Showing papers on "Secondary air injection published in 2020"
TL;DR: In this article, a can-type gas turbine combustor operating in flameless combustion mode with liquid fuels was designed and developed, in which air is supplied from different injection holes namely, swirl air near fuel injection, primary, secondary and dilution air in downstream.
30 citations
TL;DR: In this article, the authors investigated the suppression of combustion instability in a model gas turbine combustor with annular air jets and found that the suppression ratio of self-excited oscillations can reach 95% with optimal control, the transition and saturation region of control effectiveness are identified, and the four jet nozzles design case can lead to the best effect of damping.
27 citations
TL;DR: In this article, the effect of air injection at the inlet of the pump on its performance has been focused by detecting and diagnosing the cavitation using vibration technique, and the results obtained for vibration signal in time and frequency domains were analyzed in order to achieve a better understanding regarding detection of cavitation.
Abstract: Cavitation is a problem that occurs in any pump and contributes highly towards the deterioration in the performance of the pump. In industrial applications, it is vital to detect and minimize the effect of cavitation in pumps. The use of various techniques, such as vibration analyses, can provide a more robust detection of cavitation in the pump. In this work, the effect of air injection at the inlet of the pump on its performance has been focused by detecting and diagnosing the cavitation using vibration technique. The results obtained for vibration signal in time and frequency domains were analysed in order to achieve a better understanding regarding detection of cavitation. The effects of different operating conditions related to the cavitation were investigated in this work using different statistical features in time domain. Moreover, fast Fourier transform technique for frequency domain was also applied. The results showed that there is no significant change between both cases (with and without air injection) when the pump works under low flow operating conditions. However, there is a slight difference between both cases after 300(l/min) and drop in the pump head for air injection was noticed as compared to without air injection condition. Moreover, the development of cavitation starts at higher design flow and it will increase when flow rate is increased more than 350(l/min). The trend of vibration signal amplitude was more random with high peaks when compared with normal operating conditions (without cavitation).
27 citations
TL;DR: In this article, the effect of the exhaust tube vortex (ETV) and air staging on nitrogen oxide (NO) concentration and carbon monoxide (CO) concentration, as well as carbon burnout in a swirl-stabilized pulverized coal-fired furnace was investigated.
22 citations
TL;DR: In this article, the effects of single and multi-level tertiary air injection ports were discussed, and the flue gas compositions (NOx and CO) and temperatures along the axis of the down-fired combustor were analyzed.
18 citations
22 Jan 2020
TL;DR: It is found that all the three models predicted very similar trends to the experiment, just like in the case of the oil production rate curves, and therefore, no model, in these two cases, can be singled out as the best.
Abstract: While simulating toe-to-heel air injection (THAI), which is a variant of conventional in situ combustion that uses a horizontal producer well to recover mobilized partially upgraded heavy oil, the chemical kinetics is one of the main sources of uncertainty because the hydrocarbon must be represented by the use of oil pseudo-components. There is, however, no study comparing the predictive capability of the different kinetics schemes used to simulate the THAI process. From the literature, it was determined that the thermal cracking kinetics schemes can be broadly divided into two: split and direct conversion schemes. Unlike the former, the latter does not depend on the selected stoichiometric coefficients of the products. It is concluded that by using a direct conversion scheme, the extent of uncertainty imposed by the kinetics is reduced as the stoichiometric coefficients of the products are known with certainty. Three models, P, G, and B, each with their own different kinetics schemes, were successfully validated against a three-dimensional combustion cell experiment. In models P and G, which do not take low-temperature oxidation (LTO) into account, the effect of oil pseudo-component combustion reactions is insignificant. For model B, which included LTO reactions, LTO was also found to be insignificant because only a small fraction of oxygen bypassed the combustion front and the combustion zone was maintained at temperatures of over 600°C. Therefore, in all the models, it is observed that coke deposition was due to the thermal cracking taking place ahead of the combustion zone. During the first phase of the combustion, peak temperature curves of models P, G, and B closely matched the experimental curve, albeit with some deviations by up to 100°C between 90 and 120 min. After the increase in the air injection flux, only the model P curve overlapped the experimental curve. The model P cumulative oil production curve deviated from the experimental one by only a relative error of 4.0% compared to deviations in models G and B by relative errors of 6.0 and 8.3%, respectively. Consequently, it follows that model P provided better predictions of the peak temperature and cumulative oil production. The same conclusion can be drawn with regard to the produced oxygen concentration and combustion front velocity. With regard to American Petroleum Institute (API) gravity, it is found that all the three models predicted very similar trends to the experiment, just like in the case of the oil production rate curves, and therefore, no model, in these two cases, can be singled out as the best. Also, all the models' predictions of the produced CO X concentration prior to the increase in the air flux closely match the experimental curve. There are, however, serious differences, especially by model P, from the reported experimental curve by up to 15% after the increase in the air flux.
