Air Conditioning and Ventilation Systems in Hot and Humid Regions

2019 ◽  
pp. 205-219 ◽  
Author(s):  
Napoleon Enteria ◽  
Takao Sawachi
Keyword(s):  
Air Conditioning ◽  
Ventilation Systems

scholarly journals The Role of Air Conditioning in the Diffusion of Sars-CoV-2 in Indoor Environments: a First Computational Fluid Dynamic Model, based on Investigations performed at the Vatican State Childrens Hospital.

2020 ◽  
Author(s):  
Luca Borro ◽  
Lorenzo Mazzei ◽  
Massimiliano Raponi ◽  
Prisco Piscitelli ◽  
Alessandro Miani ◽  
...  
Keyword(s):  
Air Conditioning ◽  
Indoor Environment ◽  
Hvac Systems ◽  
Indoor Environments ◽  
Hospital Room ◽  
Childrens Hospital ◽  
Infection Index ◽  
Indoor Scenarios ◽  
Ventilation Systems

Background: About 15 million people worldwide were affected by the Sars-Cov-2 infection, which already caused 600,000 deaths. This virus is mainly transmitted through exhalations from the airways of infected persons, so that Heating, Ventilation and Air Conditioning (HVAC) systems might play a role in spreading the infection in indoor environments. Methods: We modelled the role of HVAC systems in the diffusion of the contagion through a Computational Fluid Dynamics (CFD) simulations of cough at the Vatican State childrens hospital Bambino Gesu. Both waiting rooms and hospital rooms were modeled as indoor scenarios. A specific Infection-Index parameter was used to estimate the amount of contaminated air inhaled by each person present in the simulated indoor scenarios. The potential role of exhaust air ventilation systems placed above the coughing patients mouth was also assessed. Results: Our CFD-based simulations show that HVAC air-flow remarkably enhance infected droplets diffusion in the whole indoor environment within 25 seconds from the cough event, despite the observed dilution of saliva particles containing the virus. In the waiting room simulation, Infection-Index parameter increases the faster the higher the HVAC airflow. Greater flows of air conditioning correspond to greater diffusion of the infected droplets. The proper use of Local Exhaust Ventilation systems (LEV) simulated in the hospital room was associated to a complete reduction of infected droplets spreading from the patient s mouth in the first 0.5 seconds following the cough event. In the hospital room, the use of LEV system completely reduced the index computed for the patient hospitalized at the bed next to the spreader, with a decreased possibility of contagion. Conclusions: CFD-based simulations for indoor environment can be useful to optimize air conditioning flow and to predict the contagion risk both in hospitals/ambulatories and in other public/private settings.

scholarly journals Impact Assessment of the ventilation systems on microbiological safety and microclimatic conditions of premises.

2020 ◽  
pp. 49-55
Author(s):  
Tetiana Kryvomaz ◽  
Dmytro Varavin ◽  
Rostyslav Sipakov
Keyword(s):  
Air Conditioning ◽  
Residential Buildings ◽  
Operating Conditions ◽  
International Agencies ◽  
Industrial Buildings ◽  
Key Factor ◽  
Poor Ventilation ◽  
Air Conditioning Systems ◽  
The Impact ◽  
Ventilation Systems

The critical aspects of the impact of microbiological contamination on ventilation and air conditioning systems, the microclimate of the premises, and human health are analyzed. The quantitative and qualitative composition of the microflora of premises depends on their functional purpose, design features, operating conditions, climate, and other factors, among which the method of ventilation is essential. The moisturizers in the air conditioning system are hazardous, which provide bacteria and fungi with water necessary for their life and reproduction. In addition, contaminants accumulated in ventilation systems operate as a substrate for feeding microorganisms. Multi-story administrative, public, and residential buildings, industrial buildings, and other places of mass concentration are areas of increased aerobiological risk of infection. In case of improper operation, air conditioning and ventilation systems can be sources of microorganisms in any room. Transmission of infectious aerosol over long distances occurs in rooms with poor ventilation, and a key factor for the outbreak of infection is the direction of airflows. In the context of the COVID-19 pandemic, organizations and international agencies to control the spread of SARS-CoV-2 indoors recommend limiting the operation of exhaust ventilation and recirculation systems. However, there is still insufficient data to clarify the role of heating, ventilation, and air conditioning systems in spreading infection. Risk assessment and decision-making on the choice of air conditioning systems should be dynamic and based on the scale of the pandemic and the verification of the characteristics of HVAC systems and their effectiveness.

scholarly journals An Overview of the Ship Ventilation Systems and Measures to Avoid the Spread of Diseases

Inventions ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 55
Author(s):  
Victor Mihai ◽  
Liliana Rusu
Keyword(s):  
Air Conditioning ◽  
Current Practice ◽  
High Efficiency ◽  
Local Heating ◽  
Uv Disinfection ◽  
Usual Practice ◽  
Air Supply ◽  
Different Types ◽  
Air Conditioning Systems ◽  
Ventilation Systems

This article presents a review of the main aspects regarding the current rules of classification societies, standards, and practice regarding the design and construction of ventilation and air conditioning systems for different compartments in different types of ships. In the context of the COVID-19 pandemic, this paper also presents the usual practice of the actual heating ventilation and air conditioning (HVAC) systems used on large ships, which recirculate the air between living compartments, in comparison with the new requirements to avoid the risk of spreading diseases. According to the rules, the technical compartments are provided with independent ventilation systems that ensure high air flow rates; therefore, the spread of diseases through this system is not an issue. The living spaces are provided with common ventilation and air conditioning systems that recirculate the air in all compartments served. The current practice of air recirculation in various living rooms leads to the spread of diseases, which should therefore be analyzed and improved by adding high-efficiency particulate air (HEPA) filters and UV disinfection or be replaced with individual systems that provide local heating or cooling without air recirculation between different rooms and fresh air supply with complete evacuation. For existing ships, different solutions should be analyzed such as reducing or cancelling recirculation and increasing filtration.

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