Aging assessment of essential HVAC chillers used in nuclear power plants

Energy Technology Data Exchange (ETDEWEB)

Blahnik, D.E.; Camp, T.W.

1996-09-01

The Pacific Northwest Laboratory conducted a comprehensive aging assessment of chillers used in the essential safety air-conditioning systems in nuclear power plants (NPPs). The chillers used, and air-conditioning systems served, vary in design from plant to plant. The review of operating experience indicated that chillers experience aging degradation and failures. The primary aging factors of concern for chillers include vibration, excessive temperatures and pressures, thermal cycling, chemical attack, and poor quality cooling water. The evaluation of Licensee Event Reports (LERs) indicated that about 38% of the failures were primarily related to aging, 55% were partially aging related, and 7% of the failures were unassignable. About 25% of the failures were primarily caused by human, design, procedure, and other errors. The large number of errors is probably directly related to the complexity of chillers and their interfacing systems. Nearly all of the LERs were the result of entering plant Technical Specification Limiting Condition for Operation (LCO) that initiated remedial actions like plant shutdown procedures. The trend for chiller-related LERs has stabilized at about 0.13 LERs per plant year since 1988. Carefully following the vendor procedures and monitoring the equipment can help to minimize and/or eliminate most of the premature failures. Recording equipment performance can be useful for trending analysis. Periodic operation for a few hours on a weekly or monthly basis is useful to remove moisture and non-condensable gases that gradually build up inside the chiller. Chiller pressurization kits are available that will help minimize the amount of moisture and air ingress to low-pressure chillers during standby periods. The assessment of service life condition monitoring of chillers indicated there are many simple to sophisticated methods available that can help in chiller surveillance and monitoring.

Energy and Exergy Analysis for Improving the Energy Performance of Air-Cooled Liquid Chillers by Different Condensing-Coil Configurations

Directory of Open Access Journals (Sweden)

Tzong-Shing Lee

2012-03-01

Full Text Available This study constructed a parameter analysis for improving the energy performance of air-cooled water chillers by altering the angle configuration of the condenser coils. The mathematical models for energy and exergy analyses of the individual components and overall system of air-cooled water chillers are presented. This study investigated the potential enhancement of performance efficiency in air-cooled chillers and the energy conversion efficiency of each component, in order to determine how the angle configuration of condenser coils influences chiller performance. This study found that the overall performance of an air-cooled chiller could be improved by approximately 3.4%, and the total irreversibility could be reduced by approximately 2.7%. With each 1% increase in average wind speed over the condenser coils, the overall performance of an air‑cooled chiller was found to be enhanced by approximately 0.43%, and its total irreversibility was reduced by approximately 0.35%. The results of this study can be effectively applied to air-cooled condenser units, and can provide an important basis of reference for developing and enhancing the energy efficiency of air-cooled chillers.

Thermodynamic-behaviour model for air-cooled screw chillers with a variable set-point condensing temperature

International Nuclear Information System (INIS)

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

2006-01-01

This paper presents a thermodynamic model to evaluate the coefficient of performance (COP) of an air-cooled screw chiller under various operating conditions. The model accounts for the real process phenomena, including the capacity control of screw compressors and variations in the heat-transfer coefficients of an evaporator and a condenser at part load. It also contains an algorithm to determine how the condenser fans are staged in response to a set-point condensing temperature. The model parameters are identified, based on the performance data of chiller specifications. The chiller model is validated using a wide range of operating data of an air-cooled screw chiller. The difference between the measured and modelled COPs is within ±10% for 86% of the data points. The chiller's COP can increase by up to 115% when the set-point condensing temperature is adjusted, based on any given outdoor temperature. Having identified the variation in the chiller's COP, a suitable strategy is proposed for air-cooled screw chillers to operate at maximum efficiency as much as possible when they have to satisfy a building's cooling-load

Design and experimental analysis of a carbon dioxide transcritical chiller for commercial refrigeration

International Nuclear Information System (INIS)

Cecchinato, Luca; Chiarello, Manuel; Corradi, Marco

2010-01-01

Carbon dioxide is an interesting solution for commercial refrigeration and in perspective for air-conditioning systems. In this paper a newly developed carbon dioxide transcritical air cooled chiller for refrigerating propylene glycol down to -8 o C supply temperature is described. The aim of the project was at optimising the cycle energy efficiency while assuring reliable operation and simple management of the unit. The carbon dioxide optimal pressure issue is addressed with an innovate system architecture and control logic. Using a flash tanks and two electronic valves, the optimal cycle upper pressure was maintained in transcritical operation mode. The managing of the valves allows the refrigeration machine efficiency improvement when the gas cooler inlet air allows subcritical working conditions. A simulation model of the chiller was developed and its results validated with experimental data. A measurement campaign was carried out, testing the chiller at external temperatures ranging from 18 to 35 o C, the unit energy efficiency ranging from 3.1 to 2.0.

Experimental Investigation of a Mechanical Vapour Compression Chiller at Elevated Chilled Water Temperatures

KAUST Repository

Thu, Kyaw; Saththasivam, Jayaprakash; Saha, Bidyut Baran; Chua, Kian Jon; Srinivasa Murthy, S.; Ng, Kim Choon

2017-01-01

The performance of a Mechanical Vapour Compression (MVC) chiller is experimentally investigated under operating conditions suitable for sensible cooling. With the emergence of the energy efficient dehumidification systems, it is possible to decouple the latent load from the MVC chillers which can be operated at higher chilled water temperature for handling sensible cooling load. In this article, the performance of the chiller is evaluated at the elevated chilled water outlet temperatures (7 – 17° C) at various coolant temperatures (28 – 32° C) and flow rates (ΔT = 4 and 5° C) for both full- and part-load conditions. Keeping the performance at the AHRI standard as the baseline condition, the efficacy of the chiller in terms of compression ratio, cooling capacity and COP at aforementioned conditions is quantified experimentally. It is observed that for each one-degree Celsius increase in the chilled water temperature, the COP of the chiller improves by about 3.5% whilst the cooling capacity improvement is about 4%. For operation at 17° C chilled water outlet temperature, the improvements in COP and cooling capacity are between 37 – 40% and 40 – 45%, respectively, compared to the performance at the AHRI standards. The performance of the MVC chiller at the abovementioned operation conditions is mapped on the chiller performance characteristic chart.

Experimental Investigation of a Mechanical Vapour Compression Chiller at Elevated Chilled Water Temperatures

KAUST Repository

Thu, Kyaw

2017-05-18

The performance of a Mechanical Vapour Compression (MVC) chiller is experimentally investigated under operating conditions suitable for sensible cooling. With the emergence of the energy efficient dehumidification systems, it is possible to decouple the latent load from the MVC chillers which can be operated at higher chilled water temperature for handling sensible cooling load. In this article, the performance of the chiller is evaluated at the elevated chilled water outlet temperatures (7 – 17° C) at various coolant temperatures (28 – 32° C) and flow rates (ΔT = 4 and 5° C) for both full- and part-load conditions. Keeping the performance at the AHRI standard as the baseline condition, the efficacy of the chiller in terms of compression ratio, cooling capacity and COP at aforementioned conditions is quantified experimentally. It is observed that for each one-degree Celsius increase in the chilled water temperature, the COP of the chiller improves by about 3.5% whilst the cooling capacity improvement is about 4%. For operation at 17° C chilled water outlet temperature, the improvements in COP and cooling capacity are between 37 – 40% and 40 – 45%, respectively, compared to the performance at the AHRI standards. The performance of the MVC chiller at the abovementioned operation conditions is mapped on the chiller performance characteristic chart.

Performance characteristics of single effect lithium bromide/ water absorption chiller for small data centers

Science.gov (United States)

Mysore, Abhishek Arun Babu

A medium data center consists of servers performing operations such as file sharing, collaboration and email. There are a large number of small and medium data centers across the world which consume more energy and are less efficient when compared to large data center facilities of companies such as GOOGLE, APPLE and FACEBOOK. Such companies are making their data center facilities more environmental friendly by employing renewable energy solutions such as wind and solar to power the data center or in data center cooling. This not only reduces the carbon footprint significantly but also decreases the costs incurred over a period of time. Cooling of data center play a vital role in proper functioning of the servers. It is found that cooling consumes about 50% of the total power consumed by the data center. Traditional method of cooling includes the use of mechanical compression chillers which consume lot of power and is not desirable. In order to eliminate the use of mechanical compressor chillers renewable energy resources such as solar and wind should be employed. One such technology is solar thermal cooling by means of absorption chiller which is powered by solar energy. The absorption chiller unit can be coupled with either flat plate or evacuated tube collectors in order to achieve the required inlet temperature for the generator of the absorption chiller unit. In this study a modular data center is considered having a cooling load requirement of 23kw. The performance characteristics of a single stage Lithium Bromide/ water refrigeration is presented in this study considering the cooling load of 23kw. Performance characteristics of each of the 4 heat exchangers within the unit is discussed which helps in customizing the unit according to the users' specific needs. This analysis helps in studying the importance of different properties such as the effect of inlet temperatures of hot water for generator, inlet temperatures of cooling water for absorber and

Prediction of Chiller Power Consumption: An Entropy Generation Approach

KAUST Repository

Saththasivam, Jayaprakash

2016-06-21

Irreversibilities in each component of vapor compression chillers contribute to additional power consumption in chillers. In this study, chiller power consumption was predicted by computing the Carnot reversible work and entropy generated in every component of the chiller. Thermodynamic properties namely enthalpy and entropy of the entire refrigerant cycle were obtained by measuring the pressure and temperature at the inlet and outlet of each primary component of a 15kW R22 water cooled scroll chiller. Entropy generation of each component was then calculated using the First and Second Laws of Thermodynamics. Good correlation was found between the measured and computed chiller power consumption. This irreversibility analysis can be also effectively used as a performance monitoring tool in vapor compression chillers as higher entropy generation is anticipated during faulty operations.

Energy Efficiency Evaluation and Economic Feasibility Analysis of a Geothermal Heating and Cooling System with a Vapor-Compression Chiller System

Directory of Open Access Journals (Sweden)

Muharrem Imal

2015-09-01

Full Text Available Increasing attention has been given to energy utilization in Turkey. In this report, we present an energy efficiency evaluation and economic feasibility analysis of a geothermal heating and cooling system (GSHP and a mechanical compression water chiller system (ACHP to improve the energy utilization efficiency and reduce the primary energy demand for industrial use. Analyses of a mechanical water chiller unit, GSW 180, and geothermal heating and cooling system, EAR 431 SK, were conducted in experimental working areas of the office buildings in a cigarette factory in Mersin, Turkey. The heating and cooling loads of the cigarette factory building were calculated, and actual thermal data were collected and analyzed. To calculate these loads, the cooling load temperature difference method was used. It was concluded that the geothermal heating and cooling system was more useful and productive and provides substantial economic benefits.

Absorption chillers: Part of the solution

International Nuclear Information System (INIS)

Occhionero, A.J.; Hughes, P.J.; Reid, E.A.

1991-01-01

Acid rain, ozone depletion, global warming, and implementation economics are considered as they relate to the advisability of expanding the application of absorption chillers. Introductory and background information are provided to put the discussion in the proper context. Then all four issues are discussed separately as they relate to absorption chillers. Acid rain and ozone depletion concerns, and implementation economics, are found to support the expanded use of absorption chillers. The global warming concern is found to be more of a gray area, but the areas of benefit correspond well with the conditions of greatest economic advantage. All things considered, absorption chillers are believed to be part of the environmental and economic solution. It is further believed that integrated resource planning (IRP) processes that consider electric and gas technologies on an equal footing would come to the same conclusion for many regions of the United States. 9 refs., 3 tabs

Simulation Model for Dynamic Operation of Double-Effect Absorption Chillers

Directory of Open Access Journals (Sweden)

Ahmed Mojahid Sid Ahmed Mohammed Salih

2014-07-01

Full Text Available The development in the field of refrigeration and air conditioning systems driven by absorption cycles acquired a considerable importance recently. For commercial absorption chillers, an essential challenge for creating chiller model certainly is the shortage of components technical specifications. These kinds of specifications are usually proprietary for chillers producers. In this paper, a double-effect parallel-flow-type steam absorption chiller model based on thermodynamic and energy equations is presented. The chiller studied is Lithium bromide-water with capacity of 1250 RT (Refrigeration Tons. The governing equations of the dynamic operation of the chiller are developed. From available design information, the values of the overall heat transfer coefficients multiplied by the surface area are computed. The dynamic operation of the absorption chiller is simulated to study the performance of the system. The model is able to provide essential details of the temperature, concentration, and flow rate at each state point in the chiller.

Energy optimization methodology of multi-chiller plant in commercial buildings

International Nuclear Information System (INIS)

Thangavelu, Sundar Raj; Myat, Aung; Khambadkone, Ashwin

2017-01-01

This study investigates the potential energy savings in commercial buildings through optimized operation of a multi-chiller plant. The cooling load contributes 45–60% of total power consumption in commercial and office buildings, especially at tropics. The chiller plant operation is not optimal in most of the existing buildings because the chiller plant is either operated at design condition irrespective of the cooling load or optimized locally due to lack of overall chiller plant behavior. In this study, an overall energy model of chiller plant is developed to capture the thermal behavior of all systems and their interactions including the power consumption. An energy optimization methodology is proposed to derive optimized operation decisions for chiller plant at regular intervals based on building thermal load and weather condition. The benefits of proposed energy optimization methodology are examined using case study problems covering different chiller plant configurations. The case studies result confirmed the energy savings achieved through optimized operations is up to 40% for moderate size chiller plant and around 20% for small chiller plant which consequently reduces the energy cost and greenhouse gas emissions. - Highlights: • Energy optimization methodology improves the performance of multi-chiller plant. • Overall energy model of chiller plant accounts all equipment and the interactions. • Operation decisions are derived at regular interval based on time-varying factors. • Three case studies confirmed 20 to 40% of energy savings than conventional method.

Studies on Steam Absorption Chillers Performance at a Cogeneration Plant

Directory of Open Access Journals (Sweden)

Abd Majid Mohd Amin

2014-07-01

Full Text Available Absorption chillers at cogeneration plants generate chilled water using steam supplied by heat recovery steam generators. The chillers can be of either single-effect or double effect configuration and the coefficient of performance (COP depends on the selection made. The COP varies from 0.7 to 1.2 depending on the types of chillers. Single effect chillers normally have COP in the range of 0.68 to 0.79. Double effect chillers COP are higher and can reach 1.2. However due to factors such as inappropriate operations and maintenance practices, COP could drop over a period of time. In this work the performances of double effect steam absorption chillers at a cogeneration plant were studied. The study revealed that during the period of eleven years of operation the COP of the chillers deteriorated from 1.25 to 0.6. Regression models on the operation data indicated that the state of deterioration was projected to persist. Hence, it would be recommended that the chillers be considered for replacement since they had already undergone a series of costly repairs.

Experimental investigation on the optimal performance of Zeolite-water adsorption chiller

KAUST Repository

Myat, Aung

2013-02-01

This paper presents the performance testing of Zeolite adsorption cooling system driven by low grade waste heat source extracted from prime mover\\'s exhaust, power plant\\'s exhaust and the solar energy. The adsorbent FAM Z01 is used as an adsorbent in the adsorption chiller facility. Owing to its large equilibrium pore volume, it has the high affinity for the water vapor adsorbate. The key advantages of the Zeolite adsorption cooling system are: (i) it has no moving parts rendering less maintenance, (ii) the energy efficient means of cooling by the adsorption process with a low temperature heat source, (iii) the use of vapor pipes are replaced by self actuating vapor valves rendering smaller footprint area and (iv) it is environmental friendly with low carbon footprint. The experimental investigations were carried out for Zeolite adsorption chiller at different key operating conditions namely (i) heat source temperature, (ii) the cycle time and (iii) the heat recovery time. It is investigated that performance of coefficient (COP) of this system could be as high as 0.48 while the waste heat source temperature is applicable as low as 55 °C. © 2012.

Comparison and Analysis of Lithium Bromide-water Absorption Chillers Using Plastic Heat Transfer Tubes and Traditional Lithium Bromide-water Absorption Chillers

OpenAIRE

Xue-dong Zhang

2010-01-01

There are extensive applications of lithium bromide-water absorption chillers in industry, but the heat exchangers corrosion and refrigerating capacity loss are very difficult to be solved. In this paper, an experiment was conducted by using plastic heat transfer tubes instead of copper tubes. As an example, for a lithium bromide-water absorption chiller of refrigerating capacity of 35kW, the correlative performance of the lithium bromide-water absorption chiller using pl...

