Numerical analysis of natural convection in a prismatic enclosure

Aich, Walid; Hajri, Imen; Omri, Ahmed

doi:10.2298/tsci1102437a

Cited by 13 publications

(6 citation statements)

References 15 publications

(19 reference statements)

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“…In the study of Yejjer et al [16] concerning three-dimensional natural convection and entropy generation in an inclined solar collector equipped with partitions, results are reported in terms of isosurfaces of temperature, isotherms, particles trajectories, velocity vector projection, average Nusselt number along the absorber plate and entropies generation contours. Aich et al [17] made a numerical analysis of natural convection in parismatic enclosure that looks like a monochapel greenhouse; he found that heat transfer increases with increasing Rayleigh number and decreases with increasing aspect ratio.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Natural Convection With Heated Tubes in Tunnel Greenhouse

Slatni

Djezzar

Messai³

2021

Journal of Thermal Engineering

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In this research, a numerical study was carried out on heat transfer by natural convection, in a closed tunnel greenhouse, in the range of the Rayleigh number (10 3 ≤Ra≤10 6 ). Were considered in the study, the number of heating tubes used (1≤Nt≤7), which were equidistant inside the greenhouse volume, when the bottom at an average temperature and cold Roof. The governing equations written in a bicylindrical coordinates were discretized using the finite volume method and vorticity-stream function formulation; the resulting algebraic equations were solved using successive over relaxation method (S.O.R). First, the effect of the Rayleigh number on heat transfer was examined for a fixed number of tubes as reference (Nt = 3) and the number of tubes was varied to investigate the influence on heat transfer in the greenhouse. Finally, the results obtained were summarized in the form of isotherms and streamlines, and for the average Nusselt number profile; in addition to the horizontal and vertical velocities and temperatures. However, in the reference case, for low Rayleigh numbers, the heat transfer is dominated by pure conduction.With the increase of the Rayleigh number and the number of tubes Nt, the natural convection becomes more dominant and the heat transfer increases, and in general the heat transfer increase with the increasing number of tubes.

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Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Natural Convection With Heated Tubes in Tunnel Greenhouse

Slatni

Djezzar

Messai³

2021

Journal of Thermal Engineering

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“…Lo and Novoselac [15] pointed out that the position of the outlet opening at the leeward façade only has a small impact on the volume flow rate, however, they analyzed a position of the outlet opening that is at the same level as the inlet opening, which is not the case in the current study. Aich et al [16] carried out a 2-D numerical study of natural convection flows in a prismatic cavity. It has been found that a considerable proportion of the heat transfer across the inclined walls of the enclosure takes place near the intersection of the adiabatic vertical walls and cold inclined walls.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional computational fluid dynamics analysis of buoyancy-driven natural ventilation and entropy generation in a prismatic greenhouse

Aich¹,

Kolsi²,

Borjini³

et al. 2018

Therm sci

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A computational analysis of the natural ventilation process and entropy generation in 3-D prismatic greenhouse was performed using CFD. The aim of the study is to investigate how buoyancy forces influence air-flow and temperature patterns inside the greenhouse having lower level opening in its right heated façade and also upper level opening near the roof top in the opposite cooled façade. The bottom and all other walls are assumed to be perfect thermal insulators. Rayleigh number is the main parameter which changes from 10 3 to 10 6 and Prandtl number is fixed at Pr = 0.71. Results are reported in terms of particles trajectories, iso-surfaces of temperature, mean Nusselt number, and entropy generation. It has been found that the flow structure is sensitive to the value of Rayleigh number and that heat transfer increases with increasing this parameter. Also, it have been noticed that, using asymmetric opening positions improve the natural ventilation and facilitate the occurrence of buoyancy induced upward cross air-flow (low-level supply and upper-level extraction) inside the greenhouse.

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“…Studies of convective energy transfer regimes play an important role in science and engineering. Solutions of various natural convection problems in closed and semi-open cavities in non-conjugate [8][9][10][11][12][13][14] and conjugate [15][16][17][18] formulation are published. However, a special interest for practical applications represents investigation of jointly proceeding processes of conduction, convection, and radiation.…”

Section: Introductionmentioning

confidence: 99%

Modelling of the conjugate natural convection in a closed system with the radiant heating source radiant energy distribution by Lambert’s cosine law

Кузнецов

Nee

2018

THERM SCI

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Various types of emitters are often used as energy sources in real engineering systems and technological processes. Investigations of heat transfer basic laws in such systems are of interest. We conducted mathematical modelling of conjugate heat transfer in a closed rectangular cavity under conditions of radiant energy source operating. The 2-D problem of conjugate natural convection in vorticity stream function-temperature dimensionless variables has been numerically solved by means of the finite difference method. Radiant energy distribution along the gas-wall interfaces was set by Lamberts? cosine law. We obtained fields of temperature and stream functions in a wide range of governing parameters (Rayleigh number 104 ? Ra ? 106, the length of radiant heating source 0.15 ? D ? 0.6). Then we analyzed how heat retaining properties of finite thickness heat conducting walls made of different materials affect the heat transfer intensity. Differential characteristics distribution showed significant non-uniformity and non-stationarity of the conjugate heat transfer process under study.

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Numerical analysis of natural convection in a prismatic enclosure

Cited by 13 publications

References 15 publications

Numerical Investigation of Natural Convection With Heated Tubes in Tunnel Greenhouse

Numerical Investigation of Natural Convection With Heated Tubes in Tunnel Greenhouse

Three-dimensional computational fluid dynamics analysis of buoyancy-driven natural ventilation and entropy generation in a prismatic greenhouse

Modelling of the conjugate natural convection in a closed system with the radiant heating source radiant energy distribution by Lambert’s cosine law

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