WorldWideScience

Sample records for greenhouse natural ventilation

  1. Sonic anemometry to measure natural ventilation in greenhouses.

    Science.gov (United States)

    López, Alejandro; Valera, Diego Luis; Molina-Aiz, Francisco

    2011-01-01

    The present work has developed a methodology for studying natural ventilation in Mediterranean greenhouses by means of sonic anemometry. In addition, specific calculation programmes have been designed to enable processing and analysis of the data recorded during the experiments. Sonic anemometry allows us to study the direction of the airflow at all the greenhouse vents. Knowing through which vents the air enters and leaves the greenhouse enables us to establish the airflow pattern of the greenhouse under natural ventilation conditions. In the greenhouse analysed in this work for Poniente wind (from the southwest), a roof vent designed to open towards the North (leeward) could allow a positive interaction between the wind and stack effects, improving the ventilation capacity of the greenhouse. The cooling effect produced by the mass of turbulent air oscillating between inside and outside the greenhouse at the side vents was limited to 2% (for high wind speed, u(o) ≥ 4 m s(-1)) reaching 36.3% when wind speed was lower (u(o) = 2 m s(-1)).

  2. Heat Transfer and Fluid Flow in Naturally Ventilated Greenhouses

    Directory of Open Access Journals (Sweden)

    M. Elashmawy

    2017-08-01

    Full Text Available In this paper, heat transfer and fluid flow in naturally ventilated greenhouses are studied numerically for tow configuration according to the number and positions of the opening. The equations governing the phenomenon are developed using the stream function-vorticity formalism and solved using the finite volume method. The aim of the study is to investigate how buoyancy forces influence airflow and temperature patterns inside the greenhouse. Rayleigh number is the main parameter which changes from 103 to 106 and Prandtl number is fixed at Pr=0.71. Results are reported in terms of stream function, isotherms and average Nusselt number. It is found that the flow structure is sensitive to the value of Rayleigh number and the number of openings. Also, that using asymmetric opening positions improve the natural ventilation and facilitate the occurrence of buoyancy induced upward cross-airflow inside the greenhouse.

  3. Natural ventilation of large multi-span greenhouses

    NARCIS (Netherlands)

    Jong, de T.

    1990-01-01

    In this thesis the ventilation of large multi-span greenhouses caused by wind and temperature effects is studied. Quantification of the ventilation is important to improve the control of the greenhouse climate.

    Knowledge of the flow characteristics of the one-side-mounted windows of

  4. Effectiveness of horizontal air flow fans supporting natural ventilation in a Mediterranean multi-span greenhouse

    OpenAIRE

    López, Alejandro; Valera, Diego Luis; Molina-Aiz, Francisco Domingo; Peña, Araceli

    2013-01-01

    Natural ventilation is the most important method of climate control in Mediterranean greenhouses. In this study, the microclimate and air flow inside a Mediterranean greenhouse were evaluated by means of sonic anemometry. Experiments were carried out in conditions of moderate wind (≈ 4.0 m s-1), and at low wind speed (≈ 1.8 m s-1) the natural ventilation of the greenhouse was supplemented by two horizontal air flow fans. The greenhouse is equipped with a single roof vent opening t...

  5. Effectiveness of horizontal air flow fans supporting natural ventilation in a Mediterranean multi-span greenhouse

    Directory of Open Access Journals (Sweden)

    Alejandro López

    2013-08-01

    Full Text Available Natural ventilation is the most important method of climate control in Mediterranean greenhouses. In this study, the microclimate and air flow inside a Mediterranean greenhouse were evaluated by means of sonic anemometry. Experiments were carried out in conditions of moderate wind (≈ 4.0 m s-1, and at low wind speed (≈ 1.8 m s-1 the natural ventilation of the greenhouse was supplemented by two horizontal air flow fans. The greenhouse is equipped with a single roof vent opening to the windward side and two side vents, the windward one being blocked by another greenhouse close to it, while the leeward one is free of obstacles. When no fans are used, air enters through the roof vent and exits through both side vents, thus flowing contrary to the thermal effect which causes hot air to rise and impairing the natural ventilation of the greenhouse. Using fans inside the greenhouse helps the air to circulate and mix, giving rise to a more homogeneous inside temperature and increasing the average value of normalized air velocity by 365 %. These fans also increase the average values of kinetic turbulence energy inside the greenhouse by 550 % compared to conditions of natural ventilation. As the fans are placed 4 m away from the side vents, their effect on the entrance of outside air is insufficient and they do not help to reduce the inside temperature on hot days with little wind. It is therefore recommended to place the fans closer to the side vents to allow an additional increase of the air exchange rate of greenhouses.

  6. A Particle Swarm Optimization of Natural Ventilation Parameters in a Greenhouse with Continuous Roof Vents

    Directory of Open Access Journals (Sweden)

    Abdelhafid HASNI

    2009-03-01

    Full Text Available Although natural ventilation plays an important role in the affecting greenhouse climate, as defined by temperature, humidity and CO2 concentration, particularly in Mediterranean countries, little information and data are presently available on full-scale greenhouse ventilation mechanisms. In this paper, we present a new method for selecting the parameters based on a particle swarm optimization (PSO algorithm which optimize the choice of parameters by minimizing a cost function. The simulator was based on a published model with some minor modifications as we were interested in the parameter of ventilation. The function is defined by a reduced model that could be used to simulate and predict the greenhouse environment, as well as the tuning methods to compute their parameters. This study focuses on the dynamic behavior of the inside air temperature and humidity during ventilation. Our approach is validated by comparison with some experimental results. Various experimental techniques were used to make full-scale measurements of the air exchange rate in a 400 m2 plastic greenhouse. The model which we propose based on natural ventilation parameters optimized by a particle swarm optimization was compared with the measurements results.

  7. Simulation of thermal environment in a three-layer vinyl greenhouse by natural ventilation control

    Science.gov (United States)

    Jin, Tea-Hwan; Shin, Ki-Yeol; Yoon, Si-Won; Im, Yong-Hoon; Chang, Ki-Chang

    2017-11-01

    A high energy, efficient, harmonious, ecological greenhouse has been highlighted by advanced future agricultural technology recently. This greenhouse is essential for expanding the production cycle toward growth conditions through combined thermal environmental control. However, it has a negative effect on farming income via huge energy supply expenses. Because not only production income, but operating costs related to thermal load for thermal environment control is important in farming income, it needs studies such as a harmonious ecological greenhouse using natural ventilation control. This study is simulated for energy consumption and thermal environmental conditions in a three-layered greenhouse by natural ventilation using window opening. A virtual 3D model of a three-layered greenhouse was designed based on the real one in the Gangneung area. This 3D model was used to calculate a thermal environment state such as indoor temperature, relative humidity, and thermal load in the case of a window opening rate from 0 to 100%. There was also a heat exchange operated for heating or cooling controlled by various setting temperatures. The results show that the cooling load can be reduced by natural ventilation control in the summer season, and the heat exchange capacity for heating can also be simulated for growth conditions in the winter season.

  8. Simulation of thermal environment in a three-layer vinyl greenhouse by natural ventilation control

    Directory of Open Access Journals (Sweden)

    Jin Tea-Hwan

    2017-01-01

    Full Text Available A high energy, efficient, harmonious, ecological greenhouse has been highlighted by advanced future agricultural technology recently. This greenhouse is essential for expanding the production cycle toward growth conditions through combined thermal environmental control. However, it has a negative effect on farming income via huge energy supply expenses. Because not only production income, but operating costs related to thermal load for thermal environment control is important in farming income, it needs studies such as a harmonious ecological greenhouse using natural ventilation control. This study is simulated for energy consumption and thermal environmental conditions in a three-layered greenhouse by natural ventilation using window opening. A virtual 3D model of a three-layered greenhouse was designed based on the real one in the Gangneung area. This 3D model was used to calculate a thermal environment state such as indoor temperature, relative humidity, and thermal load in the case of a window opening rate from 0 to 100%. There was also a heat exchange operated for heating or cooling controlled by various setting temperatures. The results show that the cooling load can be reduced by natural ventilation control in the summer season, and the heat exchange capacity for heating can also be simulated for growth conditions in the winter season.

  9. Identification of Natural Ventilation Parameters in a Greenhouse with Continuous Roof Vents, Using a PSO and GAs

    Directory of Open Access Journals (Sweden)

    Abdelhafid HASNI

    2010-08-01

    Full Text Available Although natural ventilation plays an important role in the affecting greenhouse climate, as defined by temperature, humidity and CO2 concentration, particularly in Mediterranean countries, little information and data are presently available on full-scale greenhouse ventilation mechanisms. In this paper, we present a new method for selecting the parameters based on a particle swarm optimization (PSO algorithm and a genetic algorithm (GA which optimize the choice of parameters by minimizing a cost function. The simulator was based on a published model with some minor modifications as we were interested in the parameter of ventilation. The function is defined by a reduced model that could be used to simulate and predict the greenhouse environment, as well as the tuning methods to compute their parameters. This study focuses on the dynamic behavior of the inside air temperature and humidity during ventilation. Our approach is validated by comparison with some experimental results. Various experimental techniques were used to make full-scale measurements of the air exchange rate in a 400 m2 plastic greenhouse. The model which we propose based on natural ventilation parameters optimized by a particle swarm optimization was compared with the measurements results. Furthermore, the PSO and the GA are used to identify the natural ventilation parameters in a greenhouse. In all cases, identification goal is successfully achieved using the PSO and compared with that obtained using the GA. For the problem at hand, it is found that the PSO outperforms the GA.

  10. Three-dimensional computational fluid dynamics analysis of buoyancy-driven natural ventilation and entropy generation in a prismatic greenhouse

    Directory of Open Access Journals (Sweden)

    Aich Walid

    2018-01-01

    Full Text Available A computational analysis of the natural ventilation process and entropy generation in 3-D prismatic greenhouse was performed using CFD. The aim of the study is to investigate how buoyancy forces influence air-flow and temperature patterns inside the greenhouse having lower level opening in its right heated façade and also upper level opening near the roof top in the opposite cooled façade. The bot-tom and all other walls are assumed to be perfect thermal insulators. Rayleigh number is the main parameter which changes from 103 to 106 and Prandtl number is fixed at Pr = 0.71. Results are reported in terms of particles trajectories, iso-surfaces of temperature, mean Nusselt number, and entropy generation. It has been found that the flow structure is sensitive to the value of Rayleigh number and that heat transfer increases with increasing this parameter. Also, it have been noticed that, using asymmetric opening positions improve the natural ventilation and facilitate the occurrence of buoyancy induced upward cross air-flow (low-level supply and upper-level extraction inside the greenhouse.

  11. On the determination of the overall heat transmission coefficient and soil heat flux for a fog cooled, naturally ventilated greenhouse: Analysis of radiation and convection heat transfer

    International Nuclear Information System (INIS)

    Abdel-Ghany, Ahmed M.; Kozai, Toyoki

    2006-01-01

    A physical model for analyzing the radiative and convective heat transfer in a fog cooled, naturally ventilated greenhouse was developed for estimating the overall heat transmission coefficient based on the conduction, convection and thermal radiation heat transfer coefficients and for predicting the soil heat flux. The contribution of the water vapor of the inside air to the emission and absorption of thermal radiation was determined. Measurements of the outside and inside greenhouse environments to be used in the analysis were conducted around solar noon (12:19-13:00) on a hot sunny day to provide the maximum solar radiation transmission into the greenhouse. The net solar radiation flux measured at the greenhouse floor showed a reasonable agreement with the predicted value. The net fluxes were estimated around noon. The average net radiation (solar and thermal) at the soil surface was 220.0 W m -2 , the average soil heat flux was 155.0 W m -2 and the average contribution of the water vapor of the inside air to the thermal radiation was 22.0 W m -2 . The average overall heat transmission coefficient was 4.0 W m -2 C -1 and was in the range between 3.0 W m -2 C -1 and 6.0 W m -2 C -1 under the different hot summer conditions between the inside and outside of the naturally ventilated, fog cooled greenhouse

  12. Natural Ventilation in Atria

    DEFF Research Database (Denmark)

    Svidt, Kjeld; Heiselberg, Per; Hendriksen, Ole Juhl

    This case study comprises a monitoring programme as well as a Computational Fluid Dynamics (CFD) analysis of a natural ventilated atrium. The purpose has been to analyse the performance of a typical natural ventilation system in Denmark under both summer and winter conditions.......This case study comprises a monitoring programme as well as a Computational Fluid Dynamics (CFD) analysis of a natural ventilated atrium. The purpose has been to analyse the performance of a typical natural ventilation system in Denmark under both summer and winter conditions....

  13. Diurnal and seasonal variations of greenhouse gas emissions from a naturally ventilated dairy barn in a cold region

    Science.gov (United States)

    Huang, Dandan; Guo, Huiqing

    2018-01-01

    Carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions were quantified for a naturally ventilated free-stall dairy barn in the Canadian Prairies climate through continuous measurements for a year from February 2015 to January 2016, with ventilation rate estimated by a CO2 mass balance method. The results were categorized into seasonal emission profiles with monthly data measured on a typical day, and diurnal profiles in cold (January), warm (July), and mild seasons (October) of all three gases. Seasonal CO2, CH4, and N2O concentrations greatly fluctuated within ranges of 593-2433 ppm, 15-152 ppm, and 0.32-0.40 ppm, respectively, with obviously higher concentrations in the cold season. Emission factors of the three gases were summarized: seasonal N2O emission varied between 0.5 and 10 μg s-1 AU-1 with lower emission in the cold season, while seasonal CO2 and CH4 emissions were within narrow ranges of 112-119 mg s-1 AU-1 and 2.5-3.5 mg s-1 AU-1. The result suggested a lower enteric CH4 emission for dairy cows than that estimated by Environment Canada (2014). Significant diurnal effects (P 0.05), but obvious diurnal variations in all seasons. In comparison with previous studies, it was found that the dairy barn in a cold region climate with smaller vent openings had relatively higher indoor CO2 and CH4 concentrations, but comparable CO2 and CH4 emissions to most previous studies. Besides, ventilation rate, temperature, and relative humidity all significantly affected the three gas concentrations with the outdoor temperature being the most relevant factor (P < 0.01); however, they showed less or no statistical relations to emissions.

  14. Harnessing natural ventilation benefits.

    Science.gov (United States)

    O'Leary, John

    2013-04-01

    Making sure that a healthcare establishment has a good supply of clean fresh air is an important factor in keeping patients, staff, and visitors, free from the negative effects of CO2 and other contaminants. John O'Leary of Trend Controls, a major international supplier of building energy management solutions (BEMS), examines the growing use of natural ventilation, and the health, energy-saving, and financial benefits, that it offers.

  15. Natural ventilation for free stall dairy barns

    OpenAIRE

    Gay, Susan Wood

    2009-01-01

    Natural ventilation is a result of a combination good construction, correct temperature, humidity control, air exchange. This publication discusses how to achieve natural ventilation in your structure.

  16. Monitoring and energetic performance of two similar semi-closed greenhouse ventilation systems

    International Nuclear Information System (INIS)

    Coomans, Mathias; Allaerts, Koen; Wittemans, Lieve; Pinxteren, Dave

    2013-01-01

    Highlights: • Measurements on two semi-closed greenhouses and two traditional open greenhouses. • Mechanical and natural ventilation for dehumidification and cooling. • Analyses and comparison of installation controls, indoor climate and energy flows. • Examination of air-to-air heat recuperation efficiency in ventilation unit. • Using the semi-closed systems amounted to energy savings of 13% and 28%. - Abstract: Horticulture is an energy intensive industry when dealing with cold climates such as Western Europe. High energy prices and on-going pressure from international competition are raising demand for energy efficient solutions. In search of reducing greenhouse energy consumption, this study investigates semi-closed systems combining controlled mechanical and natural ventilation with thermal screens. Ventilated greenhouse systems (semi-closed) have been implemented in the greenhouse compartments of two Belgian horticulture research facilities: the Research Station for Vegetable Production Sint-Katelijne-Waver (PSKW) and the Research Center Hoogstraten (PCH). Additionally, two reference compartments were included for comparison of the results. The greenhouses were part of a long-term monitoring campaign in which detailed measurements with a high time resolution were gathered by a central monitoring system. A large amount of data was processed and analysed, including outdoor and indoor climatic parameters, system controls and installation measurements. The ventilated greenhouses obtained energy savings of 13% and 28% for PSKW and PCH respectively, without substantial impact on crop production or indoor climate conditions when compared to the reference compartments. A considerable amount of heat was recovered by the heat recuperation stage in the ventilation unit of PCH, accounting for 12% of the total heat demand. In general, it was demonstrated that the greenhouse heat demand can be reduced significantly by controlled dehumidification with mechanical

  17. Design Principles for Natural and Hybrid Ventilation

    DEFF Research Database (Denmark)

    Heiselberg, Per

    For many years mechanical and natural ventilation systems have developed separately. Naturally, the next step in this development is the development of ventilation concepts that utilize and combine the best features from each system to create a new type of ventilation system- Hybrid Ventilation. ....... The hybrid ventilation concepts, design challenges and principles are discussed and illustrated by four building examples.......For many years mechanical and natural ventilation systems have developed separately. Naturally, the next step in this development is the development of ventilation concepts that utilize and combine the best features from each system to create a new type of ventilation system- Hybrid Ventilation...

  18. Wind Extraction for Natural Ventilation

    Science.gov (United States)

    Fagundes, Tadeu; Yaghoobian, Neda; Kumar, Rajan; Ordonez, Juan

    2017-11-01

    Due to the depletion of energy resources and the environmental impact of pollution and unsustainable energy resources, energy consumption has become one of the main concerns in our rapidly growing world. Natural ventilation, a traditional method to remove anthropogenic and solar heat gains, proved to be a cost-effective, alternative method to mechanical ventilation. However, while natural ventilation is simple in theory, its detailed design can be a challenge, particularly for wind-driven ventilation, which its performance highly involves the buildings' form, surrounding topography, turbulent flow characteristics, and climate. One of the main challenges with wind-driven natural ventilation schemes is due to the turbulent and unpredictable nature of the wind around the building that impose complex pressure loads on the structure. In practice, these challenges have resulted in founding the natural ventilation mainly on buoyancy (rather than the wind), as the primary force. This study is the initial step for investigating the physical principals of wind extraction over building walls and investigating strategies to reduce the dependence of the wind extraction on the incoming flow characteristics and the target building form.

  19. Design Principles for Natural and Hybrid Ventilation

    OpenAIRE

    Heiselberg, Per

    2000-01-01

    For many years mechanical and natural ventilation systems have developed separately. Naturally, the next step in this development is the development of ventilation concepts that utilize and combine the best features from each system to create a new type of ventilation system- Hybrid Ventilation. The hybrid ventilation concepts, design challenges and principles are discussed and illustrated by four building examples.

  20. Optimization of ventilation and its effect on the microclimate of a colombian multispan greenhouse

    Directory of Open Access Journals (Sweden)

    Edwin Andrés Villagrán

    2012-08-01

    Full Text Available In Colombia, greenhouse design optimization has not been a relevant topic and, as a consequence, the ventilation systems of current structures are not optimal, generating inadequate microclimates for the development of horticultural species. At the production level, management of the greenhouse climate is deficient, and this factor is not taken into account as a function of characteristics dependent on greenhouse design that cannot be modified during its lifespan. The aim of the present work was to study the efficiency of modifications applied to the ventilation system of a commercial greenhouse available on the Colombian market. This was accomplished by using numerical simulations through the application of the computational fluid dynamics method. Based on the commercial greenhouse design, two modified models were designed by applying structural modifications and changing the orientation of the fixed open ridges. Simulations with the three greenhouse models were carried out in order to maximize the air renovation rates and improve air movement within the entire greenhouse, striving for the highest degree of climate homogenization. The best greenhouse design was the one with the highest air renovation index, high enough to ensure adequate control of temperature and humidity extremes through natural ventilation. Additionally, this design generated the most homogenous microclimate within the cultivation zone

  1. Implementation of natural ventilation in pig houses

    NARCIS (Netherlands)

    Klooster, van 't C.E.

    1994-01-01

    A description of experimental work and discussion on implementation of natural ventilation in pig houses is given. A literature review describes the state of the art, animal growth data are given. It includes characterization of ventilation openings, a technique to estimate the ventilation

  2. Modelling of Natural and Hybrid Ventilation

    OpenAIRE

    Heiselberg, Per

    2006-01-01

    The effectiveness of natural ventilation, i.e. its ability to ensure indoor air quality and passive cooling in a building, depends greatly on the design process. Mechanical ventilation systems can be designed separately from the design of the building in which they are installed. They can also be installed in existing buildings after a few modifications. In contrast, ventilation systems using only natural forces such as wind and thermal buoyancy need to be designed together with the building,...

  3. Short-term airing by natural ventilation

    DEFF Research Database (Denmark)

    Perino, Marco; Heiselberg, Per

    2009-01-01

    The need to improve the energy efficiency of buildings requires new and more efficient ventilation systems. It has been demonstrated that innovative operating concepts that make use of natural ventilation seem to be more appreciated by occupants. This kind of system frequently integrates traditio......The need to improve the energy efficiency of buildings requires new and more efficient ventilation systems. It has been demonstrated that innovative operating concepts that make use of natural ventilation seem to be more appreciated by occupants. This kind of system frequently integrates...... traditional mechanical ventilation components with natural ventilation devices, such as motorized windows and louvers. Among the various ventilation strategies that are currently available, buoyancy driven single-sided natural ventilation has proved to be very effective and can provide high air change rates...... that was aimed at developing and validating numerical models for the analysis of buoyancy driven single-sided natural ventilation systems. Once validated, these models can be used to optimize control strategies in order to achieve satisfactory indoor comfort conditions and IAQ....

  4. The greenhouse advantage of natural gas appliances

    International Nuclear Information System (INIS)

    Coombe, N.

    2000-01-01

    The life cycle report prepared recently by Energetics for the AGA, Assessment of Greenhouse Gas Emissions from Natural Gas, demonstrates clearly the greenhouse advantage natural gas has over coal in generating electricity. This study also goes one step further in applying this life cycle approach to the use of space and water heating within the home. The study shows the significant green-house advantage that natural gas appliances have over electric appliances. Findings from other studies also support this claim. The natural gas suppliers are encouraged to take advantage of the marketing opportunity that these studies provide, offering the householders the fuel that will significantly reduce their contribution to greenhouse emission

  5. Mechanisms of natural ventilation in livestock buildings

    DEFF Research Database (Denmark)

    Rong, Li; Bjerg, Bjarne; Batzanas, Thomas

    2016-01-01

    Studies on the mechanisms of natural ventilation in livestock buildings are reviewed and influences on discharge and pressure coefficients are discussed. Compared to studies conducted on buildings for human occupation and industrial buildings which focus on thermal comfort, ventilation systems......, indoor air quality, building physics and energy etc., our understanding of the mechanisms involved in natural ventilation of livestock buildings are still limited to the application of the orifice equation. It has been observed that the assumptions made for application of the orifice equation...... are not valid for wind-induced cross ventilation through large openings. This review identifies that the power balance model, the concept of stream tube and the local dynamic similarity model has helped in the fundamental understanding of wind-induced natural ventilation in buildings for human occupation...

  6. Short Term Airing by Natural Ventilation

    DEFF Research Database (Denmark)

    Heiselberg, Per; Perino, M.

    2010-01-01

    The need to improve the energy efficiency of buildings requires new and more efficient ventilation systems. It has been demonstrated that innovative operating concepts that make use of natural ventilation seem to be more appreciated by occupants. Among the available ventilation strategies...... that are currently available, buoyancy driven, single-sided natural ventilation has proved to be very effective and can provide high air change rates for temperature and Indoor Air Quality (IAQ) control. However, to promote a wider distribution of these systems an improvement in the knowledge of their working...... airflow rate, ventilation efficiency, thermal comfort and dynamic temperature conditions. A suitable laboratory test rig was developed to perform extensive experimental analyses of the phenomenon under controlled and repeatable conditions. The results showed that short-term window airing is very effective...

  7. Potential of Natural Ventilation in Shopping Centres

    DEFF Research Database (Denmark)

    Diederichsen, Alice; Friis, Kristina; Brohus, Henrik

    2008-01-01

    The indoor environmental quality (IEQ) is a fundamental requirement for a well performing shopping centre. This paper contains a pilot study of the potential of using hybrid ventilation (a combination of automatically controlled natural and mechanical ventilation - respectively NV and MV) in shop......The indoor environmental quality (IEQ) is a fundamental requirement for a well performing shopping centre. This paper contains a pilot study of the potential of using hybrid ventilation (a combination of automatically controlled natural and mechanical ventilation - respectively NV and MV......) in shopping centres with focus on both the achieved IEQ and energy consumptions for air movement. By thermal building simulations it is found that there exists an interesting potential for hybrid ventilation of shopping centres, which can lead to great savings in the electrical energy consumptions...

  8. The fluid mechanics of natural ventilation

    Science.gov (United States)

    Linden, Paul

    1999-11-01

    Natural ventilation of buildings is the flow generated by temperature differences and by the wind. Modern buildings have extreme designs with large, tall open plan spaces and large cooling requirements. Natural ventilation offers a means of cooling these buildings and providing good indoor air quality. The essential feature of ventilation is an exchange between an interior space and the external ambient. Recent work shows that in many circumstances temperature variations play a controlling feature on the ventilation since the directional buoyancy force has a large influence on the flow patterns within the space and on the nature of the exchange with the outside. Two forms of buoyancy-driven ventilation are discussed: mixing ventilation in which the interior is at approximately uniform temperature and displacement ventilation where there is strong internal stratification. The dynamics of these flows are considered and the effects of wind on them are examined both experimentally and theoretically. The aim behind this work is to give designers rules and intuition on how air moves within a building and the research shows a fascinating branch of fluid mechanics.

  9. Design of Natural and Hybrid Ventilation

    DEFF Research Database (Denmark)

    Heiselberg, Per

    The effectiveness of natural ventilation, i.e. its ability to ensure indoor air quality and passive cooling in a building, depends greatly on the design process. Mechanical ventilation systems can be designed separately from the design of the building in which they are installed. They can also...... be installed in existing buildings after a few modifications. In contrast, ventilation systems using only natural forces such as wind and thermal buoyancy need to be designed together with the building, since the building itself and its components are the elements that can reduce or increase air movement...... as well as influence the air content (dust, pollution etc.). Architects and engineers need to acquire qualitative and quantitative information about the interactions between building characteristics and natural ventilation in order to design buildings and systems consistent with a passive low...

  10. Modelling of Natural and Hybrid Ventilation

    DEFF Research Database (Denmark)

    Heiselberg, Per

    The effectiveness of natural ventilation, i.e. its ability to ensure indoor air quality and passive cooling in a building, depends greatly on the design process. Mechanical ventilation systems can be designed separately from the design of the building in which they are installed. They can also...... be installed in existing buildings after a few modifications. In contrast, ventilation systems using only natural forces such as wind and thermal buoyancy need to be designed together with the building, since the building itself and its components are the elements that can reduce or increase air movement...... as well as influence the air content (dust, pollution etc.). Architects and engineers need to acquire qualitative and quantitative information about the interactions between building characteristics and natural ventilation in order to design buildings and systems consistent with a passive low...

  11. Solar chimney for natural ventilation: A review

    Science.gov (United States)

    Dhrubo, Abir Ahsan; Alam, Chowdhury Sadid; Rahman, Md. Mustafizur; Islam, A. K. M. Sadrul

    2017-06-01

    In the 21st century the talk of the time has been proper use of renewable energy sources due to the continuous depletion of non-renewable energy sources and global warming as a result of combustion of fossil fuels. The energy situation in the 3rd world countries is even worse. The continuous industrial development in the 1st world countries is hugely responsible for global temperature increase and greenhouse gas (GHG) emissions which badly affect the countries like Bangladesh. As of April 2016, the electricity generation capacity of Bangladesh was 12,399 MW to which only 60% of the total population have access to. The shortage of electricity during the summer season makes life very difficult. Cooling of buildings requires a large quantity of energy in the summer. An alternative cooling system can reduce the dependency on electricity. This paper specially deals with a passive cooling system that reduces pressure on the electricity supply and focuses on renewable energy sources. Here a different process engineering has been discussed which incorporates Earth-to-Air Heat Exchangers with solar collector enhanced solar chimney system. In this study natural ventilation of buildings, using solar chimney system is reviewed extensively. Experimentally it has already been observed that sufficient temperature drop takes place 2-3 m within the undisturbed ground, which can work as a heat sink for ambient air if passed through and can lead to attaining comfort zone at a confined location. During peak hours of summer this kind of system may work as a very efficient cooling system and reduces extra load on electricity supply.

  12. Characterizing the chaotic nature of ocean ventilation

    Science.gov (United States)

    MacGilchrist, Graeme A.; Marshall, David P.; Johnson, Helen L.; Lique, Camille; Thomas, Matthew

    2017-09-01

    Ventilation of the upper ocean plays an important role in climate variability on interannual to decadal timescales by influencing the exchange of heat and carbon dioxide between the atmosphere and ocean. The turbulent nature of ocean circulation, manifest in a vigorous mesoscale eddy field, means that pathways of ventilation, once thought to be quasi-laminar, are in fact highly chaotic. We characterize the chaotic nature of ventilation pathways according to a nondimensional "filamentation number," which estimates the reduction in filament width of a ventilated fluid parcel due to mesoscale strain. In the subtropical North Atlantic of an eddy-permitting ocean model, the filamentation number is large everywhere across three upper ocean density surfaces—implying highly chaotic ventilation pathways—and increases with depth. By mapping surface ocean properties onto these density surfaces, we directly resolve the highly filamented structure and confirm that the filamentation number captures its spatial variability. These results have implications for the spreading of atmospherically-derived tracers into the ocean interior.

  13. Achieving Natural and Hybrid Ventilation in Practice

    DEFF Research Database (Denmark)

    Liddament, Martin; Axley, James; Heiselberg, Per

    2006-01-01

    Case studies provide essential evidence about the performance of buildings. They also illustrate the methods by which a technology can be implemented as well as highlighting problems. Various case study buildings (both new and retrofit) that incorporate mixed mode, natural ventilation and low ene...

  14. Boundary conditions for natural supply ventilation

    NARCIS (Netherlands)

    Jansen, D.W.L.; Loomans, M.G.L.C.; Wit, de M.H.; Zeiler, W.; Seppänen, O.; Säteri, J.

    2007-01-01

    The development of an air jet from a controlled natural ventilation grill for different outdoor conditions is studied. Extensive laboratory measurements are taken in different situations, while the air flow rate through the grill is kept constant. The grill setting and supply temperature are varied.

  15. Buoyancy Driven Natural Ventilation through Horizontal Openings

    DEFF Research Database (Denmark)

    Heiselberg, Per

    2009-01-01

    An experimental study of the phenomenon of buoyancy driven natural ventilation through single-sided horizontal openings was performed in a full-scale laboratory test rig. The measurements were made for opening ratios L/D ranging from 0.027 to 4.455, where L and D are the length of the opening...... and the diameter of the opening, respectively. The basic nature of airflow through single-sided openings, including airflow rate, air velocity, temperature difference between the rooms and the dimensions of the horizontal openings, were measured. A bi-directional airflow rate was measured using the constant...... quite well with the Epstein's formula ratio are presented. In some cases the measured airflow rates fit quite well with the Epstein's formula but in other cases the measured data show clear deviations from the Epstein's formula. Thus, revised formulas for natural ventilation are proposed....

  16. Buoyancy Driven Natural Ventilation through Horizontal Openings

    DEFF Research Database (Denmark)

    Heiselberg, Per; Li, Zhigang

    2009-01-01

    An experimental study of the phenomenon of buoyancy driven natural ventilation through single-sided horizontal openings was performed in a full-scale laboratory test rig. The measurements were made for opening ratios L/D ranging from 0.027 to 4.455, where L and D are the length of the opening...... and the diameter of the opening, respectively. The basic nature of airflow through single-sided openings, including airflow rate, air velocity, temperature difference between the rooms and the dimensions of the horizontal openings, were measured. A bi-directional airflow rate was measured using the constant...... quite well with the Epstein's formula but in other cases the measured data show clear deviations from the Epstein's formula. Thus, revised formulas for natural ventilation are proposed....

  17. Design guidelines for natural ventilation systems in tertiary sector buildings

    OpenAIRE

    Van Moeseke, Geoffrey; Bruyère, Isabelle; De Herde, André; CISBAT 2005: Renewables in a changing climate

    2005-01-01

    Parameters determining efficiency of natural ventilation systems are numerous. The most important are architecture and system design. This article get onto both but focuses on system design. Through dynamic simulations it shows that natural ventilation management has a large impact on energy saving but most of all on thermal comfort. Natural ventilation techniques are also weighted against hybrid solutions and high efficiency mechanical cooling solutions. Natural ventilation techniques show t...

  18. 33 CFR 183.630 - Standards for natural ventilation.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Standards for natural ventilation... (CONTINUED) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Ventilation § 183.630 Standards for natural ventilation. (a) For the purpose of § 183.620, “natural ventilation” means an airflow in a compartment in a...

  19. Buoyancy Driven Natural Ventilation through Horizontal Openings

    OpenAIRE

    Heiselberg, Per

    2009-01-01

    An experimental study of the phenomenon of buoyancy driven natural ventilation through single-sided horizontal openings was performed in a full-scale laboratory test rig. The measurements were made for opening ratios L/D ranging from 0.027 to 4.455, where L and D are the length of the opening and the diameter of the opening, respectively. The basic nature of airflow through single-sided openings, including airflow rate, air velocity, temperature difference between the rooms and the dimensions...

  20. Natural ventilation for reducing airborne infection in hospitals

    Energy Technology Data Exchange (ETDEWEB)

    Qian, Hua [School of Energy and Environment, Southeast University, Nanjing (China); Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong (China); Li, Yuguo; Ching, W.H.; Sun, H.Q. [Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong (China); Seto, W.H.; Ching, Patricia [Department of Microbiology, Queen Mary Hospital, Hong Kong (China)

    2010-03-15

    High ventilation rate is shown to be effective for reducing cross-infection risk of airborne diseases in hospitals and isolation rooms. Natural ventilation can deliver much higher ventilation rate than mechanical ventilation in an energy-efficient manner. This paper reports a field measurement of naturally ventilated hospital wards in Hong Kong and presents a possibility of using natural ventilation for infection control in hospital wards. Our measurements showed that natural ventilation could achieve high ventilation rates especially when both the windows and the doors were open in a ward. The highest ventilation rate recorded in our study was 69.0 ACH. The airflow pattern and the airflow direction were found to be unstable in some measurements with large openings. Mechanical fans were installed in a ward window to create a negative pressure difference. Measurements showed that the negative pressure difference was negligible with large openings but the overall airflow was controlled in the expected direction. When all the openings were closed and the exhaust fans were turned on, a reasonable negative pressure was created although the air temperature was uncontrolled. The high ventilation rate provided by natural ventilation can reduce cross-infection of airborne diseases, and thus it is recommended for consideration of use in appropriate hospital wards for infection control. Our results also demonstrated a possibility of converting an existing ward using natural ventilation to a temporary isolation room through installing mechanical exhaust fans. (author)

  1. Computational fluid dynamics modelling of displacement natural ventilation.

    OpenAIRE

    Ji, Yingchun

    2005-01-01

    Natural ventilation is widely recognised as contributing towards low-energy building design. The requirement to reduce energy usage in new buildings has rejuvenated interest in natural ventilation. This thesis deals with computer modelling of natural displacement ventilation driven either by buoyancy or buoyancy combined with wind forces. Two benchmarks have been developed using computational fluid dynamics (CFD) in order to evaluate the accuracy with which CFD is able to mo...

  2. NATURAL BASEMENT VENTILATION AS A RADON MITIGATION TECHNIQUE

    Science.gov (United States)

    The report documents a study of natural basement ventilation in two research houses during both the summer cooling season and the winter heating season. NOTE: Natural basement ventilation has always been recommended as a way to reduce radon levels in houses. However, its efficacy...

  3. Natural ventilation for the prevention of airborne contagion.

    Science.gov (United States)

    Escombe, A Roderick; Oeser, Clarissa C; Gilman, Robert H; Navincopa, Marcos; Ticona, Eduardo; Pan, William; Martínez, Carlos; Chacaltana, Jesus; Rodríguez, Richard; Moore, David A J; Friedland, Jon S; Evans, Carlton A

    2007-02-01

    Institutional transmission of airborne infections such as tuberculosis (TB) is an important public health problem, especially in resource-limited settings where protective measures such as negative-pressure isolation rooms are difficult to implement. Natural ventilation may offer a low-cost alternative. Our objective was to investigate the rates, determinants, and effects of natural ventilation in health care settings. The study was carried out in eight hospitals in Lima, Peru; five were hospitals of "old-fashioned" design built pre-1950, and three of "modern" design, built 1970-1990. In these hospitals 70 naturally ventilated clinical rooms where infectious patients are likely to be encountered were studied. These included respiratory isolation rooms, TB wards, respiratory wards, general medical wards, outpatient consulting rooms, waiting rooms, and emergency departments. These rooms were compared with 12 mechanically ventilated negative-pressure respiratory isolation rooms built post-2000. Ventilation was measured using a carbon dioxide tracer gas technique in 368 experiments. Architectural and environmental variables were measured. For each experiment, infection risk was estimated for TB exposure using the Wells-Riley model of airborne infection. We found that opening windows and doors provided median ventilation of 28 air changes/hour (ACH), more than double that of mechanically ventilated negative-pressure rooms ventilated at the 12 ACH recommended for high-risk areas, and 18 times that with windows and doors closed (p ventilation than modern naturally ventilated rooms (40 versus 17 ACH; p natural ventilation exceeded mechanical (p ventilated rooms 39% of susceptible individuals would become infected following 24 h of exposure to untreated TB patients of infectiousness characterised in a well-documented outbreak. This infection rate compared with 33% in modern and 11% in pre-1950 naturally ventilated facilities with windows and doors open. Opening windows and

  4. Natural ventilation of buildings: opposing wind and buoyancy

    Science.gov (United States)

    Linden, Paul; Hunt, Gary

    1998-11-01

    The use of natural ventilation in buildings is an attractive way to reduce energy usage thereby reducing costs and CO2 emissions. Generally, it is necessary to remove excess heat from a building and the designer can use the buoyancy forces associated with the above ambient temperatures within the building to drive a flow - 'stack' ventilation. The most efficient mode is displacement ventilation where warm air accumulates near the top of the building and flows out through upper level vents and cooler air flows in at lower levels. Ventilation will also be driven between these lower and upper openings by the wind. We report on laboratory modeling and theory which investigates the effects of an opposing wind on stack ventilation driven by a constant source of heat within a space under displacement ventilation. We show that there is a critical wind speed, expressed in dimensionless terms as a critical Froude number, above which displacement ventilation is replaced by (less efficient) mixing ventilation with reversed flow. Below this critical speed, displacement ventilation, in which the interior has a two-layer stratification, is maintained. The criterion for the change in ventilation mode is derived from general considerations of mixing efficiencies in stratified flows. We conclude that even when wind effects might appear to be dominant, the inhibition of mixing by the stable stratification within the space ensures that stack ventilation can operate over a wide range of apparently adverse conditions.

  5. Reducing the ingress of urban noise through natural ventilation openings.

    Science.gov (United States)

    Oldham, D J; de Salis, M H; Sharples, S

    2004-01-01

    For buildings in busy urban areas affected by high levels of road traffic noise the potential to use natural ventilation can be limited by excessive noise entering through ventilation openings. This paper is concerned with techniques to reduce noise ingress into naturally ventilated buildings while minimizing airflow path resistance. A combined experimental and theoretical approach to the interaction of airflow and sound transmission through ventilators for natural ventilation applications is described. A key element of the investigation has been the development of testing facilities capable of measuring the airflow and sound transmission losses for a range of ventilation noise control strategies. It is demonstrated that a combination of sound reduction mechanisms -- one covering low frequency sound and another covering high frequency sound -- is required to attenuate effectively noise from typical urban sources. A method is proposed for quantifying the acoustic performance of different strategies to enable comparisons and informed decisions to be made leading to the possibility of a design methodology for optimizing the ventilation and acoustic performance of different strategies. The need for employing techniques for combating low frequency sound in tandem with techniques for reducing high frequency sound in reducing the ingress of noise from urban sources such as road traffic to acceptable levels is demonstrated. A technique is proposed for enabling the acoustic and airflow performance of apertures for natural ventilation systems to be designed simultaneously.

  6. Characteristics of rain penetration through a gravity ventilator used for natural ventilation.

    Science.gov (United States)

    Kim, Taehyeung; Lee, Dong Ho; Ahn, Kwangseog; Ha, Hyunchul; Park, Heechang; Piao, Cheng Xu; Li, Xiaoyu; Seo, Jeoungyoon

    2008-01-01

    Gravity ventilators rely simply on air buoyancy to extract air and are widely used to exhaust air contaminants and heat from workplaces using minimal energy. They are designed to maximize the exhaust flow rate, but the rain penetration sometimes causes malfunctioning. In this study, the characteristics of rain penetration through a ventilator were examined as a preliminary study to develop a ventilator with the maximum exhaust capacity while minimizing rain penetration. A model ventilator was built and exposed to artificial rain and wind. The paths, intensities and amounts of penetration through the ventilator were observed and measured in qualitative and quantitative fashions. In the first phase, the pathways and intensities of rain penetration were visually observed. In the second phase, the amounts of rain penetration were quantitatively measured under the different configurations of ventilator components that were installed based on the information obtained in the first-phase experiment. The effects of wind speed, grill direction, rain drainage width, outer wall height, neck height and leaning angle of the outer wall from the vertical position were analyzed. Wind speed significantly affected rain penetration. Under the low crosswind conditions, the rain penetration intensities were under the limit of detection. Under the high crosswind conditions, grill direction and neck height were the most significant factors in reducing rain penetration. The installation of rain drainage was also important in reducing rain penetration. The experimental results suggest that, with proper configurations of its components, a gravity ventilator can be used for natural ventilation without significant rain penetration problems.

  7. Potential of Natural Ventilation in Cold Conditions Countries

    DEFF Research Database (Denmark)

    Oropeza-Perez, Ivan; Østergaard, Poul Alberg

    2014-01-01

    The objective of this article is to investigate the energy performance of natural ventilation as a passive cooling method of buildings within houses located in temperate countries using Denmark as a case study. The method consists in running simulations with a thermal-airflow program of a household...... the simulations are validated with measured data, and by applying a new assessment method presented in this article as the cooling rate due to natural ventilation instead of a constant mechanical ventilation rate in the thermal balance within the dwelling, the energy saving is calculated. Results show...... ventilation rather mechanical one on large-scale scenarios located in temperate conditions. Finally, as a practical implication example, an assessment for Denmark is carried out....

  8. Architectural design of an advanced naturally ventilated building form

    Energy Technology Data Exchange (ETDEWEB)

    Lomas, K.J. [De Montfort University, Leicester (United Kingdom). Institute of Energy and Sustainable Development

    2007-02-15

    Advanced stack-ventilated buildings have the potential to consume much less energy for space conditioning than typical mechanically ventilated or air-conditioned buildings. This paper describes how environmental design considerations in general, and ventilation considerations in particular, shape the architecture of advanced naturally ventilated (ANV) buildings. The attributes of simple and advanced naturally ventilated buildings are described and a taxonomy of ANV buildings presented. Simple equations for use at the preliminary design stage are presented. These produce target structural cross section areas for the key components of ANV systems. The equations have been developed through practice-based research to design three large educational buildings: the Frederick Lanchester Library, Coventry, UK; the School of Slavonic and East European Studies, London, UK; the Harm A. Weber Library, Elgin, near Chicago, USA. These buildings are briefly described and the sizes of the as-built ANV features compared with the target values for use in preliminary design. The three buildings represent successive evolutionary stages: from advanced natural ventilation, to ANV with passive downdraught cooling, and finally ANV with HVAC support. Hopefully the guidance, simple calculation tools and case study examples will give architects and environmental design consultants confidence to embark on the design of ANV buildings. (author)

  9. Characterization of natural ventilation in wastewater collection systems.

    Science.gov (United States)

    Ward, Matthew; Corsi, Richard; Morton, Robert; Knapp, Tom; Apgar, Dirk; Quigley, Chris; Easter, Chris; Witherspoon, Jay; Pramanik, Amit; Parker, Wayne

    2011-03-01

    The purpose of the study was to characterize natural ventilation in full-scale gravity collection system components while measuring other parameters related to ventilation. Experiments were completed at four different locations in the wastewater collection systems of Los Angeles County Sanitation Districts, Los Angeles, California, and the King County Wastewater Treatment District, Seattle, Washington. The subject components were concrete gravity pipes ranging in diameter from 0.8 to 2.4 m (33 to 96 in.). Air velocity was measured in each pipe using a carbon-monoxide pulse tracer method. Air velocity was measured entering or exiting the components at vents using a standpipe and hotwire anemometer arrangement. Ambient wind speed, temperature, and relative humidity; headspace temperature and relative humidity; and wastewater flow and temperature were measured. The field experiments resulted in a large database of measured ventilation and related parameters characterizing ventilation in full-scale gravity sewers. Measured ventilation rates ranged from 23 to 840 L/s. The experimental data was used to evaluate existing ventilation models. Three models that were based upon empirical extrapolation, computational fluid dynamics, and thermodynamics, respectively, were evaluated based on predictive accuracy compared to the measured data. Strengths and weaknesses in each model were found and these observations were used to propose a concept for an improved ventilation model.

  10. Single-Sided Natural Ventilation through a Velux Roof Window

    DEFF Research Database (Denmark)

    Li, Zhigang; Nielsen, Peter Vilhelm; Fransson, J.

    2004-01-01

    This paper investigates the single-sided natural ventilation through a VELUX centre pivot roof window under natural weather conditions. The aim of the investigation is to develop an empirical formulation for air flow rate through a roof window based on CFD and tracer gas decay measurement methods...

  11. Natural Ventilation Driven by Wind and Temperature Difference

    DEFF Research Database (Denmark)

    Larsen, Tine Steen

    Natural ventilation is a commonly used principle when buildings are being ventilated. It can be controlled by openings in the building envelope, which open or close depending on the need of air inside the building. It can also be the simple action of just opening a door or a window to let the fresh...... driving forces are still wind pressure and temperature differences as with cross-ventilation, but here the turbulence in the wind and the pulsating flow near the opening also affect the flow through the opening. From earlier work, some design expressions already exist, but none of these include...... the incidence angle of the wind, which is an important parameter in this type of ventilation. Several wind tunnel experiments are made and from the results of these, a new design expression is made which includes the wind pressure, temperature difference, incidence angle of the wind and the fluctuations...

  12. Ventilation

    DEFF Research Database (Denmark)

    Nielsen, Toke Rammer; Svendsen, Sv Aa Højgaard

    1999-01-01

    The note concerns ventilation in residential buildings. Describes components in ventilation systems, electric energy consumption and different ventilation systems with heat exchanger.......The note concerns ventilation in residential buildings. Describes components in ventilation systems, electric energy consumption and different ventilation systems with heat exchanger....

  13. Investigation of Indoor Climate in a Naturally Ventilated Office Building

    DEFF Research Database (Denmark)

    Larsen, Tine Steen; Kalyanova, Olena; Jensen, Rasmus Lund

    2008-01-01

    A measuring program in a naturally ventilated office building in Copenhagen was carried out to document the indoor climate and ventilation system performance during a year. It included a questionnaire regarding the perceived indoor environmental quality and physical measurements of thermal comfort...... to a combination of poor control of solar shading and a very high local heat load that was above the Danish recommendations for naturally ventilated office buildings. Both measured and perceived indoor air quality in the building was in general very high. The measured air flow rates was relatively high due...... to the need for cooling in the office building, while the level of infiltration was quite low indicating an airtight construction....

  14. Energy Saving Potential by Utilizing Natural Ventilation under Warm Conditions

    DEFF Research Database (Denmark)

    Oropeza-Perez, Ivan; Østergaard, Poul Alberg

    2014-01-01

    The objective of this article is to show the potential of natural ventilation as a passive cooling method within the residential sector of countries which are located in warm conditions using Mexico as a case study. The method is proposed as performing, with a simplified ventilation model, thermal......–airflow simulations of 27 common cases of dwellings (considered as one thermal zone) based on the combination of specific features of the building design, occupancy and climate conditions. The energy saving potential is assessed then by the use of a new assessment method suitable for large-scale scenarios using...... the actual number of air-conditioned dwellings distributed among the 27 cases. Thereby, the energy saving is presented as the difference in the cooling demand of the dwelling during one year without and with natural ventilation, respectively. Results indicate that for hot-dry conditions, buildings with high...

  15. Environmental performance of a naturally ventilated city centre library

    Energy Technology Data Exchange (ETDEWEB)

    Krausse, Birgit; Cook, Malcolm; Lomas, Kevin [Institute of Energy and Sustainable Development, De Montfort University, Queens Building, The Gateway, Leicester LE1 9BH, (United Kingdom)

    2007-07-15

    To tackle climate change it is essential to reduce carbon dioxide emissions. To this end, it is important to reduce the energy demands of non-domestic buildings. Naturally ventilated buildings can have low energy demands but the strategy is difficult to implement in deep plan, urban locations. The Frederick Lanchester Library at Coventry University, UK, incorporates natural ventilation, daylighting and passive cooling strategies. By using lightwells and perimeter stacks to supply and exhaust air, it can be ventilated by natural means despite its deep plan form and sealed facade. This paper describes the building and presents the energy consumption and the internal temperatures and CO{sub 2} levels recorded in 2004/2005. The building's performance is compared to the original design criteria and good practice guidelines. Recommendations for the design of such buildings are made and the likely performance in other UK cities is assessed. It is concluded that the building uses under half the energy of a standard air-conditioned building and yet, in summer, can keep the interior comfortable and up to 5 deg C below ambient. The design would perform equally well in the typical weather conditions experienced at 13 other UK cities, but not in London. It is concluded that deep-plan, naturally ventilated buildings with sealed facades, if well designed, could maintain thermal comfort in all but a very few UK locations, whilst consuming much less energy than even good practice standards. (Author)

  16. Natural ventilation systems to enhance sustainability in buildings: a review towards zero energy buildings in schools

    Science.gov (United States)

    Gil-Baez, Maite; Barrios-Padura, Ángela; Molina-Huelva, Marta; Chacartegui, Ricardo

    2017-11-01

    European regulations set the condition of Zero Energy Buildings for new buildings since 2020, with an intermediate milestone in 2018 for public buildings, in order to control greenhouse gases emissions control and climate change mitigation. Given that main fraction of energy consumption in buildings operation is due to HVAC systems, advances in its design and operation conditions are required. One key element for energy demand control is passive design of buildings. On this purpose, different recent studies and publications analyse natural ventilation systems potential to provide indoor air quality and comfort conditions minimizing electric power consumption. In these passive systems are of special relevance their capacities as passive cooling systems as well as air renovation systems, especially in high-density occupied spaces. With adequate designs, in warm/mild climates natural ventilation systems can be used along the whole year, maintaining indoor air quality and comfort conditions with small support of other heating/cooling systems. In this paper is analysed the state of the art of natural ventilation systems applied to high density occupied spaces with special focus on school buildings. The paper shows the potential and applicability of these systems for energy savings and discusses main criteria for their adequate integration in school building designs.

  17. 76 FR 22825 - Mandatory Reporting of Greenhouse Gases: Petroleum and Natural Gas Systems

    Science.gov (United States)

    2011-04-25

    ... Reporting of Greenhouse Gases: Petroleum and Natural Gas Systems AGENCY: Environmental Protection Agency... Subpart W: Petroleum and Natural Gas Systems of the Greenhouse Gas Reporting Rule. As part of the... greenhouse gas emissions for the petroleum and natural gas systems source category of the greenhouse gas...

  18. Methane emission from naturally ventilated livestock buildings can be determined from gas concentration measurements

    DEFF Research Database (Denmark)

    Bjerg, B; Zhang, Guoqiang; Madsen, J

    2012-01-01

    Determination of emission of contaminant gases as ammonia, methane, or laughing gas from natural ventilated livestock buildings with large opening is a challenge due to the large variations in gas concentration and air velocity in the openings. The close relation between calculated animal heat pr...... to investigate the influence of feed composition on methane emission in a relative large number of operating cattle buildings and consequently it can support a development towards reduced greenhouse gas emission from cattle production.......Determination of emission of contaminant gases as ammonia, methane, or laughing gas from natural ventilated livestock buildings with large opening is a challenge due to the large variations in gas concentration and air velocity in the openings. The close relation between calculated animal heat...... ventilated, 150 milking cow building. The results showed that the methane emission can be determined with much higher precision than ammonia or laughing gas emissions, and, for methane, relatively precise estimations can be based on measure periods as short as 3 h. This result makes it feasible...

  19. Research of CO2 concentration in naturally ventilated lecture room

    Science.gov (United States)

    Laska, Marta; Dudkiewicz, Edyta

    2017-11-01

    Naturally ventilated buildings especially dedicated for educational purposes need to be design to achieve required level of thermal comfort and indoor air quality. It is crucial in terms of both: health and productivity of the room users. Higher requirements of indoor environment are important due to the level of students concentration, their ability to acquire new knowledge and willingness to interact with the lecturer. The article presents the results of experimental study and surveys undertaken in naturally ventilated lecture room. The data is analysed in terms of CO2 concentration and its possible influence on users. Furthermore the outcome of the research is compared with the CO2 concentration models available in the literature.

  20. Thermal Comfort in a Naturally-Ventilated Educational Building

    OpenAIRE

    David Mwale Ogoli

    2012-01-01

    A comprehensive study of thermal comfort in a naturally ventilated education building (88,000 ft2) in a Chicago suburb will be conducted with 120 student subjects in 2007. This paper discusses some recent trends in worldwide thermal comfort studies and presents a proposal of research for this building through a series of questionnaire tables. Two research methods used inthermal comfort studies are field studies and laboratory experiments in climate-chambers. The various elements that constitu...

  1. Assessment of greenhouse gas emissions from natural gas

    International Nuclear Information System (INIS)

    Anon

    2000-01-01

    The study, 'Assesment of greenhouse gas emission from natural gas' by independent consultants Energetics Pty Ltd, shows that natural gas has significantly fewer greenhouses gas emissions than either black or brown cola for the defined life cycle stages. The life cycle emissions from natural gas use by an Australian Major User are approximately 50% less than the emissions from Victorian brown coal and approximately 38% less than the emissions from Australian average black coal. Australian Best Practice gas fired electricity generation is estimated to emit between 514 and 658 kg CO 2 e/MWh. By comparison, Australian Best Practice coal-fired electricity generation is estimated to emit between 907 and 1,246 kg CO 2 e/MWh for black and brown coal respectively. Greenhouse gas emissions from Australian Best Practice gas-fired electricity generation using combined cycle gas turbines (including full fuel cycle emissions) vary from 41% to 46% of the emissions from brown coal-fired electricity generation and 57% to 64% of emissions from black coal-fired electricity generation. Greenhouse gas emissions from direct gas supply water heating range from 1,470 to 2,042 kilograms per annum. This compares with emissions of 1,922 to 2,499 kg for electric heating from gas-fired electricity generation and 3,975 to 5,393 kg for coal-fired electricity generation. The implications for greenhouse policy nationally are also discussed, emphasising the need to review national energy policy, currently tied to 'fuel neutrality' doctrine

  2. Passive Design Strategies to Enhance Natural Ventilation in Buildings "Election of Passive Design Strategies to Achieve Natural Ventilation in Iraqi Urban Environment with Hot Arid Climate"

    Directory of Open Access Journals (Sweden)

    Ghada M.Ismael Abdul Razzaq Kamoona

    2016-06-01

    Full Text Available the natural ventilation in buildings is one of effective strategies for achieving energy efficiency in buildings by employing methods and ways of passive design, as well as its efficiency in providing high ranges of thermal comfort for occupants in buildings and raises their productivity. Because the concept of natural ventilation for many people confined to achieve through the windows and openings only, become necessary to provide this research to demonstrate the various passive design strategies for natural ventilation. Then, research problem: Insufficient knowledge about the importance and mechanism of the application of passive design strategies for natural ventilation in buildings. The research objective is: Analysis of passive design strategies to achieve natural ventilation in buildings, for the purpose of the proper selection of them to Iraqi urban environment. Accordingly, the research included two parts: First, the theoretical part, which dealt with the conceptual framework of natural ventilation and deriving the most important aspects in it, in order to adopted as a base for the practical part of the research. Second: the practical part, which analyzed examples of buildings projects that employed various design strategies for natural ventilation, according to the theoretical framework that has been drawn. The main conclusion is, Necessity to adopt various passive design strategies for natural ventilation in Iraqi urban environment with hot dry climate, as they have a significant impact in reducing the energy consumption for the purposes of ventilation and cooling, as well as for its efficiency in improving air quality in indoor environments of buildings.

  3. Estimating wind frequency limits for natural ventilation at remote sites

    International Nuclear Information System (INIS)

    Su, B.; Aynsley, R.

