Calculating solar photovoltaic potential on residential rooftops in Kailua Kona, Hawaii

Science.gov (United States)

Carl, Caroline

As carbon based fossil fuels become increasingly scarce, renewable energy sources are coming to the forefront of policy discussions around the globe. As a result, the State of Hawaii has implemented aggressive goals to achieve energy independence by 2030. Renewable electricity generation using solar photovoltaic technologies plays an important role in these efforts. This study utilizes geographic information systems (GIS) and Light Detection and Ranging (LiDAR) data with statistical analysis to identify how much solar photovoltaic potential exists for residential rooftops in the town of Kailua Kona on Hawaii Island. This study helps to quantify the magnitude of possible solar photovoltaic (PV) potential for Solar World SW260 monocrystalline panels on residential rooftops within the study area. Three main areas were addressed in the execution of this research: (1) modeling solar radiation, (2) estimating available rooftop area, and (3) calculating PV potential from incoming solar radiation. High resolution LiDAR data and Esri's solar modeling tools and were utilized to calculate incoming solar radiation on a sample set of digitized rooftops. Photovoltaic potential for the sample set was then calculated with the equations developed by Suri et al. (2005). Sample set rooftops were analyzed using a statistical model to identify the correlation between rooftop area and lot size. Least squares multiple linear regression analysis was performed to identify the influence of slope, elevation, rooftop area, and lot size on the modeled PV potential values. The equations built from these statistical analyses of the sample set were applied to the entire study region to calculate total rooftop area and PV potential. The total study area statistical analysis findings estimate photovoltaic electric energy generation potential for rooftops is approximately 190,000,000 kWh annually. This is approximately 17 percent of the total electricity the utility provided to the entire island in

Impact of Rooftop Solar PV on Residential Distribution Network

DEFF Research Database (Denmark)

Bhattarai, Bishnu Prasad; Bak-Jensen, Birgitte; Pillai, Jayakrishnan Radhakrishna

Increased environmental awareness in recent years has encouraged rapid growth of renewable energy sources especially solar PV and wind. Among them, small scale solar PV has been gaining more momentum especially at residential level. Even today moderate penetration of grid tied rooftop solar PV has...... become reality in many countries. In spite of various benefits, higher penetration of rooftop PVs might come up with number of detrimental effects, with power quality and overcurrent protection being the major ones. Therefore, it is reasonable to quantify both drawback and benefits of rooftop PV...

Elevated temperatures are associated with stress in rooftop-nesting Common Nighthawk (Chordeiles minor) chicks.

Science.gov (United States)

Newberry, Gretchen N; Swanson, David L

2018-01-01

Grasslands and riparian forests in southeastern South Dakota have been greatly reduced since historical times, primarily due to conversion to row-crop agriculture. Common Nighthawk ( Chordeiles minor ) nesting habitat includes grasslands, open woodlands and urban rooftops, but nesting sites in southeastern South Dakota are confined to rooftops, as natural nesting habitat is limited. Nighthawks nesting on exposed rooftop habitats may encounter thermal conditions that increase operative temperatures relative to vegetated land cover types. Mean humidity has increased and mean wind speed and cloud cover have decreased during the nighthawk breeding season from 1948 to 2016 in southeastern South Dakota. These changes might contribute to increasing operative temperatures at exposed rooftop nest sites and this could influence chick condition. We studied nest micro-climate and the plasma stress response for 24 rooftop-nesting nighthawk chicks from 17 nests during 2015 and 2016. High humidity prior to blood collection reduced both baseline and stress-induced plasma corticosterone (CORT). In contrast, high maximum temperatures during the day before sampling increased stress-induced CORT. The magnitude of the chick stress response was significantly negatively related to maximum wind speed for the week prior to CORT measurement. Other weather and micro-climate variables were not significant effectors of CORT metrics. Most chicks had low baseline CORT and were able to mount a stress response, but a subset of chicks ( n = 4) showed elevated baseline CORT and a negative association between the magnitude of stress response and ambient temperature. For this subset, mean ambient temperature for the day before sampling was significantly higher (2.3°C) than for chicks with typical baseline CORT levels. These data suggest that regional climate change trends could affect the ability of nighthawk chicks to mount a stress response, which, in turn, might influence the susceptibility of

77 FR 58114 - SunShot Prize: Race to the Rooftop

Science.gov (United States)

2012-09-19

...This notice announces the release of the SunShot Prize: Race to the Rooftop competition. This competition offers $10 million in prizes to those who can lower the non-hardware installation cost of rooftop solar energy systems.

Resilience of roof-top Plant-Microbial Fuel Cells during Dutch winter

NARCIS (Netherlands)

Helder, M.; Strik, D.P.B.T.B.; Timmers, R.A.; Reas, S.M.T.; Hamelers, H.V.M.; Buisman, C.J.N.

2013-01-01

The Plant-Microbial Fuel Cell (P-MFC) is in theory a technology that could produce sustainable electricity continuously. We operated two designs of the P-MFC under natural roof-top conditions in the Netherlands for 221 days, including winter, to test its resilience. Current and power densities are

DEVELOPMENT OF A HYDRONIC ROOFTOP UNIT -- HYPAK

Energy Technology Data Exchange (ETDEWEB)

Eric Lee; Dick Bourne; Mark Berman

2004-03-25

The majority of US commercial floor space is cooled by rooftop HVAC units (RTU's). RTU popularity derives chiefly from their low initial cost and relative ease of service access without disturbing building occupants. Unfortunately, current RTU's are inherently inefficient due to a combination of characteristics that unnecessarily increase cooling loads and energy use. Existing RTU's in the U.S. consume an estimated 2.4 quads annually. Inefficient RTU's create an estimated 3.5% of U.S. CO{sub 2} emissions, thus contributing significantly to global warming. Also, RTU's often fail to maintain adequate ventilation air and air filtration. This project was developed to evaluate the feasibility of a radically new ''HyPak'' RTU design that significantly and cost-effectively increases RTU performance and delivered air quality. The objective of the HyPak Project was to design, develop and test a hydronic RTU that provides a quantum improvement over conventional RTU performance. Our proposal targeted 60% and 50% reduction in electrical energy use by the HyPak RTU for dry and humid climates, respectively, when compared with a conventional unit.

Better Buildings Alliance, Advanced Rooftop Unit Campaign: Rooftop Unit Measurement and Verification (Fact Sheet)

Energy Technology Data Exchange (ETDEWEB)

2014-09-01

This document provides facility managers and building owners an introduction to measurement and verification (M&V) methods to estimate energy and cost savings of rooftop units replacement or retrofit projects to estimate paybacks or to justify future projects.

Dish-based CPV-T for rooftop generation

Science.gov (United States)

Davila-Peralta, Christian; Hyatt, Justin; Alfred, Dan; Struble, Morgan; Sodari, Frank; Angel, Roger

2017-09-01

Hybrid CPV-T with combined electrical and thermal output is well suited to solar generation from fixed limited areas, such as on the roof of an industrial or commercial facility with need for heat. This application will become especially attractive once overall electrical conversion efficiency of 40% is reached, as is projected for REhnu CPV systems using multijunction cells of 50% efficiency, anticipated in a few years. We outline here a configuration of dish- based CPV trackers optimized for close packing on a flat roof in a triangular grid, with a mirror area-to-ground area ratio of 50%. When the geometry of shadowing averaged over a year is taken into account, 80% of all the sunlight that would strike the rooftop is directed into the receivers. Such an array on a given area of flat roof will generate more electrical energy than would be possible with conventional PV panels, even if covering the entire rooftop, because of silicon's relative inefficiency. For example, in Tucson, the annual average global flux of 5.7 kWh/m2/day on a horizontal surface covered with 22% silicon modules will yield 1.25 kWh/m2/day. We show that a CPV system collecting 80% of all the direct sunlight of 7.0 kWh/m2 and converting it with 40% efficiency will yield 2.24 kWh/m2/day of rooftop area, nearly twice as much4. Thermal power will double again the total energy yield. A dual axis CPV-T tracker designed specifically very close spacing has been built to carry a single dish mirror of the standard type used in REhnu's M-8 generator, described by Stalcup et al in these proceedings1,2. Sunlight is collected and focused by a single square paraboloidal mirror, 1.65 × 1.65 m with focal length of 1.5 m. For closest possible packing without mechanical interference, and for broad distribution of load on a rooftop, the mirror and receiver are mounted to a C-ring structure, configured such that the elevation and azimuth axes intersect at a virtual pivot, at the center of the sphere that just

77 FR 36272 - SunShot Prize: America's Most Affordable Rooftop

Science.gov (United States)

2012-06-18

...The Department of Energy (DOE) announces in this notice the release of the SunShot Prize: America's Most Affordable Rooftop Solar for public comment. Interested persons are encouraged to learn about the SunShot Prize: America's Most Affordable Rooftop rules at eere.energy.gov/solar/sunshot/prize.html.

Business models and financing options for a rapid scale-up of rooftop solar power systems in Thailand

International Nuclear Information System (INIS)

Tongsopit, Sopitsuda; Moungchareon, Sunee; Aksornkij, Apinya; Potisat, Tanai

2016-01-01

Diverse solar PV business models and financing options exist in the international landscape, helping expand and accelerate the adoption of rooftop solar PV systems. The conditions for their emergence are context specific, depending on the policies, regulations, incentives, and market conditions of each country. After a review of the international landscape, this paper compiles and analyzes business models and financing options for rooftop solar PV investment in Thailand that have emerged during the period between 2013 and 2015. Despite policy discontinuity for the support of rooftop solar systems, diverse business models and financing options are driving market expansion and expanding solar access to more Thai consumers. Drawing on our policy and regulatory analyses and in-depth interviews with business representatives, we identify four types of business models and one financing option. The business models include Roof Rental, Solar PPA, Solar Leasing, and Community Solar, and the financing option is the solar loan. We analyze the drivers for their emergence, barriers to their success, and the risks from the business owners' and consumers' viewpoints. Our policy recommendation is focused on crafting a net-metering regulation with evidence-based studies on the potential costs and benefits to different stakeholders. - Highlights: •Advances understanding on PV business models in urban developing countries' context. •Reviews emerging rooftop solar business models in Thailand. •Thailand has a dynamic solar market despite policy uncertainties.

Development of a Hydronic Rooftop Unit-HyPak-MA

Energy Technology Data Exchange (ETDEWEB)

Lee, Eric; Berman, Mark

2009-11-14

The majority of U.S. commercial floor space is cooled by rooftop HVAC units (RTUs). RTU popularity derives chiefly from their low initial cost and relative ease of service access without disturbing building occupants. Unfortunately, current RTUs are inherently inefficient due to a combination of characteristics that unnecessarily increase cooling loads and energy use. 36% percent of annual U.S. energy, and two-thirds of electricity, is consumed in and by buildings. Commercial buildings consume approximately 4.2 quads of energy each year at a cost of $230 billion per year, with HVAC equipment consuming 1.2 quads of electricity. More than half of all U.S. commercial floor space is cooled by packaged HVAC units, most of which are rooftop units (RTUs). Inefficient RTUs create an estimated 3.5% of U.S. CO{sub 2} emissions, thus contributing significantly to global warming5. Also, RTUs often fail to maintain adequate ventilation air and air filtration, reducing indoor air quality. This is the second HyPak project to be supported by DOE through NETL. The prior project, referred to as HyPak-1 in this report, had two rounds of prototype fabrication and testing as well as computer modeling and market research. The HyPak-1 prototypes demonstrated the high performance capabilities of the HyPak concept, but made it clear that further development was required to reduce heat exchanger cost and improve system reliability before HyPak commercialization can commence. The HyPak-1 prototypes were limited to about 25% ventilation air fraction, limiting performance and marketability. The current project is intended to develop a 'mixed-air' product that is capable of full 0-100% modulation in ventilation air fraction, hence it was referred to as HyPak-MA in the proposal. (For simplicity, the -MA has been dropped when referencing the current project.) The objective of the HyPak Project is to design, develop and test a hydronic RTU that provides a quantum improvement over

Performance Assessment of a Solar powered Air Quality and Weather Station Placed on a School Rooftop in Hong Kong

Science.gov (United States)

Summary of compact, roof version of a Village Green Project station installed on a secondary school rooftop in Hong Kong. Preliminary comparison of the station's data against nearby regulatory monitors are summarized.

Rooftop Solar Photovoltaic Technical Potential in the United States

Energy Technology Data Exchange (ETDEWEB)

Gagnon, Pieter; Margolis, Robert; Melius, Jennifer; Phillips, Caleb; Elmore, Ryan

2016-01-01

How much energy could we generate if PV modules were installed on all of the suitable roof area in the nation? To answer this question, we first use GIS methods to process a lidar dataset and determine the amount of roof area that is suitable for PV deployment in 128 cities nationwide, containing 23% of U.S. buildings, and provide PV-generation results for a subset of those cities. We then extend the insights from that analysis to the entire continental United States. We develop two statistical models -- one for small buildings and one for medium and large buildings -- and populate them with geographic variables that correlate with rooftop's suitability for PV. We simulate the productivity of PV installed on the suitable roof area, and present the technical potential of PV on both small buildings and medium/large buildings for every state in the continental US. Within the 128 cities covered by lidar data, 83% of small buildings have a location suitable for a PV installation, but only 26% of the total rooftop area of small buildings is suitable for development. The sheer number of buildings in this class, however, gives small buildings the greatest technical potential. Small building rooftops could accommodate 731 GW of PV capacity and generate 926 TWh/year of PV energy, approximately 65% of rooftop PV's total technical potential. We conclude by summing the PV-generation results for all building sizes and therefore answering our original question, estimating that the total national technical potential of rooftop PV is 1,118 GW of installed capacity and 1,432 TWh of annual energy generation. This equates to 39% of total national electric-sector sales.

Adaptive Harmonic Compensation in Residential Distribution Grid by Roof-Top PV Systems

DEFF Research Database (Denmark)

Zangeneh Bighash, Esmaeil; Sadeghzadeh, Seyed Mohammad; Ebrahimzadeh, Esmaeil

2018-01-01

grid- connected roof-top PV inverters in residential distribution grid can be an opportunity to engage these systems in the power quality issues as custom power devices. By implementing a proper control for roof-top PV inverters, these systems may in addition to inject the fundamental current......, additionally act like a virtual harmonic resistance and dedicate their additional current capacity to compensate the harmonics of residential distribution grid. In this paper, each roof-top PV system is a grid harmonic supervisor, where it continually measures the PCC voltage harmonics by Sliding Discrete...

Rooftop photovoltaic (PV) systems : a cost–benefit analysis study of industrial halls

NARCIS (Netherlands)

Lee, B.; Trcka, M.; Hensen, J.L.M.

2013-01-01

Rooftop photovoltaic (PV) systems can be readily deployed on industrial halls with relatively large rooftop area. Feed-in tariff above the base price of electricity is offered in many countries to subsidize the high initial investment of PV systems. In order to fully capitalize the benefit of the

Rooftop runoff as a source of contamination: a review.

Science.gov (United States)

Lye, Dennis J

2009-10-15

Scientific reports concerning chemical and microbiological contaminant levels of rainwater runoff from rooftop collection in both urban and rural areas are reviewed. This alternative source of water has been documented to often contain substantial amounts of contaminants. Studies describing levels of heavy metal contamination specific to runoff from rooftop catchment areas containing exposed metal surfaces are discussed. Depending upon the intended use, scientific evidence is also accumulating that various treatments and disinfections will be required prior to release of roof-runoff water either into surface waters or for more direct consumer usage. For microbial contamination, current proposed standards and guidelines regarding this type of water source are shown to vary widely worldwide. Scientific literature reveals a lack of clarity regarding water quality guidelines and health related standards for certain types of rooftop runoff. Studies suggests that rainwater collection systems which are properly designed, maintained, and treated may provide a valuable supplement to existing water supplies by reducing demand on community water supplies/infrastructure costs, enhancing effective management of storm water runoff, and increasing restoration of underground reservoirs through controlled infiltration.

Flânerie and Acrophilia in the Postmetropolis: Rooftops in Hong Kong Cinema

NARCIS (Netherlands)

Chow, Y.F.; de Kloet, J.

2014-01-01

Living in the spectacle of Hong Kong's skyscape, how often do its dwellers actually see, not to mention reach, its rooftops? Intriguingly, despite their apparent ephemerality and inaccessibility, the vertical fringes of the city feature frequently in Hong Kong cinema: the rooftop. In this article,

Assessing the Potential for Rooftop Rainwater Harvesting from Large Public Institutions.

Science.gov (United States)

Adugna, Dagnachew; Jensen, Marina Bergen; Lemma, Brook; Gebrie, Geremew Sahilu

2018-02-14

As in many other cities, urbanization coupled with population growth worsens the water supply problem of Addis Ababa, Ethiopia, with a water supply deficit of 41% in 2016. To investigate the potential contribution of rooftop rainwater harvesting (RWH) from large public institutions, 320 such institutions were selected and grouped into 11 categories, from which 25-30% representative 588 rooftops were digitalized and the potential RWH volume computed based on a ten-year rainfall dataset. When comparing the resulting RWH potential with the water consumption, up to 2.3% of the annual, potable water supply can be provided. If reused only within one's own institution, the self-sufficiency varies from 0.9 to 649%. Non-uniform rainfall patterns add uncertainty to these numbers, since the size of the storage tank becomes critical for coverage in the dry season from October to May. Despite the low replacement potential at the city level, RWH from large institutions will enable a significant volume of potable water to be transferred to localities critically suffering from water shortage. Further, large institutions may demonstrate how RWH can be practiced, thus acting as a frontrunner for the dissemination of RWH to other types of rooftops. To narrow the water supply gap, considering rooftop RWH as an alternative water supply source is recommended. However, the present study assumed that financial constraints to install large sized storage tanks are considered as a possible challenge. Thus, future research is needed to investigate the cost-benefit balance along with the invention of a cheap storage tank as they may affect the potential contribution of RWH from rooftops.

Assessing the Potential for Rooftop Rainwater Harvesting from Large Public Institutions

Directory of Open Access Journals (Sweden)

Dagnachew Adugna

2018-02-01

Full Text Available As in many other cities, urbanization coupled with population growth worsens the water supply problem of Addis Ababa, Ethiopia, with a water supply deficit of 41% in 2016. To investigate the potential contribution of rooftop rainwater harvesting (RWH from large public institutions, 320 such institutions were selected and grouped into 11 categories, from which 25–30% representative 588 rooftops were digitalized and the potential RWH volume computed based on a ten-year rainfall dataset. When comparing the resulting RWH potential with the water consumption, up to 2.3% of the annual, potable water supply can be provided. If reused only within one’s own institution, the self-sufficiency varies from 0.9 to 649%. Non-uniform rainfall patterns add uncertainty to these numbers, since the size of the storage tank becomes critical for coverage in the dry season from October to May. Despite the low replacement potential at the city level, RWH from large institutions will enable a significant volume of potable water to be transferred to localities critically suffering from water shortage. Further, large institutions may demonstrate how RWH can be practiced, thus acting as a frontrunner for the dissemination of RWH to other types of rooftops. To narrow the water supply gap, considering rooftop RWH as an alternative water supply source is recommended. However, the present study assumed that financial constraints to install large sized storage tanks are considered as a possible challenge. Thus, future research is needed to investigate the cost-benefit balance along with the invention of a cheap storage tank as they may affect the potential contribution of RWH from rooftops.

A case study of air quality above an urban roof top vegetable farm

International Nuclear Information System (INIS)

Tong, Zheming; Whitlow, Thomas H.; Landers, Andrew; Flanner, Benjamin

2016-01-01

The effect of elevation and rooftop configuration on local air quality was investigated at the Brooklyn Grange rooftop farm during a short-term observational campaign. Using multiple particle counters and sonic anemometers deployed along vertical gradients, we found that PM_2_._5 concentration decayed with height above the street. Samples adjacent to the street had the highest average PM_2_._5 concentration and frequent stochastic spikes above background. Rooftop observations 26 m above ground showed 7–33% reductions in average PM_2_._5 concentration compared with the curbside and had far fewer spikes. A relationship between the vertical extinction rate of PM_2_._5 and atmospheric stability was found whereby less unstable atmosphere and greater wind shear led to greater PM_2_._5 extinction due to damped vertical motion of air. - Highlights: • PM_2_._5 concentrations on a rooftop farm were 7–33% lower than at ground level. • Rooftop plantings will remove less pollution due to the less steep concentration gradient. • Vegetables are exposed to less vehicular pollution on roofs than that at ground level. - PM_2_._5 concentrations on a rooftop farm were 7–33% below those at ground level, and the vertical extinction rate of PM_2_._5 varied with the atmospheric stability, and a perimeter wall was the dominant factor governing rooftop boundary layer thickness.

Relationship between rooftop and on-road concentrations of traffic-related pollutants in a busy street canyon: Ambient wind effects

International Nuclear Information System (INIS)

Kwak, Kyung-Hwan; Lee, Sang-Hyun; Seo, Jaemyeong Mango; Park, Seung-Bu; Baik, Jong-Jin

2016-01-01

Rooftop and on-road measurements of O_3, NO_2, NO_x, and CO concentrations were conducted to investigate the relationship between rooftop and on-road concentrations in a busy and shallow street canyon with an aspect ratio of ∼0.3 in Seoul, Republic of Korea, from 15 April to 1 May 2014. The median road-to-roof concentration ratios, correlation coefficients between rooftop and on-road concentrations, and temporal variations of rooftop and on-road concentrations are analyzed according to the rooftop wind directions which are two cross-canyon and two along-canyon directions. The analysis results indicate that the relationship is strong when the rooftop is situated on the downwind side rather than on the upwind side. Relative to the cross-canyon wind directions, one of the along-canyon wind directions can more enhance the relationship. A conceptual framework is proposed to explain the effect of ambient wind direction on the relationship between rooftop and on-road concentrations in a street canyon. - One of the along-canyon wind directions can enhance the relationship between rooftop and on-road concentrations of traffic-related pollutants in a busy and shallow street canyon.

Rooftop wind resource assessment using a three-dimensional ultrasonic anemometer

Energy Technology Data Exchange (ETDEWEB)

Anderson, D.C.; Whale, J.; Livingston, P.O.; Chan, D. [Murdoch Univ., Murdoch, WA (Australia)

2008-07-01

Building integrated wind turbines (BUWTs) are designed for the built environment and can be located on or next to buildings. In general, these types of urban wind turbines are less than 20 kW in rated capacity, and have the potential to contribute to the energy needs of the building and reduce overall emissions. There are currently over 32 manufacturers and 57 different urban wind turbine products available in Europe alone. The first rooftop wind system in Australia was installed in 2006. To data, 5 systems have been installed and there are plans for up to 20 more. The main problems associated with these types of systems are due to poor wind resources at the location or improper site selection for the turbine. This paper reported on a research study into initiating best practice guidelines for rooftop wind systems. There is a concern that environmentally conscious homeowners or businesses will install rooftop wind systems in support of sustainability, but without adequate consideration of safety, structural building integrity or turbine performance. The potential consequence of such projects could be the failure of the project due to underperforming turbines, noise, and vibration; or the development of a negative reputation for wind energy and the renewable energy industry. This study included 2 primary initiatives, notably a computer simulated modeling exercise and an onsite rooftop wind monitoring station. This paper focused on the methodology and justification for developing the monitoring station. An ultrasonic 3D anemometer was used to collect data and to develop a 3D wind profile. The wind regime on the rooftop in the complex terrain of the built environment was highly dynamic, turbulent, and included a strong vertical component. It was concluded that site selection for turbines must be determined by a proper feasibility study involving accurate data. Although the initial phase of the project to predict the resource and deploy the monitoring station has been

Rooftop solar photovoltaic potential in cities: how scalable are assessment approaches?

Science.gov (United States)

Castellanos, Sergio; Sunter, Deborah A.; Kammen, Daniel M.

2017-12-01

Distributed photovoltaics (PV) have played a critical role in the deployment of solar energy, currently making up roughly half of the global PV installed capacity. However, there remains significant unused economically beneficial potential. Estimates of the total technical potential for rooftop PV systems in the United States calculate a generation comparable to approximately 40% of the 2016 total national electric-sector sales. To best take advantage of the rooftop PV potential, effective analytic tools that support deployment strategies and aggressive local, state, and national policies to reduce the soft cost of solar energy are vital. A key step is the low-cost automation of data analysis and business case presentation for structure-integrated solar energy. In this paper, the scalability and resolution of various methods to assess the urban rooftop PV potential are compared, concluding with suggestions for future work in bridging methodologies to better assist policy makers.

Resilience of roof-top Plant-Microbial Fuel Cells during Dutch winter

International Nuclear Information System (INIS)

Helder, Marjolein; Strik, David P.B.T.B.; Timmers, Ruud A.; Raes, Sanne M.T.; Hamelers, Hubertus V.M.; Buisman, Cees J.N.

2013-01-01

The Plant-Microbial Fuel Cell (P-MFC) is in theory a technology that could produce sustainable electricity continuously. We operated two designs of the P-MFC under natural roof-top conditions in the Netherlands for 221 days, including winter, to test its resilience. Current and power densities are not stable under outdoor conditions. Highest obtained power density was 88 mW m −2 , which is lower than was achieved under lab-conditions (440 mW m −2 ). Cathode potential was in our case dependent on solar radiation, due to algae growth, making the power output dependent on a diurnal cycle. The anode potential of the P-MFC is influenced by temperature, leading to a decrease in electricity production during low temperature periods and no electricity production during frost periods. Due to freezing of the roots, plants did not survive winter and therefore did not regrow in spring. In order to make a sustainable, stable and weather independent electricity production system of the P-MFC attention should be paid to improving cathode stability and cold insulation of anode and cathode. Only when power output of the Plant-Microbial Fuel Cell can be increased under outdoor conditions and plant-vitality can be sustained over winter, it can be a promising sustainable electricity technology for the future. -- Highlights: ► Plant-Microbial Fuel Cells (P-MFCs) produce sustainable electricity under outdoor conditions. ► During frost periods no electricity is produced in P-MFCs. ► Cathodes limit performance of P-MFCs under outdoor conditions. ► Spartina anglica in P-MFCs does not survive on a roof-top during Dutch winter. ► The P-MFC needs optimization of power output to be a promising sustainable electricity technology

Estimating Rooftop Suitability for PV: A Review of Methods, Patents, and Validation Techniques

Energy Technology Data Exchange (ETDEWEB)

Melius, J. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Margolis, R. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Ong, S. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2013-12-01

A number of methods have been developed using remote sensing data to estimate rooftop area suitable for the installation of photovoltaics (PV) at various geospatial resolutions. This report reviews the literature and patents on methods for estimating rooftop-area appropriate for PV, including constant-value methods, manual selection methods, and GIS-based methods. This report also presents NREL's proposed method for estimating suitable rooftop area for PV using Light Detection and Ranging (LiDAR) data in conjunction with a GIS model to predict areas with appropriate slope, orientation, and sunlight. NREL's method is validated against solar installation data from New Jersey, Colorado, and California to compare modeled results to actual on-the-ground measurements.

Solar to hydrogen: Compact and cost effective CPV field for rooftop operation and hydrogen production

KAUST Repository

Burhan, Muhammad; Oh, Seung Jin; Chua, Kian Jon Ernest; Ng, Kim Choon

2016-01-01

installations at the rooftop of commercial and residential buildings are aimed to be increased to half of total installed PV. On the other hand, there is no commercial CPV system available to be suitable for rooftop operation, giving motivation

Region-Based Building Rooftop Extraction and Change Detection

Science.gov (United States)

Tian, J.; Metzlaff, L.; d'Angelo, P.; Reinartz, P.

2017-09-01

Automatic extraction of building changes is important for many applications like disaster monitoring and city planning. Although a lot of research work is available based on 2D as well as 3D data, an improvement in accuracy and efficiency is still needed. The introducing of digital surface models (DSMs) to building change detection has strongly improved the resulting accuracy. In this paper, a post-classification approach is proposed for building change detection using satellite stereo imagery. Firstly, DSMs are generated from satellite stereo imagery and further refined by using a segmentation result obtained from the Sobel gradients of the panchromatic image. Besides the refined DSMs, the panchromatic image and the pansharpened multispectral image are used as input features for mean-shift segmentation. The DSM is used to calculate the nDSM, out of which the initial building candidate regions are extracted. The candidate mask is further refined by morphological filtering and by excluding shadow regions. Following this, all segments that overlap with a building candidate region are determined. A building oriented segments merging procedure is introduced to generate a final building rooftop mask. As the last step, object based change detection is performed by directly comparing the building rooftops extracted from the pre- and after-event imagery and by fusing the change indicators with the roof-top region map. A quantitative and qualitative assessment of the proposed approach is provided by using WorldView-2 satellite data from Istanbul, Turkey.

REGION-BASED BUILDING ROOFTOP EXTRACTION AND CHANGE DETECTION

Directory of Open Access Journals (Sweden)

J. Tian

2017-09-01

Full Text Available Automatic extraction of building changes is important for many applications like disaster monitoring and city planning. Although a lot of research work is available based on 2D as well as 3D data, an improvement in accuracy and efficiency is still needed. The introducing of digital surface models (DSMs to building change detection has strongly improved the resulting accuracy. In this paper, a post-classification approach is proposed for building change detection using satellite stereo imagery. Firstly, DSMs are generated from satellite stereo imagery and further refined by using a segmentation result obtained from the Sobel gradients of the panchromatic image. Besides the refined DSMs, the panchromatic image and the pansharpened multispectral image are used as input features for mean-shift segmentation. The DSM is used to calculate the nDSM, out of which the initial building candidate regions are extracted. The candidate mask is further refined by morphological filtering and by excluding shadow regions. Following this, all segments that overlap with a building candidate region are determined. A building oriented segments merging procedure is introduced to generate a final building rooftop mask. As the last step, object based change detection is performed by directly comparing the building rooftops extracted from the pre- and after-event imagery and by fusing the change indicators with the roof-top region map. A quantitative and qualitative assessment of the proposed approach is provided by using WorldView-2 satellite data from Istanbul, Turkey.

The rise of non-imaging optics for rooftop solar collectors

Science.gov (United States)

Rosengarten, Gary; Stanley, Cameron; Ferrari, Dave; Blakers, Andrew; Ratcliff, Tom

2016-09-01

In this paper we explore the use of non-imaging optics for rooftop solar concentrators. Specifically, we focus on compound parabolic concentrators (CPCs), which form an ideal shape for cylindrical thermal absorbers, and for linear PV cells (allowing the use of more expensive but more efficient cells). Rooftops are ideal surfaces for solar collectors as they face the sky and are generally free, unused space. Concentrating solar radiation adds thermodynamic value to thermal collectors (allowing the attainment of higher temperature) and can add efficiency to PV electricity generation. CPCs allow that concentration over the day without the need for tracking. Hence they have become ubiquitous in applications requiring low concentration.

Rooftop Solar Photovoltaic Technical Potential in the United States. A Detailed Assessment

Energy Technology Data Exchange (ETDEWEB)

Gagnon, Pieter [National Renewable Energy Lab. (NREL), Golden, CO (United States); Margolis, Robert [National Renewable Energy Lab. (NREL), Golden, CO (United States); Melius, Jennifer [National Renewable Energy Lab. (NREL), Golden, CO (United States); Phillips, Caleb [National Renewable Energy Lab. (NREL), Golden, CO (United States); Elmore, Ryan [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2016-01-01

How much energy could be generated if PV modules were installed on all of the suitable roof area in the nation? To answer this question, we first use GIS methods to process a lidar dataset and determine the amount of roof area that is suitable for PV deployment in 128 cities nationwide, containing 23% of U.S. buildings, and provide PV-generation results for a subset of those cities. We then extend the insights from that analysis to the entire continental United States. We develop two statistical models--one for small buildings and one for medium and large buildings--and populate them with geographic variables that correlate with rooftop's suitability for PV. We simulate the productivity of PV installed on the suitable roof area, and present the technical potential of PV on both small buildings and medium/large buildings for every state in the continental US. Within the 128 cities covered by lidar data, 83% of small buildings have a location suitable for a PV installation, but only 26% of the total rooftop area of small buildings is suitable for development. The sheer number of buildings in this class, however, gives small buildings the greatest technical potential. Small building rooftops could accommodate 731 GW of PV capacity and generate 926 TWh/year of PV energy, approximately 65% of rooftop PV's total technical potential. We conclude by summing the PV-generation results for all building sizes and therefore answering our original question, estimating that the total national technical potential of rooftop PV is 1,118 GW of installed capacity and 1,432 TWh of annual energy generation. This equates to 39% of total national electric-sector sales.

Rooftop Solar Technical Potential for Low-to-Moderate Income Households in the United States

Energy Technology Data Exchange (ETDEWEB)

Sigrin, Benjamin O [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Mooney, Meghan E [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2018-04-17

This report presents a first-of-kind assessment of the technical potential of rooftop solar for low and moderate-income households, as well as providing insight on the distribution of solar potential by tenure, income, and other building characteristics. We find that a substantial fraction of the national rooftop solar potential is located on LMI buildings and, for all incomes, a substantial fraction on multi-family and renter-occupied buildings. We also find that rooftop solar can significantly contribute to long-term penetration targets established by the U.S. DOE, though to do so requires deployment on multi-family and renter-occupied buildings. Traditional deployment models have insufficiently enabled access to solar for these income groups and building types. Without innovation either in regulatory, market, or policy factors, a large fraction of the U.S. potential is unlikely to be addressed, as well as leading to inequalities in solar access. Ironically, potential electric bill savings from rooftop solar would have the greatest material impact on the lives of low-income households as compared to their high-income counterparts.

Rooftop PV system. Final technical progress report, Phase II

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-08-01

Under this four-year PV:BONUS Program, ECD and United Solar are developing and demonstrating two new lightweight flexible building integrated Photovoltaic (BIPV) modules specifically designed as exact replacements for conventional asphalt shingles and standing seam metal roofing. These modules can be economically and aesthetically integrated into new residential and commercial buildings, and address the even larger roofing replacement market. The modules are designed to be installed by roofing contractors without special training which minimizes the installation and balance of system costs. The modules will be fabricated from high-efficiency, multiple-junction a-Si alloy solar cells developed by ECD and United Solar. Under the Phase I Program, which ended in March 1994, we developed two different concept designs for rooftop PV modules: (1) the United Solar overlapping (asphalt shingle replacement) shingle-type modules and (2) the ECD metal roof-type modules. We also developed a plan for fabricating, testing and demonstrating these modules. Candidate demonstration sites for our rooftop PV modules were identified and preliminary engineering designs for these demonstrations were developed; a marketing study plan was also developed. The major objectives of the Phase II Program, which started in June 1994 was (1) to develop, test, and qualify these new rooftop modules; (2) to develop mechanical and electrical engineering specifications for the demonstration projects; and (3) to develop a marketing/commercialization plan.

Global Trends and Current Status of Commercial Urban Rooftop Farming

Directory of Open Access Journals (Sweden)

Devi Buehler

2016-10-01

Full Text Available The aim of this study was to analyze current practices in commercial urban rooftop farming (URF. In recent years, URF has been experiencing increasing popularity. It is a practice that is well-suited to enhancing food security in cities and reducing the environmental impact that results from long transportation distances that are common in conventional agriculture. To date, most URF initiatives have been motivated by social and educational factors rather than the aim of creating large sustainable food production systems in cities. The commercial operation of urban rooftop farms, should they become profitable, is likely to attract notable private investment, allowing a significant level of high quality urban food production to be achieved. There is a reasonable amount of literature available on urban farming that deals with its potential, and its limitations. However, it does not focus on commercial operations. In contrast to other surveys and theoretical papers, this study of URF focuses on large and commercial operations. The analysis showed that commercial URFs can be grouped into two main types: Firstly, hydroponic systems in greenhouses where mostly leafy greens, tomatoes, and herbs are grown; secondly, soil-based open-air farms that grow a large variety of vegetables. Hydroponics is frequently seen as the key technology for commercial urban food production. While the technology is not in and of itself sustainable, hydroponic farms often make an effort to implement environmentally friendly technologies and methods. However, there is still untapped potential to systemically integrate farms into buildings. The findings of this study identified where future research is needed in order to make URF a widespread sustainable solution.

An automated model for rooftop PV systems assessment in ArcGIS using LIDAR

Directory of Open Access Journals (Sweden)

Mesude Bayrakci Boz

2015-08-01

Full Text Available As photovoltaic (PV systems have become less expensive, building rooftops have come to be attractive for local power production. Identifying rooftops suitable for solar energy systems over large geographic areas is needed for cities to obtain more accurate assessments of production potential and likely patterns of development. This paper presents a new method for extracting roof segments and locating suitable areas for PV systems using Light Detection and Ranging (LIDAR data and building footprints. Rooftop segments are created using seven slope (tilt, ve aspect (azimuth classes and 6 different building types. Moreover, direct beam shading caused by nearby objects and the surrounding terrain is taken into account on a monthly basis. Finally, the method is implemented as an ArcGIS model in ModelBuilder and a tool is created. In order to show its validity, the method is applied to city of Philadelphia, PA, USA with the criteria of slope, aspect, shading and area used to locate suitable areas for PV system installation. The results show that 33.7% of the buildings footprints areas and 48.6% of the rooftop segments identi ed is suitable for PV systems. Overall, this study provides a replicable model using commercial software that is capable of extracting individual roof segments with more detailed criteria across an urban area.

Thermal conditions and perceived air quality in an air-conditioned auditorium

Science.gov (United States)

Polednik, Bernard; Guz, Łukasz; Skwarczyński, Mariusz; Dudzińska, Marzenna R.

2016-07-01

The study reports measurements of indoor air temperature (T) and relative humidity (RH), perceived air quality (PAQ) and CO2, fine aerosol particle number (PN) and mass (PM1) concentrations in an air conditioned auditorium. The measurements of these air physical parameters have been carried out in the unoccupied auditorium with the air conditioning system switched off (AC off mode) and in the unoccupied and occupied auditorium with the air conditioning system switched off during the night and switched on during the day (AC on/off mode). The average indoor air thermal parameters, CO2 concentration and the PAQ value (in decipols) were elevated, while average PM1 concentration was lower in the AC on/off mode. A statistically significant (p PAQ values and CO2 concentrations (r = 0.66 and r = 0.59, respectively) in that AC mode. A significant negative correlation has been observed between T and PN and PM1 concentrations (r = -0.38 and r = -0.49, respectively). In the AC off mode the above relations between T and the particle concentrations were not that unequivocal. These findings may be of importance as they indicate that in certain AC operation modes the indoor air quality deteriorates along with the variation of the indoor air microclimate and room occupation. This, in turn, may adversely affect the comfort and productivity of the users of air conditioned premises.

What land covers are effective in mitigating a heat island in urban building rooftop?

Science.gov (United States)

Lee, S.; Ryu, Y.

2014-12-01

Since the 20th century, due to the rapid urbanization many urban environment problems have got blossomed and above all heat island has been recognized as an important issue. There are several causes of urban heat island, but land cover change occupies the largest portion of them. Owing to urban expansion, vegetation is changed into asphalt pavements and concrete buildings, which reduces latent heat flux. To mitigate the problems, people enlarge vegetation covers such as planting street trees, making rooftop gardens and constructing parks or install white roofs that feature high albedo on a building. While the white roofs reflect about 70% of solar radiation and absorb less radiation, vegetation has low albedo but cools the air through transpiration and fixes carbon dioxide through photosynthesis. There are some studies concerning which one is more effective to mitigate heat island between the green roof and white roof. This study compares the green roof and white roof and additionally considers carbon fixation that has not been treated in other studies. Furthermore, this study ascertains an efficiency of solar-cell panel that is used for building roof recently. The panel produces electric power but has low albedo which could warm the air. The experiment is conducted at the rooftop in Seoul, Korea and compares green roof (grass), white roof (painted cover), black roof (solar panel) and normal painted roof. Surface temperature and albedo are observed for the four roof types and incoming shortwave, outgoing longwave and carbon flux are measured in green roof solely. In the case of solar panels, the electricity generation is calculated from the incoming radiation. We compute global warming potentials for the four roof types and test which roof type is most effective in reducing global warming potential.

Performance evaluation of photovoltaic systems on Kuwaiti schools’ rooftop

International Nuclear Information System (INIS)

Al-Otaibi, A.; Al-Qattan, A.; Fairouz, F.; Al-Mulla, A.

2015-01-01

Highlights: • Evaluation of rooftop PV installations at 2 Kuwaiti schools was carried out. • Lack of real plants data in the region and specifically Kuwait motivated the work. • Automated cleaning system allowed for minimization of soiling loss. • The average PV system performance was greater than 76%. • Schools show high potential for rooftop installations. - Abstract: Photovoltaic (PV) is a high-potential renewable energy technology for Kuwait to pursue due to high daily irradiation, and has garnered local attention in recent years due to the growing energy demand and concerns over climate change. As yet, no data are available regarding the actual performance of PV systems in Kuwait’s harsh environment. This paper presents a 12-month-long performance evaluation of the first 85.05 kW p and 21.6 kW p copper indium gallium selenide (CIGS) thin film, grid-connected PV systems on the rooftops of two schools. The schools’ monthly energy consumption and PV generation profiles, the actual performance of the PV plants, the effectiveness of automated cleaning systems on the power output, and the benefits of PV implementation in schools were analyzed and evaluated. Data analysis was applied to filter and normalize the data in order to identify the actual performance parameters. The findings of the study, based on solar irradiation collected, the performance of the module technology and the effectiveness of the automated cleaning systems, show that the performance ratio was maintained between 0.74 and 0.85. Furthermore, the minimum monthly energy yield of the PV systems was about 104 kW h/kW p . The annual average daily final yields of the PV systems in this study were 4.5 kW h/kW p /day. The results provided insight into the performance of CIGS grid-connected PV systems in Kuwait, and those data will be beneficial to the PV research community worldwide. School buildings, particularly for the rooftops, are a unique and important asset for urban PV system

A case study of air quality above an urban roof top vegetable farm.

Science.gov (United States)

Tong, Zheming; Whitlow, Thomas H; Landers, Andrew; Flanner, Benjamin

2016-01-01

The effect of elevation and rooftop configuration on local air quality was investigated at the Brooklyn Grange rooftop farm during a short-term observational campaign. Using multiple particle counters and sonic anemometers deployed along vertical gradients, we found that PM2.5 concentration decayed with height above the street. Samples adjacent to the street had the highest average PM2.5 concentration and frequent stochastic spikes above background. Rooftop observations 26 m above ground showed 7-33% reductions in average PM2.5 concentration compared with the curbside and had far fewer spikes. A relationship between the vertical extinction rate of PM2.5 and atmospheric stability was found whereby less unstable atmosphere and greater wind shear led to greater PM2.5 extinction due to damped vertical motion of air. Copyright © 2015 Elsevier Ltd. All rights reserved.

Solar access of residential rooftops in four California cities

Energy Technology Data Exchange (ETDEWEB)

Levinson, Ronnen; Akbari, Hashem; Pomerantz, Melvin

2010-05-14

Shadows cast by trees and buildings can limit the solar access of rooftop solar-energy systems, including photovoltaic panels and thermal collectors. This study characterizes residential rooftop shading in Sacramento, San Jose, Los Angeles and San Diego, CA. Our analysis can be used to better estimate power production and/or thermal collection by rooftop solar-energy equipment. It can also be considered when designing programs to plant shade trees. High-resolution orthophotos and LiDAR (Light Detection And Ranging) measurements of surface height were used to create a digital elevation model of all trees and buildings in a well-treed 2.5-4 km{sup 2} residential neighborhood. On-hour shading of roofing planes (the flat elements of roofs) was computed geometrically from the digital elevation model. Values in future years were determined by repeating these calculations after simulating tree growth. Parcel boundaries were used to determine the extent to which roofing planes were shaded by trees and buildings in neighboring parcels. For the subset of S+SW+W-facing planes on which solar equipment is commonly installed for maximum solar access, absolute light loss in spring, summer and fall peaked about two to four hours after sunrise and about two to four hours before sunset. The fraction of annual insolation lost to shading increased from 0.07-0.08 in the year of surface-height measurement to 0.11-0.14 after 30 years of tree growth. Only about 10% of this loss results from shading by trees and buildings in neighboring parcels.

Indoor air quality investigation at air-conditioned and non-air-conditioned markets in Hong Kong

International Nuclear Information System (INIS)

Guo, H.; Lee, S.C.; Chan, L.Y.

2004-01-01

To characterize indoor air quality at the markets in Hong Kong, three non-air-conditioned and two air-conditioned markets were selected for this study. The indoor air pollutants measured included PM 10 (particulate matters with aerodynamic diameter less than 10 μm), total bacteria count (TBC), carbon monoxide (CO), nitric oxide (NO), nitrogen dioxide (NO 2 ) and sulfur dioxide (SO 2 ). The indoor and outdoor concentrations of these target air pollutants at these markets were measured and compared. The effects of air conditioning, temperature/relative humidity variation and different stalls on the indoor air quality were also investigated. The results indicated that all of the average indoor concentrations of PM 10 , TBC, CO and NO 2 at the markets were below the Hong Kong Indoor Air Quality Objectives (HKIAQO) standards with a few exceptions for PM 10 and TBC. The elevated PM 10 concentrations at Hung Hom, Ngau Tau Kok and Wan Chai markets were probably due to the air filtration of outdoor airborne particulates emitted from vehicular exhaust, whereas high concentrations of airborne bacteria at Sai Ying Pun and Tin Shing markets were linked to the use of air conditioning. Correlation analysis demonstrated that indoor bacteria concentrations were correlated with temperature and relative humidity. The operation of air conditioning did not significantly reduce the levels of air pollutants at the markets. However, the higher indoor/outdoor ratios demonstrated that the operation of air conditioning had influence on the levels of bacteria at the markets. It was found that average PM 10 concentration at poultry stalls was higher than the HKIAQO standard of 180 μg/m 3 , and was over two times that measured at vegetable, fish and meat stalls. Furthermore, the concentration of airborne bacteria at the poultry stalls was as high as 1031 CFU/m 3 , which was above the HKIAQO standard of 1000 CFU/m 3 . The bacteria levels at other three stalls were all below the HKIAQO standard

Building-integrated rooftop greenhouses: An energy and environmental assessment in the mediterranean context

International Nuclear Information System (INIS)

Nadal, Ana; Llorach-Massana, Pere; Cuerva, Eva; López-Capel, Elisa; Montero, Juan Ignacio; Josa, Alejandro

2017-01-01

Highlights: • iRTG incorporates urban agriculture into and improves energy efficiency in buildings. • iRTG concept recycles low-grade, waste thermal energy for growing vegetables. • iRTG is an adaptable concept to promotes food security through urban agriculture. • Indoor building climate affects iRTG more than outdoor climatic conditions. • iRTG achieved annual CO_2 and cost savings of 113.8 kg CO_2 (eq)/m"2/yr and 19.63 €/m"2/yr. - Abstract: A sustainable and secure food supply within a low-carbon and resilient infrastructure is encapsulated in several of The United Nations’ 17 sustainable development goals. The integration of urban agriculture in buildings can offer improved efficiencies; in recognition of this, the first south European example of a fully integrated rooftop greenhouse (iRTG) was designed and incorporated into the ICTA-ICP building by the Autonomous University of Barcelona. This design seeks to interchange heat, CO_2 and rainwater between the building and its rooftop greenhouse. Average air temperatures for 2015 in the iRTG were 16.5 °C (winter) and 25.79 °C (summer), making the iRTG an ideal growing environment. Using detailed thermophysical fabric properties, 2015 site-specific weather data, exact control strategies and dynamic soil temperatures, the iRTG was modelled in EnergyPlus to assess the performance of an equivalent ‘freestanding’ greenhouse. The validated result shows that the thermal interchange between the iRTG and the ICTA-ICP building has considerable moderating effects on the iRTG’s indoor climate; since average hourly temperatures in an equivalent freestanding greenhouse would have been 4.1 °C colder in winter and 4.4 °C warmer in summer under the 2015 climatic conditions. The simulation results demonstrate that the iRTG case study recycled 43.78 MWh of thermal energy (or 341.93 kWh/m"2/yr) from the main building in 2015. Assuming 100% energy conversion efficiency, compared to freestanding greenhouses

Implicit Regularization for Reconstructing 3D Building Rooftop Models Using Airborne LiDAR Data

Directory of Open Access Journals (Sweden)

Jaewook Jung

2017-03-01

Full Text Available With rapid urbanization, highly accurate and semantically rich virtualization of building assets in 3D become more critical for supporting various applications, including urban planning, emergency response and location-based services. Many research efforts have been conducted to automatically reconstruct building models at city-scale from remotely sensed data. However, developing a fully-automated photogrammetric computer vision system enabling the massive generation of highly accurate building models still remains a challenging task. One the most challenging task for 3D building model reconstruction is to regularize the noises introduced in the boundary of building object retrieved from a raw data with lack of knowledge on its true shape. This paper proposes a data-driven modeling approach to reconstruct 3D rooftop models at city-scale from airborne laser scanning (ALS data. The focus of the proposed method is to implicitly derive the shape regularity of 3D building rooftops from given noisy information of building boundary in a progressive manner. This study covers a full chain of 3D building modeling from low level processing to realistic 3D building rooftop modeling. In the element clustering step, building-labeled point clouds are clustered into homogeneous groups by applying height similarity and plane similarity. Based on segmented clusters, linear modeling cues including outer boundaries, intersection lines, and step lines are extracted. Topology elements among the modeling cues are recovered by the Binary Space Partitioning (BSP technique. The regularity of the building rooftop model is achieved by an implicit regularization process in the framework of Minimum Description Length (MDL combined with Hypothesize and Test (HAT. The parameters governing the MDL optimization are automatically estimated based on Min-Max optimization and Entropy-based weighting method. The performance of the proposed method is tested over the International

Implicit Regularization for Reconstructing 3D Building Rooftop Models Using Airborne LiDAR Data.

Science.gov (United States)

Jung, Jaewook; Jwa, Yoonseok; Sohn, Gunho

2017-03-19

With rapid urbanization, highly accurate and semantically rich virtualization of building assets in 3D become more critical for supporting various applications, including urban planning, emergency response and location-based services. Many research efforts have been conducted to automatically reconstruct building models at city-scale from remotely sensed data. However, developing a fully-automated photogrammetric computer vision system enabling the massive generation of highly accurate building models still remains a challenging task. One the most challenging task for 3D building model reconstruction is to regularize the noises introduced in the boundary of building object retrieved from a raw data with lack of knowledge on its true shape. This paper proposes a data-driven modeling approach to reconstruct 3D rooftop models at city-scale from airborne laser scanning (ALS) data. The focus of the proposed method is to implicitly derive the shape regularity of 3D building rooftops from given noisy information of building boundary in a progressive manner. This study covers a full chain of 3D building modeling from low level processing to realistic 3D building rooftop modeling. In the element clustering step, building-labeled point clouds are clustered into homogeneous groups by applying height similarity and plane similarity. Based on segmented clusters, linear modeling cues including outer boundaries, intersection lines, and step lines are extracted. Topology elements among the modeling cues are recovered by the Binary Space Partitioning (BSP) technique. The regularity of the building rooftop model is achieved by an implicit regularization process in the framework of Minimum Description Length (MDL) combined with Hypothesize and Test (HAT). The parameters governing the MDL optimization are automatically estimated based on Min-Max optimization and Entropy-based weighting method. The performance of the proposed method is tested over the International Society for

Hydrogen at the Rooftop: Compact CPV-Hydrogen system to Convert Sunlight to Hydrogen

KAUST Repository

Burhan, Muhammad

2017-12-27

Despite being highest potential energy source, solar intermittency and low power density make it difficult for solar energy to compete with the conventional power plants. Highly efficient concentrated photovoltaic (CPV) system provides best technology to be paired with the electrolytic hydrogen production, as a sustainable energy source with long term energy storage. However, the conventional gigantic design of CPV system limits its market and application to the open desert fields without any rooftop installation scope, unlike conventional PV. This makes CPV less popular among solar energy customers. This paper discusses the development of compact CPV-Hydrogen system for the rooftop application in the urban region. The in-house built compact CPV system works with hybrid solar tracking of 0.1° accuracy, ensured through proposed double lens collimator based solar tracking sensor. With PEM based electrolyser, the compact CPV-hydrogen system showed 28% CPV efficiency and 18% sunlight to hydrogen (STH) efficiency, for rooftop operation in tropical region of Singapore. For plant designers, the solar to hydrogen production rating of 217 kWh/kg has been presented with 15% STH daily average efficiency, recorded from the long term field operation of the system.

Hydrogen at the Rooftop: Compact CPV-Hydrogen system to Convert Sunlight to Hydrogen

KAUST Repository

Burhan, Muhammad; Wakil Shahzad, Muhammad; Ng, Kim Choon

2017-01-01

Despite being highest potential energy source, solar intermittency and low power density make it difficult for solar energy to compete with the conventional power plants. Highly efficient concentrated photovoltaic (CPV) system provides best technology to be paired with the electrolytic hydrogen production, as a sustainable energy source with long term energy storage. However, the conventional gigantic design of CPV system limits its market and application to the open desert fields without any rooftop installation scope, unlike conventional PV. This makes CPV less popular among solar energy customers. This paper discusses the development of compact CPV-Hydrogen system for the rooftop application in the urban region. The in-house built compact CPV system works with hybrid solar tracking of 0.1° accuracy, ensured through proposed double lens collimator based solar tracking sensor. With PEM based electrolyser, the compact CPV-hydrogen system showed 28% CPV efficiency and 18% sunlight to hydrogen (STH) efficiency, for rooftop operation in tropical region of Singapore. For plant designers, the solar to hydrogen production rating of 217 kWh/kg has been presented with 15% STH daily average efficiency, recorded from the long term field operation of the system.

Solar PV-based rooftop power plant

International Nuclear Information System (INIS)

Ashok Kumar, B.; Kumar, Chaitanya; Patel, C.B.; Pattanaik, B.R.; Panda, P.K.; Kaul, S.K.; Mishra, H.

