatively characterize the sol–gel conversion process for waxy crude oil. A physical and mathematical models are established to describe the flow-heat transfer coupling behavior of the three-phase medium of crude oil, gas on top, and water at the bottom of the dome roof tank. In terms of the overall cooling process,The gas at the top of the tank has the simplest and fastest physical field evolution. It has the most uneven distribution (average temperature variance of 4 °C2), the strongest flow (average flow velocity of 0.4 m/s), the highest cooling rate (0.632 °C/h), and the lowest temperature (14.84 °C at the end). Its physical field is influenced by both the atmosphere and crude oil. The evolution of the physical field of crude oil is the most complex. It lags behind the gas at the top of tank and is directly effectted by it. Based on the evolution characteristics of the flow field of crude oil, the cooling process is divided into three stages: Stage I (0–––10 h) is the stage of convection generation and evolution in the crude oil region; Stage II (10 h − 34 h) is the stage of convection stability in the crude oil region; Stage III (after 35 h) is the stage of flow field transformation of crude oil. In stages I and II, the flow and momentum exchange at the oil–gas interface are significant. Crude oil is jointly influenced by the natural convection of the gas at the top of the tank and its own natural convection, forming a counterclockwise large vortex structure. The low-temperature area is near the central axis boundary of storage tank, oil–gas interface, and tank wall. The high-temperature area is within a range of 0.1 m − 3.3 m from the tank wall. After entering stage III, the flow and momentum exchange at the oil–gas interface weaken. The flow field of crude oil is only controlled by its own natural convection and transforms into a clockwise large vortex dominated. The low-temperature area is concentrated in the enclosed area of “oil–gas interface − tank wall” and “oil–water interface − tank wall”. The temperature field changes accordingly. Eventually, the high-temperature area is concentrated in the area slightly above the center of the tank. The physical field evolution of bottom water lags behind crude oil and is most unstable. Its cooling rate is 0.164 °C/h, slightly higher than crude oil’s 0.157 °C/h. The temperature is always slightly lower (33.47 °C at the end), and the physical field is the most uniform (average temperature variance of 0.0003 °C2), affected by the tank bottom environment and liquid crude oil.

Seismic evaluation of frequency influence and resonant behavior for lead rubber bearing isolated rigid rectangular liquid tanks

Seismic evaluation of frequency influence and resonant behavior for lead rubber bearing isolated rigid rectangular liquid tanks

Study on recovery and utilization of cold energy for insulation design of liquid hydrogen tanks

Insulation design is one of the key technologies for Liquid Hydrogen (LH2) tanks. To enhance the insulation efficiency and energy utilization of the LH2, this study proposes a novel approach to enhance the insulation performance of LH2 tank and cold energy cascade utilization of LH2. Three Cryo-cooling Insulation Systems (CIS) with various insulation schemes are designed, analyzed and compared from the perspectives of insulation performance, consumption and energy utilization efficiency. An optimal insulation scheme among three CISs is identified and evaluated. Additionally, a dimensionless number (Ψ) is proposed to assess the insulation advantages of the CISs. And the insulation performance and economic feasibility of the system be effectively balanced. The findings reveal that the insulation performance of the proposed CIS outperforms previous insulation methods by a factor of 239.13. Among the schemes in three CISs, Schemes 2 (Position of CSs at 6th, 25th and 35th layers), Schemes 3 (Position of CSs at 10th, 40th and 45th layers), and Schemes 3 (Position of CSs at 3rd, 40th and 45th layers) exhibit superior insulation performance in Cases #1 (CIS of LN2-LAr), Cases #2 (CIS of R14-R170), and Cases #3 (CIS of R1150-R23). Notably, Case #1 achieves the highest insulation performance, showing improvements of 2.58 and 1.63 times over Case #2 and Case #3, respectively. However, the energy output in Case #1 is approximately 248.12 W, constituting 83.10 % and 71.60 % of Case #2 and Case #3, respectively. Case #1 demonstrates the highest specific energy output, with improvements of 30.12 % and 81.05 % compared to Case #2 and Case #3, respectively. In terms of the exergy utilization rate of each equipment, the exergy utilization rate of equipment in Case #1 is the highest among the three cases. The study underscore the feasibility of cold energy utilization for insulation, providing solutions for energy conversion and thermal management of LH2 tanks through cryo-cooling cascade utilization.

