Numerical study and optimization of air-conditioning systems grilles used in indoor environments

2021 ◽  
Author(s):  
Luis Angeles-Rodríguez ◽  
Cesar Celis
Keyword(s):  
Air Conditioning ◽  
Numerical Study ◽  
Indoor Environments ◽  
Air Conditioning Systems

A dynamic model for human thermal comfort for smart building applications

2019 ◽  
Vol 234 (4) ◽  
pp. 472-483
Author(s):  
Ghezlane Halhoul Merabet ◽  
Mohamed Essaaidi ◽  
Driss Benhaddou
Keyword(s):  
Thermal Comfort ◽  
Air Conditioning ◽  
Research Work ◽  
Comfort Level ◽  
Indoor Environments ◽  
Air Conditioning System ◽  
Human Thermal Comfort ◽  
Local Quality ◽  
Set Up ◽  
Air Conditioning Systems

Thermal comfort is closely related to the evaluation of heating, ventilation, and air conditioning systems. It can be seen as the result of the perception of the occupants of a given environment, and it is the product of the interaction of a number of personal and environmental factors. Otherwise, comfort issues still do not play an important role in the daily operation of commercial buildings. However, in the workplace, local quality effects, in addition to the health, the productivity that has a significant impact on the performance of the activities. In this regard, researchers have conducted, for decades, investigations related to thermal comfort and indoor environments, which includes developing models and indices through experimentations to establish standards to evaluate comfort and factors and set-up parameters for heating, ventilation, and air conditioning systems. However, to our best knowledge, most of the research work reported in the literature deals only with parameters that are not dynamically tracked. This work aims to propose a prototype for comfort measuring through a wireless sensor network and then presenting a model for thermal comfort prediction. The developed model can be used to set up a heating, ventilation, and air conditioning system to meet the expected comfort level. In particular, the obtained results show that there is a strong correlation between users’ comfort and variables such as age, gender, and body mass index as a function of height and weight.

Fungal Contamination in Hospital Environments

2006 ◽  
Vol 27 (1) ◽  
pp. 44-47 ◽  
Author(s):  
F. Perdelli ◽  
M. L. Cristina ◽  
M. Sartini ◽  
A. M. Spagnolo ◽  
M. Dallera ◽  
...  
Keyword(s):  
Air Conditioning ◽  
Airborne Fungi ◽  
Selective Medium ◽  
Indoor Environments ◽  
Fungal Contamination ◽  
Mean Values ◽  
Hospital Environments ◽  
Airborne Concentration ◽  
Detection And Counting ◽  
Air Conditioning Systems

Objectives.To assess the degree of fungal contamination in hospital environments and to evaluate the ability of air conditioning systems to reduce such contamination.Methods.We monitored airborne microbial concentrations in various environments in 10 hospitals equipped with air conditioning. Sampling was performed with a portable Surface Air System impactor with replicate organism detection and counting plates containing a fungus-selective medium. The total fungal concentration was determined 72-120 hours after sampling. The genera most involved in infection were identified by macroscopic and microscopic observation.Results.The mean concentration of airborne fungi in the set of environments examined was 19 ± 19 colony-forming units (cfu) per cubic meter. Analysis of the fungal concentration in the different types of environments revealed different levels of contamination: the lowest mean values (12 ± 14 cfu/m3) were recorded in operating theaters, and the highest (45 ± 37 cfu/m3) were recorded in kitchens. Analyses revealed statistically significant differences between median values for the various environments. The fungal genus most commonly encountered was Penicillium, which, in kitchens, displayed the highest mean airborne concentration (8 ± 2.4 cfu/m3). The percentage (35%) of Aspergillus documented in the wards was higher than that in any of the other environments monitored.Conclusions.The fungal concentrations recorded in the present study are comparable to those recorded in other studies conducted in hospital environments and are considerably lower than those seen in other indoor environments that are not air conditioned. These findings demonstrate the effectiveness of air-handling systems in reducing fungal contamination.

