CFD analysis of thermal comfort in hospital operation room with different air distribution design and operative temperature

The operation room is one of the most critical regions in hospital that require extra attention in air ventilation and prevention of dangerous pollutants contamination. A good level of ventilation will help to raise the productivity of workers in terms of performance and ensuring a safe surgery operation. It is obvious that today's operation rooms are completely equipped with mechanical ventilation systems. However, despite the fact that they meet the acceptable comfort standards, surgical workers have complained about thermal discomfort during operation which gives negative impact on their performance. Thermal comfort can be achieved by controlling the temperature, relative humidity and air movement. In this study, the operation room models are simulated to analyze the comfort conditions of surgical workers under 3 different air velocities at 0.2 ms-1, 0.25 ms-1 and 0.35 ms-1 and under 5 different temperatures between 16℃ to 20℃. Additionally, there are two 3D models created with different position of exhaust vent. The thermal comfort of surgical workers is measured using Predicted Mean Vote (PMV) and Predicted Percentage Dissatisfied (PPD) approaches using CBE Thermal Comfort Tool. The PMV and PPD results show that most surgical workers were outside the acceptable range value of -0.5 to +0.5 stated in ASHRAE Standard 55-2020. According to thermal scale index, most of the surgical workers were in a cool and slightly cool state despite the fact that the computational analysis shown an acceptable simulation validated with previous research studies. Finally, it has been discovered that clothing insulation, metabolic rate, mechanical equipment and air distribution design play a significant influence in providing comfort to the surgical workers.

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Automatic estimation of clothing insulation rate and metabolic rate for dynamic thermal comfort assessment

Pattern Analysis and Applications ◽

10.1007/s10044-021-00961-5 ◽

2021 ◽

Author(s):

Jinsong Liu ◽

Isak Worre Foged ◽

Thomas B. Moeslund

Keyword(s):

Metabolic Rate ◽

Thermal Comfort ◽

Clothing Insulation ◽

Automatic Estimation

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Numerical Study on Coupled Operation of Stratified Air Distribution System and Natural Ventilation under Multi-Variable Factors in Large Space Buildings

Energies ◽

10.3390/en14238130 ◽

2021 ◽

Vol 14 (23) ◽

pp. 8130

Author(s):

Ziwen Dong ◽

Liting Zhang ◽

Yongwen Yang ◽

Qifen Li ◽

Hao Huang

Keyword(s):

Thermal Comfort ◽

Working Conditions ◽

Distribution System ◽

Distribution Systems ◽

Natural Ventilation ◽

Numerical Study ◽

Air Distribution ◽

Large Space ◽

Air Conditioners ◽

Air Supply

Stratified air distribution systems are commonly used in large space buildings. The research on the airflow organization of stratified air conditioners is deficient in terms of the analysis of multivariable factors. Moreover, studies on the coupled operation of stratified air conditioners and natural ventilation are few. In this paper, taking a Shanghai Airport Terminal departure hall for the study, air distribution and thermal comfort of the cross-section at a height of 1.6 m are simulated and compared under different working conditions, and the effect of natural ventilation coupling operation is studied. The results show that the air distribution is the most uniform and the thermal comfort is the best (predicted mean vote is 0.428, predicted percentage of dissatisfaction is 15.2%) when the working conditions are 5.9% air supply speed, 11 °C cooling temperature difference and 0° air supply angle. With the coupled operation of natural ventilation, the thermal comfort can be improved from Grade II to Grade I.

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Clothing Insulation Rate and Metabolic Rate Estimation for Individual Thermal Comfort Assessment in Real Life

Sensors ◽

10.3390/s22020619 ◽

2022 ◽

Vol 22 (2) ◽

pp. 619

Author(s):

Jinsong Liu ◽

Isak Worre Foged ◽

Thomas B. Moeslund

Keyword(s):