2017-01-01

Technical Services Division (TSD) is responsible for providing reliable power supply to various operating reactors, laboratories and facilities of BARC. The power supply to BARC is derived from TATA Power at 110 KV and 22 KV at an average HT tariff of Rs.8.49 per unit at present. Peak power demand of BARC in summer season goes up to 23 MW. TSD has implemented several energy conservation measures to reduce the energy consumption and as well taken initiatives to install solar PV based rooftop power plants to reduce the cost of energy consumption in BARC

Thermal performance of different planting substrates and irrigation frequencies in extensive tropical rooftop greeneries

Energy Technology Data Exchange (ETDEWEB)

Lin, Yi-Jiung [Department of Environmental Engineering and Science, Foo-Yin University, Kaohsiung (China); No. 16, Lane 29, Chen-Sing 7th Street, Niao-Song, Kaohsiung 833 (China); Lin, Hsien-Te [Department of Architecture, National Cheng Kung University, Tainan (China); No. 1, Ta-Hsueh Road, Tainan 701 (China)

2011-02-15

The need for the better use of scarce planetary resources has never been more evident than it is today. However, this need is poorly reflected in human housing. In recent years, there has been a growing realization of the importance of constructing human shelters that better conserve energy and water through appropriate insulation and architectural designs. Among the important advancements in these areas is the use of rooftop greeneries for both energy and water conservation. This paper performs an investigation into this topic within the specific climatic context of tropical regions. Long-term experimental results are provided from a four-floor building in Kaohsiung in the southern part of Taiwan. The study involves a fully monitored extensive rooftop greenery and examines four different plant substrates, three different irrigation regimes, and different types of drought-enduring plants to find the most efficient combination of all three in providing maximum heat insulation and water usage efficiency. The attenuation of solar radiation through the vegetation layer is evaluated, as well as the thermal insulation performance of the rooftop greenery structure. Among the substrates, burned sludge has the best thermal reduction percentage of heat amplitude under the roof slab surface (up to 84.4%). Irrigation twice a week has the best thermal reduction percentage of heat amplitude (91.6%). Among the plant types, Sansevieria trifasciata cv. Laurentii Compacta and Rhoeo spathaceo cv. Compacta are found to be suitable for extensive rooftop greeneries because they have the best coverage ratio and are most drought enduring. (author)

Rooftop hospital gardens for physical therapy: a post-occupancy evaluation.

Science.gov (United States)

Davis, Brad E

2011-01-01

The goal of this study was to understand successes and weaknesses of a rooftop hospital garden used primarily for physical therapy. Literature on the healing benefits of nature and designed outdoor spaces in healthcare contexts continues to become more focused on specific patient populations. This study contributes to the knowledge of rooftop hospital gardens and gardens for physical rehabilitation. A post-occupancy evaluation was conducted using interviews with a lead therapist and landscape architect, behavior mapping, a staff survey, and a patient questionnaire. The designer and administrative staff perceived high accessibility while patients and staff reported low accessibility. Patients reported high satisfaction with the garden while staff reported little time for garden use. Poor maintenance decisions resulted in decreased functional and aesthetic value. Garden elements take on added layers of meaning and value to users seeking to escape the indoor environment, placing increased importance on evidence-based site design. Multiple perspectives must be considered in facility and garden master planning. Finally, designers and horticultural therapists must be retained in garden management to preserve and enhance garden functionality.

Solar to hydrogen: Compact and cost effective CPV field for rooftop operation and hydrogen production

KAUST Repository

Burhan, Muhammad

2016-11-25

Current commercial CPV systems are designed as large units which are targeted to be installed in open desert fields with high DNI availability. It appeared that the CPV is among some of those technologies which gained very little attention of people, with less customers and market. For conventional PV systems, the installations at the rooftop of commercial and residential buildings have a significant share in the total installed capacity of PV systems. That is why for most of the countries, the PV installations at the rooftop of commercial and residential buildings are aimed to be increased to half of total installed PV. On the other hand, there is no commercial CPV system available to be suitable for rooftop operation, giving motivation for the development of CPV field of compact systems. This paper discusses the development of a CPV field for the rooftop operation, comprising of compact CPV system with cost effective but highly accurate solar tracking sensor and wireless master slave control. In addition, the performance of the developed CPV systems is evaluated for production of hydrogen, which can be used as energy carrier or energy storage and a maximum solar to hydrogen efficiency of 18% is obtained. However, due to dynamic nature of the weather data and throughout the day variations in the performance of CPV and electrolyser, the solar to hydrogen performance is proposed to be reported as daily and long term average efficiency. The CPV-Hydrogen system showed daily average conversion efficiency of 15%, with solar to hydrogen production rate of 218 kW h/kg.

Analyzing the Energy Performance, Wind Loading, and Costs of Photovoltaic Slat Modules on Commercial Rooftops

Energy Technology Data Exchange (ETDEWEB)

Van Geet, Otto D. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Fu, Ran [National Renewable Energy Lab. (NREL), Golden, CO (United States); Horowitz, Kelsey A. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Kurup, Parthiv [National Renewable Energy Lab. (NREL), Golden, CO (United States); MacAlpine, Sara M. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Silverman, Timothy J. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2018-02-13

NREL studied a new type of photovoltaic (PV) module configuration wherein multiple narrow, tilted slats are mounted in a single frame. Each slat of the PV slat module contains a single row of cells and is made using ordinary crystalline silicon PV module materials and processes, including a glass front sheet and weatherproof polymer encapsulation. Compared to a conventional ballasted system, a system using slat modules offer higher energy production and lower weight at lower LCOE. The key benefits of slat modules are reduced wind loading, improved capacity factor and reduced installation cost. First, the individual slats allow air to flow through, which reduce wind loading. Using PV performance modeling software, we compared the performance of an optimized installation of slats modules to a typical installation of conventional modules in a ballasted rack mounting system. Based on the results of the performance modeling two different row tilt and spacing were tested in a wind tunnel. Scaled models of the PV Slat modules were wind tunnel tested to quantify the wind loading of a slat module system on a commercial rooftop, comparing the results to conventional ballasted rack mounted PV modules. Some commercial roofs do not have sufficient reserve dead load capacity to accommodate a ballasted system. A reduced ballast system design could make PV system installation on these roofs feasible for the first time without accepting the disadvantages of penetrating mounts. Finally, technoeconomic analysis was conducted to enable an economic comparison between a conventional commercial rooftop system and a reduced-ballast slat module installation.

Relationship between Air Pollution and Weather Conditions under Complicated Geographical conditions

Science.gov (United States)

Cheng, Q.; Jiang, P.; Li, M.

2017-12-01

Air pollution is one of the most serious issues all over the world, especially in megacities with constrained geographical conditions for air pollution diffusion. However, the dynamic mechanism of air pollution diffusion under complicated geographical conditions is still be confused. Researches to explore relationship between air pollution and weather conditions from the perspective of local atmospheric circulations can contribute more to solve such problem. We selected three megacities (Beijing, Shanghai and Guangzhou) under different geographical condition (mountain-plain transition region, coastal alluvial plain and coastal hilly terrain) to explore the relationship between air pollution and weather conditions. RDA (Redundancy analysis) model was used to analyze how the local atmospheric circulation acts on the air pollutant diffusion. The results show that there was a positive correlation between the concentration of air pollutants and air pressure, while temperature, precipitation and wind speed have negative correlations with the concentration of air pollutants. Furthermore, geographical conditions, such as topographic relief, have significant effects on the direction, path and intensity of local atmospheric circulation. As a consequence, air pollutants diffusion modes in different cities under various geographical conditions are diverse from each other.

[Microbial air purity in hospitals. Operating theatres with air conditioning system].

Science.gov (United States)

Krogulski, Adam; Szczotko, Maciej

2010-01-01

The aim of this study was to show the influence of air conditioning control for microbial contamination of air inside the operating theatres equipped with correctly working air-conditioning system. This work was based on the results of bacteria and fungi concentration in hospital air obtained since 2001. Assays of microbial air purity conducted on atmospheric air in parallel with indoor air demonstrated that air filters applied in air-conditioning systems worked correctly in every case. To show the problem of fluctuation of bacteria concentration more precisely, every sequences of single results from successive measure series were examined independently.

Prototype Systems for Measuring Outdoor Air Intake Rates in Rooftop Air Handlers

Energy Technology Data Exchange (ETDEWEB)

Fisk, William J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Chan, Wanyu R. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Hotchi, Toshifumi [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2015-01-01

The widespread absence of systems for real-time measurement and feedback control, of minimum outdoor air intake rates in HVAC systems contributes to the poor control of ventilation rates in commercial buildings. Ventilation rates affect building energy consumption and influence occupant health. The project designed fabricated and tested four prototypes of systems for measuring rates of outdoor air intake into roof top air handlers. All prototypes met the ±20% accuracy target at low wind speeds, with all prototypes accurate within approximately ±10% after application of calibration equations. One prototype met the accuracy target without a calibration. With two of four prototype measurement systems, there was no evidence that wind speed or direction affected accuracy; however, winds speeds were generally below usually 3.5 m s^-1 (12.6 km h^-1) and further testing is desirable. The airflow resistance of the prototypes was generally less than 35 Pa at maximum RTU air flow rates. A pressure drop of this magnitude will increase fan energy consumption by approximately 4%. The project did not have resources necessary to estimate costs of mass produced systems. The retail cost of components and materials used to construct prototypes ranged from approximately $1,200 to $1,700. The test data indicate that the basic designs developed in this project, particularly the designs of two of the prototypes, have considerable merit. Further design refinement, testing, and cost analysis would be necessary to fully assess commercial potential. The designs and test results will be communicated to the HVAC manufacturing community.

Fungal colonization of air-conditioning systems

Directory of Open Access Journals (Sweden)

Ljaljević-Grbić Milica

2008-01-01

Full Text Available Fungi have been implicated as quantitatively the most important bioaerosol component of indoor air associated with contaminated air-conditioning systems. rarely, indoor fungi may cause human infections, but more commonly allergenic responses ranging from pneumonitis to asthma-like symptoms. From all air conditioner filters analyzed, 16 fungal taxa were isolated and identified. Aspergillus fumigatus causes more lethal infections worldwide than any other mold. Air-conditioning filters that adsorb moisture and volatile organics appear to provide suitable substrates for fungal colonization. It is important to stress that fungal colonization of air-conditioning systems should not be ignored, especially in hospital environments.

Market Transformation Pathways for Grid-Connected Rooftop Solar PV in Minnesota

Energy Technology Data Exchange (ETDEWEB)

Abbey, Ross [Fresh Energy, St. Paul, MN (United States); Ross, Brian [CR Planning, Minneapolis, MN (United States)

2013-06-03

This report presents the market and policy findings of the Minnesota Solar Challenge program. The report draws on information collected from state agencies, local government units, solar industry participants, rooftop photovoltaic (PV) adopters (sometimes called customer-generators), state and national experts, the Commerce distributed generation stakeholder process, and the numerous reports and data sets referenced herein.

Air conditioning systems to clean radioactive air

International Nuclear Information System (INIS)

Ganz, G.

1987-01-01

The author reports a study by the Institutes fuer Klimatechnik and Umweltschutz Giessen that shows that air conditioning systems not only make the atmosphere more comfortable, they also extract dust particles. This cleaning action is also valid for radioactively contaminated air. (G.T.H./Auth.)

Impact of PID on industrial rooftop PV-installations

Science.gov (United States)

Buerhop, Claudia; Fecher, Frank W.; Pickel, Tobias; Patel, Tirth; Zetzmann, Cornelia; Camus, Christian; Hauch, Jens; Brabec, Christoph J.

2017-08-01

Potential induced degradation (PID) causes severe damage and financial losses even in modern PV-installations. In Germany, approximately 19% of PV-installations suffer from PID and resulting power loss. This paper focuses on the impact of PID in real installations and how different evaluated time intervals influence the performance ratio (PR) and the determined degradation rate. The analysis focuses exemplarily on a 314 kWp PV-system in the Atlantic coastal climate. IR-imaging is used for identifying PID without operation interruption. Historic electric performance data are available from a monitoring system for several years on system level, string level as well as punctually measured module string IV- curves. The data sets are combined for understanding the PID behavior of this PV plant. The number of PID affected cells within a string varies strongly between 1 to 22% with the string position on the building complex. With increasing number of PID-affected cells the performance ratio decreases down to 60% for daily and monthly periods. Local differences in PID evolution rates are identified. An average PR-reduction of -3.65% per year is found for the PV-plant. On the string level the degradation rate varied up to 8.8% per year depending on the string position and the time period. The analysis reveals that PID generation and evolution in roof-top installations on industrial buildings with locally varying operation conditions can be fairly complex. The results yield that local operating conditions, e.g. ambient weather conditions as well as surrounding conditions on an industrial building, seem to have a dominating impact on the PID evolution rate.

Economic and environmental assessment of rooftops regarding suitability for photovoltaic systems installation based on remote sensing data

International Nuclear Information System (INIS)

Lukač, Niko; Seme, Sebastijan; Dežan, Katarina; Žalik, Borut; Štumberger, Gorazd

2016-01-01

Within the last few years, the increase of the world's energy consumption has substantially impacted the environment. Solar energy initiative is more than ever involved to tackle this issue, especially when deploying PV (photovoltaic) systems over large-scale residential areas. However, not all surfaces in these areas are economically suitable, while some surfaces have low CO_2 mitigation. With the availability of high-resolution remote sensing data, the estimation of suitable rooftops for PV systems installation can be performed automatically by estimating the PV potential. This paper presents a novel method for estimating NPV (net present value) of the potential PV systems installed on rooftops by using LiDAR (Light Detection And Ranging) data and PV systems' nonlinear efficiency characteristics. More importantly, the environmental impact is estimated for each rooftop through EPBT (energy payback time) and GGER (greenhouse gas emission rate), based on the life-cycle of a specific PV system. This is combined with NPV in order to find rooftops that are both economically and environmentally viable candidates for PV systems deployment. Results demonstrate a case study LiDAR data for predicting each building's economical and environmental impact, as well as providing an overall view of resulting cumulative CO_2 mitigation over large residential area. - Highlights: • The method relies on PV potential estimation over LiDAR remote sensing data. • Novel economic assessment of PV systems using remote sensing data is proposed. • Environmental analysis of PV systems based on EPBT and GGER is performed. • Estimation of CO_2 mitigation over LiDAR data by considering national energy network.

Estimating rooftop solar technical potential across the US using a combination of GIS-based methods, lidar data, and statistical modeling

Science.gov (United States)

Gagnon, Pieter; Margolis, Robert; Melius, Jennifer; Phillips, Caleb; Elmore, Ryan

2018-02-01

We provide a detailed estimate of the technical potential of rooftop solar photovoltaic (PV) electricity generation throughout the contiguous United States. This national estimate is based on an analysis of select US cities that combines light detection and ranging (lidar) data with a validated analytical method for determining rooftop PV suitability employing geographic information systems. We use statistical models to extend this analysis to estimate the quantity and characteristics of roofs in areas not covered by lidar data. Finally, we model PV generation for all rooftops to yield technical potential estimates. At the national level, 8.13 billion m2 of suitable roof area could host 1118 GW of PV capacity, generating 1432 TWh of electricity per year. This would equate to 38.6% of the electricity that was sold in the contiguous United States in 2013. This estimate is substantially higher than a previous estimate made by the National Renewable Energy Laboratory. The difference can be attributed to increases in PV module power density, improved estimation of building suitability, higher estimates of total number of buildings, and improvements in PV performance simulation tools that previously tended to underestimate productivity. Also notable, the nationwide percentage of buildings suitable for at least some PV deployment is high—82% for buildings smaller than 5000 ft2 and over 99% for buildings larger than that. In most states, rooftop PV could enable small, mostly residential buildings to offset the majority of average household electricity consumption. Even in some states with a relatively poor solar resource, such as those in the Northeast, the residential sector has the potential to offset around 100% of its total electricity consumption with rooftop PV.

Variable speed drives boost air handler benefits

Energy Technology Data Exchange (ETDEWEB)

Twenty-four separate roof-top air handlers, controlled by variable speed ac motor drives, provide comfort and ventilation for employees at a 500,000 sq. ft. sportswear distribution center in southern Virginia. They were chosen over optional packaged HVAC units because of their flexibility, efficiency, and short payback advantages. The operation of the units is described.

Simultaneous measurements of new particle formation at 1 s time resolution at a street site and a rooftop site

Science.gov (United States)

Zhu, Yujiao; Yan, Caiqing; Zhang, Renyi; Wang, Zifa; Zheng, Mei; Gao, Huiwang; Gao, Yang; Yao, Xiaohong

2017-08-01

This study is the first to use two identical Fast Mobility Particle Sizers for simultaneous measurement of particle number size distributions (PNSDs) at a street site and a rooftop site within 500 m distance in wintertime and springtime to investigate new particle formation (NPF) in Beijing. The collected datasets at 1 s time resolution allow deduction of the freshly emitted traffic particle signal from the measurements at the street site and thereby enable the evaluation of the effects on NPF in an urban atmosphere through a site-by-site comparison. The number concentrations of 8 to 20 nm newly formed particles and the apparent formation rate (FR) in the springtime were smaller at the street site than at the rooftop site. In contrast, NPF was enhanced in the wintertime at the street site with FR increased by a factor of 3 to 5, characterized by a shorter NPF time and higher new particle yields than at the rooftop site. Our results imply that the street canyon likely exerts distinct effects on NPF under warm or cold ambient temperature conditions because of on-road vehicle emissions, i.e., stronger condensation sinks that may be responsible for the reduced NPF in the springtime but efficient nucleation and partitioning of gaseous species that contribute to the enhanced NPF in the wintertime. The occurrence or absence of apparent growth for new particles with mobility diameters larger than 10 nm was also analyzed. The oxidization of biogenic organics in the presence of strong photochemical reactions is suggested to play an important role in growing new particles with diameters larger than 10 nm, but sulfuric acid is unlikely to be the main species for the apparent growth. However, the number of datasets used in this study is relatively small, and larger datasets are essential to draw a general conclusion.

Global Trends and Current Status of Commercial Urban Rooftop Farming

OpenAIRE

Devi Buehler; Ranka Junge

2016-01-01

The aim of this study was to analyze current practices in commercial urban rooftop farming (URF). In recent years, URF has been experiencing increasing popularity. It is a practice that is well-suited to enhancing food security in cities and reducing the environmental impact that results from long transportation distances that are common in conventional agriculture. To date, most URF initiatives have been motivated by social and educational factors rather than the aim of creating large sustai...

Volcanic air pollution hazards in Hawaii

Science.gov (United States)

Elias, Tamar; Sutton, A. Jeff

2017-04-20

Noxious sulfur dioxide gas and other air pollutants emitted from Kīlauea Volcano on the Island of Hawai‘i react with oxygen, atmospheric moisture, and sunlight to produce volcanic smog (vog) and acid rain. Vog can negatively affect human health and agriculture, and acid rain can contaminate household water supplies by leaching metals from building and plumbing materials in rooftop rainwater-catchment systems. U.S. Geological Survey scientists, along with health professionals and local government officials are working together to better understand volcanic air pollution and to enhance public awareness of this hazard.

Infrasonic waves and air-conditioning

Energy Technology Data Exchange (ETDEWEB)

Hoenmann, W.

1986-08-01

This article is a critical investigation of the recently-suggested possibility that the infrasound generated by an air conditioning system (up to 2o kHz) may adversely affect the well-being of human beings. After an introductory explanation of the infrasonic wave band and the dependency of the sound pressure level on the frequency for decibel values of 20 to 100 (diagram), the relevant results of studies by various experts are quoted. It became apparent that the influence of the inaudible infrasound has been greatly overestimated, whereas audibility was underestimated. Inaudible infrasound was shown to be completely harmless. A number of frequency variation analysis diagrams of various residences (old building, new building) with audibility thresholds marked in. The measurement results discussed in more detail indicate that it is possible not to raise the basic noise level of an air conditioning system in the low-frequency range. Therein lies the actual acoustic chance for air conditioning: In an air-conditioned building, there is no need to ventilate by means of open windows, thereby letting in traffic noise, the nuisance value of which is beyond dispute. (HWJ).

Rooftop photovoltaic (PV) systems for industrial halls: Achieving economic benefit via lowering energy demand

NARCIS (Netherlands)

Lee, B.; Trcka, M.; Hensen, J.L.M.

2012-01-01

Industrial halls are characterized with their relatively high roof-to-floor ratio, which facilitates ready deployment of renewable energy generation, such as photovoltaic (PV) systems, on the rooftop. To promote deployment of renewable energy generation, feed-in tariff (FIT) higher than the

Air Conditioning Compressor Air Leak Detection by Image Processing Techniques for Industrial Applications

Directory of Open Access Journals (Sweden)

Pookongchai Kritsada

2015-01-01

Full Text Available This paper presents method to detect air leakage of an air conditioning compressor using image processing techniques. Quality of air conditioning compressor should not have air leakage. To test an air conditioning compressor leak, air is pumped into a compressor and then submerged into the water tank. If air bubble occurs at surface of the air conditioning compressor, that leakage compressor must be returned for maintenance. In this work a new method to detect leakage and search leakage point with high accuracy, fast, and precise processes was proposed. In a preprocessing procedure to detect the air bubbles, threshold and median filter techniques have been used. Connected component labeling technique is used to detect the air bubbles while blob analysis is searching technique to analyze group of the air bubbles in sequential images. The experiments are tested with proposed algorithm to determine the leakage point of an air conditioning compressor. The location of the leakage point was presented as coordinated point. The results demonstrated that leakage point during process could be accurately detected. The estimation point had error less than 5% compared to the real leakage point.

Air Conditioner Charging. Automotive Mechanics. Air Conditioning. Instructor's Guide [and] Student Guide.

Science.gov (United States)

Spignesi, B.

This instructional package, one in a series of individualized instructional units on automobile air conditioning, consists of a student guide and an instructor guide dealing with air conditioning charging. Covered in the module are checking the air conditioning system for leaks, checking and adding refrigerant oil as needed, evacuating the system,…

Simultaneous measurements of new particle formation at 1 s time resolution at a street site and a rooftop site

Directory of Open Access Journals (Sweden)

Y. Zhu

2017-08-01

Full Text Available This study is the first to use two identical Fast Mobility Particle Sizers for simultaneous measurement of particle number size distributions (PNSDs at a street site and a rooftop site within 500 m distance in wintertime and springtime to investigate new particle formation (NPF in Beijing. The collected datasets at 1 s time resolution allow deduction of the freshly emitted traffic particle signal from the measurements at the street site and thereby enable the evaluation of the effects on NPF in an urban atmosphere through a site-by-site comparison. The number concentrations of 8 to 20 nm newly formed particles and the apparent formation rate (FR in the springtime were smaller at the street site than at the rooftop site. In contrast, NPF was enhanced in the wintertime at the street site with FR increased by a factor of 3 to 5, characterized by a shorter NPF time and higher new particle yields than at the rooftop site. Our results imply that the street canyon likely exerts distinct effects on NPF under warm or cold ambient temperature conditions because of on-road vehicle emissions, i.e., stronger condensation sinks that may be responsible for the reduced NPF in the springtime but efficient nucleation and partitioning of gaseous species that contribute to the enhanced NPF in the wintertime. The occurrence or absence of apparent growth for new particles with mobility diameters larger than 10 nm was also analyzed. The oxidization of biogenic organics in the presence of strong photochemical reactions is suggested to play an important role in growing new particles with diameters larger than 10 nm, but sulfuric acid is unlikely to be the main species for the apparent growth. However, the number of datasets used in this study is relatively small, and larger datasets are essential to draw a general conclusion.

Comparison of desiccant air conditioning systems with different indirect evaporative air coolers

International Nuclear Information System (INIS)

Pandelidis, Demis; Anisimov, Sergey; Worek, William M.; Drąg, Paweł

2016-01-01

Highlights: • A numerical study of desiccant air conditioning systems is presented. • The ε-NTU model is used for the analysis. • Different arrangements of the desiccant systems were compared. • The systems were compared under different operating conditions. - Abstract: This paper presents a numerical analysis of three desiccant air-conditioning systems equipped with different indirect evaporative air coolers: (1) the cross-flow Maisotsenko cycle heat and mass exchanger (HMX), (2) the regenerative counter-flow Maisotsenko cycle heat and mass exchanger and (3) the standard cross-flow evaporative air cooler. To analyze the desiccant wheel and the indirect evaporative air coolers, the modified ε-NTU-model was used. The simulations were performed under assumption that the desiccant wheel is regenerated with air heated to relatively low temperature values (50–60 °C), which can be produced with solar panels in typical moderate climatic conditions. It was established that the main advantage of the presented solutions is that they can provide comfort conditions even with less effective dehumidification. The different systems were compared under variable selected operational factors (i.e. inlet air temperature, humidity and regeneration air temperature). The analysis allowed establishing the advantages and disadvantages of presented solutions and allowed estimating their application potential.

Heating, ventilating, and air-conditioning applications

International Nuclear Information System (INIS)

Anon.

1991-01-01

This book covers: Comfort air conditioning and heating of residences: Space HVAC systems; Industrial and special air conditioning and ventilation for nuclear facilities, and for mines; Energy sources, such as Geothermal energy, solar utilization, and energy resources; Building operation and maintenance; energy management, and Thermal storage

A RADIANT AIR-CONDITIONING SYSTEM USING SOLAR-DRIVEN

Directory of Open Access Journals (Sweden)

S. A. ABDALLA

2006-12-01

Full Text Available Every air-conditioning system needs some fresh air to provide adequate ventilation air required to remove moisture, gases like ammonia and hydrogen sulphide, disease organisms, and heat from occupied spaces. However, natural ventilation is difficult to control because urban areas outside air is often polluted and cannot be supplied to inner spaces before being filtered. Besides the high electrical demand of refrigerant compression units used by most air-conditioning systems, and fans used to transport the cool air through the thermal distribution system draw a significant amount of electrical energy in comparison with electrical energy used by the building thermal conditioning systems. Part of this electricity heats the cooled air; thereby add to the internal thermal cooling peak load. In addition, refrigerant compression has both direct and indirect negative effects on the environment on both local and global scales. In seeking for innovative air-conditioning systems that maintain and improve indoor air quality under potentially more demanding performance criteria without increasing environmental impact, this paper presents radiant air-conditioning system which uses a solar-driven liquid desiccant evaporative cooler. The paper describes the proposed solar-driven liquid desiccant evaporative cooling system and the method used for investigating its performance in providing cold water for a radiant air-conditioning system in Khartoum (Central Sudan. The results of the investigation show that the system can operate in humid as well as dry climates and that employing such a system reduces air-conditioning peak electrical demands as compared to vapour compression systems.

Assessment of radiofrequency/microwave radiation emitted by the antennas of rooftop-mounted mobile phone base stations

International Nuclear Information System (INIS)

Keow, M. A.; Radiman, S.

2006-01-01

Radiofrequency (RF) and microwave (MW) radiation exposures from the antennas of rooftop-mounted mobile telephone base stations have become a serious issue in recent years due to the rapidly evolving technologies in wireless telecommunication systems. In Malaysia, thousands of mobile telephone base stations have been erected all over the country, most of which are mounted on the rooftops. In view of public concerns, measurements of the RF/MW levels emitted by the base stations were carried out in this study. The values were compared with the exposure limits set by several organisations and countries. Measurements were performed at 200 sites around 47 mobile phone base stations. It was found that the RF/MW radiation from these base stations were well below the maximum exposure limits set by various agencies. (authors)

Performance of desiccant air conditioning system with geothermal energy under different climatic conditions

International Nuclear Information System (INIS)

El-Agouz, S.A.; Kabeel, A.E.

2014-01-01

Highlights: • The performance of the hybrid air conditioning system is studied. • The influence of important operating parameters are estimated. • The ventilation, makeup and mix cycles are investigated at different climate. • The highest COP of the hybrid air conditioning system is 1.03. • The hybrid system provides a human thermal comfort at different climates. - Abstract: Energy saving still and continue a major seek in our life, due to the continuous increase in energy consumptions. So, a desiccant air conditioning system with geothermal energy is conducted in the current study. The thermal analysis of air conditioning system with its different components desiccant wheel, solar collector, heat exchanger, ground heat exchanger and water spray evaporative cooler is presented. Three different air conditioning cycles are simulated in the current study for different zones like: hot-dry zone, warm-dry zone, hot-humid zone and the warm-humid zone. The results show that the desiccant air conditioning system successfully provides a better thermal comfort condition in different climates. This hybrid system significantly decreases the supplied air temperature from 12.7 to 21.7 °C at different climate zones. When ω in , air and T Reg increasing, COP decreases and the ventilation cycle provides the better COP. The highest COP value of the desiccant air conditioning system is about 1.03 while the lowest value is about 0.15. The SHR of makeup cycle is higher than that ventilation cycle at warm and hot-humid zone and vice versa at warm and hot-dry zone. The highest SHR value of the desiccant air conditioning system is about 0.99 while the lowest value is about 0.2. The T sup,air , ω sup,air , COP and SHR isolines may easily be used for pre-evaluating of various cooling cycles in different climates. The hybrid system provides a human thermal comfort at different climates

Measurement of Vehicle Air Conditioning Pull-Down Period

Energy Technology Data Exchange (ETDEWEB)

Thomas, John F [ORNL; Huff, Shean P [ORNL; Moore, Larry G [ORNL; West, Brian H [ORNL

2016-08-01

Air conditioner usage was characterized for high heat-load summer conditions during short driving trips using a 2009 Ford Explorer and a 2009 Toyota Corolla. Vehicles were parked in the sun with windows closed to allow the cabin to become hot. Experiments were conducted by entering the instrumented vehicles in this heated condition and driving on-road with the windows up and the air conditioning set to maximum cooling, maximum fan speed and the air flow setting to recirculate cabin air rather than pull in outside humid air. The main purpose was to determine the length of time the air conditioner system would remain at or very near maximum cooling power under these severe-duty conditions. Because of the variable and somewhat uncontrolled nature of the experiments, they serve only to show that for short vehicle trips, air conditioning can remain near or at full cooling capacity for 10-minutes or significantly longer and the cabin may be uncomfortably warm during much of this time.

Study of containment air cooler capacity in steam air environment during accident conditions

International Nuclear Information System (INIS)

Kansal, M.; Mohan, N.; Bhawal, R.N.; Bajaj, S.S.

2002-01-01

Full text: The air coolers are provided for controlling the temperature in the reactor building during normal operation. These air coolers also serve as the main heat sink for the removal of energy from high enthalpy air-steam mixture expected in reactor building under accident conditions. A subroutine COOLER has been developed to estimate the heat removal rate of the air coolers at high temperature and steam conditions. The subroutine COOLER has been attached with the code PACSR (post accident containment system response) used for containment pressure temperature calculation. The subroutine was validated using design parameters at normal operating condition. A study was done to estimate the heat removal rate for some postulated accident conditions. The study reveals that, under accident conditions, the heat removal rate of air coolers increases several times compared with normal operating conditions

Feasibility of a solar-assisted winter air-conditioning system using evaporative air-coolers

Energy Technology Data Exchange (ETDEWEB)

El-Awad, Mohamed M. [Mechanical Engineering Department, the University of Khartoum, P.O. Box 321 Khartoum (Sudan)

2011-07-01

The paper presents a winter air-conditioning system which is suitable for regions with mildly cold but dry winters. The system modifies the evaporative air-cooler that is commonly used for summer air-conditioning in such regions by adding a heating process after the humidification process. The paper describes a theoretical model that is used to estimate the system's water and energy consumption. It is shown that a 150-LPD solar heater is adequate for air-conditioning a 500 ft3/min (14.4 m3/min) air flow rate for four hours of operation. The maximum air-flow rate that can be heated by a single solar water-heater for four hours of operation is about 900-cfm, unless a solar water heater large than a 250-LPD heater is used. For the 500 ft3/min air flow rate the paper shows that the 150, 200, 250 and 300 LPD solar water-heaters can provide air-conditioning for 4, 6, 8 and 10 hours, respectively, while consuming less energy than the equivalent refrigerated-type air-conditioner.

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.)

Optimizing economic benefit of rooftop photovoltaic (PV) systems through lowering energy demand of industrial halls

NARCIS (Netherlands)

Lee, B.; Trcka, M.; Hensen, J.L.M.

2012-01-01

Industrial halls are characterized with their relatively high roof-to-floor ratio, which facilitates ready deployment of photovoltaic (PV) systems on the rooftop. To promote deployment of PV systems, feed-in tariff (FIT) higher than the electricity rate is available in many countries to subsidize

Air quality and passenger comfort in an air-conditioned bus micro-environment.

Science.gov (United States)

Zhu, Xiaoxuan; Lei, Li; Wang, Xingshen; Zhang, Yinghui

2018-04-12

In this study, passenger comfort and the air pollution status of the micro-environmental conditions in an air-conditioned bus were investigated through questionnaires, field measurements, and a numerical simulation. As a subjective analysis, passengers' perceptions of indoor environmental quality and comfort levels were determined from questionnaires. As an objective analysis, a numerical simulation was conducted using a discrete phase model to determine the diffusion and distribution of pollutants, including particulate matter with a diameter air quality and dissatisfactory thermal comfort conditions in Jinan's air-conditioned bus system. To solve these problems, three scenarios (schemes A, B, C) were designed to alter the ventilation parameters. According to the results of an improved simulation of these scenarios, reducing or adding air outputs would shorten the time taken to reach steady-state conditions and weaken the airflow or lower the temperature in the cabin. The airflow pathway was closely related to the layout of the air conditioning. Scheme B lowered the temperature by 0.4 K and reduced the airflow by 0.01 m/s, while scheme C reduced the volume concentration of PM 10 to 150 μg/m 3 . Changing the air supply angle could further improve the airflow and reduce the concentration of PM 10 . With regard to the perception of airflow and thermal comfort, the scheme with an airflow provided by a 60° nozzle was considered better, and the concentration of PM 10 was reduced to 130 μg/m 3 .

Design and analysis of a small-scale vertical-axis wind turbine for rooftop power generation

International Nuclear Information System (INIS)

Abraham, J.P.; Mowry, G.S.; Erickson, R.A.

2009-01-01

This paper described a fluid flow model of a 2-blade vertical axis wind turbine designed for use in crowded urban and rooftop environments. The turbine featured a contoured blade developed to maximize rotational velocity and minimize drag forces. The model was used to determine the turbine's rotational velocities in a range of wind speeds. The analysis included a numerical simulation of air flow across the cup faces at all circumferential locations in order to determine pressure and drag forces. A rigid body dynamic analysis was then conducted to determine the rotational velocity of the turbine. Mass, momentum and turbulence closure equations were presented. Results of the study demonstrated that a turbine rotation rate of 137 rpm was achieved at wind velocities of 30 miles per hour. Wind speeds of 20 and 10 miles per hour resulted in rotational velocities of 91 and 43 rpm. It was concluded that the model can be used to predict the angular velocity of the vertical turbine system. 13 refs., 11 figs

Utilization of Solar Energy for Air Conditioning System

Directory of Open Access Journals (Sweden)

Sutikno Juwari Purwo

2018-01-01

Full Text Available The purposes of this research are to do a system simulation of air conditioning utilizing solar energy with single effect absorption refrigeration method, analyze the coefficient of performance (COP for each absorbent-refrigerant variable and compare the effectivity of every absorbent-refrigerant variable used. COP is a constant that denotes the effeciency of a refrigeration system, that is ratio of work or useful output to the amount of work or energy input. The higher the number of COP, the more efficient the system is. Absorbent-refrigerant (working fluids variables used in this research depend on its chemical and thermodynamics properties. Steps in this research are including data collection and tabulation from literature and do a simulation of air conditioning system both commercial air conditioning system (using electrical energy and solar energy air conditioning system with Aspen Plus software. Next, run the simulation for each working fluid variables used and calculate the COP for each variable. Subsequently, analyze and compare the effectivity of all variables used from COP value and economical point of view with commercial air conditioning system. From the result of the simulation, can be concluded that solar air conditioning can achieve 98,85 % of energy savings than commercial air conditioning. Furthermore, from the calculation of COP, the highest COP value is achieved by solar conditioning system with LiNO3-NH3 as working fluid where 55% of the composition is the refrigerant and 45% of absorbent.

Air conditioning system and component therefore distributing air flow from opposite directions

Science.gov (United States)

Obler, H. D.; Bauer, H. B. (Inventor)

1974-01-01

The air conditioning system comprises a plurality of separate air conditioning units coupled to a common supply duct such that air may be introduced into the supply duct in two opposite flow directions. A plurality of outlets such as registers or auxiliary or branch ducts communicate with the supply duct and valve means are disposed in the supply duct at at least some of the outlets for automatically channelling a controllable amount of air from the supply duct to the associated outlet regardless of the direction of air flow within the supply duct. The valve means comprises an automatic air volume control apparatus for distribution within the air supply duct into which air may be introduced from two opposite directions. The apparatus incorporates a freely swinging movable vane in the supply duct to automatically channel into the associated outlet only the deflected air flow which has the higher relative pressure.

Solar air-conditioning. Proceedings

Energy Technology Data Exchange (ETDEWEB)

NONE

2009-07-01

Within the 3rd International Conference on solar air-conditioning in Palermo (Italy) at 30th September to 2nd October, 2009 the following lectures were held: (1) Removal of non-technological barriers to solar cooling technology across Southern European islands (Stefano Rugginenti); (2) The added economic and environmental value of solar thermal systems in microgrids with combined heat and power (Chris Marney); (3) Australian solar cooling interest group (Paul Kohlenbach); (4) Designing of a technology roadmap for solar assisted air conditioning in Austria (Hilbert Focke); (5) Solar cooling in the new context of renewable policies at European level (Raffaele Piria); (6) Prototype of a solar driven steam jet ejector chiller (Clemens Pollerberg); (7) New integrated solar air conditioning system (Joan Carlos Bruno); (8) Primary energy optimised operation of solar driven desiccant evaporative cooling systems through innovative control strategies; (9) Green chiller association (Uli Jakob); (10) Climate Well {sup registered} (Olof Hallstrom); (11) Low capacity absorption chillers for solar cooling applications (Gregor Weidner); (12) Solar cooling in residential, small scale commercial and industrial applications with adsorption technology (Walter Mittelbach); (13) French solar heating and cooling development programme based on energy performance (Daniel Mugnier); (14) Mirrox fresnel process heat collectors for industrial applications and solar cooling (Christian Zahler); (15) Modelling and analyzing solar cooling systems in polysun (Seyen Hossein Rezaei); (16) Solar cooling application in Valle Susa Italy (Sufia Jung); (17) Virtual case study on small solar cooling systems within the SolarCombi+Project (Bjoern Nienborg); (18) Design of solar cooling plants under uncertainty (Fernando Dominguez-Munoz); (19) Fast pre-design of systems using solar thermally driven chillers (Hans-Martin Henning); (20) Design of a high fraction solar heating and cooling plant in southern

The minimum work required for air conditioning process

International Nuclear Information System (INIS)

Alhazmy, Majed M.

2006-01-01

This paper presents a theoretical analysis based on the second law of thermodynamics to estimate the minimum work required for the air conditioning process. The air conditioning process for hot and humid climates involves reducing air temperature and humidity. In the present analysis the inlet state is the state of the environment which has also been chosen as the dead state. The final state is the human thermal comfort fixed at 20 o C dry bulb temperature and 60% relative humidity. The general air conditioning process is represented by an equivalent path consisting of an isothermal dehumidification followed by a sensible cooling. An exergy analysis is performed on each process separately. Dehumidification is analyzed as a separation process of an ideal mixture of air and water vapor. The variations of the minimum work required for the air conditioning process with the ambient conditions is estimated and the ratio of the work needed for dehumidification to the total work needed to perform the entire process is presented. The effect of small variations in the final conditions on the minimum required work is evaluated. Tolerating a warmer or more humid final condition can be an easy solution to reduce the energy consumptions during critical load periods

The microbiological quality of air improves when using air conditioning systems in cars.

Science.gov (United States)

Vonberg, Ralf-Peter; Gastmeier, Petra; Kenneweg, Björn; Holdack-Janssen, Hinrich; Sohr, Dorit; Chaberny, Iris F

2010-06-01

Because of better comfort, air conditioning systems are a common feature in automobiles these days. However, its impact on the number of particles and microorganisms inside the vehicle--and by this its impact on the risk of an allergic reaction--is yet unknown. Over a time period of 30 months, the quality of air was investigated in three different types of cars (VW Passat, VW Polo FSI, Seat Alhambra) that were all equipped with a automatic air conditioning system. Operation modes using fresh air from outside the car as well as circulating air from inside the car were examined. The total number of microorganisms and the number of mold spores were measured by impaction in a high flow air sampler. Particles of 0.5 to 5.0 microm diameter were counted by a laser particle counter device. Overall 32 occasions of sampling were performed. The concentration of microorganisms outside the cars was always higher than it was inside the cars. Few minutes after starting the air conditioning system the total number of microorganisms was reduced by 81.7%, the number of mold spores was reduced by 83.3%, and the number of particles was reduced by 87.8%. There were no significant differences neither between the types of cars nor between the types of operation mode of the air conditioning system (fresh air vs. circulating air). All parameters that were looked for in this study improved during utilization of the car's air conditioning system. We believe that the risk of an allergic reaction will be reduced during use also. Nevertheless, we recommend regular maintenance of the system and replacement of older filters after defined changing intervals.

Optimal Residential Load Scheduling Under Utility and Rooftop Photovoltaic Units

Directory of Open Access Journals (Sweden)

Ghulam Hafeez

2018-03-01

Full Text Available With the rapid advancement in technology, electrical energy consumption is increasing rapidly. Especially, in the residential sector, more than 80% of electrical energy is being consumed because of consumer negligence. This brings the challenging task of maintaining the balance between the demand and supply of electric power. In this paper, we focus on the problem of load balancing via load scheduling under utility and rooftop photovoltaic (PV units to reduce electricity cost and peak to average ratio (PAR in demand-side management. For this purpose, we adopted genetic algorithm (GA, binary particle swarm optimization (BPSO, wind-driven optimization (WDO, and our proposed genetic WDO (GWDO algorithm, which is a hybrid of GA and WDO, to schedule the household load. For energy cost estimation, combined real-time pricing (RTP and inclined block rate (IBR were used. The proposed algorithm shifts load from peak consumption hours to off-peak hours based on combined pricing scheme and generation from rooftop PV units. Simulation results validate our proposed GWDO algorithm in terms of electricity cost and PAR reduction while considering all three scenarios which we have considered in this work: (1 load scheduling without renewable energy sources (RESs and energy storage system (ESS, (2 load scheduling with RESs, and (3 load scheduling with RESs and ESS. Furthermore, our proposed scheme reduced electricity cost and PAR by 22.5% and 29.1% in scenario 1, 47.7% and 30% in scenario 2, and 49.2% and 35.4% in scenario 3, respectively, as compared to unscheduled electricity consumption.

Flow in air conditioned rooms

DEFF Research Database (Denmark)

Nielsen, Peter V.

1974-01-01

Flow in air conditioned r ooms is examined by means of model experiments . The different gearnetries giving unsteady, steady three- dimensional and steady twodimensional flow are determined . Velacity profiles and temperature profiles are measured in some of the geometries. A numerical solution...... of the flow equations is demonstrated and the flow in air conditioned rooms in case of steady two dimensional flow is predi cted. Compari son with measured results is shown i n the case of small Archimedes numbers, and predictions are shown at high Archimedes numbers. A numerical prediction of f low and heat...

Computer Model to Estimate Reliability Engineering for Air Conditioning Systems

International Nuclear Information System (INIS)

Afrah Al-Bossly, A.; El-Berry, A.; El-Berry, A.

2012-01-01

Reliability engineering is used to predict the performance and optimize design and maintenance of air conditioning systems. Air conditioning systems are expose to a number of failures. The failures of an air conditioner such as turn on, loss of air conditioner cooling capacity, reduced air conditioning output temperatures, loss of cool air supply and loss of air flow entirely can be due to a variety of problems with one or more components of an air conditioner or air conditioning system. Forecasting for system failure rates are very important for maintenance. This paper focused on the reliability of the air conditioning systems. Statistical distributions that were commonly applied in reliability settings: the standard (2 parameter) Weibull and Gamma distributions. After distributions parameters had been estimated, reliability estimations and predictions were used for evaluations. To evaluate good operating condition in a building, the reliability of the air conditioning system that supplies conditioned air to the several The company's departments. This air conditioning system is divided into two, namely the main chilled water system and the ten air handling systems that serves the ten departments. In a chilled-water system the air conditioner cools water down to 40-45 degree F (4-7 degree C). The chilled water is distributed throughout the building in a piping system and connected to air condition cooling units wherever needed. Data analysis has been done with support a computer aided reliability software, this is due to the Weibull and Gamma distributions indicated that the reliability for the systems equal to 86.012% and 77.7% respectively. A comparison between the two important families of distribution functions, namely, the Weibull and Gamma families was studied. It was found that Weibull method performed for decision making.

Demonstration & Testing of ClimaStat for Improved DX Air-Conditioning Efficiency

Science.gov (United States)

2013-04-01

Performance DDC – Direct Digital Control DoD – Department of Defense DOE – Department of Energy DX – Direct Expansion EER – Energy Efficiency...field tests on four Trane (American Standard) systems at a university site were concluded in 2009. A production prototype was constructed based on...dehumidification, giving a 18% reduction in energy consumption. Field test data from four Trane Voyager rooftop package units at a university site

Hospital-acquired infections associated with poor air quality in air-conditioned environments

Directory of Open Access Journals (Sweden)

Daniela Pinheiro da Silva

2013-10-01

Full Text Available Backgound and Objectives: Individuals living in cities increasingly spend more time indoors in air-conditioned environments. Air conditioner contamination can be caused by the presence of aerosols from the external or internal environment, which may be associated with disease manifestations in patients present in this type of environment. Therefore, the aim of this review was to assess the air quality in air-conditioned hospital environments as a risk factor for hospital-acquired infections – HAI – as the air can be a potential source of infection, as well as assess the exposure of professionals and patients to different pollutants. Material and Methods: A literature review was performed in the LILACS, MEDLINE, SCIELO, SCIENCE DIRECT databases, CAPES thesis database and Ministry of Health – Brazil, including studies published between 1982 and 2008. The literature search was grouped according to the thematic focus, as follows: ventilation, maintenance and cleaning of systems that comprehend the environmental quality standard. Discussion and Conclusion: Outbreaks of hospital-acquired infections associated with Aspergillus, Acinetobacter, Legionella, and other genera such as Clostridium and Nocardia, which were found in air conditioners, were observed, thus indicating the need for air-conditioning quality control in these environments.

The relevance of rooftops: Analyzing the microscale surface energy balance in the Chicago region

Science.gov (United States)

Khosla, Radhika

Spatial structure in climate variables often exist over very short length scales within an urban area, and this structure is a result of various site-specific features. In order to analyze the seasonal and diurnal energy flows that take place at a microclimatic surface, this work develops a semi-empirical energy balance model. For this, radiation fluxes and meteorological measurements are determined by direct observation; sensible heat and latent heat fluxes by parameterizations; and the heat storage flux by a 1-D mechanistic model that allows analysis of the temperature profile and heat storage within an underlying slab. Two sites receive detailed study: an anthropogenic site, being a University of Chicago building rooftop, and a natural site, outside Chicago in the open country. Two identical sets of instruments record measurements contemporaneously from these locations during June-November 2007, the entire period for which analyses are carried out. The study yields seasonal trends in surface temperature, surface-to-air temperature contrast and net radiation. At both sites, a temporal hysteresis between net radiation and heat storage flux indicates that surplus energy absorbed during daylight is released to the atmosphere later in the evening. The surface energy balance model responds well to site specific features for both locations. An analysis of the surface energy balance shows that the flux of sensible heat is the largest non-radiative contributor to the roof's surface cooling, while the flux of latent heat (also referred to as evaporative cooling) is the largest heat sink for the soil layer. In the latter part of the study, the surface energy balance model is upgraded by adding the capability to compute changes in surface temperature and non-radiative fluxes for any specified set of thermal and reflective roof properties. The results of this analysis allow an examination of the relationship between the roof temperature, the heat flux entering the building

Evaluation of the source area of rooftop scalar measurements in London, UK using wind tunnel and modelling approaches.

Science.gov (United States)

Brocklehurst, Aidan; Boon, Alex; Barlow, Janet; Hayden, Paul; Robins, Alan

2014-05-01

The source area of an instrument is an estimate of the area of ground over which the measurement is generated. Quantification of the source area of a measurement site provides crucial context for analysis and interpretation of the data. A range of computational models exists to calculate the source area of an instrument, but these are usually based on assumptions which do not hold for instruments positioned very close to the surface, particularly those surrounded by heterogeneous terrain i.e. urban areas. Although positioning instrumentation at higher elevation (i.e. on masts) is ideal in urban areas, this can be costly in terms of installation and maintenance costs and logistically difficult to position instruments in the ideal geographical location. Therefore, in many studies, experimentalists turn to rooftops to position instrumentation. Experimental validations of source area models for these situations are very limited. In this study, a controlled tracer gas experiment was conducted in a wind tunnel based on a 1:200 scale model of a measurement site used in previous experimental work in central London. The detector was set at the location of the rooftop site as the tracer was released at a range of locations within the surrounding streets and rooftops. Concentration measurements are presented for a range of wind angles, with the spread of concentration measurements indicative of the source area distribution. Clear evidence of wind channeling by streets is seen with the shape of the source area strongly influenced by buildings upwind of the measurement point. The results of the wind tunnel study are compared to scalar concentration source areas generated by modelling approaches based on meteorological data from the central London experimental site and used in the interpretation of continuous carbon dioxide (CO2) concentration data. Initial conclusions will be drawn as to how to apply scalar concentration source area models to rooftop measurement sites and

Small Business Voucher CRADA Report: Natural Gas Powered HVAC System for Commercial and Residential Buildings

Energy Technology Data Exchange (ETDEWEB)

Betts, Daniel [Be Power Tech, Deerfield Beach, FL (United States); Ally, Moonis Raza [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mudiraj, Shyam [Be Power Tech, Deerfield Beach, FL (United States); Tilghman, Matthew [Be Power Tech, Deerfield Beach, FL (United States); Graham, Matthew [Be Power Tech, Deerfield Beach, FL (United States)

2017-04-30

Be Power Tech is commercializing BeCool, the first integrated electricity-producing heating, ventilation, and air conditioning (HVAC) system using a non-vapor compression cycle (VCC), packaged rooftop HVAC unit that also produces base-load electricity, heating, ventilation, and air conditioning. BeCool is a distributed energy resource with energy storage that eliminates the tremendous peak electricity demand associated with commonly used electricity-powered vapor compression air conditioning systems.

Optimization of recirculating laminar air flow in operating room air conditioning systems

Directory of Open Access Journals (Sweden)

Enver Yalcin

2016-04-01

Full Text Available The laminar flow air-conditioning system with 100% fresh air is used in almost all operating rooms without discrimination in Turkey. The laminar flow device which is working with 100% fresh air should be absolutely used in Type 1A operating rooms. However, there is not mandatory to use of 100% fresh air for Type 1B defined as places performed simpler operation. Compared with recirculating laminar flow, energy needs of the laminar flow with 100 % fresh air has been emerged about 40% more than re-circulated air flow. Therefore, when a recirculating laminar flow device is operated instead of laminar flow system with 100% fresh air in the Type 1B operating room, annual energy consumption will be reduced. In this study, in an operating room with recirculating laminar flow, optimal conditions have been investigated in order to obtain laminar flow form by analyzing velocity distributions at various supply velocities by using computational fluid dynamics method (CFD.

Analysis of urban land use in the megacity of Dhaka, Bangladesh: Roof-top detection in the context of assessing solar photovoltaic potential

Science.gov (United States)

Jaegermeyr, J.; Kabir, H.; Endlicher, W.

2009-12-01

The megacity of Dhaka, Bangladesh is considered to be one of the world’s fastest growing urban centers. With nearly 14 million people Dhaka currently faces tremendous power crisis. The available power supply of Dhaka Megacity is currently 1000-1200 MW against the maximum demand of nearly 2000 MW. The objective of this study is to classify land cover of Dhaka to locate roof-top areas which are adequate for solar photovoltaic applications. Usually this task is performed with additional building-heights data. With lack of that, we present an object-based classification approach which is based on high resolution Quickbird data only. Extensive formal buildings in Dhaka mostly have flat roof-tops made from concrete which are well suited for PV applications. The classification is focused to detect these ‘Bright Roof-Tops’ to assess a lower limit for potential PV areas. With that conservative approach bright roof-top areas of 10.554 km2 out of the city’s 134.282 km2 could be found. The overall classification accuracy is 0.918, the producer’s accuracy of ‘Bright Roof-Tops’ is 0.833. Preliminary result of the PhD work of Humayun Kabir indicates that the application of only 75 Wp stand-alone solar modules on these available bright roof-tops can generate nearly 1,000 MW of electricity. The application of solar modules with high capacity (i.e., >200 Wp) preferably through grid-connected PV systems can substantially meet-up the city’s power demand, although several techno-economic and socio-political factors are certainly involved.

Reduced energy reqirement for air conditioning by using air diffusion with air flow from floor to ceiling

Energy Technology Data Exchange (ETDEWEB)

Bach, H; Dittes, W; Mangelsdorf, R; Detzer, R; Jungbaeck, E; Fitzner, K; Radtke, W; Soethout, F

1982-02-01

The condition of the air in the occupied zone in airconditioned rooms is influenced by the mixing of supply air with room air. When supplying air from the ceiling there is a mixing all over the room, when supplying from the floor or from desks there is a mixing region only in the lower area. Above this their is warm air from which the return air is drawn. For air supply from below the cooling load can be decreased. In combination with the possible enthalpy difference between room air and supply air this decrease of the cooling load influences the necessary air rate. The interdependence of various air conditioning systems and various air temperatures is shown with a computer program. The load factor for various air distribution system at various cooling loads have been measured in a room of (8 x 5)m/sup 2/ x 3m. Experiments in a smaller model room (scale 1:3) showed how the heat was transported from the mixing region to the stratification region. The theoretically gained influence of the supply air jets of the height of the mixing region and on the load rate could be verified by the experiments. For the design of the fresh air rate, experience has been gained by measurements with tracegas (N/sub 2/O) in a third room. In comparing calculations the annual energy consumption has been computed for a building assuming various air conditioning systems and typical operation data. From experience with the existing systems the conclusions have been drawn how air distribution from floor to ceiling can be installed and operated.

Solar air conditioning. Dresden colloquium; Solare Klimatisierung. Dresdner Kolloquium

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-07-01

Subjects: R + D activities in solar air conditioning; dessicative and evaporative cooling (DEC) - systems and components; Chances of solar air conditioning in Europe; Practical experience with solar-assisted air conditioning; Performance of a solar system at Lissabon; DEC system in the Alsenblock building, Berlin; Does solar air conditioning require specially designed buildings; Performance of solar heated adsorption refrigerators; Low-capacity absacity absorption systems for solar air conditioning. [German] Die Kolloquiumsschrift beinhaltet Unterlagen ueber die abgehandelten Themen. Sie lauten: F and E-Aktivitaeten im Bereich Solare Klimatisierung; SGK(DEC-Technik) - ausgefuehrte Anlagen und deren Komponenten; Chancen der solaren Klimatisierung in Europa; Erfahrungen mit der solarunterstuetzten Klimatisierung; Energieverbrauch und Regelung von SGK-Anlagen; Betriebserfahrungen einer Solaranlage in Lissabon; Realisierung der SGK im Alsenblock Berlin; Erfordert die solare Klimatisierung besondere Gebaeude?; Betriebserfahrungen mit solar beheizten Adsorptionskaeltemaschinen; Absorptionsanlagen kleiner Leistung fuer solare Klimatisierung. (orig.)

