scholarly journals Influence of Surroundings on Radiant Tube Lifetime in Indirect-Fired Vertical Strip Annealing Furnaces

2020 ◽  
Vol 10 (5) ◽  
pp. 1748
Author(s):  
Dominik Büschgens ◽  
Narayana K. Karthik ◽  
Nico Schmitz ◽  
Herbert Pfeifer
Keyword(s):  
Numerical Models ◽  
Characteristic Temperature ◽  
Furnace Chamber ◽  
Firing Cycle ◽  
Vertical Strip ◽  
Reference Case ◽  
Radiant Tube ◽  
Vertical Column ◽  
Radiation Exchange ◽  
Burner Operation

The effects of surrounding radiation—emanating from radiation exchange with neighboring partners in indirect-fired vertical strip annealing furnaces, such as the other radiant tubes, the passing strip, and the enclosing furnace chamber—on the radiant tube lifetime were studied. In-house developed and validated numerical models were used to calculate the thermomechanical behavior, especially creep deformations and the corresponding stresses as lifetime indicating parameters. Different setups of recirculating P-type radiant tubes were investigated, including a reference case of an isolated tube. The investigations could be broadly classified into the study of the effects of different tube arrangements, burner operations (synchronous/asynchronous on/off firing), and changes of strip parameters (width/temperature). Results showed higher creep deformation of the central radiant tube in the setup with three tubes arranged horizontally in a row compared to three tubes stacked in a vertical column, even though the respective characteristic temperature values in a firing cycle were similar. Furthermore, the cases with asynchronous burner firing resulted in lower creep rates than other cases, where the burners were operating in synchronous on/off firing modes. In addition, the change of strip width had a higher impact on radiant tube lifetime compared to locally changing strip temperatures across the furnace. Alternating temperatures, caused by burner operation or process changes, such as change of strip’s speed or cross-section, and local temperature gradients were observed to be the main factors influencing the tube’s service life.

Analysis of Heat Transfer through PVC Window Profile Reinforced with Ti6Al4V Alloy

2016 ◽  
Vol 687 ◽  
pp. 236-242 ◽  
Author(s):  
Piotr Lacki ◽  
Judyta Różycka ◽  
Marcin Rogoziński
Keyword(s):  
Heat Transfer ◽  
Titanium Alloy ◽  
Thermal Insulation ◽  
Numerical Models ◽  
Characteristic Temperature ◽  
Permanent Deformation ◽  
Transfer Coefficients ◽  
Element Analysis ◽  
Ti6al4v Titanium Alloy ◽  
Characteristic Points

This requires the use of additional reinforcement in order to prevent excessive or permanent deformation of PVC windows. In the paper particular attention was devoted to space located in a corrosive environment exposed to chemical agents. For this purpose, proposed to change the previously used steel profiles reinforcements made of Ti6Al4V titanium alloy corrosion-resistant in the air, at sea and many types of industrial atmosphere. Analysis of the thermal insulation properties of PVC windows with additional reinforcement of profile Ti6Al4V titanium alloy was performed. PVC window set in a layer of thermal insulation was analyzed. Research was conducted using Finite Element Analysis. Numerical models and thermal calculations were made in the program ADINA, assuming appropriate material parameters. The constant internal temperature of 20 ̊ and an outer-20 ̊ was assumed. The course of temperature distribution in baffle in time 24 hours and graphs of characteristic points was obtained. The time of in which followed the steady flow of heat, as well as the course of isotherm of characteristic temperature in the baffle was determined. On the basis of numerical analysis obtained vector distribution of heat flux q [W/m2] and was determined heat transfer coefficients U [W/m2K] for the whole window with titanium reinforcement . All results were compared with the model of PVC windows reinforced with steel profile.

