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- Study on thermal comfort by using an atmospheric pressure dependent predicted mean vote indexPublication . Ruivo, Celestino; Gameiro da Silva, Manuel; Broday, Evandro EduardoThe thermal environment index Predicted Mean Vote is a descriptor largely applied to evaluate the comfort sensation of people in moderate environments. Software tools based on the Fanger's method have been created and used, which application is limited for the sea level atmospheric pressure. A procedure for estimating the index of thermal comfort of individuals in environments at air pressure different from barometric pressure 0 m of altitude was recently introduced. In present study, indoor air state associated with neutral thermal comfort conditions of individuals in seating activity are predicted for atmospheric pressure values in the range between 65.0 kPa and 101.3 kPa. It was observed that neutral temperature diminishes with the decrease of barometric pressure. Dependencies of index PMV on the activity level, the clothing insulation, relative, air velocity and on relative humidity for two atmospheric pressure values are investigated. It is concluded that the impact of pressure of the environment on the index of thermal comfort must be also considered when sizing an air-conditioning system.
- Methodology for calculating an atmospheric pressure-sensitive thermal comfort index PMVapsPublication . Ruivo, Celestino; da Silva, Manuel Gameiro; Broday, Evandro EduardoSeveral software tools have been created to calculate the indices Predicted Mean Vote (PMV) and Predicted Percentage of Dissatisfied (PPD) by following Fanger's method, which is valid only for atmospheric pressures close to 1 atm. The main objective of this work is to propose a formulation named PMV-PS for predicting an atmospheric pressure-sensitive thermal comfort index (PMVaps). The effort conducted by the authors was focused on the identification of the variables and expressions used in the calculation of thermal comfort index that may be affected by the change of the atmospheric pressure. The best known formulations for each individual aspect were introduced in the new model. It has been calibrated with data at sea level and tested for a set of cases considering different values of metabolic activity rate, thermal resistance of clothing and environmental parameters. At sea level there are negligible differences between PMV and PMVaps. However, when atmospheric pressure deviates from 1 atm, large differences between PMV and PMVaps are observed. PMV-PS model is a good starting point for further investigations into the influence of atmospheric pressure on thermal comfort perception and assessment, under real conditions, or using hypobaric chambers. Moreover, due to the subsisting doubts resulting from the analysis of published studies, it is crucial to perform further experimental work with high statistical significance i) to test the validity of the adopted correlations for the relationship between metabolic rate and atmospheric pressure and ii) to investigate in deep thermal comfort sensation of individuals used to live at altitude and of individuals with short-term exposure to an environment different from what they are used to live. Based upon the main findings of the present work, not considering the atmospheric pressure effect in PMV index may lead to significant errors. (C) 2021 Elsevier B.V. All rights reserved.
- The use of Monte Carlo method to assess the uncertainty of thermal comfort indices PMV and PPD: Benefits of using a measuring set with an operative temperature probePublication . Broday, Evandro Eduardo; Ruivo, Celestino; Silva, Manuel Gameiro daThe Predicted Mean Vote (PMV) and Predicted Percentage of Dissatisfied (PPD) are the most used indices for the assessment of thermal conditions in indoor environments. However, many times, the uncertainties associated with the calculation of both indices are not reported, may be because direct methods are not easily applicable to calculate it. The present study applies Monte Carlo method to assess the uncertainties on the calculation of PMV and PPD, as a function of values and the uncertainties of four environmental (air temperature, mean radiant temperature, air velocity, and partial vapour pressure) and two individual related input parameters (metabolic rate and clothing insulation), used in Fanger's model, to calculate it. The metrological quality of the measuring probes was assumed through the scenarios established by ISO 7726 (1998) (required and desirable conditions). The use of uncertainties values for metabolic rate, clothing insulation and operative temperature were also considered. The main findings of this research are: (i) condition defined as required is not suitable for implementation of the classification scheme of thermal environments proposed by ISO 7730 (2005); (ii) in desirable condition, it is unrealistic obtaining an uncertainty of 0.2 degrees C for mean radiant temperature, if a 0.2 degrees C uncertainty temperature probe is used; (iii) the use of an operative temperature probe is a good strategy to decrease the overall level of uncertainty in the indices.