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Article: Globe thermometer free convection error potentials

TitleGlobe thermometer free convection error potentials
Authors
Issue Date2020
Citation
Scientific Reports, 2020, v. 10, n. 1, article no. 2652 How to Cite?
AbstractFor thermal comfort research, globe thermometers have become the de facto tool for mean radiant temperature, tr, measurement. They provide a quick means to survey the radiant environment in a space with nearly a century of trials to reassure researchers. However, as more complexity is introduced to built environments, we must reassess the accuracy of globe measurements. In particular, corrections for globe readings taking wind into account rely on a forced convection heat transfer coefficient. In this study, we investigate potential errors introduced by buoyancy driven flow, or free convection, induced by radiant forcing of a black globe’s surface to a temperature different from the air. We discovered this error in an experimental radiant cooling system with high separation of air to radiant temperature. Empirical simulations and the data collected in a radiant cooling setup together demonstrate the influence of free convection on the instrument’s readings. Initial simulation and data show that tr measurements neglecting free convection when calculating tr from air temperatures of 2 K above tr could introduce a mechanism for globe readings to incorrectly track air temperatures. The experimental data constructed to test this hypothesis showed the standard correction readings are 1.94 ± 0.90 °C higher than the ground truth readings for all measurements taken in the experiment. The proposed mixed convection correction is 0.51 ± 1.07 °C higher than the ground truth, and is most accurate at low air speeds, within 0.25 ± 0.60 °C. This implies a potential systematic error in millions of measurements over the past 30 years of thermal comfort research. Future work will be carried out to experimentally validate this framework in a controlled climate chamber environment, examining the tradeoffs between accuracy and precision with globe thermometer measurements.
Persistent Identifierhttp://hdl.handle.net/10722/334643
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorTeitelbaum, Eric-
dc.contributor.authorChen, Kian Wee-
dc.contributor.authorMeggers, Forrest-
dc.contributor.authorGuo, Hongshan-
dc.contributor.authorHouchois, Nicholas-
dc.contributor.authorPantelic, Jovan-
dc.contributor.authorRysanek, Adam-
dc.date.accessioned2023-10-20T06:49:36Z-
dc.date.available2023-10-20T06:49:36Z-
dc.date.issued2020-
dc.identifier.citationScientific Reports, 2020, v. 10, n. 1, article no. 2652-
dc.identifier.urihttp://hdl.handle.net/10722/334643-
dc.description.abstractFor thermal comfort research, globe thermometers have become the de facto tool for mean radiant temperature, tr, measurement. They provide a quick means to survey the radiant environment in a space with nearly a century of trials to reassure researchers. However, as more complexity is introduced to built environments, we must reassess the accuracy of globe measurements. In particular, corrections for globe readings taking wind into account rely on a forced convection heat transfer coefficient. In this study, we investigate potential errors introduced by buoyancy driven flow, or free convection, induced by radiant forcing of a black globe’s surface to a temperature different from the air. We discovered this error in an experimental radiant cooling system with high separation of air to radiant temperature. Empirical simulations and the data collected in a radiant cooling setup together demonstrate the influence of free convection on the instrument’s readings. Initial simulation and data show that tr measurements neglecting free convection when calculating tr from air temperatures of 2 K above tr could introduce a mechanism for globe readings to incorrectly track air temperatures. The experimental data constructed to test this hypothesis showed the standard correction readings are 1.94 ± 0.90 °C higher than the ground truth readings for all measurements taken in the experiment. The proposed mixed convection correction is 0.51 ± 1.07 °C higher than the ground truth, and is most accurate at low air speeds, within 0.25 ± 0.60 °C. This implies a potential systematic error in millions of measurements over the past 30 years of thermal comfort research. Future work will be carried out to experimentally validate this framework in a controlled climate chamber environment, examining the tradeoffs between accuracy and precision with globe thermometer measurements.-
dc.languageeng-
dc.relation.ispartofScientific Reports-
dc.titleGlobe thermometer free convection error potentials-
dc.typeArticle-
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1038/s41598-020-59441-1-
dc.identifier.pmid32060327-
dc.identifier.scopuseid_2-s2.0-85079359628-
dc.identifier.volume10-
dc.identifier.issue1-
dc.identifier.spagearticle no. 2652-
dc.identifier.epagearticle no. 2652-
dc.identifier.eissn2045-2322-
dc.identifier.isiWOS:000562932300012-

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