Performance of Intermittent Personalized Ventilation Assisting Mixing Ventilation in the Presence of Indoor Disturbance

2019 ◽  
Author(s):  
Douaa Al-Assad ◽  
Kamel Ghali ◽  
Nesreen Ghaddar
Keyword(s):  
Ventilation System ◽  
Pressure Gradients ◽  
Breathing Zone ◽  
Dynamics Model ◽  
Pv System ◽  
Low Frequencies ◽  
Air Ventilation ◽  
Airflow Field ◽  
Personalized Ventilation ◽  
Ventilation Systems

Abstract In this work, an office space is considered, equipped with an intermittent personalized ventilation (PV) system assisting a conventional mixing ventilation system. In ideal offices with no disturbances, it was proven that an intermittent PV average flow rate of 7.5 L/s and frequency of 0.86 Hz could enhance comfort compared to a steady PV and provide protection against contaminants present in the macroclimate. However, office spaces are subject to many disturbances, which could deteriorate the performance of air ventilation systems. In this work, an office door is considered to open disturbing the flow field by establishing pressure gradients. To conduct this study, a 3D computational fluid dynamics model was developed to predict the airflow field variables as well as contaminants’ concentration in the occupant-breathing zone. The model was used to assess the ability of the ventilation systems in maintaining its optimal operating parameters (0.86 Hz) obtained in ideal conditions. Results showed that the optimal PV frequency did not assure the same level of air quality. In fact, ventilation effectiveness decreased by 18% due to the opening door which pulled the PV jet away from the occupant’s breathing zone (BZ). Therefore, in office spaces with high disturbance levels, it is better off to operate the PV under steady state conditions to avoid further disturbance of the jet, or to operate the intermittent PV at low frequencies of 0.3 Hz to 0.5 Hz to minimize turbulence intensities created by the jet fluctuations.

scholarly journals Sistema de Ventilação Personalizada Instalado na Poltrona em Cabine de Aeronave: Análise da Concentração e da Eficiência na Remoção de Partículas Expiratórias

REVISTA PLURI ◽  
2020 ◽  
Vol 1 (3) ◽  
pp. 77
Author(s):  
Victor Barbosa Felix ◽  
Douglas Fabichack Jr. ◽  
Paulo Rogério Celline ◽  
Arlindo Tribess
Keyword(s):  
Air Quality ◽  
Removal Efficiency ◽  
Experimental Analysis ◽  
Ventilation System ◽  
Particle Removal ◽  
Pv System ◽  
Aircraft Cabins ◽  
Personalized Ventilation ◽  
Mode Of Transport ◽  
Ventilation Systems

