Steam Condensation Research Articles

Experimental study on direct contact condensation of saturated steam at low mass flux in subcooled quiescent water

Abstract The phenomenon of saturated steam jet injection in subcooled quiescent water has many practical applications including in heat exchangers, steam jet pumps, steam dumping systems in nuclear plants, etc. The experimental setup is designed and fabricated indigenously to investigate this phenomenon at lower mass fluxes ∼120 and 150 kg/m2 s. The steam jet of conical shape has been observed for all the test conditions. The recorded axial temperature distribution showed that near the nozzle region, the temperature is governed by the saturated condition of steam while the later region is dependent on the water pool temperature. The maximum temperature is observed to be at the center of the jet. It has been found that the dimensionless penetration length of the steam jet in water is directly dependent on both the temperature of the water pool and the mass flux of steam. The dimensionless jet length has been found in the range ∼1.54–2.02 and 2.07–2.19 for mass fluxes ∼120 and 150 kg/m2 s, respectively. The average heat transfer coefficient has been found in the range ∼1.97–2.37 MW/m2 K.

A Multiscale Porous 3D‐Fabric Evaporator with Vertically Aligned Yarns Enables Ultra‐Efficient and Continuous Water Desalination

AbstractSolar steam generation has emerged as an environment‐friendly and promising strategy to overcome the freshwater and energy crisis. However, simultaneously attaining the satisfied evaporation rate, durability and energy utilization in a single system is challengeable, but crucial to the practical application. Herein, inspired by the carpet weaving technique and benefiting from “fiber–yarn–fabric” hierarchical structures, a 3D fabric evaporator with vertical hemp‐yarn arrays is innovatively constructed, featuring a combined structure of multiscale pores from tunable spacing between adjacent fibers or yarns, the vertically aligned architecture coated with superhydrophilic MXene‐sandwiched layer and the adjustable side height/areas. These structures work cooperatively, surprisingly achieving the integrated functions of excellent light capture, the balanced evaporation area and vapor escape space, the additional energy adsorption from the environment and the salt exchange along or between micro/macro pores. Consequently, the 3D evaporator exhibits an outstanding evaporation rate (3.95 kg m−2 h−1 under one‐sun illumination) and extremely high outdoor evaporation (47.04 kg m−2 for 8 h), accompanied with outstanding salt‐resistance (continuous 120 h in 14% brine without salt accumulation), anti‐oilfouling and anti‐bacterial (efficiency over 99.9%) performances. Finally, through rationally assembling multi‐function modules with a condenser, an all‐in‐one “desalination–thermoelectricity–irrigation” platform is built, realizing the maximum utilization of steam condensation enthalpy.

Improvement of diffusion layer model for steam condensation in the presence of non-condensable gas under turbulent free convection

Steam condensation plays a crucial role in predicting the pressure behavior and hydrogen distribution in nuclear power plant containment during a postulated loss-of-coolant accident or a severe accident. The stagnant film model and diffusion layer model are two commonly used heat and transfer analogy models for predicting film-wise condensation in the presence of non-condensable gas on a vertical wall in the nuclear engineering field. This study proposed a general formula for the equivalent condensation thermal conductivity, which can be used to convert between the traditional diffusion layer model and the stagnant film model. An improved diffusion layer model is established, which can be used to analyze steam condensation in the presence of non-condensable gas on a vertical flat surface or outer surface of condenser tubes under turbulent free convection. The density difference of water vapor at the bulk and at the gas–liquid interface is the driving force for steam condensation in the improved model, the traditional diffusion layer model’s assumption, e.g., diffusion layer thickness, constant gas mixture density, and the application of modified Clausius-Clapeyron equation, are no longer used. The newly established model also divides the condensation process into liquid film heat transfer, latent heat transfer, and sensible heat transfer. The three parts of heat transfer processes are linked together by the equivalent heat flux on both sides of the gas–liquid interface. The effects of gas compressibility, suction, fog formation, and liquid film waviness have been considered in this study. The influences of gas compressibility, the thermal resistance of condensate film, and sensible heat transfer on modeling steam condensation were discussed. Compared with various sources of experimental data (619 data points), more than 97% of the model predicted results are within the ±25.0% error band, and the mean absolute relative error is 10.2%, which indicates that the newly proposed model has high accuracy and widely applicable ranges.

