Globe Temperature and Its Measurement: Requirements and Limitations

2019 ◽  
Vol 63 (7) ◽  
pp. 743-758
Author(s):  
A Virgílio M Oliveira ◽  
António M Raimundo ◽  
Adélio R Gaspar ◽  
Divo A Quintela
Keyword(s):  
Forced Convection ◽  
Environmental Conditions ◽  
Response Times ◽  
Air Velocity ◽  
Globe Temperature ◽  
Different Diameters ◽  
Relative Differences ◽  
Correction Equations

Abstract This study addresses the measurement of the globe temperature. For this purpose, two globe thermometers with different diameters (50 and 150 mm) and a variety of thermal environmental conditions were considered. The assessments of the response times and of the influences of the globe diameter and the air velocity on the measured globe temperatures are discussed. The results of the response times clearly put in evidence that the values usually stated in the literature can be questioned and that longer measurement periods must be considered. In fact, response times >30 min were obtained in 68% of the tests performed. Moreover, differences >20ºC were obtained between the 150 and 50 mm sensors, highlighting the influence of the globe diameter. The analysis of the effect of the air velocity on the globe temperature shows mean relative differences >30% between tests in still air and with the higher air velocity considered (1.81 m s–1). On the basis of measurements carried out with the 50 mm globe, correction equations to the standard globe temperature for both natural and forced convection are proposed.

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

Atmosphere ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 621
Author(s):  
Francesca Romana d’Ambrosio Alfano ◽  
Giorgio Ficco ◽  
Andrea Frattolillo ◽  
Boris Igor Palella ◽  
Giuseppe Riccio
Keyword(s):  
Heat Stress ◽  
Forced Convection ◽  
Response Times ◽  
Table Tennis ◽  
Mean Radiant Temperature ◽  
Metrological Analysis ◽  
Experimental Apparatus ◽  
The Mean ◽  
Globe Temperature ◽  
Radiant Temperature

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.

Evaluation of the influence of ambient air temperature and air velocity on mortar cement durability using a forced convection solar dryer

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Younes Bahammou ◽  
Mounir Kouhila ◽  
Haytem Moussaoui ◽  
Hamza Lamsyehe ◽  
Zakaria Tagnamas ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Forced Convection ◽  
Air Temperature ◽  
Building Materials ◽  
Ambient Air ◽  
Physical Significance ◽  
Drying Process ◽  
Air Velocity ◽  
Content Type ◽  
Ambient Air Temperature

PurposeThis work aims to study the hydrothermal behavior of mortar cement toward certain environmental factors (ambient air temperature and air velocity) based on its drying kinetics data. The objective is to provide a better understanding and controlling the stability of mortar structures, which integrate the sorption phenomenon, drying process, air pressure and intrinsic characteristics. This leads to predict the comportment of mortar structures in relation with main environmental factors and minimize the risk of cracking mortar structures at an early age.Design/methodology/approachThermokinetic study was carried out in natural and forced convection solar drying at three temperatures 20, 30 and 40°C and three air velocities (1, 3 and 5 m.s-1). The empirical and semiempirical models tested successfully describe the drying kinetics of mortar. These models simulate the drying process of water absorbed by capillarity, which is the most common humidity transfer mechanism in building materials and contain parameters with physical significance, which integrate the effect of several environmental factors and intrinsic characteristics of mortar structures.FindingsThe models simulate the drying process of water absorbed by capillarity, which is the most common humidity transfer mechanism in building materials and contain parameters with physical significance, which integrate the effect of several environmental factors and intrinsic characteristics of mortar structures. The average activation energy obtained expressed the temperature effect on the mortar diffusivity. The drying constant and the diffusion coefficient can be used to predict the influence of these environmental factors on the drying behavior of various building materials and therefore on their durability.Originality/valueEvaluation of the effect of several environmental factors and intrinsic characteristics of mortar structures on their durability.