A novel energy-saving method for air-cooled chiller plant by parallel connection

International Nuclear Information System (INIS)

Zhang Xiaosong; Xu Guoying; Chan, K.T.; Yi Xia

2006-01-01

A novel method was put forward for improving the energy efficiency of air-cooled water chiller plant operating on part load conditions. The conventional multiple-chiller plant was proposed to be integrated into one refrigeration cycle, by connecting those separate compressors, condensers and evaporators in parallel, respectively. The integrated multiple-chiller plant uses the electronic expansion valve to control refrigerant flow, achieving variable condensing temperature control. A prototype composed of four reciprocating compressors (including one variable-speed compressor), with total nominal cooling capacity of 120 kW was simulated and experimented. Both the simulative and experimental results indicated that applying this novel energy-saving method, the air-cooled chiller plant could get a significant performance improvement on various part load ratio (PLR) conditions, due to the apparent decrease of condensing temperature and some increase of evaporating temperature. Under the same outdoor temperature of 35 o C, when the PLR decreased from 100% to 50%, the COP increased by about 16.2% in simulation and 9.5% in experiment. Also, the practical refrigeration output ratio of the system was 55% on the condition of 50% PLR

Modelling and adaptive control of small capacity chillers for HVAC applications

International Nuclear Information System (INIS)

Beghi, A.; Cecchinato, Luca

2011-01-01

An adaptive controller for single and uneven tandem scroll compressor, packaged air-cooled water chillers is described. The designed controller allows to substantially increase the energy performance of the system, as well as to achieve excellent regulation performances in process applications. The controller parameters are adapted on the basis of estimates of the plant thermal load, that are computed by using a Kalman filter. An ad hoc approach is used to define a relay control logic, which is based on a numerical optimization procedure. To support controller design, a detailed simulation environment is developed and validated on an experimental facility. Performance of the algorithm is described with both simulation and experimental data. At low part load ratio values the proposed algorithm grants a 0.6-0.7 K improvement in the regulation performance in terms of supply water temperature standard deviation and mean supply water temperature deviation. The unit energy efficiency improvement with respect to supply water temperature control varies from 7.3% to 3.0% while the experimental seasonal energy efficiency rating improvement is 9.1%. - Research highlights: → Design of an advanced control algorithms for small capacity chillers. → Matlab/Simulink simulation environment development and experimental validation. → Development of an adaptive control algorithm for scroll compressor chillers, which allows to increase both control accuracy and energy performance. → New load estimation scheme based on a Kalman filter.

Seismic qualification for water chillers of nuclear power plant

International Nuclear Information System (INIS)

Wang Chunming

2005-01-01

Water chillers are important components of the electric building chilled water system of Nuclear Power Plant. In this article, we describe the seismic qualification methodology. A united method of seismic analysis and experiment testing were applied. Since the seismic classification of the evaporator, condenser and oil separator is 1F, the chillers must satisfy the function criteria. The functional and performance of the control panel were qualified by seismic test. In order to get the seismic time histories of the base of the motor, compressor and control panel, we did time histories analysis for the whole chillers using the seismic acceleration time history of the building floor on which the water chillers was located. Then, these curves were translated into required response spectrum (RRS), which were used by the seismic test of water chillers compressor sets. All passive components, such as evaporator, condenser, oil separator and support, were qualified by seismic stress analysis method. These components were verified to satisfy the standard when they were subjected to the seismic, gravitational, operational pressure and nozzle loads. The Chillers' components were qualified to the specification and the standard. The motor-compressor set and control panel were qualified to the functional and performance criteria. The applied of this methodology qualified the function of the water chillers compressor sets effectively, especially after the aging test. (author)

Targeting Zero Emission Through Siemens Compressor Chiller Packages

Energy Technology Data Exchange (ETDEWEB)

Girbig, Paul

2010-09-15

Ecological as well as economic impacts necessities in District Cooling Technology. Reduction of total primary energy use. Reduction of greenhouse gas emission. Energy efficiency goals worldwide and in chiller equipment. A smart grid to get a reliable energy supply. Use of the sun leads to thermal power plants. Thermal storage technology to compensate differences in load and supply. The high energy demand of the district cooling plants, the variety of load demand, the methods employed in production of refrigeration and the highly sensitive production processes, depend on a reliable and efficient supply of technology.

Screw compressors for applications in liquid chillers and heat pumps; Schraubenverdichter fuer Anwendungen in Fluessigkeitskuehlsaetzen und Waermepumpen

Energy Technology Data Exchange (ETDEWEB)

Grosse-Kracht, Rainer [Bitzer Kuehlmaschinenbau GmbH, Sindelfingen (Germany)

2009-05-15

The demands on compressors for liquid chillers and heat pumps are changing continuously, with energy efficiency becoming ever more of a key focus. Especially certification programs are rating part load conditions higher than full load conditions. Another aspect is the lowering of the condensing temperature in order to achieve an increase in efficiency. Bitzer offers three compressor series optimized for these requirements: The CSH series for air-cooled liquid chillers and heat pumps; the CSW series, developed on the basis of the CSH, for low condensing temperatures occurring in water-cooled systems; and the HS.VS with frequency inverter for high part load efficiencies. (orig.)

Application of heat in postcook meat chillers reduces Listeria.

Science.gov (United States)

Eglezos, Sofroni; Dykes, Gary A

2011-06-01

Electrical air-blowing heaters were used to heat and dry out holding chillers used for postcook commercial processed meats in an attempt to control the presence of Listeria. A baseline study of the prevalence of Listeria in holding chillers in seven facilities was undertaken. Listeria was detected in four of the seven chillers, and swab samples showed Listeria prevalence ranging from 7 (7.8%) of 90 to 6 (20%) of 30, depending on the facility. Two of the facilities with established Listeria contamination (A and E) were chosen for further studies. The heating trials consisted of three individual heating interventions at each of the two facilities, with 2 weeks of postintervention sampling after each treatment. The initial Listeria prevalence in chiller A was 19 (10.6%) of 180, and treatment at 37°C for 36 h reduced prevalence to 3 (1.7%) of 180. The initial Listeria prevalence in chiller E was 7 (7.8%) of 90, and treatment at 50°C for 2 h reduced prevalence to 0 of 90. Both reductions were statistically significant at P prevalence of Listeria in chillers.

Optimizing condenser fan control for air-cooled centrifugal chillers

Energy Technology Data Exchange (ETDEWEB)

Yu, F.W.; Chan, K.T. [Dept. of Building Services Engineering, The Hong Kong Polytechnic Univ., Hung Hom, Hong Kong (China)

2008-07-15

The current design and operation of air-cooled condensers can cause a significant decrease in chiller performance under part load conditions. This paper demonstrates optimal condenser fan control to improve the coefficient of performance (COP) of air-cooled chillers. This control involves identifying the optimum set point of condensing temperature with the optimized power relationships of the compressors and condenser fans and enhancing the airflow and heat transfer area of the condensers. An example application of this control for an air-cooled centrifugal chiller indicated that the COP could increase by 11.4-237.2%, depending on the operating conditions. Such the increase of the COP results in a reduction of up to 14.1 kWh/m{sup 2}, or 27.3% in the annual electricity consumption per unit A/C floor area of chillers, given that the chillers serve an office building requiring an annual cooling energy per unit A/C floor area of 173.3 kWh/m{sup 2}. The simulation results of this study will give HVAC engineers a better understanding of how to optimize the design and operation of air-cooled chillers. (author)

Aging assessment of essential HVAC chillers used in nuclear power plants

International Nuclear Information System (INIS)

Blahnik, D.E.; Klein, R.F.

1993-09-01

The Pacific Northwest Laboratory conducted a Phase I aging assessment of chillers used in the essential safety air-conditioning systems of nuclear power plants. Centrifugal chillers in the 75- to 750-ton refrigeration capacity range are the predominant type used. The chillers used, and air-conditioning systems served, vary in design from plant-to-plant. It is crucial to keep chiller internals very clean and to prevent the leakage of water, air, and other contaminants into the refrigerant containment system. Periodic operation on a weekly or monthly basis is necessary to remove moisture and noncondensable gases that gradually build up inside the chiller. This is especially desirable if a chiller is required to operate only as an emergency standby unit. The primary stressors and aging mechanisms that affect chillers include vibration, excessive temperatures and pressures, thermal cycling, chemical attack, and poor quality cooling water. Aging is accelerated by moisture, non-condensable gases (e.g., air), dirt, and other contamination within the refrigerant containment system, excessive start/stop cycling, and operating below the rated capacity. Aging is also accelerated by corrosion and fouling of the condenser and evaporator tubes. The principal cause of chiller failures is lack of adequate monitoring. Lack of performing scheduled maintenance and human errors also contribute to failures

Evaluation of Aqua-Ammonia Chiller Technologies and Field Site Installation

Energy Technology Data Exchange (ETDEWEB)

Zaltash, Abdolreza [ORNL

2007-09-01

The Naval Facilities Engineering Service Center (NFESC) has sponsored Oak Ridge National Laboratory (ORNL) to review, select, and evaluate advanced, gas-fired, 5-ton, aqua-ammonia, chiller technologies. The selection criteria was that units have COP values of 0.67 or better at Air-conditioning and Refrigeration Institute (ARI) 95 F outdoor rating conditions, an active refrigerant flow control, and a variable-speed condenser fan. These features are expected to allow these units to operate at higher ambient temperatures (up to the maximum operating temperature of 110 F) with minimal degradation in performance. ORNL evaluated three potential manufacturers of advanced, gas-fired, 5-ton, aqua-ammonia chillers-Robur, Ambian, and Cooling Technologies. Unfortunately, Robur did not meet the COP requirements and Cooling Technologies could not deliver a unit to be tested at the U.S. Department of Energy (DOE)-ORNL environmental chamber testing facility for thermally activated heat pumps. This eliminated these two technologies from further consideration, leaving only the Ambian chillers for evaluation. Two Ambian chillers were evaluated at the DOE-ORNL test facility. Overall these chillers operated well over a wide range of ambient conditions with minimal degradation in performance due to several control strategies used such as a variable speed condenser fan, a modulating burner, and active refrigerant flow control. These Ambian pre-commercial units were selected for installation and field testing at three federal facilities. NFESC worked with ORNL to assist with the site selection for installation and evaluation of these chillers. Two sites (ORNL and Naval Surface Warfare Center [NSWC] Corona) had a single chiller unit installed; and at one site (Naval Amphibious Base [NAB] Little Creek), two 5-ton chillers linked together were installed to provide 10 tons of cooling. A chiller link controller developed under this project was evaluated in the field test at Little Creek.

Experimental study on improved two-bed silica gel-water adsorption chiller

Energy Technology Data Exchange (ETDEWEB)

Xia Zaizhong [Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai 200030 (China)], E-mail: xzz@sjtu.edu.cn; Wang Dechang; Zhang Jincui [College of Electromechanical Engineering, Qingdao University, Qingdao 266071 (China)

2008-06-15

A novel silica gel-water adsorption chiller with two chambers has been built in Shanghai Jiao Tong University (SJTU). This chiller combines two single bed systems (basic system) without any vacuum valves. One adsorber, one condenser and one evaporator are housed in the same chamber to constitute one adsorption/desorption unit. In this work, the chiller is developed and improved. The improved chiller is composed of three vacuum chambers: two adsorption/desorption vacuum chambers (the same structure as the former chiller) and one heat pipe working vacuum chamber. The evaporators of these two adsorption/desorption units are combined by a heat pipe. So, no valves are installed in the chilled water sub system and one vacuum valve connects the two adsorption/desorption chambers together to improve its performance. The performance of the chiller is tested. As the results, the refrigerating capacity and the COP of the chiller are, respectively, 8.69 kW and 0.388 for the heat source temperature of 82.5 deg. C, the cooling water temperature of 30.4 deg. C and the chilled water outlet temperature of 11.9 deg. C. For a chilled water outlet temperature of 16.5 deg. C, the COP reaches 0.432, while the refrigerating capacity is near 11 kW. There is an improvement of at least 12% for the COP compared with the former chillers.

Experimental study on improved two-bed silica gel-water adsorption chiller

Energy Technology Data Exchange (ETDEWEB)

Xia, Zaizhong [Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai 200030 (China); Wang, Dechang; Zhang, Jincui [College of Electromechanical Engineering, Qingdao University, Qingdao 266071 (China)

2008-06-15

A novel silica gel-water adsorption chiller with two chambers has been built in Shanghai Jiao Tong University (SJTU). This chiller combines two single bed systems (basic system) without any vacuum valves. One adsorber, one condenser and one evaporator are housed in the same chamber to constitute one adsorption/desorption unit. In this work, the chiller is developed and improved. The improved chiller is composed of three vacuum chambers: two adsorption/desorption vacuum chambers (the same structure as the former chiller) and one heat pipe working vacuum chamber. The evaporators of these two adsorption/desorption units are combined by a heat pipe. So, no valves are installed in the chilled water sub system and one vacuum valve connects the two adsorption/desorption chambers together to improve its performance. The performance of the chiller is tested. As the results, the refrigerating capacity and the COP of the chiller are, respectively, 8.69 kW and 0.388 for the heat source temperature of 82.5 C, the cooling water temperature of 30.4 C and the chilled water outlet temperature of 11.9 C. For a chilled water outlet temperature of 16.5 C, the COP reaches 0.432, while the refrigerating capacity is near 11 kW. There is an improvement of at least 12% for the COP compared with the former chillers. (author)

Performance Analysis of Waste Heat Driven Pressurized Adsorption Chiller

KAUST Repository

LOH, Wai Soong; SAHA, Bidyut Baran; CHAKRABORTY, Anutosh; NG, Kim Choon; CHUN, Won Gee

2010-01-01

This article presents the transient modeling and performance of waste heat driven pressurized adsorption chillers for refrigeration at subzero applications. This innovative adsorption chiller employs pitch-based activated carbon of type Maxsorb III

Absorber performance of a water/lithium-bromide absorption chiller

International Nuclear Information System (INIS)

Xie Guozhen; Sheng Guogang; Bansal, Pradeep Kumar; Li, Guang

2008-01-01

An absorber is one of the most important components of a lithium-bromide absorption chiller (LBAC) as its absorbing characteristics directly influence the performance of the whole chiller. It has been indicated that the absorbing efficiency and cooling capacity could be improved by increasing the solution concentration. In this paper, based on the mechanism of falling film absorption on horizontal tubes, the theoretical models of falling film absorption on horizontal tubes have been established. A series of programs used for computing the theoretical mathematical models, including simulation of LBAC cycle and falling film absorption, have been programmed. The models have been validated reasonably by the experimental data. The results show that the cooling capacity of the LBAC varies in parabola shape of curve with the solution concentration from 52.5% to 58.5%, and that the best coefficient of performance (COP) occurs at concentration of 57%. The investigation proposes the absorbing process of sub-steady thermodynamic equilibrium for the duality solution under increase absorbing pressure

T Plant removal of PWR Chiller Subsystem

International Nuclear Information System (INIS)

Dana, C.M.

1994-01-01

The PWR Pool Chiller System is not longer required for support of the Shippingport Blanket Fuel Assemblies Storage. The Engineering Work Plan will provide the overall coordination of the documentation and physical changes to deactivate the unneeded subsystem. The physical removal of all energy sources for the Chiller equipment will be covered under a one time work plan. The documentation changes will be covered using approved Engineering Change Notices and Procedure Change Authorizations as needed

Experimental research on novel adsorption chiller driven by low grade heat source

International Nuclear Information System (INIS)

Wang, D.C.; Shi, Z.X.; Yang, Q.R.; Tian, X.L.; Zhang, J.C.; Wu, J.Y.