Effects of Slenderness and Fundamental Frequency on the Dynamic Response of Adjacent Structures

2019 ◽  
Vol 19 (09) ◽  
pp. 1950105
Author(s):  
Gonzalo Barrios ◽  
Vinuka Nanayakkara ◽  
Pramodya De Alwis ◽  
Nawawi Chouw
Keyword(s):  
Dynamic Response ◽  
Fundamental Frequency ◽  
Soil Structure ◽  
Numerical Models ◽  
Ground Motions ◽  
Soil Structure Interaction ◽  
Reference Case ◽  
Maximum Acceleration ◽  
Structure Interaction ◽  
Adjacent Structures

In conventional seismic design, the structure is often assumed to be fixed at the base. However, this assumption does not reflect reality. Furthermore, if the structure has close neighbors, the adjacent structures will alter the response of the structure considered. Investigations on soil–structure interaction and structure–soil–structure interaction have been performed mainly using numerical models. The present work addresses the dynamic response of adjacent single-degree-of-freedom models on a laminar box filled with sand. Impulse loads and simulated ground motions were applied. The standalone condition was also studied as a reference case. Models with different fundamental frequencies and slenderness were considered. Results from the impulse tests showed that the top displacement of the models with an adjacent structure was reduced compared with that of the standalone case. Changes in the fundamental frequency of the models due to the presence of an adjacent model were also observed. Results from ground motions showed amplification of the maximum acceleration and the top displacement of the models when both structures have a similar fundamental frequency.

scholarly journals A Transient Temperature Solution for Bore-Hole Model Testing

1987 ◽  
Vol 33 (114) ◽  
pp. 140-148 ◽  
Author(s):  
Brian Hanson ◽  
Robert E. Dickinson
Keyword(s):  
Response Time ◽  
Time Scale ◽  
Numerical Models ◽  
Ice Sheet ◽  
Energy Balance Equation ◽  
Finite Difference Approximation ◽  
Difference Approximation ◽  
Small Scale ◽  
Transient Temperature ◽  
Vertical Column

AbstractTransient temperature variations in a vertical column of ice with horizontally uniform conditions, constant vertical strain-rate and specified surface temperature, and basal heat flux can be calculated analytically. The solution consists of eigenfunctions which are forms of the confluent hypergeometric function. This solution shows that advection and diffusion have clearly separated areas of dominance, with diffusion being a sufficient approximation for small-scale perturbations in the temperature profile and advection placing an upper limit on the response time of the ice sheet as a whole. This solution is useful for analysis and testing of numerical models, for evaluation of the response time of an ice sheet and for exploratory analysis of real bore-hole data. The lowest eigenvalue of the solution determines the time-scale for transient decay of temperature anomalies. The time-scale can be determined for more general strain-rates using a finite-difference approximation to the linearized energy-balance equation.

scholarly journals MAX-DOAS NO<sub>2</sub> observations over Guangzhou, China; ground-based and satellite comparisons

2018 ◽  
Vol 11 (4) ◽  
pp. 2239-2255 ◽  
Author(s):  
Theano Drosoglou ◽  
Maria Elissavet Koukouli ◽  
Natalia Kouremeti ◽  
Alkiviadis F. Bais ◽  
Irene Zyrichidou ◽  
...  
Keyword(s):  
Time Window ◽  
Correlation Coefficients ◽  
Urban Site ◽  
Reference Case ◽  
Vertical Column ◽  
Time Period ◽  
Tropospheric No2 ◽  
Vertical Column Density ◽  
Satellite Sensors ◽  
Academy Of Sciences

