scholarly journals Influence of Ceiling Height on Airflow and Particle Distribution in an Operating Room

2019 ◽  
Vol 111 ◽  
pp. 01032
Author(s):  
Aleyna Agirman ◽  
Yunus Emre Cetin ◽  
Mete Avci ◽  
Orhan Aydin
Keyword(s):  
Operating Room ◽  
Particle Distribution ◽  
Numerical Study ◽  
Surgical Site Infections ◽  
Particle Dispersion ◽  
Ansys Fluent ◽  
Change Rate ◽  
Numerical Predictions ◽  
Air Change Rate ◽  
Ceiling Height

Bacteria-carrying particles released by surgical staff are the main factors leading to surgical site infections (SSI). Operating rooms must be designed to reduce risks of such infections. In this numerical study, the effect of different ceiling heights on particle dispersion and deposition are studied for an operating room with laminar airflow (LAF) system. Two different particle diameters (12 and 20 ìm) are tested under three different ceiling heights (2.43–2.8–3.0 m) at a constant air change rate (ACH=20). Numerical predictions are performed by using the commercial software ANSYS Fluent 16.0. The results reveal that decreasing of the ceiling height reduces the amount of particle deposited on the surgical table.

Numerical Study on Indoor Air Quality of Commercial Kitchen in China

2011 ◽  
Vol 374-377 ◽  
pp. 1100-1105 ◽  
Author(s):  
Xiao Tan Hou ◽  
An Gui Li ◽  
Zhi Hua Wang ◽  
Yu Jiao Zhao
Keyword(s):  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Numerical Study ◽  
Average Concentration ◽  
Energy Utilization ◽  
Change Rate ◽  
Air Supply ◽  
Air Change Rate

Indoor air quality of commercial kitchen is investigated and analyzed through velocity, temperature, humidity, and CO2 concentration under different air change rate and supply air temperature. the best air change rate is 30 times per hour and air supply temperature is 301.15K for kitchen, the mean value of the minimum velocity and standard deviation is 0.410m/s and 0.129 respectively, the maximum of the average concentration of CO2 is 659.78ppm, which is less than the acceptance criteria (CO2<1000ppm), and the energy utilization coefficient is maximum of 1.352. Research results show that this air supply mode can optimize indoor air quality.

scholarly journals Study on Self-Cleaning Time and Suspended Particle Distribution in Medical Clean Room

2022 ◽  
Vol 2148 (1) ◽  
pp. 012042
Author(s):  
Long Chen ◽  
Enyan Wang ◽  
Yang Li ◽  
Miaocheng Weng ◽  
Fang Liu
Keyword(s):  
Particle Distribution ◽  
Suspended Particle ◽  
Air Flow ◽  
Concentration Field ◽  
Simulation Method ◽  
Clean Room ◽  
Actual Measurement ◽  
Change Rate ◽  
Air Change Rate ◽  
Self Cleaning

Abstract CFD numerical simulation of clean room in Class D medical factory was carried out and compared with the actual measurement to verify the feasibility of the simulation method. On this basis, four typical air flow organizations were simulated and compared by changing air change rate from two directions of self-cleaning time and suspended particle concentration field. According to the simulation results, in order to meet the self-cleaning time within 20 min, the best air change rate should be between 15/h and 25/h. Different air flow organizations have different self-cleaning capacity, and the value of air change rate can be relatively small in the form of single-side supply same-side down return. Different airflow organizations have different suspended particle distribution characteristics, and there are differences in the applicable scenarios, and the applicability of the top supply down return is the best.

scholarly journals Effect of Zero Air Change Rate On Particle Dispersion in A Room with Floor Heating

2019 ◽  
Vol 111 ◽  
pp. 02037
Author(s):  
Mustafa Mutlu
Keyword(s):  
Particle Diameter ◽  
Heating System ◽  
Ambient Air ◽  
Particle Dispersion ◽  
Lagrangian Model ◽  
Residential Areas ◽  
Change Rate ◽  
Heating Systems ◽  
Air Change Rate ◽  
Floor Heating

