Experimental Investigation of Flow Phenomena of a Single Fuel Jet in Cross-Flow During Highly Preheated Air Combustion Conditions

2006 ◽  
Vol 129 (2) ◽  
pp. 556-564 ◽  
Author(s):  
Magnus Mörtberg ◽  
Wlodzimierz Blasiak ◽  
Ashwani K. Gupta
Keyword(s):  
High Temperature ◽  
High Speed ◽  
Cross Flow ◽  
Flux Ratio ◽  
Flow Dynamics ◽  
High Temperature Air Combustion ◽  
Fuel Jet ◽  
Temperature Combustion ◽  
High Temperature Combustion

Particle image velocimetry and a spectroscopy technique has been used to obtain information on the flow dynamics and flame thermal signatures of a fuel jet injected into a cross-flow of normal temperature and very high-temperature combustion air. Flame fluctuations were obtained using a high-speed camera and then performing fast Fourier transform on the signal. High-temperature air combustion has been demonstrated to provide significant energy savings, higher heat flux, and reduction of pollution and equipment size of industrial furnaces. The dynamics of flow associated with high temperature combustion air conditions (for mean velocity, axial strain rate and vorticity) has been obtained in two-dimensional using propane and methane as the fuels. The data have been compared with normal temperature combustion air case, including the nonburning case. A specially designed experimental test furnace facility was used to provide well-controlled conditions and allowed air preheats to 1100°C using regenerative burners. Four different experimental cases have been examined. The momentum flux ratio between the burning and nonburning conditions was kept constant to provide comparison between cases. The results provide the role of high-temperature combustion air on the dynamics of the flow, turbulence, and mixing under nonburning and combustion conditions. The data provide the direct role of combustion on flow dynamics, turbulence, and flame fluctuations. High-temperature combustion air at low-oxygen concentration showed larger flame volume with less fluctuation than normal or high-temperature normal air cases. High-temperature combustion air technology prolongs mixing in the combustion zone to enhance the flame volume, reduce flame fluctuations, and to provide uniform flow and thermal characteristics. This information assists in model validation and model development for new applications and technology development using high-temperature air combustion principles.

Thermal Characteristics of Gaseous Fuel Flames Using High Temperature Air

2004 ◽  
Vol 126 (1) ◽  
pp. 9-19 ◽  
Author(s):  
A. K. Gupta
Keyword(s):  
High Temperature ◽  
Energy Savings ◽  
Elevated Temperatures ◽  
Waste Heat ◽  
Uniform Heat Flux ◽  
Chemical Behavior ◽  
High Temperature Air Combustion ◽  
Temperature Combustion ◽  
Combustion Technology ◽  
High Temperature Combustion

Recent advances on high temperature air combustion (HiTAC) have demonstrated significant energy savings, higher and uniform thermal field, lower pollution, and smaller size of the equipment for a range of furnace applications. The HiTAC technology has evolved from the conception of excess enthalpy combustion (EEC) to high and ultra-high preheated air combustion. In the HiTAC method, combined heat regeneration and low oxygen methods are utilized to enlarge and control the flame thermal behavior. This technology has shown promise for much wider applications in various process and power industries, energy conversion, and waste to clean fuel conversion. For each application the flow, thermal, and chemical behavior of HiTAC flames must be carefully tailored to satisfy the specific needs. Qualitative and quantitative results are presented on several gas-air diffusion flames using high-temperature combustion air. A specially designed regenerative combustion test furnace facility, built by Nippon Furnace Kogyo, Japan, was used to preheat the combustion air to elevated temperatures. The flames with highly preheated combustion air were significantly more stable and homogeneous (both temporally and spatially) as compared to the flames with room-temperature combustion air. The global flame features showed the flame color to change from yellow to blue to bluish-green to green over the range of conditions examined. In some cases hybrid and purple color flame was also observed. Under certain conditions flameless or colorless oxidation of the fuel has also been demonstrated. Information on global flame features, flame spectral emission characteristics, spatial distribution of OH, CH, and C2 species and emission of pollutants has been obtained. Low levels of NOx along with negligible levels of CO and HC have been obtained using high-temperature combustion air. The thermal and chemical behavior of high-temperature air combustion flames depends on fuel property, preheat temperature, and oxygen concentration of air. Waste heat from a furnace in high-temperature air combustion technology is retrieved and introduced back into the furnace using regenerator. These features help save energy, which subsequently also reduce the emission of CO2 (greenhouse gas) to the environment. Flames with high temperature air provide significantly higher and uniform heat flux than normal air, which reduces the equipment size or increases the process material throughput for same size of the equipment. The high-temperature air combustion technology can provide significant energy savings (up to about 60%), downsizing of the equipment (about 30%), and pollution reduction (about 25%). Fuel energy savings directly translates to a reduction of CO2 and other greenhouse gases to the environment.

scholarly journals Simultaneous High-Speed Formaldehyde PLIF and Schlieren Imaging of Multiple Injections From an ECN Spray D Injector

2020 ◽  
Author(s):  
Noud Maes ◽  
Hyung Sub Sim ◽  
Lukas Weiss ◽  
Lyle Pickett
Keyword(s):  
High Temperature ◽  
High Speed ◽  
Combustion Products ◽  
Schlieren Imaging ◽  
Multiple Injections ◽  
Soot Precursors ◽  
Planar Laser ◽  
Temperature Combustion ◽  
Polycyclic Aromatic ◽  
High Temperature Combustion