    2006-01-01

    Detailed wind data are collected at a limited number of sites, usually at airports. When a building is sited remote from the nearest wind data collection site, estimating wind frequency is more complex. The techniques involved come from the discipline of wind engineering. Where there is a relatively flat terrain between the wind data-recording site and the building site, simple computations can be made to account for the wind velocities over intervening terrain roughness. Where significant topographic features such as hills or mountains are present between the wind data-recording site and the building site, then boundary layer wind tunnel studies will be necessary to determine the influence of such features on wind speed and direction. Rough estimates can be calculated using factors used in some wind loading codes. When buildings are to be designed to take advantage of the energy efficiency offered by natural ventilation, it is important to estimate the actual potential for such ventilation. The natural ventilation potential can be estimated in terms of the percentage of time when wind exceeds some minimum value. For buildings near airports this is a relatively simple procedure. Such estimates are important as they also indicate the likely percentage of time when fans or other energy consuming devices will be needed to maintain indoor thermal comfort. This paper identifies the wind engineering techniques that can be used for such estimates and gives examples of such calculations

  4. Thermal Comfort in a Naturally-Ventilated Educational Building

    Directory of Open Access Journals (Sweden)

    David Mwale Ogoli

    2012-11-01

    Full Text Available A comprehensive study of thermal comfort in a naturally ventilated education building (88,000 ft2 in a Chicago suburb will be conducted with 120 student subjects in 2007. This paper discusses some recent trends in worldwide thermal comfort studies and presents a proposal of research for this building through a series of questionnaire tables. Two research methods used inthermal comfort studies are field studies and laboratory experiments in climate-chambers. The various elements that constitute a “comfortable” thermal environment include physical factors (ambient air temperature, mean radiant temperature, air movement and humidity, personal factors(activity and clothing, classifications (gender, age, education, etc. and psychological expectations (knowledge, experience, psychological effect of visual warmth by, say, a fireplace. Comparisons are made using data gathered from Nairobi, Kenya.Keywords: Comfort, temperature, humidity and ventilation

  5. Natural Ventilation with Heat Recovery: A Biomimetic Concept

    Directory of Open Access Journals (Sweden)

    Zulfikar A. Adamu

    2015-05-01

    Full Text Available In temperate countries, heat recovery is often desirable through mechanical ventilation with heat recovery (MVHR. Drawbacks of MVHR include use of electric power and complex ducting, while alternative passive heat recovery systems in the form of roof or chimney-based solutions are limited to low rise buildings. This paper describes a biomimetic concept for natural ventilation with heat recovery (NVHR. The NVHR system mimics the process of water/mineral extraction from urine in the Loop of Henle (part of human kidney. Simulations on a facade-integrated Chamber successfully imitated the geometry and behaviour of the Loop of Henle (LoH. Using a space measuring 12 m2 in area and assuming two heat densities of 18.75 W/m2 (single occupancy or 30 W/m2 (double occupancy, the maximum indoor temperatures achievable are up to 19.3 °C and 22.3 °C respectively. These come with mean relative ventilation rates of 0.92 air changes per hour (ACH or 10.7 L·s−1 and 0.92 ACH (11.55 L·s−1, respectively, for the month of January. With active heating and single occupant, the LoH Chamber consumes between 65.7% and 72.1% of the annual heating energy required by a similar naturally ventilated space without heat recovery. The LoH Chamber could operate as stand-alone indoor cabinet, benefitting refurbishment of buildings and evading constraints of complicated ducting, external aesthetic or building age.

  6. Effect of near-infrared-radiation reflective screen materials on ventilation requirement, crop transpiration and water use efficiency of a greenhouse rose crop

    NARCIS (Netherlands)

    Stanghellini, C.; Jianfeng, D.; Kempkes, F.L.K.

    2011-01-01

    The effect of Near Infrared (NIR)-reflective screen material on ventilation requirement, crop transpiration and water use efficiency of a greenhouse rose crop was investigated in an experiment whereby identical climate was ensured in greenhouse compartments installed with either NIR-reflective or

  7. The Impact of an Extensive Usage of Controlled Natural Ventilation in the Residential Sector on Large-Scale Energy Systems

    DEFF Research Database (Denmark)

    Oropeza-Perez, Ivan

    The energy situation in the world is becoming alarming. The demand of electricity continues to grow whereas the means of production remain limited. In addition, the electricity generation in the world is mostly based on fossil fuels such as coal, oil and natural gas. Only a small share of the total...... to the atmosphere. On the other hand, the efficiency of the end-use energy consumption is also fundamental to decrease the electricity production thus to lower the emission of greenhouse gases. Thereby, the building sector is a very important target because it consumes approximately one quarter of the total annual...... be reflected in the reduction of the electricity production. The objective of the thesis is to show realistic benefits of utilizing natural ventilation at an extensive manner onto large-scale scenarios such as a national scenario by using a model of natural ventilation developed here. To do so, a building...

  8. Experimental study of buoyancy driven natural ventilation through horizontal openings

    OpenAIRE

    Heiselberg, Per; Li, Zhigang

    2007-01-01

    An experimental study of buoyancy driven natural ventilation through single-sided horizontal openings was performed in a full-scale laboratory test rig. Measurements were made for opening ratios L/D range from 0.027 to 4.455, where L and D are the length and the diameter of the opening, respectively. The bidirectional air flow rate was measured using constant injection tracer gas technique. Smoke visualizations showed that the air flow patterns are highly transient, unstable and complex, and ...

  9. Experimental study of buoyancy driven natural ventilation through horizontal openings

    DEFF Research Database (Denmark)

    Heiselberg, Per; Li, Zhigang

    2007-01-01

    An experimental study of buoyancy driven natural ventilation through single-sided horizontal openings was performed in a full-scale laboratory test rig. Measurements were made for opening ratios L/D range from 0.027 to 4.455, where L and D are the length and the diameter of the opening......, respectively. The bidirectional air flow rate was measured using constant injection tracer gas technique. Smoke visualizations showed that the air flow patterns are highly transient, unstable and complex, and that air flow rates oscillate with time. Correlations between the Froude number Fr and the L/D ratio...

  10. Assessment of Natural Ventilation Potential for Residential Buildings across Different Climate Zones in Australia

    Directory of Open Access Journals (Sweden)

    Zijing Tan

    2017-09-01

    Full Text Available In this study, the natural ventilation potential of residential buildings was numerically investigated based on a typical single-story house in the three most populous climate zones in Australia. Simulations using the commercial simulation software TRNSYS (Transient System Simulation Tool were performed for all seasons in three representative cities, i.e., Darwin for the hot humid summer and warm winter zone, Sydney for the mild temperate zone, and Melbourne for the cool temperate zone. A natural ventilation control strategy was generated by the rule-based decision-tree method based on the local climates. Natural ventilation hour (NVH and satisfied natural ventilation hour (SNVH were employed to evaluate the potential of natural ventilation in each city considering local climate and local indoor thermal comfort requirements, respectively. The numerical results revealed that natural ventilation potential was related to the local climate. The greatest natural ventilation potential for the case study building was observed in Darwin with an annual 4141 SNVH out of 4728 NVH, while the least natural ventilation potential was found in the Melbourne case. Moreover, summer and transition seasons (spring and autumn were found to be the optimal periods to sustain indoor thermal comfort by utilising natural ventilation in Sydney and Melbourne. By contrast, natural ventilation was found applicable over the whole year in Darwin. In addition, the indoor operative temperature results demonstrated that indoor thermal comfort can be maintained only by utilising natural ventilation for all cases during the whole year, except for the non-natural ventilation periods in summer in Darwin and winter in Melbourne. These findings could improve the understanding of natural ventilation potential in different climates, and are beneficial for the climate-conscious design of residential buildings in Australia.

  11. Single-sided Natural Ventilation Driven by a Combination of Wind Pressure and Temperature Difference

    DEFF Research Database (Denmark)

    Larsen, Tine Steen; Heiselberg, Per

    2007-01-01

    Natural ventilation is a commonly used principle when ventilation systems for buildings are designed. The ventilation can either be obtained by automatically controlled openings in the building envelope, or it can just be the simple action of opening a door or a window to let the fresh air in...

  12. Experimental Study of Wind-Opposed Buoyancy-Driven Natural Ventilation

    OpenAIRE

    Andersen, A.; Bjerre, M.; Chen, Z. D.; Heiselberg, Per; Li, Y.

    2000-01-01

    Natural ventilation driven by natural forces, i.e. wind and thermal buoyancy, is an environmentally friendly system for buildings and has been increasingly used around the world in recent years to mitigate the impact on the global environment due to the significant energy consumption by heating, ventilation and air-conditioning (HV AC). There is a need for the understanding and development of theories and tools related to the design, operation and control of natural ventilation systems.

  13. Experimental Study of Wind-Opposed Buoyancy-Driven Natural Ventilation

    DEFF Research Database (Denmark)

    Andersen, A.; Bjerre, M.; Chen, Z. D.

    Natural ventilation driven by natural forces, i.e. wind and thermal buoyancy, is an environmentally friendly system for buildings and has been increasingly used around the world in recent years to mitigate the impact on the global environment due to the significant energy consumption by heating......, ventilation and air-conditioning (HV AC). There is a need for the understanding and development of theories and tools related to the design, operation and control of natural ventilation systems....

  14. Calculation methods for single-sided natural ventilation - simplified or detailed?

    DEFF Research Database (Denmark)

    Larsen, Tine Steen; Plesner, Christoffer; Leprince, Valérie

    2016-01-01

    A great energy saving potential lies within increased use of natural ventilation, not only during summer and midseason periods, where it is mainly used today, but also during winter periods, where the outdoor air holds a great cooling potential for ventilative cooling if draft problems can...... be handled. This paper presents a newly developed simplified calculation method for single-sided natural ventilation, which is proposed for the revised standard FprEN 16798-7 (earlier EN 15242:2007) for design of ventilative cooling. The aim for predicting ventilative cooling is to find the most suitable......, while maintaining an acceptable correlation with measurements on average and the authors consider the simplified calculation method well suited for the use in standards such as FprEN 16798-7 for the ventilative cooling effects from single-sided natural ventilation The comparison of different design...

  15. Characteristics of Buoyancy Driven Natural Ventilation through Horizontal Openings

    DEFF Research Database (Denmark)

    Li, Zhigang

    through horizontal openings. Two cases of full-scale measurements of buoyancy driven natural ventilation through horizontal openings are performed: one horizontal opening and one horizontal opening combined with one vertical opening. For the case of one horizontal opening, the measurements are made....... Computational fluid dynamics (CFD) are used to study these two air flow cases. The air flow rate and air flow pattern are predicted and compared with the full-scale measurements. The measurement data are used to compare two CFD models: standard k- ε model and large eddy simulation (LES) model. The cases...... transient, unstable and complex, and the air flow rates oscillate with time. Correlations between the Froude number Fr and the opening ratio L/D are obtained, which is reasonable agreement with Epstein's formula derived from brine-water measurements, but the obtained Fr values show considerable deviations...

  16. The greenhouse effect and natural fluctuations of the climate

    International Nuclear Information System (INIS)

    Schoenwiese, C.D.

    1993-01-01

    There is a straight line connecting the first estimate in 1896 of worldwide climate changes due to the increasing use of fossil sources of energy with the Climate Convention of the United Nations at the 1992 Environmental Summit. Extensive model calculations exist of the 'greenhouse effect', in which the lower atmosphere is heated by manmade emissions of trace gases affecting the climate. However, the anticipated changes are not restricted to the temperature of the air; they affect the climate as a whole worldwide. As a consequence, the German Federal Government, in addition to its ban on CFCs, plans to reduce manmade carbon dioxide emissions by 25 or 30% by 2005. Natural fluctuations of the climate compete with the greenhouse effect: Volcanic and solar effects, but also random variations within the complicated interactions in the climatic system (atmosphere - oceans - ice regions - biosphere - land surface). Mathematical and statistical analyses of the superposition of such climatic mechanisms, which are based on data from observations, result in a risk analysis at a high level of probability. (orig.) [de

  17. Mine ventilation engineering

    Energy Technology Data Exchange (ETDEWEB)

    Hall, C.J.

    1981-01-01

    This book on mine ventilation covers psychometrics, airflow through roadways and ducts, natural ventilation, fans, instruments, ventilation surveys, auxiliary ventilation, air quality, and planning and economics.

  18. Greenhouse

    Data.gov (United States)

    Federal Laboratory Consortium — PurposeThe greenhouse at ERDC’s Cold Regions Research and Engineering Laboratory (CRREL) is used for germination and root-growth studies to support basic and field...

  19. The influence of wind direction on natural ventilation: application to a large semi-enclosed stadium

    NARCIS (Netherlands)

    Hooff, van T.A.J.; Blocken, B.J.E.

    2009-01-01

    Natural ventilation is still a commonly applied way in building engineering to ensure a healthy and comfortable indoor climate. In this paper CFD simulations of the natural ventilation of a large semi-enclosed stadium in the Netherlands during the summer are described. Simulations are performed to

  20. BSim models for 2 case-studies of naturally and mechanically ventilated daycare institutions

    Energy Technology Data Exchange (ETDEWEB)

    Kalyanova, O.; Heiselberg, P.

    2009-06-15

    The report intends to provide complete information necessary for evaluation of assumptions made in the models and conclusions derived from the results of simulation of two different institutions in various operational modes. Thermal models are prepared for two day-care buildings, one which is mechanically ventilated and one which is naturally ventilated. All simulations were preformed in BSim, and all the models are simulated in the current version og BSim which is version 6,8,9,8. The results of the simulations showed that it is possible to reduce energy use for ventilation, both in mechanically and naturally ventilated child care center without compromising indoor air quality. (ln)

  1. Vapour Removal from the Greenhouse Using Forced Ventilation when Applying a Thermal Screen

    NARCIS (Netherlands)

    Campen, J.B.

    2008-01-01

    The objective of this study is to dimension a system capable of removing water vapour mainly generated by evaporation of the crop when a thermal screen is applied. The humid greenhouse air is replaced by cold dry outside air using an air distribution system. The dry air is injected above the

  2. Thermal comfort in naturally ventilated buildings in Maceio, Brazil

    Science.gov (United States)

    Djamila, Harimi

    2017-11-01

    This article presents the results from thermal comfort survey carried out in classrooms over two different seasons in Maceio, Brazil. The secondary data were collected from thermal comfort field study conducted in naturally ventilated classrooms. Objective and subjective parameters were explored to evaluate thermal comfort conditions. The potential effect of air movement on subjects' vote under neutrality was evaluated. Overall, the indoor climate of the surveyed location was classified warm and humid. Conflicting results were depicted when analyzing the effect of air movements on subjects' vote. The mean air temperature for subjects feeling hot was found to be lower than those feeling warm. A reasonable approach to tackle these two unpredictable results was suggested. Correlation matrix between selected thermal comfort variables was developed. Globe temperature recorded the highest correlation with subjects' response on ASHRAE seven-point scale. The correlation was significant at the 0.01 level. On the other hand, the correlation between air movement and subjects' response on ASHRAE seven-point scale was weak but significant. Further field studies on the current topic were recommended.

  3. Use of natural basement ventilation to control radon in single family dwellings

    International Nuclear Information System (INIS)

    Cavallo, A.; Gadsby, K.; Reddy, T.A.

    1992-01-01

    Natural basement ventilation has always been recommended as a means of reducing radon levels in houses. However, its efficacy has never been documented. In these experiments, natural ventilation has for the first time been studied systematically in two research houses during both the summer cooling season and the winter heating season. Ventilation rates, environmental and house operating parameters, as well as radon levels, have been monitored. It can be definitely concluded from radon entry rate calculations that natural ventilation can reduce radon levels in two ways. The first is by simple dilution. The second is by reducing basement depressurization and thus the amount of radon-contaminated soil gas drawn into the structure. Therefore, basement ventilation can be an effective mitigation strategy under some circumstances. It might be especially useful in houses with low radon concentrations (of the order of 370 Bq m -1 ) or those with low levels and which cannot be mitigated cost-effectively with conventional technology. (Author)

  4. Single-sided natural ventilation through a centre-pivot roof window

    DEFF Research Database (Denmark)

    Iqbal, Ahsan; Nielsen, Peter V.; Gunner, Amalie

    2014-01-01

    The characteristics of centre pivot roof windows for wind driven single-sided ventilation has not been studied before. These types of windows are dominating roof windows in Europe. Knowledge of flow characteristics of this kind of window is essential for accurate designing of natural ventilation...... systems. In this study, numerical methods were used to characterise a centre-pivot roof window for wind-driven single-sided ventilation. A 1:20 scale model house of the Energy Flex House (Denmark) was used in this study. The roof slope was 36o. It was found that the single-sided ventilation through...

  5. Short-term airing by natural ventilation - modeling and control strategies.

    Science.gov (United States)

    Perino, M; Heiselberg, P

    2009-10-01

    The need to improve the energy efficiency of buildings requires new and more efficient ventilation systems. It has been demonstrated that innovative operating concepts that make use of natural ventilation seem to be more appreciated by occupants. This kind of system frequently integrates traditional mechanical ventilation components with natural ventilation devices, such as motorized windows and louvers. Among the various ventilation strategies that are currently available, buoyancy driven single-sided natural ventilation has proved to be very effective and can provide high air change rates for temperature and IAQ control. However, in order to promote a wider applications of these systems, an improvement in the knowledge of their working principles and the availability of new design and simulation tools is necessary. In this context, the paper analyses and presents the results of a research that was aimed at developing and validating numerical models for the analysis of buoyancy driven single-sided natural ventilation systems. Once validated, these models can be used to optimize control strategies in order to achieve satisfactory indoor comfort conditions and IAQ. Practical Implications Numerical and experimental analyses have proved that short-term airing by intermittent ventilation is an effective measure to satisfactorily control IAQ. Different control strategies have been investigated to optimize the capabilities of the systems. The proposed zonal model has provided good performances and could be adopted as a design tool, while CFD simulations can be profitably used for detailed studies of the pollutant concentration distribution in a room and to address local discomfort problems.

  6. Short-term airing by natural ventilation - implication on IAQ and thermal comfort.

    Science.gov (United States)

    Heiselberg, P; Perino, M

    2010-04-01

    The need to improve the energy efficiency of buildings requires new and more efficient ventilation systems. It has been demonstrated that innovative operating concepts that make use of natural ventilation seem to be more appreciated by occupants. Among the available ventilation strategies that are currently available, buoyancy driven, single-sided natural ventilation has proved to be very effective and can provide high air change rates for temperature and Indoor Air Quality (IAQ) control. However, to promote a wider distribution of these systems an improvement in the knowledge of their working principles is necessary. The present study analyses and presents the results of an experimental evaluation of airing performance in terms of ventilation characteristics, IAQ and thermal comfort. It includes investigations of the consequences of opening time, opening frequency, opening area and expected airflow rate, ventilation efficiency, thermal comfort and dynamic temperature conditions. A suitable laboratory test rig was developed to perform extensive experimental analyses of the phenomenon under controlled and repeatable conditions. The results showed that short-term window airing is very effective and can provide both acceptable IAQ and thermal comfort conditions in buildings. Practical Implications This study gives the necessary background and in-depth knowledge of the performance of window airing by single-sided natural ventilation necessary for the development of control strategies for window airing (length of opening period and opening frequency) for optimum IAQ and thermal comfort in naturally ventilated buildings.

  7. Analysis of Natural Ventilation in a Passive House Located in Cold Conditions

    DEFF Research Database (Denmark)

    Oropeza-Perez, Ivan; Østergaard, Poul Alberg; Remmen, Arne

    2013-01-01

    in Vejle during cooling season, in the months of June, July and August. The dwelling belongs to a Danish project of passive houses denominated Komfort Husene, where its occupants claim there is no thermal comfort in summer time. The results show that the use of natural ventilation helps to reduce......This article shows the potential of using natural ventilation as a passive method of cooling buildings that are located in cold climate countries using Denmark as a case study. The energy saving potential of natural ventilation is found by performing thermal simulations of a household located...

  8. Natural ventilation: it's as easy as opening the windows, or is it

    Energy Technology Data Exchange (ETDEWEB)

    Siebein, G.W.

    1984-10-01

    The research consisted of an evaluation of the existing technologies available for passive cooling with an emphasis on strategies related to the use of natural ventilation. A preliminary data base for the study was established by three major efforts: 1. An extensive literature search of the architectural press was undertaken to ascertain the degree to which passive cooling strategies in general and natural ventilation in particular are designed into buildings at the present time. 2. An investigation of existing building stock profiles was undertaken to identify the existing and potential obstacles or advantages to the implementation of natural ventilation as a passive cooling strategy. The EIA Nonresidential Buildings Energy Consumption Survey and two previous PNL studies were reviewed. 3. Components 1 and 2 were followed up with telephone interviews and site visits with the architects, building owners and operators of selected buildings from 1 and 2 above to gain more specific insights into the problems and pleasures typically associated with natural ventilation.

  9. Design and performance of a rule-based controller in a naturally ventilated room

    OpenAIRE

    Marjanovic-Halburd, Ljiljana; Angelov, P.; Eftekhari, M. M.

    2003-01-01

    This paper reflects the final phase of the EPSRC project, and the PhD work of Marjanovic, on rule-based control in naturally ventilated buildings. Marjanovic is the second author. Eftekhari was her PhD supervisor.

  10. Air flow distribution in and around a single-sided naturally ventilated room

    OpenAIRE

    Marjanovic-Halburd, Ljiljana; Eftekhari, M. M.; Pinnock, D. J.

    2003-01-01

    This paper reports on the initial findings of the EPSRC project on rule-based control in naturally ventilated buildings which led to Marjanovic's PhD thesis, supervised by Eftekhari. Marjanovic is the second author.

  11. Computational Fluid Dynamics Modeling to Improve Natural Flow Rate and Sweet Pepper Productivity in Greenhouse

    OpenAIRE

    W. Limtrakarn; P. Boonmongkol; A. Chompupoung; K. Rungprateepthaworn; J. Kruenate; P. Dechaumphai

    2012-01-01

    Natural flow rate and sweet peppers productivity in tropical greenhouse are improved by CFD simulation is the main objective of this research work. Most of the greenhouse types today are in the arch shape. To develop an improved greenhouse structure for the region, the arch type was built and used as the control model. Mae Sar Mai agriculture research station under the royal project foundation was selected as the field test site. Temperature sensors with data logger were installed to monitor ...

  12. The simulation of naturally ventilated residential buildings in semi-arid regions

    Energy Technology Data Exchange (ETDEWEB)

    Ghiabaklou, Z.; Ballinger, J.A.; Prasad, D.K. [New South Wales Univ., Kensington, NSW (Australia). Solar Architecture Research Unit

    1995-12-31

    The most important consideration in hot arid and semi-arid zones is to reduce the internal day temperature and to maintain the interior spaces of buildings in a comfortable condition. An important contributor to errors in the thermal analysis of naturally ventilated buildings is inaccurate airflow predictions. These predictions are important for designers in regions where most buildings are naturally ventilated. Passive cooling by day and night natural ventilation in a single story residential building in Wagga Wagga, a semi-arid location in New South Wales has been compared and analyzed theoretically. A modified version of the computer simulation program CHEETAH, has been used to consider a building with continuous natural ventilation to simulate indoor air temperature. The aim of the study was to investigate the thermal behaviour of the building with continuous ventilation (24 hour/day) and the same building with only night time ventilation. Using night time ventilation in high mass buildings in such a climate, leads to a considerable decrease in room air temperature. Simulation results showed that increasing the effective area of windows is effective only when the wind blows. Using a steady averaged air change per hour can also cause a reduction in room air temperatures which results in different temperatures than the actual air changes per hour. (author). 3 figs., 4 refs.

  13. In vitro growth and leaf anatomy of Cattleya walkeriana (Gardner, 1839 grown in natural ventilation system

    Directory of Open Access Journals (Sweden)

    Adriano Bortolotti da Silva

    2014-12-01

    Full Text Available Natural ventilation system facilitates gaseous exchanges in in vitro plants promoting changes in the leaf tissue, which can be evaluated through the leaf anatomy, and it allows a cultivation closer to the photoautrophic micropropagation. The objective of this work was to evaluate the effects on in vitro growth and on the leaf anatomy of Cattleya walkeriana grown in natural and conventional ventilation system with different concentrations of sucrose (0; 15; 30 and 45 L-1 combined with different cultivation systems (conventional micropropagation and natural ventilation system. The culture medium was composed of MS salts, solidified with 7 g L-1 of agar and pH adjusted to 5.8. Forty milliliters of culture medium were distributed in 250 mL flasks, autoclaved at 120 ºC for 20 minutes. The greater plant growth, as well as the greater thickness of the mesophyll was observed with the use of 20 g L-1 sucrose in natural ventilation system. Plants grown in natural ventilation system showed a thicker leaf mesophyll, which is directly related to photoautotrophic crops. The natural ventilation system induced more elliptical stomata and probably more functional formats.

  14. Natural ventilation in organic poultry houses in cold weather

    Science.gov (United States)

    This topic was suggested as a way to address concerns with winter ventilation and temperature control. The suggestion came with a request that the presentation cover “proper management in cooler ambient temps. The broad issue is most organic egg production is brown and these birds have an easy abil...

  15. The Effects of Void on Natural Ventilation Performance in Multi-Storey Housing

    Directory of Open Access Journals (Sweden)

    Fakhriah Muhsin

    2016-08-01

    Full Text Available Enhancing natural ventilation performance in multi-storey housing is very important for the living environment in terms of health and thermal comfort purposes. One of the most important design strategies to enhance natural ventilation in multi-storey housing is through the provision of voids. A void is a passive architectural feature, which is located in the middle of deep plan buildings. It is very crucial to consider the configurations of voids in the buildings for enhancing natural ventilation, especially for multi-storey housing. In this study, Malaysian Medium Cost Multi-Storey Housing (MMCMSH, which is an example of multi-storey housing located in a suburban area, has been selected in this study. This study aims to investigate the potential of void for enhancing natural ventilation performance in multi-storey housing by the comparison of two different void configurations. Field measurement of MMCMSH has been conducted to validate Computational Fluid Dynamic (CFD model and Atmospheric Boundary Layer (ABL is an important parameter for setting up the CFD Model’s domain. Ventilation rate (Q, which is necessary for comfort and health reasons, is an important parameter for the comparison of the different void configurations. This study revealed that the provision of void can enhance natural ventilation performance in multi-storey housing with an increase in the value of Q, from 3.44% to 40.07%, by enlarging the void’s width by 50% compared to the existing void.

  16. Application of Breathing Architectural Members to the Natural Ventilation of a Passive Solar House

    Directory of Open Access Journals (Sweden)

    Kyung-Soon Park

    2016-03-01

    Full Text Available The efficient operation of a passive solar house requires an efficient ventilation system to prevent the loss of energy and provide the required ventilation rates. This paper proposes the use of “breathing architectural members” (BAMs as passive natural ventilation devices to achieve much improved ventilation and insulation performance compared to mechanical ventilation. Considering the importance of evaluating the ventilation and insulation performances of the members, we also propose numerical models for predicting the heat and air movements afforded by the members. The numerical model was validated by comparison with experimental results. The effectiveness of the BAMs was also verified by installation in houses located in an area with warm climate. For this purpose, chamber experiments were performed using samples of the BAMs, as well as numerical simulations to assess natural ventilation and heat load. The main findings of the study are as follows: (1 the one-dimensional chamber experiments confirmed the validity of the numerical models for predicting the heat and air movements afforded by the BAMs. Comparison of the experimental and calculated values for the temperature of air that flowed into the room from outside revealed a difference of less than 5%; (2 observations of the case studies in which BAMs were installed in the ceilings and exterior walls of Tokyo model houses revealed good annual ventilation and energy-saving effects. When BAMs with an opening area per unit area of A = 0.002 m2/m2 were applied to three surfaces, the required ventilation rate was 0.5 ACH (air changes per hour, and this was achieved consistently. Compared to a house with general insulation and conventional mechanical ventilation, heating load was reduced by 15.3%–40.2% depending on the BAM installation points and the differing areas of the house models.

  17. Change-over natural and mechanical ventilation system energy consumption in single-family buildings

    Science.gov (United States)

    Kostka, Maria; Szulgowska-Zgrzywa, Małgorzata

    2017-11-01

    The parameters of the outside air in Poland cause that in winter it is reasonable to use a mechanical ventilation equipped with a heat recovery exchanger. The time of spring, autumn, summer evenings and nights are often characterized by the parameters of the air, which allow for a natural ventilation and reduce the electricity consumption. The article presents the possibilities of energy consumption reduction for three energy standards of buildings located in Poland, ventilated by a change-over hybrid system. The analysis was prepared on the assumption that the air-to-water heat pump is the heat source for the buildings.

  18. Numerical investigation of airborne infection in naturally ventilated hospital wards with central-corridor type

    DEFF Research Database (Denmark)

    Zhou, Qi; Qian, Hua; Liu, Li

    2018-01-01

    Natural ventilation is believed to control airborne infection due to high ventilation rates while an undesired flow pattern may cause infection transmission in hospital wards. A computational fluid dynamics simulation was carried out in this study to investigate the impact of airflow pattern....... The results not only give direct evidence to strongly support World Health Organization’s recommendation but also suggest required amendment of the Chinese standard GB 51039-2014 to improve ventilation arrangement in general hospital wards in China. Our findings are useful for improving the future design...... of general hospital wards for airborne infection control....

  19. Greenhouse Gases

    Science.gov (United States)

    ... Production of Hydrogen Use of Hydrogen Greenhouse Gases Basics | | Did you know? Without naturally occurring greenhouse gases, the earth would be too cold to support life as we know it. Without the greenhouse effect, ...

  20. [Likeness between respiratory responses on CO2 in conditions of natural breathing and voluntary-controlled mechanical ventilation].

    Science.gov (United States)

    Pogodin, M A; Granstrem, M P; Dimitrienko, A I

    2007-04-01

    We did Read CO2 rebreathing tests in 8 adult males. Both at natural breathing, and at self-controlled mechanical ventilation, volunteers increased ventilation proportionally to growth end-tidal PCO2. Inside individual distinctions of responses to CO2 during controlled mechanical ventilation are result of the voluntary motor control.

  1. Measurement and Modelling of Air Flow Rate in a Naturally Ventilated Double Skin Facade

    DEFF Research Database (Denmark)

    Heiselberg, Per; Kalyanova, Olena; Jensen, Rasmus Lund

    2008-01-01

    Air flow rate in a naturally ventilated double skin façade (DSF) is extremely difficult to measure due to the stochastic nature of wind, and as a consequence non-uniform and dynamic flow conditions. This paper describes the results of two different methods to measure the air flow in a full...... by the thermal simulation program, BSim, based on measured weather boundary conditions are compared to the measured air temperature, temperature gradient and mass flow rate in the DSF cavity. The results show that it is possible to predict the temperature distribution and airflow in the DSF although some......-scale outdoor test facility with a naturally ventilated double skin façade. Although both methods are difficult to use under such dynamic air flow conditions, they show reasonable agreement and can be used for experimental validation of numerical models of natural ventilation air flow in DSF. Simulations...

  2. A CFD study for evaluating the effects of natural ventilation on indoor comfort conditions

    Directory of Open Access Journals (Sweden)

    Miguel Mora-Pérez

    2017-03-01

    Full Text Available There is an increasing interest in improving energy efficiency in buildings due to the increased awareness about environmental impact and energy cost. Natural ventilation is an environmentally friendly technique which has become more attractive way for reducing energy use while it also provides acceptable comfort conditions. The research shows a case study building in which the natural ventilation effect due to wind-driven forces on indoor comfort conditions is evaluated. Moreover, the architectural solutions selected during the building design phase to improve the natural ventilation behaviour are successfully validated in a full-scale building. The indoor comfort conditions are evaluated through contrasted performance indicators: draught risk (DR, predicted percentage of dissatisfied people (PPD and predicted mean vote (PMV indexes. The results show that air movement due to natural ventilation allows increasing indoor air temperature maintaining the initial comfort conditions. Therefore, the mechanical air conditioning use can be postponed until the indoor air temperature is high and would, consequently, reduce the total building energy consumption. Thereby, a proper natural ventilation focus during the initial design stage could improve the building energy efficiency without compromising the indoor comfort conditions.

  3. Ventilation and internal structure effects on naturally induced flows in a static aircraft wing

    International Nuclear Information System (INIS)

    Moore, Daithi; Newport, David; Egan, Vanessa; Lacarac, Vesna

    2012-01-01

    The ventilation performance within an aircraft wing leading edge is investigated for a number of enclosure and ventilation configurations. The natural convection regime present is found to be highly sensitive to enclosure conditions, particularly the introduction of a partition. The presence of a partition reduced the overall heat exhausted from the cavity by up to 60%. The optimum ventilation strategy is also changed from a forward biased vent orientation (found for the unpartitioned case), to one where both the rear and front vents within the enclosure had the same open area. Cylinder plume effects dominate within the enclosure and were the main driver of the convective regime, with steady-state enclosure conditions highly dependent upon cylinder placement and plume orientation. An externally heated enclosure with internal heat source, combined with ventilation and an internal structure produced a complex natural convection regime which is sensitive to enclosure conditions. Hence an adequate knowledge of such conditions is necessary in order to fully appreciate the convective regime. - Highlights: → Optimum ventilation strategy changed between unpartitioned and partitioned cases. → Flow path and plume orientation are important to consider when analysing ventilation. → Bleed duct placement significantly alters flow path and temperature distribution. → Enclosure partitioning reduced heat exhaustion by 60%.

  4. Evaluation of Discharge Coefficients for Window Openings in Wind Driven Natural Ventilation

    DEFF Research Database (Denmark)

    Heiselberg, Per; Sandberg, Mats

    2006-01-01

    This paper describes the classical approach for calculation of wind driven airflow through large openings in buildings and discusses the fulfilment of the limiting assumptions. It is demonstrated that the limiting assumptions are not fulfilled for large openings in buildings for cross ventilation...... cannot be regarded as a constant and it is very difficult to estimate correct values resulting in less accuracy of prediction of natural ventilation.......This paper describes the classical approach for calculation of wind driven airflow through large openings in buildings and discusses the fulfilment of the limiting assumptions. It is demonstrated that the limiting assumptions are not fulfilled for large openings in buildings for cross ventilation......, and therefore, the classical approach is not appropriate for prediction of airflow through large openings in buildings in the cross ventilation case. Using the approach for real openings and estimating the discharge coefficient for window openings has also not been very successful. The discharge coefficient...

  5. 2012 Stakeholder Workshop on Natural Gas in the Inventory of U.S. Greenhouse Gas Emissions and Sinks

    Science.gov (United States)

    This page describes EPA's September 2012 stakeholder workshop on key aspects of the estimates of greenhouse gas emissions from the natural gas sector in the Inventory of U.S. Greenhouse Gas Emissions and Sinks.

  6. A First Approach to Natural Thermoventilation of Residential Buildings through Ventilation Chimneys Supplied by Solar Ponds

    Directory of Open Access Journals (Sweden)

    Ferdinando Salata

    2015-07-01

    Full Text Available The exploitation of natural ventilation is a good solution to improve buildings from an energetic point of view and to fulfill the requirements demanded by the thermohygrometric comfort and the air quality in enclosed spaces. Some past researches demonstrated how some devices, useful to this purpose, follow the principles of solar chimneys and are able to move air masses while exploiting the Archimedes thrust. The natural ventilation must be supplied by a flow moving upward, generated by a heat source performing at temperatures slightly higher than the one present in the environment. To have a minimum energetic effect, the heat can be extracted from solar ponds; solar ponds are able to collect and store solar energy in the geographical regions characterized by sufficient values of solar radiation. Thus it is possible, in summer, to provoke a nocturnal natural ventilation useful for the air change in indoor spaces (in those climatic areas where, during the night, there is a temperature gradient.

  7. Peat and the greenhouse effect - Comparison of peat with coal, oil, natural gas and wood

    International Nuclear Information System (INIS)

    Hillebrand, K.

    1993-01-01

    The earth's climate is effected both by natural factors and human activities. So called greenhouse gas emissions increase the increment of the temperature of the air nearby the earth's surface, due to which the social changes can be large. The increment of greenhouse gas concentration in the atmosphere is due to increasing energy consumption. About 50 % of the climatic changes are caused by increase of the CO 2 concentration in the atmosphere. Other gases, formed in the energy production, intensifying the greenhouse effect are methane and nitrous oxide. The effect of greenhouse gases is based on their ability to absorb infrared radiation coming from the earth. This presentation discusses some of the greenhouse effect caused by some peat production and utilization chains in comparison with corresponding effects of coal, oil, natural gas and wood. The instantaneous greenhouse effects and the cumulative effects of the emissions of the gases (CO 2 , CH 4 and N 2 O) during a time period has been reviewed. The greenhouse effect has been calculated as CO 2 - equivalents. (5 figs.)

  8. The influence of an estimated energy saving due to natural ventilation on the Mexican energy system

    DEFF Research Database (Denmark)

    Oropeza-Perez, Ivan; Østergaard, Poul Alberg

    2014-01-01

    This article shows the impacts of the extensive use of NV (natural ventilation) in the Mexican residential sector on the Mexican energy system. By integrating a thermal-airflow simulation programme with an energy systems analysis model, the impact on the Mexican energy system of replacing air...... conditioning, in particular, with natural ventilation to cool residential buildings is determined. It is shown that when, as in Mexico, there is a relatively simple connection between supply and electricity demand, NV creates savings which could be used to reduce either the fossil-fuel-based generation...

  9. Climate Change and the Greenhouse Effect - Nature and Humans

    Science.gov (United States)

    Alevizos, Anastasios; Zygouras, Grigorios

    2014-05-01

    In this project twenty A grade students of Lyceum (age 16) were involved (2011-12) and had been learning to give answers to questions about greenhouse gases, their origin and the processes forming them with regard to human activity on our planet and our dependence on fossil fuels. They had considered whether and how this dependence affects global warming, how this dependence can be reduced by changing attitudes and using renewable energy sources and further more they had put questions and doubts about anthropogenic global warming existence. The student dialogues during a '' TV series debate '' concerning the views, questions and answers of three groups, the ''IPCCs'', the ''CLIMATE SCEPTICS'' and the '' REALISTS'' are exposed on a poster.

  10. Natural-basement ventilation as a radon-mitigation technique. Final report Jun 89-Feb 91

    International Nuclear Information System (INIS)

    Cavallo, A.; Gadsby, K.; Reddy, T.A.

    1992-04-01

    The report documents a study of natural basement ventilation in two research houses during both the summer cooling season and the winter heating season. (NOTE: Natural basement ventilation has always been recommended as a way to reduce radon levels in houses. However, its efficacy has never been documented. It has generally been assumed to be a very inefficient mitigation strategy since it was believed that dilution was the mechanism by which radon levels were reduced.) Ventilation rates, environmental and house operating parameters, and radon levels have been monitored; it can be concluded that natural ventilation can reduce radon levels two ways: (1) by simple dilution, and (2) although less obvious, by providing a pressure break that reduces basement depressurization and thus the amount of radon-contaminated soil gas drawn into the house. Thus, basement ventilation can be a much more effective mitigation strategy than was previously believed. It might be especially useful in houses with low radon concentrations (of the order of 10 pCi/L) or those with low levels that cannot be mitigated cost-effectively with conventional technology

  11. Greenhouse gas emissions from high demand, natural gas-intensive energy scenarios

    International Nuclear Information System (INIS)

    Victor, D.G.

    1990-01-01

    Since coal and oil emit 70% and 30% more CO 2 per unit of energy than natural gas (methane), fuel switching to natural gas is an obvious pathway to lower CO 2 emissions and reduced theorized greenhouse warming. However, methane is, itself, a strong greenhouse gas so the CO 2 advantages of natural gas may be offset by leaks in the natural gas recovery and supply system. Simple models of atmospheric CO 2 and methane are used to test this hypothesis for several natural gas-intensive energy scenarios, including the work of Ausubel et al (1988). It is found that the methane leaks are significant and may increase the total 'greenhouse effect' from natural gas-intensive energy scenarios by 10%. Furthermore, because methane is short-lived in the atmosphere, leaking methane from natural gas-intensive, high energy growth scenarios effectively recharges the concentration of atmospheric methane continuously. For such scenarios, the problem of methane leaks is even more serious. A second objective is to explore some high demand scenarios that describe the role of methane leaks in the greenhouse tradeoff between gas and coal as energy sources. It is found that the uncertainty in the methane leaks from the natural gas system are large enough to consume the CO 2 advantages from using natural gas instead of coal for 20% of the market share. (author)

  12. Enhancement of natural ventilation in buildings using a thermal chimney

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kwang Ho [University of California at Berkeley, Berkeley, CA (United States); Strand, Richard K. [University of Illinois at Urbana-Champaign, Champaign, IL (United States)

    2009-06-15

    A new module was developed for and implemented in the EnergyPlus program for the simulation and determination of the energy impact of thermal chimneys. This paper describes the basic concepts, assumptions, and algorithms implemented into the EnergyPlus program to predict the performance of a thermal chimney. Using the new module, the effects of the chimney height, solar absorptance of the absorber wall, solar transmittance of the glass cover and the air gap width are investigated under various conditions. Chimney height, solar absorptance and solar transmittance turned out to have more influence on the ventilation enhancement than the air gap width. The potential energy impacts of a thermal chimney under three different climate conditions are also investigated. It turned out that significant building cooling energy saving can be achieved by properly employing thermal chimneys and that they have more potential for cooling than for heating. In addition, the performance of a thermal chimney was heavily dependent on the climate of the location. (author)

  13. 76 FR 80553 - Mandatory Reporting of Greenhouse Gases: Technical Revisions to the Petroleum and Natural Gas...

    Science.gov (United States)

    2011-12-23

    ... permeability gas, shale gas, coal seam, or other tight reservoir rock. For example, wells producing coal bed... separation means one or more of the following processes: forced extraction of natural gas liquids, sulfur and... Mandatory Reporting of Greenhouse Gases: Technical Revisions to the Petroleum and Natural Gas Systems...

  14. Lifecycle greenhouse gas emissions of coal, conventional and unconventional natural gas for electricity generation

    Science.gov (United States)

    An analysis of the lifecycle greenhouse gas (GHG) emissions associated with natural gas use recently published by Howarth et al. (2011) stated that use of natural gas produced from shale formations via hydraulic fracturing would generate greater lifecycle GHG emissions than petro...

  15. Computational Analysis of Natural Ventilation Flows in Geodesic Dome Building in Hot Climates

    Directory of Open Access Journals (Sweden)

    Zohreh Soleimani

    2016-08-01

    Full Text Available For centuries, dome roofs were used in traditional houses in hot regions such as the Middle East and Mediterranean basin due to its thermal advantages, structural benefits and availability of construction materials. This article presents the computational modelling of the wind- and buoyancy-induced ventilation in a geodesic dome building in a hot climate. The airflow and temperature distributions and ventilation flow rates were predicted using Computational Fluid Dynamics (CFD. The three-dimensional Reynolds-Averaged Navier-Stokes (RANS equations were solved using the CFD tool ANSYS FLUENT15. The standard k-epsilon was used as turbulence model. The modelling was verified using grid sensitivity and flux balance analysis. In order to validate the modelling method used in the current study, additional simulation of a similar domed-roof building was conducted for comparison. For wind-induced ventilation, the dome building was modelled with upper roof vents. For buoyancy-induced ventilation, the geometry was modelled with roof vents and also with two windows open in the lower level. The results showed that using the upper roof openings as a natural ventilation strategy during winter periods is advantageous and could reduce the indoor temperature and also introduce fresh air. The results also revealed that natural ventilation using roof vents cannot satisfy thermal requirements during hot summer periods and complementary cooling solutions should be considered. The analysis showed that buoyancy-induced ventilation model can still generate air movement inside the building during periods with no or very low wind.

  16. Naturally ventilated double-skin façade in modeling and experiments

    DEFF Research Database (Denmark)

    Dama, Alessandro; Angeli, Diego; Larsen, Olena Kalyanova

    2017-01-01

    Highlights •An experimental validation of a model, developed for integration of DSF in Building Simulation tools, is given. •The validation was based on heat removed by natural ventilation, which is the main parameter in passive cooling systems. •A good degree of correlation was found between the...

  17. Optimization of air-curtain sealing efficiency with respect to heat transfer in naturally ventilated buildings

    NARCIS (Netherlands)

    Khayrullina, A.; Hooff, van T.A.J.; Blocken, B.J.E.; van Heijst, G.J.F.; Sun, Y.; Pei, J.; Zhao, X

    This study presents results of coupled 3D steady Reynolds-averaged Navier-Stokes (RANS) Computational Fluid Dynamics (CFD) simulations of an isolated naturally-ventilated building with the application of an air curtain to prevent heat transfer across a doorway. The considered parameters include air

  18. Dynamic model to tune a climate control algorithm in pig houses with natural ventilation

    NARCIS (Netherlands)

    Klooster, van 't C.E.; Bontsema, J.; Salomons, L.

    1995-01-01

    Algorithms for environmental control in livestock buildings have to be tuned for optimum response of actuators. For tuning, a simple, but dynamic, climate model for a pig house was formulated and validated to predict the
    environmental changes in a pig house with natural ventilation under varying

  19. Effects of Natural Sounds on Pain: A Randomized Controlled Trial with Patients Receiving Mechanical Ventilation Support.

    Science.gov (United States)

    Saadatmand, Vahid; Rejeh, Nahid; Heravi-Karimooi, Majideh; Tadrisi, Sayed Davood; Vaismoradi, Mojtaba; Jordan, Sue

    2015-08-01

    Nonpharmacologic pain management in patients receiving mechanical ventilation support in critical care units is under investigated. Natural sounds may help reduce the potentially harmful effects of anxiety and pain in hospitalized patients. The aim of this study was to examine the effect of pleasant, natural sounds on self-reported pain in patients receiving mechanical ventilation support, using a pragmatic parallel-arm, randomized controlled trial. The study was conducted in a general adult intensive care unit of a high-turnover teaching hospital, in Tehran, Iran. Between October 2011 and June 2012, we recruited 60 patients receiving mechanical ventilation support to the intervention (n = 30) and control arms (n = 30) of a pragmatic parallel-group, randomized controlled trial. Participants in both arms wore headphones for 90 minutes. Those in the intervention arm heard pleasant, natural sounds, whereas those in the control arm heard nothing. Outcome measures included the self-reported visual analog scale for pain at baseline; 30, 60, and 90 minutes into the intervention; and 30 minutes post-intervention. All patients approached agreed to participate. The trial arms were similar at baseline. Pain scores in the intervention arm fell and were significantly lower than in the control arm at each time point (p natural sounds via headphones is a simple, safe, nonpharmacologic nursing intervention that may be used to allay pain for up to 120 minutes in patients receiving mechanical ventilation support. Copyright © 2015 American Society for Pain Management Nursing. Published by Elsevier Inc. All rights reserved.

  20. Model of natural ventilation by using a coupled thermal-airflow simulation program

    DEFF Research Database (Denmark)

    Oropeza-Perez, Ivan; Østergaard, Poul Alberg; Remmen, Arne

    2012-01-01

    This article presents a model of natural ventilation of buildings at the stage of design and a consequence of the behaviour of the occupants. An evaluation is made by coupling multizone air modelling and thermal building simulation using a deterministic set of input factors comprising among others...

  1. Occupant Time Period of Thermal Adaption to Change of Outdoor Air Temperature in Naturally Ventilated Buildings

    DEFF Research Database (Denmark)

    liu, weiwei; Wargocki, Pawel; Xiong, Jing

    2014-01-01

    The present work proposed a method to determine time period of thermal adaption of occupants in naturally ventilated building, based on the relationship between their neutral temperatures and running mean outdoor air temperature. Based on the data of the field investigation, the subjects’ time...

  2. Experimental and numerical study on natural ventilation performance of various multi-opening wind catchers

    NARCIS (Netherlands)

    Montazeri, H.

    2011-01-01

    Wind catcher as a natural ventilation system is increasingly used in modern buildings to minimize the consumption of non-renewable energy and reduce the harmful emissions. Height, cross section of the air passages and also place and the number of openings are the main factors which affect the

  3. Bed Microenvironment in Hospital Patient Rooms with Natural or Mechanical Ventilation

    DEFF Research Database (Denmark)

    Melikov, Arsen Krikor; Li, Yuguo; Georgiev, Emanuil

    2012-01-01

    We studied how to provide patients in bed with thermally comfortable microenvironment in both naturally and mechanically ventilated hospital rooms for both winter and summer seasons. A climate chamber was used to resemble a hospital room and thermal manikin to simulate a patient lying in a bed...

  4. Relationship of Indoor and Outdoor Air Pollutants in a Naturally Ventilated Historical Building Envelope

    Czech Academy of Sciences Publication Activity Database

    López-Aparicio, S.; Smolík, Jiří; Mašková, Ludmila; Součková, M.; Grøntoft, T.; Ondráčková, Lucie; Stankiewicz, J.

    2011-01-01

    Roč. 46, č. 7 (2011), s. 1460-1468 ISSN 0360-1323 Grant - others:MF NF(CZ) A/CZ0046/2/0001 Institutional research plan: CEZ:AV0Z40720504 Keywords : indoor/outdoor ration * natural ventilation * ammonia Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.400, year: 2011

  5. Influence of wind direction and urban surroundings on natural ventilation of a large football stadium

    NARCIS (Netherlands)

    Hooff, van T.A.J.; Blocken, B.J.E.

    2011-01-01

    In this paper, CFD simulations of the natural ventilation of a large semi-enclosed stadium in the Netherlands during summer conditions are described. The simulations are performed to assess the air exchange rate for eight wind directions. The CFD model consists of both the complex stadium geometry

  6. The Design and Simulation of Natural Personalised Ventilation (NPV System for Multi-Bed Hospital Wards

    Directory of Open Access Journals (Sweden)

    Zulfikar A. Adamu

    2015-05-01

    Full Text Available Adequate ventilation is necessary for thermal comfort and reducing risks from infectious bio-aerosols in hospital wards, but achieving this with mechanical ventilation has carbon and energy implications. Natural ventilation is often limited to window-based designs whose dilution/mixing effectiveness are subject to constraints of wind speed, cross ventilation, and in the case of hospital wards, proximity of patients to external walls. A buoyancy-driven natural ventilation system capable of achieving dilution/mixing was shown to be feasible in a preceding study of novel system called natural personalised ventilation (NPV. This system combined both architecture and airflow engineering principles of space design and buoyancy and was tested and validated (salt-bath experiment for a single bed ward. This research extends the previous work and is proof-of-concept on the feasibility of NPV system for multi-bed wards. Two different four-bed ward types were investigated of using computational fluid dynamics (CFD simulations under wind-neutral conditions. Results predict that NPV system could deliver fresh air to multiple patients, including those located 10 m away from external wall, with absolute flow rates of between 32 L·s−1 and 54 L·s−1 for each patient/bed. Compared to same wards simulated using window design, ingress of airborne contaminants into patients’ breathing zone and summer overheating potential were minimised, while overall ward dilution was maximised. Findings suggest the NPV has potentials for enabling architects and building service engineers to decouple airflow delivery from the visualisation and illumination responsibilities placed upon windows.

  7. Natural ventilation of the Romance churches. Prophylaxis and constructive security; Ventilacion natural de las iglesias romanicas. Profilaxis y seguridad constructiva

    Energy Technology Data Exchange (ETDEWEB)

    Arroba, M.; Grau, J.; Alanon, P.; Diez-Pastor, C.; Garcia, J.

    2008-07-01

    As part of an investigation project on three medieval churches of Segovia, financed by the Junta de Castilla y Leon, a study of hygrometric behaviour of these three buildings was carried out. The analysis of natural ventilation is essential, not only as an eliminator of pollutants but also as a reducer of the infiltrated water that could deteriorate structures. The appearance in these buildings of a series of openings or, in their case, fissures-that allows the infiltration of air (the combination provides perfect sweeping of the interior of the buildings), can only be justified by ventilation necessities, and not for the requirements of interior illumination. (Author)

  8. Single-sided natural ventilation driven by wind pressure and temperature difference

    DEFF Research Database (Denmark)

    Larsen, Tine Steen; Heiselberg, Per

    2008-01-01

    -scale wind tunnel experiments have been made with the aim of making a new expression for calculation of the airflow rate in single-sided natural ventilation. During the wind tunnel experiments it was found that the dominating driving force differs between wind speed and temperature difference depending......Even though opening a window for ventilation of a room seems very simple, the flow that occurs in this situation is rather complicated. The amount of air going through the window opening will depend on the wind speed near the building, the temperatures inside and outside the room, the wind...

  9. BSim Models for 2 Case-studies of Naturally and Mechanically Ventilated Daycare Institutions

    DEFF Research Database (Denmark)

    Larsen, Olena Kalyanova; Heiselberg, Per

    and conclusions derived from the results of simulation of two different institutions in various operational modes. Thermal models are prepared for two buildings, which are: SFO Nymarken in Kerterminde and SFO Spirehuset in Hirtshals. The main operational principles in these buildings are significantly different......, as SFO Nymarken is mechanically ventilated and SFO Spirehuset is naturally ventilated. All of the simulations were carried in BSim, and all of the models are simulated in the current version of BSim, which is version 6,8,9,8....

  10. Preliminary study of ammonia emissions from naturally ventilated fattening pig houses in the south-east China

    Energy Technology Data Exchange (ETDEWEB)

    Wang, K.; Ye, Z.; Li, H. [Zhejiang Univ., Hangzhou City (China). School of Biosystems Engineering and Food Science

    2010-07-01

    This paper reported on an experimental simulation in which ammonia emissions from naturally ventilated pig houses were monitored and the ventilation airflow rate was estimated. Two identical pig houses and the same number of pigs were used in the study. Natural ventilation was used in the experimental pig house while the reference pig house had mechanical ventilation. Both houses had the same air temperature and relative humidity. The ventilation airflow rate of the experimental pig house was estimated by calculating the ventilation airflow rate in the reference pig house. The ventilation airflow rate of the experimental pig house was also estimated based on heat pressure theory. The room air temperature and relative humidity were found to be related to inlet air temperature and relative humidity for both ventilation systems. After 19 days, the average air temperature in the room with mechanical ventilation was about 4.1 degrees C higher than inlet air temperature, but the relative humidity was lower by 7.1 per cent. In the room with natural ventilation, the average air temperature after 19 days was about 3.9 degrees C higher than inlet air temperature, but the relative humidity was lower by 4.3 per cent.

  11. Ventilation of carbon monoxide from a biomass pellet storage tank--a study of the effects of variation of temperature and cross-ventilation on the efficiency of natural ventilation.

    Science.gov (United States)

    Emhofer, Waltraud; Lichtenegger, Klaus; Haslinger, Walter; Hofbauer, Hermann; Schmutzer-Roseneder, Irene; Aigenbauer, Stefan; Lienhard, Martin

    2015-01-01

    Wood pellets have been reported to emit toxic gaseous emissions during transport and storage. Carbon monoxide (CO) emission, due to the high toxicity of the gas and the possibility of it being present at high levels, is the most imminent threat to be considered before entering a pellet storage facility. For small-scale (ventilation, preferably natural ventilation utilizing already existing openings, has become the most favored solution to overcome the problem of high CO concentrations. However, there is little knowledge on the ventilation rates that can be reached and thus on the effectiveness of such measures. The aim of the study was to investigate ventilation rates for a specific small-scale pellet storage system depending on characteristic temperature differences. Furthermore, the influence of the implementation of a chimney and the influence of cross-ventilation on the ventilation rates were investigated. The air exchange rates observed in the experiments ranged between close to zero and up to 8 m(3) h(-1), depending largely on the existing temperature differences and the existence of cross-ventilation. The results demonstrate that implementing natural ventilation is a possible measure to enhance safety from CO emissions, but not one without limitations. © The Author 2014. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

  12. Data on the natural ventilation performance of windcatcher with anti-short-circuit device (ASCD).

    Science.gov (United States)

    Nejat, Payam; Calautit, John Kaiser; Majid, Muhd Zaimi Abd; Hughes, Ben Richard; Jomehzadeh, Fatemeh

    2016-12-01

    This article presents the datasets which were the results of the study explained in the research paper 'Anti-short-circuit device: a new solution for short-circuiting in windcatcher and improvement of natural ventilation performance' (P. Nejat, J.K. Calautit, M.Z. Abd. Majid, B.R. Hughes, F. Jomehzadeh, 2016) [1] which introduces a new technique to reduce or prevent short-circuiting in a two-sided windcatcher and also lowers the indoor CO2 concentration and improve the ventilation distribution. Here, we provide details of the numerical modeling set-up and data collection method to facilitate reproducibility. The datasets includes indoor airflow, ventilation rates and CO2 concentration data at several points in the flow field. The CAD geometry of the windcatcher models are also included.

  13. An Attempt to Design a Naturally Ventilated Tower in Subtropical Climate of the Developing Country; Pakistan

    Directory of Open Access Journals (Sweden)

    Sohail Maha

    2017-12-01

    Full Text Available A large proportion of the world’s population resides in developing countries where there is a lack of rigorous studies in designing energy efficient buildings. This study is a step in designing a naturally ventilated high rise residential building in a tropical climatic context of the developing country, Pakistan. Karachi, the largest city of Pakistan, lies in the subtropical hot desert region with constant high temperature of average 32 °C throughout the summer and no particular winter season. The Design Builder software package is used to design a 25 storey high rise residential building relying primarily on natural ventilation. A final conceptual design is proposed after optimization of massing, geometry, orientation, and improved building envelope design including extensive shading devices in the form of trees. It has been observed that a reduction of 8 °C in indoor ambient temperature is possible to achieve with passive measures and use of night time ventilation. A fully naturally ventilated building can reduce the energy consumption for cooling and heating by 96 % compared to a building using air conditioning systems.