Numerical study and optimization of the combined indirect evaporative air cooler for air-conditioning systems

Energy ◽  
2015 ◽  
Vol 80 ◽  
pp. 452-464 ◽  
Author(s):  
Sergey Anisimov ◽  
Demis Pandelidis ◽  
Jan Danielewicz
Keyword(s):  
Air Conditioning ◽  
Numerical Study ◽  
Air Cooler ◽  
Air Conditioning Systems

Experimental and numerical study of an evaporatively-cooled condenser of air-conditioning systems

Energy ◽  
2015 ◽  
Vol 87 ◽  
pp. 390-399 ◽  
Author(s):  
M.R. Islam ◽  
K.A. Jahangeer ◽  
K.J. Chua
Keyword(s):  
Air Conditioning ◽  
Numerical Study ◽  
Air Conditioning Systems

scholarly journals Control Strategies in Multi-Zone Air Conditioning Systems

Energies ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 347 ◽  
Author(s):  
Behzad Rismanchi ◽  
Juan Zambrano ◽  
Bryan Saxby ◽  
Ross Tuck ◽  
Mark Stenning
Keyword(s):  
Air Conditioning ◽  
New Technologies ◽  
Control Strategies ◽  
Efficient Solutions ◽  
Indoor Environments ◽  
Commercial Building ◽  
Thermal Discomfort ◽  
Variable Air Volume ◽  
Air Volume ◽  
Air Conditioning Systems

In a commercial building, a significant amount of energy is used by the ventilation systems to condition the air for the ‎indoor environments to satisfy the required quantity (temperature ‎and humidity) and quality (amount of fresh air). For many years, Variable Air Volume ‎‎(VAV) systems have been considered as the most efficient solutions by balancing the airflow volume based on the demand making them energy efficient when compared with the traditional Constant Air Volume (CAV) systems. However, the setpoints in VAV systems are ‎often misread by the sensors due to stratification and formation of pollutant pockets and ‎responding to design levels that overestimate the real-time demand conditions, which result in ‎waste of energy, thermal discomfort and unhealthy air. In general, VAV devices are expensive, complicated and prone to failures and ‎they are used only in medium and large projects. More recently, new technologies have evolved to solve this issue. In one of the new solutions, VAV motors terminals are replaced with flaps which are simpler and less expensive thus, they can be implemented ‎in a wider range of projects. In systems, balancing and supplying the optimal airflow ‎to reduce the energy consumption while delivering ideal thermal and Indoor Air Quality (IAQ) levels are the ‎main challenges. In this paper, a comparison of the recent technologies with traditional VAV systems is presented to be used as a guild line for researchers and designers in the field of Heating Ventilation Air Conditioning (HVAC)‎.

scholarly journals Can Air-Conditioning Systems Contribute to the Spread of SARS/MERS/COVID-19 Infection? Insights from a Rapid Review of the Literature

2020 ◽  
Vol 17 (17) ◽  
pp. 6052 ◽  
Author(s):  
Francesco Chirico ◽  
Angelo Sacco ◽  
Nicola Luigi Bragazzi ◽  
Nicola Magnavita
Keyword(s):  
Air Conditioning ◽  
Far East ◽  
Hvac Systems ◽  
Rapid Review ◽  
Sufficient Evidence ◽  
Indoor Environments ◽  
Airborne Transmission ◽  
International Agencies ◽  
Viral Particles ◽  
Air Conditioning Systems

The airborne transmission of SARS-CoV-2 is still debated. The aim of this rapid review is to evaluate the COVID-19 risk associated with the presence of air-conditioning systems. Original studies (both observational and experimental researches) written in English and with no limit on time, on the airborne transmission of SARS-CoV, MERS-CoV, and SARS-CoV-2 coronaviruses that were associated with outbreaks, were included. Searches were made on PubMed/MEDLINE, PubMed Central (PMC), Google Scholar databases, and medRxiv. A snowball strategy was adopted to extend the search. Fourteen studies reporting outbreaks of coronavirus infection associated with the air-conditioning systems were included. All studies were carried out in the Far East. In six out the seven studies on SARS, the role of Heating, Ventilation, and Air Conditioning (HVAC) in the outbreak was indirectly proven by the spatial and temporal pattern of cases, or by airflow-dynamics models. In one report on MERS, the contamination of HVAC by viral particles was demonstrated. In four out of the six studies on SARS-CoV-2, the diffusion of viral particles through HVAC was suspected or supported by computer simulation. In conclusion, there is sufficient evidence of the airborne transmission of coronaviruses in previous Asian outbreaks, and this has been taken into account in the guidelines released by organizations and international agencies for controlling the spread of SARS-CoV-2 in indoor environments. However, the technological differences in HVAC systems prevent the generalization of the results on a worldwide basis. The few COVID-19 investigations available do not provide sufficient evidence that the SARS-CoV-2 virus can be transmitted by HVAC systems.

