Steam Jet Research Articles

Numerical simulation of boiling dynamics in liquid Lead-Bismuth injected with multi-rupture high-pressure water jets

Once a steam generator tube rupture (SGTR) accident occurs in a lead-based fast reactor, it can trigger a domino effect of heat transfer tube ruptures, leading to a loss-of-flow accident involving multiple ruptures. This paper employs numerical methods to investigate the jet boiling phenomenon associated with the injection of sub-cooled water into high-temperature lead‑bismuth eutectic (LBE) through multiple nozzles. It explores how nozzle spacing, number, and diameter impact jet characteristics. Additionally, it analyzes flow characteristics and heat transfer mechanisms from the perspective of jet interaction. The study identifies critical areas within the multi-nozzle jet, specifically the three-phase mixing region, LBE entrainment region, water core region, and steam plume region. In scenarios where nozzle spacing is narrow or nozzle diameters differ significantly, the jet's base may undergo fragmentation. The jet process is categorized into two stages: the transition stage and the stable stage. During the stable stage, the mass flow rate of sub-cooled water remains relatively constant, with nozzle spacing exerting minimal influence on it. When considering the cross-sectional area of a single nozzle, an increase in nozzle diameter elevates the normalized mass flow rate, whereas the number and diameter of nozzles have little effect on it. Jet penetration depth is inversely related to nozzle spacing. As the number and diameter of nozzles increase, penetration depth initially rises and then decreases. Nozzle spacing has a minor influence on the jet's steam volume, while the number and diameter of nozzles are positively correlated with steam volume. Conversely, the number and diameter of nozzles negatively correlate with normalized steam volume.

Control of Liquid Hydrocarbon Combustion Parameters in Burners with Superheated Steam Supply

A numerical simulation of reacting mixture flow in a full-scale combustion chamber of a prototype burner with a fuel-sprayed jet of superheated steam and a controlled excess air ratio was performed based on a verified model. The influence of steam jets on the combustion parameters of the created prototype device was analyzed based on the results, and a comparison with data from various atmospheric burners, including evaporative and spray types, direct-flow and vortex types, and those with natural and forced (regulated) air supply, was made. Various schemes for supplying steam to burner devices were discussed. It was shown that the relative steam consumption is a parameter for controlling the emission of toxic combustion products, such as NOx and CO, for all designs. A high burner performance is achieved when superheated steam is supplied at more than 250 °C with a relative steam flow rate of >0.6. The design features of the burner systems and operational parameters that ensure high thermal and environmental efficiency when burning various types of fuel and waste are identified.

Experimental investigation of the swirling steam jet condensation at low mass flux

Swirling steam jet condensation holds significant applications in industrial processes such as nuclear safety and gas–liquid mixing in the oxygen transmission pipeline of the liquid rocket engine. However, due to its involvement with complex flow and phase-change heat transfer, the application and optimization of related condensation technologies still face challenges. Therefore, this paper aims to investigate the condensation characteristics of the swirling steam jet by numerous experiments. The steam mass flux is 15–45 kg/(m2·s), and the water temperature ranges from 40 to 85 °C. A novel X-type swirl pressure nozzle is selected to achieve the swirling flow of the steam jet. A comparative analysis is conducted on the interface behavior and evolution of condensation parameters of the non-swirling and swirling steam jets during condensation processes. Results show that the swirling jet condensation includes three flow patterns, namely, chugging regime, smooth grown bubble regime, and rough grown bubble regime. Compared with the non-swirling steam jet condensation, swirling steam jets exhibit a 10.36% increase in the smooth grown bubble regime region and a 14.63% decrease in the rough grown bubble regime. Swirling bubble morphology evolves steadily, and the surface is smoother and more rounded. Simultaneously, irregular deformation behaviors can also occur in the swirling bubble condensation process, such as spiral growth of jet bulge, neck torsion, and the corolla pattern. This deformation helps to increase the contact area and prolongs the bubble lifetime, allowing for more adequate heat transfer at the steam–water interface. The swirling motion of the steam jet will reduce the bubble collapse frequency. As the water temperature rises from 60 to 80 °C, the bubble condensation rate and collapse frequency decrease. The bubble radius increases and the condensation time is extended. With the increasing steam mass flux, the collapse frequency gradually increases. The condensation rate and the bubble radius vary nonlinearly. At the higher steam mass flux, the swirling motion can effectively release the heat that accumulates inside the bubble after reaching the condensation equilibrium state.

