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.

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.

Comparison Between Numerical and Experimental Results of Airflow Distribution in Diffuser Based Data Center

2012 ◽  
Vol 134 (1) ◽  
Author(s):  
Qifei Jian ◽  
Qiaoli Wang ◽  
Haoting Wang ◽  
Zheng Zuo
Keyword(s):  
Data Center ◽  
Distribution Systems ◽  
Volume Flow Rate ◽  
Mathematic Model ◽  
Experimental Results ◽  
Air Distribution ◽  
Test Results ◽  
Airflow Distribution ◽  
Computational Fluid Dynamics Cfd

This paper studies the flow and temperature patterns in an overhead diffuser based data center. In-situ measurements of the data center were carried out to validate a mathematic model for predicting the effect of different air distribution systems. With the measured data of temperatures and airflow velocities, the mathematic model is constructed using a commercial Computational Fluid Dynamics (CFD) software and experimental data to present a comparison between test results and numerical simulations. The area of the data center is 311 square meters and the heat load of the equipment is 320~360 watt per square meter. In-situ temperatures and humidity of the data center were measured with an Automatic Temperature and Humidity measuring instrument, whose error is ±0.5 °C. The discrepancy of the temperature and velocity between the numerical and experimental results were within ±2.3 °C and ±1.8 m/s, respectively. In addition, analysis shows that changing the volume flow rate of the cold air delivered to some diffusers can optimize the temperature field and thereby save the energy.

scholarly journals Is building ventilation a process of diluting contaminants or delivering clean air?

2019 ◽  
Vol 29 (6) ◽  
pp. 768-774 ◽  
Author(s):  
Mats Sandberg ◽  
Alan Kabanshi ◽  
Hans Wigö
Keyword(s):  
Distribution Systems ◽  
Ambient Air ◽  
Single Parameter ◽  
Air Distribution ◽  
Contaminant Concentration ◽  
Clean Air ◽  
Pros And Cons ◽  
Building Ventilation ◽  
Personalized Ventilation

The purpose of this paper is to discuss the performance of air distribution systems intended for dilution of contaminants (e.g. mixing ventilation) and those intended for delivery of clean air to local regions within rooms (e.g. personalized ventilation). We first start by distinguishing the systems by their visiting frequency behaviour. Then, the performance of the systems with respect to their possibility to influence contaminant concentration in the room or regions within the room is dealt with. Dilution capacity concept for mixing systems is discussed, and delivery capacity concept for systems intended to deliver clean air locally is introduced. Various ways for supply of clean air to regions within the room are presented and their pros and cons are discussed. In delivery capacity systems, the most important single parameter is the entrainment of ambient air into the primary supply flow. Therefore, methods of determining entrainment in these systems need to be defined and the results should be included when describing the performance of the air terminal devices.

Indoor Environment Numerical Simulation of All Cold Air Distribution System With Stratified Air Conditioning

2008 ◽  
Author(s):  
Wei Bing ◽  
Li Li ◽  
Jiang Lu ◽  
Zhang Wei
Keyword(s):  
Numerical Simulation ◽  
Distribution System ◽  
Air Conditioning ◽  
Distribution Systems ◽  
Dew Point ◽  
Air Distribution ◽  
Large Space ◽  
Cold Air ◽  
Point Temperature ◽  
Dew Point Temperature

At present all cold air distribution systems are being used widely due to their advantages of smaller ductwork, shorter floor-to-floor height and less energy consumption etc. They are mostly used in VAV (Variable Air Volume) systems or with the radiant panel systems in the office and residential buildings at the supply air dew point temperature of 6∼10°C, rarely used in large space buildings. The technology of stratified air conditioning is one of the energy saving technologies to large space buildings, which has been popularly used in the conventional air supply systems with the supply air dew point temperature of 11∼16°C. In this paper, the cold air distribution system and the stratified air conditioning technology in a large space building are combined to study. With the method of CFD, the indoor thermal environment of a large space workshop is simulated. The velocity and the temperature as well as the relative humidity fields under different air flow modes are presented, analyzed and compared. With the help of numerical simulation results, the optimal airflow mode is proposed, which show that the all cold air distribution with the stratified air conditioning is a good option for large space buildings. All these above will be good references to the application of cold air distribution system and the selection of the airflow mode in large space buildings.

Numerical Simulation of Air Distribution Plate at the Inlet of Wet Electrostatic Precipitator

2014 ◽  
Vol 494-495 ◽  
pp. 756-762 ◽  
Author(s):  
Jin Feng Zhang ◽  
Zai Xing Li ◽  
Wei Li ◽  
Ying Gao ◽  
Qiang Li
Keyword(s):  
Numerical Simulation ◽  
Optimal Allocation ◽  
Electrostatic Precipitator ◽  
Air Distribution ◽  
Dust Collector ◽  
Key Factors ◽  
Airflow Distribution ◽  
Distribution Uniformity ◽  
Design Requirements ◽  
Distribution Plate

The air distribution uniformity of electrostatic precipitator is one of the key factors to affect the efficiency of dust collector. A layer of air distribution plate was set in precipitator and its opening rate of distribution plate was adjusted to explore the optimal allocation of air distribution in the precipitator. With the design requirements, we used the Fluent to simulate the airflow distribution in the precipitator. The results show that it can obtain more uniform air distribution to adjust the hole shape and the opening rate of air distribution plate, and the efficiency is ideal when the opening rate is 30%.

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