  14. A Natural Ventilation Alternative to the Passivhaus Standard for a Mild Maritime Climate

    Directory of Open Access Journals (Sweden)

    Paola Sassi

    2013-01-01

    Full Text Available This study examines the need in mild maritime climates, such as the southern areas of the UK, for mechanical ventilation with heat recovery (MVHR as required by the German Passivhaus standard. It considers the comfort, air quality and energy impacts of MVHR versus natural ventilation and reviews the post-occupancy monitoring data of two flats in Cardiff designed to Passivhaus standards, one of which had been operated as a naturally ventilated building rather than with MVHR. The energy consumption of this free-running flat was significantly lower (36 kWh primary energy/m²a than the Passivhaus Planning Package modeling had predicted (93 kWh primary energy/m²a with no adverse effects on occupant comfort, air quality or excessive humidity, and advantages of lower capital cost and maintenance. The paper concludes that in climates with mild winters and cool summers the use of MVHR could be omitted without compromising comfort levels and achieving at least equivalent energy savings resulting from adopting the Passivhaus model and at a lower capital cost. This suggests the potential for a naturally ventilated, ultra-low energy model with lower capital investment requirements and lower disruption when applied to retrofit that would facilitate its mainstream adoption.

  15. An Attempt to Design a Naturally Ventilated Tower in Subtropical Climate of the Developing Country; Pakistan

    Science.gov (United States)

    Sohail, Maha

    2017-12-01

    A large proportion of the world's population resides in developing countries where there is a lack of rigorous studies in designing energy efficient buildings. This study is a step in designing a naturally ventilated high rise residential building in a tropical climatic context of the developing country, Pakistan. Karachi, the largest city of Pakistan, lies in the subtropical hot desert region with constant high temperature of average 32 °C throughout the summer and no particular winter season. The Design Builder software package is used to design a 25 storey high rise residential building relying primarily on natural ventilation. A final conceptual design is proposed after optimization of massing, geometry, orientation, and improved building envelope design including extensive shading devices in the form of trees. It has been observed that a reduction of 8 °C in indoor ambient temperature is possible to achieve with passive measures and use of night time ventilation. A fully naturally ventilated building can reduce the energy consumption for cooling and heating by 96 % compared to a building using air conditioning systems.

  16. Natural Frequency of Oscillating Gaseous Bubbles in Ventilated Cavitation

    Science.gov (United States)

    Zhang, Yu-Ning

    2017-07-01

    Not Available Supported by the National Natural Science Foundation of China under Grant No 51506051, the Fundamental Research Funds for the Central Universities under Grant No JB2015RCY04, and the Incubation Project for Young Talents of Chinese Society for Electrical Engineering under Grant No JLB-2016-68.

  17. Effects of window position on natural cross ventilation in vernacular ...

    African Journals Online (AJOL)

    Among the most effective architectures is vernacular architecture of Mazandaran whose incorporation in nature is so delicate that appears to be an essential part of it. Paying more attention to vernacular architecture and promoting it can be helpful in reducing energy consumption. Increasing use of fossil fuels in heating and ...

  18. CFD model of air movement in ventilated facade: comparison between natural and forced air flow

    Energy Technology Data Exchange (ETDEWEB)

    Mora Perez, Miguel; Lopez Patino, Gonzalo; Lopez Jimenez, P. Amparo [Hydraulic and Environmental Engineering Department, Universitat Politècnica de Valencia (Spain)

    2013-07-01

    This study describes computational fluid dynamics (CFD) modeling of ventilated facade. Ventilated facades are normal facade but it has an extra channel between the concrete wall and the (double skin) facade. Several studies found in the literature are carried out with CFD simulations about the behavior of the thermodynamic phenomena of the double skin facades systems. These studies conclude that the presence of the air gap in the ventilated facade affects the temperature in the building skin, causing a cooling effect, at least in low-rise buildings. One of the most important factors affecting the thermal effects of ventilated facades is the wind velocity. In this contribution, a CFD analysis applied on two different velocity assumptions for air movement in the air gap of a ventilated facade is presented. A comparison is proposed considering natural wind induced velocity with forced fan induced velocity in the gap. Finally, comparing temperatures in the building skin, the differences between both solutions are described determining that, related to the considered boundary conditions, there is a maximum height in which the thermal effect of the induced flow is significantly observed.

  19. Computational Fluid Dynamics Modeling to Improve Natural Flow Rate and Sweet Pepper Productivity in Greenhouse

    Directory of Open Access Journals (Sweden)

    W. Limtrakarn

    2012-01-01

    Full Text Available Natural flow rate and sweet peppers productivity in tropical greenhouse are improved by CFD simulation is the main objective of this research work. Most of the greenhouse types today are in the arch shape. To develop an improved greenhouse structure for the region, the arch type was built and used as the control model. Mae Sar Mai agriculture research station under the royal project foundation was selected as the field test site. Temperature sensors with data logger were installed to monitor variation of temperature inside the greenhouse. The measured temperature data were used as the boundary conditions for the CFD analysis. A new greenhouse model with two-step roof shape was designed and the air flow behavior was simulated by using CFD. Regarding CFD results the air flow rate of the new model is about 39% higher than that of old model. The maximum temperature of the new model is lower than that of the old one. The sweet paper growths in both greenhouse models were measured and compared. Results show that the new model obtains 4°C lower maximum temperature in day time, 97% in number and 90% in weight higher the first grade pepper productivity than the old one.

  20. The enhanced greenhouse signal versus natural variations in observed climate time series: a statistical approach

    Energy Technology Data Exchange (ETDEWEB)

    Schoenwiese, C D [J.W. Goethe Univ., Frankfurt (Germany). Inst. for Meteorology and Geophysics

    1996-12-31

    It is a well-known fact that human activities lead to an atmospheric concentration increase of some IR-active trace gases (greenhouse gases GHG) and that this influence enhances the `greenhouse effect`. However, there are major quantitative and regional uncertainties in the related climate model projections and the observational data reflect the whole complex of both anthropogenic and natural forcing of the climate system. This contribution aims at the separation of the anthropogenic enhanced greenhouse signal in observed global surface air temperature data versus other forcing using statistical methods such as multiple (multiforced) regressions and neural networks. The competitive natural forcing considered are volcanic and solar activity, in addition the ENSO (El Nino/Southern Oscillation) mechanism. This analysis will be extended also to the NAO (North Atlantic Oscillation) and anthropogenic sulfate formation in the troposphere

  1. The enhanced greenhouse signal versus natural variations in observed climate time series: a statistical approach

    Energy Technology Data Exchange (ETDEWEB)

    Schoenwiese, C.D. [J.W. Goethe Univ., Frankfurt (Germany). Inst. for Meteorology and Geophysics

    1995-12-31

    It is a well-known fact that human activities lead to an atmospheric concentration increase of some IR-active trace gases (greenhouse gases GHG) and that this influence enhances the `greenhouse effect`. However, there are major quantitative and regional uncertainties in the related climate model projections and the observational data reflect the whole complex of both anthropogenic and natural forcing of the climate system. This contribution aims at the separation of the anthropogenic enhanced greenhouse signal in observed global surface air temperature data versus other forcing using statistical methods such as multiple (multiforced) regressions and neural networks. The competitive natural forcing considered are volcanic and solar activity, in addition the ENSO (El Nino/Southern Oscillation) mechanism. This analysis will be extended also to the NAO (North Atlantic Oscillation) and anthropogenic sulfate formation in the troposphere

  2. Simulation comparison between natural and hybrid ventilation by fans at night time for severe hot climate (Aswan, Egypt)

    Energy Technology Data Exchange (ETDEWEB)

    Rizk, A. [Department of Architectural Engineering, Faculty of Engineering, Tanta University, Tanta (Egypt); El-Deberky, A. [Department of Architecture, Faculty of Fine Arts, Minya University, Minya (Egypt); Guirguis, N. M. [Housing and Building Research Center, Cairo (Egypt)

    2010-07-01

    During the summer in Aswan, Egypt, indoor temperatures rise to a level exceeding thermal comfort. Due to the lag time of the building's envelope, temperature at night is higher inside than outside during the overheated period. The aim of this paper is to assess the effectiveness of ceiling and wall falls in lowering indoor air temperature at night. Computer simulations were carried out with ANSYS FLOTRAN computational fluid dynamic on a single room; 3 models were studied: natural ventilation, hybrid ventilation with a wall fan and hybrid ventilation with a ceiling fan. Results showed that hybrid ventilation fan is more effective in decreasing the temperature than natural cross ventilation alone and it was found that a wall fan is better than a ceiling fan. This study demonstrated that using hybrid ventilation with a side fan is the best option to reduce the air temperature in a room in Aswan, Egypt.

  3. Measurement of Air Flow Rate in a Naturally Ventilated Double Skin Facade

    DEFF Research Database (Denmark)

    Kalyanova, Olena; Jensen, Rasmus Lund; Heiselberg, Per

    2007-01-01

    Air flow rate in a naturally ventilated space is extremely difficult to measure due to the stochastic nature of wind, and as a consequence non-uniform and dynamic flow conditions. This paper describes three different methods to measure the air flow in a full-scale outdoor test facility...... with a naturally ventilated double skin façade. In the first method, the air flow in the cavity is estimated on the basis of six measured velocity profiles. The second method is represented by constant injection of tracer gas and in the third method a measured relation in the laboratory is used to estimate...... the flow rate on the basis of continues measurement of the pressure difference between the surface pressure at the opening and inside pressure of the double skin façade. Although all three measurement methods are difficult to use under such dynamic air flow conditions, two of them show reasonable agreement...

  4. Greenhouse gas and energy analysis of substitute natural gas from biomass for space heat

    Energy Technology Data Exchange (ETDEWEB)

    Pucker, J.; Jungmeier, G. [JOANNEUM RESEARCH Forschungsgesellschaft mbH, RESOURCES - Institute for Water, Energy and Sustainability, Steyrergasse 17, 8010 Graz (Austria); Zwart, R. [Energy Research Centre of The Netherlands (ECN), Westerduinweg 3, 1755 LE Petten (Netherlands)

    2012-03-15

    In this paper, the greenhouse gas and energy balances of the production and use for space heating of substitute natural gas from biomass (bio-SNG) for space heat are analysed. These balances are compared to the use of natural gas and solid biomass as wood chips to provide the same service. The reduction of the greenhouse gas emissions (CO{sub 2}-eq.) - carbon dioxide, methane and nitrous oxide - and of the fossil primary energy use is investigated in a life cycle assessment (LCA). This assessment was performed for nine systems for bio-SNG; three types of gasification technologies (O{sub 2}-blown entrained flow, O{sub 2}-blown circulating fluidised bed and air-steam indirect gasification) with three different types of feedstock (forest residues, miscanthus and short rotation forestry). The greenhouse gas analysis shows that forest residues using the air-steam indirect gasification technology result in the lowest greenhouse gas emissions (in CO{sub 2}-eq. 32 kg MWh{sup -1} of heat output). This combination results in 80% reduction of greenhouse gas emissions when compared to natural gas and a 29% reduction of greenhouse gases if the forest residues were converted to wood chips and combusted. The gasification technologies O{sub 2}-blown entrained flow and O{sub 2}-blown circulating fluidised bed gasification have higher greenhouse gas emissions that range between in CO{sub 2}-eq. 41 to 75 kg MWh{sup -1} of heat output depending on the feedstock. When comparing feedstocks in the bio-SNG systems, miscanthus had the highest greenhouse gas emissions bio-SNG systems producing in CO2-eq. 57-75 kg MWh{sup -1} of heat output. Energy analysis shows that the total primary energy use is higher for bio-SNG systems (1.59-2.13 MWh MWh{sup -1} of heat output) than for the reference systems (in 1.37-1.51 MWh MWh{sup -1} of heat output). However, with bio-SNG the fossil primary energy consumption is reduced compared to natural gas. For example, fossil primary energy use is reduced by

  5. Natural Ventilation Effectiveness of Round Wall-Mounted Vent Caps in Residential Kitchens

    Directory of Open Access Journals (Sweden)

    Yi-Pin Lin

    2018-05-01

    Full Text Available This study explores the effect of different numbers of wall-mounted vent caps and their installation locations on the indoor air environment in residential kitchens, for which limited information is available. Wind tunnel tests were performed to study the induced ventilation rates of a vent cap, and the impact of vent caps on the natural ventilation efficiency in residential kitchens was examined using computational fluid dynamics (CFD numerical simulations. The results were then applied to determine the appropriate quantity of vent caps and their proper installation location. The wind tunnel test results indicated that outdoor winds with speeds of 0–6 m/s that flow parallel to the wall with a vent cap induce indoor air to exit through the cap with ventilation rates of 0–20 m3/h; when the wind blows perpendicular to the wall, outdoor air with 0–31.9 m3/h flows indoors. CFD numerical simulations showed that the installation of kitchen vent caps can reduce the average carbon monoxide concentration in the cook’s breathing zone. A sufficient quantity of vent caps and the proper installation location are required to ensure the natural ventilation effectiveness of wall-mounted vent caps.

  6. Buoyancy and Pressure Driven Flow of Hot Gases in Vertical Shafts with Natural and Forced Ventilation

    Science.gov (United States)

    Tamm, Gunnar; Jaluria, Yogesh

    2003-11-01

    An experimental investigation has been carried out on the buoyancy and pressure induced flow of hot gases in vertical shafts, in order to simulate the propagation of combustion products in elevator shafts due to fire in multilevel buildings. Various geometrical configurations are studied, with regard to natural and forced ventilation imposed at the top or bottom of the vertical shaft. The aspect ratio is taken at a fixed value of 6 and the inflow conditions for the hot gases, at a vent near the bottom, are varied in terms of the Reynolds and Grashof numbers. Temperature measurements within the shaft allow a detailed study of the steady state thermal fields, from which optimal means for smoke alleviation in high-rise building fires may be developed. Flow visualization is also used to study the flow characteristics. The results obtained indicate a wall plume as the primary transport mechanism. Flow recirculation dominates at high Grashof number flows, while increased Reynolds numbers gives rise to greater mixing in the shaft. The development and stability of the flow and its effect on the spread of smoke and hot gases are assessed for the different shaft configurations and inlet conditions. It is found that the fastest smoke removal and lowest shaft temperatures occur for a configuration with natural ventilation at the top and forced ventilation up from the shaft bottom. It is also shown that forced ventilation can be used to arrest smoke spread, as well as to dilute the effects of the fire.

  7. Transient natural ventilation of a room with a distributed heat source

    Science.gov (United States)

    Fitzgerald, Shaun D.; Woods, Andrew W.

    We report on an experimental and theoretical study of the transient flows which develop as a naturally ventilated room adjusts from one temperature to another. We focus on a room heated from below by a uniform heat source, with both high- and low-level ventilation openings. Depending on the initial temperature of the room relative to (i) the final equilibrium temperature and (ii) the exterior temperature, three different modes of ventilation may develop. First, if the room temperature lies between the exterior and the equilibrium temperature, the interior remains well-mixed and gradually heats up to the equilibrium temperature. Secondly, if the room is initially warmer than the equilibrium temperature, then a thermal stratification develops in which the upper layer of originally hot air is displaced upwards by a lower layer of relatively cool inflowing air. At the interface, some mixing occurs owing to the effects of penetrative convection. Thirdly, if the room is initially cooler than the exterior, then on opening the vents, the original air is displaced downwards and a layer of ambient air deepens from above. As this lower layer drains, it is eventually heated to the ambient temperature, and is then able to mix into the overlying layer of external air, and the room becomes well-mixed. For each case, we present new laboratory experiments and compare these with some new quantitative models of the transient flows. We conclude by considering the implications of our work for natural ventilation of large auditoria.

  8. Approaches to conserving natural enemy populations in greenhouse crops: current methods and future prospects

    NARCIS (Netherlands)

    Messelink, G.J.; Bennison, J.; Alomar, O.; Ingegno, B.L.; Tavella, L.; Shipp, L.; Palevsky, E.; Wäckers, F.L.

    2014-01-01

    Biological pest control in greenhouse crops is usually based on periodical releases of mass-produced natural enemies, and this method has been successfully applied for decades. However, in some cases there are shortcomings in pest control efficacy, which often can be attributed to the poor

  9. Continuous monitoring of natural ventilation pressure at the Waste Isolation Pilot Plant

    International Nuclear Information System (INIS)

    Loomis, I.M.; Wallace, K.G.

    1993-01-01

    The Waste Isolation Pilot Plant (WIPP) is a US Department of Energy research and development facility designed to demonstrate the permanent, safe disposal of US defense-generated transuranic waste. The waste storage horizon is 655 m (2150 ft) below surface in bedded salt. To date the WIPP project has not emplaced any waste. There are three intake shafts used to supply air to the underground. All air is exhausted through a single return shaft. The total design airflow during normal operations is 200 m 3 /s (424,000 cfm). The ventilation system is designed to provide separate air splits to construction, experimental, and storage activities. Separation is achieved by isolating the storage circuit from the construction or experimental circuits with bulkheads. Any air leakage must be towards the storage area of the facility. Field studies have shown that the pressure differential necessary to maintain the correct leakage direction is susceptible to the effects of natural ventilation; therefore, extensive studies and analyses have been conducted to quantify the natural ventilation effects on the WIPP underground airflow system. A component of this work is a monitoring system designed to measure the air properties necessary for calculation of the natural ventilation pressure (NVP). This monitoring system consists of measuring dry bulb temperature, relative humidity, and barometric pressure at strategic location on surface and underground. The psychometric parameters of the air are measured every fifteen minutes. From these data, trends can be determined showing the impact of NVP on the ventilation system during diurnal variations in surface climate. Both summer and winter conditions have been studied. To the author's knowledge this is the first reported instance of automatic and continuous production of time and temperature variant NVPs. This paper describes the results of the initial monitoring study

  10. Roles of sunlight and natural ventilation for controlling infection: historical and current perspectives.

    Science.gov (United States)

    Hobday, R A; Dancer, S J

    2013-08-01

    Infections caught in buildings are a major global cause of sickness and mortality. Understanding how infections spread is pivotal to public health yet current knowledge of indoor transmission remains poor. To review the roles of natural ventilation and sunlight for controlling infection within healthcare environments. Comprehensive literature search was performed, using electronic and library databases to retrieve English language papers combining infection; risk; pathogen; and mention of ventilation; fresh air; and sunlight. Foreign language articles with English translation were included, with no limit imposed on publication date. In the past, hospitals were designed with south-facing glazing, cross-ventilation and high ceilings because fresh air and sunlight were thought to reduce infection risk. Historical and recent studies suggest that natural ventilation offers protection from transmission of airborne pathogens. Particle size, dispersal characteristics and transmission risk require more work to justify infection control practices concerning airborne pathogens. Sunlight boosts resistance to infection, with older studies suggesting potential roles for surface decontamination. Current knowledge of indoor transmission of pathogens is inadequate, partly due to lack of agreed definitions for particle types and mechanisms of spread. There is recent evidence to support historical data on the effects of natural ventilation but virtually none for sunlight. Modern practice of designing healthcare buildings for comfort favours pathogen persistence. As the number of effective antimicrobial agents declines, further work is required to clarify absolute risks from airborne pathogens along with any potential benefits from additional fresh air and sunlight. Copyright © 2013 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  11. Energy saving potential of natural ventilation in China: The impact of ambient air pollution

    International Nuclear Information System (INIS)

    Tong, Zheming; Chen, Yujiao; Malkawi, Ali; Liu, Zhu; Freeman, Richard B.

    2016-01-01

    Highlights: • Natural ventilation potential is affected largely by ambient air pollution in China. • NV hours of 76 Chinese cities based on weather and ambient air quality are estimated. • Cooling energy savings and carbon reductions of 35 major Chinese cities are estimated. • 8–78% of the cooling energy usage can be potentially reduced by NV. • Our findings provide guidelines to improve energy policies in China. - Abstract: Natural ventilation (NV) is a key sustainable solution for reducing the energy use in buildings, improving thermal comfort, and maintaining a healthy indoor environment. However, the energy savings and environmental benefits are affected greatly by ambient air pollution in China. Here we estimate the NV potential of all major Chinese cities based on weather, ambient air quality, building configuration, and newly constructed square footage of office buildings in the year of 2015. In general, little NV potential is observed in northern China during the winter and southern China during the summer. Kunming located in the Southwest China is the most weather-favorable city for natural ventilation, and reveals almost no loss due to air pollution. Building Energy Simulation (BES) is conducted to estimate the energy savings of natural ventilation in which ambient air pollution and total square footage at each city must be taken into account. Beijing, the capital city, displays limited per-square-meter saving potential due to the unfavorable weather and air quality for natural ventilation, but its largest total square footage of office buildings makes it become the city with the greatest energy saving opportunity in China. Our analysis shows that the aggregated energy savings potential of office buildings at 35 major Chinese cities is 112 GWh in 2015, even after allowing for a 43 GWh loss due to China’s serious air pollution issue especially in North China. 8–78% of the cooling energy consumption can be potentially reduced by natural

  12. Spatial variability of mixing ratios of ammonia and tracer gases in a naturally ventilated dairy cow barn

    NARCIS (Netherlands)

    Mendes, Luciano B.; Edouard, Nadège; Ogink, Nico W.M.; Dooren, van Hendrik Jan C.; Fátima F. TinÔco, de Ilda; Mosquera Losada, Julio

    2015-01-01

    The use of the tracer gas ratio method to estimate emissions from naturally ventilated (NV) livestock barns excludes the need of monitoring ventilation rates. However, it requires accurate measurement of tracer release rate (QT) and a representative estimate of the mixing ratio between

  13. Influence of the urban environment on the effectiveness of natural night-ventilation of an office building

    NARCIS (Netherlands)

    Ramponi, R.; Gaetani, I.; Angelotti, A.

    2014-01-01

    The effectiveness of natural night-ventilation in the urban environment depends on local climate characteristics, but also on solar shading and wind shielding effects of the surrounding buildings. However, the impact of the latter factors on the effectiveness of night-ventilation is often

  14. Energy Performance of a Novel System Combining Natural Ventilation with Diffuse Ceiling Inlet and Thermally Activated Building Systems (TABS)

    DEFF Research Database (Denmark)

    Yu, Tao

    and thermally activated building systems (TABS) for cooling and ventilation in future Danish office buildings. The new solution would have the special potential of using natural ventilation all year round even in the extremely cold seasons without any draught risk. The main focuses of this study are the energy...

  15. Sonic anemometry measurements to determine airflow patterns in multi-tunnel greenhouse

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, A.; Valera, D. L.; Molina-aiz, F. D.; Pena, A.

    2012-11-01

    The present work describes a methodology for studying natural ventilation in Mediterranean greenhouses using sonic anemometry. The experimental work took place in the three-span greenhouse located at the agricultural research farm belonging to the University of Almeria. This methodology has allowed us to obtain patterns of natural ventilation of the experimental greenhouse under the most common wind regimes for this region. It has also enabled us to describe how the wind and thermal effects interact in the natural ventilation of the greenhouse, as well as to detect deficiencies in the ventilation of the greenhouse, caused by the barrier effect of the adjacent greenhouse (imply a mean reduction in air velocity close to the greenhouse when facing windward of 98% for u, 63% for u, and more importantly 88% for ux, the component of air velocity that is perpendicular to the side vent). Their knowledge allows us to improve the current control algorithms that manage the movement of the vents. In this work we make a series of proposals that could substantially improve the natural ventilation of the experimental greenhouse. For instance, install vents equipped with ailerons which guide the air inside, or with vents in which the screen is not placed directly over the side surface of the greenhouse. A different proposal is to prolong the opening of the side vents down to the soil, thus fomenting the entrance of air at crop level. (Author) 34 refs.

  16. Prediction of the diffuse-field transmission loss of interior natural-ventilation openings and silencers.

    Science.gov (United States)

    Bibby, Chris; Hodgson, Murray

    2017-01-01

    The work reported here, part of a study on the performance and optimal design of interior natural-ventilation openings and silencers ("ventilators"), discusses the prediction of the acoustical performance of such ventilators, and the factors that affect it. A wave-based numerical approach-the finite-element method (FEM)-is applied. The development of a FEM technique for the prediction of ventilator diffuse-field transmission loss is presented. Model convergence is studied with respect to mesh, frequency-sampling and diffuse-field convergence. The modeling technique is validated by way of predictions and the comparison of them to analytical and experimental results. The transmission-loss performance of crosstalk silencers of four shapes, and the factors that affect it, are predicted and discussed. Performance increases with flow-path length for all silencer types. Adding elbows significantly increases high-frequency transmission loss, but does not increase overall silencer performance which is controlled by low-to-mid-frequency transmission loss.

  17. Augmenting natural ventilation using solar heat and free cool energy for residential buildings

    Directory of Open Access Journals (Sweden)

    N. B. Geetha

    2014-03-01

    Full Text Available In many urban buildings ventilation is not sufficient that will increase the temperature and also create unhealthy atmosphere inside the room. In such buildings artificially induced ventilation through freely available energy promote comfort conditions by reducing the temperature by 2 to 3°C and also creating good circulation of fresh air inside the room. In the present work the concept of improving the ventilation by excess hot energy available during summer days from the solar flat plate collector and by storing cool energy available during the early morning hour in the Phase Change Material (PCM based storage system is attempted. An experimental setup is made to study the effect of improvement in natural ventilation and the results are reported. A visible reduction in temperature is observed through circulation of air from the bottom side of the room to the roof of the house using the stored hot and cool energy. A CFD analysis is also carried out using ANSYS-CFX software to simulate and evaluate the mass flow of air at the inlet and at the selected RTD location by matching the transient temperature profile of the simulated result with the experimental results at the selected RTD location.

  18. Occupants’ Utilization of Natural Ventilation: A Study of Selected Terrace House Designs in Hot-humid Climate

    Directory of Open Access Journals (Sweden)

    Ibiyeye AI

    2015-05-01

    Full Text Available With increased time spent indoors and demand for enhanced comfort levels, energy consumption in homes is rising mostly for cooling, particularly in hot-humid regions. Natural ventilation is seen as an alternative to mechanical cooling as it is totally independent on energy and has been reported to be of high potential. However, little information is available on the utilization of natural ventilation in individual living spaces in different house designs. Therefore, this paper aims to investigate occupants’ utilization of natural ventilation in living spaces under different terrace house designs in hot-humid climate and also the relationship between the openings and occupants’ satisfaction with natural ventilation. Five (5 different terrace house types in Putrajaya, Malaysia with different opening design characteristics were selected for the study. A total of 298 households from these house types were surveyed and results show that occupants mostly open their windows during the daytime to capture breeze from outside despite the fact that they owned air-conditioners. In terms of occupants’ level of satisfaction with indoor ventilation when utilizing natural ventilation, majority rated neither satisfied nor unsatisfied. Further regression analysis reveals that this level of satisfaction is significantly related to opening sizes that are in accordance with the law, duration of opening windows and AC ownership. Findings from this study will shed more light on behavioural pattern of occupants of residential buildings towards natural ventilation provisions and highlight the importance of conforming to the law governing them.

  19. Evaluation of naturally ventilated dairy barn management by a thermographic method

    Czech Academy of Sciences Publication Activity Database

    Knížková, I.; Kunc, P.; Koubková, M.; Flusser, Jan; Doležal, O.

    2002-01-01

    Roč. 77, 2/3 (2002), s. 349-353 ISSN 0301-6226 R&D Projects: GA ČR GA523/99/1489 Institutional research plan: CEZ:AV0Z1075907 Keywords : natural ventilation * dairy cattle * body surface temperature Subject RIV: GH - Livestock Nutrition Impact factor: 1.117, year: 2002 http://library.utia.cas.cz/prace/20020202.pdf

  20. Characteristics of Buoyant Flow from Open Windows in Naturally Ventilated Rooms

    DEFF Research Database (Denmark)

    Nielsen, Peter V.; Dam, Henrik; Sørensen, Lars C.

    An important element in the natural ventilation design procedure is the flow-pressure characteristics of a window with a -given opening area. The flow in the room is another important element that is often ignored in the design phase due to lack of relevant information on the air movement....... This paper shows the outcome of experiments with the room air distribution. The results show that the velocity distribution in the occupied zone can be described by a semiempirical model....

  1. An analysis of natural ventilation techniques to achieve indoor comfort in Wal-Mart express

    Science.gov (United States)

    O'Dea, Shona

    Despite global efforts to reduce world fossil fuel dependency the world still obtains 81% of its energy from fossil fuels (IEA,2009). Modern renewable alternatives have been around since the mid twentieth century these alternatives have not been integrated into electrical grid systems at the exponential rate required to eradicate fossil fuels dependency. The problem, world energy demand, is too large to be satisfied by anything other than the energy-dense fossil fuels used today. We must change our energy intensive processes in order to conserve energy and hence reduce the demands that alternatives must satisfy. This research aims to identify sustainable design opportunities through the application of innovative technologies for the largest retailer in the US with the view that a viable conservative design measure could be applied to the store model, which is replicated across the country, causing a cumulative and hence larger impact on the company energy consumption as a whole. This paper will present the literature available on the 'big box' industry and Wal-Mart, comfort, natural ventilation and building simulation software and then perform an analysis into the viability of naturally ventilating the Wal-Mart Express sales zone using Monodraught natural ventilation windcatcher products

  2. Contribution of natural ventilation in a double skin envelope to heating load reduction in winter

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yu-Min; Sohn, Jang-Yeul [Department of Architectural Engineering, Hanyang University, Seoul (Korea); Kim, Soo-Young [Department of Housing and Interior Design, Yonsei University, Seoul (Korea); Shin, Sung-Woo [Department of Architectural Engineering, Hanyang University, Ansan (Korea)

    2009-11-15

    This study examined the contribution of a double skin envelope (DSE) to the heating energy savings brought about by natural ventilation in office buildings. A DSE was applied to the east- and west-facing walls on an actual three-floor building. Field measurements and computer simulations were performed in winter. The results implied that the DSE on the west-facing wall contributed to energy savings when natural ventilation was supplied from the cavity to the indoor space. The DSE facing east was not recommended for energy savings by natural ventilation because of its smaller exposure to solar irradiance. Multiple linear regression models were developed based on field measurements to predict the temperature variation in the cavities, and effective control logics will be discussed in a future study. Of all variables, the outdoor air temperature was the most significant factor influencing the air temperature in the cavity. Computer simulation indicated that the air in the cavity was heated to the required temperature without consuming additional energy when the ratio of the diffused irradiance to global irradiance was smaller than 0.69. The cavity in the DSE worked as a thermal buffer zone and contributed to reducing heating energy consumption by 14.71% in January. (author)

  3. Experimental and CFD evidence of multiple solutions in a naturally ventilated building.

    Science.gov (United States)

    Heiselberg, P; Li, Y; Andersen, A; Bjerre, M; Chen, Z

    2004-02-01

    This paper considers the existence of multiple solutions to natural ventilation of a simple one-zone building, driven by combined thermal and opposing wind forces. The present analysis is an extension of an earlier analytical study of natural ventilation in a fully mixed building, and includes the effect of thermal stratification. Both computational and experimental investigations were carried out in parallel with an analytical investigation. When flow is dominated by thermal buoyancy, it was found experimentally that there is thermal stratification. When the flow is wind-dominated, the room is fully mixed. Results from all three methods have shown that the hysteresis phenomena exist. Under certain conditions, two different stable steady-state solutions are found to exist by all three methods for the same set of parameters. As shown by both the computational fluid dynamics (CFD) and experimental results, one of the solutions can shift to another when there is a sufficient perturbation. These results have probably provided the strongest evidence so far for the conclusion that multiple states exist in natural ventilation of simple buildings. Different initial conditions in the CFD simulations led to different solutions, suggesting that caution must be taken when adopting the commonly used 'zero initialization'.

  4. Investigating the adaptive model of thermal comfort for naturally ventilated school buildings in Taiwan

    Science.gov (United States)

    Hwang, Ruey-Lung; Lin, Tzu-Ping; Chen, Chen-Peng; Kuo, Nai-Jung

    2009-03-01

    Divergence in the acceptability to people in different regions of naturally ventilated thermal environments raises a concern over the extent to which the ASHRAE Standard 55 may be applied as a universal criterion of thermal comfort. In this study, the ASHRAE 55 adaptive model of thermal comfort was investigated for its applicability to a hot and humid climate through a long-term field survey performed in central Taiwan among local students attending 14 elementary and high schools during September to January. Adaptive behaviors, thermal neutrality, and thermal comfort zones are explored. A probit analysis of thermal acceptability responses from students was performed in place of the conventional linear regression of thermal sensation votes against operative temperature to investigate the limits of comfort zones for 90% and 80% acceptability; the corresponding comfort zones were found to occur at 20.1-28.4°C and 17.6-30.0°C, respectively. In comparison with the yearly comfort zones recommended by the adaptive model for naturally ventilated spaces in the ASHRAE Standard 55, those observed in this study differ in the lower limit for 80% acceptability, with the observed level being 1.7°C lower than the ASHRAE-recommended value. These findings can be generalized to the population of school children, thus providing information that can supplement ASHRAE Standard 55 in evaluating the thermal performance of naturally ventilated school buildings, particularly in hot-humid areas such as Taiwan.

  5. Application of fuzzy control in naturally ventilated buildings for summer conditions

    Energy Technology Data Exchange (ETDEWEB)

    Eftekhari, M.M. [Loughborough University (United Kingdom). Department of Civil and Building Engineering; Marjanovic, L.D. [University of Belgrade (Yugoslavia). Faculty of Mechanical Engineering

    2003-08-01

    The objective of this work is to develop a fuzzy controller for naturally ventilated buildings. Approximate reasoning has proven to be in many cases more successful control strategy than classically designed controlled scheme. In this paper the process of designing a supervisory control to provide thermal comfort and adequate air distribution inside a single-sided naturally ventilated test room is described. The controller is based on fuzzy logic reasoning and sets of linguistic rules in forms of IF-THEN rules are used. The inputs to the controller are the outside wind velocity, direction, outside and inside temperatures. The output is the position of the opening. A selection of membership functions for input and output variables are described and analysed. The control strategy consisting of the expert rules is then validated using experimental data from a naturally ventilated test room. The test room is located in a sheltered area and air flow inside the room, the air pressures and velocities across the openings together with indoor air temperature and velocity at four locations and six different levels were measured. Validation of the controller is performed in the test room by measuring the air distribution and thermal comfort inside the room with no control action. These data are then compared to the air temperature and velocity with the controller in action. The initial results are presented here, which shows that the controller is capable of providing better thermal comfort inside the room. (author)

  6. The integration of engineering and architecture: A perspective on natural ventilation for the new San Francisco Federal Building

    International Nuclear Information System (INIS)

    McConahey, Erin; Haves, Philip; Christ, Tim

    2002-01-01

    A description of the in-progress design of a new Federal Office Building for San Francisco is used to illustrate a number of issues arising in the design of large, naturally ventilated office buildings. These issues include the need for an integrated approach to design involving the architects, mechanical and structural engineers, lighting designers and specialist simulation modelers. In particular, the use of natural ventilation, and the avoidance of air-conditioning, depends on the high degree of exposed thermal mass made possible by the structural scheme and by the minimization of solar heat gains while maintaining the good daylighting that results from optimization of the facade. Another issue was the need for a radical change in interior space planning in order to enhance the natural ventilation; all the individual enclosed offices are located along the central spine of each floorplate rather than at the perimeter. The role of integration in deterring the undermining of the design through value engineering is discussed. The comfort criteria for the building were established based on the recent extension to the ASHRAE comfort standard based on the adaptive model for naturally ventilated buildings. The building energy simulation program EnergyPlus was used to compare the performance of different natural ventilation strategies. The results indicate that, in the San Francisco climate, wind-driven ventilation provides sufficient nocturnal cooling to maintain comfortable conditions and that external chimneys do not provide significant additional ventilation at times when it when it would be beneficial

  7. Greenhouse gas and energy analysis of substitute natural gas from biomass for space heat

    International Nuclear Information System (INIS)

    Pucker, Johanna; Zwart, Robin; Jungmeier, Gerfried

    2012-01-01

    In this paper, the greenhouse gas and energy balances of the production and use for space heating of substitute natural gas from biomass (bio-SNG) for space heat are analysed. These balances are compared to the use of natural gas and solid biomass as wood chips to provide the same service. The reduction of the greenhouse gas emissions (CO 2 -eq.) – carbon dioxide, methane and nitrous oxide – and of the fossil primary energy use is investigated in a life cycle assessment (LCA). This assessment was performed for nine systems for bio-SNG; three types of gasification technologies (O 2 -blown entrained flow, O 2 -blown circulating fluidised bed and air–steam indirect gasification) with three different types of feedstock (forest residues, miscanthus and short rotation forestry). The greenhouse gas analysis shows that forest residues using the air–steam indirect gasification technology result in the lowest greenhouse gas emissions (in CO 2 -eq. 32 kg MWh −1 of heat output). This combination results in 80% reduction of greenhouse gas emissions when compared to natural gas and a 29% reduction of greenhouse gases if the forest residues were converted to wood chips and combusted. The gasification technologies O 2 -blown entrained flow and O 2 -blown circulating fluidised bed gasification have higher greenhouse gas emissions that range between in CO 2 -eq. 41 to 75 kg MWh −1 of heat output depending on the feedstock. When comparing feedstocks in the bio-SNG systems, miscanthus had the highest greenhouse gas emissions bio-SNG systems producing in CO 2 -eq. 57–75 kg MWh −1 of heat output. Energy analysis shows that the total primary energy use is higher for bio-SNG systems (1.59–2.13 MWh MWh −1 of heat output) than for the reference systems (in 1.37–1.51 MWh MWh −1 of heat output). However, with bio-SNG the fossil primary energy consumption is reduced compared to natural gas. For example, fossil primary energy use is reduced by 92% when air

  8. Numerical Simulation of Air Temperature and Velocity in a Naturally Ventilated Office

    Directory of Open Access Journals (Sweden)

    S. Shodiya

    2017-04-01

    Full Text Available This paper presents a numerical simulation of air velocity and air temperature distribution in an office room of Computer Engineering Department of University of Maiduguri which is naturally ventilated. The office room under investigation with the dimension 5 m × 5 m × 4 m has a door in the East direction, and two windows, one in the East direction and the other in the South direction. For cost effectiveness, numerical solutions of steady-state airflow and heat transfer were done using a complete two-dimensional model. The results showed that the windows and the door could not undertake indoor heat load that can make the occupants to be thermally comfortable. In activity area where people sit and stand, the air velocity is moderate, this is about 0.98 m/s on the average. In addition, the temperature in this area is relatively high of about 302 K (29 °C on the average. Based on the American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE standard for comfort environment in summer (air temperature: 293 – 299 K (20 – 26 °C; air velocity: 0.5 – 0.8 m/s, the natural ventilation for the office room cannot give a thermal comfort for the inhabitant of the room. However, a window, if installed opposite the door could improve the ventilation of the office.

  9. A preliminary investigation of indoor air quality in a naturally ventilated house

    International Nuclear Information System (INIS)

    Shahrani, S.; Ahmed, A.Z.; Abdul Rahman, S.

    2006-01-01

    Continuous monitoring of indoor air quality was conducted in a naturally ventilated Malaysian house. CO 2 , CO, temperature and relative air humidity measurements were performed in the bathroom, bedroom, family room, kitchen and living room at 15-minute intervals over a 24-hour monitoring period. The measurement data were supplemented with time activity diaries detailing the occupants time of occupancy in each room, activities undertaken in each room and cooling and/or ventilation techniques used in each room. Indoor air quality was found to be generally satisfactory in all five rooms. However, levels of CO in the family room exceeded the USEPA, WHO and Singapore guidelines. Additionally, levels of relative humidity in the kitchen, living room and family room temperature in all five rooms exceeded the ASHRAE and Singapore guidelines, and suggest the like hood of condensation and mould growth

  10. Experimental research on the indoor temperature and humidity fields in radiant ceiling air-conditioning system under natural ventilation

    Science.gov (United States)

    Huang, Tao; Xiang, Yutong; Wang, Yonghong

    2017-05-01

    In this paper, the indoor temperature and humidity fields of the air in a metal ceiling radiant panel air conditioning system with fresh air under natural ventilation were researched. The temperature and humidity distributions at different height and different position were compared. Through the computation analysis of partial pressure of water vapor, the self-recovery characteristics of humidity after the natural ventilation was discussed.

  11. Pilot Greenhouse

    CERN Multimedia

    1983-01-01

    This pilot greenhouse was built in collaboration with the "Association des Maraichers" of Geneva in the frame of the study for making use of the heat rejected as warm water by CERN accelerators and experiments. Among other improvements, more automated and precise regulation systems for heating and ventilation were developed. See also 8305598X.

  12. Life-cycle greenhouse gas emissions of shale gas, natural gas, coal, and petroleum.

    Science.gov (United States)

    Burnham, Andrew; Han, Jeongwoo; Clark, Corrie E; Wang, Michael; Dunn, Jennifer B; Palou-Rivera, Ignasi

    2012-01-17

    The technologies and practices that have enabled the recent boom in shale gas production have also brought attention to the environmental impacts of its use. It has been debated whether the fugitive methane emissions during natural gas production and transmission outweigh the lower carbon dioxide emissions during combustion when compared to coal and petroleum. Using the current state of knowledge of methane emissions from shale gas, conventional natural gas, coal, and petroleum, we estimated up-to-date life-cycle greenhouse gas emissions. In addition, we developed distribution functions for key parameters in each pathway to examine uncertainty and identify data gaps such as methane emissions from shale gas well completions and conventional natural gas liquid unloadings that need to be further addressed. Our base case results show that shale gas life-cycle emissions are 6% lower than conventional natural gas, 23% lower than gasoline, and 33% lower than coal. However, the range in values for shale and conventional gas overlap, so there is a statistical uncertainty whether shale gas emissions are indeed lower than conventional gas. Moreover, this life-cycle analysis, among other work in this area, provides insight on critical stages that the natural gas industry and government agencies can work together on to reduce the greenhouse gas footprint of natural gas.

  13. Animal welfare in cross-ventilated, compost-bedded pack, and naturally ventilated dairy barns in the upper Midwest.

    Science.gov (United States)

    Lobeck, K M; Endres, M I; Shane, E M; Godden, S M; Fetrow, J

    2011-11-01

    The objective of this cohort study was to investigate animal welfare in 2 newer dairy housing options in the upper Midwest, cross-ventilated freestall barns (CV) and compost-bedded-pack barns (CB), compared with conventional, naturally ventilated freestall barns (NV). The study was conducted on 18 commercial dairy farms, 6 of each housing type, in Minnesota and eastern South Dakota. The primary breed in all farms was Holstein; 1 CV and 1 NV herd had approximately 30% Jersey-Holstein crossbreds. All freestall herds used sand for bedding. Farms were visited 4 times (once in each season) between January and November 2008, and approximately 93% of all animals in each pen were visually scored on each visit. Outcome-based measurements of welfare (locomotion, hock lesions, body condition score, hygiene, respiration rates, mortality, and mastitis prevalence) were collected on each farm. Lameness prevalence (proportion of cows with locomotion score ≥3 on a 1 to 5 scale, where 1=normal and 5=severely lame) in CB barns (4.4%) was lower than that in NV (15.9%) and CV (13.1%) barns. Lameness prevalence was similar between CV and NV barns. Hock lesion prevalence (proportion of cows with a lesion score ≥2 on a 1 to 3 scale, where 1=normal, 2=hair loss, and 3=swelling) was lower in CB barns (3.8%) than in CV (31.2%) and NV barns (23.9%). Hygiene scores (1 to 5 scale, where 1=clean and 5=very dirty) were higher for CB (3.18) than CV (2.83) and NV (2.77) barns, with no differences between CV and NV barns. Body condition scores, respiration rates, mastitis prevalence, culling, and mortality rates did not differ among housing systems. The CV and NV barns were evaluated using the cow comfort index (proportion of cows lying down in a stall divided by all animals touching a stall) and the stall usage index (proportion of cows lying divided by all animals in the pen not eating). The CV barns tended to have greater cow comfort index (85.9%) than the NV barns (81.4%) and had greater

  14. Study of natural convection heat transfer characteristics. (1) Influence of ventilation duct height

    International Nuclear Information System (INIS)

    Wakamatsu, Mitsuo; Iwaki, Chikako; Ikeda, Tatsumi; Morooka, Shinichi; Ikeda, Hiroshi; Nakada, Kotaro; Masaki, Yoshikazu

    2008-01-01

    Natural cooling system has been investigated in waste storage. It is important to evaluate the flow by natural draft enough to removal the decay heat from the waste. In this study, we carried out the fundamental experiment of ventilation duct height effect for natural convection on vertical cylindrical heater in atmospheric air. The scale of test facility is about 4m height with single heater. The heating value is varied in the range of 33-110W, where Rayleigh number is over 10 10 . Natural convection flow rate were calculated by measured velocity with thermo anemometer in the inlet duct. The temperature of the cylindrical heater wall and fluid were measured with thermocouples. It was found that the heat transfer coefficient difference between long duct and short duct is small in this experiment. (author)

  15. Radon-222 signatures of natural ventilation regimes in an underground quarry.

    Science.gov (United States)

    Perrier, Frédéric; Richon, Patrick; Crouzeix, Catherine; Morat, Pierre; Le Mouël, Jean Louis

    2004-01-01

    Radon-222 activity concentration has been monitored since 1999 in an underground limestone quarry located in Vincennes, near Paris, France. It is homogeneous in summer, with an average value of 1700 Bq m(-3), and varies from 730 to 1450 Bq m(-3) in winter, indicating natural ventilation with a rate ranging from 0.5 to 2.4 x 10(-6) s(-1) (0.04-0.22 day(-1)). This hypothesis is supported by measurements in the vertical access pit where, in winter, a turbulent air current produces a stable radon profile, smoothly decreasing from 700 Bq m(-3) at 20 m depth to 300 Bq m(-3) at surface. In summer, a thermal stratification is maintained in the pit, but the radon-222 concentration jumps repeatedly between 100 and 2000 Bq m(-3). These jumps are due to atmospheric pressure pumping, which induces ventilation in the quarry at a rate of about 0.1 x 10(-6) s(-1) (0.009 day(-1)). Radon-222 monitoring thus provides a dynamical characterisation of ventilation regimes, which is important for the assessment of the long-term evolution of underground systems.

  16. Numerical analysis of natural ventilation system in a studio apartment in Bangladesh

    Science.gov (United States)

    Kabir, K. M. Ariful; Hasan, Md. Rakibul; Khan, Md. Abdul Hakim

    2017-07-01

    The study of temperature and air flow for natural ventilation system has been investigated numerically. A finite element model for studio apartment was developed with the aim of achieving detail energy allocation in the real buildings during the transient process in the walls and internal air. A tool of computational fluid dynamics (CFD) is employed to assist the process. In the tropical regions most of the energy is consumed by the heating, cooling and ventilation appliances. Therefore, the optimize ventilation system will be a suitable and valid option for the saving of energy from the household sector to increase cooling performance and ensuring thermal comfort as well. A mathematical exploration is carried out on full scale dwelling and small scale model and indication is given on the relevance of such a comparison. Calculations are carried out with household heat sources for calm and windy period, but without any human. As expected, for windy periods, the wind is the main driving force behind the internal air flow. However, in calm periods for unsteady flow the internal airflow looks like more complexes through observation.

  17. Ammonia emissions from a naturally and a mechanically ventilated broiler house in Brazil

    Directory of Open Access Journals (Sweden)

    Luciano B. Mendes

    2014-11-01

    Full Text Available This study was conducted with the aim of monitoring NH3 emissions from a mechanically and a naturally ventilated broiler house (MVB and NVB, respectively and calculate their ammonia emission factors (fNH3. Bird stocking density was 13.5 and 11.1 birds m-2 for the MVB and NVB, respectively. The marketing age was 43 days and bedding consisted of dried coffee husks in its first time of use. Ventilation rates were calculated with the metabolic carbon dioxide mass balance method. Values of fNH3 were 0.32 ± 0.10 and 0.27 ± 0.07 g bird-1 d-1 for the MVB and NVB, respectively, and are in agreement to what was presented in other studies performed under similar conditions. The fNH3 estimated on yearly basis was 58 g bird-place-1 year-1. It was concluded that the different types of ventilation system between the studied broiler barns did not significantly affect emissions in the modeling process. The results obtained help providing reliable methodology for the determination of a solid database on NH3 emission factors for tropical conditions that can be used for future inventories, when performed in a sufficient number of barns that is representative for the Brazilian scenario.

  18. Effects of 17β-estradiol on emissions of greenhouse gases in simulative natural water body.

    Science.gov (United States)

    Ruan, Aidong; Zhao, Ying; Liu, Chenxiao; Zong, Fengjiao; Yu, Zhongbo

    2015-05-01

    Environmental estrogens are widely spread across the world and are increasingly thought of as serious contaminators. The present study looks at the influence of different concentrations of 17β-estradiol on greenhouse gas emissions (CO2 , CH4 , and N2 O) in simulated systems to explore the relationship between environmental estrogen-pollution and greenhouse gas emissions in natural water bodies. The present study finds that 17β-estradiol pollution in simulated systems has significant promoting effects on the emissions of CH4 and CO2 , although no significant effects on N2 O emissions. The present study indicates that 17β-estradiol has different effects on the different elements cycles; the mechanism of microbial ecology is under review. © 2015 SETAC.

  19. Natural ventilation reduces high TB transmission risk in traditional homes in rural KwaZulu-Natal, South Africa.

    Science.gov (United States)

    Lygizos, Melissa; Shenoi, Sheela V; Brooks, Ralph P; Bhushan, Ambika; Brust, James C M; Zelterman, Daniel; Deng, Yanhong; Northrup, Veronika; Moll, Anthony P; Friedland, Gerald H

    2013-07-01

    Transmission of drug susceptible and drug resistant TB occurs in health care facilities, and community and households settings, particularly in highly prevalent TB and HIV areas. There is a paucity of data regarding factors that may affect TB transmission risk in household settings. We evaluated air exchange and the impact of natural ventilation on estimated TB transmission risk in traditional Zulu homes in rural South Africa. We utilized a carbon dioxide decay technique to measure ventilation in air changes per hour (ACH). We evaluated predominant home types to determine factors affecting ACH and used the Wells-Riley equation to estimate TB transmission risk. Two hundred eighteen ventilation measurements were taken in 24 traditional homes. All had low ventilation at baseline when windows were closed (mean ACH = 3, SD = 3.0), with estimated TB transmission risk of 55.4% over a ten hour period of exposure to an infectious TB patient. There was significant improvement with opening windows and door, reaching a mean ACH of 20 (SD = 13.1, p ventilation conditions (windows/doors open) and window to volume ratio. Expanding ventilation increased the odds of achieving ≥12 ACH by 60-fold. There is high estimated risk of TB transmission in traditional homes of infectious TB patients in rural South Africa. Improving natural ventilation may decrease household TB transmission risk and, combined with other strategies, may enhance TB control efforts.

  20. Numerical investigations of buoyancy-driven natural ventilation in a simple three-storey atrium building and thermal comfort evaluation

    International Nuclear Information System (INIS)

    Hussain, Shafqat; Oosthuizen, Patrick H.

    2013-01-01

    The numerical investigations of buoyancy-driven natural ventilation and thermal comfort evaluation in a simple three-storey atrium building as a part of the passive ventilation strategy was undertaken using a validated Computational Fluid Dynamic (CFD) model. The Reynolds Averaged Navier–Stokes (RANS) modeling approach with the SST-k–ω turbulence model and the discrete transfer radiation model (DTRM) was used for the numerical investigations. The steady-state governing equations were solved using a commercial solver FLUENT©. Various flow situations of the buoyancy-driven natural ventilation in the building during day and night time were examined. The numerical results obtained for the airflow rates, airflow patterns and temperature distributions inside the building are presented in this paper. Using the numerical results, the well-known thermal comfort indices PMV (predicted mean vote) and PPD (predicted percentage of dissatisfied) were calculated for the evaluation of the thermal comfort conditions in the occupied regions of the building. It was noticed that thermal conditions prevailing in the occupied areas of the building as a result of using the buoyancy-driven ventilation were mostly in comfort zone. From the study of the night time ventilation, it was found that hot water (80 °C) circulation (heated by solar collectors during daytime) along the chimney walls during night time and heat sources present in the building can be useful in inducing night ventilation airflows in the building as a part of the passive ventilation strategy. -- Highlights: • A simple three-storey atrium building. • Numerical modeling of buoyancy-driven ventilation flow in the building. • Effect of solar intensity and geographical location on ventilation. • CFD predictions were used to calculate thermal comfort indices. • Evaluation of thermal comfort conditions for the occupants

  1. The greenhouse gas balance of Italy. An insight on managed and natural terrestrial ecosystems

    International Nuclear Information System (INIS)

    Valentini, Riccardo; Miglietta, Franco

    2015-01-01

    Comprehensively addresses the full greenhouse gases budget of the Italian landscape. Presents the results of the national project CARBOITALY. Provides new data and analyses in the framework of climate policies. The book addresses in a comprehensive way the full greenhouse gases budget of the Italian landscape, focusing on land use and terrestrial ecosystems. In recent years there has been a growing interest in the role of terrestrial ecosystems with regard to the carbon cycle and only recently a regional approach has been considered for its specificity in terms of new methodologies for observations and models and its relevance for national policies on mitigation and adaptation to climate changes. In terms of methods this book describes the role of flux networks and data-driven models, airborne regional measurements of fluxes and specific sectoral approaches related to important components of the human and natural landscapes. There is also a growing need on the part of institutions, agencies and policy stakeholders for new data and analyses enabling them to improve their national inventories of greenhouse gases and their compliance with the UNFCCC process. In this respect the data presented is a basis for a full carbon accounting and available to relevant stakeholders for improvements and/or verification of national inventories. The wealth of research information is the result of a national project, CARBOITALY, which involved 15 Italian institutions and several researchers to provide new data and analyses in the framework of climate policies.

  2. The greenhouse gas balance of Italy. An insight on managed and natural terrestrial ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Valentini, Riccardo [Tuscia Univ., Viterbo (Italy). Dept. for Innovation in Biological, Agro-Food and Forest System (DIBAF); Euro-Mediterranean Center on Climate Changes (CMCC), Viterbo (Italy). Impacts on Agriculture, Forest and Natural Ecosystem Division (IAFENT); Miglietta, Franco (ed.) [National Research Council of Italy (CNR) and Edmund Mach Foundation, San Michele all' Adige (Italy). FoxLab Inst. of Biometeorology

    2015-04-01

    Comprehensively addresses the full greenhouse gases budget of the Italian landscape. Presents the results of the national project CARBOITALY. Provides new data and analyses in the framework of climate policies. The book addresses in a comprehensive way the full greenhouse gases budget of the Italian landscape, focusing on land use and terrestrial ecosystems. In recent years there has been a growing interest in the role of terrestrial ecosystems with regard to the carbon cycle and only recently a regional approach has been considered for its specificity in terms of new methodologies for observations and models and its relevance for national policies on mitigation and adaptation to climate changes. In terms of methods this book describes the role of flux networks and data-driven models, airborne regional measurements of fluxes and specific sectoral approaches related to important components of the human and natural landscapes. There is also a growing need on the part of institutions, agencies and policy stakeholders for new data and analyses enabling them to improve their national inventories of greenhouse gases and their compliance with the UNFCCC process. In this respect the data presented is a basis for a full carbon accounting and available to relevant stakeholders for improvements and/or verification of national inventories. The wealth of research information is the result of a national project, CARBOITALY, which involved 15 Italian institutions and several researchers to provide new data and analyses in the framework of climate policies.

  3. Performance analysis of greenhouse dryer by using insulated north-wall under natural convection mode

    Directory of Open Access Journals (Sweden)

    Prashant Singh Chauhan

    2016-11-01

    Full Text Available A prototype north wall insulated greenhouse dryer has been fabricated and tested in no-load conditions under natural convection mode. Experimentation has been conducted in two different cases. Case-I is when solar collector placed inside the dryer and Case-II is North wall insulated greenhouse dryer without solar collector. Coefficient of performance, heat utilisation factor, convective heat transfer coefficient and coefficient of diffusivity have been evaluated in thermal performance analysis. The difference of the highest convective heat transfer coefficient of both cases is 29.094W/m2°C which is showing the effectiveness of insulated north wall and solar collector. The maximum coefficient of diffusivity (0.0827 was achieved during the third day of experiment in Case-II. The inside room temperature of wall insulated greenhouse dryer for Case-I is 4.11%, 5.08 % and 11.61 % higher than the Case-II during the day 1, day 2 and day 3 respectively. This result is also showing the effectiveness of solar collector and insulated north wall. The highest heat utilisation factor (0.616 is obtained during the second day for Case-I while for Case-II it is 0.769 during the third day of experimentation. Maximum coefficient of performance achieved is 0.892 during the third day of the experiment for Case-I whereas 0.953 is obtained on the first day of experimentation for Case-II.

  4. Filtering natural light at the greenhouse covering - better greenhouse climate and higher production by filtering out NIR?

    NARCIS (Netherlands)

    Hemming, S.; Kempkes, F.; Braak, van der N.; Dueck, T.A.; Marissen, A.