A multi-objective optimization model for energy-efficiency building envelope retrofitting plan with rooftop PV system installation and maintenance

International Nuclear Information System (INIS)

Fan, Yuling; Xia, Xiaohua

2017-01-01

Highlights: • A multi-objective optimization model for building envelope retrofit is presented. • Facility performance degradation and maintenance is built into the model. • A rooftop PV system is introduced to produce electricity. • Economic factors including net present value and payback period are considered. - Abstract: Retrofitting existing buildings with energy-efficient facilities is an effective method to improve their energy efficiency, especially for old buildings. A multi-objective optimization model for building envelope retrofitting is presented. Envelope components including windows, external walls and roofs are considered to be retrofitted. Installation of a rooftop solar panel system is also taken into consideration in this study. Rooftop solar panels are modeled with their degradation and a maintenance scheme is studied for sustainability of energy and its long-term effect on the retrofitting plan. The purpose is to make the best use of financial investment to maximize energy savings and economic benefits. In particular, net present value, the payback period and energy savings are taken as the main performance indicators of the retrofitting plan. The multi-objective optimization problem is formulated as a non-linear integer programming problem and solved by a weighted sum method. Results of applying the designed retrofitting plan to a 50-year-old building consisting of 66 apartments demonstrated the effectiveness of the proposed model.

Ventilation and air-conditioning system for PWR nuclear power plant

International Nuclear Information System (INIS)

Ohmoto, Kenji

1987-01-01

This report outlines the ventilation and air conditioning facilities for PWR nuclear power plant as well as design re-evaluation and optimization of ventilation and air-conditioning. The primary PWR installations are generally housed in the nuclear reactor building, auxiliary buildings and control building, which are equipped with their own ventilation and air-conditioning systems to serve for their specific purposes. A ventilation/air-conditioning system should be able to work effectively not only for maintaining the ordinary reactor operation but also for controlling the environmental temperature in the event of an accident. Designing of a ventilation/air-conditioning system relied on empirical data in the past, but currently it is performed based on information obtained from various analyses to optimize the system configuration and ventilation capacity. Design re-evaluation of ventilation/air-conditioning systems are conducted widely in various areas, aiming at the integration of safety systems, optimum combination of air-cooling and water-cooling systems, and optimization of the ventilation rate for controlling the concentrations of radioactive substances in the atmosphere in the facilities. It is pointed out that performance evaluation of ventilation/air-conditioning systems, which has been conducted rather macroscopically, should be carried out more in detal in the future to determine optimum air streams and temperature distribution. (Nogami, K.)

Air conditioning system with supplemental ice storing and cooling capacity

Science.gov (United States)

Weng, Kuo-Lianq; Weng, Kuo-Liang

1998-01-01

The present air conditioning system with ice storing and cooling capacity can generate and store ice in its pipe assembly or in an ice storage tank particularly equipped for the system, depending on the type of the air conditioning system. The system is characterized in particular in that ice can be produced and stored in the air conditioning system whereby the time of supplying cooled air can be effectively extended with the merit that the operation cycle of the on and off of the compressor can be prolonged, extending the operation lifespan of the compressor in one aspect. In another aspect, ice production and storage in great amount can be performed in an off-peak period of the electrical power consumption and the stored ice can be utilized in the peak period of the power consumption so as to provide supplemental cooling capacity for the compressor of the air conditioning system whereby the shift of peak and off-peak power consumption can be effected with ease. The present air conditioning system can lower the installation expense for an ice-storing air conditioning system and can also be applied to an old conventional air conditioning system.

Spreading the rooftop revolution: What policies enable solar-as-a-service?

International Nuclear Information System (INIS)

Overholm, Harald

2015-01-01

Firms using third-party-ownership (TPO) business models transform solar rooftop installations into a simple service. TPO firms sign long-term agreements with building owners or users to install, finance and manage locally sited solar panels. Customers simply buy solar electricity. The business model can increase total PV market demand by removing central barriers to PV adoption including technology risk, financing needs, and learning costs. TPO is now the dominant US model for residential solar and attempts to use the business model are underway in Europe and Asia. This study discusses how policy makers can enable emergence of solar TPO business models in new markets, a theme novel to extant literature. The paper is based on a comprehensive study of the US solar TPO ecosystem including 50 interviews with key market actors. A downside to the TPO model is potential lock-out of innovative solar technology. Crucial policy actions to enable TPO emergence in new markets are to ensure the legality of the TPO model and to facilitate solar self-consumption (the ability of customers to offset grid electricity costs by using locally generated solar electricity). -- Highlights: •Solar third-party ownership (TPO) firms can boost solar rooftop growth. •5 in-depth cases of US TPO firms and their ecosystem of partners are analyzed. •Policy options to enable solar TPO emergence in new markets are suggested. •Avoiding prohibitive rules and facilitating solar self-consumption are key measures. •Lock-out of new and innovative solar technology is a downside to the TPO model

2013 German refrigeration and air conditioning meeting. Proceedings

International Nuclear Information System (INIS)

2013-01-01

These proceedings cover the following main topics: cryoengineering - superconduction / energy storage; cryoapplications in biology and medicine; metrology; adsorption processes; condensation/evaporation; working fluids / simulation; ice production; plants and compressors; expansion and ejectors or recooling; use of cooling (passenger car air conditioning, supermarket); refrigerants; plant efficiency; emissions and legislation; air conditioning and use of heat pumps; air quality and control; building technology and block-type thermal power stations. [de

Modelling of air-conditioned and heated spaces

Energy Technology Data Exchange (ETDEWEB)

Moehl, U

1987-01-01

A space represents a complex system involving numerous components, manipulated variables and disturbances which need to be described if dynamic behaviour of space air is to be determined. A justifiable amount of simulation input is determined by the application of adjusted modelling of the individual components. The determination of natural air exchange in heated spaces and of space-air flow in air-conditioned space are a primary source of uncertainties. (orig.).

2014 German refrigeration and air conditioning meeting. Proceedings

International Nuclear Information System (INIS)

2014-01-01

The proceedings of the 2014 German refrigeration and air conditioning meeting contain contributions on the following topics: cryotechnology, fundamentals and materials for the refrigeration and heat pump technology, devices and components for the refrigeration and heat pump technology, applications of refrigeration technologies, air conditioning technology and heat pump applications, cryotechnology in biology and medicine, heat transfer and ventilation, guidelines and legal topics, refrigerant fluid - oil mixtures, control and surveillance, simulation and control, ambient air.

DISAIN SIMULATOR AUTOMOTIVE AIR CONDITIONING UNTUK MENINGKATKAN KOMPETENSI MAHASISWA

Directory of Open Access Journals (Sweden)

Kamin Sumardi

2015-08-01

Full Text Available Perkembangan teknologi automotive air conditioning dan aplikasinya sangat cepat, salah satunya dengan menerapkan green technology. Penerapan green technology pada teknologi air conditioning, karena masih menggunakan refrigeran yang mengandung unsur kimia yang merusak lapisan ozon dan pemanasan global. Alih teknologi bidang air conditioning yang ramah lingkungan, belum dibarengi dengan ketersediaan tenaga kerja pada tingkat SMK dan perguruan tinggi yang memadai, baik kuantitas maupun kompetensinya. Pada level SMK dan perguruan tinggi, kompetensi akademik dan vokasional bidang automotive air conditioning harus terus ditingkatkan dan diperbaharui sesuai dengan perkembangan teknologinya. Penelitian ini bertujuan untuk menghasilkan simulator automotive air conditioner dan model pembelajaran tata udara pada otomotif berwawasan teknologi ramah lingkungan. Penelitian menggunakan metode research and development dengan langkah-langkah: studi pendahuluan, perencanaan, pengembangan melalui uji coba simulator, validasi, dan produk akhir. Simulator dibuat sesuai dengan kondisi di dunia kerja agar tidak terjadi miskonsepsi dan mala-praktek automotive air conditioning. Simulator ini dibuat secara kompak dan mobile atau dapat dipindah dan dibawa. Model pembelajaran disesuaikan dengan kebutuhan kompetensi yang dipersyaratkan. Hasil penelitian menunjukkan bahwa dengan bantuan simulator automotive air conditioner dan model pembelajaran yang tepat mahasiswa mampu menyerap konsep dan praktek lebih cepat 85%. Hasil belajar pada ranah afektif, kognitif, psikomotor dan kompetensi meningkat secara signifikan.

Performance assessment and transient optimization of air precooling in multi-stage solid desiccant air conditioning systems

International Nuclear Information System (INIS)

Gadalla, Mohamed; Saghafifar, Mohammad

2016-01-01

Highlights: • Studying three two-stage solid desiccant cooling systems using Maisotsenko cooler. • Proposing precooling to improve two-stage desiccant systems’ COP for humid climates. • Performing transient analysis for a two-stage solid desiccant cooler in UAE. • Optimizing daily performance of a two-stage solid desiccant cooler for UAE. - Abstract: Renewable energy is one of the most promising solutions to both energy and global warming crisis. Energy consumption can be minimized considerably by utilizing solar energy in air conditioning systems operation. One of the popular solar air conditioning technologies is desiccant air conditioning. Nonetheless, conventional desiccant air conditioning systems have a relatively low coefficient of performance (COP). In consequence, two-stage desiccant air-conditioning systems are proposed to improve desiccant air conditioning systems’ COP. Moreover, a recently commercialized cooling method named Maisotsenko cooling cycle which is capable of cooling air near to its dew point temperature is considered to be integrated within the proposed multi-stage desiccant cooling systems. In this paper, three new two-stage desiccant air conditioning systems incorporating Maisotsenko cooling cycle are proposed and investigated in details for hot and humid climates such as UAE. Furthermore, air precooling is considered to improve two stage desiccant air conditioning systems’ COP. Moreover, full transient analysis and optimization are carried out in UAE within June–October. The proposed system can minimize the required solar heating during noon time as the ambient air dry bulb temperature rises. Average COP of the system during electricity load peak hours (10:00–14:00) for all five considered and combined months is 1.77. Average rate of heat input required to operate the system and average building cooling load are determined to be 100.3 kW and 46.2 kW, respectively. Therefore, system average COP is computed to be 0.46.

Air conditioning for data processing system areas

Directory of Open Access Journals (Sweden)

Hernando Camacho García

1996-09-01

Full Text Available The appropiate selection of air conditioners for data processing system areas requires the knowledge of the environmental desing conditions, the air conditioning systems succssfully used computer and the cooling loads to handle. This work contains information about a wide variety of systems designed for computer room applications. a complete example of calculation to determine the amount of heat to be removed for satisfactory operation, is also included.

Experimental analysis of fuzzy controlled energy efficient demand controlled ventilation economizer cycle variable air volume air conditioning system

Directory of Open Access Journals (Sweden)

Rajagopalan Parameshwaran

2008-01-01

Full Text Available In the quest for energy conservative building design, there is now a great opportunity for a flexible and sophisticated air conditioning system capable of addressing better thermal comfort, indoor air quality, and energy efficiency, that are strongly desired. The variable refrigerant volume air conditioning system provides considerable energy savings, cost effectiveness and reduced space requirements. Applications of intelligent control like fuzzy logic controller, especially adapted to variable air volume air conditioning systems, have drawn more interest in recent years than classical control systems. An experimental analysis was performed to investigate the inherent operational characteristics of the combined variable refrigerant volume and variable air volume air conditioning systems under fixed ventilation, demand controlled ventilation, and combined demand controlled ventilation and economizer cycle techniques for two seasonal conditions. The test results of the variable refrigerant volume and variable air volume air conditioning system for each techniques are presented. The test results infer that the system controlled by fuzzy logic methodology and operated under the CO2 based mechanical ventilation scheme, effectively yields 37% and 56% per day of average energy-saving in summer and winter conditions, respectively. Based on the experimental results, the fuzzy based combined system can be considered to be an alternative energy efficient air conditioning scheme, having significant energy-saving potential compared to the conventional constant air volume air conditioning system.

A Framework for Evaluating Economic Impacts of Rooftop PV Systems with or without Energy Storage on Thai Distribution Utilities and Ratepayers

Science.gov (United States)

Chaianong, A.; Bangviwat, A.; Menke, C.

2017-07-01

Driven by decreasing PV and energy storage prices, increasing electricity costs and policy supports from Thai government (self-consumption era), rooftop PV and energy storage systems are going to be deployed in the country rapidly that may disrupt existing business models structure of Thai distribution utilities due to revenue erosion and lost earnings opportunities. The retail rates that directly affect ratepayers (non-solar customers) are expected to increase. This paper focuses on a framework for evaluating impacts of PV with and without energy storage systems on Thai distribution utilities and ratepayers by using cost-benefit analysis (CBA). Prior to calculation of cost/benefit components, changes in energy sales need to be addressed. Government policies for the support of PV generation will also help in accelerating the rooftop PV installation. Benefit components include avoided costs due to transmission losses and deferring distribution capacity with appropriate PV penetration level, while cost components consist of losses in revenue, program costs, integration costs and unrecovered fixed costs. It is necessary for Thailand to compare total costs and total benefits of rooftop PV and energy storage systems in order to adopt policy supports and mitigation approaches, such as business model innovation and regulatory reform, effectively.

THE USE OF AIR LAYERS IN BUILDING ENVELOPES FOR ENERGY SAVING DURING AIR CONDITIONING

Directory of Open Access Journals (Sweden)

S. N. Osipov

2017-01-01

Full Text Available Since there are no large natural energy resources in Belarus, energy savings ought to be a point of the special attention. With this regard it is important to develop modern ways of savings during the process of air conditioning inside new buildings with an air layer in the enclosure, especially in translucent ones. The system of ventilation of air layers in the enclosure of a building has been introduced in which air movement is caused by the gravitational and aerodynamic forces. It makes it possible to arrange further ventilation – a natural, forced or a hybrid one. With the purpose of increasing and streamlining natural draught the partitions are used separating the different parts of air layers. For natural ventilation with the use of gravitational forces the holes in the upper and lower parts of the partitions between adjacent air layers are applied. Natural ventilation in the holes of the partitions is regulated by movable shutters, blinds or other adjusting devices. For combined or forced air exchange between adjacent zones of air layers fans are used pumping air from the air layer zones with a higher temperature to zones of air layers with lower temperature and vice versa. When air exchange is forced, in order to intensify the infiltration of air into zones of air layers jets are laid on a hard surface. In order to cool a multi-layered enclosure of a building, where the movement of air between the air layers (that have been formed by internal partitions is being fulfilled by a natural, forced or combined mode, a part of the air or the total air processed inside the building (i.e. conditioned or non-conditioned air cooler as compared with the outside one is being sent to these strata. Combined or forced flow of the air processed inside the building into the air layers is done through the ducts associated with the output channels of the air conditioners. The internal partitions are equipped with the air valve hole.

INTERGRATION OF LiDAR DATA WITH AERIAL IMAGERY FOR ESTIMATING ROOFTOP SOLAR PHOTOVOLTAIC POTENTIALS IN CITY OF CAPE TOWN

Directory of Open Access Journals (Sweden)

A. K. Adeleke

2016-06-01

Full Text Available Apart from the drive to reduce carbon dioxide emissions by carbon-intensive economies like South Africa, the recent spate of electricity load shedding across most part of the country, including Cape Town has left electricity consumers scampering for alternatives, so as to rely less on the national grid. Solar energy, which is adequately available in most part of Africa and regarded as a clean and renewable source of energy, makes it possible to generate electricity by using photovoltaics technology. However, before time and financial resources are invested into rooftop solar photovoltaic systems in urban areas, it is important to evaluate the potential of the building rooftop, intended to be used in harvesting the solar energy. This paper presents methodologies making use of LiDAR data and other ancillary data, such as high-resolution aerial imagery, to automatically extract building rooftops in City of Cape Town and evaluate their potentials for solar photovoltaics systems. Two main processes were involved: (1 automatic extraction of building roofs using the integration of LiDAR data and aerial imagery in order to derive its’ outline and areal coverage; and (2 estimating the global solar radiation incidence on each roof surface using an elevation model derived from the LiDAR data, in order to evaluate its solar photovoltaic potential. This resulted in a geodatabase, which can be queried to retrieve salient information about the viability of a particular building roof for solar photovoltaic installation.

Plate heat exchangers in air conditioning applications. Development of air-coolers, air-heaters and air-conditioning units with low pressure loss. Plattenwaermetauscher in raumlufttechnischen Anlagen. Entwicklung stroemungsoptimierter Luftkuehler, Lufterhitzer und Klimageraete

Energy Technology Data Exchange (ETDEWEB)

Bach, H; Diemer, R; Eisenmann, G; Goettling, D; Madjidi, M

1989-08-01

To prepare the development of a water to air plate heat exchanger the state of the art, i.e. the technological knowhow and the design basis are given. The concept and ideas are presented which lead to a slightly wavy plate. Furthermore an exemplary design of a plate heat exchanger and an air-conditioning unit is described and finally the application of plate heat exchangers as direct evaporators and the potential icing problems are investigated. Comparing measured and calculated data shows that the performance of plates with plane surfaces can be predicted fairly well by the presented design methods. The performance of plates with strongly wavy surface however has to be measured. Optimization calculations yield to an air gap of slightly over 4 mm. Comparison with an air-conditioning unit demonstrates that the strongest advantage is for the air cooler (one third of the pressure loss) that a new concept of an air-conditioning unit has lower losses in the fan unit and that it does not need an eliminator. This results in half the volume for the new unit, in a pressure drop of 88%, fan power of 90% and fan revolutions of 50%. (orig./GL).

Was it worthwhile? Where have the benefits of rooftop solar photovoltaic generation exceeded the cost?

Science.gov (United States)

Vaishnav, Parth; Horner, Nathaniel; Azevedo, Inês L.

2017-09-01

We estimate the lifetime magnitude and distribution of the private and public benefits and costs of currently installed distributed solar PV systems in the United States. Using data for recently-installed systems, we estimate the balance of benefits and costs associated with installing a non-utility solar PV system today. We also study the geographical distribution of the various subsidies that are made available to owners of rooftop solar PV systems, and compare it to distributions of population and income. We find that, after accounting for federal subsidies and local rebates and assuming a discount rate of 7%, the private benefits of new installations will exceed private costs only in seven of the 19 states for which we have data and only if customers can sell excess power to the electric grid at the retail price. These states are characterized by abundant sunshine (California, Texas and Nevada) or by high electricity prices (New York). Public benefits from reduced air pollution and climate change impact exceed the costs of the various subsidies offered system owners for less than 10% of the systems installed, even assuming a 2% discount rate. Subsidies flowed disproportionately to counties with higher median incomes in 2006. In 2014, the distribution of subsidies was closer to that of population income, but subsidies still flowed disproportionately to the better-off. The total, upfront, subsidy per kilowatt of installed capacity has fallen from 5200 in 2006 to 1400 in 2014, but the absolute magnitude of subsidy has soared as installed capacity has grown explosively. We see considerable differences in the balance of costs and benefits even within states, indicating that local factors such as system price and solar resource are important, and that policies (e.g. net metering) could be made more efficient by taking local conditions into account.

Sampling for Air Chemical Emissions from the Life Sciences Laboratory II

Energy Technology Data Exchange (ETDEWEB)

Ballinger, Marcel Y. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lindberg, Michael J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2017-03-30

Sampling for air chemical emissions from the Life Science Laboratory II (LSL-II) ventilation stack was performed in an effort to determine potential exposure of maintenance staff to laboratory exhaust on the building roof. The concern about worker exposure was raised in December 2015 and several activities were performed to assist in estimating exposure concentrations. Data quality objectives were developed to determine the need for and scope and parameters of a sampling campaign to measure chemical emissions from research and development activities to the outside air. The activities provided data on temporal variation of air chemical concentrations and a basis for evaluating calculated emissions. Sampling for air chemical emissions was performed in the LSL-II ventilation stack over the 6-week period from July 26 to September 1, 2016. A total of 12 sampling events were carried out using 16 sample media. Resulting analysis provided concentration data on 49 analytes. All results were below occupational exposure limits and most results were below detection limits. When compared to calculated emissions, only 5 of the 49 chemicals had measured concentrations greater than predicted. This sampling effort will inform other study components to develop a more complete picture of a worker’s potential exposure from LSL-II rooftop activities. Mixing studies were conducted to inform spatial variation in concentrations at other rooftop locations and can be used in conjunction with these results to provide temporal variations in concentrations for estimating the potential exposure to workers working in and around the LSL-II stack.

Health effects of air conditioning

Energy Technology Data Exchange (ETDEWEB)

Molina, C.; Caillaud, D.

The air conditioning used in residential or commercial buildings (offices, hotels, sterile areas of hospitals, computer and electronics industries) is responsible for a certain number of well identified ailments which can be classified in three groups: infections (legionnaires'disease, ornithosis), allergies (mainly respiratory) eg. rhinitis, asthma, alveolitis but also Monday morning illness or humidifier fever, various functional disorders grouped under the name Sick Building Syndrome. To avoid these problems, a certain number of recommendations may be made. They concern: installation of air conditioning, humidification which is the cause of bacterial and fungal contamination, filtration, monitoring of the installation by qualitative and quantitative measurements, maintenance. The legal problems relating to these illnesses, the responsibility for which is ultimately laid at the door of the installers, should also be mentioned. Allergies are recognized to be of professional origin in Table 66 of allergic illnesses issued by the Social Security.

[Air quality control systems: heating, ventilating, and air conditioning (HVAC)].

Science.gov (United States)

Bellucci Sessa, R; Riccio, G

2004-01-01

After a brief illustration of the principal layout schemes of Heating, Ventilating, and Air Conditioning (HVAC), the first part of this paper summarizes the standards, both voluntary and compulsory, regulating HVAC facilities design and installation with regard to the question of Indoor Air Quality (IAQ). The paper then examines the problem of ventilation systems maintenance and the essential hygienistic requirements in whose absence HVAC facilities may become a risk factor for people working or living in the building. Lastly, the paper deals with HVAC design strategies and methods, which aim not only to satisfy comfort and air quality requirements, but also to ensure easy and effective maintenance procedures.

Opportunities to Reduce Air-Conditioning Loads Through Lower Cabin Soak Temperatures

International Nuclear Information System (INIS)

Farrington, R.; Cuddy, M.; Keyser, M.; Rugh, J.

1999-01-01

Air-conditioning loads can significantly reduce electric vehicle (EV) range and hybrid electric vehicle (HEV) fuel economy. In addition, a new U. S. emissions procedure, called the Supplemental Federal Test Procedure (SFTP), has provided the motivation for reducing the size of vehicle air-conditioning systems in the United States. The SFTP will measure tailpipe emissions with the air-conditioning system operating. If the size of the air-conditioning system is reduced, the cabin soak temperature must also be reduced, with no penalty in terms of passenger thermal comfort. This paper presents the impact of air-conditioning on EV range and HEV fuel economy, and compares the effectiveness of advanced glazing and cabin ventilation. Experimental and modeled results are presented

Application of solar energy to air conditioning systems

Science.gov (United States)

Nash, J. M.; Harstad, A. J.

1976-01-01

The results of a survey of solar energy system applications of air conditioning are summarized. Techniques discussed are both solar powered (absorption cycle and the heat engine/Rankine cycle) and solar related (heat pump). Brief descriptions of the physical implications of various air conditioning techniques, discussions of status, proposed technological improvements, methods of utilization and simulation models are presented, along with an extensive bibliography of related literature.

Performance advancement of solar air-conditioning through integrated system design for building

International Nuclear Information System (INIS)

Fong, K.F.; Lee, C.K.

2014-01-01

This study is to advance the energy performance of solar air-conditioning system through appropriate component integration from the absorption refrigeration cycle and proper high-temperature cooling. In the previous studies, the solar absorption air-conditioning using the working pair of water – lithium bromide (H 2 O–LiBr) is found to have prominent primary energy saving than the conventional compression air-conditioning for buildings in the hot-humid climate. In this study, three integration strategies have been generated for solar cooling, namely integrated absorption air-conditioning; integrated absorption-desiccant air-conditioning; and integrated absorption-desiccant air-conditioning for radiant cooling. To realize these ideas, the working pair of ammonia – water (NH 3 –H 2 O) was used in the absorption cycle, rather than H 2 O–LiBr. As such, the evaporator and the condenser can be separate from the absorption refrigeration cycle for the new configuration of various integrated design alternatives. Through dynamic simulation, the year-round primary energy saving of the proposed integration strategies for solar NH 3 –H 2 O absorption air-conditioning systems could be up to 50.6% and 25.5%, as compared to the conventional compression air-conditioning and the basic solar H 2 O–LiBr absorption air-conditioning respectively. Consequently, carbon reduction of building air-conditioning can be achieved more effectively through the integrated system design in the hot and humid cities. - Highlights: • Three integration strategies, IAAU, IADAU and IADAU-RC, are proposed to advance solar air-conditioning. • NH 3 –H 2 O is adopted for absorption refrigeration instead of H 2 O–LiBr. • Separate evaporator and condenser, desiccant cooling and radiant cooling are designed for IADAU-RC. • IADAU-RC can have 50.6% primary energy saving against the conventional air-conditioning

Mountain Plains Learning Experience Guide: Heating, Refrigeration, & Air Conditioning.

Science.gov (United States)

Carey, John

This Heating, Refrigeration, and Air Conditioning course is comprised of eleven individualized units: (1) Refrigeration Tools, Materials, and Refrigerant; (2) Basic Heating and Air Conditioning; (3) Sealed System Repairs; (4) Basic Refrigeration Systems; (5) Compression Systems and Compressors; (6) Refrigeration Controls; (7) Electric Circuit…

Sensitivity of Rooftop PV Projections in the SunShot Vision Study to Market Assumptions

Energy Technology Data Exchange (ETDEWEB)

Drury, E.; Denholm, P.; Margolis, R.

2013-01-01

The SunShot Vision Study explored the potential growth of solar markets if solar prices decreased by about 75% from 2010 to 2020. The SolarDS model was used to simulate rooftop PV demand for this study, based on several PV market assumptions--future electricity rates, customer access to financing, and others--in addition to the SunShot PV price projections. This paper finds that modeled PV demand is highly sensitive to several non-price market assumptions, particularly PV financing parameters.

Air conditioning device for reactor buildings

International Nuclear Information System (INIS)

Kikuchi, Shiro.

1982-01-01

Purpose: To decrease the opening areas of pipe lines for an air conditioning device at the portions passing through the shielding walls of a reactor building for a FBR type reactor, as well as reduce the size of the building. Constitution: Airs in the building for containing reactor are liquefied in an air liquefying mechanism. The liquefied airs are sent by way of pipe lines to each of evaporators, wherein each of the chambers are cooled because of latent heat of evaporation and evaporated airs are released to each of the chambers. The airs released to each of the chambers are collected into an exhaust chamber and sent by way of a duct to the air liquefying mechanism and liquefied again. Since the volume of the liquefied airs may be smaller than the amount conventionally required for usual cooled airs, the pipe lines passing through the shielding walls of the building can be of smaller diameter. This can decrease the opening areas of the pipe lines at the portions passing through the walls of the shieldings and, since the opening areas are smaller, the structure of the radiation shieldings can be simplified in these portions. Further, since the space of the pipe lines in the building is reduced extremely, the size of the building can be reduced. (Moriyama, K.)

Influence of different outdoor design conditions on design cooling load and design capacities of air conditioning equipments

International Nuclear Information System (INIS)

Aktacir, Mehmet Azmi; Bueyuekalaca, Orhan; Bulut, Huesamettin; Yilmaz, Tuncay

2008-01-01

Outdoor design conditions are important parameters for energy efficiency of buildings. The result of incorrect selection of outdoor design conditions can be dramatic in view of comfort and energy consumption. In this study, the influence of different outdoor design conditions on air conditioning systems is investigated. For this purpose, cooling loads and capacities of air conditioning equipments for a sample building located in Adana, Turkey are calculated using different outdoor design conditions recommended by ASHRAE, the current design data used in Turkey and the daily maximum dry and wet bulb temperatures of July 21st, which is generally accepted as the design day. The cooling coil capacities obtained from the different outdoor design conditions considered in this study are compared with each other. The cost analysis of air conditioning systems is also performed. It is seen that the selection of outdoor design conditions is a very critical step in calculation of the building cooling loads and design capacities of air conditioning equipments

[Relationships between air conditioning, airborne microorganisms and health].

Science.gov (United States)

Parat, S; Perdrix, A; Baconnier, P

1999-01-01

Concurrently with the increase of air-conditioning, potentially severe or frequent new diseases have emerged, giving rise to social and economical consequences. The first part of this work is a state of the art review of the relationships between air-conditioning, airborne microorganisms and health, through a technical, metrological and medical approach. The second part presents four studies performed in this field. Two of them deal with the relationship between airborne microorganisms and technical features of air-conditioning. Measurements performed on actual sites demonstrated the benefit of using high efficiency filters and low risk components in air-conditioning systems. The third study was aimed to look for a relationship between airborne microorganisms and sick building syndrome symptoms. Statistical analyses of individual data revealed significant associations between airborne bacteria or fungi and symptoms. These results may be the first step in determining a dose-response relationship, in order to define threshold limit values in this field. In the fourth study, the contribution of particle counting in assessing exposure to airborne microorganisms was explored by monitoring simultaneous variations of microbial and particle concentrations. The results showed that associating particle counting may allow to detect microbial variations instantaneously, and therefore improve the assessment of exposure to airborne microorganisms.

Impaired Air Conditioning within the Nasal Cavity in Flat-Faced Homo.

Directory of Open Access Journals (Sweden)

Takeshi Nishimura

2016-03-01

Full Text Available We are flat-faced hominins with an external nose that protrudes from the face. This feature was derived in the genus Homo, along with facial flattening and reorientation to form a high nasal cavity. The nasal passage conditions the inhaled air in terms of temperature and humidity to match the conditions required in the lung, and its anatomical variation is believed to be evolutionarily sensitive to the ambient atmospheric conditions of a given habitat. In this study, we used computational fluid dynamics (CFD with three-dimensional topology models of the nasal passage under the same simulation conditions, to investigate air-conditioning performance in humans, chimpanzees, and macaques. The CFD simulation showed a horizontal straight flow of inhaled air in chimpanzees and macaques, contrasting with the upward and curved flow in humans. The inhaled air is conditioned poorly in humans compared with nonhuman primates. Virtual modifications to the human external nose topology, in which the nasal vestibule and valve are modified to resemble those of chimpanzees, change the airflow to be horizontal, but have little influence on the air-conditioning performance in humans. These findings suggest that morphological variation of the nasal passage topology was only weakly sensitive to the ambient atmosphere conditions; rather, the high nasal cavity in humans was formed simply by evolutionary facial reorganization in the divergence of Homo from the other hominin lineages, impairing the air-conditioning performance. Even though the inhaled air is not adjusted well within the nasal cavity in humans, it can be fully conditioned subsequently in the pharyngeal cavity, which is lengthened in the flat-faced Homo. Thus, the air-conditioning faculty in the nasal passages was probably impaired in early Homo members, although they have survived successfully under the fluctuating climate of the Plio-Pleistocene, and then they moved "Out of Africa" to explore the more

PROSPECTS FOR THE DEVELOPMENT OF TECHNOLOGY AIR CONDITIONING

Directory of Open Access Journals (Sweden)

O. V. Chernyshova

2008-03-01

Full Text Available In the article the evaporation cooling and spray (aqueous and air-to-water types of the air-conditioning systems are considered, their merits and demerits are analyzed; the new scheme of a conditioner is offered.

Effects of suspension of air-conditioning on airtight-type racks.

Science.gov (United States)

Kanzaki, M; Fujieda, M; Furukawa, T

2001-10-01

Although isolation racks are superior to open-type racks in terms of securing breeding conditions for laboratory animals, the contingency-proofing capability of the former has yet to be determined. Therefore, from the view of risk management, we studied the environmental change in isolation racks by forcibly suspending ventilation and air-conditioning and confirming the maximal time length for complete recovery to the original condition after restarting their operations. The isolation racks were placed in a room that was equipped with an independent air-conditioning system. When the inside condition of the racks reached 22-24 degrees C and 59-64% of relative humidity, the air-conditioning and ventilation were forcibly suspended and the subsequent temperature, relative humidity, ammonium and CO2 concentrations in the racks were measured over time. We found that after suspending the air-conditioning and ventilation, it took 40-60 min for temperature, and about 10 min for relative humidity to exceed the maximum values (temperature and relative humidity) referred to in the Showa 58 Nenban Guideline Jikken Doubutsu Shisetsu no Kenchiku oyobi Setsubi (Guidelines of buildings and facilities for experimental animals in Japan; Year 1983 edition). After 17 hr 25 min of the suspension of air-conditioning and ventilation, two rats were found dead. Then, the air-conditioning and ventilation were restarted. It took about 2 hr for temperature, and 50 min for relative humidity to regain the guideline values. The ammonium concentration stayed within the guideline value with a maximum concentration of 2 ppm in the experimental period, whereas the CO2 concentration was found to exceed 9% at the time of animal death.

Monitoring and analysis of an absorption air-conditioning system

Energy Technology Data Exchange (ETDEWEB)

Perez de Vinaspre, M.; Bourouis, M.; Coronas, A. [Centro de Innovacion Tecnologica en Revalorizacion Energetica y Refrigeracion, Tarragona (Spain); Garcia, A.; Soto, V.; Pinazo, J.M. [E.T.S. Ingenieros Industriales, Valencia (Spain)

2004-09-01

In the last few years, high-energy consumption due to air-conditioning has led to a growing interest in the efficient use of energy in buildings. Although simulation programs have always been the main tools for analyzing energy in buildings, the reliability of their results is often compromised by a lack of certainty to reflect real conditions. The aim of this work is to monitorize and analyze the thermal behavior of an absorption-based air-conditioning installation of a university building in Tarragona, Spain. The existing monitoring system of the installation has been improved by implementing additional sensors and flow meters. The data has been stored during summer 2002 and used to assess the energy balance of the air-conditioning installation and the operational regime of the absorption chiller. [Author].

Central Air-Conditioning Plant (CAP) extension

International Nuclear Information System (INIS)

Shetty, P.S.; Kaul, S.K.; Mishra, H.

2017-01-01

Central Air-Conditioning Plant (CAP) and its associated chilled water network of BARC is one among the largest central plants in India for such application. The plant was planned in 1960s to cater to the air-conditioning and process water requirements of laboratories, workshops and buildings spread over a distance of 1.5 Km in three directions from CAP through underground network of chilled water pipelines. The plant was designed for a total capacity of 6600 TR. The present installed capacity of the plant is 7250 TR. The connected load at present is 9800 TR. After the XII plan capacity will be augmented to 7650 TR. The connected load is expected to cross 11,000 TR after the commissioning of new Engg. Halls 9, 10 and 11

Air conditioning systems as non-infectious health hazards inducing acute respiratory symptoms.

Science.gov (United States)

Gerber, Alexander; Fischer, Axel; Willig, Karl-Heinz; Groneberg, David A

2006-04-01

Chronic and acute exposure to toxic aerosols belongs to frequent causes of airway diseases. However, asthma attacks due to long-distance inhalative exposure to organic solvents, transmitted via an air condition system, have not been reported so far. The present case illustrates the possibility of air conditioning systems as non-infectious health hazards in occupational medicine. So far, only infectious diseases such as legionella pneumophila pneumonia have commonly been associated to air-conditioning exposures but physicians should be alert to the potential of transmission of toxic volatile substances via air conditioning systems. In view of the events of the 11th of September 2001 with a growing danger of large building terrorism which may even use air conditioning systems to transmit toxins, facility management security staff should be alerted to possible non-infectious toxic health hazards arising from air-conditioning systems.

41 CFR 102-79.65 - May Executive agencies outlease space on major public access levels, courtyards and rooftops of...

Science.gov (United States)

2010-07-01

... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false May Executive agencies outlease space on major public access levels, courtyards and rooftops of public buildings? 102-79.65... Utilization of Space Outleasing § 102-79.65 May Executive agencies outlease space on major public access...

Small photovoltaic setup for the air conditioning system

Directory of Open Access Journals (Sweden)

Masiukiewicz Maciej

2017-01-01

Full Text Available The increasing interest in air conditioning systems for residential applications in Poland will certainly increase the demand for electricity during the summer period. Due to this fact a growing interest in solutions that help to lower the electricity consumption in this sector is observed. The problem of increased energy demand for air conditioning purposes can be solved by transfer the consumption of electricity from the grid system to renewable energy sources (RES. The greatest demand for cooling occurs during the biggest sunlight. This is the basis for the analysis of technical power system based on photovoltaic cells (PV to power the split type air conditioner. The object of the study was the commercial residential airconditioning inverter units with a capacity of 2.5kW. A network electricity production system for their own use with the possibility of buffering energy in batteries (OFF-GRID system. Currently, on the Polish market, there are no developed complete solutions dedicated to air conditioning systems based on PV. In Poland, solar energy is mainly used for heat production in solar collectors. The proposed solution will help to increase the popularity of PV systems in the Polish market as an alternative to other RES. The basic conclusion is that the amount of PV energy generated was sufficient to cover the daily energy requirement of the air conditioner.

Small photovoltaic setup for the air conditioning system

Science.gov (United States)

Masiukiewicz, Maciej

2017-10-01

The increasing interest in air conditioning systems for residential applications in Poland will certainly increase the demand for electricity during the summer period. Due to this fact a growing interest in solutions that help to lower the electricity consumption in this sector is observed. The problem of increased energy demand for air conditioning purposes can be solved by transfer the consumption of electricity from the grid system to renewable energy sources (RES). The greatest demand for cooling occurs during the biggest sunlight. This is the basis for the analysis of technical power system based on photovoltaic cells (PV) to power the split type air conditioner. The object of the study was the commercial residential airconditioning inverter units with a capacity of 2.5kW. A network electricity production system for their own use with the possibility of buffering energy in batteries (OFF-GRID system). Currently, on the Polish market, there are no developed complete solutions dedicated to air conditioning systems based on PV. In Poland, solar energy is mainly used for heat production in solar collectors. The proposed solution will help to increase the popularity of PV systems in the Polish market as an alternative to other RES. The basic conclusion is that the amount of PV energy generated was sufficient to cover the daily energy requirement of the air conditioner.

Solar-Driven Air-Conditioning Cycles: A Review

Directory of Open Access Journals (Sweden)

A. M. Abu-Zour

2007-12-01

Full Text Available Most conventional cooling/refrigeration systems are driven by fossil fuel combustion, and therefore give rise to emission of environmentally damaging pollutants. In addition, many cooling systems employ refrigerants, which are also harmful to the environment in terms of their Global Warming Potential (GWP and Ozone Depletion Potential (ODP. Development of a passive or hybrid solar-driven air-conditioning system is therefore of interest as exploitation of such systems would reduce the demand for grid electricity particularly at times of peak load. This paper presents a review of various cooling cycles and summarises work carried out on solar-driven air-conditioning systems.

Air-conditioning and ventilation systems and components of nuclear facilities

International Nuclear Information System (INIS)

2006-01-01

The Guide defines the requirements for the design, implementation and operation of the air-conditioning and ventilation systems of nuclear facilities belonging to safety classes 3 and 4, and for the related documents to be submitted to STUK (Radiation and Nuclear Safety Authority, Finland). Furthermore, the Guide describes the inspections of air-conditioning and ventilation systems to be conducted by STUK during construction and operation of the facilities. As far as systems and components belonging to safety class 2 are concerned, STUK sets additional requirements case by case. In general, air-conditioning systems refer to systems designed to manage the indoor air cleanness, temperature, humidity and movement. In some rooms of a nuclear power plant, ventilation systems are also used to prevent radioactive materials from spreading outside the rooms. Guide YVL1.0 defines the safety principles concerning the air-conditioning and ventilation of nuclear power plants. Guide YVL2.0 gives the requirements for the design of nuclear power plant systems. In addition, YVLGuide groups 3, 4, 5 and 7 deal with the requirements for air-conditioning and ventilation systems with regard to the mechanical equipment, fire prevention, electrical systems, instrumentation and control technology, and the restriction of releases. The rules and regulations issued by the Ministry of the Environment and the Ministry of the Interior (RakMK, the Finnish building code) concerning the design and operation of air-conditioning and ventilation systems and the related fire protection design bases also apply to nuclear facilities. Exhaust gas treatment systems, condenser vacuum systems of boiling water reactor plants and leak collection systems are excluded from the scope of this Guide

Performance study of desiccant coated heat exchanger air conditioning system in winter

International Nuclear Information System (INIS)

Ge, T.S.; Dai, Y.J.; Wang, R.Z.

2016-01-01

Highlights: • Performance of desiccant coated heat exchanger AC system is predicted. • Effects of main operation parameters and climatic conditions are discussed. • Regeneration temperature of 30 °C is recommended under simulation condition. • Higher ambient humidity ratio results in increased humidity ratio of supply air. • Temperature of ambient air has neglectable effect on supply air. - Abstract: Conventional air source heat pump system faces several challenges when adopted in winter season. Solid desiccant air conditioning system can provide humidification and heating power simultaneously and can be driven by low grade thermal energy; it provides a good alternative for air source heat pump systems. However, conventional solid desiccant air conditioning system adopts desiccant wheel with high cost as core component, which hinders the development of such system. Recently, desiccant coated heat exchanger (DCHE) with low initial cost and high efficiency was developed and this paper aims to investigate performance of DCHE air conditioning system adopted in Shanghai winter season. Performance of the system is predicted by a developed mathematical model where supply air states, mass of humidification and coefficient of performance (COP) are adopted as performance indices to evaluate the feasibility and energy utilization ratio of the system. Effects of regeneration water temperature on system performance are analyzed. It is found that under the simulation condition, relatively low regeneration temperature (such as 20 °C) cannot meet the designed standard and relatively high regeneration temperature (such as 40 °C) provides too much extra heating power, thus moderate regeneration temperature around 30 °C is recommended. Meanwhile, switch time is a crucial operation parameter for the system to obtain satisfied supply air, switch time from 40 s to 80 s and from 70 s to 240 s are recommended for transient and average supply air states, respectively. Both

Thermal Environment for Classrooms. Central System Approach to Air Conditioning.

Science.gov (United States)

Triechler, Walter W.

This speech compares the air conditioning requirements of high-rise office buildings with those of large centralized school complexes. A description of one particular air conditioning system provides information about the system's arrangement, functions, performance efficiency, and cost effectiveness. (MLF)

Air-cooled LiBr-water absorption chillers for solar air conditioning in extremely hot weathers

International Nuclear Information System (INIS)

Kim, D.S.; Infante Ferreira, C.A.

2009-01-01

A low temperature-driven absorption cycle is theoretically investigated for the development of an air-cooled LiBr-water absorption chiller to be combined with low-cost flat solar collectors for solar air conditioning in hot and dry regions. The cycle works with dilute LiBr-water solutions so that risk of LiBr crystallization is less than for commercially available water-cooled LiBr-water absorption chillers even in extremely hot ambient conditions. Two-phase heat exchangers in the system were modelled taking account of the heat and mass transfer resistances in falling film flows by applying the film theory in thermal and concentration boundary layers. Both directly and indirectly air-cooled chillers were modelled by properly combining component models and boundary conditions in a matrix system and solved with an algebraic equation solver. Simulation results predict that the chillers would deliver chilled water around 7.0 deg. C with a COP of 0.37 from 90 deg. C hot water under 35 deg. C ambient condition. At 50 deg. C ambient temperature, the chillers retained about 36% of their cooling power at 35 deg. C ambient. Compared with the directly air-cooled chiller, the indirectly air-cooled chiller presented a cooling power performance reduction of about 30%

Thermodynamic analysis of the two-phase ejector air-conditioning system for buses

International Nuclear Information System (INIS)

Ünal, Şaban; Yilmaz, Tuncay

2015-01-01

Air-conditioning compressors of the buses are usually operated with the power taken from the engine of the buses. Therefore, an improvement in the air-conditioning system will reduce the fuel consumption of the buses. The improvement in the coefficient of performance (COP) of the air-conditioning system can be provided by using the two-phase ejector as an expansion valve in the air-conditioning system. In this study, the thermodynamic analysis of bus air-conditioning system enhanced with a two-phase ejector and two evaporators is performed. Thermodynamic analysis is made assuming that the mixing process in ejector occurs at constant cross-sectional area and constant pressure. The increase rate in the COP with respect to conventional system is analyzed in terms of the subcooling, condenser and evaporator temperatures. The analysis shows that COP improvement of the system by using the two phase ejector as an expansion device is 15% depending on design parameters of the existing bus air-conditioning system. - Highlights: • Thermodynamic analysis of the two-phase ejector refrigeration system. • Analysis of the COP increase rate of bus air-conditioning system. • Analysis of the entrainment ratio of the two-phase ejector refrigeration system

An energy impact assessment of indoor air quality acceptance for air-conditioned offices

International Nuclear Information System (INIS)

Wong, L.T.; Mui, K.W.; Shi, K.L.; Hui, P.S.

2008-01-01

Treatment of fresh air in ventilation systems for the air-conditioning consumes a considerable amount of energy and affects the indoor air quality (IAQ). The ventilation demand is primarily related to the occupant load. In this study, the ventilation demands due to occupant load variations and occupant acceptability were examined against certain IAQ objectives using the mass balance of carbon dioxide (CO 2 ) concentrations in an air-conditioned office. In particular, this study proposed a ventilation model for the consideration of the occupant load variations and occupant acceptability based on the regional survey of typical offices (422 samples) in Hong Kong. The model was applied to evaluate the relative energy performance of different IAQ objectives in ventilation systems for typical office buildings in Hong Kong. The results showed that the energy consumption of a ventilation system would be correlated with the occupant load and acceptability in the air-conditioned office. Indicative CO 2 levels of 800 ppmv, 1000 ppmv and 1200 ppmv corresponding to 83%, 97% and 99.7% survey samples were shown, corresponding to the thermal energy consumptions of 1500 MJ m -2 yr -1 , 960 MJ m -2 yr -1 and 670 MJ m -2 yr -1 , respectively. In regards to the monetary issue, an annual value of HK$ 762 million per year in electrical consumption could be saved in all office buildings in Hong Kong when the indoor target CO 2 concentration is increased from 1000 ppmv to 1200 ppmv. To achieve an excellent IAQ following the existing design standard, i.e. to decrease the CO 2 level from 1000 ppmv to 800 ppmv, 56% additional energy would be consumed, corresponding to an annual value of HK$ 1,419 million, even though the occupant acceptability is only improved from 81% to 86%. The development of the models in this study would be useful for the energy performance evaluation of ventilation systems in air-conditioned offices

Uncertainty Evaluation of Residential Central Air-conditioning Test System

Science.gov (United States)

Li, Haoxue

2018-04-01

According to national standards, property tests of air-conditioning are required. However, test results could be influenced by the precision of apparatus or measure errors. Therefore, uncertainty evaluation of property tests should be conducted. In this paper, the uncertainties are calculated on the property tests of Xinfei13.6 kW residential central air-conditioning. The evaluation result shows that the property tests are credible.

The application of gas ejector for road transport air conditioning system

Science.gov (United States)

Sumeru, Nasution, Henry; Ani, Farid Nasir

2012-06-01

The depletion of fossil fuel supply requires fuel and energy saving in energy utilization system. Therefore, these required the development of new and efficient technologies as to reduce fuel consumption especially in air conditioning of road vehicles. Currently, the air conditioning for road vehicles uses vapor compression system. Although the vapor compression system has high COP, the compressor is driven by vehicle engines, which take additional fuel consumption when the air conditioning system is in operation. In this study, the waste heat of radiator drives the ejector refrigeration for air conditioning. Although the ejector refrigeration system has low COP, the use of heat driven air conditioning will reduce the fuel consumption as compared with conventional system. This is because the systems do not use the mechanical engine load. The analysis of this study is based on the ejector refrigeration system using natural refrigerant (isobutene). The evaporation temperature is 10°C, condensation temperature is 35°C, generator temperature is 90°C with ejector isentropic efficiency of 0.7, and the COP system is 0.25. The heat released by the radiator of typical small road vehicles is between 60 to 100 kW and if the generator absorbs 20% of the heat, the heat contained in the generator is 12 to 20 kW. When the ejector air conditioning system has a COP 0.25, it will generate cooling capacity between 3 to 5 kW, compared with the conventional air conditioning of similar vehicles, which is approximately 2 to 4.4 kW.

Life Cycle Impact Assessment of a Rainwater Harvesting System Compared with an A/C Condensate System

Science.gov (United States)

This study reviewed U.S. commercial buildings to design a decentralized rooftop rainwater harvesting (RWH) system and air-conditioning (AC) condensate harvesting (ACH) system for non-potable use. RWH systems were designed for one-to multi-story buildings selected from each of th...

Large scale rooftop photovoltaics grid connected system at Charoenphol-Rama I green building

Energy Technology Data Exchange (ETDEWEB)

Ketjoy, N.; Rakwichian, W. [School of Renewable Energy Technology (SERT) (Thailand); Wongchupan, V. [Panya Consultants Co., Ltd (Thailand); Sankarat, T. [Tesco Lotus, Ek-Chai Distribution System Co., Ltd. (Thailand)

2004-07-01

This paper presents a technical feasibility study project for the large scale rooftop photovoltaics (PV) grid connected system at Charoenphol-Rama I green building super store of TESCO LOTUS (TL) in Thailand. The objective of this project is (i) to study the technical feasibility of installation 350 kWp PV systems on the top of the roof in this site (ii) and to determine the energy produce from this system. The technical factors are examined using a computerized PVS 2000 simulation and assessment tool. This super store building located in Bangkok, with latitude 14 N, longitude 100 E and the building direction is 16 from North direction. The building roof area is 14,000 m2; with 3 degree face East and 3 degree face West pitch. Average daily solar energy in this area is approximately 5.0 kWh. The study team for this project consists of educational institution as School of Renewable Energy Technology (SERT) and private institution as Panya Consultants (PC). TL is the project owner, PC is responsible for project management, and SERT is a third party and responsible for PV system study, conceptual design and all technical process. In this feasibility studies SERT will identify the most attractive scenarios of photovoltaic cell technology (mono, poly-crystalline or thin film amorphous), system design concepts for owners (TL) and determine possibility of the energy yield of the system from different module orientation and tilt angle. The result of this study is a guide to help TL to make decision to select proper rooftop PV system option for this store with proper technology view. The economic view will not be considered in this study. (orig.)

Online optimal control of variable refrigerant flow and variable air volume combined air conditioning system for energy saving

International Nuclear Information System (INIS)

Zhu, Yonghua; Jin, Xinqiao; Du, Zhimin; Fang, Xing

2015-01-01

The variable refrigerant flow (VRF) and variable air volume (VAV) combined air conditioning system can solve the problem of the VRF system in outdoor air ventilation while taking advantage of its high part load energy efficiency. Energy performance of the combined air conditioning system can also be optimized by joint control of both the VRF and the VAV parts. A model-based online optimal control strategy for the combined air conditioning system is presented. Simplified adaptive models of major components of the combined air conditioning system are firstly developed for predicting system performances. And a cost function in terms of energy consumption and thermal comfort is constructed. Genetic algorithm is used to search for the optimal control sets. The optimal control strategy is tested and evaluated through two case studies based on the simulation platform. Results show that the optimal strategy can effectively reduce energy consumption of the combined air conditioning system while maintaining acceptable thermal comfort. - Highlights: • A VRF and VAV combined system is proposed. • A model-based online optimal control strategy is proposed for the combined system. • The strategy can reduce energy consumption without sacrificing thermal comfort. • Novel simplified adaptive models are firstly developed for the VRF system

Assessment of indoor air quality in comparison using air conditioning and fan system in printing premise

Directory of Open Access Journals (Sweden)

Ramlan Nazirah

2017-01-01

Full Text Available Printers contribute to various emissions consist with chemical contaminants. High concentration of the particulate matter can cause serious health problems. This study focuses on the indoor air quality in printing premise unit in Universiti Tun Hussein Onn, Malaysia. Field testing involving air sampling methods were taken from 900 hours to 1600 hours, for every 30 minutes using physical measurement which is Multi-Channel Air Quality Monitor (YESAIR, E-Sampler and Ozone Meter. Air sampling was recorded based on one sampling point and most suitable point for production. A comparison based on different ventilation using fan and air-conditioning were also taken and results is being compared based on OSHA and NIOSH standards. Besides that, the statistical analysis is being conducted in order to predict the effect on number of printers. From the result, the O3 concentrations show, 10% reduced for printing premise using fan ventilation compared to air-conditioning but remain the same value for PM2.5. The concentration of O3 increased when the number of printers decreased, while the concentration of PM2.5 increased the increase of printers number. Overall, the use of fan in printing premise is more suggested since the level is slightly lower than the printing premise using air-conditioning.

[Assessment of the air quality improment of cleaning and disinfection on central air-conditioning ventilation system].

Science.gov (United States)

Liu, Hongliang; Zhang, Lei; Feng, Lihong; Wang, Fei; Xue, Zhiming

2009-09-01

To assess the effect of air quality of cleaning and disinfection on central air-conditioning ventilation systems. 102 air-conditioning ventilation systems in 46 public facilities were sampled and investigated based on Hygienic assessment criterion of cleaning and disinfection of public central air-conditioning systems. Median dust volume decreased from 41.8 g/m2 to 0.4 g/m2, and the percentage of pipes meeting the national standard for dust decreased from 17.3% (13/60) to 100% (62/62). In the dust, median aerobic bacterial count decreased from 14 cfu/cm2 to 1 cfu/cm2. Median aerobic fungus count decreased from 10 cfu/cm2 to 0 cfu/cm2. The percentage of pipes with bacterial and fungus counts meeting the national standard increased from 92.4% (171/185) and 82.2% (152/185) to 99.4% (165/166) and 100% (166/166), respectively. In the ventilation air, median aerobic bacterial count decreased from 756 cfu/m3 to 229 cfu/m3. Median aerobic fungus count decreased from 382 cfu/m3 to 120 cfu/m3. The percentage of pipes meeting the national standard for ventilation air increased from 33.3% (81/243) and 62.1% (151/243) to 79.8% (292/366) and 87.7% (242/276), respectively. But PM10 rose from 0.060 mg/m3 to 0.068 mg/m3, and the percentage of pipes meeting the national standard for PM10 increased from 74.2% (13/60) to 90.2% (46/51). The cleaning and disinfection of central air-conditioning ventilation systems could have a beneficial effect of air quality.

[Biological contamination in office buildings related to ventilation/air conditioning system].