As pessoas viajam cada vez mais de avião e, muitas vezes, estas viagens são longas. A qualidade do ar dentro desse meio de transporte torna-se então uma questão crucial, principalmente agora que o mundo está passando por uma pandemia causada pela COVID 19. Uma forma de melhorar a qualidade do ar e as condições de conforto térmico dentro de uma cabine de aeronave está na utilização de novos sistemas de ventilação personalizada. No presente trabalho é apresentada análise experimental da influência de um sistema de ventilação personalizada (PV) na concentração e na eficiência de remoção de partículas expiratórias em cabine de aeronave com sistema de ventilação convencional por mistura (MV). Os ensaios foram realizados em um mock-up com 12 lugares, com três fileiras de quatro poltronas. Medições de concentração de partículas foram realizadas na região de respiração, a 1,10m do piso, em todos os assentos da cabine. Os resultados mostram que a eficiência na remoção de partículas na região de respiração, considerando toda a cabine, é de até 25% para partículas de 5 a 10 μm e de até 30% para partículas de 2 a 5μm. Os resultados mostram também que a eficiência na remoção de partículas é praticamente igual para o sistema PV operando tanto no assento da janela quanto no assento do corredor para todos os tamanhos de partículas. Os resultados da eficiência de remoção de partículas mostram que o sistema PV influencia significativamente a remoção de partículas no assento no qual o sistema está operando e na cabine como um todo.Palavras-chave: Sistemas de Ventilação, Qualidade do Ar, Partículas Expiratórias, Análise Experimental, Cabines de AeronavesAbstractPeople travel more and more by plane, and often these trips are long. Air quality within this mode of transport then becomes a crucial issue, especially now that the world is experiencing a pandemic caused by COVID 19. A way to improve air quality and thermal comfort conditions inside a cabin of aircraft is in the use of new personalized ventilation systems. This work presents an experimental analysis of the influence of a personalized ventilation system (PV) on the concentration and efficiency of removal of expiratory particles in an aircraft cabin with a conventional mixing ventilation system (MV). The tests were carried out in a mock-up with 12 seats, three rows with four abreast. Measurements of particle concentration were performed in the breathing region, 1.10 m from the floor, in all seats of the cabin. The results show that the efficiency in removing particles in the breathing region, considering the entire cabin, is up to 25% for particles of 5 to 10 μm and up to 30% for particles of 2 to 5 μm. The results also show that particle removal efficiency is practically the same for the PV system operating on both the window seat and the aisle seat for all particle sizes. The results of particle removal efficiency show that the PV system significantly influences the removal of particles in the seat on which the system is perating and in the cab as a whole.Keyworks: Ventilation systems, Air Quality, Expiratory droplets, Experimental analysis, Aircraft cabins

scholarly journals LATENT HEAT ENERGY STORAGE DEVICE AS А PART OF THE VENTILATION SYSTEM OF INDIVIDUAL HOUSE

2017 ◽  
Vol 1 (48) ◽  
pp. 238-243
Author(s):  
B. A. Kutnyi ◽  
B. R. Novakh
Keyword(s):  
Energy Efficient ◽  
Heat Storage ◽  
Ventilation System ◽  
Heat Energy ◽  
Storage Device ◽  
Energy Prices ◽  
Air Ventilation ◽  
Seasonal Heat ◽  
Quantity Of Heat ◽  
Ventilation Systems

Energy efficient ventilation systems allow to minimize the heat energy consumption for heating supply air, which is very relevant in the context of rising energy prices. It is dealt with the variant of the installation seasonal phase-change heat storage device in the system of ventilation with recuperation of heat energy. Preliminary engineering calculations were perfomed and the quantity of heat storage material (water) necessary for the operation of the ventilation system was determined. The diagrams of change the temperature of the air at the output from the accumulator and distribution of water and ice during the heating period were given. In the article the calculation of seasonal heat storage device on the basis of the water in the supply air ventilation systems are considered , which allows to minimize costs of thermal energy for heating  the outside air before it enters to the premises of the house. It is proved that in modern economy conditions development the energy-efficient ventilation system is a promising direction of research and implementations.

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.

Effectiveness of Intermittent Personalized Ventilation Assisting Chilled Ceiling in Protecting Occupants Against Active Particles

2019 ◽  
Author(s):  
Douaa Al-Assad ◽  
Nesreen Ghaddar ◽  
Kamel Ghali
Keyword(s):  
Particle Diameter ◽  
Operating Conditions ◽  
Thermal Manikin ◽  
Breathing Zone ◽  
Pv System ◽  
Active Particles ◽  
Comfort Levels ◽  
Office Space ◽  
Personalized Ventilation ◽  
Chilled Ceiling

Abstract In this work, an intermittent personalized ventilation (PV) system was coupled with a chilled ceiling system in an office space. The ability of this system in protecting occupants from active particulate matter due to an indoor contamination source was investigated. To perform this study, a 3D transient computational fluid dynamics model was used to determine the velocity, thermal, and particle concentration fields in the space. The fluid flow in the space was experimentally validated in previous works in a climatic chamber equipped with a thermal manikin representing an occupant in an office space. The validated model was used to perform a parametric study varying the intermittent PV operating frequency as well as the particle diameter. The results were used to recommend PV operating conditions, which would ensure the protection of occupant against the contaminants present in the macroclimate and deposited on nearby surfaces. It was found that the intermittent PV should operate at an average flow rate of 7.5 L/s and a frequency of 0.73 Hz. These conditions provided acceptable values of intake fraction in the breathing zone and surrounding microclimate and acceptable deposited fractions. Moreover, these conditions provided good thermal comfort levels (0.86: comfortable) and good protection against passive contaminants (εv,BZ = 64 %).

