scholarly journals Experimental Investigation of the Air Exchange Effectiveness of Push-Pull Ventilation Devices

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5817
Author(s):  
Sven Auerswald ◽  
Carina Hörberg ◽  
Thibault Pflug ◽  
Jens Pfafferott ◽  
Constanze Bongs ◽  
...  
Keyword(s):  
Heat Dissipation ◽  
Residential Buildings ◽  
Air Flow ◽  
Operation Mode ◽  
Ventilation System ◽  
Field Measurements ◽  
Gas Analysis ◽  
Decentralised Systems ◽  
Set Up ◽  
Air Exchange

The increasing installation numbers of ventilation units in residential buildings are driven by legal objectives to improve their energy efficiency. The dimensioning of a ventilation system for nearly zero energy buildings is usually based on the air flow rate desired by the clients or requested by technical regulations. However, this does not necessarily lead to a system actually able to renew the air volume of the living space effectively. In recent years decentralised systems with an alternating operation mode and fairly good energy efficiencies entered the market and following question was raised: “Does this operation mode allow an efficient air renewal?” This question can be answered experimentally by performing a tracer gas analysis. In the presented study, a total of 15 preliminary tests are carried out in a climatic chamber representing a single room equipped with two push-pull devices. The tests include summer, winter and isothermal supply air conditions since this parameter variation is missing till now for push-pull devices. Further investigations are dedicated to the effect of thermal convection due to human heat dissipation on the room air flow. In dependence on these boundary conditions, the determined air exchange efficiency varies, lagging behind the expected range 0.5 < εa < 1 in almost all cases, indicating insufficient air exchange including short-circuiting. Local air exchange values suggest inhomogeneous air renewal depending on the distance to the indoor apertures as well as the temperature gradients between in- and outdoor. The tested measurement set-up is applicable for field measurements.

Experimental Study of Heat Storage Unit Made of PCM-gypsum Composite Integrated with the Ventilation System of the Building

2017 ◽  
Author(s):  
Maciej Jaworski ◽  
Hanna Jędrzejuk ◽  
Rafał Laskowski
Keyword(s):  
Heat Storage ◽  
Air Flow ◽  
Ventilation System ◽  
Ambient Air ◽  
Heat Transfer Process ◽  
Night Time ◽  
Storage Unit ◽  
Regenerative Heat ◽  
Air Temperatures ◽  
Set Up

In the paper a special heat storage unit for building applications is presented. It has a form of a ceiling panel that is made of PCM-gypsum mortar composite and it contains internal channels for air flow, since it is designed as a part of ventilation system of the building. The panel works as a regenerative heat exchanger with phase change material (PCM) as a prevailing heat storage medium. When a melting point of PCM is properly chosen it is possible that air temperature flowing into the building reach a level corresponding to thermal comfort conditions, regardless the temperature at the intake. Warm air (during a day) releases heat basically to PCM causing its melting. During night time cool ambient air is heated up while it takes back heat accumulated in PCM. An experimental set-up based on the above concept was developed. A series of tests in different conditions (for variable inlet air temperatures, air flow rates) were performed. Information on thermal performance of the ceiling panel as well as detailed data on heat transfer process were obtained and discussed in the paper.

scholarly journals Assessment of Natural Ventilation System for a Typical Residential House in Poland

2016 ◽  
Vol 22 (3) ◽  
pp. 25-44 ◽  
Author(s):  
Romana Antczak-Jarząbska ◽  
Marek Krzaczek
Keyword(s):  
Natural Ventilation ◽  
Flow Direction ◽  
Air Flow ◽  
Ventilation System ◽  
Winter Season ◽  
Residential Building ◽  
Field Measurements ◽  
Significant Deterioration ◽  
Climate Conditions ◽  
Ventilation Performance

Abstract The paper presents the research results of field measurements campaign of natural ventilation performance and effectiveness in a residential building. The building is located in the microclimate whose parameters differ significantly in relation to a representative weather station. The measurement system recorded climate parameters and the physical variables characterizing the air flow in the rooms within 14 days of the winter season. The measurement results showed that in spite of proper design and construction of the ventilation system, unfavorable microclimatic conditions that differed from the predicted ones caused significant reduction in the efficiency of the ventilation system. Also, during some time periods, external climate conditions caused an opposite air flow direction in the vent inlets and outlets, leading to a significant deterioration of air quality and thermal comfort measured by CO2 concentration and PMV index in a residential area.

scholarly journals Analysis of the need of detailed modelling for the assessment of indoor air quality in residential buildings

