Outlet Of Chamber Research Articles

Thermodynamic modeling and comparative analysis of a compressed air energy storage system boosted with thermoelectric unit

Current study represents the thermodynamic modeling and exergy analysis of a compressed air energy storage system boosted with thermoelectric generator (CAES/TEG). To evaluate the studied system, a comparative analysis between compressed air energy storage system (CAES) with CAES/TEG has been done. Exergy, a powerful tool for analyzing energy conversion systems, is employed to determine the exergy destruction rate and exergy efficiency of the system as well as different related components. The results of exergy analysis indicates that the wind turbine with 35.28 kW (44.81% of total exergy destruction rate) has the highest exergy destruction rate and after that in the second and third places are combustion chamber and cavern. Findings indicate that with adding thermoelectric modules to the CAES system, the output power of Rankine cycle and organic Rankine cycle increase about 1.16 kW and 0.959 kW in comparison with CAES system, which these changes lead to increasing the net output power of the system in CAES/TEG system from 33.59 kW to 35.71 kW compare with CAES. Moreover, the influences of main parameters such as compressor mass flow rate, compressor pressure ratio, and combustion chamber outlet temperature and wind speed on the CAES/TEG performance are investigated.

Assessment on the supersonic combustor performance induced by the asymmetric struts with hydrogen fuel

Enhancing the combustion efficiency of gas fuel, i.e., hydrogen, in supersonic reacting flows has attracted wide attention around the world, besides, the flame holders are the key components of scramjet engines which even can make the injected fuel and local air mix and burn better in milliseconds. In previous researches, two struts with backward facing-steps have been proved to be a superior flame holder, also, some parameters of the two struts have been studied in detail. In this work, an in-house code was developed to compute the Reynolds-averaged Navier-Stokes (RANS) equations coupled with the SST k−ω turbulence model and the one-step reaction finite-rate/eddy-dissipation model, next, the effects of the horizontal staggered distances of the two struts have been investigated computationally including with/without chemical reactions. The results indicate that the structure of the flow field behaves comparably, also, the distributions of the mixing efficiencies, including mixing length, show little differences for all the cases with distinct staggered (horizontal) distances, i.e., the cases of upper and lower struts staggered, in the cold flows. However, there are considerable discrepancies for the total pressure losses, and the symmetric struts case is the minimal one. In the reactive flows, the flow field including the section in the vicinity of the fuel injectors, combustion efficiency and total pressure loss vary obviously for the cases lower strut staggered, here, the case of the staggered distance, which equals 2 mm, has the greatest combustion efficiency at the outlet of the combustion chamber. Whereas the total pressure loss at the outlet of the combustor for the symmetric struts case, which's staggered distance equals 0, is minimal. Next, the flow field and total pressure loss for the cases of upper strut staggered show considerable discrepancies, also, the symmetric case has the lowest total pressure loss. Whilst the combustion efficiency behaves comparably, except in the vicinity of the injection position. Note that, the asymmetric struts benefit the combustion of the fuels with extra pressure loss cost. For high combustion efficiency with the total pressure loss acceptable, the case sd-l = 2 mm is the optimal scheme.

Two-phase flow-based numerical investigation of the temperature maps of sodium-cooled exhaust valves in a turbocharged engine

Valves at the outlet of the combustion chamber in modern combustion engines must withstand very high temperature and acceleration. Such valves are subject to thermal loading to have to tolerate the limit of material temperature. The present study constitutes a contribution to predict the temperature maps of the sodium-cooled exhaust valves considering the real conditions of an engine operation. An adequate subdivision of the valve is used to better assess the effect of each part of the cylinder head. Therefore, the instantaneous heat transfer coefficient and adiabatic wall temperature for each subdivision are evaluated. To survey the two-phase flow phenomenon, the valve motion was modeled by a dynamic mesh method, and the sodium sloshing was modeled by the volume of fluid multiphase model. The average values of these parameters are calculated and introduced as boundary conditions in a finite element model implemented in the commercial code ANSYS to extract the temperature map. The results indicated that the maximum temperature errors between the simulated and the test results were 45.5 °C and 37.2 °C in the axial and radial directions of the valve, respectively, and their maximum relative errors were not more than 8%. As an application, this methodology is used to highlight the temperature maps and to show the region of extreme temperature in the aim of avoiding any damage.