2007-01-01

A novel silica gel-water adsorption chiller is developed. This chiller consists of three vacuum chambers: two adsorption/desorption (or evaporation/condensation) vacuum chambers and one heat pipe working vacuum chamber. In this chiller, only one vacuum valve is installed between the two adsorption/desorption vacuum chambers to improve its performance when it is driven by a low temperature heat source. The operational reliability of the chiller is highly improved because of fewer moving parts. In this work, the performance of the chiller is experimentally tested under a low grade heat source, such as 55-67 o C. The test results show that the performance of this chiller is satisfying when it is driven by a low grade heat source, such as 65 o C, and the cooling capacity (or refrigeration capacity) will reach about 5 kW when the hot water temperature is 65 o C, the cooling water temperature is 30.5 o C and the chilled water inlet temperature is 15.1 o C. The test results confirm that this kind of adsorption chiller can be effectively driven by a low grade heat source

Modelling of a condenser-fan control for an air-cooled centrifugal chiller

International Nuclear Information System (INIS)

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

2007-01-01

There is a lack of detailed experimental and simulation studies on air-cooled centrifugal chillers. This paper investigates how to optimize the control of condenser fans within the chillers to maximize their coefficients of performance (COPs). A thermodynamic model for the chillers was developed and used to analyse the steady-state COP under various load and ambient conditions. An algorithm is introduced to compute the number of staged condenser fans based on settings of the condensing pressure and outdoor temperature. The model was validated using the experimental data and performance data of an existing chiller running under various operating conditions. It is found that the best strategy for switching condenser fans is to vary their rotating speed by the use of a set point of the condensing temperature, which is adjusted in response to the chiller load and condenser air-inlet temperature. The results of this paper provide an important insight into how to increase the COPs of air-cooled chillers

Modelling of a condenser-fan control for an air-cooled centrifugal chiller

Energy Technology Data Exchange (ETDEWEB)

Yu, F.W.; Chan, K.T. [Department of Building Services Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China)

2007-11-15

There is a lack of detailed experimental and simulation studies on air-cooled centrifugal chillers. This paper investigates how to optimize the control of condenser fans within the chillers to maximize their coefficients of performance (COPs). A thermodynamic model for the chillers was developed and used to analyse the steady-state COP under various load and ambient conditions. An algorithm is introduced to compute the number of staged condenser fans based on settings of the condensing pressure and outdoor temperature. The model was validated using the experimental data and performance data of an existing chiller running under various operating conditions. It is found that the best strategy for switching condenser fans is to vary their rotating speed by the use of a set point of the condensing temperature, which is adjusted in response to the chiller load and condenser air-inlet temperature. The results of this paper provide an important insight into how to increase the COPs of air-cooled chillers. (author)

Part load performance of air-cooled centrifugal chillers with variable speed condenser fan control

Energy Technology Data Exchange (ETDEWEB)

Yu, F.W.; Chan, K.T. [Department of Building Services Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China)

2007-11-15

Air-cooled centrifugal chillers are commonly used in commercial buildings but their performance analysis is lacking. This paper investigates the part load performance of the chillers via a thermodynamic model. The model was validated using a wide range of operating data from an existing chiller with specific settings of outdoor temperature and condensing pressure in controlling the condensing temperature. The validated model was developed specifically to ascertain the maximum coefficient of performance of chiller (COP) together with the strategy for optimizing the condensing temperature under various operating conditions. It is found that the highest COP occurs at a part load ratio (PLR) of 0.71-0.84, depending on the outdoor temperature and the control of condensing temperature, rather than at full load. Yet the chillers operating at such part load conditions will cause extra energy used for the early staging of chilled water pumps. To minimize the overall chiller plant energy consumption, it is still preferable to implement chiller sequencing based on the full load condition than on the aforementioned PLRs. The results of this paper present criteria for implementing low-energy strategies for operating air-cooled chillers satisfying a given building cooling load profile. (author)

Constraints of using thermostatic expansion valves to operate air-cooled chillers at lower condensing temperatures

International Nuclear Information System (INIS)

Yu, F.W.; Chan, K.T.; Chu, H.Y.

2006-01-01

Thermostatic expansion valves (TXVs) have long been used in air-cooled chillers to implement head pressure control under which the condensing temperature is kept high at around 50 o C by staging condenser fans as few as possible. This paper considers how TXVs prevent the chillers from operating with an increased COP at lower condensing temperatures when the chiller load or outdoor temperature drops. An analysis on an existing air-cooled reciprocating chiller showed that the range of differential pressures across TXVs restricts the maximum heat rejection airflow required to increase the chiller COP, though the set point of condensing temperature is reduced to 22 o C from a high level of 45 o C. It is possible to use electronic expansion valves to meet the differential pressure requirements for maximum chiller COP. There is a maximum of 28.7% increase in the chiller COP when the heat rejection airflow is able to be maximized in various operating conditions. The results of this paper emphasize criteria for lowering the condensing temperature to enhance the performance of air-cooled chillers

Study on Relative COP Changes with Increasing Heat Input Temperatures of Double Effect Steam Absorption Chillers

Directory of Open Access Journals (Sweden)

Abd Majid Mohd Amin

2016-01-01

Full Text Available Absorption chillers at cogeneration plants generate chilled water using steam supplied by heat recovery steam generators. The chillers are mainly of double effect type. The COP of double effect varies from 0.7 to 1.2 depending on operation and maintenance practices of the chillers. Heat input to the chillers during operations could have impact on the COP of the chillers. This study is on relative COP changes with increasing the heat input temperatures for a steam absorption chiller at a gas fueled cogeneration plant. Reversible COP analysis and zero order model were used for evaluating COP of the chiller for 118 days operation period. Results indicate increasing COP trends for both the reversible COP and zero model COP. Although the zero model COP are within the range of double effect absorption chiller, it is not so for the actual COP. The actual COP is below the range of normal double effect COP. It is recommended that economic replacement analysis to be undertaken to assess the feasibility either to repair or replace the existing absorption chiller.

Experimental investigation of a solar adsorption chiller used for grain depot cooling

International Nuclear Information System (INIS)

Luo, H.L.; Dai, Y.J.; Wang, R.Z.; Wu, J.Y.; Xu, Y.X.; Shen, J.M.

2006-01-01

The solar cooling technology is attractive since cooling load of building is roughly in phase with solar energy availability. In this study, a solar adsorption chiller was built and tested with aim of developing an alternative refrigeration system used for grain cooling storage. This solar adsorption chiller consists of four subsystems, namely, a solar water heating unit with 49.4 m 2 solar collecting area, a silica gel-water adsorption chiller, a cooling tower and a fan coil unit. In order to achieve continuous refrigeration, two adsorption units are operated out-of-phase with mass recovery cycle in the adsorption chiller. Field test results show that, under the climatic conditions of daily solar radiation being about 16-21 MJ/m 2 , this solar adsorption chiller can furnish 14-22 deg. C chilled air with an average cooling output ranging from about 3.2-4.4 kW, its daily solar cooling COP (coefficient of performance) is about 0.1-0.13

Measured performance of a 3 ton LiBr absorption water chiller and its effect on cooling system operation

Science.gov (United States)

Namkoong, D.

1976-01-01

A three ton lithium bromide absorption water chiller was tested for a number of conditions involving hot water input, chilled water, and the cooling water. The primary influences on chiller capacity were the hot water inlet temperature and the cooling water inlet temperature. One combination of these two parameters extended the output to as much as 125% of design capacity, but no combination could lower the capacity to below 60% of design. A cooling system was conceptually designed so that it could provide several modes of operation. Such flexibility is needed for any solar cooling system to be able to accommodate the varying solar energy collection and the varying building demand. It was concluded that a three-ton absorption water chiller with the kind of performance that was measured can be incorporated into a cooling system such as that proposed, to provide efficient cooling over the specified ranges of operating conditions.

Measured performance of a 3-ton LiBr absorption water chiller and its effect on cooling system operation

Science.gov (United States)

Namkoong, D.

1976-01-01

A 3-ton lithium bromide absorption water chiller was tested for a number of conditions involving hot-water input, chilled water, and the cooling water. The primary influences on chiller capacity were the hot water inlet temperature and the cooling water inlet temperature. One combination of these two parameters extended the output to as much as 125% of design capacity, but no combination could lower the capacity to below 60% of design. A cooling system was conceptually designed so that it could provide several modes of operation. Such flexibility is needed for any solar cooling system to be able to accommodate the varying solar energy collection and the varying building demand. It is concluded that a 3-ton absorption water chiller with the kind of performance that was measured can be incorporated into a cooling system such as that proposed, to provide efficient cooling over the specified ranges of operating conditions.

Improved energy performance of air cooled centrifugal chillers with variable chilled water flow

International Nuclear Information System (INIS)

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

2008-01-01

This paper considers how to apply optimum condensing temperature control and variable chilled water flow to increase the coefficient of performance (COP) of air cooled centrifugal chillers. A thermodynamic model for the chillers was developed and validated using a wide range of operating data and specifications. The model considers real process phenomena, including capacity control by the inlet guide vanes of the compressor and an algorithm to determine the number and speed of condenser fans staged based on a set point of condensing temperature. Based on the validated model, it was found that optimizing the control of condensing temperature and varying the evaporator's chilled water flow rate enable the COP to increase by 0.8-191.7%, depending on the load and ambient conditions. A cooling load profile of an office building in a subtropical climate was considered to assess the potential electricity savings resulting from the increased chiller COP and optimum staging of chillers and pumps. There is 16.3-21.0% reduction in the annual electricity consumption of the building's chiller plant. The results of this paper provide useful information on how to implement a low energy chiller plant

Performance Evaluation of a Continuous Operation Adsorption Chiller Powered by Solar Energy Using Silica Gel and Water as the Working Pair

Directory of Open Access Journals (Sweden)

Hassan Zohair Hassan

2014-10-01

Full Text Available In the present study, dynamic analysis and performance evaluation of a solar-powered continuous operation adsorption chiller are introduced. The adsorption chiller uses silica gel and water as the working pair. The developed mathematical model represents the heat and mass transfer within the reactor coupled with the energy balance of the collector plate and the glass cover. Moreover, a non-equilibrium adsorption kinetic model is taken into account by using the linear driving force equation. The variation of solar radiation, wind speed, and atmospheric temperature along a complete cycle are considered for a more realistic simulation. Based on the case studied  and the baseline parameters, the chiller is found to acquire a coefficient of performance of 0.402. The average thermal efficiency of the solar collector is estimated to be 62.96% and the average total efficiency  approaches a value of 50.91%. Other performance parameters obtained are 363.8 W and 1.82 W/kg for the cooling capacity and the specific cooling power of the chiller, respectively. Furthermore, every 1 kg of silica gel inside the adsorption reactor produces a daily chilled water mass of 3 kg at a temperature of 10 ◦C. In addition, the cooling system harnesses 25.35% of the total available solar radiation and converts it to a cooling effect.

Aging assessment of essential HVAC chillers used in nuclear power plants. Phase 1, Volume 1

Energy Technology Data Exchange (ETDEWEB)

Blahnik, D.E.; Klein, R.F. [Pacific Northwest Lab., Richland, WA (United States)

1993-09-01

The Pacific Northwest Laboratory conducted a Phase I aging assessment of chillers used in the essential safety air-conditioning systems of nuclear power plants. Centrifugal chillers in the 75- to 750-ton refrigeration capacity range are the predominant type used. The chillers used, and air-conditioning systems served, vary in design from plant-to-plant. It is crucial to keep chiller internals very clean and to prevent the leakage of water, air, and other contaminants into the refrigerant containment system. Periodic operation on a weekly or monthly basis is necessary to remove moisture and noncondensable gases that gradually build up inside the chiller. This is especially desirable if a chiller is required to operate only as an emergency standby unit. The primary stressors and aging mechanisms that affect chillers include vibration, excessive temperatures and pressures, thermal cycling, chemical attack, and poor quality cooling water. Aging is accelerated by moisture, non-condensable gases (e.g., air), dirt, and other contamination within the refrigerant containment system, excessive start/stop cycling, and operating below the rated capacity. Aging is also accelerated by corrosion and fouling of the condenser and evaporator tubes. The principal cause of chiller failures is lack of adequate monitoring. Lack of performing scheduled maintenance and human errors also contribute to failures.

An experimental and analytical investigation of water chillers of nuclear power plant

International Nuclear Information System (INIS)

Wang Chunming

2005-01-01

Water chillers are important components of the electric building chilled water system of Nuclear Power Plant. In this article, we describe the seismic qualification methodology. A united method of seismic analysis and experiment testing were applied. Since the seismic classification of the evaporator, condenser and oil separator is 1F, the function criteria are necessary to be satisfied. The functional and performance of the control panel were qualified by seismic test. In order to get the seismic time histories of the base of the motor, compressor and control panel, we did time histories analysis for the whole chillers using the seismic acceleration time history of the building floor on which the water chillers was located. Then, these curves were translated into required response spectrum (RRS), which were used by the seismic test of water chillers compressor sets. All passive components, such as evaporator, condenser, oil separator and support, were qualified by seismic stress analysis method. These components were verified to satisfy the standard when they were subjected to the seismic, gravitational, operational pressure and nozzle loads. The Chillers' components were qualified to the specification and the standard. The motor-compressor set and control panel were qualified to the functional and performance criteria. The applied of this methodology adequately qualified the function of the water chillers compressor sets , especially after the aging test. (authors)

Optimal chiller sequencing by branch and bound method for saving energy

International Nuclear Information System (INIS)

Chang, Y.-C.; Lin, F.-A.; Lin, C.H.

2005-01-01

This paper proposes a method for using the branch and bound (B and B) method to solve the optimal chiller sequencing (OCS) problem and to eliminate the deficiencies of conventional methods. The coefficient of performance (COP) of the chiller is adopted as the objective function because it is concave. The Lagrangian method determines the optimal chiller loading (OCL) in each feasible state. The potential performance of the proposed method is examined with reference to an example system. The proposed method consumes much less power than the conventional method and is very appropriate for application in air conditioning systems

Performance of a LiBr-water absorption chiller operating with plate heat exchangers

International Nuclear Information System (INIS)

Vega, M. de; Almendros-Ibanez, J.A.; Ruiz, G.

2006-01-01

This paper studies the performance of a lithium bromide-water absorption chiller operating with plate heat exchangers (PHE). The overall heat transfer coefficients in the desorber, the condenser and the solution heat recoverer are calculated using the correlations provided in the literature for evaporation, condensation and liquid to liquid heat transfer in PHEs. The variable parameters are the external driving temperatures. In the desorber, the inlet temperature of the hot fluid ranges from 75 deg. C to 105 deg. C. In the condenser and the absorber, the inlet temperature of the cooling water goes from 20 deg. C to 40 deg. C. The coefficient of performance (COP) obtained ranges from 0.5 to 0.8 for cooling duties ranging from 2 kW to 12 kW. The chiller response to different hot fluid temperatures and circulated mass flow rates is also presented. The performance and the internal parameters of the chiller at part load are, therefore, calculated. A higher efficiency results when the solution pumped from the absorber to the desorber decreases. The heat transfer analysis of the PHEs is also presented. The overall heat transfer coefficient in the desorber, equal to 790 W/m 2 K at the design conditions, is also analysed at part load. The condenser performance can be represented by a similar relationship found in conventional air cooled condensers

A numerical model for the dynamic simulation of a recirculation single-effect absorption chiller

International Nuclear Information System (INIS)

Zinet, Matthieu; Rulliere, Romuald; Haberschill, Philippe

2012-01-01

Highlights: ► Dynamic simulation of a new recirculation single-effect H 2 O/LiBr absorption chiller is developed. ► The chiller is driven by two heat sources and exclusively cooled by the ambient air. ► Heat and mass transfer in the absorber and the desorber are described according to a detailed physical model. ► Analyse of the dynamic behaviour of the chiller after sudden changes in operation. - Abstract: A dynamic model for the simulation of a new single-effect water/lithium bromide absorption chiller is developed. The chiller is driven by two distinct heat sources, includes a custom integrated falling film evaporator–absorber, uses mixed recirculation and is exclusively cooled by the ambient air. Heat and mass transfer in the evaporator–absorber and in the desorber are described according to a physical model for vapour absorption based on Nusselt’s film theory. The other heat exchangers are handled using a simplified approach based on the NTU-effectiveness method. The model is then used to analyze the chiller response to a step drop of the heat recovery circuit flow rate, and to a sudden reduction of the cooling need in the conditioned space. In the latter case, a basic temperature regulation system is simulated. In both simulations, the performance of the chiller is well represented and consistent with expectations.

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%

Exergy and Exergoenvironmental Analysis of a CCHP System Based on a Parallel Flow Double-Effect Absorption Chiller

Directory of Open Access Journals (Sweden)

Ali Mousafarash

2016-01-01

Full Text Available A combined cooling, heating, and power (CCHP system which produces electricity, heating, and cooling is modeled and analyzed. This system is comprised of a gas turbine, a heat recovery steam generator, and a double-effect absorption chiller. Exergy analysis is conducted to address the magnitude and the location of irreversibilities. In order to enhance understanding, a comprehensive parametric study is performed to see the effect of some major design parameters on the system performance. These design parameters are compressor pressure ratio, gas turbine inlet temperature, gas turbine isentropic efficiency, compressor isentropic efficiency, and temperature of absorption chiller generator inlet. The results show that exergy efficiency of the CCHP system is higher than the power generation system and the cogeneration system. In addition, the results indicate that when waste heat is utilized in the heat recovery steam generator, the greenhouse gasses are reduced when the fixed power output is generated. According to the parametric study results, an increase in compressor pressure ratio shows that the network output first increases and then decreases. Furthermore, an increase in gas turbine inlet temperature increases the system exergy efficiency, decreasing the total exergy destruction rate consequently.

The effects of operation parameter on the performance of a solar-powered adsorption chiller

International Nuclear Information System (INIS)

Luo, Huilong; Wang, Ruzhu; Dai, Yanjun

2010-01-01

A solar-powered adsorption chiller with heat and mass recovery cycle was designed and constructed. It consists of a solar water heating unit, a silica gel-water adsorption chiller, a cooling tower and a fan coil unit. The adsorption chiller includes two identical adsorption units and a second stage evaporator with methanol working fluid. The effects of operation parameter on system performance were tested successfully. Test results indicated that the COP (coefficient of performance) and cooling power of the solar-powered adsorption chiller could be improved greatly by optimizing the key operation parameters, such as solar hot water temperature, heating/cooling time, mass recovery time, and chilled water temperature. Under the climatic conditions of daily solar radiation being about 16-21 MJ/m 2 , this solar-powered adsorption chiller can produce a cooling capacity about 66-90 W per m 2 collector area, its daily solar cooling COP is about 0.1-0.13.