Metabolic Rate ◽

Thermal Comfort ◽

Real Life ◽

Activity Level ◽

Tracking Accuracy ◽

Classification Rate ◽

Clothing Insulation ◽

Activity Intensity ◽

Bounding Box ◽

Tracking By Detection

Satisfactory indoor thermal environments can improve working efficiencies of office staff. To build such satisfactory indoor microclimates, individual thermal comfort assessment is important, for which personal clothing insulation rate (Icl) and metabolic rate (M) need to be estimated dynamically. Therefore, this paper proposes a vision-based method. Specifically, a human tracking-by-detection framework is implemented to acquire each person’s clothing status (short-sleeved, long-sleeved), key posture (sitting, standing), and bounding box information simultaneously. The clothing status together with a key body points detector locate the person’s skin region and clothes region, allowing the measurement of skin temperature (Ts) and clothes temperature (Tc), and realizing the calculation of Icl from Ts and Tc. The key posture and the bounding box change across time can category the person’s activity intensity into a corresponding level, from which the M value is estimated. Moreover, we have collected a multi-person thermal dataset to evaluate the method. The tracking-by-detection framework achieves a mAP50 (Mean Average Precision) rate of 89.1% and a MOTA (Multiple Object Tracking Accuracy) rate of 99.5%. The Icl estimation module gets an accuracy of 96.2% in locating skin and clothes. The M estimation module obtains a classification rate of 95.6% in categorizing activity level. All of these prove the usefulness of the proposed method in a multi-person scenario of real-life applications.

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Experimental Study of Air Distribution Characteristics in Room of Stratum Ventilation under Two Kinds of Air Change Times

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.409-410.668 ◽

2013 ◽

Vol 409-410 ◽

pp. 668-672

Author(s):

Yong Mei Xu ◽

Jian Tang ◽

Jun Han ◽

Chu Qin Lin

Keyword(s):

Experimental Study ◽

Thermal Comfort ◽

Experimental Studies ◽

Air Distribution ◽

Distribution Characteristics ◽

Breathing Zone ◽

Wind Speeds ◽

Pollutant Concentrations ◽

New Type ◽

Better Than

Aimed at a new type of ventilation - stratum ventilation, air distributions at a breathing-zone in a model office were measured under kinds of air changes, the measure parameters in the experimental studies included temperatures, wind speeds and pollutant concentrations, based on which the thermal comfort at a breathing-zone were studied. Experimental results show that, the temperature, pollutant concentration and wind speeds in a breathing-zone under 5 times air changes are better than those under 6 times air changes. The calculating results of PMV and PPD indicate that the thermal comfort at a breathing-zone under 5 times air changes is better. The experimental study is instructive for the development of the ventilation.

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Thermal Comfort Evaluation of Under Floor Air Distribution Space Using EDT Index

Journal of The Korean Society of Living Environmental System ◽

10.21086/ksles.2017.12.24.6.777 ◽

2017 ◽

Vol 24 (6) ◽

pp. 777-784

Author(s):

Byung-Yoon Park ◽

Yong-Ho Jung

Keyword(s):

Thermal Comfort ◽

Air Distribution ◽

Distribution Space ◽

Comfort Evaluation

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Thermal Comfort Assessment of Underfloor vs. Overhead Air Distribution System

Journal of Applied Sciences ◽

10.3923/jas.2012.473.479 ◽

2012 ◽

Vol 12 (5) ◽

pp. 473-479 ◽

Cited By ~ 2

Author(s):

M. Aghakhani ◽

Gh. Eslami

Keyword(s):

Thermal Comfort ◽

Distribution System ◽

Air Distribution

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Experimental Investigation of Ventilation Performance of Different Air Distribution Systems in an Office Environment—Heating Mode

Energies ◽

10.3390/en12101835 ◽

2019 ◽

Vol 12 (10) ◽

pp. 1835 ◽

Cited By ~ 5

Author(s):

Arman Ameen ◽

Mathias Cehlin ◽

Ulf Larsson ◽

Taghi Karimipanah

Keyword(s):

