scholarly journals Numerical simulation on heating performance and emission characteristics of a new multi-stage dispersed burner for gas-fired radiant tubes

2021 ◽  
pp. 323-323
Author(s):  
Huanbao Fan ◽  
Junxiao Feng ◽  
Wei Bai ◽  
Yujie Zhao ◽  
Weidong Li ◽  
...  
Keyword(s):  
Temperature Difference ◽  
Wall Temperature ◽  
Thermal Efficiency ◽  
Structural Parameters ◽  
Nox Reduction ◽  
Nozzle Diameter ◽  
Nox Emission ◽  
Multi Stage ◽  
Secondary Fuel ◽  
Fuel Nozzle

To enhance the temperature uniformity and NOx reduction performance of the gas-fired radiant tubes, we proposed a new multi-stage dispersed burner based on fuel-staging combustion technology in this study. The effect of fuel nozzle structural parameters, including secondary fuel nozzle distance D (30, 50, 70 mm), secondary fuel nozzle diameter ds (2, 3, 4, 5, 6 mm) and tertiary fuel nozzle diameter dt (2.5, 5, 7.5, 10 mm) on the flow field, temperature distribution, NOx generation and thermal efficiency were analyzed by numerical simulations. The results show that the multi-stage dispersed fuel nozzle could slow down the combustion rate and form a low-oxygen dilution zone in the reaction process, reducing the maximum combustion temperature and NOx emission. With the increase of the secondary fuel nozzle distance, the NOx concentration at the outlet decreased from 69.0 ppm to 54.6 ppm, and a decrease of 20.9%. When the secondary fuel nozzle diameter increased from 2 mm to 6 mm, the maximum wall temperature difference gradually increased 72.8 K to 76.3 K. NOx emission at the outlet first decreased, then increased, and was as low as 45.6 ppm at a 5 mm diameter. Furthermore, increasing the tertiary fuel nozzle diameter could reduce the maximum wall temperature difference and NOx emission, and improve thermal efficiency. When dt = 7.5 mm, the overall performance of the radiant tube was the best, and the outlet NOx concentration, wall temperature difference and thermal efficiency were 46.1 ppm, 73.0 K, 63.7%, respectively.

Optimization of a radiant system for hydrothermal performance using Taguchi and utility concept

2021 ◽  
pp. 1-29
Author(s):  
Ratnadeep Nath ◽  
Vikas Verma ◽  
Rahul Tarodiya
Keyword(s):  
Heat Flux ◽  
Pressure Drop ◽  
Temperature Difference ◽  
Wall Temperature ◽  
Thermal Parameters ◽  
Conventional Heating ◽  
Geometrical Parameters ◽  
Maximum Heat ◽  
Utility Concept ◽  
Heating Mode

Abstract Radiant floor panel technology is gaining popularity as an alternative system over conventional heating, ventilation and, air conditioning system (HVAC) to maintain the room temperature for the desired comfort. This research paper aims to optimize the hydrothermal performance of a radiant system by implementing the Taguchi technique and utility concept for cooling and heating mode of operation. Five geometrical and thermal parameters such as pipe diameter, pipe spacing, concrete layer thickness, wall temperature, and inlet and outlet water temperature difference with three levels are chosen as controlling factors to perform optimization. Considering five parameters and three levels, a total of 27 trial runs (L27) are constructed and computed by mathematical calculation. Two different sets of optimum parameters are obtained for maximizing heat flux and minimizing pressure drop. Further, the utility concept is employed to get a single set of parameters to achieve maximum utilization of the radiant system. Taguchi analysis revealed that thermal parameters like temperature difference and wall temperature are the most influential parameters to reach maximum heat transfer and minimum pressure drop followed by geometrical parameters like pipe spacing and diameter for heat flux and pressure drop, respectively. Providing more weightage to heat flux than pressure drop, utility analysis showed 32% and 42% augmentation in heat flux for cooling and heating mode respectively, at the cost of an increase in pressure drop.