Analysis and parameter identification for characteristic equations of single- and double-effect absorption chillers by means of multivariable regression

DEFF Research Database (Denmark)

Puig Arnavat, Maria; López-Villada, Jesús; Bruno, Joan Carles

2010-01-01

Two approaches to the characteristic equation method have been compared in order to find a simple model that best describes the performance of thermal chillers. After comparing the results obtained using experimental data from a single-effect absorption chiller, we concluded that the adaptation o...... chillers. The characteristic parameters for these chillers are given and can be incorporated as a chiller module in thermal modelling and simulation packages....

Modeling and simulation of chillers with Dymola/Modelica; Modellierung und Simulation von Kaeltemaschinen mit Dymola/Modelica

Energy Technology Data Exchange (ETDEWEB)

Rettich, Daniel [Hochschule Biberach (Germany). Inst. fuer Gebaeude- und Energiesysteme (IGE)

2012-07-01

Within the contribution under consideration, a chiller was modeled and simulated with the program package Dymola / Modelica using the TIL Toolbox. An existing refrigeration technology test bench at the University of Biberach (Federal Republic of Germany) serves as a reference for the chiller illustrated in the simulation. The aim of the simulation is the future use of the models in a hardware-in-the-Loop (HIL) test bench in order to test different controllers with respect to their function and logic under identical framework conditions. Furthermore, the determination of the energy efficiency according to the regulation VDMA 24247 is in the foreground at the test bench as well as within the simulation. Following the final completion of the test bench, the models are validated against the test bench, and the model of the refrigerator will be connected to a detailed space model. Individual models were taken from the TIL toolbox, adapted for the application and parameterized with the design values of the laboratory chiller. Modifications to the TIL models were necessary in order to reflect the dynamic effects of the chiller in detail. For this purpose, investigations on indicators of the various dynamic components were employed. Subsequently to the modeling, each model was tested on the bases of design values and documents of the manufacturer. First simulation studies showed that the simulation in Dymola including the developed models provide plausible results. In the course of the modeling and parameterization of these modified models a component library was developed. Different models for future simulation studies can be extracted.

Performance Investigation of a Solar Heat Driven Adsorption Chiller under Two Different Climatic Conditions

Science.gov (United States)

Choudhury, Biplab; Chatterjee, Pradip Kumar; Habib, Khairul; Saha, Bidyut Baran

2018-06-01

The demand for cooling, especially in the developing economies, is rising at a fast rate. Fast-depleting sources of fossil fuel and environmental concerns necessitate looking for alternative cooling solutions. Solar heat driven adsorption based cooling cycles are environmentally friendly due to their use of natural refrigerants and the thermal compression process. In this paper, a performance simulation study of a basic two-bed solar adsorption chiller has been performed through a transient model for two different climatic locations in India. Effect of operating temperatures and cycle time on the chiller performance has been studied. It is observed that the solar hot water temperature obtained in the composite climate of Delhi (28.65°N, 77.25°E) can run the basic adsorption cooling cycle efficiently throughout the year. Whereas, the monsoon months of July and August in the warm and humid climate of Durgapur (23.48°N, 87.32°E) are unable to supply the required driving heat.

Test Ability of Chiller Post Re-functioning at The Facility of KH-IPSB3

International Nuclear Information System (INIS)

Harahap, Sentot-Alibasya; M-Taufik-Arsyad; Djunaidi

2006-01-01

Chiller water unit (CWU) represent supplier of cool water for the system of ventilation, cooler of purification system irrigate canal (T.C) and pool (depository ponds) ex-fuel at facility of KH-IPSB3. Have been conducted by re-functioning of Chiller unit water by changing system conduct and control from electronic mode to mode of electric-mechanic and parts of damage other. A unit water chiller system have some component / appliance which way of its activity integrated one other, so that re-functioning of partial like in this time where some of component / appliance use old goods and some of using new material hence to get optimum activity at test ability of difficult chiller relative. At operation is old ones expected by optimum activity will be able to reach with an process which in phases and planed. (author)

Cost justification of chiller replacement

International Nuclear Information System (INIS)

Baker, T.J.; Baumer, R.A.

1993-01-01

We often hear of products with paybacks that are too good to be true. Just a few weeks ago,a client received a recommendation from a national service company's local office. In the letter the company recommended that open-quotes due to the age and condition of the boiler ... that the school consider replacing the boiler... The cost for the new boiler can usually be recovered by lower fuel bills in 2 to 3 yearsclose quotes. This was for an installation in Southeast Texas where the boiler is only used 4 to 5 months per year. Analysis show the above claims to be nonsense. A new boiler would cost about $47,000 installed. Current total gas bills for the facility are $15,630 per year. They would have to shutoff the gas to the facility to have a three year payback. In fact, only two-thirds of the gas is used to heat the facility so we have only $10, 000 to write off against the new boiler. How much will the greater efficiency save? A 30% savings due to greater efficiency produces $3,000 per year in gas savings to offset the $47,000 cost, a 16 year payback. And much of the efficiency savings can be realized by adjusting the existing boiler. In another care a client wanted to investigate replacement of a twenty year old chiller plant with more efficient equipment. We investigated the project and determined that the payback would be greater than ten years. They did not operate the equipment during the summer and at less than 50% of capacity the balance of the year

Dynamic Performance Analysis for an Absorption Chiller under Different Working Conditions

Directory of Open Access Journals (Sweden)

Jian Wang

2017-08-01

Full Text Available Due to the merits of energy saving and environmental protection, the absorption chiller (AC has attracted a lot of attention, and previous studies only concentrated on the dynamic response of the AC under a single working condition. However, the working conditions are usually variable, and the dynamic performance under different working conditions is beneficial for the adjustment of AC and the control of the whole system, of which the stabilization can be affected by the AC transient process. Therefore, the steady and dynamic models of a single-effect H2O-LiBr absorption chiller are built up, the thermal inertia and fluid storage are also taken into consideration. And the dynamic performance analyses of the AC are completed under different external parameters. Furthermore, a whole system using AC in a process plant is analyzed. As a conclusion, the time required to reach a new steady-state (relaxation time increases when the step change of the generator inlet temperature becomes large, the cooling water inlet temperature rises, or the evaporator inlet temperature decreases. In addition, the control strategy considering the AC dynamic performance is favorable to the operation of the whole system.

Truck Thermoacoustic Generator and Chiller

Energy Technology Data Exchange (ETDEWEB)

Keolian, Robert

2011-03-31

This Final Report describes the accomplishments of the US Department of Energy (DOE) cooperative agreement project DE-FC26-04NT42113 - Truck Thermoacoustic Generator and Chiller - whose goal is to design, fabricate and test a thermoacoustic piezoelectric generator and chiller system for use on over-the-road heavy-duty-diesel trucks, driven alternatively by the waste heat of the main diesel engine exhaust or by a burner integrated into the thermoacoustic system. The thermoacoustic system would utilize engine exhaust waste heat to generate electricity and cab air conditioning, and would also function as an auxiliary power unit (APU) for idle reduction. The unit was to be tested in Volvo engine performance and endurance test cells and then integrated onto a Class 8 over-the-road heavy-duty-diesel truck for further testing on the road. The project has been a collaboration of The Pennsylvania State University Applied Research Laboratory, Los Alamos National Laboratory, Clean Power Resources Inc., and Volvo Powertrain (Mack Trucks Inc.). Cost share funding was provided by Applied Research Laboratory, and by Clean Power Resources Inc via its grant from Innovation Works - funding that was derived from the Commonwealth of Pennsylvania. Los Alamos received its funding separately through DOE Field Work Proposal 04EE09.

Thermodynamic simulation of condensation heat recovery characteristics of a single stage centrifugal chiller in a hotel

International Nuclear Information System (INIS)

Gong, Guangcai; Chen, Feihu; Su, Huan; Zhou, Jianyong

2012-01-01

Highlights: ► Thermodynamic model of a two-condenser condensation system has been carried out. ► Dynamic simulation method has been presented. ► COP and g of the refrigerating system is better than the single condensation system. ► The optimal parameters for the two-condenser condensation system have been studied. -- Abstract: A thermodynamic simulation study has been carried out for a single stage centrifugal chiller in this paper. The cooling capacity of the chiller unit is about 1750 kW. The chiller unit has been set and tested, and the work refrigerant is R22. A heat exchanger has been set between outlet of the compressor and the condenser for sanitary hot water supplying. Then the chiller unit is a kind of combined system that can provide sanitary hot water supplying and air conditioning simultaneously. A thermodynamic simulation model of the combined system has been established with the system simulation toolbox Simulink. Performance of the components and the combined system of the chiller unit has been studied over a wide range of operating conditions. The potential energy and fuel cost saving associated with the use of the proposed combined system for a typical hotel in south China has been estimated. It is showed that the combined system of the chiller unit is very useful in hotel buildings. And the thermodynamic simulation model of the combined system is significance for the optimization of parameters of the chiller unit such as condensation and evaporation temperature, mass flow of the sanitary hot water and size of hot water storage tank.

A novel approach for optimal chiller loading using particle swarm optimization

Energy Technology Data Exchange (ETDEWEB)

Ardakani, A. Jahanbani; Ardakani, F. Fattahi; Hosseinian, S.H. [Department of Electrical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Hafez Avenue, Tehran 15875-4413 (Iran, Islamic Republic of)

2008-07-01

This study employs two new methods to solve optimal chiller loading (OCL) problem. These methods are continuous genetic algorithm (GA) and particle swarm optimization (PSO). Because of continuous nature of variables in OCL problem, continuous GA and PSO easily overcome deficiencies in other conventional optimization methods. Partial load ratio (PLR) of the chiller is chosen as the variable to be optimized and consumption power of the chiller is considered as fitness function. Both of these methods find the optimal solution while the equality constraint is exactly satisfied. Some of the major advantages of proposed approaches over other conventional methods can be mentioned as fast convergence, escaping from getting into local optima, simple implementation as well as independency of the solution from the problem. Abilities of proposed methods are examined with reference to an example system. To demonstrate these abilities, results are compared with binary genetic algorithm method. The proposed approaches can be perfectly applied to air-conditioning systems. (author)

Thermal analysis and modeling of a swimming pool heating system by utilizing waste energy rejected from a chiller unit of an ice rink

Directory of Open Access Journals (Sweden)

Kuyumcu Muhammed Enes

2017-01-01

Full Text Available This study deals with the thermal analysis and modeling of a swimming pool heating system in which the waste energy rejected from the chiller unit of an ice rink is used as an energy source. The system consists of a swimming pool and an ice rink coupled by a chiller unit. The swimming pool and the ice rink both indoor types and were constructed in city of Gaziantep, Turkey. The thermal energy requirement for each section is determined by thermal analysis of each component of the system. Effects of different design parameters such as ceiling insulation thickness, ceiling emissivity, Carnot efficiency factor and size of the ice rink on the thermal energy requirements and coefficient of performance of the chiller unit are investigated. As a result of analyses of the system, the minimum ice rink area is determined in order to meet annual total heat energy demand of the olympic-sized swimming pool.

Comparative study of air conditioning systems with vapor compression chillers using the concept of green buildings

Directory of Open Access Journals (Sweden)

Gutenberg da Silva Pereira

2015-10-01

Full Text Available This paper sets out to compare two different cooling systems that use vapor compression chillers for air conditioning environments. It was proposed to compare different operations in isolated and combined action operations. These operations are evaluated in the concepts of green buildings. A mathematical model was developed based on the principles of mass and energy conservation and complemented by various functions so as to determine the thermophysical properties and efficiencies of the compressors. The equations of the model were solved by the EES (Engineering Equation Solver program. The model evaluates the influence of the main HVAC operating parameters of the chilled water system when operating under three different configurations. The results showed that the system with a differentiated compression presents a COP equal to that of the system with screw chillers in the range  0-300 RTs, and a COP hat is on average 9% higher in the range 400-800 RTs.

LiCl Dehumidifier LiBr absorption chiller hybrid air conditioning system with energy recovery

Science.gov (United States)

Ko, Suk M.

1980-01-01

This invention relates to a hybrid air conditioning system that combines a solar powered LiCl dehumidifier with a LiBr absorption chiller. The desiccant dehumidifier removes the latent load by absorbing moisture from the air, and the sensible load is removed by the absorption chiller. The desiccant dehumidifier is coupled to a regenerator and the desiccant in the regenerator is heated by solar heated hot water to drive the moisture therefrom before being fed back to the dehumidifier. The heat of vaporization expended in the desiccant regenerator is recovered and used to partially preheat the driving fluid of the absorption chiller, thus substantially improving the overall COP of the hybrid system.

Experimental study of a thermoelectrically-driven liquid chiller in terms of COP and cooling down period

International Nuclear Information System (INIS)

Faraji, Amir Yadollah; Goldsmid, H.J.; Akbarzadeh, Aliakbar

2014-01-01

Highlights: • A COP of 0.8 is achievable for a thermoelectrically-driven water chiller. • With two market available TEC modules with ZT around 0.7 sub-zero temperatures became applicable. • Forced air convection heat exchangers have better COP and CDP compared with natural convection. • A PID controller has several advantages against on–off controller for controlling TEC module. - Abstract: To study COP and other cooling parameters of a thermoelectically-driven liquid chiller, a 430 ml capacity liquid chiller incorporating two commercially available thermoelectric modules as its active components, has been designed, built and assessed. The system can use natural or forced air convection in heat exchangers attached to the thermoelectric module surfaces. The coefficient of performance (COP) and cooling down period (CDP) of the system for different thermoelectric input voltages have been measured. The COP of the thermoelectric chiller was found to be in the range 0.2–1.4 for forced convection and 0.2–1 for natural convection at a cooled liquid temperature of 10 °C and an ambient temperature of 18 °C. For the chiller, heat pumping capacity, minimum achievable water temperature, and temperature difference across the thermoelectric surfaces were investigated for input voltages of 3 V, 5 V, 7 V, 10 V and 12 V. Furthermore, as a basis for reliable and convenient control of the chiller, a proportional integral derivative (PID) controller has been proposed

Testing of Model Water Chiller System with Hidrokarbon as a Primer Refrigeran

Directory of Open Access Journals (Sweden)

Nengah Suarnadwipa

2012-11-01

Full Text Available Now days, there are two issues that give a negative impact on the environment due to the uses of synthetic refrigerant on therefrigeration system and air conditioning system. The first issue was the Ozon Layer Depletion and the second issue was theGlobal Warming. Regarding those condition, it will be investigated the design and examination of performance the use of thesplit type AC system as water chiller system and using hydrocarbon as a primer refrigerant. As a result, in the examination ofthe standard split type AC system using refrigerant R-22, it founded that the cooling rate of 1958 Watt and COP of 5.29.While the examination on the modified split type AC system into water chiller system using hydrocarbon (hycool 22, hasgiven cooling rate of 1832 Watt and COP of 4.19. Finally, it could be councluded that the split type AC system could be usedas water chiller system.

Zero-ODP Refrigerants for Low Tonnage Centrifugal Chiller Systems

National Research Council Canada - National Science Library

Gui, Fulin

1996-01-01

..., HFC-236cb, HFC-236fa, HFC-245cb, and HFC-254cb, for centrifugal chiller applications. We took into account the thermodynamic properties of the refrigerant and aerodynamic properties of the impeller compression process to this evaluation...

Evolution strategy based optimal chiller loading for saving energy

International Nuclear Information System (INIS)

Chang, Y.-C.; Lee, C.-Y.; Chen, C.-R.; Chou, C.-J.; Chen, W.-H.; Chen, W.-H.

2009-01-01

This study employs evolution strategy (ES) to solve optimal chiller loading (OCL) problem. ES overcomes the flaw that Lagrangian method is not adaptable for solving OCL as the power consumption models or the kW-PLR (partial load ratio) curves include convex functions and concave functions simultaneously. The complicated process of evolution by the genetic algorithm (GA) method for solving OCL can also be simplified by the ES method. This study uses the PLR of chiller as the variable to be solved for the decoupled air conditioning system. After analysis and comparison of the case study, it has been concluded that this method not only solves the problems of Lagrangian method and GA method, but also produces results with high accuracy within a rapid timeframe. It can be perfectly applied to the operation of air conditioning systems

Performance Analysis of Waste Heat Driven Pressurized Adsorption Chiller

KAUST Repository

LOH, Wai Soong

2010-01-01

This article presents the transient modeling and performance of waste heat driven pressurized adsorption chillers for refrigeration at subzero applications. This innovative adsorption chiller employs pitch-based activated carbon of type Maxsorb III (adsorbent) with refrigerant R134a as the adsorbent-adsorbate pair. It consists of an evaporator, a condenser and two adsorber/desorber beds, and it utilizes a low-grade heat source to power the batch-operated cycle. The ranges of heat source temperatures are between 55 to 90°C whilst the cooling water temperature needed to reject heat is at 30°C. A parametric analysis is presented in the study where the effects of inlet temperature, adsorption/desorption cycle time and switching time on the system performance are reported in terms of cooling capacity and coefficient of performance. © 2010 by JSME.

