Dynamic thermal building analysis with CFD – modelling radiation

Abstract

In an attempt to reduce the high computational efforts for dynamic thermal simulations using Computational Fluid Dynamics (CFD) the authors have recently developed an adaptive freeze-flow method (i.e. freezing of flow equations over variable time periods). This paper documents the work that has been carried out to predict the radiative surface heat transfer in dynamic thermal building processes using CFD.The Monte Carlo and Discrete Transfer radiation models were investigated and results compared with analytical solutions. The Discrete Transfer model has shown good performance whereas an unrealistic radiation distribution on the surfaces was observed for the Monte Carlo model. A further investigation of the Discrete Transfer model for the cooling of a solid wall has shown that the adaptive freeze-flow method is an efficient and accurate way to carry out dynamic thermal CFD simulations which involve radiation.

Calculation of view factors for complex geometries using Stokes’ theorem

“…There are several applications that ask for this detailed calculations, such as industrial equipment studies (Boulet et al 2010;Gemaque and Costa 2012), building thermal simulation (Gong and Claridge 2007;Cook, Zitzmann, and Pfrommer 2008;Chen et al 2012;Yang, Li, and Yang 2012), performance analysis of HVAC equipment (Ghaddar, Salam, and Ghali 2006;Vangtook and Chirarattananon 2006;Gong and Claridge 2007) or detailed analysis of comfort conditions of a person (Kakuta et al 2001;Miyanaga 2001;Manabe, Yamazaki, and Sakai 2004;Omori et al 2004;Raimundo, Gaspar, and Quintela 2004a;Yang et al 2007; Kilic and Sevilgen 2008;Zhu et al 2008;Martinho, Lopes, and Gameiro da Silva 2012).…”

“…However, despite being extremely useful, this information is inappropriate to generic geometries and computational procedures, to incorporate into computer fluid dynamic (CFD) programs, or, for * Corresponding author. Email: sara.francisco@adai.pt instance, in building's energy simulation programs, where some simplifications may lead to discrepancies on the prediction of thermal comfort level and energy consumption (Conceição and Silva 2004;Kubaha et al 2004;Ghaddar, Salam, and Ghali 2006;Cook, Zitzmann, and Pfrommer 2008).…”

RANS model calibration using stochastic optimization for accuracy improvement of urban airflow CFD modeling

“…Increasing applications of computational fluid dynamics (CFD) in the urban studies reflects on its importance in research and practical engineering applications (Blocken, 2014;Jiru and Bitsuamlak, 2010). Different aspects of airflow in urban environment, including pedestrian level wind comfort (Blocken et al, 2016;Fadl and Karadelis, 2013;Iqbal and Chan, 2016;Mirzaei and Haghighat, 2011;Serteser and Karadag, 2018;Tsang et al, 2012;Wang et al, 2019;Yoshie et al, 2007), building energy (Allegrini et al, 2015;Charisi et al, 2019;Cook et al, 2008;Fan and Ito, 2012;Malys et al, 2015;Mochida et al, 2006b;Zhai et al, 2002;Zhang et al, 2018), pollution dispersion (Abbassi et al, 2019;Gonzalez Olivardia et al, 2019;Haghighat and Mirzaei, 2011;Longo et al, 2019;Luo et al, 2016;Tominaga andStathopoulos, 2011, 2010;Yoshie et al, 2011), and urban heat island (Allegrini et al, 2015;Hien et al, 2012;Kawamoto, 2016;Mirzaei et al, 2015;Priyadarsini, 2009) are the main subject areas tackled by CFD models.…”

Thermal comfort analysis of a high-speed train cabin considering the solar radiation effects

“…On one hand, the solar radiation condition is based on a dynamic environment, which is related to solar emitting angle, radiation intensity, local time, location coordinates and weather condition. 15,16 For instance, the radiated area inside the cabin can be small when the sun is at zenith, or great when the sun stands lower. 6 On the other hand, the HSR cabin itself could have an impact on the effect of the solar radiation, such as the train travelling direction, the materials in the cabin and window, the arrangement of passengers and cabin geometry.…”