Dispersion of airborne particles in the office and residential areas should be well known as these particles in an enclosed volume has a significant effect on human health. In this study, the effect of the floor heating system, which is often preferred by end users due to the energy efficiency of low heating systems, on particle distribution in a room was investigated numerically. It is essential to examine the floor heating having a significant place among low heating systems, concerning particle dispersion. In enclose volumes, ambient air should be replaced with fresh air that is supplied from outdoor in order to ensure indoor air quality. However, the ideal air change rates may not be met for daily use, even in some cases air change rates might be zero. Therefore, in this study absence of air change were assumed, and after temperature and velocity distributions were determined, five different sized particles were tracked by using Eulerian-Lagrangian model. Additionally, three heating capacities (35 W/m2 41.25 W/m2 and 47 W/m2) of the floor heating system were investigated. In this study, where computational fluid dynamics were used, the effect of drag, lift, thermophoretic and Brownian forces were considered. It was found that particles were settled on walls and ceiling due to zero air change rate, and particle concentration rises in the lower part of the wall as particle diameter increases.

scholarly journals The Effect of Blade Number on Small Horizontal Axis Wind Turbine (HAWT) Performance: An Experimental and Numerical Study

2020 ◽  
Vol 11 (12) ◽  
pp. 555-560
Author(s):  
Andi F. Sudarma ◽  
◽  
Muhammad Kholil ◽  
Subekti Subekti ◽  
Indra Almahdy
Keyword(s):  
Wind Turbine ◽  
Numerical Study ◽  
Horizontal Axis ◽  
Experimental Measurements ◽  
Blade Surface ◽  
Horizontal Axis Wind Turbine ◽  
Ansys Fluent ◽  
Wind Speeds ◽  
Blade Number ◽  
Numerical Predictions

The effect of blade number on small Horizontal Axis Wind Turbine (HAWT) has been studied experimentally and numerically in this research. The turbine blade is made of a flat metal sheet and the tip was formed to shape a winglet. The 5-blades turbine was tested inside a wind tunnel for performance investigation at different wind speeds. The experiment was conducted under various wind speed, i.e. 3.5 m/s, 3.9 m/s, 4.3 m/s, 4.6 m/s dan 5 m/s. Furthermore, three wind turbines geometry with different blade number (3, 4, and 5 blades) were built for numerical study purpose by using Ansys Fluent and the results were compared to the experimental one. The results show that the blade number does increase the wind turbine torque and there is also more power generated from the turbine with more blade numbers since torque is related to pressure. Moreover, the winglet helps the blade to retain the flow and increases the pressure on the blade surface. However, the experimental measurements obtained were smaller than the numerical predictions about 50% on the average since more unidentified losses existed and not accounted for the calculation.

The impact of air change rate on the air quality of surgical microenvironment in an operating room with mixing ventilation

2020 ◽  
Vol 32 ◽  
pp. 101770
Author(s):  
Yixian Zhang ◽  
Guangyu Cao ◽  
Guohui Feng ◽  
Kai Xue ◽  
Christoffer Pedersen ◽  
...  
Keyword(s):  
Air Quality ◽  
Operating Room ◽  
Change Rate ◽  
Air Change Rate ◽  
The Impact

scholarly journals Influence of the Airflow in a Solar Passive Building on the Indoor Air Quality and Thermal Comfort Levels

Atmosphere ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 766 ◽  
Author(s):  
Eusébio Conceição ◽  
João Gomes ◽  
Hazim Awbi
Keyword(s):  
Air Quality ◽  
Thermal Comfort ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Numerical Study ◽  
Change Rate ◽  
Comfort Levels ◽  
Air Change Rate ◽  
Typical Summer ◽  
Shading Devices

