Two-dimension experimental study of the reverse flow in a free convection channel with active walls differentially heated

Dupont, Frédéric; Ternat, Fabien; Sandrine, Samot; Ruddy, Blonbou

doi:10.1016/j.expthermflusci.2013.01.010

Cited by 18 publications

(3 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The first hypothesis is to be rejected, as increasing the length of a chimney always increases its draught due to heat loss. It should also be noted that the second hypothesis is also to be rejected, as all numerical and experimental studies on heated channels have never mentioned the formation of a recirculation zone at the inlet [ 21 , 32 – 35 ]. In our opinion, the real reason for the poor performance of inlet extensions is the presence, in this zone, of fresh, dense air that cannot flow by buoyancy because it has not yet been heated.…”

Section: Resultsmentioning

confidence: 99%

Improved cooling of photovoltaic panels by natural convection flow in a channel with adiabatic extensions

Badi,

Laatar

2024

PLoS ONE

View full text Add to dashboard Cite

In hot dry regions, photovoltaic modules are exposed to excessive temperatures, which leads to a drop in performance and the risk of overheating. The present numerical study aims to evaluate the natural air cooling of PV modules by an inclined chimney mounted at the back. The basic equations were solved using the finite volume method. The validity of the model is verified by comparison with the data available in the literature. Thermal and dynamic flow patterns are analyzed for a variety of parameters: Rayleigh numbers from 102 to 106, PV panel tilt angle from 15° to 90°, and channel aspect ratios from 1/20 to 1/5. A critical aspect ratio has been determined to minimize overheating of the PV module. According to the computational results, the tilt angle and modified Rayleigh number increase the mass flow rate and mean Nusselt number. The overheating zone with maximum temperatures is located in the upper part of the photovoltaic panel. The addition of an extension to both channel’s inlet and outlet was found to improve the cooling of the photovoltaic panels; however, only the extensions downstream of the channel are truly effective. The critical lengths at which channel performance improves significantly were identified by examining the impact of longer extensions on channel performance. Increasing the extension length from 0 to 3H improves the mass flow rate by 65%, the average Nusselt number by 13.4%, and leads to an 11% decrease in maximum temperature when Ra* = 106. This cooling technique is particularly promising for hot dry regions where water is scarce.

show abstract

Section: Resultsmentioning

confidence: 99%

Improved cooling of photovoltaic panels by natural convection flow in a channel with adiabatic extensions

Badi,

Laatar

2024

PLoS ONE

View full text Add to dashboard Cite

show abstract

“…Moreover, the size of the vortex increases by considering surface radiation and setting a temperature to grey bodies surface. Observation of vortex at the exit of channel has been already made by [11] and [18]. So, thermal stratification produces a vortex-like structure at the top region of the channel.…”

Section: Impact On Dynamic Quantities and On Flow Fieldmentioning

confidence: 97%

Impact of External Surroundings on Natural Convection in a Vertical Channel Asymmetrically Heated

Ramalingom¹,

Bastide²

2016

Proceedings of the VII European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS Congress 2016)

View full text Add to dashboard Cite

Abstract. This paper reports a numerical study of natural convection problem between vertical plates with asymmetric heating. Influence of perturbation conditions outside of the channel on flow structure and on the heat transfer rate are investigated. The effect of temperature consists of considering a gradient of temperature between the bottom and top of the channel in order to obtain a thermal stratification. The effect of surface radiation on the laminar air flow with a thermal stratification is investigated by considering temperature of grey bodies. Results show that these weak perturbations outside the channel are a real influence on flow and that the influence of thermal stratification is more important than surface radiation. Numerical simulations have been carried out at modified Rayleigh number Ra=5.10 5 (laminar regime) and with Prandtl number Pr=0.71.

show abstract

“…In 2013, Dupont et al (2013) argued that the recirculation zones are related to the Rayleigh number and the aspect ratio. Recently, Cherif et al (2020) published numerical and experimental work describing natural free convection in asymmetrically heated building structures, such as Trombe walls or ventilated windows.…”

Section: Flow Structurementioning

confidence: 99%

Double-skin façade simulation with computational fluid dynamics: A review of simulation trends, validation methods and research gaps

Melgaard¹,

Nikolaisson²,

Zhang³

et al. 2023

Build. Simul.

View full text Add to dashboard Cite

Dynamic simulation of a double-skin façade (DSF) with computational fluid dynamics (CFD) can be challenging due to the lack of validated models and benchmarking datasets. Furthermore, there is a lack of consensus in the scientific community on what constitutes a successfully validated DSF model. The present review study identifies simulation trends and research gaps for DSFs simulated with CFD. Additionally, this article presents a series of CFD simulations in which key aspects of the DSF modelling are varied: 2D or 3D modelling approaches, turbulence viscosity models (TVMs), radiation models, and wall function. These simulation results are compared to the empirical data (both temperature and velocity fields) of a benchmark test with laboratory-controlled boundary conditions. This analysis shows that using the k-ε RNG model with enhanced wall treatment and surface-to-surface (S2S) radiation model yields the best results for the 2D case of natural convection flow. Moreover, it is shown that accounting for the velocity field in the validation process is essential to ensure the suitability of a model. Finally, the authors advocate for the use of selected dimensionless numbers to improve the comparability of the different DSF scientific studies. This would also help to identify relevant experimental datasets for validation and suitable CFD simulation settings for specific DSF cases.

show abstract

Two-dimension experimental study of the reverse flow in a free convection channel with active walls differentially heated

Cited by 18 publications

References 14 publications

Improved cooling of photovoltaic panels by natural convection flow in a channel with adiabatic extensions

Improved cooling of photovoltaic panels by natural convection flow in a channel with adiabatic extensions

Impact of External Surroundings on Natural Convection in a Vertical Channel Asymmetrically Heated

Double-skin façade simulation with computational fluid dynamics: A review of simulation trends, validation methods and research gaps

Contact Info

Product

Resources

About