Abstract. In this study, the tropospheric NO2 vertical column density (VCD) over an urban site in Guangzhou megacity in China is investigated by means of MAX-DOAS measurements during a campaign from late March 2015 to mid-March 2016. A MAX-DOAS system was deployed at the Guangzhou Institute of Geochemistry of the Chinese Academy of Sciences and operated there for about 1 year, during the spring and summer months. The tropospheric NO2 VCDs retrieved by the MAX-DOAS are presented and compared with space-borne observations from GOME-2/MetOp-A, GOME-2/MetOp-B and OMI/Aura satellite sensors. The comparisons reveal good agreement between satellite and MAX-DOAS observations over Guangzhou, with correlation coefficients ranging between 0.795 for GOME-2B and 0.996 for OMI. However, the tropospheric NO2 loadings are underestimated by the satellite sensors on average by 25.1, 10.3 and 5.7 %, respectively, for OMI, GOME-2A and GOME-2B. Our results indicate that GOME-2B retrievals are closer to those of the MAX-DOAS instrument due to the lower tropospheric NO2 concentrations during the days with valid GOME-2B observations. In addition, the effect of the main coincidence criteria is investigated, namely the cloud fraction (CF), the distance (d) between the satellite pixel center and the ground-based measurement site, as well as the time period within which the MAX-DOAS data are averaged around the satellite overpass time. The effect of CF and time window criteria is more profound on the selection of OMI overpass data, probably due to its smaller pixel size. The available data pairs are reduced to half and about one-third for CF  ≤  0.3 and CF  ≤  0.2, respectively, while, compared to larger CF thresholds, the correlation coefficient is improved to 0.996 from about 0.86, the slope value is very close to unity ( ∼  0.98) and the mean satellite underestimation is reduced to about half (from  ∼  7 to  ∼  3.5  ×  1015 molecules cm−2). On the other hand, the distance criterion affects mostly GOME-2B data selection, because GOME-2B pixels are quite evenly distributed among the different radii used in the sensitivity test. More specifically, the number of collocations is notably reduced when stricter radius limits are applied, the r value is improved from 0.795 (d ≤  50 km) to 0.953 (d ≤  20 km), and the absolute mean bias decreases about 6 times for d ≤  30 km compared to the reference case (d ≤  50 km).

scholarly journals Cork Core Sandwich Plates for Blast Protection

2020 ◽  
Vol 10 (15) ◽  
pp. 5180
Author(s):  
Jesús Pernas-Sánchez ◽  
Jose A. Artero-Guerrero ◽  
David Varas ◽  
Filipe Teixeira-Dias
Keyword(s):  
Energy Absorption ◽  
Mechanical Response ◽  
Numerical Models ◽  
Areal Density ◽  
Absorption Capacity ◽  
Geometrical Parameters ◽  
Sandwich Plates ◽  
Arbitrary Lagrangian Eulerian ◽  
Reference Case ◽  
Blast Protection

A numerical model is developed and validated to analyse the performance of aluminium skin and agglomerated cork core sandwich plates subjected to blast loads. Two numerical approaches are used and thoroughly compared to generate the blast loading: an Arbitrary-Lagrangian–Eulerian approach and the Load Blast Enhanced method. Both of the models are validated by comparing the numerical results with experimental observations. A detailed analysis of the sandwich behaviour is done for both approaches showing small differences regarding the mechanical response of the sandwich structure. The results obtained from the numerical models uncover the specific energy absorption mechanisms happening within the sandwich plate components. A new core topology is proposed, based on these results, which maximises the energy absorption capacity of the plate, keeping the areal density unchanged. A wavy agglomerated cork core is proposed and the effects of different geometrical parameters on the energy absorption are thoroughly analysed and discussed. The proposed optimised plate configuration shows an increase in the total absorbed energy of close to 40% relative to a reference case with the same areal density. The adopted optimisation methodology can be applied to alternative configurations to increase the performance of sandwich structures under blast events.

scholarly journals A Transient Temperature Solution for Bore-Hole Model Testing

1987 ◽  
Vol 33 (114) ◽  
pp. 140-148 ◽  
Author(s):  
Brian Hanson ◽  
Robert E. Dickinson
Keyword(s):  
Response Time ◽  
Time Scale ◽  
Numerical Models ◽  
Ice Sheet ◽  
Energy Balance Equation ◽  
Finite Difference Approximation ◽  
Difference Approximation ◽  
Small Scale ◽  
Transient Temperature ◽  
Vertical Column

