Computational Analysis of a Lecture Room Ventilation System

The level of Indoor Air Quality (IAQ) has become a big topic of research, and improving it using passive ventilation methods is imperative due to the cost saving potentials. Designing lecture buildings to use less energy or Zero Energy (ZE) has become more important, and analysing buildings before construction can save money in design changes. This research analyses the performance (thermal comfort [TC]) of a lecture room, investigate the use of passive ventilation methods and determine the energy-saving potential of the proposed passive ventilation method using Computational Fluid Dynamics (CFD). Results obtained showed that air change per hour at a wind velocity of 0.05 m/s was 3.10, which was below standards. Therefore, the lecture hall needs external passive ventilation systems (Solar Chimney [SC]) for improved indoor air quality at minimum cost. Also, it was observed that the proposed passive ventilation (SC) system with the size between 1 and 100 m3, made an improvement upon the natural ventilation in the room. There was a 66.69% increase after 10 years in the saving of energy and cost using Solar Chimney as compared to Fans, which depicts that truly energy and cost were saved using passive ventilation systems rather than mechanical ventilation systems.

Method of the boiler room ventilation system efficiency experimental determination

The issue of the normative air exchange ensuring in the premises of the boiler houses is extremely important. The article presents the results of theoretical and experimental studies of air velocity determination in the distribution of air by round and compact jets in the boiler room. Graphical and analytical dependences are given. The research results substantiate the higher accuracy of the average air flow velocity determination in small boiler rooms. The aim of the work is to develop a method for experimental determination of the efficiency of the ventilation system in the boiler room; to increase of the accuracy of the average velocity determination of the round and the compact air jets in the plane of the supply nozzle to ensure the normative air exchange of the boiler room and to substantiate of the calculation method. The characteristics and patterns of development of round and compact air jets in the premises are established and the calculated dependences are obtained. It is substantiated that the application of the proposed method will significantly increase the accuracy of air exchange determination in the boiler rooms to ensure the required value in accordance with regulatory requirements. Recommendations for the practical determination of the calculated values to ensure proper ventilation of the boiler rooms are given.

Tracking the Flu Virus in a Room Mechanical Ventilation Using CFD Tools and Effective Disinfection of an HVAC System

Recent concerns raised by the World Health Organization over the Coronavirus raised a worldwide reaction. Governments are racing to contain and stop the Coronavirus from reaching an epidemic/pandemic status. This research presents a way in tracking such a virus or any contagious germ capable of transferring through air specifically where such a transfer can be assisted by a mechanical room ventilation system. Tracking the spread of such a virus is a complicated process, as they can exist in a variety of forms, shapes, sizes, and can change with time. However, a beginning has to be made at some point. Assumptions had to be made based on published scientific data, and standards. The tracking of airborne viruses was carried out on the following assumption (for illustrative purposes); one person with one sneeze in a period of 600 s. The presence of viruses was tracked with curves plotted indicating how long it could take to remove the sneezed viruses from the mechanically ventilated room space. Results gave an indication of what time span is required to remove airborne viruses. Thus, we propose the following: (a) utilizing CFD software as a possible tool in optimizing a mechanical ventilation system in removing contagious viruses. This will track the dispersion of viruses and their removal. The numerical solution revealed that with one typical adult human sneeze, it can take approximately 640 s to reduce an average sneeze of 20,000 droplets to a fifth; (b) upscaling the status of human comfort to a “must have” with regards to the 50% relative humidity, and the use of Ultraviolet germicidal irradiation (UVGI) air disinfection in an epidemic/pandemic condition. A recommendation can be presented to the local authorities of jurisdiction in enforcing the above proposals partially/fully as seen fit as “prevention is better than cure”. This will preclude the spread of highly infectious viruses in mechanically ventilated buildings.

