Cryogenic Liquid Research Articles

Dynamic modeling and analysis of LNG fuel tank pressurization under marine conditions

In this paper, a fast and effective dynamic model was developed to predict and investigate the performance of liquefied natural gas (LNG) fuel tank pressurization under marine conditions. An extended sloshing Nusselt number was defined to quantitatively evaluate the heat transfer enhancement in horizontal tanks under resonant sloshing. The validity of the model was confirmed by the corresponding experimental data. The pre-pressurization process, the fuel gas supply process, and the cryogenic liquid sloshing were investigated for two types of LNG fueled ships. Parametric studies, including the tank size, the filling level, the rated power, the engine load, and the sloshing intensity were conducted. The results showed that the heat transfer between the vapor and tank wall dominates the pressurization process, while the vapor condensation at the liquid-vapor interface dominates the holding period and the sloshing process. Moreover, the sloshing has a severe impact on the tank pressure, especially when the resonance condition of the tank is met, which can cause the shut-down of gas engines in extreme situations.

Assessment of prediction and efficiency parameters for cryogenic no-vent fill

Future long-duration crewed and robotic missions will require efficient methods with which to transfer cryogenic propellant from a depot storage tank to a customer receiver tank in the microgravity of space. Because unsettled cryogenic liquid cannot be transferred in microgravity with the vent valve open, the receiver tank must be pre-chilled to some “target temperature” that is sufficiently cold to then allow a non-vented fill (NVF). Predicting this target temperature is difficult, however, but can be done. A predictive parameter based on 1st Law from Kim et al. [13] is extended to include parasitic heat leak as well as initial fill levels to permit an assessment across the consolidated NVF and no-vent top off database. An efficiency parameter is also proposed to determine efficiency of a given injection method/tank pair. The prediction parameter is applied to 158 historical tests over a wide range of fluids, injection methods, and tank geometries. Additionally, a parametric study is conducted to determine the influential factors that affect NVF. Results indicate a 100% success rate that the parameter can predict the failure of a non-vented transfer for a given initial state and desired final state.

CFD modelling of the isobaric evaporation of cryogenic liquids in storage tanks

A new CFD model relevant to isobaric cryogen evaporation and weathering in storage tanks has been developed. It treats the heat influx from the surroundings into the vapour and liquid phases separately and allows for heat transfer between the two phases. The model accurately predicts the dynamics of the vapour flow and the vapour to liquid heat transfer. It provides well-resolved velocity and temperature profiles in the vapour phase, as well as evaporation and boil-off gas rates. It demonstrates that the main flow pattern is that the vapour circulates upwards close to the tank wall, then radially along the roof towards the tank axis, where the flow is partitioned; between a fluid that leaves the tank, and a fluid that recirculates back towards the vapour bulk. The results of simulations, carried out in different sized tanks with different initial amounts of cryogen, were compared with the results of the Huerta and Vesovic non-equilibrium model. The results indicate that, for the purposes of modelling heat transfer between the phases, steady-state vapour temperature and boil-off gas rate, the complex flow established in the vapour phase can be adequately modelled by the effective advective, upward flow from the interface.

Нелинейные колебания поверхности раздела двух жидкостей при угловых колебаниях бака

The development of rocket and space technology in recent years has led to the widespread use of various cryogenic liquids. To increase the shelf life of cryo-products on board spacecraft or in tankers of future space filling stations, it is proposed to create a certain stock of cryo-product, which is simultaneously in a two-phase or three-phase state and forms layers of liquid. The paper considers the problem in a nonlinear formulation about the oscillations of the interface of a two-layer liquid in an arbitrary axisymmetric cavity of a solid body performing angular oscillations around a horizontal axis. For the considered class of cavities with an arbitrary bottom and a lid, the nonlinear problem is reduced to the sequential solution of linear boundary value problems. Nonlinear differential equations describing the oscillations of the interface between two liquids in the vicinity of the main resonance are obtained. In the case of a circular cylindrical cavity with flat bottoms, solutions of boundary value problems in the form of cylindrical functions were used to calculate linear and nonlinear hydrodynamic coefficients depending on the depth and density of the upper liquid.