ПОВЫШЕНИЕ ТОЧНОСТИ РАСЧЕТА ПОЛЯ ТЕМПЕРАТУР ГАЗА НА ВЫХОДЕ ИЗ КАМЕРЫ СГОРАНИЯ ГТД МЕТОДОМ ТРЕХМЕРНОГО КОМПЬЮТЕРНОГО МОДЕЛИРОВАНИЯ

The problem of numerical simulation of the gas flow with the combustion of atomized liquid fuel was solved (the equilibrium combustion model pdf was used along with the partially mixed mixture model) in the annular combustion chamber of a gas turbine engine. Numerical modeling was performed in Ansys Fluent calculation complex. The purpose of the calculations was to simulate the radial and circumferential unevenness of the gas temperature pattern at the outlet of the combustion chamber. As a result of the calculations, it was found that the accuracy of modeling the radial and circumferential unevenness of the gas temperature pattern at the outlet of the combustion chamber is unsatisfactory when using the k–e turbulence model with the initial settings for the Ansys Fluent calculation complex. Moreover, the maximum value of the radial non-uniformity of the gas temperature pattern at the outlet of the combustion chamber exceeded the value obtained in the experiment by 12.61 %, and the maximum value of the circumferential non-uniformity by 12.69 %. To improve the accuracy of modeling the temperature pattern non-uniformity at the outlet of the combustion chamber, a numerical experiment was conducted to study the effect of the degree of turbulent diffusion of gas components on the value of temperature pattern non-uniformity. To reduce the non-uniformity of the temperature pattern at the outlet of the combustion chamber, the degree of turbulent diffusion of gas components was increased with respect to the initial version of the calculation, performed using the k–e model of turbulence with the initial settings for the Ansys Fluent calculation complex, by reducing the turbulent Schmidt number Sc in the turbulence model. For the initial settings of the k–e turbulence model in the Ansys Fluent calculation complex, the turbulent Schmidt number Sc = 0.85. A numerical experiment was performed for the values of Sc = 0.6, Sc = 0.4, and Sc = 0.2. The results of a numerical experiment confirmed the influence of the turbulent Schmidt number Sc on the result of calculating the gas temperature pattern at the outlet of the combustion chamber; as the value of Sc decreases, the level of the circumferential and radial non-uniformities of the gas temperature pattern decreases. However, the degree of reduction of radial and circumferential irregularities with a decrease in Sc is different. Therefore, to ensure high accuracy in calculating both the circumferential and radial non-uniformities of the gas temperature pattern, it was proposed to use a variable value of the turbulent Schmidt number Sc depending on the gas temperature instead of a constant value. The functional dependence of the turbulent Schmidt number Sc on the gas temperature was implemented in the Ansys Fluent calculation complex using the user function (UDF). The results of modeling the gas temperature pattern using the proposed UDF function for the turbulent Schmidt number Sc are in satisfactory agreement with the experimental data for both radial and circumferential non-uniformities of the gas temperature pattern at the outlet of the combustion chamber.

Method to simulate distal flow resistance in coronary arteries in 3D printed patient specific coronary models