17 citations
TL;DR: In this article, the effect of the cavity-air injection mode on the combustion and flow characteristics of a trapped vortex combustor (TVC) was investigated under atmospheric pressure with an inlet temperature of 473 K.
17 citations
TL;DR: In this article, air was injected as small bubbles into the riser tubes of the solar collector with three different flow rates Q a = 1, 1.5 a n d 2 L P M and was compared with no air injection Qa = 0 L PM.
Abstract: Air bubble injection has been proved to be a simple and effective heat transfer enhancement technique in liquid-to-liquid heat exchangers. This study aimed to investigate the technique experimentally as a possible method for augmenting the thermal performance of a flat plate solar collector in the climatic conditions of Najaf city, Iraq. Air was injected as small bubbles into the riser tubes of the solar collector with three different flow rates Q a = 1 , 1.5 a n d 2 L P M and was compared with no air injection Q a = 0 L P M . The flat plate solar collector had dimensions of 1000 × 2000 × 80 mm (length, width and thickness respectively) and contained seven riser tubes of 8 mm internal diameter and 0.6 mm thickness. A perforated silicon tube (with holes of 0.5 mm diameter) was used for the air injection. Tap water was used as a working fluid and the experiments were repeated three times for each air flow rate. The experimental results showed that the injected air significantly improved the thermal performance of the solar collector. Its efficiency was enhanced by about 16.5%, 69.2% and 68.8% for the injected air flow rates of 1 LPM, 1.5 LPM and 2 LPM respectively.
15 citations
TL;DR: In this article, an experimental plant specifically designed to challenge the main operating issues related to modern biomass combustion systems (mainly NOx, particulate matter, and deposition phenomena) is presented.
Abstract: This paper introduces an experimental plant specifically designed to challenge the main operating issues related to modern biomass combustion systems (mainly NOx, particulate matter, and deposition phenomena). The prototype is an 11–18 kW overfed fixed-bed burner with a modular configuration, and the design considers the implementation of certain strategies for improving combustion: (1) a complete refrigeration system that also includes the fuel bed; and (2) an air injection control through flue gas recirculation. First, the stability and repeatability of the facility were successfully tested, establishing the duration of transient periods in the phase of experiment design. The results revealed similar effects in temperature and particulate emissions when comparing the use of the cooling bed and recirculation techniques. Reductions of 15% and up to 70% were achieved for the exhaust temperature and particulate matter concentration, respectively. Otherwise, the refrigeration considerably reduced the bed temperature, especially in its core, which enhanced the condensation of volatile salts and therefore the fouling phenomena. Although the viability of using both techniques as temperature control methods is demonstrated, further studies are needed to clarify the specific effects of each technology and to clarify the possible significance of a hybrid solution that combines both strategies.
13 citations
TL;DR: In this paper, the authors investigated how to improve the thermal efficiency of a turbo gasoline direct injection (T-GDI) engine using H2 from combined steam and partial oxidation exhaust gas gasoline reforming under low-load stoichiometric conditions.
13 citations
TL;DR: In this paper, an analytical method was proposed to estimate the produced oxygen concentration during AIP, where the oxygen reaction rate was measured by the SBR (small batch reactor) experiments.
