A Numerical Study On Thermal Characteristics of HALE UAV Solar Arrays

A numerical study is made of the thermal characteristics of semitransparent materials exposed to simultaneous conduction and radiation between concentric cylinders. For extremely high-temperature applications, where radiative transfer plays an important role, ceramic-matrix composites, considered as semitransparent materials, are being explored for potential use in turbine and compressor components, spacecraft structures, engine control systems and nuclear reactors. Through the use of a gray model and the two-flux method, specialized equations are developed that generate a system of nonlinear ordinary differential equations. To facilitate the solution of this system, an iterative strategy is adopted. In order to demonstrate the versatility and accuracy of the proposed methodology, the results of several numerical experiments are presented and compared with benchmark solutions.

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Numerical Investigation of a two-inlet PVT air collector

E3S Web of Conferences ◽

10.1051/e3sconf/201913605014 ◽

2019 ◽

Vol 136 ◽

pp. 05014

Author(s):

Zhangyang Kang ◽

Zhaoyang Lu ◽

Xin Deng ◽

Qiongqiong Yao

Keyword(s):

Heat Transfer ◽

Single Channel ◽

Numerical Study ◽

Convection Heat Transfer ◽

Thermal Characteristics ◽

Area Ratio ◽

Cross Sectional Area ◽

Sectional Area ◽

Cross Sectional ◽

Maximum Heat

A numerical study of heat and mass transfer characteristics of a two-inlet PV/T air collector is performed. The influence of thermal characteristics and efficiency is investigated as the area ratios of inlet and outlet of the single channel with two inlets are changed. The design of the two-inlet PV/T air collector can avoid the poor heat transfer conditions of the single inlet PV/T air collector and improve the total photo-thermal efficiency. When the inlet/outlet cross-sectional area ratio is reduced, the inlet air from the second inlet enhances the convection heat transfer in the second duct and the temperature distribution is more uniform. As the cross-sectional area of the second inlet increase, the maximum heat exchange amount of the two-inlet PV/T air collector occurs between the inlet and outlet cross-sectional area ratio L=0.645 and L=0.562.

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Numerical study on the thermal characteristics and its influence factors of crude oil pipeline after restart

Case Studies in Thermal Engineering ◽

10.1016/j.csite.2019.100455 ◽

2019 ◽

Vol 14 ◽

pp. 100455 ◽

Cited By ~ 1

Author(s):

Hang Dong ◽

Jian Zhao ◽

Weiqiang Zhao ◽

Minglin Si ◽

Junyang Liu

Keyword(s):

Crude Oil ◽

Numerical Study ◽

Influence Factors ◽

Thermal Characteristics ◽

Oil Pipeline

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Numerical study of thermal characteristics of double skin facade system with middle shade

Frontiers in Energy ◽

10.1007/s11708-017-0480-8 ◽

2017 ◽

Author(s):

Shaoning Liu ◽

Xiangfei Kong ◽

Hua Yang ◽

Minchao Fan ◽

Xin Zhan

Keyword(s):

Numerical Study ◽

Thermal Characteristics ◽

Double Skin

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Numerical studies of a thermokinetic model for oscillatory cool flame and complex ignition phenomena in ethanal oxidation under well-stirred flowing conditions

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1989.0029 ◽

1989 ◽

Vol 422 (1863) ◽

pp. 289-310 ◽

Cited By ~ 12

Keyword(s):

