Natural convection in asymmetric triangular enclosures heated from below

Abstract

. Among a number of scientific topics he cultivated in his brilliant academic career, convection heat transfer was the first and the most beloved.Abstract. Triangular enclosures are typical configurations of attic spaces found in residential as well as industrial pitched-roof buildings. Natural convection in triangular rooftops has received considerable attention over the years, mainly on right-angled and isosceles enclosures. In this paper, a finite volume CFD package is employed to study the laminar air flow and temperature distribution in asymmetric rooftop-shaped triangular enclosures when heated isothermally from the base wall, for aspect ratios (AR) 0.2 ≤ AR ≤ 1.0, and Rayleigh number (Ra) values 8 × 10 5 ≤ Ra ≤ 5 × 10 7 . The effects of Rayleigh number and pitch angle on the flow structure and temperature distributions within the enclosure are analysed. Results indicate that, at low pitch angle, the heat transfer between the cold inclined and the hot base walls is very high, resulting in a multi-cellular flow structure. As the pitch angle increases, however, the number of cells reduces, and the total heat transfer rate progressively reduces, even if the Rayleigh number, being based on the enclosure height, rapidly increases. Physical reasons for the above effect are inspected.

Numerical Study of Natural Convective Heat Transfer Within M-Shaped Roofs

“…In attempts to model different weather scenarios, a number of studies have considered different thermal boundary conditions. Enclosure heated from below only is reported by Asan and Namli (2001), Mahmoudi (2011), Kamiyo et al (2014) and Cui et al (2019). Enclosure heated from above only is studied by Akinsete and Coleman (1982), Asan and Namli (2000) and Amrani et al (2017).…”

“…However, with the development of advanced numerical methods that could accurately predicted problems of flows in enclosed surfaces, majority of the authors have used modelling approach. In the past decade, the numerical modelling studies reported include those of , , Ching et al (2012), Yesiloz and Aydin (2013), Kamiyo et al (2014), Mirabedin (2016) and Amrani et al (2017) while the few experimental studies are those of Anderson et al (2010), Oztop et al (2012), Yesiloz and Aydin (2013), Raj et al (2018) and Michels et al (2018). In most cases, sealed attics are considered but there are few reports on vented attics , , Raj et al (2018)).…”

“…Enclosure heated from above only is studied by Akinsete and Coleman (1982), Asan and Namli (2000) and Amrani et al (2017). Ridouane et al (2005), Mahmoudi et al (2013) Recently, some complex roofs reported include dome (Das and Morsi, 2002), inclined triangular cavity (Mahmoudi et al, 2013), asymmetric triangular cavity (Kamiyo et al, 2014) and baffled triangular enclosure (Saha and Gu, 2015). Others are vertical upright-angled triangular cavity (Sieres et al, 2016), gable roofs Amrani et al, 2017), sectioned-triangular prismatic enclosure (Cui et al, 2019) and trapezoidal enclosure (Mehryan et al, 2020).…”

Combined Natural Convection and Surface Radiation Inside Vented Triangular Enclosure - An Experimental Study

“…Mirabedin [3] formulated a correlation for Nusselt number in terms of its aspect ratio and Rayleigh number in case of a triangular enclosure and found that the Nusselt number increased with increase in aspect ratio. Kamiyo et al [4] studied the heat transfer in an asymmetric triangular enclosure with a hot isothermal base wall. They varied the pitch angle (angle between the hot isothermal wall and cold inclined wall) and found that the heat transfer from hot base wall to inclined cold wall is high at low pitch angles and reduces with increasing pitch angle.…”