A comparative study of effect of heater orientation on flow and heat transfer characteristics in buoyancy driven flow in cryogenic liquid

The present study aims to analyse the buoyancy driven fluid flow and heat transfer characteristics using different heater orientation in liquid nitrogen for cooling superconductor. For this purpose, a localized circular heater (analogous to superconductor) generating heat at constant rate submerged in liquid nitrogen enclosure is analysed. The study is performed with two orientations of heater; one is vertical and another is horizontal. The entropy generation associated with heat transfer and fluid flow is also discussed in the present study. The Rayleigh number, average Nusselt number, maximum vertical velocity, entropy generation and Bejan number are used as comparing parameters for two orientations of heater. Under same heat generation rate, Rayleigh number is comparatively higher for vertically oriented heater whereas average Nusselt number is comparatively higher for horizontally oriented heater. The maximum vertical velocity of fluid is higher when heater is vertically oriented. The horizontally oriented heater has comparatively less value of thermal entropy generation than vertically oriented heater but horizontally oriented heater has higher value of fluid friction irreversibility. In summary, horizontally oriented heater has comparatively higher value of total entropy generation than vertically oriented heater. Bejan number is higher for horizontally oriented heater. In overall study, the value of Bejan number is less than 0.5; therefore, it can be said that fluid friction irreversibility is more dominated than heat transfer irreversibility.

Multi-energy liquid air energy storage: A novel solution for flexible operation of districts with thermal networks

Liquid Air Energy Storage (LAES) stores electricity in the form of a liquid cryogen while making hot and cold streams available during charging and discharging processes. The combination of electricity, hot and cold makes LAES a promising asset for the management of multi-energy streams in various energy systems; however, such opportunity has not received attention so far. To overcome the traditional view of LAES as electricity storage only, this study investigates the techno-economic value of using LAES as a smart multi-energy asset for the provision of heat and cold, alongside power, in districts with heating and cooling networks. A reduced thermodynamic model of LAES was developed, validated and used to i) quantify the thermodynamic efficiency for a multi-energy LAES, ii) generalise the multi-energy capability of LAES over the three energy vectors considered iii) link different plant designs and integration conditions – in terms of loads and temperatures – with the associated multi-energy LAES performance and iv) describe multi-energy LAES operation as part of two district sizes, for provision of peak and base load. It is found that, by leveraging the vector-coupling capability of LAES, more flexible district operation can be achieved, with increased LAES energy efficiency from 47% to 72.8% and up to 8–12% reduction of operational costs, in the considered integration case studies. Results demonstrate the technical feasibility of multi-energy LAES operation and illustrate the associated trade-offs and potential: new perspectives for smart management of multi-energy systems are opened up.

Black Hole-Inspired Optimal Design of Biomethane Liquefaction Process for Small-Scale Applications

Biomethane is regarded as a promising renewable energy source, with great potential to satisfy the growth of energy demands and to reduce greenhouse gas emissions. Liquefaction is a suitable approach for long distances and overseas transportation of biomethane; however, it is energy-intensive due to its cryogenic working condition. The major challenge is to design a high-energy efficiency liquefaction process with simple operation and configuration. A single mixed refrigerant biomethane liquefaction process adopting the cryogenic liquid turbine for small-scale production has been proposed in this study to address this issue. The optimal design corresponding to minimal energy consumption was obtained through the black-hole-based optimization algorithm. The effect of the minimum internal temperature approach (MITA) in the main cryogenic heat exchanger on the biomethane liquefaction process performance was investigated. The study results indicated that the specific energy consumption of modified case 2 with MITA of 2°C was 0.3228 kWh/kg with 21.01% reduction compared to the published base case. When the MITA decreased to 1°C, the specific power of modified case 1 reduced to 0.3162 kWh/kg, which was 24.96% lower than the base case. In terms of exergy analysis, the total exergy destruction of the modified cases 1, 2, and 3 was 31.28%, 22.27%, and 17.51% lower than the base case, respectively. This study’s findings suggested that introducing the cryogenic liquid turbine to the single mixed refrigerant-based biomethane liquefaction process could reduce the specific energy consumption and total exergy destruction significantly. Therefore, this study could provide a viable path for designing and improving the small-scale biomethane liquefaction process.