Analysis of Longitudinal Braking Stability of Lightweight Liquid Storage Mini-Track Vehicles

In this study, a theoretical model was established for longitudinal braking stability (LBS) of a lightweight liquid storage mini-track vehicle to investigate its behaviors. The influence of the tank liquid filling ratio (TLR), initial velocity (IV), and initial braking deceleration (IBD) on the LBS of the tracked vehicle was studied via FLUENT simulation. The simulation results showed that when the IV and the IBD were constant, the TLR significantly affected the braking efficiency. Conversely, when the TLR was 0.7, the braking efficiency decreased by 32%, resulting in the worst LBS. The braking efficiency at different IVs decreased by ~30% when using a constant IBD and TLR, and the braking stability exhibited little difference. Further, the braking efficiency decreased noticeably with increasing IBD; meanwhile, the braking longitudinal stability worsened. When the IBD was increased to 5 m⋅s−2, the braking efficiency decreased by 48.4%. The road experiment showed that when the tracked vehicle was accelerated and braked under limit conditions, the stability requirements were met. Finally, by combining the simulation and road experiment, the driving parameters of the tracked vehicle that could satisfy the LBS were obtained.

Experimental Study on a Liquid Hydrogen Tank for Unmanned Aerial Vehicle Applications

A lightweight, 12 L liquid hydrogen fuel tank has been designed, fabricated, and tested with the aim of optimizing boil-off rates while minimizing the weight of a complete propulsion system intended to be integrated into an unmanned aerial vehicle. After looking at several different insulation schemes, the system was optimized as two concentric, lightweight titanium cylinders with high vacuum and multilayer insulation in between. The thickness of the multilayer insulation and the design of support structures were optimized to reduce the overall weight of the tank. This paper focuses on characterizing the boil-off rate of a small liquid hydrogen tank in relation to ambient temperature and fuel level. Additionally, it addresses the analysis of the instrumented transfer line between the reservoir and the operating fuel cell, presenting pressure and temperature measurements for each component of the transfer line. The efficiency of the heat exchanger under natural and forced convection is also discussed. The key contribution of the experimental campaign lies in demonstrating an average boil-off rate of 19.5 g/h over 45 h. This significantly surpasses the limits of ultra-long-range flight achievable with alternative electric energy sources. Furthermore, the paper highlights the importance of the variable boil-off with time and its impact on aircraft performance.

Influence of solid particles in liquid tank on sloshing behaviour based on CFD-DEM coupling method

This paper employs multiphase flow theory to investigate the influence of different solid particle densities on the sloshing characteristics within a liquid tank. A numerical model of gas-liquid-solid multiphase flow sloshing motion within the tank was established using the Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) coupling method, simulating the interactive coupling between the two-phase fluid and solid particles. In this context, the gas-liquid two-phase fluid is treated as a continuous phase, described under the Eulerian framework, with the Volume of Fluid (VOF) method applied to capture the gas-liquid interface. Conversely, the solid particles are treated as a discrete phase, described under the Lagrangian framework. The effects of different solid particle densities on the tank sloshing characteristics were analyzed utilizing the STAR-CCM + software platform. Initially, the validity of the CFD-DEM method was confirmed by simulating classical scenarios such as a single spherical particle falling from air into water and the flow dynamics of a gas-liquid-solid three-phase dam break. Subsequently, a numerical simulation of sloshing in a pure water tank was conducted and compared with published experimental results, thereby verifying the feasibility of the numerical method for gas-liquid two-phase sloshing. Following this, a series of simulations were conducted on a pure water tank to validate the effectiveness of the numerical method for gas-liquid two-phase fluid sloshing. Subsequently, solid particles were introduced to the model, and the effect of solid particle densities on sloshing load and response under forced motion was studied. Finally, by comparing and analyzing the sloshing-induced pressure on the tank walls and the amplitude of the free surface motion across different solid particle densities and as well as different excitation frequencies, the sloshing characteristics of the solid-liquid mixed two-phase flow were investigated. The computational results indicate that an increase in solid particle density corresponds to an increase in liquid surface wave amplitude. This suggests that lighter solid particles have a greater damping effect on tank sloshing. It can be inferred that when the density of solid particles is maintained at a constant level, the closer the external excitation frequency is to the natural frequency, the more effective the sloshing suppression effect. This is attributed to the fact that, as sloshing intensifies, fluid velocity increases, resulting in greater damping due to viscosity effects, thereby enhancing the sloshing suppression.