scholarly journals Air-Conditioning and the Transmission of COVID-19 in Indoor Environment

2021 ◽  
Vol 10 (3) ◽  
pp. 1
Author(s):  
Tosin T. Oye ◽  
Naren Gupta ◽  
Keng Goh ◽  
Toyosi K. Oye
Keyword(s):  
Air Conditioning ◽  
Indoor Environment ◽  
Respiratory Infections ◽  
Indoor Environments ◽  
Infectious Dose ◽  
Air Conditioning Systems ◽  
Droplet Nuclei ◽  
Respiratory Droplets

Substandard ventilation in restricted air-conditioning indoor places is allied with upsurge in the respiratory infections’ transmission. There have been several COVID-19 spread occurrences connected with indoor environment, together with a few from pre-symptomatic situations. Ventilation role in averting coronavirus transmission is not precise (i.e., through inhibiting transmission of an infectious dose to susceptible individuals or preventing the spreading of contagious particles to lessen the risk of transmission). SARS-CoV-2 is believed to be mainly spread through significant respiratory droplets, nevertheless, a growing amount of epidemic information associate aerosol role in the epidemics of coronavirus. Aerosols comprise of droplet nuclei and little droplets which stay in the air for longer than significant droplets. Recent studies show that coronavirus particles can stay transmissible on numerous substances, including aerosols within the indoor environments, as well as the contagion period contingent on humidity and temperature. Thus far, COVID-19 transmission via air-conditioning systems is unclear, but it is considered possible.

ANALYSIS OF COMPETING VARIANTS OF AIR CONDITIONING SYSTEMS WITHOUT AIR EXTRACTION FROM ENGINES AT THE STAGE OF PASSENGER AIRCRAFT ONBOARD SYSTEMS CONCEPTUAL DESIGN

2019 ◽  
Vol 6 (3) ◽  
pp. 80-85
Author(s):  
Denis Igorevich Smagin ◽  
Konstantin Igorevich Starostin ◽  
Roman Sergeevich Savelyev ◽  
Anatoly Anatolyevich Satin ◽  
Anastasiya Romanovna Neveshkina ◽  
...  
Keyword(s):  
Conceptual Design ◽  
Air Conditioning ◽  
Research University ◽  
Cooling System ◽  
Fuel Efficiency ◽  
Air Cooling ◽  
Moscow Aviation Institute ◽  
Air Conditioning System ◽  
Low Efficiency ◽  
Air Conditioning Systems

One of the ways to achieve safety and comfort is to improve on-board air conditioning systems.The use of air cooling machine determines the air pressure high level at the point of selection from the aircraft engine compressor. Because of the aircraft operation in different modes and especially in the modes of small gas engines, deliberately high stages of selection have to be used for ensuring proper operation of the refrigeration machine in the modes of the aircraft small gas engines. Into force of this, most modes of aircraft operation have to throttle the pressure of the selected stage of selection, which, together with the low efficiency of the air cycle cooling system, makes the currently used air conditioning systems energy inefficient.A key feature of the architecture without air extraction from the main engines compressors is the use of electric drive compressors as a source of compressed air.A comparative analysis of competing variants of on-board air conditioning system without air extraction from engines for longrange aircraft projects was performed at the Moscow Aviation Institute (National Research University).The article deals with the main approaches to the decision-making process on the appearance of a promising aircraft on-board air conditioning system at the stage of its conceptual design and formulated the basic requirements for the structure of a complex criterion at different life cycle stages.The level of technical and technological risk, together with a larger installation weight, will require significant costs for development, testing, debugging and subsequent implementation, but at the same time on-board air conditioning system scheme without air extraction from the engines will achieve a significant increase in fuel efficiency at the level of the entire aircraft.

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