scholarly journals Coupling of differential CFD and integral human thermophysiology numerical models applied in indoor ventilated spaces

2021 ◽  
Vol 321 ◽  
pp. 03002
Author(s):  
Eusébio Conceição ◽  
João Gomes ◽  
M. Manuela Lúcio ◽  
M. Inês Conceição ◽  
André Ramos ◽  
...  
Keyword(s):  
Air Quality ◽  
Thermal Comfort ◽  
Numerical Models ◽  
Exhaust System ◽  
Comfort Level ◽  
Experimental Chamber ◽  
Airflow Rate ◽  
Inlet System ◽  
Computer Fluid Dynamics ◽  
Air Diffusion

This work presents the development of the coupling of differential Computer Fluid Dynamics and integral human thermo-physiology numerical models applied in indoor ventilated spaces. The study is performed in a virtual chamber, similar to an existing experimental chamber, with dimensions of 4.50×2.55×2.50 m3. The chamber, occupied with twelve virtual manikins, is equipped with six tables, twelve chairs, one exhaust system and one inlet system, based on confluents jets system. In the exhaust system, they are considered six air ducts, located above the head level, connected to the ceiling area. The inlet system, based in four vertical ducts, with 0.15 m diameter, located on the corners of the chamber, is equipped with consecutive holes, that promotes horizontal jets near the wall. The results demonstrate that when the airflow rate increases the air quality number increases, the thermal comfort number decreases, and the Air Diffusion Index increases slightly. The predicted percentage of dissatisfied index values show that the thermal comfort level of occupants is acceptable, the dioxide carbon concentration values show that the indoor air quality is near the acceptable value and the Draught Risk is acceptable.

scholarly journals Application of Horizontal Confluents Jets in a School Virtual Chamber

2021 ◽  
Vol 246 ◽  
pp. 02005
Author(s):  
Eusébio Conceição ◽  
Mª Inês Conceição ◽  
João Gomes ◽  
Mª Manuela Lúcio ◽  
Hazim Awbi
Keyword(s):  
Air Quality ◽  
Thermal Comfort ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Exhaust System ◽  
Comfort Level ◽  
Experimental Chamber ◽  
Airflow Rate ◽  
Inlet System ◽  
Head Level

The study presented in this work is performed in a virtual chamber, similar to an existing experimental chamber, with dimensions of 4.50×2.55×2.50 m3. The chamber, occupied with twelve virtual manikins, is equipped with six tables, twelve chairs, one exhaust system and one inlet system, based in confluents jets system. In the exhaust system are considered six air ducts, located above the head level, connected to the ceiling area. The inlet system, based in four vertical ducts, with 0.15 m diameter, located on the corners of the chamber, are equipped with consecutive holes, that promotes horizontal jets near the wall. The results demonstrate that when the airflow rate increases the air quality number increases, the thermal comfort number decreases and the ADI increases slightly. The predicted percentage of dissatisfied index values show that the thermal comfort level is acceptable, the dioxide carbon concentration values show that the indoor air quality is near the acceptable value and the Draught Risk is acceptable.

scholarly journals Comparative Study of a Clean Technology Based on DSF Use in Occupied Buildings for Improving Comfort in Winter

2021 ◽  
Vol 3 (2) ◽  
pp. 311-334
Author(s):  
Eusébio Conceição ◽  
João Gomes ◽  
Maria Manuela Lúcio ◽  
Maria Inês Conceição ◽  
Hazim Awbi
Keyword(s):  
Air Quality ◽  
Comparative Study ◽  
Thermal Comfort ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Thermal Response ◽  
Clean Technology ◽  
Comfort Level ◽  
Airflow Rate ◽  
Winter Conditions