BackgroundThree-dimensional printing (3DP) offers a unique opportunity to build flexible vascular patient-specific coronary models for device testing, treatment planning, and physiological simulations. By optimizing the 3DP design to replicate the geometrical and mechanical properties of healthy and diseased arteries, we may improve the relevance of using such models to simulate the hemodynamics of coronary disease. We developed a method to build 3DP patient specific coronary phantoms, which maintain a significant part of the coronary tree, while preserving geometrical accuracy of the atherosclerotic plaques and allows for an adjustable hydraulic resistance.MethodsCoronary computed tomography angiography (CCTA) data was used within Vitrea (Vital Images, Minnetonka, MN) cardiac analysis application for automatic segmentation of the aortic root, Left Anterior Descending (LAD), Left Circumflex (LCX), Right Coronary Artery (RCA), and calcifications. Stereolithographic (STL) files of the vasculature and calcium were imported into Autodesk Meshmixer for 3D model optimization. A base with three chambers was built and interfaced with the phantom to allow fluid collection and independent distal resistance adjustment of the RCA, LAD and LCX and branching arteries. For the 3DP we used Agilus for the arterial wall, VeroClear for the base and a Vero blend for the calcifications, respectively. Each chamber outlet allowed interface with catheters of varying lengths and diameters for simulation of hydraulic resistance of both normal and hyperemic coronary flow conditions. To demonstrate the manufacturing approach appropriateness, models were tested in flow experiments.ResultsModels were used successfully in flow experiments to simulate normal and hyperemic flow conditions. The inherent mean resistance of the chamber for the LAD, LCX, and RCA, were 1671, 1820, and 591 (dynes ∙ sec/ cm5), respectively. This was negligible when compared with estimates in humans, with the chamber resistance equating to 0.65–5.86%, 1.23–6.86%, and 0.05–1.67% of the coronary resistance for the LAD, LCX, and RCA, respectively at varying flow rates and activity states. Therefore, the chamber served as a means to simulate the compliance of the distal coronary trees and to allow facile coupling with a set of known resistance catheters to simulate various physical activity levels.ConclusionsWe have developed a method to create complex 3D printed patient specific coronary models derived from CCTA, which allow adjustable distal capillary bed resistances. This manufacturing approach permits comprehensive coronary model development which may be used for physiologically relevant flow simulations.

Numerical Simulation of Vapor Deposition Process of Perovskite Solar Cells: The Influence of Methylammonium Iodide Vapor Flow to Perovskite Growth

Abstract This paper presents a two-dimensional (2D) transient numerical model for simulating the vapor deposition process for growing perovskite films. The diffusion process of methylammonium iodide (MAI) vapor through the processing chamber to react with the lead iodide (PbI2) substrate and grow the perovskite layer is analyzed with a diffusion coefficient that has been determined by measuring thicknesses of perovskite layers grown in a chemical vapor deposition (CVD) chamber. Innovations applied to the CVD chamber to improve the uniformity of layer thickness and offer control over the growth process are applied and computationally assessed. One is the addition of screens at various strategic locations in the chamber to improve flow uniformity. Another is changing the locations of MAI sublimation bowls and chamber outlet numbers and locations. The results show that adding screens makes the MAI vapor flow more uniform in the plenum while allowing a quicker purge of the N2 inert gas. This leads to a higher and more uniform growth rate of perovskite. The MAI vapor flow is influenced by the reaction plenum geometry, so the chamber is expected to allow good control of the process to achieve uniform surface deposition rate and controlled grain growth of the perovskite layer.

Performance Improvement of Swirl Type Micro Bubble Generator

Micro bubbles measuring tens of micrometers or less in diameter have recently been paid much attention. Swirl type, pressurizing dissolution, and perforated plate methods have been proposed for micro bubble generation. The swirl type method can generate micro bubbles even under low-pressure power in a simple structure. This study examined the effect of the swirl chamber inlet diameter on the bubble diameter in a swirl type micro bubble generator. The swirl chamber inlet diameter was varied in the range of 15-90 mm and the effect was examined. In order to clarify the effect of enlarged inlet diameter, the micro bubbles diameter was measured under changing water supply pressure and air flow rate, the behavior of air column in the swirl chamber was visualized, and the velocity distribution around outlet of swirl chamber was measured. As a result, when the swirl chamber inlet diameter was enlarged, the outflow form changed from an axial outflow to a radial outflow. The average bubble diameter could also be reduced. An average bubble diameter of 28 μm could be realized under the conditions of swirl inlet diameter of 90 mm and water supply pressure of 0.1 MPa gage.

