Modeling of the nitrous oxide synthesis in a microchannel reactor: the effect of parameters on the temperature regimes and output

2021 ◽  
Vol 1 (1-2) ◽  
pp. 74-85
Author(s):  
A. S. Ignatov ◽  
N. V. Vernikovskaya ◽  
V. A. Chumachenko ◽  
A. S. Noskov
Keyword(s):  
Nitrous Oxide ◽  
Tubular Reactor ◽  
Outer Edge ◽  
Maximum Temperature ◽  
Maximum Output ◽  
Microchannel Reactor ◽  
Temperature Regimes ◽  
Radial Heat ◽  
Mixture Volume ◽  
Metal Disk

The study deals with the synthesis of nitrous oxide via selective oxidation of ammonia in a microreactor (MCR), which is a metal disk with cylindrical channels filled with the manganese-bismuth oxide catalyst. The proposed 3D mathematical model of MCR takes into account axial and radial heat and mass transfer, catalytic reactions and related changes of the reaction mixture volume, heat exchange between the disk and channels, and thermal conductivity of the disk. Parameters providing the maximum output of nitrous oxide were determined with allowance for restrictions on the temperature in MCR channels. The highest efficiency of the nitrous oxide synthesis is achieved at a temperature of the outer edge of reactor 370 °С and an inlet concentration of ammonia 20 vol.%. The output per unit catalyst volume in MCR is approximately 1.5 times higher as compared to a tubular reactor; the maximum temperature corresponds to the optimal one, which provides the best selectivity of the process with respect to nitrous oxide.

Modeling the Synthesis of Nitrous Oxide in a Microchannel Reactor: Effect of Parameters on Temperature Regimes and Capacity

2021 ◽  
Vol 13 (3) ◽  
pp. 269-279
Author(s):  
A. S. Ignatov ◽  
N. V. Vernikovskaya ◽  
V. A. Chumachenko ◽  
A. S. Noskov
Keyword(s):  
Nitrous Oxide ◽  
Microchannel Reactor ◽  
Temperature Regimes

scholarly journals Evaluating temperature thresholds and optimizing sowing dates of wheat in Bihar

2021 ◽  
Vol 22 (2) ◽  
pp. 158-164
Author(s):  
ABDUS SATTAR ◽  
GULAB SINGH ◽  
SHRUTI V. SINGH ◽  
MAHESH KUMAR ◽  
P. VIJAYA KUMAR ◽  
...  
Keyword(s):  
Grain Yield ◽  
Time Management ◽  
Climate Scenario ◽  
Significant Negative Correlation ◽  
Adaptation Strategy ◽  
Maximum Temperature ◽  
Maturity Stage ◽  
Gangetic Plains ◽  
Temperature Regimes ◽  
Sowing Dates

Studies on wheat-weather relationship were carried out at Pusa (25.98 oN, 85.67 oE, 52 m), Bihar situated in middle Gangetic plains of India, with three popular wheat cultivars viz. RW 3711, HD 2824 and HD273, grown under five fixed dates of sowing viz. 15 November, 25 November, 5 December, 15 December and 25 December, for five consecutive rabi seasons from 2011-12 to 2015-16. Thresholds of maximum temperature (Tmax), minimum temperature (Tmin) and bright sunshine hours (BSH), associated with higher productivity, occurring at different phenophases, were determined. Results revealed that temperature played a crucial role in achieving higher grain yield of wheat. Both Tmax and Tmin during flowering to milking and flowering to maturity phases increased with delayed sowing dates beyond 25 November with consequent reductions in grain yield. During 50 % flowering to milk stage, Tmax and Tmin above 24.6 oC and 11.6 oC, respectively, reduced grain yield below 4000 kg ha-1; significant reduction in grain yield was also noted beyond maximum temperature of 26.9 oC. During flowering to milk and flowering to maturity phases, Tmax and Tmin exhibited highly significant negative correlation with grain yield, indicating higher temperatures causing lower grain yield. With delayed sowing, sensitive phases of the crop experienced higher air temperatures which led to reduction in grain yield. An increase of Tmax from 29.2 to 32.1 oC during flowering to maturity phases reduced the wheat productivity drastically in this region of Indo-Gangetic plains. Grain yield declined by 399 kg ha-1 per 1 oC rise in Tmax during 50 % flowering to maturity stage. Considering grain yield vis-à-vis temperature regimes during flowering to maturity stage, the most important recommendation for the farmers of the region would be to finish wheat sowing before 25 November in order to enable them to escape terminal heat stress in wheat and thereby realizing higher grain yield. The anthesis-time management by manipulating sowing dates could be a realistic adaptation strategy for attaining optimum grain yield under changing climate scenario.