This paper presents a comparative study of a clean technology based on a DSF (double skin facade) used in winter conditions in the occupied buildings comfort improvement, namely the thermal comfort and air quality. The performance of a solar DSF system, the building’s thermal response, the internal thermal comfort and the internal air quality are evaluated. In this study, a DSF system, an air transport system and a HVAC (heating, ventilating and air conditioning) system based on mixing ventilation are used. The study considers a virtual chamber occupied by eight persons and equipped, in the outside environment, by three DSFs. A new horary pre-programming control methodology is developed and applied when the airflow rate is constant and the number of DSFs to operate is variable, when the airflow rate is variable and the number of DSFs to operate is constant and when the airflow rate is variable and the number of DSFs to operate is variable. This work uses a numerical model that simulates the integral building thermal behavior and an integral human thermal response. The internal air, provided by a mixing ventilating system, is warmed using the DSF system. The air temperature inside the DSF system and the virtual chamber, the thermal comfort level using the PMV index, the internal air quality using the carbon dioxide concentration and the uncomfortable hours are calculated for winter conditions. The results obtained show that the energy produced in the DSF, using solar radiation, guarantees acceptable thermal comfort conditions in the morning and in the afternoon. The indoor air quality obtained at the breathing level is acceptable. It is found that the airflow rate to be used is more decisive than the DSF operating methodology. However, when a solution is chosen that combines a ventilation rate with the number of DSF to operate, both variables throughout the day can obtain simultaneously better results for indoor air quality and thermal comfort according to the standards.

Application of solar radiation to the ventilation of an experimental chamber through a set of dual skin facades

2020 ◽  
pp. 25-35
Author(s):  
Eusébio Conceição ◽  
João Gomes ◽  
Mª Manuela Lúcio ◽  
Mª Inês Conceição ◽  
Hazim Awbi
Keyword(s):  
Air Quality ◽  
Thermal Comfort ◽  
Indoor Air Quality ◽  
Integral Equations ◽  
Indoor Air ◽  
Carbon Dioxide Concentration ◽  
Integral Model ◽  
Experimental Chamber ◽  
Airflow Rate ◽  
Numerical Work

The aim of this numerical work is to evaluate the influence of a set of three Dual Skin Façades (DSF) on the thermal comfort and air quality inside a virtual occupied experimental chamber under various airflow rates. Each DSF is constituted by two transparent glasses and an adjustable venetian blind located in the air channel existing between the two surfaces. A system of energy balance integral equations is used to estimate the air temperature inside the virtual chamber and DSF and the temperature in the different elements of the virtual chamber and a system of mass balance integral equations is used to estimate the contaminants inside the virtual chamber and the DSF. The uncomfortable hours integral model is used to evaluate the total number of uncomfortable hours due to warm and cold indoor conditions and also due to indoor air quality conditions. The acceptable levels of indoor thermal comfort, evaluated by the Predicted Mean Vote index, must be within category C of ISO 7730 standard. The acceptable levels of indoor air quality, evaluated by the carbon dioxide concentration, must be below the limit of 1800 mg/m3 proposed by the ASHRAE 62.1 standard. Three airflow rates were chosen: 0.0389 m3/s, 0.0778 m3/s and 0.1167 m3/s. The airflow that guarantees, at the same time, the best indoor air quality and thermal comfort levels is obtained through the minimization of the total number of uncomfortable hours. As best option, it was obtained the airflow rate of 0.1167 m3/s.

Numerical study of different ceiling-mounted air distribution systems for a virtual classroom environment

2016 ◽  
Vol 26 (10) ◽  
pp. 1382-1396 ◽  
Author(s):  
Eusébio Z. E. Conceição ◽  
Cristina I. M. Santiago ◽  
Hazim B. Awbi
Keyword(s):  
Air Quality ◽  
Thermal Comfort ◽  
Air Temperature ◽  
Distribution Systems ◽  
Numerical Study ◽  
Virtual Classroom ◽  
Comfort Level ◽  
Air Distribution ◽  
Air Supply ◽  
Distribution Index