Thermodynamic analysis and optimization of an oxy-combustion combined cycle power plant based on a membrane reactor equipped with a high-temperature ion transport membrane ITM

This paper presents an advanced zero emission power plant (AZEP) which is a combined cycle power plant with a membrane reactor equipped with a high-temperature ion transport membrane (ITM). The membrane reactor, which is used as a replacement for a combustor in the gas turbine, combines three functions: combustion of fuel, oxygen separation from the air in the ITM, and heating of the oxygen-depleted air. Due to the membrane reactor, the AZEP does not need an energy-consuming external air separation unit, which is a significant advantage over other types of power plants which utilize oxy-combustion technology. The presented thermodynamic model for AZEP with an advanced numeric model of the ITM allows the user to perform thermodynamic analyses for a wide range of AZEP operating parameters and to select their optimal values, without the need to determine the geometric parameters of the ITM and heat exchangers. The obtained results allow one to indicate the basic features of this carbon capture technology. The selection of AZEP operating parameters is related to the balance between the power plant’s efficiency maximization and the limitation of the ITM and heat exchangers surface areas. This manuscript also presents an analysis of the possible AZEP plant development. The development model of the E-AZEP plant assumes a number of improvements in the parameters of the ITM and the entire membrane reactor, with respect to the AZEP plant basic model. The ITM assumes an improvement in the ionic conductivity (σion) by approx. 45%, by changing the value of the conductivity coefficient (C2) as well as increasing the maximum operating temperature of the membrane from 900 °C to 1000 °C. The work demonstrated the great influence of the membrane surface. In the model of the membrane reactor, a higher flue gas temperature was assumed at the combustion chamber outlet, equal to t1g = 1600 °C, which together with the assumption of temperature approximation ΔThe.HHX = 20 K gives an air temperature t3a = 1580 °C. With the current technological possibilities, AZEP plants are competitive compared to alternative solutions, but they do not have a significant advantage over them. However, overcoming the presented limitations may allow us to achieve an advantage in terms of achieved efficiency compared to alternative CO2 capture technologies. Achieving the air temperature at the inlet to the expander, at a level close to the temperatures used in J-class gas turbines (E-AZEP plant case), allows for a decrease in the efficiency when compared to modern combined cycle power plants, at a level of 3% points.

The Impact of Operating Conditions on the Performance of a CH4 Dry Reforming Membrane Reactor for H2 Production

Biogas is a promising resource for the production of H2 since it liberates energy by recycling waste, along with the reduction of CO2. In this paper, the biogas dry reforming membrane reactor is proposed to produce H2 for use in fuel cells. Pd/Cu alloy membrane is used to enhance the performance of the biogas dry reforming reactor. This study aims at understanding the effect of operating parameters such as feed ratio of sweep gas, pressure in the reactor, and reaction temperature on the performance of the biogas dry reforming membrane reactor. The effect of the molar ratio of the supplied CH2:CO2, feed ratio of the sweep gas, and the valve located at the outlet of the reaction chamber on the performance of biogas dry reforming are investigated. Besides, the thermal efficiency of the proposed reactor is also evaluated. The results show that the concentration of H2 in the closed valve condition is higher than that of the open valve, and the optimum feed ratio of the sweep gas to produce H2 is 1, irrespective of the molar ratio of supplied CH2:CO2. Also, H2 selectivity and CO selectivity increases and decreases respectively when the reaction temperature increases, irrespective of the molar ratio of supplied CH2:CO2. Therefore, the thermal efficiency of the closed valve is higher than that of the opened valve. Also, the thermal efficiency is the maximum when the feed ratio of the sweep gas is 1 due to high H2 production performance.

