ABSTRACT
The Air borne transmission is a very big concern for highly infectious diseases like Covid-19 and other airborne diseases. A micro droplet and aerosol can be carried out in the air and can remain flowing in air over a distance in a confined space, leading to affecting high number of people getting prone to infection and it is very dangerous in enclosed spaces or shared spaces. Public places, shared facilities are the areas, where infectious aerosol can be present in the air for a long duration. Ventilation of closed spaces, shared spaces is the need of hour to have analysed and deep study in context of infectious airborne diseases. Introduction of fresh air into the enclosed environment at regular interval of times may lead to fast dilution of air present in the enclosed space. The prominent building codes and HVAC guidelines allows as to calculate ACPH (Air changes per hour) in an enclosed space as per the occupancy and flow rate. The age of air is the criteria to define the amount of air residing in the enclosed space when it enters the space till its exhaust from that space. The more the age of air in the particular area the more can be the infection probability among the occupants. It is predominant to study the airflow pattern caused due to ventilation which can be collaborated with age of air to know about the infection probability. Typically, a classroom geometry is assumed with inlet outlet boundary conditions where exhaust fan is playing a major role of displacement ventilation. Study of air recirculation zones and dead zones is the point of interest of this study. Computational fluid dynamics is the most powerful tool in the present era to study the air flow pattern in enclosed and shared spaces.Copyright © 2022, Anka Publishers. All rights reserved.
ABSTRACT
The emergence of viral variants has driven a continuous pandemic with a higher possibility of airborne transmission and a larger scale of infective cases, posing greater demands on indoor risk control. However, the role of room-level air recirculation systems (RRSs) in infection control remains unclear due to insufficient detailed research. There are also fewer analyses of the filtering rating of recirculation filters from the perspective of multi-scale particle size. Thus, a simulation procedure to assess the performance of RRSs on infection control that accounts the transient recirculation of real virus-laden particles in multi-scale sizes was proposed, and focusing on recirculation filter strategies to balance the risk limitation and energy cost. A poorly ventilated winter classroom was selected as a typical environment equipped with RRSs to operate this procedure. Different RRS strategies (i.e., wall-mounted air conditioners (WMAC), floor-standing air conditioners (FSAC) and 4-way cassette air conditioners (WCAC)) were compared. The results show the important contribution of recirculated particles to accumulating the overall infection risk of susceptible occupants towards a high basic reproduction number (Ro > 1). Then, there is a strong correlation of the spatial distributions between high-risk zones and large vortexes at the breathing height of susceptible occupants. Considering rating suitability and filtration effectiveness, the optimization of recirculation filters on energy and cost can be suggested with comparable benefits of infection control. © 2023 Elsevier B.V.
ABSTRACT
The air environment is favorable for the reproduction of microorganisms and viruses. The problem has become particularly urgent in connection with the Cov19 coronavirus pandemic, which undoubtedly affected the operation of all types of fleet. The need for a concealed installation of an air disinfection device is due to safety requirements during the operation of the vessel. The recirculators currently in use are not elements of shipboard ventilation systems. The article proposes the modernization of this system using an integrated air disinfection unit. A schematic diagram of such an installation is proposed. An experimental stand has been developed to determine the effectiveness of air disinfection by studying microbial contamination. The planning and processing of the experiment results were carried out using a software product. A mathematical model has been developed for the operation of the supply air disinfection unit in the ship's ventilation system, which provides the necessary efficiency with minimal energy and heat costs for air treatment.
ABSTRACT
COVID-19 em ergency has ca used major changes in everyday life in the la st m onths, a nd it a lso affected the management of buildings. In particular, indoor a ir quality and ventilation ha ve been considered to play a key role in the spreading of the infection, causing national and interna tional subjects to draw up specific guidelines on ventilation and air recirculation rate in AHUs. The pa per deals with the “Loccioni Leaf Lab”, a n industria l building that hosts offices a nd workers operating on test benches. The building features high performance envelope, solar photovoltaic systems, groundwater heat pumps a nd a high -technology control a nd monitoring system and it is connected to a thermal and electric smart grid. A va lidated m odel of the building, im plem ented with the software DesignBuilder a nd EnergyPlus, wa s used to carry out numerical sim ula tions to optimize the m anagement of the HVAC through the Building Management System. Different working conditions have been sim ulated, a nd the numerical output has been used together with experimental data collected from the Company monitoring system. Ithas been possible to investigate how the extra ventilation required by the new guidelines would affect the tota l energy consumption a nd to compare, in term s of energy efficiency, the different HVAC m a nagement stra tegies tha t could be used to ensure occupants hea lth safety and indoor air qua lity. © 2021 Institute of Physics Publishing. All rights reserved.