Science.gov (United States)

Bródka, Karolina; Sowiak, Małgorzata; Kozajda, Anna; Cyprowski, Marcin; Irena, Szadkowska-Stańczyk

2012-01-01

Indoor air is contaminated with microorganisms coming from both the atmospheric air and sources present in premises. The aim of this study was to analyze the concentrations of biological agents in office buildings, dependending on ventilation/air conditioning system and season. The study covered office buildings (different in the system of ventila-tion/air conditioning). Air samples for assessing the levels of inhalable dust, endotoxins and (1-->3)-beta-D-glucans, were taken at the selected stationary points of each building during summer and winter. The air was sampled for 6 h, using portable sets consisting of the GilAir 5 pump and the head filled with a filter of fiber glass. The samples for the presence of airborne bacteria and fungi were collected twice during the day using the impaction method. Average concentrations of inhalable dust, bacteria, fungi, endotoxins and (1-->3)-beta-D-glucans in office premises were 0.09 mg/m3, 6.00 x 10(2) cfu/m3, 4.59 x 10(1) cfu/m3, 0.42 ng/m3 and 3.91 ng/m3, respectively. Higher concentrations of the investigated agents were found in summer. In premises with air conditioning concentrations of airborne fungi, (1-->3)-beta-D-glucans and inhalable dust were significantly lower in winter. In summer the trend was reverse except for (1-->3)-beta-D-glucans. Concentrations of biological agents were affected by the season and the presence of air conditioning. Concentrations of inhalable dust, bacteria, fungi, endotoxins and (1-->3)-beta-D-glucans, observed inside the office buildings, were significantly higher in summer than in winter. The presence of the air conditioning system modified in various ways the levels of biological agents. Its influence was greater on the concentration of fungi and (1-->3)-beta-D-glucans than on that of bacteria and endotoxins.

Performance Evaluation of Photovoltaic Solar Air Conditioning

Directory of Open Access Journals (Sweden)

Snegirjovs A.

2016-12-01

Full Text Available Information on the electrical-driven solar air conditioning (SAC is rather scanty. A considerable body of technical data mostly concerns large-scale photo-voltaic solar air conditioning (PV-SAC systems. Reliable information about the energy output has arisen only in recent years; however, it is still not easily accessible, and sometimes its sources are closed. Despite these facts, solar energy researchers, observers and designers devote special attention to this type of SAC systems. In this study, performance evaluation is performed for the PV-SAC technology, in which low-power (up to 15 kWp of cooling power on average systems are used. Such a system contains a PV electric-driven compression chiller with cold and heat sensible thermal storage capacities, and a rejected energy unit used for preheating domestic hot water (DHW. In a non-cooling season, it is possible to partly employ the system in the reverse mode for DHW production. In this mode, the ambient air serves as a heat source. Besides, free cooling is integrated in the PV-SAC concept.

Performance Evaluation of Photovoltaic Solar Air Conditioning

Science.gov (United States)

Snegirjovs, A.; Shipkovs, P.; Lebedeva, K.; Kashkarova, G.; Migla, L.; Gantenbein, P.; Omlin, L.

2016-12-01

Information on the electrical-driven solar air conditioning (SAC) is rather scanty. A considerable body of technical data mostly concerns large-scale photo-voltaic solar air conditioning (PV-SAC) systems. Reliable information about the energy output has arisen only in recent years; however, it is still not easily accessible, and sometimes its sources are closed. Despite these facts, solar energy researchers, observers and designers devote special attention to this type of SAC systems. In this study, performance evaluation is performed for the PV-SAC technology, in which low-power (up to 15 kWp of cooling power on average) systems are used. Such a system contains a PV electric-driven compression chiller with cold and heat sensible thermal storage capacities, and a rejected energy unit used for preheating domestic hot water (DHW). In a non-cooling season, it is possible to partly employ the system in the reverse mode for DHW production. In this mode, the ambient air serves as a heat source. Besides, free cooling is integrated in the PV-SAC concept.

A mixed air/air and air/water heat pump system ensures the air-conditioning of a cinema; Un systeme mixte PAC air/air et air/eau climatise un cinema

Energy Technology Data Exchange (ETDEWEB)

Anon.

2001-03-01

This article presents the air conditioning system of a new cinema complex of Boulogne (92, France) which comprises a double-flux air processing plant and two heat pumps. Each heat pump has two independent refrigerating loops: one with a air condenser and the other with a water condenser. This system allows to limit the power of the loop and to reduce the size of the cooling tower and of the vertical ducts. This article describes the technical characteristics of the installation: thermodynamic units, smoke clearing, temperature control, air renewing. (J.S.)

The Effect of Air-Conditioning on Student and Teacher Performance.

Science.gov (United States)

Phoenix Union High School District, AZ. Dept. of Research and Planning.

The literature is reviewed to see if research shows a relationship between student and teacher performance and air conditioning of classrooms. The benefits of air conditioning in promoting learning are substantiated by studies that are summarized but not cited. The relationship of the report to the Phoenix Union High School System Advisory…

Criticality Analysis of SFP Region I under Dry Air Condition

International Nuclear Information System (INIS)

Kim, Ki Yong; Kim, Min Chul

2016-01-01

This paper is to provide a result of the criticality evaluation under the condition that new fuel assemblies for initial fuel loading are storing in Region 1 of SFP in the dry air. The objective of this analysis is to ensure the effective neutron multiplication factor(k_e_f_f) of SFP is less than 0.95 under that condition. This analysis ensured the effective neutron multiplication factor(k_e_f_f) of Region 1 of SFP is less than 0.95 under the condition in the air. The keff in Region I of SFP under the condition of the dry air is 0.5865. The increased k_c_a_l_c of the Region 1 after the mislocated fuel assembly accident is 0.0444 at the pool flooded with un-borated water

Sustainability Challenges from Climate Change and Air Conditioning Use in Urban Areas

Directory of Open Access Journals (Sweden)

Karin Lundgren

2013-07-01

Full Text Available Global climate change increases heat loads in urban areas causing health and productivity risks for millions of people. Inhabitants in tropical and subtropical urban areas are at especial risk due to high population density, already high temperatures, and temperature increases due to climate change. Air conditioning is growing rapidly, especially in South and South-East Asia due to income growth and the need to protect from high heat exposures. Studies have linked increased total hourly electricity use to outdoor temperatures and humidity; modeled future predictions when facing additional heat due to climate change, related air conditioning with increased street level heat and estimated future air conditioning use in major urban areas. However, global and localized studies linking climate variables with air conditioning alone are lacking. More research and detailed data is needed looking at the effects of increasing air conditioning use, electricity consumption, climate change and interactions with the urban heat island effect. Climate change mitigation, for example using renewable energy sources, particularly photovoltaic electricity generation, to power air conditioning, and other sustainable methods to reduce heat exposure are needed to make future urban areas more climate resilient.

Performance evaluation of an integrated automotive air conditioning and heat pump system

International Nuclear Information System (INIS)

Hosoz, M.; Direk, M.

2006-01-01

This study deals with the performance characteristics of an R134a automotive air conditioning system capable of operating as an air-to-air heat pump using ambient air as a heat source. For this aim, an experimental analysis has been performed on a plant made up of original components from an automobile air conditioning system and some extra equipment employed to operate the system in the reverse direction. The system has been tested in the air conditioning and heat pump modes by varying the compressor speed and air temperatures at the inlets of the indoor and outdoor coils. Evaluation of the data gathered in steady state test runs has shown the effects of the operating conditions on the capacity, coefficient of performance, compressor discharge temperature and the rate of exergy destroyed by each component of the system for both operation modes. It has been observed that the heat pump operation provides adequate heating only in mild weather conditions, and the heating capacity drops sharply with decreasing outdoor temperature. However, compared with the air conditioning operation, the heat pump operation usually yields a higher coefficient of performance and a lower rate of exergy destruction per unit capacity. It is also possible to improve the heating mode performance of the system by redesigning the indoor coil, using another refrigerant with a higher heat rejection rate in the condenser and employing a better heat source such as the engine coolant or exhaust gases

Air Conditioning and Refrigeration. Book One.

Science.gov (United States)

Wantiez, Gary W.

Designed to provide students with the basic skills for an occupation in air conditioning and refrigeration, this curriculum guide includes seven major areas, each consisting of one or more units of instruction. These areas and their respective units are titled as follows: Orientation (history and development, and job opportunities), Safety…

Heating, Ventilation and Air-Conditioning Systems, Part of Indoor Air Quality Design Tools for Schools

Science.gov (United States)

The main purposes of a Heating, Ventilation, and Air-Conditioning system are to help maintain good indoor air quality through adequate ventilation with filtration and provide thermal comfort. HVAC systems are among the largest energy consumers in schools.

Potential Evaluation of Solar Heat Assisted Desiccant Hybrid Air Conditioning System

Science.gov (United States)

Tran, Thien Nha; Hamamoto, Yoshinori; Akisawa, Atsushi; Kashiwagi, Takao

The solar thermal driven desiccant dehumidification-absorption cooling hybrid system has superior advantage in hot-humid climate regions. The reasonable air processing of desiccant hybrid air conditioning system and the utility of clean and free energy make the system environment friendly and energy efficient. The study investigates the performance of the desiccant dehumidification air conditioning systems with solar thermal assistant. The investigation is performed for three cases which are combinations of solar thermal and absorption cooling systems with different heat supply temperature levels. Two solar thermal systems are used in the study: the flat plate collector (FPC) and the vacuum tube with compound parabolic concentrator (CPC). The single-effect and high energy efficient double-, triple-effect LiBr-water absorption cooling cycles are considered for cooling systems. COP of desiccant hybrid air conditioning systems are determined. The evaluation of these systems is subsequently performed. The single effect absorption cooling cycle combined with the flat plate collector solar system is found to be the most energy efficient air conditioning system.

A new optical concentrator design and analysis for rooftop solar applications

Science.gov (United States)

Zheng, Cheng; Li, Qiyuan; Rosengarten, Gary; Hawkes, Evatt; Taylor, Robert A.

2015-08-01

In this paper, a new type of linear focus, linear-tracking, catadioptric concentrator system is proposed and analysed for roof-integrated solar thermal applications. The optical concentrator designs have a focal distance of less than 10cm and are analysed using optical simulation software (Zemax). The results show that a relatively high concentration ratio (4.5 ~ 5.9 times) can be obtained and that the concentrators are capable of achieving an average optical efficiency around 66 - 69% during the middle 6 hours of a sunny day (i.e. a day with ~1000W/m2 global irradiance). Optical efficiency is analysed for perfect and non-ideal optical components to predict the collector performance under different `practical' circumstances. Overall, we intend for this paper to catalyse the development of rooftop solar thermal concentrators with compact form factors, similar to PV panels.

Data characteristic analysis of air conditioning load based on fast Fourier transform

Science.gov (United States)

Li, Min; Zhang, Yanchi; Xie, Da

2018-04-01

With the development of economy and the improvement of people's living standards, air conditioning equipment is more and more popular. The influence of air conditioning load for power grid is becoming more and more serious. In this context it is necessary to study the characteristics of air conditioning load. This paper analyzes the data of air conditioning power consumption in an office building. The data is used for Fast Fourier Transform by data analysis software. Then a series of maps are drawn for the transformed data. The characteristics of each map were analyzed separately. The hidden rules of these data are mined from the angle of frequency domain. And these rules are hard to find in the time domain.

Air-quality implications of widespread adoption of cool roofs on ozone and particulate matter in southern California

Science.gov (United States)

Ban-Weiss, G. A.; Lee, S. M.; Katzenstein, A. S.; Carreras-Sospedra, M.; Zhang, X.; Farina, S.; Vahmani, P.; Fine, P.; Epstein, S. A.

2017-12-01

The installation of roofing materials with increased solar reflectance (i.e., "cool roofs") can mitigate the urban heat island effect and reduce energy use. In addition, meteorological changes, along with the possibility of enhanced UV reflection from these surfaces, can have complex impacts on ozone and PM2.5 concentrations. We aim to evaluate the air-quality impacts of widespread cool-roof installations prescribed by building energy efficiency standards within the heavily populated and polluted South Coast Air Basin (SoCAB) in Southern California. Development of a comprehensive rooftop area database and evaluation of spectral reflectance measurements of roofing materials allows us to predict potential future changes in solar and UV reflectance for simulations using the Weather Research Forecast and Community Multiscale Air Quality (CMAQ) models. Meteorological simulations indicate a decrease in daily maximum temperatures, daily maximum boundary layer heights, and ventilation coefficients throughout the SoCAB upon widespread installation of cool roofs. CMAQ simulations show significant increases in PM2.5 concentrations and policy-relevant design values. Changes in 8-h ozone concentrations depend on the potential change in UV reflectance, ranging from a decrease in population-weighted concentrations when UV reflectance remains unchanged to an increase when changes in UV reflectance are at an upper bound. However, 8-h policy-relevant ozone design values increase in all cases. Although the other benefits of cool roofs could outweigh small air-quality penalties, UV reflectance standards for cool roofing materials could mitigate these negative consequences. Results of this study motivate the careful consideration of future rooftop and pavement solar reflectance modification policies.

Cooling energy efficiency and classroom air environment of a school building operated by the heat recovery air conditioning unit

International Nuclear Information System (INIS)

Wang, Yang; Zhao, Fu-Yun; Kuckelkorn, Jens; Liu, Di; Liu, Li-Qun; Pan, Xiao-Chuan

2014-01-01

The recently-built school buildings have adopted novel heat recovery ventilator and air conditioning system. Heat recovery efficiency of the heat recovery facility and energy conservation ratio of the air conditioning unit were analytically modeled, taking the ventilation networks into account. Following that, school classroom displacement ventilation and its thermal stratification and indoor air quality indicated by the CO 2 concentration have been numerically modeled concerning the effects of delivering ventilation flow rate and supplying air temperature. Numerical results indicate that the promotion of mechanical ventilation rate can simultaneously boost the dilution of indoor air pollutants and the non-uniformity of indoor thermal and pollutant distributions. Subsequent energy performance analysis demonstrates that classroom energy demands for ventilation and cooling could be reduced with the promotion of heat recovery efficiency of the ventilation facility, and the energy conservation ratio of the air conditioning unit decreases with the increasing temperatures of supplying air. Fitting correlations of heat recovery ventilation and cooling energy conservation have been presented. - Highlights: • Low energy school buildings and classroom environment. • Heat recovery facility operating with an air conditioning unit. • Displacement ventilation influenced by the heat recovery efficiency. • Energy conservation of cooling and ventilation through heat recovery. • Enhancement of classroom environment with reduction of school building energy

14 CFR 203.5 - Compliance as condition on operations in air transportation.

Science.gov (United States)

2010-01-01

... air transportation. 203.5 Section 203.5 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF... DEFENSES § 203.5 Compliance as condition on operations in air transportation. It shall be a condition on the authority of all direct U.S. and foreign carriers to operate in air transportation that they have...

Feedback linearization based control of a variable air volume air conditioning system for cooling applications.

Science.gov (United States)

Thosar, Archana; Patra, Amit; Bhattacharyya, Souvik

2008-07-01

Design of a nonlinear control system for a Variable Air Volume Air Conditioning (VAVAC) plant through feedback linearization is presented in this article. VAVAC systems attempt to reduce building energy consumption while maintaining the primary role of air conditioning. The temperature of the space is maintained at a constant level by establishing a balance between the cooling load generated in the space and the air supply delivered to meet the load. The dynamic model of a VAVAC plant is derived and formulated as a MIMO bilinear system. Feedback linearization is applied for decoupling and linearization of the nonlinear model. Simulation results for a laboratory scale plant are presented to demonstrate the potential of keeping comfort and maintaining energy optimal performance by this methodology. Results obtained with a conventional PI controller and a feedback linearizing controller are compared and the superiority of the proposed approach is clearly established.

Air conditioning with small power gas appliances

International Nuclear Information System (INIS)

Canci, Franco

1997-01-01

This article describes research and test activities on small power air conditioning appliances for residential use carried out in the United States, Japan and Europe. The absorption technology aims at the following objectives: to develop appliances requiring reduced maintenance and having a size comparable with electric units of the same output; to reduce production costs and therefore the final prince by adopting special manufacturing technologies such as welded plate exchangers; to obtain appliances which operate both in summer and winter ( as heat pumps), allowing to minimize management and installation costs in southern European climates. The final aim is to offer the customer one appliance only for the following purposes: hot water production for sanitary use, water refrigeration for summer air conditioning, hot water production production for winter heating. This kind of appliance should have management and maintenance costs similar to current individual boilers

Air-conditioning Australian households: The impact of dynamic peak pricing

International Nuclear Information System (INIS)

Strengers, Yolande

2010-01-01

International mandates for smart metering are enabling variable and real-time pricing regimes such as dynamic peak pricing (DPP), which charges 10-40 times the off-peak rate for electricity during short periods. This regime aims to reduce peak electricity demand (predominantly due to increase in residential air-conditioning usage) and curb greenhouse gas emissions. Although trials indicate that DPP can achieve significant demand reductions, particularly in summer, little is known about how or why households change their cooling practices in response to this strategy. This paper discusses the outcomes of a small qualitative study assessing the impact of a DPP trial on household cooling practices in the Australian state of New South Wales. The study challenges common assumptions about the necessity of air-conditioning and impact of price signals. It finds that DPP engages households as co-managers of their cooling practices through a series of notification signals (SMS, phone, in-home display, email, etc.). Further, by linking the price signal to air-conditioning, some householders consider this practice discretionary for short periods of time. The paper concludes by warning that policy makers and utilities may serve to legitimise air-conditioning usage and/or negate demand reductions by failing to acknowledge the non-rational dynamics of DPP and household cooling practices. - Research highlights: →Most householders consider air-conditioning discretionary during DPP events →DPP engages householders as co-managers of their demand →Notification of an upcoming DPP event is significant to the response →Householders feel obligated to respond to DPP for a range of non-financial reasons

An expert fault diagnosis system for vehicle air conditioning product development

NARCIS (Netherlands)

Tan, C.F.; Tee, B.T.; Khalil, S.N.; Chen, W.; Rauterberg, G.W.M.

2015-01-01

The paper describes the development of the vehicle air-conditioning fault diagnosis system in automotive industries with expert system shell. The main aim of the research is to diagnose the problem of new vehicle air-conditioning system development process and select the most suitable solution to

Open air-vapor compression refrigeration system for air conditioning and hot water cooled by cool water

International Nuclear Information System (INIS)

Hou Shaobo; Li Huacong; Zhang Hefei

2007-01-01

This paper presents an open air-vapor compression refrigeration system for air conditioning and hot water cooled by cool water and proves its feasibility through performance simulation. Pinch technology is used in analysis of heat exchange in the surface heat exchanger, and the temperature difference at the pinch point is selected as 6 o C. Its refrigeration depends mainly on both air and vapor, more efficient than a conventional air cycle, and the use of turbo-machinery makes this possible. This system could use the cool in the cool water, which could not be used to cool air directly. Also, the heat rejected from this system could be used to heat cool water to 33-40 o C. The sensitivity analysis of COP to η c and η t and the simulated results T 4 , T 7 , T 8 , q 1 , q 2 and W m of the cycle are given. The simulations show that the COP of this system depends mainly on T 7 , η c and η t and varies with T 3 or T wet and that this cycle is feasible in some regions, although the COP is sensitive to the efficiencies of the axial compressor and turbine. The optimum pressure ratio in this system could be lower, and this results in a fewer number of stages of the axial compressor. Adjusting the rotation speed of the axial compressor can easily control the pressure ratio, mass flow rate and the refrigerating capacity. The adoption of this cycle will make the air conditioned room more comfortable and reduce the initial investment cost because of the obtained very low temperature air. Humid air is a perfect working fluid for central air conditioning and no cost to the user. The system is more efficient because of using cool water to cool the air before the turbine. In addition, pinch technology is a good method to analyze the wet air heat exchange with water

Magnetic Refrigeration Technology for High Efficiency Air Conditioning

Energy Technology Data Exchange (ETDEWEB)

Boeder, A; Zimm, C

2006-09-30

Magnetic refrigeration was investigated as an efficient, environmentally friendly, flexible alternative to conventional residential vapor compression central air conditioning systems. Finite element analysis (FEA) models of advanced geometry active magnetic regenerator (AMR) beds were developed to minimize bed size and thus magnet mass by optimizing geometry for fluid flow and heat transfer and other losses. Conventional and magnetocaloric material (MCM) regenerator fabrication and assembly techniques were developed and advanced geometry passive regenerators were built and tested. A subscale engineering prototype (SEP) magnetic air conditioner was designed, constructed and tested. A model of the AMR cycle, combined with knowledge from passive regenerator experiments and FEA results, was used to design the regenerator beds. A 1.5 Tesla permanent magnet assembly was designed using FEA and the bed structure and plenum design was extensively optimized using FEA. The SEP is a flexible magnetic refrigeration platform, with individually instrumented beds and high flow rate and high frequency capability, although the current advanced regenerator geometry beds do not meet performance expectations, probably due to manufacturing and assembly tolerances. A model of the AMR cycle was used to optimize the design of a 3 ton capacity magnetic air conditioner, and the system design was iterated to minimize external parasitic losses such as heat exchanger pressure drop and fan power. The manufacturing cost for the entire air conditioning system was estimated, and while the estimated SEER efficiency is high, the magnetic air conditioning system is not cost competitive as currently configured. The 3 ton study results indicate that there are other applications where magnetic refrigeration is anticipated to have cost advantages over conventional systems, especially applications where magnetic refrigeration, through the use of its aqueous heat transfer fluid, could eliminate intermediate

Low-Flow Liquid Desiccant Air Conditioning: General Guidance and Site Considerations

Energy Technology Data Exchange (ETDEWEB)

Kozubal, E.; Herrmann, L.; Deru, M.; Clark, J.

2014-09-01

Dehumidification or latent cooling in buildings is an area of growing interest that has been identified as needing more research and improved technologies for higher performance. Heating, ventilating, and air-conditioning (HVAC) systems typically expend excessive energy by using overcool-and-reheat strategies to dehumidify buildings. These systems first overcool ventilation air to remove moisture and then reheat the air to meet comfort requirements. Another common strategy incorporates solid desiccant rotors that remove moisture from the air more efficiently; however, these systems increase fan energy consumption because of the high airside pressure drop of solid desiccant rotors and can add heat of absorption to the ventilation air. Alternatively, liquid desiccant air-conditioning (LDAC) technology provides an innovative dehumidification solution that: (1) eliminates the need for overcooling and reheating from traditional cooling systems; and (2) avoids the increased fan energy and air heating from solid desiccant rotor systems.

Smart Sensors Enable Smart Air Conditioning Control

Directory of Open Access Journals (Sweden)

Chin-Chi Cheng

2014-06-01

Full Text Available In this study, mobile phones, wearable devices, temperature and human motion detectors are integrated as smart sensors for enabling smart air conditioning control. Smart sensors obtain feedback, especially occupants’ information, from mobile phones and wearable devices placed on human body. The information can be used to adjust air conditioners in advance according to humans’ intentions, in so-called intention causing control. Experimental results show that the indoor temperature can be controlled accurately with errors of less than ±0.1 °C. Rapid cool down can be achieved within 2 min to the optimized indoor capacity after occupants enter a room. It’s also noted that within two-hour operation the total compressor output of the smart air conditioner is 48.4% less than that of the one using On-Off control. The smart air conditioner with wearable devices could detect the human temperature and activity during sleep to determine the sleeping state and adjusting the sleeping function flexibly. The sleeping function optimized by the smart air conditioner with wearable devices could reduce the energy consumption up to 46.9% and keep the human health. The presented smart air conditioner could provide a comfortable environment and achieve the goals of energy conservation and environmental protection.

The characteristics of welded joints for air conditioning application

Science.gov (United States)

Weglowski, M. St.; Weglowska, A.; Miara, D.; Kwiecinski, K.; Błacha, S.; Dworak, J.; Rykala, J.; Pikula, J.; Ziobro, G.; Szafron, A.; Zimierska-Nowak, P.; Richert, M.; Noga, P.

2017-10-01

In the paper the results of metallographic examination of welded joints for air-conditioning elements are presented. The European directives 2006/40/EC on the greenhouse gasses elimination demand to stop using traditional refrigerant and to change it to R744 (CO2) medium in air conditioning installation. The R744 refrigerant is environmental friendly medium if compared with standard solution such as R12, R134a or R1234yf and safer for passengers than R1234yf. The non-standard thermodynamic parameters of the R744 which translate into high pressure and high temperature require specific materials to develop the shape and to specify the technology of manufacturing for the particular elements of the conduits and moreover the technologies of joining for the whole structure, which would meet the exploitation requirements of the new air-conditioning system. To produce the test welded joints of stainless steels four different joining technologies were applied: laser welding, plasma welding, electron beam welding as well as high speed rotation welding. This paper describes the influence of the selected welding process on the macrostructure and microstructure of welded joints of AISI 304 and AISI 316L steels. The results indicated that plasma welding laser welding and electron beam welding technologies guaranty the proper quality of welded joints and can be used for the air conditioning application in automotive industry. However, high speed rotation welding not guarantee the good quality of welded joints and cannot be used for above application.

Intelligent energy management control of vehicle air conditioning system coupled with engine

International Nuclear Information System (INIS)

Khayyam, Hamid; Abawajy, Jemal; Jazar, Reza N.

2012-01-01

Vehicle Air Conditioning (AC) systems consist of an engine powered compressor activated by an electrical clutch. The AC system imposes an extra load to the vehicle's engine increasing the vehicle fuel consumption and emissions. Energy management control of the vehicle air conditioning is a nonlinear dynamic system, influenced by uncertain disturbances. In addition, the vehicle energy management control system interacts with different complex systems, such as engine, air conditioning system, environment, and driver, to deliver fuel consumption improvements. In this paper, we describe the energy management control of vehicle AC system coupled with vehicle engine through an intelligent control design. The Intelligent Energy Management Control (IEMC) system presented in this paper includes an intelligent algorithm which uses five exterior units and three integrated fuzzy controllers to produce desirable internal temperature and air quality, improved fuel consumption, low emission, and smooth driving. The three fuzzy controllers include: (i) a fuzzy cruise controller to adapt vehicle cruise speed via prediction of the road ahead using a Look-Ahead system, (ii) a fuzzy air conditioning controller to produce desirable temperature and air quality inside vehicle cabin room via a road information system, and (iii) a fuzzy engine controller to generate the required engine torque to move the vehicle smoothly on the road. We optimised the integrated operation of the air conditioning and the engine under various driving patterns and performed three simulations. Results show that the proposed IEMC system developed based on Fuzzy Air Conditioning Controller with Look-Ahead (FAC-LA) method is a more efficient controller for vehicle air conditioning system than the previously developed Coordinated Energy Management Systems (CEMS). - Highlights: ► AC interacts: vehicle, environment, driver components, and the interrelationships between them. ► Intelligent AC algorithm which uses

Contribution of air conditioning adoption to future energy use under global warming

Science.gov (United States)

Davis, Lucas W.; Gertler, Paul J.

2015-01-01

As household incomes rise around the world and global temperatures go up, the use of air conditioning is poised to increase dramatically. Air conditioning growth is expected to be particularly strong in middle-income countries, but direct empirical evidence is scarce. In this paper we use high-quality microdata from Mexico to describe the relationship between temperature, income, and air conditioning. We describe both how electricity consumption increases with temperature given current levels of air conditioning, and how climate and income drive air conditioning adoption decisions. We then combine these estimates with predicted end-of-century temperature changes to forecast future energy consumption. Under conservative assumptions about household income, our model predicts near-universal saturation of air conditioning in all warm areas within just a few decades. Temperature increases contribute to this surge in adoption, but income growth by itself explains most of the increase. What this will mean for electricity consumption and carbon dioxide emissions depends on the pace of technological change. Continued advances in energy efficiency or the development of new cooling technologies could reduce the energy consumption impacts. Similarly, growth in low-carbon electricity generation could mitigate the increases in carbon dioxide emissions. However, the paper illustrates the enormous potential impacts in this sector, highlighting the importance of future research on adaptation and underscoring the urgent need for global action on climate change. PMID:25918391

Contribution of air conditioning adoption to future energy use under global warming.

Science.gov (United States)

Davis, Lucas W; Gertler, Paul J

2015-05-12

As household incomes rise around the world and global temperatures go up, the use of air conditioning is poised to increase dramatically. Air conditioning growth is expected to be particularly strong in middle-income countries, but direct empirical evidence is scarce. In this paper we use high-quality microdata from Mexico to describe the relationship between temperature, income, and air conditioning. We describe both how electricity consumption increases with temperature given current levels of air conditioning, and how climate and income drive air conditioning adoption decisions. We then combine these estimates with predicted end-of-century temperature changes to forecast future energy consumption. Under conservative assumptions about household income, our model predicts near-universal saturation of air conditioning in all warm areas within just a few decades. Temperature increases contribute to this surge in adoption, but income growth by itself explains most of the increase. What this will mean for electricity consumption and carbon dioxide emissions depends on the pace of technological change. Continued advances in energy efficiency or the development of new cooling technologies could reduce the energy consumption impacts. Similarly, growth in low-carbon electricity generation could mitigate the increases in carbon dioxide emissions. However, the paper illustrates the enormous potential impacts in this sector, highlighting the importance of future research on adaptation and underscoring the urgent need for global action on climate change.

Air-water flow measurement for ERVC conditions by LIF/PIV

International Nuclear Information System (INIS)

Yoon, Jong Woong; Jeong, Yong Hoon

2016-01-01

Critical heat flux (CHF) of the external reactor vessel wall is a safety limit that indicate the integrity of the reactor vessel during the situation. Many research conducted CHF experiments in the IVR-ERVC conditions. However, the flow velocity field which is an important factor in the CHF mechanism were not studied enough in the IVR-ERVC situations. In this study, flow measurements including velocity vector field and the liquid velocity in the IVR-ERVC conditions were studied. The air-water two phase flow loop simulating IVRERVC conditions was set up and liquid velocity field was measured by LIF/PIV technique in this study. The experiment was conducted with and without air injection conditions. For the air-water flow experiment, liquid velocity at the outside of two phase boundary layer became higher and the two phase boundary layer thickness became smaller when the mass flux increases. The velocity data obtained in this study are expected to improve the CHF correlation in the IVR-ERVC situations.

Air-water flow measurement for ERVC conditions by LIF/PIV

Energy Technology Data Exchange (ETDEWEB)

Yoon, Jong Woong; Jeong, Yong Hoon [KAIST, Daejeon (Korea, Republic of)

2016-05-15

Critical heat flux (CHF) of the external reactor vessel wall is a safety limit that indicate the integrity of the reactor vessel during the situation. Many research conducted CHF experiments in the IVR-ERVC conditions. However, the flow velocity field which is an important factor in the CHF mechanism were not studied enough in the IVR-ERVC situations. In this study, flow measurements including velocity vector field and the liquid velocity in the IVR-ERVC conditions were studied. The air-water two phase flow loop simulating IVRERVC conditions was set up and liquid velocity field was measured by LIF/PIV technique in this study. The experiment was conducted with and without air injection conditions. For the air-water flow experiment, liquid velocity at the outside of two phase boundary layer became higher and the two phase boundary layer thickness became smaller when the mass flux increases. The velocity data obtained in this study are expected to improve the CHF correlation in the IVR-ERVC situations.

Calculation of the Chilling Requirement for Air Conditioning in the Excavation Roadway

Directory of Open Access Journals (Sweden)

Yueping Qin

2015-10-01

Full Text Available To effectively improve the climate conditions of the excavation roadway in coal mine, the calculation of the chilling requirement taking air conditioning measures is extremely necessary. The temperature field of the surrounding rock with moving boundary in the excavation roadway was numerically simulated by using finite volume method. The unstable heat transfer coefficient between the surrounding rock and air flow was obtained via the previous calculation. According to the coupling effects of the air flow inside and outside air duct, the differential calculation mathematical model of air flow temperature in the excavation roadway was established. The chilling requirement was calculated with the selfdeveloped computer program for forecasting the required cooling capacity of the excavation roadway. A good air conditioning effect had been observed after applying the calculated results to field trial, which indicated that the prediction method and calculation procedure were reliable.

10 CFR 71.74 - Accident conditions for air transport of plutonium.

Science.gov (United States)

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Accident conditions for air transport of plutonium. 71.74 Section 71.74 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) PACKAGING AND TRANSPORTATION OF RADIOACTIVE MATERIAL Package, Special Form, and LSA-III Tests 2 § 71.74 Accident conditions for air transport of...

A Pilot Study of the Effectiveness of Indoor Plants for Removal of Volatile Organic Compounds in Indoor Air in a Seven-Story Office Building

Energy Technology Data Exchange (ETDEWEB)

Apte, Michael G.; Apte, Joshua S.

2010-04-27

The Paharpur Business Centre and Software Technology Incubator Park (PBC) is a 7 story, 50,400 ft{sup 2} office building located near Nehru Place in New Delhi India. The occupancy of the building at full normal operations is about 500 people. The building management philosophy embodies innovation in energy efficiency while providing full service and a comfortable, safe, healthy environment to the occupants. Provision of excellent Indoor Air Quality (IAQ) is an expressed goal of the facility, and the management has gone to great lengths to achieve it. This is particularly challenging in New Delhi, where ambient urban pollution levels rank among the worst on the planet. The approach to provide good IAQ in the building includes a range of technical elements: air washing and filtration of ventilation intake air from rooftop air handler, the use of an enclosed rooftop greenhouse with a high density of potted plants as a bio-filtration system, dedicated secondary HVAC/air handling units on each floor with re-circulating high efficiency filtration and UVC treatment of the heat exchanger coils, additional potted plants for bio-filtration on each floor, and a final exhaust via the restrooms located at each floor. The conditioned building exhaust air is passed through an energy recovery wheel and chemisorbent cartridge, transferring some heat to the incoming air to increase the HVAC energy efficiency. The management uses 'green' cleaning products exclusively in the building. Flooring is a combination of stone, tile and 'zero VOC' carpeting. Wood trim and finish appears to be primarily of solid sawn materials, with very little evidence of composite wood products. Furniture is likewise in large proportion constructed from solid wood materials. The overall impression is that of a very clean and well-kept facility. Surfaces are polished to a high sheen, probably with wax products. There was an odor of urinal cake in the restrooms. Smoking is not allowed in

Analysis on a hybrid desiccant air-conditioning system

International Nuclear Information System (INIS)

Jia, C.X.; Dai, Y.J.; Wu, J.Y.; Wang, R.Z.

2006-01-01

Hybrid desiccant-assisted preconditioner and split cooling coil system, which combines the merits of moisture removal by desiccant and cooling coil for sensible heat removal, is a potential alternative to conventional vapor compression cooling systems. In this paper, experiments on a hybrid desiccant air-conditioning system, which is actually an integration of a rotary solid desiccant dehumidification and a vapor compression air-conditioning unit, had been carried out. It is found that, compared with the conventional VC (vapor compression) system, the hybrid desiccant cooling system economizes 37.5% electricity powers when the process air temperature and relative humidity are maintained at 30 o C, and 55% respectively. The reason why the hybrid desiccant cooling system features better performance relative to the VC system lies in the improvement brought about in the performance of the evaporator in VC unit due to desiccant dehumidification. A thermodynamic model of the hybrid desiccant system with R-22 as the refrigerant has been developed and the impact of operating parameters on the sensible heat ratio of the evaporator and the electric power saving rate has been analyzed. It is found that a majority of evaporators can operate in the dry condition even if the regeneration temperature is lower (i.e. 80 o C)

Human requirements in future air-conditioned environments

DEFF Research Database (Denmark)

Fanger, Povl Ole

1999-01-01

Although air-conditioning has played a positive role for economic development in warm climates, its image is globally mixed. Field studies demonstrate that there are substantial numbers of dissatisfied people in many buildings, among them those suffering from Sick Building Syndrome (SBS) symptoms...

Human requirements in future air-conditioned environments

DEFF Research Database (Denmark)

Fanger, Povl Ole

2001-01-01

Although air-conditioning has played a positive role for economic development in warm climates, its image is globally mixed. Field studies demonstrate that there are substantial numbers of dissatisfied people in many buildings, among them those suffering from Sick Building Syndrome (SBS) symptoms...

Does the air condition system in busses spread allergic fungi into driver space?

Science.gov (United States)

Sowiak, Małgorzata; Kozajda, Anna; Jeżak, Karolina; Szadkowska-Stańczyk, Irena

2018-02-01

The aim of this study was to establish whether the air-conditioning system in buses constitutes an additional source of indoor air contamination with fungi, and whether or not the fungi concentration depends on the period from the last disinfection of the system, combined with replacement of the cabin dust particle filter. The air samples to fungi analysis using impact method were taken in 30 buses (20 with an air-conditioning system, ACS; 10 with a ventilation system, VS) in two series: 1 and 22 weeks after cabin filter replacement and disinfection of the air-conditioning system. During one test in each bus were taken two samples: before the air-conditioning or ventilation system switched on and 6 min after operating of these systems. The atmospheric air was the external background (EB). After 1 week of use of the system, the fungi concentrations before starting of the ACS and VS system were 527.8 and 1053.0 cfu/m 3 , respectively, and after 22 weeks the concentrations were 351.9 and 1069.6 cfu/m 3 , respectively. While in the sample after 6 min of ACS and VS system operating, the fungi concentration after 1 week of use was 127.6 and 233.7 cfu/m 3 , respectively, and after 22 weeks it was 113.3 and 324.9 cfu/m 3 , respectively. Results do not provide strong evidence that air-conditioning system is an additional source of indoor air contamination with fungi. A longer operation of the system promoted increase of fungi concentration in air-conditioned buses only.

Duct corrosion in the ventilating air conditioning system for Main Control Room

International Nuclear Information System (INIS)

Yamada, Kohei; Kobayashi, Takashi; Minami, Akiko; Fukuba, Kazushi

2014-01-01

Higashidori Nuclear Power Station, start-of-operation in December 2005, is a relatively new plant. We decided to get original data of air duct condition to determine maintenance policy of air duct, because planned maintenance of air duct has never been done and the corrosion of air duct has occurred in other plant. In January 2014, we found a corrosion-hole at the downstream of the inlet damper in the ventilating air conditioning system for Main Control Room (MCR). We supposed that the cause of rapid corrosion is related to the characteristic environment of this site. (author)

Air conditioning device for pool facilities in nuclear power plant buildings

International Nuclear Information System (INIS)

Taruishi, Yoshiaki; Ishida, Seiji.

1981-01-01

Purpose: To improve the temperature and humidity conditions for the working circumstance, prevent condensations on the wall surface and enable the reduction in the irradiation exposure to workers. Constitution: Air intake ports are provided on the side wall of a fuel storage pool or an equipment installation pool above the water level and connected by way of their exhaust ducts to the exhaust ducts of an air ventilation system. While on the other hand, air feed ducts having horizontally opened blowing ports and air exhaust ducts having horizontally opened exhaust ports above and in adjacent to the air feed ducts are provided on the side walls of the pool buildings at the height near the floor level. With this structure, fresh outdoor airs blown out horizontally from the blowing ports provided near the floor level can improve the temperature and humidity conditions of the working circumstance for the workers working on the floor. Further, an air clean up device is provided to the feed and exhaust systems for clean up the feed and exhaust airs. (Furukawa, Y.)

Report of study 7.3: cooling and air conditioning

Energy Technology Data Exchange (ETDEWEB)

Russo, F.

2000-07-01

This report describes the results of the study carried out by the study group 7.3 in the triennium 1997-2000. The study was focused on industrial refrigeration and air conditioning for the large building utilising natural gas. The goal of this study, carried out in collaboration of the members of study group 7.3, was to analyse the markets of industrial refrigeration and air conditioning for large buildings to identify possibilities to increase the natural gas share in these sectors. The available technology in the two sectors of the market are described in a single section, i.e. the 'State of the art of the technology'. In this section, technical characteristics, applications, performances, new developments and others topics are discussed for absorbers, gas engines, gas turbines and fuel cells. In the 'Industrial Refrigeration' section an analysis of the present global market for the industrial sector is presented. Economics, advantages and barriers to gas units compared with the electrical units are discussed. Information on existing industrial plants, possible application options and new technology developments are described as well. The 'Air conditioning for the large building' section deals with offices, hotels, commercial buildings, hospitals and shopping centres with a cooling capacity of 350 kW or higher. It appears that the use of natural gas for cooling of large buildings has been increasing during the last decade, thanks to the greater availability of natural gas and the development of new technologies. A marketing survey of gas air-conditioning was carried out in cooperation with a group of Intergas Marketing. Based on the survey, the report describes the market position of natural gas relative to electricity. It provides the strategic prospects for further developing natural gas as a competitive option for air-conditioning of large buildings using a combination of state-of-the-art technologies. It is important to highlight

Human requirements in future air-conditioned environments

DEFF Research Database (Denmark)

Fanger, Povl Ole

2002-01-01

Air-conditioning of buildings has played a very positive role for economic development in warm climates. Still its image is globally mixed. Field studies demonstrate that there are substantial numbers of dissatisfied people in many buildings, among them those suffering from SBS symptoms, even...

Design of Air Conditioning Automation for Patisserie Shopwindow

OpenAIRE

Kemal Tutuncu; Recai Ozcan

2013-01-01

Having done in this study, air-conditioning automation for patisserie shopwindow was designed. In the cooling sector it is quite important to cooling up the air temperature in the shopwindow within short time interval. Otherwise the patisseries inside of the shopwindow will be spoilt in a few days. Additionally the humidity is other important parameter for the patisseries kept in shopwindow. It must be raised up to desired level in a quite short time. Traditional patisser...

Analysis and simulation of mobile air conditioning system coupled with engine cooling system

International Nuclear Information System (INIS)

Qi, Zhao-gang; Chen, Jiang-ping; Chen, Zhi-jiu

2007-01-01

Many components of the mobile air conditioning system and engine cooling system are closely interrelated and make up the vehicle climate control system. In the present paper, a vehicle climate control system model including air conditioning system and engine cooling system has been proposed under different operational conditions. All the components have been modeled on the basis of experimental data. Based on the commercial software, a computer simulation procedure of the vehicle climate control system has been developed. The performance of the vehicle climate control system is simulated, and the calculational data have good agreement with experimental data. Furthermore, the vehicle climate control simulation results have been compared with an individual air conditioning system and engine cooling system. The influences between the mobile air conditioning system and the engine cooling system are discussed

THERMAL COMFORT STUDY OF AN AIR-CONDITIONED DESIGN STUDIO IN TROPICAL SURABAYA

OpenAIRE

Agus Dwi Hariyanto

2005-01-01

This paper evaluates the current thermal comfort condition in an air-conditioned design studio using objective measurement and subjective assessment. Objective measurement is mainly to quantify the air temperature, MRT, relative humidity, and air velocity. Subjective assessment is conducted using a questionnaire to determine the occupants thermal comfort sensations and investigate their perception of the thermal comfort level. A design studio in an academic institution in Surabaya was chosen ...

FY1999 Meeting of The Society of Heating, Air-Conditioning and Sanitary Engineering of Japan. Air conditioning systems for various facilities; 1999 nendo gakujutsu koenkai gaiyo. Kakushu shisetsu kucho system

Energy Technology Data Exchange (ETDEWEB)

Iwamoto, K. [Takenaka Corp., Osaka (Japan)

1999-12-05

B-49 reported the outline of an artificial weather room composed of one inner room and two outer rooms, and its temperature change and temperature profiles during air conditioning. The room is scheduled to be used for evaluation of air conditioning systems, thermal performance evaluation of building materials and study on ventilation efficiency. B-50 reported the seasonal measurement results on thermal environment, and cooling and heating use patterns of living rooms and common spaces of 4 welfare homes for aged persons, and showed that room temperature difference in winter should be considered. Measurement data on facilities with floor heating were required. B-51 reported the experiment and numerical analysis results on thermal environment, draft sensation, condensation and radiation effect of patient bedrooms by using a full-scale 4-bed room model with a specific outlet developed for patient bedroom air conditioning. B-52 reported the outline of an air conditioning system for vegetable factories, and its performance evaluation result during cooling. The effect of blackout curtains and local air conditioning was reported. B-53 reported the comparison study result on air conditioning for animal breeding rooms by full-scale model experiment and numerical analysis. The line outlet + hanging wall + rack back exhaust system was most favorable from the viewpoint of temperature profile and prevention of pollutants from diffusion. (translated by NEDO)

Analysis of Direct Outdoor Air Cooling Efficency for Combined Variable Air Volume Air-conditioning System in Stores in Cold Climates of China

OpenAIRE

Luo, Zhiwen

2006-01-01

Direct outdoor air cooling contributes a lot not only to the improvement of the indoor air quality but also to the energy saving. Its full use will reduce the water chiller’s running time especially in some stores where cooling load keeps much higher and longer than that in other buildings. A novel air-conditioning system named Combined Variable Air Volume system (CVAV), combining a normal AHU with a separate outdoor air supply system, was proposed firstly by the authors. The most attractive ...

Energy impact of indoor environmental policy for air-conditioned offices of Hong Kong

International Nuclear Information System (INIS)

Wong, L.T.; Mui, K.W.; Shi, K.L.

2008-01-01

Air-conditioned office buildings are one of the biggest energy consumers of electricity in developed cities in the subtropical climate regions. A good energy policy for the indoor environment should respond to both the needs of energy conservation and the needs for a desirable indoor healthy environment with a reduction in carbon dioxide (CO 2 ) generation. This study evaluates energy implications and the corresponding CO 2 generation of some indoor environmental policies for air-conditioned office buildings in the subtropical climate. In particular, the thermal energy consumption in an air-conditioned office building was evaluated by the heat gains through the building fabric, the transport of outdoor fresh air for ventilation, and the heat generated by the occupant and equipment in the space. With the Monte-Carlo sampling technique and the parameters from the existing office building stocks of Hong Kong, the energy consumption profiles of air-conditioned office buildings in Hong Kong were evaluated. Energy consumption profiles were simulated for certain indoor environmental quality (IEQ) policies on indoor air temperature and CO 2 concentration settings in the offices, with other building parameters remaining unchanged. The impact assessment and the regression models described in this study may be useful for evaluation of energy performances of IEQ policies. They will also be useful for the promotion of energy-saving measures in air-conditioned office buildings in Hong Kong. This study presented a useful source of references for policymakers, building professionals and end users to quantify the energy and environmental impacts due to an IEQ policy for air-conditioned office buildings

Uncertainty Model for Total Solar Irradiance Estimation on Australian Rooftops

Science.gov (United States)

Al-Saadi, Hassan; Zivanovic, Rastko; Al-Sarawi, Said

2017-11-01

The installations of solar panels on Australian rooftops have been in rise for the last few years, especially in the urban areas. This motivates academic researchers, distribution network operators and engineers to accurately address the level of uncertainty resulting from grid-connected solar panels. The main source of uncertainty is the intermittent nature of radiation, therefore, this paper presents a new model to estimate the total radiation incident on a tilted solar panel. Where a probability distribution factorizes clearness index, the model is driven upon clearness index with special attention being paid for Australia with the utilization of best-fit-correlation for diffuse fraction. The assessment of the model validity is achieved with the adoption of four goodness-of-fit techniques. In addition, the Quasi Monte Carlo and sparse grid methods are used as sampling and uncertainty computation tools, respectively. High resolution data resolution of solar irradiations for Adelaide city were used for this assessment, with an outcome indicating a satisfactory agreement between actual data variation and model.

History of ventilation and of air conditioning in Dolni Rozinka uranium mines

International Nuclear Information System (INIS)

Voltr, S.

1987-01-01

At a time of the start of mining operations in the Dolni Rozinka uranium mine, ventilation had been provided using the underpressure technique with diagonal winding shafts. From 1967 the overpressure system had been used. The system is described in detail and its constraints are listed. In 1983, on the basis of an analysis and model tests, the ventilation system was replaced by a underpressure system which satisfied the current hygiene specifications, was costsaving and reliable. Since 1985, an air conditioning system has been in operation featuring mobile cooling units and a closed-circuit air conditioning water system that is separated from the mining water pumping system. In view of the favourable temperature factors of the deposit, the mobile air conditioning units are only installed in blind headings. When the through-flow wind stream is achieved, air conditioning is abandoned. (J.B.). 2 figs., 5 refs

Capability of air filters to retain airborne bacteria and molds in heating, ventilating and air-conditioning (HVAC) systems.

Science.gov (United States)

Möritz, M; Peters, H; Nipko, B; Rüden, H

2001-07-01

The capability of air filters (filterclass: F6, F7) to retain airborne outdoor microorganisms was examined in field experiments in two heating, ventilating and air conditioning (HVAC) systems. At the beginning of the 15-month investigation period, the first filter stages of both HVAC systems were equipped with new unused air filters. The number of airborne bacteria and molds before and behind the filters were determined simultaneously in 14 days-intervals using 6-stage Andersen cascade impactors. Under relatively dry ( 12 degrees C) outdoor air conditions air filters led to a marked reduction of airborne microorganism concentrations (bacteria by approximately 70% and molds by > 80%). However, during long periods of high relative humidity (> 80% R. H.) a proliferation of bacteria on air filters with subsequent release into the filtered air occurred. These microorganisms were mainly smaller than 1.1 microns therefore being part of the respirable fraction. The results showed furthermore that one possibility to avoid microbial proliferation is to limit the relative humidity in the area of the air filters to 80% R. H. (mean of 3 days), e.g. by using preheaters in front of air filters in HVAC-systems.

Load Distribution of Semi-Central Evaporative Cooling Air-Conditioning System Based on the TRNSYS Platform

Directory of Open Access Journals (Sweden)

Ji Li

2018-05-01

Full Text Available Evaporative cooling is a green, energy-efficient cooling technology adopted in hot and dry regions, which has wider application in the field of air-conditioning systems. Outdoor meteorological parameters have a great influence on the operation mode and control strategy of evaporative cooling air-conditioning systems, and the system load distribution and system configuration will be affected. This paper aims at investigating the load distribution of semi-central evaporative cooling air-conditioning systems under the condition of hourly outdoor meteorological parameters. Firstly, this paper introduced the design partition, operation mode, controlling strategy and load distribution method on semi-central evaporative cooling air-conditioning system. Then, taking an office building in Lanzhou (China as an example, the evaporative cooling air-conditioning system was divided into five regions and the load distribution was simulated by TRNSYS (The Transient Energy System Simulation Tool under the condition of hourly outdoor meteorological parameters. Finally, the results have shown that the evaporative cooling air-conditioning system can provide 25.46% of the building loads, which was of great significance to reduce the energy consumption of air-conditioning system.

Air conditioning system

Science.gov (United States)

Lowenstein, Andrew; Miller, Jeffrey; Gruendeman, Peter; DaSilva, Michael

2005-02-01

An air conditioner comprises a plurality of plates arranged in a successively stacked configuration with portions thereof having a spaced apart arrangement, and defining between successive adjacent pairs of plates at the spaced apart portions a first and second series of discrete alternating passages wherein a first air stream is passed through the first series of passages and a second air stream is passed through the second series of passages; and said stacked configuration of plates forming integrally therewith a liquid delivery means for delivering from a source a sufficient quantity of a liquid to the inside surfaces of the first series of fluid passages in a manner which provides a continuous flow of the liquid from a first end to a second end of the plurality of plates while in contact with the first air stream.

Cleaning and air conditioning device for atmosphere in thermonuclear reactor chamber

International Nuclear Information System (INIS)

Ishida, Seiji.

1993-01-01

The device of the present invention removes tritium efficiently and attains ventilation and conditioning of a great amount of air flow. That is, there are disposed a humidity separator, a filter, a heater, a catalyst filled layer, a water jetting type humidifying heat insulation cooler and a cooler in this order from an inlet side (upstream) of contaminated room atmospheric gases. The catalyst filled layer, etc. are incorporated integrally into the ventilation air conditioning facility for ventilating air in the chamber of the thermonuclear reactor, to clean a tritium atmosphere at the same time. Accordingly, the device is made compact as a whole. A limit for the air flow rate owing to the use of the conventional catalyst tower and adsorbing tower is eliminated. Then a ventilating air conditioning for a great flow rate can be attained. Tritium is removed by cooling and dehumidification without using any adsorbent. Accordingly, an adsorbing tower is no more necessary and conventional regeneration operation is not required. As a result, space for installation is reduced, the system is simplified and the cost for construction and facility can be reduced. (I.S.)

Thermal comfort in air-conditioned mosques in the dry desert climate

Energy Technology Data Exchange (ETDEWEB)

Al-ajmi, Farraj F. [Department of Civil Engineering, College of Technological Studies, Shuwaikh 70654 (Kuwait)

2010-11-15

In Kuwait, as in most countries with a typical dry desert climate, the summer season is long with a mean daily maximum temperature of 45 C. Centralized air-conditioning, which is generally deployed from the beginning of April to the end of October, can have tremendous impact on the amount of electrical energy utilized to mechanically control the internal environment in mosque buildings. The indoor air temperature settings for all types of air-conditioned buildings and mosque buildings in particular, are often calculated based on the analytical model of ASHRAE 55-2004 and ISO 7730. However, a field study was conducted in six air-conditioned mosque buildings during the summers of 2007 to investigate indoor climate and prayers thermal comfort in state of Kuwait. The paper presents statistical data about the indoor environmental conditions in Kuwait mosque buildings, together with an analysis of prayer thermal comfort sensations for a total of 140 subjects providing 140 sets of physical measurements and subjective questionnaires were used to collect data. Results show that the neutral temperature (T{sub n}) of the prayers is found to be 26.1 C, while that for PMV is 23.3 C. Discrepancy of these values is in fact about 2.8 C higher than those predicted by PMV model. Therefore, thermal comfort temperature in Kuwait cannot directly correlate with ISO 7730 and ASHRAE 55-2004 standards. Findings from this study should be considered when designing air conditioning for mosque buildings. This knowledge can contribute towards the development of future energy-related design codes for Kuwait. (author)

Temperature and Humidity Control in Air-Conditioned Buildings with lower Energy Demand and increased Indoor Air Quality

DEFF Research Database (Denmark)

Paul, Joachim; Martos, E. T.

2003-01-01

Air-conditioning is not only a matter of temperature control. Thermal comfort and good indoor air quality are mainly a matter of humidity. Human health and well being may suffer seriously from inadequate humidity and/or too low temperatures in a room. A case study involving supermarket air......%. For indoor air temperature and humidity control, the use of an ice slurry (´Binary Ice´)was compared to conventional chilled water. The use of Binary Ice instead of chilled water makes the air handling and air distribution installation much simpler, recirculation of air becomes obsolete, and a higher portion...... of ambient air can be supplied, thus improving the indoor air quality still further. Reheating of air is not necessary when using Binary Ice. The introduction of chilled air into a room requires a different type of air outlet, however. When using Binary Ice, energy savings are high for climates with low...