Performances of the ITER Pressure Suppression System during unstable steam condensation regimes

Abstract The paper deals with the qualification of the main safety system of the nuclear fusion reactor ITER: the Vacuum Vessel Pressure Suppression System (VVPSS). This safety system manages the Loss of Coolant Accident (LOCA), that could occur in the Vacuum Vessel (VV), avoiding a significant increase of the internal pressure that could breach the primary confinement barrier. Steam condensation occurs at sub-atmospheric pressure. This condition is original respect the usual applications of steam direct condensation in nuclear fission reactors. An extensive experimental research program, funded by ITER Organization, on reduced scale experimental rigs (scale 1/22 and 1/10) have been carried out at the University of Pisa. Unstable condensation regimes occurred during some tests at about 500 g/s of steam mass flow rate (10 % of the maximum steam mass flow rate foreseen for the relevant accidental scenarios). In these conditions, high intensity vibrations of the whole experimental rig occurred. These events can be classified as ‘Chugging’ or Condensation Induced Water Hammer (CIWH). 
The performed tests have been analysed elaborating the images of the video-cameras located in the pool and comparing the steam jet shape with the acceleration values recorded by an accelerometer mounted on the sparger structure.
These elaborations permitted to evaluate the dynamic of bubble collapse, the volume of the developed external bubbles, the collapse frequency as function of thermal-hydraulic parameters. 
Moreover, the paper emphasizes the beneficial effects of non-condensable gases on the unstable condensation regimes. In fact, the non-condensable gas inhibits the occurrences of Water Hammer inside the sparger and eliminates the thermal stratification inside the water pool increasing the turbulence.

Numerical heat transfer analysis of steam injection into subcooled water

Steam direct contact condensation (DCC) into subcooled water may be encountered in different important industrial process applications, such as steam jet pumps, steam ejectors, pressurizers, and emergency cooling systems of nuclear reactor core. In this work, a numerical simulation study has been done for injection of steam into a tank full of subcooled water. In the simulations, the Eulerian multiphase flow in addition to a realizable k-epsilon turbulence model has been utilized. Moreover, a DCC model has been used for condensation capturing. Fluent software with a user-defined function (UDF) for the DCC model was employed for simulations. The results obtained from simulations were validated with experimental results, and a fair agreement was observed. This study considered the local Nusselt number (LNN) the most suitable parameter for investigating the heat transfer rate (HTR) at the computational cell level. Therefore, the contours of the LNN, its axial distribution, and radial distribution were studied with respect to the inlet pressure of injected steam, temperature of tank water, and location along the axis of the nozzle. The results reveal the fact that the value of the LNN reaches a maximum at the nozzle exit along the axis of the nozzle at 323 K tank water temperature. LNN decreases by increasing or decreasing the tank water temperature beyond 323 K. It is claimed that the heat transfer (HT) study at such a local scale has been conducted for the first time to the best of our knowledge, and it unfolds various crucial facts regarding steam-water interaction.

Numerical Simulation of Steam Jet Condensation Through a Triple Nozzle Submerged into a Subcooled Water Pool

Submerged steam jet condensation is widely applied in many industrial fields due to its high heat and mass transfer efficiency during the process of direct contact condensation (DCC). The injection of steam into a water pool usually passes through an array of nozzles. It is important to understand the interaction between neighboring jets from different nozzles. In this paper, two thermal resistance models for DCC are implemented into the computational fluid dynamics code ANSYS Fluent through a user-defined function. The triple steam nozzle cases, in which the inlet pressure ranges from 0.1 to 0.6 MPa, were investigated to understand the interaction of nozzles and their configuration as well as their mechanisms. The distributions of temperature, velocity, volumetric fraction, and pressure fields were analyzed for different cases. Furthermore, the plumes of steam jets always attract each other toward the center of the plumes, and when the inlet pressure is over 0.3 MPa, the mixing of neighboring steam plumes will occur. In addition, the location where the peak value occurs for the parameters of steam velocity, pressure, and temperature, etc. is getting closer and closer to the center of the flow domain. In addition, the curve of the pressure along the centerline of the nozzle verified the existence of compression and expansion of steam inside the plume.

