scholarly journals Study on Distribution of Wellbore Temperature in Gas Drilling with Gradient Equations

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Zhongxi Zhu ◽  
Chaofei Wang ◽  
Zhigang Guan ◽  
Wanneng Lei
Keyword(s):  
Temperature Distribution ◽  
Gradient Method ◽  
Gas Flow ◽  
Temperature Drop ◽  
Geothermal Gradient ◽  
Cooling Effect ◽  
Formation Temperature ◽  
Gas Temperature ◽  
Local Cooling ◽  
Gas Drilling

Precise calculation of gas temperature profile is the key to gas drilling design. It is traditionally assumed that the gas temperature distribution in the wellbore is equal to the formation temperature, without considering the influence of fluid flow and Joule-Thomson cooling effect. This paper puts forward a gradient equation method for gas temperature distribution in wellbore considering gas flow and Joule-Thomson local cooling of the bit. The method applies pressure, temperature, density, and velocity equations to gas flow in drillstrings and annulus. The solution of the gradient equation is in the form of the fourth-order Runge-Kutta equation. Bottom wellbore temperatures measured at depths of 700 to 2000 m in an actual well are consistent with those predicted by the gradient method. Due to the Joule-Thomson cooling effect at the bit nozzle, the temperature drops by about 30°C. The sensitivity analysis is carried out by gradient method, and the results show that the temperature drop range of different nozzle sizes can reach 60°C due to the Joule-Thomson cooling effect. Stable temperature curves can be established within a few minutes of the gas cycle. Due to the influence of gas flow and Joule-Thomson cooling, the gas temperature in the wellbore deviates significantly from the geothermal temperature in the formation under the flow condition. The temperature of the gas in drillstrings increases as the drill depth increases and then decreases rapidly near the bottom of the hole. As the gas flows upward along the annulus, the gas temperature rises first, surpasses the formation temperature, and then decreases gradually along the geothermal gradient trend.

Numerical Simulation of Flow and Thermal Behavior of Radiating Gas Flow in Plane Solar Heaters

2019 ◽  
Vol 12 (3) ◽  
Author(s):  
Mohammad Foruzan Nia ◽  
Seyyed Abdolreza Gandjalikhan Nassab ◽  
Amir Babak Ansari
Keyword(s):  
Numerical Simulation ◽  
Temperature Distribution ◽  
Thermal Efficiency ◽  
Gas Flow ◽  
Simple Algorithm ◽  
Outlet Section ◽  
Gas Temperature ◽  
Conservation Of Energy ◽  
Solid Media ◽  
Solar Heater

Abstract In this paper, the radiating effect of working gas on thermal performance of plane solar heaters is investigated. In the numerical simulation of gas flow, the continuity and momentum equations are solved using the finite volume method (FVM) in which the pressure–velocity coupling is handled by the SIMPLE algorithm. To obtain the temperature distribution, the conservation of energy in the fluid and solid media is solved by the finite difference technique. The distribution of radiating intensity which is needed to calculate the radiative term in the gas energy equation is computed by numerical solution of the radiative transfer equation (RTE) using the discrete ordinate method (DOM). The effect of the variation of different parameters on the predicted thermal efficiency of plane solar heater is investigated by presenting the performance plot. The obtained results show that when the gas medium participates in radiation, the gas temperature at the outlet section increases considerably, especially at high optical thicknesses. Also, the temperature difference between the absorber plate and flowing gas decreases, and more uniform temperature distribution takes place inside the solar heater, which leads to a considerable increase in thermal efficiency. Comparison between the present numerical results and the experimental data published in literature shows good agreement.

scholarly journals Dependence of the separative power of an optimised Iguassu gas centrifuge on the velocity of rotor

2017 ◽  
Vol 27 (7) ◽  
pp. 1387-1394 ◽  
Author(s):  
Sergey Vladimirovich Bogovalov ◽  
Vladimir Dmitrievich Borman ◽  
Valentin Dmitrievich Borisevich ◽  
Vladimir Nikolaevich Tronin ◽  
Ivan Vladimirovich Tronin
Keyword(s):  
Computer Simulation ◽  
Angular Momentum ◽  
Binary Mixture ◽  
Power Law ◽  
Gas Flow ◽  
Temperature Drop ◽  
Uranium Isotopes ◽  
Gas Temperature ◽  
Content Type ◽  
Gas Centrifuge

