Three-dimensional heat transfer of globe thermometers in indoor environments controlled by radiant systems

• Published in: Building and environment 2021-01, Vol.188, p.107505, Article 107505
• Main Authors: Xing, Daoming, Li, Nianping
• Format: Article
• Language: English
• Subjects: Aerodynamics; Air temperature; Asymmetric radiation; Asymmetry; Computational fluid dynamics; Computer applications; Cooling; Cooling effects; Diameters; Environmental effects; Finite element method; Fluid dynamics; Globe thermometer; Heat transfer; Hydrodynamics; Indoor environments; Mathematical models; Parameters; Radiant cooling; Radiant systems; Solar radiation; Temperature gradients; Thermal behaviour; Thermodynamic properties; Thermometers; Three dimensional models
• ISSN: 0360-1323; 1873-684X
• DOI: 10.1016/j.buildenv.2020.107505

The theoretical basis of a globe thermometer is based on the lumped parameter method. In highly heterogeneous radiation environments, e.g., outdoor solar radiation and indoor heavily asymmetric radiation, the lumped parameter assumption is likely to be unreasonable. Asymmetric radiation is the inherent feature of radiant cooling indoor environments. Therefore, it is necessary to evaluate the influence of the asymmetric radiation of radiant cooling indoor environments on the thermal behaviour of globe thermometers. In this study, a three-dimensional heat transfer model for globe thermometers is established. The computational fluid dynamics method and the finite element method are used to solve the thermo-fluid field of the globe thermometer. The proposed theoretical model was validated against the results of experiments performed in a radiant cooling room and the data from existing literature. Some case studies were performed to analyse the thermal behaviour of various globe thermometers with different diameters and materials. The temperatures of metal globe thermometers were found to be uniform, whereas the temperature differences in the 50 mm and 150 mm acrylic globe thermometers were both 1.2 °C. Compared to metal globe thermometers, the air temperature deviations in the 50 mm and 150 mm acrylic globe thermometers were 0.6 °C and 0.4 °C, respectively. Thus, the asymmetric radiation of common radiant cooling indoor environments has a slight effect on the thermal behaviour of acrylic globe thermometers. This study is conducive to understanding the heat transfer mechanism of globe thermometers in indoor environments controlled by radiant systems. •A three-dimensional heat transfer model for the globe thermometer is established.•Thermo-fluid field of the globe thermometer is solved by the CFD combined with FEA.•Radiant temperature is vital for evaluating thermal behaviour of globe thermometers.•Thermal behaviour of globe thermometers is affected by the shell material.