Key factors in the volatile organic compounds treatment by regenerative thermal oxidizer

ABSTRACT The regenerative thermal oxidizer (RTO) is widely used in the treatment of volatile organic compounds (VOCs). The RTO with three packed beds has a backflushing process, which makes its operation quite different from common regenerative combustion devices with two beds. However, the published research regarding this kind of RTO was far from sufficient. Thus, models based on an industrial RTO with three beds were developed. Temperature distributions for the RTO were simulated based on the standard k-ε model, heat balance model, DO model, and finite chemical-rate/eddy-dissipation model after model validation. Four operating parameters were selected, and these parameters have a significant impact on key factors, such as the oxidation chamber temperature (OCT), outlet temperature, and thermal efficiency. Multi-factor analysis was performed by orthogonal experiment and regression analysis of the key factors, revealing that different parameters imposed various impacts on the key factors. A linear relationship between the OCT and RTO outlet temperature was identified, yielding a useful formula for engineering applications. Implications: A regenerative thermal oxidizer (RTO) used in volatile organic compounds (VOCs) treatment was studied between engineering and simulation. The simulation results showed a few error compared to the engineering ones. Single parameter simulations, orthogonal experiments and regression analysis were applied to study key factors such as oxidation chamber temperature, outlet temperature, and thermal efficiency. The influence and regularity of the four main operating parameters on the key factors were quite different. The best condition for this RTO was got. The linear formula of the oxidation chamber temperature and the outlet temperature are obtained, respectively.

Fluidic Oscillators, the Effect of Some Design Modifications

The number of applications where fluidic oscillators are expected to be used in the future, is raising sharply, then their ability of interacting with the boundary layer to modify forces on bluff bodies, enhancing heat transfer or decreasing noise generation, are just few of the applications where fluidic oscillators can be used. For each application a particular pulsating frequency and amplitude are required to minimize/maximize the variable under study, force, Nusselt number, etc. For a given range of Reynolds numbers, fluidic oscillators present a linear relationship between the output frequency and the incoming fluid flow, yet it appears the modification of the internal fluidic oscillator geometry may affect this relation. In the present paper and for a given fluidic oscillator, several performance parameters will be numerically evaluated as a function of different internal modifications via using 3D-CFD simulations. The paper is also evaluating the relation between the momentum applied to the mixing chamber incoming jet and the oscillator output characteristics. The evaluation is based on studying the output mass flow frequency and amplitude whenever several internal geometry parameters are modified. The geometry modifications considered were: the mixing chamber inlet and outlet widths, and the mixing chamber inlet and outlet wall inclination angles. The concept behind this paper is, to evaluate how much the fluidic oscillator internal dimensions affect the device main characteristics, and to analyze which parts of the oscillator produce a higher impact on the fluidic oscillator output characteristics. For the different internal modifications evaluated, special care is taken in studying the forces required to flip the jet. The entire study is performed for three different Reynolds numbers, 8711, 16034 and 32068. Among the conclusions reached it is to be highlighted that, for a given Reynolds number, modifying the internal shape affects the oscillation frequencies and amplitudes. Any oscillator internal modification generates a much relevant effect as Reynolds number increases. Under all conditions studied, it was observed the fluidic oscillator is pressure driven.

Numerical study of the effect of H2O diluents on NOx and CO formation in turbulent premixed methane-air flame

The interaction of turbulence–combustion inside the flame field is studied in a Launder-Sharma Low Reynolds Number (LS-LRN) k−ε/EDM framework, while suitable coefficients have been utilized in the code. A finite volume method (FVM) with staggered grids was applied to discrete set of governing equations. SIMPLE algorithm is applied with a fine grid resolution. The convective terms are discretized using Power Law Scheme (PLS). The system of governing equations is solved simultaneously using numerical or TDMA finite difference methods (Tri-Diagonal Matrix Algorithm). By implementation of the Zeldovich and Westbrook-Dryer mechanisms, NOx and CO concentrations were obtained, respectively. It is illustrated that the implemented LS-LRN-k−ε/EDM method with the new coefficients by shorter runtimes has very good agreement with previously published experimental measurements. Increasing the H2O diluent at the inlet leads to an increase in the temperature, which increases the NOx and CO near the entrance, but gradually towards the outlet of the combustion chamber. The energy absorbed by H2O leads to a severe decrease in temperature and subsequent reduction in the amount of NOx and CO emissions. With increasing H2O diluent, changes in temperature are not very significant, while changes in pollutants CO and especially NOx, are remarkable. With the increase of H2O diluent, the maximum amount of CO emission displaces towards the inlet of the combustion chamber. However, it should be noted that, at a specific value of H2O diluent, the length of the combustion chamber should not be less than critical value, causing the exhaust of the pollutant with large volume to the environment. After the critical point, the increase in the length of the chamber has little effect on reduction of the pollutant exhaust. However, by increasing the H2O diluent, enclosures with smaller length can be utilized.