Sensory evaluation of heating and air conditioning systems

Energy Technology Data Exchange (ETDEWEB)

Evin, F.; Siekierski, E. [Electricite de France, Research and Development Division, Les Renardieres, Moret Sur Loing (France)

2002-07-01

Existing standards and models, such as ISO 7730 or the work of Fanger [Thermal Comfort], are not sufficient to characterise the satisfaction and pleasantness of end-users provided by heating or air conditioning systems. For this reason Electricite de France (EDF) has initiated a project with the aim of using sensory evaluation techniques in the design of HVAC systems. Sensory evaluation has been used for more than 30 years in the food industry, and now involves the cosmetics, the phone and the automotive industries. It is based on a dual evaluation: sensation measurements carried out by a small panel of trained expert assessors; preference studies performed by a large panel of representative consumers. A correlation between the data of both studies is then used to explain the preferences in terms of sensations (preference mapping). The first experiments performed in 1999 and 2000 have provided lists of descriptors of thermal sensation and acoustic sensation associated with heating and air conditioning appliances. They show that it is possible to define discriminative descriptors, to train a panel and to reliably quantify these descriptors. It is then possible to draw the sensory profiles of different heating, ventilation and air conditioning (HVAC) systems. The future experimental laboratory that EDF has decided to build is also presented, where the trained panels and end-users will evaluate the sensations and the preferences of real systems in eight 'realistic environmental chambers' designed, furnished and decorated like offices and flats. (author)

MODELS OF AIR TRAFFIC CONTROLLERS ERRORS PREVENTION IN TERMINAL CONTROL AREAS UNDER UNCERTAINTY CONDITIONS

Directory of Open Access Journals (Sweden)

Volodymyr Kharchenko

2017-03-01

Full Text Available Purpose: the aim of this study is to research applied models of air traffic controllers’ errors prevention in terminal control areas (TMA under uncertainty conditions. In this work the theoretical framework descripting safety events and errors of air traffic controllers connected with the operations in TMA is proposed. Methods: optimisation of terminal control area formal description based on the Threat and Error management model and the TMA network model of air traffic flows. Results: the human factors variables associated with safety events in work of air traffic controllers under uncertainty conditions were obtained. The Threat and Error management model application principles to air traffic controller operations and the TMA network model of air traffic flows were proposed. Discussion: Information processing context for preventing air traffic controller errors, examples of threats in work of air traffic controllers, which are relevant for TMA operations under uncertainty conditions.

Ice Storage Air-Conditioning System Simulation with Dynamic Electricity Pricing: A Demand Response Study

Directory of Open Access Journals (Sweden)

Chi-Chun Lo

2016-02-01

Full Text Available This paper presents an optimal dispatch model of an ice storage air-conditioning system for participants to quickly and accurately perform energy saving and demand response, and to avoid the over contact with electricity price peak. The schedule planning for an ice storage air-conditioning system of demand response is mainly to transfer energy consumption from the peak load to the partial-peak or off-peak load. Least Squares Regression (LSR is used to obtain the polynomial function for the cooling capacity and the cost of power consumption with a real ice storage air-conditioning system. Based on the dynamic electricity pricing, the requirements of cooling loads, and all technical constraints, the dispatch model of the ice-storage air-conditioning system is formulated to minimize the operation cost. The Improved Ripple Bee Swarm Optimization (IRBSO algorithm is proposed to solve the dispatch model of the ice storage air-conditioning system in a daily schedule on summer. Simulation results indicate that reasonable solutions provide a practical and flexible framework allowing the demand response of ice storage air-conditioning systems to demonstrate the optimization of its energy savings and operational efficiency and offering greater energy efficiency.

A robust model predictive control strategy for improving the control performance of air-conditioning systems

International Nuclear Information System (INIS)

Huang Gongsheng; Wang Shengwei; Xu Xinhua

2009-01-01

This paper presents a robust model predictive control strategy for improving the supply air temperature control of air-handling units by dealing with the associated uncertainties and constraints directly. This strategy uses a first-order plus time-delay model with uncertain time-delay and system gain to describe air-conditioning process of an air-handling unit usually operating at various weather conditions. The uncertainties of the time-delay and system gain, which imply the nonlinearities and the variable dynamic characteristics, are formulated using an uncertainty polytope. Based on this uncertainty formulation, an offline LMI-based robust model predictive control algorithm is employed to design a robust controller for air-handling units which can guarantee a good robustness subject to uncertainties and constraints. The proposed robust strategy is evaluated in a dynamic simulation environment of a variable air volume air-conditioning system in various operation conditions by comparing with a conventional PI control strategy. The robustness analysis of both strategies under different weather conditions is also presented.

Air-side performance of a micro-channel heat exchanger in wet surface conditions

Directory of Open Access Journals (Sweden)

Srisomba Raviwat

2017-01-01

Full Text Available The effects of operating conditions on the air-side heat transfer, and pressure drop of a micro-channel heat exchanger under wet surface conditions were studied experimentally. The test section was an aluminum micro-channel heat exchanger, consisting of a multi-louvered fin and multi-port mini-channels. Experiments were conducted to study the effects of inlet relative humidity, air frontal velocity, air inlet temperature, and refrigerant temperature on air-side performance. The experimental data were analyzed using the mean enthalpy difference method. The test run was performed at relative air humidities ranging between 45% and 80%; air inlet temperature ranges of 27, 30, and 33°C; refrigerant-saturated temperatures ranging from 18 to 22°C; and Reynolds numbers between 128 and 166. The results show that the inlet relative humidity, air inlet temperature, and the refrigerant temperature had significant effects on heat transfer performance and air-side pressure drop. The heat transfer coefficient and pressure drop for the micro-channel heat exchanger under wet surface conditions are proposed in terms of the Colburn j factor and Fanning f factor.

Numerical Analysis of Exergy for Air-Conditioning Influenced by Ambient Temperature

Directory of Open Access Journals (Sweden)

Jing-Nang Lee

2014-07-01

Full Text Available The article presents numerical analysis of exergy for air-conditioning influenced by ambient temperature. The model of numerical simulation uses an integrated air conditioning system exposed in varied ambient temperature to observe change of the four main devices, the compressor, the condenser, the capillary, and the evaporator in correspondence to ambient temperature. The analysis devices of the four devices’s exergy influenced by the varied ambient temperature and found that the capillary has unusual increasing exergy loss vs. increasing ambient temperature in comparison to the other devices. The result shows that reducing exergy loss of the capillary influenced by the ambient temperature is the key for improving working efficiency of an air-conditioning system when influence of the ambient temperature is considered. The higher ambient temperature causes the larger pressure drop of capillary and more exergy loss.

Prediction of thermal sensation in non-air-conditioned buildings in warm climates

DEFF Research Database (Denmark)

Fanger, Povl Ole; Toftum, Jørn

2002-01-01

The PMV model agrees well with high-quality field studies in buildings with HVAC systems, situated in cold, temperate and warm climates, studied during both summer and winter. In non-air-conditioned buildings in warm climates, occupants may sense the warmth as being less severe than the PMV...... predicts. The main reason is low expectations, but a metabolic rate that is estimated too high can also contribute to explaining the difference. An extension of the PMV model that includes an expectancy factor is introduced for use in non-air-conditioned buildings in warm climates. The extended PMV model...... agrees well with quality field studies in non-air-conditioned buildings of three continents....

Toward an Urban Political Ecology of Energy Justice: The Case of Rooftop Solar in Tucson, AZ

Science.gov (United States)

Franklin, Remington Santiago

A central challenge of the twenty-first century is to transition to a low-carbon energy system to reduce the risks of climate change. For Pima County, Arizona, where electricity accounts for the majority of greenhouse gas emissions, this requires rapid deployment of grid-tied renewable energy resources. In light of this challenge, photovoltaic solar has emerged as an important solution, providing the top source of new US electric generating capacity installed in 2016. However, there is still no consensus about the optimal scale for solar (centralized power plants, or small, decentralized systems) and the socio-economic implications for low income households. This thesis explores the implications of rooftop solar for energy justice through empirical research about a southern Arizona electric utility rate case. Utilities argue that existing rate structures shift costs from solar owners to lower-income ratepayers, while critics say the utility's proposed rate changes are unjust and that rooftop solar benefits all ratepayers. Drawing on my empirical data and an urban political ecology (UPE) approach, I analyze competing narratives that speak to three types of justice: distributive, procedural, and recognition. While dominant justice claims revolve around the distribution of costs through rates, competing narratives emphasize procedural and recognition (in)justice. Focusing on political economy, power relations, and the materiality of the grid, I reframe the utility's cost shift argument as a strategic narrative and explain why this justice claim is ultimately validated. I propose that UPE can further an energy justice analysis by understanding procedural and recognition injustice as systemic products of rate of return regulation and the material configuration of the electric grid.

Experimental study of cooling BIPV modules by forced convection in the air channel

International Nuclear Information System (INIS)

Kaiser, A.S.; Zamora, B.; Mazón, R.; García, J.R.; Vera, F.

2014-01-01

Highlights: • An experimental setup for studying the effects of forced convection on cell temperature. • The induced velocity within the forced convection channel significantly affects the PV cooling. • Correlations for the Ross coefficient, module temperature, efficiency, and power output. • Prediction of the thermal behavior of the PV module in BIPV configurations. - Abstract: The efficiency of photovoltaic systems depends mainly on the cell temperature. Frequently, the PV collectors are installed on the top of the building. One cost effective method to regulate the temperature of rooftop integrated photovoltaic panels is to provide an open air channel beneath the panel. The cell temperature of these PV modules is very much influenced by the capability of ventilating this channel. The ventilation may be modified by different factors such as the wind velocity, the air gap size, and the forced convection induced by a fan or by a conventional air conditioning system. This paper describes an experimental setup to study the influence of the air gap size and the forced ventilation on the cell temperature (and consequently on the electrical efficiency of the PV module) of a BIPV configuration, for different values of the incident solar radiation, ambient temperatures, and aspect ratios, as well as for several forced ventilation conditions. Semi empirical correlations for the Ross coefficient, module temperature, electrical efficiency, and power output are proposed, showing a good agreement with respect to experimental measurements. A critical channel aspect ratio close to 0.11 can be considered to minimize overheating of PV devices. For a duct velocity V v = 6 m/s, a power output increase of 19% is observed over the natural ventilation case (V v = 0.5 m/s)

Physiological and subjective responses in the elderly when using floor heating and air conditioning systems.

Science.gov (United States)

Hashiguchi, Nobuko; Tochihara, Yutaka; Ohnaka, Tadakatsu; Tsuchida, Chiaki; Otsuki, Tamio

2004-11-01

The purpose of this study was to investigate the effects of a floor heating and air conditioning system on thermal responses of the elderly. Eight elderly men and eight university students sat for 90 minutes in a chair under the following 3 conditions: air conditioning system (A), floor heating system (F) and no heating system (C). The air temperature of sitting head height for condition A was 25 degrees C, and the maximum difference in vertical air temperature was 4 degrees C. The air and floor temperature for condition F were 21 and 29 degrees C, respectively. The air temperature for condition C was 15 degrees C. There were no significant differences in rectal temperature and mean skin temperature between condition A and F. Systolic blood pressure of the elderly men in condition C significantly increased compared to those in condition A and F. No significant differences in systolic blood pressure between condition A and F were found. The percentage of subjects who felt comfortable under condition F was higher than that of those under condition A in both age groups, though the differences between condition F and A was not significant. Relationships between thermal comfort and peripheral (e.g., instep, calf, hand) skin temperature, and the relationship between thermal comfort and leg thermal sensation were significant for both age groups. However, the back and chest skin temperature and back thermal sensation for the elderly, in contrast to that for the young, was not significantly related to thermal comfort. These findings suggested that thermal responses and physiological strain using the floor heating system did not significantly differ from that using the air conditioning system, regardless of the subject age and despite the fact that the air temperature with the floor heating system was lower. An increase in BP for elderly was observed under the condition in which the air temperature was 15 degrees C, and it was suggested that it was necessary for the elderly

Alternative air-conditioning with the use of solar energy

International Nuclear Information System (INIS)

Algarbi, N. M.

2006-01-01

The paper concerns the investigation of the alternative air condition systems on the basis of the open absorbtion cycle with the use of solar energy as a heat source. Schematic solution of systems has been carried. The design analysis of working characteristics was performed for a wide rang of initial parameters (teperature and humidity of ambient air, the type and concentration of liquid sorbents, etc.) and construction features of heat and mass transfer.(Author)

Amelioration of Heat-Stress Conditions of Egyptian Summer Season on Friesian Calves Using Air Condition

International Nuclear Information System (INIS)

Nessim, M.Z.; Kamal, T.H.; Khalil, W.K.B.

2010-01-01

Male Friesian calves were used to evaluate cool air condition (AC) in alleviating heat stress (HS) determined by Heat Shock Protein genes expression (HSP), hormonal, biochemical and physiological parameters. The animals were exposed to summer heat stress (HS) under shade for two weeks (control). The maximum temperature humidity index (THI) during summer HS was from 81 to 88. Afterward the animals were exposed to AC, inside a climatic chamber for 6 hours daily for two weeks, where, the THI was from 70 to 71. The results revealed that expression level of the Hsp genes (Hsp72, Hsp70.1, Hsp70 and Hsp47) was lower under air condition treatment than under summer heat stress. Rectal temperature and respiration rate were significantly lower (p< 0.01) under air condition treatment than those under heat stress. Total triiodothyronin (T3) level was significantly higher (P< 0.05) in AC cooling treatments than in HS, while cortisol level was significantly lower (P < 0.01) in AC cooling treatment than in HS calves. Creatinine and Urea -N levels were significantly lower (P < 0.01) in AC cooling treatment than in HS calves. Triglycerides, ALT and AST levels were significantly lower (p<0.01), (P< 0.01) and (p<0.05), respectively in AC cooling treatment than in HS calves. These results demonstrated that there is a relationship between the molecular weight of HSPs and the level of HSPs gene exprisson. The higher the molecular weight (HSP 72) the lower is the HSPs gene expression level (0.82 in HS and 0.39 in AC) and vise versa. This holds true in both heat stress and air condition. AC treatment is capable to ameliorate heat stress of Friesian calves under hot summer climate

Exergy analysis of heating, refrigerating and air conditioning methods and applications

CERN Document Server

Dincer, Ibrahim

2015-01-01

Improve and optimize efficiency of HVAC and related energy systems from an exergy perspective. From fundamentals to advanced applications, Exergy Analysis of Heating, Air Conditioning, and Refrigeration provides readers with a clear and concise description of exergy analysis and its many uses. Focusing on the application of exergy methods to the primary technologies for heating, refrigerating, and air conditioning, Ibrahim Dincer and Marc A. Rosen demonstrate exactly how exergy can help improve and optimize efficiency, environmental performance, and cost-effectiveness. The book also discusses the analysis tools available, and includes many comprehensive case studies on current and emerging systems and technologies for real-world examples. From introducing exergy and thermodynamic fundamentals to presenting the use of exergy methods for heating, refrigeration, and air conditioning systems, this book equips any researcher or practicing engineer with the tools needed to learn and master the application of exergy...

Geothermal as a heat sink application for raising air conditioning efficency

Science.gov (United States)

Ibrahim, Hesham Safwat Osman Mohamed

2016-04-01

Objective: Geothermal applications in heating, ventilation, air-conditioning is a US technology for more than 30 years old ,which saves more than 30% average energy cost than the traditional air-conditioning systems systems. Applying this technology in Middle East and African countries would be very feasible specially in Egypt specially as it suffers Electric crisis --The temperature of the condensers and the heat rejecting equipment is much higher than the Egyptian land at different depth which is a great advantages, and must be measured, recorded, and studied accurately -The Far goal of the proposal is to construct from soil analysis a temperature gradient map for Egypt and , African countries on different depth till 100 m which is still unclear nowadays and must be measured and recorded in databases through researches - The main model of the research is to study the heat transfer gradient through the ground earth borehole,grout,high density polyethylene pipes , and water inlet temperature which affect the electric efficiency of the ground source heat pump air conditioning unit Impact on the Region: Such research result will contribute widely in Energy saving sector specially the air conditioning sector in Egypt and the African countries which consumes more than 30% of the electric consumption of the total consumption . and encouraging Green systems such Geothermal to be applied

Experimental investigation of a novel configuration of desiccant based evaporative air conditioning system

International Nuclear Information System (INIS)

Uçkan, İrfan; Yılmaz, Tuncay; Hürdoğan, Ertaç; Büyükalaca, Orhan

2013-01-01

Highlights: ► A novel desiccant based evaporative cooling system is developed and tested. ► Cooling capacity, COP and energy consumption of the system are evaluated. ► Indoor air conditions are in the range of thermal comfort zone and expanded comfort zone. ► Designing of the system have considerable effect on the energy consumption. - Abstract: A novel configuration of desiccant based evaporative cooling system for air conditioning application is developed and tested. At the beginning of the design stage of the system, an analysis is carried out in order to maximize the performance of the system. It is found based on configuration that outdoor air must be used for regeneration to increase performance of the system and so three air channels are used. Experiments are carried out to investigate the total performance of the system and performance of the components used during summer season in a hot and humid climate. Effectiveness values for both heat exchangers and evaporative coolers are calculated through this work. In addition to the cooling capacity, coefficient of performance (COP) and energy consumption of the system are also evaluated. Results show that the effectiveness for the heat exchangers and evaporative coolers are very high under different outdoor conditions. It is also shown from the results that indoor air conditions are in the range of thermal comfort zone defined by ASHRAE and expanded comfort zone for evaporative air conditioning applications.

A simulation Model of the Reactor Hall Ventilation and air Conditioning Systems of ETRR-2

International Nuclear Information System (INIS)

Abd El-Rahman, M.F.

2004-01-01

Although the conceptual design for any system differs from one designer to another. each of them aims to achieve the function of the system required. the ventilation and air conditioning system of reactors hall is one of those systems that really differs but always dose its function for which it is designed. thus, ventilation and air conditioning in some reactor hall constitute only one system whereas in some other ones, they are separate systems. the Egypt Research Reactor-2 (ETRR-2)represents the second type. most studies conducted on ventilation and air conditioning simulation models either in traditional building or for research rectors show that those models were not designed similarly to the model of the hall of ETRR-2 in which ventilation and air conditioning constitute two separate systems.besides, those studies experimented on ventilation and air conditioning simulation models of reactor building predict the temperature and humidity inside these buildings at certain outside condition and it is difficult to predict when the outside conditions are changed . also those studies do not discuss the influences of reactor power changes. therefore, the present work deals with a computational study backed by infield experimental measurements of the performance of the ventilation and air conditioning systems of reactor hall during normal operation at different outside conditions as well as at different levels of reactor power

Experimental Study on Intelligent Control Scheme for Fan Coil Air-Conditioning System

Directory of Open Access Journals (Sweden)

Yanfeng Li

2013-01-01

Full Text Available An intelligent control scheme for fan coil air-conditioning systems has been put forward in order to overcome the shortcomings of the traditional proportion-integral-derivative (PID control scheme. These shortcomings include the inability of anti-interference and large inertia. An intelligent control test rig of fan coil air-conditioning system has been built, and MATLAB/Simulink dynamics simulation software has been adopted to implement the intelligent control scheme. A software for data exchange has been developed to combine the intelligence control system and the building automation (BA system. Experimental tests have been conducted to investigate the effectiveness of different control schemes including the traditional PID control, fuzzy control, and fuzzy-PID control for fan coil air-conditioning system. The effects of control schemes have been compared and analyzed in robustness, static and dynamic character, and economy. The results have shown that the developed data exchange interface software can induce the intelligent control scheme of the BA system more effectively. Among the proposed control strategies, fuzzy-PID control scheme which has the advantages of both traditional PID and fuzzy schemes is the optimal control scheme for the fan coil air-conditioning system.

2017 German refrigeration and air conditioning meeting. Proceedings

International Nuclear Information System (INIS)

2017-01-01

This year's lecture programme includes 117 presentations in the five working departments of DKV and 10 lectures at the special event ''Energy-efficient air conditioning in data centres''. The main topics in the respective departments were: (1) Cryogenics: Space applications; Cryogenic plants; Cryomedicine and cryobiology; Components, developments; Processes and plants; Valves, design. (2) Basics: Evaporation, material values; evaporation, condensation; absorption; adsorption, latent storage; cycle simulation. (3) Components: CO 2 plant engineering and components; refrigerants; process control, adsorption, sublimation and storage technology; refrigerating machine oils, heat exchangers and corrosion; components 4.0, sensors and control technology; simulation of plant processes. (4) Cold application: Application; Application / Natural Refrigerants; Mobile Applications Car; Mobile Applications; Supermarket / Efficiency; Optimization / Efficiency. (5) Air conditioning and heat pump applications: load shifting, smart home, flexibility; heat sources and industrial heat pumps; modelling, simulations; energy concepts heat pumps and photovoltaics; monitoring, evaluation; technology trends / working materials. Six papers are separately analyzed for this database. [de

Estimation of thermal sensation during varied air temperature conditions.

Science.gov (United States)

Katsuura, T; Tabuchi, R; Iwanaga, K; Harada, H; Kikuchi, Y

1998-03-01

Seven male students were exposed to four varied air temperature environments: hot (37 degrees C) to neutral (27 degrees C) (HN), neutral to hot (NH), cool (17 degrees C) to neutral (CN), and neutral to cool (NC). The air temperature was maintained at the first condition for 20 min, then was changed to the second condition after 15 min and was held there for 20 min. Each subject wore a T-shirt, briefs, trunks, and socks. Each sat on a chair and was continuously evaluated for thermal sensation, thermal comfort, and air velocity sensation. Some physiological and thermal parameters were also measured every 5 s during the experiment. The correlation between thermal sensation and skin temperature at 15 sites was found to be poor. The subjects felt much warmer during the rising phase of the air temperature (CN, NH) than during the descending phase (HN, NC) at a given mean skin temperature. However, thermal sensation at the same heat flux or at the same value of the difference between skin and air temperature (delta(Tsk - Ta)) was not so different among the four experimental conditions, and the correlation between thermal sensation and heat flux or delta(Tsk - Ta) was fairly good. The multiple regression equation of the thermal sensation (TS) on 15 sites of skin temperature (Tsk; degrees C) was calculated and the coefficient of determination (R*2) was found to be 0.656. Higher coefficients of determination were found in the equations of thermal sensation for the heat flux (H; kcal.m-2.h-1) at the right and left thighs of the subjects and on delta(Tsk - Ta) (degrees C) at 4 sites. They were as follows: TS = 2.04 - 0.016 Hright - 0.036 Hleft; R*2 = 0.717, TS = 1.649 + 0.013 delta(Tsk - Ta)UpperArm - 0.036 delta(Tsk - Ta)Chest - 0.223 delta(Tsk - Ta)Thigh-0.083 delta(Tsk - Ta)LowerLeg; R*2 = 0.752, respectively.

Modeling air concentration over macro roughness conditions by Artificial Intelligence techniques

Science.gov (United States)

Roshni, T.; Pagliara, S.

2018-05-01

Aeration is improved in rivers by the turbulence created in the flow over macro and intermediate roughness conditions. Macro and intermediate roughness flow conditions are generated by flows over block ramps or rock chutes. The measurements are taken in uniform flow region. Efficacy of soft computing methods in modeling hydraulic parameters are not common so far. In this study, modeling efficiencies of MPMR model and FFNN model are found for estimating the air concentration over block ramps under macro roughness conditions. The experimental data are used for training and testing phases. Potential capability of MPMR and FFNN model in estimating air concentration are proved through this study.

Silver zeolite antimicrobial activity in aluminium heating, ventilation and air conditioning system ducts.

Science.gov (United States)

Rizzetto, R; Mansi, A; Panatto, D; Rizzitelli, E; Tinteri, C; Sasso, T; Gasparini, R; Crovari, P

2008-03-01

Air pollution in confined environments is a serious health problem, in that most people spend long periods indoors (in homes, offices, classrooms etc.). Some people (children, the elderly, heart disease patients, asthmatic or allergic subjects) are at greater risk because of their conditions of frailty. The growing use of air-conditioning systems in many public and private buildings aggravates this health risk, especially when these systems are not correctly installed or regularly serviced. The aim of our study was to verify the capacity of Ag+ ions to stop the growth of bacteria and moulds inside the ducts of Heating, Ventilation and Air Conditioning system ducts (HVAC) systems when these ducts were lined with active Ag+ ions zeolite-coated panels. A Y-shaped HVAC model with two branches was used; one branch was made of traditional galvanized iron, as was the whole system, while the other was lined with active Ag+ zeolite-coated polyurethane panels. During the test, samples of dust present inside both ducts were collected and seeded in liquid and solid media to detect bacteria and moulds. The presence of bacteria was also sought in the air emerging from the outlets of both ducts. Tests made on samples of particulate collected from the two different ducts revealed a lower total bacterial load in the samples collected from the Ag+ zeolite-coated duct than in the samples from the traditional Zn galvanized duct. In addition, the values of bacterial load found in the air emerging from the Ag+ ions zeolite-lined duct were 5 times lower than those found in the air from the traditional galvanized iron duct. The utilization of Ag+ zeolite-coated panels in air-conditioning systems could improve the quality of the emerging air in comparison with traditional installations in galvanized iron. This innovation could prove particularly advantageous in the event of accidents during the installation of air-conditioning systems or of contaminated aerosols coming from outside.

Field Study on Humidification Performance of a Desiccant Air-Conditioning System Combined with a Heat Pump

Directory of Open Access Journals (Sweden)

Koichi Kawamoto

2016-01-01

Full Text Available A desiccant air-conditioning system was developed as a latent-load-processing air conditioner in a dedicated outdoor air system during the summer. This study investigated the application of this air-conditioning system to humidification during the winter without using make-up water, thereby eliminating the cause of microbial contamination in air-conditioning systems. The experiments were conducted with a system used for summer applications to determine the feasibility of adsorbing vapor from outdoor air and supplying it to an indoor space. The humidification performance, energy efficiency, and operating conditions were examined. Although the conditions were subpar because the experiments were performed with an actual dedicated outdoor air system, the results showed that it is possible to supply air with a minimum humidity ratio of 5.8 g/kg dry air (DA when the humidity ratio of outdoor air ranges from 1.8 to 2.3 g/kg DA. The minimum humidification performance required for a dedicated outdoor air system was achieved by increasing the airflow rate of the moisture-adsorption side to 2–3 times that of the humidification side. In addition, air leaking from the moisture-adsorption side to the humidification side, improving the mechanical structure, such as by the insulation of the moisture-adsorption side, and an efficient operating method were examined for humidification during the winter.

Development of Fuzzy Logic Control for Vehicle Air Conditioning System

Directory of Open Access Journals (Sweden)

Henry Nasution

2008-08-01

Full Text Available A vehicle air conditioning system is experimentally investigated. Measurements were taken during the experimental period at a time interval of one minute for a set point temperature of 22, 23 and 24oC with internal heat loads of 0, 1 and 2 kW. The cabin temperature and the speed of the compressor were varied and the performance of the system, energy consumption and energy saving ware analyzed. The main objective of the experimental work is to evaluate the energy saving obtained when the fuzzy logic control (FLC algorithm, through an inverter, continuously regulates the compressor speed. It demonstrates better control of the compressor operation in terms of energy consumption as compared to the control by using a thermostat imposing On/Off cycles on the compressor at the nominal frequency of 50 Hz. The experimental set-up consists of original components from the air conditioning system of a compact passenger vehicle. The experimental results indicate that the proposed technique can save energy and improve indoor comfort significantly for vehicle air conditioning systems compared to the conventional (On/Off control technique.

Proposal for energy saving in air conditioning equipment; Propuesta para ahorro energetico en acondicionadores de aire

Energy Technology Data Exchange (ETDEWEB)

Solis Recendez, Daniel H [Division de Ingenieria Electrica, Universidad Nacional Autonoma de Mexico (Mexico)

2008-10-15

In the last decades, the air conditioning systems have become a crucial part in the search from comfort in extreme climates. Nevertheless, they have also become one of the greatest energy consumers. In this article it is proposed that the final conditions that the air conditioning equipment looks for not to be fixed, but variable in respect to a certain comfort zone. This zone is a variation of the used one in the bio-climatic chart of Olgyay that considers the rapidity whereupon the reached conditions tend to leave the comfort zone. It is analyzed how to choose the point on the zone that costs less energy in arriving to it. [Spanish] En las ultimas decadas, los sistemas de aire acondicionado se han vuelto una parte crucial en la busqueda de confort en climas extremosos. Sin embargo, tambien se han vuelto de los mayores consumidores de energia. En este articulo se propone que las condiciones finales que busquen lograr los acondicionadores no sean fijas, si no variables respecto a una determinada zona de confort. Dicha zona es una variacion de la utilizada en la carta bioclimatica de Olgyay, que considera la rapidez con que las condiciones alcanzadas tienden a abandonar la zona de confort. Se discute como elegir el punto sobre la zona que cueste menos energia en llegara el.

Energy savings potential of a hybrid desiccant dehumidification air conditioning system in Beirut

International Nuclear Information System (INIS)

Ghali, Kamel

2008-01-01

In this work, the transient performance of a hybrid desiccant vapor compression air conditioning system is numerically simulated for the ambient conditions of Beirut. The main feature of this hybrid system is that the regenerative heat needed by the desiccant wheel is partly supplied by the condenser dissipated heat while the rest is supplied by an auxiliary gas heater. The hybrid air conditioning system of the present study replaces a 23 kW vapor compression unit for a typical office in Beirut characterized by a high latent load. The vapor compression subsystem size in the hybrid air conditioning system is reduced to 15 kW at the peak load when the regeneration temperature was fixed at 75 deg. C. Also the sensible heat ratio of the combined hybrid system increased from 0.47 to 0.73. Based on hour by hour simulation studies for a wide range of recorded ambient conditions of Beirut city, this paper predicts the annual energy consumption of the hybrid system in comparison with the conventional vapor compression system for the entire cooling season. The annual running costs savings for the hybrid system is 418.39 USD for a gas cost price of 0.141 USD/kg. The pay back period of the hybrid system is less than five years when the initial cost of the hybrid air conditioning system priced an additional 1712.00 USD. Hence, for a 20-year life cycle, the life cycle savings of the hybrid air conditioning system are 4295.19 USD

Performance Investigation of Air Velocity Effects on PV Modules under Controlled Conditions

Directory of Open Access Journals (Sweden)

Muzaffar Ali

2017-01-01

Full Text Available Junction temperature of PV modules is one of the key parameters on which the performance of PV modules depends. In the present work, an experimental investigation was carried out to analyze the effects of air velocity on the performance of two PV modules, that is, monocrystalline silicon and polycrystalline silicon under the controlled conditions of a wind tunnel in the presence of an artificial solar simulator. The parameters investigated include the surface temperature variation, power output, and efficiency of PV modules under varying air velocity from near zero (indoor lab. conditions to 15 m/s. Additionally, the results were also determined at two different module angular positions: at 0° angle, that is, parallel to air direction and at 10° angle with the direction of coming air to consider the effects of tilt angles. Afterwards, the thermal analysis of the modules was performed using Ansys-Fluent in which junction temperature and heat flux of modules were determined by applying appropriate boundary conditions, such as air velocity, heat flux, and solar radiation. Finally, the numerical results are compared with the experiment in terms of junction temperatures of modules and good agreement was found. Additionally, the results showed that the maximum module temperature drops by 17.2°C and the module efficiency and power output increased from 10 to 12% with increasing air velocity.

Conceptual Design of Automotive Compressor for Integrated Portable Air Conditioning System

Directory of Open Access Journals (Sweden)

Ishak Muhammad Ikman

2017-01-01

Full Text Available This study introduces a new concept of portable air conditioner which integrated with some available components in automotive air conditioning system. This new idea intends to solve the storage problems as well as to reduce the price of current portable air conditioner since some devices could directly be used from the automotive air conditioning system. The primary emphasis of this study was on the modification of automotive compressor design so as the system may alternately be operated. The length of conventional compressor shaft is extended to place an additional clutch pulley, a drive plate and a clutch coil. The new concept particularly the shaft and pulley were analysed through slope deflection and computational finite element analyses. The result of engineering analyses exhibited that the new design of compressor shaft and clutch pulleys promote a low risk of failure as the data values recorded are lower than the critical value for each criterion investigated.

THERMAL COMFORT STUDY OF AN AIR-CONDITIONED DESIGN STUDIO IN TROPICAL SURABAYA

Directory of Open Access Journals (Sweden)

Agus Dwi Hariyanto

2005-01-01

Full Text Available This paper evaluates the current thermal comfort condition in an air-conditioned design studio using objective measurement and subjective assessment. Objective measurement is mainly to quantify the air temperature, MRT, relative humidity, and air velocity. Subjective assessment is conducted using a questionnaire to determine the occupants thermal comfort sensations and investigate their perception of the thermal comfort level. A design studio in an academic institution in Surabaya was chosen for the study. Results show that more than 80% of the occupants accepted the indoor thermal conditions even though both the environmental and comfort indices exceeded the limit of the standard (ASHRAE Standard 55 and ISO 7730. In addition, non-uniformity of spatial temperature was present in this studio. Some practical recommendations were made to improve the thermal comfort in the design studio.

Experimental analysis of the thermal entrainment factor of air curtains in vertical open display cabinets for different ambient air conditions

International Nuclear Information System (INIS)

Gaspar, Pedro Dinis; Carrilho Goncalves, L.C.; Pitarma, R.A.

2011-01-01

The vertical open refrigerated display cabinets suffer alterations of their thermal performance and energy efficiency due to variations of ambient air conditions. The air curtain provides an aerothermodynamics insulation effect that can be evaluated by the thermal entrainment factor calculation as an engineering approximation or by the calculus of all sensible and latent thermal loads. This study presents the variation of heat transfer rate and thermal entrainment factor obtained through experimental tests carried out for different ambient air conditions, varying air temperature, relative humidity, velocity and its direction relatively to the display cabinet frontal opening. The thermal entrainment factor are analysed and compared with the total sensible and latent heats results for the experimental tests. From an engineering point of view, it is concluded that thermal entrainment factor cannot be used indiscriminately, although its use is suitable to design better cabinet under the same climate class condition.

Economic and Environmental Assessment of a 1 MW Grid Connected Rooftop Solar PV System for Energy Efficient Building in Bangladesh

Science.gov (United States)

Chakraborty, Sanjib; Hosain, Rubayet; Rahman, Toufiqur; Rabbi, Ahmead Fazle

This paper evaluates the potentiality of a 1 MW grid connected rooftop solar PV system for an Energy Efficient Building in Bangladesh, which was estimated by utilizing NASA SSE solar radiation data, PVsyst simulation software and RETScreen simulation software. Economic and environmental viability for a ten-storied building with roof area of 6,500 m2 in the Capital City of Bangladesh, Dhaka was assessed by using the RETScreen simulation software. The yearly electricity production of the proposed system was 1,581 MWh estimated by PVsyst where the technical prospective of gird-connected solar PV in Bangladesh was calculated as about 50,174 MW. The economic assessments were determined the simple payback in such a way that the generated electricity first fulfills the demand of the building, and then the rest of the energy is supplied to the grid. The result indicates that the roof top solar PV system for an Energy efficient building in Dhaka city has a favorable condition for development both in economic and environmental point of view.

Heat pipe heat exchanger for heat recovery in air conditioning

Energy Technology Data Exchange (ETDEWEB)

Abd El-Baky, Mostafa A.; Mohamed, Mousa M. [Mechanical Power Engineering Department, Faculty of Engineering, Minufiya University, Shebin El-Kom (Egypt)

2007-03-15

The heat pipe heat exchangers are used in heat recovery applications to cool the incoming fresh air in air conditioning applications. Two streams of fresh and return air have been connected with heat pipe heat exchanger to investigate the thermal performance and effectiveness of heat recovery system. Ratios of mass flow rate between return and fresh air of 1, 1.5 and 2.3 have been adapted to validate the heat transfer and the temperature change of fresh air. Fresh air inlet temperature of 32-40{sup o}C has been controlled, while the inlet return air temperature is kept constant at about 26{sup o}C. The results showed that the temperature changes of fresh and return air are increased with the increase of inlet temperature of fresh air. The effectiveness and heat transfer for both evaporator and condenser sections are also increased to about 48%, when the inlet fresh air temperature is increased to 40{sup o}C. The effect of mass flow rate ratio on effectiveness is positive for evaporator side and negative for condenser side. The enthalpy ratio between the heat recovery and conventional air mixing is increased to about 85% with increasing fresh air inlet temperature. The optimum effectiveness of heat pipe heat exchanger is estimated and compared with the present experimental data. The results showed that the effectiveness is close to the optimum effectiveness at fresh air inlet temperature near the fluid operating temperature of heat pipes. (author)

Evaluation of Rankine cycle air conditioning system hardware by computer simulation

Science.gov (United States)

Healey, H. M.; Clark, D.

1978-01-01

A computer program for simulating the performance of a variety of solar powered Rankine cycle air conditioning system components (RCACS) has been developed. The computer program models actual equipment by developing performance maps from manufacturers data and is capable of simulating off-design operation of the RCACS components. The program designed to be a subroutine of the Marshall Space Flight Center (MSFC) Solar Energy System Analysis Computer Program 'SOLRAD', is a complete package suitable for use by an occasional computer user in developing performance maps of heating, ventilation and air conditioning components.

Extension of the PMV model to non-air-conditioned building in warm climates

DEFF Research Database (Denmark)

Fanger, Povl Ole; Toftum, Jørn

2002-01-01

The PMV model agrees well with high-quality field studies in buildings with HVAC systems, situated in cold, temperate and warm climates, studied during both summer and winter. In non-air-conditioned buildings in warm climates, occupants may sense the warmth as being less severe than the PMV...... predicts. The main reason is low expectations, but a metabolic rate that is estimated too high can also contribute to explaining the difference. An extension of the PMV model that includes an expectancy factor is introduced for use in non-air-conditioned buildings in warm climates. The extended PMV model...... agrees well with quality field studies in non-air-conditioned buildings of three continents....

The biggest rooftop PV plant in Latin America. An example of a pioneering project for the whole region

International Nuclear Information System (INIS)

2016-01-01

About a year ago, the largest rooftop PV installation in Latin America came online in Honduras. Inaugurated by the country’s president, Juan Orlando Hernández, in March 2015, the plant is situated on the roof of the region’s PepsiCo bottling plant, EMSULA (Embotelladora de Sula S.A.) in the town of San Pedro Sula. The project, which has become a reference in the region, has been developed over two phases, the first of which corresponds to a 259 kWp pilot project, commissioned in November 2013, to which the second phase was added last year. (Author)

IEA SHC Task 38 'Solar air-conditioning and refrigeration'. Danish participation 2007-2010. Appendix; IEA SHC Task 38 'Solar air-conditioning and refrigeration'. Dansk deltagelse 2007-2010. Bilag

Energy Technology Data Exchange (ETDEWEB)

Ellehauge, K [Ellehauge og Kildemoes, Aarhus (Denmark); Muenster, E [PlanEnergi, Skoerping (Denmark); Reinholdt, L [Teknologisk Institut, Aarhus (Denmark); Munds, S [AC-Sun Aps, Horsens (Denmark)

2011-03-15

IEA SHC Task 38 'Solar Air-Conditioning and Refrigeration' ran from October 2006 to December 2010. Denmark was represented in the task from January 2007 to December 2010. The aim of the task was to encourage use of solar powered refrigeration and air conditioning systems in particular at residential, commercial and industrial sectors. Furthermore, the aim was to contribute to new research and development activities on new systems and concepts. The appendix contains the publications prepared by the Danish project group.(LN)

2016 German refrigeration and air conditioning meeting. Proceedings

International Nuclear Information System (INIS)

2016-01-01

The following topics were dealt with: Large cryogenic facilities, relief valves, liquid helium, liquid-nitrogen and liquid hydrogen cooling, new concepts, foundations and materials of the heat-pump techniques, evaporation, phase-change materials, absorption, afterheat usage, ionic liquids, sorption, condensers, heat exchangers, back-cooling systems, refrigerants, caron dioxide, mobile applications, efficiency and optimization, air conditioning.

An energy performance assessment for indoor environmental quality (IEQ) acceptance in air-conditioned offices

International Nuclear Information System (INIS)

Wong, L.T.; Mui, K.W.

2009-01-01

Maintaining an acceptable indoor environmental quality (IEQ) for air-conditioned office buildings consumes a considerable amount of thermal energy. This study correlates thermal energy consumption with the overall occupant acceptance of IEQ in some air-conditioned offices. An empirical expression of an IEQ index associated with thermal comfort, indoor air quality, aural and visual comfort is used to benchmark the offices. Employing input parameters obtained from the building stocks of Hong Kong, the office portfolios regarding the thermal energy consumption and the IEQ index are determined by Monte Carlo simulations. In particular, an energy-to-acceptance ratio and an energy-to-IEQ improvement ratio are proposed to measure the performance of energy consumption for the IEQ in the air-conditioned offices. The ratios give the thermal energy consumption corresponding to a desirable percentage of IEQ acceptances and to an IEQ upgrade, respectively. The results showed a non-linear increasing trend of annual thermal energy consumption for IEQ improvement at the offices of higher IEQ benchmarks. The thermal energy consumption for visual comfort and indoor air quality would also be significant in these offices. This study provides useful information that incorporates the IEQ in air-conditioned offices into the development of performance evaluation measures for thermal energy consumption.

Local Air Quality Conditions and Forecasts

Science.gov (United States)

... Monitor Location Archived Maps by Region Canada Air Quality Air Quality on Google Earth Links A-Z About AirNow AirNow International Air Quality Action Days / Alerts AirCompare Air Quality Index (AQI) ...

Reducing indoor air pollution by air conditioning is associated with improvements in cardiovascular health among the general population.

Science.gov (United States)

Lin, Lian-Yu; Chuang, Hsiao-Chi; Liu, I-Jung; Chen, Hua-Wei; Chuang, Kai-Jen

2013-10-01

Indoor air pollution is associated with cardiovascular effects, however, little is known about the effects of improving indoor air quality on cardiovascular health. The aim of this study was to explore whether improving indoor air quality through air conditioning can improve cardiovascular health in human subjects. We recruited a panel of 300 healthy subjects from Taipei, aged 20 and over, to participate in six home visits each, to measure a variety of cardiovascular endpoints, including high sensitivity-C-reactive protein (hs-CRP), 8-hydroxy-2'-deoxyguanosine (8-OHdG), fibrinogen in plasma and heart rate variability (HRV). Indoor particles and total volatile organic compounds (VOCs) were measured simultaneously at the participant's home during each visit. Three exposure conditions were investigated in this study: participants were requested to keep their windows open during the first two visits, close their windows during the next two visits, and close the windows and turn on their air conditioners during the last two visits. We used linear mixed-effects models to associate the cardiovascular endpoints with individual indoor air pollutants. The results showed that increases in hs-CRP, 8-OHdG and fibrinogen, and decreases in HRV indices were associated with increased levels of indoor particles and total VOCs in single-pollutant and two-pollutant models. The effects of indoor particles and total VOCs on cardiovascular endpoints were greatest during visits with the windows open. During visits with the air conditioners turned on, no significant changes in cardiovascular endpoints were observed. In conclusion, indoor air pollution is associated with inflammation, oxidative stress, blood coagulation and autonomic dysfunction. Reductions in indoor air pollution and subsequent improvements in cardiovascular health can be achieved by closing windows and turning on air conditioners at home. Copyright © 2013 Elsevier B.V. All rights reserved.

Design and Simulation of an Air Conditioning Project in a Hospital Based on Computational Fluid Dynamics

OpenAIRE

Ding X. R.; Guo Y. Y.; Chen Y. Y.

2017-01-01

This study aims to design a novel air cleaning facility which conforms to the current situation in China, and moreover can satisfy our demand on air purification under the condition of poor air quality, as well as discuss the development means of a prototype product. Air conditions in the operating room of a hospital were measured as the research subject of this study. First, a suitable turbulence model and boundary conditions were selected and computational fluid dynamics (CFD) software was ...

Analisa Performansi Sistem Air Conditioning Mobil tipe ET 450 dengan Variasi Tekanan Kerja Kompresor

Directory of Open Access Journals (Sweden)

Adi Purnawan

2012-11-01

Full Text Available Comfort and coolness when traveling by vehicle especially car is highly needed. So many attempts have been made byhumans that comfortable traveling by car can be achieved. One of the effective ways in which comfortable traveling by car can beobtained is by installing air conditioning. The performance of air conditioning system is highly influenced by how the compressorworks. In other words, the pressure resulting from the suction highly determines the performance of air conditioning system,which then affects how the compressor works, the compressor power, the refrigeration effect, the efficiency of isentropic andcoefficient of performance (COP of the car air conditioning sytem especially that of the car air conditioner type ET 450. Fromwhat has been described above, the writer would like to conduct a research entiled “ Analysis of the Performance of the Car AirConditioning system Type ET 450 with Variation of the Compressor Pressure”.The test was conducted on the car air conditioner type ET 450 with variations of suction 2.8 bar, 3 bar, 3.2 bar, 3.4bar, 3.6 bar and 3.8 bar. The data were obtained from the pressure of compressor output (P2, the temperatures in each point areT1, T2, T3, T4, the compressor rotationn is n, the strength of electrical current is I, and the volumetric flow rate. The data werethen processed and analyzed so that so that the performance of each variation of the suction could be actually and theoreticallyobtained.The findings show that the bigger the suction, the bigger the performance of the car air conditioner type ET 450 wouldbe. The theoretical coefficient of performance (COP produced was bigger than the actual COP. The optimal COP took placewhen the suction was 441.325 kPa, the actual COP was 3.513177 and the theoretical COP was 3.632062

2014 German refrigeration and air conditioning meeting. Proceedings; Deutsche Kaelte- und Klimatagung 2014. Tagungsbericht

Energy Technology Data Exchange (ETDEWEB)

NONE

2014-07-01

The proceedings of the 2014 German refrigeration and air conditioning meeting contain contributions on the following topics: cryotechnology, fundamentals and materials for the refrigeration and heat pump technology, devices and components for the refrigeration and heat pump technology, applications of refrigeration technologies, air conditioning technology and heat pump applications, cryotechnology in biology and medicine, heat transfer and ventilation, guidelines and legal topics, refrigerant fluid - oil mixtures, control and surveillance, simulation and control, ambient air.

Life cycle cost analysis of HPVT air collector under different Indian climatic conditions

International Nuclear Information System (INIS)

Raman, Vivek; Tiwari, G.N.

2008-01-01

In this communication, a study is carried out to evaluate an annual thermal and exergy efficiency of a hybrid photovoltaic thermal (HPVT) air collector for different Indian climate conditions, of Srinagar, Mumbai, Jodhpur, New Delhi and Banglore. The study has been based on electrical, thermal and exergy output of the HPVT air collector. Further, the life cycle analysis in terms of cost/kWh has been carried out. The main focus of the study is to see the effect of interest rate, life of the HPVT air collector, subsidy, etc. on the cost/kWh HPVT air collector. A comparison is made keeping in view the energy matrices. The study reveals that (i) annual thermal and electrical efficiency decreases with increase in solar radiation and (ii) the cost/kWh is higher in case of exergy when compared with cost/kWh on the basis of thermal energy for all climate conditions. The cost/kWh for climate conditions of Jodhpur is most economical

Passive radiative cooling below ambient air temperature under direct sunlight.

Science.gov (United States)

Raman, Aaswath P; Anoma, Marc Abou; Zhu, Linxiao; Rephaeli, Eden; Fan, Shanhui

2014-11-27

Cooling is a significant end-use of energy globally and a major driver of peak electricity demand. Air conditioning, for example, accounts for nearly fifteen per cent of the primary energy used by buildings in the United States. A passive cooling strategy that cools without any electricity input could therefore have a significant impact on global energy consumption. To achieve cooling one needs to be able to reach and maintain a temperature below that of the ambient air. At night, passive cooling below ambient air temperature has been demonstrated using a technique known as radiative cooling, in which a device exposed to the sky is used to radiate heat to outer space through a transparency window in the atmosphere between 8 and 13 micrometres. Peak cooling demand, however, occurs during the daytime. Daytime radiative cooling to a temperature below ambient of a surface under direct sunlight has not been achieved because sky access during the day results in heating of the radiative cooler by the Sun. Here, we experimentally demonstrate radiative cooling to nearly 5 degrees Celsius below the ambient air temperature under direct sunlight. Using a thermal photonic approach, we introduce an integrated photonic solar reflector and thermal emitter consisting of seven layers of HfO2 and SiO2 that reflects 97 per cent of incident sunlight while emitting strongly and selectively in the atmospheric transparency window. When exposed to direct sunlight exceeding 850 watts per square metre on a rooftop, the photonic radiative cooler cools to 4.9 degrees Celsius below ambient air temperature, and has a cooling power of 40.1 watts per square metre at ambient air temperature. These results demonstrate that a tailored, photonic approach can fundamentally enable new technological possibilities for energy efficiency. Further, the cold darkness of the Universe can be used as a renewable thermodynamic resource, even during the hottest hours of the day.

Energy performance and optimal control of air-conditioned buildings with envelopes enhanced by phase change materials

International Nuclear Information System (INIS)

Zhu Na; Wang Shengwei; Ma Zhenjun; Sun Yongjun

2011-01-01

Highlights: → Impact of PCM on the energy consumption and peak load demand as well as electricity cost of air-conditioned buildings. → Impact of load shifting control on energy consumption, peak load and electricity cost of air-conditioned PCM buildings. → Impact of demand limiting control on energy consumption, peak load and electricity cost of air-conditioned PCM buildings. → Energy/cost effects of different control strategies and use of PCM in energy-plus-demand-based pricing policy. → Energy/cost effects of different control strategies and use of PCM in time-based pricing policy. - Abstract: Studies are conducted to investigate the impacts of shape-stabilized phase change material (SSPCM) and different control strategies on the energy consumption and peak load demand as well as electricity cost of building air-conditioning systems at typical summer conditions in two climates (subtropical and dry continental climates). An office building using a typical variable air volume (VAV) air-conditioning system was selected and simulated as the reference building in this study. Its envelopes were enhanced by integrating the SSPCM layers into its walls while the air-conditioning system and other configurations of the building remained unchanged. The building system was tested under two typical weather conditions and two typical electricity pricing policies (i.e. time-based pricing and energy-plus-demand-based pricing). Test results show that the use of SSPCM in the building could reduce the building electricity cost significantly (over 11% in electricity cost reduction and over 20% in peak load reduction), under two pricing policies by using load shifting control and demand limiting control respectively. This paper presents the test results and the evaluation on the energy performance and the optimal control strategies of air-conditioned commercial buildings with envelopes enhanced by SSPCM.

Experimental and numerical study of an evaporatively-cooled condenser of air-conditioning systems

International Nuclear Information System (INIS)

Islam, M.R.; Jahangeer, K.A.; Chua, K.J.

2015-01-01

The performance of an air-conditioning unit with evaporately-cooled condenser coil is studied experimentally and numerically. An experimental setup is fabricated by retrofitting a commercially available air-conditioning unit and installing comprehensive measuring sensors and controllers. Experimental result shows that the COP (Coefficient of Performance) of the evaporately-cooled air-conditioning unit increases by about 28% compared to the conventional air cooled air-conditioning unit. To analyze the heat and mass transfer processes involved in the evaporately-cooled condenser, a detailed theoretical model has been developed based on the fluid flow characteristics of the falling film and the thermodynamic aspect of the evaporation process. Simulated results agree well with experimental data. The numerical model provides new insights into the intrinsic links between operating variables and heat transfer characteristics of water film in evaluating the performance of evaporatively-cooled condenser system. Two heat transfer coefficients, namely, wall to bulk and bulk to interface are introduced and computed from the simulation results under different operating conditions. Finally, the overall heat transfer coefficient for the water film is computed and presented as a function of dimensionless variables which can conveniently be employed by engineers to design and analyze high performance evaporatively-cooled heat exchangers. - Highlights: • Performance of evaporatively-cooled condenser is investigated. • Local convective heat transfer coefficients of water film are determined. • Thermal resistance of water film is negligible. • Heat transfer with evaporated vapor plays significant role on performance. • Better condenser performance translates to an improvement in COP

Studies of Radon and Radon Progeny in Air Conditioned Rooms in Hospitals

International Nuclear Information System (INIS)

Marley, F.; Denman, A.R.; Phillips, P.S.

1998-01-01

A series of continuous real-time radon and radon progeny measurements together with passive etched track detector measurements were performed in hospital premises during 1996. In one small room, detailed measurements over several weeks showed that both the radon concentration and the Equilibrium Factor depended on the intermittent operation of a filtered positive pressure displacement air-conditioning system, which was designed to conform to operating theatre standards. The average radon level measured while the air-conditioning was off was almost four times higher than that recorded whilst it was on. The progeny level was over five times higher than that whilst it was on. Thus, the Equilibrium Factor (F), was significantly lower when the air-conditioning was on. Measurements in similar rooms in two hospitals, confirmed that the reduction in radon level was a general finding. Thus staff working in such environments receive significantly lower radiation dose from radon than staff working in nearby normally ventilated rooms. (author)

Hollow Fiber Membrane Dehumidification Device for Air Conditioning System.

Science.gov (United States)

Zhao, Baiwang; Peng, Na; Liang, Canzeng; Yong, Wai Fen; Chung, Tai-Shung

2015-11-16

In order to provide a comfortable living and working environment indoors in tropical countries, the outdoor air often needs to be cooled and dehumidified before it enters the rooms. Membrane separation is an emerging technology for air dehumidification and it is based on the solution diffusion mechanism. Water molecules are preferentially permeating through the membranes due to its smaller kinetic diameter and higher condensability than the other gases. Compared to other dehumidification technologies such as direct cooling or desiccation, there is no phase transition involved in membrane dehumidification, neither the contact between the fresh air stream and the desiccants. Hence, membrane dehumidification would not only require less energy consumption but also avoid cross-contamination problems. A pilot scale air dehumidification system is built in this study which comprises nine pieces of one-inch PAN/PDMS hollow fiber membrane modules. A 150 h long-term test shows that the membrane modules has good water vapor transport properties by using a low vacuum force of only 0.78 bar absolute pressure at the lumen side. The water vapor concentration of the feed humid air decreases dramatically from a range of 18-22 g/m³ to a range of 13.5-18.3 g/m³. Most importantly, the total energy saving is up to 26.2% compared with the conventional air conditioning process.

Hollow Fiber Membrane Dehumidification Device for Air Conditioning System

Directory of Open Access Journals (Sweden)

Baiwang Zhao

2015-11-01

Full Text Available In order to provide a comfortable living and working environment indoors in tropical countries, the outdoor air often needs to be cooled and dehumidified before it enters the rooms. Membrane separation is an emerging technology for air dehumidification and it is based on the solution diffusion mechanism. Water molecules are preferentially permeating through the membranes due to its smaller kinetic diameter and higher condensability than the other gases. Compared to other dehumidification technologies such as direct cooling or desiccation, there is no phase transition involved in membrane dehumidification, neither the contact between the fresh air stream and the desiccants. Hence, membrane dehumidification would not only require less energy consumption but also avoid cross-contamination problems. A pilot scale air dehumidification system is built in this study which comprises nine pieces of one-inch PAN/PDMS hollow fiber membrane modules. A 150 h long-term test shows that the membrane modules has good water vapor transport properties by using a low vacuum force of only 0.78 bar absolute pressure at the lumen side. The water vapor concentration of the feed humid air decreases dramatically from a range of 18–22 g/m3 to a range of 13.5–18.3 g/m3. Most importantly, the total energy saving is up to 26.2% compared with the conventional air conditioning process.

