Steam Jet Research Articles

Ultrafine biosorbent from waste oyster shell: A comparative study of Congo red and Methylene blue adsorption

High value utilizations of waste oyster shell and industrial waste heat play the crucial roles in field of environmental protection. Crushed shell powder has expended specific surface and exposed chitin and the character makes it suitable for adsorption. Industrial waste heat can be used as energy resource of steam jet mill to produce shell powder with different particle sizes. And this method has relatively great potential in cleaner production since it avoids extra contamination. Average particle size of products decreases sharply from 27.75 μm to 8.15 μm. Specific surface and exposed chitin increase with the decreasing particle size. The results of adsorption experiments indicate powder with smaller diameters has relatively high adsorption capacity of Congo red (CR) increased by 48.3% and Methylene blue (MB) by 62.5% compared with pristine shell powder. Meanwhile, the adsorption capacity of CR is higher than that of MB due to cationic chitin.

Experimental study on steam plume shape characteristics for bevelled spray nozzles exhausting into quiescent water

Steam-water direct contact condensation phenomenon is being widely used in many industries including chemical, thermal and especially in nuclear industry due to its efficient heat and mass exchange capabilities. The present experimental study explores the underlying physics of the steam cavity/plume shapes by condensing supersonic steam exhausting from five different bevelled nozzles into quiescent water tank. Based on the high speed image capturing methodology, the effects of steam pressure, water temperature and nozzle exit inclination angle on the cavity shape characteristics have been studied. Existence of six different plume shapes (oscillatory, conical, expansion–contraction, double expansion contraction, cylindrical and divergent) have been identified. The results show that for a fixed nozzle geometry, with the increase in water temperature and steam pressure, the steam jet becomes lengthy. However, under the same steam pressure and water temperature conditions, the plume shortens with the increase in nozzle exit inclination angle. The dimensionless jet length has been found in the range of 1.26–5.64. Furthermore, it has been observed that steam plume exhausting from bevelled nozzle undergoes deflection from its nozzle symmetry axis possibly due to the pressure difference between upper and lower lip of nozzle. This deflection may either be upward oriented at high steam pressure or downward deflected at lower steam pressure. Additionally, on the basis of findings from 175 No’s of experiments, condensation regime maps have also been developed for bevelled spray nozzle.

Design Parameters on Impingement Steam Jet Heat Transfer of Continuous Liquid Food Sterilization

The effect was clarified of the design parameters on the heat transfer of an impingement steam jet applied to continuous liquid food sterilization with the aim of high heating performance. The study investigated the effects of the steam and water Reynolds number, jet-to-target spacing to jet diameter ratio, and steam temperature on the Nusselt number. The Reynolds number was defined based on steam and water injection plate configurations in turbulent flow. The Nusselt number of the steam temperature at 120 °C was greater than at 125 °C and 130 °C and higher heat transfer was noted at a water nozzle number of two. The Nusselt number was the highest at the jet-to-target spacing to jet diameter ratio (H/d) of 1 and then tended to be constant for H/d above 3. The present study was compared with jet impingement correlations from Huber and Viskanta, and from Martin. In addition, the Ranz and Marshall correlation of a conventional direct steam injection was compared with the impingement method. The sterilization temperature tended to increase as the steam temperature and the number of steam nozzles was increased while the number of product nozzles was decreased.

Accident type analysis and consequence simulation of LNG terminals equipment and facilities

A new round of energy change, energy clean and low carbon development become an inevitable trend. In the adjustment of energy structure, natural gas becomes the strongest growth carrier and LNG reserve peak regulation is of great significance. Building liquefied natural gas receiving center to secure domestic natural gas supply has become the main target, task and key work. Through the simulation of various equipment and facilities in the LNG terminal under different leakage scenarios, the accident scenarios are selected according to the protection distance criteria, the simulation of steam diffusion, pool fire, jet fire and explosion is carried out, and the influence range of consequences is obtained. The thesis provides a theoretical basis for the quantitative risk assessment for LNG terminal accident and the prediction of emergencies, having positive guiding significance for risk management and emergency disposal of new or operating LNG terminals.

