Experimental study of turbulent air natural convection in open-ended vertical parallel plates under asymmetric heating conditions

Kim, Koung Moon; Nguyen, Dong Ho; Shim, Gyu Hyeon; Jerng, Dong-Wook; Ahn, Ho Seon

doi:10.1016/j.ijheatmasstransfer.2020.120135

Cited by 18 publications

(12 citation statements)

References 21 publications

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“…In addition, the presence of the recirculation area in the marked region in Figure 8 may also cause the complex behavior of the airflow rate in the cases of G 1 = 0.1 m and 0.15 m in Figure 7. Similar effects were also reported by Zamora and Kaiser [22] and Kim et al [20].…”

Section: Changing Gsupporting

confidence: 90%

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CFD Analysis of Different Ventilation Strategies for a Room with a Heated Wall

Nguyen

Tran

et al. 2022

Buildings

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Solar chimneys can help to reduce solar heat gain on a building envelope and to enhance natural ventilation. In this work, we proposed three configurations of two solar chimneys combined with a heated wall for the natural ventilation of a room: (I) the chimneys are connected serially, (II) the chimneys are parallel and exhaust air at two separate outlets, and (III) the chimneys are parallel, but the outlets are combined. The airflow rate achieved with each configuration was predicted with a Computational Fluid Dynamics model. The results show the effects of the heat flux in each channel and the geometries of the channels. Configuration (II) shows the highest flow rate. Particularly, the proposed configurations enhance the flow rate significantly and up to 40% when compared to the typical setup with a single channel solar chimney. The findings offer a novel design option for building façades for reducing solar heat gain and enhancing natural ventilation.

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Section: Changing Gsupporting

confidence: 90%

“…However, when the gap is large compared to the height, there is a reverse flow at the top the air channel. The reverse flow obstructs the main flow and reduces the flow rate [8,11,[19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

CFD Analysis of Different Ventilation Strategies for a Room with a Heated Wall

Nguyen

Tran

et al. 2022

Buildings

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“…Typically, the height of a wall solar chimney is about 0.5−1.5 m (Al Touma and Ouahrani, 2018; Baïri et al, 2020; Burek and Habeb, 2007; Wang and Lei, 2020). The gap-to-height ratio should be below 0.3 to avoid a reverse flow at the outlet (Chen et al, 2003; Kim et al, 2020). Accordingly, the chimney in Figure 1 was tested with H and G/H in the range of 0 . 5 m − 1 . 5 m and 0 . 05 − 0 . 2 , respectively.…”

Section: Numerical Modelingmentioning

confidence: 99%

“…Besides, the gap–to–height ratio is also an important factor. Large G/H values may result in a reverse flow at the outlet (Chen et al, 2003; Kim et al, 2020; Zamora and Kaiser, 2009a) and lead to a reduction of the flow rate or the increasing rate of the flow rate versus the gap (Jing et al, 2015; Khanal and Lei, 2012). There are also optimal G/H ratios for maximizing the Nusselt number and induced flow rate of a solar chimney for heating applications (Zamora and Kaiser, 2009b).…”

Section: Introductionmentioning

confidence: 99%

Characterizing the induced flow through the cavity of a wall solar chimney under the effects of the opening heights

Nguyen

2022

Journal of Building Physics

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Using solar chimneys in buildings can enhance the thermal insulation of the building envelope and provide sufficient ventilation and cooling. The performance of a solar chimney is strongly affected by its configurational factors. This work examines the effects of the opening heights on the flow field in the cavity of a wall solar chimney with a Computational Fluid Dynamics (CFD) model. Both cases of equal and unequal opening areas were considered. The results show that the induced flow rate increases with the opening height and gradually becomes constant as the opening height is about 2.0–3.0 and 5.0–6.0 times the air gap for heating the left wall (HLW) and the right wall (HRW) of the air cavity, respectively. Particularly, using equal inlet and outlet heights that are equal to the air gap reduces the flow rate of 27% for HLW and 85% for HRW compared to the maximum ones. The optimal design of a wall solar chimney to achieve maximum flow rate is proposed for two cases of heating, that is, (a) for HLW, equal opening heights which are twice the air gap, and (b) for RHW, the inlet height equal to the air gap, and the outlet height equal to five times the air gap.

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“…The studies of vertical channels with symmetrical or asymmetrical heating approach radiative energy losses analysis. Cheng and Mu¨ller (1998) and Kim et al (2020) computed the total heat rate removed by air through a vertical channel and implemented a radiative exchange model to estimate the heat removed by the radiative exchange.…”

Section: Introductionmentioning

confidence: 99%

Experimental study and numerical analysis of radiative losses of single-channel solar chimney

Torres-Aguilar

Arce

Xamán

et al. 2022

Journal of Building Physics

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Solar chimneys provide natural ventilation for buildings, reducing the energy consumption of mechanical systems. Therefore, analyzing energy losses through solar chimney components and inlet/outlet of air channel is critical to develop a suitable design for this passive ventilation system. In this study, the performance and energy losses analysis of a single-channel solar chimney (SC-SOCH) is described; a parametric study under laboratory conditions was conducted regarding the air gap (0.10, 0.15, and 0.20 m) and heat flux of absorber plate (100, 200, 300, 400, and 500 Wm−2). The energy losses were analyzed with temperature sensors, heat flow transducers, and a net radiation transfer model. The parametric study results showed that between 10% and 15% of the total energy supplied to the absorber plate was dissipated to the laboratory environment through the glass cover. Furthermore, combining the different thermal insulation layers on the backside of the absorber plate and sidewalls of the air channel permitted only energy losses below 8% of the total energy supplied. The highest energy losses occurred due to radiative exchange; the radiative losses through the inlet and outlet of the air channel were between 9.38% and 25.78% of the total energy supplied. However, the radiative energy loss rate decreased as airflow increased; the volumetric flow rate was from 34.11 to 94.92 m3h−1, which was enough to satisfy the requirements of total ventilation rate for spaces of 9, 18, and 36 m2 according to ASHRAE 62.2–2019. Therefore, solar chimney designs must be optimized to minimize energy losses and increase airflow for natural ventilation.

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Experimental study of turbulent air natural convection in open-ended vertical parallel plates under asymmetric heating conditions

Cited by 18 publications

References 21 publications

CFD Analysis of Different Ventilation Strategies for a Room with a Heated Wall

CFD Analysis of Different Ventilation Strategies for a Room with a Heated Wall

Characterizing the induced flow through the cavity of a wall solar chimney under the effects of the opening heights

Experimental study and numerical analysis of radiative losses of single-channel solar chimney

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