    2006-01-01

    Wageningen UR investigated the potentials of several NIR-filtering methods to be applied in Dutch horticulture. NIR-filtering can be done by the greenhouse covering or by internal or external moveable screens. The objective of this investigation was to quantify the effect of different NIR-filtering

  5. A naturally ventilated accumulator for integrating measurements of radon flux from soil

    International Nuclear Information System (INIS)

    Zhuo Weihai; Furukawa, Masahide; Tokonami, Shinji

    2007-01-01

    For long-term and large-scale measurements of the averaged 222 Rn fluxes from soils in the general environmental conditions, a simple measuring method was developed. 222 Rn exhaling from soils is accumulated by a naturally ventilated accumulator (NVA) and its concentration is measured with passive 222 Rn monitors set inside the NVA. The ventilation rate of the NVA is about 0.26 h -1 and it is hardly affected by the changes of meteorological conditions during field measurements. The air and soil conditions inside and outside of the NVA are nearly the same throughout the measurements. It indicates that the natural conditions of soils will not be significantly disturbed by the NVA. Field measurements confirmed that soil 222 Rn fluxes measured by the new method were in general agreement with the results measured by another commonly used method and theoretical estimations. As no electric power is needed as well as the operation and maintenance are easy, the low-cost system offers a promise as an improved technique for long-term measurements of soil 222 Rn fluxes in the general environmental conditions. (author)

  6. Airborne microorganisms cultivable on naturally ventilated document repositories of the National Archive of Cuba.

    Science.gov (United States)

    Borrego, Sofía; Perdomo, Ivette

    2016-02-01

    The quality of the indoor air can provide very useful information for the artwork conservation. The aim of the study was to evaluate the microbial concentration inside six document repositories of the National Archive of the Republic of Cuba in two months of 1 year. The repositories are large, high, and have a natural cross-ventilation system. The microbial sampling was done in July 2010 (summer or rainy month) and February 2011 (winter or dry month) using the SAS Super 100 biocollector at 100 L/min. An appropriate selective culture media were used to isolate fungi and bacteria. A high total microbial concentration on the north side of the building in two studied months was observed. The fungal concentrations were significantly higher in July 2010 in all repositories, while the bacterial concentrations were significantly higher mostly in February 2011 only in repositories located on the first and second floor of the building. Eight fungal genera in the indoor air of all environments were isolated. Regardless of the side of the analyzed building, Penicillium, Aspergillus, and Cladosporium were the predominant genera. Aspergillus flavus and Aspergillus niger were the species isolated in almost all of the analyzed repositories in the studied months. Gram-positive bacteria prevailed among bacterial groups isolated from indoor air repositories, and some percentages corresponded to the genera Bacillus and Streptomyces. In Cuba, the temperature and relative humidity are high during the whole year but the natural ventilation plays an important role in retarding microbial growth on materials.

  7. Novel approach for evaluation of air change rate in naturally ventilated occupied spaces based on metabolic CO2 time variation

    DEFF Research Database (Denmark)

    Melikov, Arsen Krikor; Markov, Detelin G.

    2014-01-01

    IAQ in many residential buildings relies on non-organized natural ventilation. Accurate evaluation of air change rate (ACR) in this situation is difficult due to the nature of the phenomenon - intermittent infiltration-exfiltration periods of mass exchange between the room air and the outdoor air...... at low rate. This paper describes a new approach for ACR evaluation in naturally ventilated occupied spaces. Actual metabolic CO2 time variation record in an interval of time is compared with the computed variation of metabolic CO2 for the same time interval under reference conditions: sleeping occupants...

  8. Greenhouse Gas and Noxious Emissions from Dual Fuel Diesel and Natural Gas Heavy Goods Vehicles.

    Science.gov (United States)

    Stettler, Marc E J; Midgley, William J B; Swanson, Jacob J; Cebon, David; Boies, Adam M

    2016-02-16

    Dual fuel diesel and natural gas heavy goods vehicles (HGVs) operate on a combination of the two fuels simultaneously. By substituting diesel for natural gas, vehicle operators can benefit from reduced fuel costs and as natural gas has a lower CO2 intensity compared to diesel, dual fuel HGVs have the potential to reduce greenhouse gas (GHG) emissions from the freight sector. In this study, energy consumption, greenhouse gas and noxious emissions for five after-market dual fuel configurations of two vehicle platforms are compared relative to their diesel-only baseline values over transient and steady state testing. Over a transient cycle, CO2 emissions are reduced by up to 9%; however, methane (CH4) emissions due to incomplete combustion lead to CO2e emissions that are 50-127% higher than the equivalent diesel vehicle. Oxidation catalysts evaluated on the vehicles at steady state reduced CH4 emissions by at most 15% at exhaust gas temperatures representative of transient conditions. This study highlights that control of CH4 emissions and improved control of in-cylinder CH4 combustion are required to reduce total GHG emissions of dual fuel HGVs relative to diesel vehicles.

  9. A concept of external aerodynamic elements in improving the performance of natural smoke ventilation in wind conditions

    Science.gov (United States)

    Wegrzyński, Wojciech; Krajewski, Grzegorz; Kimbar, Grzegorz

    2018-01-01

    This paper is a proposal of a new device that may be used as a component of natural smoke ventilation systems - an external aerodynamic baffle used to limit the wind effect at the most adverse angle. Natural ventilation is not only affected by the external wind, but also dependent on the angle of wind attack. It has been proven, that at angles between 45° to 60° the performance of such device is the lowest. This is the reason why additional device is proposed - external baffle that could hypothetically increase the performance at chosen angles. The purpose of this paper is to explore this idea by numerical modelling of such external elements on a validated natural ventilator model, with use of ANSYS® Fluent® CFD model.

  10. The effect of natural ventilation on radon and radon progeny levels in houses

    International Nuclear Information System (INIS)

    Cavallo, A.; Gadsby, K.; Reddy, T.A.; Socolow, R.

    1992-01-01

    In contradiction to the widely held assumption that ventilation is ineffective as a means of reducing indoor radon concentrations, experiments in a research house have shown that the basement radon level can be reduced by a factor of 5-10 using only natural ventilation. Measurements of the outdoor-basement pressure differential and the radon entry rate show that this unexpectedly large reduction in indoor radon levels is caused by two complementary physical processes. The first mechanism is the obvious one: dilution. Radon concentrations are lowered by the addition of uncontaminated outdoor air. The second mechanism is less evident: an open basement window reduces basement depressurisation. This decreases the rate at which radon-laden soil gas is drawn into the house. It was also found that the radon entry rate is a linear function of basement depressurisation up to a differential pressure of about 4 Pa, as would be expected for laminar soil gas flow; opening two basement windows approximately doubles the building air exchange rate and reduces the radon entry rate by up to a factor of 5. (author)

  11. The Impact of Roof Pitch and Ceiling Insulation on Cooling Load of Naturally-Ventilated Attics

    Directory of Open Access Journals (Sweden)

    Linxia Gu

    2012-07-01

    Full Text Available A 2D unsteady computational fluid dynamics (CFD model is employed to simulate buoyancy-driven turbulent ventilation in attics with different pitch values and ceiling insulation levels under summer conditions. The impacts of roof pitch and ceiling insulation on the cooling load of gable-roof residential buildings are investigated based on the simulation of turbulent air flow and natural convection heat transfer in attic spaces with roof pitches from 3/12 to 18/12 combined with ceiling insulation levels from R-1.2 to R-40. The modeling results show that the air flows in the attics are steady and exhibit a general streamline pattern that is qualitatively insensitive to the investigated variations of roof pitch and ceiling insulation. Furthermore, it is predicted that the ceiling insulation plays a control role on the attic cooling load and that an increase of roof pitch from 3/12 to 8/12 results in a decrease in the cooling load by around 9% in the investigated cases. The results suggest that the increase of roof pitch alone, without changing other design parameters, has limited impact on attics cooling load and airflow pattern. The research results also suggest both the predicted ventilating mass flow rate and attic cooling load can be satisfactorily correlated by simple relationships in terms of appropriately defined Rayleigh and Nusselt numbers.

  12. An analytical and numerical study of solar chimney use for room natural ventilation

    Energy Technology Data Exchange (ETDEWEB)

    Bassiouny, Ramadan; Koura, Nader S.A. [Department of Mechanical Power Engineering and Energy, Minia University, Minia 61111 (Egypt)

    2008-07-01

    The solar chimney concept used for improving room natural ventilation was analytically and numerically studied. The study considered some geometrical parameters such as chimney inlet size and width, which are believed to have a significant effect on space ventilation. The numerical analysis was intended to predict the flow pattern in the room as well as in the chimney. This would help optimizing design parameters. The results were compared with available published experimental and theoretical data. There was an acceptable trend match between the present analytical results and the published data for the room air change per hour, ACH. Further, it was noticed that the chimney width has a more significant effect on ACH compared to the chimney inlet size. The results showed that the absorber average temperature could be correlated to the intensity as: (T{sub w} = 3.51I{sup 0.461}) with an accepted range of approximation error. In addition the average air exit velocity was found to vary with the intensity as ({nu}{sub ex} = 0.013I{sup 0.4}). (author)

  13. Greenhouse effects of the peat production and use as compared to coal, oil, natural gas and wood

    International Nuclear Information System (INIS)

    Hillebrand, K.; Wihersaari, M.

    1993-01-01

    This report examines the greenhouse effects of greenhouse gas emissions (carbon dioxide, methane and nitrous oxide) arising from certain production and utilization chains of peat and compares them with the corresponding effects associated with the production and utilization chains of coal, oil, natural gas and wood. In order to estimate the greenhouse effects of the peat production and utilization chains, the initial state of the peat bog together with the instantaneous and cumulative greenhouse effects associated with the production and burning of peat as well as subsequent use of the production area were taken into account. The initial state of the peat bog was taken to be either a bog in its natural sale, a forest-drained bog or a cultivated peatland. As regards alternatives for subsequent use of the peat production area, afforestation, paludification and lake formation were all examined

  14. A numerical study on the influence of slope and curvature on smoke flow in special section tunnel with natural ventilation

    Science.gov (United States)

    Wang, Wenzhou; Zhou, Xianping; Liu, Zhigang; Liu, Ya; Liu, Wanfu; Hong, Li

    2017-09-01

    In this study, a special section tunnel model was established by using FDS (Fire Dynamics Simulator). The influences of lope and curvature on smoke flow under natural ventilation have been studied. The results showed that under the condition of natural ventilation, the slope has some influences on the smoke flow in special section tunnel. The smoke spreading speed is accelerated along the upstream direction and decrease along the downstream direction due to buoyancy effect of slope. The steeper the tunnel, the more obvious the buoyancy effect. The curvature has little effect on the flow of flue gas.

  15. Feedback effect of human physical and psychological adaption on time period of thermal adaption in naturally ventilated building

    DEFF Research Database (Denmark)

    liu, weiwei; Huangfu, Hao; Xiong, Jing

    2014-01-01

    This study proposed a method to determine time period of thermal adaption for occupants in naturally ventilated building, and analyzed the synergistic and separate feedback effect of the physical and psychological adaption modes on the time period of thermal adaption. Using the method, the values...... of the time period of thermal adaption were obtained on the basis of the data from a long-term field survey conducted in two typical naturally ventilated offices located in Changsha, China. The results showed that the occupants need to take 4.25 days to fully adapt to a step-change in outdoor air temperature...

  16. Construction and Operation of a Ventilated Hood System for Measuring Greenhouse Gas and Volatile Organic Compound Emissions from Cattle

    Directory of Open Access Journals (Sweden)

    Yongjing Zhao

    2011-12-01

    Full Text Available Recent interest in greenhouse gas emissions from ruminants, such as cattle, has spawned a need for affordable, precise, and accurate methods for the measurement of gaseous emissions arising from enteric fermentation. A new head hood system for cattle designed to capture and quantify emissions was recently developed at the University of California, Davis. The system consists of two head hoods, two vacuum pumps, and an instrumentation cabinet housing the required data collection equipment. This system has the capability of measuring carbon dioxide, methane, ethanol, methanol, water vapor, nitrous oxide, acetic acid emissions and oxygen consumption in real-time. A unique aspect of the hoods is the front, back, and sides are made of clear polycarbonate sheeting allowing the cattle a full range of vision during gas sampling. Recovery rates for these slightly negative pressure chambers were measured ranging from 97.6 to 99.3 percent. This system can capture high quality data for use in improving emission inventories and evaluating gaseous emission mitigation strategies.

  17. Natural ventilation without air breathing in the top openings of highway tunnels

    Science.gov (United States)

    Jin, Sike; Jin, Jiali; Gong, Yanfeng

    2017-05-01

    A number of urban shallow-buried highway tunnels have been built in China. Despite much better internal air quality compared to the traditional tunnels, there is no sufficient theoretical ground or experimental support for the construction of such tunnels. Most researchers hold that natural ventilation in such tunnels depends on air breathing in the top openings, but some others are skeptical about this conclusion. By flow visualization technology on a tunnel experiment platform, we tested the characteristics of airflow in the top openings of highway tunnels. The results showed that air always flowed from outside to inside in all top openings above a continuous traffic stream, and the openings did not breathe at all. In addition, intake air in the top openings reached its maximum velocity at the tunnel entrance, and then gradually slowed down with tunnel depth increasing.

  18. Environmental performance of a naturally ventilated city centre library; Milieuprestatie van een natuurlijk geventileerde stadsbibliotheek

    Energy Technology Data Exchange (ETDEWEB)

    Krausse, B.; Cook, M.; Lomas, K.

    2008-03-15

    To tackle climate change it is essential to reduce carbon dioxide emissions. To this end, it is important to reduce the energy demands of nondomestic buildings. Naturally ventilated buildings can have low energy demands but the strategy is difficult to implement in deep plan, urban sites. The Frederick Lanchester Library at Coventry University, UK, incorporates natural ventilation, daylighting and passive cooling strategies. By using lightwells and perimeter stacks to supply and exhaust air, it can be ventilated by natural means despite its deep plan form and sealed facade. This paper describes the building and presents the energy consumption and the internal temperatures and CO2 levels recorded in 2004/2005. The building's performance is compared to the original design criteria and good practice guidelines. Recommendations for the design of such buildings are made and the likely performance in other UK cities is assessed. It is concluded that the building uses under half the energy of a standard airconditioned building and yet, in summer, can keep the interior comfortable and up to 5C below ambient. The design would perform equally well in the typical weather conditions experienced at 13 other UK cities, but not in London. It is concluded that deep-plan, naturally ventilated buildings with sealed facades, if well designed, could maintain thermal comfort in all but a very few UK sites, whilst consuming much less energy than even good practice standards. [Dutch] Natuurlijk geventileerde gebouwen kunnen een lage energievraag hebben. Het is echter moeilijk om deze strategie te implementeren in gebouwen in stedelijke gebieden met een, in verhouding, diepe plattegrond. De Frederick Lanchester Bibliotheek op de Coventry Universiteit in het Verenigd Koninkrijk brengt natuudijke ventilatie, daglicht en passieve koeling samen tot een geheel. Door gebruik te maken van een atrium en ventilatieschachten voor de toevoer en afvoer van lucht, kan er op een natuurlijke wijze

  19. The effects of uncinectomy and natural ostial dilatation on maxillary sinus ventilation: a clinical experimental study.

    Science.gov (United States)

    Kutluhan, Ahmet; Şalvız, Mehti; Bozdemir, Kazım; Kanbak, Orhan; Ulu, Mustafa; Yalçıner, Gökhan; Bilgen, Akif Sinan

    2011-04-01

    The purpose of this study was to determine the effect of uncinectomy without sinusotomy and natural ostial dilatation on maxillary sinus ventilation in chronic rhinosinusitis. Twenty patients with chronic rhinosinusitis were included in this study. The patients were randomly divided into two groups. Group 1 consisted of patients with uncinectomy (n = 10), while group 2 was made up of patients treated with natural ostial dilatation (n = 10). The CO(2) tension and pressure levels of the maxillary sinus during inspiration and expiration phases were obtained and compared before and after the procedures within and between the groups. The mean CO(2) tension levels in both groups were significantly decreased after the procedures. The mean maxillary sinus pressure during inspiration was significantly decreased to a negative value after uncinectomy; however, no significant change was observed during expiration. There were no significant changes in maxillary sinus pressures after natural ostial dilatation procedure. Both uncinectomy and natural ostial dilatation seem to be equally effective in decreasing maxillary sinus pCO(2) levels. The effects of decreased maxillary sinus pressure during inspiration after uncinectomy on mucociliary clearance and development mechanisms of chronic rhinosinusitis seem to be worth investigating.

  20. A Review on Natural Ventilation-enabling Façade Noise Control Devices for Congested High-Rise Cities

    Directory of Open Access Journals (Sweden)

    Shiu-Keung Tang

    2017-02-01

    Full Text Available This review summarizes the current status of the research and development of natural ventilation-enabling noise control devices for use on the façades of high-rise residential buildings in congested cities. These devices are important for a sustainable urbanized city, as they are supposed to offer good acoustical protection to citizens, allowing for an acceptable level of natural ventilation inside residential units; energy for mechanical ventilation can then be saved. From the information presented in the existing literature, it is concluded that protrusive devices, such as lintels and balconies, are not effective noise screening devices, even if they are installed with sound absorbers and/or reflectors, under the effect of city reverberation. On the contrary, plenum windows and similar structures, which are plenum structures with a staggered air inlet and outlet, are interesting alternatives that are worth rigorous considerations.

  1. Numerical analysis of passive strategies for energy retrofit of existing buildings in Mediterranean climate: thermal mass and natural ventilation combination

    Directory of Open Access Journals (Sweden)

    Calcerano Filippo

    2017-01-01

    Full Text Available The study investigates the potential of coupling natural ventilation and thermal storage systems to improve hygrothermal comfort and reduce energy consumption during summer season in an existing building in the Mediterranean. It aims at bridging the knowledge gap between designers, researchers and building scientists, fostering a multidisciplinary approach and promoting numerical simulation of the energy performance of buildings within architectural professional practice. The study analyses the interaction between six natural ventilation systems (single sided ventilation through facade openings; cross ventilation through facade openings, inlet wind tower, thermal chimney, evaporative cool tower, earth pipes and with two thermal storage typology (heavy and medium-light within four strategic Italian location (Rome, Naples, Messina and Catania. For each interaction we perform a numerical dynamic simulation of indoor comfort, indoor air quality and energy consumption during the summer period, on a reference building model corresponding to the most common Italian typology. Results show that the use of the chosen systems ensures significant reductions of discomfort hours and energy consumption in all configurations. The study also highlights the high efficiency of non invasive systems (single-sided and cross ventilation with automatic control present discomfort hours reduction and energy consumption reduction above 68% for all combinations and the significant influence of the daily thermal range value on the performance of systems without air pre-treatment.

  2. Occupant Interactions and Effectiveness of Natural Ventilation Strategies in Contemporary New Housing in Scotland, UK.

    Science.gov (United States)

    Sharpe, Tim; Farren, Paul; Howieson, Stirling; Tuohy, Paul; McQuillan, Jonathan

    2015-07-21

    The need to reduce carbon emissions and fuel poverty has led to increased building envelope air tightness, intended to reduce uncontrolled ventilation heat losses. Ventilation strategies in dwellings still allow the use of trickle ventilators in window frames for background ventilation. The extent to which this results in "healthy" Indoor Air Quality (IAQ) in recently constructed dwellings was a concern of regulators in Scotland. This paper describes research to explore this. First a review of literature was conducted, then data on occupant interactions with ventilation provisions (windows, doors, trickle vents) gathered through an interview-based survey of 200 recently constructed dwellings, and measurements made on a sample of 40 of these. The main measured parameter discussed here is CO2 concentration. It was concluded after the literature review that 1000 ppm absolute was a reasonable threshold to use for "adequate" ventilation. The occupant survey found that there was very little occupant interaction with the trickle ventilators e.g., in bedrooms 63% were always closed, 28% always open, and in only 9% of cases occupants intervened to make occasional adjustments. In the measured dwellings average bedroom CO2 levels of 1520 ppm during occupied (night time) hours were observed. Where windows were open the average bedroom CO2 levels were 972 ppm. With windows closed, the combination of "trickle ventilators open plus doors open" gave an average of 1021 ppm. "Trickle ventilators open" gave an average of 1571 ppm. All other combinations gave averages of 1550 to 2000 ppm. Ventilation rates and air change rates were estimated from measured CO2 levels, for all dwellings calculated ventilation rate was less than 8 L/s/p, in 42% of cases calculated air change rate was less than 0.5 ach. It was concluded that trickle ventilation as installed and used is ineffective in meeting desired ventilation rates, evidenced by high CO2 levels reported across the sampled dwellings

  3. On the effect of wind direction and urban surroundings on natural ventilation of a large semi-enclosed stadium

    NARCIS (Netherlands)

    Hooff, van T.A.J.; Blocken, B.J.E.

    2010-01-01

    Natural ventilation of buildings refers to the replacement of indoor air with outdoor air due to pressure differences caused by wind and/or buoyancy. It is often expressed in terms of the air change rate per hour (ACH). The pressure differences created by the wind depend – among others – on the wind

  4. Use of CO2 feedback as a retrofit solution for improving air quality in naturally ventilated classrooms

    DEFF Research Database (Denmark)

    Wargocki, Pawel; Faria Da Silva, Nuno Alexandre

    Carbon dioxide (CO2) sensors that provide a green/yellow/red visual indication were installed in pairs of naturally ventilated classrooms during normal school operation. During a two-week period in the heating and the cooling season, teachers and students were instructed to open the windows in re...

  5. Methods for measuring gas emissions from naturally ventilated livestock buildings: Developments over the last decade and perspectives for improvement

    NARCIS (Netherlands)

    Ogink, N.W.M.; Mosquera Losada, J.; Calvet, S.; Zhang, G.

    2013-01-01

    The objectives of this paper are: 1) to give an overview of the development of methods for measuring emission rates from naturally ventilated livestock buildings over the last decade, 2) to identify and evaluate strengths and weaknesses, 3) to summarise and conclude the current state-of-art of

  6. Ultrafine and fine particle formation in a naturally ventilated office as a result of reactions between ozone and scented products

    DEFF Research Database (Denmark)

    Toftum, Jørn; Dijken, F. v.

    2003-01-01

    Ultrafine and fine particle formation as a result of chemical reactions between ozone and four different air fresheners and a typical lemon-scented domestic cleaner was studied in a fully furnished, naturally ventilated office. The study showed that under conditions representative of those...

  7. Modeling a Naturally Ventilated Double Skin Façade with a Building Thermal Simulation Program

    DEFF Research Database (Denmark)

    Jensen, Rasmus Lund; Kalyanova, Olena; Heiselberg, Per

    2008-01-01

    to predict. This is manly due to the very transient and complex air flow in the naturally ventilated double skin façade cavity. In this paper the modelling of the DSF using a thermal simulation program, BSim, is discussed. The simulations are based on the measured weather boundary conditions...

  8. Optimization of a solar chimney design to enhance natural ventilation in a multi-storey office building

    NARCIS (Netherlands)

    Gontikaki, M.; Trcka, M.; Hensen, J.L.M.; Hoes, P.

    2010-01-01

    Natural ventilation of buildings can be achieved with solar-driven, buoyancy-induced airflow through a solar chimney channel. Research on solar chimneys has covered a wide range of topics, yet study of the integration in multi-storey buildings has been performed in few numerical studies, where

  9. Numerical analysis of the performance of a venturi-shaped roof for natural ventilation : influence of building width

    NARCIS (Netherlands)

    Hooff, van T.A.J.; Blocken, B.J.E.; Aanen, L.; Bronsema, B.

    2012-01-01

    A numerical analysis with Computational Fluid Dynamics (CFD) is performed to investigate the influence of building width on the performance of a venturi-shaped roof (called Ventec roof) for natural ventilation. The specific roof configuration is intended to create an underpressure in the narrowest

  10. Indoor air quality and occupant satisfaction in five mechanically and four naturally ventilated open-plan office buildings

    DEFF Research Database (Denmark)

    Hummelgaard, J.; Juhl, P.; Saebjornsson, K.O.

    2007-01-01

    Occupant responses and indoor environment characteristics were recorded and compared in five mechanically and four naturally ventilated open-plan office buildings by using a simple approach that enabled us to survey many buildings simultaneously. All occupant responses were obtained during one...

  11. Design Principles for Hybrid Ventilation

    DEFF Research Database (Denmark)

    Heiselberg, Per

    For many years mechanical and natural ventilation systems have developed separately. Naturally, the next step in this development is the development of ventilation concepts that utilize and combine the best features from each system to create a new type of ventilation system -Hybrid Ventilation. ....... The hybrid ventilation concepts, design challenges and - principles are discussed and illustrated by four building examples....

  12. On buoyancy-driven natural ventilation of a room with a heated floor

    Science.gov (United States)

    Gladstone, Charlotte; Woods, Andrew W.

    2001-08-01

    The natural ventilation of a room, both with a heated floor and connected to a cold exterior through two openings, is investigated by combining quantitative models with analogue laboratory experiments. The heated floor generates an areal source of buoyancy while the openings allow displacement ventilation to operate. When combined, these produce a steady state in which the air in the room is well-mixed, and the heat provided by the floor equals the heat lost by displacement. We develop a quantitative model describing this process, in which the advective heat transfer through the openings is balanced with the heat flux supplied at the floor. This model is successfully tested with observations from small-scale analogue laboratory experiments. We compare our results with the steady-state flow associated with a point source of buoyancy: for a given applied heat flux, an areal source produces heated air of lower temperature but a greater volume flux of air circulates through the room. We generalize the model to account for the effects of (i) a cooled roof as well as a heated floor, and (ii) an external wind or temperature gradient. In the former case, the direction of the flow through the openings depends on the temperature of the exterior air relative to an averaged roof and floor temperature. In the latter case, the flow is either buoyancy dominated or wind dominated depending on the strength of the pressure associated with the wind. Furthermore, there is an intermediate multiple-solution regime in which either flow regime may develop.

  13. Applying Time Series Analysis Model to Temperature Data in Greenhouses

    Directory of Open Access Journals (Sweden)

    Abdelhafid Hasni

    2011-03-01

    Full Text Available The objective of the research is to find an appropriate Seasonal Auto-Regressive Integrated Moving Average (SARIMA Model for fitting the inside air temperature (Tin of a naturally ventilated greenhouse under Mediterranean conditions by considering the minimum of Akaike Information Criterion (AIC. The results of fitting were as follows: the best SARIMA Model for fitting air temperature of greenhouse is SARIMA (1,0,0 (1,0,224.

  14. Environmental Noise Exposure On Occupants In Naturally Ventilated Open-Plan Offices Case Of Selected Offices In Kumasi Ghana

    Directory of Open Access Journals (Sweden)

    Koranteng

    2015-08-01

    Full Text Available The design of buildings in public educational institutions in Ghana predominantly adopts open-plan offices that are naturally ventilated with the aid of operable windows for reasons such as achieving adaptable spaces improved social climate and effective ventilation. However adoption of open-plan naturally ventilated offices in these educational institutions expose occupants to noise that emanates indoors and from outdoor sources which can interfere with and impede work performance. The study aimed at assessing noise exposure levels and occupants satisfaction with noise level in selected naturally ventilated open-plan offices in Ghana. The study employed an empirical assessment of the noise levels in and around three of the office buildings using a PCE222 Digital Sound Level Meter and a survey involving interviews to assess workers satisfaction of noise levels of the open-plan offices at the Kwame Nkrumah University of Science and Technology in Kumasi. The results show that mean outdoor noise levels for offices ranged from 11 per cent below to 5 per cent above the WHO permissible limits while mean indoor noise levels exceeded the limit by between 20-40 per cent during the course of the day. In spite of the high levels of noise occupants generally considered the overall noise level in their offices as acceptable. Likewise the results indicate that there are no significant differences in occupants exposure to noise from their various sitting positions in an office space and floor levels in an office building. The paper recommends strategies to manage and improve ambient noise quality within naturally ventilated open-plan office spaces in Ghana. The study will be of relevance as a useful guide to organizations and policy makers concerned with built environmental issues.

  15. Occupant Interactions and Effectiveness of Natural Ventilation Strategies in Contemporary New Housing in Scotland, UK

    Directory of Open Access Journals (Sweden)

    Tim Sharpe

    2015-07-01

    Full Text Available The need to reduce carbon emissions and fuel poverty has led to increased building envelope air tightness, intended to reduce uncontrolled ventilation heat losses. Ventilation strategies in dwellings still allow the use of trickle ventilators in window frames for background ventilation. The extent to which this results in “healthy” Indoor Air Quality (IAQ in recently constructed dwellings was a concern of regulators in Scotland. This paper describes research to explore this. First a review of literature was conducted, then data on occupant interactions with ventilation provisions (windows, doors, trickle vents gathered through an interview-based survey of 200 recently constructed dwellings, and measurements made on a sample of 40 of these. The main measured parameter discussed here is CO2 concentration. It was concluded after the literature review that 1000 ppm absolute was a reasonable threshold to use for “adequate” ventilation. The occupant survey found that there was very little occupant interaction with the trickle ventilators e.g., in bedrooms 63% were always closed, 28% always open, and in only 9% of cases occupants intervened to make occasional adjustments. In the measured dwellings average bedroom CO2 levels of 1520 ppm during occupied (night time hours were observed. Where windows were open the average bedroom CO2 levels were 972 ppm. With windows closed, the combination of “trickle ventilators open plus doors open” gave an average of 1021 ppm. “Trickle ventilators open” gave an average of 1571 ppm. All other combinations gave averages of 1550 to 2000 ppm. Ventilation rates and air change rates were estimated from measured CO2 levels, for all dwellings calculated ventilation rate was less than 8 L/s/p, in 42% of cases calculated air change rate was less than 0.5 ach. It was concluded that trickle ventilation as installed and used is ineffective in meeting desired ventilation rates, evidenced by high CO2 levels reported

  16. RE: Request for Correction, Technical Support Document, Greenhouse Gas Emissions Reporting from the Petroleum and Natural Gas Industry

    Science.gov (United States)

    The Industrial Energy Consumers of America (IECA) joins the U.S. Chamber of Commerce in its request for correction of information developed by the Environmental Protection Agency (EPA) in a background technical support document titled Greenhouse Gas Emissions Reporting from the Petroleum and Natural Gas Industry

  17. Diesel oil pool fire characteristic under natural ventilation conditions in tunnels with roof openings.

    Science.gov (United States)

    Wang, Yanfu; Jiang, Juncheng; Zhu, Dezhi

    2009-07-15

    In order to research the fire characteristic under natural ventilation conditions in tunnels with roof openings, full-scale experiment of tunnel fire is designed and conducted. All the experimental data presented in this paper can be further applied for validation of numerical simulation models and reduced-scale experimental results. The physical model of tunnel with roof openings and the mathematical model of tunnel fire are presented in this paper. The tunnel fire under the same conditions as experiment is simulated using CFD software. From the results, it can be seen that most smoke is discharged directly off the tunnel through roof openings, so roof openings are favorable for exhausting smoke. But along with the decrease of smoke temperatures, some smoke may backflow and mix with the smoke-free layer below, which leads to fall in visibility and is unfavorable for personnel evacuation. So it is necessary to research more efficient ways for improving the smoke removal efficiency, such as early fire detection systems, adequate warning signs and setting tunnel cap.

  18. Experimental investigation on single-sided transient natural ventilation driven by buoyancy

    Directory of Open Access Journals (Sweden)

    Vadugapalayam Rangasamy Lenin

    2017-01-01

    Full Text Available Energy consumption in building sector plays a major role in hot climate for space cooling. In this view of equipment energy consumption reduction on building space cooling, top vent and window operation-based natural ventilation model is developed in reduced scale. In this study, the performance of rectangular top vent arrangement along with window opening configuration with respect to temperature distribution and air flow pattern is investigated experimentally. The results depicted that the heat generated from the indoor element with vent and window opening configuration showed a greater influence in vertical temperature difference. For both the case of window opened and closed with vent, the time taken to attain the steady-state is shorter for larger vent compared to smaller vent. Increasing the top vent area reduces the indoor air temperature at various levels. When windows in open condition, there is significant reduction in indoor air temperature upto window level for all vent areas. Air flow pattern of the in-door air is validated through smoke visualization test.

  19. Design and simulation of a fuzzy controller for naturally ventilated buildings

    Energy Technology Data Exchange (ETDEWEB)

    Marjanovic, L. [De Montfort Univ., IESD, Leicester (United Kingdom); Eftekhari, M. [Loughborough Univ., Civil and Building Engineering Dept., Loughborough (United Kingdom)

    2004-03-01

    In this paper the design and validation process of a supervisory control for a single-sided naturally ventilated test room is described. The controller is based on fuzzy logic reasoning and sets of linguistic rules in the form of IF-THEN rules are used. The inputs to the controller are the outside wind speed, outside and inside temperatures. The output is the position of the opening. The basis of any fuzzy rule system is the inference engine responsible for the input's fuzzification, fuzzy processing of the rule base and defuzzification of the output. The choice of the inference engine, starting with the selection of input and output variables and their membership functions. Three rule bases of different complexity were developed and are presented and analysed here. Validation through simulation offers possibility of testing the controller under extreme conditions regardless of physical limitations of an experimental test cell. Simulations were performed for different typical levels of input parameters and also for extreme fictitious conditions. Simulations were carefully designed to allow simultaneous comparison of different controllers' performances. Simulation results have shown that all three controllers are capable of responding to the changes in outside conditions by adjusting the opening positions. They satisfy security requirements due to strong wind and successfully, in a stable manner respond to sudden changes in wind velocity and outdoor temperature. A controller with more membership functions and therefore a larger number of IF-THEN rules was more responsive to the changes in outside conditions. (Author)

  20. Air flow distribution in and around a single-sided naturally ventilated room

    Energy Technology Data Exchange (ETDEWEB)

    Eftekhari, M.M.; Marjanovic, L.D.; Pinnock, D.J. [Loughborough University (United Kingdom). Dept. of Civil and Building Engineering

    2002-03-01

    The objective of this research is to compare calculated and measured air flow distributions inside a test room which is naturally ventilated. The test room is situated in a relatively sheltered location and to visualise the resultant local wind pattern around the room for all prevailing wind directions, wind tunnel trials were carried out. Both the wind tunnel and full-scale measurements show that the wind direction at the test cell was generally restricted to either a westerly or an easterly direction. To investigate air flow inside the room, the air pressures and velocities across the openings together with indoor air temperature and velocity at four locations and six different levels are measured. The experimental results demonstrate that for both winter and summer the air was entering the test room at bottom and leaving at the top louvre. Separate air flow and thermal modelling programs are used to predict the spatial distribution of the air flow and thermal comfort. The air flow distribution was predicted using a network air flow program. The predicted flow showed similar trends and the simulation results were in agreement with the measured data. An explicit finite-difference thermal modeling simulation package was used to predict the thermal comfort indices.(author)

  1. NATURAL VENTILATION: A PASSIVE DESIGN STRATEGY IN DESIGNING HOTEL LOBBIES – CASES FROM TROPICAL MALAYSIA

    Directory of Open Access Journals (Sweden)

    Abdul Malik Abdul Rahman

    2009-07-01

    Full Text Available When the Malaysian government increased electricity tariff by up to 12% in early 2006 and also another increase in early July 2008, most commercial buildings were affected by the move. The hardest hit would be the hotel industry as they are among the economic forefronts of the nation. Already burdened with the rigorous efforts of filling their rooms with guests, they now have to re-strategize to sustain business. Energy bills to pay for cooling have always been the biggest burden. Cooling the air is an intangible and a never-ending wasteful activity. Cold room for food is on for 24 hours for obvious reasons. To overcome this, one strategy was considered to be part and parcel of the overall building design so as to contribute to the reduction of the high dependency of energy consumption for cooling. The challenge here is to reduce electricity consumption without compromising the comfort of the guests and also reduce the overhead costs to give a more competitive edge in hotel room rates. Among other passive design elements this paper considers two natural ventilation occurrences and locations that can be relied upon for Malaysian hotel designs.

  2. Synergic effects of thermal mass and natural ventilation on the thermal behaviour of traditional massive buildings

    Science.gov (United States)

    Gagliano, A.; Nocera, F.; Patania, F.; Moschella, A.; Detommaso, M.; Evola, G.

    2016-05-01

    The energy policies about energy efficiency in buildings currently focus on new buildings and on existing buildings in case of energy retrofit. However, historic and heritage buildings, that are the trademark of numerous European cities, should also deserve attention; nevertheless, their energy efficiency is nowadays not deeply investigated. In this context, this study evaluates the thermal performance of a traditional massive building situated in a Mediterranean city. Dynamic numerical simulations were carried out on a yearly basis through the software DesignBuilder, both in free-running conditions and in the presence of an air-conditioning (AC) system. The results highlight that the massive envelope of traditional residential buildings helps in maintaining small fluctuations of the indoor temperature, thus limiting the need for AC in the mid-season and in summer. This feature is highly emphasised by exploiting natural ventilation at night, which allows reducing the building energy demand for cooling by about 30%.The research also indicates that, for Mediterranean climate, the increase in thermal insulation does not always induce positive effects on the thermal performance in summer, and that it might even produce an increase in the heat loads due to the transmission through the envelope.

  3. Assessing the Greenhouse Gas Emissions from Natural Gas Fired Power Plants

    Science.gov (United States)

    Hajny, K. D.; Shepson, P. B.; Rudek, J.; Stirm, B. H.; Kaeser, R.; Stuff, A. A.

    2017-12-01

    Natural gas is often discussed as a "bridge fuel" to transition to renewable energy as it only produces 51% the amount of CO2 per unit energy as coal. This, coupled with rapid increases in production fueled by technological advances, has led to a near tripling of natural gas used for electricity generation since 2005. One concern with this idea of a "bridge fuel" is that methane, the primary component of natural gas, is itself a potent greenhouse gas with 28 and 84 times the global warming potential of CO2 based on mass over a 100 and 20 year period, respectively. Studies have estimated that leaks from the point of extraction to end use of 3.2% would offset the climate benefits of natural gas. Previous work from our group saw that 3 combined cycle power plants emitted unburned CH4 from the stacks and leaked additional CH4 from equipment on site, but total loss rates were still less than 2.2%. Using Purdue's Airborne Laboratory for Atmospheric Research (ALAR) we completed additional aircraft based mass balance experiments combined with passes directly over power plant stacks to expand on the previous study. In this work, we have measured at 12 additional natural gas fired power plants including a mix of operation types (baseload, peaking, intermediate) and firing methods (combined cycle, simple thermal, combustion turbine). We have also returned to the 3 plants previously sampled to reinvestigate emissions for each of those, to assess reproducibility of the results. Here we report the comparison of reported continuous emissions monitoring systems (CEMS) data for CO2 to our emission rates calculated from mass balance experiments, as well as a comparison of calculated CH4 emission rates to estimated emission rates based on the EPA emission factor of 1 g CH4/mmbtu natural gas and CEMS reported heat input. We will also discuss emissions from a coal-fired plant which has been sampled by the group in the past and has since converted to natural gas. Lastly, we discuss the

  4. Implications of natural occlusion of ventilated racks on ammonia and sanitation practices.

    Science.gov (United States)

    Creamer, Michelle A; Petty, Joann; Martin, Tara; Bergdall, Valerie; Hickman-Davis, Judy M

    2014-03-01

    Examination of ventilated rat racks prior to semiannual sanitation revealed silicone nozzles and ventilation ports that were partially or completely occluded with granular debris. We subsequently sought to document performance standards for rack sanitation and investigate the effect of ventilation port occlusion on rack function and animal husbandry practices. We hypothesized that individually ventilated cages with occluded airflow would require more frequent cage changes, comparable to those for static cages (that is, every 3 to 4 d). Sprague-Dawley rats were housed under one of 4 conditions: no airflow occlusion, occluded air-supply inlet, occluded air-exhaust outlet, and occlusion of both inlet and outlet. Cages were changed when daily ammonia concentration exceeded 20 ppm or after 14 d had elapsed. Most cages with unoccluded or partial airflow occlusion remained below the 20 ppm limit until day 12 or 13. Cages with occlusion of both inlet and outlet exceeded 20 ppm ammonia by as early as day 5. Airflow was significantly lower in cages with occlusion of both inlet and outlet airflow. Weekly inspection revealed that occlusion of ventilation ports was detectable by 3 mo after semiannual sanitation. This study demonstrates that silicone nozzles should be removed prior to rack sanitation to improve the effectiveness of cleaning ventilation ports and nozzles. While the rack is in use, silicone nozzles and ventilation ports should be inspected regularly to identify occlusion that is likely to diminish environmental quality in the cage. Intracage ammonia levels are significantly higher when both inlet and outlet airflow are occluded.

  5. The role of natural ventilation in the exposure to radon in the Postojna Cave

    Science.gov (United States)

    Gregorič, A.; Smerajec, M.; Vaupotič, J.

    2012-04-01

    Postojna Cave is the biggest of 21 show caves in Slovenia and one of present day's most visited show caves in the world. Long and branched out cave system, large entrances at different levels, inflow of the Pivka river, and large variation of the outdoor air temperature and precipitation, make the Postojna Cave also a very complex climatic system in which each part shows different conditions. The cave is only naturally ventilated and it is therefore characterised by high radon concentration, which depends on the ventilation regime in different seasons, resulting in typical annual cycles of radon levels in the cave air. Postojna Cave is a typical horizontal cave, where the difference between outside and cave air temperature represents the main driving force for air circulation. In winter, when the cave temperature is higher than outside, cave air is released from the cave into the outdoor atmosphere due to the air draught caused by the 'chimney effect', thus allowing fresh and cold outdoor air to enter the cave through low lying openings. This effect is not operative in summer, when the outside temperature is higher than in the cave, and air draught is minimal or reversed. In addition, air circulation can be locally altered due to other processes, like changing level of Pivka river during the rainy season and local geomorphologic characteristics of cave passages. High radon concentration in the Postojna Cave is the reason for thorough studies of the methodology for dose estimates of the personnel working in the cave. Due to high relative humidity and low air circulation, the cave air is characterised by very low particle concentration, which play an important role in radon dosimetry. Therefore parallel monitoring of radioactive aerosols of radon decay products (RnDP) and general (non-radioactive) aerosols in the particle size range of 10-1100 nm was performed in the air of Postojna Cave at the lowest point of tourist path in summer, winter and both transitional

  6. Impact of neonicotinoid insecticides on natural enemies in greenhouse and interiorscape environments.

    Science.gov (United States)

    Cloyd, Raymond A; Bethke, James A

    2011-01-01

    The neonicotinoid insecticides imidacloprid, acetamiprid, dinotefuran, thiamethoxam and clothianidin are commonly used in greenhouses and/or interiorscapes (plant interiorscapes and conservatories) to manage a wide range of plant-feeding insects such as aphids, mealybugs and whiteflies. However, these systemic insecticides may also be harmful to natural enemies, including predators and parasitoids. Predatory insects and mites may be adversely affected by neonicotinoid systemic insecticides when they: (1) feed on pollen, nectar or plant tissue contaminated with the active ingredient; (2) consume the active ingredient of neonicotinoid insecticides while ingesting plant fluids; (3) feed on hosts (prey) that have consumed leaves contaminated with the active ingredient. Parasitoids may be affected negatively by neonicotinoid insecticides because foliar, drench or granular applications may decrease host population levels so that there are not enough hosts to attack and thus sustain parasitoid populations. Furthermore, host quality may be unacceptable for egg laying by parasitoid females. In addition, female parasitoids that host feed may inadvertently ingest a lethal concentration of the active ingredient or a sublethal dose that inhibits foraging or egg laying. There are, however, issues that require further consideration, such as: the types of plant and flower that accumulate active ingredients, and the concentrations in which they are accumulated; the influence of flower age on the level of exposure of natural enemies to the active ingredient; the effect of neonicotinoid metabolites produced within the plant. As such, the application of neonicotinoid insecticides in conjunction with natural enemies in protected culture and interiorscape environments needs further investigation. Copyright © 2010 Society of Chemical Industry.

  7. CFD evaluation of natural ventilation of indoor environments by the concentration decay method : CO2 gas dispersion from a semi-enclosed stadium

    NARCIS (Netherlands)

    Hooff, van T.A.J.; Blocken, B.J.E.

    2013-01-01

    Computational Fluid Dynamics (CFD) simulations can be used to assess indoor natural ventilation by solving the interaction between the urban wind flow and the indoor airflow. The air exchange rate (ACH) can be obtained from the simulated volume flow rates through the ventilation openings or by the

  8. Natural Ventilation: A Mitigation Strategy to Reduce Overheating In Buildings under Urban Heat Island Effect in South American Cities

    Science.gov (United States)

    Palme, Massimo; Carrasco, Claudio; Ángel Gálvez, Miguel; Inostroza, Luis

    2017-10-01

    Urban heat island effect often produces an increase of overheating sensation inside of buildings. To evacuate this heat, the current use of air conditioning increases the energy consumption of buildings. As a good alternative, natural ventilation is one of the best strategies to obtain indoor comfort conditions, even in summer season, if buildings and urban designs are appropriated. In this work, the overheating risk of a small house is evaluated in four South American cities: Guayaquil, Lima, Antofagasta and Valparaíso, with and without considering the UHI effect. Then, natural ventilation is assessed in order to understand the capability of this passive strategy to assure comfort inside the house. Results show that an important portion of the indoor heat can be evacuated, however the temperature rising (especially during the night) due to UHI can generate a saturation effect if appropriate technical solutions, like the increase in the air speed that can be obtained with good urban design, are not considered.

  9. Effects of air conditioning, dehumidification and natural ventilation on indoor concentrations of 222Rn and 220Rn

    International Nuclear Information System (INIS)

    Lee, Thomas K.C.; Yu, K.N.

    2000-01-01

    A bedroom was selected for detailed measurements on 220 Rn and 222 Rn concentrations and environmental parameters including CO 2 concentration, temperature and relative humidity. To simulate different sealing conditions, five conditions were artificially created in the sampling period of 25 consecutive days. It was concluded that natural ventilation is the most efficient way to lower the 222 Rn levels, while air conditioning is the next. Dehumidification provides only a marginal reduction of 222 Rn levels. The 220 Rn concentrations are not affected by natural ventilation, air conditioner or dehumidification, and were all around 10 Bq m -3 . There are no significant correlations between the 220 Rn and 222 Rn concentrations and environmental conditions such as CO 2 concentrations, temperature, relative humidity and pressure

  10. Experimental study on the dynamic performance of a novel system combining natural ventilation with diffuse ceiling inlet and TABS

    DEFF Research Database (Denmark)

    Yu, Tao; Heiselberg, Per Kvols; Lei, Bo

    2016-01-01

    Highlights • Dynamic experiments are performed to study energy performance of a new HVAC system. • Designed control strategies show good utilization of natural ventilation cooling. • TABS work well with the diffuse ceiling in the dynamic measurements. • No local thermal comfort problem is found...... even in the extreme winter case. • Designed control strategies can be used in the future application of this system....

  11. Building envelope design for renewal of air by natural ventilation in moderate climates. Proposition of a designing methodology; Conception des enveloppes de batiments pour le renouvellement d'air par ventilation naturelle en climats temperes. Proposition d'une methodologie de conception

    Energy Technology Data Exchange (ETDEWEB)

    Mansouri, Y.

    2003-12-01

    The subject of this research is to produce methods and methodological tools for the architects to support the integration of natural ventilation systems in the building envelope design. Our research is situated to the interface between the architectural practice and the physical research on natural ventilation. We are interested in phenomena that can influence or force the strategy of ventilation. A morphological analysis of naturally ventilated buildings concerning the integration modes of natural ventilation systems is done permitting US to propose a typology and a topology of ventilation systems. We define criteria in relation to the thermal comfort, to the quality of air and the economy of energy to assess air renewal techniques. In complement of the sizing tool, we elaborate a methodology of conception for the integration of passives ventilation systems. Design guidelines permit US to conclude on an effective natural ventilation system which is well adapted to collective habitat. (author)

  12. Country-Level Life Cycle Assessment of Greenhouse Gas Emissions from Liquefied Natural Gas Trade for Electricity Generation.

    Science.gov (United States)

    Kasumu, Adebola S; Li, Vivian; Coleman, James W; Liendo, Jeanne; Jordaan, Sarah M

    2018-02-20

    In the determination of the net impact of liquefied natural gas (LNG) on greenhouse gas emissions, life cycle assessments (LCA) of electricity generation have yet to combine the effects of transport distances between exporting and importing countries, country-level infrastructure in importing countries, and the fuel sources displaced in importing countries. To address this, we conduct a LCA of electricity generated from LNG export from British Columbia, Canada with a three-step approach: (1) a review of viable electricity generation markets for LNG, (2) the development of results for greenhouse gas emissions that account for transport to importing nations as well as the infrastructure required for power generation and delivery, and (3) emissions displacement scenarios to test assumptions about what electricity is being displaced in the importing nation. Results show that while the ultimate magnitude of the greenhouse gas emissions associated with natural gas production systems is still unknown, life cycle greenhouse gas emissions depend on country-level infrastructure (specifically, the efficiency of the generation fleet, transmission and distribution losses and LNG ocean transport distances) as well as the assumptions on what is displaced in the domestic electricity generation mix. Exogenous events such as the Fukushima nuclear disaster have unanticipated effects on the emissions displacement results. We highlight national regulations, environmental policies, and multilateral agreements that could play a role in mitigating emissions.

  13. Request for Correction 12003 Greenhouse Gas Emissions Reporting from the Petroleum and Natural Gas Industry

    Science.gov (United States)

    Request for Correction by the U.S. Chamber of Commerce for information in Greenhouse Gas Emissions Reporting from the Petroleum Gas Industry that regarding methane emissions, volatile organic compounds, and hazardous air pollutants.

  14. [Experimental study on the influence of natural and artificial ventilation on indoor radon concentration].

    Science.gov (United States)

    Remetti, R; Gigante, G E

    2010-01-01

    The study presents the results of a campaign of measurements on the daily radon concentration using a Genitron Alpha Guard spectrometer. All the measurements have been intended to highlight the radon concentration variability during the 24 hours of the day and trying to find correlations with other ambient parameters such as temperature and pressure or local conditions such as the presence or not of a forced ventilation system. The main part of the measurements have been carried in the area of the Nuclear Measurement Laboratory of the Department of Basic and Applied Sciences for Engineering of "Sapienza" University of Rome. Results show a rapid rise of radon concentration in the night, when the artificial ventilation system was off and with door and windows closed. In the morning, after the opening of door and windows, the concentration falls down abruptly. With artificial ventilation system in function concentration never reaches significant values.

  15. Effect of natural ventilation on radon and radon progeny levels in houses. Rept. for Apr 90-Sep 91

    International Nuclear Information System (INIS)

    Cavallo, A.; Gadsby, K.; Reddy, T.A.; Socolow, R.

    1991-01-01

    The paper discusses the effect of natural ventilation on radon and radon progeny levels in houses. Contradicting the widely held assumption that ventilation is ineffective in reducing indoor radon concentrations, experiments in a research house have shown that the basement radon level can be reduced by a factor of 5 to 10 using only natural ventilation. Measurement of the outdoor-basement pressure differential and the radon entry rate shows that this unexpectedly large reduction in indoor radon levels is caused by two complementary physical processes: (1) the obvious one, dilution, which lowers radon concentrations by adding uncontaminated outdoor air; and (2) although less evident, introducing a pressure break in the system through an open basement window which, in turn, reduces the outdoor-basement pressure differential and the rate at which radon-laden soil gas is drawn into the house. The radon entry rate was found to be a linear function of basement depressurization up to a differential pressure of about 4 Pa, as would be expected for laminar soil gas flow; opening two basement windows approximately doubled the building air exchange rate and reduced the radon entry rate by up to a factor of 5

  16. Natural ventilation in an enclosure induced by a heat source distributed uniformly over a vertical wall

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Z.D.; Li, Y.; Mahoney, J. [CSIRO Building, Construction and Engineering, Advanced Thermo-Fluids Technologies Lab., Highett, VIC (Australia)

    2001-05-01

    A simple multi-layer stratification model is suggested for displacement ventilation in a single-zone building driven by a heat source distributed uniformly over a vertical wall. Theoretical expressions are obtained for the stratification interface height and ventilation flow rate and compared with those obtained by an existing model available in the literature. Experiments were also carried out using a recently developed fine-bubble modelling technique. It was shown that the experimental results obtained using the fine-bubble technique are in good agreement with the theoretical predictions. (Author)

  17. Numerical Simulation of Inter-Flat Air Cross-Contamination under the Condition of Single-Sided Natural Ventilation

    DEFF Research Database (Denmark)

    Liu, Xiaoping; Niu, Jianlei; Perino, Marco

    2008-01-01

    ventilated room, the renormalization group based k-ε model, together with carbon dioxide used as a tracer, is chosen to reveal this air cross-contamination. The simulation results are in agreement with our prior on-site tracer-gas measurements, revealing that the windows flush with a flat fa ade can...... be a major route of the air cross-contamination in high-rise residential buildings. Finally, an assessment index is proposed to evaluate the potential infection risks associated with this inter-flat air flow occurring in high-rise residential buildings....... the two sides, each of which has a flat fa ade with openable windows. When the wind speed is extremely low, with doors closed and windows opened, the flats become single-sided naturally ventilated driven by buoyancy effects. The air pollutants can travel from a lower flat to a vertically adjacent upper...

  18. : ventilators for noninvasive ventilation

    OpenAIRE

    Fauroux , Brigitte; Leroux , Karl; Desmarais , Gilbert; Isabey , Daniel; Clément , Annick; Lofaso , Frédéric; Louis , Bruno

    2008-01-01

    International audience; The aim of the present study was to evaluate the performance characteristics of all the ventilators proposed for home noninvasive positive-pressure ventilation in children in France. The ventilators (one volume-targeted, 12 pressure-targeted and four dual) were evaluated on a bench which simulated six different paediatric ventilatory patterns. For each ventilator, the quality of the inspiratory and expiratory trigger and the ability to reach and maintain the preset pre...

  19. EFFECTS OF NATURAL AND FORCED BASEMENT VENTILATION ON RADON LEVELS IN SINGLE FAMILY DWELLINGS

    Science.gov (United States)

    The report gives, for the first time, results of an extensive study of the effect of ventilation on radon concentrations and radon entry rate in a single-family dwelling. Measurements of radon concentrations, building dynamics, and environmental parameters made in Princeton Unive...

  20. Characterization of the Airflow from a Bottom Hung Window under Natural Ventilation

    DEFF Research Database (Denmark)

    Svidt, Kjeld; Heiselberg, Per; Nielsen, Peter V.

    This paper describes the results of laboratory measurements of the airflow from a bottom hung window mounted near the ceiling of a ventilated room. In the laboratory set-up it was possible to control the temperature difference and the airflow rate through the window. The pressure drop through...

  1. The influence of opening windows and doors on the natural ventilation rate of a residential building

    Science.gov (United States)

    An analysis of air exchange rates due to intentional window and door openings in a research test house located in a residential environment is presented. These data inform the development of ventilation rate control strategies as building envelopes are tightened to improve the e...

  2. The influence of opening windows and doors on the natural ventilation rate of a residential building

    Science.gov (United States)

    Increased building energy efficiency is important in reducing national energy use and greenhouse gas emissions. An analysis of air change rates due to door and window openings in a research test house located in a residential environment are presented. These data inform developme...

  3. Natural history of dental plaque accumulation in mechanically ventilated adults: a descriptive correlational study.

    Science.gov (United States)

    Jones, Deborah J; Munro, Cindy L; Grap, Mary Jo

    2011-12-01

    The purpose of this study was to describe the pattern of dental plaque accumulation in mechanically ventilated adults. Accumulation of dental plaque and bacterial colonisation of the oropharynx is associated with a number of systemic diseases including ventilator associated pneumonia. Data were collected from mechanically ventilated critically ill adults (n=137), enrolled within 24 hours of intubation. Dental plaque, counts of decayed, missing and filled teeth and systemic antibiotic use was assessed on study days 1, 3, 5 and 7. Dental plaque averages per study day, tooth type and tooth location were analysed. Medical respiratory, surgical trauma and neuroscience ICU's of a large tertiary care centre in the southeast United States. Plaque: all surfaces >60% plaque coverage from day 1 to day 7; molars and premolars contained greatest plaque average >70%. Systemic antibiotic use on day 1 had no significant effect on plaque accumulation on day 3 (p=0.73). Patients arrive in critical care units with preexisting oral hygiene issues. Dental plaque tends to accumulate in the posterior teeth (molars and premolars) that may be hard for nurses to visualise and reach; this problem may be exacerbated by endotracheal tubes and other equipment. Knowing accumulation trends of plaque will guide the development of effective oral care protocols. Published by Elsevier Ltd.

  4. Experimental Study of a natural ventilation strategy in a Full-Scale Enclosure Under Meteorological Conditions: A Buoyancy-Driven Approach

    OpenAIRE

    Austin, Miguel Chen; Bruneau, Denis; Sempey, Alain; Mora, Laurent; Sommier, Alain

    2018-01-01

    The performance of a natural ventilation strategy, in a full-scale enclosure under meteorological conditions is studied through an experimental study, a buoyancy-driven approach, by means of the estimation of the air exchange rate per hour and ventilation power. A theoretical and an empirical model are proposed based on the airflow theory in buildings and blower-door tests. A preliminary validation, by comparing our results with standards in air leakage rate determination, is made. The experi...

  5. Ventilation systems

    International Nuclear Information System (INIS)

    Gossler

    1980-01-01

    The present paper deals with - controlled area ventilation systems - ventilation systems for switchgear-building and control-room - other ventilation systems for safety equipments - service systems for ventilation systems. (orig./RW)

  6. Mechanical Ventilation

    Science.gov (United States)

    ... ventilation is a life support treatment. A mechanical ventilator is a machine that helps people breathe when ... to breathe enough on their own. The mechanical ventilator is also called a ventilator , respirator, or breathing ...

