Thermal comfort analysis

Combined thermal and multizone airflow models are needed for problems such as thermal comfort analysis in naturally ventilated buildings, determination of heat-removal capacity by natural ventilation, design and evaluation of passive cooling by nighttime ventilation. This is outlined in more detail in Section 11.5. 

Due to the methods and limitations outlined in Section 11.3..3, in thermal comfort analysis, draft risk evaluations cannot be performed using this type of room model. Analysis of air temperature stratification and thermal comfort for the occupant zone can be achieved only by using multi-air-node room models. 

Thermal comfort analysis in naturally ventilated buildings... 

Fanger, P. 0., "Thermal Comfort Analysis and Applications in Environmental Engineering," McGraw-Hill, New York, 1970. 

Note that the operative temperature will be the arithmetic average of the ambient and surrounding surface temperatures when the convection and radiation heat transfer coefficients are equal to each other. Another environmental index used in thermal comfort analysis is the effective temperature, which combines the effects of temperature and humidity. Two environments with the same effective temperature evokes the same thermal response in people even though they are at different temperatures and humidities. 

Fanger PO (1972) Thermal comfort, analysis and applications in environmental engineering. McGraw-HUI, New York... 

In industrial ventilation the majority of air velocity measurements are related to different means of controlling indoor conditions, like prediction of thermal comfort contaminant dispersion analysis adjustment of supply airflow patterns, and testing of local exhausts, air curtains, and other devices. In all these applications the nature of the flow is highly turbulent and the velocity has a wide range, from O.l m in the occupied zone to 5-15 m s" in supply jets and up to 30-40 m s in air curtain devices. Furthermore, the flow velocity and direction as well as air temperature often have significant variations in time, which make measurement difficult. 

Environmental Conditions. The last area of discussion concerns those studies that emphasize environmental factors indoors and their interrelationship with clothing. Fanger s multivariate equation for predicting thermal comfort indoors, which he defines as thermal neutrality, is based on statistical analysis of 1,300 Danish and American subjects and consists of six parameters metabolic activity of occupants, clothing insulative value (clo), air temperature, mean radiant temperature, relative humidity, and air velocity ( 8, TjO An instrument based m these parameters and the statistical analysis is available (Figure 2) a reading for the parameters is integrated and the percent of occupants satisfied with the thermal environment is displayed. 

Chen X, Kunz E. Analysis of 3D woven structure as a device for improving thermal comfort of ballistic vests. Int J Cloth Sci Technol 2005 17(3/4) 215—24. 

Table 13.4 has been created from the information and estimates contained in BS/EN/ ISO 7730 1995 (Moderate Thermal Environments—Determination of the PMV and PPD Indices and Specification of the Conditions for Thermal Comfort). It represents a subset of values most likely to be useful and relevant to environmental design in control rooms. Note that some of the air temperature values are higher than those set in BS/EN/ISO 11064-6 2005 as minimum requirements. This illustrates the importance of a more fine-grained analysis linked to the subjective experience of the thermal environment. 

Oliveira, A.V.M., Caspar, A.R. Quintela, D A. 2008c. Measurements of clothing insulation with a thermal manikin operating under the thermal comfort regulation mode comparative analysis of the calculation methods. EurJAppl Physiol 104(4) 679-688. 

ABSTRACT Any human activity is influenced by the working environment in which it is developed. The opinion of employees is, nowadays, an important factor to consider because their perception may be related to their behavior. The satisfaction of all individuals housed in a thermal environment is an almost impossible task because a thermally comfortable environment for one person may be uncomfortable for another. Therefore, it would be ideal to create a thermal environment that satisfied the largest number of workers. As such, the evaluation of thermal comfort implies a certain degree of subjectivity and requires the analysis of two aspects physical (thermal environment) and subjective (state of mind of the individual). This study aims to analyze the pattern of thermal sensation of a packaging section of quick-frozen desalted codfish, discover the location of the most vulnerable workstations to thermal stress and assess the real thermal sensation of workers. The data were collected using a measurement instrument named Center 317—temperature humidity meter . For the analysis of thermal sensation the follow indexes were applied Temperature Humidity Index (THI), Thermal Comfort Scale (EsConTer) and Predicted Percentage of Dissatisfied (PPD). A set of standards were created for each variable and the results obtained indicate the most vulnerable workstations. Intervention strategies were considered. 

ABSTRACT The analysis of a thermal comfort or to a thermal stress situation can be achieved using diverse techniques, models and numerical simulations. The main purpose of this paper is to use a human thermal software to analyze the human response to different thermal environmental conditions. The human thermal model is based on equations of heat and mass transfer and, based on the parameters of thermal environment that influence comfort, it can predict the temperatures and humidity at the human body and clothing. A simulation was done using the experimental data obtained from a field investigation at an industrial plant. Results indicate that the software can differentiate body parts concerning its thermal behavior according to their adaptability and in all cases, the temperature values tend to stabilization. A verification of the coefficients of heat transfer between the cloth and the environment is required being pointed as future work. 

The occupational environment can be neutral, cold or hot. A combined action between the four environmental parameters (temperature, relative humidity, velocity and radiant heat) and the two individual parameters (clothing worn by the occupants and their activity) can lead to a thermal comfort, discomfort, or to a thermal stress situation (Parsons, 2013). The integration of these parameters can be done in a thermal index in a way that will provide a single value that is related to the effects on the occupants. Three types of indices can be identified empirical, rational and derived. According to Parsons (2000), rational indices are derived from mathematical models that describe the behavior of the human body in thermal environments. The analysis of these situations can be achieved using diverse techniques and comfort models, such as Computation Fluid Dynamics (CFD) and other numerical simulations (Murakami et ah, 2000). The human thermal software (Teixeira et al., 2010) is based on differential... 

Sampath, M., Aruputharaj, A., SenthiUcumar, M., Nalankilli, G., 2012. Analysis of thermal comfort characteristics of moisture management finished knitted fabrics made from different yams. J. Ind. Text. 42, 19-33. 

Existing methods for evaluation of the general thermal state of the body, both in comfort and under heat or cold stress, are based on an analysis of the heat balance for the human body ... 

Thermal analysis is carried out in order to find out whether the garment heats up above the level when the comfort of the user can be affected or it may provoke injuries. 

Queries intend to evaluate the individual perception of environmental comfort and physical fatigue. A higher number of subjects reveal discomfort when exposed to cold environment. In the query Analysis of Thermal Environment at Workstations, 4 in 13 subjects answered that they feel Very cold and 8 in 13 subjects Slightly Cold . 

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