Evaluation of Indoor Climate in Small University Lecture Hall

2016 ◽  
Vol 861 ◽  
pp. 369-375
Author(s):  
Mária Budiaková
Keyword(s):  
Thermal Comfort ◽  
Architectural Design ◽  
Winter Season ◽  
Lecture Hall ◽  
Experimental Measurements ◽  
Optimal Parameters ◽  
Indoor Climate ◽  
Air Velocity ◽  
Globe Temperature ◽  
The University

This paper is focuses on the evaluation of the indoor climate in the small university lecture hall. Providing the optimal parameters of thermal comfort in the interiors of a university is immensely important for the students of the university. Fulfilling these parameters is inevitable not only for the physiological needs of students but also for the required performance of students. Reconstruction took place in the small university lecture hall. The original windows were exchanged for the modern wood tight windows. Experimental measurements were carried out in the winter season in 2016 in this small university lecture hall in order to evaluate the thermal comfort after the reconstruction. The device Testo 480 was used for the measurements. Obtained values of air temperature, air relative humidity, air velocity, globe temperature and indexes PMV, PPD are presented in the graphs. Heating, operation and architectural design of the small university lecture hall were evaluated on the basis of the parameters of thermal comfort. In the conclusion of this paper, there are principles how to design new small university lecture halls. Furthermore, there are presented recommendations how to operate the existing small university lecture halls.

Pilot Study on Occupants’ Thermal Sensation at Different Ambient Temperature in Postgraduate Office with Cooling Mode in University Campus

2020 ◽  
Vol 78 (2) ◽  
pp. 1-11
Author(s):  
Noor Syazwanee Md Taib ◽  
Sheikh Ahmad Zaki Shaikh Salim ◽  
Aya Hagishima ◽  
Waqas Khalid ◽  
Fitri Yakub ◽  
...  
Keyword(s):  
Thermal Sensation ◽  
Mean Value ◽  
University Campus ◽  
Kuala Lumpur ◽  
Air Velocity ◽  
Cooling Mode ◽  
Rapid Urbanization ◽  
Humid Condition ◽  
Globe Temperature ◽  
Office Rooms

With rapid urbanization, massive amount of energy is required to compensate the electricity usage thus calls for a need to Malaysian government issuing standard MS1525:2014 for temperature settings in office buildings to meet energy efficiency goal. In co-sharing spaces, personal thermal comfort is often not met due to the different thermal sensation at different location inside office rooms. This study was conducted at four postgraduate office spaces with cooling mode in university campus located at Kuala Lumpur to evaluate the occupant’s thermal sensation. We used different set-point temperature of air conditioning ranging from 18.0°C to 28.6°C. The indoor thermal variables such as air temperature, globe temperature, relative humidity, and air velocity are measured at each respondent’s workspace and 200 responses were recorded from ten subjects. The mean value of thermal sensations votes is -0.4 and were within comfort range. 76% of responses voted ‘neutral’ humidity sensation as occupants have adapted to humid condition in Malaysia. The comfort operative temperature found in this study is 24.9°C which indicates that the minimum recommended temperature for energy conservation did not deprive occupants from comfort.

EFFECT OF AIR VELOCITY ON INHALATION DOSES DUE TO RADON AND THORON PROGENY IN A TEST CHAMBER

2020 ◽  
Vol 189 (3) ◽  
pp. 401-405
Author(s):  
Rosaline Mishra ◽  
Rama Prajith ◽  
Rajeswari Pradhan Rout ◽  
Jalaluddin Sriamirullah ◽  
Balwinder Kaur Sapra
Keyword(s):  
Physical Properties ◽  
Environmental Conditions ◽  
Test Chamber ◽  
Air Velocity ◽  
Attachment Rate ◽  
Inhalation Dose ◽  
Decay Products ◽  
Calibration Chamber ◽  
Thoron Progeny

Abstract Inhalation doses due to radon and thoron are predominantly due to the inhalation of progeny of Radon and Thoron. The progeny/decay-products of radon and thoron are particulates unlike their parent gas and exhibit different physical properties like attachment to the aerosols and deposition on different surfaces. All these properties in turn depend on the environmental conditions such as air velocity, aerosol concentration, attachment rate, etc. The role of air velocity on deposition on surfaces decides the progeny particles left in the air for inhalation. Therefore, in the present work, we have studied the effect of air velocity on the inhalation dose due to radon and thoron progeny at the centre of a 0.5-m3 calibration chamber as well as on all surfaces. Hence, the studies were carried out at different air velocities, and inhalation doses were measured using deposition-based direct radon and thoron progeny sensors.