  7. Greenhouse Emission Reductions and Natural Gas Vehicles: A Resource Guide on Technology Options and Project Development

    Energy Technology Data Exchange (ETDEWEB)

    Orestes Anastasia; NAncy Checklick; Vivianne Couts; Julie Doherty; Jette Findsen; Laura Gehlin; Josh Radoff

    2002-09-01

    Accurate and verifiable emission reductions are a function of the degree of transparency and stringency of the protocols employed in documenting project- or program-associated emissions reductions. The purpose of this guide is to provide a background for law and policy makers, urban planners, and project developers working with the many Greenhouse Gas (GHG) emission reduction programs throughout the world to quantify and/or evaluate the GHG impacts of Natural Gas Vehicle (NGVs). In order to evaluate the GHG benefits and/or penalties of NGV projects, it is necessary to first gain a fundamental understanding of the technology employed and the operating characteristics of these vehicles, especially with regard to the manner in which they compare to similar conventional gasoline or diesel vehicles. Therefore, the first two sections of this paper explain the basic technology and functionality of NGVs, but focus on evaluating the models that are currently on the market with their similar conventional counterparts, including characteristics such as cost, performance, efficiency, environmental attributes, and range. Since the increased use of NGVs, along with Alternative Fuel Vehicle (AFVs) in general, represents a public good with many social benefits at the local, national, and global levels, NGVs often receive significant attention in the form of legislative and programmatic support. Some states mandate the use of NGVs, while others provide financial incentives to promote their procurement and use. Furthermore, Federal legislation in the form of tax incentives or procurement requirements can have a significant impact on the NGV market. In order to implement effective legislation or programs, it is vital to have an understanding of the different programs and activities that already exist so that a new project focusing on GHG emission reduction can successfully interact with and build on the experience and lessons learned of those that preceded it. Finally, most programs

  8. Influence of input data on airflow network accuracy in residential buildings with natural wind- and stack-driven ventilation

    Institute of Scientific and Technical Information of China (English)

    Krzysztof Arendt; Marek Krzaczek; Jacek Tejchman

    2017-01-01

    The airflow network (AFN) modeling approach provides an attractive balance between the accuracy and computational demand for naturally ventilated buildings. Its accuracy depends on input parameters such as wind pressure and opening discharge coefficients. In most cases, these parameters are obtained from secondary sources which are solely representative for very simplified buildings, i.e. for buildings without facade details. Although studies comparing wind pressure coefficients or discharge coefficients from different sources exist, the knowledge regarding the effect of input data on AFN is still poor. In this paper, the influence of wind pressure data on the accuracy of a coupled AFN-BES model for a real building with natural wind- and stack-driven ventilation was analyzed. The results of 8 computation cases with different wind pressure data from secondary sources were compared with the measured data. Both the indoor temperatures and the airflow were taken into account. The outcomes indicated that the source of wind pressure data had a significant influence on the model performance.

  9. Quantifying the impact of traffic-related air pollution on the indoor air quality of a naturally ventilated building.

    Science.gov (United States)

    Tong, Zheming; Chen, Yujiao; Malkawi, Ali; Adamkiewicz, Gary; Spengler, John D

    2016-01-01

    Improper natural ventilation practices may deteriorate indoor air quality when in close proximity to roadways, although the intention is often to reduce energy consumption. In this study, we employed a CFD-based air quality model to quantify the impact of traffic-related air pollution on the indoor air quality of a naturally ventilated building. Our study found that the building envelope restricts dispersion and dilution of particulate matter. The indoor concentration in the baseline condition located 10m away from the roadway is roughly 16-21% greater than that at the edge of the roadway. The indoor flow recirculation creates a well-mixed zone with little variation in fine particle concentration (i.e., 253nm). For ultrafine particles (building, particle size, wind condition, and window size and location. A break-even point is observed at D'~2.1 (normalized distance from the roadway by the width of the road). The indoor particle concentration is greater than that at the highway where D'building planning, the distance from the roadway and the ambient wind condition need to be considered at the early design stage whereas the size and location of the window openings, the interior layout, and the placement of fresh air intakes are important to the indoor air quality of existing buildings adjacent to roadways. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Wind tunnel study of natural ventilation of building integrated photovoltaics double skin façade

    Directory of Open Access Journals (Sweden)

    Hudişteanu Sebastian Valeriu

    2018-01-01

    Full Text Available The paper presents a wind tunnel experimental analysis of a small-scale building model (1:30. The objective of the study is to determine the wind influence on the ventilation of a double skin façade channel (DSF and the cooling effect over integrated photovoltaic panels. The tests were achieved by conceiving and implementation of an experimental program using a wind tunnel with atmospheric boundary layer. The effect of the wind over the ventilation of the horizontal channels of double skin façades is evaluated for different incident velocities. The results are generalized for the average steady state values of the velocities analysed. The experimental results put in evidence the correlation between the reference wind velocity and the dynamics of the air movement inside the double skin façade. These values are used to determine the convective heat transfer and the cooling effect of the air streams inside the channel upon the integrated photovoltaic panels. The decrease of the photovoltaic panels temperature determines a raise of 11% in efficiency and power generated.

  11. Wind tunnel study of natural ventilation of building integrated photovoltaics double skin façade

    Science.gov (United States)

    Hudişteanu, Sebastian Valeriu; Popovici, Cătălin George; Cherecheş, Nelu-Cristian

    2018-02-01

    The paper presents a wind tunnel experimental analysis of a small-scale building model (1:30). The objective of the study is to determine the wind influence on the ventilation of a double skin façade channel (DSF) and the cooling effect over integrated photovoltaic panels. The tests were achieved by conceiving and implementation of an experimental program using a wind tunnel with atmospheric boundary layer. The effect of the wind over the ventilation of the horizontal channels of double skin façades is evaluated for different incident velocities. The results are generalized for the average steady state values of the velocities analysed. The experimental results put in evidence the correlation between the reference wind velocity and the dynamics of the air movement inside the double skin façade. These values are used to determine the convective heat transfer and the cooling effect of the air streams inside the channel upon the integrated photovoltaic panels. The decrease of the photovoltaic panels temperature determines a raise of 11% in efficiency and power generated.

  12. Use of computational fluid dynamics in optimization of natural smoke ventilation from a historical shopping mall - Case study

    Science.gov (United States)

    Krajewski, Grzegorz; Wegrzyński, Wojciech

    2018-01-01

    In this paper, the Authors present results of a complex case study, in which a natural smoke ventilation system was introduced into a historical mall Koszyki Market Hall located in the centre of Warsaw. As historical authorities protected the building, the only solution possible was to use a natural system - known for deficient performance in façade applications. To maximise the performance of the smoke control system, a Computational Wind Engineering exercise was performed. The goal was to find the most difficult wind attack angles, and optimise the performance at these conditions. Once the wind influence was known, a transient analysis was performed that included the growth of the fire within the building, as well as a numerical evacuation study. The resulting system was immune to the wind effects, and provided safe evacuation to users of the building, even in difficult wind conditions.

  13. Seasonal variations of natural ventilation and radon-222 exhalation in a slightly rising dead-end tunnel.

    Science.gov (United States)

    Perrier, Frédéric; Richon, Patrick; Gautam, Umesh; Tiwari, Dilli Ram; Shrestha, Prithvi; Sapkota, Soma Nath

    2007-01-01

    The concentration activity of radon-222 has been monitored, with some interruptions, from 1997 to 2005 in the end section of a slightly rising, dead-end, 38-m long tunnel located in the Phulchoki hill, near Kathmandu, Nepal. While a high concentration varying from 6 x 10(3) Bq m(-3) to 10 x 10(3) Bq m(-3) is observed from May to September (rainy summer season), the concentration remains at a low level of about 200 Bq m(-3) from October to March (dry winter season). This reduction of radon concentration is associated with natural ventilation of the tunnel, which, contrary to expectations for a rising tunnel, takes place mainly from October to March when the outside air temperature drops below the average tunnel temperature. This interpretation is supported by temperature measurements in the atmosphere of the tunnel, a few meters away from the entrance. The temporal variations of the diurnal amplitude of this temperature indeed follow the ventilation rate deduced from the radon measurements. In the absence of significant ventilation (summer season), the radon exhalation flux at the rock surface into the tunnel atmosphere can be inferred; it exhibits a yearly variation with additional transient reductions associated with heavy rainfall, likely to be due to water infiltration. No effect of atmospheric pressure variations on the radon concentration is observed in this tunnel. This experiment illustrates how small differences in the location and geometry of a tunnel can lead to vastly different behaviours of the radon concentration versus time. This observation has consequences for the estimation of the dose rate and the practicability of radon monitoring for tectonic purposes in underground environments.

  14. Indoor-outdoor concentrations of RSPM in classroom of a naturally ventilated school building near an urban traffic roadway

    Science.gov (United States)

    Goyal, Radha; Khare, Mukesh

    2009-12-01

    A study on indoor-outdoor RSPM (PM 10, PM 2.5 and PM 1.0) mass concentration monitoring has been carried out at a classroom of a naturally ventilated school building located near an urban roadway in Delhi City. The monitoring has been planned for a year starting from August 2006 till August 2007, including weekdays (Monday, Wednesday and Friday) and weekends (Saturday and Sunday) from 8:0 a.m. to 2:0 p.m., in order to take into account hourly, daily, weekly, monthly and seasonal variations in pollutant concentrations. Meteorological parameters, including temperature, rH, pressure, wind speed and direction, and traffic parameters, including its type and volume has been monitored simultaneously to relate the concentrations of indoor-outdoor RSPM with them. Ventilation rate has also been estimated to find out its relation with indoor particulate concentrations. The results of the study indicates that RSPM concentrations in classroom exceeds the permissible limits during all monitoring hours of weekdays and weekends in all seasons that may cause potential health hazards to occupants, when exposed. I/O for all sizes of particulates are greater than 1, which implies that building envelop does not provide protection from outdoor pollutants. Further, a significant influence of meteorological parameters, ventilation rate and of traffic has been observed on I/O. Higher I/O for PM 10 is indicating the presence of its indoor sources in classroom and their indoor concentrations are strongly influenced by activities of occupants during weekdays.

  15. Greenhouse science; Global warming: the origin and nature of alleged scientific consensus

    Energy Technology Data Exchange (ETDEWEB)

    Lindzen, R. (Massachusetts Institute of Technology, Cambridge, MA (USA))

    1992-01-01

    The paper contends that there is not a scientific consensus on the existence of global warming. The scientific issues associated with the prediction of global warming are reviewed and it is concluded that there is no substantive basis for predictions of sizeable global warming due to observed increases in greenhouse gases such as CO[sub 2], methane and chlorofluorocarbons. The history of the current concern over global warming is described. Political aspects, scientists' concerns over funding and the desire of industrial companies to improve their public image by supporting environmental activists are some of the factors seen as responsible for the current global warming 'hysteria'. 6 figs.

  16. Microclimate evaluation of a new design of insect-proof screens in a Mediterranean greenhouse

    Directory of Open Access Journals (Sweden)

    Alejandro Lopez-Martinez

    2014-05-01

    Full Text Available This work studies natural ventilation in a Mediterranean greenhouse, comparing a new experimental screen of 13×30 threads cm-2 (porosity 39.0% with a commercial control screen of 10×20 threads cm-2 (porosity 33.5%. In addition, both screens were tested in a wind tunnel to determine the discharge coefficients Cd of the greenhouse side and roof vents, which proved to be 0.16 for the commercial control screen and 0.18 for the experimental screen at both vents. These values represent a theoretical increase of 11% (Cd,φ-10×20 /Cd,φ-13×30 = 0.89 in the natural ventilation capacity of the greenhouse when the experimental screen is used. The greenhouse was divided into two separate sections allowing us to analyze natural ventilation in both sectors simultaneously. Air velocity was measured in the lateral and roof vents with two 3D and six 2D sonic anemometers. Using the commercial control screen there was an average reduction of 16% in ventilation rate, and an average increase of 0.5ºC in the average indoor air temperature, compared to the experimental screen. In addition, the ventilation efficiency ηT was higher with the experimental screen (mean value of 0.9 than with the control (mean value 0.6. We have designed an experimental insect-proof screen (13×30 threads cm-2 with smaller thread diameter, higher thread density, smaller pore size and higher porosity than are used in most commercial meshes. All of these factors promote natural ventilation and improve the greenhouse microclimate.

  17. Simulations of the impacts of building height layout on air quality in natural-ventilated rooms around street canyons.

    Science.gov (United States)

    Yang, Fang; Zhong, Ke; Chen, Yonghang; Kang, Yanming

    2017-10-01

    Numerical simulations were conducted to investigate the effects of building height ratio (i.e., HR, the height ratio of the upstream building to the downstream building) on the air quality in buildings beside street canyons, and both regular and staggered canyons were considered for the simulations. The results show that the building height ratio affects not only the ventilation fluxes of the rooms in the downstream building but also the pollutant concentrations around the building. The parameter, outdoor effective source intensity of a room, is then proposed to calculate the amount of vehicular pollutants that enters into building rooms. Smaller value of this parameter indicates less pollutant enters the room. The numerical results reveal that HRs from 2/7 to 7/2 are the favorable height ratios for the regular canyons, as they obtain smaller values than the other cases. While HR values of 5/7, 7/7, and 7/5 are appropriate for staggered canyons. In addition, in terms of improving indoor air quality by natural ventilation, the staggered canyons with favorable HR are better than those of the regular canyons.

  18. 75 FR 18607 - Mandatory Reporting of Greenhouse Gases: Petroleum and Natural Gas Systems

    Science.gov (United States)

    2010-04-12

    ...: Petroleum and Natural Gas Systems; Proposed Rule #0;#0;Federal Register / Vol. 75 , No. 69 / Monday, April... Natural Gas Systems AGENCY: Environmental Protection Agency (EPA). ACTION: Proposed rule. SUMMARY: EPA is... natural gas systems. Specifically, the proposed supplemental rulemaking would require emissions reporting...

  19. 75 FR 74457 - Mandatory Reporting of Greenhouse Gases: Petroleum and Natural Gas Systems

    Science.gov (United States)

    2010-11-30

    ...: Petroleum and Natural Gas Systems; Final Rule #0;#0;Federal Register / Vol. 75 , No. 229 / Tuesday, November... Natural Gas Systems AGENCY: Environmental Protection Agency (EPA). ACTION: Final rule. SUMMARY: EPA is... natural gas systems. This action adds this source category to the list of source categories already...

  20. Greenhouse Environmental Control Using Optimized MIMO PID Technique

    Directory of Open Access Journals (Sweden)

    Fateh BOUNAAMA

    2011-10-01

    Full Text Available Climate control for protected crops brings the added dimension of a biological system into a physical system control situation. The thermally dynamic nature of a greenhouse suggests that disturbance attenuation (load control of external temperature, humidity, and sunlight is far more important than is the case for controlling other types of buildings. This paper investigates the application of multi-inputs multi-outputs (MIMO PID controller to a MIMO greenhouse environmental model with actuation constraints. This method is based on decoupling the system at low frequency point. The optimal tuning values are determined using genetic algorithms optimization (GA. The inside outsides climate model of the environmental greenhouse, and the automatically collected data sets of Avignon, France are used to simulate and test this technique. The control objective is to maintain a highly coupled inside air temperature and relative humidity of strongly perturbed greenhouse, at specified set-points, by the ventilation/cooling and moisturizing operations.

  1. Overheating risk assessment of naturally ventilated classroom under the influence of climate change in hot and humid region

    Science.gov (United States)

    Huang, Kuo-Tsang

    2013-04-01

    Natural ventilation (NV) is considered one of the passive building strategies used for reducing cooling energy demand. The utilization of nature wind for cooling down indoor thermal environment to reach thermal comfort requires knowledge of adequately positioning the building fenestrations, designing inlet-outlet related opening ratios, planning unobstructed cross ventilation paths, and, the most important, assessing the utilization feasibility base on local climatic variables. Furthermore, factors that influence the indoor thermal condition include building envelope heat gain, indoor air velocity, indoor heat gain (e.g. heat discharges from occupant's body, lighting fixture, electrical appliances), and outdoor climate. Among the above, the indoor thermal performance of NV building is significantly dependent to outdoor climate conditions. In hot and humid Taiwan, under college school classrooms are usually operated in natural ventilation mode and are more vulnerable to climate change in regard to maintain indoor thermal comfort. As climate changes in progress, NV classrooms would expect to encounter more events of overheating in the near future, which result in more severe heat stress, and would risk the utilization of natural ventilation. To evaluate the overheating risk under the influence of recent climate change, an actual top floor elementary school classroom with 30 students located at north Taiwan was modeled. Long-term local hourly meteorological data were gathered and further constructed into EnergyPlus Weather Files (EPWs) format for building thermal dynamic simulation to discuss the indoor thermal environmental variation during the period of 1998 to 2012 by retrospective simulation. As indoor thermal environment is an overall condition resulting from a series combination of various factors, sub-hourly building simulation tool, EnergyPlus, coupled with the above fifteen years' EPWs was adopted to predict hourly indoor parameters of mean radiant

  2. Experimental and Numerical Investigation of the Tracer Gas Methodology in the Case of a Naturally Cross-Ventilated Building

    DEFF Research Database (Denmark)

    Nikolopoulos, Nikos; Nikolopoulos, Aristeidis; Larsen, Tine Steen

    2012-01-01

    The paper presents the investigation of a naturally cross – ventilated building using both experimental and numerical methods with the parameters being the free-stream and the incidence angle of the wind to the openings of the building. The experimental methodology calculates the air change rate......, focusing on the time dependent character of the induced flow field. The numerical results are compared with corresponding experimental data for the three aforementioned experimental methodologies in the case of a full scale building inside a wind-tunnel. The numerical investigation reveals that for large...... based either on measurements of the inlet velocity profile, the outlet velocity profile or the descending rate of the tracer gas concentration using the decay method. The numerical investigation is based on the solution of the governing Navier-Stokes equations in their full three dimensional expression...

  3. Comparative analysis of modified PMV models and SET models to predict human thermal sensation in naturally ventilated buildings

    DEFF Research Database (Denmark)

    Gao, Jie; Wang, Yi; Wargocki, Pawel

    2015-01-01

    In this paper, a comparative analysis was performed on the human thermal sensation estimated by modified predicted mean vote (PMV) models and modified standard effective temperature (SET) models in naturally ventilated buildings; the data were collected in field study. These prediction models were....../s, the expectancy factors for the extended PMV model and the extended SET model were from 0.770 to 0.974 and from 1.330 to 1.363, and the adaptive coefficients for the adaptive PMV model and the adaptive SET model were from 0.029 to 0.167 and from-0.213 to-0.195. In addition, the difference in thermal sensation...... between the measured and predicted values using the modified PMV models exceeded 25%, while the difference between the measured thermal sensation and the predicted thermal sensation using modified SET models was approximately less than 25%. It is concluded that the modified SET models can predict human...

  4. Optimal Control Design for a Solar Greenhouse

    NARCIS (Netherlands)

    Ooteghem, van R.J.C.

    2010-01-01

    Abstract: An optimal climate control has been designed for a solar greenhouse to achieve optimal crop production with sustainable instead of fossil energy. The solar greenhouse extends a conventional greenhouse with an improved roof cover, ventilation with heat recovery, a heat pump, a heat

  5. EFFECT OF THE FILL VENTILATION WINDOW ON PERFORMANCE OF A NATURAL DRAFT COOLING TOWER SUBJECTED TO CROSS-WINDS

    Directory of Open Access Journals (Sweden)

    K. V. Dobrego

    2016-01-01

    Full Text Available Various aerodynamic design elements and technics (wind deflectors, wind walls, etc. are utilized for improvement of the thermal efficiency of the natural draft cooling towers, particularly in conditions of cross wind. One of the technical methods, proposed by engineers of Belarus Academy of Sciences, is installation of the ventilation window in the center of the fill. This method is substantiated by the fact that the flow of cooling gas obtains maximum temperature and humidity near the center of the under-fill space of cooling tower and, as a consequence, performs minimal heat exchange. The influence of the fill ventilation window and wind deflectors in the inlet windows of the cooling tower on its thermal performance in condition of cross-wind is investigated in the paper numerically. The cooling tower of the “Woo-Jin” power plant (China 150 m of the height and 114 m of the base diameter was taken as a prototype. The analogy (equivalence between the heat and mass transfer was taken into consideration, which enabled us to consider single-phase flow and perform complicated 3D simulation by using modern personal computers. Heat transfer coefficient for the fill and its hydrodynamic resistance were defined by using actual data on total flow rate in the cooling tower. The numerical model and computational methods were tested and verified in numerous previous works. The non-linear dependence of the thermal performance of the cooling tower on wind velocity (with the minimum in vicinity of Ucr ~ 8 m/s for the simulated system was demonstrated. Calculations show that in the condition of the average wind speed the fill ventilation window doesn’t improve, but slightly decrease (by 3–7 % performance of the cooling tower. Situation changes in the condition of strong winds Ucw > 12 m/s, which are not typical for Belarus. Utilization of airflow deflectors at the inlet windows of cooling tower, conversely, increases thermal performance of the

  6. Effects of natural and forced basement ventilation on radon levels in single-family dwellings. Final report, May 90-Aug 91

    International Nuclear Information System (INIS)

    Cavallo, A.; Gadsby, K.; Reddy, T.A.

    1992-06-01

    The report gives, for the first time, results of an extensive study of the effect of ventilation on radon concentrations and radon entry rate in a single-family dwelling. Measurements of radon concentrations, building dynamics, and environmental parameters made in Princeton University research houses over several seasons and under different building operating conditions show the functional dependence of radon entry rate on basement depressurization. The work clarifies the role of natural ventilation in reducing indoor radon concentrations. The work shows conclusively that natural ventilation can decrease radon levels two ways: (1) by simple dilution, and (2) by providing a pressure break (defined as any opening in the building shell that reduces the outdoor/indoor differential pressure). This reduces building depressurization and thus the amount of radon-contaminated soil gas that is drawn into the building

  7. Transient effects of sudden changes of heat load in a naturally ventilated room

    Science.gov (United States)

    Caulfield, C. P.; Bower, D. J.; Fitzgerald, S.; Woods, A. W.

    2006-11-01

    Using reduced numerical models and small-scale laboratory experiments, we investigate the transient effects of changing isolated heat loads discontinuously within a large, ventilated space. We consider the emptying filling box (with high and low openings) driven by a single isolated source of buoyancy. The original steady state consists of a buoyant layer, whose depth (for the simplest case of a point source plume) is determined by the geometric properties of the room alone. When the buoyancy flux of the source is increased, a new layer `fills' the room from the top with a more buoyant layer. The original layer disappears due to entrainment by the rising plume. The behaviour is qualitatively different when the source buoyancy flux is decreased. In this case, the rising plume fluid is now relatively dense, and so it inevitably collapses back to `intrude' below the original layer. In this case, the original layer disappears due to both draining through the upper opening, and penetrative entrainment by the dense plume. We compare the predictions of three numerical models using different penetrative entrainment parametrizations to a sequence of laboratory experiments. This entrainment reduces the density of the intruding layer, and so the rising plume eventually stalls, and no longer reaches the (draining) original layer. We demonstrate that it is necessary to consider the transient effects of penetrative entrainment when the reduction in source buoyancy flux is sufficiently small.

  8. Anaesthesia ventilators

    Directory of Open Access Journals (Sweden)

    Rajnish K Jain

    2013-01-01

    Full Text Available Anaesthesia ventilators are an integral part of all modern anaesthesia workstations. Automatic ventilators in the operating rooms, which were very simple with few modes of ventilation when introduced, have become very sophisticated with many advanced ventilation modes. Several systems of classification of anaesthesia ventilators exist based upon various parameters. Modern anaesthesia ventilators have either a double circuit, bellow design or a single circuit piston configuration. In the bellows ventilators, ascending bellows design is safer than descending bellows. Piston ventilators have the advantage of delivering accurate tidal volume. They work with electricity as their driving force and do not require a driving gas. To enable improved patient safety, several modifications were done in circle system with the different types of anaesthesia ventilators. Fresh gas decoupling is a modification done in piston ventilators and in descending bellows ventilator to reduce th incidence of ventilator induced volutrauma. In addition to the conventional volume control mode, modern anaesthesia ventilators also provide newer modes of ventilation such as synchronised intermittent mandatory ventilation, pressure-control ventilation and pressure-support ventilation (PSV. PSV mode is particularly useful for patients maintained on spontaneous respiration with laryngeal mask airway. Along with the innumerable benefits provided by these machines, there are various inherent hazards associated with the use of the ventilators in the operating room. To use these workstations safely, it is important for every Anaesthesiologist to have a basic understanding of the mechanics of these ventilators and breathing circuits.

  9. Anaesthesia ventilators.

    Science.gov (United States)

    Jain, Rajnish K; Swaminathan, Srinivasan

    2013-09-01

    Anaesthesia ventilators are an integral part of all modern anaesthesia workstations. Automatic ventilators in the operating rooms, which were very simple with few modes of ventilation when introduced, have become very sophisticated with many advanced ventilation modes. Several systems of classification of anaesthesia ventilators exist based upon various parameters. Modern anaesthesia ventilators have either a double circuit, bellow design or a single circuit piston configuration. In the bellows ventilators, ascending bellows design is safer than descending bellows. Piston ventilators have the advantage of delivering accurate tidal volume. They work with electricity as their driving force and do not require a driving gas. To enable improved patient safety, several modifications were done in circle system with the different types of anaesthesia ventilators. Fresh gas decoupling is a modification done in piston ventilators and in descending bellows ventilator to reduce th incidence of ventilator induced volutrauma. In addition to the conventional volume control mode, modern anaesthesia ventilators also provide newer modes of ventilation such as synchronised intermittent mandatory ventilation, pressure-control ventilation and pressure-support ventilation (PSV). PSV mode is particularly useful for patients maintained on spontaneous respiration with laryngeal mask airway. Along with the innumerable benefits provided by these machines, there are various inherent hazards associated with the use of the ventilators in the operating room. To use these workstations safely, it is important for every Anaesthesiologist to have a basic understanding of the mechanics of these ventilators and breathing circuits.

  10. Anaesthesia ventilators

    Science.gov (United States)

    Jain, Rajnish K; Swaminathan, Srinivasan

    2013-01-01

    Anaesthesia ventilators are an integral part of all modern anaesthesia workstations. Automatic ventilators in the operating rooms, which were very simple with few modes of ventilation when introduced, have become very sophisticated with many advanced ventilation modes. Several systems of classification of anaesthesia ventilators exist based upon various parameters. Modern anaesthesia ventilators have either a double circuit, bellow design or a single circuit piston configuration. In the bellows ventilators, ascending bellows design is safer than descending bellows. Piston ventilators have the advantage of delivering accurate tidal volume. They work with electricity as their driving force and do not require a driving gas. To enable improved patient safety, several modifications were done in circle system with the different types of anaesthesia ventilators. Fresh gas decoupling is a modification done in piston ventilators and in descending bellows ventilator to reduce th incidence of ventilator induced volutrauma. In addition to the conventional volume control mode, modern anaesthesia ventilators also provide newer modes of ventilation such as synchronised intermittent mandatory ventilation, pressure-control ventilation and pressure-support ventilation (PSV). PSV mode is particularly useful for patients maintained on spontaneous respiration with laryngeal mask airway. Along with the innumerable benefits provided by these machines, there are various inherent hazards associated with the use of the ventilators in the operating room. To use these workstations safely, it is important for every Anaesthesiologist to have a basic understanding of the mechanics of these ventilators and breathing circuits. PMID:24249886

  11. Comparison of life cycle greenhouse gases from natural gas pathways for medium and heavy-duty vehicles.

    Science.gov (United States)

    Tong, Fan; Jaramillo, Paulina; Azevedo, Inês M L

    2015-06-16

    The low-cost and abundant supply of shale gas in the United States has increased the interest in using natural gas for transportation. We compare the life cycle greenhouse gas (GHG) emissions from different natural gas pathways for medium and heavy-duty vehicles (MHDVs). For Class 8 tractor-trailers and refuse trucks, none of the natural gas pathways provide emissions reductions per unit of freight-distance moved compared to diesel trucks. When compared to the petroleum-based fuels currently used in these vehicles, CNG and centrally produced LNG increase emissions by 0-3% and 2-13%, respectively, for Class 8 trucks. Battery electric vehicles (BEVs) powered with natural gas-produced electricity are the only fuel-technology combination that achieves emission reductions for Class 8 transit buses (31% reduction compared to the petroleum-fueled vehicles). For non-Class 8 trucks (pick-up trucks, parcel delivery trucks, and box trucks), BEVs reduce emissions significantly (31-40%) compared to their diesel or gasoline counterparts. CNG and propane achieve relatively smaller emissions reductions (0-6% and 19%, respectively, compared to the petroleum-based fuels), while other natural gas pathways increase emissions for non-Class 8 MHDVs. While using natural gas to fuel electric vehicles could achieve large emission reductions for medium-duty trucks, the results suggest there are no great opportunities to achieve large emission reductions for Class 8 trucks through natural gas pathways with current technologies. There are strategies to reduce the carbon footprint of using natural gas for MHDVs, ranging from increasing vehicle fuel efficiency, reducing life cycle methane leakage rate, to achieving the same payloads and cargo volumes as conventional diesel trucks.

  12. Anaesthesia ventilators

    OpenAIRE

    Jain, Rajnish K; Swaminathan, Srinivasan

    2013-01-01

    Anaesthesia ventilators are an integral part of all modern anaesthesia workstations. Automatic ventilators in the operating rooms, which were very simple with few modes of ventilation when introduced, have become very sophisticated with many advanced ventilation modes. Several systems of classification of anaesthesia ventilators exist based upon various parameters. Modern anaesthesia ventilators have either a double circuit, bellow design or a single circuit piston configuration. In the bello...

  13. Natural Ventilation of Buildings through Light Shafts. Design-Based Solution Proposals

    Science.gov (United States)

    Ángel Padilla-Marcos, Miguel; Meiss, Alberto; Feijó-Muñoz, Jesús

    2017-10-01

    This work analyses how the built environment affects the quality of the air to be introduced into buildings from light shafts. Several factors such as urban environment and building design intervene in the ability of the light shaft to produce its air change process. Urban areas continuously pollute the air in cities which affects the human health and the environment sustainability. Poor air quality outside buildings supposes a big energy waste to promote an acceptable air quality inside buildings. That requires a large flow rate to maintain the indoor air quality which is translated to an energy efficiency term. The main objective focuses on the impact of standardized architecture design in the quality of the indoor air dependent on the air change in the light shaft. The air change capacity of the outdoor space is numbered analysed using the concept of air change efficiency (ACE). ACE is determined by the built environment, the wind conditions and the design of the building containing light shafts. This concept is comparatively evaluated inside a control domain virtually defined to obtain the mean age of the air for a known air volume. The longer the light shaft in the wind direction is, the better the ACE is compared with other options. Light shafts up to 12 metres high are the most suitable in order to obtain acceptable efficiency results. Other studied cases verify that assumption. Different simplified tools for the technicians to evaluate the design of buildings containing light shafts are proposed. Some strategies of architectural design of buildings with light shafts to be used for ventilation are presented.

  14. Wind-induced single-sided natural ventilation in buildings near a long street canyon: CFD evaluation of street configuration and envelope design

    DEFF Research Database (Denmark)

    Ai, Z.T.; Mak, C.M.

    2018-01-01

    an urban context, this study investigates the wind-induced single-sided natural ventilation in buildings near a long street canyon under a perpendicular wind direction using CFD method. Four aspect ratios (AR) of the street canyon, from 1.0, 2.0, 4.0 to 6.0, are investigated to examine the influence...

  15. Full-scale measurements of indoor environmental conditions and natural ventilation in a large semi-enclosed stadium : possibilities and limitations for CFD validation

    NARCIS (Netherlands)

    Hooff, van T.A.J.; Blocken, B.J.E.

    2012-01-01

    The use of Computational Fluid Dynamics (CFD) to study complex physical processes in the built environment requires model validation by means of reduced-scale or full-scale experimental data. CFD studies of natural ventilation of buildings in urban areas should be validated concerning both the wind

  16. Coupled urban wind flow and indoor natural ventilation modelling on a high-resolution grid: A case study for the Amsterdam ArenA stadium

    NARCIS (Netherlands)

    Hooff, van T.A.J.; Blocken, B.J.E.

    2010-01-01

    Wind flow in urban environments is an important factor governing the dispersion of heat and pollutants from streets, squares and buildings. This paper presents a coupled CFD modelling approach for urban wind flow and indoor natural ventilation. A specific procedure is used to efficiently and

  17. MalariaSphere: A greenhouse-enclosed simulation of a natural Anopheles gambiae (Diptera: Culicidae ecosystem in western Kenya

    Directory of Open Access Journals (Sweden)

    Mukabana Wolfgang R

    2002-12-01

    Full Text Available Abstract Background The development and implementation of innovative vector control strategies for malaria control in Africa requires in-depth ecological studies in contained semi-field environments. This particularly applies to the development and release of genetically-engineered vectors that are refractory to Plasmodium infection. Here we describe a modified greenhouse, designed to simulate a natural Anopheles gambiae Giles ecosystem, and the first successful trials to complete the life-cycle of this mosquito vector therein. Methods We constructed a local house, planted crops and created breeding sites to simulate the natural ecosystem of this vector in a screen-walled greenhouse, exposed to ambient climate conditions, in western Kenya. Using three different starting points for release (blood-fed females, virgin females and males, or eggs, we allowed subsequent stages of the life-cycle to proceed under close observation until one cycle was completed. Results Completion of the life-cycle was observed in all three trials, indicating that the major life-history behaviours (mating, sugar feeding, oviposition and host seeking occurred successfully. Conclusion The system described can be used to study the behavioural ecology of laboratory-reared and wild mosquitoes, and lends itself to contained studies on the stability of transgenes, fitness effects and phenotypic characteristics of genetically-engineered disease vectors. The extension of this approach, to enable continuous maintenance of successive and overlapping insect generations, should be prioritised. Semi-field systems represent a promising means to significantly enhance our understanding of the behavioural and evolutionary ecology of African malaria vectors and our ability to develop and evaluate innovative control strategies. With regard to genetically-modified mosquitoes, development of such systems is an essential prerequisite to full field releases.

  18. Design of Energy Efficient Hybrid Ventilation

    DEFF Research Database (Denmark)

    Heiselberg, Per

    The focus in the development has for both systems been to minimise energy consumption while maintaining a comfortable and healthy indoor environment. The natural next step in this development is to develop ventilation concepts that utilises and combines the best features from each system......[Mechanical and natural ventilation] into a new type of ventilation system- Hybrid Ventilation....

  19. Displacement ventilation

    DEFF Research Database (Denmark)

    Kosonen, Risto; Melikov, Arsen Krikor; Mundt, Elisabeth

    The aim of this Guidebook is to give the state-of-the art knowledge of the displacement ventilation technology, and to simplify and improve the practical design procedure. The Guidebook discusses methods of total volume ventilation by mixing ventilation and displacement ventilation and it gives...... insights of the performance of the displacement ventilation. It also shows practical case studies in some typical applications and the latest research findings to create good local micro-climatic conditions....

  20. Greenhouse gas emission measurement and economic analysis of Iran natural gas fired power plants

    International Nuclear Information System (INIS)

    Shahsavari Alavijeh, H.; Kiyoumarsioskouei, A.; Asheri, M.H.; Naemi, S.; Shahsavari Alavije, H.; Basirat Tabrizi, H.

    2013-01-01

    This study attempts to examine the natural gas fired power plants in Iran. The required data from natural gas fired power plants were gathered during 2008. The characteristics of thirty two gas turbine power plants and twenty steam power plants have been measured. Their emission factor values were then compared with the standards of Energy Protection Agency, Euro Union and World Bank. Emission factors of gas turbine and steam power plants show that gas turbine power plants have a better performance than steam power plants. For economic analysis, fuel consumption and environmental damages caused by the emitted pollutants are considered as cost functions; and electricity sales revenue are taken as benefit functions. All of these functions have been obtained according to the capacity factor. Total revenue functions show that gas turbine and steam power plants are economically efficient at 98.15% and 90.89% of capacity factor, respectively; this indicates that long operating years of power plants leads to reduction of optimum capacity factor. The stated method could be implemented to assess the economic status of a country’s power plants where as efficient capacity factor close to one means that power plant works in much better condition. - Highlights: • CO 2 and NO x emissions of Iran natural gas fired power plants have been studied. • CO 2 and NO x emission factors are compared with EPA, EU and World Bank standards. • Costs and benefit as economic functions are obtained according to capacity factor. • Maximum economic profit is obtained for gas turbine and steam power plants. • Investment in CO 2 reduction is recommended instead of investment in NO x reduction

  1. Modelling natural convection in a heated vertical channel for room ventilation

    International Nuclear Information System (INIS)

    Rodrigues, A.M.; Canha da Piedade, A.; Lahellec, A.; Grandpeix, J.Y.

    2000-01-01

    Solar-air collectors installed on the south-facing walls of school buildings have been tried out in Portugal as a passive means of improving indoor air quality without prejudice to thermal comfort requirements. A numerical investigation of the behaviour of these systems, typified as vertical channels opened at both ends, is presented for typical geometries and outdoor conditions. The study is carried out with natural convection and assumes that the induced flow is turbulent and two-dimensional. The fully averaged equations of motion and energy, added to a two-equation turbulence model, are discretized and solved following the concepts of TEF (Transfer Evolution Formalism) using a finite volume method. Flow and temperature fields are produced and results presented in terms of temperature and velocity distributions at the exit section of the duct. These enable a better understanding of the developing flow and can be helpful in the design phase of this type of system. (author)

  2. Influence of radiation on predictive accuracy in numerical simulations of the thermal environment in industrial buildings with buoyancy-driven natural ventilation

    International Nuclear Information System (INIS)

    Meng, Xiaojing; Wang, Yi; Liu, Tiening; Xing, Xiao; Cao, Yingxue; Zhao, Jiangping

    2016-01-01

    Highlights: • The effects of radiation on predictive accuracy in numerical simulations were studied. • A scaled experimental model with a high-temperature heat source was set up. • Simulation results were discussed considering with and without radiation model. • The buoyancy force and the ventilation rate were investigated. - Abstract: This paper investigates the effects of radiation on predictive accuracy in the numerical simulations of industrial buildings. A scaled experimental model with a high-temperature heat source is set up and the buoyancy-driven natural ventilation performance is presented. Besides predicting ventilation performance in an industrial building, the scaled model in this paper is also used to generate data to validate the numerical simulations. The simulation results show good agreement with the experiment data. The effects of radiation on predictive accuracy in the numerical simulations are studied for both pure convection model and combined convection and radiation model. Detailed results are discussed regarding the temperature and velocity distribution, the buoyancy force and the ventilation rate. The temperature and velocity distributions through the middle plane are presented for the pure convection model and the combined convection and radiation model. It is observed that the overall temperature and velocity magnitude predicted by the simulations for pure convection were significantly greater than those for the combined convection and radiation model. In addition, the Grashof number and the ventilation rate are investigated. The results show that the Grashof number and the ventilation rate are greater for the pure convection model than for the combined convection and radiation model.

  3. Computational fluid dynamics in greenhouses: A review

    African Journals Online (AJOL)

    use

    2011-12-05

    Dec 5, 2011 ... reduce environmental impact while enhancing crop qua- lity and yields .... within a mild climate, appropriate design and control of ventilation are required .... crucial parameter in the pattern of internal greenhouse temperatures ...

  4. Chapter 14. Greenhouses

    Energy Technology Data Exchange (ETDEWEB)

    Rafferty, Kevin D.

    1998-01-01

    Greenhouse heating is one of the most common uses of geothermal resources. Because of the significant heating requirements of greenhouses and their ability to use very low- temperature fluids, they are a natural application. The evaluation of a particular greenhouse project involves consideration of the structure heating requirements, and the system to meet those requirements. This chapter is intended to provide information on each of these areas.

  5. Life Cycle Energy Consumption and Greenhouse Gas Emissions Analysis of Natural Gas-Based Distributed Generation Projects in China

    Directory of Open Access Journals (Sweden)

    Hansi Liu

    2017-10-01

    Full Text Available In this paper, we used the life-cycle analysis (LCA method to evaluate the energy consumption and greenhouse gas (GHG emissions of natural gas (NG distributed generation (DG projects in China. We took the China Resources Snow Breweries (CRSB NG DG project in Sichuan province of China as a base scenario and compared its life cycle energy consumption and GHG emissions performance against five further scenarios. We found the CRSB DG project (all energy input is NG can reduce GHG emissions by 22%, but increase energy consumption by 12% relative to the scenario, using coal combined with grid electricity as an energy input. The LCA also indicated that the CRSB project can save 24% of energy and reduce GHG emissions by 48% relative to the all-coal scenario. The studied NG-based DG project presents major GHG emissions reduction advantages over the traditional centralized energy system. Moreover, this reduction of energy consumption and GHG emissions can be expanded if the extra electricity from the DG project can be supplied to the public grid. The action of combining renewable energy into the NG DG system can also strengthen the dual merit of energy conservation and GHG emissions reduction. The marginal CO2 abatement cost of the studied project is about 51 USD/ton CO2 equivalent, which is relatively low. Policymakers are recommended to support NG DG technology development and application in China and globally to boost NG utilization and control GHG emissions.

  6. Effects of natural gas composition on performance and regulated, greenhouse gas and particulate emissions in spark-ignition engines

    International Nuclear Information System (INIS)

    Amirante, R.; Distaso, E.; Di Iorio, S.; Sementa, P.; Tamburrano, P.; Vaglieco, B.M.; Reitz, R.D.

    2017-01-01

    Highlights: • The influence of natural gas composition is investigated. • Real-time methane/propane fuel mixtures were realized. • IMEP, HRR and MBF were used to evaluate the effects on engine performance. • Gaseous, greenhouse and Particulate emissions were studied. • The propane content strongly influenced performance and emissions. - Abstract: In vehicles fueled with compressed natural gas, a variation in the fuel composition can have non-negligible effects on their performance, as well as on their emissions. The present work aimed to provide more insight on this crucial aspect by performing experiments on a single-cylinder port-fuel injected spark-ignition engine. In particular, methane/propane mixtures were realized to isolate the effects of a variation of the main constituents in natural gas on engine performance and associated pollutant emissions. The propane volume fraction was varied from 10 to 40%. Using an experimental procedure designed and validated to obtain precise real-time mixture fractions to inject directly into the intake manifold. Indicative Mean Effective Pressure, Heat Release Rate and Mass Burned Fraction were used to evaluate the effects on engine performance. Gaseous emissions were measured as well. Particulate Mass, Number and Size Distributions were analyzed with the aim to identify possible correlations existing between fuel composition and soot emissions. Emissions samples were taken from the exhaust flow, just downstream of the valves. Opacity was measured downstream the Three-Way Catalyst. Three different engine speeds were investigated, namely 2000, 3000 and 4000 rpm. Stoichiometric and full load conditions were considered in all tests. The results were compared with pure methane and propane, as well as with natural gas. The results indicated that both performance and emissions were strongly influenced by the variation of the propane content. Increasing the propane fraction favored more complete combustion and increased NO

  7. Life cycle greenhouse gas emissions from U.S. liquefied natural gas exports: implications for end uses.

    Science.gov (United States)

    Abrahams, Leslie S; Samaras, Constantine; Griffin, W Michael; Matthews, H Scott

    2015-03-03

    This study analyzes how incremental U.S. liquefied natural gas (LNG) exports affect global greenhouse gas (GHG) emissions. We find that exported U.S. LNG has mean precombustion emissions of 37 g CO2-equiv/MJ when regasified in Europe and Asia. Shipping emissions of LNG exported from U.S. ports to Asian and European markets account for only 3.5-5.5% of precombustion life cycle emissions, hence shipping distance is not a major driver of GHGs. A scenario-based analysis addressing how potential end uses (electricity and industrial heating) and displacement of existing fuels (coal and Russian natural gas) affect GHG emissions shows the mean emissions for electricity generation using U.S. exported LNG were 655 g CO2-equiv/kWh (with a 90% confidence interval of 562-770), an 11% increase over U.S. natural gas electricity generation. Mean emissions from industrial heating were 104 g CO2-equiv/MJ (90% CI: 87-123). By displacing coal, LNG saves 550 g CO2-equiv per kWh of electricity and 20 g per MJ of heat. LNG saves GHGs under upstream fugitive emissions rates up to 9% and 5% for electricity and heating, respectively. GHG reductions were found if Russian pipeline natural gas was displaced for electricity and heating use regardless of GWP, as long as U.S. fugitive emission rates remain below the estimated 5-7% rate of Russian gas. However, from a country specific carbon accounting perspective, there is an imbalance in accrued social costs and benefits. Assuming a mean social cost of carbon of $49/metric ton, mean global savings from U.S. LNG displacement of coal for electricity generation are $1.50 per thousand cubic feet (Mcf) of gaseous natural gas exported as LNG ($.028/kWh). Conversely, the U.S. carbon cost of exporting the LNG is $1.80/Mcf ($.013/kWh), or $0.50-$5.50/Mcf across the range of potential discount rates. This spatial shift in embodied carbon emissions is important to consider in national interest estimates for LNG exports.

  8. Influence of placement and height of high-rise buildings on wind pressure distribution and natural ventilation of low- and medium-rise buildings

    Czech Academy of Sciences Publication Activity Database

    Kuznetsov, Sergeii; Butova, A.; Pospíšil, Stanislav

    2016-01-01

    Roč. 15, 3/4 (2016), s. 253-266 ISSN 1473-3315 R&D Projects: GA ČR(CZ) GA14-12892S; GA MŠk(CZ) LO1219 Keywords : natural ventilation * high-rise building s * low- and medium-rise building s * wind pressure coefficient * wind tunnel tests Subject RIV: JM - Building Engineering Impact factor: 0.391, year: 2016 http://www.tandfonline.com/doi/full/10.1080/14733315.2016.1214396

  9. VENTILATION MODEL

    International Nuclear Information System (INIS)

    V. Chipman

    2002-01-01

    The purpose of the Ventilation Model is to simulate the heat transfer processes in and around waste emplacement drifts during periods of forced ventilation. The model evaluates the effects of emplacement drift ventilation on the thermal conditions in the emplacement drifts and surrounding rock mass, and calculates the heat removal by ventilation as a measure of the viability of ventilation to delay the onset of peak repository temperature and reduce its magnitude. The heat removal by ventilation is temporally and spatially dependent, and is expressed as the fraction of heat carried away by the ventilation air compared to the fraction of heat produced by radionuclide decay. One minus the heat removal is called the wall heat fraction, or the remaining amount of heat that is transferred via conduction to the surrounding rock mass. Downstream models, such as the ''Multiscale Thermohydrologic Model'' (BSC 2001), use the wall heat fractions as outputted from the Ventilation Model to initialize their postclosure analyses

  10. Solar chimney for the natural ventilation of buildings: simulation and mediation; Chimenea solar para la ventilacion natural de edificios: simulacion y mediacion

    Energy Technology Data Exchange (ETDEWEB)

    Lanceta, D.; Llorente, J.

    2008-07-01

    In this article, the first part of a research project about the modelling of a solar chimney is presented. In this first part, the average ventilation flows measured in an experimental installation have been compared to the results obtained by CFD (Computational Fluid Dynamics) simulations. In order to do so, a solar chimney with a cross-section of 0.78 m x 0.156 m, height 3,6 m, has been constructed. The chimney consists of a glass surface oriented towards the south. The internal (absorber) surface is made of a copper plate, which has been painted black in order to increase the solar absorption. The chimney is connected to a room measuring 5 m x 2.5 m x 2.5 m, from where it extracts air. The comparison of the results obtained by measurements with those obtained by CFD simulations show that computational tools are accurate enough to predict the behaviour of natural buoyancy in this kind of installations. (Author)

  11. Grappling with greenhouse

    International Nuclear Information System (INIS)

    Mitchell, C.D.

    1992-01-01

    A natural greenhouse effect keeps the Earth at a temperature suitable for life. Some of the gases responsible for the greenhouse effect are increasing at an unprecedented rate because of human activity. These increased levels of greenhouse gases in the atmosphere will strengthen the natural greenhouse effect, leading to an overall warming of the Earth's surface. Global warming resulting from the enhanced greenhouse effect is likely to be obscured by normal climatic fluctuations for another ten years or more. The extent of human-caused climate change will depend largely on future concentrations of greenhouse gases in the atmosphere. In turn, the composition of the atmosphere depends on the release of greenhouse gases. Releases are hard to predict, because they require an understanding of future human activity. The composition of the atmosphere also depends on the processes which remove greenhouse gases from it. This booklet is summarizing the latest research results in the form of climate change scenarios. The present scenarios of change are based on climate models, together with an understanding of how present-day climate, with its inherent natural variability, affects human activities. These scenarios present a coherent range of future possibilities for climate; they are not predictions but they serve as a useful starting point. It is estimated that human-caused climate change will affect all aspects of life in Australia, including our cities, agriculture, pests and diseases, fisheries and natural ecosystems. 15 figs., ills

  12. Adaptive neuro-fuzzy inference systems (ANFIS) application to investigate potential use of natural ventilation in new building designs in Turkey

    Energy Technology Data Exchange (ETDEWEB)

    Ayata, Tahir; Cam, Ertugrul; Yildiz, Osman [Kirikkale University, Faculty of Engineering, 71451, Campus, Kirikkale (Turkey)

    2007-05-15

    Natural ventilation in living and working places provides both circulation of clear air and a decrease of indoor temperature, especially during hot summer days. In addition to openings, the dimension ratio and position of buildings play a significant role to obtain a uniform indoor air velocity distribution. In this study, the potential use of natural ventilation as a passive cooling system in new building designs in Kayseri, a midsize city in Turkey, was investigated. First, indoor air velocity distributions with respect to changing wind direction and magnitude were simulated by the FLUENT package program, which employs finite element methods. Then, an adaptive neuro-fuzzy inference systems (ANFIS) model was employed to predict indoor average and maximum air velocities using the simulated data by FLUENT. The simulation results suggest that natural ventilation can be used to provide a thermally comfortable indoor environment during the summer season in the study area. Also, the ANFIS model can be proposed for estimation of indoor air velocity values in such studies. (author)

  13. [Anesthesia ventilators].

    Science.gov (United States)

    Otteni, J C; Beydon, L; Cazalaà, J B; Feiss, P; Nivoche, Y

    1997-01-01

    To review anaesthesia ventilators in current use in France by categories of ventilators. References were obtained from computerized bibliographic search. (Medline), recent review articles, the library of the service and personal files. Anaesthesia ventilators can be allocated into three groups, depending on whether they readminister expired gases or not or allow both modalities. Contemporary ventilators provide either constant volume ventilation, or constant pressure ventilation, with or without a pressure plateau. Ventilators readministering expired gases after CO2 absorption, or closed circuit ventilators, are either of a double- or a single-circuit design. Double-circuit ventilators, or pneumatical bag or bellows squeezers, or bag-in-bottle or bellows-in-bottle (or box) ventilators, consist of a primary, or driving circuit (bottle or box) and a secondary or patient circuit (including a bag or a bellows or membrane chambers). Bellows-in-bottle ventilators have either standing bellows ascending at expiration, or hanging bellows, descending at expiration. Ascending bellows require a positive pressure of about 2 cmH2O throughout exhalation to allow the bellows to refill. The expired gas volume is a valuable indicator for leak and disconnection. Descending bellows generate a slight negative pressure during exhalation. In case of leak or disconnection they aspirate ambient air and cannot act therefore as an indicator for integrity of the circuit and the patient connection. Closed circuit ventilators with a single-circuit (patient circuit) include a insufflating device consisting either in a bellows or a cylinder with a piston, operated by a electric or pneumatic motor. As the hanging bellows of the double circuit ventilators, they generate a slight negative pressure during exhalation and aspirate ambient air in case of leak or disconnection. Ventilators not designed for the readministration of expired gases, or open circuit ventilators, are generally stand

  14. Ventilation models

    Science.gov (United States)

    Skaaret, Eimund

    Calculation procedures, used in the design of ventilating systems, which are especially suited for displacement ventilation in addition to linking it to mixing ventilation, are addressed. The two zone flow model is considered and the steady state and transient solutions are addressed. Different methods of supplying air are discussed, and different types of air flow are considered: piston flow, plane flow and radial flow. An evaluation model for ventilation systems is presented.

  15. Indoor and outdoor particulate matter in primary school classrooms with fan-assisted natural ventilation in Singapore.

    Science.gov (United States)

    Chen, Ailu; Gall, Elliott T; Chang, Victor W C

    2016-09-01

    We conducted multiday continuous monitoring of indoor and outdoor particulate matter (PM) in classrooms with fan-assisted natural ventilation (NV) at five primary schools in Singapore. We monitored size-resolved number concentration of PM with diameter 0.3-10 μm at all schools and alveolar deposited surface area concentrations of PM with diameter 0.01-1.0 μm (SA0.01-1.0) at two schools. Results show that, during the monitoring period, schools closer to expressways and in the downtown area had 2-3 times higher outdoor PM0.3-1.0 number concentrations than schools located in suburban areas. Average indoor SA0.01-1.0 was 115-118 μm(2) cm(-3) during periods of occupancy and 72-87 μm(2) cm(-3) during unoccupied periods. There were close indoor and outdoor correlations for fine PM during both occupied and unoccupied periods (Pearson's r = 0.84-1.0) while the correlations for coarse PM were weak during the occupied periods (r = 0.13-0.74). Across all the schools, the size-resolved indoor/outdoor PM ratios (I/O ratios) were 0.81 to 1.58 and 0.61 to 0.95 during occupied and unoccupied periods, respectively, and average infiltration factors were 0.64 to 0.94. Average PM net emission rates, calculated during periods of occupancy in the classrooms, were lower than or in the lower range of emission rates reported in the literature. This study also reveals that indoor fine and submicron PM predominantly come from outdoor sources, while indoor sources associated with occupancy may be important for coarse PM even when the classrooms have high air exchange rates.

  16. Effect of nature-based sounds' intervention on agitation, anxiety, and stress in patients under mechanical ventilator support: a randomised controlled trial.

    Science.gov (United States)

    Saadatmand, Vahid; Rejeh, Nahid; Heravi-Karimooi, Majideh; Tadrisi, Sayed Davood; Zayeri, Farid; Vaismoradi, Mojtaba; Jasper, Melanie

    2013-07-01

    Few studies have been conducted to investigate the effect of nature-based sounds (N-BS) on agitation, anxiety level and physiological signs of stress in patients under mechanical ventilator support. Non-pharmacological nursing interventions such as N-BS can be less expensive and efficient ways to alleviate anxiety and adverse effects of sedative medications in patients under mechanical ventilator support. This study was conducted to identify the effect of the nature-based sounds' intervention on agitation, anxiety level and physiological stress responses in patients under mechanical ventilation support. A randomized placebo-controlled trial design was used to conduct this study. A total of 60 patients aged 18-65 years under mechanical ventilation support in an intensive care unit were randomly assigned to the control and experimental groups. The patients in the intervention group received 90 min of N-BS. Pleasant nature sounds were played to the patients using media players and headphones. Patients' physiological signs were taken immediately before the intervention and at the 30th, 60th, 90th minutes and 30 min after the procedure had finished. The physiological signs of stress assessed were heart rate, respiratory rate, and blood pressure. Data were collected over eight months from Oct 2011 to June 2012. Anxiety levels and agitation were assessed using the Faces Anxiety Scale and Richmond Agitation Sedation Scale, respectively. The experimental group had significantly lower systolic blood pressure, diastolic blood pressure, anxiety and agitation levels than the control group. These reductions increased progressively in the 30th, 60th, 90th minutes, and 30 min after the procedure had finished indicating a cumulative dose effect. N-BS can provide an effective method of decreasing potentially harmful physiological responses arising from anxiety in mechanically ventilated patients. Nurses can incorporate N-BS intervention as a non-pharmacologic intervention into the

  17. Design Procedure for Hybrid Ventilation

    DEFF Research Database (Denmark)

    Heiselberg, Per; Tjelflaat, Per Olaf

    Mechanical and natural ventilation systems have developed separately during many years. The natural next step in this development is development of ventilation concepts that utilises and combines the best features from each system into a new type of ventilation system - Hybrid Ventilation....... Buildings with hybrid ventilation often include other sustainable technologies and an energy optimisation requires an integrated approach in the design of the building and its mechanical systems. Therefore, the hybrid ventilation design procedure differs from the design procedure for conventional HVAC....... The first ideas on a design procedure for hybrid ventilation is presented and the different types of design methods, that is needed in different phases of the design process, is discussed....

  18. Industrial ventilation

    Science.gov (United States)

    Goodfellow, H. D.

    Industrial ventilation design methodology, using computers and using fluid dynamic models, is considered. It is noted that the design of a ventilation system must be incorporated into the plant design and layout at the earliest conceptual stage of the project. A checklist of activities concerning the methodology for the design of a ventilation system for a new facility is given. A flow diagram of the computer ventilation model shows a typical input, the initialization and iteration loop, and the output. The application of the fluid dynamic modeling techniques include external and internal flow fields, and individual sources of heat and contaminants. Major activities for a ventilation field test program are also addressed.

  19. Greenhouse climate : from physical processes to a dynamic model

    OpenAIRE

    Bot, G.P.A.

    1983-01-01

    In this thesis greenhouse climate has been studied as the set of environmental conditions in a greenhouse in so far as they affect crop growth and development. In chapter 2 this set has been defined in terms of temperatures and vapour pressures. Moreover we have indicated which physical processes co-operate in the greenhouse. So the dependency of the greenhouse climate on the outside weather, the physical properties of the greenhouse construction and the way ventilation and heating is perform...

  20. Optimal control of a solar greenhouse

    NARCIS (Netherlands)

    Ooteghem, van R.J.C.; Stigter, J.D.; Willigenburg, van L.G.; Straten, van G.

