A two-dimensional study on natural convection and heat transfer in the enclosure with heat transfer and radiation coupled in natural convection

Zhan, N.Y.; Yang, Mujie; Xu, PeiWei

doi:10.1007/s11431-009-0395-7

Cited by 4 publications

(5 citation statements)

References 29 publications

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“…Having compared the mean values of the Nusselt number obtained in the present work and in [18,19], we may conclude that they are in good agreement and, consequently, the solution method used for the above-formulated problem is reliable.…”

supporting

confidence: 62%

“…The one-dimensional difference analogs of the differential equations were solved by the marching method [15,17]. The used solution method was tested on the model problem of [18] (Table 1).…”

mentioning

confidence: 99%

“…The slight deviation (up to 3 K) of the temperature in the second variant is explained by the fact that the level of the radiant fl ux arriving at the surface of the vertical enclosure structures is much higher for the case of the radiant fl ux The main integral characteristic of the heat exchange under natural convection is customarily assumed to be the mean Nusselt number Nu [18,20]. At the enclosure-air interface with y = h1 and l1 < x < l4 the mean dimensionless heat transfer coeffi cient is defi ned [20] as Figures 10 and 11 present the dependences of Nu on the time and the Grashof number.…”

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confidence: 99%

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Computational Modeling of Conjugate Heat Transfer in a Closed Rectangular Domain Under the Conditions of Radiant Heat Supply to the Horizontal and Vertical Surfaces of Enclosure Structures

Кузнецов

Nagornova

2015

J Eng Phys Thermophy

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536.33:536.244 We have carried out computational modeling of nonstationary conductive-convective heat transfer in a closed rectangular domain in a conjugate formulation with a local heat source (a gas infrared radiator). Four variants of possible description of the radiant energy distribution over the inner surfaces of enclosures have been considered. As a result of the computational modeling, differential (temperature fi elds and stream functions) and integral (Nusselt numbers) heat transfer characteristics have been obtained. It has been shown that the radiant fl ux distribution infl uences the heat transfer intensity.Introduction. The steadily increasing energy consumption, the problems with operating NPPs, and the limited capacities of renewable energy sources make the use of energy-saving technologies more and more topical. The traditional convective heating of large-size industrial premises is at present ineffective in many cases. The use of gas infrared radiators (GIR) can make it possible to reduce the energy consumption, according to the authors of [1], by more than 30% due to by local heat supply to the working places.Investigations of radiant heating systems are carried out mainly with the aim of choosing optimal characteristics of the GIR [2-4]. The obtained experimental data [5,6] have shown that a microclimate favorable for personnel is attained in using GIRs at lower expenditures of fuel resources. It is not always possible to perform natural experiments under the conditions of large-size production shops with locally sitting operating equipment. In this case, it is expedient to use methods of mathematical modeling in choosing the basic parameters of GIR-based heating systems and test subsequently the results of the theoretical analysis under production conditions. It has been found [7,8] that mathematical modeling of the processes of conductive-convective heat transfer in a conjugate formulation in solving analogous problems creates conditions for a much more detailed analysis of the temperature regimes of investigated objects of heat supply. Mathematical models based on the thermal balance of a room [9] do not completely take into account the spatial character of the heat transfer typical in practice. The known solutions of heat transfer problems during operation of radiant heating systems [10,11] ignore the convection. The mathematical model of conductiveconvective nonstationary heat transfer under radiant heating of one of the internal boundaries of a closed rectangular domain in a conjugate formulation [12] was formulated under the assumption that the heat fl ux is distributed uniformly only over the horizontal surface of the lower base. It is interesting to analyze the thermal regimes of heated objects under radiant heating with account for the possible distribution of energy released by the GIR over the surfaces of vertical enclosure structures.The aim of the present work is to model computationally the nonstationary process of radiant heating of a rectangular domain in a conjugate formu...

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Computational Modeling of Conjugate Heat Transfer in a Closed Rectangular Domain Under the Conditions of Radiant Heat Supply to the Horizontal and Vertical Surfaces of Enclosure Structures

Кузнецов

Nagornova

2015

J Eng Phys Thermophy

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“…Several studies concern convection flows in transparent media bounded partially or totally by solid walls: 2D or 3D rectangular cavities [1e5], closed cavities with a circular or square obstruction inside [6e11 ], partitioned cavities with baffles [12e14], partially open cavities [15e17], vertical channels [18]. The coupling natural convection, conduction and surface thermal radiation has also been investigated in two [19,20] or three-dimensional rectangular cavities [21].…”