This paper presents a comparative numerical study of different ceiling-mounted-localized air distribution systems placed above students in a virtual classroom in summer conditions. The influence of four different ceiling-mounted-localized air distribution systems, using vertical descendent jets, on the thermal comfort, local thermal discomfort, and air quality levels was numerically evaluated. The air distribution index, developed previously, was used for non-uniform environment. This index considers the thermal comfort level, air quality level, effectiveness for heat removal, and effectiveness for contaminant removal. Numerical simulations were conducted for a virtual classroom equipped with one of four different ceiling-mounted-localized air distribution systems and with 6 desks, 6 or 12 students, and 2 upper airflow outlets. Inlet air supply temperature of 20 and 24℃ and an outdoor air temperature of 28℃ were used. The simulation results show that the air supply system having a vertical air jet placed at 1.8 m above the floor level (Case III), and with an inlet area of 0.01 m2 and a supply air velocity of 3 m/s would represent the best option in comparison with other air supply methods. In general, the air distribution index value decreases with an increase in inlet air temperature and the number of occupants. The air distribution index values are highest for Case III representing a classroom with 6 or 12 occupants with an inlet air temperature of 20 or 24℃.

Requirements of Air-Conditioning Systems’ Developments in Hospitals and Critical Healthcare Facilities

Volume 3 ◽  
2004 ◽  
Author(s):  
Essam E. Khalil ◽  
Ramiz Kameel
Keyword(s):  
Energy Consumption ◽  
Air Quality ◽  
Thermal Comfort ◽  
Air Conditioning ◽  
Hvac Systems ◽  
Comfort Level ◽  
Current Status ◽  
Healthcare Applications ◽  
Healthcare Facilities ◽  
Intelligent Technique

The balance between thermal comfort and air quality in healthcare facilities to optimize the Indoor Air Quality (IAQ) is the main aim of this paper. The present paper will present this balance from the viewpoint of the air conditioning design. It was found that the design of the HVAC airside systems plays an important role for achieving the optimum air quality beside the optimum comfort level. This paper highlights the importance of the proper airside design on the IAQ. The present paper introduces some recommendations for airside designs to facilitate the development of optimum HVAC systems. This paper also stresses on the factors that improve the thermal comfort and air quality for the already existed systems (for maintenance procedure). To design an optimum HVAC airside system that provides comfort and air quality in the air-conditioned spaces with efficient energy consumption is a great challenge. The present paper defines the current status, future requirements, and expectations. Based on this analysis and the vast progress of computers and associated software, the artificial intelligent technique will be a competitor candidate to the experimental and numerical techniques. Finally, the researches that relate between the different designs of the HVAC systems and energy consumption should concern with the optimization of airside design as the expected target to enhance the indoor environment. The present paper reviews the results of recent advances that are concerned with the HVAC design engineering in the healthcare applications. The following requirements are necessary for Health and hygiene considerations: • Air movements are to be restricted in and between the various hospital departments (no cross movement). • Appropriate ventilation and filtration is used to dilute and reduce contamination in the form of odour, air-borne micro organisms, viruses, hazardous chemical and radioactive substances. • Temperature and relative humidity are to be regulated and attained for various medical areas. • Environmental compliance conditions should be maintained, accurately controlled and monitored.

scholarly journals Application of passengers’ thermoregulation integral model used in the evaluation of thermal comfort in vehicles compartment equipped with internal curtains

2021 ◽  
Vol 321 ◽  
pp. 03008
Author(s):  
Eusébio Conceição ◽  
João Gomes ◽  
M. Manuela Lúcio ◽  
M. Inês Conceição ◽  
André Ramos ◽  
...  
Keyword(s):  
Numerical Model ◽  
Thermal Comfort ◽  
Numerical Study ◽  
Numerical Models ◽  
Thermal Response ◽  
Grid Generation ◽  
The Body ◽  
Comfort Level ◽  
Integral Model ◽  
Shading Devices

