Displacement Ventilation Performance
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Displacement Ventilation Performance
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Author :
language : en
Publisher:
Release Date : 1993-03-01
Displacement Ventilation Performance written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1993-03-01 with categories.
System Performance Evaluation And Design Guidelines For Displacement Ventilation
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Author : Qingyan Chen
language : en
Publisher: American Society of Heating Refrigerating and Air-Conditioning Engineers
Release Date : 2003
System Performance Evaluation And Design Guidelines For Displacement Ventilation written by Qingyan Chen and has been published by American Society of Heating Refrigerating and Air-Conditioning Engineers this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003 with Displacement ventilation categories.
This book presents system performance evaluation, and includes a 10-step design guideline for displacement ventilation systems for U.S. buildings. These design guidelines present two important models: 1) to calculate the temperature difference between the head and the foot level of an occupant; and 2) one to determine the ventilation effectiveness at the breathing level.The book notes that: A displacement ventilation system can provide a thermally comfortable indoor environment at a high cooling load through careful design. The indoor air quality in a space with displacement ventilation is better if the contaminant sources are associates with the heat sources. The displacement ventilation system can also save energy but requires a separate heating system if it is applied to building perimeter zones. 6 x 9, soft cover.
The Performance Of Displacement Ventilation Systems
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Author : Elisabeth Mundt
language : en
Publisher:
Release Date : 1996
The Performance Of Displacement Ventilation Systems written by Elisabeth Mundt and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1996 with Displacement ventilation categories.
In a displacement ventilated room the air flow pattern is mainly governed by the convection flows from different heat sources. The interaction of the convection flows influences the contamination distribution in the room. This distribution also depends on the position and strength of the contamination sources. Local va lues at the same height in the room may differ significantly. The distribution i s also sensitive to 'disturbances' in the form of e.g. persons mowing around. Th e factors governing the air flow patterns were investigated by measurements of t emperature gradients, convection flow rates in plumes and contamination distribu tions. The efficiency of the ventilation was measured for many different combina tions of ventilation flow rates, heat loads and contamination sources. The tempe rature gradient was strongly correlated to the ventilation flow rate and very st able. People mowing around or walking in and out of the room did not influence t he shape of the gradient. Models for the temperature gradient in balanced and un balanced conditions were developed. The convection flow rate in a plume and its maximum height were influenced by the temperature gradient. Models for the conve ction flow rate in a plume from a point or a line source are given including the height where the plumes disintegrate due to the gradient in the surroundings. T he air change efficiency increased with the ventilation flow rate as long as the convection plumes reached the ceiling, and decreased when the plume disintegrat ed below the ceiling. The contaminant removal effectiveness was dependent on the position of the contamination (tracer gas) source and on the interaction of the convection flows in the room. A small change in the position of the tracer gas source caused a great change in the contaminant removal effectiveness. The inter action of the different convection flows in the room also caused a great variati on in the local air quality indices measured at the same level at different posi tions both with the tracer gas source in a plume and outside a plume. When the t racer gas source was outside a plume a heavy tracer gas spread to the floor in a ll measured cases while a light tracer gas spread to the floor only at low tempe rature gradients independent of the ventilation flow rate. Opening and closing o f a door was enough to ...
Performance Evaluation And Development Of Design Guidelines For Displacement Ventilation
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Author : Qingyan Chen
language : en
Publisher:
Release Date : 1999
Performance Evaluation And Development Of Design Guidelines For Displacement Ventilation written by Qingyan Chen and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1999 with Air conditioning categories.
Thermal And Ventilation Performance Of Combined Passive Chilled Beam Displacement Ventilation Systems
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Author : Wenyu Shan
language : en
Publisher:
Release Date : 2017
Thermal And Ventilation Performance Of Combined Passive Chilled Beam Displacement Ventilation Systems written by Wenyu Shan and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.
Chilled beam systems provide sensible cooling in the occupied space using chilled water flowing through modular beams mounted to a ceiling. Chilled beam systems can achieve cooling energy saving larger compare to all-air system due to greater thermal energy delivered by the chilled water than air, and thus are well-suited for spaces with relatively large sensible cooling loads as an energy-saving method. The objective of the present study is to study air conditioning performance of combined passive chilled beam (PCB) - displacement ventilation (DV) systems. Using computational fluid dynamics (CFD) simulations, the amount of sensible cooling by PCB and its impacts on ventilation effectiveness and thermal comfort in a typical office room are investigated. Simulations for combined PCB-DV system under different cooling load and ventilation conditions are conducted to study the system performance. The study results reveal that the thermal and ventilation performance can vary significantly with type of ventilation strategy, type of air supply diffuser, PCB cooling output and supply air temperature. However, arrangement of heat sources has a marginal effect on the performance of combined PCB-DV systems. With a PCB cooling output of 50% of the total cooling load and the supply air temperature of 19-20 , the combined PCB-DV system can achieve the best performance in terms of energy use, ventilation effectiveness, and occupant thermal comfort.