Experimental study of low-cycle fatigue of S30408 welded joints with strain strengthening

With the change of energy consumption structure, cryogenic liquids are increasingly widely used, such as liquefied natural gas (LNG), liquid hydrogen, liquid nitrogen, etc. Austenitic stainless steel is widely used in fabrication of cryogenic temperature pressure vessels as a kind of material with good lower temperature resistance. It is difficult to give full play to the high tensile strength and high plasticity reserve of austenitic stainless steel by using conventional design methods, which results in material waste and cost increase. The strain strengthening technology of austenitic stainless steel is the more effective method to realize the lightweight design and manufacture of cryogenic pressure vessel and reduce the cost. Fatigue damage is one of the typical failure modes of cryogenic pressure vessels. For the fatigue design of conventional pressure vessels, there are detailed standards, but there are few specific provisions for the fatigue design of strain strengthening pressure vessels. In this paper, experimental study on the low-cycle fatigue behavior of S30408 welded joints with 7% and 9% pre-tensile deformation were carried out.

Preface

It is our great pleasure to report that the Proceedings of joint meeting of the 10th Asian Conference on Applied Superconductivity and Cryogenics (ACASC), 2nd International Cryogenic Materials Conference in Asia (Asian-ICMC), and the CSSJ meeting held at Okinawa, Japan, between January 6 to 9, 2020 is published in Journal of Physics: Conference Series (JPCS).…Total numbers of participants and presentations of the 10thACASC/2ndAsian-ICMC/CSSJ Joint Conference are 381 from 13 countries and 276 including 4 plenary lectures, 5 invited talks for Asian topics, respectively. This conference consisted of many sessions, such asCryogenic structural materials, Superconducting materials, Wire and Tapes (Nb3Sn, Nb3Al, BSCCO, REBCO, MgB2, Fe-based), Cryogenic Cooling Engineer ing, Magnet Technology, Power Applications (Motors, Generators, Cables, FCL, SMES and others), Liquid Hydrogen, Aircrafts, Motors and Maglevs, Superconducting Bulks, Evaluation and Analysis, Database of Cryogenic Structural Materials, Electronics, Superconducting Joints.…List of Editors and Program Committee, Organizing Committee are availble in this pdf.

The Role of Small Scale Experiments in the Direct Detection of Dark Matter

In the direct detection of the galactic dark matter, experiments using cryogenic solid-state detectors or noble liquids play for years a very relevant role, with increasing target mass and more and more complex detection systems. But smaller projects, based on very sensitive, advanced detectors following new technologies, could help in the exploration of the different proposed dark matter scenarios too. There are experiments focused on the observation of distinctive signatures of dark matter, like an annual modulation of the interaction rates or the directionality of the signal; other ones are intended to specifically investigate low mass dark matter candidates or particular interactions. For this kind of dark matter experiments at small scale, the physics case will be discussed and selected projects will be described, summarizing the basics of their detection methods and presenting their present status, recent results and prospects.

Retrofitting recycled stripping gas in a glycol dehydration regeneration unit

Abstract Natural gas dehydration is essential in gas processing to avoid serious problems. As a pretreatment in a cryogenic Natural Gas Liquid (NGL) recovery process, it typically uses triethylene glycol (TEG) and followed by a Molecular Sieve dehydration to achieve 1 mg/Sm3 of water moisture in the dehydrated gas. This work studied the retrofitting of the existing dehydration unit to improve its performance in satisfying the gas moisture qualities. The retrofitted process uses recycled stripping gas schemes to achieve high purity TEG while minimizing the use of fresh stripping gas. The results revealed that the recycled stripping gas has provided sufficiently high purity TEG (>99.99%-wt), significantly reduced the heating and cooling duty by 80%, and reduced the electrical duty by 29% compared to the base case. The TAC was reduced by 38.1% from $ 725,245/year to $ 448,670/year. Through this study, the evaluated cases provide similar dehydration results with less equipment, simpler process, more energy-efficient, and better economic numbers. Therefore, a better process was obtained.