2D Natural Convection and Radiation Heat Transfer Simulations of a PWR Fuel Assembly Within a Constant Temperature Support Structure

2006 ◽  
Author(s):  
Pablo E. Araya Go´mez ◽  
Miles Greiner
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Fuel Assembly ◽  
Heat Generation ◽  
Temperature Difference ◽  
Wall Temperature ◽  
Radiation Heat Transfer ◽  
Radiation Heat ◽  
Fuel Rods ◽  
Water Reactor

Two-dimensional simulations of steady natural convection and radiation heat transfer for a 14×14 pressurized water reactor (PWR) spent nuclear fuel assembly within a square basket tube of a typical transport package were conducted using a commercial computational fluid dynamics package. The assembly is composed of 176 heat generating fuel rods and 5 larger guide tubes. The maximum cladding temperature was determined for a range of assembly heat generation rates and uniform basket wall temperatures, with both helium and nitrogen backfill gases. The results are compared with those from earlier simulations of a 7×7 boiling water reactor (BWR). Natural convection/radiation simulations exhibited measurably lower cladding temperatures only when nitrogen is the backfill gas and the wall temperature is below 100°C. The reduction in temperature is larger for the PWR assembly than it was for the BWR. For nitrogen backfill, a ten percent increase in the cladding emissivity (whose value is not well characterized) causes a 4.7% reduction in the maximum cladding to wall temperature difference in the PWR, compared to 4.3% in the BWR at a basket wall temperature of 400°C. Helium backfill exhibits reductions of 2.8% and 3.1% for PWR and BWR respectively. Simulations were performed in which each guide tube was replaced with four heat generating fuel rods, to give a homogeneous array. They show that the maximum cladding to wall temperature difference versus total heat generation within the assembly is not sensitive to this geometric variation.

Water Addition in Diesel Engine Intake for NOx Reduction: Comparison of Modeling and Experiments

2003 ◽  
Author(s):  
Bhaskar Tamma ◽  
Juan Carlos Alvarez ◽  
Aaron J. Simon
Keyword(s):  
Diesel Engine ◽  
Fuel Efficiency ◽  
Nox Reduction ◽  
Engine Performance ◽  
Thermodynamic Cycle ◽  
Nox Emission ◽  
Water Addition ◽  
Predictive Tool ◽  
Fuel Flow ◽  
Influence Of Water

Reduction in emissions, especially NOx has been the main study of various engine researchers in the light of stringent emission norms. To reduce the time and cost involved in testing these technologies, engine thermodynamic cycle predictive tools are used. The present work uses one such predictive tool (GT Power from Gamma Technologies) for predicting the influence of water addition in a turbocharged 6-cylinder diesel engine intake on engine performance and NOx emissions. The experiments for comparison with modeling included the introduction of liquid water in the engine intake stream, between the compressor and intercooler ranging from 0 to 100% of fuel flow rate. NOx emission reduced linearly with water addition with reduction of 63% with less than 1% penalty on fuel efficiency at 100% water addition. The GT Power model predicted the performance within 5% of experimental data and NOx emission within 10% of the experiments.

NOx Reduction Review on Fuel Alternative in Cement Kiln

2013 ◽  
Vol 864-867 ◽  
pp. 1626-1629
Author(s):  
Hai Bing Liu ◽  
Xiao Dong Chen ◽  
Jun Gu
Keyword(s):  
Nitrogen Content ◽  
Fossil Fuels ◽  
Nox Reduction ◽  
Reducing Agent ◽  
Environmental Benefits ◽  
Nox Emission ◽  
Cement Kiln ◽  
Cement Kilns ◽  
Low Nitrogen

The paper first discusses the relativity between alternative combustion andNOx emissions by a test in dry cement kiln, and a lot of case on fuel alternative The main findings of the study are that the use of RDF in cement kilns instead of coal or coke offers environmental benefits and reduce NOx emission. The conclusion is that the NOx generation can probably be lower because of lower flame temperatures or lower air excess and low nitrogen content in comparison with fossil fuels also is impartment reason., another a fact that most of the nitrogen (N) in biomass is released as ammonia (NH3) which acts as a reducing agent with NOx to form nitrogen (N2).