scholarly journals Considerations for the development of extreme heat policies in sport and exercise

2020 ◽  
Vol 6 (1) ◽  
pp. e000774 ◽  
Author(s):  
Samuel Chalmers ◽  
Glenda Anderson ◽  
Ollie Jay
Keyword(s):  
Environmental Stress ◽  
Ambient Temperature ◽  
Environmental Conditions ◽  
Environmental Parameters ◽  
Extreme Heat ◽  
Mean Radiant Temperature ◽  
Air Velocity ◽  
Cooling Strategies ◽  
Sport And Exercise ◽  
Radiant Temperature

We detail key considerations for the development of extreme heat policies in sport and exercise. Policies should account for the four environmental parameters (ambient temperature, humidity, air velocity, and mean radiant temperature) and two personal (activity and clothing) parameters that determine the prevailing thermoregulatory strain during exercise in the heat. Considerations for how to measure environmental stress and convey the level of risk are discussed. Finally, we highlight the need to include feasible cooling strategies that are relevant for the prevailing environmental conditions.

Impact of Environmental Conditions on Frost Crystal Structure

2020 ◽  
Vol 28 (02) ◽  
pp. 2050014
Author(s):  
Tongxin Zhang ◽  
Dennis L. O’Neal ◽  
Stephen T. McClain
Keyword(s):  
Crystal Structure ◽  
Air Temperature ◽  
Wall Temperature ◽  
Environmental Conditions ◽  
Strong Influence ◽  
Aluminum Surface ◽  
Air Velocity ◽  
Air Temperatures ◽  
Crystal Type ◽  
Frost Growth

Frost crystal type and distribution were characterized in the initial periods of frost growth on an aluminum surface. Experiments were carried out for a range of wall temperatures from [Formula: see text]C to [Formula: see text]C, air temperatures from [Formula: see text]C to [Formula: see text]C, relative humidities from 15% to 85%, and air velocities from 0.5 to 5.0[Formula: see text]m/s. The results showed that frost crystal type was strongly dependent on the wall temperature and humidity. Changing the air temperature shifted the region of some frost crystal types. Decreasing the air temperature from 22 down to either [Formula: see text]C or [Formula: see text]C led to the decrease of feather crystals but increased the region of scroll crystals. Air velocity had smaller impacts on frost crystal type but had a strong influence on the distance between the crystals, particularly at lower air velocities. The results were compared to prior researchers. The results should provide a better understanding of frost morphology during the early stages of frost growth on metal surfaces.

scholarly journals Air flow characteristics of a room with air vortex diffuser

2018 ◽  
Vol 240 ◽  
pp. 02002 ◽  
Author(s):  
Marek Borowski ◽  
Marek Jaszczur ◽  
Daniel Satoła ◽  
Michał Karch
Keyword(s):  
Air Flow ◽  
Ventilation System ◽  
Flow Characteristics ◽  
Comfort Level ◽  
Translational Velocity ◽  
Comfort Zone ◽  
Air Velocity ◽  
Velocity Decay ◽  
Different Diameters ◽  
Comfort Criteria

The air diffuser is a very important component of any ventilation system, and the comfort level of ventilated space occupants depend among many other factors on properly designed and choice of diffusers. At present a large number of diffusers are produced to meet a different kind of requirements. One of the most efficient and very popular types of the diffuser is the vortex diffuser in which air flow has angular as well as translational velocity components. This paper investigates experimentally airflow characteristics of vortex ceiling diffuser and its effect on airflow in a ventilated space. Two thermal comfort criteria namely: mean age of the air and ventilation effectiveness have been used to predict the comfort zone inside the room. Effect of supply air velocity on the flow field is investigated and hence the on comfort and energy consumption. The results show that significant amount of energy can be saved by using vortex diffuser in reference to the other diffusers type. The values of the velocity decay coefficient were compared for different diameters of vortex diffuser.

