Influence of sinusoidal airflow and airflow distance on human thermal response to a personalized ventilation system

2016 ◽  
Vol 27 (3) ◽  
pp. 317-330 ◽  
Author(s):  
Yongxin Xie ◽  
Sauchung Fu ◽  
Chili Wu ◽  
Christopher Y.H. Chao
Keyword(s):  
Thermal Comfort ◽  
Thermal Sensation ◽  
Human Subjects ◽  
Ventilation System ◽  
Thermal Response ◽  
Joint Effect ◽  
Experimental Conditions ◽  
Movement Perception ◽  
Air Movement ◽  
Personalized Ventilation

Since the concept of personalized ventilation was introduced in the late 1990s, many studies on thermal comfort have been conducted and a number of parameters identified. In this research, the influence of three parameters, the airflow speed, airflow fluctuating period and a parameter which has drawn less attention in previous studies – the airflow distance between the human subject and the nozzle of the personalized ventilation device on air movement perception, thermal sensation and thermal comfort – are studied. The combinations of fluctuating period and airflow amplitude were selected based on the Power Spectrum Density method. Then 25 human subjects participated in the thermal comfort experiment, each of them underwent 54 tests of different experimental conditions and expressed their thermal feelings by completing the survey questionnaire. Our findings showed that a longer airflow distance could lead to cooler thermal sensation, but not cause any difference in thermal comfort. Changing the fluctuating period of the sinusoidal airflow from 10 s to 60 s did not cause an influence on thermal sensation, but a shorter fluctuating period could result in a higher air movement perception. When dealing with thermal comfort issues, a joint effect with airflow speed and fluctuating period occurs and this should also be considered.

Human Perception Relation between Thermal Comfort and Air Movement for Ceiling Mounted Personalized Ventilation System

2014 ◽  
Vol 935 ◽  
pp. 329-332
Author(s):  
Bin Yang ◽  
Chandra Sekhar
Keyword(s):  
Thermal Comfort ◽  
Ventilation System ◽  
Human Perception ◽  
Office Work ◽  
Pv System ◽  
Movement Perception ◽  
Ambient Temperatures ◽  
Air Movement ◽  
Air Temperatures ◽  
Personalized Ventilation

As one kind of newly developed personalized ventilation (PV) system, the relation was explored between thermal comfort and air movement perception/acceptability/preference with tropical subjects, who had become passively acclimatized to hot conditions in the course of their day-to-day life. The tests were conducted in field environmental chamber (FEC) of National University of Singapore. 32 subjects (16 males and 16 females), performed normal office work, can choose to expose to four different PV airflow rates (4, 8, 12, 16 L/s) so as to simulating individual control. Ambient temperatures of 26°C and 23.5 °C and PV air temperatures of 26 °C, 23.5 °C and 21 °C were utilized to conduct parametric variation studies. Each combination was maintained for 15 minutes during which the subjects responded to computer-administered questionnaires. Under different PV airflow rates and ambient/PV temperature combinations, the relation between thermal comfort and air movement perception/acceptability/preference was analyzed.

scholarly journals An indoor environment evaluation by gender and age using an advanced personalized ventilation system

2017 ◽  
Vol 38 (5) ◽  
pp. 505-521 ◽  
Author(s):  
Ferenc Kalmár
Keyword(s):  
Air Quality ◽  
Thermal Comfort ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Side Effect ◽  
Thermal Sensation ◽  
Ventilation System ◽  
The Other ◽  
Air Velocity ◽  
Personalized Ventilation

