Airflow Distribution and Microenvironment Evaluation of CMP Task Conditioning System

Solar Energy ◽  
2006 ◽  
Author(s):  
Youyin Jing ◽  
Guozhong Zheng
Keyword(s):  
Numerical Simulation ◽  
Thermal Comfort ◽  
Indoor Environment ◽  
Room Temperature ◽  
Working Environment ◽  
Turbulent Model ◽  
Flexible Control ◽  
Airflow Distribution ◽  
Air Blowing ◽  
Supply Velocity

Microenvironment of a typical office workplace consisting computer monitor panel (CMP) task conditioning systems was studied by numerical simulation. Two CMP task conditioning systems were operated while a conventional HVAC system supplied air through a diffuser located in the ceiling. Air was exhausted through a ducted ceiling-level grill. Numerical simulation by k-ε 3-D turbulent model was conducted to study the influence of supply velocity on microenvironment of CMP task conditioning system. Three task conditioning velocities, 0.8, 1.0 and 1.2 m/s were studied Temperature and velocity distribution, Draught Rating (DR) and Predicted Percentage of Dissatisfied (PPD) of the room and workstation were studied. Results showed that room temperature was distributed by region, and occupant was exactly in supplying area. Temperature around occupant was apparently lower than surrounding temperature. So task conditioning had high air-supplying efficiency. Results also showed that task conditioning can provide excellent working environment when supply velocity were well designed. Task conditioning may cause draught according to conventional thermal comfort standard. When supply velocity is 1.0 or 1.2 m/s, DR around head reached 25 or 30 and PPD reached 12 or 15, so it may be uncomfortable to occupant. However occupant can control supply velocity and air blowing distance of task conditioning system to maintain acceptable thermal comfort. To summarize, flexible control of task conditioning system can create a more comfortable indoor environment.

Airflow Distribution and Microenvironment Evaluation of MP Task Conditioning System

2007 ◽  
Author(s):  
Guozhong Zheng ◽  
Youyin Jing ◽  
Hongxia Huang ◽  
Lijun Shi
Keyword(s):  
Numerical Simulation ◽  
Velocity Distribution ◽  
Distribution Systems ◽  
Air Distribution ◽  
Hvac System ◽  
Breathing Zone ◽  
Airflow Distribution ◽  
Air Blowing ◽  
Clean Air ◽  
Supply Velocity

During recent years an increasing amount of attention has been paid to air distribution systems with which officer can individually condition the immediate environment of their workstations. Fanger suggested supplying ventilation air that is unmixed with room air, directly to the breathing zone of each occupant. Task conditioning aims to provide each occupant with personalized clean air direct to the breathing zone. Each occupant can control the environment at his/her workplace. Microenvironment of a typical office workplace consisting of movable panel (MP) task conditioning systems was studied by numerical simulation. MP task conditioning systems were operated while a conventional HVAC system supplied air through a diffuser located in the ceiling. Air was exhausted through a ducted ceiling-level grill. Numerical simulation of 3-D turbulent flow (k-ε closure) was separately conducted to study the influence of supply velocity, air blowing distance and size of MP supply outlet on microenvironment. Three task conditioning velocities, 0.6, 0.8 and 1.0m/s, three sizes 0.3×0.15, 0.3×0.1 and 0.25×0.08m and two air blowing distances were studied. In addition to analyzing temperature and velocity distribution, Draught Rating (DR) and Predicted Percentage of Dissatisfied (PPD) of the room and workstation were studied.

Analysis of Thermal Comfort and Microclimatic Conditions in Special Workplaces

2019 ◽  
Author(s):  
Zuzana Kolková ◽  
Peter Hrabovský ◽  
Jozef Matušov
Keyword(s):  
Thermal Comfort ◽  
Indoor Environment ◽  
Operating Conditions ◽  
Working Environment ◽  
Physical Parameters ◽  
Indoor Climate ◽  
Microclimatic Conditions ◽  
Radiant Temperature ◽  
Graphical Presentation

Microclimatic conditions and thermal comfort are important factors in the design of high quality buildings and the quality of working conditions for people in different operations. The importance of thermal comfort in the indoor environment can not be underestimated. A vast majority of complaints about indoor climate relate to poor thermal comfort. This paper presents an analysis of subjective thermal comfort measurement. The experiments were conducted to collect the data in the real conditions. ComfortSense system was used in these experiments. A Humidity and an Operative probe are available together with application software with graphical presentation of results including the Predicted Mean Vote (PMV) and Predicted Percentage Dissatisfied (PPD). The operating conditions are regulated by law in our country. The aim of the legislation is to protect people in the working environment and create appropriate health conditions for them. The goal of a thermal comfort analysis is finding an appropriate function of the physical parameters (background radiant temperature, air temperature, air humidity, wind speed, clothing, metabolic rate, and core temperature), which would yield the corresponding comfort/discomfort level.