A comprehensive, multi-objective optimization of solar-powered absorption chiller systems for air-conditioning applications

International Nuclear Information System (INIS)

Shirazi, Ali; Taylor, Robert A.; Morrison, Graham L.; White, Stephen D.

2017-01-01

Highlights: • Multi-objective optimization of solar single/multi-effect absorption chillers was conducted. • Primary energy consumption and total annual cost were considered as the objectives. • Optimized designs of the alternative configurations were compared. • A detailed sensitivity analysis of the Pareto optimal solutions was investigated. - Abstract: Solar heating and cooling (SHC) systems are currently under rapid development and deployment due to their potential to reduce the use of fossil fuel resources and to alleviate greenhouse gas emissions in the building sector – a sector which is responsible for ∼40% of the world energy use. Absorption chiller technology (traditionally powered by natural gas in large buildings), can easily be retrofitted to run on solar energy. However, numerous non-intuitive design choices must be analyzed to achieve the best techno-economic performance of these systems. To date, there has been little research into the optimal configurations among the long list of potential solar-driven absorption chiller systems. To address this lack of knowledge, this paper presents a systematic simulation-based, multi-objective optimization of three common, commercially available lithium bromide-water absorption chillers – single-effect, double-effect and triple-effect – powered by evacuated tube collectors (ETCs), evacuated flat plate collectors (EFPCs), and concentrating parabolic trough collectors (PTCs), respectively. To the best of authors’ knowledge, this is the first study of its kind that compares the optimized designs of the most promising configurations of solar-assisted absorption chillers against a common set of energy, economic, and environmental metrics from a holistic perspective. A simulation model of these three configurations is developed using TRNSYS 17. A combined energy, economic, and environmental analysis of the modeled systems is conducted to calculate the primary energy use as well as the levelized total

Modelling and testing the performance of a commercial ammonia/water absorption chiller using Aspen-Plus platform

International Nuclear Information System (INIS)

Mansouri, Rami; Boukholda, Ismail; Bourouis, Mahmoud; Bellagi, Ahmed

2015-01-01

A steady-state simulation model of a commercial 3-ton ammonia/water absorption chiller is developed and validated using the flow-sheeting software Aspen-Plus. First an appropriate thermodynamic property model for the ammonia/water fluid mixture is selected. To this purpose nine methods from the software library are pre-selected and tested, but none of the methods predicts the VLE (vapour–liquid equilibrium) with sufficient accuracy. The interaction parameters of these models are then determined by fitting the equations of state (EOS) to VLE data. It is finally found that the Boston–Mathias modified Peng–Robinson EOS with fitted parameters predicts most accurately the VLE for the temperature and pressure ranges encountered in commercial chillers. A simulation model of the machine is then developed. The simulation results are found to be in good agreement with data from literature at a cooling air temperature of 35 ºC. The heat transfer characteristics (UA) of the various heat exchangers of the machine are then determined and the model modified to make it accept these (UA) as input parameters. The comparison of the simulation predictions at cooling air temperatures of 26.7 and 38 ºC with the bibliographical data showed good concordance. The proposed model could be very useful for the analysis and performance prediction of the commercial absorption chiller. - Highlights: • A commercial NH 3 /H 2 O absorption chiller is simulated using the software Aspen-Plus. • Peng-Robinson-Boston-Mathias equation of state is used to predict VLE of NH 3 /H 2 O fluid mixture. • A steady-state model describing the chiller operation is developed. • The model predicts the internal operating conditions and COP of the chiller.

Development and experimental testing of a hybrid Stirling engine-adsorption chiller auxiliary power unit for heavy trucks

International Nuclear Information System (INIS)

Flannery, Barry; Lattin, Robert; Finckh, Oliver; Berresheim, Harald; Monaghan, Rory F.D.

2017-01-01

Highlights: • Free-piston Stirling engine for truck APU. • Waste heat driven adsorption chiller for cab air conditioning. • Reduced-order model comparing proposed system to existing technology. • Experimental test data from prototype test rig. - Abstract: This paper identifies the key technical requirements for a heavy truck auxiliary power unit (APU) and explores a potential alternative technology for use in a next-generation APU which could eliminate key problems related to emissions, noise and maintenance experienced today by conventional diesel engine-vapour compression APUs. The potential performance of a novel hybrid Stirling engine-adsorption chiller concept is investigated and benchmarked against the incumbent technology using a reduced-order model based on experimental data. Experimental results from a Stirling-adsorption system (SAS) prototype test rig are also presented which highlight system integration dynamics and overall performance. The adsorption chiller achieved an average COP of 0.42 ± 0.06 and 2.3 ± 0.1 kW_t of cooling capacity at the baseline test condition. The prototype SAS test rig demonstrates that there appear to be no major technology barriers remaining that would prevent adoption of the SAS concept in a next-generation APU. Such a system could offer a reduction of exhaust emissions, greenhouse gases (GHG), ozone-depleting substances, noise, low maintenance and the potential for fuel flexibility and higher reliability. Preliminary modelling results indicate that the proposed system could offer superior overall electrical and cooling efficiencies compared to incumbent APUs and demonstrate a payback period of 4.6 years.

Low temperature absorption chiller - Report from a project in the programs Climate 21 and 'More efficient refrigeration and heat pump systems. Final report; Laagtemperaturdriven absorptionskylmaskin - Rapport oever ett projekt inom programmen Klimat 21 och Effektivare Kyl- och Vaermepumpssystem. Slutrapport

Energy Technology Data Exchange (ETDEWEB)

Fredrik Setterwall [Fredrik Setterwall Konsult AB, Sollentuna (Sweden); Andersson, Mikael [AB Berglunds Rostfria, Boden (Sweden); Glebov, Dmitrey; Martin, Viktoria [Royal Inst. of Technology, Stockholm (Sweden). Dept. of Chemical Technology

2005-06-01

An absorption chiller with a 1.15 MW cooling effect has been designed in a collaboration project comprising university, industry and end-user. This chiller is designed to run on district heating (70-90 deg C), and its layout and function differs from conventional absorption chillers as outlined below. The chiller's heat transfer surfaces may be installed horizontally or vertically, resulting in flexibility in system design. In a conventional absorption chiller, these surfaces are always horizontally aligned. The high-pressure and low-pressure parts of the chiller may be placed independently of each other. In a conventional chiller, the high-pressure part must always be placed on top of the low-pressure part. To enable the flexibility in design and system layout, this chiller is equipped with four internal pumps instead of only two in conventional design. The increased number of pumps leads to an increase of the installed electrical power for internal pumps. The electrical power for the internal pumps is however only a small fraction of the totally installed electrical power. The main part is utilized for pumping of cooling water and coolant. This low temperature driven, single-effect chiller has a high coefficient of performance (COP). The 'first generation machine' installed at Chalmers University of Technology has a COP equal to 0.75 at full load. Through the control strategy used, the chiller can maintain a high COP even at part load. Because of the high COP, the electricity consumption of the cooling water pump is kept low. To lower the size of the absorber and generator, the chiller is equipped with extra plate heat exchangers to cool the strong solution before the absorber, and preheat the weak solution before the generator. To increase the heat transfer rate, a new additive (2-methyl-penthanol) has been tested. As compared to the conventional heat transfer additive (2-ethyl-hexanol), the heat transfer enhancement was 20% higher with the new

ANALISA KINERJA REFRIGERASI WATER CHILLER PADA PT GMF AEROASIA

Directory of Open Access Journals (Sweden)

Ali Nugroho

2015-02-01

Full Text Available Pengkondisian udara merupakan salah satu hal yang paling penting dalam suatu industri atau gedung, khusunya pada suatu gedung perkantoran. Karena dengan sistem pengkondisian udara yang baik akan menghasilkan uadara segar yang akan memperoleh kenyamanan bagi manusia, mesin, maupun lingkungan yang berada disekitar. Karena dengan tingkat kenyamanan yang baik akan meningkatkan kinerja dari mesin yang digunakan. Ketidak sesuaian pola pengoperasian sistem refrigerai pada saat perancangan dengan keadaan aktual merupakan salah satu penyebab tingginya konsumsi energi listrik, oleh karena itu perlu dilakukan analisa performansi pada sistem refrigerasi di sana agar dapat diketahui apakah energi yang digunakan sudah efisien. Untuk menganalisia kinerja mesin water chiller ini dilakukan dengan pengamatan langsung terhadap panel control water chiller selama empat jam sekali secara continue selama lima hari. Dan dilakukan perhitungan dari data tersebut untuk mengetahui nilai effisiensinya yaitu: COP, laju aliran refrigerant, kalor yang diserap evaporator dan kondensor, kerja yang dilakukan kompresor, daya yang dibutuhkan kompresor, dan laju aliran volume air cooling water. Kinerja chiller yang baik mempunyai efisiensi yang dapat dipengaruhi antara lain oleh: temperatur air keluar evaporator, dan temperaturr air masuk kondensor. Hasil penelitian hari sabtu diperoleh nilai COP = 8,04, Pref = 0,44 kW/TR, TR = 112,961 TR, dan laju massa refrigerant evaporator = 2,415 kg/s, kerja yang dilakukan kompresor = 49,395kW, laju aliran volume cooling tower = 94,613 m3/jam, dan laju aliran volume make-up water = 0,567 m3/jam. Maka di simpulkan semakin rendah temperatur refrigerant di kondensor maka akan semakin bagus juga nilai COP yang dihasilkan(KW/TR semakin rendah, karena kerja kompresor yang dibutuhkan akan lebih rendah.

The Development and Full-Scale Experimental Validation of an Optimal Water Treatment Solution in Improving Chiller Performances

Directory of Open Access Journals (Sweden)

Chen-Yu Chiang

2016-06-01

Full Text Available An optimal solution, in combining physical and chemical water treatment methods, has been developed. This method uses a high voltage capacitance based (HVCB electrodes, coupled with biocides to form a sustainable solution in improving chiller plant performances. In this study, the industrial full-scale tests, instead of laboratory tests, have been conducted on chiller plants at the size of 5000 RT to 10,000 RT cooling capacities under commercial operation for more than two years. The experimental results indicated that the condenser approach temperatures can be maintained at below 1 °C for over two years. It has been validated that the coefficient of performance (COP of a chiller can be improved by over 5% by implementing this solution. Every 1 °C reduction in condenser approach temperature can yield approximately 3% increase on chiller COP, which warrants its future application potential in the HVAC industry, where Ta can degrade by 1 °C every three to six months. The solution developed in this study could also reduce chemical dosages and conserve makeup water substantially and is more environment friendly.

Variable-Speed Screw Chiller, Sidney Yates Building, Washington, DC

Energy Technology Data Exchange (ETDEWEB)

Ostrouchov, George [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Adams, Mark B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Howett, Daniel H. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2017-07-01

This report captures the findings from an evaluation ORNL performed on a new chiller technology as part of GSA's Proving Ground Program. Note: Appendices B&C were removed from this report while the author looks for a way to insert them without consuming over 200MB of file size.

Trigeneration System Based on Municipal Waste Gasification, Fuel Cell and an Absorption Chiller

DEFF Research Database (Denmark)

Katsaros, Giannis; Nguyen, Tuong-Van; Rokni, Masoud

2016-01-01

of a specific building is also investigated and the system can fully meet the electricity and cooling demands, whereas the heat needs can be satisfied only up to 55%. Moreover, assuming 20 years of operation, the payback period is 4.3 years and the net present value exceeds 5 MEUR.......The present work focuses on the design of a novel tri-generation system based on municipal solid wastes gasification, solid oxide fuel cell and an ammonia-water absorption chiller. Trigeneration systems can be implemented in buildings such as hospitals, where there is a continuous and large demand...

Experimental investigation of a small-scale thermally driven pressurized adsorption chiller

KAUST Repository

Loh, Waisoong; Ismail, Azhar Bin; Ng, Kim Choon; Chun, Wongee

2015-01-01

This paper describes the successful operation of an adsorption cycle in a miniaturized adsorption chiller (AD). The experiments show that the bench-scale pressurized adsorption chiller (PAC) has been successfully designed, commissioned, and tested. Experimental results at various heat fl uxes, half-cycle operation time intervals, and a cooling load of up to 24 W are also presented. A COP ranging from 0.05 to 0.15 is achieved depending on the parameters of the experimental conditions. Most importantly, the cooling performance of the PAC is achieved at a low encasement temperature that is below ambient. Besides having a high cooling density, the PAC has almost no major moving parts except for the fan of the condenser and it permits quiet operation as compared to other active coolers.

Design and Implementation of Closed-loop PI Control Strategies in Real-time MATLAB Simulation Environment for Nonlinear and Linear ARMAX Models of HVAC Centrifugal Chiller Control Systems

Directory of Open Access Journals (Sweden)

Nicolae Tudoroiu

2018-04-01

Full Text Available The objective of this paper is to investigate three different approaches of modeling, design and discrete-time implementation of PI closed-loop control strategies in SIMULINK simulation environment, applied to a centrifugal chiller system. Centrifugal chillers are widely used in large building HVAC systems. The system consists of an evaporator, a condenser, a centrifugal compressor and an expansion valve. The overall system is an interconnection of two main control loops, namely the chilled water temperature inside the evaporator, and the refrigerant liquid level control in condenser. The centrifugal chiller dynamics model in a discrete-time state-space representation is of high complexity in terms of dimension and encountered nonlinearities. For simulation purpose the centrifugal chiller model is simplified by using different approaches, especially the development of linear polynomials ARMAX and ARX models. The aim to build linear ARMAX models for centrifugal chiller is to simplify considerable the control design strategies that are investigated in this research paper. The novelty of this research is a new controller design approach, more precisely an improved version of proportional – integral control, the so called Proportional-Integral-Plus control for systems with time delay, based on linear ARMAX models. It is conceived within the context of non-minimum state space control system that “seems to be the natural description of a discrete-time transfer function, since its dimension is dictated by the complete structure of the model”. The effectiveness of this new controller design, its implementation simplicity, convergence speed and robustness are proved in the last section of the paper.

Efficiency analysis of a cogeneration and district energy system

International Nuclear Information System (INIS)

Rosen, Marc A.; Le, Minh N.; Dincer, Ibrahim

2005-01-01

This paper presents an efficiency analysis, accounting for both energy and exergy considerations, of a design for a cogeneration-based district energy system. A case study is considered for the city of Edmonton, Canada, by the utility Edmonton Power. The original concept using central electric chillers, as well as two variations (one considering single-effect and the other double-effect absorption chillers) are examined. The energy- and exergy-based results differ markedly (e.g., overall energy efficiencies are shown to vary for the three configurations considered from 83% to 94%, and exergy efficiencies from 28% to 29%, respectively). For the overall processes, as well as individual subprocesses and selected combinations of subprocesses, the exergy efficiencies are generally found to be more meaningful and indicative of system behaviour than the energy efficiencies

A Tunable Bimetallic MOF-74 for Adsorption Chiller Applications: A Tunable Bimetallic MOF-74 for Adsorption Chiller Applications

Energy Technology Data Exchange (ETDEWEB)

Liu, Jian [Pacific Northwest National Laboratory, 99352 Richland WA USA; Zheng, Jian [Pacific Northwest National Laboratory, 99352 Richland WA USA; Barpaga, Dushyant [Pacific Northwest National Laboratory, 99352 Richland WA USA; Sabale, Sandip [Pacific Northwest National Laboratory, 99352 Richland WA USA; P.G. Department of Chemistry, Jaysingpur College, 416101 Jaysingpur Maharashtra India; Arey, Bruce [Environmental Molecular Sciences Laboratory (EMSL), Pacific Northwest National Laboratory, 99352 Richland WA USA; Derewinski, Miroslaw A. [Pacific Northwest National Laboratory, 99352 Richland WA USA; McGrail, B. Peter [Pacific Northwest National Laboratory, 99352 Richland WA USA; Motkuri, Radha Kishan [Pacific Northwest National Laboratory, 99352 Richland WA USA

2018-02-12

A mixed metal strategy, in which two different metal nodes coexist in one MOF framework, was examined using MOF-74. The Ni salt precursor for the MOF-74(Ni) analogue was partially replaced during synthesis with relatively inexpensive Zn salt. These bimetallic MOFs were developed and examined for water sorption for potential use in adsorption cooling/chiller applications. Varying concentration ratios of Ni:Zn in MOF-74 achieved using this mixed metal strategy were shown to provide unique impacts on H2O uptake while significantly mitigating the costs of synthesis

Real-time performance assessment and adaptive control for a water chiller unit in an HVAC system

Science.gov (United States)

Bai, Jianbo; Li, Yang; Chen, Jianhao

2018-02-01

The paper proposes an adaptive control method for a water chiller unit in a HVAC system. Based on the minimum variance evaluation, the adaptive control method was used to realize better control of the water chiller unit. To verify the performance of the adaptive control method, the proposed method was compared with an a conventional PID controller, the simulation results showed that adaptive control method had superior control performance to that of the conventional PID controller.