Abstract The interaction of multiple injections in a diesel engine facilitates a complex interplay between freshly introduced fuel, previous combustion products, and overall combustion. To improve understanding of the relevant processes, high-speed Planar Laser-Induced Fluorescence (PLIF) with 355-nm excitation of formaldehyde and Polycyclic Aromatic Hydrocarbon (PAH) soot precursors is applied to multiple injections of n-dodecane from Engine Combustion Network Spray D, characterized by a converging 189-μm nozzle. High-speed schlieren imaging is applied simultaneously with 50-kHz PLIF excitation to visualize the spray structures, jet penetration, and ignition processes. For the first injection, formaldehyde (as an indicator of low-temperature chemistry) is first found in the jet periphery, after which it quickly propagates through the center of the jet, towards the jet head prior to high-temperature ignition. At second-stage ignition, downstream formaldehyde is consumed rapidly and upstream formaldehyde develops into a quasi-steady structure for as long as the momentum flux from the injector continues. Since the first injection in this work is relatively short, differences to a single long injection are readily observed, ultimately resulting in high-temperature combustion and PAH structures appearing farther upstream after the end of injection. For the second injection in this work, the first formaldehyde signal is significantly advanced because of the entrained high-temperature combustion products, and an obvious premixed burn event does not occur. The propensity for combustion recession after the end of the first injection changes significantly with ambient temperature, thereby affecting the level of interaction between the first- and second injection.

scholarly journals Temperature Fields of the Droplets and Gases Mixture

2020 ◽  
Vol 10 (7) ◽  
pp. 2212
Author(s):  
Roman S. Volkov ◽  
Ivan S. Voytkov ◽  
Pavel A. Strizhak
Keyword(s):  
High Temperature ◽  
High Speed ◽  
Air Flow ◽  
Combustion Products ◽  
Temperature Fields ◽  
Vapor Mixture ◽  
Heated Air ◽  
Observation Area ◽  
Temperature Combustion ◽  
High Temperature Combustion

In this research, we obtain gas–vapor mixture temperature fields generated by blending droplets and high-temperature combustion products. Similar experiments are conducted for droplet injection into heated air flow. This kind of measurement is essential for high-temperature and high-speed processes in contact heat exchangers or in liquid treatment chambers, as well as in firefighting systems. Experiments are conducted using an optical system based on Laser-Induced Phosphorescence as well as two types of thermocouples with a similar measurement range but different response times (0.1–3 s) and accuracy (1–5 °C). In our experiments, we inject droplets into the heated air flow (first scheme) and into the flow of high-temperature combustion products (second scheme). We concentrate on the unsteady inhomogeneous temperature fields of the gas–vapor mixture produced by blending the above-mentioned flows and monitoring the lifetime of the relatively low gas temperature after droplets passes through the observation area. The scientific novelty of this research comes from the first ever comparison of the temperature measurements of a gas–vapor–droplet mixture obtained by contact and non-contact systems. The advantages and limitations of the contact and non-contact techniques are defined for the measurement of gas–vapor mixture temperature.

Experimental Research on Direct Gasification and Melting Incineration of Municipal Solid Waste

2005 ◽  
Author(s):  
Jianhang Hu ◽  
Hua Wang ◽  
Fang He
Keyword(s):  
High Temperature ◽  
Combustion Zone ◽  
High Speed ◽  
Melting Furnace ◽  
Melting Zone ◽  
Secondary Combustion ◽  
Combustible Gas ◽  
Lead And Zinc ◽  
Temperature Combustion ◽  
High Temperature Combustion

Direct Gasification & Melting technology is tacking with the development of environment-friendly technology and products harmonized with giving impact on the external environment. The technological process can be described as: Waste is fed from one side of the melting furnace. The auxiliary fuels maybe various fuels, such as coal, oil and combustible gas et al. The auxiliary fuel is for melting the waste. The limestone is the basically controller of slag. Air is sent through the third tuyers into the secondary combustion zone, through the second tuyers into the pryolysis and gasifying zone, through the main tuyers into the high temperature combustion and melting zone at the lower portion. In the secondary combustion zone, a high temperature reducing atmosphere is established which suppress the generation of dioxins and pyrolyzed tar. In the pryolysis and gasifying zone, the waste is brought in mild fluidizing state and gasified by the injected high-speed air through the secondary tuyers. Through the zone, the non-combustible components fall into the high temperature combustion and melting zone the bottom of the furnace. The fluidization prevents bridging or hanging obstruction due to mutual melting of plastics and other materials. In the high temperature combustion and melting zone, the combustion of auxiliary fuels and fixed carbon melt the ash. During the flow-down period, the melted ash becomes homogeneous slag. Also in this process, lead and zinc are vaporized and removed from the slag. Then, the slag is continuously extracted through the extracting equipment along with metals. The slag that is recovered from the water bath is treated by magnetic separation to remove metals, and becomes a resource material. The combustion and melting is controlled at temperatures of 1400°C or higher. The concentrations of dioxins were less than 0.1 ng-TEQ/Nm3 at the smokestack outlet and 0.0012ng-TEQ/g at the slag.

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