Flow Modeling in a Vortex Chamber of a Liquid–Steam Jet Apparatus

The article investigated the flow of boiling streams through a nozzle with an oblique cut. Due to this flow organization, deviation from the nozzle axis at the vortex chamber inlet occurred. The study of flow modeling in the inlet section was carried out. The flow design and the calculation scheme of the vortex liquid–steam jet apparatus were proposed. Analytical expressions between the main operating parameters were obtained according to the developed mathematical model. A recommended oblique-cut angle for the active-flow nozzle was evaluated considering the transition through the first critical section based on the tangential velocity flow model. Validation of the mathematical model in the inlet section of the vortex chamber was provided based on the comparison with available experimental data. Flow visualization in the inlet section of the vortex chamber was obtained. The assumption of uneven flow distribution was confirmed experimentally. Overall, the boiling liquid flow was implemented in the active flow nozzle. The obtained scientific and practical results help to determine geometric parameters and physical characteristics of the vortex-type liquid–steam jet apparatus at the design stage. The obtained results were implemented to modernize vacuum units based on vortex type liquid–steam jet apparatuses.

Study on the Characteristics of Coherent Supersonic Jet with Superheated Steam

By establishing a mathematical model to simulate a mixed jet of oxygen and superheated steam from a coherent supersonic jet oxygen lance, we studied the effect of superheated steam on the fluid characteristics of the mixed jet. The model was initially verified through laboratory experiments prior to analyzing the fluid characteristics of the mixed jet in detail. These characteristics included the jet velocity, the temperature, the turbulent kinetic energy (TKE), and the mass distribution. The results showed that, at an ambient temperature of 1700 K, the jet velocity measured in the laboratory experiment was consistent with the fluid velocity obtained by numerical simulations, with an error of only 2.7%. In a high-temperature environment, the jet velocity of the mixed oxygen and superheated steam jet was increased, the TKE around the center jet was enhanced, the superheated steam exhibited an inhibitory effect on the combustion reaction of annular methane, and the potential core length of the coherent supersonic jet was reduced, which was conducive to methane combustion and delayed the reduction in the central jet velocity.

Numerical analysis of a pre-chamber vortex burner with a steam blast atomizer

The combustion of diesel fuel in a pre-chamber vortex burner with a steam blast atomizer has been studied numerically. The well-proven k-w SST (URANS) model was chosen for calculations. Combustion was simulated using the Eddy Dissipation Concept (EDC) model, taking into account detailed chemical mechanisms in turbulent reacting flows. The results of testing the selected mathematical model showed good agreement of calculations with the known experimental data, a high agreement of the results was achieved: temperature, CO, NOx, O2, and CO2. The influence of steam and fuel flow rates on the flow structure and physicochemical processes in the burner and at the nozzle outlet has been studied. The structure of the flow inside the burner was shown. A high-velocity jet of steam ejects fuel, oxidizer flow and hot combustion products, forming a large zone of circulation and intense mixing. The influence of burner operating regimes on fuel underburning and environmental performance has been investigated. It was found that in the selected range an increase in the relative steam flow rate leads to almost complete combustion of fuel inside the burner. In the combustion chamber with a natural air supply, the excess air ratio was (0.96–1.23). For the considered fuel flow rate of (0.8–1.2 kg/h), the concentration of toxic emissions meets the environmental standard EN:267 – CO < 40 ppm, NOx < 50 ppm. The minimum emissions of CO = 5 ppm and NOx = 27 ppm are achieved at mass steam concentration of 44–50%.