Numerical design of a flow restrictor for tanked liquid nitrogen undergoing reduced-gravity flights

NASA and the United States are designing multiple reduced-gravity cryogenic payloads to study various two-phase flow phenomena that will be ground-tested and subsequently flight-tested onboard parabolic flights. The setup will undergo 25+ parabolas per flight, during which liquid nitrogen will be cyclically or continuously demanded from a supply Dewar. The minimum gravity level during a parabolic maneuver is 0 ± 0.05 g, which can last around 20 seconds, and the maximum expected gravity is 2 g, which lasts for 40-50 seconds. This Computational Fluid Dynamics (CFD) study focuses on the design and optimization of a bi-directional perforated plate and a ring baffle to help ensure single-phase liquid nitrogen outflow during all flight phases, regardless of supply tank liquid level or gravity level. CFD analyses carried out using ANSYS FLUENT indicate that a double perforated plate with an open area percent equal or less than 0.63% can achieve high values of expulsion efficiency. Structural analyses performed using the ANSYS Static Structural solver determined the minimum plate thickness needed to withstand gravitational and hydrodynamic forces experienced during the flight.

Characterization on the impact load of a local corner region of a liquid tank entering water

This study conducts a detailed examination of the characteristics of impact loads in complex triangular areas within liquid tanks via the volume of fluids (VOF) method, with a general understanding of impact loads. By comparing the numerical results with previous experimental data of oblique wedge impacts on water surfaces, the effectiveness of the VOF method was confirmed. Complex dynamic phenomena such as fluid climbing, jet impact, and air cavity effects in corner areas were analyzed through 3D flow characteristics. By examining two types of impacts (a structure impacting fluid and a fluid impacting structure), the equivalence between them is verified. An in-depth exploration of the load characteristics in different areas is conducted by combining the free surface evolution. The multipeak characteristics of the load and synchronicity of the peak loads at different parts are closely related to the phenomenon of the climbing fluid being obstructed. Bubble flow also plays a crucial role in affecting the load characteristics. Further exploration of the effects of structural motion on load characteristics reveals complex load variability. These findings provide a valuable reference for understanding the impact loads in complex corner areas of liquid tanks.

H2O2 oxidation – CaO precipitation pretreatment combining forward osmosis for electroless nickel spent tank liquid (ENSTL) reduction