Air-lift pumps characteristics under two-phase flow conditions

International Nuclear Information System (INIS)

Kassab, Sadek Z.; Kandil, Hamdy A.; Warda, Hassan A.; Ahmed, Wael H.

2009-01-01

Air-lift pumps are finding increasing use where pump reliability and low maintenance are required, where corrosive, abrasive, or radioactive fluids in nuclear applications must be handled and when a compressed air is readily available as a source of a renewable energy for water pumping applications. The objective of the present study is to evaluate the performance of a pump under predetermined operating conditions and to optimize the related parameters. For this purpose, an air-lift pump was designed and tested. Experiments were performed for nine submergence ratios, and three risers of different lengths with different air injection pressures. Moreover, the pump was tested under different two-phase flow patterns. A theoretical model is proposed in this study taking into account the flow patterns at the best efficiency range where the pump is operated. The present results showed that the pump capacity and efficiency are functions of the air mass flow rate, submergence ratio, and riser pipe length. The best efficiency range of the air-lift pumps operation was found to be in the slug and slug-churn flow regimes. The proposed model has been compared with experimental data and the most cited models available. The proposed model is in good agreement with experimental results and found to predict the liquid volumetric flux for different flow patterns including bubbly, slug and churn flow patterns

2015 German refrigeration and air conditioning meeting. Abstracts; Deutsche Kaelte- und Klimatagung 2015. Kurzfassungen

Energy Technology Data Exchange (ETDEWEB)

NONE

2015-07-01

The volume contains the abstracts of the 2015 German refrigeration and air conditioning meeting in 5 chapters: cryo-technology, fundamentals of materials for refrigeration engineering and heat pump technology, facilities and components for the refrigeration and heat pump technology; application of refrigeration engineering; air conditioning technology and heat pump application.

A new method for controlling refrigerant flow in automobile air conditioning

Energy Technology Data Exchange (ETDEWEB)

Xuquan Li; Jiangping Chen; Zhijiu Chen [Shanghai Jiao Tong University (China). Institute of Refrigeration and Cryogenics Engineering; Weihua Liu; Wei Hu; Xiaobing Liu [Shanghai Delphi Automotive Air Conditiong Systems Co. Ltd., Changhai (China)

2004-05-01

This paper describes the improvement of the refrigerant flow control method by using an electronic expansion valve (EEV) which is driven by a stepper motor in automobile air conditioning system. An EEV can make a quick response to the abrupt change in the refrigerant flow rate during the change in automobile speed and the thermostatic on/off operation. The flow rate characteristic of the EEV for automobile air conditioning was presented. A microcontroller is used to receive the input signal and generate the output signal to control the opening of the EEV. The fuzzy self-tuning proportional-integral-derivative (PID) control method is employed. Experimental results show that the new control method can feed adequate refrigerant flow into the evaporator in various operations. The evaporator discharge air temperature has dropped by approximately 3{sup o}C as compared with that of the conventional PID control system. (author)

Urban planning and agriculture. Methodology for assessing rooftop greenhouse potential of non-residential areas using airborne sensors.

Science.gov (United States)

Nadal, Ana; Alamús, Ramón; Pipia, Luca; Ruiz, Antonio; Corbera, Jordi; Cuerva, Eva; Rieradevall, Joan; Josa, Alejandro

2017-12-01

The integration of rooftop greenhouses (RTGs) in urban buildings is a practice that is becoming increasingly important in the world for their contribution to food security and sustainable development. However, the supply of tools and procedures to facilitate their implementation at the city scale is limited and laborious. This work aims to develop a specific and automated methodology for identifying the feasibility of implementation of rooftop greenhouses in non-residential urban areas, using airborne sensors. The use of Light Detection and Ranging (LIDAR) and Long Wave Infrared (LWIR) data and the Leica ALS50-II and TASI-600 sensors allow for the identification of some building roof parameters (area, slope, materials, and solar radiation) to determine the potential for constructing a RTG. This development represents an improvement in time and accuracy with respect to previous methodology, where all the relevant information must be acquired manually. The methodology has been applied and validated in a case study corresponding to a non-residential urban area in the industrial municipality of Rubí, Barcelona (Spain). Based on this practical application, an area of 36,312m 2 out of a total area of 1,243,540m 2 of roofs with ideal characteristics for the construction of RTGs was identified. This area can produce approximately 600tons of tomatoes per year, which represents the average yearly consumption for about 50% of Rubí total population. The use of this methodology also facilitates the decision making process in urban agriculture, allowing a quick identification of optimal surfaces for the future implementation of urban agriculture in housing. It also opens new avenues for the use of airborne technology in environmental topics in cities. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of cathode channel size and operating conditions on the performance of air-blowing PEMFCs

International Nuclear Information System (INIS)

Kim, Bosung; Lee, Yongtaek; Woo, Ahyoung; Kim, Yongchan

2013-01-01

Highlights: • Effect of cathode channel size on the air-blowing PEMFC is analyzed. • Performance and EIS tests of air-blowing PEMFCs are conducted. • Test conditions include the operating temperature, fan voltage, and anode humidity. • Flooding is a limiting factor for decreasing channel size at low temperature. • Water management is investigated by analyzing ohmic resistance. - Abstract: Air-blowing proton exchange membrane fuel cells (PEMFCs) have been developed as a potential new power source for portable electronic devices. However, air-blowing PEMFCs show lower performance than compressed-air PEMFCs because of their adverse operating conditions. In this study, the effects of the cathode channel size and operating conditions on the performance of the air-blowing PEMFC were analyzed. At the normal operating temperature, the performance of the air-blowing PEMFC improved with the decrease in the cathode channel size. However, at a low operating temperature and low fan voltage, massive flooding limits the decrease in the cathode channel size. In addition, water management in the air-blowing PEMFC was investigated by analyzing ohmic resistance. The transition current density between the humidification and the flooding region decreased with decreasing cathode channel size and operating temperature

Persistence of Initial Conditions in Continental Scale Air Quality Simulations

Data.gov (United States)

U.S. Environmental Protection Agency — This dataset contains the data used in Figures 1 – 6 and Table 2 of the technical note "Persistence of Initial Conditions in Continental Scale Air Quality...

Parametric analysis of a combined dew point evaporative-vapour compression based air conditioning system

Directory of Open Access Journals (Sweden)

Shailendra Singh Chauhan

2016-09-01

Full Text Available A dew point evaporative-vapour compression based combined air conditioning system for providing good human comfort conditions at a low cost has been proposed in this paper. The proposed system has been parametrically analysed for a wide range of ambient temperatures and specific humidity under some reasonable assumptions. The proposed system has also been compared from the conventional vapour compression air conditioner on the basis of cooling load on the cooling coil working on 100% fresh air assumption. The saving of cooling load on the coil was found to be maximum with a value of 60.93% at 46 °C and 6 g/kg specific humidity, while it was negative for very high humidity of ambient air, which indicates that proposed system is applicable for dry and moderate humid conditions but not for very humid conditions. The system is working well with an average net monthly power saving of 192.31 kW h for hot and dry conditions and 124.38 kW h for hot and moderate humid conditions. Therefore it could be a better alternative for dry and moderate humid climate with a payback period of 7.2 years.

Production and exploitation of thermoelectric air conditioning systems for vehicles

Energy Technology Data Exchange (ETDEWEB)

Dudnik, Vladimir [Conditioner Ltd, Gagarin (Russian Federation); Skipidarov, Sergey [SCTB NORD, Moskau (Russian Federation); Rapp, Axel [Quick-Ohm Kupper und Co. GmbH, Wuppertal-Cronenberg (Germany)

2011-07-01

In the paper more than 10-year experience of thermoelectric devices batch manufacturing is described for the field of their obvious advantages. This field of application includes thermoelectric air conditioning systems which have shown their competitive advantage when used in vehicles of elevated vibration where compressor equipment application is difficult because of leakage of refrigerant. Energy characteristics of air conditioners for tractors, excavators, tanks, locomotive driver's cabins and cranes are described. Thermoelectric (TE) air conditioners mechanical test data as well as operation experience in vehicles are presented. It is shown that consumption of tellurium, which is a strategic component for thermoelectric materials manufacturing, may be lowered to 40 grams per 1 kW of cooling. (orig.)

Development of residential solar air conditioning system for electricity power peak cut 3

Energy Technology Data Exchange (ETDEWEB)

Yu, Gwon Jong [Korea Inst. of Energy and Resources, Daeduk (Korea, Republic of)

1995-12-31

In this research, the converter rectifier unit of the inverter air conditioner is substituted into the bidirectional PWM converter. The DC/DC power converter is established on the DC link between the photovoltaic array and the inverter air conditioner, and the photovoltaic air conditioning system which can be parallel driven which utility is developed. (author). 35 ref., 112 figs.

Efficiency assessment of indoor environmental policy for air-conditioned offices in Hong Kong

International Nuclear Information System (INIS)

Wong, L.T.; Mui, K.W.

2009-01-01

To reduce carbon dioxide (CO 2 ) emissions through thermal energy conservation, air-conditioned offices in the subtropics are recommended to operate within specified ranges of indoor temperature, relative humidity and air velocity. As thermal discomfort leads to productivity loss, some indoor environmental policies for air-conditioned offices in Hong Kong are investigated in this study with relation to thermal energy consumption, CO 2 emissions from electricity use, and productivity loss due to thermal discomfort. Occupant thermal response is specifically considered as an adaptive factor in evaluating the energy consumption and productivity loss. The energy efficiency of an office is determined by the productivity which corresponds to the CO 2 generated. The results found that a policy with little impact on occupant thermal comfort and worker productivity would improve the office efficiency while the one with excessive energy consumption reduction would result in a substantial productivity loss. This study is a useful reference source for evaluating an indoor thermal environmental policy regarding the energy consumption, CO 2 emissions reduction, thermal comfort and productivity loss in air-conditioned offices in subtropical areas.

The study of operating an air conditioning system using Maisotsenko-Cycle

Science.gov (United States)

Khan, Mohammad S.; Tahan, Sami; Toufic El-Achkar, Mohamad; Abou Jamus, Saleh

2018-03-01

The project aims to design and build an air conditioning system that runs on the Maisotsenko cycle. The system is required to condition and cool down ambient air for a small residential space with the reduction in the use of electricity and eliminating the use of commercial refrigerants. This project can operate at its optimum performance in remote areas like oil diggers and other projects that run in the desert or any site that would not have a very high relative humidity level. The Maisotsenko cycle is known as the thermodynamic concept that captures energy from the air by using the psychometric renewable energy available in the latent heat in water evaporating in air. The heat and mass exchanger design was based on choosing a material that would-be water resistant and breathable, which was found to be layers of cardboard placed on top of each other and thus creating channels for air to pass through. Aiming for this design eliminates any high power electrical equipment such as compressors, condensers and evaporators that would be used in an AC system with the exception of a 600 W blower and a 10 W fan, thus making it a more environmentally friendly project. Moreover, the project is limited by the ambient temperature and humidity, as the model operates at an optimum when the relative humidity is lower.

Application of acoustic agglomeration to enhance air filtration efficiency in air-conditioning and mechanical ventilation (ACMV) systems.

Science.gov (United States)

Ng, Bing Feng; Xiong, Jin Wen; Wan, Man Pun

2017-01-01

The recent episodes of haze in Southeast Asia have caused some of the worst regional atmospheric pollution ever recorded in history. In order to control the levels of airborne fine particulate matters (PM) indoors, filtration systems providing high PM capturing efficiency are often sought, which inadvertently also results in high airflow resistance (or pressure drop) that increases the energy consumption for air distribution. A pre-conditioning mechanism promoting the formation of particle clusters to enhance PM capturing efficiency without adding flow resistance in the air distribution ductwork could provide an energy-efficient solution. This pre-conditioning mechanism can be fulfilled by acoustic agglomeration, which is a phenomenon that promotes the coagulation of suspended particles by acoustic waves propagating in the fluid medium. This paper discusses the basic mechanisms of acoustic agglomeration along with influencing factors that could affect the agglomeration efficiency. The feasibility to apply acoustic agglomeration to improve filtration in air-conditioning and mechanical ventilation (ACMV) systems is investigated experimentally in a small-scale wind tunnel. Experimental results indicate that this novel application of acoustic pre-conditioning improves the PM2.5 filtration efficiency of the test filters by up to 10% without introducing additional pressure drop. The fan energy savings from not having to switch to a high capturing efficiency filter largely outstrip the additional energy consumed by the acoustics system. This, as a whole, demonstrates potential energy savings from the combined acoustic-enhanced filtration system without compromising on PM capturing efficiency.

Application of acoustic agglomeration to enhance air filtration efficiency in air-conditioning and mechanical ventilation (ACMV systems.

Directory of Open Access Journals (Sweden)

Bing Feng Ng

Full Text Available The recent episodes of haze in Southeast Asia have caused some of the worst regional atmospheric pollution ever recorded in history. In order to control the levels of airborne fine particulate matters (PM indoors, filtration systems providing high PM capturing efficiency are often sought, which inadvertently also results in high airflow resistance (or pressure drop that increases the energy consumption for air distribution. A pre-conditioning mechanism promoting the formation of particle clusters to enhance PM capturing efficiency without adding flow resistance in the air distribution ductwork could provide an energy-efficient solution. This pre-conditioning mechanism can be fulfilled by acoustic agglomeration, which is a phenomenon that promotes the coagulation of suspended particles by acoustic waves propagating in the fluid medium. This paper discusses the basic mechanisms of acoustic agglomeration along with influencing factors that could affect the agglomeration efficiency. The feasibility to apply acoustic agglomeration to improve filtration in air-conditioning and mechanical ventilation (ACMV systems is investigated experimentally in a small-scale wind tunnel. Experimental results indicate that this novel application of acoustic pre-conditioning improves the PM2.5 filtration efficiency of the test filters by up to 10% without introducing additional pressure drop. The fan energy savings from not having to switch to a high capturing efficiency filter largely outstrip the additional energy consumed by the acoustics system. This, as a whole, demonstrates potential energy savings from the combined acoustic-enhanced filtration system without compromising on PM capturing efficiency.

Developed adaptive neuro-fuzzy algorithm to control air conditioning ...

African Journals Online (AJOL)

The paper developed artificial intelligence technique adaptive neuro-fuzzy controller for air conditioning systems at different pressures. The first order Sugeno fuzzy inference system was implemented and utilized for modeling and controller design. In addition, the estimation of the heat transfer rate and water mass flow rate ...

2012 German refrigeration and air conditioning meeting. Proceedings; Deutsche Kaelte-Klima-Tagung 2012 Tagungsbericht

Energy Technology Data Exchange (ETDEWEB)

NONE

2012-07-01

Within the DKV conference of the Deutscher Kaelte- und Klimatechnischer Verein e.V. (Hanover, Federal Republic of Germany) from 21st to 23rd November, 2012, in Wuerzburg (Federal Republic of Germany) 121 lectures were held according to the following themes: Measurement and process control in cryotechnology; energy storage and energy application; application of cryotechnology in biology and medicine, new concepts and plants; fundamentals and materials for the technology of cold pumps and heat pumps - pool boiling; flow boiling / CO{sub 2}; adsorption processes; adsorption processes / phase change materials; condensation / dehumidification; plants and components of the technology of cold pumps and heat pumps - compressors; expansion and regulation; heat exchanger and reflux cooling; heat exchangers; systems simulation; systems and materials; application of cold - energy controlling / application; foodstuff / supermarket; air conditionings of passenger cars; air-conditioning of electric-powered automobiles; railway air-conditioning / system analyses; standardization and regulations; air conditioning and application of heat pumps - regulation / hardware-in-the-loop; net-zero-energy building; building engineering and simulation; standardization / IAQ / building materials; heat pumps; thermal comfort and performance in office accommodations.

HVAC-DYNAMICS - a tool for quality assurance in relation to delivery of air-conditioning systems. [Heating, ventilating and air conditioning]. HVAC-DYNAMICS - et redskap for kvalitetsikring av sluttleveransen i klima-anlegg

Energy Technology Data Exchange (ETDEWEB)

Novakovic, V [SINTEF Varmeteknikk, Seksjon VVS (NO)

1990-07-01

HVAC-DYNAMICS is a computerized tool for quality assurance of the functioning of an air-conditioning system at the time of delivery. The system's efficiency in the case of fluctuating and critical operation is evaluated. The HVAC-DYNAMICS gives an optimal choice for air-conditioning systems regarding indoor climate, efficiency demands and energy consumption. The program can also be use for calibration of regulators, fault-finding, and training purposes. (CLS).

Commentary: Air-conditioning as a risk for increased use of healthservices

Energy Technology Data Exchange (ETDEWEB)

Mendell, Mark J.

2004-06-01

In this issue of the journal, Preziosi et al. [2004] report the first study to assess differences in the utilization of health care related to the presence of air-conditioning in office workplaces. Although the study was simple and cross-sectional, the data variables from questionnaires, and the findings subject to a variety of questions, the findings are striking enough to deserve clarification. The study used a large random national sample of French women assembled for another purpose (to study antioxidant nutrients and prevention of cancer and cardiovascular disease). Participants reported health services and health events in monthly questionnaires over 1 year, and in one questionnaire in the middle of that period also reported whether air-conditioning was in use at their workplace. Fifteen percent of participants reported air-conditioning at work. Analyses adjusting for age and smoking status of participants found increases in most outcomes assessed: use of specific kinds of physicians, sickness absence, and hospital stays. While the increases in odds ratios (OR) and 95% confidence intervals (CI) were statistically significant for only otorhinolaryngology [OR (95% CI) = 2.33 (1.35-4.04)] and sickness absence [1.70 (1.13-2.58)], other increases were notable--dermatology [1.6 (0.98-2.65)]; hospital stay [1.51 (0.92-2.45)], and pneumonology [2.10 (0.65-6.82)]. The least elevated outcomes were for general practice medicine [0.99 (0.65-1.48)] and global medical visits [1.18 (0.67-2.07)]. [Preziosi et al., 2004 ,(Table 2)] Odds ratios for relatively common health outcomes often lie farther from the null than the risk ratios most useful for quantifying the increase in risk. Risk ratios, or prevalence ratios (PRs, the equivalent measure of effect for cross-sectional data), have seldom been used because of the convenience and availability of logistic regression models that estimate odds ratios. With baseline prevalences ranging up to 85.7% in the data from Preziosi et

Design and Simulation of an Air Conditioning Project in a Hospital Based on Computational Fluid Dynamics

Directory of Open Access Journals (Sweden)

Ding X. R.

2017-06-01

Full Text Available This study aims to design a novel air cleaning facility which conforms to the current situation in China, and moreover can satisfy our demand on air purification under the condition of poor air quality, as well as discuss the development means of a prototype product. Air conditions in the operating room of a hospital were measured as the research subject of this study. First, a suitable turbulence model and boundary conditions were selected and computational fluid dynamics (CFD software was used to simulate indoor air distribution. The analysis and comparison of the simulation results suggested that increasing the area of air supply outlets and the number of return air inlets would not only increase the area of unidirectional flow region in main flow region, but also avoid an indoor vortex and turbulivity of the operating area. Based on the summary of heat and humidity management methods, the system operation mode and relevant parameter technologies as well as the characteristics of the thermal-humidity load of the operating room were analyzed and compiled. According to the load value and parameters of indoor design obtained after our calculations, the airflow distribution of purifying the air-conditioning system in a clean operating room was designed and checked. The research results suggested that the application of a secondary return air system in the summer could reduce energy consumption and be consistent with the concept of primaiy humidity control. This study analyzed the feasibility and energy conservation properties of cleaning air-conditioning technology in operating rooms, proposed some solutions to the problem, and performed a feasible simulation, which provides a reference for practical engineering.

Modeling validation and control analysis for controlled temperature and humidity of air conditioning system.

Science.gov (United States)

Lee, Jing-Nang; Lin, Tsung-Min; Chen, Chien-Chih

2014-01-01

This study constructs an energy based model of thermal system for controlled temperature and humidity air conditioning system, and introduces the influence of the mass flow rate, heater and humidifier for proposed control criteria to achieve the controlled temperature and humidity of air conditioning system. Then, the reliability of proposed thermal system model is established by both MATLAB dynamic simulation and the literature validation. Finally, the PID control strategy is applied for controlling the air mass flow rate, humidifying capacity, and heating, capacity. The simulation results show that the temperature and humidity are stable at 541 sec, the disturbance of temperature is only 0.14 °C, 0006 kg(w)/kg(da) in steady-state error of humidity ratio, and the error rate is only 7.5%. The results prove that the proposed system is an effective controlled temperature and humidity of an air conditioning system.

Modeling Validation and Control Analysis for Controlled Temperature and Humidity of Air Conditioning System

Directory of Open Access Journals (Sweden)

Jing-Nang Lee

2014-01-01

Full Text Available This study constructs an energy based model of thermal system for controlled temperature and humidity air conditioning system, and introduces the influence of the mass flow rate, heater and humidifier for proposed control criteria to achieve the controlled temperature and humidity of air conditioning system. Then, the reliability of proposed thermal system model is established by both MATLAB dynamic simulation and the literature validation. Finally, the PID control strategy is applied for controlling the air mass flow rate, humidifying capacity, and heating, capacity. The simulation results show that the temperature and humidity are stable at 541 sec, the disturbance of temperature is only 0.14°C, 0006 kgw/kgda in steady-state error of humidity ratio, and the error rate is only 7.5%. The results prove that the proposed system is an effective controlled temperature and humidity of an air conditioning system.

Air-conditioning and antibiotics: Demand management insights from problematic health and household cooling practices

International Nuclear Information System (INIS)

Nicholls, Larissa; Strengers, Yolande

2014-01-01

Air-conditioners and antibiotics are two technologies that have both been traditionally framed around individual health and comfort needs, despite aspects of their use contributing to social health problems. The imprudent use of antibiotics is threatening the capacity of the healthcare system internationally. Similarly, in Australia the increasing reliance on air-conditioning to maintain thermal comfort is contributing to rising peak demand and electricity prices, and is placing an inequitable health and financial burden on vulnerable heat-stressed households. This paper analyses policy responses to these problems through the lens of social practice theory. In the health sector, campaigns are attempting to emphasise the social health implications of antibiotic use. In considering this approach in relation to the problem of air-conditioned cooling and how to change the ways in which people keep cool during peak times, our analysis draws on interviews with 80 Australian households. We find that the problem of peak electricity demand may be reduced through attention to the social health implications of air-conditioned cooling on very hot days. We conclude that social practice theory offers a fruitful analytical route for identifying new avenues for research and informing policy responses to emerging health and environmental problems. - Highlights: • Over-use of antibiotics and air-conditioning has social health implications. • Focusing on financial incentives limits the potential of demand management programs. • Explaining peak demand to households shifts the meanings of cooling practices. • Emphasising the social health implications of antibiotics and air-conditioning may resurrect alternative practices. • Analysing policy with social practice theory offers insights into policy approaches

Flow and air conditioning simulations of computer turbinectomized nose models.

Science.gov (United States)

Pérez-Mota, J; Solorio-Ordaz, F; Cervantes-de Gortari, J

2018-04-16

Air conditioning for the human respiratory system is the most important function of the nose. When obstruction occurs in the nasal airway, turbinectomy is used to correct such pathology. However, mucosal atrophy may occur sometime after this surgery when it is overdone. There is not enough information about long-term recovery of nasal air conditioning performance after partial or total surgery. The purpose of this research was to assess if, based on the flow and temperature/humidity characteristics of the air intake to the choana, partial resection of turbinates is better than total resection. A normal nasal cavity geometry was digitized from tomographic scans and a model was printed in 3D. Dynamic (sinusoidal) laboratory tests and computer simulations of airflow were conducted with full agreement between numerical and experimental results. Computational adaptations were subsequently performed to represent six turbinectomy variations and a swollen nasal cavity case. Streamlines along the nasal cavity and temperature and humidity distributions at the choana indicated that the middle turbinate partial resection is the best alternative. These findings may facilitate the diagnosis of nasal obstruction and can be useful both to plan a turbinectomy and to reduce postoperative discomfort. Graphical Abstract ᅟ.

Fuzzy logic control of air-conditioning system in residential buildings

Directory of Open Access Journals (Sweden)

Abdel-Hamid Attia

2015-09-01

Full Text Available There has been a rising concern in reducing the energy consumption in building. Heating ventilation and air condition system is the biggest consumer of energy in building. In this study, fuzzy logic control of the air conditioning system of building for efficient energy operation and comfortable environment is investigated. A theoretical model of the fan coil unit (FCU and the heat transfer between air and coolant fluid is derived. The controlled variables are the room temperature and relative humidity and control consequents are the percentage of chilled and hot water flow rates at summer and the percentage of hot water and steam injected flow rates at winter. A computer simulation has been conducted and fuzzy control results are compared with that of conventional Proportional-Integral-Derivative control. It was found that the proposed control strategy satisfies the space load and at the same time to achieve the comfort zone, as defined by the ASHRAE code. Meanwhile PID control fails to adjust the room temperature at part-load operations. It has been demonstrated that fuzzy controller operation is more efficient and consumes less energy than PID control.

Developed adaptive neuro-fuzzy algorithm to control air conditioning ...

African Journals Online (AJOL)

user

... conditioning system is highly appreciated and essential in most of our daily life. ... (Hossien and Karla, 2012) presented an overview work which provides an .... energy balance for SSSF and the mass flow balance for the water in the air are ..... of Automatic Control and Electrical Engineering at Siegen University, Germany.

Thermal energy recovery of air conditioning system--heat recovery system calculation and phase change materials development

International Nuclear Information System (INIS)

Gu Zhaolin; Liu Hongjuan; Li Yun

2004-01-01

Latent heat thermal energy storage systems can be used to recover the rejected heat from air conditioning systems, which can be used to generate low-temperature hot water. It decreases not only the consumption of primary energy for heating domestic hot water but also the calefaction to the surroundings due to the rejection of heat from air conditioning systems. A recovery system using phase change materials (PCMs) to store the rejected (sensible and condensation) heat from air conditioning system has been developed and studied, making up the shortage of other sensible heat storage system. Also, PCMs compliant for heat recovery of air conditioning system should be developed. Technical grade paraffin wax has been discussed in this paper in order to develop a paraffin wax based PCM for the recovery of rejected heat from air conditioning systems. The thermal properties of technical grade paraffin wax and the mixtures of paraffin wax with lauric acid and with liquid paraffin (paraffin oil) are investigated and discussed, including volume expansion during the phase change process, the freezing point and the heat of fusion

Thermo economical evaluation of retrofitting strategies in air conditioning systems

Energy Technology Data Exchange (ETDEWEB)

Tribess, Arlindo; Fiorelli, Flavio Augusto Sanzogo; Hernandez Neto, Alberto [Sao Paulo Univ., SP (Brazil). Escola Politecnica. Dept. de Engenharia Mecanica]. E-mail: atribess@usp.br; fiorelli@usp.br; ahneto@usp.br

2000-07-01

In a building project, several subsystems are designed, among them the air conditioning system. Electrical energy consumption profiles show that this subsystem is responsible for 40 to 50% of total consumption in a commercial building. Besides the study of technical aspects that should be considered in order to assure the thermal comfort of the occupants as well the temperature and humidity conditions for an efficient equipment operation, an economical evaluation of this subsystem should be also made. In retrofit projects, the economical aspect is also critical for such projects in order to assure bigger efficiency in an economically attractive way. This paper analyses some strategies that might be adopted in retrofitting an air conditioning system installed in a commercial building with mixed occupation. By mixed we mean that some floors have a typical office occupation profile and other floors are mainly occupied by electronic equipment. This analysis includes both technical and economical evaluation. The proposed solutions performance are compared to the old system, which allows to verify the retrofitting impact in energy consumption reduction and its economical feasibility. (author)

The effect of inlet conditions on the air side hydraulic resistance and flow maldistribution in industrial air heaters

Energy Technology Data Exchange (ETDEWEB)

Hoffmann-Vocke, Jonas, E-mail: jh63@waikato.ac.nz [University of Waikato, Energy Research Group, School of Science and Engineering, Private Bag 3105, Hamilton 3240 (New Zealand); Neale, James, E-mail: jamesn@waikato.ac.nz [University of Waikato, Energy Research Group, School of Science and Engineering, Private Bag 3105, Hamilton 3240 (New Zealand); Walmsley, Michael, E-mail: walmsley@waikato.ac.nz [University of Waikato, Department of Engineering, School of Science and Engineering, Private Bag 3105, Hamilton 3240 (New Zealand)

2011-08-15

Highlights: > Measured the effects of air heater inlet header geometry on hydraulic performance. > Measured the effects of inlet header flow maldistribution on hydraulic performance. > Inlet header flow maldistribution increases air heater system hydraulic resistance. - Abstract: Experimental system hydraulic resistance measurements on a scale air heater unit have highlighted the excessive hydraulic resistance of typical industry configurations. Both poor header inlet conditions and large header expansion angles are shown to contribute to system hydraulic resistance magnitudes 20-100% higher than suitable benchmark cases. Typical centrifugal fan system efficiencies well under 80% multiply the system resistance effects resulting in larger fan power penalties. Velocity profile measurements taken upstream and downstream of the test heat exchanger under flow maldistribution conditions provide insight into the flow maldistribution spreading caused by the heat exchanger resistance. The anisotropic resistance of the plate fin-and-tube heat exchanger is shown to result in resistance induced flow dispersion being concentrated in the axis parallel to the plate fins.

The effect of inlet conditions on the air side hydraulic resistance and flow maldistribution in industrial air heaters

International Nuclear Information System (INIS)

Hoffmann-Vocke, Jonas; Neale, James; Walmsley, Michael

2011-01-01

Highlights: → Measured the effects of air heater inlet header geometry on hydraulic performance. → Measured the effects of inlet header flow maldistribution on hydraulic performance. → Inlet header flow maldistribution increases air heater system hydraulic resistance. - Abstract: Experimental system hydraulic resistance measurements on a scale air heater unit have highlighted the excessive hydraulic resistance of typical industry configurations. Both poor header inlet conditions and large header expansion angles are shown to contribute to system hydraulic resistance magnitudes 20-100% higher than suitable benchmark cases. Typical centrifugal fan system efficiencies well under 80% multiply the system resistance effects resulting in larger fan power penalties. Velocity profile measurements taken upstream and downstream of the test heat exchanger under flow maldistribution conditions provide insight into the flow maldistribution spreading caused by the heat exchanger resistance. The anisotropic resistance of the plate fin-and-tube heat exchanger is shown to result in resistance induced flow dispersion being concentrated in the axis parallel to the plate fins.

System and method for conditioning intake air to an internal combustion engine

Science.gov (United States)

Sellnau, Mark C.

2015-08-04

A system for conditioning the intake air to an internal combustion engine includes a means to boost the pressure of the intake air to the engine and a liquid cooled charge air cooler disposed between the output of the boost means and the charge air intake of the engine. Valves in the coolant system can be actuated so as to define a first configuration in which engine cooling is performed by coolant circulating in a first coolant loop at one temperature, and charge air cooling is performed by coolant flowing in a second coolant loop at a lower temperature. The valves can be actuated so as to define a second configuration in which coolant that has flowed through the engine can be routed through the charge air cooler. The temperature of intake air to the engine can be controlled over a wide range of engine operation.

Decoupling dehumidification and cooling for energy saving and desirable space air conditions in hot and humid Hong Kong

International Nuclear Information System (INIS)

Lee, W.L.; Chen Hua; Leung, Y.C.; Zhang, Y.

2012-01-01

Highlights: ► The combined use of dedicated ventilation and dry cooling (DCDV) system was investigated. ► Investigations were based actual equipment performance data and realistic building and system characteristics. ► DCDV system could save 54% of the annual energy use for air-conditioning. ► DCDV system could better achieve the desired space air conditions. ► DCDV system could decouple dehumidification and cooling. - Abstract: The combined use of dedicated outdoor air ventilation (DV) and dry cooling (DC) air-conditioning system to decouple sensible and latent cooling for desirable space air conditions, better indoor air quality, and energy efficiency is proposed for hot and humid climates like Hong Kong. In this study, the performance and energy saving potential of DCDV system in comparison to conventional systems (constant air volume (CAV) system with and without reheat) for air conditioning of a typical office building in Hong Kong are evaluated. Through hour-by-hour simulations, using actual equipment performance data and realistic building and system characteristics, the cooling load profile, resultant indoor air conditions, condensation at the DC coil, and energy consumptions are calculated and analyzed. The results indicate that with the use of DCDV system, the desirable indoor conditions could be achieved and the annual energy use could be reduced by 54% over CAV system with reheat. The condensate-free characteristic at the DC coil to reduce risk of catching disease could also be realized.

The effect of environmental parameters to dust concentration in air-conditioned space

Science.gov (United States)

Ismail, A. M. M.; Manssor, N. A. S.; Nalisa, A.; Yahaya, N.

2017-08-01

Malaysia has a wet and hot climate, therefore most of the spaces are air conditioned. The environment might affect dust concentration inside a space and affect the indoor air quality (IAQ). The main objective of this study is to study the dust concentration collected inside enclosed air-conditioned space. The measurement was done physically at four selected offices and two classrooms using a number of equipment to measure the dust concentration and environmental parameters which are temperature and relative air humidity. It was found that the highest dust concentration produced in office (temperature of 24.7°C, relative humidity of 66.5%) is 0.075 mg/m3, as compared to classroom, the highest dust concentration produced is 0.060 mg/m3 office (temperature of 25.9°C, relative humidity of 64.0%). However, both measurements show that value still within the safety level set by DOSH Malaysia (2005-2010) and ASHRAE 62.2 2016. The office contained higher dust concentration compared to classroom because of frequent movement transpires daily due to the functional of the offices.

Assessment of productivity loss in air-conditioned buildings using PMV index

Energy Technology Data Exchange (ETDEWEB)

Kosonen, R. [Halton OY, Kausala (Finland); Tan, F. [CapitaLand Commercial Limited, Singapore (Singapore)

2004-07-01

This theoretical study reports on the assessment of productivity loss in air-conditioned office buildings using the PMV approach and makes use of Wyon's reviews [D.P. Wyon, P.O. Fanger, B.W. Olesen, C.J.K. Pedersen, The mental performance of subjects clothed for comfort at two different air temperatures, Ergonomics 18 (1975) 358-374; D.P. Wyon, Individual microclimate control: required range, probable benefits and current feasibility, in: Proceedings of Indoor Air '96, Institute of Public Health, Tokyo, 1996; D.P. Wyon, Indoor environmental effects on productivity. IAQ 96 Paths to better building environments/Keynote address. Y. Kevin. Atlanta, ASHRAE, pp. 5-15] as the basis to compare and to relate how the productivity loss could be minimised through improved thermal comfort design criteria. The finding shows that task-related performance is significantly correlated with the human perception of thermal environment that in turn is dependent on temperatures. Different combinations of thermal criteria (air velocity, clo, metabolic, etc.) can lead to similar PMV value and the PMV equation is useful to predict productivity loss that is due to the rate of change in thermal conditions. The study also highlights the issues that remain to be resolved in future research. (author)

Energy and Greenhouse Gas Emission Assessment of Conventional and Solar Assisted Air Conditioning Systems

Directory of Open Access Journals (Sweden)

Xiaofeng Li

2015-11-01

Full Text Available Energy consumption in the buildings is responsible for 26% of Australia’s greenhouse gas emissions where cooling typically accounts for over 50% of the total building energy use. The aim of this study was to investigate the potential for reducing the cooling systems’ environmental footprint with applications of alternative renewable energy source. Three types of cooling systems, water cooled, air cooled and a hybrid solar-based air-conditioning system, with a total of six scenarios were designed in this work. The scenarios accounted for the types of power supply to the air-conditioning systems with electricity from the grid and with a solar power from highly integrated building photovoltaics (BIPV. Within and between these scenarios, systems’ energy performances were compared based on energy modelling while the harvesting potential of the renewable energy source was further predicted based on building’s detailed geometrical model. The results showed that renewable energy obtained via BIPV scenario could cover building’s annual electricity consumption for cooling and reduce 140 tonnes of greenhouse gas emissions each year. The hybrid solar air-conditioning system has higher energy efficiency than the air cooled chiller system but lower than the water cooled system.

Installation of PMV Operation Program in DDC Controller and Air Conditioning Control Using PMV Directly as Set Point

Science.gov (United States)

Haramoto, Ken-Ichi

In general, air conditioning control in a building is operated mainly by indoor air temperature control. Although the operators of the machine in the building accepted a claim for indoor air temperature presented by the building inhabitants, the indoor conditions have been often too cool or warm. Therefore, in an attempt to create better thermal environments, the author paid attention to the PMV that is a thermal comfort index. And then, the possibility of air conditioning control using the PMV directly as the set point was verified by employing actual equipment in an air conditioning testing room and an office building. Prior to the execution of this control, the operation program of the PMV was installed in a DDC controller for the air conditioning control. And information from indoor sensors and so on was inputted to the controller, and the computed PMV was used as the feedback variable.

Energy Performance and Optimal Control of Air-conditioned Buildings Integrated with Phase Change Materials

Science.gov (United States)

Zhu, Na

This thesis presents an overview of the previous research work on dynamic characteristics and energy performance of buildings due to the integration of PCMs. The research work on dynamic characteristics and energy performance of buildings using PCMs both with and without air-conditioning is reviewed. Since the particular interest in using PCMs for free cooling and peak load shifting, specific research efforts on both subjects are reviewed separately. A simplified physical dynamic model of building structures integrated with SSPCM (shaped-stabilized phase change material) is developed and validated in this study. The simplified physical model represents the wall by 3 resistances and 2 capacitances and the PCM layer by 4 resistances and 2 capacitances respectively while the key issue is the parameter identification of the model. This thesis also presents the studies on the thermodynamic characteristics of buildings enhanced by PCM and on the investigation of the impacts of PCM on the building cooling load and peak cooling demand at different climates and seasons as well as the optimal operation and control strategies to reduce the energy consumption and energy cost by reducing the air-conditioning energy consumption and peak load. An office building floor with typical variable air volume (VAV) air-conditioning system is used and simulated as the reference building in the comparison study. The envelopes of the studied building are further enhanced by integrating the PCM layers. The building system is tested in two selected cities of typical climates in China including Hong Kong and Beijing. The cold charge and discharge processes, the operation and control strategies of night ventilation and the air temperature set-point reset strategy for minimizing the energy consumption and electricity cost are studied. This thesis presents the simulation test platform, the test results on the cold storage and discharge processes, the air-conditioning energy consumption and demand

Determination of the ejector dimensions of a bus air-conditioning system using analytical and numerical methods

International Nuclear Information System (INIS)

Ünal, Şaban

2015-01-01

Comfortable journey with commercial buses is an essential goal of transportation companies. An air-conditioning system can play an important role for this comfortable journey but it can put extra load on the engine and extra cost in the fuel consumption. The purpose of this work is to increase the performance of air-conditioning system of the buses by reducing the load on the engine and fuel consumption. Using a two-phase ejector as an expansion valve can increase the coefficient of performance (COP) of the air-conditioning system. An improvement in the COP can reduce the empty vehicle weight and fuel consumption of buses. Two-phase ejector dimensions can be determined using the empirical methods available in the literature. In this paper, the two-phase ejector dimensions of air conditioning system for a bus are calculated using the analytical and numerical methods. First of all, the thermodynamic analysis of the vapor-compression refrigeration cycle with a two-phase ejector is performed, and then the ejector dimensions are subsequently determined. The cooling loads of the midibus and bus with R134a as a refrigerant are assumed to be 14 kW and 32 kW, respectively. The total length of the two-phase ejector for the midibuses and buses due to these cooling loads, are computed to be 480.8 mm and 793.1 mm, respectively. Also, an experimental setup is installed on a midibus air conditioner to turn it into the ejector air conditioning system to validate theoretical results with the experimental study. - Highlights: • Determination of two-phase ejector dimensions of a bus air-conditioning system. • Thermodynamic analysis of the two-phase ejector cooling system. • Experimental study on a midibus air conditioner using two-phase ejector.

Techno-economic analysis of a 2.1 kW rooftop photovoltaic-grid-tied system based on actual performance

International Nuclear Information System (INIS)

Adaramola, Muyiwa S.

2015-01-01

Highlights: • The economic analysis of rooftop PV grid-tied installation is examined. • Based on actual performance, the LCOE of the system is estimated as US$0.246/kW h. • Feed-in-tariff of US$0.356/kW h is estimated with no financial support. • To encourage installation of PV system, financial support of up to 40% of the investment is suggested. - Abstract: As more attention is being focus on the development of renewable energy resources globally, technical and economic assessments of these resources are crucial to ascertain their viability. These assessments can be more meaningful, if they are based on field and actual performance of the renewable energy conversion systems. This study presents the economic analysis of a rooftop 2.07 kW grid-connected photovoltaic energy system installation located in Ås (59.65°N and longitude 10.76°E, and about 105 m above sea level), Norway. Both the annual and monthly costs of energy produced by the system are determined. In addition, the feed-in tariff that can give internal rate of return of about 7.5% on investment on this installation was examined. Based on assumptions used in this study, feed-in-tariff of US$0.356/kW h is estimated for a project with economic life of 25 years with no other financial support. This translates to US$0.110/kW h premium over the levelized cost of energy of US$0.246/kW h generated by the system. However, if the financial support is more than 45% of the initial investment cost, no further premium fee is necessary to support this type of system

Analysis of the photovoltaic solar energy capacity of residential rooftops in Andalusia (Spain)

Energy Technology Data Exchange (ETDEWEB)

Ordonez, J.; Jadraque, E.; Alegre, J.; Martinez, G. [Department of Civil Engineering, University of Granada (Spain)

2010-09-15

Fossil fuel energy resources are becoming increasingly scarce. Given the negative environmental impacts (e.g. greenhouse gas emissions) that accompany their use, it is hardly surprising that the development of renewable energies has become a major priority in the world today. Andalusia, with a mean solar radiation of 4.75 kWh/m{sup 2} per day and a surface area of 87,597 km{sup 2}, is the region in Europe with the highest solar energy potential. This research study determined the solar energy potential in Andalusia for grid-connected photovoltaic systems installed on residential rooftops. A methodology was developed for this purpose, which first involved a description of building characteristics, followed by the calculation of the useful roof surface area where photovoltaic arrays could be installed. In the next phase of the study, the mean solar irradiation characteristics were defined as well as the technical parameters of the photovoltaic systems. All of these factors allowed us to estimate the amount of electricity that could be potentially generated per year by solar panels. (author)

Dictionary of heating and air conditioning. Woerterbuch der Heizungs- und Klimatechnik

Energy Technology Data Exchange (ETDEWEB)

Laege, K

1981-01-01

This German-English and English-German dictionary includes some 4000 technical terms of the field of heating and air conditioning engineering. It represents the latest state of this technical terminology.

Step response and frequency response of an air conditioning system

NARCIS (Netherlands)

Crommelin, R.D.; Jackman, P.J.

1978-01-01

A system of induction units of an existing air conditioning system has been analyzed with respect to its dynamic properties. Time constants were calculated and measured by analogue models. Comparison with measurements at the installation itself showed a reasonable agreement. Frequency responses were

Design of energy efficient ventilation and air-conditioning systems

CERN Document Server

Seppänen, Olli; Bertilsson, Thore; Maripuu, Mari-Liis; Lamy, Hervé; Vanden Borre, Alex

2012-01-01

This guidebook covers numerous system components of ventilation and air-conditioning systems and shows how they can be improved by applying the latest technology products. Special attention is paid to details, which are often overlooked in the daily design practice, resulting in poor performance of high quality products once they are installed in the building system.

Characteristic Evaluation on the Cooling Performance of an Electrical Air Conditioning System Using R744 for a Fuel Cell Electric Vehicle

Directory of Open Access Journals (Sweden)

Moo-Yeon Lee

2012-05-01

Full Text Available The objective of this study was to investigate the cooling performance characteristics of an electrical air conditioning system using R744 as an alternative of R-134a for a fuel cell electric vehicle. In order to analyze the cooling performance characteristics of the air conditioning system using R744 for a fuel cell electric vehicle, an electrical air conditioning system using R744 was developed and tested under various operating conditions according to both inlet air conditions of the gas cooler and evaporator and compressor speed. The cooling capacity and coefficient of performance (COP forcooling of the tested air conditioning system were up to 6.4 kW and 2.5, respectively. In addition, the electrical air conditioning system with R744 using an inverter driven compressor showed better performance than the conventional air conditioning system with R-134a under the same operating conditions. The observed cooling performance of the developed electrical air conditioning system was found to be sufficient for cooling loads under various real driving conditions for a fuel cell electric vehicle.

Achieving better energy-efficient air conditioning – A review of technologies and strategies

International Nuclear Information System (INIS)

Chua, K.J.; Chou, S.K.; Yang, W.M.; Yan, J.

2013-01-01

Air conditioning is essential for maintaining thermal comfort in indoor environments, particularly for hot and humid climates. Today, air conditioning, comprising cooling and dehumidification, has become a necessity in commercial and residential buildings and industrial processes. It accounts for a major share of the energy consumption of a building or facility. In tropical climates, the energy consumed by heating, ventilation and air-conditioning (HVAC) can exceed 50% of the total energy consumption of a building. This significant figure is primarily due to the heavy duty placed on cooling technologies to remove both sensible and latent heat loads. Therefore, there is tremendous potential to improve the overall efficiency of the air-conditioning systems in buildings. Based on today’s practical technology for cooling, the major components of a chiller plant are (1) compressors, (2) cooling towers, (3) pumps (chilled and cooling water) and (4) fans in air handling units. They all consume mainly electricity to operate. When specifying the kW/R ton of a plant, there are two levels of monitoring cooling efficiency: (1) at the efficiency of the chiller machines or the compressors which consume a major amount of electricity; and (2) at the overall efficiency of cooling plants which include the cooling towers, pumps for moving coolant (chilled and cooling water) to all air-handling units. Pragmatically, a holistic approach is necessary towards achieving a low energy input per cooling achieved such as 0.6 kW/R ton cooling or lower by considering all aspects of the cooling plant. In this paper, we present a review of recent innovative cooling technology and strategies that could potentially lower the kW/R ton of cooling systems – from the existing mean of 0.9 kW/R ton towards 0.6 kW/R ton or lower. The paper, broadly divided into three key sections (see Fig. 2), begins with a review of the recent novel devices that enhances the energy efficiency of cooling systems at

Performance assessment of a solar-powered air quality and weather station placed on a school rooftop in Hong Kong

Science.gov (United States)

Emerging air pollution measurement technologies that require minimal infrastructure to deploy may lead to new insights on air pollution spatial variability in urban areas. Through a collaboration between the USEPA and HKEPD, this study evaluates the performance of a compact, roo...

Transitioning to Low-GWP Alternatives in Motor Vehicle Air Conditioning Systems

Science.gov (United States)

This fact sheet provides information on low-GWP alternatives in newly manufactured motor vehicle air conditioning systems. It discusses HFC alternatives, market trends, challenges to market entry for alternatives, and potential solutions.

Energy managemant through PCM based thermal storage system for building air-conditioning: Tidel Park, Chennai

International Nuclear Information System (INIS)

Nallusamy, N.; Sampath, S.; Velraj, R.

2006-01-01

Many modern building are designed for air-conditioning and the amount of electrical energy required for providing air-conditioning can be very significant especially in the tropics. Conservation of energy is major concern to improve the overall efficiency of the system. Integration is energy storage with the conventional system gives a lot of potential for energy saving and long-term economics. Thermal energy storage systems can improve energy management and help in matching supply and demand patterns. In the present work, a detailed study has been done on the existing thermal energy storage system used in the air-conditioning system in Tidel Park, Chennai. The present study focuses on the cool energy storage system. The modes of operation and advantages of such a system for energy management are highlighted. The reason for the adoption of combined storage system and the size of the storage medium in the air-conditioning plant are analyzed. The possibility of using this concept in other cooling and heating applications, such as storage type solar water heating system, has been explored

The Histoty of Ventilation and Air Conditioning is CERN Up to Date with the latest Technological Developments?

CERN Document Server

Kühnl-Kinel, J

2000-01-01

The invention of ventilation cannot be ascribed to a certain date. It started with simple aeration when man brought fire into his abode and continued through different stages including air cooling using ice to finally arrive at the time when ventilation and air conditioning has become an essential part of our life and plays an important role in human evolution. This paper presents the history of ventilation and air conditioning, explains the key constraints over the centuries, and shows its influence on everyday life. Some examples of previous air-conditioning plants are described and different approaches to the way of calculation of ventilation systems discussed. It gives an overview of the Heating, Ventilation and Air Conditioning (HVAC) installations at CERN and points out their particularities. It also compares them with the latest technological developments in the field as well as showing the new trends that are being applied at CERN.

A questionnaire survey on sleeping thermal environment and bedroom air conditioning in high-rise residences in Hong Kong

Energy Technology Data Exchange (ETDEWEB)

Lin, Z. [Institute of Heating, Ventilation, Air Conditioning and Gas Engineering, Tongji University, Shanghai (China); Deng, S. [Department of Building Services Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR (China)

2006-07-01

This paper reports on the results of a questionnaire survey on sleeping thermal environment and bedroom air conditioning in high-rise residential buildings in Hong Kong. The survey aimed at investigating the current situation of sleeping thermal environment and bedroom air conditioning, in order to gather relevant background information to develop strategies for bedroom air conditioning in the subtropics. It focused on the use patterns and types of bedroom air conditioning systems used, human factors such as the use of bedding and sleep wear during sleep, preference for indoor air temperature settings in bedrooms, ventilation control at nighttime with room air conditioner (RAC) turned on, etc. The results of the survey showed that most of the respondents would prefer a relatively low indoor air temperature at below 24 {sup o}C. Most of the respondents might however not be satisfied with the indoor air quality (IAQ) in bedrooms in Hong Kong. On the other hand, 68% of the respondents did not use any ventilation control intentionally during their sleep with their RACs turned on. A lack of knowledge of the ventilation control devices provided on window type room air conditioners (WRACs) indicated an urgent need for user education. (author)

MODELING THE AMBIENT CONDITION EFFECTS OF AN AIR-COOLED NATURAL CIRCULATION SYSTEM

Energy Technology Data Exchange (ETDEWEB)

Hu, Rui; Lisowski, Darius D.; Bucknor, Matthew; Kraus, Adam R.; Lv, Qiuping

2017-07-02

The Reactor Cavity Cooling System (RCCS) is a passive safety concept under consideration for the overall safety strategy of advanced reactors such as the High Temperature Gas-Cooled Reactor (HTGR). One such variant, air-cooled RCCS, uses natural convection to drive the flow of air from outside the reactor building to remove decay heat during normal operation and accident scenarios. The Natural convection Shutdown heat removal Test Facility (NSTF) at Argonne National Laboratory (“Argonne”) is a half-scale model of the primary features of one conceptual air-cooled RCCS design. The facility was constructed to carry out highly instrumented experiments to study the performance of the RCCS concept for reactor decay heat removal that relies on natural convection cooling. Parallel modeling and simulation efforts were performed to support the design, operation, and analysis of the natural convection system. Throughout the testing program, strong influences of ambient conditions were observed in the experimental data when baseline tests were repeated under the same test procedures. Thus, significant analysis efforts were devoted to gaining a better understanding of these influences and the subsequent response of the NSTF to ambient conditions. It was determined that air humidity had negligible impacts on NSTF system performance and therefore did not warrant consideration in the models. However, temperature differences between the building exterior and interior air, along with the outside wind speed, were shown to be dominant factors. Combining the stack and wind effects together, an empirical model was developed based on theoretical considerations and using experimental data to correlate zero-power system flow rates with ambient meteorological conditions. Some coefficients in the model were obtained based on best fitting the experimental data. The predictive capability of the empirical model was demonstrated by applying it to the new set of experimental data. The

CFD study on the effects of boundary conditions on air flow through an air-cooled condenser

Science.gov (United States)

Sumara, Zdeněk; Šochman, Michal

2018-06-01

This study focuses on the effects of boundary conditions on effectiveness of an air-cooled condenser (ACC). Heat duty of ACC is very often calculated for ideal uniform velocity field which does not correspond to reality. Therefore, this study studies the effect of wind and different landscapes on air flow through ACC. For this study software OpenFOAM was used and the flow was simulated with the use of RANS equations. For verification of numerical setup a model of one ACC cell with dimensions of platform 1.5×1.5 [m] was used. In this experiment static pressures behind fan and air flows through a model of surface of condenser for different rpm of fan were measured. In OpenFOAM software a virtual clone of this experiment was built and different meshes, turbulent models and numerical schemes were tested. After tuning up numerical setup virtual model of real ACC system was built. Influence of wind, landscape and height of ACC on air flow through ACC has been investigated.

Energy problems of the central systems of air conditioning; Problemas energeticos de los sistemas centrales de climatizacion

Energy Technology Data Exchange (ETDEWEB)

Cardero Corria, Gaspar [Cubanacan, S.A., Varadero (Cuba)

2003-07-01

The central systems of air conditioning are widely used in air conditioning production for several reasons among which excel: 1) Better aesthetic of the building, 2) Less noise in the air conditioning premises and 3) Greater yield of the consumed energy. This is indeed the third reason in which this paper will try to contribute with elements that will allow reveal the problem and to identify some possible causes that originate it. The centralized systems of air conditioning must produce conditioned air with lesser power cost than the individual systems, it is that saving which allows to recover an investment that normally surpasses them in 3 to 5 times. Nevertheless, the real numbers do not demonstrate that. [Spanish] Los sistemas centrales de climatizacion son ampliamente usados en la produccion de aire acondicionado por varias razones entre las que sobresalen: 1) Mejor estetica del edificio, 2) Menor ruido en los locales climatizados y 3) Mayor rendimiento de la energia consumida. Es precisamente la tercera razon en la cual este trabajo intentara aportar elementos que permitan develar el problema e identificar algunas posibles causas que lo originan. Los sistemas centralizados de climatizacion deben producir aire acondicionado con un menor gasto energetico que los sistemas individuales, es precisamente ese ahorro lo que permite recuperar una inversion que normalmente los supera en 3 a 5 veces. Sin embargo, los numeros reales no demuestran eso.

Study of a vapor-compression air-conditioning system for jetliners

Energy Technology Data Exchange (ETDEWEB)

Roeyttae, P.

2009-07-01

Most modern passenger aeroplanes use air cycle cooling. A high-speed air cycle is a reliable and light option, but not very efficient. This thesis presents research work done to design a novel vapour cooling cycle for aeroplanes. Due to advancements in high-speed permanent magnet motors, the vapour cycle is seen as a competitive option for the air cycle in aeroplanes. The aerospace industry placews tighter demands on the weight, reliability and environmental effects of the machinery than those met by conventional chillers, and thus modifications to conventional design are needed. The thesis is divided into four parts: the initial screening of the working fluid, 1-D design and performance values of the compressor, 1-D off-design value predictions of the compressor and the 3-D design of the compressor. The R24fa was selected as the working fluid based the study. The off-design range of the compressor was predicted to be wide and suitable for the application. The air-conditioning system developed is considerably smaller than previous designs using centrifugal compressors. (orig.)