Transport and trajectory of cough-induced bimodal aerosol in an air-conditioned space

2020 ◽  
pp. 1420326X2094116 ◽  
Author(s):  
Bo Zhang ◽  
Guangyu Guo ◽  
Chao Zhu ◽  
Zhiming Ji ◽  
Chao-Hsin Lin
Keyword(s):  
Ventilation System ◽  
Three Dimensional ◽  
Experimental System ◽  
Ambient Air ◽  
Lagrangian Model ◽  
Breathing Zone ◽  
Cfd Model ◽  
Ansys Fluent ◽  
Liquid Phases ◽  
Air Ventilation

Aerosol generated from a human cough can be a potential major indoor health risk due to the possible transmission of infectious respiratory diseases to surrounding individuals within the same room and even could spread out via air-ventilation/conditioning systems. This study aims to investigate the transport characteristics and trajectory of coughed aerosols under the influence of conditioned air ventilation as well as near-by human breathing zone using computational fluid dynamics (CFD). An experimental system consisting of air-conditioned space with multiple inlets and outlets, a cough simulator and a receiver was built to validate the CFD predictions. The comparison is in good agreement. The CFD model was established as a transient three-dimensional multiphase multicomponent Eulerian–Lagrangian model and numerically solved using commercial software ANSYS Fluent. Both gas and liquid phases were modelled as multicomponent mixtures. With this CFD model, the indoor transport and trajectory of coughed aerosols can be accounted for the distributions of portions inhaled by each manikin, deposited on surfaces of manikins and chamber walls, as well as recirculated back into the ventilation system. Results reveal that the aerosol source location and the ambient air movement can be crucial factors of aerosol trajectory in terms of direct and indirect influence.

Development of the Ventilation System in Historical Buildings of St. Petersburg

2014 ◽  
Vol 633-634 ◽  
pp. 977-981 ◽  
Author(s):  
Vera Murgul ◽  
Dusan Vuksanovic ◽  
Viktor Pukhkal ◽  
Nikolay Vatin
Keyword(s):  
Residential Buildings ◽  
Ventilation System ◽  
Heating System ◽  
Historic Buildings ◽  
Engineering Systems ◽  
Historical Buildings ◽  
Saint Petersburg ◽  
Air Ventilation ◽  
Ventilation Systems

The article presents an analysis of the primary technologies used to arrange air ventilation systems in residential buildings in Saint-Petersburg during the late 18th and early 20th centuries. The historic buildings construction and engineering systems is indisputable interest and can be subject to conservation of historic buildings in addition to conservation of architectural facades. The article analyzed historical techniques ventilation device in conjunction with the heating system.

scholarly journals Air quality and presence of air ventilation systems inside waterpipe cafés in North Carolina

2018 ◽  
Vol 28 (3) ◽  
pp. 356-358 ◽  
Author(s):  
Andrew B Seidenberg ◽  
Elizabeth N Orlan ◽  
Mark J Travers ◽  
Erin L Sutfin
Keyword(s):  
North Carolina ◽  
Air Quality ◽  
Fine Particulate Matter ◽  
Ventilation System ◽  
Before And After ◽  
Air Ventilation ◽  
Waterpipe Cafés ◽  
Time Periods ◽  
Starting Date ◽  
Ventilation Systems