Main aspects of liquefied natural gas process line thermal and hydraulic calculations

The rapid growth of liquefied natural gas consumption makes the issues of its transportation more urgent. At present, liquefied natural gas pipeline transportation is carried out only by means of short length process lines. This paper discusses the main features of cryogenic liquids pipeline transportation that obstruct its spread. The proposed model allows to carry out thermal and hydraulic calculations of an underground cryogenic pipeline. The distinctive feature of this model is the fact that it takes into account the changes in basic thermodynamic parameters of cryogenic liquid. The model is based on the Darcy-Weisbach equation and a differential heat transfer equation. In addition, the influence of the Joule-Thomson coefficient inversion on the temperature of the pumping cryogenic liquid was discussed. The comparative analysis of the pipeline construction efficiency made of ultra-high molecular weight polyethylene and AISI 321 steel was conducted. It was found that the use of polymer materials contributes to an increase in the transportation distance. The developed model can be applied for estimation of the transportation parameters change of single-phase fluid flow. The obtained results can be used in initial analysis of the process lines designing and construction.

Predicting the vaporization rate of a spreading cryogenic liquid pool on concrete using an improved 1-D heat conduction equation

The accidental spilling of cryogenic liquid leads to formation of a spreading pool, which may result in pool fires, BLEVE(boiled liquid evaporate vapor explosion) or vapor cloud fire, such as liquefied natural gas, is flammable. The key aspect of evaluating the consequence of such a disaster is to predict vaporization rate of the spreading cryogenic liquid pool. In this study, an empirical function was established to predict the temperature gradient of concrete. Afterwards an improved 1-D heat conduction equation was established to predict heat conduction of the spreading cryogenic liquid, and then vaporization rate was measured. In addition, to validate accuracy of the improved 1-D heat conduction equation, small-scale experiments were conducted to calculate vaporization rate for a spreading cryogenic liquid pool. The resulting vaporization rate decreased with discharge time, and increased with spill rate. The established empirical function was used to predict the temperature gradient displayed satisfactory accuracy with absolute average relative errors (AAREs) less than 10%; the improved 1-D heat transfer model AAREs were less than 13% compared with the experimental value. In summary, the improved 1-D heat transfer model can be applied to predict vaporization rate if the spill rate and discharge time are confirmed.

Experimental study on thermoelectric power generation based on cryogenic liquid cold energy

A large amount of cold energy can be recovered while in use because of the large temperature difference between the cryogenic fluid and the ambience. This study designed and built a thermoelectric power generation system for cold energy. Taking liquid nitrogen as the cryogenic liquid, the thermoelectric characteristics of the system were studied experimentally. In addition, the influence of the heat transfer process of the cryogenic fluid on the thermoelectric characteristics was determined. The results revealed that in the liquid-phase and two-phase regions, the temperature difference between the hot and cold end increased in the gasification process. However, in the gas-phase region, it first decreased and then increased. The temperature difference between the hot and cold module ends was small, being only 7.2–28.1 °C. The poor heat transfer capacity at the hot end of the generator restricted the improvement of the temperature difference at the hot and cold ends. Nevertheless, the flow rate change had a relatively small impact on the open-circuit voltage. Although the thermoelectric conversion efficiency remains low, it is expected that the efficiency can be significantly improved by developing high-efficiency low-temperature thermoelectric materials and by improving the heat exchange performance of the hot end of the generator.

Experimental and Numerical Investigation of Heat Transfer Processes in Rocket Engine Cooling Channels Operated with Cryogenic Hydrogen and Methane at Supercritical Conditions

Hydrogen and Methane are two fluids that are either used or in discussion as propellants for upper and lower stage rocket engines. The conception of a regenerative cooling system is a crucial part in the design of a rocket engine and so is the detailed knowledge of the coolants behavior and the heat transfer capabilities. Hydrogen is a very efficient and well known cooling fluid whereas the properties of methane as a cooling fluid are intensively investigated nowadays. Experiments were performed with a subscale combustion chamber that is divided into four sectors around the circumference each containing rectangular cooling channels with different aspect ratios. Cryogenic hydrogen and liquid methane were used as cooling fluids. These experiments provide a broad data basis that is used for the validation of CFD simulations. The simulations are capable of predicting wall temperatures for high pressure conditions. Thermal stratification effects that are known to limit cooling properties in high aspect ratio cooling channels arise for both fluids, but the effects are much stronger for hydrogen compared to methane. However in the vicinity to the critical point, when it comes to heat transfer deterioration, the simulations show large deviations to the experimental values.