Soil nutrition and temperature as drivers of root suckering in trembling aspen

2002 ◽  
Vol 32 (9) ◽  
pp. 1685-1691 ◽  
Author(s):  
Erin C Fraser ◽  
Victor J Lieffers ◽  
Simon M Landhäusser ◽  
Brent R Frey
Keyword(s):  
Populus Tremuloides ◽  
Root Surface ◽  
Maximum Temperature ◽  
Daily Maximum Temperature ◽  
Root Surface Area ◽  
Daily Maximum ◽  
Base Temperature ◽  
Trembling Aspen ◽  
Degree Days ◽  
Temperature Regimes

In two separate studies, the suckering of trembling aspen (Populus tremuloides Michx.) roots was assessed in response to different daily maximum soil temperatures and in relation to available nutrients (CaSO4 and NH4NO3). In the first study, aspen root sections were incubated under high:low temperature regimes of 12:8, 14:8, 16:8, 18:8, or 20:8°C until 124 degree-days above 8°C had been reached. Daily maximum temperature did not affect the number of suckers produced per square centimetre of root surface area or per root section. However, more time was required to initiate suckers on root sections grown under the 12:8°C temperature regime compared with those grown at 20:8°C. Furthermore, when calculated from a base temperature of 5°C, the number of degree-days needed to initiate aspen suckers was not different across the temperature regimes. In the second study, CaSO4, NH4NO3, or distilled water was added to aspen root sections. While nutrients did not affect the number of suckers produced, the addition of CaSO4 or NH4NO3 significantly increased sucker dry mass. Nutrient addition appeared to stimulate sucker growth and mobilization of stored reserves to support this growth.

scholarly journals Analysis of thermal dependence on the germination of braquiarão seeds using the thermal time model

2016 ◽  
Vol 76 (1) ◽  
pp. 162-168 ◽  
Author(s):  
E. A. Nakao ◽  
V. J. M. Cardoso
Keyword(s):  
Thermal Fluctuations ◽  
Thermal Time ◽  
Maximum Temperature ◽  
Model Parameters ◽  
Thermal Dependence ◽  
Time Model ◽  
Temperature Regimes ◽  
Wide Range ◽  
Urochloa Brizantha ◽  
Thermal Time Model

Abstract This paper analyzed the thermal dependence on the germination of Urochloa brizantha (Stapf) Webster seeds under constant and fluctuating temperatures through the thermal time model. Germination tests were carried out at constant temperatures ranging from 8 °C to 41.5 °C in order to determine the model parameters: base (Tb), optimal (To) and maximum temperature (Tc) for germination; and the thermal time (θT) required for individual seeds to germinate. Braquiarão seeds germinate within a temperature interval from 8 °C to 41.5 °C, with an optimum range for germination estimated at 31.5 ° ≤ T ≤ 34.5 °C. Actual and expected distributions of cumulative germination percentages of U. brizantha seeds put to germinate both under controlled and uncontrolled temperature regimes were compared, and it can be seen that the model described relatively well the germination at isothermal assays; however the model failed to predict germination at a wide range of thermal fluctuations. Possible explanations for the results are discussed.