Application of Reburning for NOx Control to a Firetube Package Boiler

1985 ◽  
Vol 107 (3) ◽  
pp. 739-743 ◽  
Author(s):  
J. A. Mulholland ◽  
W. S. Lanier
Keyword(s):  
Natural Gas ◽  
Reaction Order ◽  
Nox Reduction ◽  
Process Variable ◽  
Nox Emission ◽  
Boiler Load ◽  
Second Stage ◽  
Primary Zone ◽  
Dominant Process ◽  
Nox Control

A 730 kW (2.5 × 106 Btu/hr) firetube package boiler was used to demonstrate the application of reburning for NOx emission control. An overall reduction of 50 percent from an uncontrolled NOx emission of 200 ppm was realized by diverting 15 percent of the total boiler load to a natural-gas-fired second stage burner. Tests indicate that the overall reaction order of destruction with respect to initial NOx is greater than one; thus, larger reductions can be expected from reburning applications to systems with higher initial NOx. Rich zone stoichiometry has been identified as the dominant process variable. Primary zone stoichiometry and rich zone residence time are parameters that can be adjusted to maximize NOx reduction. Reburning applied to firetube package boilers requires minimal facility modification. Natural gas would appear to be an ideal reburning fuel as nitrogen in the reburning fuel has been shown to inhibit NOx reduction.

scholarly journals An experimental study on the effects of swirling oxidizer flow and diameter of fuel nozzle on behaviour and light emittance of propane-oxygen non-premixed flame

2017 ◽  
Vol 21 (3) ◽  
pp. 1453-1462 ◽  
Author(s):  
Alireza Javareshkian ◽  
Sadegh Tabejamaat ◽  
Soroush Sarrafan-Sadeghi ◽  
Mohammadreza Baigmohammadi
Keyword(s):  
Reynolds Numbers ◽  
Flame Length ◽  
Nozzle Diameter ◽  
Fuel Flow ◽  
Maximum Value ◽  
Fuel Nozzle ◽  
Flame Shape ◽  
The Stability ◽  
Blue Flame

In this study, the stability and the light emittance of non-premixed propane-oxygen flames have been experimentally evaluated with respect to swirling oxidizer flow and variations in fuel nozzle diameter. Hence, three types of the vanes with the swirl angles of 30?, 45?, and 60? have been chosen for producing the desired swirling flows. The main aims of this study are to determine the flame behaviour, light emittance, and also considering the effect of variation in fuel nozzle diameter on combustion phenomena such as flame length, flame shape, and soot free length parameter. The investigation into the flame phenomenology was comprised of variations of the oxidizer and fuel flow velocities (respective Reynolds numbers) and the fuel nozzle diameter. The results showed that the swirl effect could change the flame luminosity and this way could reduce or increase the maximum value of the flame light emittance in the combustion zone. Therefore, investigation into the flame light emittance can give a good clue for studying the mixing quality of reactants, the flame phenomenology (blue flame or sooty flame, localized extinction), and the combustion intensity in non-premixed flames.

Exploring the Effects of Piston Bowl Geometry and Injector Included Angle On Dual-Fuel and Single-Fuel RCCI

2021 ◽  
Author(s):  
Deivanayagam Hariharan ◽  
Mozhgan Rahimi Boldaji ◽  
Ziming Yan ◽  
Brian Gainey ◽  
Benjamin Lawler
Keyword(s):  
Thermal Efficiency ◽  
Lower Surface ◽  
Combustion Efficiency ◽  
Low Temperature Combustion ◽  
Included Angle ◽  
Piston Bowl ◽  
Start Of Injection ◽  
Lower Reactivity ◽  
Secondary Fuel ◽  
Temperature Combustion

Abstract Reactivity Control Compression Ignition (RCCI) is a Low-Temperature Combustion (LTC) technique that have been proposed to meet the current demand for high thermal efficiency and low engine-out emissions. However, its requirement of two separate fuel systems has been one of its major challenges in the last decade. This leads to the single-fuel RCCI concept, where the secondary fuel is generated from the primary fuel through CPOX reformation. After studying three different fuels, diesel was found to be the best candidate for the reformation process, where the reformed gaseous fuel (with lower reactivity) was used as the secondary fuel and the parent diesel fuel (with higher reactivity) was used as the primary fuel. Previously, the effects of the start of injection (SOI) timing of diesel and the energy-based blend ratio were studied in detail. In this study, the effect of piston profile and the injector included angles were experimentally studied using both conventional fuel pairs and reformate RCCI. A validated CFD model was also used for a better understanding of the experimental trends. Comparing a re-entrant bowl piston with a shallow bowl piston, the latter showed better thermal efficiency, regardless of the fuel combination, due to its 10% lower surface area for the heat transfer. Comparing the 150-degree and 60-degree included angle, the latter showed better combustion efficiency, regardless of the fuel combination, due to its earlier combustion phasing (at constant SOI timing) as the fuel spray targets better region of the cylinder.

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