scholarly journals Barriers on Establishing Passive Strategies in Office Spaces: A Case Study in a Historic University Building

2021 ◽  
Vol 13 (8) ◽  
pp. 4563
Author(s):  
Nuno Baía Baía Saraiva ◽  
Luisa Dias Dias Pereira ◽  
Adélio Rodrigues Gaspar ◽  
José Joaquim da Costa
Keyword(s):  
Thermal Comfort ◽  
Indoor Environment ◽  
Hvac Systems ◽  
Heritage Buildings ◽  
Full Capacity ◽  
Free Cooling ◽  
Passive Strategies ◽  
The University ◽  
Indoor Conditions

The adaptation of spaces to different usage typologies can be complex in heritage buildings. Facilities were initially planned for a specific type of use that, when changed, require additional measures to ensure a suitable indoor environment. Passive strategies—e.g., free cooling—are commonly used as an alternative without requiring equipment installation. However, its implementation often leads to unsatisfactory conditions. Therefore, it is important to clarify the main barriers to achieving thermal comfort in readapted historic buildings. The present work investigates the thermal comfort conditions reported by workers in office spaces of a historic building in the University of Coimbra. A monitoring campaign was carried out between May and September 2020 to assess indoor conditions’ quality. Due to the current pandemic of COVID-19, offices were not occupied at full capacity. A one-day evaluation of thermal comfort was made using a climate analyzer and six occupants were surveyed on 19 August 2020. The main results highlighted discomfort due to overheating of spaces. The causes were related to the combination of inadequate implementation of the free cooling actions and the building use. Furthermore, it was recommended the installation of HVAC systems in case of full capacity.

scholarly journals Numerical Simulation and Engineering Application of Coalbed Water Injection

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Yijie Shi ◽  
Pengfei Wang ◽  
Ronghua Liu ◽  
Xuanhao Tan ◽  
Wen Zhang
Keyword(s):  
Numerical Simulation ◽  
Process Parameters ◽  
Water Injection ◽  
Engineering Application ◽  
Working Environment ◽  
Engineering Practice ◽  
Characteristic Parameters ◽  
Injection Process ◽  
Working Face ◽  
Dust Reduction

Coalbed water injection is the most basic and effective dust-proof technology in the coal mining face. To understand the influence of coalbed water injection process parameters and coalbed characteristic parameters on coal wetting radius, this paper uses Fluent computational fluid dynamics software to systematically study the seepage process of coalbed water injection under different process parameters and coalbed characteristic parameters, calculation results of which are applied to engineering practice. The results show that the numerical simulation can help to predict the wetness range of coalbed water injection, and the results can provide guidance for the onsite design of coalbed water injection process parameters. The effect of dust reduction applied to onsite coalbed water injection is significant, with the average dust reduction rates during coal cutting and support moving being 67.85% and 46.07%, respectively, which effectively reduces the dust concentration on the working face and improves the working environment.

scholarly journals Thermal comfort in winter incorporating solar radiation effects at high altitudes and performance of improved passive solar design—Case of Lhasa

2020 ◽  
Author(s):  
Lingjiang Huang ◽  
Jian Kang
Keyword(s):  
Solar Radiation ◽  
Thermal Comfort ◽  
Energy Saving ◽  
Solar Irradiance ◽  
Indoor Environment ◽  
Thermal Mass ◽  
High Altitudes ◽  
Energy Saving Potential ◽  
Environment Control ◽  
Passive Solar

AbstractThe solar incidence on an indoor environment and its occupants has significant impacts on indoor thermal comfort. It can bring favorable passive solar heating and can result in undesired overheating (even in winter). This problem becomes more critical for high altitudes with high intensity of solar irradiance, while received limited attention. In this study, we explored the specific overheating and rising thermal discomfort in winter in Lhasa as a typical location of a cold climate at high altitudes. First, we evaluated the thermal comfort incorporating solar radiation effect in winter by field measurements. Subsequently, we investigated local occupant adaptive responses (considering the impact of direct solar irradiance). This was followed by a simulation study of assessment of annual based thermal comfort and the effect on energy-saving potential by current solar adjustment. Finally, we discussed winter shading design for high altitudes for both solar shading and passive solar use at high altitudes, and evaluated thermal mass shading with solar louvers in terms of indoor environment control. The results reveal that considerable indoor overheating occurs during the whole winter season instead of summer in Lhasa, with over two-thirds of daytime beyond the comfort range. Further, various adaptive behaviors are adopted by occupants in response to overheating due to the solar radiation. Moreover, it is found that the energy-saving potential might be overestimated by 1.9 times with current window to wall ratio requirements in local design standards and building codes due to the thermal adaption by drawing curtains. The developed thermal mass shading is efficient in achieving an improved indoor thermal environment by reducing overheating time to an average of 62.2% during the winter and a corresponding increase of comfort time.