    2003-01-01

    A solar greenhouse has been designed that maximizes solar energy use and minimizes fossil energy consumption. It is based on a conventional greenhouse extended with a heat pump, a heat exchanger, an aquifer and ventilation with heat recovery. The aim is to minimize fossil energy consumption, while

  1. Greenhouse gas emissions from heavy-duty natural gas, hybrid, and conventional diesel on-road trucks during freight transport

    Science.gov (United States)

    Quiros, David C.; Smith, Jeremy; Thiruvengadam, Arvind; Huai, Tao; Hu, Shaohua

    2017-11-01

    Heavy-duty on-road vehicles account for 70% of all freight transport and 20% of transportation-sector greenhouse gas (GHG) emissions in the United States. This study measured three prevalent GHG emissions - carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) - from seven heavy-duty vehicles, fueled by diesel and compressed natural gas (CNG), and compliant to the MY 2007 or 2010 U.S. EPA emission standards, while operated over six routes used for freight movement in California. Total combined (tractor, trailer, and payload) weights were 68,000 ± 1000 lbs. for the seven vehicles. Using the International Panel on Climate Change (IPCC) radiative forcing values for a 100-year time horizon, N2O emissions accounted for 2.6-8.3% of total tailpipe CO2 equivalent emissions (CO2-eq) for diesel vehicles equipped with Diesel Oxidation Catalyst, Diesel Particulate Filter, and Selective Catalytic Reduction system (DOC + DPF + SCR), and CH4 emissions accounted for 1.4-5.9% of CO2-eq emissions from the CNG-powered vehicle with a three-way catalyst (TWC). N2O emissions from diesel vehicles equipped with SCR (0.17-0.30 g/mi) were an order of magnitude higher than diesel vehicles without SCR (0.013-0.023 g/mi) during highway operation. For the vehicles selected in this test program, we measured 11-22% lower CO2-eq emissions from a hybrid compared to conventional diesel vehicles during transport over lower-speed routes of the freight transport system, but 20-27% higher CO2-eq emissions during higher-speed routes. Similarly, a CNG vehicle emitted up to 15% lower CO2-eq compared to conventional diesel vehicles over more neutral-grade highway routes, but emitted up to 12% greater CO2-eq emissions over routes with higher engine loads.

  2. Controls on bacterial and archaeal community structure and greenhouse gas production in natural, mined, and restored Canadian peatlands

    Directory of Open Access Journals (Sweden)

    Nathan eBasiliko

    2013-07-01

    Full Text Available Northern peatlands are important global C reservoirs, largely because of their slow rates of microbial C mineralization. Particularly in sites that are heavily influenced by anthropogenic disturbances, there is scant information about microbial ecology and whether or not microbial community structure influences greenhouse gas production. This work characterized communities of bacteria and archaea using terminal restriction fragment length polymorphism and sequence analysis of 16S rRNA and functional genes across eight natural, mined, or restored peatlands in two locations in eastern Canada. Correlations were explored among chemical properties of peat, bacterial and archaeal community structure, and carbon dioxide and methane production rates under oxic and anoxic conditions. Bacteria and archaea similar to those found in other peat soil environments were detected. In contrast to other reports, methanogen diversity was low in our study, with only 2 groups of known or suspected methanogens. Although mining and restoration affected substrate availability and microbial activity, these land-uses did not consistently affect bacterial or archaeal community composition. In fact, larger differences were observed between the two locations and between oxic and anoxic peat samples than between mined and restored sites, with anoxic samples characterized by less detectable bacterial diversity and stronger dominance by members of the phylum Acidobacteria. There were also no apparent strong linkages between prokaryote community structure and methane or carbon dioxide production, suggesting that different organisms exhibit functional redundancy and/or that the same taxa function at very different rates when exposed to different peat substrates. In contrast to other earlier work focusing on fungal communities across similar mined and restored peatlands, bacterial and archaeal communities appeared to be more resistant or resilient to peat substrate changes brought

  3. A validated physical model of greenhouse climate

    International Nuclear Information System (INIS)

    Bot, G.P.A.

    1989-01-01

    In the greenhouse model the momentaneous environmental crop growth factors are calculated as output, together with the physical behaviour of the crop. The boundary conditions for this model are the outside weather conditions; other inputs are the physical characteristics of the crop, of the greenhouse and of the control system. The greenhouse model is based on the energy, water vapour and CO 2 balances of the crop-greenhouse system. While the emphasis is on the dynamic behaviour of the greenhouse for implementation in continuous optimization, the state variables temperature, water vapour pressure and carbondioxide concentration in the relevant greenhouse parts crop, air, soil and cover are calculated from the balances over these parts. To do this in a proper way, the physical exchange processes between the system parts have to be quantified first. Therefore the greenhouse model is constructed from submodels describing these processes: a. Radiation transmission model for the modification of the outside to the inside global radiation. b. Ventilation model to describe the ventilation exchange between greenhouse and outside air. c. The description of the exchange of energy and mass between the crop and the greenhouse air. d. Calculation of the thermal radiation exchange between the various greenhouse parts. e. Quantification of the convective exchange processes between the greenhouse air and respectively the cover, the heating pipes and the soil surface and between the cover and the outside air. f. Determination of the heat conduction in the soil. The various submodels are validated first and then the complete greenhouse model is verified

  4. Paludiculture as a chance for peatland and climate: the greenhouse gas balance of biomass production on two rewetted peatlands does not differ from the natural state

    Science.gov (United States)

    Günther, Anke; Huth, Vytas; Jurasinski, Gerald; Albrecht, Kerstin; Glatzel, Stephan

    2015-04-01

    In Europe, rising prices for farm land make it increasingly difficult for government administrations to compete with external investors during the acquisition of land for wetland conservation. Thus, adding economic value to these, otherwise "lost", areas by combining extensive land use with nature conservation efforts could increase the amount of ground available for wetland restoration. Against this background, the concept of paludiculture aims to provide biomass for multiple purposes from peatlands with water tables high enough to conserve the peat body. However, as plants have been shown to contribute to greenhouse gas exchange in peatlands, manipulating the vegetation (by harvesting, sowing etc.) might alter the effect of the restored peatlands on climate. Here, we present greenhouse gas data from two experimental paludiculture systems on formerly drained intensive grasslands in northern Germany. In a fen that has been rewetted more than 15 years ago three species of reed plants were harvested to simulate biomass production for bioenergy and as construction material. And in a peat bog that has been converted from drained grassland to a field with a controlled water table around ground surface Sphagnum mosses were cultivated to provide an alternative growing substrate for horticulture. In both systems, we determined carbon dioxide, methane, and nitrous oxide exchange using closed chambers over two years. Additionally, water and peat chemistry and environmental parameters as recorded by a weather station were analyzed. Both restored peatlands show greenhouse gas balances comparable to those of natural ecosystems. Nitrous oxide was not emitted in either system. Fluctuations of the emissions reflect changes in weather conditions across the study years. In the fen, relative emission patterns between plant species were not constant over time. We did not find a negative short-term effect of biomass harvest or Sphagnum cultivation on net greenhouse gas balances

  5. Natural upward cross-ventilation potential of a leeward sawtooth roof for a single zone building model

    NARCIS (Netherlands)

    Peren Montero, J.I.; Ramponi, R.; van Hooff, T.A.J.; Blocken, B.J.E.; Leite, B.C.C.; Schlünzen, H.

    2014-01-01

    The ventilation potential of four leeward sawtooth roof shapes (B1, C1, D1 and E1) is evaluated under normal wind incidence angle (θ = 0°). 3D Reynolds-Averaged Navier-Stokes (RANS) Computational Fluid Dynamics (CFD) simulations are performed in combination with five turbulence models and the

  6. Indoor particle dynamics in a school office: determination of particle concentrations, deposition rates and penetration factors under naturally ventilated conditions.

    Science.gov (United States)

    Cong, X C; Zhao, J J; Jing, Z; Wang, Q G; Ni, P F

    2018-05-09

    Recently, the problem of indoor particulate matter pollution has received much attention. An increasing number of epidemiological studies show that the concentration of atmospheric particulate matter has a significant effect on human health, even at very low concentrations. Most of these investigations have relied upon outdoor particle concentrations as surrogates of human exposures. However, considering that the concentration distribution of the indoor particulate matter is largely dependent on the extent to which these particles penetrate the building and on the degree of suspension in the indoor air, human exposures to particles of outdoor origin may not be equal to outdoor particle concentration levels. Therefore, it is critical to understand the relationship between the particle concentrations found outdoors and those found in indoor micro-environments. In this study, experiments were conducted using a naturally ventilated office located in Qingdao, China. The indoor and outdoor particle concentrations were measured at the same time using an optical counter with four size ranges. The particle size distribution ranged from 0.3 to 2.5 μm, and the experimental period was from April to September, 2016. Based on the experimental data, the dynamic and mass balance model based on time was used to estimate the penetration rate and deposition rate at air exchange rates of 0.03-0.25 h -1 . The values of the penetration rate and deposition velocity of indoor particles were determined to range from 0.45 to 0.82 h -1 and 1.71 to 2.82 m/h, respectively. In addition, the particulate pollution exposure in the indoor environment was analyzed to estimate the exposure hazard from indoor particulate matter pollution, which is important for human exposure to particles and associated health effects. The conclusions from this study can serve to provide a better understanding the dynamics and behaviors of airborne particle entering into buildings. And they will also highlight

  7. Noninvasive ventilation.

    Science.gov (United States)

    Rabatin, J T; Gay, P C

    1999-08-01

    Noninvasive ventilation refers to the delivery of assisted ventilatory support without the use of an endotracheal tube. Noninvasive positive pressure ventilation (NPPV) can be delivered by using a volume-controlled ventilator, a pressure-controlled ventilator, a bilevel positive airway pressure ventilator, or a continuous positive airway pressure device. During the past decade, there has been a resurgence in the use of noninvasive ventilation, fueled by advances in technology and clinical trials evaluating its use. Several manufacturers produce portable devices that are simple to operate. This review describes the equipment, techniques, and complications associated with NPPV and also the indications for both short-term and long-term applications. NPPV clearly represents an important addition to the techniques available to manage patients with respiratory failure. Future clinical trials evaluating its many clinical applications will help to define populations of patients most apt to benefit from this type of treatment.

  8. Ventilation effectiveness

    CERN Document Server

    Mathisen, Hans Martin; Nielsen, Peter V; Moser, Alfred

    2004-01-01

    Improving the ventilation effectiveness allows the indoor air quality to be significantly enhanced without the need for higher air changes in the building, thereby avoiding the higher costs and energy consumption associated with increasing the ventilation rates. This Guidebook provides easy-to-understand descriptions of the indices used to mesure the performance of a ventilation system and which indices to use in different cases.

  9. Displacement Ventilation

    DEFF Research Database (Denmark)

    Nielsen, Peter Vilhelm

    Displacement ventilation is an interesting new type of air distribution principle which should be considered in connection with design of comfort ventilation in both smal1 and large spaces. Research activities on displacement ventilation are large all over the world and new knowledge of design...... methods appears continuously. This book gives an easy introduction to the basis of displacement ventilation and the chapters are written in the order which is used in a design procedure. The main text is extended by five appendices which show some of the new research activities taking place at Aalborg...

  10. Demand Controlled Ventilation and Classroom Ventilation

    Energy Technology Data Exchange (ETDEWEB)

    Fisk, William J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Mendell, Mark J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Davies, Molly [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Eliseeva, Ekaterina [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Faulkner, David [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Hong, Tienzen [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sullivan, Douglas P. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2012-05-01

    This document summarizes a research effort on demand controlled ventilation and classroom ventilation. The research on demand controlled ventilation included field studies and building energy modeling.

  11. Demand controlled ventilation and classroom ventilation

    Energy Technology Data Exchange (ETDEWEB)

    Fisk, William J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Mendell, Mark J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Davies, Molly [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Eliseeva, Ekaterina [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Faulkner, David [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Hong, Tienzen [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sullivan, Douglas P. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2014-01-06

    This document summarizes a research effort on demand controlled ventilation and classroom ventilation. The research on demand controlled ventilation included field studies and building energy modeling.

  12. 46 CFR 194.10-25 - Ventilation.

    Science.gov (United States)

    2010-10-01

    ... magazines. (1) All integral magazines shall be provided with natural or mechanical ventilation. Design... vans shall be provided with natural ventilation sufficient to maintain the inside air temperature below... 46 Shipping 7 2010-10-01 2010-10-01 false Ventilation. 194.10-25 Section 194.10-25 Shipping COAST...

  13. Spatiotemporal variation of radon and carbon dioxide concentrations in an underground quarry: coupled processes of natural ventilation, barometric pumping and internal mixing.

    Science.gov (United States)

    Perrier, Frédéric; Richon, Patrick

    2010-04-01

    Radon-222 and carbon dioxide concentrations have been measured during several years at several points in the atmosphere of an underground limestone quarry located at a depth of 18 m in Vincennes, near Paris, France. Both concentrations showed a seasonal cycle. Radon concentration varied from 1200 to 2000 Bq m(-3) in summer to about 800-1400 Bq m(-3) in winter, indicating winter ventilation rates varying from 0.6 to 2.5 x 10(-6) s(-1). Carbon dioxide concentration varied from 0.9 to 1.0% in summer, to about 0.1-0.3% in winter. Radon concentration can be corrected for natural ventilation using temperature measurements. The obtained model also accounts for the measured seasonal variation of carbon dioxide. After correction, radon concentrations still exhibit significant temporal variation, mostly associated with the variation of atmospheric pressure, with coupling coefficients varying from -7 to -26 Bq m(-3) hPa(-1). This variation can be accounted for using a barometric pumping model, coupled with natural ventilation in winter, and including internal mixing as well. After correction, radon concentrations exhibit residual temporal variation, poorly correlated between different points, with standard deviations varying from 3 to 6%. This study shows that temporal variation of radon concentrations in underground cavities can be understood to a satisfactory level of detail using non-linear and time-dependent modelling. It is important to understand the temporal variation of radon concentrations and the limitations in their modelling to monitor the properties of natural or artificial underground settings, and to be able to assess the existence of new processes, for example associated with the preparatory phases of volcanic eruptions or earthquakes. Copyright 2009 Elsevier Ltd. All rights reserved.

  14. Spatiotemporal variation of radon and carbon dioxide concentrations in an underground quarry: coupled processes of natural ventilation, barometric pumping and internal mixing

    International Nuclear Information System (INIS)

    Perrier, Frederic; Richon, Patrick

    2010-01-01

    Radon-222 and carbon dioxide concentrations have been measured during several years at several points in the atmosphere of an underground limestone quarry located at a depth of 18 m in Vincennes, near Paris, France. Both concentrations showed a seasonal cycle. Radon concentration varied from 1200 to 2000 Bq m -3 in summer to about 800-1400 Bq m -3 in winter, indicating winter ventilation rates varying from 0.6 to 2.5 x 10 -6 s -1 . Carbon dioxide concentration varied from 0.9 to 1.0% in summer, to about 0.1-0.3% in winter. Radon concentration can be corrected for natural ventilation using temperature measurements. The obtained model also accounts for the measured seasonal variation of carbon dioxide. After correction, radon concentrations still exhibit significant temporal variation, mostly associated with the variation of atmospheric pressure, with coupling coefficients varying from -7 to -26 Bq m -3 hPa -1 . This variation can be accounted for using a barometric pumping model, coupled with natural ventilation in winter, and including internal mixing as well. After correction, radon concentrations exhibit residual temporal variation, poorly correlated between different points, with standard deviations varying from 3 to 6%. This study shows that temporal variation of radon concentrations in underground cavities can be understood to a satisfactory level of detail using non-linear and time-dependent modelling. It is important to understand the temporal variation of radon concentrations and the limitations in their modelling to monitor the properties of natural or artificial underground settings, and to be able to assess the existence of new processes, for example associated with the preparatory phases of volcanic eruptions or earthquakes.

  15. Proposed law of nature linking impacts, plume volcanism, and Milankovitch cycles to terrestrial vertebrate mass extinctions via greenhouse-embryo death coupling

    Science.gov (United States)

    Mclean, D. M.

    1994-01-01

    A greenhouse-physiological coupling killing mechanism active among mammals, birds, and reptiles has been identified. Operating via environmental thermal effects upon the maternal core-skin blood flow critical to the survival and development of embryos, it reduces the flow of blood to the uterine tract. Today, during hot summers, this phenomena kills embryos on a vast, global scale. Because of sensitivity of many mammals to modern heat, a major modern greenhouse could reduce population numbers on a global scale, and potentially trigger population collapses in the more vulnerable parts of the world. In the geological past, the killing mechanism has likely been triggered into action by greenhouse warming via impact events, plume volcanism, and Earth orbital variations (Milankovitch cycles). Earth's biosphere is maintained and molded by the flow of energy from the solar energy source to Earth and on to the space energy sink (SES). This SES energy flow maintains Earth's biosphere and its living components, as open, intermediate, dissipative, nonequilibrium systems whose states are dependent upon the rate of energy flowing through them. Greenhouse gases such as CO2 in the atmosphere influence the SES energy flow rate. Steady-state flow is necessary for global ecological stability (autopoiesis). Natural fluctuations of the C cycle such as rapid releases of CO2 from the mantle, or oceans, disrupt steady-state SES flow. These fluctuations constantly challenge the biosphere; slowdown of SES energy flow drives it toward thermodynamical equilibrium and stagnation. Fluctuations induced by impact event, mantle plume volcanism, and Milankovitch cycles can grow into structure-breaking waves triggering major perturbations of Earth's C cycle and mass extinctions. A major C cycle perturbation involves readjustment of the outer physiochemical spheres of the Earth: the atmosphere, hydrosphere, and lithosphere; and by necessity, the biosphere. A greenhouse, one manifestation of a major

  16. Natural gas based infrared heating i greenhouses. Phase II. System optimization; Naturgasbaserad infravaerme i vaexthus. Fas II. Systemoptimering

    Energy Technology Data Exchange (ETDEWEB)

    Naeslund, Mikael [Lund Inst. of Tech. (Sweden). Dept. of Heat and Power Engineering; Schuessler, Hartmut K. [Swedish Univ. of Agricultural Sciences, Alnarp (Sweden); Ljungberg, Sven-Aake [Hoegskolan i Gaevle (Sweden). Avdelningen byggnadskvalitet

    2004-01-01

    The energy use is high in greenhouses and the cost of energy is a substantial part of the plant production cost. Infrared heating (IR) has been shown to decrease the heating demand in industrial facilities and similar buildings. IR was studied with the same purpose for greenhouses. Special emphasis has also been put on the plant growth and quality. Temperature measurements showed a slightly more than 10% decrease in net heating demand compared to the reference houses in the same facility. A saving of 10-15% should be possible with some improvements. Temperature measurements at a few selected points in the infrared heated greenhouse and thermography showed differences. Repeated thermography during similar radiation conditions showed that the production tables in the infrared heated house had differences in radiation temperature and distribution caused by inhomogenous radiation from the radiating tubes. These radiation variations cause differences in in conditions and growth for cuttings and plants in later stage of growth. The thermography study also indicate that the humidity is an important factor for redistributing the radiation and ensure an optimal micro climate when infrared heaters are used in greenhouses. These differences can be reduced if the greenhouse floor layout allows radiating tubes to be located in order to make adjacent radiation fields partly overlapping. Also, burner input, excess air ratio and radiation tube and reflector design are influential for the performance. Good design criteria are discussed. Careful studies of the root development also showed differences caused by the plant location with regard to the heating tubes. The differences were reduced after reporting and further growth. One cultivation even turned out to be more compact and thus of higher quality when infrared heating was used.

  17. Ventilation Effectiveness

    DEFF Research Database (Denmark)

    Mundt, M.; Mathisen, H. M.; Moser, M.

    Improving the ventilation effectiveness allows the indoor air quality to be significantly enhanced without the need for higher air changes in the building, thereby avoiding the higher costs and energy consumption associated with increasing the ventilation rates. This Guidebook provides easy-to-un...

  18. Behovstyret ventilation

    DEFF Research Database (Denmark)

    Afshari, Alireza; Heiselberg, Per; Reinhold, Claus

    2010-01-01

    I en nylig afsluttet undersøgelse er der udført en række målinger på otte udvalgte børneinstitutioner. Fire af disse med mekanisk ventilation og fire med naturlig ventilation. Formålet er at udvide den erfaringsbaserede viden om funktionen af naturlige og mekaniske ventilationsløsninger i...

  19. Ventilation Model

    International Nuclear Information System (INIS)

    Yang, H.

    1999-01-01

    The purpose of this analysis and model report (AMR) for the Ventilation Model is to analyze the effects of pre-closure continuous ventilation in the Engineered Barrier System (EBS) emplacement drifts and provide heat removal data to support EBS design. It will also provide input data (initial conditions, and time varying boundary conditions) for the EBS post-closure performance assessment and the EBS Water Distribution and Removal Process Model. The objective of the analysis is to develop, describe, and apply calculation methods and models that can be used to predict thermal conditions within emplacement drifts under forced ventilation during the pre-closure period. The scope of this analysis includes: (1) Provide a general description of effects and heat transfer process of emplacement drift ventilation. (2) Develop a modeling approach to simulate the impacts of pre-closure ventilation on the thermal conditions in emplacement drifts. (3) Identify and document inputs to be used for modeling emplacement ventilation. (4) Perform calculations of temperatures and heat removal in the emplacement drift. (5) Address general considerations of the effect of water/moisture removal by ventilation on the repository thermal conditions. The numerical modeling in this document will be limited to heat-only modeling and calculations. Only a preliminary assessment of the heat/moisture ventilation effects and modeling method will be performed in this revision. Modeling of moisture effects on heat removal and emplacement drift temperature may be performed in the future

  20. Liquid Ventilation

    Directory of Open Access Journals (Sweden)

    Qutaiba A. Tawfic

    2011-01-01

    Full Text Available Mammals have lungs to breathe air and they have no gills to breath liquids. When the surface tension at the air-liquid interface of the lung increases, as in acute lung injury, scientists started to think about filling the lung with fluid instead of air to reduce the surface tension and facilitate ventilation. Liquid ventilation (LV is a technique of mechanical ventilation in which the lungs are insufflated with an oxygenated perfluorochemical liquid rather than an oxygen-containing gas mixture. The use of perfluorochemicals, rather than nitrogen, as the inert carrier of oxygen and carbon dioxide offers a number of theoretical advantages for the treatment of acute lung injury. In addition, there are non-respiratory applications with expanding potential including pulmonary drug delivery and radiographic imaging. The potential for multiple clinical applications for liquid-assisted ventilation will be clarified and optimized in future. Keywords: Liquid ventilation; perfluorochemicals; perfluorocarbon; respiratory distress; surfactant.

  1. Ventilative Cooling

    DEFF Research Database (Denmark)

    Heiselberg, Per Kvols; Kolokotroni, Maria

    This report, by venticool, summarises the outcome of the work of the initial working phase of IEA ECB Annex 62 Ventilative Cooling and is based on the findings in the participating countries. It presents a summary of the first official Annex 62 report that describes the state-of-the-art of ventil......This report, by venticool, summarises the outcome of the work of the initial working phase of IEA ECB Annex 62 Ventilative Cooling and is based on the findings in the participating countries. It presents a summary of the first official Annex 62 report that describes the state......-of-the-art of ventilative cooling potentials and limitations, its consideration in current energy performance regulations, available building components and control strategies and analysis methods and tools. In addition, the report provides twenty six examples of operational buildings using ventilative cooling ranging from...

  2. Greener greenhouses

    Energy Technology Data Exchange (ETDEWEB)

    Paksoy, Halime; Turgut, Bekir; Beyhan, Beyza; Dasgan, H. Yildiz; Evliya, Hunay; Abak, Kazim; Bozdag, Saziye

    2010-09-15

    Agricultural greenhouses are solution to the increased demand for higher production yields, facilitating off season cultivation and allowing the growth of certain varieties in areas where it was not possible earlier. Heating and/or cooling system, required to maintain the inside micro-climate in greenhouses mostly rely on fossil fuels and/or electricity. This paper aims to discuss the 'greener' solutions for heating and cooling systems of greenhouses based on different thermal energy storage concepts. Results from a greenhouse Aquifer Thermal Energy Storage (ATES) application in Turkey producing tomatoes with zero fossil fuels and up to 40% higher yield are presented.

  3. Temperature Field-Wind Velocity Field Optimum Control of Greenhouse Environment Based on CFD Model

    Directory of Open Access Journals (Sweden)

    Yongbo Li

    2014-01-01

    Full Text Available The computational fluid dynamics technology is applied as the environmental control model, which can include the greenhouse space. Basic environmental factors are set to be the control objects, the field information is achieved via the division of layers by height, and numerical characteristics of each layer are used to describe the field information. Under the natural ventilation condition, real-time requirements, energy consumption, and distribution difference are selected as index functions. The optimization algorithm of adaptive simulated annealing is used to obtain optimal control outputs. A comparison with full-open ventilation shows that the whole index can be reduced at 44.21% and found that a certain mutual exclusiveness exists between the temperature and velocity field in the optimal course. All the results indicate that the application of CFD model has great advantages to improve the control accuracy of greenhouse.

  4. Numerical investigations of buoyancy-driven natural ventilation in a simple atrium building and its effect on the thermal comfort conditions

    International Nuclear Information System (INIS)

    Hussain, Shafqat; Oosthuizen, Patrick H.

    2012-01-01

    In the present study use of solar-assisted buoyancy-driven natural ventilation in a simple atrium building is explored numerically with particular emphasis on the thermal comfort conditions in the building. Initially various geometric configurations of the atrium space were considered in order to investigate airflows and temperature distributions in the building using a validated computational fluid dynamics (CFD) model. The Reynolds Averaged Navier–Stokes (RANS) modelling approach with the SST-k–ω turbulence model and the Discrete Transfer Radiation Model (DTRM) was used for the investigations. The steady-state governing equations were solved using a commercial CFD solver FLUENT © . From the numerical results obtained, it was noted that an atrium space integrated with a solar chimney would be a relatively better option to be used in an atrium building. In the geometry selected, the performance of the building in response to various changes in design parameters was investigated. The produced airflows and temperature distributions were then used to evaluate indoor thermal comfort conditions in terms of the thermal comfort indices, i.e. the well-known predicted mean vote (PMV) index, its modifications especially for natural ventilation, predicted percent dissatisfied (PPD) index and Percent dissatisfied (PD) factor due to draft. It was found that the thermal conditions in the occupied areas of the building developed as a result of the use of solar-assisted buoyancy-driven ventilation for the particular values of the design parameters selected are mostly in the comfortable zone. Finally, it is demonstrated that the proposed methodology leads to reliable thermal comfort predictions, while the effect of various design variables on the performance of the building is easily recognized. - Highlights: ► Numerical investigations were carried for the use of buoyancy-driven displacement ventilation in a simple atrium building. ► Effect of various atrium

  5. Residential greenhouse

    Energy Technology Data Exchange (ETDEWEB)

    1985-02-01

    The following report examines the technical and economic viability of residential greenhouse additions in Whitehorse, Yukon. The greenhouse was constructed using the south facing wall of an existing residence as a common wall. Total construction costs were $18,000, including labour. Annual fuel demand for the residence has been reduced by about 10 per cent for an annual saving of $425. In addition, produce to the value of $1,000 is grown annually in the greenhouse for domestic consumption and commercial resale. Typically the greenhouse operates for nine months each year. There is a net thermal loss during the months of November, December and January as a result of the large area of glazing. As well as supplementing the heating supply solar greenhouses can provide additional cash crops which can be used to offset the cost of construction. Humidity problems are minimal and can be dealt with by exhausting high humidity air. One system which has been considered for the greenhouse is to use a standard residential heat pump to remove excess moisture and to pump heat into the house. This would have a secondary benefit of excluding the need to circulate greenhouse air through the house. Thus any allergenic reactions to the greenhouse air would be prevented. 8 refs., 3 figs, 2 tabs.

  6. Estimating Greenhouse Gas Emissions Level of A Natural Gas Pipeline – Case Study from A to B Point in West Java-Indonesia

    Directory of Open Access Journals (Sweden)

    Dianita Cindy

    2016-01-01

    Full Text Available Indonesia is one of the highest greenhouse emitters in the world. As a response of this problem, Indonesia declared the national action plan to focus on national greenhouse gas (GHG reduction by 26 % by 2020. To achieve this target, Government puts energy sector as one of the top priorities since it is the second strongest contributor to national GHG emissions. The main purpose of this paper is to apply the method of fugitive emissions calculation to the existing natural gas pipeline in Indonesia. Fugitive emissions are the major component of GHG emissions from natural gas systems and methane (CH4, the primary component of natural gas pipeline, is a potent GHG. Tiered approaches from Interstate Natural Gas Association of America (INGAA are implemented in this paper as the estimation guidelines. A case study of a natural gas pipeline system in Indonesia is analyzed to compare the GHG emissions level resulted from Tier 1 and Tier 2 methods. In these methods, the input data are pipeline length, the number of compressor stations, and the number of meter and pressure regulation stations. In this case, the GHG emissions level of Tier 2 is significantly different from Tier 1. The variation of pipeline length shows that for the length under 479.2 miles, Tier 1 gives lower amount of CO2 equivalent than Tier 2. The differences of these estimation methods and results can be furtherly developed to provide relevant information and recommendation for the Companies and Government to record the emissions level from natural gas transmission pipeline according to their needs and purposes.

  7. Role of natural gas in meeting an electric sector emissions reduction strategy and effects on greenhouse gas emissions

    Science.gov (United States)

    With advances in natural gas extraction technologies, there is an increase in availability of domestic natural gas, and natural gas is gaining a larger share of use as a fuel in electricity production. At the power plant, natural gas is a cleaner burning fuel than coal, but unce...

  8. 46 CFR 98.25-75 - Ventilation.

    Science.gov (United States)

    2010-10-01

    ... shall be fitted with efficient natural or mechanical ventilation. (b) Enclosed compartments in which... 46 Shipping 4 2010-10-01 2010-10-01 false Ventilation. 98.25-75 Section 98.25-75 Shipping COAST... Ventilation. (a) All enclosed spaces containing cargo tanks fitted with bottom outlet connections shall be...

  9. Ventilation strategies and indoor environment in classrooms

    DEFF Research Database (Denmark)

    Zhang, Chen; Liu, Li

    2017-01-01

    Compared with the other building types, the school building has much higher occupancy density and ventilation demand. In Demark, most of the school buildings are ventilated by natural manner. There is a risk of poor indoor environment associated with the lack of ventilation system or insufficient...

  10. A Synoptic View of the Ventilation and Circulation of Antarctic Bottom Water from Chlorofluorocarbons and Natural Tracers

    Science.gov (United States)

    Purkey, Sarah G.; Smethie, William M.; Gebbie, Geoffrey; Gordon, Arnold L.; Sonnerup, Rolf E.; Warner, Mark J.; Bullister, John L.

    2018-01-01

    Antarctic Bottom Water (AABW) is the coldest, densest, most prolific water mass in the global ocean. AABW forms at several distinct regions along the Antarctic coast and feeds into the bottom limb of the meridional overturning circulation, filling most of the global deep ocean. AABW has warmed, freshened, and declined in volume around the globe in recent decades, which has implications for the global heat and sea level rise budgets. Over the past three decades, the use of tracers, especially time-varying tracers such as chlorofluorocarbons, has been essential to our understanding of the formation, circulation, and variability of AABW. Here, we review three decades of temperature, salinity, and tracer data and analysis that have led to our current knowledge of AABW and how the southern component of deep-ocean ventilation is changing with time.

  11. Greenhouse effect

    International Nuclear Information System (INIS)

    1992-01-01

    This special issue is devoted to the greenhouse effect and reviews the possible climate change by mankind, paleoclimates, climate models, measurement of terrestrial temperature, CO 2 concentration and energy policy

  12. Ventilation of radioactive enclosures

    International Nuclear Information System (INIS)

    Caminade, F.; Laurent, H.

    1957-01-01

    Mechanical, physical and chemical manipulations on radioactive products must be carried out in properly ventilated enclosed places. The air extracted can only be discharged into the atmosphere after a correct filtration. The power of the ventilation systems is a function of the dimensions and purpose of the enclosure? The choice of types of filter is determined by the physical state and chemical nature of the radioactive materials to be manipulated. This study deals with the individual equipment of small installations: glove boxes, manipulation boxes with outside control and, if necessary, production chambers (maximum useful volume: 5 m 3 ). The performances of three types of 'ventilators', and the modifications provided by the addition of filters, are measured and compared. (author) [fr

  13. Liquid ventilation.

    Science.gov (United States)

    Sarkar, Suman; Paswan, Anil; Prakas, S

    2014-01-01

    Human have lungs to breathe air and they have no gills to breath liquids like fish. When the surface tension at the air-liquid interface of the lung increases as in acute lung injury, scientists started to think about filling the lung with fluid instead of air to reduce the surface tension and facilitate ventilation. Liquid ventilation (LV) is a technique of mechanical ventilation in which the lungs are insufflated with an oxygenated perfluorochemical liquid rather than an oxygen-containing gas mixture. The use of perfluorochemicals, rather than nitrogen as the inert carrier of oxygen and carbon dioxide offers a number of advantages for the treatment of acute lung injury. In addition, there are non-respiratory applications with expanding potential including pulmonary drug delivery and radiographic imaging. It is well-known that respiratory diseases are one of the most common causes of morbidity and mortality in intensive care unit. During the past few years several new modalities of treatment have been introduced. One of them and probably the most fascinating, is of LV. Partial LV, on which much of the existing research has concentrated, requires partial filling of lungs with perfluorocarbons (PFC's) and ventilation with gas tidal volumes using conventional mechanical ventilators. Various physico-chemical properties of PFC's make them the ideal media. It results in a dramatic improvement in lung compliance and oxygenation and decline in mean airway pressure and oxygen requirements. No long-term side-effect reported.

  14. Efeito da ventilação natural e mecânica sobre o desempenho de porcas em lactação Effect of natural and mechanical ventilation on performance of lactation sows

    Directory of Open Access Journals (Sweden)

    Carlos Cláudio Perdomo

    1999-04-01

    Full Text Available O controle efetivo da ventilação é fundamental para maximizar o bem-estar, o desempenho e a saúde dos suínos. Este trabalho avaliou o efeito de sistemas de ventilação natural através de janelas basculantes (com e sem exaustor eólico e mecânica, dimensionados para a retirada da carga térmica incidente, nas condições de verão, sobre o condicionamento ambiental e desempenho de porcas em lactação, em Concórdia, SC, no período de 1991/92. Embora tenha sido observado efeito da estação do ano (P0,05. O condicionamento térmico no verão foi considerado estressante em todos os sistemas, com temperaturas (Ti elevadas (> 22,0°C, taxas de ventilação (Vi deficientes (13 dias, em comparação com as observadas no inverno: Ti (Air movement has been shown to influence performance of confined swine, and that appropriate air flow is fundamental to better animal comfort, and to minimize sanitary problems. The effect of window with and without aeolic exhaustion and mechanical ventilation designed only for hot season was evaluated at Concordia, SC, Brazil, during 1991/92. Although effect of season (P0.05. The hot season environment was stressing for animals, due to higher environment temperature (Ti (>22.0°C, low air velocity (Vi (13 days during the hot season as compared to cold season: Ti (<19.0°C, Vi (<0.1 m/s, CR (<4.57 kg/day and IDC (<7 days, respectively. In conclusion, ventilation systems based only on natural openings are sufficient for cold season, but are not for hot season due to increase in the ventilation needs.

  15. Personalized ventilation

    DEFF Research Database (Denmark)

    Melikov, Arsen Krikor

    2004-01-01

    microenvironment. Furthermore, HVAC systems should be designed to protect occupants from airborne transmission of infectious agents that may be present in exhaled air. Personalized ventilation is a new development in the field of HVAC and has the potential to fulfill the above requirements. This paper reviews...... existing knowledge on performance of personalized ventilation (PV) and on human response to it. The airflow interaction in the vicinity of the human body is analyzed and its impact on thermal comfort and inhaled air quality is discussed together with control strategies and the application of PV in practice...

  16. Role of natural gas in meeting an electric sector emissions reduction strategy and effects on greenhouse gas emissions

    International Nuclear Information System (INIS)

    Lenox, Carol; Kaplan, P. Ozge

    2016-01-01

    With advances in natural gas extraction technologies, there is an increase in the availability of domestic natural gas, and natural gas is gaining a larger share of use as a fuel in electricity production. At the power plant, natural gas is a cleaner burning fuel than coal, but uncertainties exist in the amount of methane leakage occurring upstream in the extraction and production of natural gas. At higher leakage levels, the additional methane emissions could offset the carbon dioxide emissions reduction benefit of switching from coal to natural gas. This analysis uses the MARKAL linear optimization model to compare the carbon emissions profiles and system-wide global warming potential of the U.S. energy system over a series of model runs in which the power sector is required to meet a specific carbon dioxide reduction target across a number of scenarios in which the availability of natural gas changes. Scenarios are run with carbon dioxide emissions and a range of upstream methane emission leakage rates from natural gas production along with upstream methane and carbon dioxide emissions associated with production of coal and oil. While the system carbon dioxide emissions are reduced in most scenarios, total carbon dioxide equivalent emissions show an increase in scenarios in which natural gas prices remain low and, simultaneously, methane emissions from natural gas production are higher. - Highlights: • MARKAL analysis of energy system GHG emissions reduction scenarios. • High methane leakage can eliminate the benefit that natural gas brings over coal. • A robust GHG reduction strategy takes into account upstream emissions for all fuels.

  17. Greenhouse effect: Myth or reality

    International Nuclear Information System (INIS)

    Martin, J.L.

    1992-01-01

    This paper debates on greenhouse effect controversy. Natural greenhouse effect is beneficent but additional greenhouse effect, in relation with human activities, can present a major risk for humanity. However an international agreement is difficult owing to the enormous costs which could not be endured by South economies. A tax on carbon dioxide emissions would have for consequence a wave of industrial delocalizations without precedent with important unemployment in Europe and no impact on additional greenhouse effect because it is a radiative effect and it is not a classic local chemical pollution. 11 refs., 10 figs

  18. Displacement Ventilation

    DEFF Research Database (Denmark)

    Bjørn, Erik; Mattsson, Magnus; Sandberg, Mats

    Full-scale experiments were made in a displacement ventilated room with two breathing thermal manikins to study the effect of movements and breathing on the vertical contaminant distribution, and on the personal exposure of occupants. Concentrations were measured with tracer gas equipment...

  19. Mixing Ventilation

    DEFF Research Database (Denmark)

    Kandzia, Claudia; Kosonen, Risto; Melikov, Arsen Krikor

    In this guidebook most of the known and used in practice methods for achieving mixing air distribution are discussed. Mixing ventilation has been applied to many different spaces providing fresh air and thermal comfort to the occupants. Today, a design engineer can choose from large selection...

  20. Small-scale electricity generating facilities from natural gas : a measure to mitigate the greenhouse effect; Microgeneracion de energia con gas natural: una medida efectiva para mitigar el cambio climatico

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez, A. M.

    2002-07-01

    The forthcoming liberalization of the gas and electricity markets in Europe, in conjunction with the increase of the global energy consumption in the near future are enabling the development of natural gas alternatives to traditional large-scale centralized power plants. They emerged from research suggesting that the use of small-scale electricity generating facilities dispersed throughout the electrical network, provides the electricity system with measurable technical, economic and environmental benefits. In this sense, the distributed generation powered by cogeneration systems offers the biggest measure to mitigate the greenhouse effect due to the carbon dioxide. (Author)

  1. A decade of boreal rich fen greenhouse gas fluxes in response to natural and experimental water table variability

    Science.gov (United States)

    Olefeldt, David; Euskirchen, Eugénie S.; Harden, Jennifer W.; Kane, Evan S.; McGuire, A. David; Waldrop, Mark P.; Turetsky, Merritt R.

    2017-01-01

    Rich fens are common boreal ecosystems with distinct hydrology, biogeochemistry and ecology that influence their carbon (C) balance. We present growing season soil chamber methane emission (FCH4), ecosystem respiration (ER), net ecosystem exchange (NEE) and gross primary production (GPP) fluxes from a 9-years water table manipulation experiment in an Alaskan rich fen. The study included major flood and drought years, where wetting and drying treatments further modified the severity of droughts. Results support previous findings from peatlands that drought causes reduced magnitude of growing season FCH4, GPP and NEE, thus reducing or reversing their C sink function. Experimentally exacerbated droughts further reduced the capacity for the fen to act as a C sink by causing shifts in vegetation and thus reducing magnitude of maximum growing season GPP in subsequent flood years by ~15% compared to control plots. Conversely, water table position had only a weak influence on ER, but dominant contribution to ER switched from autotrophic respiration in wet years to heterotrophic in dry years. Droughts did not cause inter-annual lag effects on ER in this rich fen, as has been observed in several nutrient-poor peatlands. While ER was dependent on soil temperatures at 2 cm depth, FCH4 was linked to soil temperatures at 25 cm. Inter-annual variability of deep soil temperatures was in turn dependent on wetness rather than air temperature, and higher FCH4 in flooded years was thus equally due to increased methane production at depth and decreased methane oxidation near the surface. Short-term fluctuations in wetness caused significant lag effects on FCH4, but droughts caused no inter-annual lag effects on FCH4. Our results show that frequency and severity of droughts and floods can have characteristic effects on the exchange of greenhouse gases, and emphasize the need to project future hydrological regimes in rich fens.

  2. Energy demand hourly simulations and energy saving strategies in greenhouses for the Mediterranean climate

    Science.gov (United States)

    Priarone, A.; Fossa, M.; Paietta, E.; Rolando, D.

    2017-01-01

    This research has been devoted to the selection of the most favourable plant solutions for ventilation, heating and cooling, thermo-hygrometric control of a greenhouse, in the framework of the energy saving and the environmental protection. The identified plant solutions include shading of glazing surfaces, natural ventilation by means of controlled opening windows, forced convection of external air and forced convection of air treated by the HVAC system for both heating and cooling. The selected solution combines HVAC system to a Ground Coupled Heat Pump (GCHP), which is an innovative renewable technology applied to greenhouse buildings. The energy demand and thermal loads of the greenhouse to fulfil the requested internal design conditions have been evaluated through an hourly numerical simulation, using the Energy Plus (E-plus) software. The overall heat balance of the greenhouse also includes the latent heat exchange due to crop evapotranspiration, accounted through an original iterative calculation procedure that combines the E-plus dynamic simulations and the FAO Penman-Monteith method. The obtained hourly thermal loads have been used to size the borehole field for the geothermal heat pump by using a dedicated GCHP hourly simulation tool.

  3. Greenhouse effect

    International Nuclear Information System (INIS)

    Lepetit, J.P.

    1992-01-01

    This book speaks about the growth of greenhouse gases content in the atmosphere and try to forecast the different scenarios which may happen. But, in spite of international cooperation and coordinated research programs, nobody owns the answer. So possible future climatic changes depend on the behavior of the concerned actors. A review of energy policy driven by USA, Japan, Sweden, United Kingdom and Federal Republic of Germany is given. Political management of this file and public opinion in front of greenhouse effect are also described. 7 refs., 3 figs., 6 tabs

  4. Greenhouse Warming Research

    DEFF Research Database (Denmark)

    Sørensen, Bent Erik

    2016-01-01

    The changing greenhouse effect caused by natural and anthropogenic causes is explained and efforts to model the behavior of the near-surface constituents of the Earth's land, ocean and atmosphere are discussed. Emissions of various substances and other aspects of human activity influence...... the greenhouse warming, and the impacts of the warming may again impact the wellbeing of human societies. Thus physical modeling of the near-surface ocean-soil-atmosphere system cannot be carried out without an idea of the development of human activities, which is done by scenario analysis. The interactive...

  5. Comparison of greenhouse and 32P isotopic laboratory methods for evaluating the agronomic effectiveness of natural and modified rock phosphates in some acid soils of Ghana

    International Nuclear Information System (INIS)

    Owusu-Bennoah, E.; Zapata, F.; Fardeau, J.C.

    2002-01-01

    Phosphorus deficiency is one of the major constraints for normal plant growth and crop yields in the acid soils of Ghana and therefore addition of P inputs is required for sustainable crop production. This is often difficult, if not impossible for small-scale farmers due to the high cost of mineral P fertilizers and limited access to fertilizer supplies. Direct application of finely ground phosphate rocks (PRs) and their modified forms have been recommended as alternatives for P fertilization. The direct application of the natural and modified PRs to these acid soils implies the need to predict their agronomic effectiveness of the PRs in the simplest and most cost-effective manner. In this study the classical greenhouse pot experiment was compared to the 32 P isotopic kinetics laboratory method for evaluating the agronomic effectiveness of natural and modified Togo PR in six highly weathered Oxisols from southwest Ghana. In the 32 P isotopic kinetics laboratory experiment the six soil samples were each fertilised at the rate of 50 mg P kg -1 soil in the form of triple superphosphate (TSP), Togo PAPR-50%, and Togo PR, respectively. Controls without P amendment were also included. Isotopic exchange kinetics experiments were carried out on two sets of samples, immediately after P fertilizer additions (without incubation) and after 6 weeks of incubation under wet conditions and at a room temperature of 25 deg C. In the greenhouse pot experiment, P fertilizers in the form of Togo PR, Togo PAPR, Mali PR and TSP were each applied to the six soils at rates equivalent to 0, 30, 60, and 120 kg P ha -1 , respectively. The P fertilizers were mixed with the soils and maize (Zea mays L.) variety Obatanpa was grown for 42 days before harvest. The isotopic kinetics data of the control samples indicated that 5 of the studied soils had very low P fertility status as reflected by their low P concentrations in solution (C P -1 ) and low exchangeable P (E 1 min -1 ). The capacity

  6. Receding Horizon Optimal Control of a Solar Greenhouse

    NARCIS (Netherlands)

    Ooteghem, van R.J.C.; Willigenburg, van L.G.; Straten, van G.

    2005-01-01

    A solar greenhouse has been designed that maximizes solar energy use and minimizes fossil energy consumption. It is based on a conventional Venlo greenhouse extended with a heat pump, a heat exchanger, an aquifer and ventilation with heat recovery. The goal is to minimize fossil energy consumption,

  7. Greenhouse gases and global warming

    International Nuclear Information System (INIS)

    1995-01-01

    From previous articles we have learned about the complexities of our environment, its atmosphere and its climate system. we have also learned that climate change and, therefore global warm and cool periods are naturally occurring phenomena. Moreover, all scientific evidence suggests that global warming, are likely to occur again naturally in the future. However, we have not yet considered the role of the rates of climate change in affecting the biosphere. It appears that how quickly the climate changes may be more important than the change itself. In light of this concern, let us now consider the possibility that, is due to human activity. We may over the next century experience global warming at rates and magnitudes unparalleled in recent geologic history. The following questions are answered; What can we learn from past climates? What do we know about global climates over the past 100 years? What causes temperature change? What are the greenhouse gases? How much have concentration of greenhouse gases increased in recent years? Why are increases in concentrations of greenhouse of concern? What is the e nhanced greenhouse effect ? How can human activity impact the global climate? What are some reasons for increased concentrations of greenhouse gases? What are fossil fuel and how do they transform into greenhouse gases? Who are the biggest emitters of greenhouse gases? Why are canada per capita emissions of greenhouse gases relatively high? (Author)

  8. To Investigate the Influence of Building Envelope and Natural Ventilation on Thermal Heat Balance in Office Buildings in Warm and Humid Climate

    Science.gov (United States)

    Kini, Pradeep G.; Garg, Naresh Kumar; Kamath, Kiran

    2017-07-01

    India’s commercial building sector is witnessing robust growth. India continues to be a key growth market among global corporates and this is reflective in the steady growth in demand for prime office space. A recent trend that has been noted is the increase in demand for office spaces not just in major cities but also in smaller tier II and Tier III cities. Growth in the commercial building sector projects a rising trend of energy intensive mechanical systems in office buildings in India. The air conditioning market in India is growing at 25% annually. This is due to the ever increasing demand to maintain thermal comfort in tropical regions. Air conditioning is one of the most energy intensive technologies which are used in buildings. As a result India is witnessing significant spike in energy demand and further widening the demand supply gap. Challenge in India is to identify passive measures in building envelope design in office buildings to reduce the cooling loads and conserve energy. This paper investigates the overall heat gain through building envelope components and natural ventilation in warm and humid climate region through experimental and simulation methods towards improved thermal environmental performance.

  9. 46 CFR 177.600 - Ventilation of enclosed and partially enclosed spaces.

    Science.gov (United States)

    2010-10-01

    ... ventilation system unless natural ventilation in all ordinary weather conditions is satisfactory to the OCMI... 46 Shipping 7 2010-10-01 2010-10-01 false Ventilation of enclosed and partially enclosed spaces... PASSENGER VESSELS (UNDER 100 GROSS TONS) CONSTRUCTION AND ARRANGEMENT Ventilation § 177.600 Ventilation of...

  10. A refined protocol for calculating air flow rate of naturally-ventilated broiler barns based on co2 mass balance

    Directory of Open Access Journals (Sweden)

    Luciano Barreto-Mendes

    2014-01-01

    Full Text Available Este estudio se realizó para evaluar protocolos relativamente simples para el monitoreo de la tasa de ventilación (TV en instalaciones pecuarias con ventilación natural (ENV. Los protocolos de ensayo se aplicaron primero a una instalación de pollos de engorde mecánicamente ventilada (EMV, donde TV se estimó con mayor precisión y luego se utilizaron para calcular la TV en la ENV. Las concentraciones de CO2 se midieron con dos esquemas de muestreo diferentes: (S1 la media de las mediciones al interior y a lo largo de la longitud de la instalación a dos alturas de 0,5 m y 1,5 m del suelo; y (S2 igual que la anterior pero con las mediciones de concentración fueron realizadas únicamente a 0,5 m del suelo. La tasa de producción de CO2 metabólico dinámico de las aves se predijo con dos algoritmos diferentes: (A1 el mantenimiento constante durante los periodos de luz y oscuridad, y (A2 que varía con la actividad de los animales sobre una base horaria. Los resultados demostraron que la combinación de S2 con A1 o A2 presentó la mejor estimación de TV en el ENV.

  11. The natural chlorine cycle - Formation of the carcinogenic and greenhouse gas compound chloroform in drinking water reservoirs.

    Science.gov (United States)

    Forczek, Sándor T; Pavlík, Milan; Holík, Josef; Rederer, Luděk; Ferenčík, Martin

    2016-08-01

    Chlorine cycle in natural ecosystems involves formation of low and high molecular weight organic compounds of living organisms, soil organic matter and atmospherically deposited chloride. Chloroform (CHCl3) and adsorbable organohalogens (AOX) are part of the chlorine cycle. We attempted to characterize the dynamical changes in the levels of total organic carbon (TOC), AOX, chlorine and CHCl3 in a drinking water reservoir and in its tributaries, mainly at its spring, and attempt to relate the presence of AOX and CHCl3 with meteorological, chemical or biological factors. Water temperature and pH influence the formation and accumulation of CHCl3 and affect the conditions for biological processes, which are demonstrated by the correlation between CHCl3 and ΣAOX/Cl(-) ratio, and also by CHCl3/ΣAOX, CHCl3/AOXLMW, CHCl3/ΣTOC, CHCl3/TOCLMW and CHCl3/Cl(-) ratios in different microecosystems (e.g. old spruce forest, stagnant acidic water, humid and warm conditions with high biological activity). These processes start with the biotransformation of AOX from TOC, continue via degradation of AOX to smaller molecules and further chlorination, and finish with the formation of small chlorinated molecules, and their subsequent volatilization and mineralization. The determined concentrations of chloroform result from a dynamic equilibrium between its formation and degradation in the water; in the Hamry water reservoir, this results in a total amount of 0.1-0.7 kg chloroform and 5.2-15.4 t chloride. The formation of chloroform is affected by Cl(-) concentration, by concentrations and ratios of biogenic substrates (TOC and AOX), and by the ratios of the substrates and the product (feedback control by chloroform itself). Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Ventilator-driven xenon ventilation studies

    International Nuclear Information System (INIS)

    Chilcoat, R.T.; Thomas, F.D.; Gerson, J.I.

    1984-01-01

    A modification of a common commercial Xe-133 ventilation device is described for mechanically assisted ventilation imaging. The patient's standard ventilator serves as the power source controlling the ventilatory rate and volume during the xenon study, but the gases in the two systems are not intermixed. This avoids contamination of the ventilator with radioactive xenon. Supplemental oxygen and positive end-expiratory pressure (PEEP) are provided if needed. The system can be converted quickly for conventional studies with spontaneous respiration

  13. Greenhouse intelligent control system based on microcontroller

    Science.gov (United States)

    Zhang, Congwei

    2018-04-01

    As one of the hallmarks of agricultural modernization, intelligent greenhouse has the advantages of high yield, excellent quality, no pollution and continuous planting. Taking AT89S52 microcontroller as the main controller, the greenhouse intelligent control system uses soil moisture sensor, temperature and humidity sensors, light intensity sensor and CO2 concentration sensor to collect measurements and display them on the 12864 LCD screen real-time. Meantime, climate parameter values can be manually set online. The collected measured values are compared with the set standard values, and then the lighting, ventilation fans, warming lamps, water pumps and other facilities automatically start to adjust the climate such as light intensity, CO2 concentration, temperature, air humidity and soil moisture of the greenhouse parameter. So, the state of the environment in the greenhouse Stabilizes and the crop grows in a suitable environment.

  14. Development of a Residential Integrated Ventilation Controller

    Energy Technology Data Exchange (ETDEWEB)

    Staff Scientist; Walker, Iain; Sherman, Max; Dickerhoff, Darryl

    2011-12-01

    The goal of this study was to develop a Residential Integrated Ventilation Controller (RIVEC) to reduce the energy impact of required mechanical ventilation by 20percent, maintain or improve indoor air quality and provide demand response benefits. This represents potential energy savings of about 140 GWh of electricity and 83 million therms of natural gas as well as proportional peak savings in California. The RIVEC controller is intended to meet the 2008 Title 24 requirements for residential ventilation as well as taking into account the issues of outdoor conditions, other ventilation devices (including economizers), peak demand concerns and occupant preferences. The controller is designed to manage all the residential ventilation systems that are currently available. A key innovation in this controller is the ability to implement the concept of efficacy and intermittent ventilation which allows time shifting of ventilation. Using this approach ventilation can be shifted away from times of high cost or high outdoor pollution towards times when it is cheaper and more effective. Simulations, based on the ones used to develop the new residential ventilation requirements for the California Buildings Energy code, were used to further define the specific criteria and strategies needed for the controller. These simulations provide estimates of the energy, peak power and contaminant improvement possible for different California climates for the various ventilation systems. Results from a field test of the prototype controller corroborate the predicted performance.

  15. Diffuse Ceiling Ventilation

    DEFF Research Database (Denmark)

    Zhang, Chen; Yu, Tao; Heiselberg, Per Kvols

    with conventional ventilation systems (mixing or displacement ventilation), diffuse ceiling ventilation can significantly reduce or even eliminate draught risk in the occupied zone. Moreover, this ventilation system presents a promising opportunity for energy saving, because of the low pressure loss, extended free...

  16. Diffuse ceiling ventilation

    DEFF Research Database (Denmark)

    Zhang, Chen

    Diffuse ceiling ventilation is an innovative ventilation concept where the suspended ceiling serves as air diffuser to supply fresh air into the room. Compared with conventional ventilation systems, diffuse ceiling ventilation can significantly reduce or even eliminate draught risk due to the low...

  17. Control of Airborne Infectious Diseases in Ventilated Spaces

    DEFF Research Database (Denmark)

    Nielsen, Peter V.

    2009-01-01

    We protect ourselves from airborne cross-infection in the indoor environment by supplying fresh air to a room by natural or mechanical ventilation. The air is distributed in the room according to different principles: mixing ventilation, displacement ventilation, etc. A large amount of air...... to have high ventilation effectiveness. Furthermore, personalized ventilation may reduce the risk of cross-infection, and in some cases, it can also reduce the source of infection. Personalized ventilation can especially be used in hospital wards, aircraft cabins and, in general, where people are in fixed...

  18. Variable mechanical ventilation.

    Science.gov (United States)

    Fontela, Paula Caitano; Prestes, Renata Bernardy; Forgiarini, Luiz Alberto; Friedman, Gilberto

    2017-01-01

    To review the literature on the use of variable mechanical ventilation and the main outcomes of this technique. Search, selection, and analysis of all original articles on variable ventilation, without restriction on the period of publication and language, available in the electronic databases LILACS, MEDLINE®, and PubMed, by searching the terms "variable ventilation" OR "noisy ventilation" OR "biologically variable ventilation". A total of 36 studies were selected. Of these, 24 were original studies, including 21 experimental studies and three clinical studies. Several experimental studies reported the beneficial effects of distinct variable ventilation strategies on lung function using different models of lung injury and healthy lungs. Variable ventilation seems to be a viable strategy for improving gas exchange and respiratory mechanics and preventing lung injury associated with mechanical ventilation. However, further clinical studies are necessary to assess the potential of variable ventilation strategies for the clinical improvement of patients undergoing mechanical ventilation.