2019 ◽  
Vol 111 ◽  
pp. 04043
Author(s):  
Louis Cony-Renaud-Salis ◽  
Nouamane Belhaj ◽  
Olivier Ramalho ◽  
Marc Abadie
Keyword(s):  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Large Scale ◽  
Residential Buildings ◽  
Ventilation System ◽  
Field Measurements ◽  
Well Being ◽  
Good Alternative ◽  
Specific Care

Home represents an important part of the time spent indoors and is the emblematic place of a family need, e.g. well-being, comfort and safety. In France, health agencies provide information and raise the awareness of the public on health risks and on factors likely to affect the quality of indoor air. However, indoor air quality remains difficult to assess for health investigators. A solution would be to resort to field measurements, but they are expensive and hard to apply to a large-scale population when considering the numerous pollutants found indoors. Therefore, numerical simulation represents a good alternative when accurate and realistic input data are used. We already designed such a model of a dwelling prototype using a type 98 coupling procedure between CONTAM (airflow rates and pollutants concentration determination) and TRNSYS (thermal and moisture calculation). We paid a lot of attention to the details that we thought were important: dwelling multi-zonal representation, envelope airtightness, ventilation system elements (pressure driven inlet and outlet, ducts, fan characteristics), presence of furniture, people activity and location… Nevertheless, the design of this simulation requires a very specific care. This very last point naturally induces a debate: is it necessary to design the simulation to be as accurate and realistic as it actually is, or will a simpler model provide similar results? In this study, we aim to answer that question by evaluating the sensitivity of the ULR-IAQ multipollutant index, defined in a previous study, to different levels of modelling complexity.

scholarly journals Short-term <sup>222</sup>Rn activity concentration changes in underground spaces with limited air exchange with the atmosphere

2011 ◽  
Vol 11 (4) ◽  
pp. 1179-1188 ◽  
Author(s):  
L. Fijałkowska-Lichwa ◽  
T. A. Przylibski
Keyword(s):  
Mechanical Ventilation ◽  
Radiation Protection ◽  
Activity Concentration ◽  
Residential Buildings ◽  
Ventilation System ◽  
The Other ◽  
Uranium Mine ◽  
Activity Concentrations ◽  
Concentration Changes ◽  
Air Exchange

Abstract. The authors investigated short-time changes in 222Rn activity concentration occurring yearly in two underground tourist facilities with limited air exchange with the atmosphere. One of them is Niedźwiedzia (Bear) Cave in Kletno, Poland – a natural space equipped with locks ensuring isolation from the atmosphere. The other site is Fluorite Adit in Kletno, a section of a disused uranium mine. This adit is equipped with a mechanical ventilation system, operated periodically outside the opening times (at night). Both sites are situated within the same metamorphic rock complex, at similar altitudes, about 2 km apart. The measurements conducted revealed spring and autumn occurrence of convective air movements. In Bear Cave, this process causes a reduction in 222Rn activity concentration in the daytime, i.e. when tourists, guides and other staff are present in the cave. From the point of view of radiation protection, this is the best situation. For the rest of the year, daily concentrations of 222Rn activity in the cave are very stable. In Fluorite Adit, on the other hand, significant variations in daily 222Rn activity concentrations are recorded almost all year round. These changes are determined by the periods of activity and inactivity of mechanical ventilation. Unfortunately this is inactive in the daytime, which results in the highest values of 222Rn activity concentration at the times when tourists and staff are present in the adit. Slightly lower concentrations of radon in Fluorite Adit are recorded in the winter season, when convective air movements carry a substantial amount of radon out into the atmosphere. The incorrect usage of mechanical ventilation in Fluorite Adit results in the most unfavourable conditions in terms of radiation protection. The staff working in that facility are exposed practically throughout the year to the highest 222Rn activity concentrations, both at work (in the adit) and at home (outside their working hours). Therefore, not very well considered solution for the ventilation system not only does not prevent radioactive exposure of the staff, but can even increase it. The authors have also observed comparable characteristics of the annual patterns of 222Rn activity concentration changes in underground spaces and residential buildings situated in the same or similar climatic zones.

Numerical Study of Internal Fire Whirls in a Kitchen With Ceiling Vents

2013 ◽  
Author(s):  
W. K. Chow ◽  
N. Cai ◽  
Y. Gao
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Numerical Study ◽  
Air Flow ◽  
Ventilation System ◽  
Necessary Condition ◽  
Temperature Distributions ◽  
Computational Fluid Dynamics Cfd ◽  
Fire Whirl ◽  
Set Up

The characteristics of flame rotation induced by a fire at the top of kitchen stove were studied numerically with Computational Fluid Dynamics (CFD). Four cases with different locations of fire sources and vents were set up; simulations of swirling air flow and temperature distributions in the kitchen room were carried out. Ventilation by ceiling vents was identified as the necessary condition for internal fire whirl. Recommendations on the design of kitchen ventilation system were made.