Numerical Study ◽

Thermal Characteristics ◽

Kinetic Scheme ◽

Ambient Conditions ◽

Two Stage ◽

Experimental Conditions ◽

Cool Flame ◽

Cool Flames ◽

Spatial Uniformity ◽

Acetyl Radical

A numerical study has been undertaken to predict quantitatively each of the non-isothermal reaction modes (stationary-state reaction, oscillatory cool flames and oscillatory two-stage and multiple-stage ignitions) associated with the oxidation of ethanal in a non-adiabatic well-stirred flow system (0.5 dm 3 ) at a mean residence time of 3 s. The kinetic scheme comprises 28 species involved in 60 reactions and it is coupled to the thermal characteristics through enthalpy change in each step, heat capacities of the major components and a heat transfer coefficient appropriate to heat loss through the reaction vessel wall. Spatial uniformity of temperature and concentrations is assumed, matching the experimental conditions. Very satisfactory accord is obtained between the experimentally measured and predicted location of the different reaction modes in the ( p - T a ) ignition diagram (where p is pressure and T a is temperature at ambient conditions), and the time-dependent patterns for oscillatory reaction agree with experimental measurements. The competition between degenerate branching and non-branching reaction modes is governed ultimately by the equilibrium CH 3 +O 2 ⇌CH 3 O 2 . The predicted behaviour is found also to be especially sensitive to the rate of decomposition of the acetyl radical CH 3 CO + M → CH 3 + CO + M. Corrections for its pressure dependence are essential if the predicted form of the oscillatory cool flame region in the ( p - T a ) diagram is to match the experimental results. Variations of the rate of this reaction also give new kinetic insight into the origins of complex oscillatory wave-forms for cool flames that have been observed experimentally. Relationships between the results of the detailed kinetic computations and the predictions from a three-variable, thermokinetic model are examined. This model is the simplest of all reduced schemes that makes successful predictions of two-stage ignition phenomena.

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Multiple-relaxation-time Lattice Boltzmann model for flow and convective heat transfer in lid driven cavity with porous obstacle

MATEC Web of Conferences ◽

10.1051/matecconf/202033001007 ◽

2020 ◽

Vol 330 ◽

pp. 01007

Author(s):

Abderrahmane Bourada ◽

Asma Ouahouah ◽

Kaoutar Bouarnouna ◽

Karim Ragui ◽

Abdelkader Boutra ◽

...

Keyword(s):

Relaxation Time ◽

Lattice Boltzmann ◽

Numerical Study ◽

Thermal Characteristics ◽

Darcy Number ◽

Considerable Effect ◽

Lattice Boltzmann Model ◽

Driven Cavity ◽

Multiple Relaxation Time ◽

Porous Obstacle

In this work, we study numerically a problem of mixed convection in lid driven square cavity, filled with air (Pr = 0.71), whose upper wall is movable and kept at constant cold temperature TC. The cavity contains a porous obstacle of height h and width b, placed on the bottom wall maintained at a constant hot temperature TH. The side walls are adiabatic. Darcy-Brinkmann-forchheimer model is used for modelling the momentum equations in porous medium. This numerical study is based on the multiple relaxation time lattice Boltzmann method (MRT -LBM). The D2Q9 two-dimensional model is adopted to the dynamic part, while the D2Q5 model is applied for the thermal part. The objective of the study is to analyze the effect of Darcy number (10-1 ≼ Da ≼ 10-5), Richardson number (0.01 ≼ Ri ≼ 100) and the aspect ratio w = b/H (0.2 ≼ w ≼ 1) on the hydrodynamic and thermal characteristics in the cavity through the velocity and temperature as well as the average Nusselt number. The results obtained show a considerable effect of these parameters on the structure of the flow and on the heat exchange in the cavity.

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Methods for estimate the dynamic and thermal characteristics of smoke plumes

10.25743/sdm.2021.53.21.065 ◽

2021 ◽

Author(s):

V.F. Raputa ◽

A.A. Lezhenin

Keyword(s):

Power Plant ◽

Numerical Study ◽

Thermal Characteristics ◽

Physical Characteristics ◽

Observation Data ◽

Meteorological Observation ◽

Industrial Enterprises ◽

Atmospheric Stratification ◽

Smoke Plumes ◽

Estimation Models

Space observations of the propagation of smoke flares from the chimneys of industrial enterprises provide information on the physical characteristics of the emitted gas-air mixtures. Models for estimating the parameters of the rise of impurities under the influence of dynamic and thermal factors are proposed. The basic relations in the estimation models are the solutions of the equations of hydrothermodynamics of the atmosphere. The case of neutral atmospheric stratification is considered in detail. Using satellite information and meteorological observation data, a numerical study of the stage of ascent of smoke jets from the chimneys of the Gusinoozerskaya State District Power Plant was carried out.

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