TL;DR: In this article, an automatic stability control using tip air injection in a multi-stage axial flow compressor is investigated using a digital signal processing controller for online monitoring wall pressure signal at different stages.
TL;DR: In this paper, a self-designed porous medium thermo-effect cell (PMTEC) was used to monitor the temperature alterations caused by oxidation/combustion reactions occurring within a porous medium under dynamic air flow.
TL;DR: In this article, an air injection assisted in situ upgrading (AAISU) is proposed to improve heat transfer by gas convection and along with the thermal effect of oil oxidation due to the oxygen in the injected air.
TL;DR: In this article, the oil oxidation characteristics of the whole temperature regions from 30 °C to 600 °C during oil reservoir air injection were revealed by experiments and the reaction mechanisms of different regions were explained.
TL;DR: In this paper, the air-water mixed flow shape at the lower surface of a flat plate is captured by an image system under different air flow rates and velocities, and four distinct air water mixed flow are classified: dispersed bubble flow (DBF), mixture flow (MF), air layer flow (ALF), and bifurcation flow (BF).
TL;DR: The single pass shell and multi-tube heat exchanger with double segmental baffles'' performance improvement were experimentally investigated by two methods of air injection into shell side as discussed by the authors.
Abstract: The single pass shell and multi-tube heat exchanger with double segmental baffles'’ performance improvement were experimentally investigated by two methods of air injection into shell side ...
TL;DR: In this article, the effect of reservoir thickness on the performance of toe-to-heel air injection (THAI) process was studied and it was found that the lower the reservoir thickness, the larger the cumulative air-tooil ratio (cAOR) indicating that heat loss increases with the decrease in the reservoir depth.
Abstract: The increasing energy demand has to be met while we transitioned to a decarbonized energy future. Heavy oil and bitumen reserves are urgently needed to be developed to ensure that a smooth transition is provided. In this work, field-scale kinetics parameters are used to study the effect of reservoir pay thickness on the performance of toe-to-heel air injection (THAI) process. Air was injected at constant rate into three different models with the thicknesses of 24 m, 16 m, and 8 m, respectively. The oil produced is slightly affected by the reservoir thickness. It is found that the lower the reservoir thickness, the larger the cumulative air-to-oil ratio (cAOR), indicating that heat loss increases with the decrease in the reservoir thickness. This trend is similar to steam-based processes. At constant air injection flux, it is found that both the cumulative oil produced and the cAOR decrease with the decrease in the reservoir thicknesses. This decrease is attributed to the decrease in the rate of heat generation in the thinner reservoirs, which in turn results in lower combustion zone temperature and thus lower temperature gradients between the reservoir and the overburden and the reservoir and the underburden. Consequently, a more general conclusion is that decreasing the air injection rate by the same factor the reservoir thickness is decreased (i.e. keeping the air injection flux constant) results in a more economical THAI process operation compared to when the air injection rate is kept constant (i.e. allowing increase in air injection flux).
TL;DR: In this article, thermal cracking experiments of ultra-heavy oils in small batch reactor as well as thermogravimetry analysis (TGA) experiments have been conducted under high pressure in the presence of air and nitrogen to simulate the AAISU process.
TL;DR: In this paper, a reasonable injection and production parameters for the oilfield are calculated by using the oil field parameters, which shows that the calculated value of injection-production ratio is consistent with the actual value, which can guide the adjustment of production parameters in an oilfield.
Abstract: The stability of combustion in the process of fire flooding requires not only a reasonable gas injection rate but also a matching exhaust rate. A reasonable injection-production balance system is very important. Based on the material balance of injection-production, the expression of injection-production ratio suitable for normal fire flooding production is established. The air injection rate of fire flooding combustion and oxygen consumption of formation pressurization is analyzed by this formula to calculate the gas production and liquid production in combustion. The reasonable injection and production parameters for the oilfield are calculated by using the oilfield parameters. It can be seen that the calculated value of injection-production ratio is consistent with the actual value, which shows that the injection-production ratio is reasonable and can guide the adjustment of production parameters in the oilfield.