Effect of Nozzle Quantity on the Flow Field Characteristics and Grinding Efficiency in a Steam Jet Mill

A steam jet mill (SJM), which employs industrial waste heat steam as a gas source, is a widely utilized apparatus for the pulverization of fly ash. To achieve elevated single-machine grinding capacity, efficiency improvement research based on structural optimization should be conducted. In this study, numerical simulations and industrial experiments are carried out on SJMs equipped with three and six nozzles (hereinafter referred to as N3 and N6, respectively) to study the influence of nozzle quantity on the flow field and grinding efficiency. The numerical simulation results indicate that, under the N3 structure, particles can achieve a higher impact velocity in the comminution area and improve the kinetic energy of a single impact. In the conveying area, the airflow diffusion is better, resulting in an upward flow field that is more uniform. The classification area shows an increase in the uniformity of the flow field and a significant reduction in the local vortex structure, which is beneficial for accurate particle classification. In the interim, industrial experiments demonstrate that the N3 structure can markedly enhance the processing capacity and energy efficiency of the system. The smaller the feed particle size, the more pronounced the efficiency improvement.

Evaluasi Kinerja Steam Jet Ejector Tingkat Pertama Terhadap Kevakuman Kondensor

The steam jet ejector is a device for extracting NCG from the condenser. NCG can increase the pressure in the condenser until a vacuum condition is not reached. The diffuser pressure on the steam jet ejector has a normal operational limit of below 1 atm, meaning that the ejector performance will be optimal if it is operated at the operational limit under vacuum conditions. The expected objectives are to determine the effect of the steam jet ejector on condenser vacuum, calculate the performance of the first level steam jet ejector through pressure analysis in the diffuser section, calculate the performance of the steam jet ejector in actual conditions compared to the design data conditions and analyze actions that can be taken to improve the performance of the tool. Based on the results of calculations and analysis, it was found that the increase in steam jet ejector pressure had an effect on the increase in condenser pressure from the design pressure of 0.10 bar to 0.107-0.123 bar under actual conditions. The decrease in steam jet ejector performance results in the condenser vacuum level decreasing, but the equipment performance is within normal operational limit conditions, namely below 1 atm. The decrease in steam jet ejector performance is influenced by the motive steam mass flow rate, NCG mass flow towards suction, entrainment ratio value, NCG pressure and motive steam pressure which exceeds the design data.

Investigation into negative corona discharge in steam jets and distribution characteristics of charged steam jets

Electricity provides a wide range of benefits for plant growth, and the electric field created by a charged steam jet exhibits significant potential for application in this field. This study investigates the electrical characteristics of charged steam jets, including the corona-discharge process, distribution of electric fields, and deposition currents. By installing a needle-ring electrode near the steam-jet exit, high-potential charged steam is generated within a confined space through the corona charging of droplets in the steam. The humid environment inside the steam jet considerably reduces the corona current compared with that of air. The outlet current is identified as a critical factor for assessing the charged steam-jet behaviour, with a higher outlet current indicating a stronger electric field and deposition current. The configuration of the electrode and the steam operational conditions, particularly the latter, affect the outlet current. Experimental results highlight the different electrical distribution characteristics of wet and saturated steam jets. Notably, the distributions of electric field and deposition currents, along with the depositional droplets and absolute-humidity increments exhibit asymmetry above and below the steam jet. This paper presents a discussion on the formation, development, and dissipative processes of charged droplets and an analysis into their possible movement trajectories under various forces. Generally, the asymmetric distribution of charged steam jets is caused by the asymmetric distribution of charged droplets or water-cluster molecules, which becomes more pronounced as one departs further from the steam-jet exit.

Experimental study on effect of submergence depth on steam jet shape characteristics in direct contact condensation

The phenomenon of direct contact condensation is frequently utilized in the industrial sector due to low driving potential requirements and proficient heat and mass transfer characteristics. This experimental study investigates the influence of nozzle submergence depth by condensing steam through a straight pipe (SP) and converging-diverging (CD) nozzle. The effect of operating conditions i.e. steam pressure and water temperature in addition to nozzle geometry were also studied on steam cavity shape characteristics. Six different shapes were manifested including unstable, conical, ellipsoidal, cylindrical, divergent, and double expansion-contraction. The dimensionless penetration length of plumes was observed in a range of 1.46–3.91 and 2.14–4.41 for the CD and SP nozzle, respectively while the maximum expansion ratio was determined to be 1–1.25 for the CD nozzle and 1.16–1.58 for the SP nozzle. It has been observed that jet length increases with an increase in submergence depth, steam pressure, and water temperature. The maximum expansion ratio was observed to decrease with the increase in submergence depth and increase with an increase in steam pressure and water temperature. The empirical correlations for dimensionless penetration length were developed and predicted results were found to be lying between ±10 % and ±7 % for CD and SP nozzle respectively.

