Wet Steam Research Articles

Influence of thermophysical and thermodynamic properties of refrigerants on the energy efficiency of a refrigeration unit when the compressor operates in the wet steam region

The energy efficiency of a refrigeration unit, the compressor of which operates in the wet steam region using R134a, R600a and R717 refrigerants, is analyzed. Keywords refrigeration unit, refrigerant, wet steam, low-speed compressor, condensation dkhsadvakasov@omgtu.ru

Enhancing Plasma Torch Efficiency: Wet Steam Cooling

The efficient use of wet steam for plasma torch cooling and water plasma generation is important for reliable plasma generator design. Wet steam, due to phase transformation capability, improves heat removal at lower gas flow rates if compared to liquid water. To evaluate the wet steam cooling potential, a numerical model is proposed, incorporating governing equations (mass, momentum, energy, current, and Ampere's law) are expressed in the cylindrical coordinate system. The model is applied to investigate the wet steam cooling feasibility for the anode of a direct current plasma torch with non-transferred arc. Electric arc modeling examines anode spot location and anode surface temperature distribution for a 120 A arc current and gas flow rates of 42, 90, and 140 l/min under steady flow conditions. Analysis of spatial vapor content distribution in the refrigeration channel highlights unfavorable conditions when wet steam becomes dry.

Non-equilibrium condensation flow characteristics of wet steam considering condensation shock effect in the steam turbine

Non-equilibrium condensation flow characteristics of wet steam considering condensation shock effect in the steam turbine

Numerical investigation of spindle position effects on steam ejector performance with a nonequilibrium condensation model

AbstractThis research studied the performance of a spindle‐controlled steam ejector using models such as ideal gas and wet steam under various operating conditions based on computational fluid dynamics (CFD). A wet steam model incorporating nonequilibrium condensation was employed to simulate the complex flow phenomena within the ejector. The structure of the flow, entrainment ratio (Er), and shock wave characteristics of the steam ejector were examined in two different models. Results indicate that the spindle position has a substantial impact on steam ejector performance. For the ideal gas and wet steam models, the optimal spindle position (SP‐5) at a .1 MPa motive pressure achieves the highest entrainment ratios (Er) of 1.01 and 1.042, respectively. However, an ejector with a fixed geometry achieves Er values of only .517 and .549 for the ideal gas and wet steam models, under identical working conditions. This represents a substantial improvement of 89.8% over the fixed‐geometry ejector. The wet steam model consistently predicts 2%–4% higher Er values compared with the ideal gas model across all spindle positions. The study also reveals that increasing the motive pressure from .1 to .3 MPa reduces Er by up to 45.8% at the optimal spindle position, with the shock train length extending to 35% of the mixing chamber at .3 MPa. These findings offer insights for improving the design and optimization of variable‐geometry steam ejectors, potentially increasing efficiency in industrial applications.

Utilizing a pressure-based CFD solver for modelling wet steam flow in low-pressure turbine stages: a predictive approach to assessing flow losses

Utilizing a pressure-based CFD solver for modelling wet steam flow in low-pressure turbine stages: a predictive approach to assessing flow losses

Energetic, exergetic, and exergoeconomic analyses of beer wort production processes

Energy efficiency strategies in industrial breweries examine the inefficiency of thermal systems from a thermodynamic perspective. However, understanding the costs of inefficiencies in systems, including non-thermodynamic costs, requires exergoeconomics. This study examined wort production in a standard Tier-1 brewery from the tripod of energy, exergy, and exergoeconomics analyses to assess the performance of brewing sections and to pinpoint components that contributed the most to exergy destruction and product cost rate. The energy analyses for the production system showed that the total specific energy for processing 10.05 tons of brew grains to 346.98 hL high-gravity wort was (86 ± 1) MJ/hL at an operational energy efficiency of 30.35%. The exergetic analyses showed that the cumulative exergetic destruction was 3.2737 MW, with the brewhouse section contributing 89.25% of the system’s inefficiencies. Also, the analyses showed that the wort kettle (42.7911%), mash tun (10.8086%), preheater (10.0683%), whirlpool (8.3522%), and adjunct kettle (6.2705%) are the top five components with the highest rates of cumulative exergy destruction. The exergoeconomic analyses revealed that the cost rate of processing chilled wort was estimated to be 0.0681 USD/s per overall exergetic efficiency of 6.61%. The five most significant components are the wort kettle (53.70%), whirlpool (16.42%), mash filter (10.44%), mash tun (6.875%), and adjunct kettle (3.31%) based on the relative total cost increases for the production processes. Additionally, wet steam throttling resulted in a 2.51% increase in exergetic efficiency, a 1.60% drop in exergetic destruction rate, and a decrease in cost rates to 0.0675 USD/s.