Feasibility study on the application of a heat-pipe type adsorption chiller

Energy Technology Data Exchange (ETDEWEB)

Ahn, Sang Hyeok; Chung, Jae Dong [Dept. of Mechanical Engineering, Sejong University, Seoul (Korea, Republic of); Kwon, Oh Kyung [Energy System R and D Group, Korea Institute of Industrial Technology, Cheonan (Korea, Republic of)

2017-01-15

A parametric study on a heat-pipe type adsorption chiller with SWS-1L (mesoporous silica gel impregnated with CaCl{sub 2}) and water pair was conducted using a numerical method in this research. A heat pipe that is in direct contact with the adsorbent is applied to the adsorption chiller to improve the heat transfer capacity of the adsorption bed. A feasibility study was performed on the heat-pipe type adsorption bed with a single layer. The Coefficient of performance (COP) and the Specific cooling power (SCP) were 0.231 and 844.8 W/kg, respectively. These values are lower than the system performance values of the existing fin-tube type adsorption bed. However, when the number of bed layers was increased to seven, the COP and SCP of the heat-pipe type adsorption bed were 0.520 and 752.4 W/kg, respectively. These values are 5.25 % and 39.8 % higher than the COP and SCP, respectively, of the fin-tube type adsorption bed. These findings indicate that the heat-pipe type adsorption bed can potentially address the disadvantage caused by the system size of the adsorption chiller. A parametric study was also conducted for six design parameters, namely, number of layers, heat pipe pitch, heat pipe radius, fin width, fin spacing, and hot water temperature.

Feasibility study on the application of a heat-pipe type adsorption chiller

International Nuclear Information System (INIS)

Ahn, Sang Hyeok; Chung, Jae Dong; Kwon, Oh Kyung

2017-01-01

A parametric study on a heat-pipe type adsorption chiller with SWS-1L (mesoporous silica gel impregnated with CaCl_2) and water pair was conducted using a numerical method in this research. A heat pipe that is in direct contact with the adsorbent is applied to the adsorption chiller to improve the heat transfer capacity of the adsorption bed. A feasibility study was performed on the heat-pipe type adsorption bed with a single layer. The Coefficient of performance (COP) and the Specific cooling power (SCP) were 0.231 and 844.8 W/kg, respectively. These values are lower than the system performance values of the existing fin-tube type adsorption bed. However, when the number of bed layers was increased to seven, the COP and SCP of the heat-pipe type adsorption bed were 0.520 and 752.4 W/kg, respectively. These values are 5.25 % and 39.8 % higher than the COP and SCP, respectively, of the fin-tube type adsorption bed. These findings indicate that the heat-pipe type adsorption bed can potentially address the disadvantage caused by the system size of the adsorption chiller. A parametric study was also conducted for six design parameters, namely, number of layers, heat pipe pitch, heat pipe radius, fin width, fin spacing, and hot water temperature

Using the adsorption chillers for waste heat utilisation from the CCS installation

Science.gov (United States)

Sztekler, Karol; Kalawa, Wojciech; Nowak, Wojciech; Stefański, Sebastian; Krzywański, Jarosław; Grabowska, Karolina

2018-06-01

Worldwide tendencies in the scope of environmental protection demonstrate the requirement for the limited carbon dioxide emission, that influences on the development of greenhouse effect. As a result of coal as a basic fuel used in the professional power industry, this industry sector is the greatest CO2 polluter and it means that works on the reduction of carbon dioxide in such industry are completely justified. In the IPSEpro programming environment, a reference block model for a conventional coal power station was elaborated, including the CO2 separation unit basing on the adsorption methods with the CO2 preparation installation to liquid state. Simulation researches were conducted with means of numeric techniques, that enabled the system analysis for the CO2 separation unit with the CO2 preparation system to the liquid state, as well as analysis was made for the use of chiller systems, basing on the adsorption technology for waste heat use originating from the compression of CO2 in a cascade system, as well as for potential opportunities for further exploitation of the produced chilled water in the CCS cycle. We analysed in these papers the opportunities for chiller systems application, based on the adsorption chillers in the CCS installation used for the reduction of CO2 emission in the coal power station and its influence on the operation of a power station cycle.

The sun also can cold. In the summer, the adsorption chillers utilizes the capacity of solar thermal energy; Die Sonne kann auch kalt. Adsorptionskaeltemaschine lastet im Sommer die Solarthermie besser aus

Energy Technology Data Exchange (ETDEWEB)

Weiss, Andre [SorTec AG, Halle an der Saale (Germany)

2013-06-15

A combination of solar thermal systems with adsorption chillers from SorTech (Speyer, Federal Republic of Germany) enables an environmentally friendly and efficient recovery of coldness for the solar cooling of buildings by means of excess heat energy.

Design and performance prediction of a new generation adsorption chiller using composite adsorbent

International Nuclear Information System (INIS)

Gong, L.X.; Wang, R.Z.; Xia, Z.Z.; Chen, C.J.

2011-01-01

Research highlights: → Composite adsorbent 'employing lithium chloride in silica gel' and water as working pair. → A new type adsorbent bed is used to accommodate the composite adsorbent. → A dynamic model of the adsorption chiller is built. → The coefficient of performance (COP) and the cooling capacity will be improved. -- Abstract: This paper presents a novel adsorption chiller using composite adsorbent 'employing lithium chloride in silica gel' as adsorbent and water as adsorbate. A new type adsorbent bed is used to accommodate the composite adsorbent. The mass recovery between two adsorbent beds usually results in the adsorbate unbalance. So a novel auto water makeup unite is used to solve the problem. A dynamic model of the adsorption chiller is built based on the adsorption isotherms to predict the performance. The simulation result shows that the coefficient of performance (COP) and the cooling capacity will increase by using this new composite adsorbent. When the temperatures of hot water inlet, cooling water inlet, and chilled water inlet are 363, 303 and 293 K, COP will be 0.43, and the cooling capacity will be 5.295 kW. Also operation strategy is optimized. Different temperatures of hot water inlet, cooling water inlet and chilling water inlet will result in different COP and cooling capacity.

Corrosion behavior of selected materials in lithium bromide solution for the application absorption chillers; Korrosionsverhalten ausgewaehlter Werkstoffe in Lithiumbromid-Loesung fuer den Anwendungsfall Absorptionskaeltemaschinen

Energy Technology Data Exchange (ETDEWEB)

Brandt, B. [ZAE Bayern, Garching (Germany)

2004-07-01

Absorption chillers on the basis of lithium bromide-water are interesting systems for efficient and energy-saving supply of coldness. The heating energy for the propulsion of the chiller could result ideally from renewable energies, e.g. solar energy, or waste heating energy from industry. The chiller can work as a multiple-stage process for increasing the energy efficiency. For the three-stage-plants, in the generator temperatures of up to 200-220 C are necessary. The factors high temperature, high halogenide concentration (lithium bromide) and the presence of water vapour lead to a very high corrosive exposure of the materials. In that reason the task of the present report was the consideration of commercial materials and inhibitors concerning their suitability for the application in triple-effect-chillers. The measurements were carried out under identical conditions, but in unmoved solution and excluding the contact with air. The result of the investigations showed that stainless steel has been identified as a promising material for this application. Furthermore we have found out that the type of the inhibitor and the interaction of different phases have a strong influence on the corrosion processes. (Abstract Copyright [2004], Wiley Periodicals, Inc.) [German] Absorptionskaeltemaschinen auf der Basis von Lithiumbromid-Wasser stellen eine interessante Moeglichkeit zur effizienten und energiesparenden Versorgung mit Kaelte dar. Die zum Antrieb erforderliche Waermeenergie kann idealerweise aus regenerativen Energien, wie z.B. Solarwaerme, oder Abwaerme aus der Industrie bereitgestellt werden. Um die Energieeffizienz zu steigern, koennen die Prozesse mehrstufig betrieben werden. Bei den dreistufigen, sogenannten Triple-Effekt-Anlagen, sind im Generator Temperaturen bis zu etwa 200-220 C erforderlich. Die Faktoren hohe Temperatur, hohe Halogenidkonzentration (Lithiumbromid) und die Anwesenheit von Wasserdampf fuehren zu einer besonders starken korrosiven

Capillary Tube and Thermostatic Expansion Valve Comparative Analysis in Water Chiller Air Conditioning

Science.gov (United States)

Wijaya Sunu, Putu; Made Rasta, I.; Anakottapary, Daud Simon; Made Suarta, I.; Cipta Santosa, I. D. M.

2018-01-01

The aims of this study to compares the performance characteristics of a water chiller air conditioning simulation equipped with thermostatic expansion valve (TEV) with those of a capillary tube. Water chiller system filled with the same charge of refrigerant. Comparative analyses were performed based on coefficient of performance (COP) and performance parameter of the refrigeration system, carried out at medium cooling load level with the ambient temperature of 29-31°C, constant compressor speed and fixed chilled water volume flowrate at 15 lpm. It was shown that the TEV system showed better energy consumption compared to that of capillary tube. From the coefficient of performance perspective, the thermostatic expansion valve system showed higher COP (± 21.4%) compared to that of capillary tube system.

Development of design program for small-sized gas absorption chiller/heaters

Energy Technology Data Exchange (ETDEWEB)

Yoon, J.I.; Kwon, O.K.; Moon, C.K. [Pukyong National University, Pusan (Korea); Yang, Y.M.; Kim, H.Y. [R and D Center, Korea Gas Corporation, Ansan (Korea)

1999-10-01

Analysis of basic data is performed for development of small size water-cooled household absorption chiller/heater using non CFC refrigerant, analytic simulation program of air cooling performance is developed that system has 1.5-10RT of air cooling performance, we perform cycle analysis and numerical simulation. We develope a performance analysis of simulation program to perform a basic design for 1.5-10RT apparatus of small size system of development model in gas driven double effect absorption chiller/heater. The system working condition and operation limit condition is decided from the existing data which is analyzed and the conference with KOGAS. After the basic input variable and regular condition is established for heat cycle analysis, the simulation algorithm is set up and performance simulation program is coded according to the organized algorithm. The basic design of optimum system is completed from parametric study using developed simulation program and establishing the design variable range of developing object model. 20 refs., 30 figs., 9 tabs.

Thermodynamic feasibility of harvesting data center waste heat to drive an absorption chiller

International Nuclear Information System (INIS)

Haywood, Anna; Sherbeck, Jon; Phelan, Patrick; Varsamopoulos, Georgios; Gupta, Sandeep K.S.

2012-01-01

Highlights: ► We propose an alternative data center cooling architecture that is heat driven. ► Our primary source of thermal energy is the heat dissipated by the CPUs. ► Supplementary external heat sources such as solar thermal are included as well. ► We develop a comprehensive model that leads to a potentially realizable value of less than one. - Abstract: More than half the energy to run a data center can be consumed by vapor-compression equipment that cools the center. To reduce consumption and recycle otherwise wasted thermal energy, this paper proposes an alternative cooling architecture that is heat driven and leads to a more efficient data center in terms of power usage effectiveness (PUE). The primary thermal source is waste heat produced by CPUs on each server blade. The main challenge is capturing enough of this high-temperature heat to energize an absorption unit. The goal is to capture a high fraction of dissipated thermal power by using a heat capture scheme with water as the heat transfer fluid. To determine if the CPU temperature range and amount of heat are sufficient for chiller operation, we use server software, validation thermocouples, and chip specifications. We compare these results to required values from a simulator tool specific to our chiller model. One challenge is to simultaneously cool the data center and generate enough exergy to drive the cooling process, regardless of the thermal output of the data center equipment. We can address this by adding phase change latent heat storage to consistently deliver the required heat flow and, if necessary, a solar heat source. Even with zero solar contribution, the results show that the number of CPUs we have is sufficient and our PUE indicates a very efficient data center. Adding solar contribution, the steady-state model proposed leads to a potentially realizable PUE value of less than one.

Analysis of chiller units capacity for different heat loads considering variation of ambient air and cooling water temperature

International Nuclear Information System (INIS)

Coman, Aurelia Camelia; Tenescu, Mircea

2010-01-01

The paper purpose is to analyze the chiller units capacity to determine whether they can cope with high air and cooling water temperatures during summer time to remove heat loads imposed from Heating, Ventilation and Air Conditioning (HVAC) units in a CANDU 6 Nuclear Power Plant. The starting point is calculation of the overall heat transfer coefficient at the evaporator and condenser. They are used in heat balance equations of heat exchangers. A mathematical model was developed that simulates the refrigeration cycle to assess the response of chilled water system and its performance at different heat loads. In this analysis there were calculated values for inlet/outlet chilled water temperature and the refrigerant cycle thermodynamic parameters (condenser and evaporator pressure/temperature, refrigerant mass flowrate, refrigerant quality at the evaporator, refrigerant vapour superheated temperature at the compressor outlet, refrigerant subcooled temperature at the condenser outlet). To find the adequate functioning parameters of the installation, the MathCAD 13 software was used in all cases analyzed. The behaviour of the chiller units was investigated by examining the variation of three basic parameters, namely: - cooling water (river water) temperature; - air temperature; - heat load. The simultaneous variation of these three independent parameters allows to identify the actual chillers unit operating point (including chiller trip). (authors)

Simulation of adsorber tube diameter's effect on new design silica gel-water adsorption chiller

Science.gov (United States)

Nasruddin, Taufan, A.; Manga, A.; Budiman, D.

2017-03-01

A new design of silica gel-water adsorption chiller is proposed. The design configuration is composed of two sorption chambers with compact fin tube heat exchangers as adsorber, condenser, and evaporator. Heat and mass recovery were adopted in order to increase the cooling capacity. Numerical modelling and calculation were used to show the performance of the chiller with different adsorber tube diameter. Under typical condition for hot water inlet/cooling water inlet/chilled water outlet temperatures are 90/30/7°C, respectively, the simulation results showed the best average value of COP, SCP, and cooling power are 0.19, 15.88 W/kg and 279.89 W using 3/8 inch tube.

Controladores fuzzy adaptativos para la optimización de un sistema chiller

Directory of Open Access Journals (Sweden)

Moreno G. Francisco. E.

2011-01-01

Full Text Available The chiller systems are vapor compression cycles used in industrial and residential applications, operated a classical control and inadequate under energy consumption point of view. The experimental work, development in the Energy and Thermal System Laboratory of Federal University of Uberlandia (UFU, investigates some advantages of the use of variable speed compressor and electronic expansion valves focusing on energy consumption reduction and increase of the coefficient of performance, (COP of these chillers systems. In these conditions, a proposed model experimentally based on experimental planning techniques, applying tools of answer surfaces. This model allows the estimative of the dynamic behavior of the compressor frequency to contribute in the control mesh applying adaptative fuzzy strategies, showing a good performance on the system, searching a minimum degree of superheating in the order of the 7°C and reaching on the bests COP zones.

A systematic parametric study and feasibility assessment of solar-assisted single-effect, double-effect, and triple-effect absorption chillers for heating and cooling applications

International Nuclear Information System (INIS)

Shirazi, Ali; Taylor, Robert A.; White, Stephen D.; Morrison, Graham L.

2016-01-01

Highlights: • TRNSYS simulations of SHC single/multi-effect absorption chillers were conducted. • A detailed parametric study was conducted to find the optimal size of the tank. • The effect of tank heat loss on the performance of the configurations was analyzed. • The effect of beam and diffuse radiation on the solar field size was investigated. • Energy performance and economics of each plant were analyzed in various climates. - Abstract: The present work investigates the feasibility of solar heating and cooling (SHC) absorption systems based on combining three types of LiBr–H_2O absorption chillers (single-, double-, and triple-effect) with common solar thermal collectors available on the market. A single-effect chiller is coupled with evacuated tube collectors (ETCs) – SHC1. A double-effect chiller is integrated with parabolic trough collectors (PTCs), linear Fresnel micro-concentrating collectors (MCTs) and evacuated flat plate collectors (EFPCs) respectively – SHC2, SHC3, and SHC4. PTCs are employed to provide high-temperature heat to a triple-effect absorption chiller (SHC5). Although triple-effect chillers have been around for a while, this paper represents the first system-level analysis of these chillers coupled with high-temperature solar concentrating collectors for air-conditioning applications. A simulation model for each configuration is developed in a transient system simulation environment (TRNSYS 17). Furthermore, a unique, comprehensive perspective is given by investigating the impact of characteristic solar beam radiation to global radiation ratios on the techno-economic performance of the proposed SHC plants for a wide variety of climatic regions worldwide. The results of parametric study suggest that a storage volume of around 70 L/m"2 is a good choice for SHC1, while 40–50 L/m"2 storage capacity is sufficient for the other configurations (SHC2 to SHC5). The simulation results reveal that when the fraction of direct normal

Hybrid solar receiver as a source of high-temperature medium for an absorption chiller supply

Directory of Open Access Journals (Sweden)

Przenzak Estera

2016-01-01

Full Text Available This article discusses the problems related with the cold production, i.e. energy efficiency of the process. The idea of solar cooling systems has been presented as the solution of the problem of big electricity demand. The paper discusses the principle of the operation of absorption chillers. Disadvantages and advantages of the solar cooling systems were discussed. The installation for manufacturing high-temperature heat based on solar collectors and concentrator of solar radiation constructed in AGH in Cracow has been presented. This installation is a first stage of projected, complete solar cooling system. The special attention is paid to the dedicated solar high-temperature heat receiver as a most important element of the system. The achieved values of temperature, power and efficiency depending on the working medium flow has been presented and discussed. The intensity of solar radiation during the measurements has been taken into account. Two versions of heat receiver were investigated: non-insulated and insulated with mineral wool. The obtained efficiency of the heat receiver (less than 30% is not satisfactory but possibility of improvements exist.