scholarly journals Study of a segmented ventilation system of the brake disc and determination of the aerodynamic and heat exchange characteristics of the airflow

2022 ◽  
Vol 25 (6) ◽  
pp. 720-732
Author(s):  
P. A. Polyakov
Keyword(s):  
Boundary Layer ◽  
Heat Exchange ◽  
Work Performance ◽  
Heat Dissipation ◽  
Air Flow ◽  
Ventilation System ◽  
Aerodynamic Characteristics ◽  
Design Parameters ◽  
Brake Disc ◽  
Cfd Modelling

This study aims determine a relationship between the aerodynamic and heat exchange characteristics of the air flow in a segmented ventilation system of the brake disc with improved heat dissipation in the boundary layer of the air flow. Classical equations of heat and mass transfer in the boundary layer of the air flow cooling the brake disc ventilation chamber were used. The cooling performance of the system was assessed using the method of similarity. The obtained theoretical findings were confirmed by CFD-modelling. Mathematical models were developed for vented discs with both continuous grooves and slotted grooves. A criterion for assessing the performance of brake disc ventilation systems was proposed, consisting in turbulization of the air flow inside the device under study. According to the obtained analytical dependencies, a 20-fold acceleration of the air flow decreases the turbulization parameter by 1.24 times. An increase in the temperature difference in the boundary layer by 8 times leads to an increase in the turbulization parame-ter by 86.2 times. Using the criterion proposed for assessing the work performance, the aerodynamic and heat exchange characteristics of the system under study were calculated. As a result, a relationship between the design parameters of the segmented ventilation system and improved heat dissipation in the boundary layer of the cooling air flow is proposed. The conducted CFD modelling confirmed the aerodynamic characteristics of the system under study obtained theoretical-ly. This mathematical model together with the turbulization parameter can be used when both developing modern vented brake discs and assessing the existing cooling systems of friction units in order to minimize the possibility of reduced heat exchange processes.

Experimental Quantification of Air Permeability of Building Envelope with Installed Controlled Ventilation System - Case Study

2019 ◽  
Vol 887 ◽  
pp. 571-578
Author(s):  
Boris Bielek ◽  
Daniel Szabó
Keyword(s):  
Exchange Rate ◽  
Residential Buildings ◽  
Ventilation System ◽  
Air Permeability ◽  
Building Envelope ◽  
Test Method ◽  
Air Exchange Rate ◽  
Controlled Ventilation ◽  
Air Infiltration ◽  
Air Exchange

To meet the increasingly stringent requirements of standard energy consumption and thus reducing operating costs of buildings, it is necessary to use energy-saving elements of technical equipment and eliminate heat loss through the building envelope. The biggest losses are caused by heat transmission and ventilation in the form of uncontrolled air infiltration through the building envelope. Their elimination can be achieved by improving the thermal technical quantification of building envelope and increase its airtightness. Determination of air permeability as a measure of quality building envelope is possible using the method of measuring devices Blower-Door test. Any defects can be detected by detection tools, then propose a suitable method for their removal and thus prevent unwanted unregulated air infiltration into the interior. On the other hand, are opposed to the health requirements required air exchange in the room, which is a significant reason for the transformation of this mode of ventilation by uncontrolled air infiltration to a controllable ventilation system. The subject of the paper is in-situ measurement of air permeability of specific apartment envelope by Blower-Door test method and comparison the efficacy of the installed controlled ventilation system and hygiene requirements of the ventilation intensity for residential buildings. Laboratory verification of façade ventilation unit parameters in big pressure chamber - measurement of inlet ventilation flap airflows at variable pressure differences. Methodology for the measurement by Blower-Door test method to determine the air permeability of building envelope structures and functionality of controlled ventilation system was based on a series of 10 measurements in 5 regimes. The overall air permeability of the building envelope or its integrated part may be verified using the total air exchange rate n50at 50 Pa pressure difference, determined experimentally according to STN EN 13829. Comparison of measured values with standard values recommended by some European countries with a similar climate with sealed and with unsealed ventilation flaps, which can determine the impact on the overall airtightness of the building envelope. Calculation of total hygiene required air exchange rate of the apartment and its comparison with actual measured values by Blower-Door test method.

scholarly journals Method of the boiler room ventilation system efficiency experimental determination

2020 ◽  
Vol 2020 (2) ◽  
pp. 84-91
Author(s):  
Orest Voznyak ◽  
◽  
Yuriy Yurkevych ◽  
Iryna Sukholova ◽  
Oleksandr Dovbush ◽  
...  
Keyword(s):  
Experimental Determination ◽  
Average Velocity ◽  
Air Flow ◽  
Ventilation System ◽  
Experimental Studies ◽  
Air Velocity ◽  
Air Jets ◽  
Boiler Room ◽  
Air Exchange