Simulations of thermal phase changes and bacterial inactivation in a superheated steam dishwasher

The use of superheated steam in dishwashers as a means of reducing water consumption and cleaning time without the use of chemical cleaning agents has great future potential for the restaurants, hotels, and hospitals. In these sectors in particular, hygienic safety is an important concern in addition to the removal of food residues. To evaluate this potential application, the heat transfer and phase change characteristics of superheated steam associated with bacterial inactivation are investigated in an idealized three-dimensional dishwasher with a nozzle and a plate at a temperature of 180 °C and a pressure of 10 bar. Transient OpenFOAM simulations were performed using the interThermalPhaseChangeFoam solver. The k-omega shear stress transport turbulence model was used to capture the turbulent flow conditions. Bacteria inactivation was described using first-order Arrhenius kinetics. The flow pattern of the steam jet, the shape of the steam plume, the steam condensate, and the separation of the boundary layer are affected by the structure of the shock interaction, and vortices occur near the nozzle exit, around the perimeter of the plate, and on the side walls of the dishwasher. Strong steam shocks result in a temperature increase, higher steam condensation rate, and lower bacterial concentration on the plate surface. The bacteria on the plate surface are killed within a short time of 25 s, proving the effectiveness of superheated steam in dishwasher cleaning. This study provides a basis for future development and optimization of next-generation superheated steam dishwashers.

Numerical analysis of heat transfer enhancement on steam condensation in the presence of air outside the tube

Numerical analysis of heat transfer enhancement on steam condensation in the presence of air outside the tube

Enhancing the Overall Heat Transfer Coefficient through Tube Rotation of a Heat Exchanger: An Analytical Approach

Background: Flow in an annulus between two concentric cylinders or pipes is very often observed, ranging its applications in many streams, namely, in steam generators, condensers, petroleum science and engineering, and various flow devices in chemical processing industries. The objective is to prove or understand the essence of parameters like heat transfer coefficient, mass transfer coefficient, etc., depending on such flow regimes. One such piece of equipment found in industry is a heat exchanger, where heat transfer occurs from one medium to another. Objective: The present study majorly discusses increasing the heat transfer coefficient in the case of shell and tube heat exchangers with rotation of tubes and is restricted to a single tube inside a shell. Methods: The methodology section can be broadly divided into two categories. First, the theoretical solution (obtained under certain assumptions) of the flow between two concentric cylinders, which includes both the rotation case and no rotation case. And second, ANSYS Fluent simulations have been presented at a steady state for both cases. All required conditions, dimensions of the chosen geometry, and assumptions have been clearly mentioned before getting into the discussion or along the way. Moreover, this study is a kind of comparative study between the conventional method of operating and rotation of tubes inside the shell and tube heat exchangers. Results: The results were positive from both the ways – theoretical and ANSYS, that there was a certain increase in the heat transfer coefficient. The overall heat transfer coefficient increased at varying flow rates (0.25 kg/s, 0.5 kg/s, and 1 kg/s) at different speeds of rotation (100 RPM, 200 RPM, and 300 RPM). Conclusion: One of the most common equipment in industries is heat exchanger. Parameters like heat transfer coefficient can be increased by rotating tube(s) of heat exchanger. This was presented using two approaches- analytical and simulation techniques. On varying RPM from 0 to 300, heat transfer coefficient increased by 69.1% for 1 kg/s, 124.7% for 0.5 kg/s, and 172.3% for 0.25 kg/s.

Experimental study on condensation heat transfer characteristics of steam in rectangular channels rotating about a parallel axis