Thermal Comfort ◽

Distribution Systems ◽

Cold Climate ◽

Air Distribution ◽

Temperature Pattern ◽

Office Environment ◽

Ventilation Effectiveness ◽

Local Thermal Comfort ◽

Heating Mode ◽

Occupied Zone

A vital requirement for all-air ventilation systems are their functionality to operate both in cooling and heating mode. This article experimentally investigates two newly designed air distribution systems, corner impinging jet (CIJV) and hybrid displacement ventilation (HDV) in comparison against a mixing type air distribution system. These three different systems are examined and compared to one another to evaluate their performance based on local thermal comfort and ventilation effectiveness when operating in heating mode. The evaluated test room is an office environment with two workstations. One of the office walls, which has three windows, faces a cold climate chamber. The results show that CIJV and HDV perform similar to a mixing ventilation in terms of ventilation effectiveness close to the workstations. As for local thermal comfort evaluation, the results show a small advantage for CIJV in the occupied zone. Comparing C2-CIJV to C2-CMV the average draught rate (DR) in the occupied zone is 0.3% for C2-CIJV and 5.3% for C2-CMV with the highest difference reaching as high as 10% at the height of 1.7 m. The results indicate that these systems can perform as well as mixing ventilation when used in offices that require moderate heating. The results also show that downdraught from the windows greatly impacts on the overall airflow and temperature pattern in the room.

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Genetic Algorithm Applied to Multi-Criteria Selection of Thermal Insulation on Industrial Shed Roof

Buildings ◽

10.3390/buildings9120238 ◽

2019 ◽

Vol 9 (12) ◽

pp. 238 ◽

Cited By ~ 1

Author(s):

Stamoulis ◽

Santos ◽

Lenz ◽

Tusset

Keyword(s):

Genetic Algorithm ◽

Thermal Comfort ◽

Thermal Insulation ◽

Optimization Technique ◽

Building Envelope ◽

Expanded Polystyrene ◽

Insulation Material ◽

Clothing Insulation ◽

Climate Conditions ◽

Selection Of

The rational use of energy has motivated research on improving the energy efficiency of buildings, which are responsible for a large share of world consumption. A strategy to achieve this goal is the application of optimized thermal insulation on a building envelope to avoid thermal exchanges with the external environment, reducing the use of heating, ventilation and air-conditioning (HVAC) systems. In order to contribute to the best choice of insulation applied to an industrial shed roof, this study aims to provide an optimization tool to assist this process. Beyond the thermal comfort and cost of the insulation, some hygrothermic properties also have been analysed to obtain the best insulation option. To implement this optimization technique, several thermo-energetic simulations of an industrial shed were performed using the Domus software, applying 4 types of insulation material (polyurethane, expanded polystyrene, rockwool and glass wool) on the roof. Ten thicknesses ranging from 0.5 cm to 5 cm were considered, with the purpose of obtaining different thermal comfort indexes (PPD, predicted percentage dissatisfied). Posteriorly, the best insulation ranking has been obtained from the weights assigned to the parameters in the objective function, using the technique of the genetic algorithm (GA) applied to multi-criteria selection. The optimization results showed that polyurethane (PU) insulation, applied with a thickness of 1 cm was the best option for the roof, considering the building functional parameters, occupant metabolic activity, clothing insulation and climate conditions. On the other hand, when the Brazilian standard was utilized, rock wool (2 cm) was considered the best choice.

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Operation Testing of an Advanced Personalized Ventilation System

Energies ◽

10.3390/en12091596 ◽

2019 ◽

Vol 12 (9) ◽

pp. 1596 ◽

Cited By ~ 3

Author(s):

Csáky ◽

Kalmár ◽

Kalmár

Keyword(s):

Air Quality ◽

Thermal Comfort ◽

Indoor Air Quality ◽

Indoor Air ◽

Distribution System ◽

Noise Level ◽

Background Noise ◽

Ventilation System ◽

Air Distribution ◽

Personalized Ventilation

Using personalized ventilation systems in office buildings, important energy saving might be obtained, which may improve the indoor air quality and thermal comfort sensation of occupants at the same time. In this paper, the operation testing results of an advanced personalized ventilation system are presented. Eleven different air terminal devices were analyzed. Based on the obtained air velocities and turbulence intensities, one was chosen to perform thermal comfort experiments with subjects. It was shown that, in the case of elevated indoor temperatures, the thermal comfort sensation can be improved considerably. A series of measurements were carried out in order to determine the background noise level and the noise generated by the personalized ventilation system. It was shown that further developments of the air distribution system are needed.

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