The issue of the normative air exchange ensuring in the premises of the boiler houses is extremely important. The article presents the results of theoretical and experimental studies of air velocity determination in the distribution of air by round and compact jets in the boiler room. Graphical and analytical dependences are given. The research results substantiate the higher accuracy of the average air flow velocity determination in small boiler rooms. The aim of the work is to develop a method for experimental determination of the efficiency of the ventilation system in the boiler room; to increase of the accuracy of the average velocity determination of the round and the compact air jets in the plane of the supply nozzle to ensure the normative air exchange of the boiler room and to substantiate of the calculation method. The characteristics and patterns of development of round and compact air jets in the premises are established and the calculated dependences are obtained. The unitless integral air velocity for the round and compact air jets in the boiler room is established. Calculation dependences for determining of the air flow rate in the boiler room have been obtained. It is substantiated that the application of the proposed method will significantly increase the accuracy of air exchange determination in the boiler rooms to ensure the required value in accordance with regulatory requirements. Also it is substantiated that to obtain satisfactory experimental results on speed measurements in the boiler room, it is necessary to measure the speed in the center of the supply nozzle several times with maximum accuracy. Then multiply the result by the relative average velocity: for a round jet vav = 0,26 and for a compact jet – vav = 0,2025. The obtained results allow to avoid a significant error (19 %) in determining the required air exchange ventilation of the boiler room. Recommendations for the practical determination of the calculated values to ensure proper ventilation of the boiler rooms are given.

scholarly journals Natural balanced ventilation. Simulations part 2

2018 ◽  
Vol 49 ◽  
pp. 00026
Author(s):  
Tomasz Gaczoł
Keyword(s):  
Natural Ventilation ◽  
Residential Buildings ◽  
Air Flow ◽  
Ventilation System ◽  
Flow Analysis ◽  
Comfort Level ◽  
Test Results ◽  
Pressure System ◽  
Exhaust Duct ◽  
Flow Through

The paper is devoted to test results of air flow through natural ventilation supply-exhaust ducts in the rooms located on the upper floor of the building that were conducted in ANSYS Fluent software. Three types of solutions were selected for the tests: air inflow into the room through the air intake located at the basement level, air inflow through the window ventilator (although no longer used, this solution can be found in many existing residential buildings) and the natural ventilation system supported with the so-called “solar chimney” that is usually a glass superstructure, located on the roof of the building above the ventilation ducts. All simulations were conducted with an outdoor temperature of +3 degrees C. The indoor temperature is + 20 degrees C, considered to be the minimum thermal comfort level. The simulations concerned such issues as: pressure system inside the room and in the exhaust duct, distribution of air temperatures in the room, vector direction of air flow through supply and exhaust ducts and in the room. Tests conducted using a computer method of air flow analysis in ducts and in the analysed room indicate that the developed natural balanced ventilation system is a good solution, especially when building sealing is so common. In all cases presented, it meets the normative regulations and requirements for the ventilation air stream and the air exchange rate in the room. The paper (second part) describes test results concerning the room located on the upper floor of the building, i.e. with a long 9-meter long supply duct and a short 3-meter long exhaust duct.

scholarly journals RESEARCH OF APARTMENTS’ AIR REGIME IN THE PROCESS OF OPERATION AND RECONSTRUCTION

2019 ◽  
Vol 4 (10) ◽  
pp. 53-59
Author(s):  
О. Тирон ◽  
O. Tiron ◽  
Е. Попов ◽  
E. Popov
Keyword(s):  
Natural Ventilation ◽  
Residential Buildings ◽  
Ventilation System ◽  
Operating Mode ◽  
Cold Season ◽  
Air Permeability ◽  
Normal Operation ◽  
Scale Experiment ◽  
Comparison Of The Results ◽  
Air Exchange

Insufficient air exchange of apartments in gasified apartment residential buildings, as well as an apartment’s air balance when using mechanical ventilation can cause the formation and accumulation of carbon monoxide. This work is aimed at studying the air exchange of apartments when installing kitchen hoods in apartment buildings, as well as insufficient air permeability of windows in PVC (Polyvinyl chloride) bindings during the cold season. Analytical calculations and a full-scale experiment are carried out in two apartments with and without kitchen hood. The calculated air exchanges, actual air exchanges are determined: in normal operation by tenants and in conditionally maximum operating mode with open windows. The comparison of the results of analytical calculations with experimental data shows insufficient air permeability of PVC windows to maintain the necessary air exchange of natural ventilation. It becomes obvious that there are two ways to increase air exchange: regulated - opening vents and non-normative - installation of mechanical hoods. At the same time, the use of mechanical hoods can disrupt the operation of the natural ventilation system.

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