The influence of the airflow in a solar passive building on the indoor air quality and thermal comfort levels was investigated. The numerical study for a university library was conducted using a software that simulates the building thermal behavior with complex topology, in transient conditions, for evaluating the indoor air quality and occupants’ thermal comfort levels for typical summer and winter days. Solar radiation was used as a renewable energy source to increase simultaneously the thermal comfort and air quality levels and reduce building energy consumption. Regarding the solar passive building, consideration was given to all of the building structure envelope, shading devices and interior details, while in the solar active building active ventilation was used. To analyze the airflow that simultaneously provides the best indoor air quality and thermal comfort levels, a new integral methodology based on the minimization of the total number of uncomfortable hours was used. The results show that it was possible to determine an air change rate that ensures a good compromise between thermal comfort and indoor air quality. An optimal air change rate of two and three renewals per hour had been determined, respectively, for winter and summer conditions.

An Investigation of the Effect of interrupted fin arrangements on the Thermal Performance of a Heat Sink under a Free Convection Condition

2019 ◽  
Vol 7 (1) ◽  
pp. 43-53
Author(s):  
Abbas Jassem Jubear ◽  
Ali Hameed Abd
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Natural Convection ◽  
Thermal Performance ◽  
Heat Sink ◽  
Numerical Study ◽  
Ansys Fluent ◽  
Fluent Software ◽  
Steady State Heat ◽  
Steady State Heat Transfer

The heat sink with vertically rectangular interrupted fins was investigated numerically in a natural convection field, with steady-state heat transfer. A numerical study has been conducted using ANSYS Fluent software (R16.1) in order to develop a 3-D numerical model.  The dimensions of the fins are (305 mm length, 100 mm width, 17 mm height, and 9.5 mm space between fins. The number of fins used on the surface is eight. In this study, the heat input was used as follows: 20, 40, 60, 80, 100, and 120 watts. This study focused on interrupted rectangular fins with a different arrangement and angle of the fins. Results show that the addition of interruption in fins in various arrangements will improve the thermal performance of the heat sink, and through the results, a better interruption rate as an equation can be obtained.

Comparison of two air sampling methods to monitor operating room air quality and assessment of air quality in two operating rooms with different ventilation systems in the national hospital of Sri Lanka

2016 ◽  
Vol 12 (3) ◽  
Author(s):  
Tshokey Tshokey ◽  
Pranitha Somaratne ◽  
Suneth Agampodi
Keyword(s):  
Air Quality ◽  
Sri Lanka ◽  
Operating Room ◽  
Ventilation System ◽  
Surgical Site Infections ◽  
National Hospital ◽  
Air Contamination ◽  
Acceptable Method ◽  
The Difference ◽  
Laminar Air Flow

Air contamination in the operating room (OR) is an important contributor for surgical site infections. Air quality should be assessed during microbiological commissioning of new ORs and as required thereafter. Despite many modern methods of sampling air, developing countries mostly depended on conventional methods. This was studied in two ORs of the National Hospital of Sri Lanka (NHSL) with different ventilation system; a conventional ventilation (CV) and a laminar air flow (LAF). Both ORs were sampled simultaneously by two different methods, the settle plate and sampler when empty and during use for a defined time period. Laboratory work was done in the Medical Research Institute. The two methods of sampling showed moderate but highly significant correlation. The OR with CV was significantly more contaminated than LAF when empty as well as during use by both methods. Overall, the difference in contamination was more significant when sampled by the sampler. Differences in contamination in empty and in-use ORs were significant in both ORs, but significance is less in LAF rooms. The consistent and significant correlation between settle plate and sampler showed that the settle plate is an acceptable method. The LAF theatre showed less contamination while empty and during use as expected. Air contamination differences were more significant when sampled with sampler indicating that it is a more sensitive method. Both CV and LAF ORs of the NHSL did not meet the contamination standards for empty theatres but met the standards for in-use indicating that the theatre etiquette was acceptable.

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