This work evaluates the passengers thermal comfort level inside a vehicles compartment. The numerical study, made in winter conditions, consider a bus indoor environment equipped with internal curtains, internal seats, lateral panels, ceiling, floor and occupied by 52 passengers. The numerical model considers the passengers and vehicle grid generation, passengers body and clothing thermal response and passengers thermal comfort level. The grid generation is used to evaluate the view factors and Mean Radiant Temperature that the passengers are subjected. In this calculus the passengers and the vehicles surfaces shading devices are considered. The thermal response numerical models consider the energy and mass balance integral equations. The thermal comfort evaluation considers the heat produced inside the body and the heat exchange between the body and the environment. The human body numerical model considers also the thermoregulatory system to control the temperature. The numerical model is used to evaluate the thermal comfort level that seated passengers are subjected in a bus equipped with asymmetrical warm curtains. Three Cases studies were developed: the first one considers the temperature curtains equal to the indoor bus surfaces, while the other two consider higher temperatures values. All Cases are thermally comfortable according to the standards.

scholarly journals Thermal comfort analysis in office buildings with different air-conditioning systems

2018 ◽  
Vol 9 (1) ◽  
pp. 59-63 ◽  
Author(s):  
J. Szabo ◽  
L. Kajtar
Keyword(s):  
Air Quality ◽  
Thermal Comfort ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Air Conditioning ◽  
Carbon Dioxide Concentration ◽  
Comfort Level ◽  
Office Buildings ◽  
Ducted Fan ◽  
Air Conditioning Systems

It is a prime aim to ensure a suitable comfort level in case of office buildings. The productivity of office employees is directly influenced by the comfort. Thermal discomfort and poor indoor air quality deteriorate the intensity and quality of human work. We investigated the comfort in office buildings with on-site measurements during the summer season. The office buildings were operating with different HVAC (Heating, Ventilating and Air-Conditioning) systems: ducted fan-coil with suspended ceiling, installation, non-ducted fan-coil with floor-mounted installation, active chilled beam with fresh air supply. We evaluated the thermal comfort under PMV (Predicted Mean Vote), PPD (Predicted Percentage of Dissatisfied), the local discomfort based on DR (Draught Rate) and the IAQ (Indoor Air Quality) based on carbon dioxide concentration. The comfort measurements were evaluated. The measurements were evaluated with scientific research methods, comfort categories based on the requirements of CR 1752. The results of this comparison were presented in this article.

Evaluation of comfort levels in office space equipped with HVAC system based in personalized ventilation system using energy produced in DSF systems

2020 ◽  
pp. 65-74
Author(s):  
Eusébio Conceição ◽  
Mª Inês Conceição ◽  
Mª Manuela Lúcio ◽  
João Gomes ◽  
Hazim Awbi
Keyword(s):  
Air Quality ◽  
Numerical Model ◽  
Thermal Comfort ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Numerical Study ◽  
Ventilation System ◽  
Airflow Rate ◽  
Hvac System ◽  
Personalized Ventilation