Entraining of dust and steam flux in water pool: experimental and numerical simulations of vapor condensation and dust deposition

This paper deals with experimental tests of steam condensation in a water pool at atmospheric pressure and temperature in the range 15-100 °C. The activity is performed in the frame of a research program, funded by the ITER organization, for the study of dust deposition, produced in the ITER Vacuum Vessel and entrained by the steam and non condensable gas into the Pressure Suppression Tanks in the case of a Loss of Coolant Accident. The steam condensation into a subcooled water pool has been investigated to characterise the condensation regimes occurring during dust deposition tests. The dust distribution on the tank walls strongly depends on the steam jet length and on the effective heat transfer coefficient. Few grams of dust reduce the water transparency, therefore separated tests without dust overcome this drawback. Measurements of the lengths and surfaces of the steam jets (which permit to calculate effective average heat transfer) have been performed by means of image analyses and have been compared with theoretical correlations. The comparison showed a good agreement between the experimental data and theoretical correlations. Useful data have been obtained for implementing numerical models of dust deposition and for understanding the dust distribution on the tank wall obtained in the experimental tests.

Experimental study of the characteristics of heptane combustion in a high-speed steam jet

This paper is devoted to the experimental study of the characteristics of heptane combustion in a high-speed superheated steam jet. The completeness of the combustion under steam gasification conditions and the gas composition of the heptane combustion products cooled to room temperature were determined. The averaged temperature of the flame was measured. It is shown that the presence of superheated steam ensures high combustion efficiency and reduces emissions of nitrogen oxides in comparison with a heated air combustion. It is also shown that the organization of liquid fuel combustion in a high-speed steam jet ensures effective burning of fuel in the absence of nozzles and swirlers.

Experimental Analysis of Steam Condensation Heat Transfer Coefficient in Water Pool at Sub-Atmospheric Pressure

The experimental analysis of steam direct contact condensation in a water pool at sub-atmospheric condition was carried out in relevant configurations for the International Thermonuclear Experimental Reactor (ITER) Vacuum Vessel Pressure Suppression System, during a postulated Ingress of Coolant Event category IV accidental scenario. This transient accident was experimentally simulated in a reduced scale (1:22) facility at University of Pisa, adopting a defined scaling law. The steam jet plumes were video recorded and image analysis was performed at stable and interfacial oscillation condensation regimes, providing steam plume average length and interfacial area. The average heat transfer coefficient was therefore computed and correlated to the condensation driving potential. Also, the steam jet length divided by orifice diameter (L/D) was characterised as function of driving potential. Empirical correlations available in literature at atmospheric conditions were modified for evaluating vacuum conditions peculiarities. The remarkable higher dependence of heat transfer coefficient (HTC) to driving potential parameter, at vacuum conditions, was highlighted by the driving potential exponent equal to 1.2 instead of 0.04 at ambient pressure. The obtained L/D and HTCcorrelations are able to predict with ± 15% and ± 30% of error the corresponding experimental data, respectively.

Design and flow simulation of a micro steam jet pump

The development of micropump is directly related to the popularization and application of microfluidic systems. Recently, microfluidic systems have more urgent requirements for stable operation and simple structure of micropumps. For these purposes, a novel micro steam jet pump which uses planar induction heating to evaporate the initial fluid is presented. This new micropump could generate continuous flow with merits of no moving parts, stable operation and easy integration. A negative pressure is formed flowed with high-speed flow of vapor in the chamber to pump and eject liquid, and then realize continuous pumping. The working chamber of the micropump is calculated with aerodynamic function, and the simulation analysis is carried on with COMSOL Multiphysics 5.5. By changing key working parameters, appropriate working conditions are adopted with simulation analysis. When the primary vapor temperature is 403.15 K, the inlet width of the tapered section of the mixing chamber is 0.4 mm and the outlet width of the diffuser is 0.5 mm, the mingling and enhancing pressure performance of the micro steam jet pump is better. The optimization of design and simulation involved in this paper provided a good guidance for the design and experimental study of the micro steam jet pump.