The Methodology for Calculating the Hydrodynamic Characteristics of a Mechanical Seal with Leakage Steam Formation

This paper presents the numerical methods for calculating the hydrodynamic characteristics of a mechanical seal, taking into account the possibility of a phase transition in its gap. In the numerical model, the solutions are used for the flow of both liquid and gas in the microgap of compaction obtained using the finite volume method. Regularities of the influence of the size and taper of the gap, the depth of the microgrooves, the pressure drop and the value of the saturated vapor pressure on the hydrodynamic characteristics of the seal are revealed. A method has been developed for calculating leaks, the stiffness of the lubricant layer, and the friction power in the seal gap, taking into account vaporization and thermal deformations of the sealing rings. Recommendations for the selection of the geometric parameters of the seal are offered. The cause of pulsating seal leakage has been identified. The developed technique is applicable both for cryogenic liquids and for water.

Modeling of the cooling process of long pipelines for transportation of liquid hydrogen

A simplified model of cooling long insulated pipelines with liquid hydrogen flowing through them has been developed. The model allows us to determine the flow parameters at different points in time and to estimate the pipeline cooling time. When developing the model, the following assumptions were made: the linear velocities of the liquid and vapor are equal, the phases are in a state of thermodynamic equilibrium, the dependencies obtained for a single-phase flow are applicable to determine the friction coefficient of a two-phase flow. Based on the model, an automated algorithm for calculating the cooling process of a long pipeline with cryogenic components was developed. It allows us to obtain data for plotting the temperature fields of the pipeline walls and the flow of the transported cryogenic liquid at different times, as well as to determine the cooling time of the pipeline and the moment of the onset of a stationary single-phase flow. The calculation results are in good agreement with the experimental data.

Experimental and Numerical Investigation of Change in Boil-Off Gas and Thermodynamic Characteristics According to Filling Ratio in a C-Type Cryogenic Liquid Fuel Tank

Experimental and Numerical Investigation of Change in Boil-Off Gas and Thermodynamic Characteristics According to Filling Ratio in a C-Type Cryogenic Liquid Fuel Tank

Practical Prediction of the Boil-Off Rate of Independent-Type Storage Tanks

Because environmentally-friendly fuels such as natural gas and hydrogen are primarily stored in the form of cryogenic liquids to enable efficient transportation, the demand for cryogenic fuel (LNG, LH) ships has been increasing as the primary carriers of environmentally-friendly fuels. In such ships, insulation systems must be used to prevent heat inflow to the tank to suppress the generation of boil-off gas (BOG). The presence of BOG can lead to an increased internal pressure, and thus, its control and prediction are key aspects in the design of fuel tanks. In this regard, although the thermal analysis of the phase change through a finite element analysis requires less computational time than that implemented through computational fluid dynamics, the former is relatively more error-prone. Therefore, in this study, a cryogenic fuel tank to be incorporated in ships was established, and the boil-off rate (BOR), measured considering liquid nitrogen, was compared with that obtained using the finite element method. Insulation material with a cubic structure was applied to the cylindrical tank to increase the insulation performance and space efficiency. To predict the BOR through finite element analysis, the effective thermal conductivity was calculated through an empirical correlation and applied to the designed fuel tank. The calculation was predicted to within 1% of the minimum error, and the internal fluid behavior was evaluated by analyzing the vertical temperature profile according to the filling ratio.

Research on attitude control strategy of single engine failure in the first-stage flight phase of new generation launch vehicle

The successful launching of the new generation of launch vehicle is of great practical significance to the development of China Space, and the cryogenic liquid engine commonly used in the launch vehicle has a certain probability of failures, which may affect the success or failure of rocket launching. In this paper, a Bolza problem optimization algorithm based on Radau pseudo-spectral method is proposed to solve the problem of single engine failure in the first-stage flight phase of the new generation launch vehicle by simulating fault injection and taking the attitude angle as optimal control quantity. The simulation results show that this method can effectively eliminate the influence of single engine failure on orbit injection accuracy, achieve the fault absorption of new generation launch vehicle engine, improve the fault tolerance of attitude control system, and further guarantee the system reliability.