Variation and design criterion of heat load ratio of generator for air cooled lithium bromide–water double effect absorption chiller

International Nuclear Information System (INIS)

Li, Zeyu; Liu, Liming; Liu, Jinping

2016-01-01

Highlights: • Design criterion of heat load ratio of generator is vital to system performance. • Heat load ratio of generator changes with working condition. • Change of heat load ratio of generator for four systems was obtained and compared. • Design criterion of heat load ratio of generator was presented. - Abstract: The heat load ratio of generator (HLRG) is a special system parameter because it is not fixed at the design value but changes with the working condition. For the air cooled chiller, the deviation from the design working condition occurs easily due to the variation of the surrounding temperature. The system is likely to suffer from crystallization when the working condition is different from the designed one if the HLRG is designed improperly. Consequently, the design criterion of HLRG based on a broad range of working condition is essential and urgent to the development of air cooled lithium bromide–water double effect absorption chiller. This paper mainly deals with the variation of HLRG with the working condition as well as corresponding design criterion. Four types of double effect chillers named series, pre-parallel, rear parallel and reverse parallel flow system were considered. The parametric model was developed by the introduction of a new thermodynamic relationship of generator. The change of HLRG for different types of chillers with the working condition was analyzed and compared. The corresponding design criterion of HLRG was presented. This paper is helpful for further improvement of the performance and reliability of air cooled lithium bromide–water double effect absorption chiller.

Evaluation of trigeneration system using microturbine, ammonia-water absorption chiller, and a heat recovery boiler

Energy Technology Data Exchange (ETDEWEB)

Preter, Felipe C.; Rocha, Marcelo S.; Simoes-Moreira, Jose Roberto [SISEA - Alternative Energy Systems Lab. Dept. of Mechanical Engineering. University of Sao Paulo (EP/USP), SP (Brazil)], e-mails: felipe.preter@poli.usp.br, msrocha@poli.usp.br, jrsimoes@usp.br; Andreos, Ronaldo [COMGAS - Companhia de Gas de Sao Paulo, SP (Brazil)], e-mail: randreos@comgas.com.br

2010-07-01

In this work, a CCHP or tri generation system has been projected, mounted, and tested in laboratory, combining a microturbine for power generation, a heat recovery boiler for hot water production, and an ammonia water absorption chiller for chilled water production. The project was motivated by the large practical applications of this kind of energy recovery system in commerce, and industry, and, in general, more than 85% of the energy source is used as power, hot water, and cold water. In the first part, the trigeneration system theoretical model is detailed, and in the second part, experimental results are presented for different operation conditions. (author)

Development of the Hybrid Operation Method of a Multi-Geothermal Heat Pump System and Absorption Chiller-Heater

Directory of Open Access Journals (Sweden)

Young-Ju Jung

2015-08-01

Full Text Available Considerable efforts have been made to reduce the energy consumption of buildings due to the energy crisis, and, the Korean government has supported the use of renewable energy through various grants. Among the possible renewable energy sources, geothermal energy can be used regardless of the outside weather. Therefore, energy consumption can be reduced considerably in summer and winter. Despite the increasing use of renewable energy, the use of renewables has not been operating appropriately. Therefore, this study examined some of the problems of the operation of renewable energy and some possible improvements. The aim of the study is to evaluate a building containing an actual installed multi-geothermal heat pump (Multi-GHP system, in terms of the energy efficiency. In addition, this study evaluated the present control system and the method of complex operation regarding existing heat sources systems and GHP systems through a simulation. The results can be regarded as the result of a hybrid operation method for the improvement of an existing operation. Therefore, the Multi-GHP system energy use of a hybrid operation condition of the Multi-GHP systems and the absorption (ABS chiller-heater system was reduced compared to the operation condition of the Multi-GHP system, and the total energy consumption of the heat source equipment was reduced. The proposed operation plan was evaluated after applying the system to a building. These results showed that the efficient operation of a Multi-GHP hybrid operation method is possible. As a result, the GHP energy use of Multi-GHP systems and the ABS chiller-heater system was reduced by 30% compared to existing operation and the total energy consumption of heat source equipment was reduced by 78%.

Transient modeling of an air-cooled chiller with economized compressor. Part II: Application to control design

International Nuclear Information System (INIS)

Zhang Weijiang; Ding Shufu; Zhang Chunlu

2009-01-01

Based on the transient modeling developed in the previous paper, the control design of the air-cooled chiller is studied. The main electronic expansion valve (EXV) controls the suction superheat, the compressor controls the leaving water temperature and the sub EXV regulates the injection superheat. Since the system reliability is sensitive to the control of the suction superheat, it is the focus in this paper. Dynamic simulation cases are built to compare two control algorithms, PID and fuzzy logic. The case studies show that the fuzzy controller has higher reliability and performance. Both the two controllers are fully tested and tuned on a chiller test facility and the experiments indicate that the fuzzy controller works better as well.

Development of an Innovative 2.5 kW Water-Silica Gel Adsorption Chiller

Energy Technology Data Exchange (ETDEWEB)

Bakker, E.J.; De Boer, R.; Smeding, S.F.; Sijpheer, N.C.; Van der Pal, M.

2013-10-15

Besides (better) utilization of available solar heat or waste heat, and thereby reduction of fossil fuel consumption, sorption cooling offers several other advantages compared to conventional compression cooling. Such as reduction of summer peaks in the electricity grid, use of natural refrigerants, and low noise and maintenance. Sorption cooling in itself is not a new development. However, the development of small scale sorption chillers (2-20 kW) is new. This development allows sorption cooling to enter the markets for individual homes, small collective systems and small commercial applications. A second trend is gradual reduction of the driving temperatures of the sorption cycles allowing more solar and waste heat to be used. This article describes the design and performance of a new, innovative 2.5 kW adsorption chiller, developed by ECN. This system was built and tests have been performed in a laboratory and in one of ECN's full-scale research houses.

Performance Evaluation of a Continuous Operation Adsorption Chiller Powered by Solar Energy Using Silica Gel and Water as the Working Pair

OpenAIRE

Hassan, Hassan

2014-01-01

In the present study, dynamic analysis and performance evaluation of a solar-powered continuous operation adsorption chiller are introduced. The adsorption chiller uses silica gel and water as the working pair. The developed mathematical model represents the heat and mass transfer within the reactor coupled with the energy balance of the collector plate and the glass cover. Moreover, a non-equilibrium adsorption kinetic model is taken into account by using the linear driving force equation. T...

Two 175 ton geothermal chiller heat pumps for leed platinum building technology demonstration project. Operation data, data collection and marketing

Energy Technology Data Exchange (ETDEWEB)

Kolo, Daniel [Johnson Controls, Inc., Glendale, WI (United States)

2016-08-15

The activities funded by this grant helped educate and inform approximately six thousand individuals who participated in guided tours of the geothermal chiller plant at Johnson Controls Corporate Headquarters in Glendale, Wisconsin over the three year term of the project. In addition to those who took the formal tour, thousands more were exposed to hands-on learning at the self-service video kiosks located in the headquarters building and augmented reality tablet app that allowed for self-guided tours. The tours, video, and app focused on the advantages of geothermal heat pump chillers, including energy savings and environmental impact. The overall tour and collateral also demonstrated the practical application of this technology and how it can be designed into a system that includes many other sustainable technologies without sacrificing comfort or health of building occupants Among tour participants were nearly 1,000 individuals, representing 130 organizations identified as potential purchasers of geothermal heat pump chillers. In addition to these commercial clients, tours were well attended by engineering, facilities, and business trade groups. This has also been a popular tour for groups from Universities around the Midwest and K-12 schools from Wisconsin and Northern Illinois A sequence of operations was put into place to control the chillers and they have been tuned and maintained to optimize the benefit from the geothermal water loop. Data on incoming and outgoing water temperature and flow from the geothermal field was logged and sent to DOE monthly during the grant period to demonstrate energy savings.

SAPO-34 coated adsorbent heat exchanger for adsorption chillers

International Nuclear Information System (INIS)

Freni, Angelo; Bonaccorsi, Lucio; Calabrese, Luigi; Caprì, Angela; Frazzica, Andrea; Sapienza, Alessio

2015-01-01

In this work, adsorbent coatings on aluminum surfaces were prepared by dip-coating method starting from a water suspension of SAPO-34 zeolite and a silane-based binder. Silane-zeolite coatings morphology and surface coverage grade were evaluated by scanning electron microscopy. Adhesive and mechanical properties were evaluated by peel, pull-off, impact and micro-hardness tests, confirming the good interaction between metal substrate, binder and zeolite. Adsorption equilibrium and kinetics of water vapour adsorption on the adsorbent coating were studied in the range T = 30–150 °C and pH 2 O = 11 mbar using a CAHN 2000 thermo-balance. It was found that, in the investigated conditions, the organic binder doesn't affect the water adsorption capacity and adsorption kinetics of the original SAPO-34 zeolite. Subsequently, the zeolite coating was applied on a finned flat-tubes aluminum heat exchanger realizing a full-scale AdHEx with an uniform adsorbent coating 0.1 mm thick and a metal/adsorbent mass ratio = 6. The cooling capacity of the realized coated AdHEx was measured by a lab-scale adsorption chiller under realistic operating conditions for air conditioning applications. The coated AdHEx produced up to 675 W/kg ads specific cooling power with a cycle time of 5 min. Adsorption stability of the coated adsorber subjected to 600 sorption cycles was successfully verified. - Highlights: • Adsorbent coatings on aluminum surfaces were prepared by dip-coating method. • Silane-zeolite coatings morphology, and mechanical properties were studied. • The zeolite coating was applied on a finned flat-tubes aluminum heat exchanger. • The coated AdHEx was tested in a lab scale adsorption chiller

Thermal analysis and modeling of a swimming pool heating system by utilizing waste energy rejected from a chiller unit of an ice rink

OpenAIRE

Kuyumcu Muhammed Enes; Yumrutaş Recep

2017-01-01

This study deals with the thermal analysis and modeling of a swimming pool heating system in which the waste energy rejected from the chiller unit of an ice rink is used as an energy source. The system consists of a swimming pool and an ice rink coupled by a chiller unit. The swimming pool and the ice rink both indoor types and were constructed in city of Gaziantep, Turkey. The thermal energy requirement for each section is determined by thermal analysis of each component of the system. Effec...

Thermodynamic and economic studies of two new high efficient power-cooling cogeneration systems based on Kalina and absorption refrigeration cycles

International Nuclear Information System (INIS)

Rashidi, Jouan; Ifaei, Pouya; Esfahani, Iman Janghorban; Ataei, Abtin; Yoo, Chang Kyoo

2016-01-01

Highlights: • Proposing two new power and cooling cogeneration systems based on absorption chillers and Kalina cycles. • Model-based comparison through thermodynamic and economic standpoints. • Investigating sensitivity of system performance and costs to the key parameters. • Reducing total annual costs of the base system up to 8% by cogeneration. • Increasing thermal efficiency up to 4.9% despite of cooling generation. - Abstract: Two new power and cooling cogeneration systems based on Kalina cycle (KC) and absorption refrigeration cycle (AC) are proposed and studied from thermodynamic and economic viewpoints. The first proposed system, Kalina power-cooling cycle (KPCC), combines the refrigerant loop of the water-ammonia absorption chiller, consisting of an evaporator and two throttling valves with the KC. A portion of the KC mass flow enters the evaporator to generate cooling after being condensed in the KPCC system. KPCC is a flexible system adapting power and cooling cogeneration to the demand. The second proposed system, Kalina lithium bromide absorption chiller cycle (KLACC), consists of the KC and a single effect lithium bromide-water absorption chiller (AC_L_i_B_r_-_w_a_t_e_r). The KC subsystem discharges heat to the AC_L_i_B_r_-_w_a_t_e_r desorber before condensing in the condenser. The performance and economic aspects of both proposed systems are analyzed and compared with the stand alone KC. A parametric analysis is conducted to evaluate the sensitivity of efficiencies and the generated power and cooling quantities to the key operating variables. The results showed that, thermal efficiency and total annual costs decreased by 5.6% and 8% for KPCC system but increased 4.9% and 58% for KLACC system, respectively. Since the power-cooling efficiency of KLACC is 42% higher than KPCC it can be applied where the aim is cooling generation without considering economic aspects.

Performance of a LiBr water absorption chiller operating with plate heat exchangers

OpenAIRE

Vega Blázquez, Mercedes de; Almendros Ibáñez, José Antonio; Ruiz, G.

2006-01-01

This paper studies the performance of a lithium bromide water absorption chiller operating with plate heat exchangers (PHE). The overall heat transfer coefficients in the desorber, the condenser and the solution heat recoverer are calculated using the correlations provided in the literature for evaporation, condensation and liquid to liquid heat transfer in PHEs. The variable parameters are the external driving temperatures. In the desorber, the inlet temperature of the hot fluid ranges from ...

Performance optimization of solar driven small-cooled absorption–diffusion chiller working with light hydrocarbons

Energy Technology Data Exchange (ETDEWEB)

Sayadi, Zouhour [U.R. Thermique et Thermodynamique des Procédés Industriels, Ecole Nationale d’Ingénieurs de Monastir (ENIM), Av. Ibn Jazzar, 5060 Monastir (Tunisia); Ben Thameur, Nizar, E-mail: nizarbenthameur@yahoo.fr [U.R. Thermique et Thermodynamique des Procédés Industriels, Ecole Nationale d’Ingénieurs de Monastir (ENIM), Av. Ibn Jazzar, 5060 Monastir (Tunisia); Bourouis, Mahmoud [Mechanical Engineering Department, Universitat Rovira i Virgili, 43007 Tarragona (Spain); Bellagi, Ahmed [U.R. Thermique et Thermodynamique des Procédés Industriels, Ecole Nationale d’Ingénieurs de Monastir (ENIM), Av. Ibn Jazzar, 5060 Monastir (Tunisia)

2013-10-15

Highlights: • 1 kW{sub cooling} diffusion/absorption machine with light hydrocarbons as working fluids. • Hysys optimization to choose the optimal mixture for a better machine performance. • Cooling loads for a small bed-room (16 m{sup 2}) have been estimated into TRNSYS. • Economic assessment to choose the best combination of solar equipments. • Energy savings, CO{sub 2} avoided and equivalent gasoil and Diesel saved energy. - Abstract: We present in this paper a HYSYS (Aspen One) model and simulation results for 1 kW capacity water-cooled absorption/diffusion machine using different binary mixtures of light hydrocarbons as working fluids (C{sub 3}/n-C{sub 6}, C{sub 3}/c-C{sub 6}, C{sub 3}/c-C{sub 5}, propylene/c-C{sub 5}, propylene/i-C{sub 4}, propylene/i-C{sub 5}) in combination with helium as inert gas. The driving heat is supposed to be provided by an evacuated solar collector field. TRNSYS is used to address the solar aspects of the simulations. For the optimal chiller the driving heat temperature was found to be 121 °C for an evaporator exit temperature of 0 °C. The cooling water flow rate circulating between chiller and cooling tower is 140 l/h. Bubble pump and generator are heated by pressurized water from an insulated tank (70 l/m{sup 2}) maintained at a maximum temperature of 126 °C – with make-up heat when needed – and storing solar heat at an estimated 4.2 kW power. The solar energy cover only 40% for the energy supplied to drive the chiller. It’s found that the necessary collector surface area is about 6 m{sup 2} with annually total costs of 1.60 €/kW h with 20 years lifetime period for the installation. The avoided CO{sub 2} emissions are estimated at 1396 kg. The equivalent saved energy is 521 l of diesel or 604 l of gasoline.