Model development for air conditioning system in heavy duty trucks

NARCIS (Netherlands)

Kessels, J.T.B.A.; van den Bosch, P.P.J.; Zhang, Quansheng; Li, Shengbo Eben; Deng, Kun

2016-01-01

This chapter presents a modelling approach for the air conditioning (AC) system in heavy duty trucks. The presented model entails two major elements: a mechanical compressor model and a thermal AC model. The compressor model describes the massflow of the refrigerant as well as the mechanical power

Performance improvement of a hybrid air conditioning system using the indirect evaporative cooler with internal baffles as a pre-cooling unit

Directory of Open Access Journals (Sweden)

A.E. Kabeel

2017-12-01

Full Text Available In the present paper, the effects of the indirect evaporative cooler with internal baffle on the performance of the hybrid air conditioning system are numerically investigated. The hybrid air conditioning system contains two indirect evaporative coolers with internal baffle, one is utilized to pre-cool the air inlet to the desiccant wheel and the other is utilized to pre-cool the supply air inlet to the room. The effects of the inlet conditions of the process and reactivation air and working air ratio on the thermal performance of the hybrid air conditioning system have been analyzed. The results of this study show that in the hybrid air conditioning system for using the indirect evaporative cooler with internal baffle as a pre-cooling unit, the supply air temperature reduced by 21% and the coefficient of performance improved by 71% as compared to previous designs of the hybrid air conditioning system at the same inlet conditions. For increasing process air inlet temperature from 25 °C to 45 °C, supply air temperature increases from 12.7 °C to 14.2 °C, thermal COP increases from 1.87 to 2.84, and supply air relative humidity increases from 76.7% to 77.4%. Also, for increasing the reactivation air inlet temperature from 70 °C to 110 °C, supply air temperature dropped from 15.9 °C to 10.9 °C, supply air relative humidity dropped from 82.7% to 71.8%, and thermal COP dropped from 4.5 to 1.7. The recommended optimal air working ratio in the indirect evaporative cooler with internal baffle should be 0.15. Keywords: Desiccant material, Solar air collector, Evaporative cooler, Internal baffles, Air conditioning

The application of condensate water as an additional cooling media intermittently in condenser of a split air conditioning

Science.gov (United States)

Ardita, I. N.; Subagia, I. W. A.

2018-01-01

The condensate water produced by indoor a split air conditioning is usually not utilized and thrown away into the environment. The result of measurement shows that the temperature of condensate water produced by split air conditioning is quite low, that is 19-22 °C at the rate of 16-20 mL / min and it has PH balance. Under such conditions, Air Condensate produced by split air conditioning should still be recovered as an additional cooling medium on the condenser. This research will re-investigate the use of condensate water as an intermittent additional cooling of the condenser to increase the cooling capacity and performance of the air conditioning system. This research is done by experimental method whose implementation includes; designing and manufacturing of experimental equipment, mounting measuring tools, experimental data retrieval, data processing and yield analysis. The experimental results show that the use of condensate water as an intermittent additional cooling medium on split air conditioning condenser can increase the refrigeration effect about 2%, cooling capacity about 4% and 7% of COP system. Experimental results also show a decrease in power consumption in the system compressor about 3%

Statistical modeling of urban air temperature distributions under different synoptic conditions

Science.gov (United States)

Beck, Christoph; Breitner, Susanne; Cyrys, Josef; Hald, Cornelius; Hartz, Uwe; Jacobeit, Jucundus; Richter, Katja; Schneider, Alexandra; Wolf, Kathrin

2015-04-01

Within urban areas air temperature may vary distinctly between different locations. These intra-urban air temperature variations partly reach magnitudes that are relevant with respect to human thermal comfort. Therefore and furthermore taking into account potential interrelations with other health related environmental factors (e.g. air quality) it is important to estimate spatial patterns of intra-urban air temperature distributions that may be incorporated into urban planning processes. In this contribution we present an approach to estimate spatial temperature distributions in the urban area of Augsburg (Germany) by means of statistical modeling. At 36 locations in the urban area of Augsburg air temperatures are measured with high temporal resolution (4 min.) since December 2012. These 36 locations represent different typical urban land use characteristics in terms of varying percentage coverages of different land cover categories (e.g. impervious, built-up, vegetated). Percentage coverages of these land cover categories have been extracted from different sources (Open Street Map, European Urban Atlas, Urban Morphological Zones) for regular grids of varying size (50, 100, 200 meter horizonal resolution) for the urban area of Augsburg. It is well known from numerous studies that land use characteristics have a distinct influence on air temperature and as well other climatic variables at a certain location. Therefore air temperatures at the 36 locations are modeled utilizing land use characteristics (percentage coverages of land cover categories) as predictor variables in Stepwise Multiple Regression models and in Random Forest based model approaches. After model evaluation via cross-validation appropriate statistical models are applied to gridded land use data to derive spatial urban air temperature distributions. Varying models are tested and applied for different seasons and times of the day and also for different synoptic conditions (e.g. clear and calm

[Influence of industrial pollution of ambient air on health of workers engaged into open air activities in cold conditions].

Science.gov (United States)

Chashchin, V P; Siurin, S A; Gudkov, A B; Popova, O N; Voronin, A Iu

2014-01-01

The article presents the results of a study on assessment of occupational exposure to air pollutants and related health effects in3792 outdoor workers engaged in operations performed in the vicinity of non-ferrous metallurgical facilities in Far North. Findings are that during cold season repeated climate and weather conditions are associated with higher level of chemical hazards and dust in surface air. At the air temperature below -17 degrees C, maximal single concentrations of major pollutants can exceed MAC up to 10 times. With that, transitory disablement morbidity parameters and occupational accidents frequency increase significantly. The workers with long exposure to cooling meteorological factors and air pollution demonstrate significantly increased prevalence of respiratory and circulatory diseases, despite relatively low levels of sculpture dioxide and dust in the air, not exceeding the occupational exposure limits. It has been concluded that severe cold is to be considered asa factor increasing occupational risk at air polluted outdoor worksites dueto more intense air pollution, higher traumatism risk and lower efficiency of filter antidust masks respiratory PPE and due to modification of the toxic effects.

Management of air-conditioning systems in residential buildings by using fuzzy logic

Directory of Open Access Journals (Sweden)

Sohair F. Rezeka

2015-06-01

Full Text Available There has been a rising concern in reducing the energy consumption in buildings. Heating, ventilation and air-conditioning system is the biggest consumer of energy in buildings. In this study, management of the air-conditioning system of a building for efficient energy operation and comfortable environment is investigated. The strategy used in this work depends on classifying the rooms to three different groups: very important rooms, important rooms and normal rooms. The total mass flow rate is divided between all rooms by certain percentage using a fuzzy-logic system to get the optimum performance for each room. The suggested Building Management System (BMS was found capable of keeping errors in both temperature and humidity within the acceptable limits at different operating conditions. The BMS can save the chilled/hot water flow rate and the cooling/heating capacity of rooms.

Performance of alternative refrigerants for residential air-conditioning applications

International Nuclear Information System (INIS)

Park, Ki-Jung; Seo, Taebeom; Jung, Dongsoo

2007-01-01

In this study, performances of two pure hydrocarbons and seven mixtures composed of propylene, propane, HFC152a, and dimethylether were measured to substitute for HCFC22 in residential air-conditioners and heat pumps. Thermodynamic cycle analysis was carried out to determine the optimum compositions before testing and actual tests were performed in a breadboard-type laboratory heat pump/air-conditioner at the evaporation and condensation temperatures of 7 and 45 deg. C, respectively. Test results show that the coefficient of performance of these mixtures is up to 5.7% higher than that of HCFC22. While propane showed a 11.5% reduction in capacity, most of the fluids had a similar capacity to that of HCFC22. For these fluids, compressor-discharge temperatures were reduced by 11-17 deg. C. For all fluids tested, the amount of charge was reduced by up to 55% as compared to HCFC22. Overall, these fluids provide good performances with reasonable energy-savings without any environmental problem and thus can be used as long-term alternatives for residential air-conditioning and heat-pumping applications

Influence of Mean Rooftop-Level Estimation Method on Sensible Heat Flux Retrieved from a Large-Aperture Scintillometer Over a City Centre

Science.gov (United States)

Zieliński, Mariusz; Fortuniak, Krzysztof; Pawlak, Włodzimierz; Siedlecki, Mariusz

2017-08-01

The sensible heat flux ( H) is determined using large-aperture scintillometer (LAS) measurements over a city centre for eight different computation scenarios. The scenarios are based on different approaches of the mean rooftop-level (zH) estimation for the LAS path. Here, zH is determined separately for wind directions perpendicular (two zones) and parallel (one zone) to the optical beam to reflect the variation in topography and building height on both sides of the LAS path. Two methods of zH estimation are analyzed: (1) average building profiles; (2) weighted-average building height within a 250 m radius from points located every 50 m along the optical beam, or the centre of a certain zone (in the case of a wind direction perpendicular to the path). The sensible heat flux is computed separately using the friction velocity determined with the eddy-covariance method and the iterative procedure. The sensitivity of the sensible heat flux and the extent of the scintillometer source area to different computation scenarios are analyzed. Differences reaching up to 7% between heat fluxes computed with different scenarios were found. The mean rooftop-level estimation method has a smaller influence on the sensible heat flux (-4 to 5%) than the area used for the zH computation (-5 to 7%). For the source-area extent, the discrepancies between respective scenarios reached a similar magnitude. The results demonstrate the value of the approach in which zH is estimated separately for wind directions parallel and perpendicular to the LAS optical beam.

Effects of air flow maldistribution on refrigeration system dynamics of air source heat pump chiller under frosting conditions

International Nuclear Information System (INIS)

Gong Jianying; Gao Tieyu; Yuan Xiuling; Huang Dong

2008-01-01

The effects of air flow maldistribution on the performance of an air source heat pump chiller under frosting conditions were investigated experimentally. The results indicated that air flow maldistribution was the dominant factor leading to hunting of the thermostatic expansion valve for medium and/or large size finned tube evaporators. With air flow maldistribution degree (AMD) increasing, frost occurred earlier, and the frost layer grew faster. The operating characteristics became lower when AMD was increased. We found such phenomenon seemed to be related to both the difference of refrigerant outlet superheat and the frosting velocity. In the hunting stage, the frost block effect became the main factor degrading the refrigeration system performance. With AMD increasing, the heat pump system pertinent performance data (suction pressure, evaporation temperature, discharge pressure, refrigerant outlet temperature, etc.) were degraded more dramatically

The effect of air dried conditions on mechanical and physical ...

African Journals Online (AJOL)

STORAGESEVER

2009-04-20

Apr 20, 2009 ... small dimension wooden material is used and this affects the cost of ... The first serious application of laminating technique ... buildings, stock hangar, farms and stables constructions ... resistant lamine elements to air dried condition were easy .... the other was organic solvent water repellent protim WR230.

Operational experience of air washer based ventilation system for power conditioning system of Indus-2

International Nuclear Information System (INIS)

Pandey, R.M.; Baghel, S.L.; Parate, J.K.; Ahlawat, Sandeep; Rawlani, B.K.; Chouksey, Sanjay

2015-01-01

Indus-2 Synchrotron Accelerator requires high quality conditioned uninterrupted AC mains power for their smooth and reliable operation. Three units of 1670 kVA and one unit of 1100 kVA capacity rotary uninterruptible power conditioning systems (UPS) were installed and commissioned. These UPS units require dust free and cool ambient conditions for smooth operation. In order to meet the ventilation requirements, an evaporative cooling system of 80000 cubic meter/hour capacity with filtration units was designed, installed and commissioned in February 2011 and is operational on round-the-clock basis. Evaporative cooling scheme was chosen as has various advantages over a refrigerated system like lower initial capital costs, lower energy usage, lower running costs, less greenhouse gas and it does not contribute to ozone depletion. The ventilation system filters the environment air in stages up to 5 micron level and being conditioned with an automatic controlled soft water circulating system with cooling pads. An instrumentation and control scheme is included in the system to provide the automation requirements for operating 24 x 7 through the year. All the mechanical, hydraulic and electrical devices are maintained by providing preventive maintenance work without affecting the accelerator machine operation. Availability and reliability of the system was analysed based on the failure data. In Year 2014, the ventilation system was upgraded to accommodate standby blower unit, coupling unit and improved quality of supply air with new air conditioning devices. The control panel monitors the condition of air in the UPS hall and maintainsup to 28°C air temperature and 85% maximum relative humidity in round-the clock shift with more than 98% operational reliability. In this paper, we present design philosophy, installation, instrumentation, testing, operation experience and availability of the ventilation system for Power Conditioning System, Indus complex. (author)

A basic condition-based maintenance strategy for air-cooled turbine generators

International Nuclear Information System (INIS)

Laird, T.; Griffith, G.; Hoof, M.

2005-01-01

This paper discusses the methods of using condition-based maintenance (CBM) for turbine generators. Even though it is focused on the maintenance strategy for air-cooled generators, all types of power producers can realize benefits from a better maintenance strategy at lower costs. A reliable assessment of the actual unit condition requires detailed knowledge of the unit design, operational weaknesses, cost of maintenance and operational capabilities. (author)

Techno-economical Analysis of Rooftop Grid-connected PV Dairy Farms; Case Study of Urmia University Dairy Farm

Science.gov (United States)

Nikbakht, A. M.; Aste, N.; Sarnavi, H. J.; Leonforte, F.

2017-08-01

The global trends indicate a growing commitment to renewable energy development because of declining fossil fuels and environmental threats. Moreover, the global demographic growth coupled with rising demands for food has escalated the rate of energy consumption in food section. This study aims to investigate the techno-economic impacts of a grid-connected rooftop PV plan applied for a educational dairy farm in Urmia university, with total estimated annual electrical energy consumption of 18,283 kWh, located at the north west part of Iran. Based on the current feed-in tariff and tremendously low electricity price in agriculture section in Iran, the plants with size ranged from 14.4 to 19.7 kWp (initial investment ranged from 26,000 to 36,000 USD) would be satisfied economically.

Thermodynamic analysis of an innovative liquid desiccant air conditioning system to supply potable water

International Nuclear Information System (INIS)

Ahmed, M.A.; Gandhidasan, P.; Zubair, Syed M.; Bahaidarah, Haitham M.

2017-01-01

Highlights: • The study objective is to reduce the energy consumption of desiccant AC system. • Heat and mass losses are recovered in the proposed system using a condenser. • The conventional and the proposed systems are compared in terms of COP. • The proposed system performance is better than the conventional system. • The proposed system produces freshwater in addition to space cooling. - Abstract: Liquid desiccant air conditioning systems are cost-effective, environmentally friendly and energy efficient techniques, especially in coastal areas. In the conventional liquid desiccant air conditioning system, the scavenging air is expelled into the atmosphere carrying a considerable amount of energy and water vapor. Thus, there is plenty of room to improve the system performance by recovering these losses. The proposed system consists of a conventional liquid desiccant air conditioning system plus a condenser. The aim of this study is to reduce the energy consumption by recovering the heat from the scavenging air using the condenser while also producing freshwater in addition to space cooling. Lithium chloride (LiCl) is used as the liquid desiccant for this study. The mathematical formulation for simultaneous heat and mass transfer between the condenser and the regenerator was developed to establish a comparison between the performance of the conventional and modified systems. Using the generated model, it is found that the modified system performance is 11.25% better than the conventional system and that it produces 86.4 kg of freshwater per hour as a by-product under the given conditions.

Experimental performance study of a proposed desiccant based air conditioning system.

Science.gov (United States)

Bassuoni, M M

2014-01-01

An experimental investigation on the performance of a proposed hybrid desiccant based air conditioning system referred as HDBAC is introduced in this paper. HDBAC is mainly consisted of a liquid desiccant dehumidification unit integrated with a vapor compression system (VCS). The VCS unit has a cooling capacity of 5.27 kW and uses 134a as refrigerant. Calcium chloride (CaCl2) solution is used as the working desiccant material. HDBAC system is used to serve low sensible heat factor applications. The effect of different parameters such as, process air flow rate, desiccant solution flow rate, evaporator box and condenser box solution temperatures, strong solution concentration and regeneration temperature on the performance of the system is studied. The performance of the system is evaluated using some parameters such as: the coefficient of performance (COPa), specific moisture removal and energy saving percentage. A remarkable increase of about 54% in the coefficient of performance of the proposed system over VCS with reheat is achieved. A maximum overall energy saving of about 46% is observed which emphasizes the use of the proposed system as an energy efficient air conditioning system.

2013 German refrigeration and air conditioning meeting. Proceedings; Deutsche Kaelte- und Klimatagung 2013. Tagungsbericht

Energy Technology Data Exchange (ETDEWEB)

NONE

2013-07-01

These proceedings cover the following main topics: cryoengineering - superconduction / energy storage; cryoapplications in biology and medicine; metrology; adsorption processes; condensation/evaporation; working fluids / simulation; ice production; plants and compressors; expansion and ejectors or recooling; use of cooling (passenger car air conditioning, supermarket); refrigerants; plant efficiency; emissions and legislation; air conditioning and use of heat pumps; air quality and control; building technology and block-type thermal power stations. [German] Dieser Tagungsbericht enthaelt folgende Themenschwerpunkte: Kryotechnik - Supraleitung/Energiespeicher; Kryoanwendungen in der Biologie und Medizin; Messtechnik; Adsorptionsprozesse; Kondensation/Verdampfung; Arbeitsfluide/Simulation; Eiserzeugung; Anlagen und Verdichter; Expansion und Ejektoren bzw. Rueckkuehlung; Kaelteanwendung (PKW-Klimatisierung; Supermarkt); Kaeltemittel; Anlageneffizienz; Emissionen und Gesetzgebung; Klimatechnik und Waermepumpenanwendung; Luftqualitaet und Regelung; Gebaeudetechnik und BHKW.

Heating, ventilating, and air conditioning deactivation thermal analysis of PUREX Plant

Energy Technology Data Exchange (ETDEWEB)

Chen, W.W.; Gregonis, R.A. [Westinghouse Hanford Company, Richland, WA (United States)

1997-08-01

Thermal analysis was performed for the proposed Plutonium Uranium Extraction Plant exhaust system after deactivation. The purpose of the analysis was to determine if enough condensation will occur to plug or damage the filtration components. A heat transfer and fluid flow analysis was performed to evaluate the thermal characteristics of the underground duct system, the deep-bed glass fiber filter No. 2, and the high-efficiency particulate air filters in the fourth filter building. The analysis is based on extreme variations of air temperature, relative humidity, and dew point temperature using 15 years of Hanford Site weather data as a basis. The results will be used to evaluate the need for the electric heaters proposed for the canyon exhaust to prevent condensation. Results of the analysis indicate that a condition may exist in the underground ductwork where the duct temperature can lead or lag changes in the ambient air temperature. This condition may contribute to condensation on the inside surfaces of the underground exhaust duct. A worst case conservative analysis was performed assuming that all of the water is removed from the moist air over the inside surface of the concrete duct area in the fully developed turbulent boundary layer while the moist air in the free stream will not condense. The total moisture accumulated in 24 hours is negligible. Water puddling would not be expected. The results of the analyses agree with plant operating experiences. The filters were designed to resist high humidity and direct wetting, filter plugging caused by slight condensation in the upstream duct is not a concern. 19 refs., 2 figs.

A dynamic model for air-based photovoltaic thermal systems working under real operating conditions

International Nuclear Information System (INIS)

Sohel, M. Imroz; Ma, Zhenjun; Cooper, Paul; Adams, Jamie; Scott, Robert

2014-01-01

Highlights: • A dynamic model suitable for air-based photovoltaic thermal (PVT) systems is presented. • The model is validated with PVT data from two unique buildings. • The simulated output variables match very well with the experimental data. • The performance of the PVT system under changing working condition is analysed. - Abstract: In this paper a dynamic model suitable for simulating real operating conditions of air-based photovoltaic thermal (PVT) systems is presented. The performance of the model is validated by using the operational data collected from the building integrated photovoltaic (PVT) systems installed in two unique buildings. The modelled air outlet temperature and electrical power match very well with the experimental data. In Solar Decathlon house PVT, the average (RMS) error in air outlet temperatures was 4.2%. The average (RMS) error in electrical power was also 4.2%. In the Sustainable Buildings Research Centre PVT, the average errors (RMS) of PV and air temperatures were 3.8% and 2.2%, respectively. The performance of the PVT system under changing working condition is also analysed in this paper. The analysis includes the effect of ambient air temperature, air inlet temperature, air flow rate and solar irradiation on thermal, electrical, first law and second law efficiencies. Both the thermal and the 1st law efficiencies almost linearly increased with the increase of the ambient temperature. However, the PVT electrical efficiency and the second law efficiency decreased with the increase of the ambient temperature. All efficiencies expect the second law efficiency decreased with increase of the PVT air inlet temperature. The second law efficiency first increased and then reduced. With increasing the air flow rate all the efficiencies increased. The electrical and second law efficiencies become less sensitive when the air flow rate exceeded 300 l/s. Both the thermal and the 1st law efficiencies decreased while the electrical

A dynamic switching strategy for air-conditioning systems operated in light-thermal-load conditions

International Nuclear Information System (INIS)

Lin, Jin-Long; Yeh, T.-J.; Hwang, Wei-Yang

2009-01-01

Recently, modern air-conditioners have begun to incorporate variable-speed compressors and variable-opening expansion valves, together with feedback control to improve the performance and energy efficiency. However, for the compressor there usually exists a low-speed limit below which its speed can not be continuously modulated unless it is completely turned off. When the air-conditioning system is operated in light-thermal-load conditions, the low-speed limit causes the compressor to run in an on-off manner which can significantly degrade the performance and efficiency. In this paper, a dynamic switching strategy is proposed for such scenarios. The strategy is basically an integration of a cascading control structure, an intuitive switching strategy, and a dynamic compensator. While the control structure provides the nominal performance, the intuitive switching strategy and the dynamic compensator together can account for the compressor's low-speed limitation. Theoretical analysis reveals that when the output matrix of the dynamic compensator is chosen properly, the proposed strategy can effectively reduce the output error caused by the on-off operation of the compressor. Experiments also demonstrate that the proposed strategy can simultaneously provide better regulation for the indoor temperature and improve the energy efficiency at steady state.

Feasibility study of using agriculture waste as desiccant for air conditioning system

Energy Technology Data Exchange (ETDEWEB)

Khedari, J.; Rawangkul, R.; Hirunlabh, J. [King Mongkut' s University of Technology Thonburi, Bangkok (Thailand). Buidling Scientific Research Center; Chimchavee, W. [University of Thai Chamber of Commerce, Bangkok (Thailand); Watanasungsuit, A. [South East Asia Univ., Bangkok (Thailand). Engineering Management

2003-08-01

This research was aimed at investigating the feasibility of using dried agricultural waste as desiccant for an open cycle air conditioning system. The natural fibers are, therefore, intended to replace chemical desiccant such as silica gel, molecular sieves etc. The investigation was limited to Coconut coir (Cocos nucifera) and Durian peels (Durio zibethinus). Experimental results confirmed that dry coconut coir and durian peel can absorb 30 g and 17 g H{sub 2}O per 100 g dry product, respectively, from air at the average condition of 32{sup o}C and 75% relative humidity. The optimum airflow rate is about 84 and 98 m{sup 3}/hr-100 g dry product, respectively. Therefore, the dry coconut coir is more suitable than the dry durian peel. Comparison between the dry coconut coir and silica gel showed that the average adsorption rate of coconut coir is less than that of silica gel by about 5 g/h-100 g dry product at an airflow rate of 84 m{sup 3}/h and 60 min operating time. However, it is still an interesting option to replace silica gel in open cycle air conditioning system, as the decrease of average adsorption rate is rather small. The other extremely interesting advantage of coconut coir is that during moisture absorption the heat generated during the process is less important. That means the air leaves the coconut coir bed at a lower temperature compared to that with a silica gel. Therefore, the saving of cooling energy is much more important. (Author)

Simplified model-based optimal control of VAV air-conditioning system

Energy Technology Data Exchange (ETDEWEB)

Nassif, N.; Kajl, S.; Sabourin, R. [Ecole de Technologie Superieure, Montreal, PQ (Canada). Dept. of Construction Engineering

2005-07-01

The improvement of Variable Air Volume (VAV) system performance is one of several attempts being made to minimize the high energy use associated with the operation of heating, ventilation and air conditioning (HVAC) systems. A Simplified Optimization Process (SOP) comprised of controller set point strategies and a simplified VAV model was presented in this paper. The aim of the SOP was to determine supply set points. The advantage of the SOP over previous methods was that it did not require a detailed VAV model and optimization program. In addition, the monitored data for representative local-loop control can be checked on-line, after which controller set points can be updated in order to ensure proper operation by opting for real situations with minimum energy use. The SOP was validated using existing monitoring data and a model of an existing VAV system. Energy use simulations were compared to that of the existing VAV system. At each simulation step, 3 controller set point values were proposed and studied using the VAV model in order to select a value for each point which corresponded to the best performance of the VAV system. Simplified VAV component models were presented. Strategies for controller set points were described, including zone air temperature, duct static pressure set points; chilled water supply set points and supply air temperature set points. Simplified optimization process calculations were presented. Results indicated that the SOP provided significant energy savings when applied to specific AHU systems. In a comparison with a Detailed Optimization Process (DOP), the SOP was capable of determining set points close to those obtained by the DOP. However, it was noted that the controller set points determined by the SOP need a certain amount of time to reach optimal values when outdoor conditions or thermal loads are significantly changed. It was suggested that this disadvantage could be overcome by the use of a dynamic incremental value, which

IEA SHC Task 38 'Solar air-conditioning and refrigeration'. Danish participation 2007-2010. Appendix; IEA SHC Task 38 'Solar air-conditioning and refrigeration'. Dansk deltagelse 2007-2010. Bilag

Energy Technology Data Exchange (ETDEWEB)

Ellehauge, K. (Ellehauge og Kildemoes, Aarhus (Denmark)); Muenster, E. (PlanEnergi, Skoerping (Denmark)); Reinholdt, L. (Teknologisk Institut, Aarhus (Denmark)); Munds, S. (AC-Sun Aps, Horsens (Denmark))

2011-03-15

IEA SHC Task 38 'Solar Air-Conditioning and Refrigeration' ran from October 2006 to December 2010. Denmark was represented in the task from January 2007 to December 2010. The aim of the task was to encourage use of solar powered refrigeration and air conditioning systems in particular at residential, commercial and industrial sectors. Furthermore, the aim was to contribute to new research and development activities on new systems and concepts. The appendix contains the publications prepared by the Danish project group.(LN)

Heavy metal contamination in an urban stream fed by contaminated air-conditioning and stormwater discharges.

Science.gov (United States)

O'Sullivan, Aisling; Wicke, Daniel; Cochrane, Tom

2012-03-01

Urban waterways are impacted by diffuse stormwater runoff, yet other discharges can unintentionally contaminate them. The Okeover stream in Christchurch, New Zealand, receives air-conditioning discharge, while its ephemeral reach relies on untreated stormwater flow. Despite rehabilitation efforts, the ecosystem is still highly disturbed. It was assumed that stormwater was the sole contamination source to the stream although water quality data were sparse. We therefore investigated its water and sediment quality and compared the data with appropriate ecotoxicological thresholds from all water sources. Concentrations of metals (Zn, Cu and Pb) in stream baseflow, stormwater runoff, air-conditioning discharge and stream-bed sediments were quantified along with flow regimes to ascertain annual contaminant loads. Metals were analysed by ICP-MS following accredited techniques. Zn, Cu and Pb concentrations from stormflow exceeded relevant guidelines for the protection of 90% of aquatic species by 18-, 9- and 5-fold, respectively, suggesting substantial ecotoxicity potential. Sporadic copper (Cu) inputs from roof runoff exceeded these levels up to 3,200-fold at >4,000 μg L⁻¹ while Cu in baseflow from air-conditioning inputs exceeded them 5.4-fold. There was an 11-fold greater annual Cu load to the stream from air-conditioning discharge compared to stormwater runoff. Most Zn and Cu were dissolved species possibly enhancing metal bioavailability. Elevated metal concentrations were also found throughout the stream sediments. Environmental investigations revealed unsuspected contamination from air-conditioning discharge that contributed greater Cu annual loads to an urban stream compared to stormwater inputs. This discovery helped reassess treatment strategies for regaining ecological integrity in the ecosystem.

Air conditioning design temperature - a new proposal; Temperatura de projeto para condicionamento de ar - uma nova proposta

Energy Technology Data Exchange (ETDEWEB)

Camargo, Jose R.; Cardoso, Sebastiao [Universidade de Taubate, SP (Brazil). Dept. de Engenharia Mecanica]. E-mails: rui@engenh.mec.unitau.br; cardoso@prppg.unitau.br; Travelho, Jeronimo S. [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil)]. E-mail: jeff@lac.inpe.br

2000-07-01

ABNT - Associacao Brasileira de Normas Tecnicas (Brazilian Association for Technical Standards) - establishes, in NBR-6401, Table 1 (Interior Design Conditions), the dry-bulb summer temperature and the relative humidity to be used in air conditioning design. In thermal comfort plant for residences, hotels, offices and schools these values are, respectively, 23 deg C to 25 deg C and 40% to 60% rh. These data are in accordance with what is recommended by ASHRAE, which was established as a model for North America. This paper presents a new proposal to air conditioning design temperature that takes into consideration Brazilian climatological conditions. The method, named 'effective temperature distribution', compares the maximum recommended effective temperature for each region with dry-bulb temperatures and effective temperatures plotted in a single diagram. This diagram may be used in energetic planning to minimize the use of electric energy for air conditioning. It concludes that the method allows an accuracy analysis about both the temperature levels and the periods of utilization of the air conditioning systems. (author)

Heat Transfer Enhancement of the Air-Cooling Tower with Rotating Wind Deflectors under Crosswind Conditions

OpenAIRE

Xueping Du; Dongtai Han; Qiangmin Zhu

2018-01-01

To investigate the effect of wind deflectors on air flow and heat transfer performance of an air-cooling tower under crosswind conditions, an experimental system based on a surface condenser aluminum exchanger-type indirect air-cooling tower is established at a 1:100 proportional reduction. A 3-D computational fluid dynamics simulation model is built to study the air flow and temperature fields. The air flow rate into the cooling tower and the heat transfer rate of the radiators are used to e...

The effects of air stoichiometry and air excess ratio on the transient response of a PEMFC under load change conditions

International Nuclear Information System (INIS)

Kim, Bosung; Cha, Dowon; Kim, Yongchan

2015-01-01

Highlights: • Effects of controlling parameters on the transient response of a PEMFC are studied. • The transient response is measured by varying air stoichiometry and air excess ratio. • Voltage drop, undershoot, and voltage fluctuation are analyzed under the load change. • Optimal air stoichiometry and air excess ratio are suggested for stable operation. - Abstract: The transient response of a proton exchange membrane fuel cell (PEMFC) is an important issue for transportation applications. The objective of this study is to investigate the effects of operating and controlling parameters on the transient response of a PEMFC for achieving more stable cell performance under load change conditions. The transient response of a PEMFC was measured and analyzed by varying air stoichiometry, air humidity, and air excess ratio (AER). The optimal air stoichiometry and AER were determined to minimize the voltage drop, undershoot, and voltage fluctuation under the load change, while maintaining high cell performance. Based on the present data, the optimal air stoichiometry was determined to be between 2.0 and 2.5, and the optimal AER was suggested to be between 1.65 and 2.0

Heat Transfer Enhancement of the Air-Cooling Tower with Rotating Wind Deflectors under Crosswind Conditions

Directory of Open Access Journals (Sweden)

Xueping Du

2018-04-01

Full Text Available To investigate the effect of wind deflectors on air flow and heat transfer performance of an air-cooling tower under crosswind conditions, an experimental system based on a surface condenser aluminum exchanger-type indirect air-cooling tower is established at a 1:100 proportional reduction. A 3-D computational fluid dynamics simulation model is built to study the air flow and temperature fields. The air flow rate into the cooling tower and the heat transfer rate of the radiators are used to evaluate cooling performance. Rotating wind deflectors are adopted to reduce the influence of crosswind on the cooling tower performance. The effects of the rotating wind deflectors on the thermal-hydraulic characteristics of the air-cooling tower under different environmental crosswind speeds are studied. Results indicate that the wind direction in the tower reverses as the rotating speed of the wind deflectors increases. The thermal performance of an air-cooling tower under crosswind conditions can be improved by using rotating wind deflectors. The heat transfer rate of a cooling tower with eight wind deflectors begins to increase when the rotating speed exceeds 2 r/min.

Voltage controller design for air conditioning; Diseno de controlador de voltaje para aire acondicionado

Energy Technology Data Exchange (ETDEWEB)

Garcia Andrade, R; Lopez Villalobos, J.J; Valderrama Chairez, J; Ramirez, R.L. [Instituto Tecnologico de Nuevo Leon, Guadalupe, Nuevo Leon (Mexico)]. E-mails: roxana_garciaandrade@yahoo.com; xe2n@yahoo.com.mx; jose.valderrama@ieee.org

2013-03-15

This paper discusses the design of a voltage controller for an air conditioning system in order to generate additional power in activation or startup of the system, for which as a first stage is presented the modeling power generation of electric current through alternative means, such as solar energy. The results of this study will be the basis for development of the physical prototype of this system controller. [Spanish] El presente trabajo trata sobre el diseno de un controlador de voltaje para un sistema de aire acondicionado con el fin de generar energia adicional en la activacion o arranque de dicho sistema, para lo cual como primer fase se presenta el modelado de la generacion de corriente electrica mediante medios alternos, como lo es la energia solar. Los resultados de este trabajo seran la base para desarrollo del prototipo fisico de este sistema controlador.

Natural convection liquid desiccant loop as an auxiliary air conditioning system: investigating the operational parameters

Science.gov (United States)

Fazilati, Mohammad Ali; Alemrajabi, Ali Akbar; Sedaghat, Ahmad

2018-03-01

Liquid desiccant air conditioning system with natural convection was presented previously as a new generation of AC systems. The system consists of two three-fluid energy exchangers namely absorber and regenerator in which the action of air dehumidifying and desiccant regeneration is done, respectively. The influence of working parameters on system performance including the heat source and heat sink temperature, concentration of desiccant solution fills the system initially and humidity content of inlet air to regenerator is investigated experimentally. The heat source temperatures of 50 °C and 60 °C, heat sink temperatures of 15 °C and 20 °C and desiccant concentrations of 30% and 34%, are examined here. The inlet air to regenerator has temperature of 38.5 °C and three relative humidity of 14%, 38% and 44%. In all experiments, the inlet air to absorber has temperature of 31 °C and relative humidity of 75%. By inspecting evaluation indexes of system, it is revealed that higher startup desiccant concentration solution is more beneficial for all study cases. It is also observed although the highest/lowest temperature heat source/heat sink is most suitable for best system operation, increasing the heat source temperature should be accompanied with decreasing heat sink temperature. Using drier air stream for regenerator inlet does not necessarily improve system performance; and the air stream with proper value of humidity content should be employed. Finally after running the system in its best working condition, the coefficient of performance (COP) reached 4.66 which verified to be higher than when the same air conditioning task done by a conventional vapor compression system, in which case the COP was 3.38.

F1 occurrence including L condition in TUCUMAN and BUENOS AIRES

International Nuclear Information System (INIS)

Mosert Gonzalez, M. de; Ezquer, R.G.; Oviedo, R.V. del

1997-01-01

An analysis of the occurrence of the F1 layer including the L condition has been done, using data from two Argentine stations: TUCUMAN and BUENOS AIRES, at different seasons and solar activity conditions. The comparisons between observations and the F1 occurrence predicted by the IRI-90 model show the need of reviewing the use of the DuCharme et al. (1973) formula adopted by the model to predict the occurrence of the intermediate F1 layer including the L condition. (author). 6 refs, 6 figs, 2 tabs

The natural gas air-conditioning; La climatisation au gaz naturel. Un avenir prometteur, une technique confirmee

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-07-01

The natural gas air-conditioning market is in growth (it will cover 10% of the market in 2002).To illustrate the possibilities of this energy source, this paper presents three examples of the natural gas air-conditioning in France. The technical aspects, the cost and the advantages of such systems are discussed. (A.L.B.)

The effect of the atmospheric condition on the extensive air shower analysis at the Telescope Array experiment

International Nuclear Information System (INIS)

Kobayashi, Y.; Tsunesada, Y.; Tokuno, H.; Kakimoto, F.; Tomida, T.

2011-01-01

The accuracies in determination of air shower parameters such as longitudinal profiles or primary energies with the fluorescence detection technique are strongly dependent on atmospheric conditions of the molecular and aerosol components. Moreover, air fluorescence photon yield depends on the atmospheric density, and the transparency of the air for fluorescence photons depends on the atmospheric conditions from EAS to FDs. In this paper, we describe the atmospheric monitoring system in the Telescope Array (TA experiment), and the impact of the atmospheric conditions in air shower reconstructions. The systematic uncertainties of the determination of the primary cosmic ray energies and of the measurement of depth of maximum development (X max ) of EASs due to atmospheric variance are evaluated by Monte Carlo simulation.

Ecologic air-conditioning. A pilot plant for the geothermal and sorption supported air-conditioning in the HafenCity Hamburg; Oekologische Klimatisierung. Pilotanlage zur geothermisch- und sorptionsgestuetzten Klimatisierung in der HafenCity Hamburg

Energy Technology Data Exchange (ETDEWEB)

Ma, Xiaolong; Grabe, Juergen [Technische Univ. Hamburg-Harburg (Germany). Inst. fuer Geotechnik und Baubetrieb

2011-10-24

The relatively constant temperatures of the underground at a depth of 100 meters provide the opportunity to air-condition buildings with geothermal energy and economically. Currently, building air conditioning systems in Central Europe exhibit high growth rates. In summer, the task of an air conditioner is to cool and dehumidify air. Especially the dehumidification usually causes a high cooling demand, as the air is cooled below the dew point temperature of 12 C in order to condense out the water. The dew point is well below the demand for a comfortable room temperature of about 19 C. With this in mind, the authors of this contribution report on a principle of alternative dehumidification by means of a so-called sorption wheel. Sorption wheels use the hygroscopic properties of certain substances such as lithium chloride or silica gel in order to dehumidify the air. Thereby, the cooling demand significantly is reduced by the previous dehumidification. The regeneration of the sorption wheel requires heat. This heat can be provided by solar thermal plants and district heating. Since the air can no longer be dehumidified, rich supply temperatures between 16 and 19 C from. These temperatures can be achieved by means of near-surface temperature. Ground registers, geothermal energy probes or geothermal structures such as power poles are used as ground heat exchanger. The authors present the concept and the measurement results of the pilot plant in Hamburg's HafenCity.

Performance enhancement of a subcooled cold storage air conditioning system

International Nuclear Information System (INIS)

Hsiao, M.-J.; Cheng, C.-H.; Huang, M.-C.; Chen, S.-L.

2009-01-01

This article experimentally investigates the enhancement of thermal performance for an air conditioning system utilizing a cold storage unit as a subcooler. The cold storage unit is composed of an energy storage tank, liquid-side heat exchanger, suction-side heat exchanger and energy storage material (ESM), water. When the cooling load is lower than the nominal cooling capacity of the system, the cold storage unit can store extra cold energy of the system to subcool the condenser outlet refrigerant. Hence, both the cooling capacity and coefficient of performance (COP) of the system will be increased. This experiment tests the two operation modes: subcooled mode with energy storage and non-subcooled mode without energy storage. The results show that for fixed cooling loads at 3.05 kW, 3.5 kW and 3.95 kW, the COP of the subcooled mode are 16.0%, 15.6% and 14.1% higher than those of the non-subcooled mode, respectively. In the varied cooling load experiments, the COP of the subcooled cold storage air conditioning system is 15.3% higher than the conventional system.

Experimental determination of the energy efficiency of an air-cooled chiller under part load conditions

International Nuclear Information System (INIS)

Yu, F.W.; Chan, K.T.

2005-01-01

In cities located in a subtropical climate, air-cooled chillers are commonly used to provide cooling to the indoor environment. This accounts for the increasing electricity demand of buildings over the decades. This paper investigates how the condensing temperature serves to accurately determine the energy efficiency, or coefficient of performance (COP), of air-cooled chillers under part load conditions. An experiment on an air-cooled reciprocating chiller showed that for any given operating condition, the COP of the chiller varies, depending on how the condensing temperature is controlled. A sensitivity analysis is implemented to investigate to what extent COP is responding to changes in operating variables and confirms that the condensing temperature is an adequate variable to gauge COP under various operating conditions. The specifications of the upper limit for the condensing temperature in order to improve the energy efficiency of air-cooled chillers are discussed. The results of this work will give designers and researchers a good idea about how to model chiller energy performance curves in the thermal and energy computation exercises

Application of computational fluid dynamics and pedestrian-behavior simulations to the design of task-ambient air-conditioning systems of a subway station

Energy Technology Data Exchange (ETDEWEB)

Fukuyo, Kazuhiro [Graduate School of Innovation and Technology Management, Faculty of Engineering, Yamaguchi University, Tokiwadai 2-16-1, Ube, Yamaguchi 755-8611 (Japan)

2006-04-15

The effects of task-ambient (TA) air-conditioning systems on the air-conditioning loads in a subway station and the thermal comfort of passengers were studied using computational fluid dynamics (CFD) and pedestrian-behavior simulations. The pedestrian-behavior model was applied to a standard subway station. Task areas were set up to match with crowdedness as predicted by the pedestrian-behavior simulations. Subsequently, a variety of TA air-conditioning systems were designed to selectively control the microclimate of the task areas. Their effects on the thermal environment in the station in winter were predicted by CFD. The results were compared with those of a conventional air-conditioning system and evaluated in relation to the thermal comfort of subway users and the air-conditioning loads. The comparison showed that TA air-conditioning systems improved thermal comfort and decreased air-conditioning loads. (author)

Human requirements in future air-conditioned environments: a search for excellence

DEFF Research Database (Denmark)

Fanger, Povl Ole

2000-01-01

Although air-conditioning has played a positive role for economic development in warm climates, its image is globally mixed. Field studies demonstrate that there are substantial numbers of dissatisfied people in many buildings, among them those suffering from SBS symptoms, even though existing...

Thermodynamic model of a thermal storage air conditioning system with dynamic behavior

International Nuclear Information System (INIS)

Fleming, Evan; Wen, Shaoyi; Shi, Li; Silva, Alexandre K. da

2013-01-01

Highlights: • We developed an automotive thermal storage air conditioning system model. • The thermal storage unit utilizes phase change materials. • We use semi-analytic solution to the coupled phase change and forced convection. • We model the airside heat exchange using the NTU method. • The system model can incorporate dynamic inputs, e.g. variable inlet airflow. - Abstract: A thermodynamic model was developed to predict transient behavior of a thermal storage system, using phase change materials (PCMs), for a novel electric vehicle climate conditioning application. The main objectives of the paper are to consider the system’s dynamic behavior, such as a dynamic air flow rate into the vehicle’s cabin, and to characterize the transient heat transfer process between the thermal storage unit and the vehicle’s cabin, while still maintaining accurate solution to the complex phase change heat transfer. The system studied consists of a heat transfer fluid circulating between either of the on-board hot and cold thermal storage units, which we refer to as thermal batteries, and a liquid–air heat exchanger that provides heat exchange with the incoming air to the vehicle cabin. Each thermal battery is a shell-and-tube configuration where a heat transfer fluid flows through parallel tubes, which are surrounded by PCM within a larger shell. The system model incorporates computationally inexpensive semi-analytic solution to the conjugated laminar forced convection and phase change problem within the battery and accounts for airside heat exchange using the Number of Transfer Units (NTUs) method for the liquid–air heat exchanger. Using this approach, we are able to obtain an accurate solution to the complex heat transfer problem within the battery while also incorporating the impact of the airside heat transfer on the overall system performance. The implemented model was benchmarked against a numerical study for a melting process and against full system

An Investigation about using Nanorefrigerants in Air Conditioning Systems According to the Theoretical, CFD and Experimental Review of the Recent Literature

Directory of Open Access Journals (Sweden)

Farshad Panahizadeh

2016-10-01

Full Text Available Greenhouse gases (GHG causing global warming and climate change. In the year 2014, 32.3 billion tones CO2 emitted to the atmosphere as the most important greenhouse gas. According to the statistics, a significant portion of this amount is related to electricity demand of air conditioning systems, for producing a one ton of refrigeration in HVAC air cooled or water cooled systems respectively 1026 and 764 grams GHG emitted in the atmosphere. Therefore, air conditioning systems have an important role in the global warming and climate change. By increasing the COP of air conditioning systems the electricity demand of them reduced. One strategy for increasing the COP of air conditioning systems is using nanorefrigerants. In the present study, a comprehensive information is given regarding to use nanorefrigerants in air conditioning systems according to the theoretical, CFD and experimental review of the recent literature. This paper gives assistance to designers of air conditioning systems in their future efforts for selecting refrigerant for their systems

Impact of climate change on commercial sector air conditioning energy consumption in subtropical Hong Kong

International Nuclear Information System (INIS)

Lam, Tony N.T.; Wan, Kevin K.W.; Wong, S.L.; Lam, Joseph C.

2010-01-01

Past and future trend of electricity use for air conditioning in the entire commercial sector in subtropical climates using 1979-2008 measured meteorological data as well as predictions for 2009-2100 from a general circulation model (MIROC3.2-H) was investigated. Air conditioning consumption showed an increasing trend over the past 30 years from 1979 to 2008. Principal component analysis (PCA) of measured and predicted monthly mean dry-bulb temperature, wet-bulb temperature and global solar radiation was conducted to determine a new climatic index Z for 1979-2008 and future 92 years (2009-2100) based on two emissions scenarios B1 and A1B (low and medium forcing). Through regression analysis, electricity use in air conditioning for the 92-year period was estimated. For low forcing, average consumption in 2009-2038, 2039-2068 and 2069-2100 would be, respectively, 5.7%, 12.8% and 18.4% more than the 1979-2008 average, with a mean 12.5% increase for the entire 92-year period. Medium forcing showed a similar increasing trend, but 1-4% more. Standard deviations of the monthly air conditioning consumption were found to be smaller suggesting possible reduction in seasonal variations in future years.

A novel capacity controller for a three-evaporator air conditioning (TEAC) system for improved indoor humidity control

International Nuclear Information System (INIS)

Yan, Huaxia; Deng, Shiming; Chan, Ming-yin

2016-01-01

Highlights: • A novel capacity controller for TEAC systems for improved indoor humidity control is developed. • The novel controller was developed by integrating two previous control algorithms. • Experimental controllability tests were carried out. • Improved control over indoor humidity levels and higher energy efficiency can be achieved. - Abstract: Using a multi-evaporator air conditioning (MEAC) system to correctly control indoor air temperatures only in a multi-room application is already a challenging and difficult task, let alone the control of both indoor air temperature and humidity. This is because in an MEAC system, a number of indoor units are connected to a common condensing unit. Hence, the interferences among operation parameters of different indoor units would make the desired control of an MEAC system hard to realize. Limited capacity control algorithms for MEAC systems have been developed, with most of them focusing only on the control of indoor air temperature, and no previous studies involving control of indoor air humidity using MEAC systems can be identified. In this paper, the development of a novel capacity controller for a three-evaporator air conditioning (TEAC) system for improved indoor air humidity control is reported. The novel controller was developed by integrating two previous control algorithms for a dual-evaporator air conditioning system for temperature control and for a single-evaporator air conditioning system for improved indoor humidity control. Experimental controllability tests were carried out and the controllability test results showed that, with the novel controller, improved control over indoor humidity levels and better energy efficiency for a TEAC system could be obtained as compared to the traditional On–Off controllers extensively used by MEAC systems.

Complex dynamics and chaos control of duopoly Bertrand model in Chinese air-conditioning market

International Nuclear Information System (INIS)

Yi, Qi Guo; Zeng, Xiang Jin

2015-01-01

Highlights: •A dynamic duopoly Bertrand model with bounded rationality and quadratic cost function. •In Chinese air-conditioning market the boundary equilibrium point is locally stable. •The Lyapunov dimension of the chaos attractor is 1.9585. •The adjustment speeds may cause a market structure to behave chaotically. •The chaotic behavior can be controlled by decreasing the degree of substitutability. -- Abstract: A dynamic duopoly Bertrand model with quadratic cost function which is closer to reality and different from previous researches is discussed. The model is applied into air-conditioning market where the boundary equilibrium point is locally stable. Numerical simulations illustrate that the stability of Nash equilibrium strongly depends on the speed of adjustment of bounded rational player. The adjustment speeds and the degree of substitutability may undermine the stability of the equilibrium and cause a market structure to behave chaotically. The Lyapunov dimension of the chaos attractor is 1.9585 under some conditions. The stabilization of the chaotic behavior can be obtained by reducing the degree of substitutability. The results have an important theoretical and practical significance to Chinese air-conditioning market

Performance Analysis of Air-to-Water Heat Pump in Latvian Climate Conditions

Science.gov (United States)

Kazjonovs, Janis; Sipkevics, Andrejs; Jakovics, Andris; Dancigs, Andris; Bajare, Diana; Dancigs, Leonards

2014-12-01

Strategy of the European Union in efficient energy usage demands to have a higher proportion of renewable energy in the energy market. Since heat pumps are considered to be one of the most efficient heating and cooling systems, they will play an important role in the energy consumption reduction in buildings aimed to meet the target of nearly zero energy buildings set out in the EU Directive 2010/31/EU. Unfortunately, the declared heat pump Coefficient of Performance (COP) corresponds to a certain outdoor temperature (+7 °C), therefore different climate conditions, building characteristics and settings result in different COP values during the year. The aim of this research is to investigate the Seasonal Performance factor (SPF) values of air-to-water heat pump which better characterize the effectiveness of heat pump in a longer selected period of time, especially during the winter season, in different types of residential buildings in Latvian climate conditions. Latvia has four pronounced seasons of near-equal length. Winter starts in mid-December and lasts until mid-March. Latvia is characterized by cold, maritime climate (duration of the average heating period being 203 days, the average outdoor air temperature during the heating period being 0.0 °C, the coldest five-day average temperature being -20.7 °C, the average annual air temperature being +6.2 °C, the daily average relative humidity being 79 %). The first part of this research consists of operational air-towater heat pump energy performance monitoring in different residential buildings during the winter season. The second part of the research takes place under natural conditions in an experimental construction stand which is located in an urban environment in Riga, Latvia. The inner area of this test stand, where air-to-water heat pump performance is analyzed, is 9 m2. The ceiling height is 3 m, all external wall constructions (U = 0.16 W/(m2K)) have ventilated facades. To calculate SPF, the

Health risk air-conditioning system; Insufficient maintenance increases the risk of illness. Gesundheitsrisiko Klimaanlagen; Unzureichende Wartung erhoeht das Erkrankungsrisiko

Energy Technology Data Exchange (ETDEWEB)

Anon.

1994-01-01

In Germany every fifth employee who works in air-conditioned rooms complains about headache, an increased proneness to colds and influenza infections as well as allergic reactions. These troubles are often caused by the insufficient maintenance of air-conditioning systems. At present only 15% of the estimated annual demand for maintenance of space hvac-systems is actually carried out. Problematic in case of air-conditioning systems are the so-called air washers used for air humidification which can become an ideal cultur medium for microorganisms. A second problematic area are the often very dirty filters. But health risks can be avoided with regular expert maintenance alone. As first step an analysis of the causes of faults is proposed. (BWI)

FY1999 Meeting of The Society of Heating, Air-Conditioning and Sanitary Engineering of Japan. Air flow analysis II; 1999 nendo gakujutsu koenkai gaiyo. Kiryu kaiseki 2

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-12-05

B-4 reported the result on particle size distribution experiment and numerical calculation with FEM and {kappa}- {epsilon} model using a welding simulation equipment for generation and removal of welding fume in a narrow site. Discussion was held on the position of an exhaust hood. B-5 reported the study results on indoor air flow conditions derived from a movable nozzle air conditioning system by model experiment and numerical analysis. Disagreement of both results between the experiment and calculation in the case of two diffusing nozzles attached at 30 degrees toward the inside was improved by shortening a sampling time for calculation. B-6 reported the study results on some parameters such as wind velocity, flow rate and inlet position, and the energy saving effect of an air curtain (wall outlet, floor inlet) to control air conditioning areas for a part of large spaces by numerical analysis of air flow. Discussion was held on calculation of 2-D flow and layered flow. B-7 is the 5th research report on measurement of air flow conditions such as measurement of large space environment by video camera and balloon. Study on the camera for automatic measurement, and the identification technique of balloon positions was reported. (translated by NEDO)

[Study on air quality and pollution meteorology conditions of Guangzhou during the 2010 Asian games].

Science.gov (United States)

Li, Ting-Yuan; Deng, Xue-Jiao; Fan, Shao-Jia; Wu, Dui; Li, Fei; Deng, Tao; Tan, Hao-Bo; Jiang, De-Hai

2012-09-01

Based on the monitoring data of NO2, O3, SO2, PM, visibility, regional air quality index (RAQI) and the atmospheric transport and diffusion data from Nov. 4, 2010 to Dec. 10, 2010 in Guangzhou area, the variations of air quality and meteorological conditions during the Guangzhou Asian Games were analyzed. It was found that, during the Asian Games, the air quality was better than the air quality before or after the Asian Games. The visibility was greater than the visibility before or after the Asian Games, while the concentrations of PM1 and PM2.5 were lower. The correlation coefficient between visibility and the concentrations of PM1, PM2.5 indicated anti-correlation relationships. Daily and hourly concentrations of NO2 and SO2 met the primary ambient air quality standards, whereas the daily concentration of PM10 and hourly concentration of O3 met the secondary ambient air quality standards. Pollutants had been well controlled during the Asian Games. The concentration of SO2 in Guangzhou was influenced by local sources and long distance transmission, while the concentration of NO2 was significantly influenced by local sources. The emissions of NO2, SO2 and PM10 surrounding Guangzhou had a trend to affect the concentrations in Guangzhou, but the situation of O3 was opposite, the relatively high concentration of O3 in Guangzhou had tendency to be transported to the surrounding areas. The pollution meteorology conditions in the period of Asian Games were better than the conditions before or after the Asian Games. The decrease in the concentrations during the Asian Games did not only benefit from the emission control by the government, but also from the good meteorological conditions.

[Hygienic assessment of a recirculatory combined air-conditioning extract-and-input system in office building].

Science.gov (United States)

Malysheva, A G; Abramov, E G

2006-01-01

The high concentrations of lead were reveled in the air and dust of some premises and on the filters of a combined air-conditioning extract-and-input system in the high-rise office buildings located in the ecologically lead favorable environment. The dust content of lead in some premises on the first floors dust was as high as 200 mg/kg, which was more than 6 times higher than that in the soil at the highway near the office buildings. The use of new technologies and devices for cleaning and optimizing the air in the premises requires analytical studies to assess the quality of the environment, by taking into account the optimal conditions of their operation.