AbstractTransient temperature variations in a vertical column of ice with horizontally uniform conditions, constant vertical strain-rate and specified surface temperature, and basal heat flux can be calculated analytically. The solution consists of eigenfunctions which are forms of the confluent hypergeometric function. This solution shows that advection and diffusion have clearly separated areas of dominance, with diffusion being a sufficient approximation for small-scale perturbations in the temperature profile and advection placing an upper limit on the response time of the ice sheet as a whole. This solution is useful for analysis and testing of numerical models, for evaluation of the response time of an ice sheet and for exploratory analysis of real bore-hole data. The lowest eigenvalue of the solution determines the time-scale for transient decay of temperature anomalies. The time-scale can be determined for more general strain-rates using a finite-difference approximation to the linearized energy-balance equation.

Reliability Analysis of CFD Solution Using Sensitivity Theory

2003 ◽  
Author(s):  
Nobuatsu Tanaka ◽  
Yasunori Motoyama
Keyword(s):  
Sensitivity Analysis ◽  
Numerical Solution ◽  
Numerical Method ◽  
Reliability Analysis ◽  
Numerical Models ◽  
The Other ◽  
Reference Case ◽  
Strict Solution ◽  
Sensitivity Theory ◽  
Additional Calculation

In this study, we present a new numerical method to quantitatively analyze the reliability of numerical models by using the sensitivity theory. If a reference case of typical parameters is once calculated with the method, no additional calculation is required to estimate the results of the other numerical parameters such as more detailed solutions. Furthermore, we can estimate the strict solution from the sensitivity analysis results and can quantitatively evaluate the reliability of the numerical solution by calculating the numerical error.

scholarly journals Spatial and Temporal Variation of NO2 Vertical Column Densities (VCDs) over Poland: Comparison of the Sentinel-5P TROPOMI Observations and the GEM-AQ Model Simulations

Atmosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 896
Author(s):  
Marcin Kawka ◽  
Joanna Struzewska ◽  
Jacek W. Kaminski
Keyword(s):  
High Resolution ◽  
Numerical Models ◽  
Surface Concentration ◽  
Point Sources ◽  
Spatial And Temporal Variation ◽  
Emission Data ◽  
Vertical Column ◽  
Near Surface ◽  
Boundary Layer Height ◽  
Column Number

The TROPOMI instrument aboard Sentinel-5P is a relatively new, high-resolution source of information about atmosphere composition. One of the primary atmospheric trace gases that we can observe is nitrogen dioxide. Thanks to TROPOMI capabilities (high resolution and short revisit time), one can describe regional and seasonal NO2 concentration patterns. Thus far, such patterns have been analysed by either ground measurements (which have been limited to specific locations and only to the near-surface troposphere layer) or numerical models. This paper compares the TROPOMI and GEM-AQ derived vertical column densities (VCD) over Poland, focusing on large point sources. Although well established in atmospheric science, the GEM-AQ simulations are always based on emission data, which in the case of the energy sector were reported by stack operators. In addition, we checked how cloudy conditions influence TROPOMI results. Finally, we tried to link the NO2 column number densities with surface concentration using boundary layer height as an additional explanatory variable. Our results showed a general underestimation of NO2 tropospheric column number density by the GEM-AQ model (compared to the TROPOMI). However, for the locations of the most significant point sources, we noticed a systematic overestimation by the GEM-AQ model (excluding spring and summer months when TROPOMI presents larger NO2 VCDs than GEM-AQ). For the winter months, we have found TROPOMI NO2 VCD results highly dependent on the choice of qa_value threshold.

scholarly journals MAX-DOAS NO<sub>2</sub> observations over Guangzhou, China; ground-based and satellite comparisons

2017 ◽  
Author(s):  
Theano Drosoglou ◽  
Maria Elissavet Koukouli ◽  
Natalia Kouremeti ◽  
Alkiviadis F. Bais ◽  
Irene Zyrichidou ◽  
...  
Keyword(s):  
Time Window ◽  
Correlation Coefficients ◽  
Urban Site ◽  
Reference Case ◽  
Vertical Column ◽  
Tropospheric No2 ◽  
Vertical Column Density ◽  
Satellite Sensors ◽  
D 20 ◽  
One Year