Sensory evaluation in test chambers: Influences of direct and indirect assessment

The release of volatile organic compounds from building products may influence the perceived air quality in the indoor environment. Consequently, building products need to be assessed for the acceptability of emitted odors. The standard ISO 16000-28 describes the evaluation of perceived odor in test chambers with trained panelists, being calibrated with diluted acetone. For the direct odor assessment, ISO 16000-28 requires an air flow of 0.6–1.0 l/s at the chamber outlet. To meet these conditions under normal air exchange rates, the minimum chamber volume is about 3 m³. If smaller chambers are used, air must be collected into containers for an indirect assessment. Procedures for the handling of the containers are provided in the ISO standard. Nevertheless, the indirect assessment method has a number of pitfalls and drawbacks. Experiments with sampling-container materials such as Nalophan™ and Tedlar® and different sampling techniques (continuous vs. discontinuous) have shown that the composition of sampled air might be influenced by the container material due to sink effects and leakage. The recoveries of the target VOCs in the sampling container decreased in dependence of decreasing vapor pressure and increasing octanol/air distribution coefficient.1-butanol and 1-hexanol have high recovery rates in Nalophan™ containers. These substances therefore appeared to be suitable for investigations into the synergistic odor effect. It could be shown that mixtures of 1-butanol and 1-hexanol have no clear additive effect in the sensory evaluation. This calls into question the practical relevance of an odor guide-value concept based on individual substance evaluations.

ВЛИЯНИЕ РЕЖИМНЫХ И КОНСТРУКТИВНЫХ ПАРАМЕТРОВ НА НЕРАВНОМЕРНОСТЬ ТЕМПЕРАТУРНОГО ПОЛЯ НА ВЫХОДЕ ИЗ КАМЕРЫ СГОРАНИЯ ГАЗОТУРБИННОГО ДВИГАТЕЛЯ

Ensuring acceptable temperature field non-uniformity at the outlet of the combustion chamber is a very important requirement that determines the reliability and durability of the turbine. The formation of non-uniformity is determined by the nature of the interaction of the secondary air jets with the gas flow in the flame tube and depends on many factors, both structural and operational parameters. In this paper, we propose to evaluate the non-uniformity of the temperature fields at the outlet of the combustion chamber using a mixing coefficient that determines the quality of mixing jets of secondary air with a gas stream in the mixer. Based on the equation of turbulent diffusion during the flow of an annular jet into a limited space, an analytical dependence is obtained in the work that allows one to calculate the mixing process in the combustion chamber. The connection of the mixing process with the formation of temperature fields is established. Based on this, dependences are obtained for calculating the nonuniformity of temperature fields. Their satisfactory agreement with experimental data was shown. The found dependences allow one to analyze the influence of various parameters on the non-uniformity of temperature fields and accelerate the refinement of the combustion chamber by this parameter. The possibility of predicting the effect of various parameters on the unevenness of temperature fields is shown. The presence of the optimal value of the degree of opening of the mixer is confirmed, at which the minimum value of the unevenness of the temperature field at the outlet of the combustion chamber is achieved. Therefore, the analytical relationships found in the work allow optimizing the design of the mixer in the combustion chamber and the distribution of secondary air in it in order to reduce the unevenness of the temperature fields at the outlet of the combustion chamber.

Effects of different fuel supply types on combustion characteristics behind group of V-gutter flame holders: Experimental and numerical study

Experiments on fuel effects flame stabilization processes, NOx generation and temperature at combustion chamber outlet when using a group of three V-gutter flame holders have been reported. Fuel supply directly to the re-circulation zone on the inside of the V-gutter (type A fuel supply), and alternatively in the second type, fuel was supplied to the V-gutter symmetry axis on the outside (type B fuel supply have been carried out.