In a closed space, appropriate thermal comfort and proper indoor air quality are extremely important in order to obtain the optimal work performance and to avoid health problems of the occupants. Using advanced personalized ventilation systems, different comfort needs can be locally satisfied even in case of warm environments. Thermal sensation and the subjective evaluation of indoor air quality of young and elderly people, men and women respectively, were studied in warm environment using advanced personalized ventilation system combined with total volume ventilation system. Using an advanced personalized ventilation system, 20 m3 h−1 air flow was alternately introduced by three air terminal devices built-in the desk and placed on a horizontal plane at the head level of the sitting subject. Thermal sensation was significantly cooler in case of young women in comparison with the other groups. Odor intensity was evaluated to be significantly lower in case of elderly women in comparison with the other groups. Evaluation of air freshness is in correlation with the general thermal sensation. Variation of the direction of the air velocity vector has a cooling side-effect, which, in warm environments, might be useful in order to improve the thermal comfort sensation. Practical application: From the basic factors that influence the thermal comfort sensation, air velocity is the one and only parameter that must be treated as a vector. The air flow velocity has an important effect on the convective heat quantity released by the human body, but the changes in the air velocity direction have a cooling side-effect. This cooling side-effect should be exploited properly in warm environments by advanced personalized ventilation systems to improve the thermal comfort sensation of the occupants without supplementary energy use.

scholarly journals Investigation of Thermal Comfort Responses with Fuzzy Logic

Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1792 ◽  
Author(s):  
József Menyhárt ◽  
Ferenc Kalmár
Keyword(s):  
Fuzzy Logic ◽  
Thermal Comfort ◽  
Thermal Sensation ◽  
Ventilation System ◽  
Elderly Persons ◽  
Comfort Index ◽  
Environment Quality ◽  
Personalized Ventilation ◽  
Internal And External Factors ◽  
The University

In order to reduce the energy consumption of buildings a series of new heating, ventilation and air conditioning strategies, methods, and equipment are developed. The architectural trends show that office and educational buildings have large glazed areas, so the thermal comfort is influenced both by internal and external factors and discomfort parameters may affect the overall thermal sensation of occupants. Different studies have shown that the predictive mean vote (PMV)—predictive percentage of dissatisfied (PPD) model poorly evaluates the thermal comfort in real buildings. At the University of Debrecen a new personalized ventilation system (ALTAIR) was developed. A series of measurements were carried out in order to test ALTAIR involving 40 subjects, out of which 20 female (10 young and 10 elderly) and 20 male (10 young and 10 elderly) persons. Based on the responses of subjects related to indoor environment quality, a new comfort index was determined using fuzzy logic. Taking into consideration the responses related to thermal comfort sensation and perception of odor intensity a new the fuzzy comfort index was 5.85 on a scale from 1–10.

scholarly journals Operation Testing of an Advanced Personalized Ventilation System

Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1596 ◽  
Author(s):  
Csáky ◽  
Kalmár ◽  
Kalmár
Keyword(s):  
Air Quality ◽  
Thermal Comfort ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Distribution System ◽  
Noise Level ◽  
Background Noise ◽  
Ventilation System ◽  
Air Distribution ◽  
Personalized Ventilation

Using personalized ventilation systems in office buildings, important energy saving might be obtained, which may improve the indoor air quality and thermal comfort sensation of occupants at the same time. In this paper, the operation testing results of an advanced personalized ventilation system are presented. Eleven different air terminal devices were analyzed. Based on the obtained air velocities and turbulence intensities, one was chosen to perform thermal comfort experiments with subjects. It was shown that, in the case of elevated indoor temperatures, the thermal comfort sensation can be improved considerably. A series of measurements were carried out in order to determine the background noise level and the noise generated by the personalized ventilation system. It was shown that further developments of the air distribution system are needed.

Performance of Mixing Ventilation System Coupled With Dynamic Personalized Ventilator for Thermal Comfort

2017 ◽  
Author(s):  
Douaa Al-Assaad ◽  
Nesreen Ghaddar ◽  
Kamel Ghali
Keyword(s):  
Thermal Comfort ◽  
Flow Rate ◽  
Thermal Sensation ◽  
Ventilation System ◽  
Low Frequency ◽  
Temperature Fields ◽  
Upper Body ◽  
Breathing Zone ◽  
Cfd Model ◽  
Mean Flow