  19. VENTILATION NEEDS DURING CONSTRUCTION

    International Nuclear Information System (INIS)

    C.R. Gorrell

    1998-01-01

    The purpose of this analysis is to determine ventilation needs during construction and development of the subsurface repository and develop systems to satisfy those needs. For this analysis, construction is defined as pre-emplacement excavation and development is excavation that takes place simultaneously with emplacement. The three options presented in the ''Overall Development and Emplacement Ventilation Systems'' analysis (Reference 5.5) for development ventilation will be applied to construction ventilation in this analysis as well as adding new and updated ventilation factors to each option for both construction and development. The objective of this analysis is to develop a preferred ventilation system to support License Application Design. The scope of this analysis includes: (1) Description of ventilation conditions; (2) Ventilation factors (fire hazards, dust control, construction logistics, and monitoring and control systems); (3) Local ventilation alternatives; (4) Global ventilation options; and (5) Evaluation of options

  20. Characteristics of coal mine ventilation air flows.

    Science.gov (United States)

    Su, Shi; Chen, Hongwei; Teakle, Philip; Xue, Sheng

    2008-01-01

    Coal mine methane (CMM) is not only a greenhouse gas but also a wasted energy resource if not utilised. Underground coal mining is by far the most important source of fugitive methane emissions, and approximately 70% of all coal mining related methane is emitted to the atmosphere through mine ventilation air. Therefore, research and development on mine methane mitigation and utilisation now focuses on methane emitted from underground coal mines, in particular ventilation air methane (VAM) capture and utilisation. To date, most work has focused on the oxidation of very low concentration methane. These processes may be classified based on their combustion kinetic mechanisms into thermal oxidation and catalytic oxidation. VAM mitigation/utilisation technologies are generally divided into two basic categories: ancillary uses and principal uses. However, it is possible that the characteristics of ventilation air flows, for example the variations in methane concentration and the presence of certain compounds, which have not been reported so far, could make some potential VAM mitigation and utilisation technologies unfeasible if they cannot cope with the characteristics of mine site ventilation air flows. Therefore, it is important to understand the characteristics of mine ventilation air flows. Moreover, dust, hydrogen sulphide, sulphur dioxide, and other possible compounds emitted through mine ventilation air into the atmosphere are also pollutants. Therefore, this paper presents mine-site experimental results on the characteristics of mine ventilation air flows, including methane concentration and its variations, dust loadings, particle size, mineral matter of the dust, and other compounds in the ventilation air flows. The paper also discusses possible correlations between ventilation air characteristics and underground mining activities.

  1. Energy and exergy performance of residential heating systems with separate mechanical ventilation

    International Nuclear Information System (INIS)

    Zmeureanu, Radu; Yu Wu, Xin

    2007-01-01

    The paper brings new evidence on the impact of separate mechanical ventilation system on the annual energy and exergy performance of several design alternatives of residential heating systems, when they are designed for a house in Montreal. Mathematical models of residential heating, ventilation and domestic hot water (HVAC-DHW) systems, which are needed for this purpose, are developed and furthermore implemented in the Engineering Equation Solver (EES) environment. The Coefficient of Performance and the exergy efficiency are estimated as well as the entropy generation and exergy destruction of the overall system. The equivalent greenhouse gas emissions due to the on-site and off-site use of primary energy sources are also estimated. The addition of a mechanical ventilation system with heat recovery to any HVAC-DHW system discussed in the paper increases the energy efficiency; however, it decreases the exergy efficiency, which indicates a potential long-term damaging impact on the natural environment. Therefore, the use of a separate mechanical ventilation system in a house should be considered with caution, and recommended only when other means for controlling the indoor air quality cannot be applied

  2. 46 CFR 169.315 - Ventilation (other than machinery spaces).

    Science.gov (United States)

    2010-10-01

    ... section is satisfied, a vessel having only a natural ventilation system must satisfy the following: V/A≥1... 46 Shipping 7 2010-10-01 2010-10-01 false Ventilation (other than machinery spaces). 169.315... SCHOOL VESSELS Construction and Arrangement Hull Structure § 169.315 Ventilation (other than machinery...

  3. 9 CFR 354.226 - Lighting and ventilation.

    Science.gov (United States)

    2010-01-01

    ... Facilities § 354.226 Lighting and ventilation. There shall be ample light, either natural or artificial or both, of good quality and well distributed, and sufficient ventilation for all rooms and compartments... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Lighting and ventilation. 354.226...

  4. Experimental Analysis and Model Validation of an Opaque Ventilated Facade

    DEFF Research Database (Denmark)

    López, F. Peci; Jensen, Rasmus Lund; Heiselberg, Per

    2012-01-01

    Natural ventilation is a convenient way of reducing energy consumption in buildings. In this study an experimental module of an opaque ventilated façade (OVF) was built and tested for assessing its potential of supplying free ventilation and air preheating for the building. A numerical model was ...

  5. Thermal Plumes in Ventilated Rooms

    DEFF Research Database (Denmark)

    Kofoed, Peter; Nielsen, Peter V.

    Ventilation systems with vertical displacement flow have been used in industrial areas with extensive heat loads for many years. Hot and contaminant air is carried directly from the occupied zone towards the ceiling by hot processes and other activities which create a natural convection flow....

  6. Contaminants in ventilated filling boxes

    Science.gov (United States)

    Bolster, D. T.; Linden, P. F.

    While energy efficiency is important, the adoption of energy-efficient ventilation systems still requires the provision of acceptable indoor air quality. Many low-energy systems, such as displacement or natural ventilation, rely on temperature stratification within the interior environment, always extracting the warmest air from the top of the room. Understanding buoyancy-driven convection in a confined ventilated space is key to understanding the flow that develops with many of these modern low-energy ventilation schemes. In this work we study the transport of an initially uniformly distributed passive contaminant in a displacement-ventilated space. Representing a heat source as an ideal sourced of buoyancy, analytical and numerical models are developed that allow us to compare the average efficiency of contaminant removal between traditional mixing and modern low-energy systems. A set of small-scale analogue laboratory experiments was also conducted to further validate our analytical and numerical solutions.We find that on average traditional and low-energy ventilation methods are similar with regard to pollutant flushing efficiency. This is because the concentration being extracted from the system at any given time is approximately the same for both systems. However, very different vertical concentration gradients exist. For the low-energy system, a peak in contaminant concentration occurs at the temperature interface that is established within the space. This interface is typically designed to sit at some intermediate height in the space. Since this peak does not coincide with the extraction point, displacement ventilation does not offer the same benefits for pollutant flushing as it does for buoyancy removal.

  7. Dissolved greenhouse gases (nitrous oxide and methane) associated with the natural iron-fertilized Kerguelen region (KEOPS 2 cruise) in the Southern Ocean

    Science.gov (United States)

    Farías, L.; Florez-Leiva, L.; Besoain, V.; Fernández, C.

    2014-08-01

    The concentrations of greenhouse gases (GHGs) like nitrous oxide (N2O) and methane (CH4) were measured in the Kerguelen Plateau Region (KPR), an area with annual microalgal bloom caused by natural Fe fertilization, which may stimulate microbes involved in GHG cycling. This study was carried out during the KEOPS 2 cruise during the austral spring of 2011. Two transects were sampled along and across the KRP, the north-south (N-S) transect (46-51° S, 72° E meridian) and the west-east (W-E) transect (66-75° E, 48.3° S latitude), both associated with the presence of a plateau, polar fronts and other mesoscale features. The W-E transect had N2O levels ranging from equilibrium (105%) to light supersaturation (120%) with respect to the atmosphere. CH4 levels fluctuated dramatically, with intense supersaturations (120-970%) in areas close to the coastal waters of Kerguelen Island and in the polar front (PF). There, Fe and nutrient fertilization seem to promote high total chlorophyll a (TChl a) levels. The distribution of both gases was more homogenous in the N-S transect, but CH4 peaked at southeastern stations of the KPR (A3 stations), where phytoplankton bloom was observed. Both gases responded significantly to the patchy distribution of particulate matter as Chl a, stimulated by Fe supply by complex mesoscale circulation. While CH4 appears to be produced mainly at the pycnoclines, N2O seems to be consumed superficially. Air-sea fluxes for N2O (from -10.5 to 8.65, mean 1.71 μmol m-2d-1), and for CH4 (from 0.32 to 38.1, mean 10.07 μmol m-2d-1) reflected sink and source behavior for N2O and source behavior for CH4, with considerable variability associated with a highly fluctuating wind regime and, in the case of CH4, due to its high superficial levels that had not been reported before in the Southern Ocean and may be caused by an intense microbial CH4 cycling.

  8. Gardening with Greenhouses

    Science.gov (United States)

    Keeler, Rusty

    2010-01-01

    Greenhouses come in all shapes, sizes, and price ranges: from simple hand-built plastic-covered frames to dazzling geodesic domes. Some child care centers install greenhouses as a part of their outdoor garden space. Other centers have incorporated a greenhouse into the building itself. Greenhouses provide a great opportunity for children to grow…

  9. Patient-Ventilator Dyssynchrony

    Directory of Open Access Journals (Sweden)

    Elvira-Markela Antonogiannaki

    2017-11-01

    Full Text Available In mechanically ventilated patients, assisted mechanical ventilation (MV is employed early, following the acute phase of critical illness, in order to eliminate the detrimental effects of controlled MV, most notably the development of ventilator-induced diaphragmatic dysfunction. Nevertheless, the benefits of assisted MV are often counteracted by the development of patient-ventilator dyssynchrony. Patient-ventilator dyssynchrony occurs when either the initiation and/or termination of mechanical breath is not in time agreement with the initiation and termination of neural inspiration, respectively, or if the magnitude of mechanical assist does not respond to the patient’s respiratory demand. As patient-ventilator dyssynchrony has been associated with several adverse effects and can adversely influence patient outcome, every effort should be made to recognize and correct this occurrence at bedside. To detect patient-ventilator dyssynchronies, the physician should assess patient comfort and carefully inspect the pressure- and flow-time waveforms, available on the ventilator screen of all modern ventilators. Modern ventilators offer several modifiable settings to improve patient-ventilator interaction. New proportional modes of ventilation are also very helpful in improving patient-ventilator interaction.

  10. Ventilation of radioactive enclosures; Ventilation des enceintes radioactives

    Energy Technology Data Exchange (ETDEWEB)

    Caminade, F; Laurent, H [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1957-07-01

    Mechanical, physical and chemical manipulations on radioactive products must be carried out in properly ventilated enclosed places. The air extracted can only be discharged into the atmosphere after a correct filtration. The power of the ventilation systems is a function of the dimensions and purpose of the enclosure? The choice of types of filter is determined by the physical state and chemical nature of the radioactive materials to be manipulated. This study deals with the individual equipment of small installations: glove boxes, manipulation boxes with outside control and, if necessary, production chambers (maximum useful volume: 5 m{sup 3}). The performances of three types of 'ventilators', and the modifications provided by the addition of filters, are measured and compared. (author) [French] Les manipulations oceaniques, physiques et chimiques sur des produits radioactifs doivent s'effectuer dans des enceintes convenablement ventilees. L'air extrait ne peut etre rejete dans l'atmosphere qu'apres une filtration correcte. La puissance des installations de ventilation est fonction des dimensions de l'enceinte et de son utilisation. Le choix des types de filtres est determine par l'etat physique et la nature ehimique des corps radioactifs manipules. Notre etude porte sur l'equipement individuel d'installations de petites dimensions: boites a gants, boites a pinces et, a la rigueur, enceintes de production (volume maximum utilisable 5 m{sup 3}). Nous mesurons et comparons les performances de trois types de 'ventilateurs' et les modifications apportees par l'adjonction de filtres. (auteur)

  11. GREENHOUSE BRITAIN

    Directory of Open Access Journals (Sweden)

    David Haley

    2008-10-01

    Full Text Available We believe that the cultural landscape is largely formed by the dominant cultures of a place. “It is formed by a sometimes conflicted, sometimes consensual discourse or narrative from an array of stories, observations and intentions, first spoken by people of these dominant cultures and thereafter enacted on the ground. To our view, such a story has certain fluidity about it, and may change directions for any number of reasons. This work, Greenhouse Britain, is designed literally to express what the risingof waters would mean to the landscape of the island. It takes the 3 positions of defense, withdrawal and then defense, withdrawal to the high grounds. We suggest that the existing plans for greenhouse emissions control will be insufficient to keep temperature rise at 2° or less. In fact, we believe that the tipping point is past. In this context, the rising ocean becomes a form determinant. By “form determinant”, we mean, the rising ocean will determine many of the new forms that culture, industry and many other elements of civilization will have to take. There is another piece of this picture that we wish to give Voice to. That is up until this present rising of the world oceans, the creators of Western civilization have held and enacted the belief that all limitations in the physical world, particularly in the ecological world are there to be used and overcome. We think that the rising ocean is an opportunity for transformation, but it is exactly the reverse of a new frontier to overcome from civilization’s perspective. Now, from the ocean’s perspective, its boundary is perhaps a continuing, evolving transforming new frontier. Therefore, assuming a rapid rise of waters, even for a modest 5 meters in 100 years, there are apparently no models of precedence, no information, design, nor planning on the table, with the exception of ocean defenses and typical development models, albeit more energy efficient ones. It is the intention of

  12. Mechanical ventilator - infants

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/007240.htm Mechanical ventilator - infants To use the sharing features on this page, please enable JavaScript. A mechanical ventilator is a machine that assists with breathing. ...

  13. Learning about ventilators

    Science.gov (United States)

    ... medlineplus.gov/ency/patientinstructions/000458.htm Learning about ventilators To use the sharing features on this page, ... fixed or changed. How Does Being on a Ventilator Feel? A person receives medicine to remain comfortable ...

  14. 46 CFR 116.600 - Ventilation of enclosed and partially enclosed spaces.

    Science.gov (United States)

    2010-10-01

    ... unless natural ventilation in all ordinary weather conditions is satisfactory to the OCMI. (d) An exhaust... 46 Shipping 4 2010-10-01 2010-10-01 false Ventilation of enclosed and partially enclosed spaces... PASSENGERS CONSTRUCTION AND ARRANGEMENT Ventilation § 116.600 Ventilation of enclosed and partially enclosed...

  15. 46 CFR 92.15-15 - Ventilation for crew quarters and, where provided, passenger spaces.

    Science.gov (United States)

    2010-10-01

    ..., unless it can be shown that a natural system will provide adequate ventilation. However, vessels which... 46 Shipping 4 2010-10-01 2010-10-01 false Ventilation for crew quarters and, where provided...) CARGO AND MISCELLANEOUS VESSELS CONSTRUCTION AND ARRANGEMENT Ventilation § 92.15-15 Ventilation for crew...

  16. 46 CFR 190.15-15 - Ventilation for living spaces and quarters.

    Science.gov (United States)

    2010-10-01

    ... mechanical system unless it can be shown that a natural system will provide adequate ventilation. By a... 46 Shipping 7 2010-10-01 2010-10-01 false Ventilation for living spaces and quarters. 190.15-15... VESSELS CONSTRUCTION AND ARRANGEMENT Ventilation § 190.15-15 Ventilation for living spaces and quarters...

  17. 46 CFR 72.15-20 - Ventilation for crew quarters and passenger spaces.

    Science.gov (United States)

    2010-10-01

    ... shown that a natural system will provide adequate ventilation. However, vessels which trade regularly in... 46 Shipping 3 2010-10-01 2010-10-01 false Ventilation for crew quarters and passenger spaces. 72... VESSELS CONSTRUCTION AND ARRANGEMENT Ventilation § 72.15-20 Ventilation for crew quarters and passenger...

  18. Improved Performance With Ventilation

    Science.gov (United States)

    Kawakami, Ellison; Lee, Seung Jae; Karn, Ashish; Hong, Jiarong; Arndt, Roger

    2013-11-01

    Drag reduction and/or speed augmentation of marine vehicles by means of supercavitation is a topic of great interest. During the initial launch of a supercavitating vehicle, ventilation is required to supply an artificial cavity until conditions at which a natural supercavity can be sustained are reached. Various aspects of the flow physics of a supercavitating vehicle have been under investigation for several years at Saint Anthony Falls Laboratory. Both steady flow and simulated flow below a wave train have been studied. Using a high speed camera and the proper software, it is possible to synchronize cavity dimensions with pressure measurements taken inside the cavity to permit an in-depth study of unsteadiness. It was found that flow unsteadiness caused a decrease in the overall length of the supercavity while having only a minimal effect on the maximum diameter. Results regarding supercavity shape, ventilation demand, cavitation parameters and closure methods are reviewed in light of new studies that focused on various closure mechanisms. Sponsored by ONR.

  19. VENTILATION TECHNOLOGY SYSTEMS ANALYSIS

    Science.gov (United States)

    The report gives results of a project to develop a systems analysis of ventilation technology and provide a state-of-the-art assessment of ventilation and indoor air quality (IAQ) research needs. (NOTE: Ventilation technology is defined as the hardware necessary to bring outdoor ...

  20. Ventilation of nuclear facilities

    International Nuclear Information System (INIS)

    1982-01-01

    In this work an examination is made of ventilation problems in nuclear installations, of the fuel cycle or the handling of radioactive compounds. The study covers the detection of radioactive aerosols, purification, iodine trapping, ventilation equipment and its maintenance, engineering, safety of ventilation, fire efficiency, operation, regulations and normalization [fr

  1. Irrigation management in organic greenhouse

    NARCIS (Netherlands)

    Voogt, W.; Balendonck, J.; Berkelmans, R.; Enthoven, N.

    2017-01-01

    Irrigation in protected cultivation is essential due to the absence of natural precipitation. High evapotranspiration, due to higher temperature and prolonged cropping period, requires ample an adequate supply of water. The water supply in a greenhouse is solely carried out by irrigation and thus

  2. Ventilation and ventilation/perfusion ratios

    International Nuclear Information System (INIS)

    Valind, S.O.

    1989-01-01

    The thesis is based on five different papers. The labelling of specific tracer compounds with positron emitting radionuclides enables a range of structural, physiological and biochemical parameters in the lung to be measured non-invasively, using positron emission tomography. This concept affords a unique opportunity for in vivo studies of different expressions of pulmonary pathophysiology at the regional level. The present thesis describes the application of positron emission tomography to the measurements of ventilation and ventilation/perfusion ratios using inert gas tracers, neon-19 and nitrogen-13 respectively. The validity of the methods applied was investigated with respect to the transport of inert gas tracers in the human lung. Both ventilation and the ventilation/perfusion ratio may be obtained with errors less than 10 % in the normal lung. In disease, however, errors may increase in those instances where the regional ventilation is very low or the intra-regional gas flow distribution is markedly nonuniform. A 2-3 fold increase in ventilation was demonstrated in normal nonsmoking subjects going from ventral to dorsal regions in the supine posture. These large regional differences could be well explained by the intrinsic elastic properties of lung tissue, considering the gravitational gradient in transpulmonary pressure. In asymptomatic smokers substantial regional ventilatroy abnormalities were found whilst the regional gas volume was similar in smokers and nonsmokers. The uncoupling between ventilation and gas volume probably reflects inflammatory changes in the airways. The regional differences in dV/dt/dQ/dt were relatively small and blood flow was largely matched to ventilation in the supine posture. However, small regions of lung with very low ventilation, unmatched by blood flow commonly exists in the most dependent parts of the lung in both smokers and nonsmokers. (29 illustrations, 7 tables, 113 references)

  3. Ventilation effectiveness : health benefits of heat recovery ventilators

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2010-08-15

    Studies have shown that the installation of a heat recovery ventilator (HRV) in homes in northern Canada could improve indoor air quality and the respiratory health of inhabitants. Low ventilation rates are common in many homes in the North because the climate is severe, homes are smaller and lack basements, and occupancies are higher, leading to unhealthy indoor air quality. Northern communities also have a high rate of respiratory infections. HRVs recover much of the energy used to ventilate, which is desirable in cold regions with high heating costs. For the study, the test sample was divided into two types of houses, notably houses with active HRVs and those with control HRVs that were installed and operated but that did not function. The study results showed that HRVs provided increased ventilation. Complaints by residents about HRV noise, discomfort, or low humidity were common but equally spread between those with active and placebo HRVs. The study showed that the system design needs to be improved to better suit the needs of Inuit families. The nature of northern housing presents installation and maintenance challenges. It is hard to retrofit HRV ducting inside small, existing houses, and building supplies arrive infrequently, so detailed planning and careful take-offs of all supplies and materials must be done well in advance of construction. In addition, contractors are hard to locate and have variable expertise, and there is little technical follow-up. Robust technical support by local contractors and housing authorities is therefore important. 2 refs.

  4. Modeling and simulation of fuzzy logic controller for optimization of the greenhouse microclimate management

    Directory of Open Access Journals (Sweden)

    Didi Faouzi

    2017-06-01

    Full Text Available Abstract. Agricultural greenhouse is largely answered in the agricultural sphere, despite the shortcomings it has, including overheating during the day and night cooling which sometimes results in the thermal inversion mainly due to its low inertia. The glasshouse dressed chapel is relatively more efficient than the conventional tunnel greenhouse. Its proliferation on the ground is more or less timid because of its relatively high cost. Agricultural greenhouse aims to create a favorable microclimate to the requirements of growth and development of culture, from the surrounding weather conditions, produce according to the cropping calendars fruits, vegetables and flower species out of season and widely available along the year. It is defined by its structural and functional architecture, the quality thermal, mechanical and optical of its wall, with its sealing level and the technical and technological accompanying. The greenhouse is a very confined environment, where multiple components are exchanged between key stakeholders and the factors are light, temperature and relative humidity. This state of thermal evolution is the level sealing of the cover of its physical characteristics to be transparent to solar, absorbent and reflective of infrared radiation emitted by the enclosure where the solar radiation trapping effect otherwise called "greenhouse effect" and its technical and technological means of air that accompany. The socio-economic analysis of populations in the world leaves appear especially the last two decades of rapid and profound transformations These changes are accompanied by changes in eating habits, mainly characterized by rising consumption spread along the year. To effectively meet this demand, greenhousesystems have evolved, particularly towards greater control of production conditions (climate, irrigation, ventilation techniques, CO supply, etc.. Technological 2 progress has allowed the development of greenhouses so that they

  5. Effects of agrochemicals, ultra violet stabilisers and solar radiation on the radiometric properties of greenhouse films

    Directory of Open Access Journals (Sweden)

    Giuliano Vox

    2013-10-01

    Full Text Available Agrochemicals, based on iron, sulphur and chlorine, generate by products that lead to a degradation of greenhouse films together with a decrease in their mechanical and physical properties. The degradation due to agrochemicals depends on their active principles, method and frequency of application, and greenhouse ventilation. The aim of the research was to evaluate how agrochemical contamination and solar radiation influence the radiometric properties of ethylene-vinyl acetate copolymer greenhouse films by means of laboratory and field tests. The films, manufactured on purpose with the addition of different light stabiliser systems, were exposed to natural outdoor weathering at the experimental farm of the University of Bari (Italy; 41° 05’ N in the period from 2006 to 2008. Each film was tested for two low tunnels: one low tunnel was sprayed from inside with the agrochemicals containing iron, chlorine and sulphur while the other one was not sprayed and served as control. Radiometric laboratory tests were carried out on the new films and on samples taken at the end of the trials. The experimental tests showed that both the natural weathering together with the agrochemicals did not modify significantly the radiometric properties of the films in the solar and in the photosynthetically active radiation wavelength range. Within six months of experimental field tests the variations in these radiometric characteristics were at most 10%. Significant variations, up to 70% of the initial value, were recorded for the stabilised films in the long-wave infrared radiation wavelength range.

  6. Development of a pneumatic roof envelope for industrial greenhouses

    NARCIS (Netherlands)

    Lindner, G.; Vos, de G.J.

    2008-01-01

    The Eindhoven University of Technology (TU/e) was approached by Van Diemen BV, a turn-key greenhouse builder looking for a new and higher insulated design for their green house envelope. They had developed a new system of climate control which rendered windows for ventilation purposes unnecessary

  7. Effects of ground insulation and greenhouse microenvironment on ...

    African Journals Online (AJOL)

    A study was conducted at Egerton University, Njoro, Kenya to establish the potential of plastic digester to produce biogas under natural and greenhouse microenvironment. The specific objectives were to evaluate the effects of greenhouse and ground insulation on the rate and quality of biogas generation. A greenhouse ...

  8. Agriculture: Nurseries and Greenhouses

    Science.gov (United States)

    Nurseries and Greenhouses. Information about environmental requirements specifically relating to the production of many types of agricultural crops grown in nurseries and greenhouses, such as ornamental plants and specialty fruits and vegetables.

  9. Temperature Simulation of Greenhouse with CFD Methods and Optimal Sensor Placement

    OpenAIRE

    Yanzheng Liu; Jing Chen; Yazhou Lv; Xiaojie Li

    2014-01-01

    The accuracy of information monitoring is significant to increase the effect of Greenhouse Environment Control. In this paper, by taking simulation for the temperature field in the greenhouse as an example, the CFD (Computational Fluid Dynamics) simulation model for measuring the microclimate environment of greenhouse with the principle of thermal environment formation was established, and the temperature distributions under the condition of mechanical ventilation was also simulated. The resu...

  10. Complications of mechanical ventilation

    Directory of Open Access Journals (Sweden)

    Drašković Biljana

    2011-01-01

    Full Text Available Mechanical ventilation of the lungs, as an important therapeutic measure, cannot be avoided in critically ill patients. However, when machines take over some of vital functions there is always a risk of complications and accidents. Complications associated with mechanical ventilation can be divided into: 1 airway-associated complications; 2 complications in the response of patients to mechanical ventilation; and 3 complications related to the patient’s response to the device for mechanical ventilation. Complications of artificial airway may be related to intubation and extubation or the endotracheal tube. Complications of mechanical ventilation, which arise because of the patient’s response to mechanical ventilation, may primarily cause significant side effects to the lungs. During the last two decades it was concluded that mechanical ventilation can worsen or cause acute lung injury. Mechanical ventilation may increase the alveolar/capillary permeability by overdistension of the lungs (volutrauma, it can exacerbate lung damage due to the recruitment/derecruitment of collapsed alveoli (atelectrauma and may cause subtle damages due to the activation of inflammatory processes (biotrauma. Complications caused by mechanical ventilation, beside those involving the lungs, can also have significant effects on other organs and organic systems, and can be a significant factor contributing to the increase of morbidity and mortality in critically ill of mechanically ventilated patients. Complications are fortunately rare and do not occur in every patient, but due to their seriousness and severity they require extensive knowledge, experience and responsibility by health-care workers.

  11. The Dynamic Greenhouse Challenge

    Science.gov (United States)

    Roman, Harry T.

    2010-01-01

    Greenhouses are marvelous devices, allowing one to enjoy the flower spectacle of summer all year round. At night, greenhouses use supplemental heat to keep the fragile plants warm. Over the last 30 years, greenhouse technology has undergone many changes, with the structures being automated and monitored and low-cost plastic structures emerging as…

  12. Evaluation of ventilators for mouthpiece ventilation in neuromuscular disease.

    Science.gov (United States)

    Khirani, Sonia; Ramirez, Adriana; Delord, Vincent; Leroux, Karl; Lofaso, Frédéric; Hautot, Solène; Toussaint, Michel; Orlikowski, David; Louis, Bruno; Fauroux, Brigitte

    2014-09-01

    Daytime mouthpiece ventilation is a useful adjunct to nocturnal noninvasive ventilation (NIV) in patients with neuromuscular disease. The aims of the study were to analyze the practice of mouthpiece ventilation and to evaluate the performance of ventilators for mouthpiece ventilation. Practice of mouthpiece ventilation was assessed by a questionnaire, and the performance of 6 home ventilators with mouthpiece ventilation was assessed in a bench test using 24 different conditions per ventilator: 3 mouthpieces, a child and an adult patient profile, and 4 ventilatory modes. Questionnaires were obtained from 30 subjects (mean age 33 ± 11 y) using NIV for 12 ± 7 y. Fifteen subjects used NIV for > 20 h/day, and 11 were totally ventilator-dependent. The subject-reported benefits of mouthpiece ventilation were a reduction in dyspnea (73%) and fatigue (93%) and an improvement in speech (43%) and eating (27%). The bench study showed that none of the ventilators, even those with mouthpiece ventilation software, were able to deliver mouthpiece ventilation without alarms and/or autotriggering in each condition. Alarms and/or ineffective triggering or autotriggering were observed in 135 of the 198 conditions. The occurrence of alarms was more common with a large mouthpiece without a filter compared to a small mouthpiece with a filter (P ventilator. Subjects are satisfied with mouthpiece ventilation. Alarms are common with home ventilators, although less common in those with mouthpiece ventilation software. Improvements in home ventilators are needed to facilitate the expansion of mouthpiece ventilation. Copyright © 2014 by Daedalus Enterprises.

  13. Ventilation System Strategy for a Prospective Korean Radioactive Waste Repository

    International Nuclear Information System (INIS)

    Kim, Jin; Kwon, Sang Ki

    2005-01-01

    In the stage of conceptual design for the construction and operation of the geologic repository for radioactive wastes, it is important to consider a repository ventilation system which serves the repository working environment, hygiene and safety of the public at large, and will allow safe maintenance like moisture content elimination in repository for the duration of the repositories life, construction/operation/closure, also allowing safe waste transportation and emplacement. This paper describes the possible ventilation system design criteria and requirements for the prospective Korean radioactive waste repositories with emphasis on the underground rock cavity disposal method in the both cases of low and medium-level and high-level wastes. It was found that the most important concept is separate ventilation systems for the construction (development) and waste emplacement (storage) activities. In addition, ventilation network system modeling, natural ventilation, ventilation monitoring systems and real time ventilation simulation, and fire simulation and emergency system in the repository are briefly discussed.

  14. Greenhouse gas trading

    Energy Technology Data Exchange (ETDEWEB)

    Drazilov, P. [Natsource-Tullett Emissions Brokerage, Toronto, ON (Canada)

    2001-07-01

    Natsource-Tullett Emissions Brokerage is a market leader in natural gas, electricity, coal, and weather, emissions with a total of more than $2 billion by volume in emissions transactions in the United States, Canada, Australia, Japan, and Europe. This power point presentation addressed issues dealing with global warming, the Kyoto Protocol, and explained where we are in terms of reaching commitments for the first compliance period between 2008-2012. The paper focused on international emissions trading (IET), joint implementation (JI) and the clean development mechanism (CDM) and explained how greenhouse gases are traded. Emissions trading refers to the trade of carbon dioxide, methane, nitrous oxides, perfluoro-carbons, hydrofluorocarbons, and sulphur hexafluorides. The motivational drivers for trading were outlined in terms of liability for buyers and assets for sellers. To date, trading activity is nearly 120 transactions with nearly 70 million tons of carbon dioxide equivalent. tabs., figs.

  15. Protective garment ventilation system

    Science.gov (United States)

    Lang, R. (Inventor)

    1970-01-01

    A method and apparatus for ventilating a protective garment, space suit system, and/or pressure suits to maintain a comfortable and nontoxic atmosphere within is described. The direction of flow of a ventilating and purging gas in portions of the garment may be reversed in order to compensate for changes in environment and activity of the wearer. The entire flow of the ventilating gas can also be directed first to the helmet associated with the garment.

  16. Ventilation rates and health

    DEFF Research Database (Denmark)

    Sundell, Jan; Levin, H; Nazaroff, W W

    2011-01-01

    and health effects to inform the relationship. Consistency was found across multiple investigations and different epidemiologic designs for different populations. Multiple health endpoints show similar relationships with ventilation rate. There is biological plausibility for an association of health outcomes...... studies of the relationship between ventilation rates and health, especially in diverse climates, in locations with polluted outdoor air and in buildings other than offices. PRACTICAL IMPLICATIONS: Ventilation with outdoor air plays an important role influencing human exposures to indoor pollutants...

  17. Ventilation of uranium mines

    International Nuclear Information System (INIS)

    Francois, Y.; Pradel, J.; Zettwoog, P.; Dumas, M.

    1975-01-01

    In the first part of the paper the authors describe the ventilation of French mines in terms of the primary ventilation system, which brings the outside air close to the working places using the overall structure of the mine to form the airways, and the secondary ventilation system, which is for the distribution of the primary air or for the ventilation of the development drifts and blind tunnels. Brief mention is made of the French regulations on the ventilation of mines in general and uranium mines in particular. The authors describe the equipment used and discuss the installed capacities and air flow per man and per working place. The difficulties encountered in properly ventilating various types of working places are mentioned, such as sub-level development drifts, reinforced stopes, and storage chambers with an artificial crown. The second part of the paper is devoted to computer calculations of the primary ventilation system. It is explained why the Commissariat a l'energie atomique has found it necessary to make these calculations. Without restating the mathematical theories underlying the methods employed, the authors demonstrate how simple measuring instruments and a small-size computer can be used to solve the ventilation problems arising in French mines. Emphasis is given to the layout of the ventilation system and to air flow and negative pressure measurements at the base of the mine. The authors show how calculations can be applied to new heading operations, a change in resistance, the replacement or addition of a ventilator, and a new air inlet or outlet. The authors come to the conclusion that since ventilation is at present the most reliable way of avoiding the pollution of mines, a thorough knowledge of the capabilities in this respect can often help improve working conditions. Despite the progress made, however, constant surveillance of the ventilation systems in uranium mines by a separate team with no responsibility for production problems is

  18. Ventilation of uranium mines

    International Nuclear Information System (INIS)

    Francois, Y.; Pradel, J.; Zettwoog, P.; Dumas, M.

    1975-01-01

    In the first part of the paper the authors describe the ventilation of French mines in terms of the primary ventilation system, which brings the outside air close to the working places using the overall structure of the mine to form the airways, and the secondary ventilation system, which is for the distribution of the primary air or for the ventilation of the development drifts and blind tunnels. Brief mention is made of the French regulations on the ventilation of mines in general and uranium mines in particular. The authors describe the equipment used and discuss the installed capacities and air flow per man and per working place. The difficulties encountered in properly ventilating various types of working places are mentioned, such as sublevel development drifts, reinforced stopes, and storage chambers with an artificial crown. The second part of the paper is devoted to computer calculations of the primary ventilation system. It is explained why the Commissariat a l'energie atomique has found it necessary to make these calculations. Without restating the mathematical theories underlying the methods employed, the authors demonstrate how simple measuring instruments and a small-size computer can be used to solve the ventilation problems arising in French mines. Emphasis is given to the layout of the ventilation system and to air flow and negative pressure measurements at the base of the mine. The authors show how calculations can be applied to new heading operations, a change in resistance, the replacement or addition of a ventilator, and a new air inlet or outlet. The authors come to the conclusion that since ventilation is at present the most reliable way of avoiding the pollution of mines, a thorough knowledge of the capabilities in this respect can often help improve working conditions. Despite the progress made, however, constant surveillance of the ventilation systems in uranium mines by a separate team with no responsibility for production problems is

  19. Nuclear energy and the greenhouse effect

    International Nuclear Information System (INIS)

    Weinberg, A.M.

    1990-01-01

    The extent and nature of the greenhouse effect are examined and placed in an environmental and historical context. The effect of energy policies on the greenhouse effect are discussed and the offending countries are identified. What energy policies would mitigate the greenhouse effect, and yet make good sense whether or not the effect proves to be real? Conservation is a desirable though not completely understood strategy. Conservation may not be a better bet in every instance than is increase in supply. If the greenhouse effect turns out to be real, nuclear energy can be one of the supply options that we turn to. If the greenhouse effect turns out to be false, and acceptable, economic nuclear option is surely better than one that does nothing but create strife and dissension. Let us remember that nuclear energy is the only large-scale non-fossil source other than hydropower that has been demonstrated to be practical. (author)

  20. REVERSIBLE VENTILATION SYSTEM FOR ADMINISTRATIVE BUILDINGS

    Directory of Open Access Journals (Sweden)

    Valery Yu. Kravchuk

    2017-01-01

    Full Text Available Abstract. Objectives To consider the possibility of applying the principle of reversing air flows for a centralised ventilation system; to develop a specific scheme for air exchange reversible ventilation, which will take into account the peculiarities of the microclimate of administrative buildings; to select the type of filling of the air-permeable element and justify this choice; to determine the conditions for changing the direction of air movement in the ventilation system and the area of its application; to form a list of equipment necessary for the operation of such a system; to consider the influence of supply and exhaust devices on the heat and humidity regime of claddings. Methods  To achieve this goal, the published thematic material was reviewed and a patent search carried out using Russian and European databases. Data on mathematical modelling of filtration in porous media and experimental results were used. A method for ventilating rooms in administrative building using the reversal of movement of supply and exhaust air streams along the same channels was applied. Results  Schemas for reversible ventilation systems are presented and their modes of operation considered. It is established that the idea of reversing ventilation flows has not yet been applied in the development of centralised ventilation systems. Based on these published materials, it was concluded that the proposed design of supply and exhaust devices can be used in practice. An original air exchange scheme for the ventilation of administrative buildings and design of supply and exhaust devices for this system are proposed. The conditions for changing the operating modes of the system and the scope of its application are determined. Conclusion The use of the proposed ventilation system allows normative air exchange to be provided without using a supply unit during the cold season. This application of airflow reversal allows the potential of natural forces to be used

  1. Note on protection offered by ventilation systems in the event of a nuclear reactor accident

    International Nuclear Information System (INIS)

    Wayland, J.R.; McGrath, P.E.

    1976-05-01

    A brief review of the protection offered by natural and forced ventilation systems in buildings to an atmospheric release of radioactive material is given. The protection to be gained by using the internal ventilation system is estimated

  2. Tracheostomy and invasive mechanical ventilation in amyotrophic lateral sclerosis: decision-making factors and survival analysis.

    Science.gov (United States)

    Kimura, Fumiharu

    2016-04-28

    Invasive and/or non-invasive mechanical ventilation are most important options of respiratory management in amyotrophic lateral sclerosis. We evaluated the frequency, clinical characteristics, decision-making factors about ventilation and survival analysis of 190 people with amyotrophic lateral sclerosis patients from 1990 until 2013. Thirty-one percentage of patients underwent tracheostomy invasive ventilation with the rate increasing more than the past 20 years. The ratio of tracheostomy invasive ventilation in patients >65 years old was significantly increased after 2000 (25%) as compared to before (10%). After 2010, the standard use of non-invasive ventilation showed a tendency to reduce the frequency of tracheostomy invasive ventilation. Mechanical ventilation prolonged median survival (75 months in tracheostomy invasive ventilation, 43 months in non-invasive ventilation vs natural course, 32 months). The life-extending effects by tracheostomy invasive ventilation were longer in younger patients ≤65 years old at the time of ventilation support than in older patients. Presence of partners and care at home were associated with better survival. Following factors related to the decision to perform tracheostomy invasive ventilation: patients ≤65 years old: greater use of non-invasive ventilation: presence of a spouse: faster tracheostomy: higher progression rate; and preserved motor functions. No patients who underwent tracheostomy invasive ventilation died from a decision to withdraw mechanical ventilation. The present study provides factors related to decision-making process and survival after tracheostomy and help clinicians and family members to expand the knowledge about ventilation.

  3. Per capita emissions of greenhouse gases and international trade

    International Nuclear Information System (INIS)

    Karman, D.; Baptiste, S.

    1994-01-01

    The role played by international trade in Canada's emissions of greenhouse gases is investigated. Data used in the study include Environment Canada greenhouse gas emission estimates for 1990, a Statistics Canada input-output model linking greenhouse gas emissions to economic activity in different sectors, and monetary statistics on imports and exports. Subject to some simplifying assumptions, it is estimated that nearly 20% of Canada's greenhouse gas emissions can be attributed to the production of commodities destined for export to other countries. If the same greenhouse gas emission intensities are assumed for Canada's imports, the greenhouse gas emissions due to Canada's net trade is nearly 7% of the 660 megatonnes of CO 2 equivalent emissions for 1990. Commodities from natural resource exploitation head the list of greenhouse gas emissions attributed to international trade, as expected from their large export volumes and large greenhouse gas emission intensities. 4 refs., 1 fig

  4. Styret naturlig ventilation

    DEFF Research Database (Denmark)

    Morsing, S.; Strøm, J.S.

    Publikationen præsenterer et generelt dimensioneringsgrundlag for naturlig ventilation i husdyrstalde. Det er kontrolleret ved forsøg i slagtesvinestalde, hvor det ligeledes er undersøgt hvilken temperaturstabilitet, der kan opnås ved naturlig ventilation, samt produktions- og adfærdsmæssige...

  5. Multifamily Ventilation Retrofit Strategies

    Energy Technology Data Exchange (ETDEWEB)

    Ueno, K. [Building Science Corporation (BSC), Somerville, MA (United States); Lstiburek, J. [Building Science Corporation (BSC), Somerville, MA (United States); Bergey, D. [Building Science Corporation (BSC), Somerville, MA (United States)

    2012-12-01

    In multifamily buildings, central ventilation systems often have poor performance, overventilating some portions of the building (causing excess energy use), while simultaneously underventilating other portions (causing diminished indoor air quality). BSC and Innova Services Corporation performed a series of field tests at a mid-rise test building undergoing a major energy audit and retrofit, which included ventilation system upgrades.

  6. Diffuse Ceiling Ventilation

    DEFF Research Database (Denmark)

    Zhang, Chen; Heiselberg, Per; Nielsen, Peter V.

    2014-01-01

    As a novel air distribution system, diffuse ceiling ventilation combines the suspended acoustic ceiling with ventilation supply. Due to the low-impulse supply from the large ceiling area, the system does not generate draught when supplying cold air. However, heat sources play an important role...

  7. Pulmonary perfusion ''without ventilation''

    International Nuclear Information System (INIS)

    Chapman, C.N.; Sziklas, J.J.; Spencer, R.P.; Rosenberg, R.J.

    1983-01-01

    An 88-yr-old man, with prior left upper lobectomy and phrenic nerve injury, had a ventilation/perfusion lung image. Both wash-in and equilibrium ventilation images showed no radioactive gas in the left lung. Nevertheless, the left lung was perfused. A similar result was obtained on a repeat study 8 days later. Delayed images, during washout, showed some radioactive gas in the left lung. Nearly absent ventilation (but continued perfusion) of that lung might have been related to altered gas dynamics brought about by the prior lobectomy, a submucosal bronchial lesion, phrenic nerve damage, and limited motion of the left part of the diaphragm. This case raises the issue of the degree of ventilation (and the phase relationship between the lungs) required for the entry of radioactive gas into a diseased lung, and the production of a ''reversed ventilation/perfusion mismatch.''

  8. Realtime mine ventilation simulation

    International Nuclear Information System (INIS)

    McDaniel, K.H.

    1997-01-01

    This paper describes the development of a Windows based, interactive mine ventilation simulation software program at the Waste Isolation Pilot Plant (WIPP). To enhance the operation of the underground ventilation system, Westinghouse Electric Corporation developed the program called WIPPVENT. While WIPPVENT includes most of the functions of the commercially available simulation program VNETPC and uses the same subroutine to calculate airflow distributions, the user interface has been completely rewritten as a Windows application with screen graphics. WIPPVENT is designed to interact with WIPP ventilation monitoring systems through the sitewise Central monitoring System. Data can be continuously collected from the Underground Ventilation Remote Monitoring and Control System (e.g., air quantity and differential pressure) and the Mine Weather Stations (psychrometric data). Furthermore, WIPPVENT incorporates regulator characteristic curves specific to the site. The program utilizes this data to create and continuously update a REAL-TIME ventilation model. This paper discusses the design, key features, and interactive capabilities of WIPPVENT

  9. Economic growth and greenhouse gas emissions

    Energy Technology Data Exchange (ETDEWEB)

    Ansuategi, Alberto [Environment Department, University of York, York (United Kingdom); Escapa, Marta [Foundations of Economic Analysis Department, University of the Basque Country, Bilbao (Spain)

    2002-01-01

    Recent empirical research has examined the relationship between certain indicators of environmental degradation and income, concluding that in some cases an inverted U-shaped relationship, which has been called an environmental Kuznets curve (EKC), exists between these variables. Unfortunately, this inverted U-shaped relationship does not hold for greenhouse gas emissions. One explanation of the absence of EKC-like behavior in greenhouse gas emissions is that greenhouse gases are special pollutants that create global, not local, disutility. But the international nature of global warming is not the only reason that prevents de-linking greenhouse gas emissions from economic growth. The intergenerational nature of the negative impact of greenhouse gas emissions may have also been an important factor preventing the implementation of greenhouse gas abatement measures in the past. In this paper we explore the effect that the presence of intergenerational spillovers has on the emissions-income relationship. We use a numerically calibrated overlapping generations model of climate-economy interactions. We conclude that: (1) the intertemporal responsibility of the regulatory agency, (2) the institutional capacity to make intergenerational transfers and (3) the presence of intergenerationally lagged impact of emissions constitute important determinants of the relationship between economic growth and greenhouse gas emissions.

  10. 46 CFR 32.55-1 - Ventilation of tank vessels constructed on or after July 1, 1951-TB/ALL.

    Science.gov (United States)

    2010-10-01

    ... natural ventilation, with at least one duct extending to immediately below the floor plates will be... 46 Shipping 1 2010-10-01 2010-10-01 false Ventilation of tank vessels constructed on or after July... VESSELS SPECIAL EQUIPMENT, MACHINERY, AND HULL REQUIREMENTS Ventilation and Venting § 32.55-1 Ventilation...

  11. Capturing energy from ventilation air methane a preliminary design for a new approach

    International Nuclear Information System (INIS)

    Cluff, D.L.; Kennedy, G.A.; Bennett, J.G.; Foster, P.J.

    2015-01-01

    Methane is a potent greenhouse gas (GHG), discharged to the atmosphere by coalmining, the natural gas industry and natural biological processes, second only to carbon dioxide; thus, any reduction in atmospheric methane would be globally beneficial. The capture or use of ventilation air methane (VAM) is challenging because it is a high volume low concentration methane source. This results in the routine discharge of methane into the atmosphere. A review of VAM mitigation technologies is provided and the main disadvantages of the existing technologies are discussed. In the proposed VamTurBurner © system, the heat from the combustion chamber is transferred to the preheating zone either by a heat exchanger or by redirecting the combustion products to mix with the ventilation air stream from a coalmine. Gas turbines (GT) are used to produce electricity with the exhaust gases directed to mix with the incoming ventilation airflow. The turbulence introduced by the GT exhaust assists with mixing of the incoming ventilation airflow and the return flow of combustion products from the combustion chamber. The combustion products are a source of heat, which increases the temperature of the incoming ventilation air to a value high enough for the methane to undergo flameless combustion upon encountering the igniters. The high temperature combustion products enter a multi-generation system. The multi-generation system is based on mature engineering technology such as heat exchangers and steam turbines. The residual heat provides additional heat based products such as industrial scale drying, chilling by an absorption chiller or simply hot water. The VamTurBurner © uses the energy from the GT, igniters and VAM to provide clean efficient energy while mitigating the atmospheric emissions of methane. The opportunity to collect carbon credits may improve the economics. Since the VAM is a free energy source, the output of the system is greater than the purchased energy. - Highlights:

  12. Greening the greenhouse grower

    DEFF Research Database (Denmark)

    Staats, Henk; Jansen, Lilian; Thøgersen, John

    2011-01-01

    Growing plants and flowers in greenhouses is a commercial activity that imposes a burden on the environment. Recently a system of registration, control, and licensing has been developed by the sector of greenhouse growers in the Netherlands, acknowledged by the state. The current study was executed...... to understand the achievements of the greenhouse growers within this system. We applied a social-cognitive model to understand intentions to reduce emissions and predict actual pesticide use. The social-cognitive concepts from the model were measured in a questionnaire that was completed by 743 greenhouse...

  13. Natural history and risk stratification of patients undergoing non-invasive ventilation in a non-ICU setting for severe COPD exacerbations.

    Science.gov (United States)

    Sainaghi, Pier Paolo; Colombo, Davide; Re, Azzurra; Bellan, Mattia; Sola, Daniele; Balbo, Piero Emilio; Campanini, Mauro; Della Corte, Francesco; Navalesi, Paolo; Pirisi, Mario

    2016-10-01

    Non-invasive ventilation (NIV) delivered in an intensive care unit (ICU) has become the cornerstone in the treatment of patients with severe chronic obstructive pulmonary disease (COPD) exacerbations. A trend towards managing these patients in non-ICU setting has emerged in recent years, although out-of-hospital survival by this approach and how to prognosticate it is unknown. We aimed to investigate these issues. We consecutively recruited 100 patients (49 males; median age 82 years) who received NIV treatment for acute respiratory failure due to COPD exacerbation in non-ICU medical wards of our hospital, between November 2008 and July 2012. We assessed survival (both in-hospital and out-of-hospital) of all these patients, and analyzed baseline parameters in a Cox proportional hazards model to develop a prognostic score. The median survival in the study population was 383 days (240-980). Overall survival rates were 71.0, 65.3, and 52.7 % at 1, 3, and 12 months, respectively. Age >85 years, a history of heart disorders and a neutrophil count ≥10 × 10(9) were associated with higher mortality at Cox's analysis (χ (2) = 35.766, p = 0.0001), and were used to build a prognostic score (NC85). The presence of two or more factors determined the deepest drop in survival (when NC85 ≥2, mortality at 1, 3, and 12 was 60.7, 70.4, and 77.2 %, respectively, while when NC85 = 0 were 4.0, 4.0, and 14.0 %). A simple model, based on three variables (age, neutrophil count and history of heart disease), accurately predicts survival of COPD patients receiving NIV in a non-ICU setting.

  14. Ventilation-air conditioning system

    International Nuclear Information System (INIS)

    Kubokoya, Takashi.

    1991-01-01

    Heretofore, in ventilation-air conditioning systems in a nuclear power plant, exhaust gases from each of the ventilation-air conditioning systems of a reactor building, a turbine building, a waste processing building are joined and they are released into atmosphere from the top of a high main exhaustion stack. In order to build such a high main exhaustion stack, a considerable construction cost is required and, in addition, there is a worry of lacking balance with surrounding scenery. Then, in the present invention, exhaust gases are heated by waste heat in a turbine during their introduction from the ventilation-air conditioning facility in the building of a power plant to the main exhaust stack. With such a constitution, since the exhaust gases are heated and their temperature is elevated, they uprise by natural convection when they are released from the top of the main exhaustion stack to the atmosphere. Accordingly, they are released to a level higher than the conventional case in view of the volume of the blower which sends the exhaust gases under pressure, to diffuse them to the atmosphere more sufficiently compared with a conventional case. Further, the height of the main exhaustion stack can be reduced, enabling to minimize the cost for moving the blower. (T.M.)

  15. EVALUATION TOOL OF CLIMATE POTENTIAL FOR VENTILATIVE COOLING

    DEFF Research Database (Denmark)

    Belleri, Annamaria; Psomas, Theofanis Ch.; Heiselberg, Per Kvols

    2015-01-01

    . Within IEA Annex 62 project, national experts are working on the development of a climate evaluation tool, which aims at assessing the potential of ventilative cooling by taking into account also building envelope thermal properties, internal gains and ventilation needs. The analysis is based on a single......-zone thermal model applied to user-input climatic data on hourly basis. The tool identifies the percentage of hours when natural ventilation can be exploited to assure minimum air change rates required by state of the art research, standards and regulations and the percentage of hours when direct ventilative...

  16. Ventilating Air-Conditioner

    Science.gov (United States)

    Dinh, Khanh

    1994-01-01

    Air-conditioner provides ventilation designed to be used alone or incorporated into cooling or heating system operates efficiently only by recirculating stale air within building. Energy needed to operate overall ventilating cooling or heating system slightly greater than operating nonventilating cooling or heating system. Helps to preserve energy efficiency while satisfying need for increased forced ventilation to prevent accumulation of undesired gases like radon and formaldehyde. Provides fresh treated air to variety of confined spaces: hospital surgeries, laboratories, clean rooms, and printing shops and other places where solvents used. In mobile homes and portable classrooms, eliminates irritant chemicals exuded by carpets, panels, and other materials, ensuring healthy indoor environment for occupants.

  17. Receding Horizon Optimal Control of a Solar Greenhouse. GreenSys2004, Leuven, 2004 september 12-16

    NARCIS (Netherlands)

    Ooteghem, van R.J.C.; Stigter, J.D.; Willigenburg, van L.G.; Straten, van G.

    2004-01-01

    A solar greenhouse has been designed that maximizes solar energy use and minimizes fossil energy consumption. It is based on a conventional Venlo greenhouse extended with a heat pump, a heat exchanger, an aquifer and ventilation with heat recovery. The aim is to minimize fossil energy consumption,

  18. Meeting Residential Ventilation Standards Through Dynamic Control of Ventilation Systems

    OpenAIRE

    Sherman, Max H.

    2011-01-01

    Existing ventilation standards, including American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE) Standard 62.2, specify continuous operation of a defined mechanical ventilation system to provide minimum ventilation, with time-based intermittent operation as an option. This requirement ignores several factors and concerns including: other equipment such as household exhaust fans that might incidentally provide ventilation, negative impacts of ventilation when outd...

  19. Plant Physiology in Greenhouses

    NARCIS (Netherlands)

    Heuvelink, E.; Kierkels, T.

    2015-01-01

    Since 2004 Ep Heuvelink and Tijs Kierkels have been writing a continuing series of plant physiology articles for the Dutch horticultural journal Onder Glas and the international edition In Greenhouses. The book Plant Physiology in Greenhouses consists of 50 of their plant physiology articles. The

  20. Geothermal Greenhouse Information Package

    Energy Technology Data Exchange (ETDEWEB)

    Rafferty, K. [P.E.; Boyd, T. [ed.

    1997-01-01

    This package of information is intended to provide a foundation of background information for developers of geothermal greenhouses. The material is divided into seven sections covering such issues as crop culture and prices, operating costs for greenhouses, heating system design, vendors and a list of other sources of information.

  1. The greenhouse effect gases

    International Nuclear Information System (INIS)

    2006-06-01

    This road-map proposes by the Group Total aims to inform the public on the greenhouse effect gases. It presents the greenhouses effect as a key component of the climate system, the impacts of the human activity, the foreseeable consequences of global warming, the Kyoto protocol and Total commitment in the domain. (A.L.B.)

  2. The greenhouse effect

    International Nuclear Information System (INIS)

    2004-01-01

    In the framework of the sustainable development, this paper presents the greenhouse effect and its impact on the climatic change, the world interest from Rio to Buenos Aires, the human activities producing the carbon dioxide and responsible of the greenhouse effect, the carbon dioxide emission decrease possibilities and shows the necessity of the electric power producers contribution. (A.L.B.)

  3. Towards the semiclosed greenhouse

    NARCIS (Netherlands)

    Hemming, S.

    2009-01-01

    What can we do right now to reduce the consumption of fossil fuels in the greenhouse sector? What technologies should we concentrate on in the future? Researchers, consultants and technology enterprises working with the greenhouse sector have tried to answer these questions in collaboration with the

  4. The impacts of balanced and exhaust mechanical ventilation on indoor radon

    International Nuclear Information System (INIS)

    Fisk, W.J.; Mowris, R.J.

    1987-02-01

    Models for estimating radon entry rates, indoor radon concentrations, and ventilation rates in houses with a basement or a vented crawl-space and ventilated by natural infiltration, mechanical exhaust ventilation, or balanced mechanical ventilation are described. Simulations are performed for a range of soil and housing characteristics using hourly weather data for the heating season in Spokane, WA. For a house with a basement, we show that any ventilation technique should be acceptable when the soil permeability is less than approximately 10 -12 m 2 . However, exhaust ventilation leads to substantially higher indoor radon concentrations than infiltration or balanced ventilation with the same average air exchange rate when the soil permeability is 10 -10 m 2 or greater. For houses with a crawl-space, indoor radon concentrations are lowest with balanced ventilation, intermediate with exhaust ventilation, and highest with infiltration

  5. Achievements and opportunities from ESF Research Networking Programme: Natural molecular structures as drivers and tracers of terrestrial C fluxes, and COST Action 639: Greenhouse gas budget of soils under changing climate and land use

    Science.gov (United States)

    Boeckx, P.; Rasse, D.; Jandl, R.

    2009-04-01

    One of the activities of the European Science Foundation (ESF, www.esf.org) is developing European scale Research Networking Programmes (RNPs). RNPs lay the foundation for nationally funded research groups to address major scientific and research infrastructure issues, in order to advance the frontiers of existing science. MOLTER (www.esf.org/molter or www.molter.no) is such an RNP. MOLTER stands for "Natural molecular structures as drivers and tracers of terrestrial C fluxes" aims at stimulating the use of isotopic and organic chemistry to study carbon stabilization and biogeochemistry in terrestrial ecosystems and soils in particular. The understanding of the formation, stabilization and decomposition of complex organic compounds in the environment is currently being revolutionized by advanced techniques in identification, quantification, and origin tracing of functional groups and individual molecules. MOLTER focuses on five major research themes: - Molecular composition and turnover time of soil organic matter; - Plant molecular structures as drivers of C stabilisation in soils; - Fire transformations of plant and soil molecular structures - Molecular markers in soils; - Dissolved organic molecules in soils: origin, functionality and transport. These research themes are covered via the following activities: - Organisation of international conferences; - Organisation of specific topical workshops; - Organisation of summer schools for PhD students; - Short- and long-term exchange grants for scientists. MOLTER is supported by research funding or performing agencies from Austria, Belgium, France, Germany, the Netherlands, Norway, Romania, Spain, Sweden, Switzerland and the United Kingdom. The ESF is also the implementing agency of COST (European Cooperation in Science and Technology, www.cost.esf.org), one of the longest-running European instruments supporting cooperation among scientists and researchers across Europe. COST Action 639 "Greenhouse gas budget of

  6. Why We Ventilate

    Energy Technology Data Exchange (ETDEWEB)

    Logue, Jennifer M.; Sherman, Max H.; Price, Phil N.; Singer, Brett C.