• Nu in rotating channel increases with Re but decreases with steam temperature. • Pressure drop in rotating channel increases with Re and steam temperature. • Propose a new heat transfer correlation for steam condensation in rotating channel. In the papermaking industry, a kind of new cylinder dryer with multiple small and rectangular channels are employed to enhance the drying efficiency of drying machine. In practical working conditions, the multi-channel cylinder dryer runs under rotating states that could affect the heat transfer characteristics of the inside two-phase flow. However, the fluid heat transfer characteristics in the multi-channel at rotating states have not been well explored. In this study, a set of rotating experimental system is established to investigate the condensation characteristics and pressure drop changes of steam in rotating rectangular channels. Firstly, the experimental apparatus and the data processing method are described in detail. Then the effects of rotation speed, mass flux and steam temperature on the heat transfer coefficients and pressure drop are studied through experiment. The results show that when Re is small, the heat transfer coefficient first increases and then decreases with the increased Re ω ; when Re is large, the heat transfer coefficient increases with the increased Re ω . Moreover, the heat transfer coefficient decreases as the steam temperature increases. In addition, the pressure drop decreases with the increased Re ω while increases with the increased Re and steam temperature. Finally, a heat transfer model of two-phase flow condensation under rotating states is developed to predict the heat transfer coefficient of steam in rotating multiple channels.

Thermodynamic Analysis of Steam Cooling Process in Marine Power Plant by Using Desuperheater

Thermodynamic (energy and exergy) analysis of steam cooling process in the marine steam propulsion plant is presented in this research. Steam cooling is performed by using Desuperheater which inject water in the superheated steam to obtain wet steam. Wet steam is used in auxiliary heaters for various heating purposes inside the marine steam propulsion system. Auxiliary heaters require wet steam due to safety reasons and for easier steam condensation after heat transfer. Analysis of steam cooling process is performed for a variety of steam system loads. Mass flow rates of cooling water and superheated steam in a properly balanced cooling process should have the same trends at different system loads - deviations from this conclusion is expected only for a notable change in any fluid temperature. Reduction in steam temperature is dependable on the superheated steam temperature (at Desuperheater inlet) because the temperature of wet steam (at Desuperheater outlet) is intended to be almost constant at all steam system loads. Energy losses of steam cooling process for all observed system loads are low and in range between 10–30 kW, while exergy losses are lower in comparison to energy losses (between 5–15 kW) for all loads except three the highest ones. At the highest system loads exergy losses strongly increase and are higher than 20 kW (up to 40 kW). The energy efficiency of a steam cooling process is very high (around 99% or higher), while exergy efficiency is slightly lower than energy efficiency (around 98% or higher) for all loads except the highest ones. At the highest steam system loads, due to a notable increase in cooling water mass flow rate and high temperature reduction, steam cooling process exergy efficiency significantly decreases, but still remains acceptably high (between 95% and 97%). Observation of both energy and exergy losses and efficiencies leads to conclusion that exergy analysis consider notable increase in mass flow rate of cooling water which thermodynamic properties (especially specific exergies) strongly differs in comparison to steam. Such element cannot be seen in the energy analysis of the same system.

A Novel Steady-State Simulation Approach for a Combined Electric and Steam System Considering Steam Condensate Loss

Steam is commonly used for heating in industrial production and transmitted through the steam network. Along with the decarbonization of energy generation and utilization, electric boiler and combined heat and power (CHP) became the alternatives for steam generation. Thus, the steam network is becoming tightly coupled with the power system, which brings new challenges in the simulation and operation of the combined electric and steam system (CESS). A novel simulation approach for CESS that can balance both the simulation accuracy and speed is proposed. Piecewise linearization of the saturated steam property is used for model simplification, which accelerates the simulation speed while ensuring the accuracy. Meanwhile, the heat loss of the steam network takes both condensate loss and heat dissipation into account, which further improves the accuracy of heat loss calculation. In view of model solving, two computation frameworks are provided for back-pressure and extraction condensing the CHP units, respectively. The accuracy and efficiency of the steam heating network model is verified through both the tree and ring steam network. In addition, a CESS case with both CHP and electric boilers is presented, and the results indicate such a system can reasonably improve the system stability and renewable energy consumption capability.

Modeling of Ventilation’s Influence on Energy Consumption in Multi-cylinder Dryer Section Part1: Theoretical Model

Ventilation system affects the water evaporation rate, energy consumption and the paper quality, which is considered as the largest optimization potential part of multi-cylinder dryer section. Energy consumption of drying system is divided into three parts: steam consumption of cylinders, steam consumption of air heaters, power consumption of blowers and exhaust fans. An energy consumption model of drying system integrating steam condensation system and ventilation system is constructed according to the control logic and process flow of the actual ventilation system, by combining the established models of each module and energy consumption indexes. It is the premise to realize the intelligent control of paper drying process. The research results perfects the mechanism of ventilation system for assisted drying, which can promote the improvement of the monitoring, and enable intelligent computing technology to play a greater role in optimizing drying operation and reducing drying energy consumption.