New ecology safe waste-to-energy technology of liquid fuel combustion with superheated steam

The huge amounts of accumulated unclaimed liquid hydrocarbon waste (waste from oil production and oil refining, etc.) determine the prospects for their involvement in energy production. The Waste-to-Energy technology improves economic efficiency through low energy costs. Efficient use of waste for energy production requires the creation of new technologies with high energy efficiency and low emissions. The paper proposes and substantiates a promising new environmentally friendly Waste-to-Energy method of burning liquid fuel with injection of superheated steam (SIM) to the combustion zone. The authors have developed a new burner to combust liquid waste when producing energy (protected by patents of the Russian Federation), in which the fuel is atomized by a jet of superheated steam. This approach provides efficient fuel dispersion, the ability to burn a wide range of waste, high fuel combustion efficiency, long service life due to the absence of fuel injectors, and reduction of toxic combustion products due to steam. The large-scale introduction of new burners based on the SIM combustion technology requires reliable scientific data and pilot test results. First of all, this is the influence of operating parameters (steam flow rate and temperature, fuel and air flow rates) on the combustion performance in the oil-steam burner being developed. The aim of the work is complex laboratory and experimental studies of the characteristics of fuel combustion in a new burner with a controlled excess air ratio. Forced air supply to the combustion chamber of a steam-oil burner is a novelty of the burner under study. Based on the results of laboratory studies, the optimal ratios of operating parameters were found (fuel, steam and air flow rates: 1:0.8:2.75), which provide the best thermal and environmental performance (NOx<35 ppm, CO < 25 ppm). A significant reduction in the content of nitrogen oxides in the flue gases up to 70% was achieved with a high completeness of fuel combustion due to the joint control of steam concentration and excess factor in the gas generation chamber. This claims the proposed burner as a low emission one. To confirm the achieved effect, in this work, for the first time, experimental tests of the burner were carried out under the operating conditions of a low-power boiler plant (10–40 kW). Successful tests prove the efficiency of using the developed burner for solving the problem of efficient and environmentally friendly combustion of fuel (including liquid combustible waste) for the production of thermal energy at small-scale energy facilities.

Erosion of a helium-rich layer by a steam jet in the presence of an inclined grid: Comparison of the predictions by URANS, STRUC-URANS and LES

Severe accidents in Light Water Reactors (LWRs) involve the production of hydrogen, which may accumulate in the upper regions of the containment and form flammable mixtures with the initial air inventory. To study phenomena related to light gas layer removal, the H2P1_10_2 HYMERES test (Paranjape et al., 2019, 2020) was conducted in the PANDA vessel with the aim of investigating the erosion of a helium-rich layer by a steam jet deflected by an inclined grid. In this paper, we make use of the test data to validate computational fluid dynamics (CFD) simulations of such a transient. The simulation models involve the standard k- ε URANS, the more advanced second generation STRUC- ε URANS, and a coarse Large Eddy Simulation (CLES). All simulations are conducted with the same numerical grid consisting of 3.5 million hexahedral cells. Results show that all models capture well the main physical quantities, namely: the helium erosion rate, the temperatures and the velocities downstream of the obstructing grid. Fine details such as the turbulent kinetic energy (TKE) are better reproduced by the CLES, although the latter miss somewhat the amplitudes due to lack of spatial resolution, especially in the near-field downstream of the grid region. The STRUC- ε model replicates qualitatively the flow field fluctuations in sections of the domain where the spatiotemporal resolution is adequate. Mesh refinement in the jet region shows a substantial quantitative improvement, demonstrating that the STRUC- ε model is superior to traditional URANS when spatial resolution is increased. Finally, the simulations show unmistakably that radiation modeling is necessary to achieve reasonable predictions of the temperature field, as the radiative flux can account for a substantial fraction of the heat transfer to the vessel walls, in particular when convective currents are weak.