    2011-09-01

    It is widely accepted that ventilation is critical for providing good indoor air quality (IAQ) in homes. However, the definition of"good" IAQ, and the most effective, energy efficient methods for delivering it are still matters of research and debate. This paper presents the results of work done at the Lawrence Berkeley National Lab to identify the air pollutants that drive the need for ventilation as part of a larger effort to develop a health-based ventilation standard. First, we present results of a hazard analysis that identified the pollutants that most commonly reach concentrations in homes that exceed health-based standards or guidelines for chronic or acute exposures. Second, we present results of an impact assessment that identified the air pollutants that cause the most harm to the U.S. population from chronic inhalation in residences. Lastly, we describe the implications of our findings for developing effective ventilation standards.

  7. What Is a Ventilator?

    Science.gov (United States)

    ... who are on ventilators for shorter periods. The advantage of this tube is that it can be ... other disease or condition. VAP is treated with antibiotics. You may need special antibiotics if the VAP ...

  8. Uranium mine ventilation

    International Nuclear Information System (INIS)

    Katam, K.; Sudarsono

    1982-01-01

    Uranium mine ventilation system aimed basically to control and decreasing the air radioactivity in mine caused by the radon emanating from uranium ore. The control and decreasing the air ''age'' in mine, with adding the air consumption volume, increasing the air rate consumption, closing the mine-out area; using closed drainage system. Air consumption should be 60m 3 /minute for each 9m 2 uranium ore surfaces with ventilation rate of 15m/minute. (author)

  9. Fire, safety and ventilation

    Energy Technology Data Exchange (ETDEWEB)

    Hindle, D.

    1999-02-01

    Correct ventilation in tunnel environments is vital for the comfort and safety of the people passing through. This article gives details of products from several manufacturers of safety rescue and fire fighting equipment, fire and fume detection equipment, special fire resistant materials, fire resistant hydraulic oils and fire dampers, and ventilation systems. Company addresses and fax numbers are supplied. 4 refs., 5 tabs., 10 photos.

  10. National Greenhouse Gas Emission Inventory

    Data.gov (United States)

    U.S. Environmental Protection Agency — The National Greenhouse Gas Emission Inventory contains information on direct emissions of greenhouse gases as well as indirect or potential emissions of greenhouse...

  11. Lay perceptions of the greenhouse effect

    International Nuclear Information System (INIS)

    Peretti-Watel, P.; Hammer, B.

    2006-01-01

    Using the data from the French Environment Barometer EDF-RD 2004 (national representative sample of French citizens aged over 15) and surveys by ADEME between 2000 and 2005, the paper investigates lay perceptions of the causes and consequences of the greenhouse effect, which may be considered as archetypical of contemporary environmental risks. Beyond lay lack of knowledge, the greenhouse effect gives rise to coherent and meaningful cognitions, including causal explanations, shaped by the pre-existing cognitive framework. This cognitive work, based on analogic rather than scientific thought, strings together the greenhouse effect, ozone depletion, air pollution and even nuclear power. The cognitive process is also fed by the individuals' general conceptions of Nature and of the rights and duties of humankind towards Nature. People are not greatly worried about the unseen and controversial consequences of the greenhouse effect: such worry could be one of those 'elite fears' mentioned by Beck. Finally, while the efficiency of public policies to counter the greenhouse effect requires extensive societal involvement, low confidence towards both political and scientific authorities may prevent the population from becoming aware of the environmental stakes tied to the greenhouse effect. (authors)

  12. On the influence of the ventilation rate to the radiation burden in dwellings

    International Nuclear Information System (INIS)

    Tschurlovits, M.

    1980-01-01

    Calculations on the influence of the ventilation rate to the concentration of radon in dwellings from radioactive material of natural origin in building material are completed with a few examples of measurements. In addition, the optimization of the ventilation rate and the consequences of poorly ventilated dwellings are reported briefly. (author)

  13. 46 CFR 182.465 - Ventilation of spaces containing diesel machinery.

    Science.gov (United States)

    2010-10-01

    ... furnish natural or powered supply and exhaust ventilation. The total inlet area and the total outlet area... 46 Shipping 7 2010-10-01 2010-10-01 false Ventilation of spaces containing diesel machinery. 182... Ventilation of spaces containing diesel machinery. (a) A space containing diesel machinery must be fitted with...

  14. The greenhouse effect

    International Nuclear Information System (INIS)

    Berger, A.

    1991-01-01

    The greenhouse effect on earth can be defined as the long wave energy trapped in the atmosphere. Climate forcing and climate system response within which climate feedback mechanisms are contained are determined. Quantitative examples illustrate what could happen if the greenhouse effect is perturbed by human activities, in particular if CO2 atmospheric concentration would double in the future. Recent satellite measurements of the greenhouse effect are given. The net cooling effect of clouds and whether or not there will be less cooling by clouds as the planet warms are also discussed

  15. Through the greenhouse window

    International Nuclear Information System (INIS)

    Townsley, M.

    1989-01-01

    Nuclear power is being promoted as the only answer to the greenhouse effect. However, power station emissions (from fossil-fuel powered stations) account for only a fraction of the total carbon dioxide emissions. And carbon dioxide accounts for only about a half of the global warming effect -the other gases which create the greenhouse effect must also be limited. Nuclear energy is neither a practical nor economic alternative. Energy efficiency and conservation is a far better answer to the greenhouse effect. (U.K.)

  16. Climate, greenhouse effect, energy

    International Nuclear Information System (INIS)

    Henriksen, Thormod; Kanestroem, Ingolf

    2001-01-01

    The book has sections on the sun as energy source, the earth climate and it's changes and factors influencing this, the greenhouse effect on earth and other planets, greenhouse gases and aerosols and their properties and importance, historic climate and paleoclimate, climatic models and their uses and limitations, future climate, consequences of climatic changes, uncertainties regarding the climate and measures for reducing the greenhouse effect. Finally there are sections on energy and energy resources, the use, sources such as fossil fuels, nuclear power, renewable resources, heat pumps, energy storage and environmental aspects and the earth magnetic field is briefly surveyed

  17. Demand Controlled Ventilation in a Combined Ventilation and Radiator System

    OpenAIRE

    Hesaraki, Arefeh; Holmberg, Sture

    2013-01-01

    With growing concerns for efficient and sustainable energy treatment in buildings there is a need for balanced and intelligent ventilation solutions. This paper presents a strategy for demand controlled ventilation with ventilation radiators, a combined heating and ventilation system. The ventilation rate was decreased from normal requirements (per floor area) of 0.375 l·s-1·m-2 to 0.100 l·s-1·m-2 when the residence building was un-occupied. The energy saving potential due to decreased ventil...

  18. A numerical simulated model of the impact of the surrounding vegetation on the natural ventilation of the factory buildings%植被对厂房自然通风影响的数值模拟研究

    Institute of Scientific and Technical Information of China (English)

    李孔清; 邹声华

    2012-01-01

    This paper presents a numerical simulated model for the influence of the surrounding vegetation on the three-dimensional natural ventilation of the factory buildings, which consist of equations for momentum, turbulence energy and its dissipation rate, and temperature . The influence of the vegetation on the air ventilation is generally considered by the source (or sink) terms added to the momentum and standard k-E model and the energy equation. The source (or sink) terms for the turbulent energy and its dissipation rate are adopted from the works of Foudhil which is based on the numerical integration of neutral atmospheric current equations for the energy-dissipating closure and over a domain that may include vegetation layers. The source (or sink) terms being added to the energy equation include the sensible and latent heat transfer between the air and the vegetation which can be worked out on the basis of temperature difference between the local air mass and the vegetation leaves. Then, it is possible to set up the closure of the energy equation, and the implicit e-quation of the energy balance model for the canopy by using the Newton- Kaphson method. All in all, what our research is aimed at is to build a statistical device to predict the flow field over the landscape characterized by the heterogeneous vegetation cover so as to find how the outdoor vegetation affects the indoor temperature of the buildings. For the validation of the method, it is necessary to simulate an industrial building with a micro-forest upwind. The simulation results of underlying surface temperature, air temperature, and vegetation-leaf' s temperature are in good agreement with the measured data and fully reflect the actual temperature distribution trends. Thus, it can be concluded that being accurate, the suggested model we have developed can be used in the research of building natural ventilation affected by the outdoor vegetation. In so ding, the temperature feeling of the workers in

  19. Ventilation of nuclear rooms and operators' protection

    International Nuclear Information System (INIS)

    Vavasseur, C.

    1985-01-01

    Ventilation systems are designed to guarantee air replacement in rooms so as to evacuate gases, odors and aerosols liable to be produced therein. This air is conditioned, filtered, heated, and the relative humidity checked. At the outlet, a filtration system adapted to the type of effluent prevents the external dispersion of toxic substances. Ventilation is defined by the air change time. A comfort rule recommends reducing the velocities reaching the person present in less than 0.2 m/sec. This reduction is achieved by adjusting the natural property of the jets, induction, by means of diffusers placed at the vents

  20. Clinical challenges in mechanical ventilation.

    Science.gov (United States)

    Goligher, Ewan C; Ferguson, Niall D; Brochard, Laurent J

    2016-04-30

    Mechanical ventilation supports gas exchange and alleviates the work of breathing when the respiratory muscles are overwhelmed by an acute pulmonary or systemic insult. Although mechanical ventilation is not generally considered a treatment for acute respiratory failure per se, ventilator management warrants close attention because inappropriate ventilation can result in injury to the lungs or respiratory muscles and worsen morbidity and mortality. Key clinical challenges include averting intubation in patients with respiratory failure with non-invasive techniques for respiratory support; delivering lung-protective ventilation to prevent ventilator-induced lung injury; maintaining adequate gas exchange in severely hypoxaemic patients; avoiding the development of ventilator-induced diaphragm dysfunction; and diagnosing and treating the many pathophysiological mechanisms that impair liberation from mechanical ventilation. Personalisation of mechanical ventilation based on individual physiological characteristics and responses to therapy can further improve outcomes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Economic, Environmental and Health Implications of Enhanced Ventilation in Office Buildings.

    Science.gov (United States)

    MacNaughton, Piers; Pegues, James; Satish, Usha; Santanam, Suresh; Spengler, John; Allen, Joseph

    2015-11-18

    Current building ventilation standards are based on acceptable minimums. Three decades of research demonstrates the human health benefits of increased ventilation above these minimums. Recent research also shows the benefits on human decision-making performance in office workers, which translates to increased productivity. However, adoption of enhanced ventilation strategies is lagging. We sought to evaluate two of the perceived potential barriers to more widespread adoption-Economic and environmental costs. We estimated the energy consumption and associated per building occupant costs for office buildings in seven U.S. cities, representing different climate zones for three ventilation scenarios (standard practice (20 cfm/person), 30% enhanced ventilation, and 40 cfm/person) and four different heating, ventilation and air conditioning (HVAC) system strategies (Variable Air Volume (VAV) with reheat and a Fan Coil Unit (FCU), both with and without an energy recovery ventilator). We also estimated emissions of greenhouse gases associated with this increased energy usage, and, for comparison, converted this to the equivalent number of vehicles using greenhouse gas equivalencies. Lastly, we paired results from our previous research on cognitive function and ventilation with labor statistics to estimate the economic benefit of increased productivity associated with increasing ventilation rates. Doubling the ventilation rate from the American Society of Heating, Refrigeration and Air-Conditioning Engineers minimum cost less than $40 per person per year in all climate zones investigated. Using an energy recovery ventilation system significantly reduced energy costs, and in some scenarios led to a net savings. At the highest ventilation rate, adding an ERV essentially neutralized the environmental impact of enhanced ventilation (0.03 additional cars on the road per building across all cities). The same change in ventilation improved the performance of workers by 8

  2. Economic, Environmental and Health Implications of Enhanced Ventilation in Office Buildings

    Directory of Open Access Journals (Sweden)

    Piers MacNaughton

    2015-11-01

    Full Text Available Introduction: Current building ventilation standards are based on acceptable minimums. Three decades of research demonstrates the human health benefits of increased ventilation above these minimums. Recent research also shows the benefits on human decision-making performance in office workers, which translates to increased productivity. However, adoption of enhanced ventilation strategies is lagging. We sought to evaluate two of the perceived potential barriers to more widespread adoption—Economic and environmental costs. Methods: We estimated the energy consumption and associated per building occupant costs for office buildings in seven U.S. cities, representing different climate zones for three ventilation scenarios (standard practice (20 cfm/person, 30% enhanced ventilation, and 40 cfm/person and four different heating, ventilation and air conditioning (HVAC system strategies (Variable Air Volume (VAV with reheat and a Fan Coil Unit (FCU, both with and without an energy recovery ventilator. We also estimated emissions of greenhouse gases associated with this increased energy usage, and, for comparison, converted this to the equivalent number of vehicles using greenhouse gas equivalencies. Lastly, we paired results from our previous research on cognitive function and ventilation with labor statistics to estimate the economic benefit of increased productivity associated with increasing ventilation rates. Results: Doubling the ventilation rate from the American Society of Heating, Refrigeration and Air-Conditioning Engineers minimum cost less than $40 per person per year in all climate zones investigated. Using an energy recovery ventilation system significantly reduced energy costs, and in some scenarios led to a net savings. At the highest ventilation rate, adding an ERV essentially neutralized the environmental impact of enhanced ventilation (0.03 additional cars on the road per building across all cities. The same change in ventilation

  3. Reflections on greenhouse gas life cycle assessment

    International Nuclear Information System (INIS)

    Jarrell, J.; Phillips, B.; Pendergast, D.

    1999-01-01

    The amount of carbon dioxide equivalent greenhouse gas emitted per unit of electricity produced is an important consideration in the planning of future greenhouse gas reduced electricity supply systems. Useful estimates of emissions must also take into account the entire cradle to grave life cycle emissions of alternative systems. Thus emissions of greenhouse gases take into account all of the components of building operating, and decommissioning facilities. This requires an accounting of emissions from production of all materials used to build the plants, transportation of materials to the site as well as fuels used for their construction, operation, and decommissioning. The construction of facilities may also have effects which tend to affect greenhouse gas emissions through modification of the local environment. A notable example, often cited, is the evolution of methane from the decay of organic matter submerged by dams built to serve hydro power facilities. In the long term, we anticipate that some kind of cost will be associated with the release of greenhouse gases. In that event it may be argued that the modified economic system established by inclusion of this cost will naturally control the emission of greenhouse gases from competing means of electricity production. Greenhouse gas emissions from all stages involved in the birth and retirement of electricity producing plant could be suitably constrained as the least cost method of production is sought. Such an ideal system is far from in place. At this point in time the results of life cycle accounting of greenhouse gas emissions are a needed means of comparing emissions from alternative sources of electricity. Many life cycle studies have been undertaken in the past. Many of the estimates are based on past practice which does not take into account any possible need to limit the production of greenhouse gas during the design of the plant and operational processes. Sources of energy used to produce materials

  4. GEOTHERMAL GREENHOUSING IN TURKEY

    Directory of Open Access Journals (Sweden)

    Sedat Karaman

    2016-07-01

    Full Text Available Use of renewable energy resources should be brought forward to reduce heating costs of greenhouses and to minimize the use of ever-depleting fossil fuels. Geothermal energy not only provides the heat required throughout plant growth, but also allow a year-long production. Geothermal resources with several other benefits therefore play significant role in agricultural activities. With regard to geothermal potential and implementation, Turkey has the 7th place in the world and the 1st place in Europe. Majority of country geothermal resources is used in greenhouse heating. The size of geothermal greenhouses increased 5 folds during the last decade and reached to 2500 decare. In this study, current status of geothermal greenhousing of Turkey was presented; problems and possible solutions were discussed.

  5. Computer control of the greenhouse climate - an introduction

    Energy Technology Data Exchange (ETDEWEB)

    Andreasson, I; Stroem, K

    1983-01-01

    A typical greenhouse has, compared to other kinds of buildings, a rather low thermal mass, rather bad insulation and it acts as a solar collector during a hot day. The dynamical behaviour of the greenhouse, when it is heated, is influenced by that kind of heating system which is in use, i.e. hot air heating compared to water pipe heating. In the water pipe system a lot of heat is stored in the pipes. The ventilation rate is strongly dependent on the wind speed and the direction of the wind. This causes problems with regard to the control of the ventilation windows. The introduction of computers for controlling the greenhouse environment raises possibilities of a totally new development in this field. In the computer several functions, earlier separated, can be integrated, i.e. heating, ventilation, water, CO/sub 2/-enrichment, shading, light a.s.o. More complicated control algorithms can be used as the software is easy to modify. The capability of the computer to process information makes it possible, at least to some degree, to optimize the crop yield depending on how much resources that are consumed, i.e. energy. Intense research all over the world opens new areas, due to new sensor constructions. An interesting field is the hydropond growing of plants.

  6. Solar greenhouse aquaculture

    Energy Technology Data Exchange (ETDEWEB)

    Toever, W V

    1979-01-01

    Rainbow and Speckled Trout have been successfully hatched and reared in a recirculating aquaculture system. The system is integrated into the Ark greenhouse providing thermal mass for temperature regulation and supplying nutrient-rich water for plants. The system incorporates bacterial, algal and hydroponic water filtration. Various vegetable crops have been raised in the hydroponic troughs. A scaled-down system suitable for domestic solar greenhouse application is also under development.

  7. Regional greenhouse climate effects

    International Nuclear Information System (INIS)

    Hansen, J.; Rind, D.; Delgenio, A.; Lacis, A.; Lebedeff, S.; Prather, M.; Ruedy, R.; Karl, T.

    1990-01-01

    The authors discuss the impact of an increasing greenhouse effect on three aspects of regional climate: droughts, storms and temperature. A continuous of current growth rates of greenhouse gases causes an increase in the frequency and severity of droughts in their climate model simulations, with the greatest impacts in broad regions of the subtropics and middle latitudes. But the greenhouse effect enhances both ends of the hydrologic cycle in the model, that is, there is an increased frequency of extreme wet situations, as well as increased drought. Model results are shown to imply that increased greenhouse warming will lead to more intense thunderstorms, that is, deeper thunderstorms with greater rainfall. Emanual has shown that the model results also imply that the greenhouse warming leads to more destructive tropical cyclones. The authors present updated records of observed temperatures and show that the observations and model results, averaged over the globe and over the US, are generally consistent. The impacts of simulated climate changes on droughts, storms and temperature provide no evidence that there will be regional winners if greenhouse gases continue to increase rapidly

  8. Mechanical ventilation strategies.

    Science.gov (United States)

    Keszler, Martin

    2017-08-01

    Although only a small proportion of full term and late preterm infants require invasive respiratory support, they are not immune from ventilator-associated lung injury. The process of lung damage from mechanical ventilation is multifactorial and cannot be linked to any single variable. Atelectrauma and volutrauma have been identified as the most important and potentially preventable elements of lung injury. Respiratory support strategies for full term and late preterm infants have not been as thoroughly studied as those for preterm infants; consequently, a strong evidence base on which to make recommendations is lacking. The choice of modalities of support and ventilation strategies should be guided by the specific underlying pathophysiologic considerations and the ventilatory approach must be individualized for each patient based on the predominant pathophysiology at the time. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. [Ventilator associated pneumonia].

    Science.gov (United States)

    Bellani, S; Nesci, M; Celotto, S; Lampati, L; Lucchini, A

    2003-04-01

    Ventilator associated pneumonia (VAP) is a nosocomial lower respiratory tract infection that ensues in critically ill patients undergoing mechanical ventilation. The reported incidence of VAP varies between 9% and 68% with a mortality ranging between 33% and 71%. Two key factors are implicated in the pathogenesis of VAP: bacterial colonization of the upper digestive-respiratory tract and aspiration of oral secretions into the trachea. Preventive measurements are advocated to reduce the incidence of VAP, such as selective decontamination of the digestive tract (SDD), supraglottic aspiration and positioning. Prompt recognition and treatment of established VAP has also been demostrated to affect outcome. Therefore, the knowledge of risk factors associated with the development of VAP and the implementation of strategies to prevent, diagnose and treat VAP are mainstems in the nursing of mechanically ventilated patients.

  10. CFD and Ventilation Research

    DEFF Research Database (Denmark)

    Li, Y.; Nielsen, Peter V.

    2011-01-01

    There has been a rapid growth of scientific literature on the application of computational fluid dynamics (CFD) in the research of ventilation and indoor air science. With a 1000–10,000 times increase in computer hardware capability in the past 20 years, CFD has become an integral part...... of scientific research and engineering development of complex air distribution and ventilation systems in buildings. This review discusses the major and specific challenges of CFD in terms of turbulence modelling, numerical approximation, and boundary conditions relevant to building ventilation. We emphasize...... the growing need for CFD verification and validation, suggest on-going needs for analytical and experimental methods to support the numerical solutions, and discuss the growing capacity of CFD in opening up new research areas. We suggest that CFD has not become a replacement for experiment and theoretical...

  11. Auxiliary mine ventilation manual

    International Nuclear Information System (INIS)

    Workplace Safety North

    2010-01-01

    An adequate ventilation system is needed for air quality and handling in a mine and is comprised of many different pieces of equipment for removing contaminated air and supplying fresh air and thereby provide a satisfactory working environment. This manual highlights auxiliary ventilation systems made up of small fans, ducts, tubes, air movers, deflectors and additional air flow controls which distribute fresh air delivered by the primary system to all areas. A review of auxiliary ventilation is provided. Design, operation and management issues are discussed and guidelines are furnished. This manual is limited to underground hard rock operations and does not address directly other, specific auxiliary systems, either in underground coal mines or uranium mines.

  12. Auxiliary mine ventilation manual

    Energy Technology Data Exchange (ETDEWEB)

    Workplace Safety North

    2010-07-01

    An adequate ventilation system is needed for air quality and handling in a mine and is comprised of many different pieces of equipment for removing contaminated air and supplying fresh air and thereby provide a satisfactory working environment. This manual highlights auxiliary ventilation systems made up of small fans, ducts, tubes, air movers, deflectors and additional air flow controls which distribute fresh air delivered by the primary system to all areas. A review of auxiliary ventilation is provided. Design, operation and management issues are discussed and guidelines are furnished. This manual is limited to underground hard rock operations and does not address directly other, specific auxiliary systems, either in underground coal mines or uranium mines.

  13. Nuclear power and the greenhouse effect

    International Nuclear Information System (INIS)

    1989-01-01

    Carbon dioxide from fossil fuel combustion accounts for about 40% of the global warming due to the 'greenhouse effect'. Thus national energy policies of the fuels used to generate electricity can have a significant effect on the levels of gas emissions which contribute to the 'greenhouse effect'. The more efficient use of energy is the first way of controlling the increase in gas emissions. The use of natural gas instead of coal or oil would also be beneficial but the reserves of natural gas are limited. The use of nuclear-generated electricity has already reduced the level of global warming by 3% but could have a greater effect in the future. Ways in which the government could reduce 'greenhouse' gas emissions are listed. These include the more extensive use of nuclear power for generating electricity not only for domestic but industrial uses. (U.K.)

  14. Effects of types of ventilation system on indoor particle concentrations in residential buildings.

    Science.gov (United States)

    Park, J S; Jee, N-Y; Jeong, J-W

    2014-12-01

    The objective of this study was to quantify the influence of ventilation systems on indoor particle concentrations in residential buildings. Fifteen occupied, single-family apartments were selected from three sites. The three sites have three different ventilation systems: unbalanced mechanical ventilation, balanced mechanical ventilation, and natural ventilation. Field measurements were conducted between April and June 2012, when outdoor air temperatures were comfortable. Number concentrations of particles, PM2.5 and CO2 , were continuously measured both outdoors and indoors. In the apartments with natural ventilation, I/O ratios of particle number concentrations ranged from 0.56 to 0.72 for submicron particles, and from 0.25 to 0.60 for particles larger than 1.0 μm. The daily average indoor particle concentration decreased to 50% below the outdoor level for submicron particles and 25% below the outdoor level for fine particles, when the apartments were mechanically ventilated. The two mechanical ventilation systems reduced the I/O ratios by 26% for submicron particles and 65% for fine particles compared with the natural ventilation. These results showed that mechanical ventilation can reduce exposure to outdoor particles in residential buildings. Results of this study confirm that mechanical ventilation with filtration can significantly reduce indoor particle levels compared with natural ventilation. The I/O ratios of particles substantially varied at the naturally ventilated apartments because of the influence of variable window opening conditions and unsteadiness of wind flow on the penetration of outdoor air particles. For better prediction of the exposure to outdoor particles in naturally ventilated residential buildings, it is important to understand the penetration of outdoor particles with variable window opening conditions. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  15. Factors defining value and direction of thermal pressure between the mine shafts and impact of the general mine natural draught on ventilation process of underground mining companies

    Science.gov (United States)

    Nikolaev, A. V.; Alymenko, N. I.; Kamenskikh, A. A.; Alymenko, D. N.; Nikolaev, V. A.; Petrov, A. I.

    2017-10-01

    The article specifies measuring data of air parameters and its volume flow in the shafts and on the surface, collected in BKPRU-2 (Berezniki potash plant and mine 2) («Uralkali» PJSC) in normal operation mode, after shutdown of the main mine fan (GVU) and within several hours. As a result of the test it has been established that thermal pressure between the mine shafts is active continuously regardless of the GVU operation mode or other draught sources. Also it has been discovered that depth of the mine shafts has no impact on thermal pressure value. By the same difference of shaft elevation marks and parameters of outer air between the shafts, by their different depth, thermal pressure of the same value will be active. Value of the general mine natural draught defined as an algebraic sum of thermal pressure values between the shafts depends only on the difference of temperature and pressure of outer air and air in the shaft bottoms on condition of shutdown of the air handling system (unit-heaters, air conditioning systems).

  16. Ventilation with heat recovery

    DEFF Research Database (Denmark)

    Tommerup, Henrik M.; Svendsen, Svend

    2005-01-01

    This paper presents the experiences from the use of ventilation with heat recovery in several experimental single-family houses developed and built within the last four years to meet the new Danish energy requirements of 2005. Included are descriptions of the ventilation system components...... and the main functional demands as well as measurements of the thermal efficiency, electricity consumptions and building air tightness. The paper addresses the aspects of minimizing the heat loss from the duct system and the heat recovery unit (when placed in an unheated attic space) in order to obtain...

  17. Behovstyret ventilation til enfamiliehuse

    DEFF Research Database (Denmark)

    Nielsen, Toke Rammer; Drivsholm, Christian; Hansen, Mads Peter Rudolph

    Muligheden for behovsstyret ventilation i enfamiliehuse er undersøgt. To strategier er afprøvet i praksis: En relativ simpel og billig strategi og en relativ avanceret og dyr strategi. Den simple strategi regulerer luftskiftet ensartet for alle rum mellem et lavt eller højt niveau. Den avancerede...... ventilation efter gældende krav. Desuden kræver den simple regulering kun få sensorer og er således væsentlig billigere og enklere at implementere end den avancerede strategi....

  18. Bench performance of ventilators during simulated paediatric ventilation.

    Science.gov (United States)

    Park, M A J; Freebairn, R C; Gomersall, C D

    2013-05-01

    This study compares the accuracy and capabilities of various ventilators using a paediatric acute respiratory distress syndrome lung model. Various compliance settings and respiratory rate settings were used. The study was done in three parts: tidal volume and FiO2 accuracy; pressure control accuracy and positive end-expiratory pressure (PEEP) accuracy. The parameters set on the ventilator were compared with either or both of the measured parameters by the test lung and the ventilator. The results revealed that none of the ventilators could consistently deliver tidal volumes within 1 ml/kg of the set tidal volume, and the discrepancy between the delivered volume and the volume measured by the ventilator varied greatly. The target tidal volume was 8 ml/kg, but delivered tidal volumes ranged from 3.6-11.4 ml/kg and the volumes measured by the ventilator ranged from 4.1-20.6 ml/kg. All the ventilators maintained pressure within 20% of the set pressure, except one ventilator which delivered pressures of up to 27% higher than the set pressure. Two ventilators maintained PEEP within 10% of the prescribed PEEP. The majority of the readings were also within 10%. However, three ventilators delivered, at times, PEEPs over 20% higher. In conclusion, as lung compliance decreases, especially in paediatric patients, some ventilators perform better than others. This study highlights situations where ventilators may not be able to deliver, nor adequately measure, set tidal volumes, pressure, PEEP or FiO2.

  19. Demand controlled ventilation; Behovsstyrt ventilasjon

    Energy Technology Data Exchange (ETDEWEB)

    Soerensen, Henning Holm

    2006-07-01

    The terms CAV and VAV have been known terms for many years in the ventilation business. The terms are also included in building regulations, but the time is now right to focus on demand controlled ventilation (DCV). The new building regulations and the accompanying energy framework underline the need for a more nuanced thinking when it comes to controlling ventilation systems. Descriptions and further details of the ventilation systems are provided (ml)

  20. 46 CFR 32.55-5 - Ventilation of tank vessels constructed between November 10, 1936, and July 1, 1951-TB/ALL.

    Science.gov (United States)

    2010-10-01

    ... actuated gas ejectors or blowers or ventilators fitted with heads for natural ventilation, will be approved... 46 Shipping 1 2010-10-01 2010-10-01 false Ventilation of tank vessels constructed between November... HOMELAND SECURITY TANK VESSELS SPECIAL EQUIPMENT, MACHINERY, AND HULL REQUIREMENTS Ventilation and Venting...

  1. Battery life of portable home ventilators: effects of ventilator settings.

    Science.gov (United States)

    Falaize, Line; Leroux, Karl; Prigent, Hélène; Louis, Bruno; Khirani, Sonia; Orlikowski, David; Fauroux, Brigitte; Lofaso, Frédéric

    2014-07-01

    The battery life (BL) of portable home ventilator batteries is reported by manufacturers. The aim of this study was to evaluate the effects of ventilator mode, breathing frequency, PEEP, and leaks on the BL of 5 commercially available portable ventilators. The effects of the ventilator mode (volume controlled-continuous mandatory ventilation [VC-CMV] vs pressure support ventilation [PSV]), PEEP 5 cm H2O, breathing frequency (10, 15, and 20 breaths/min), and leaks during both volume-targeted ventilation and PSV on the BL of 5 ventilators (Elisée 150, Monnal T50, PB560, Vivo 50, and Trilogy 100) were evaluated. Each ventilator was ventilated with a test lung at a tidal volume of 700 ml and an inspiratory time of 1.2 s in the absence of leaks. Switching from PSV to VC-CMV or the addition of PEEP did not significantly change ventilator BL. The increase in breathing frequency from 10 to 20 breaths/min decreased the BL by 18 ± 11% (P = .005). Leaks were associated with an increase in BL during the VC-CMV mode (18 ± 20%, P = .04) but a decrease in BL during the PSV mode (-13 ± 15%, P = .04). The BL of home ventilators depends on the ventilator settings. BL is not affected by the ventilator mode (VC-CMV or PSV) or the addition of PEEP. BL decreases with an increase in breathing frequency and during leaks with a PSV mode, whereas leaks increase the duration of ventilator BL during VC-CMV. Copyright © 2014 by Daedalus Enterprises.

  2. Recent data concerning contribution of various greenhouse effect gas sources

    International Nuclear Information System (INIS)

    Lambert, G.

    1991-01-01

    The greenhouse effect contributes to a +33 degrees C warming of the earth atmosphere (mean temperature of +15 deg C instead of -18 deg C without any greenhouse effect). The roles of water vapour, carbon dioxide and methane in greenhouse effect are discussed; the CH 4 raise seems to be due to rice cultivation and cattle farming; the CO 2 raise is mainly due oil, coal and natural gas burning. Greenhouse gas increase will cause a 2 to 4 deg C increase of the earth mean temperature but the anthropogenous causes will be obviously seen only during the next century

  3. Buying greenhouse insurance

    International Nuclear Information System (INIS)

    Manne, A.S.; Richels, R.G.

    1992-01-01

    A growing concern that the increasing accumulation of greenhouse gases will lead to undesirable changes in global climate has resulted in proposals, both in the United States and internationally, to set physical targets for reducing greenhouse gas emissions. But what will these proposals cost? This book outlines a way to think about greenhouse-effect decisions under uncertainty. It describes an insightful model for determining the economic costs of limiting CO 2 emissions produced by burning fossil fuels and provides a solid analytical base for rethinking public policy on the far-reaching issue of global warming. It presents region-by-region estimates of the costs that would underlie an international agreement. Using a computer model known as Global 2100, they analyze the economic impacts of limiting CO 2 emissions under alternative supply and conservation scenarios. The results clearly indicate that a reduction in emissions is not the sole policy response to potential climate change. Following a summary of the greenhouse effect, its likely causes, and possible consequences, this book takes up issues that concern the public at large. They provide an overview of Global 2100, look at how the U.S. energy sector is likely to evolve under business-as-usual conditions and under carbon constraints, and describe the concept of greenhouse insurance. They consider possible global agreements, including an estimate of benefits that might result from trading in an international market in emission rights. They conclude with a technical description directed toward modeling specialists

  4. Hybrid Ventilation Air Flow Process

    DEFF Research Database (Denmark)

    Heiselberg, Per Kvols

    The scope of this annex is therefore to obtain better knowledge of the use of hybrid ventilation technologies. The annex focus on development of control strategies for hybrid ventilation, on development of methods to predict hybrid ventilation performance in office buildings and on implementation...

  5. Ventilator and viral induced inflammation

    NARCIS (Netherlands)

    Hennus, M.P.

    2013-01-01

    This thesis expands current knowledge on ventilator induced lung injury and provides insights on the immunological effects of mechanical ventilation during viral respiratory infections. The experimental studies in the first part of this thesis improve our understanding of how mechanical ventilation

  6. How to Plan Ventilation Systems.

    Science.gov (United States)

    Clarke, John H.

    1963-01-01

    Ventilation systems for factory safety demand careful planning. The increased heat loads and new processes of industry have introduced complex ventilation problems in--(1) ventilation supply, (2) duct work design, (3) space requirements, (4) hood face velocities, (5) discharge stacks, and (6) building eddies. This article describes and diagrams…

  7. Thermal Plumes in Ventilated Rooms

    DEFF Research Database (Denmark)

    Kofoed, P.; Nielsen, Peter Vilhelm

    The main objective of ventilation is to provide good air quality for the occupants. For this purpose the necessary ventilating air change rate must be determined. Within displacement ventilation the estimation is closely related to the air flow rate in the thermal plumes when an air quality based...

  8. Greenhouse gas emissions from Savanna ( Miombo ) woodlands ...

    African Journals Online (AJOL)

    Natural vegetation represents an important sink for greenhouse gases (GHGs); however, there is relatively little information available on emissions from southern African savannas. The effects of clearing savanna woodlands for crop production on soil fluxes of N2O, CO2 and CH4 were studied on clay (Chromic luvisol) and ...

  9. The amazing Minivent ventilator

    African Journals Online (AJOL)

    Southern African Journal of Anaesthesia and Analgesia is co-published by Medpharm Publications, NISC (Pty) Ltd and Cogent, ... Respiratory rate was obtained by counting the clicking noise ... was appointed as a part-time lecturer to the University of the ... The Minivent became the first of three miniature ventilators that.

  10. Omnidirectional ventilated acoustic barrier

    Science.gov (United States)

    Zhang, Hai-long; Zhu, Yi-fan; Liang, Bin; Yang, Jing; Yang, Jun; Cheng, Jian-chun

    2017-11-01

    As an important problem in acoustics, sound insulation finds applications in a great variety of situations. In the existing schemes, however, there has always been a trade-off between the thinness of sound-insulating devices and their ventilating capabilities, limiting their potentials in the control of low-frequency sound in high ventilation environments. Here, we design and experimentally implement an omnidirectional acoustic barrier with a planar profile, subwavelength thickness ( 0.18 λ ), yet high ventilation. The proposed mechanism is based on the interference between the resonant scattering of discrete states and the background scattering of continuous states which induces a Fano-like asymmetric transmission profile. Benefitting from the binary-structured design of the coiled unit and hollow pipe, it maximally simplifies the design and fabrication while ensuring the ventilation for all the non-resonant units with open tubes. The simulated and measured results agree well, showing the effectiveness of our proposed mechanism to block low frequency sound coming from various directions while allowing 63% of the air flow to pass. We anticipate our design to open routes to design sound insulators and to enable applications in traditionally unattainable cases such as those calling for noise reduction and cooling simultaneously.

  11. Mechanical ventilation of mice

    NARCIS (Netherlands)

    Schwarte, L. A.; Zuurbier, C. J.; Ince, C.

    2000-01-01

    Due to growing interest in murine functional genomics research, there is an increasing need for physiological stable in vivo murine models. Of special importance is support and control of ventilation by artificial respiration, which is difficult to execute as a consequence of the small size of the

  12. Lavt elforbrug til ventilation

    DEFF Research Database (Denmark)

    Jagemar, L.; Bergsøe, Niels Christian

    Rapporten giver gode råd om mulige energibesparelser og praktiske projekteringshensyn, som er forbundet med udformning af energieffektiv ventilation i ikke blot kontorbygninger, men i alle bygninger med komfortventilationsanlæg. I forbindelse med projektering af ventilationsanlæg har interessen...

  13. Understanding mechanical ventilators.

    Science.gov (United States)

    Chatburn, Robert L

    2010-12-01

    The respiratory care academic community has not yet adopted a standardized system for classifying and describing modes of ventilation. As a result, there is enough confusion that patient care, clinician education and even ventilator sales are all put at risk. This article summarizes a ventilator mode taxonomy that has been extensively published over the last 15 years. Specifically, the classification system has three components: a description of the control variables within breath; a description of the sequence of mandatory and spontaneous breaths; and a specification for the targeting scheme. This three-level specification provides scalability of detail to make the mode description appropriate for the particular need. At the bedside, we need only refer to a mode briefly using the first or perhaps first and second components. To distinguish between similar modes and brand names, we would need to include all components. This taxonomy uses the equation of motion for the respiratory system as the underlying theoretical framework. All terms relevant to describing modes of mechanical ventilation are defined in an extensive appendix.

  14. A review of greenhouse gas research in Canada

    International Nuclear Information System (INIS)

    Yundt, P.

    1995-11-01

    Greenhouse gas research programs and projects that relate to the Canadian natural gas industry were presented. Fossil fuel related emissions, primarily methane and carbon dioxide, impact on the atmospheric concentrations of the greenhouse gases. Therefore, strategies to reduce these emissions should impact on the Canadian natural gas industry. A list of 39 projects and 18 research programs of potential interest to the natural gas industry were presented in summary form. The involvement of CANMET (Canada Centre for Mineral and Energy Technology), Environment Canada, and NSERC (Natural Sciences and Engineering Research Council) in doing or sponsoring research projects directed towards greenhouse gas emission reduction was highlighted. Some potential options for member companies of the Canadian natural gas industry, to support climate change and greenhouse gas research, were outlined. 6 refs., 12 tabs

  15. Human response to ductless personalized ventilation coupled with displacement ventilation

    DEFF Research Database (Denmark)

    Dalewski, Mariusz; Veselý, Michal; Melikov, Arsen K.

    2012-01-01

    A human subject experiment was carried out to investigate the extent to which ductless personalized ventilation (DPV) in conjunction with displacement ventilation can improve perceived air quality (PAQ) and thermal comfort at elevated room air temperature in comparison with displacement ventilation...... alone. The experimental conditions comprised displacement ventilation alone (room air temperature of 23 °C, 26 °C, 29 °C) and DPV with displacement ventilation (26 °C, 29 °C), both operating at supply air temperatures 3, 5 or 6K lower than room air temperature, as well as mixing ventilation (23 °C, 3 K......). During one hour exposure participants answered questionnaires regarding PAQ and thermal comfort. PAQ was significantly better with DPV than without DPV at the same background conditions. Thermal comfort improved when DPV was used. Combining DPV with displacement ventilation showed the potential...

  16. Nunavut housing ventilation research 2003-2005

    Energy Technology Data Exchange (ETDEWEB)

    Fugler, D.

    2005-11-15

    Inuit children in Alaska and Nunavut have high rates of severe lower respiratory tract infections, with hospitalization rates of 300 per year for each 1000 infants. The aim of this research report was to summarize the findings of a pilot project measuring the indoor air quality (IAQ) in 20 Cape Dorset houses as well as a study measuring the ventilation rates of 100 house from 4 communities in Nunavut. The 20 house pilot study included a respiratory questionnaire; a detailed home inspection and data collection; a blower door airtightness test; 7 day measurements of nitrogen dioxide (NO{sub 2}), nicotine, carbon dioxide (CO{sub 2}), relative humidity and temperature; a natural air change rate testing using Brookhaven tracer gas technology; and settled floor dust and bed dust collection followed by biological analysis. The 100 house study recorded 3 to 5 days of house temperatures, relative humidity and CO{sub 2}. The Brookhaven tracer gas technique was used to establish house air change rate. A questionnaire was used to assess ventilation devices. A medical questionnaire was administered and an evaluation of hospitalization data was carried out. Results indicated that a large number of Nunavut houses were not adequately ventilated. In the 20 house study, a third of the houses showed air change rates that would be considered low by any ventilation standards, and that were very low when considering the high occupancy of the houses. In the hundred house study, almost all houses indicated a mean CO{sub 2} level over 1000 ppm, and peaks exceeded 2000 ppm in approximately half the houses. The concentrations were far higher than those seen in southern Canadian homes. It was concluded that the development and promotion of energy-efficient ventilation devices could help to resolve ventilation deficiencies in Nunavut. 2 figs.

  17. Greenhouse effects on Venus

    Science.gov (United States)

    Bell, Peter M.

    Calculations that used Pioneer-Venus measurements of atmosphere composition, temperature profiles, and radiative heating predicted Venus' surface temperature ‘very precisely,’ says the Ames Research Center. The calculations predict not only Venus' surface temperature but agree with temperatures measured at various altitudes above the surface by the four Pioneer Venus atmosphere probe craft.Using Pioneer-Venus spacecraft data, a research team has virtually proved that the searing 482° C surface temperature of Venus is due to an atmospheric greenhouse effect. Until now the Venus greenhouse effect has been largely a theory.

  18. Harnessing greenhouse effect

    International Nuclear Information System (INIS)

    Meunier, F.; Rivet, P.; Terrier, M.F.

    2005-01-01

    This book considers the energy and greenhouse effect questions in a global way. It presents the different methods of fight against the increase of the greenhouse effect (energy saving, carbon sinks, cogeneration,..), describes the main alternative energy sources to fossil fuels (biomass, wind power, solar, nuclear,..), and shows that, even worrying, the future is not so dark as it seems to be and that technical solutions exist which will allow to answer the worldwide growing up energy needs and to slow down the climatic drift. (J.S.)

  19. Ventilation of nuclear power plants

    International Nuclear Information System (INIS)

    Madoyan, A.A.; Vlasik, V.F.

    1984-01-01

    Foundations and calculation methods of ventilation of rooms with different degree of heat and gas release with the change of operation mode of NPP main equipment, as well as problems of NPP site and adjoining area aerodynamics, have been presented. Systems of air ventilation and conditioning, cooling equipment, are considered. The main points of designing are described and determination of economic efficiency of the ventilation systems are made. Technical characteristics of the ventilators, conditioners, filters and air heaters used, are presented. Organization of adjustment, tests, operation and maintenance of the ventilation systems of NPP with RBMK and WWER-type reactors, is described

  20. Outcome-based ventilation: A framework for assessing performance, health, and energy impacts to inform office building ventilation decisions.

    Science.gov (United States)

    Rackes, A; Ben-David, T; Waring, M S

    2018-04-23

    This article presents an outcome-based ventilation (OBV) framework, which combines competing ventilation impacts into a monetized loss function ($/occ/h) used to inform ventilation rate decisions. The OBV framework, developed for U.S. offices, considers six outcomes of increasing ventilation: profitable outcomes realized from improvements in occupant work performance and sick leave absenteeism; health outcomes from occupant exposure to outdoor fine particles and ozone; and energy outcomes from electricity and natural gas usage. We used the literature to set low, medium, and high reference values for OBV loss function parameters, and evaluated the framework and outcome-based ventilation rates using a simulated U.S. office stock dataset and a case study in New York City. With parameters for all outcomes set at medium values derived from literature-based central estimates, higher ventilation rates' profitable benefits dominated negative health and energy impacts, and the OBV framework suggested ventilation should be ≥45 L/s/occ, much higher than the baseline ~8.5 L/s/occ rate prescribed by ASHRAE 62.1. Only when combining very low parameter estimates for profitable impacts with very high ones for health and energy impacts were all outcomes on the same order. Even then, however, outcome-based ventilation rates were often twice the baseline rate or more. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  1. ASHRAE and residential ventilation

    Energy Technology Data Exchange (ETDEWEB)

    Sherman, Max H.

    2003-10-01

    In the last quarter of a century, the western world has become increasingly aware of environmental threats to health and safety. During this period, people psychologically retreated away from outdoors hazards such as pesticides, smog, lead, oil spills, and dioxin to the seeming security of their homes. However, the indoor environment may not be healthier than the outdoor environment, as has become more apparent over the past few years with issues such as mold, formaldehyde, and sick-building syndrome. While the built human environment has changed substantially over the past 10,000 years, human biology has not; poor indoor air quality creates health risks and can be uncomfortable. The human race has found, over time, that it is essential to manage the indoor environments of their homes. ASHRAE has long been in the business of ventilation, but most of the focus of that effort has been in the area of commercial and institutional buildings. Residential ventilation was traditionally not a major concern because it was felt that, between operable windows and envelope leakage, people were getting enough outside air in their homes. In the quarter of a century since the first oil shock, houses have gotten much more energy efficient. At the same time, the kinds of materials and functions in houses changed in character in response to people's needs. People became more environmentally conscious and aware not only about the resources they were consuming but about the environment in which they lived. All of these factors contributed to an increasing level of public concern about residential indoor air quality and ventilation. Where once there was an easy feeling about the residential indoor environment, there is now a desire to define levels of acceptability and performance. Many institutions--both public and private--have interests in Indoor Air Quality (IAQ), but ASHRAE, as the professional society that has had ventilation as part of its mission for over 100 years, is the

  2. Ventilation in Sewers Quantified by Measurements of CO2

    DEFF Research Database (Denmark)

    Fuglsang, Emil Dietz; Vollertsen, Jes; Nielsen, Asbjørn Haaning

    2012-01-01

    Understanding and quantifying ventilation in sewer systems is a prerequisite to predict transport of odorous and corrosive gasses within the system as well as their interaction with the urban atmosphere. This paper studies ventilation in sewer systems quantified by measurements of the natural...... occurring compound CO2. Most often Danish wastewater is supersaturated with CO2 and hence a potential for stripping is present. A novel model was built based on the kinetics behind the stripping process. It was applied to simulate ventilation rates from field measurements of wastewater temperature, p...

  3. Smarter greenhouse climate control

    NARCIS (Netherlands)

    Nederhoff, E.M.; Houter, G.

    2011-01-01

    Greenhouse operators strive to be as economic as possible with energy. However, investing in fancy energy-saving equipment is often not cost-effective for smaller operations and in climate zones with mild winters. It is possible, though, for many growers to save energy without buying special

  4. Reduction of heat losses from greenhouses by means of internal blinds with low thermal emissivity

    NARCIS (Netherlands)

    Meijer, J.

    1980-01-01

    Heat losses in greenhouses may be substantially reduced by the use of heat reflecting blinds. Quantitative results are obtained solving a mathematical heat flow model by numerical methods. Special attention has been given to the emissivity and transmittance of the screen and the ventilation through

  5. Greenhouse cooling using a rainwater basin under the greenhouse

    NARCIS (Netherlands)

    Campen, J.B.

    2006-01-01

    The objective of the study was to determine the technical and economical aspects of additional applications for a rainwater basin installed under a greenhouse. The installation for cooling the greenhouse can be placed under the greenhouse. Part of the installation consists of a short-term heat store

  6. High Frequency Oscillatory Ventilation

    Directory of Open Access Journals (Sweden)

    AC Bryan

    1996-01-01

    Full Text Available High frequency oscillatory (HFO ventilation using low tidal volume and peak airway pressures is extremely efficient at eliminating carbon dioxide and raising pH in the newborn infant with acute respiratory failure. Improvement in oxygenation requires a strategy of sustained or repetitive inflations to 25 to 30 cm H2O in order to place the lung on the deflation limb of the pressure-volume curve. This strategy has also been shown to decrease the amount of secondary lung injury in animal models. Experience of the use of HFO ventilation as a rescue therapy as well as several published controlled trials have shown improved outcomes and a decrease in the use of extracorporeal membrane oxygenation when it has been used in newborns.

  7. Diffuse Ceiling Ventilation

    DEFF Research Database (Denmark)

    Zhang, Chen; Yu, Tao; Heiselberg, Per Kvols

    cooling capacity, energy saving, low investment cost and low noise level; while the limitations include condensation risk and the limit on the room geometry. Furthermore, the crucial design parameters are summarized and their effects on the system performance are discussed. In addition to the stand...... is not well structured with this system. These become the motivations in developing the design guide. This design guide aims to establish a systematic understanding of diffuse ceiling ventilation and provide assistance in designing of such a system. The guide is targeted at design engineers, architects...... and manufacturers and the users of diffuse ceiling technology. The design guide introduces the principle and key characteristics of room air distribution with diffuse ceiling ventilation. It provides an overview of potential benefit and limitations of this technology. The benefits include high thermal comfort, high...

  8. Purge ventilation operability

    International Nuclear Information System (INIS)

    Marella, J.R.

    1995-01-01

    A determination of minimum requirements for purge exhaust ventilation system operability has been performed. HLWE and HLW Regulatory Program personnel have evaluated the various scenarios of equipment conditions and HLWE has developed the requirements for purge exhaust systems. This report is provided to document operability requirements to assist Tank Farm personnel to determine whether a system is operable/inoperable and to define required compensatory actions

  9. Ventilation i industrien

    DEFF Research Database (Denmark)

    Valbjørn, O.

    I en række afsnit belyses problemer med træk, kulde, varme, og luftforurening på industriens arbejdspladser, og hvordan man ved ventilation og bygningsudformning kan bekæmpe disse gener. Hvert afsnit kan i princippet læses for sig, og anvisningen kan derfor bruges som håndbog, både af de der er...

  10. 75 FR 14081 - Mandatory Reporting of Greenhouse Gases: Minor Harmonizing Changes to the General Provisions

    Science.gov (United States)

    2010-03-24

    ... (subpart NN): (A) All fractionators. (B) All local natural gas distribution companies. Industrial greenhouse gas suppliers (subpart OO): (A) All producers of industrial greenhouse gases. (B) Importers of industrial greenhouse gases with annual bulk imports of N2O, fluorinated GHG, and CO2 that in combination are...

  11. Greenhouse production systems for people

    NARCIS (Netherlands)

    Giacomelli, G.A.; Sase, S.; Cramer, R.; Hoogeboom, J.; McKenzie, A.; Parbst, K.; Sacrascia-Mugnozza, G.; Selina, P.; Sharp, D.A.; Voogt, J.O.; Weel, van P.A.; Mears, D.

    2012-01-01

    Environmentally sound greenhouse production requires that: demand for market products is understood; greenhouse design addresses the climate circum-stances; input resources are available and consumed efficiently, and; there must be a reasonable balance of production products to the environmental

  12. Nuclear energy and greenhouse effect

    International Nuclear Information System (INIS)

    Strub, R.A.

    1991-01-01

    The contribution of nuclear power plants against the greenhouse effects is evaluated, not only nuclear energy is unable to fight greenhouse effect increase but long life wastes endanger environment. 8 refs

  13. Greenhouse Gas Data Publication Tool

    Data.gov (United States)

    U.S. Environmental Protection Agency — This tool to gives you access to greenhouse gas data reported to EPA by large facilities and suppliers in the United States through EPA's Greenhouse Gas Reporting...

  14. Ventilation in nuclear facilities. Organisation of nuclear safety in France

    International Nuclear Information System (INIS)

    Bouhet, J.C.

    1982-01-01

    Having defined safety and analysis of safety, the nature and significance of nuclear hazards are indicated, highlighting the importance of ventilation for safety. The authorization procedure for the creation and commissioning of an installation is also indicated. The list of safety organizations in France is given. Mention is then made of the general technical regulations, their aim and working out. To conclude, normalization and its application to the ventilation of nuclear installations is examined [fr

  15. Humidification during Mechanical Ventilation in the Adult Patient

    OpenAIRE

    Al Ashry, Haitham S.; Modrykamien, Ariel M.

    2014-01-01

    Humidification of inhaled gases has been standard of care in mechanical ventilation for a long period of time. More than a century ago, a variety of reports described important airway damage by applying dry gases during artificial ventilation. Consequently, respiratory care providers have been utilizing external humidifiers to compensate for the lack of natural humidification mechanisms when the upper airway is bypassed. Particularly, active and passive humidification devices have rapidly evo...

  16. Effect of ventilation type on radon concentration at places of work

    International Nuclear Information System (INIS)

    Oksanen, E.

    1994-01-01

    Indoor radon ( 222 Rn) concentrations were measured at 76 child care facilities and 36 schools in southern Finland. The buildings had three different types of ventilation systems: mechanical air supply and exhaust, mechanical exhaust, and natural ventilation, the first being most common. The effect of the ventilation type on the long-term radon concentration was studied in child care facilities. The radon concentrations were highest in the naturally ventilated buildings. The mechanical air supply and exhaust system maintained the lowest values in cold wintertime. In school buildings both the long-term radon concentration and short-term radon and daughter concentrations were measured. The correlation of the ventilation type and the radon concentration was not obvious in this group of measurements, but the radon concentrations and the equilibrium factors were highest in buildings with natural ventilation. Radon concentrations were generally lower during the working hours than during the one-month period, as expected. (author)

  17. Noninvasive Ventilation in Premature Neonates.

    Science.gov (United States)

    Flanagan, Keri Ann

    2016-04-01

    The use of noninvasive ventilation is a constantly evolving treatment option for respiratory disease in the premature infant. The goals of these noninvasive ventilation techniques are to improve gas exchange in the premature infant's lungs and to minimize the need for intubation and invasive mechanical ventilation. The goals of this article are to consider various uses of nasal interfaces, discuss skin care and developmental positioning concerns faced by the bedside nurse, and discuss the medical management aimed to reduce morbidity and mortality. This article explores the nursing role, the advances in medical strategies for noninvasive ventilation, and the team approach to noninvasive ventilation use in this population. Search strategy included a literature review on medical databases, such as EBSCOhost, CINAHL, PubMed, and NeoReviews. Innovative products, nursing research on developmental positioning and skin care, and advanced medical management have led to better and safer outcomes for premature infants requiring noninvasive ventilation. The medical focus of avoiding long-term mechanical ventilation would not be possible without the technology to provide noninvasive ventilation to these premature infants and the watchful eye of the nurse in terms of careful positioning, preventing skin breakdown and facial scarring, and a proper seal to maximize ventilation accuracy. This article encourages nursing-based research to quantify some of the knowledge about skin care and positioning as well as research into most appropriate uses for noninvasive ventilation devices.

  18. Performance evaluation of ventilation radiators

    International Nuclear Information System (INIS)

    Myhren, Jonn Are; Holmberg, Sture

    2013-01-01

    A ventilation radiator is a combined ventilation and heat emission unit currently of interest due to its potential for increasing energy efficiency in exhaust-ventilated buildings with warm water heating. This paper presents results of performance tests of several ventilation radiator models conducted under controlled laboratory conditions. The purpose of the study was to validate results achieved by Computational Fluid Dynamics (CFD) in an earlier study and identify possible improvements in the performance of such systems. The main focus was on heat transfer from internal convection fins, but comfort and health aspects related to ventilation rates and air temperatures were also considered. The general results from the CFD simulations were confirmed; the heat output of ventilation radiators may be improved by at least 20% without sacrificing ventilation efficiency or thermal comfort. Improved thermal efficiency of ventilation radiators allows a lower supply water temperature and energy savings both for heating up and distribution of warm water in heat pumps or district heating systems. A secondary benefit is that a high ventilation rate can be maintained all year around without risk for cold draught. -- Highlights: ► Low temperature heat emitters are currently of interest due to their potential for increasing energy efficiency. ► A ventilation radiator is a combined ventilation and heat emission unit which can be adapted to low temperature heating systems. ► We examine how ventilation radiators can be made to be more efficient in terms of energy consumption and thermal comfort. ► Current work focuses on heat transfer mechanisms and convection fin configuration of ventilation radiators

  19. Localized climate control in greenhouses

    NARCIS (Netherlands)

    Booij, P.S.; Sijs, J.; Fransman, J.E.

    2012-01-01

    Strategies for controlling the indoor climate in greenhouses are based on a few sensors and actuators in combination with an assumption that climate variables, such as temperature, are uniform throughout the greenhouse. While this is already an improper assumption for conventional greenhouses, it

  20. Pretest Predictions for Ventilation Tests

    International Nuclear Information System (INIS)

    Y. Sun; H. Yang; H.N. Kalia

    2007-01-01

    The objective of this calculation is to predict the temperatures of the ventilating air, waste package surface, concrete pipe walls, and insulation that will be developed during the ventilation tests involving various test conditions. The results will be used as input to the following three areas: (1) Decisions regarding testing set-up and performance. (2) Assessing how best to scale the test phenomena measured. (3) Validating numerical approach for modeling continuous ventilation. The scope of the calculation is to identify the physical mechanisms and parameters related to thermal response in the ventilation tests, and develop and describe numerical methods that can be used to calculate the effects of continuous ventilation. Sensitivity studies to assess the impact of variation of linear power densities (linear heat loads) and ventilation air flow rates are included. The calculation is limited to thermal effect only