This study optimizes the performance of a mixing ventilation system coupled with a personalized ventilator that emits a cool sinusoidal horizontal airflow jet towards the occupant upper body in order to achieve good overall thermal comfort and good air quality in the occupant breathing zone. A transient 3-D computational fluid dynamics (CFD) model coupled with a transient bio-heat model was deployed to predict airflow and temperature fields in the space and around the occupant as well as segmental skin temperature profiles for local and overall thermal sensation and comfort analysis. Simulations were performed using the CFD model to determine the airflow optimal supply frequency, mean flow rate and amplitude at room temperature of 25 °C and PV jet temperature of 22 °C. The system also showed, that when increasing frequency at fixed mean flow rate, thermal comfort increased from by 15.2 %. However when increasing mean flow rate at a fixed frequency, thermal comfort dropped at the low frequency of 0.3 Hz but remained acceptable at the higher frequency of 0.5 Hz.

scholarly journals Investigating Thermal Comfort for the Classroom Environment using IoT

2018 ◽  
Vol 9 (1) ◽  
pp. 157 ◽  
Author(s):  
Nurshahrily Idura Ramli ◽  
Mohd Izani Mohamed Rawi ◽  
Ahmad Zahid Hijazi ◽  
Abdullah Hayyan Kunji Mohammed
Keyword(s):  
Environmental Factors ◽  
Metabolic Rate ◽  
Thermal Comfort ◽  
Classroom Environment ◽  
Thermal Sensation ◽  
Influencing Factor ◽  
Physiological Factors ◽  
Clothing Insulation ◽  
Air Movement ◽  
Radiant Temperature

<p>In this modern century where fine comfort is a necessity especially in buildings and occupied space, the study to satisfy one aspect of human comfort is a must. This study encompasses of exploring the physiological and environmental factors in achieving thermal comfort which specifically considering the clothing insulation and metabolic rate of students as well as the deployment of dry-bulb temperature, mean radiant temperature, humidity, and air movement in order to obtain the level of comfort students are experiencing in class. The level of comfort are detected by using ASHRAE 55 to determine the average thermal sensation response through the Predicted Mean Vote (PMV) value. An android application were developed to read input of recognizing clothing level (thickness of clothing) and capturing metabolic rate to cater the inputs for physiological factors, while radiant temperature, humidity and air movement are captured through static sensors set up in the classroom space. This paper analyses both the physiological and environmental factors in affecting students in class and further determine their comfort levels that is a major influencing factor of focus in learning. Through cross referencing collected data from IoT enabled nodes, it is found that both physiological and environmental factors, and the combination of them greatly influence in getting the most comfortable state with PMV value of 0.</p>

scholarly journals Evaluation of Thermal Comfort in the Traditional Bourgeoisie Houses in Beirut

2020 ◽  
Vol 3 (1) ◽  
pp. p1
Author(s):  
Jad Hammoud ◽  
Elise Abi Rached
Keyword(s):  
Thermal Comfort ◽  
Natural Ventilation ◽  
Heat Waves ◽  
Thermal Environment ◽  
Thermal Sensation ◽  
Residential Buildings ◽  
Ventilation System ◽  
Electricity Consumption ◽  
Comfort Level ◽  
Climate Zones

The increasing of energy demands has considerably increased the requirements for new and traditional buildings in different climate zones. Unprecedented heat waves have increased climate temperature, in particular, in moderate climate zones such as Lebanon. In Beirut, only the residential sector consumes 50% of total electricity consumption. HVAC (Heating, Ventilation and Air conditioning) systems are used to reach acceptable thermal comfort levels in the new residential buildings. In case of the traditional bourgeoisie houses in Beirut, there are no discussions about the use of HVAC systems to achieve the required thermal comfort level. Thus, to reach an acceptable thermal comfort level, these houses which already contain natural ventilation system shall adapt the modern thermal comfort requirements and thermal comfort strategies and technologies where their architectural features and existing materials condition the available solutions. In order to identify the best options within the possible intervention lines (envelopes, passive strategies, equipment, renewable energy systems), it is necessary to perceive the real performance of this type of houses. In this context, the article presents the results of the study of thermal performance and comfort in a three case studies located in Beirut. Detailed field data records collected are analyzed, with a view to identify the indoor thermal environment with respect to outdoor thermal environment in different seasons. Monitoring also included measurement of hygrothermal parameters and surveys of occupant thermal sensation.

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