Study of steam jet characteristics and regime maps for bevelled spray nozzles exhausting into quiescent water

Steam-water direct contact condensation phenomenon is being widely used in industrial applications due to its rapid heat and mass transfer rates. The present experimental study explores the underlying physics of the steam jet characteristics by condensing supersonic steam exhausting from five different bevelled nozzles into quiescent water tank. Based on the image processing approach, the effects of steam pressure, water temperature and nozzle exit inclination angle on the size and shape of the steam jet have been studied. The dimensionless steam jet length and maximum expansion ratio have been found in the range of 1.18–5.64 and 1.03–2.70, respectively. The results show that the dimensionless penetration length increases with the increase of steam pressure and water temperature, and decreases with increase in nozzle exit inclination angle. Similarly, maximum expansion ratio of steam jet increases with steam pressure, water temperature and nozzle exit inclination angle. It was observed that steam jet exhausting from bevel nozzle undergoes deflection from its nozzle symmetry axis. The deflected angle increases with steam pressure and nozzle exit inclination angle. A theoretical model of steam jet length for bevelled nozzle has also been presented whose accuracy is found to be within ±30% of the experimental data. Additionally, condensation regime diagrams have been proposed on the basis of steam pressure, water temperature and nozzle exit inclination angle. Existence of seven different plume shapes in regime maps have been identified.

An in vitro Assessment of the Haemodynamic Features Occurring Within the True and False Lumens Separated by a Dissection Flap for a Patient-Specific Type B Aortic Dissection.

One of the highest mortality rates of cardiovascular diseases is aortic dissections with challenging treatment options. Currently, less study has been conducted in developing in vitro patient-specific Type B aortic dissection models, which mimic physiological flow conditions along the true and false lumens separated by a dissection flap with multiple entry and exit tears. A patient-specific Stanford Type B aortic dissection scan was replicated by an in-house manufactured automatic injection moulding system and a novel modelling technique for creating the ascending aorta, aortic arch, and descending aorta incorporating arterial branching, the true/false lumens, and dissection flap with entry and exit intimal tears. The physiological flowrates and pressure values were monitored, which identified jet stream fluid flows entering and exiting the dissection tears. Pressure in the aorta’s true lumen region was controlled at 125/85 mmHg for systolic and diastolic values. Pressure values were obtained in eight sections along the false lumen using a pressure transducer. The true lumen systolic pressure varied from 122 to 128 mmHg along the length. Flow patterns were monitored by ultrasound along 12 sections. Detailed images obtained from the ultrasound transducer probe showed varied flow patterns with one or multiple jet steam vortices along the aorta model. The dissection flap movement was assessed at four sections of the patient-specific aorta model. The displacement values of the flap varied from 0.5 to 3 mm along the model. This model provides a unique insight into aortic dissection flow patterns and pressure distributions. This dissection phantom model can be used to assess various treatment options based on the surgical, endovascular, or hybrid techniques.

Experimental and numerical study of a condensing steam jet

ABSTRACT During a severe accident of a light-water reactor, a large amount of water vapor and hydrogen gas are generated, filling up the containment space. The hydrogen concentration in the containment space must be held below the flammable limit, even during a severe accident. The increase and decrease in the water vapor level may result in overpressure and elevation of the hydrogen concentration, respectively. Therefore, the risk of hydrogen in the containment building is closely related to the distribution and behavior of the water vapor. Condensation and evaporation change the concentration of the water vapor. A steam jet is one of the main water vapor condensation mechanisms during the early stages of accident scenarios. We investigated the flow features of the condensation of a steam jet experimentally as well as numerically. For different steam flow rates, flow characteristics induced by water vapor condensation were examined and certain flow features, in this case, the decay and spread of the velocity and temperature were studied. From the numerical study, it was found that a numerical simulation can accurately predict the condensation process from a macroscopic standpoint.