Experimental Study of Influence of Initial Air Temperature on Characteristics of Combustion of Diesel Fuel Atomized by Jet of Superheated Steam

Experimental Study of Influence of Initial Air Temperature on Characteristics of Combustion of Diesel Fuel Atomized by Jet of Superheated Steam

Numerical simulation of jet boiling characteristics of high-pressure water injected into high-temperature liquid lead–bismuth in a confined space

The steam generator heat transfer tube rupture (SGTR) accident is potentially devastating and is one of the most serious design basis accidents for lead–bismuth cooled fast reactor (LFR). It is important to study the mechanism of water jet injecting into liquid lead–bismuth eutectic (LBE) for the safety analysis of SGTR accidents. In this paper, based on the volume of fluid (VOF) model, the large eddy simulation (LES) turbulence model and the Lee phase transition model, a three-dimensional numerical model is developed to investigate the typical characteristics of a high-pressure sub-cooled water jet injecting into high-temperature LBE in a confined space. The study focuses on examining the impact of water temperature, inlet pressure, and nozzle diameter on jet development and its surroundings, including the cover gas layer and LBE phase. The results indicate that the central region of the jet is primarily subject to flash boiling, particularly at the nozzle position, whereas the jet interface undergoes heat-transfer boiling. The residual liquid phase migrates upward along the interface and gradually boils. Based on the phase distribution characteristics, a typical jet can be categorized into four zones: the water-steam transition zone, the multiphase flow zone, the end water phase zone, and the steam block zone. Under the conditions analyzed in this paper (water temperature 140–260 °C, injection pressure 2–10 MPa, nozzle diameter 2–10 mm, LBE temperature 400 °C), the jet volume expands approximately exponentially, correlating positively with the three factors studied. It is also found that at high injection pressures and large nozzle diameters, the steam at the top of the jet is prone to destabilization and fragmentation, with steam volume and pressure oscillations being the dominant factors. Steam migration triggers pressure oscillations in the LBE region, and the intensity of these oscillations is closely linked to the migration rate. Under the conditions studied, the maximum pressure oscillation reached 5.5 times the initial pressure. The expansion of the jet steam drives the pressurization of the cover gas layer, which correlates positively with all three factors studied. The nozzle diameter has the greatest effect, increasing the maximum pressure by 168 % from the initial pressure.

Structure and functionality of surface-active amylose-fatty amine salt inclusion complexes

Novel value-added starch-based materials can be produced by forming amylose inclusion complexes (AIC) with hydrophobic compounds. There is currently little research on AIC use as polymeric emulsifiers, particularly for AIC with fatty amine salt ligands. This work evaluated AIC emulsifiers by studying the structure and functionality of AIC composed of high amylose corn starch and fatty amine salts (10–18 carbons, including a mixture simulating vegetable oil composition) produced via steam jet cooking. X-ray scattering verified successful AIC formation, with peaks located near 7.0°, 12.8° and 19.9° 2θ. AIC were easily dispersed in water (80–85 °C) and remained in suspension at room temperature for weeks, unlike the uncomplexed ligands or starch. AIC were highly effective emulsifying agents, with emulsifying activity indexes of 213–229 m2g−1 at pH 5, and zeta potentials, a measure of electrostatic repulsion, as high as 43.4 mV. AIC dispersions had surface tension ranging from 24 to 41 mN/m and displayed surface-active properties superior to amylose complexes formed from fatty acid salts and competitive with common starch-based emulsifiers. These findings demonstrate that fatty amine salt AIC are effective emulsifiers that can be made from low-cost sources of fatty amine salts, such as vegetable oil derivatives.

Investigation of the effect of a high-speed steam jet on viscous oil using the SAGD method

Investigation of the effect of a high-speed steam jet on viscous oil using the SAGD method

Visual observations of steam–air submerged horizontal jets at low mass flux

Steam jet condensation at low mass flux is important especially in start-up, shutdown or accident conditions of various applications. Visual experiments of steam–air submerged jets through horizontal pipe were conducted in the ranges of mass flux 0–––20 kg/m2s, air mass fraction 0–––0.02, and water temperature 20 − 80℃. In pure steam jets, three condensation regimes of no bubbling, intermittent bubbling, and continuous bubbling were identified in steam jets. In no bubbling regime, rolling up and billows of plane shear flow were observed. In intermittent bubbling regime, large bubble was generated, detached and collapsed intermittently, accompanied by fluid oscillations. The bubble forming frequency increased with the rise of water temperature. Condensation heat transfer coefficients tends to decrease as the steam mass flux increases. In continuous bubbling, fluid oscillation no longer occurred. The bubble forming frequency decreased with the rise of water temperature. Condensation heat transfer coefficients increase as the steam mass flux increases. In the cases with shallow submerged depth, air-entrained vortex, surface water jets, and splash were observed after bubble condensation. In steam–air jets, condensation became stable and small bubbles increased. The condensation regime transitioned from intermittent bubbling to continuous bubbling earlier.