Enhancing shipboard waste heat management with advanced technologies

Enhancing shipboard waste heat management with advanced technologies

Investigation on Water Erosion Behavior of Ti-based Metal Matrix Composite: Experimental Approach

Wet steam flow produces big water droplets in the low-pressure zone of a steam turbine blade. These droplets clash with subsequent blades, resulting in a strong impact that is evident as erosion. Titanium and its alloys are valuable for technical applications such as turbine blades because of their low density, high strength, and exceptional corrosion resistance. The boron carbide(B4C) has a high hardness but a low strength; therefore, it's exciting to investigate water erosion of Ti/ B4C and SiC combination. The effect of 1 wt% B4C and 1, 3, 5, and 7 wt% SiC particles on water droplet erosion of Ti composite was studied using the SPS method for 5 minutes at 1200 oC temperature and 50 MPa pressure. The L9 orthogonal array with four levels of parameters of the Taguchi method is used to conduct the experiments. By measuring the weight of the specimen at interval time, the erosion behavior with time is obtained with different nozzle diameters. The effect of material and experimental parameters on erosion resistance is studied, and an empirical relation is developed.

Condensation mechanism and pressure fluctuation of a steam centrifugal compressor based on a non-equilibrium condensation model

In this paper, the condensation mechanism and pressure fluctuation of a steam centrifugal compressor are deeply studied based on a non-equilibrium condensation model. The wet steam model is generated to predict the flow characteristics and the condensation of the steam centrifugal compressor. The effect of different inlet temperatures on the steam condensation characteristics is deeply explored. Numerical results show that the steam condensation phenomenon on the high span surface is increasingly obvious, and the mass fraction of liquid steam first increases and then decreases with the increase in temperature. The droplet particle diameter and the droplet number gradually increase with the increase in temperature. It is also found that the blade loading on the impeller blade also becomes more unstable with the increase in inlet temperature. The amplitude spectrum of pressure fluctuation on the both sides of impeller blade and diffuser blade is analyzed through the fast Fourier transform. The pressure fluctuation in the flow channel becomes severe first and then becomes stable with the increase in temperature, which is well consistent with the variation trend of liquid mass fraction. The quantitative relationship between condensation strength and operating temperature is established to explore the variation trend essence of surface-average wetness fraction of different span surfaces at different inlet temperatures, which further reveals the condensation sensitivity to temperature at different blade heights. It is further found that the condensation strength on the low span surface and the average wetness fraction of steam condensation in the flow field increasingly decrease with the increase in inlet temperature.

Thermodynamics to economic analyses of geothermal-driven hydrogen energy systems

Thermodynamics to economic analyses of geothermal-driven hydrogen energy systems

CFD simulation of the influence of swirl intensity on entropy production for wet steam flow in supersonic dehydration

CFD simulation of the influence of swirl intensity on entropy production for wet steam flow in supersonic dehydration

Numerical investigation of discharge pressure effect on steam ejector performance in renewable refrigeration cycle by considering wet steam model and dry gas model