Ice thermal storage air conditioning system for electric load leveling; Denryoku heijunka to hyochikunetsu system

Energy Technology Data Exchange (ETDEWEB)

Shigenaga, Y. [Daikin Industries Ltd., Osaka (Japan)

1998-08-15

Thermal storage air conditioning system is the one to use energy stored into thermal storing materials by using night electric power and to operate effective air conditioning. Therefore, as load can be treated by the stored energy, volume of the apparatus can be reduced. And, by reduction of the consumed power at day time, it can contribute to leveling of electric power demand. In general, there are two types in the thermal storage method: one is a method to store as thermal energy, and the other is that to store as chemical energy. For conditions required for the storing materials, important elements on their actual uses are not only physical properties such as large thermal storage per unit and easy thermal in- and out-puts, but also safety, long-term reliability, and easy receiving and economics containing future. The ice thermal storage air conditioning system is classified at the viewpoint of type of ice, kind of thermal storing medium, melting method on using cooling and heating, kinds of thermal medium on cooling and heating. 3 refs., 5 figs., 2 tabs.

Characteristics of radon and its progeny concentrations in air-conditioned office buildings in Tokyo

International Nuclear Information System (INIS)

Tokonami, S.; Furukawa, M.; Shicchi, Y.; Sanada, T.; Yamada, Y.

2003-01-01

A series of measurements were carried out to understand the characteristics of radon and its progeny in air-conditioned office buildings. Long-term measurements of radon were made with etched track detectors. Continuous measurements of radon and its progeny concentrations were also conducted in some buildings to study their temporal variations. The results show that radon and its progeny concentrations routinely varied along with working activities. They are generally low while people are working, due to air conditioning, whereas they rise steadily after the air conditioning stops. When considering action levels not only in homes but also workplaces, attention should be paid to annual doses from the viewpoint of radiation protection. The annual dose is generally estimated with a long-term measurement of radon concentration using a passive device such as an etched track detector. Since its reading corresponds to a long-term average concentration regardless of working hours, the annual dose will be overestimated. When comparing a real dose after considering the working hours, they differ by a factor of more than 2. (author)

Correlation between meteorological conditions and the concentration of radionuclides in the ground layer of atmospheric air

International Nuclear Information System (INIS)

Krajny, E.; Osrodka, L.; Wojtylak, M.; Michalik, B.; Skowronek, J.

2001-01-01

The main goal of this work was to find correlation between the concentrations of radionuclides in outdoor air and the meteorological conditions like: atmospheric pressure, wind velocity and amount of precipitation. Because the sampling period of radionuclides concentrations in air was relatively long (7 days), the average levels of meteorological parameters have been calculated within the same time. Data of radionuclide concentrations and meteorological data have been analyzed in order to find statistical correlation. The regression analysis and one of AI methods, known as neural network, were applied. In general, analysis of the gathered data does not show any strong correlation between the meteorological conditions and the concentrations of the radionuclides in air. A slightly stronger correlation we found for radionuclides with relatively short half-lives. The only positive correlation has been found between the 7 Be concentration and air temperature (at the significance level α = 0.05). In our opinion, the lack of correlation was caused by a too long sampling time in measurements of radionuclides in outdoor air (a whole week). Results of analysis received by means of the artificial neuron network are better. We were able to find certain groups of meteorological conditions, related with the corresponding concentrations of particular radionuclides in air. Preliminary measurements of radon progeny concentration support the thesis that the link between changes of meteorological parameters and concentrations of radionuclides in ambient air must exist. (author)

Effect of real-time boundary wind conditions on the air flow and pollutant dispersion in an urban street canyon—Large eddy simulations

Science.gov (United States)

Zhang, Yun-Wei; Gu, Zhao-Lin; Cheng, Yan; Lee, Shun-Cheng

2011-07-01

Air flow and pollutant dispersion characteristics in an urban street canyon are studied under the real-time boundary conditions. A new scheme for realizing real-time boundary conditions in simulations is proposed, to keep the upper boundary wind conditions consistent with the measured time series of wind data. The air flow structure and its evolution under real-time boundary wind conditions are simulated by using this new scheme. The induced effect of time series of ambient wind conditions on the flow structures inside and above the street canyon is investigated. The flow shows an obvious intermittent feature in the street canyon and the flapping of the shear layer forms near the roof layer under real-time wind conditions, resulting in the expansion or compression of the air mass in the canyon. The simulations of pollutant dispersion show that the pollutants inside and above the street canyon are transported by different dispersion mechanisms, relying on the time series of air flow structures. Large scale air movements in the processes of the air mass expansion or compression in the canyon exhibit obvious effects on pollutant dispersion. The simulations of pollutant dispersion also show that the transport of pollutants from the canyon to the upper air flow is dominated by the shear layer turbulence near the roof level and the expansion or compression of the air mass in street canyon under real-time boundary wind conditions. Especially, the expansion of the air mass, which features the large scale air movement of the air mass, makes more contribution to the pollutant dispersion in this study. Comparisons of simulated results under different boundary wind conditions indicate that real-time boundary wind conditions produces better condition for pollutant dispersion than the artificially-designed steady boundary wind conditions.

Residential solar air conditioning: Energy and exergy analyses of an ammonia–water absorption cooling system

International Nuclear Information System (INIS)

Aman, J.; Ting, D.S.-K.; Henshaw, P.

2014-01-01

Large scale heat-driven absorption cooling systems are available in the marketplace for industrial applications but the concept of a solar driven absorption chiller for air-conditioning applications is relatively new. Absorption chillers have a lower efficiency than compression refrigeration systems, when used for small scale applications and this restrains the absorption cooling system from air conditioning applications in residential buildings. The potential of a solar driven ammonia–water absorption chiller for residential air conditioning application is discussed and analyzed in this paper. A thermodynamic model has been developed based on a 10 kW air cooled ammonia–water absorption chiller driven by solar thermal energy. Both energy and exergy analyses have been conducted to evaluate the performance of this residential scale cooling system. The analyses uncovered that the absorber is where the most exergy loss occurs (63%) followed by the generator (13%) and the condenser (11%). Furthermore, the exergy loss of the condenser and absorber greatly increase with temperature, the generator less so, and the exergy loss in the evaporator is the least sensitive to increasing temperature. -- Highlights: • 10 kW solar thermal driven ammonia–water air cooled absorption chiller is investigated. • Energy and exergy analyses have been done to enhance the thermal performance. • Low driving temperature heat sources have been optimized. • The efficiencies of the major components have been evaluated

The Histoty of Ventilation and Air Conditioning: is CERN Up to Date with the latest Technological Developments?

OpenAIRE

Kühnl-Kinel, J

2000-01-01

The invention of ventilation cannot be ascribed to a certain date. It started with simple aeration when man brought fire into his abode and continued through different stages including air cooling using ice to finally arrive at the time when ventilation and air conditioning has become an essential part of our life and plays an important role in human evolution. This paper presents the history of ventilation and air conditioning, explains the key constraints over the centuries, and shows its i...

Comparative economic assessment of the energy performance of air-conditioning within the Mexican residential sector

Directory of Open Access Journals (Sweden)

Ivan Oropeza-Perez

2016-11-01

Full Text Available This work shows a sensitivity analysis of the economic impact of different energy performances of air-conditioning within the Mexican housing sector. For this purpose, a cooling-load calculator program in function of the indoor temperature is developed. The program also calculates the electricity consumption along with the expenditure with the different residential rates of the Mexican Federal Commission of Electricity (CFE, initials in Spanish set according to the season of the year and zone of the country. After the results onto the national-scale scenario are validated with the literature, a sensitivity analysis is carried out by changing three parameters that are considered as influential on the consumption and which can be considered as energy saving strategies. With these strategies, it is found that the indoor temperature decrease due to the use of a passive cooling system is the most important characteristic to take into account followed by the coefficient of performance (COP of the air-conditioning and the increase of the comfort temperature set-point, respectively. Thereby, an economic analysis is carried out, finding an annual saving up to 770 USD within a single air-conditioned dwelling having a payback period of 3 years for using a combination of passive cooling techniques and increasing the comfort temperature set-point; or a 2 years payback period if the air-conditioning is changed by a high-efficient equipment.

Liquid over-feeding air conditioning system and method

Science.gov (United States)

Mei, Viung C.; Chen, Fang C.

1993-01-01

A refrigeration air conditioning system utilizing a liquid over-feeding operation is described. A liquid refrigerant accumulator-heat exchanger is placed in the system to provide a heat exchange relationship between hot liquid refrigerant discharged from condenser and a relatively cool mixture of liquid and vaporous refrigerant discharged from the evaporator. This heat exchange relationship substantially sub-cools the hot liquid refrigerant which undergoes little or no evaporation across the expansion device and provides a liquid over-feeding operation through the evaporator for effectively using 100 percent of evaporator for cooling purposes and for providing the aforementioned mixture of liquid and vaporous refrigerant.

Exergy analysis of a centralized air conditioning system for ice water

International Nuclear Information System (INIS)

Armas, Juan C; Lapido, Margarita J; Castellanos, Juan A

2006-01-01

An exergetic analysis of a centralized system of air conditioning, based on a vapor compression refrigeration cycle, appears in this article. The investigation allows to calculate the irreversibilities (exergy destruction) in the main components of the refrigeration cycle as well as to evaluate the sensitivity of this indicator when the operating conditions changes. As main result the most sensible components of the cycle are identified, information that will be useful in order to define strategies of operation focused to the power efficiency increase.

Exergy storage to exploit solar energy in air conditioning

Energy Technology Data Exchange (ETDEWEB)

Navarrete-Gonzalez, J.J.; Torres-Reyes, E. [Guanajuato Univ., Guanajuato (Mexico). Inst. de Investigaciones Cientificas; Cervantes-de Gortari, J.G. [Univ. of Cuidad, Mexico City (Mexico). Dept. de Termoenergia y Mejoramiento Ambiental

2006-07-01

A thermodynamic procedure was developed to analyze the exergy of a rock bed thermal storage unit that used solar power to acclimatize a pig farm. Thermal behaviour was described by means of a control volume that included the entire system and assumed a unidirectional air flow and an adiabatic process. The thermodynamic properties of the system were determined as a function of the experimental temperature profiles developed during thermal storage from solar to thermal energy conversion provided by a solar collector at a fixed mass rate of air flow. Experimental data were used to calculate the energy yield and to determine the entropy generation inside the system. The aim of the study was to determine how well the thermodynamic model matched the real data obtained experimentally during normal operating conditions. Results indicated that an exergy accumulation existed inside the control volume, which was the net result of the energy gain during the heating process. However, entropy generation due to irreversibilities was studied for just 1 air flow. Further research is needed to establish a semi-empirical model of the process with the minimum of entropy generation. It was concluded that the thermal energy storage system was suitable for use in pig farms. 5 refs., 8 figs.

Mode switching control of dual-evaporator air-conditioning systems

International Nuclear Information System (INIS)

Lin, J.-L.; Yeh, T.-J.

2009-01-01

Modern air-conditioners incorporate variable-speed compressors and variable-opening expansion valves as the actuators for improving cooling performance and energy efficiency. These actuators have to be properly feedback-controlled; otherwise the systems may exhibit even poorer performance than the conventional machines which use fixed-speed compressors and mechanical expansion valves. Particularly for an air-conditioner with multiple evaporators, there are occasions that the machine is operated in a mode that only selected evaporator(s) is(are) turned on, and switching(s) between modes occurs(occur) during the control process. In this case, one needs to have more carefully designed control and switching strategies to ensure the system performance. In this paper, a framework for mode switching control of the dual-evaporator air-conditioning (DEAC) system is proposed. The framework is basically an integration of a controller and a dynamic compensator. The controller, which possesses the flow-distribution capability and assumes both evaporators are on throughout the control process, is intended to provide nominal performance. While mode switching is achieved by varying the reference settings in the controller, the dynamic compensator is used to improve the transient responses immediately after the switching. Experiments indicate that the proposed framework can achieve satisfactory indoor temperature regulation and provide bumpless switching between different modes of operation.

Research on ration selection of mixed absorbent solution for membrane air-conditioning system

International Nuclear Information System (INIS)

Li, Xiu-Wei; Zhang, Xiao-Song; Wang, Fang; Zhao, Xiao; Zhang, Zhuo

2015-01-01

Highlights: • We derive models of the membrane air-conditioning system with mixed absorbents. • We make analysis on system COP, cost-effectiveness and economy. • The paper provides a new method for ideal absorbent selection. • The solutes concentration of 50% achieves the best cost-effectiveness and the economy. - Abstract: Absorption air-conditioning system is a good alternative to vapor compression system for developing low carbon society. To improve the performance of the traditional absorption system, the membrane air-conditioning system is configured and its COP can reach as high as 6. Mixed absorbents are potential for cost reduction of the membrane system while maintaining a high COP. On the purpose of finding ideal mixed absorbent groups, this paper makes analysis on COP, cost-effectiveness and economy of the membrane system with mixed LiBr–CaCl 2 absorbent solution. The models of the system have been developed for the analysis. The results show the COP is higher for the absorbent groups with lower concentration of the total solute and higher concentration ratio of LiBr. It also reveals when the total solutes concentration is about 50%, it achieves the best cost-effectiveness and the economy. The process of the analysis provides a useful method for mixed absorbents selection

Acanthamoeba belonging to T3, T4, and T11: genotypes isolated from air-conditioning units in Santiago, Chile.

Science.gov (United States)

Astorga, Berbeli; Lorenzo-Morales, Jacob; Martín-Navarro, Carmen M; Alarcón, Verónica; Moreno, Johanna; González, Ana C; Navarrete, Elizabeth; Piñero, José E; Valladares, Basilio

2011-01-01

Free-living amoebae (FLA) of the genus Acanthamoeba are widely distributed in the environment, in the air, soil, and water, and have also been isolated from air-conditioning units. The objective of this work was to investigate the presence of this genus of FLA in the air-conditioning equipment at the Institute of Public Health of Chile in Santiago, Chile. Water and air samples were collected from air-conditioning systems and were checked for the presence of Acanthamoeba spp. Positive samples were further classified at the genotype level after sequencing the highly variable diagnostic fragment 3 (DF3) region of the 18S rRNA gene. This is the first report of the T3, T4, and T11 genotypes of Acanthamoeba in air-conditioning units from Chile. Overall, the widespread distribution of potentially pathogenic Acanthamoeba strains in the studied source demands more awareness within the public and health professionals in Chile as this pathogen is emerging as a risk for human health worldwide. © 2011 The Author(s) Journal of Eukaryotic Microbiology © 2011 International Society of Protistologists.

A Bayesian localized conditional autoregressive model for estimating the health effects of air pollution.

Science.gov (United States)

Lee, Duncan; Rushworth, Alastair; Sahu, Sujit K

2014-06-01

Estimation of the long-term health effects of air pollution is a challenging task, especially when modeling spatial small-area disease incidence data in an ecological study design. The challenge comes from the unobserved underlying spatial autocorrelation structure in these data, which is accounted for using random effects modeled by a globally smooth conditional autoregressive model. These smooth random effects confound the effects of air pollution, which are also globally smooth. To avoid this collinearity a Bayesian localized conditional autoregressive model is developed for the random effects. This localized model is flexible spatially, in the sense that it is not only able to model areas of spatial smoothness, but also it is able to capture step changes in the random effects surface. This methodological development allows us to improve the estimation performance of the covariate effects, compared to using traditional conditional auto-regressive models. These results are established using a simulation study, and are then illustrated with our motivating study on air pollution and respiratory ill health in Greater Glasgow, Scotland in 2011. The model shows substantial health effects of particulate matter air pollution and nitrogen dioxide, whose effects have been consistently attenuated by the currently available globally smooth models. © 2014, The Authors Biometrics published by Wiley Periodicals, Inc. on behalf of International Biometric Society.

Assessment of the thermal environment effects on human comfort and health for the development of novel air conditioning system in tropical regions

Energy Technology Data Exchange (ETDEWEB)

Sookchaiya, Thammanoon; Monyakul, Veerapol; Thepa, Sirichai [Division of Energy Technology, School of Energy Environment and Materials, King Mongkut' s University of Technology Thonburi, Bangkok (Thailand)

2010-10-15

This research shows the result of a brainstorming by medical experts in the first ranking university medical school and hospital of Thailand. It was based on Delphi technique. The objective of this research was to study both direct and indirect effects of humidity and temperature on human health in air-conditioned buildings in Thailand. Afterwards, the result was used to design and develop split type air conditioner (conventional air conditioner) which could control relative humidity and temperature with precision air conditioning system to comply with the climate and the suitability of the people living in Thailand building. The result of operation with precision inverter air conditioning system showed that the temperature inside the room changed from the default value around {+-}0.2 C (Case 1) and around {+-}0.35 C (Case 2) and it could control relative humidity as a desired condition between 50-60% (both cases) which was the appropriate range for Thai climate. Moreover, energy consumption of precision inverter air conditioning system was still less than conventional air conditioning system for about 7.5%. This research could provide people living in Thailand air conditioned building with human thermal comfort and health. (author)

Possible schemes for solar-powered air-conditioning in 2-storey terrace houses

International Nuclear Information System (INIS)

Chu, C.M.; Bono, A.; Prabhakar, A.

2006-01-01

Space cooling is required all year round in the tropics, and probably accounts for a considerable proportion of the cost of electricity. Solar radiation can be channeled into cooling by photovoltaic powered systems and through the relatively new adsorption cycle technology. Two-storey terrace housing appear to have the greatest potential of introducing solar-powered cooling to residential homes. There are two schemes to cool a two-storey terrace housing: 1) By spraying water down the roof a tank, circulated by a pump powered by PV panels on the roof or 2) By replacing the roof with solar hot water collectors and use adsorption cooling chillers to produce air-conditioning for the entire block of terrace houses. In scheme number 1, a preliminary, rough technical evaluation showed that it is possible to pump water to the roof to flow down as a thin film and cool the roof by evaporation to about 40 degree C from about 70 degree C if without water evaporation at the highest insolation rate of the day. Scheme number 2, which uses adsorption chilling technology, requires communal sharing of the air-conditioning facility. The effect of collecting solar heat using the roof is two fold: to absorb solar energy for producing hot water and reducing excess heat input to the house. Preliminary costing demonstrates that solar-powered air-conditioning is within reach of commercialisation, bearing in mind that bulk purchases will dramatically lower the price of a product

Potential electricity savings by variable speed control of compressor for air conditioning systems

Energy Technology Data Exchange (ETDEWEB)

Nasution, Henry [Bung Hatta University, Department of Mechanical Engineering, Faculty of Industrial Engineering, Padang, West Sumatera (Indonesia); Wan Hassan, Mat Nawi [Universiti Teknologi Malaysia, Faculty of Mechanical Engineering, Skudai, Johor Bahru-Darul Ta' zim (Malaysia)

2006-05-15

The potential of a variable-speed compressor running on a controller to provide enhanced load-matching capability, energy saving and thermal comfort for application in air-conditioning system is demonstrated. An air-conditioning system, originally operated on a constant speed mode, is retrofitted with an inverter and a PID controller. The system was installed to a thermal environmental room together with a data acquisition system to monitor energy consumption and temperature of the room. Measurements were taken 2 h daily at a time interval of 5 min for an on/off and an inverter variable-speed conditions. The results indicate that thermal comfort of the room together with energy saving can be obtained through a proper selection of K for the controller. At a temperature setting of 22 C, the energy saving for the system is estimated to reach 25.3% for PID controllers. (orig.)

OPTIMIZATION OF MICROWAVE AND AIR DRYING CONDITIONS OF QUINCE (CYDONIA OBLONGA, MILLER USING RESPONSE SURFACE METHODOLOGY

Directory of Open Access Journals (Sweden)

Cem Baltacioglu

2015-03-01

Full Text Available Effects of slice thickness of quince (Cydonia oblonga Miller , microwave incident power and air drying temperature on antioxidant activity and total phenolic content of quince were investigated during drying in microwave and air drying. Optimum conditions were found to be: i for microwave drying, 285 W and 4.14 mm thick (maximum antioxidant activity and 285 W and 6.85 mm thick (maximum total phenolic content, and ii for air drying, 75 ºC and 1.2 mm thick (both maximum antioxidant activity and total phenolic content. Drying conditions were optimized by using the response surface methodology. 13 experiments were carried out considering incident microwave powers from 285 to 795 W, air temperature from 46 to 74 ºC and slice thickness from 1.2 to 6.8 mm.

Simulation of Artificial Intelligence for Automotive Air-conditioning System

Institute of Scientific and Technical Information of China (English)

YUAN Xiao-mei; CHEN You-hua; CHEN Zhi-jiu

2002-01-01

The artificial intelligence is applied to the simulation of the automotive air-conditioning system ( AACS )According to the system's characteristics a model of AACS, based on neural network, is developed. Different control methods of AACS are discussed through simulation based on this model. The result shows that the neural- fuzzy control is the best one compared with the on-off control and conventional fuzzy control method.It can make the compartment's temperature descend rapidly to the designed temperature and the fluctuation is small.

Ant-nest corrosion of copper tubing in air-conditioning units

Directory of Open Access Journals (Sweden)

Bastidas, D. M.

2006-10-01

Full Text Available Ant-nest corrosion is a specific type of premature failure (2-3 months of copper tubes used in air-conditioning units causing the loss of refrigerant liquid and the consequent environment pollution. It is known that attack requires the simultaneous presence of moisture, oxygen and a corrodent, usually an organic acid, such as formic, acetic, propionic or butyric acid or other volatile organic substances like methanol, ethanol, formaldehyde or acetoaldehyde. Approximately 10% of all premature failures of copper tubes used in the heating, ventilation and air-conditioning (HVAC industry are the result of ant-nest corrosion. This type of corrosion usually occurs in thin-wall copper pipes, especially when copper is de-sulphurised, and is known by several names: formicary corrosion, unusual corrosion, branched pits, pinhole corrosion, etc.

Corrosión por “nido de hormigas” es un tipo específico de fallo prematuro (2-3 meses que tiene lugar en tubos de cobre utilizados en sistemas de aire acondicionado originando la pérdida de líquido refrigerante y la consecuente contaminación ambiental. Es conocido que este tipo de ataque requiere la presencia simultánea de humedad, oxígeno y un medio agresivo, habitualmente un ácido orgánico, como fórmico, acético  propiónico o butírico u otras sustancias orgánicas volátiles tales como metanol, etanol, formaldehido o acetoaldehido. Aproximadamente el 10% de los fallos prematuros en tubos de cobre utilizados en calefacción, ventilación y en la industria de aire acondicionado son el resultado de corrosión por nido de hormigas. Frecuentemente, este tipo de corrosión tiene lugar en tubos de cobre de pared delgada, especialmente cuando el cobre es del tipo desulfurizado, y se conoce con varios nombres: corrosión por ácido fórmico, corrosión no habitual, picaduras ramificadas, corrosión con forma de alfiler, etc.

Assessing the impacts of seasonal and vertical atmospheric conditions on air quality over the Pearl River Delta region

Science.gov (United States)

Tong, Cheuk Hei Marcus; Yim, Steve Hung Lam; Rothenberg, Daniel; Wang, Chien; Lin, Chuan-Yao; Chen, Yongqin David; Lau, Ngar Cheung

2018-05-01

Air pollution is an increasingly concerning problem in many metropolitan areas due to its adverse public health and environmental impacts. Vertical atmospheric conditions have strong effects on vertical mixing of air pollutants, which directly affects surface air quality. The characteristics and magnitude of how vertical atmospheric conditions affect surface air quality, which are critical to future air quality projections, have not yet been fully understood. This study aims to enhance understanding of the annual and seasonal sensitivities of air pollution to both surface and vertical atmospheric conditions. Based on both surface and vertical meteorological characteristics provided by 1994-2003 monthly dynamic downscaling data from the Weather and Research Forecast Model, we develop generalized linear models (GLMs) to study the relationships between surface air pollutants (ozone, respirable suspended particulates, and sulfur dioxide) and atmospheric conditions in the Pearl River Delta (PRD) region. Applying Principal Component Regression (PCR) to address multi-collinearity, we study the contributions of various meteorological variables to pollutants' concentration levels based on the loading and model coefficient of major principal components. Our results show that relatively high pollutant concentration occurs under relatively low mid-level troposphere temperature gradients, low relative humidity, weak southerly wind (or strong northerly wind) and weak westerly wind (or strong easterly wind). Moreover, the correlations vary among pollutant species, seasons, and meteorological variables at various altitudes. In general, pollutant sensitivity to meteorological variables is found to be greater in winter than in other seasons, and the sensitivity of ozone to meteorology differs from that of the other two pollutants. Applying our GLMs to anomalous air pollution episodes, we find that meteorological variables up to mid troposphere (∼700 mb) play an important role in

The Maintenance of Heating, Ventilating and Air-Conditioning Systems and Indoor Air Quality in Schools: A Guide for School Facility Managers. Technical Bulletin.

Science.gov (United States)

Wheeler, Arthur E.

To help maintain good indoor air quality (IAQ) in schools, guidance for the development and implementation of an effective program for maintenance and operation of heating, ventilating, and air-conditioning (HVAC) systems are discussed. Frequently, a building's occupants will complain about IAQ when the temperature or humidity are at uncomfortable…

Ventilation and air conditioning system in waste treatment and storage facilities

International Nuclear Information System (INIS)

Kinoshita, Hirotsugu; Sugawara, Kazushige.

1987-01-01

So far, the measures concerning the facilities for treating and storing radioactive wastes in nuclear fuel cycle in Japan were in the state which cannot be said to be sufficient. In order to cope with this situation, electric power companies constructed and operated radioactive waste concentration and volume reduction facilities, solid waste storing facilities for drums, high level solid waste storing facilities, spent fuel cask preserving facilities and so on successively in the premises of nuclear power stations, and for the wastes expected in future, the research and the construction plan of the facilities for treating and storing low, medium and high level wastes have been advanced. The ventilation and air conditioning system for these facilities is the important auxiliary system which has the mission of maintaining safe and pleasant environment in the facilities and lowering as far as possible the release of radioactive substances to outside. The outline of waste treatment and storage facilities is explained. The design condition, ventilation and air conditioning method, the features of respective waste treatment and storage facilities, and the problems for the future are described. Hereafter, mechanical ventilation system continues to be the main system, and filters become waste, while the exchange of filters is accompanied by the radiation exposure of workers. (Kako, I.)

Performance analysis of air conditioning system and airflow simulation in an operating theater

Science.gov (United States)

Alhamid, Muhammad Idrus; Budihardjo, Rahmat

2018-02-01

The importance of maintaining performance of a hospital operating theater is to establish an adequate circulation of clean air within the room. The parameter of air distribution in a space should be based on Air Changes per Hour (ACH) to maintain a positive room pressure. The dispersion of airborne particles in the operating theater was governed by regulating the air distribution so that the operating theater meets clean room standards ie ISO 14664 and ASHRAE 170. Here, we introduced several input parameters in a simulation environment to observe the pressure distribution in the room. Input parameters were air temperature, air velocity and volumetric flow rate entering and leaving room for existing and designed condition. In the existing operating theatre, several observations were found. It was found that the outlet air velocity at the HEPA filter above the operating table was too high thus causing a turbulent airflow pattern. Moreover, the setting temperature at 19°C was found to be too low. The supply of air into the room was observed at lower than 20 ACH which is under the standard requirement. Our simulation using FloVent 8.2™ program showed that not only airflow turbulence could be reduced but also the amount of particle contamination could also be minimized.

Thermal analysis of a direct evaporative cooling system enhancement with desiccant dehumidification for vehicular air conditioning

International Nuclear Information System (INIS)

Alahmer, Ali

2016-01-01

Highlights: • Thermal analysis was conducted to design a desiccant evaporative cooling system for vehicular air conditioning. • EC is more efficient than the conventional air conditioning when the gasoline price is more than 0.34 $/liter. • Drawbacks of evaporative cooler of increased weight and reduced COP. • A rotary desiccant dehumidifier with generation was combined with evaporative cooling to be more efficient. - Abstract: This manuscript analyzes the sub-systems of evaporative cooler (EC) combined with desiccant dehumidification and regeneration for automotive air conditioning purpose. The thermodynamic and psychometric analysis was conducted to design all evaporative cooling system components in terms of desiccant selection, regeneration process, compact heat exchanger and evaporative cooler. Moreover, the effect of the desiccant, heat exchanger and evaporative performances on the mass flow rate and water sprayed required for evaporative cooling system was investigated. The results show that the theoretical evaporative cooling design will achieve two main objectives: lower fuel consumption and less environmental pollutants. However, it has the two drawbacks in terms of increased weight and reduces the coefficient of performance (COP). The main remark is that evaporating cooling system is more efficient than the conventional air conditioning when the gasoline price is more than 0.34 $/liter.

Effect of operating conditions on performance of silica gel-water air-fluidised desiccant cooler

Directory of Open Access Journals (Sweden)

Rogala Zbigniew

2017-01-01

Full Text Available Fluidised desiccant cooling is reported in the literature as an efficient way to provide cooling for air-conditioning purposes. The performance of this technology can be described by electric and thermal Coefficients of Performance (COP and Specific Cooling Power (SCP. In this paper comprehensive theoretical study was carried out in order to assess the effect of operating conditions such as: superficial air velocity, desiccant particle diameter, bed switching time and desiccant filling height on the performance of fluidised desiccant cooler (FDC. It was concluded that FDC should be filled with as small as possible desiccant particles featuring diameters and should not be operated with shorter switching times than optimum. Moreover in order to efficiently run such systems superficial air velocities during adsorption and desorption should be similar. At last substantial effect of desiccant filling height on performance of FDC was presented.

Air Filtration as Protection against Fouling of Ventilation and Air Conditioning Units

DEFF Research Database (Denmark)

Bekö, Gabriel; Lajčíková, Ariana

2005-01-01

Currently, air filters are one of the most critical components of air treatment systems as they decontaminate the air delivered to living space. During the operation, however, the level of harmful surface deposits increases, and at certain times, an uncleaned filter can itself become a source...... of undesirable contaminents influencing negatively the IAQ of a living space. This is the phenomenon that has been a subject of the current research. The article presents a new, alternative view on indoor air contaminents and filtration requirements. It describes alternative means of filtration and assesses...... issues of inadequate maintenance and/or long term use of applied air filters. An experimental method of evealuating the air quality by means of chemical analysis and state-of-the-art spectrometer is also described....

Effect of Intake Air Filter Condition on Vehicle Fuel Economy

Energy Technology Data Exchange (ETDEWEB)

Norman, Kevin M [ORNL; Huff, Shean P [ORNL; West, Brian H [ORNL

2009-02-01

The U.S. Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy and the U.S. Environmental Protection Agency (EPA) jointly maintain a fuel economy website (www.fueleconomy.gov), which helps fulfill their responsibility under the Energy Policy Act of 1992 to provide accurate fuel economy information [in miles per gallon (mpg)] to consumers. The site provides information on EPA fuel economy ratings for passenger cars and light trucks from 1985 to the present and other relevant information related to energy use such as alternative fuels and driving and vehicle maintenance tips. In recent years, fluctuations in the price of crude oil and corresponding fluctuations in the price of gasoline and diesel fuels have renewed interest in vehicle fuel economy in the United States. (User sessions on the fuel economy website exceeded 20 million in 2008 compared to less than 5 million in 2004 and less than 1 million in 2001.) As a result of this renewed interest and the age of some of the references cited in the tips section of the website, DOE authorized the Oak Ridge National Laboratory (ORNL) Fuels, Engines, and Emissions Research Center (FEERC) to initiate studies to validate and improve these tips. This report documents a study aimed specifically at the effect of engine air filter condition on fuel economy. The goal of this study was to explore the effects of a clogged air filter on the fuel economy of vehicles operating over prescribed test cycles. Three newer vehicles (a 2007 Buick Lucerne, a 2006 Dodge Charger, and a 2003 Toyota Camry) and an older carbureted vehicle were tested. Results show that clogging the air filter has no significant effect on the fuel economy of the newer vehicles (all fuel injected with closed-loop control and one equipped with MDS). The engine control systems were able to maintain the desired AFR regardless of intake restrictions, and therefore fuel consumption was not increased. The carbureted engine did show a decrease in

Urban air quality assessment using monitoring data of fractionized aerosol samples, chemometrics and meteorological conditions.

Science.gov (United States)

Yotova, Galina I; Tsitouridou, Roxani; Tsakovski, Stefan L; Simeonov, Vasil D

2016-01-01

The present article deals with assessment of urban air by using monitoring data for 10 different aerosol fractions (0.015-16 μm) collected at a typical urban site in City of Thessaloniki, Greece. The data set was subject to multivariate statistical analysis (cluster analysis and principal components analysis) and, additionally, to HYSPLIT back trajectory modeling in order to assess in a better way the impact of the weather conditions on the pollution sources identified. A specific element of the study is the effort to clarify the role of outliers in the data set. The reason for the appearance of outliers is strongly related to the atmospheric condition on the particular sampling days leading to enhanced concentration of pollutants (secondary emissions, sea sprays, road and soil dust, combustion processes) especially for ultra fine and coarse particles. It is also shown that three major sources affect the urban air quality of the location studied-sea sprays, mineral dust and anthropogenic influences (agricultural activity, combustion processes, and industrial sources). The level of impact is related to certain extent to the aerosol fraction size. The assessment of the meteorological conditions leads to defining of four downwind patterns affecting the air quality (Pelagic, Western and Central Europe, Eastern and Northeastern Europe and Africa and Southern Europe). Thus, the present study offers a complete urban air assessment taking into account the weather conditions, pollution sources and aerosol fractioning.

Thermodynamic model of a thermal storage air conditioning system with dynamic behavior

Energy Technology Data Exchange (ETDEWEB)

Fleming, E; Wen, SY; Shi, L; da Silva, AK

2013-12-01

A thermodynamic model was developed to predict transient behavior of a thermal storage system, using phase change materials (PCMs), for a novel electric vehicle climate conditioning application. The main objectives of the paper are to consider the system's dynamic behavior, such as a dynamic air flow rate into the vehicle's cabin, and to characterize the transient heat transfer process between the thermal storage unit and the vehicle's cabin, while still maintaining accurate solution to the complex phase change heat transfer. The system studied consists of a heat transfer fluid circulating between either of the on-board hot and cold thermal storage units, which we refer to as thermal batteries, and a liquid-air heat exchanger that provides heat exchange with the incoming air to the vehicle cabin. Each thermal battery is a shell-and-tube configuration where a heat transfer fluid flows through parallel tubes, which are surrounded by PCM within a larger shell. The system model incorporates computationally inexpensive semianalytic solution to the conjugated laminar forced convection and phase change problem within the battery and accounts for airside heat exchange using the Number of Transfer Units (NTUs) method for the liquid-air heat exchanger. Using this approach, we are able to obtain an accurate solution to the complex heat transfer problem within the battery while also incorporating the impact of the airside heat transfer on the overall system performance. The implemented model was benchmarked against a numerical study for a melting process and against full system experimental data for solidification using paraffin wax as the PCM. Through modeling, we demonstrate the importance of capturing the airside heat exchange impact on system performance, and we investigate system response to dynamic operating conditions, e.g., air recirculation. (C) 2013 Elsevier Ltd. All rights reserved.

Exergy characteristics of a ceiling-type residential air conditioning system operating under different climatic conditions

Energy Technology Data Exchange (ETDEWEB)

Ozbek, Arif [Dept. of Mechanical Engineering, Ceyhan Engineering Faculty, Cukurova University, Adana (Turkmenistan)

2016-11-15

In this study an energy and exergy analysis of a Ceiling-type residential air conditioning (CTRAC) system operating under different climatic conditions have been investigated for provinces within the different geographic regions of Turkey. Primarily, the hourly cooling load capacities of a sample building (Q{sub evap}) during the months of April, May, June, July, August and September were determined. The hourly total heat gain of the sample building was determined using the Hourly analysis program (HAP). The Coefficient of performance (COP), exergy efficiency (η) and exergy destruction (Ex{sub dest}) values for the whole system and for each component were obtained. The results showed that lower atmospheric temperature (T{sub atm}) influenced the performance of the system and each of its components.

Evaluation of Heating, Ventilation, and Air conditioning (HVAC System Performance in an Administrative Building in Tehran (Iran

Directory of Open Access Journals (Sweden)

H. Mari Oriyad

2014-09-01

Full Text Available Introduction: One of the factors influencing on indoor air quality of the buildings is performance of HVAC (heating, ventilation, and air conditioning systems. These systems supply clean and odorless air, with temperature, humidity, and air velocity within comfort ranges for the residents. The aim of this study was to evaluate performance HVAC system in an administrative building in Tehran. .Material and Method: A questionnaire, developed in their research was used to assess the building occupants’ perception about the performance of HVAC system. To evaluate the performance of HVAC systems, air velocities were measured in the diffusers using a thermal anemometer. Moreover, CO2 concentration, air temperature and relative humidity were measured in the whole floors of the building. Air distribution inside the building was evaluated using smoke test. .Results: Most of the studied people complained about the direction of airflow, thermal conditions and cigarette odor. The highest level of carbon dioxide was measured at 930 ppm inside the restaurant. The maximum and minimum air temperatures and relative humidity were measured 28.3-13.8° C and 28.4-23% respectively. Smoke test showed that the air distribution/direction wasn’t suitable in one third of air diffusers. .Conclusion: Improper air distribution / direction was the main problem with the studied HVAC system which could be corrected by adjusting and balancing of the system.

Air conditioning and power generation for residential applications using liquid nitrogen

International Nuclear Information System (INIS)

Ahmad, Abdalqader; Al-Dadah, Raya; Mahmoud, Saad

2016-01-01

Highlights: • Using liquid nitrogen to provide power and air conditioning for domestic applications. • The proposed system leads to save energy and reduce the peak electricity demands. • Compared with conventional AC saving up to 36% was achieved at the current LN2 price. • The widespread of this technology leads to lower LN2 price and saving up to 81%. • The last configuration was the efficient system with overall thermal efficiency 74%. - Abstract: Current air conditioning (AC) systems consume a significant amount of energy, particularly during peak times where most electricity suppliers face difficulties to meet the users’ demands, and the global demands for AC systems have increased rapidly over the last few decades leading to significant power consumption and carbon dioxide emissions. This paper presents a new technique that uses liquid nitrogen (LN2) produced from renewable energy sources, or surplus electricity at off peak times, to provide cooling and power for domestic houses. Thermodynamic analyses of various cryogenic cycles have been carried out to achieve the most effective configuration that produces the maximum power output with minimum LN2 flow rate, to meet the required cooling of a 170 m"2 dwelling in Libya. A comparison with a conventional AC system was also made. Results showed that at the current LN2 prices, using LN2 to provide cooling and power demands of residential buildings is feasible and saves up to 36% compared to conventional air conditioning systems with an overall thermal efficiency of 74%. However, as the LN2 price decreases to around 1.3 pence per kg, the proposed technology will have significant advantages compared to conventional AC systems with savings of up to 81%.

V-TECS Guide for Automobile Air Conditioning and Electrical System Technician.

Science.gov (United States)

Meyer, Calvin F.; Benson, Robert T.

This curriculum guide provides an outline for an eight-unit course to train automobile air conditioning and electrical system technicians. Each unit focuses on a duty that is composed of a number of performance objectives. For each objective, these materials are provided: a task, a standard of performance of task, source of standard, conditions…

Exploring policy strategies for mitigating HFC emissions from refrigeration and air conditioning

NARCIS (Netherlands)

Hekkenberg, M.; Uiterkamp, Anton J. M. Schoot

The growing demand for cooling throughout the world, possibly increased by global climate change, requires the implementation of policies to mitigate the related greenhouse gas (GHG) emissions from energy and refrigerant use in the refrigeration and air conditioning (RAC) sector. This article aims

Liquid over-feeding air conditioning system and method

Science.gov (United States)

Mei, V.C.; Chen, F.C.

1993-09-21

A refrigeration air conditioning system utilizing a liquid over-feeding operation is described. A liquid refrigerant accumulator-heat exchanger is placed in the system to provide a heat exchange relationship between hot liquid refrigerant discharged from condenser and a relatively cool mixture of liquid and vaporous refrigerant discharged from the evaporator. This heat exchange relationship substantially sub-cools the hot liquid refrigerant which undergoes little or no evaporation across the expansion device and provides a liquid over-feeding operation through the evaporator for effectively using 100 percent of evaporator for cooling purposes and for providing the aforementioned mixture of liquid and vaporous refrigerant. 1 figure.

Badly maintained air conditioning installations (Part 2); Schlecht gewartete Klimaanlagen (Teil 2)

Energy Technology Data Exchange (ETDEWEB)

Haefliger, P. E.; Thies, U.

2002-07-01

This article is the second of a series of four articles that discuss hygiene problems that often occur in ventilation and air-conditioning installations. They describe the problems encountered in detail, provide the reader with appropriate know-how on hygiene-related topics and present an overview of the regulations appertaining to the problems along with inspection and analysis methods. In particular, this second article examines the so-called 'Sick Building Syndrome', its technical, chemical, biological and psychosocial causes and mentions the results of studies made in this area. Typical illnesses such as allergic alveolitis and legionnaires illness are discussed. Definitions of hygiene and comfort with respect to ventilation and air-conditioning installations are presented and problem areas such as filters, ducting, humidifiers and cooling are discussed. The article is rounded off - as are all articles of this series - with a comprehensive literature list.

Tourists' attitudes towards ban on smoking in air-conditioned hotel lobbies in Thailand.

Science.gov (United States)

Viriyachaiyo, V; Lim, A

2009-06-01

Thailand is internationally renowned for its stringent tobacco control measures. In Thailand, a regulation banning smoking in air-conditioned hotel lobbies was issued in late 2006, causing substantial apprehension within the hospitality industry. A survey of tourists' attitudes toward the ban was conducted. A cross-sectional survey of 5550 travellers staying in various hotels in Bangkok, Surat Thani, Phuket, Krabi and Songkhla provinces, October 2005 to December 2006. Travellers aged 15 years or older with a check-in duration of at least one day and willing to complete the questionnaire were requested by hotel staff to fill in the 5-minute questionnaire at check-in or later at their convenience. Secondhand cigarette smoke was recognised as harmful to health by 89.7% of respondents. 47.8% of travellers were aware of the Thai regulation banning smoking in air-conditioned restaurants. 80.9% of the respondents agreed with the ban, particularly female non-smokers. 38.6% of survey respondents indicated that they would be more likely to visit Thailand again because of the regulation, 53.4% that the regulation would not affect their decision and 7.9% that they would be less likely to visit Thailand again. Banning smoking in air-conditioned hotel lobbies in Thailand is widely supported by tourists. Enforcement of the regulation is more likely to attract tourists than dissuade them from holidaying in Thailand.

CFD SIMULATION OF AIR ION REGIME IN WORK AREAS AT CONDITION OF ARTIFICIAL AIR IONIZATION

Directory of Open Access Journals (Sweden)

M. M. Biliaiev

2016-02-01

sources and ions of different polarity; physical processes affecting the formation of ions concentration field. Practical value. The obtained 2D CFD model for calculating the air ions regime in working areas allow to calculate the concentration of ions at the location of the respiratory organs, taking into account the basic physical factors determining the formation of ions concentration fields. It will allow rationally arranged the ionizers in the working premises to create the comfortable working conditions for staff.

Identifying Potential Area and Financial Prospects of Rooftop Solar Photovoltaics (PV

Directory of Open Access Journals (Sweden)

Sarawut Ninsawat

2016-10-01

Full Text Available In an urban area, the roof is the only available surface that can be utilized for installing solar photovoltaics (PV, and the active surface area depends on the type of roof. Shadows on a solar panel can be caused by nearby tall buildings, construction materials such as water tanks, or the roof configuration itself. The azimuth angle of the sun varies, based on the season and the time of day. Therefore, the simulation of shadow for one or two days or using the rule of thumb may not be sufficient to evaluate shadow effects on solar panels throughout the year. In this paper, a methodology for estimating the solar potential of solar PV on rooftops is presented, which is particularly applicable to urban areas. The objective of this method is to assess how roof type and shadow play a role in potentiality and financial benefit. The method starts with roof type extraction from high-resolution satellite imagery, using Object Base Image Analysis (OBIA, the generation of a 3D structure from height data and roof type, the simulation of shadow throughout the year, and the identification of potential and financial prospects. Based on the results obtained, the system seems to be adequate for calculating the financial benefits of solar PV to a very fine scale. The payback period varied from 7–13 years depending on the roof type, direction, and shadow impact. Based on the potentiality, a homeowner can make a profit of up to 200%. This method could help homeowners to identify potential roof area and economic interest.

Anti-seismic air condition's cooling capability increase of the second control area

International Nuclear Information System (INIS)

Pan Qiang

2008-01-01

Secondary area (SCA) air-conditioning system is an important ventilation system in plant. It should achieve the indoor temperature controllable. To resolve the problem of cooling capacity insufficiency, on the basis of ventilation and refrigeration theory, the thesis analyzes the design modification plan. (author)

Burnout behaviour of bituminous coals in air-staged combustion conditions

Energy Technology Data Exchange (ETDEWEB)

Kluger, F.; Spliethoff, H.; Hein, K.R.G. [University of Stuttgart, Stuttgart (Germany). Inst. of Process Engineering and Power Plant (IVD)

2001-07-01

In order to determine the influence on burnout by the combustion conditions and the coal preparation, three bituminous coals sold on the world market, from three different locations in Poland, South Africa, and Australia, were studied more closely. For this purpose, the coals were ground in two different particle size ranges, which, besides the influence of the combustion conditions, such a temperature, residence time, and stoichiometry, made it possible to also investigate the impact on burnout by the coal preparation. The experiments were carried out in an electrically heated entrained-flow reactor with a thermal input of 8.5 kW. The parameters for the experiments are wall temperature (1000-1350{degree}C), air ratio (0.6-1.15) and two particle sizes (70% {lt} 75 {mu}m, 90% {lt} 75 {mu}m). The results show that in general, for increasing temperatures, the burnout quality will improve. For the Australian Illawara coal, another outcome is increased NOx emissions. Lowering the air ratio in the reduction zone leads to less NOx emission but to increased unburnt matter in ash. For the smaller particle size fraction, the analysis of the different particle sizes shows an improvement of the burnout without a change in NOx emissions. 10 refs., 10 figs., 2 tabs.

2011 German refrigeration and air conditioning meeting. Proceedings; Deutsche Kaelte-Klima-Tagung 2011. Tagungsbericht

Energy Technology Data Exchange (ETDEWEB)

NONE

2011-07-01

Within the DKV conference of the Deutscher Kaelte- und Klimatechnischer Verein e.V. (Hanover, Federal Republic of Germany) from 16th to 18th November, 2011, at the Eurogress Aachen (Federal Republic of Germany) 112 lectures were held according to the following themes: cryomedicine, cryobiology, cryocomponents, mobility, cryoapplications, miniature cooler, Fundamentals and materials in the cryotechnology and heat pump technology, heat transfer, absorption processes, materials characteristics and phase change materials, storage and phase change, plants and components of refrigerating and heat pump technology - compressors, control and systems, energy efficiency (and CO{sub 2}), standardization and standard, application of refrigeration, supermarket/coolant, enhancement of efficiency in the air conditioning of passenger cars, indoor air conditioning in automobiles, enhancement of efficiency in different vehicles, climate technology and application of heat pumps - field tests and optimization, test rigs and simulations, heat pumps, optimisation in new buildings and stock buildings, climate coolants and quality of air. Beside this conference twelve student meetings were presented.

Colonization by Cladosporium spp. of painted metal surfaces associated with heating and air conditioning systems

Science.gov (United States)

Ahearn, D. G.; Simmons, R. B.; Switzer, K. F.; Ajello, L.; Pierson, D. L.

1991-01-01

Cladosporium cladosporioides and C. hebarum colonized painted metal surfaces of covering panels and register vents of heating, air conditioning and ventilation systems. Hyphae penetrated the paint film and developed characteristic conidiophores and conidia. The colonies were tightly appressed to the metal surface and conidia were not readily detectable via standard air sampling procedures.

Open absorption system for cooling and air conditioning using membrane contactors - Final report

Energy Technology Data Exchange (ETDEWEB)

Conde-Petit, M. [M. Conde Engineering, Zuerich (Switzerland); Weber, R.; Dorer, V. [Swiss Federal Laboratories for Materials Testing and Research (EMPA), Duebendorf (Switzerland)

2008-07-01

Air conditioning systems based upon the open absorption principle, essentially an absorption device operating at atmospheric pressure, have been proposed and investigated at many instances in the past eighty years. Their potential for improving energy efficiency is clearly recognized in the earliest research reports. By the mid 1950ies, solar thermal energy was being applied to drive open absorption-based air conditioning systems. For several reasons, however, the open absorption technology was not mature enough to take place in the mainstream. In the past two decades, vigorous efforts have been undertaken to reverse this situation, but success continued to elude, despite the fact that the main problems, such as corrosion, aerosols in the supply air, etc., have been identified. This report details the work and the main results from the MemProDEC Project. In this project innovative solutions were proposed, and successfully investigated, for the corrosion problem and the improvement of efficiency of the absorption process, in particular a new method to cool a very compact absorber. The practically uniform flow distribution for all three streams in the absorber (air, water and desiccant) warrants the contact of the air to be dehumidified with the desiccant over the whole surface of exchange (across a porous membrane). This, together with the cooling with water in counter flow to the air, are the key factors for the excellent effectiveness of the absorber. As the results show, the dehydration effectiveness of the prototype absorber is up to 150 % higher than that previously obtained by others. The solutions developed for compactness and modularity represent an important step in the way to flexible manufacturing, i.e. using a single element size to assemble autonomous air handling units of various nominal capacities. And although the manufacturing methods of the individual elements require improvement, namely by avoiding adhesive bonding, the choice of materials and the

Greenhouse effect: an issue for the refrigeration and air conditioning sector; Effet de serre: quelle problematique pour le froid et le conditionnement de l`air?

Energy Technology Data Exchange (ETDEWEB)

Billiard, F. [Institut International du Froid, 75 - Paris (France)

1997-12-31

The principles of greenhouse effect and the greenhouse gas main direct and indirect emission sources due to refrigeration and air conditioning systems are first reviewed. Evolution scenarios from 1992 to 2020 and 2100 for the emissions of CFC, HCFC and HFC are presented and related to the Kyoto protocol project limitations; technical improvements in refrigerating and air conditioning systems (lower refrigerant utilization, fluid confinement, alternative technologies, natural refrigerant utilization, etc.) could lead to substantial diminutions of these greenhouse gases

Effect of air condition on AP-1000 containment cooling performance in station black out accident

International Nuclear Information System (INIS)

Hendro Tjahjono

2015-01-01

AP1000 reactor is a nuclear power plant generation III+ 1000 MWe which apply passive cooling concept to anticipate accidents triggered by the extinction of the entire supply of electrical power or Station Black Out (SBO). In the AP1000 reactor, decay heat disposal mechanism conducted passively through the PRHR-IRWST and subsequently forwarded to the reactor containment. Containment externally cooled through natural convection in the air gap and through evaporation cooling water poured on the outer surface of the containment wall. The mechanism of evaporation of water into the air outside is strongly influenced by the conditions of humidity and air temperature. The purpose of this study was to determine the extent of the influence of the air condition on cooling capabilities of the AP1000 containment. The method used is to perform simulations using Matlab-based analytical calculation model capable of estimating the power of heat transferred. The simulation results showed a decrease in power up to 5% for relative humidity rose from 10% to 95%, while the variation of air temperature of 10°C to 40°C, the power will decrease up to 15%. It can be concluded that the effect of air temperature increase is much more significant in lowering the containment cooling ability compared with the increase of humidity. (author)

Investigation of air cleaning system response to accident conditions

International Nuclear Information System (INIS)

Andrae, R.W.; Bolstad, J.W.; Foster, R.D.; Gregory, W.S.; Horak, H.L.; Idar, E.S.; Martin, R.A.; Ricketts, C.I.; Smith, P.R.; Tang, P.K.

1980-01-01

Air cleaning system response to the stress of accident conditions are being investigated. A program overview and hghlight recent results of our investigation are presented. The program includes both analytical and experimental investigations. Computer codes for predicting effects of tornados, explosions, fires, and material transport are described. The test facilities used to obtain supportive experimental data to define structural integrity and confinement effectiveness of ventilation system components are described. Examples of experimental results for code verification, blower response to tornado transients, and filter response to tornado and explosion transients are reported

Investigating performance of microchannel evaporators for automobile air conditioning with different port structures

Directory of Open Access Journals (Sweden)

Guoliang Zhou

2017-08-01

Full Text Available Microchannel evaporator has been widely applied in automobile air conditioning, while it faces the problem of refrigerant maldistribution which deteriorates the thermal performance of evaporator. In this study, the performances of microchannel evaporators with different port structures are experimentally investigated for purpose of reducing evaporator pressure drop. Four evaporator samples with different port number and hydraulic diameter are made for this study. The performances of the evaporator samples are tested on a psychometric calorimeter test bench with the refrigerant R-134A at a real automobile air conditioning. The results on the variations of the evaporator pressure drop and evaporator surface temperature distribution are presented and analyzed. By studying the performance of an evaporator, seeking proper port structure is an approach to reduce refrigerant pressure drop as well as improve refrigerant distribution.

Low-Flow Liquid Desiccant Air-Conditioning: Demonstrated Performance and Cost Implications

Energy Technology Data Exchange (ETDEWEB)

Kozubal, E.; Herrmann, L.; Deru, M.; Clark, J.; Lowenstein, A.

2014-09-01

Cooling loads must be dramatically reduced when designing net-zero energy buildings or other highly efficient facilities. Advances in this area have focused primarily on reducing a building's sensible cooling loads by improving the envelope, integrating properly sized daylighting systems, adding exterior solar shading devices, and reducing internal heat gains. As sensible loads decrease, however, latent loads remain relatively constant, and thus become a greater fraction of the overall cooling requirement in highly efficient building designs, particularly in humid climates. This shift toward latent cooling is a challenge for heating, ventilation, and air-conditioning (HVAC) systems. Traditional systems typically dehumidify by first overcooling air below the dew-point temperature and then reheating it to an appropriate supply temperature, which requires an excessive amount of energy. Another dehumidification strategy incorporates solid desiccant rotors that remove water from air more efficiently; however, these systems are large and increase fan energy consumption due to the increased airside pressure drop of solid desiccant rotors. A third dehumidification strategy involves high flow liquid desiccant systems. These systems require a high maintenance separator to protect the air distribution system from corrosive desiccant droplet carryover and so are more commonly used in industrial applications and rarely in commercial buildings. Both solid desiccant systems and most high-flow liquid desiccant systems (if not internally cooled) add sensible energy which must later be removed to the air stream during dehumidification, through the release of sensible heat during the sorption process.