Design and Parameter Optimization of an Air-Suction Jujube Picking and Conveying Device

HighlightsThis study designed an air-suction jujube picking and conveying device to address the problems of low transport efficiency and high damage rate.Theoretical analysis, Fluent software simulation, and prototype testing determined the diameter of the conveying pipe, the inlet and outlet diameters of the suction chamber, and the fan type and speed.A Box-Behnken center combination design in Design-Expert software was used to perform response surface orthogonal tests to optimize the device.This study provides a reference for further optimization of the air-suction jujube picking and conveying device.Abstract. To address the problems of low transport efficiency and high damage rate, an air-suction jujube picking and conveying device was designed. The main components of the device include the fan, suction chamber, and conveying pipe. Simulation of the conveying pipe and suction chamber was performed using Fluent software, and the airflow rate and pressure were analyzed for conveying pipes of five different diameters and suction chambers with different inlet and outlet diameters. In the simulation results, the diameter of the conveying pipe was 105 to 165 mm, and the outlet diameter of the suction chamber was 150 to 210 mm. The Box-Behnken center combination design method in Design-Expert software was used to perform response surface orthogonal tests with the conveying pipe diameter, suction chamber outlet diameter, and fan speed as the test factors, and the jujube conveying rate and breakage rate as the target values. The results show that the order of the test factors on the jujube conveying rate is: fan speed = conveying pipe diameter > suction chamber outlet diameter, and the order of the test factors on the jujube breakage rate is: fan speed > suction chamber outlet diameter > conveying pipe diameter. The experimental results were verified in field tests with the optimized parameters. When the conveying pipe diameter was 165 mm, the suction chamber outlet diameter was 200 mm, and the fan speed was 3254 rpm, the average jujube conveying rate in the verification test was 238.68 kg h-1. The relative error between the experimental verification value and the theoretical optimized value was 1.44%, which is less than 5%. The average value of the jujube breakage rate in the verification test was 2.18%. The relative error between the experimental verification value and the theoretical optimized value was 3.81%, which is also less than 5%. This study provides a reference for subsequent research and optimization of the air-suction jujube picking and conveying device. Keywords: Air suction, Conveying device, Conveying pipe, Jujube, Suction chamber.

Flow characteristics of an axial turbine with chamber and diffuser adopted in compressed air energy storage system

Axial turbine is an important work-output device in Compressed Air Energy Storage (CAES) system. A compact chamber and a short diffuser are both adopted in the turbine to obtain higher power with lower investment. As a result, the internal flow field is also influenced significantly. In present study, internal flow characteristic of an axial turbine adopted in a new 10MW CAES system is analyzed with compact chamber and short diffuser by three-dimensional steady numerical method. The results illustrate that the isentropic efficiency obtained by the numerical method agrees well with the experiment. Analysis of aerodynamic performance indicates that maximum entropy increase is found in rotor, and the flow loss in stator also cannot be neglected. Back flow with lower velocity, higher static pressure and entropy is observed near bottom of the chamber, and non-uniform distribution of total pressure is thus formed at outlet of chamber. As a result, obvious variation of inlet attack angle of stator is observed along spanwise and circumferential direction, the entropy in stator is thus increased by 33.17%. Fluid with velocity of 23m/s is found at outlet of diffuser, which causes higher leasing velocity loss. The struts significantly reduces the pressure recover ability of diffuser by 11.42%. However, higher pressure recovery coefficient can be obtained at 0.035 m ∼ 0.135 m along axial distance of diffuser when actual inlet swirl angle is applied.