Purpose The purpose of this work is to determine dependence of the separative power of the Iguassu gas centrifuge (GC) on the velocity of the rotor. Design/methodology/approach The dependence is determined by means of computer simulation of the gas flow in the GC and numerical solution of the diffusion equation for the light component of the binary mixture of uranium isotopes. 2D axisymmetric model with the sources/sinks of the mass, angular momentum and energy reproducing the scoops was explored for the computer simulation. Parameters of the model correspond to the parameters of the so-called Iguassu centrifuge. The separative power has been optimised in relation to the pressure of the gas, temperature of the gas, the temperature drop along the rotor, power of the source of angular momentum and energy, feed flow and geometry of the lower baffle. Findings In the result, the optimised separative power depends only on the velocity, length and diameter of the rotor. The dependence on the velocity is described by the power law function with the power law index 2.6 which demonstrate stronger dependence on the velocity than it follows from experimental data. However, the separative power obtained with limitation on the pressure growth with the velocity depends on the velocity on the power ∼ 2 which well agree with the experiments. Originality/value For the first time, the optimised separative power of the GCs have been calculated via numerical simulation of the gas flow and diffusion of the binary mixture of isotope.

Study on Effective Radial Thermal Conductivity of Gas Flow through a Methanol Reactor

2015 ◽  
Vol 13 (1) ◽  
pp. 103-112 ◽  
Author(s):  
Kun Lei ◽  
Hongfang Ma ◽  
Haitao Zhang ◽  
Weiyong Ying ◽  
Dingye Fang
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Reynolds Number ◽  
Temperature Distribution ◽  
Large Scale ◽  
Gas Flow ◽  
Fixed Bed ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Particle Reynolds Number

Abstract The heat conduction performance of the methanol synthesis reactor is significant for the development of large-scale methanol production. The present work has measured the temperature distribution in the fixed bed at air volumetric flow rate 2.4–7 m3 · h−1, inlet air temperature 160–200°C and heating tube temperature 210–270°C. The effective radial thermal conductivity and effective wall heat transfer coefficient were derived based on the steady-state measurements and the two-dimensional heat transfer model. A correlation was proposed based on the experimental data, which related well the Nusselt number and the effective radial thermal conductivity to the particle Reynolds number ranging from 59.2 to 175.8. The heat transfer model combined with the correlation was used to calculate the temperature profiles. A comparison with the predicated temperature and the measurements was illustrated and the results showed that the predication agreed very well with the experimental results. All the absolute values of the relative errors were less than 10%, and the model was verified by experiments. Comparing the correlations of both this work with previously published showed that there are considerable discrepancies among them due to different experimental conditions. The influence of the particle Reynolds number on the temperature distribution inside the bed was also discussed and it was shown that improving particle Reynolds number contributed to enhance heat transfer in the fixed bed.

scholarly journals Catalytic Micro Gas Sensor with Excellent Homogeneous Temperature Distribution and Low Power Consumption for Long-Term Stable Operation

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 927 ◽  
Author(s):  
Anmona Shabnam Pranti ◽  
Daniel Loof ◽  
Sebastian Kunz ◽  
Marcus Bäumer ◽  
Walter Lang
Keyword(s):  
Temperature Distribution ◽  
Low Power ◽  
Gas Sensor ◽  
Gas Flow ◽  
Pt Nanoparticles ◽  
Stable Operation ◽  
Catalytic Layer ◽  
Micro Gas Sensor ◽  
Homogeneous Temperature

This paper presents a long-term stable thermoelectric micro gas sensor with ligand linked Pt nanoparticles as catalyst. The sensor design gives an excellent homogeneous temperature distribution over the catalytic layer, an important factor for long-term stability. The sensor consumes very low power, 18 mW at 100 °C heater temperature. Another thermoresistive sensor is also fabricated with same material for comparative analysis. The thermoelectric sensor gives better temperature homogeneity and consumes 23% less power than thermoresistive sensor for same average temperature on the membrane. The sensor shows linear characteristics with temperature change and has significantly high Seebeck coefficient of 6.5 mV/K. The output of the sensor remains completely constant under 15,000 ppm continuous H2 gas flow for 24 h. No degradation of sensor signal for 24 h indicates no deactivation of catalytic layer over the time. The sensor is tested with 3 different amount of catalyst at 2 different operating temperatures under 6000 ppm and 15,000 ppm continuous H2 gas flow for 4 h. Sensor output is completely stable for 3 different amount of catalyst.

