On the measurement of the mean radiant temperature by means of globes: An experimental investigation under black enclosure conditions. (15th April 2021)

• Record Type: Journal Article
• Authors: d'Ambrosio Alfano, Francesca Romana; Dell'isola, Marco; Ficco, Giorgio; Palella, Boris Igor; Riccio, Giuseppe
• Is Part Of: Building and environment. Volume 193(2021)
• Publication Date: 2021-04-15
• Subjects: Mean radiant temperature -- Globe temperature -- Thermal comfort -- PMV -- Thermal stress -- WBGT -- Smart sensors; Buildings -- Environmental engineering -- Periodicals; Building -- Research -- Periodicals; Constructions -- Technique de l'environnement -- Périodiques; Electronic journals; 696
• DOI: 10.1016/j.buildenv.2021.107655
• Languages: English
• ISSNs: 0360-1323

Abstract

Abstract: Mean radiant temperature is one of the four physical quantities required for the objective assessment of thermal environments. Due to its simplicity and relatively good accuracy, the most common measurement method is the black globe thermometer. Most studies have investigated the effects of diameter on the response time, of globe materials on its accuracy and the heat transfer modelling. Unfortunately, results seem to be inconsistent due to the difficulty of calibrating and metrologically characterizing globe thermometers under uniform black enclosure conditions. Besides, few studies have been focused on the accuracy of small globes that could result in a wrong assessment of the thermal environment. To answer to these open issues, this study will be focused on a metrological analysis of a wide sample of globes (metallic-made and plastic-made with different diameters) carried out in a testing apparatus specifically designed to reproduce a black uniform enclosure whose temperature can be strictly controlled. Obtained results revealed high errors of the mean radiant temperature measurement by tennis-table globes (up to 6 °C) which require a specific reformulation of convective heat transfer modelling, and lower response time (3–4 min) of table-tennis globes if compared with large ones (6–9 min). Highlights: The measurement of the mean radiant temperature with globes was investigated. An apparatus reproducing a reference black enclosure was developed. Small globes underestimate the mean radiant temperature at high radiative loads. New equations for calculating the convective heat transfer coefficient were proposed. Time constants are not affected by the material and did not exceed 10 min.