scholarly journals Evaluating a New Shade for Feedlot Cattle Performance and Heat Stress

2017 ◽  
Vol 60 (4) ◽  
pp. 1301-1311 ◽  
Author(s):  
Morgan D. Hayes ◽  
Tami M. Brown-Brandl ◽  
Roger A. Eigenberg ◽  
Larry A. Kuehn ◽  
R. Mark Thallman
Keyword(s):  
Heat Stress ◽  
Feed Intake ◽  
Environmental Conditions ◽  
Average Daily Gain ◽  
Ground Temperature ◽  
Globe Temperature ◽  
The Impact ◽  
Daily Gain ◽  
Black Globe Temperature ◽  
Cattle Performance

Abstract. Heat stress in cattle results in decreased feed intake, lower daily gain, and potentially death in susceptible animals under intense conditions. A study was carried out during the summer of 2013 at the USDA-ARS U.S. Meat Animal Research Center feedlot evaluating the impact of shade on environmental conditions and cattle performance. A novel two-tiered shade was used in half of the 14 pens, each holding 30 animals. The shades were designed to reduce solar heat load by 40% to 60% and to provide traveling shade across the pen, providing varied amounts of shade area as well as varied solar reduction potential. The objective of this study was to determine if the shade was effective at improving performance (evaluated as average daily gain, feed intake, and feed to gain ratio) and reducing environmental conditions that cause heat stress. A group of mixed-breed cattle with varied genetics including both and were selected, penned on the basis of sex, and blocked by color. Production parameters of pen feed usage were measured daily, and individual body weights were taken monthly. Environmental conditions including air temperature, relative humidity, wind speed, ground temperature, and black globe temperature with and without shade were measured. Solar load on the pens was reduced when shade was provided, with both ground temperature and black globe temperature showing reductions. Cattle showed nominally better performance; however, no significant differences were found in gain or feed intake. Panting scores were significantly lower with shade provided; slopes of cattle respiration rate versus ambient temperature were significantly lower with shade during the afternoon period. Keywords: Cattle, Feedlot, Heat stress, Respiration, Shade.

scholarly journals Evaluation of litter material and ventilation systems on poultry production: II. thermal comfort

2011 ◽  
Vol 40 (6) ◽  
pp. 1356-1363 ◽  
Author(s):  
Paulo Giovanni de Abreu ◽  
Valéria Maria Nascimento Abreu ◽  
Arlei Coldebella ◽  
Fátima Regina Ferreira Jaenisch ◽  
Doralice Pedroso de Paiva
Keyword(s):  
Repeated Measures ◽  
Thermal Environment ◽  
Thermal Conditions ◽  
Radiant Heat ◽  
Poultry Production ◽  
Rice Husks ◽  
Air Velocity ◽  
Globe Temperature ◽  
Soybean Straw ◽  
Ventilation Systems

The objective of this study was to evaluate environmental thermal conditions in broiler houses with two different ventilation systems and two different litter materials. The experiment was carried out in four 12 m × 10 m broiler houses, internally divided in 4 boxes/poultry house, with 200 birds/pen for four consecutive flocks, each one with a duration of 42 days with 15 days of downtime between flocks. Treatments tested were two ventilation systems (stationary or oscillating fans), and two types of litter materials (soybean straw or rice husks). It was collected in the center of each pen and in the external enviroment, dry and wet bulb temperatures, black globe temperature, and air velocity. These data were collected at 3-hour intervals from 8:00 a.m. to 6:00 p.m. at the fourth, fifth and sixth week age of the bird. Based on the data collected at each time, wet and globe temperature index (WBGT) and radiant heat load (RHL) were determined. Litter temperature reaings were also performed by using an infrared thermometer. Effects of flock, ventilation, week, hour and the interactions among factors on the studied variables were evaluated in the analysis of the internal thermal environment by using the theory of mixed models for repeated measures. Ventilation provided by stationary and oscilating fans had equal behavior and it did not affect the studied variable. However, both ventilation systems are sufficient to soften internal thermal conditions in the broiler house in relation to the external environment. Relative humidity of the air is higher when rice husks is used as litter material.

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