ABSTRACT The electroless nickel spent tank liquid (ENSTL), as a typical hazardous waste, contains a variety of refractory organic substances as well as heavy metals and inorganic salts. Generally, ENSTL is delegated for disposing by qualified hazardous waste disposal departments in China. However, the temporary storage, transportation, and higher entrusted disposal expenses increase the burden on enterprises producing the hazardous ENSTL. This paper explored an oxidation/precipitation pretreatment and forward osmosis (FO) combined process for ENSTL reduction. 400 mmol/L Hydrogen peroxide and 5.0 wt% calcium oxide were selected as the optimal pretreatment in order to minimize the osmotic pressure of ENSTL, by which the conductivity was significantly reduced from 50.8 mS/cm to 26.8 mS/cm. As a result, the concentrating factor (N) could be dramatically increased from 2.45 by the direct FO to 8.71 by the combined system. Accordingly, the average water flux during the 24 h concentrating cycle increased from 2.47 L/(m2·h) to 4.56 L/(m2·h). TOC rejection rate decreased from 90.23% to 84.39% due to the transformation of organic matter forms by the chemical oxidation during the pretreatment. Meanwhile, TP, Ni and NH4 + rejection rates decreased to a certain extent, which may related to the mitigation of membrane fouling by the pretreatment.

Seismic Performance of Cylindrical Liquid Storage Tanks in the 2023 Kahramanmaras Earthquakes: A Case Study of a Self-Supported Oil Storage Tank

ABSTRACT This paper covers the seismic performance of liquid tanks due to 2023 Türkiye earthquakes and a case study of a moderately damaged self-supported tank is studied. Typical types of damage were sloshing induced upper tank wall deformations, sliding and uplift of the base, and rupture at tank-pipe connections. Besides, slip-prone tanks were less vulnerable to tank damage. The coupling between sliding and uplift responses of a self-supported tank is investigated considering different coefficients of friction. The results revealed that tank wall stresses can be significantly reduced due to sliding effect.

Exploring variations in the weight, size and shape of liquid hydrogen tanks for zero-emission fuel-cell vessels

We report an exploration of liquid hydrogen (LH2) tank technology, determining if improving LH2 tank weight, multiplicity or shape enables more hydrogen to be stored on hydrogen vessels. The improvements investigated are well beyond the current LH2 technology state-of-the-art. The platform for this study is a monohull H2 Baseline research vessel powered 100% by hydrogen.Regarding weight reductions, we found that the research vessel does not benefit significantly from large weight reductions of the LH2 tanks. A 50% reduction in mass of the inner pressure vessel led to a 3.1% reduction in the total research vessel weight. Reducing the LH2 tank weight to the asymptotic limit of zero results in a 7.1% reduction in the overall research vessel weight. This maritime application, while benefitting from a reduction in LH2 tank weight, is not a strong driver for LH2 tank weight improvements.The two large LH2 tanks of the H2 Baseline Vessel can be replaced with a multitude of smaller LH2 tanks. In two Multiplicity design variants, the total amount of stored LH2 was ∼5–9% less than that of the H2 Baseline Vessel, which does not motivate conducting the needed R&D that would drive the technology to smaller high-performing LH2 tanks.We did find a significant benefit to improving the shape of LH2 tanks, towards prismatic tanks that would better match the vessel hullform. Considering a “Shape Variant” that included space-consuming features such as tank connection spaces, manifolding and ventilation, we found a 26% improvement in stored LH2 compared to the H2 Baseline Vessel. The large improvement in storage capacity could warrant further LH2 tank R&D that can enable high performing prismatic LH2 tanks, such as pressure vessel steel developments allowing for higher strength/ductility at 20 K, improved insulation systems, methods for efficiently building prismatic tanks with insulation systems fit for 20 K service and flare-less techniques for managing heat leak (venting).The results are reviewed considering the current regulatory restrictions as well as prevailing limitations in LH2 tank manufacturing.

Prediction of waves in tanks excited by ship motion and moving walls with a three-dimensional fully linear finite difference approach