Section: Introductionmentioning

confidence: 99%

Non-Boussinesq convection in a square cavity with surface thermal radiation

Bouafia

Hamimid

Guellal

2015

International Journal of Thermal Sciences

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International audienceAbstract The interaction of natural convection with surface radiation in a differentially heated square cavity filled with air is considered under large temperature differences. The study has been investigated by direct numerical simulations with a two-dimensional finite volume numerical code solving the time-dependent Navier-Stokes equations under the Low Mach Number (LMN) approximation. Calculations were performed for cases with strong non-Boussinesq effects. The results reveal that the fluid flow and heat transfer are influenced significantly by the surface radiation. At steady state, the top wall is cooled and the bottom wall is heated compared to the case without radiation. The air flow is reinforced near the horizontal walls and the thermal stratification at the core is reduced. The surface radiation reduces the convection heat transfer at the hot wall and increases it on the cold wall.Transition from steady to unsteady flow has also been investigated. By comparing the solutions in pure convection, the results in combined convection-radiation show that the radiation promotes the occurrence of instabilities leading to an early transition to the unsteadiness and contributes to the modification of the physical mechanism responsible for their onset

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“…Yang et al [86] and Huang et al [87] studied the seepage-stress coupling with meso-mechanics approach and obtained some meaningful results. In [88][89][90][91][92], some approaches were proposed to handle the temperature-seepagestress coupling problem, and some progresses were obtained both for engineering practice and further research.…”

Section: The Damage Mechanism Of Dam Concrete and Foundation Rockmentioning

confidence: 99%

Research advance in failure risk and local strength failure for high arch dams

Ren

Liu

2012

Chin. Sci. Bull.

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To develop national economy and use the water resources and hydropower resources sufficiently, a lot of high arch dams, with the height of more than 200 m, have been and will be built in China. Although arch dams have good mechanical behavior, there is still failure possibility due to the huge water pressure and high stress level in dam, complex topographic and geologic conditions, formidable environment and high intensity earthquake. As one of the three main aspects concerning the safety of high arch dam, the study on global destruction, has been elaborated in the literatures, and research advance in the other two aspects, namely the failure risk and local damage of high arch dams, will be reviewed in this paper. In recent years, the failure risk of high arch dams has been investigated, and the model for identifying dam failure risk factors has been established. It is shown that the foundation deterioration and strong earthquake are the major risk sources for high dam failure. With the fault tree method, the failure mode and failure probability of high arch dams are studied, and the principle for determining failure mode and the method of calculating failure probability are proposed. Meanwhile, the determination principle of acceptable risk standard for high arch dam was proposed, and the acceptable risk rate and the acceptable standard value of various risk losses were given. For the local damage of arch dam, it is pointed out that the local damage belongs to the strength failure at material level. The study on local failure mechanism of arch dam is reviewed, based on the theories that from traditional strength theory to damage mechanics and meso-mechanics theory. Aiming at the cracking, the main pattern of local failure of high concrete dam, the research advances in the analysis methods and cracking criteria for smeared crack model and discrete crack model are summarized, and the research findings of preventive measures for local failure are shown. high arch dam, failure risk, local damage, research advance Citation:Ren Q W, Li Q, Liu S. Research advance in failure risk and local strength failure for high arch dams. Chin Sci Bull, 2012Bull, , 57: 46724682, doi: 10.1007 To develop national economy, to save energy and to reduce emission, exploitation and utilization of water resources and hydropower resources are continued in China. At present, the height of arch dams under construction and to be built are of 300 m high level, such as Jinping arch dam (305 m high), Xiaowan arch dam (294.5 m high), Xiluodu arch dam (285.5 m high), and Baihetan arch dam (289 m high). The construction scale and difficulty of these dams are beyond the current design specifications, and there is hardly successful precedential reference. Moreover most of these high arch dams are located in the western region of China, where the topographic and geologic conditions are quite complex, with harsh environment and high seismic intensity as well as frequent geological disasters. In addition the resistance of dam and foundation may be red...

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A two-dimensional study on natural convection and heat transfer in the enclosure with heat transfer and radiation coupled in natural convection

Cited by 4 publications

References 29 publications

Computational Modeling of Conjugate Heat Transfer in a Closed Rectangular Domain Under the Conditions of Radiant Heat Supply to the Horizontal and Vertical Surfaces of Enclosure Structures

Computational Modeling of Conjugate Heat Transfer in a Closed Rectangular Domain Under the Conditions of Radiant Heat Supply to the Horizontal and Vertical Surfaces of Enclosure Structures

Non-Boussinesq convection in a square cavity with surface thermal radiation

Research advance in failure risk and local strength failure for high arch dams

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