Karakteristik Pembakaran Wood Pellet Stove dengan Variasi Geometri dan Blockage Ratio Flame Connector

This research was intended to investigate the effect of the geometry and blockage ratio of the flame connector on the combustion characteristics of wood pellets on a wood pellet stove. Combustion characteristics observed in this research included flame visualization, flame temperature, specific fuel consumption, and corrected-specific fuel consumption. Two types of geometry were used as a flame connector, i.e. disk and cone; for each geometry, the blockage ratio was varied at 0,6, 0,7, and 0,8. The blockage ratio was varied by change the number of the circular hole on the flame connector. Combustion in wood pellet stove without flame connector was then used as a comparison. The flame visualization test was applied to find out the color and dimensions of the flame, which was then used to determine the temperature on this flame. The water boiling test method version 4.2.3 was used to determine specific fuel consumption and corrected specific fuel consumption. The combustion chamber of the wood pellet stove has a dimension of 15 cm diameter and 20 cm height. Wood pellet supply used intermittent - continuous feeding system with a mass flow rate of 16 gram/minute. Flame visualization shows that stove with cone flame connector has a larger flame dimension and flame dimension decreases with the increasing of blockage ratio. The highest flame temperature occurred near the outlet of the combustion chamber, the same conditions were observed in all variations experiment. The application of flame connector involves greater specific fuel consumption due to longer boiling time. However, a correction factor by considering the amount of evaporated water results from corrected specific fuel consumption of wood pellet stove with cone flame connector which is smaller compared to the other type of wood pellet stove.

Augmentation of Vortex Cavitator Performance by the Use of Co-Directional Swirl of the Flux after Vortex Chamber

Abstract Background: Acoustic cavitation is the creation and collapse of cavitation caverns in liquid in an acoustic field with a frequency of f = 1–3 kHz. The acoustic-cavitation processes manifest themselves during the collapse phase, with high pressure gradient continuum deformation, with a multiple transformation of energy forms. Liquid whistles are widely used to create an acoustic field of high power, but their efficiency only reaches 6–12%. We propose a liquid whistle in the form of a vortex cavitator (analogue of the Ranque vortex tube) with a rotating body in which a reduction in the input power is predicted. Objective: Verification of feasibility of using a rotating body in a vortex cavitator with a rotation co-directional to the operational pump impeller. Method: The method for identifying the feasibility of using a rotating body is to exclude body from the prototype and directly connect vortex chamber outlet with the pump inlet, which ensures the most complete preservation of co-directional vortex component of the flux entering the pump impeller. Results: The results of experimental studies confirmed the validity of the hypothesis to a greater extent, since we achieved an increase in pressure at the outlet of the pump and a decrease in power at the drive relative to the original design. Conclusions: The feasibility of designing the vortex cavitator body with rotation capability has been established, which will provide a reduction in input power of at least 30% by a rotation of the body, co-directional with the impeller.

An experimental investigation into the effect of flue gas recirculation on ash deposition and Na migration behaviour in circulating fluidized bed during combustion of high sodium Zhundong lignite

The effect of flue gas recirculation (FGR) on ash deposition and Na migration in a laboratory-scale circulating fluidized bed (CFB) burning Zhundong lignite was investigated. The CFB dense phase was maintained at temperature 950 °C, whereas that of the furnace exit was adjusted to 730 and 680 °C respectively by manipulating the FGR flow rate. Two ash deposition probes maintained at 550 °C were installed in the furnace chamber (P1) and cyclone outlet (P2). The deposited ashes along with the bottom and fly ash were collected and analysed by using XRD, SEM-EDX and ICP-OES. Results showed that the P1 deposit consisted of sintered Ca/Mg/Na sulphates and aluminosilicates at 730 °C, but became granular Na2SO4/CaSO4 at 680 °C. The P2 deposit and fly ash were sintered and rich in CaSO4 and Na2SO4 at 730 °C, but did not show signs of sintering at 680 °C. The bottom ash was enriched in CaSiO3 and NaAlSi3O8 at 730 °C, but were dominated by Na6(AlSiO4)6 at 680 °C. Na in the bottom ash increased from 31.7 to 35.2 mg g−1 as FGR flow rate increased, leading to severe bed particle agglomeration consequently. The FGR thus exerted a trade-off effect on the sintering and deposition propensity of fly ash and agglomeration of bed materials.