Mitigation of waves in shipboard swimming pools excited by ship motions is a topic of current interest that has not yet been extensively investigated. Various damping mechanisms have been applied to mitigate waves excited in tanks, such as porous baffles or different types of internal baffles. However, most of these devices are installed in LNG tanks to prevent serious sloshing effects. Furthermore, these are passive devices and, hence, unable to control wave-induced excitations. Our focus was on the validation and verification of the three-dimensional (3D) fully linear Finite Difference Method (FDM) based on the previously developed method of Qi et al. (2024) for predicting waves in a transversely placed swimming pool excited by ship motions and piston-type actuators. We validated our FDM approach against comparative Computational Fluid Dynamics (CFD) simulations as well as experimental model test measurements. The CFD tools solved the Reynolds-averaged Navier-Stokes (RANS) equations, relied on an appropriate turbulence model and the Volume of Fluid (VOF) method to capture the free surface of the liquid in the model tank, and employed the overset technique to specify the motions of the active actuators. Our FDM considered ship-induced roll excitations as well as simultaneous roll and sway excitations, albeit only at frequencies outside the range of the pool's resonance frequency. For these periods, our approach accurately predicted not only the mitigated waves in the pool, but also the optimum amplitude of the actuators needed to mitigate such waves. Our FDM can be applied to obtain a preview of excited waves under various conditions, leveraging its principal advantage of extreme computational efficiency.© 2017 Elsevier Inc. All rights reserved.

Numerical Study on the Sloshing Behaviors of Dual Liquid Tanks with Gas Inflow

Numerical Study on the Sloshing Behaviors of Dual Liquid Tanks with Gas Inflow

Optimizing seismic performance: Integrating friction dampers into spherical liquid tanks

This study addresses the vital challenge of ensuring the safe storage of Liquid Natural Gas (LNG) in spherical tanks during seismic events, focusing on the crucial balance between meeting seis- mic performance criteria and mitigating economic losses due to potential operational disrup- tions from necessary retrofitting efforts. In response to this challenge, we present a case study on retrofitting an LNG tank near the North Anatolian Fault (NAF) line of Türkiye. Through a com- prehensive seismic evaluation, this study reveals inadequacies in the existing case's compliance with seismic criteria. It suggests a remedy involving the increased stiffness of lateral force-resist- ing members coupled with the utilization of friction dampers. Following the proposed stiffness increase achieved through retrofitting, our approach is fundamental to exploring alternative damping mechanisms designed to enhance the steel column-brace support structure. One of the key design challenges is the unique dynamic behavior of LNG, especially its sloshing during earthquakes, which necessitates a comprehensive understanding of fluid-structure interaction for accurate modeling and analysis. Through a series of transient analyses incorporating actions, we evaluate the effectiveness of the proposed retrofitting measures on the structure. Our findings introduce a feasible and efficient retrofitting strategy, marked by minimal operational interrup- tion, primarily by avoiding the extensive demolition and reconstruction typically required.

Multi-objective optimization of the wave-proof plate layout of the liquid tank vehicle based on NSGA-II and RSM

Multi-objective optimization of the wave-proof plate layout of the liquid tank vehicle based on NSGA-II and RSM

Economic and exergy transmission analysis of the gas-liquid type compressed CO2 energy storage system

Exergy transmission characteristic of the compressed CO2 energy storage system is significant to evaluate the system performance while little attention has been paid to this analytical method in the literature. A CO2 energy storage cycle configured with a gas holder as a low-pressure gas reservoir and a liquid tank as a high-pressure gas reservoir is studied comprehensively. The exergy transmission characteristics and the cost uncertain analysis are considered. Results demonstrated that the round trip efficiency and levelized cost of storage are 71.2 % and 0.1286 $/kWh under optimal design parameters, respectively. Keeping the charge/discharge duration ratio close to 1 has a positive effect on optimizing the economic performance of the system. With the general exergy model of the whole system configured for the charge and discharge process, the study uncovers the fluctuations in the pertinent proportional ratios and exergy transfer efficiency in relation to important parameters. Except for the turbomachinery isentropic efficiency, which impacts nearly all efficiencies, the variation of each parameter only governs the modification of the exergy transfer efficiency for a specific term or a pair of terms. Furthermore, the thermal exergy efficiency of the discharge process and intercooler has a maximum value as the cold-side temperature difference of the high-temperature cooler changes to 27 °C.