TL;DR: In this article, the authors examined ramp rate improvements and performance enhancement through compressed air injection at the back of the high-pressure compressor (HPC) and two configurations of AD engines are considered in the investigation.
TL;DR: In this article, numerical simulations were conducted about the air layer on the lower surface of a large ship model with and without a propeller, and the influence of air injection on the propulsion performance of the propeller was investigated by comparing of thrust and torque of propeller.
TL;DR: In this article, a flow-type annular cylindrical combustor with an outer diameter of 503mm was used to investigate the influence of air addition to products of continuous spin detonation of CH4/676/$m$$m$$¯¯¯¯¯¯H2−air mixtures on the parameters of detonation waves, the pressure in the combustor, and the specific impulse.
Abstract: Results of experimental investigations in a flow-type annular cylindrical combustor with an outer diameter of 503 mm are reported. The influence of air addition to products of continuous spin detonation of CH4/
$$m$$
H2–air mixtures on the parameters of detonation waves, the pressure in the combustor, and the specific impulse is considered. It is demonstrated that air injection into detonation products increases the velocity of continuous spin detonation, the pressure in the combustor, and the thrust, whereas the specific flow rate of the fuel decreases.
TL;DR: In this paper, the authors describe miscible displacement upon air injection in a porous medium saturated with oil corresponding to conditions of high-pressure air injection (HPAI) under the assumption that injection fluids and produced fluids are fully miscible with the oil at the prevailing high pressure.
Abstract: This paper describes miscible displacement upon air injection in a porous medium saturated with oil corresponding to conditions of high-pressure air injection (HPAI). We assume that injection fluids and produced fluids are fully miscible with the oil at the prevailing high pressure. We use three pseudo-components, viz., oxygen, oil, and an inert component, which includes nitrogen, carbon dioxide, etc. To model the fingering instabilities, we follow a similar procedure as proposed by Koval (SPE J. 3(02):145–154, 1963) and include the reaction between oxygen and oil in the Koval model. The equations are solved numerically, using a finite element software package (COMSOL). The results show that a combustion wave is formed. We study the performance at low and high viscosities and show that the reaction improves the speed and degree of recovery at later times.
TL;DR: In this paper, a numerical model of an ultrasonic mist generator for the pre-cooling of the inlet air of the condenser in air conditioning applications was developed and validated against the experimental data obtained in a wind tunnel experimental facility.
Abstract: Pre-cooling of inlet air using evaporative cooling is an effective approach to enhance the performance of air-cooled condensers in air conditioning applications. Ultrasonic mist generators have emerged as a promising alternative to conventional evaporative cooling systems based on cooling pads or spray cooling. This paper presents the developed numerical model of an ultrasonic mist generator for the evaporative pre-cooling of the inlet air of the condenser in air conditioning applications. The model was validated against the experimental data obtained in a wind tunnel experimental facility. A parametric analysis including some physical variables involved in the cooling process was carried out, including the main axial air velocity, the injection air velocity and the water mass flow rate of atomized water. The dimensionless groups water-to-air mass flow and air-to-air mass flow ratios were found to most affect the average evaporative cooling efficiency. A maximum value of 0.654 was found for the studied conditions. The optimization analysis carried out shows that the operational ranges leading to the best overall performance are 5 × 10 − 4 ≤ m ˙ w / m ˙ a T ≤ 0.002 and 0.035 ≤ m ˙ a i / m ˙ a T ≤ 0.05 . Under these conditions, there is a better distribution of the water mist throughout the control section and a more homogeneous and effective evaporative cooling process.
Patent•
17 Jan 2020
TL;DR: In this article, a garbage landfill rapid stabilization system is described, in which a leachate horizontal guide and discharge system is arranged at the bottom of a garbage pile, an air exhaust and injection system and a lachate irrigation and drainage system are inserted into the garbage pile.
