Estimating outdoor mean radiant temperature in a humid subtropical climate

Manavvi, S.; Rajasekar, E.

doi:10.1016/j.buildenv.2020.106658

Cited by 32 publications

(12 citation statements)

References 33 publications

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“…As far as comparison with other literature correlations for h c,g under not controlled outdoor forced convection conditions [43,44,47] is concerned (see Table 6), the data in Figure 5 provide meaningful information. Particularly, values of the heat transfer coefficient by convection obtained in the present study seem to be relatively close to those obtained by Thorsson et al [43] outdoors.…”

Section: Analysis Of the Heat Transfer By Convection On The Globesmentioning

confidence: 54%

“…The coefficients for Equations ( 5), ( 8) and ( 9), obtained by means of sim-ple/multivariable regressions with Sigma Plot [66] are summarized in Table 5. Table 6 also summarizes coefficients for Equation (5) obtained in other literature studies [20,43,44,47]. Experimental results in Figure 4 demonstrate that the measured values of the heat transfer coefficients by convection are generally higher than those predicted by ISO equations [20].…”

Section: Analysis Of the Heat Transfer By Convection On The Globesmentioning

confidence: 75%

“…Particularly, at v a = 1.1 m s −1 , Equation ( 9) overestimates the convection heat transfer by 34% for the 38 mm globe (43 W m −2 K −1 instead of 32 W m −2 K −1 ) and by 15% for the 50 mm one (31 W m −2 K −1 instead of 27 W m −2 K −1 ). In addition, the correlations empirically formulated by Tan et al [44] and Manavvi et al [47] (Table 6) return quite unrealistic h c,g values for heat transfer convection in air being more consistent with forced convection in water [65] which typically exhibits mean heat transfer coefficient in the range from 300 to 1.8•10 4 W m −2 K −1 [65].…”

Section: Analysis Of the Heat Transfer By Convection On The Globesmentioning

confidence: 82%

“…The inaccuracy in the evaluation of the mean radiant temperature observed above (especially at high enclosure temperatures) could be ascribed to the incorrect estimation of the heat transfer coefficient h c,g in Equation (3), which has been derived from the equation recommended by McAdams for spheres heated or cooled by gas with a Reynolds' number ranging from 25 to 100,000 [65]. To verify this hypothesis [25,43,44,47], Equation (1) has been rearranged by assuming that the enclosure surface temperature is equal to the mean radiant temperature (t s = t r ). In this way, the heat transfer coefficient by convection can be measured using the following equation [25]:…”

Section: Analysis Of the Heat Transfer By Convection On The Globesmentioning

confidence: 97%

“…Particularly, in the case of outdoor measurements, small globes show different accuracy leading to overestimation [45] as well as underestimation [47] of the mean radiant temperature in respect to the six-direction radiation reference method [43,[48][49][50]. The most common hypotheses for this behavior are: (i) ISO 7726 [20] and ASHRAE [17] equations do not account for high turbulence phenomena occurring outdoors [51]; (ii) black globes absorb higher short-wave radiation with respect to the clothed human body resulting in systematic errors [43,44,[47][48][49][50]; (iii) the presence of mixed convection [46,52]. A significant underestimation of the mean radiant temperature by table tennis globes (up to 6 • C) has also been found under natural convection conditions (v a = 0) [25].…”

Section: Introductionmentioning

confidence: 99%

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Mean Radiant Temperature Measurements through Small Black Globes under Forced Convection Conditions

et al. 2021

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One of the most critical variables in the field of thermal comfort measurements is the mean radiant temperature which is typically measured with a standard 150 mm black globe thermometer. This is also the reference instrument required for the assessment of heat stress conditions by means of the well-known Wet Bulb Globe Temperature index (WBGT). However, one of the limitations of this method is represented by the relatively long response time. This is why in recent years there has been a more and more pressing need of smart sensors for controlling Heating Ventilation and Air Conditioning (HVAC) systems, and for pocket heat stress meters (e.g., WBGT meters provided with table tennis balls). Although it is widely agreed that there is a clear advantage of small probes in terms of response times, their accuracy is a still a debated matter and no systematic studies aimed at metrologically characterizing their performances are actually available, due to the difficulty of reproducing measuring conditions such as a black enclosure at uniform temperature. In this paper the results of a metrological analysis of two small globes (38 and 50 mm diameter) carried out by means of an experimental apparatus specifically designed to reproduce a black uniform enclosure are presented and discussed. Experimental results revealed a systematic underestimation of the mean radiant temperature predicted by small globes of more than 10 °C in forced convection and at high radiative loads.

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Section: Analysis Of the Heat Transfer By Convection On The Globesmentioning

confidence: 54%

Section: Analysis Of the Heat Transfer By Convection On The Globesmentioning

confidence: 75%

Section: Analysis Of the Heat Transfer By Convection On The Globesmentioning

confidence: 82%

Section: Analysis Of the Heat Transfer By Convection On The Globesmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Mean Radiant Temperature Measurements through Small Black Globes under Forced Convection Conditions

et al. 2021

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Technological opportunities for sensing of the health effects of weather and climate change: a state-of-the-art-review

et al. 2021

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Sensing and measuring meteorological and physiological parameters of humans, animals, and plants are necessary to understand the complex interactions that occur between atmospheric processes and the health of the living organisms. Advanced sensing technologies have provided both meteorological and biological data across increasingly vast spatial, spectral, temporal, and thematic scales. Information and communication technologies have reduced barriers to data dissemination, enabling the circulation of information across different jurisdictions and disciplines. Due to the advancement and rapid dissemination of these technologies, a review of the opportunities for sensing the health effects of weather and climate change is necessary. This paper provides such an overview by focusing on existing and emerging technologies and their opportunities and challenges for studying the health effects of weather and climate change on humans, animals, and plants.

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Improved methods for estimating mean radiant temperature in hot and sunny outdoor settings

et al. 2021

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Estimating outdoor mean radiant temperature in a humid subtropical climate

Cited by 32 publications

References 33 publications

Mean Radiant Temperature Measurements through Small Black Globes under Forced Convection Conditions

Mean Radiant Temperature Measurements through Small Black Globes under Forced Convection Conditions

Technological opportunities for sensing of the health effects of weather and climate change: a state-of-the-art-review

Improved methods for estimating mean radiant temperature in hot and sunny outdoor settings

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