505 research outputs found

    Improving predicted mean vote with inversely determined metabolic rate

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    Inaccurate thermal comfort prediction would lead to thermal discomfort and energy wastage of overcooling/overheating. Predicted Mean Vote (PMV) is widely used for thermal comfort management in air-conditioned buildings. The metabolic rate is the most important input of the PMV. However, existing measurements of the metabolic rate are practically inconvenient or technically inaccurate. This study proposes a method to improve the PMV for the thermal sensation prediction by inversely determining the metabolic rate. The metabolic rate is expressed as a function of the room air temperature and velocity considering the effects of the physiological adaptation, and inversely determined using an optimizer (variable metric algorithm) to reduce the deviation between the PMV and thermal sensation vote. Experiments in environmental chambers configured as a stratum ventilated classroom and an aircraft cabin and field experiments in a real air-conditioned building from the ASHRAE database validate the proposed method. Results show that the proposed method improves the accuracy and robustness of the PMV in the thermal sensation prediction by more than 52.5% and 41.5% respectively. Essentially, the proposed method develops a grey-box model using model calibration, which outperforms the black-box model using machine learning algorithms

    Aerospace Medicine and Biology: A continuing bibliography with indexes

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    This bibliography lists 253 reports, articles, and other documents introduced into the NASA scientific and technical information system in October 1975

    Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 212

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    A bibliography listing 146 reports, articles, and other documents introduced into the NASA scientific and technical information system is presented. The subject coverage concentrates on the biological, psychological, and environmental factors involved in atmospheric and interplanetary flight. Related topics such as sanitary problems, pharmacology, toxicology, safety and survival, life support systems, and exobiology are also given attention

    Educational tool for the learning of thermal comfort control based on PMV-PPD indices

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    In this paper, an interactive educational tool designed for the learning of thermal comfort concepts is presented. Thermal comfort is one of the fundamental aspects of indoor environmental quality and energy savings in buildings. Comfort-based control and energy management constitute an important emergent sub-discipline of engineering studies. The developed tool allows for the definition of the thermal model of a house. Based on this model, thermal comfort is estimated through the predicted mean vote (PMV) and predicted percentage dissatisfied (PPD) indices, and energy consumption is also calculated. The tool can communicate through Modbus TCP/IP protocol, providing external connectivity and data collection from the different sensors available in a building management system (BMS). In this way, it is possible to calculate in real-time the aforementioned comfort indices and propose corrective control indications to maintain the indoor-air conditions inside the optimal comfort range. A simple control strategy that can be applied to conventional HVAC systems is also addressed. The tool is available for degree students in control engineering. A survey was performed to evaluate the effectiveness of the proposed tool

    Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 187

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    This supplement to Aerospace Medicine and Biology lists 247 reports, articles and other documents announced during November 1978 in Scientific and Technical Aerospace Reports (STAR) or in International Aerospace Abstracts (IAA). In its subject coverage, Aerospace Medicine and Biology concentrates on the biological, physiological, psychological, and environmental effects to which man is subjected during and following simulated or actual flight in the earth's atmosphere or in interplanetary space. References describing similar effects of biological organisms of lower order are also included. Emphasis is placed on applied research, but reference to fundamental studies and theoretical principles related to experimental development also qualify for inclusion. Each entry in the bibliography consists of a bibliographic citation accompanied in most cases by an abstract

    The Effects of Exhaust Vent Location on Thermal Comfort Inside the Residential Buildings Equipped With an Evaporative Cooling System

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    Inlet and outlet conditions, Including size and location, have significant effects on the air distribution, temperature, humidity and thermal comfort in the buildings. In the current study, various strategies are presented for exhaust air vents and the effects of inlet and outlet vents locations are evaluated on providing thermal comfort in the residential and industrial buildings. To provide thermal comfort, three key factors need to be investigated based on ASHRAE standard 55- 2013 as follows: Comfort Zone, Thermal Sensation and Draft Rate. Flow distribution is studied as well in order to investigate the strategies, which make more vorticity in the ventilated air in living spaces as a factor of increasing discomfort in the building. The case study is located in Las Vegas where the weather is hot and dry in the summer time and the relative humidity is less than 8 %. In this regard, an evaporative cooling system is considered to increase humidity in the building since not only lack of humidity cause discomfort but also has many effects on breathing and skin dryness. A Computational Fluid Dynamic (CFD) study is developed as a numerical solution for obtaining temperature profile, relative humidity profile in different sections of the building regarding the evaluation of Thermal comfort in most critical spaces. In this study, relative humidity definition is formulated and imported as a field function in STAR-CCM+ to track relative humidity in each points of the building. As the temperature of ventilated air increases by absorbing heat, the percentage of relative humidity will be decreased consequently inside the building. By evaluating various strategies of exhaust vents in different hours of the day, it can be concluded that the thermal comfort will be provided most appropriate if the exhaust vents in each room are on the intersection of ceiling with the middle of farthest walls from the room’s entrance in a building with a single evaporative cooler. The results presented in this study can be used in the design of air conditioning systems in residential and industrial buildings, which leads to improvement in performance of air conditioning systems without any extra expenses