Recyclable vitrimer epoxy coatings for durable protection

In this research, the synthesis and application of vitrimer epoxy coatings for long-term corrosion protection of metal surfaces are described. To that end, a polyamine curing agent based on vinylogous urethanes (VUs) was developed to add repairability, recyclability and recoatability to thermosetting materials. Thin films with excellent resistance to water penetration and damage could be obtained by combining the dynamic hardener with existing epoxy resins, resulting in good barrier properties. Various formulations were investigated yielding transparent coatings with durable corrosion protection, even after being scratched, exposed to saltwater, and subjected to steam condensation. Furthermore, stress-relaxation experiments revealed sufficient material flow at 150 °C, which could be significantly slowed down below 100 °C. Optical microscopy was used to demonstrate the healing ability of the vitrimer coatings, resulting in the restoration of barrier properties after scratching. The dynamic properties of the epoxy resin were used to recoat an aluminium plate as a proof of concept, demonstrating that the thin layer could be adhered to a surface again in its cured state. As a result, the service life of epoxy coatings and protected metals could be extended while maintaining excellent mechanical properties, opening the door to a wide range of potential applications such as marine coatings and concrete bonding.

Biogas upgrading by 2-steps methanation of its CO2 – Thermodynamics analysis

A thermodynamic analysis of the methanation of CO2 within biogas sets the limits to the achievable performances, directing process and catalyst development. Practical indications of thermodynamics are elaborated. The large presence of CH4 in the biogas does not hinder the achievement of an almost complete CO2 methanation, even with CH4/CO2 = 3. The smaller the temperature, the higher the CH4 concentration in the dry biomethane, and the lower the residual H2. Results comply with some grid specification even operating at 1 bar, below 400 °C, where active commercial catalysts are available. CO in the product is never a concern, in this temperature range. There is no advantage in operating above approx. 400 °C. The H2 slip can be further reduced increasing the pressure, but the improvement is most effective with a few bars; 15 bar is already quite good. H2 in excess of the stoichiometric is not useful. The process can be completely autothermal, but adiabatic operation must be avoided. Significant improvements in biomethane purity can be achieved with two methanation steps, with steam condensation in between. Residual H2 can be reduced from 7% (single stage, 1 bar, 300 °C), to 1.8% (two stages, at 300 °C, and 1 and 15bars, respectively). Partial steam condensation allows to limit coking in the second step, without a remarkable increase of residual H2. The second step cannot be autothermal above 150 °C, but the first step provides heat in excess, at 300 °C, to support also the second step.

Influence of Jet on Aerosol Retention by Pool Scrubbing Under Multihole Injector

In severe nuclear power plant accidents, when the containment is in a serious challenging state, the gas mixture in the containment can be injected into the spent fuel pool through the multihole injector by the containment depressurization measure, to reduce the risk of containment overpressure failure and the release of radioactivity to the environment. The pool scrubbing efficiency of aerosol under the jet regime is studied on the small-scale aerosol pool scrubbing facility, focusing on the influence of mass flux, steam fraction, submergence, particle diameter, and pool initial temperature on the aerosol decontamination factor (DF). The results show that under the jet regime, the DF value is significantly greater than that in the bubble regime and the effect of jet flow on the mechanism of steam condensation and aerosol removal of the rising zone is weak under the conditions explored. DF increases with the increase of mass flux owing to the droplet interception and inertial collision aerosol removal mechanisms. Because the high pool temperature weakens the aerosol removal by steam condensation, DF decreases with the increase of initial pool temperature under the conditions explored. Based on the experimental data and the analysis of the removal mechanism under the jet regime, an empirical model of aerosol DF considering mass flux, steam fraction, pool temperature, submergence, and particle size is established and verified by the international experiments. The proposed model can be used to calculate DF in the process of containment overpressure discharge.