BackgroundAfter North Carolina (NC) fire inspectors detected unsafe carbon monoxide (CO) levels inside several waterpipe cafés, the state fire code was amended to include provisions regulating waterpipe cafés, adding a requirement for air ventilation. These regulations apply to new buildings constructed after 1 January 2016, but can be enforced for older buildings where there exists a distinct hazard to life. We measured air quality at a sample of waterpipe cafés before and after the starting date of this regulation and collected information on presence of air ventilation.MethodsAir quality (CO, fine particulate matter (PM2.5)) monitoring was conducted inside and outside of six waterpipe cafés in NC in September of 2015 (time 1) and September of 2016 (time 2). In addition, questionnaires were administered to managers from each waterpipe café at time 2 to determine the presence of air ventilation systems.ResultsElevated levels of CO and PM2.5 were found inside waterpipe cafés at time 1 (median CO=42 ppm; median PM2.5=379.3 µg/m3) and time 2 (median CO=65 ppm; median PM2.5=484.0 µg/m3), with no significant differences between time periods (p>0.05). Indoor levels were significantly higher than levels outside cafés at both time periods (p<0.05). All waterpipe cafés reported having an air ventilation system that was installed prior to time 1 air monitoring.ConclusionsUnsafe levels of CO and PM2.5 were observed in waterpipe cafés in NC, despite reported use of air ventilation systems. Prohibiting indoor waterpipe smoking may be necessary to ensure clean air for employees and patrons.

scholarly journals RESEARCH OF APARTMENT BUILDINGS‘VENTILATION SYSTEMS AND ANALYSIS OF SYSTEM RENEWAL OPTIONS / DAUGIABUČIŲ GYVENAMŲJŲ NAMŲ VĖDINIMO TYRIMAI IR SISTEMŲ ATNAUJINIMO GALIMYBIŲ ANALIZĖ

2015 ◽  
Vol 7 (4) ◽  
pp. 484-492 ◽  
Author(s):  
Kęstutis Valančius ◽  
Sabina Paulauskaitė ◽  
Violeta Motuzienė
Keyword(s):  
Experimental Study ◽  
Mechanical Ventilation ◽  
Indoor Air ◽  
Natural Ventilation ◽  
Ventilation System ◽  
Heating Season ◽  
Apartment Buildings ◽  
Air Ventilation ◽  
Hygienic Conditions ◽  
Ventilation Systems

The paper presents experimental study of apartment buildings' ventilation parameters which was carried out during the heating season. The results show that the existing apartment buildings often don‘t guarantee the hygienic conditions that are directly related to the indoor air ventilation. Also article contains an analysis of possibilities to upgrade the ventilation systems of apartment buildings. Four ventilation systems‘ upgrade options were examined. The economic analysis showed that according to the economic aspect the best solution for mechanical ventilation in the typical apartment houses is a centralized ventilation system which operates in combination with ground heat pump when supply ducts are mounted on the building facade, and extraction takes place at existing natural ventilation system channels. Straipsnyje pateikiami daugiabučių gyvenamųjų namų vėdinimo parametrų eksperimentiniai tyrimai, kurie buvo atlikti šildymo sezono metu. Tyrimų rezultatai rodo, kad esamuose daugiabučiuose namuose dažniausiai nėra užtikrinamos higieninės sąlygos, kurios yra tiesiogiai susijusios su šių namų vėdinimu. Taip pat straipsnyje pateikiama daugiabučio vėdinimo sistemų atnaujinimo galimybių analizė. Ekonomiškai išnagrinėti keturi vėdinimo sistemų atnaujinimo variantai. Atlikus ekonominę analizę, nustatyta, jog ekonominiu aspektu geriausias mechaninio vėdinimo sprendimas tipiniame daugiabučiame name yra centralizuota vėdinimo sistema, veikianti kombinuotai su gruntiniu šilumos siurbliu, kai tiekiamieji ortakiai montuojami ant pastato fasadų, o ištraukimas vyksta esamais natūralios vėdinimo sistemos kanalais.

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