Abstract: The invention discloses a garbage landfill rapid stabilization system. A leachate horizontal guide and discharge system is arranged at the bottom of a garbage pile, an air exhaust and injection systemand a leachate irrigation and drainage system are inserted into the garbage pile, and the leachate horizontal guide and discharge system and the leachate irrigation and drainage system communicate with a leachate collection well. One end of an air exhaust and injection pipeline in the exhaust and injection system is vertically inserted into the garbage pile, the other end of the air exhaust and injection pipeline is connected with a second control system, and the other end of the second control system is connected with an air injection fan and an air exhaust fan. One end of the leachate irrigation and drainage system is vertically inserted into the garbage pile of a garbage landfill, the other end of the leachate irrigation and drainage system is connected with a third control system, andthe other end of the third control system is connected with a leachate pumping and discharging pump and a leachate lifting pump. By means of the system, sufficient oxygen is provided for garbage landfill, and it is ensured that garbage is subjected to aerobic biochemical degradation. The landfill becomes a composite purification reactor by refilling leachate, nutrient substances in the leachate can be fully circulated in the garbage pile, and the growth metabolic efficiency of microorganisms is effectively improved.
Patent•
10 Apr 2020
TL;DR: In this article, the authors present a system for cleaning a solar panel, which includes a sensing unit, storage unit, air injection unit, an actuator, and a control unit, and the control unit controls such that cold air is injected through a compressed air outlet of an air supply when the pollutant detected by the sensor unit is water, moisture or dust.
Abstract: The present invention relates to a device for cleaning a solar panel, which includes a sensing unit, a storage unit, an air injection unit, an actuator, and a control unit. The control unit controls such that cold air is injected through a compressed air outlet of an air supply when the pollutant detected by the sensor unit is water, moisture, or dust. The control unit controls such the hot air is injected through the compressed air outlet of the air supply when the pollutant detected by the sensor unit is snow. The air supply injects compressed air vertically to the solar panel or injects compressed air in a state in which the air supply is rotated at a certain angle (10 to 15 degrees) on the left and right sides. The pressure of compressed air is adjustable. As the compressed air is discharged by adjusting the pressure, the cleaning efficiency is improved because it is discharged to the surface of the solar panel as if sweeping with a cleaning tool. The control unit compares the amount of power generated by the solar panels with the amount of power generated by at least one or more comparison target solar panels located at upper/lower/left/right, and is set by the data input unit to determine whether there is a solar panel which has an allowable error in the difference in power generation between panels stored in the data storage unit. When a solar panel having a reduced power generation amount exceeding an allowable error is detected, it is determined that the surface of the solar panel having a reduced power generation amount is contaminated, and washing is performed through a panel washing driving unit.
TL;DR: In this paper, the impact of injection strategy on temperature distribution and flame structure in a planar single-cavity TVC is investigated, where a fuel jet and an air jet are injected directly into the cavity from the forebody and the afterbody, respectively.
Abstract: Propane combustion in a trapped vortex combustor (TVC) is characterized via large eddy simulation coupled with filtered mass density function. A computational algorithm based on high order finite difference (FD) schemes, is employed to solve the Eulerian filtered compressible Navier-Stokes equations. In contrast, a Lagrangian Monte-Carlo solver based on the filtered mass density function is invoked to describe the scalar field. The impact of injection strategy on temperature distribution and flame structure in a planar single-cavity TVC is investigated. A fuel jet and an air jet are injected directly into the cavity from the forebody and the afterbody, respectively. Different injection schemes are contemplated by altering fuel and air jet locations representing the different flow and flame structures. The temperature distribution, along with cross-sectional averaged temperature and flame structure, are compared for fuel/air injection strategies. The temperature field reveals that configurations in which both air and fuel jets are located at the cavity-walls midpoint or adjacent to the cavity inferior wall, lead to a more uniform temperature distribution and lower maximum temperature with the latter configuration performing slightly better. While, the former configuration provides the closest cross-sectional averaged temperature to the adiabatic flame temperature. The reaction rate distributions show that the configurations mentioned above lead to a more contained flame, chiefly due to more efficient fuel-air mixing at lower regions of the cavity.