Advanced characterization of hydrothermal flows within recharge and discharge areas using rare earth elements, proved through a case study of two-phase reservoir geothermal field, in Southern Bandung, West Java, Indonesia

Rare earth element (REE) analysis is effective for tracing water–rock interactions and solute transport in geothermal and groundwater systems. This study aimed to clarify hydrothermal flows within recharge and discharge areas of a geothermal system. We selected a well-known high-temperature geothermal field with two-phase reservoir in Southern Bandung, West Java (Indonesia) as a case study target, and collected 31 river/spring samples and 8 well rock samples. The measured total REE series concentrations ranged widely in the water samples, i.e., rivers: 3.4–35 ppt, cold springs: 0.3–284 ppt, and hot springs: 1.4 ppt to 102 ppm. Enrichment of light REEs (LREEs) in the water samples was characterized more clearly by Post Archean Australian Shale normalization than by chondrite normalization. Speciation analysis derived the following interpretations: dissolved REEs in the river water originated from free ions or Ln3+ that are typically contained in near-surface groundwater, and the dominant components were carbonate (LnCO3+) and Ln3+ complexes in the cold springs and LnCO3+ complexation in the hot springs. Steam and gas condensation into less-oxygenated groundwater can be indicated by rich LnCO3+. Only one hot spring was interpreted as being directly connected with the reservoir by strong H2S condensation and LREE enrichment. The water of the other cold and hot springs probably underwent dilution, evaporation, and magmatic gas condensation through shallow, deep, and deep-perched aquifers, permeable zones, and a major fault within the recharge and discharge areas. REE results also suggest that the main constituents of the aquifers are carbonates and silicate minerals and hydrothermally altered lahars, andesitic lava, and pyroclastic flow deposits. REEs facilitate detailed interpretation of geochemistry facies in shallow–deep waters of a hydrothermal system. Finally, integration of the analysis results of REEs, major anions and cations, water isotopes, and strontium isotopes improved a conceptual model of groundwater flows and recharge–discharge interactions in aquifers feeding a geothermal reservoir.

Inhibitory and bactericidal activities of Lippia origanoides essential oil against Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa multidrug resistant

The objective of this study was to evaluate the antimicrobial potential of essential oil (EO) from L. origanoides against Gram-negative bacteria with multidrug resistance (MDR) phenotype and to correlate the results obtained with the genetic profile of these microorganisms. The oil was extracted from the leaves of this plant by steam dragging and condensation with Clevenger equipment, the chemical components were identified and quantified by gas chromatography coupled with mass spectrometry and gas chromatography coupled with the flame ionization detector. Twenty clinical isolates and one standard strain of each species were analyzed: E. coli, K. pneumoniae and P. aeruginosa (n=63). The antibacterial potential was evaluated by broth microdilution tests. Thymol is the prevalent component (87.37%). The EO at a concentration of 312 μg/mL was effective in inhibiting 52% of E. coli strains and about 38% of K. pneumoniae. On the other hand, for P. aeruginosa a concentration of 2,500 μg/mL was needed to obtain growth inhibition of approximately 38% of the strains. Among the resistance genes detected, the highest prevalence was blaCTX-M 1/2, however, even with the presence of these genes, an antimicrobial action of this EO was observed. Therefore, the results of this study suggest that the EO of L. origanoides presented an efficient antibacterial action with potential use in the fight against infections by MDR microorganisms.

Experimental Investigation of Coolant Side Characteristic on the Performance of Air-Cooled Condenser Structured by Horizontal Flattened Tube

The steam condensation process has been experimentally investigated in an air-cooled condenser (ACC). The ACC has been designed and built using a flattened cross-section horizontal tube. The flattened tube has an internal dimension of 102 mm x 12 mm with 4030 mm length. A range of vacuum operating conditions are applied to operate the ACC. In the experiments, parameters such as vacuum pressure, saturated temperature, wall tube temperature, rate of heat transfer, and local average steam heat transfer coefficient have been considered along the flow direction with the variation of cooling water temperature. The experimental results revealed that the steam saturated temperature and the related pressure decrease with the reduction of the cooling water temperature, and the temperatures of the upper and lower parts of the horizontal flattened tube. The results also showed that the local steam condensation heat transfer coefficient decreases along with the direction of the flow, but it there is incrementing with the decreasing of saturated steam temperature at a certain range of cooling water temperature.