Numerical simulation on the effect of non-condensable gas on direct contact condensation of steam jet in a narrow pipe

A numerical model was developed to investigate the phenomenon of direct contact condensation involving steam-air jet in subcooled waterflow. This study encompassed a comprehensive exploration of the influence exerted by non-condensable gas from a multi-faceted perspective. These aspects included an examination of gas plume shape, distribution of air mass fraction, variation in axial thermodynamic parameters, the local heat transfer coefficient, and the local condensation rate. It was observed that the presence of non-condensable gas had the effect of extending the penetration length of the steam plume. Notably, the non-condensable gas was predominantly concentrated in proximity to the gas-liquid interface, a phenomenon that introduced hindrances to both heat and mass transfer processes. A detailed analysis of axial thermodynamic parameters further unveiled an intriguing trend. As the air content increased, the expansion of gas plume weakened, subsequently leading to a reduction in the condensation rate. This resulted in diminished pressure fluctuations in the two-phase mixing region. Moreover, the presence of non-condensable gas was shown to curtail the local heat transfer coefficient and the local condensation rate at the interface. This observation offered valuable insights into the underlying mechanisms responsible for the protraction of the gas plume.

The effect of the nozzle exit geometry on the flow characteristics of the free condensing jet

In the present study, we investigated the velocity distribution, temperature distribution and condensation characteristics of steam jet issuing from four different orifice nozzles with a Reynolds number of approximately 79,000 using the phase Doppler particle analyzer system and a K-type thermocouple. The steam jet discharged from the orifice nozzle has a wider jet width compared to pipe nozzle because of the vena-contracta which can enhance the mixing of steam jet with the ambient air. Therefore, the orifice jet showed less condensation due to its wideness, resulting in small velocity decay rate and large temperature decay rate due to momentum conservation and decreased latent heat release compared to pipe nozzle, respectively. Also, the wider jet width of the orifice jet resulted in larger velocity and temperature spread rate compared to the pipe jet. In addition, the increase in the aspect ratio of the orifice jet led to more condensation and larger velocity spread rate and temperature spread rate due to both the vena-contracta and axis-switching effect, resulting in the increase of jet entrainment.

Experimental Study of Kerosene Combustion Characteristics in a Jet of Superheated Steam with a Controlled Air Excess

Experimental Study of Kerosene Combustion Characteristics in a Jet of Superheated Steam with a Controlled Air Excess

Innovative thermo-compressor nozzle design for enhanced mixing in TVC desalination plants

This paper introduces an innovative nozzle design for steam jet thermo-compressors used in Thermal Vapor Compression (TVC) desalination plants. Using advanced computational techniques, we compare the performance of the novel nozzle design with a traditional conical nozzle under identical conditions. Resultsunequivocally show that the novel thermo-compressor nozzle design enhances mixing and increases entrainment ratios compared to the conventional nozzle across different conditions. Additionally, we explore a variant of the new design featuring a carefully tuned divergent shape, showing potential for further improving entrainment ratios.This research opens new avenues for optimizing thermo-compressor technology in TVC desalination plants, improving mixing efficiency, and potentially enhancing the overall desalination process.

Techno-economic assessment of a novel integrated multigeneration system to synthesize e-methanol and green hydrogen in a carbon-neutral context

A novel and efficient multigeneration system aiming to achieve near-zero CO2 emissions is proposed. The system employs a methanol production process utilizing captured CO2 from the flue gas of a biomass-gasification plant. The proposed system successfully generates green H2 through water electrolysis, supported by thermal power, with a portion of the hydrogen reacting with CO2 to produce e-methanol. Additionally, the system produces other valuable products, including power, cooling, O2, and CO2, in a coherent manner, benefiting from a low-emission framework and exhibiting high thermodynamic performance. The proposed multigeneration system consists of a biomass-gasification-based power plant, a water electrolyzer, a methanol generation unit, a carbon capture unit, and a steam jet ejector-based refrigeration cycle. The integrated multigeneration system is analyzed from the energy, exergy, and economic aspects. The results demonstrate the system's ability to achieve production rates of 430.25 kg/h of e-methanol and 190 kg/h of green H2. Furthermore, the energy and exergy efficiencies of the system are found to be 78.13% and 71.63%, respectively. The CO2 emissions analysis reveals that the proposed system significantly reduced total CO2 emission to 78.5% (0.61 kgCO2/kg). The total cost of production is estimated to be 0.087 $/kg.