    Aerospace Medicine and Biology: a Continuing Bibliography with Indexes (Supplement 328)

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    This bibliography lists 104 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during September, 1989. Subject coverage includes: aerospace medicine and psychology, life support systems and controlled environments, safety equipment, exobiology and extraterrestrial life, and flight crew behavior and performance

    Aerospace medicine and biology: A continuing bibliography with indexes, supplement 183

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    This bibliography lists 273 reports, articles, and other documents introduced into the NASA scientific and technical information system in July 1978

    EFFECT OF RELATIVE HUMIDITY AND TEMPERATURE CONTROL ON IN-CABIN THERMAL COMFORT STATE

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    This dissertation discusses the effect of manipulating the relative humidity RH levels inside vehicular cabins on the thermal comfort and human occupants\u27 thermal sensation. Three different techniques are used to investigate this effect. Firstly, thermodynamic and psychometric analyses are used to incorporate the effect of changing RH along with the dry bulb temperature on the human comfort window. Specifically, the study computes the effect of changing the relative humidity on the amount of heat rejected from the passenger compartment and the effect on occupants comfort zone. A practical system implementation is also discussed in terms of an evaporative cooler design. Secondly, a 3-D finite difference simulation is used to predict the RH effects on the thermal sensation metrics. The study uses the Berkeley and the Fanger models to investigate the human comfort using four specific perspectives; (i) the effect on other environmental conditions, (ii) the effect on the body segments temperature variation within the cabin, (iii) the cabin local sensation (LS) and comfort (LC) for the different body segments; in addition to the overall sensation (OS) and overall comfort (OC), (iv) the human sensation is also measured by the Predicted Mean Value (PMV) and the Predicted Percentage Dissatisfied (PPD) indices during the summer and the winter periods following the Fanger model calculations. Thirdly, the analysis and modeling of the vehicular thermal comfort parameters is conducted using a set of designed experiments aided by thermography measurements. The experiments employed a full size climatic chamber to host the test vehicle, to accurately assess the transient and steady state temperature distributions of the test vehicle cabins. The experimental and simulation work show that controlling the RH levels along with the Dry Bulb Temperature helps the A/C system achieve the human comfort zone faster than the case if the RH value is not controlled. Also, the results show that changing the RH along with Dry Bulb Temperature inside vehicular cabins can improve the air conditioning efficiency by reducing the amount of heat removed. Finally, this work has developed the passenger thermal-comfort psychometric zones during summer and winter periods using Berkeley and Fanger models

    Temperature and comfort monitoring systems for humans

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    PhDThermoregulation system and human body responses, both physiological (i.e. skin and core temperature) and psychological (thermal sensation and thermal comfort), have been of considerable interest to researchers. However, while reactions to extreme conditions are well understood and explained, there is a considerable knowledge gap for mild temperature range adaptation. Previous research focused on the whole body response, while local analysis is more appropriate for a new generation of intelligent thermal control systems such as needed in planes. Furthermore majority of previous studies were carried out predominantly on mannequins or with subjects placed in highly controlled lab chambers, hence adaptations in normal shared spaces is not investigated in sufficient depth. In addition, no study investigated infants’ temperature adaptation. This thesis describes the comprehensive study of the human temperature distribution in selected areas, both for adults and infants under the age of 2. Furthermore, variation of core and local skin temperature, thermal sensation and level of comfort due to long periods of inactivity were also investigated in adults. These studies have set the basis for the development of temperature monitoring systems. The first monitoring system specific to children under 2 provides fever detection based on skin temperature measurement. It was developed for a Spanish textile company (AITEX), and it is a patent under consideration. The second system monitors level of comfort and thermal sensation of adults in indoor environments. The system is based on pre-existing statistical studies and Fanger’s steady-state model. It adapts to the individual while analysing real time skin temperature distribution, and identifie
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