Ventilation Systems
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Author : Hazim B. Awbi
language : en
Publisher: Psychology Press
Release Date : 2008
Ventilation Systems written by Hazim B. Awbi and has been published by Psychology Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with Technology & Engineering categories.
This comprehensive account of the methods used for ventilating buildings and the type of systems currently in use for achieving the desired indoor environment will be of particular interest to graduate students, professionals and researchers.
Performance Of Displacement Ventilation At Pori Works Ltd
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Author : Raimo Niemelä
language : en
Publisher:
Release Date : 1996
Performance Of Displacement Ventilation At Pori Works Ltd written by Raimo Niemelä and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1996 with categories.
A Ventilation Strategy Based On Confluent Jets
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Author : Setareh Janbakhsh
language : en
Publisher: Linköping University Electronic Press
Release Date : 2015-04-27
A Ventilation Strategy Based On Confluent Jets written by Setareh Janbakhsh and has been published by Linköping University Electronic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-04-27 with categories.
This study presents air distribution systems that are based on confluent jets; this system can be of interest for the establishment of indoor environments, to fulfill the goals of indoor climate and energy-efficient usage. The main objective of this study is to provide deeper understanding of the flow field development of a supply device that is designed based on wall confluent jets and to investigate the ventilation performance by experimental and numerical methods. In this study, the supply device can be described as an array of round jets on a flat surface attached to a side wall. Multiple round jets that issue from supply device apertures are combined at a certain distance downstream from the device and behave as a united jet or so-called confluent jets. Multiple round jets that are generated from the supply device move downward and are attached to the wall at the primary region, due to the Coanda effect, and then they become wall confluent jets until the floor wall is reached. A wall jet in a secondary region is formed along the floor after the stagnation region. The characteristics of the flow field and the ventilation performance of conventional wall confluent jets and modified wall confluent jets supply devices are investigated experimentally in an office test room. The study of the modified wall confluent jets is intended to improve the efficiency of the conventional one while maintaining acceptable thermal comfort in an office environment. The results show that the modified wall confluent jets supply device can provide acceptable thermal comfort for the occupant with lower airflow rate compared to the conventional wall confluent jets supply device. Numerical predictions using three turbulence models (renormalization group (RNG k– ?), realizable (Re k– ?), and shear stress transport (SST k– ?) are evaluated by measurement results. The computational box and nozzle plate models are used to model the inlet boundary conditions of the nozzle device. In the isothermal study, the wall confluent jets in the primary region and the wall jet in the secondary region, when predicted by the three turbulence models, are in good agreement with the measurements. The non-isothermal validation studies show that the SST k– ? model is slightly better at predicting the wall confluent jets than the other two models. The SST k– ? model is used to investigate the effects of the nozzle diameter, number of nozzles, nozzle array configuration, and inlet discharge height on the ventilation performance of the proposed wall confluent jets supply device. The nozzle diameter and number of nozzles play important roles in determining the airflow pattern, temperature field, and draught distribution. Increased temperature stratification and less draught distribution are achieved by increasing the nozzle diameter and number of nozzles. The supply device with smaller nozzle diameters and fewer nozzles yields rather uniform temperature distribution due to the dominant effect of mixing. The flow behavior is nearly independent of the inlet discharge height for the studied range. The proposed wall confluent jets supply device is compared with a mixing supply device, impinging supply device and displacement supply device. The results show that the proposed wall confluent jets supply device has the combined behavior of both mixing and stratification principles. The proposed wall confluent jets supply device provides better overall ventilation performance than the mixing and displacement supply devices used in this study. This study covers also another application of confluent jets that is based on impinging technology. The supply device under consideration has an array of round jets on a curve. Multiple jets issue from the supply device aperture, in which the supply device is positioned vertically and the jets are directed against a target wall. The flow behavior and ventilation performance of the impinging confluent jets supply device is studied experimentally in an industrial premise. The results show that the impinging confluent jets supply device maintains acceptable thermal comfort in the occupied zone by creating well-distributed airflow during cold and hot seasons.
Evaluation Of Displacement Ventilation For Use In High Ceiling Facilities
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Author : Anthony Daniel Arens
language : en
Publisher:
Release Date : 2000
Evaluation Of Displacement Ventilation For Use In High Ceiling Facilities written by Anthony Daniel Arens and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2000 with categories.
Displacement Ventilation And Static Cooling Devices
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Author : Tariq Abbas
language : en
Publisher:
Release Date : 1999
Displacement Ventilation And Static Cooling Devices written by Tariq Abbas and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1999 with Buildings categories.
This volume presents the accepted practice for the design and implementation of displacement ventilation systems with and without static cooling devices, based on research as well as the views of consultants and manufacturers considered to be experts in this field. The book presents a detailed description of how displacement ventilation systems work, applications where they can be used, design issues, calculation procedures, system performance in terms of temperature, air speed, thermal comfort and indoor air quality as well as control, installation and maintenance.