CTCS(Condenser Tube Cleaning System) 튜브 스케일 제거용 스폰지 볼의 선별을 위한 Ball Sorter 개발

This study has been conducted to develop a device that automatically removes foreign bodies and tube scale deposits by evaluating the effect on a sponge ball in a condenser tube. The device was used to increase thermal efficiency and involves the condensation of steam on a heat exchanger and condenser during turbine operation in nuclear and thermal power plants. In all experimental cases, the ball sorter satisfied all target achievement evaluation indicators of the ball sorter certification test, with sorting accuracy exceeding 95%, at a speed of 500 sponge balls per 15 min, and a noise of less than 85dB.

Effect of Mucilage Pollution on Ship Cooling Systems: A Case Study

In recent years, ecological degradation has increased and drawn many environmental problems with it. One of the outcomes is the mucilage problem, which directly affects tourism, fishing, and especially the maritime sector. The recent mucilage outbreak in the Sea of Marmara has brought attention to these environmental disaster-related studies. However, there are only a few studies about mucilage’s effect on maritime transportation. In this context, the impact of mucilage on a marine vessel is examined within the scope of the study. One of the major negative effects of mucilage on a vessel is, its cooling system. Due to the mucosal formation of mucilage, it clogs the filters and reduces the cooling effect of seawater. In our paper, a case study was made, and data was obtained from a simulator. The seawater filter in front of the seawater pump was clogged by 0%, 30%, 45%, and 60% during the simulated case studies. 0% is the base condition that is not clogged by the mucilage while the other three cases are partially clogged. A comparison study was made according to the data gathered from the simulator. While the filter is clogged by 60% main engine is in slow down condition, but during 30% and 45% of cases, pumps tried to compensate cooling effect by increasing the seawater flow. However, enough cooling effects on the main engine jacket water, air cooler, lubrication oil cooler, steam condenser, and air compressor were not provided. Moreover, the reduced cooling effect increases fuel oil consumption which leads to higher CO2 emissions. These results show that mucilage not only affects fishing, and tourism but also affects the environment by increasing the fuel oil consumption of a vessel.

Out-of-sample validation of a general correlation for steam condensation in the presence of air over a vertical slender tube in turbulent free convection

In a previous work [Dehbi, 2015], a general correlation was proposed for the prediction of steam condensation rates in the presence of air over vertical flat surfaces in turbulent free convection. Because most of the heat transfer data were obtained from tube condenser tests, the Popiel [2008] correction for curvature was employed to transfer results to flat plate surfaces. Popiel’s correlation is valid for laminar flows, and hence, as shown in subsequent investigations [Dehbi, 2021], it predicts mostly lower values for the curvature correction factors if applied to turbulent flows. Hereafter, we first revisit the flat surface correlation presented in [Dehbi, 2015] and update its form based on the more accurate curvature correction given in [Dehbi, 2021]. The updated flat plate correlation, along with the curvature correction, is subsequently used to predict heat transfer rates in five experiments conducted recently on slender vertical tubes, covering tube diameters from 12 mm to 38.1 mm, steam mass fraction from 0.2 to 0.90, wall temperature subcooling from 4 K to 120 K, and pressures from 1 to 16 bars. It is demonstrated that the general correlation provides very good out-of-sample predictions of the data, with a standard deviation of 13.3 %, which is typical of experimental uncertainty.

Analysis of power plant more efficaciously and reforms by heat pipes

The thermal power plants were analysed more efficaciously through 5E analysis: energy, exergy, exergoeconomic, exergoenvironmental and endurability analysis. Analysis revealed that combustion, super-heaters, re-heaters and condenser need improvement. Various reforms like modifications of heat exchanger equipment by heat pipes and solar blending of the existing plant were discussed in this paper. These reforms resulted in the efficiency improvement from 31.09% to 38.87%, exergy efficiency improvement from 49.7% to 62%, exergoeconomic factor from 417.3 to 932, exergoenvironment index from 18% to 25.5 and endurability factor from 0.689 to 0.495. The experimental validation of heat pipes for steam condensation, which is one of the reforms, was presented in this paper.