Flow characteristic of steam jet condensed into a water pipe flow - a numerical study

• Numerical simulation of steam jet condensation in subcooled water flow is conducted. • Thermal hydraulic parameters of cone and cylinder-cone steam plumes are analyzed. • The total pressure in the centerline reaches maximum at steam volume fraction 0.01. • Heat transfer coefficients based on area and volume of two-phase region are obtained. Gas-liquid two-phase jet condensation has a property of high heat and mass transfer efficiency, thereby its theory and method becoming an urgent requirement for optimization design and safe operation of various industrial processes. Based on the experimental study of steam jet condensation in subcooled water flow in a vertical pipe, we have developed a numerical simulation method of steam-water two-phase jet condensation coupled with thermal phase change model and two-fluid model. Meanwhile, we emphasize on the shape of the steam plume, the distribution of pressure and velocity, and the heat and mass transfer of the two-phase interface. As the steam mass flux increases from subsonic to sonic, the steam plume becomes longer, and its shape transforms from cone to cylinder-cone gradually. The steam volume fraction is close to 0.01 at the end of the two-phase region, where the total pressure in the centerline approaches the total pressure of the water and reaches the maximum. The mass transfer process of steam condensed into liquid mainly occurs in the gas–liquid two-phase region, accompanied by drastic parameter change in pressure and velocity. Under the working conditions of this paper, the heat transfer coefficients based on the interfacial area of the steam plume and the volume of the two-phase region range from 1.71 MW/m 2 K to 3.51 MW/m 2 K, and from 2398.80 MW/m 3 K to 5040.07 MW/m 3 K, respectively.

Numerical study on dominant oscillation frequency of unstable steam jet under rolling condition

Steam direct contact condensation has been widely applied in many fields because of its high heat and mass transfer efficiency. However, this process may cause damage to related devices due to its pressure oscillation, especially under ocean condition. The axial and radial components of the additional force and buoyancy force were analyzed in this numerical study. Results indicated that the Coriolis force played a more important role than other forces. The effects of rolling period and rolling angle on the dominant oscillation frequency were investigated. Under rolling condition, as the rolling period decreased and the rolling angle increased, the dominant oscillation frequency of steam submerged jet increased because of the enhanced Coriolis force, which promoted the necking of the bubble. Moreover, a correlation was proposed to predict the dominant oscillation frequency of steam submerged jet under rolling condition. The maximum deviation was less than ± 9.5%.

Interfacial characteristics of steam jet condensation in subcooled water pipe flow – An experimental and numerical study

Subsonic and sonic steam jet condensation in subcooled water pipe flow is investigated experimentally and numerically. Steam plumes are captured using a high-speed camera, and thermal hydraulic parameters and heat and mass transfer are revealed by a two-fluid model coupled with a phase change model. As the Reynolds number of water increases, the steam plumes show a conical shape and gradually shorten in length. The steam dynamic pressure suddenly drops at the nozzle outlet, and the water dynamic pressure rises sharply to the maximum at the end of the two-phase region where the steam volume fraction is 0.001. Starting from the single-phase region, the pressure, velocity and temperature of the jet are self-similar. The heat and mass transfer mainly occur in the two-phase region with steam volume fractions between 0.01 and 0.99, and the mass transfer reaches the maximum at the phase interface with the steam volume fraction of 0.60.

Design and Development of Innovative Steam Injection for High-Temperature Short-Time Liquid Foods

Jet impingement has been effective in reducing the process time and improvement of product quality in various industrial applications, such as textile and paper drying, electronic cooling, glass quenching and food processing. The current work applied innovative steam injection to liquid food continuous sterilization. The multiple impingement jets of steam and product came together in the impingement tank. The effects were investigated on the Reynolds number, steam temperature and jet-to-target spacing (H/d), sterilization temperature and heat transfer efficiency in water and pineapple juice tests. The Reynolds number was based on the nozzle configuration and liquid flow rate. The study investigated product injection plates formed using two, three or four circular holes (diameter 2 mm), steam injection plates with six, nine or twenty circular holes (diameter 1 mm), steam temperatures of 120, 125 or 130 °C and H/d values of 1, 3, 5 or 7. The different options were tested with water to determine the optimal conditions, and then tested with pineapple juice. The results showed that the optimal conditions from water testing that provided the highest heat transfer efficiency occurred with two jet nozzles, six steam injection plates, a steam temperature of 120 °C and an H/d value of 1.