In this study the numerical simulation of a Heating, Ventilating and Air Conditioning (HVAC) system, based in a personalized ventilation system, installed in an occupied office desk is made. The energy is produced in a Dual Skin Facades (DSF) system installed in the outdoor environment. The personalized ventilation system, placed above and below the writing area, installed in the desk central area. The office desk is occupied by eight virtual manikins. The numerical simulation is made in a winter typical day. This numerical study considers a coupling of a differential numerical model and an integral numerical model. The differential numerical model simulates the Computational Fluids Dynamics (CFD), evaluates the air velocity, air temperature, turbulence intensity and carbon dioxide concentration and calculates the indoor air quality. The integral numerical model simulates the Multi-Node Human Thermo-physiology Model, evaluates the tissue, blood and clothing temperatures distribution and calculates the thermal comfort level. The HVAC system, based on a DSF system, is built using three DSF unities, is equipped with internal venetian blinds. Each one, installed in a virtual chamber, is turned to south. The personalized ventilation system, made with eight upper and eight lower air terminal devices, is installed in the desk central area. On each table top two upper and two lower air terminal devices are considered in the left and right manikin area, while on each side of the table two upper and two lower air terminal devices are placed between the manikins. The office desk is occupied by eight virtual manikins, one sitting on each table top and three sitting on each side of the meeting table. In this numerical study, carried out in winter conditions, the occupants’ clothing level is 1 clo. In these situations a typical activity level of 1.2 met is considered. The evolution of indoor environmental conditions, in the DSF and in the office room, are calculated during a full winter typical day. The thermal comfort, the indoor air quality, the effectiveness for heat removal, the effectiveness for contaminant removal and the Air Distribution Index (ADI), are evaluated. In accordance with the obtained results the thermal comfort levels increase when the air renovation rate increases and the indoor air quality level increases when the air renovation rate increases. However, the ADI is quite constant when the inlet airflow rate increases, because the thermal comfort number decreases when the inlet airflow rate increases and the air quality number increases when the inlet airflow rate increases.

scholarly journals INDOOR AIR QUALITY STUDY ON COASTAL BAILEO IN WEST SERAM, MALUKU

2021 ◽  
Vol 47 (1) ◽  
pp. 35-42
Author(s):  
Purnama Esa Dora Tedjokoesoemo ◽  
Felicia Jane Thendean
Keyword(s):  
Air Quality ◽  
Thermal Comfort ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Quantitative Research ◽  
Comfort Level ◽  
Physical Factors ◽  
Air Velocity ◽  
Chemical Factors ◽  
Physical And Chemical

Thermal comfort is one of the most influencing aspects to affect comfort level in interior. Indoor Air Quality (IAQ) is one part of thermal comfort parametric often suggested in any building assessment for its role to affect health and comfort. IAQ is influenced by physical factors (temperature, air humidity and air velocity) and chemical factors (in the form of substances in the air). Traditional buildings in Indonesia, has long since consider IAQ in its passive design approach, one of them is in Baileo. This paper reports an investigation of IAQ in coastal Baileo in West Seram, Maluku. This quantitative research is conducted in method comparative analysis method. This paper discusses the relation between IAQ in Baileo to building formation and materials selection. The measurement done show that IAQ in coastal Baileo in West Seram has good performance on both physical and chemical factors.

Development and application of an integrated virtual thermal-acoustic manikin design used inside an office space

2021 ◽  
Vol 263 (2) ◽  
pp. 4226-4237
Author(s):  
Eusebio Conceição ◽  
Mª Ines Conceição ◽  
Mª Manuela Lúcio ◽  
João Gomes
Keyword(s):  
Air Quality ◽  
Thermal Comfort ◽  
Sound Propagation ◽  
Ventilation System ◽  
Comfort Level ◽  
Quality Level ◽  
Thermal Manikin ◽  
Reverberation Time ◽  
Surrounding Space ◽  
Personalized Ventilation

In this study an integrated virtual thermal-acoustic manikin design used inside ventilated and occupied office spaces is developed and applicated. The component of the virtual thermal manikin evaluates the internal airflow and occupants' thermal, thermo-physiology and clothing systems and calculates the thermal comfort and the indoor air quality levels. The component of the virtual binaural manikin evaluates the direct and indirect sound and calculates the reverberation time. The space geometry with complex topology is developed using a Computer Aid Design (CAD), while the occupants' geometry is made using geometric equations. The grid generation, in the surrounding space surfaces and around the external occupants' surfaces geometry, is used to calculate the radiative heat exchanges and the sound propagation. In this study, performed in an office room occupied by eight persons and equipped with personalized ventilation system, the thermal comfort level, the air quality level and the space reverberation time is evaluated and discussed. In accordance with the obtained results the values are, in general, in accordance the actual standards.

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