scholarly journals A Method for Determining the Main Requirements of Outlet Gas Temperature Profile of Marine Gas Turbine Combustors

1982 ◽  
Author(s):  
Tang Chian-ti
Keyword(s):  
Temperature Distribution ◽  
Temperature Profile ◽  
Gas Turbine ◽  
Guide Vane ◽  
Safety Margin ◽  
Gas Temperature ◽  
Distribution Factor ◽  
Radial Temperature ◽  
Blade Height ◽  
Blade Cooling

Taking account of the marine gas turbine operation features, the author has chosen the hot corrosion peak temperature of materials as the guide vane material limiting temperature while evaluating the overall temperature distribution factor. Along with the blade cooling effectiveness a safety margin factor has been introduced during its evaluation. The gas temperature distribution along blade height is assumed to satisfy the condition that approximately equal safety factor in respect of strength prevails along blade height. Once the gas radial temperature profile becomes known, the radial temperature distribution factor can be readily determined.

scholarly journals Analysis of the Effect of Anode Porosity on Temperature Distribution on Planar Radial Type SOFC

2018 ◽  
Vol 73 ◽  
pp. 01010
Author(s):  
Alif Widiyanto ◽  
Sulistyo ◽  
MSK Tony Suryo Utomo
Keyword(s):  
Temperature Distribution ◽  
Gas Flow ◽  
Hydrogen Gas ◽  
Cfd Modeling ◽  
Dynamics Modeling ◽  
Waste Products ◽  
Geometry Model ◽  
Electrolyte Surface ◽  
Fluent Software ◽  
Object Of Study

Solid Oxide Fuel Cell (SOFC) is an electrochemical equipment that converts gas into electricity directly. The waste products resulting from SOFC are water vapor and heat when using hydrogen gas. The electrode of the SOFC is the anode, electrolyte and cathode. The performance of SOFC is influenced porosity of the electrode. This study explained the relationship between porosity of the anode and temperature distribution using computational fluid dynamics modeling approach (CFD). In this study, CFD modeling was done by using Fluent software. The geometry model of computational modeling is a planar radial-type SOFC. The assumptions of some boundary conditions used from the study of literature and the object of study. The standard deviation and the different of temperature of the anode-electrolyte surface used to analyse the result. Non-homogenous temperature distribution rise if the anode porosity and gas flow rate is increasing. This indicates the gradient of temperature is bigger in the higher porosity, which may cause thermal stress and degrades the materials of electrode.

scholarly journals CFD Simulation Research on Agglomeration between Coal-fired Ash Fine Particulate and Atomized Droplets

2020 ◽  
Vol 165 ◽  
pp. 01006
Author(s):  
Yiquan Guo ◽  
Junying Zhang
Keyword(s):  
Power Plant ◽  
Flow Field ◽  
Cfd Simulation ◽  
Negative Impact ◽  
Droplet Diameter ◽  
Temperature Drop ◽  
Operating Conditions ◽  
Gas Temperature ◽  
Simulation Research ◽  
Agglomeration Process

In this paper, a collision model between atomized droplets of agglomeration solution and particles is established. On this basis, the effects of flue gas temperature, atomized droplet diameter and other factors on the particle agglomeration process are studied. In addition, the evaporation model of agglomeration solution in the flue of a power plant is established for the coal-fired unit of power plant. Through CFD software, the variation of flow field velocity, temperature and pressure in the flue is simulated to determine whether the chemical agglomeration technology has negative impact on the actual operating conditions of the power plant. The simulation results show that the velocity and pressure of the flow field in the flue have no obvious change after the agglomerating agent is injected. Besides, the temperature drop of about 7°C. The droplets evaporate completely at a distance of 7-8 m after spraying. The evaporation time of droplets is within 1.6 s.

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