Effect of Peak Temperature Limitations on the Design of Processes with Cooled Tubular Reactors

2014 ◽  
Vol 12 (1) ◽  
pp. 191-203
Author(s):  
William L. Luyben
Keyword(s):  
Catalyst Deactivation ◽  
Tubular Reactor ◽  
Peak Temperature ◽  
Tube Length ◽  
Maximum Temperature ◽  
Coolant Temperature ◽  
Operating Variables ◽  
In Series ◽  
Temperature Limitation ◽  
The Impact

Abstract Maximum temperature limitations are usually encountered in exothermic catalytic reaction systems due to catalyst deactivation. Therefore, the peak temperature in a cooled tubular reactor can be constrained to some maximum limit. The peak temperature is a function of many design and operating variables such as reactor volume and heat-transfer area (number of tubes, tube diameter and tube length), coolant temperature, inlet reactant concentration, per-pass conversion and reactant feed distribution. These variables affect the design of both the reactor and the separation section of the plant. This paper explores the impact of this peak temperature limitation on the economic design of the entire process. The numerical example used is the production of cumene from benzene and propylene. Results show that costs increase as the peak temperature limitation decreases. Use of two cooled reactors in series with the limiting reactant split between the reactors is more economical than a single reactor.

Finite Element Numerical Simulation of EDM Surface Strengthening in Gas Medium of Stainless Steel 1Cr13

2010 ◽  
Vol 136 ◽  
pp. 189-193
Author(s):  
H.X. Wang ◽  
X. Zhang ◽  
W.S. Zhang
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Temperature Gradient ◽  
Stress Test ◽  
Stress Gradient ◽  
Single Pulse ◽  
Outer Edge ◽  
Spark Discharge ◽  
Maximum Temperature ◽  
Initial Moment

In this paper, the finite element simulation model of the electrode melting drops coating process on the workpiece was established, and the numerical simulation of the the temperature field and thermal stress field of the single-pulse electric spark discharge strengthening region was carried out. The results indicated that, in the initial moment of spark discharge, the heat-affected region was small, but the temperature gradient and the maximum temperature were very big. With time increased, heat-affected region kept growing, while the temperature gradient and the maximum temperature both kept decreasing. The extrusion stress mainly concentrated in the region of the outer edge of the combination area of the coating point and the workpiece, and the region of the coating point surface. The tensile stress mainly concentrated in the region of the combination area of the coating point and the workpiece. As time increased, both maximum stress and stress gradient kept growing. The results showed that the experimental data by X-ray stress test had good agreement with the simulation results.

scholarly journals Summer temperature regimes in southcentral Alaska streams: watershed drivers of variation and potential implications for Pacific salmon

2017 ◽  
Vol 74 (5) ◽  
pp. 702-715 ◽  
Author(s):  
Sue Mauger ◽  
Rebecca Shaftel ◽  
Jason C. Leppi ◽  
Daniel J. Rinella
Keyword(s):  
Air Temperature ◽  
Sublethal Effects ◽  
Pacific Salmon ◽  
Thermal Sensitivity ◽  
Open Water ◽  
Maximum Temperature ◽  
Temperature Regimes ◽  
Southcentral Alaska ◽  
Maximum Temperatures ◽  
Cook Inlet Basin

Climate is changing fastest in high-latitude regions, focusing our research on understanding rates and drivers of changing temperature regimes in southcentral Alaska streams and implications for salmon populations. We collected continuous water and air temperature data during open-water periods from 2008 to 2012 in 48 nonglacial salmon streams across the Cook Inlet basin spanning a range of watershed characteristics. The most important predictors of maximum temperatures, expressed as mean July temperature, maximum weekly average temperature, and maximum weekly maximum temperature (MWMT), were mean elevation and wetland cover, while thermal sensitivity (slope of the stream–air temperature relationship) was best explained by mean elevation and area. Although maximum stream temperatures varied widely between years and across sites (8.4 to 23.7 °C), MWMT at most sites exceeded established criterion for spawning and incubation (13 °C), above which chronic and sublethal effects become likely, every year of the study, which suggests salmon are already experiencing thermal stress. Projections of MWMT over the next ∼50 years suggest these criteria will be exceeded at more sites and by increasing margins.