The dependence of the productive qualities of pigs on the ventilation system of the premises during the suckling period of their cultivation

The dependence of the growth rate, the safety of young pigs in growing and fattening and their feeding qualities on the ventilation system of negative and uniform pressure in the suckling period of their cultivation was studied. We have found that the growth rate of piglets, and their payment of feed by growth during rearing, did not depend on the design features of the room ventilation system during suckling period. We have established some better preservation of piglets in growing with an unchanged ventilation system in the suckling and growing periods. It was revealed the tendency to insignificantly improve of the growth rate and feed payment by growths in piglets, which were grown during ventilation with uniform pressure in the suckling period. It was found that pigs that were raised during the suckling period with a uniform pressure ventilation system reached a mass of 100 kg at the age of 158.4 days, while their counterparts that were raised at that time with a negative pressure ventilation system reached the age of 159.8, that is later on 1, 4 days, or 0.88%. It wasn’t found a significant dependence of the feeding qualities of pigs on the ventilation system of the premises during the suckling period of their cultivation. There was a tendency to a slight improvement in the safety index by 1.9% in animals that were kept in the suckling period with a uniform pressure ventilation system, compared with analogues that were raised during this period with negative pressure ventilation. According to the calculation of the index of feeding qualities according to the formula M.D. Berezovsky, a comprehensive indicator of feeding qualities in animals that were raised during the suction period with uniform pressure ventilation was 21.4% higher compared to peers that were kept during negative pressure ventilation. In general, the growth rate of pigs during rearing and fattening, their safety during these periods and fattening qualities did not significantly depend on the ventilation system of the premises during the suction period of their rearing. Key words: ventilation, microclimate, sow, pig, multiplicity, growth, safety.

Improving Quality Control of Operating Room Environment by Computational Fluid Dynamics

In Vietnam, the operating room (OR) is used with max productivity. So, how to maintain comfort environment level, which is one of the assignments in designing and installing the operating room. In this study, the OR model is designed based on ASHRAE 170 – 2013 standard [1], and dimensions are referred to as “Comparison of Operating Room Ventilation System in the Protection of the Surgical Site” [2]. ANSYS CFX is used for calculating and simulating velocity and temperature of surveyed air points inside the room by many cases. A face temperature between 20,3 and 20,6 °C and a velocity of around 0,15 to 0,18 m/s is provided from the same laminar diffuser array. From the results, the OR comfort level is reviewed through the ADPI index.

EKSPERIMENTINIO ŠILUMOS SIURBLIO CIKLO VALDYMO ALGORITMO PAIEŠKA / EXPERIMENTAL STUDY OF THE HEAT PUMP CYCLE CONTROL ALGORITHM SEARCH

This paper analyzes an experimental heat pump used for heat recovery in a mechanical room ventilation system. The aim of the work is to examine the operation, control logic of the heat pump and evaluate the possibilities of its operation modes, cycle control by outdoor air temperature. A review of scientific literature and experimental tests of the heat pump were performed to achieve this goal. Tests were performed in three stages, after each stage, according to the results obtained the heat pump stand was improved and experimental modes were adjusted. During the experiment, the tendencies of the heat pump freon and air involved in the heat exchange parameters are analyzed with different combinations of expansion valve positions and compressor power. Knowing these experimental characteristics, the extent to which the combination of these two controls can be used to efficiently control of the heat pump according to the outside air temperature is assessed. Based on the results of the research the heat pump control algorithms (depending on the variable outdoor air temperature) are prepared.

A new modelling procedure of the engine room ventilation system for work risk prevention and energy saving

Maritime transport is one of the primary international objectives for energy saving and pollution reduction, in agreement with the International Maritime Organization. Within the most interesting energy-saving topics, the ventilation system of the engine room must be highlighted, which represents about 5% of the nominal power of a modern ship. Nevertheless, its energetic optimization is not simple and must consider also work risk criteria, since the engine room is the hottest and, in consequence, one of the hazardous places in the ship. In this research, a complete three-dimensional computational fluid dynamics model of the engine room of a real ship has been developed in order to identify the hottest places and fully characterize their thermal conditions. On the basis of this analysis, a mathematical model of the maximum working time allowed has been defined, which can be directly used to design an efficient control algorithm for the ventilation system. In a complementary way, the minimum time required to rest in the control engine room to release the cumulated heat has also been analysed, in order to optimize its set-point conditions.