Abstract In recent times, steam ejectors have garnered significant interest among researchers due to their environmental friendliness and the utilization of low-grade energy sources. However, a key drawback of the ejector refrigeration cycle (ERC) is its relatively low coefficient of performance (COP). Understanding the behavior of ejectors under various operating conditions is crucial for addressing this concern. This study specifically focuses on investigating the flow characteristics of ejectors in the single-choking mode. Both dry steam model (DSM) and wet steam model (WSM) are employed to analyze and evaluate the performance in this study. Based on the findings, it is evident that the discharge pressure (DP) significantly influences the flow characteristics. With increasing DP, there is a decrease in the Mach number and liquid mass fraction (LMF) within the ejector, while the temperature distribution shows an upward trend. Additionally, as the DP increases, there is a notable decline in the entrainment ratio (ER) and production entropy. With an increase in the DP, both the DSM and WSM exhibit similar trends. However, in the DSM, the ER reaches zero at an earlier stage compared to the WSM. Specifically, when the DP rises from 5000 Pa to 5600 Pa, there is a 12.6 % increase in the production entropy in the WSM, while the DSM experiences a slightly higher increase of 12.9 %.

Determining the Idle Mode of the Last Stages of Powerful Steam Turbines for Wet Steam Area

Determining the Idle Mode of the Last Stages of Powerful Steam Turbines for Wet Steam Area

CFD approach for determining the losses in two-phase flows through the last stage of condensing steam turbine

CFD approach for determining the losses in two-phase flows through the last stage of condensing steam turbine

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.

Development of a new expression for predicting wet steam loss coefficient in steam turbines based on CFD and symbolic regression

Development of a new expression for predicting wet steam loss coefficient in steam turbines based on CFD and symbolic regression

Numerical study of the impact of hot steam injection in the condensation flow through the low-pressure stage of steam turbine

Numerical study of the impact of hot steam injection in the condensation flow through the low-pressure stage of steam turbine

Advancing Thermophilic Anaerobic Digestion of Corn Whole Stillage: Lignocellulose Decomposition and Microbial Community Characterization

Converting corn grains into bioethanol is an expanding practice for sustainable fuel production, but this is accompanied by the production of large quantities of by-products such as whole stillage. In the present study, the influence of advanced wet oxidation and steam explosion (AWOEx) pretreatment on biogas production and lignocellulose decomposition of corn whole stillage (CWS) was evaluated using semi-continuous thermophilic reactors. The digestion of the CWS was shown to be feasible with an organic loading rate (OLR) of 1.12 ± 0.03 kg VS/m3 day and a hydraulic retention time (HRT) of 30 days, achieving a methane yield of 0.75 ± 0.05 L CH4/g VSfed for untreated stillage and 0.86 ± 0.04 L CH4/g VSfed for pretreated stillage, corresponding with an increase in methane yield of about 15%. However, the reactors showed unstable performance with the highest investigated OLRs and shortest HRTs. Under optimal conditions, the conversion efficiencies of COD, cellulose, hemicellulose, and lignin were 88, 95, 97, and 59% for pretreated CWS, and 86, 94, 95, and 51% for untreated CWS, respectively. Microbial community analysis showed that Proteiniphilum, MBA03, and Acetomicrobium were the dominant genera in the digestate and were likely responsible for the conversion of proteins and volatile fatty acids in CWS.

Wet steam method for reducing attached cells of Salmonella and Listeria monocytogenes on Hass avocado

Wet steam method for reducing attached cells of Salmonella and Listeria monocytogenes on Hass avocado

Binary Vapor Cycle for Waste Heat Recovery from Marine Engine Exhaust

Abstract The considerable energy waste in maritime transport and the need to obtain alternatives to reduce emissions of polluting gases are factors that have motivated the study of waste heat recovery systems for marine engines. The system studied herein relies on a binary vapor cycle that uses water for the topping cycle while three organic fluids were investigated for the bottoming cycle: R601a, R134a, and R22. Each of these belongs to a different category of fluid, namely, dry fluid, isentropic fluid, and wet fluid, respectively. Two engines of different ratings and two different pressures of the heat recovery steam generator have been considered for each engine. Various outlet pressures for the topping turbine, which is the most liable to erosion and corrosion due to wet steam, have been investigated. The maximum efficiency achieved for the waste heat recovery system peaked at 21% while the maximum electric power accounted for 4.2% of engine brake power. Therefore, the employment of a waste heat recovery system based on a binary cycle seems a promising alternative to harnessing heat from the exhaust gases of marine engines.