Experimente zur Erhöhung der Lichtbogentemperatur durch Reduktion der Wärmeleitfähigkeit in einem Magnetfeld*

1964 ◽  
Vol 19 (10) ◽  
pp. 1202-1207 ◽  
Author(s):  
C. Mahn ◽  
H. Ringler ◽  
R. Wienecke ◽  
S. Witkowski ◽  
G. Zankl
Keyword(s):  
Magnetic Field ◽  
High Pressure ◽  
Heat Conduction ◽  
Power Input ◽  
Maximum Temperature ◽  
Arc Length ◽  
Field Parallel ◽  
Different Types ◽  
Radial Heat

Currently, in different types of high pressure arc the maximum temperature is limited by radial heat conduction. Heat conduction can be reduced by a magnetic field parallel to the axis of the arc. An experiment is described in which arc temperatures in the region of 105 °K have been reached. Typical conditions for the discharge in hydrogen are: current = 2000 amps, magnetic field = 10 kGauss, power input = 4 kW per cm arc length, pressure inside the arc = 0,1 atmosphere. - A similar experiment was made with helium.

OXIDATIVE TORREFACTION FOR PULVERIZED PALM BIOMASS USING AIR

2017 ◽  
Vol 79 (7-4) ◽  
Author(s):  
Mohamad Aiman Adnan ◽  
Muhammad Ariff Hanaffi Mohd Fuad ◽  
Mohd Faizal Hasan
Keyword(s):  
Weight Loss ◽  
Palm Kernel ◽  
Tubular Reactor ◽  
Industrial Sector ◽  
Volatile Matter ◽  
Inert Gas ◽  
Maximum Temperature ◽  
Empty Fruit Bunch ◽  
Palm Kernel Shell ◽  
Combustion Properties

Torrefaction is one of the promising ways to utilize abundant amount of empty fruit bunch (EFB) and palm kernel shell (PKS) while upgrading the combustion properties of both types of palm biomass. However, the supply of costly inert gas during torrefaction process such as nitrogen in large industrial sector may not be economical. Therefore, in the present study, air is used instead of nitrogen for the torrefaction process. The EFB and PKS were torrefied separately in a 60 mm diameter and 300 mm length of horizontal tubular reactor under various temperatures of 150°C to 190°C and 210°C to 250°C, respectively for 30 minutes using air. The torrefaction with nitrogen was also performed for comparison purpose. At the respective maximum temperature, energy yields of the torrefied EFB for the case of oxidative (air) torrefaction and nitrogen torrefaction are around 95% and 88%, respectively while energy yields of PKS for the case of oxidative(air) and nitrogen torrefaction are around 69% and 83%, respectively due to the weight loss after removal of volatile matter during torrefaction process. Besides that, the calorific values are enhanced after being torrefied with air (mere 4% for EFB and 18% for PKS when the respective maximum temperature was used).

Elevated Temperature Fatigue Life Investigation of Aluminium Alloy based on the Predicted S-N Curve

2013 ◽  
Vol 63 (1) ◽  
Author(s):  
K. A. Zakaria ◽  
S. Abdullah ◽  
M. J. Ghazali
Keyword(s):  
Fatigue Life ◽  
Elevated Temperature ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Fatigue Tests ◽  
Maximum Temperature ◽  
Stress Control ◽  
Temperature Regimes ◽  
Engine Mount ◽  
Load Sequence

This paper discusses a methodology used to predict the stress-life (S-N) curve at elevated temperatures based on the normal S-N curve. Fatigue tests were performed under stress control at room temperature in accordance with the ASTM E466 standard to obtain a normal S-N curve. In addition, the tests were performed at both room and elevated temperatures using constant-amplitude, high-to-low sequence, and low-to-high sequence loadings to investigate the effect of the load sequence at elevated temperatures on fatigue life. Three elevated temperature regimes at 70 to 250°C were chosen based on the maximum temperature of the engine mount bracket and the cylinder head that can be reached during normal service. The results show that the fatigue lives were significantly affected by the load sequences at both room and elevated temperatures. Furthermore, the existing fatigue data obtained at elevated temperatures can be used to predict the corresponding S-N curves. 

Sign in / Sign up

Export Citation Format

Share Document