Numerical Simulation of Muzzle Flow Field of Gun Based on CFD

2013 ◽  
Vol 291-294 ◽  
pp. 1981-1984
Author(s):  
Zhang Xia Guo ◽  
Yu Tian Pan ◽  
Yong Cun Wang ◽  
Hai Yan Zhang
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Stokes Equation ◽  
Wave Structure ◽  
Flow Fields ◽  
Single Equation ◽  
Navier Stokes ◽  
Turbulent Model ◽  
Navier Stokes Equation ◽  
Numerical Simulation Result

Gunpowder was released in an instant when the pill fly out of the shell during the firing, and then formed a complicated flow fields about the muzzle when the gas expanded sharply. Using the 2 d axisymmetric Navier-Stokes equation combined with single equation turbulent model to conduct the numerical simulation of the process of gunpowder gass evacuating out of the shell without muzzle regardless of the pill’s movement. The numerical simulation result was identical with the experimental. Then simulated the evacuating process of gunpowder gass of an artillery with muzzle brake. The result showed complicated wave structure of the flow fields with the muzzle brake and analysed the influence of muzzle brake to the gass flow field distribution.

scholarly journals Indoor Thermal Comfort Analysis: A Case Study of Modern and Traditional Buildings in Hot-Arid Climatic Region of Ethiopia

Urban Science ◽  
2021 ◽  
Vol 5 (3) ◽  
pp. 53
Author(s):  
Haven Hailu ◽  
Eshetu Gelan ◽  
Yared Girma
Keyword(s):  
Thermal Comfort ◽  
Significant Role ◽  
Indoor Environment ◽  
Thermal Sensation ◽  
Climatic Region ◽  
Contributing Factors ◽  
Objective Measurements ◽  
Indoor Thermal Comfort ◽  
Adaptive Comfort

Indoor thermal comfort is an essential aspect of sustainable architecture and it is critical in maintaining a safe indoor environment. Expectations, acceptability, and preferences of traditional and modern buildings are different in terms of thermal comfort. This study, therefore, attempts to evaluate the indoor thermal comforts of modern and traditional buildings and identify the contributing factors that impede or facilitate indoor thermal comfort in Semera city, Ethiopia. This study employed subjective and objective measurements. The subjective measurement is based on the ASHRAE seven-point thermal sensation scale. An adaptive comfort model was employed according to the ASHRAE standard to evaluate indoor thermal comfort. The results revealed that with regards to thermal sensational votes between −1 and +1, 88% of the respondents are satisfied with the indoor environment in traditional houses, while in modern houses this figure is 22%. Likewise, 83% of occupants in traditional houses expressed a preference for their homes to remain the same or be only slightly cooler or warmer. Traditional houses were, on average, in compliance with the 80% acceptability band of the adaptive comfort standard. The study investigated that traditional building techniques and materials, in combination with consideration of microclimate, were found to play a significant role in regulating the indoor environment.

Numerical Simulation of Gasoline Blending with Two Different Mixing Systems

2011 ◽  
Vol 317-319 ◽  
pp. 2107-2112
Author(s):  
Song Ying Chen ◽  
Fu Chao Xie ◽  
Jun Jie Mao
Keyword(s):  
Numerical Simulation ◽  
Reynolds Equation ◽  
Mixing Time ◽  
Three Dimensional ◽  
Momentum Equation ◽  
Moving Mesh ◽  
Mixing Models ◽  
Turbulent Model ◽  
Jet Mixing ◽  
Mixing Effects

Based on two different mixing systems: Rotary Jet Mixing (RJM) system and side-entering agitator, two kinds of three-dimensional gasoline components mixing models are established. The incompressible Reynolds equation is selected as the momentum equation and the algorithm of SIMPLE is used to simulate the jet facility. To get the mixing time, moving mesh and the standard k-ε turbulent model has been employed in the multiphase unsteady flow. The results show that the dead areas of RJM are less than side-entering agitator, and the mixing effects are much better. Furthermore, the mixing time of RJM is only 58.2s, which is 69.7% of Side-entering Agitator.

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