Abstract. In this study, the tropospheric NO2 vertical column density (VCD) over an urban site in Guangzhou megacity in China is investigated, by means of MAX-DOAS measurements during a campaign from late March 2015 to mid-March 2016. A MAX-DOAS system was deployed at the Guangzhou Institute of Geochemistry of the Chinese Academy of Sciences and operated there for about one year, during the spring and summer months. The tropospheric NO2 VCDs retrieved by the MAX-DOAS are presented and compared with space-borne observations from GOME-2/MetOp-A, GOME-2/MetOp-B and OMI/Aura satellite sensors. The comparisons reveal good agreement between satellite and MAX-DOAS observations over Guangzhou, with correlation coefficients ranging between 0.76 for GOME-2B and 0.99 for GOME-2A. However, the tropospheric NO2 loadings are underestimated by the satellite sensors on average by 25.1 %, 10.3 % and 5.7 %, respectively for OMI, GOME-2A and GOME-2B. Our results indicate that GOME-2B retrievals are closer to those of the MAX-DOAS instrument due to the lower tropospheric NO2 concentrations during the days with valid GOME-2B observations. In addition, the effect of the main coincidence criteria is investigated, namely the cloud fraction (CF), the distance (d) between the satellite pixel center and the ground-based measurement site, as well as the time period within which the MAX-DOAS data are averaged around the satellite overpass time. The effect of CF and time window criteria is more profound on the selection of OMI overpass data, probably due to its smaller pixel size. The available data pairs are reduced to half and about one third for CF ≤ 0.3 and CF ≤ 0.2, respectively, while, compared to larger CF thresholds, the correlation coefficient is improved to 0.99 from about 0.6, the slope value is almost doubled (~ 0.8) and the mean satellite underestimation is reduced to about half (from ~ 7 to ~ 3.5 × 1015 molecules/cm2). On the other hand, the distance criterion affects mostly GOME-2B data selection, because GOME-2B pixels are quite evenly distributed among the different radii used in the sensitivity test. More specifically, the number of collocations is notably reduced when stricter radius limits are applied, the r value is improved from 0.76 (d ≤ 50 km) to 0.93 (d ≤ 20 km), and the absolute mean bias decreases about 6 times for d ≤ 30 km compared to the reference case (d ≤ 50 km).

Tsunami Bore Impingement onto a Vertical Column

2009 ◽  
Vol 4 (6) ◽  
pp. 391-403 ◽  
Author(s):  
Halldor Arnason ◽  
◽  
Catherine Petroff ◽  
Harry Yeh ◽  
◽  
...  
Keyword(s):  
Cross Sections ◽  
Water Surface ◽  
Numerical Models ◽  
Laboratory Data ◽  
Flow Fields ◽  
Laser Doppler Velocimeter ◽  
Vertical Column ◽  
Image Velocimetry ◽  
Velocity Flow ◽  
Temporal And Spatial

In a laboratory wave tank, bores were generated by dam-break: by lifting a gate that initially separated quiescent shallow water from a volume of impounded water. The study was motivated by the problem of tsunami-structure interaction and sought to further the understanding of interactions between the bore-like flow of a broken tsunami wave and structures of different cross sections. Experiments were designed to observe the structure’s effect on the bore as well as the bore’s effect on the structure. This comprehensive study used highly repeatable experiments to measure water-surface variations, velocity flow fields, and forces exerted by bores on vertically erected columns. The temporal and spatial variations of the water-surface elevations were quantified with a Laser-Induced Fluorescence (LIF) technique; velocity flow fields were recorded with a combination of Laser Doppler Velocimeter (LDV) and Digital Particle Image Velocimetry (DPIV); forces on the columns were measured with a miniature load-cell transducer. The laboratory data obtained in the study are available for validating numerical models that predict forces on structures in unsteady flows.

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