Performance optimization of solar driven small-cooled absorption–diffusion chiller working with light hydrocarbons

International Nuclear Information System (INIS)

Sayadi, Zouhour; Ben Thameur, Nizar; Bourouis, Mahmoud; Bellagi, Ahmed

2013-01-01

Highlights: • 1 kW cooling diffusion/absorption machine with light hydrocarbons as working fluids. • Hysys optimization to choose the optimal mixture for a better machine performance. • Cooling loads for a small bed-room (16 m 2 ) have been estimated into TRNSYS. • Economic assessment to choose the best combination of solar equipments. • Energy savings, CO 2 avoided and equivalent gasoil and Diesel saved energy. - Abstract: We present in this paper a HYSYS (Aspen One) model and simulation results for 1 kW capacity water-cooled absorption/diffusion machine using different binary mixtures of light hydrocarbons as working fluids (C 3 /n-C 6 , C 3 /c-C 6 , C 3 /c-C 5 , propylene/c-C 5 , propylene/i-C 4 , propylene/i-C 5 ) in combination with helium as inert gas. The driving heat is supposed to be provided by an evacuated solar collector field. TRNSYS is used to address the solar aspects of the simulations. For the optimal chiller the driving heat temperature was found to be 121 °C for an evaporator exit temperature of 0 °C. The cooling water flow rate circulating between chiller and cooling tower is 140 l/h. Bubble pump and generator are heated by pressurized water from an insulated tank (70 l/m 2 ) maintained at a maximum temperature of 126 °C – with make-up heat when needed – and storing solar heat at an estimated 4.2 kW power. The solar energy cover only 40% for the energy supplied to drive the chiller. It’s found that the necessary collector surface area is about 6 m 2 with annually total costs of 1.60 €/kW h with 20 years lifetime period for the installation. The avoided CO 2 emissions are estimated at 1396 kg. The equivalent saved energy is 521 l of diesel or 604 l of gasoline

Modeling and simulation of a 100 kWe HT-PEMFC subsystem integrated with an absorption chiller subsystem

DEFF Research Database (Denmark)

Arsalis, Alexandros

2012-01-01

A 100 kWe liquid-cooled HT-PEMFC subsystem is integrated with an absorption chiller subsystem to provide electricity and cooling. The system is designed, modeled and simulated to investigate the potential of this technology for future novel energy system applications. Liquid-cooling can provide...

Engineering Task Plan for Tank 241-C-106 contingency chiller definitive design

International Nuclear Information System (INIS)

Rensink, G.E.; Kriskovich, J.R.

1995-01-01

This document identifies the scope, cost, schedule and responsible organizations for completing a design of a contingency ventilation inlet air cooling system for Tank 241-C-106. The air cooling system, described in Rensink (1995), consists of a chiller, cooling coils, and supporting equipment that, when installed will be capable of assuring that the waste temperatures in Tank 241-C-106 are maintained within acceptable limits for safe storage. The effort described herein is scheduled for completion by May 31, 1995 to support Performance Based Incentive (PBI) Milestone SI-2x

Brain temperature profiles during epidural cooling with the ChillerPad in a monkey model of traumatic brain injury.

Science.gov (United States)

King, Christopher; Robinson, Timothy; Dixon, C Edward; Rao, Gutti R; Larnard, Donald; Nemoto, C Edwin M

2010-10-01

Therapeutic hypothermia remains a promising treatment for patients with severe traumatic brain injury (TBI). Multiple animal studies have suggested that hypothermia is neuroprotective after TBI, but clinical trials have been inconclusive. Systemic hypothermia, the method used in almost all major clinical trials, is limited by the time to target temperature, the depth of hypothermia, and complications, problems that may be solved by selective brain cooling. We evaluated the effects on brain temperature of a cooling device called the ChillerPad,™ which is applied to the dura in a non-human primate TBI model using controlled cortical impact (CCI). The cortical surface was rapidly cooled to approximately 15°C and maintained at that level for 24 h, followed by rewarming over about 10 h. Brain temperatures fell to 34-35°C at a depth of 15 mm at the cortical gray/white matter interface, and to 28-32°C at 10 mm deep. Intracranial pressure was mildly elevated (8-12 mm Hg) after cooling and rewarming, likely due to TBI. Other physiological variables were unchanged. Cooling was rapidly diminished at points distant from the cooling pad. The ChillerPad may be useful for highly localized cooling of the brain in circumstances in which a craniotomy is clinically indicated. However, because of the delay required by the craniotomy, other methods that are more readily available for inducing hypothermia may be used as a bridge between the time of injury to placement of the ChillerPad.

Solar heating and cooling system with absorption chiller and low temperature latent heat storage: Energetic performance and operational experience

Energy Technology Data Exchange (ETDEWEB)

Helm, M.; Keil, C.; Hiebler, S.; Mehling, H.; Schweigler, C. [Bavarian Center for Applied Energy Research (ZAE Bayern) (Germany)

2009-06-15

Absorption cooling systems based on water/lithium bromide (LiBr) solution typically require an open wet cooling tower to transfer the reject heat to the ambient. Yet, water consumption, the need for water make-up and cleaning, formation of fog, and the risk of Legionella bacteria growth are hindering factors for the implementation of small solar cooling systems. The application of a latent heat storage supporting the heat rejection of the absorption chiller in conjunction with a dry cooling system allows eliminating the wet cooling tower. By that means heat rejection of the chiller is shifted to periods with lower ambient temperatures, i.e. night time or off-peak hours. The system concept and the hydraulic scheme together with an analysis of the energetic performance of the system are presented, followed by a report on the operation of a first pilot installation. (author)

On-site study of HCFC-22 substitution for HFC non-azeotropic blends (R417A, R422D) on a water chiller of a centralized HVAC system

Energy Technology Data Exchange (ETDEWEB)

Torrella, E.; Larumbe, J.A. [Polytechnic University of Valencia, Dep. of Applied Thermodynamics, Camino de Vera 14, E-46022 Valencia (Spain); Cabello, R.; Sanchez, D.; Llopis, R. [Jaume I University, Dep. of Mechanical Engineering and Construction, Campus de Riu Sec s/n, E-12071 Castellon (Spain)

2010-09-15

The European Regulation no 2037/2000 has banned manufacturing HCFC refrigerants from January 1st 2010, although its use is allowed up to 2015 if the fluids come from a recycling process. This situation creates the need for developing new working fluids to replace the HCFC in the refrigeration plants now in operation. Among all the HCFCs the R22 is the most widely used in a wide range of applications, especially in air conditioning. This work presents an on-site experimental study of the R22 replacement by two possible substitutes, the HFC-417A and the HFC-422D, in a water chiller in which the energy performance was evaluated. This chiller is part of the centralized HVAC system of a lecture room building at the Jaume I University of Castellon, Spain. This communication compares and analyses main operation parameters of the chiller when operating with each refrigerant in real conditions. (author)

Preventive maintenance basis: Volume 19 -- HVAC -- chillers and compressors. Final report

International Nuclear Information System (INIS)

Worledge, D.; Hinchcliffe, G.

1997-12-01

US nuclear power plants are implementing preventive maintenance (PM) tasks with little documented basis beyond fundamental vendor information to support the tasks or their intervals. The Preventive Maintenance Basis project provides utilities with the technical basis for PM tasks and task intervals associated with 40 specific components such as valves, electric motors, pumps, and HVAC equipment. This document provides a program of preventive maintenance tasks suitable for application to HVAC -- Chillers and Compressors. The PM tasks that are recommended provide a cost-effective way to intercept the causes and mechanisms that lead to degradation and failure. They can be used in conjunction with material from other sources, to develop a complete PM program or to improve an existing program

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

Demonstration of an on-site PAFC cogeneration system with waste heat utilization by a new gas absorption chiller

Energy Technology Data Exchange (ETDEWEB)

Urata, Tatsuo [Tokyo Gas Company, LTD, Tokyo (Japan)

1996-12-31

Analysis and cost reduction of fuel cells is being promoted to achieve commercial on-site phosphoric acid fuel cells (on-site FC). However, for such cells to be effectively utilized, a cogeneration system designed to use the heat generated must be developed at low cost. Room heating and hot-water supply are the most simple and efficient uses of the waste heat of fuel cells. However, due to the short room-heating period of about 4 months in most areas in Japan, the sites having demand for waste heat of fuel cells throughout the year will be limited to hotels and hospitals Tokyo Gas has therefore been developing an on-site FC and the technology to utilize tile waste heat of fuel cells for room cooling by means of an absorption refrigerator. The paper describes the results of fuel cell cogeneration tests conducted on a double effect gas absorption chiller heater with auxiliary waste heat recovery (WGAR) that Tokyo Gas developed in its Energy Technology Research Laboratory.

Appropriate heat load ratio of generator for different types of air cooled lithium bromide–water double effect absorption chiller

International Nuclear Information System (INIS)

Li, Zeyu; Liu, Jinping

2015-01-01

Highlights: • Effect of heat load ratio of generator on the performance was analyzed. • The performance is sensitive to heat load ratio of generator. • The appropriate heat load ratio of generator for four systems was obtained. • The change of appropriate heat load ratio of generator for four systems was studied. - Abstract: The lower coefficient of performance and higher risk of crystallization in the higher surrounding temperature is the primary disadvantage of air cooled lithium bromide–water double effect absorption chiller. Since the coefficient of performance and risk of crystallization strongly depend on the heat load ratio of generator, the appropriate heat load ratio of generator can improve the performance as the surrounding temperature is higher. The paper mainly deals with the appropriate heat load ratio of generator of air cooled lithium bromide–water double effect absorption chiller. Four type systems named series, pre-parallel, rear parallel and reverse parallel flow configuration were considered. The corresponding parametric model was developed to analyze the comprehensive effect of heat load ratio of generator on the coefficient of performance and risk of crystallization. It was found that the coefficient of performance goes up linearly with the decrease of heat load ratio of generator. Simultaneously, the risk of crystallization also rises slowly at first but increases fast finally. Consequently, the appropriate heat load ratio of generator for the series and pre-parallel flow type systems is suggested to be 0.02 greater than the minimum heat load ratio of generator and that for the rear parallel and reverse parallel flow chillers should be 0.01 higher than the minimum heat load ratio of generator. Besides, the changes of minimum heat load ratio of generator for different type systems with the working condition were analyzed and compared. It was found that the minimum heat load ratio of generator goes up with the increase of

Scope-oriented thermoeconomic analysis of energy systems. Part I: Looking for a non-postulated cost accounting for the dissipative devices of a vapour compression chiller. Is it feasible?

Energy Technology Data Exchange (ETDEWEB)

Piacentino, Antonio; Cardona, Fabio [DREAM - Department of Energy and Environmental Researches, University of Palermo, Viale delle Scienze, 90128 Palermo (Italy)

2010-03-15

The authors of the main thermoeconomic methodologies developed in the last two decades have recently focused their efforts on the analysis of dissipative devices, i.e. those components whose productive purpose is neither intuitive nor easy to define. Coherent and unanimously accepted cost structures have been identified for dissipative components, while ambiguities still exist as concerns the cost allocation principles to be adopted. Being this aspect evidently cost-influencing, accurate analyses focused on the subjectivity of results are needed. This paper is structured in two parts. In the Part I an in-depth study of some critical issues arising from the thermoeconomic analysis of a 1.5 MW{sub c} industrial chiller is presented. The attention is focused on the role of the condenser and the throttling valve (considered as a limit condition for an expander with very low isentropic efficiency); marginal analyses performed on the condensation pressure and the isentropic efficiency of the expander provided elements to assess the rational of the cost allocation principles. Attempting to refugee any cost allocation criterion based on postulates, the concept of Scope is identified as a possible non-arbitrary basis for cost allocation in dissipative devices; consequently, a new topology is defined, abandoning the conventional classification between dissipative and productive units, toward a new distinction between Product Makers and Product Takers functions. The proposed approach is applied to the cost accounting of the examined chiller, revealing inadequate and less explicative than the conventional thermoeconomic approaches due to its ''intrinsically differential'' nature. In the Part II of this paper the proposed approach will be applied to an Optimization problem, revealing very flexible and insightful. (author)

Converting Constant Volume, Multizone Air Handling Systems to Energy Efficient Variable Air Volume Multizone Systems

Science.gov (United States)

2017-10-26

TO OTHER ZONE DAMPERS N.O. TEMPERATURE SENSOR CHILLED WATER ZONE 1 STAT SUPPLY FAN COLD DECK COIL TO OTHER ZONE DAMPERS ZONE 1 DAMPER ACTUATOR HOT... water pump usage were considered. Figure 25. Condensing Boiler Combustion Efficiencies 3. Chilled water system losses : Similarly, electrical energy...required to meet cooling demands at the chilled water coil BTU meter is dependent on network losses and chiller energy efficiency ratios. Using

Geothermal ORC Systems Using Large Screw Expanders

OpenAIRE

Biederman, Tim R.; Brasz, Joost J.

2014-01-01

Geothermal ORC Systems using Large Screw Expanders Tim Biederman Cyrq Energy Abstract This paper describes a low-temperature Organic Rankine Cycle Power Recovery system with a screw expander a derivative of developed of Kaishan's line of screw compressors, as its power unit. The screw expander design is a modified version of its existing refrigeration compressor used on water-cooled chillers. Starting the ORC development program with existing refrigeration screw compre...

Economical analysis of combined fuel cell generators and absorption chillers

Directory of Open Access Journals (Sweden)

M. Morsy El-Gohary

2013-06-01

Full Text Available This paper presents a co-generation system based on combined heat and power for commercial units. For installation of a co-generation system, certain estimates for this site should be performed through making assessments of electrical loads, domestic water, and thermal demand. This includes domestic hot water, selection of the type of power generator, fuel cell, and the type of air conditioning system, and absorption chillers. As a matter of fact, the co-generation system has demonstrated good results for both major aspects, economic and environmental. From the environmental point of view, this can be considered as an ideal solution for problems concerned with the usage of Chlorofluoro carbons. On the other hand, from the economic point of view, the cost analysis has revealed that the proposed system saves 4% of total cost through using the co-generation system.

Evaluation of an Extremum Seeking Control Based Optimization and Sequencing Strategy for a Chilled-water Plant

OpenAIRE

Zhao, Zhongfan; Li, Yaoyu; Mu, Baojie; Salsbury, Timothy I.; House, John M.

2016-01-01

Chilled-water plants with multiple chillers account for a significant fraction of energy use in large commercial buildings. Real-time optimization and sequencing of such plants is thus critical for building energy efficiency. Due to the cost and complexity associated with calibrating a chiller plant model to field operation, model-free control has become an attractive solution. Recently, Mu et al. (2015) proposed a model-free real-time optimization and sequencing strategy based on extremum se...

Tri-generation System based on Municipal Waste Gasification, Fuel Cell and an Absorption Chiller

Directory of Open Access Journals (Sweden)

Giannis Katsaros

2018-03-01

Full Text Available The present work focuses on the design of a novel tri-generation system based on gasification of municipal solid wastes, a solid oxide fuel cell and an ammonia-water absorption chiller. Tri-generation systems can be implemented in buildings such as hospitals and hotels, where there is a continuous and large demand for electricity, heating and cooling. The system is modelled in Aspen Plus and the influence of different operating parameters on the system performance was studied. The findings suggest that low air equivalent ratios and high gasification temperatures enhance the overall system performance. Syngas cleaning with metal sorbents zinc oxide and sodium bicarbonate for the removal of hydrogen sulfide and hydrogen chloride concentrations proved to be very effective, reducing the concentration of contaminants to < 1 ppm (part per million levels. The possibility of covering the demand profiles of a specific building was also investigated: the system could fully meet the electricity and cooling demands, whereas the heat requirements could be satisfied only up to 55%. Moreover, assuming 20 years of operation, the payback period was 4.5 years and the net present value exceeded 5 million euros.

Performance investigation of a cogeneration plant with the efficient and compact heat recovery system

KAUST Repository

Myat, Aung

2011-10-03

This paper presents the performance investigation of a cogeneration plant equipped with an efficient waste heat recovery system. The proposed cogeneration system produces four types of useful energy namely: (i) electricity, (ii) steam, (iii) cooling and (iv) dehumidification. The proposed plant comprises a Capstone C30 micro-turbine which generates 24 kW of electricity, a compact and efficient waste heat recovery system and a host of waste heat activated devices namely (i) a steam generator, (ii) an absorption chiller, (iii) an adsorption chiller and (iv) a multi-bed desiccant dehumidifier. The numerical analysis for the host of waste heat recovery system and thermally activated devices using FORTRAN power station linked to powerful IMSL library is performed to investigate the performance of the overall system. A set of experiments, both part load and full load, of micro-turbine is conducted to examine the electricity generation and the exhaust gas temperature. It is observed that energy utilization factor (EUF) could achieve as high as 70% while Fuel Energy Saving Ratio (FESR) is found to be 28%.

Energetic, exergetic and financial evaluation of a solar driven absorption chiller – A dynamic approach

International Nuclear Information System (INIS)

Bellos, Evangelos; Tzivanidis, Christos; Symeou, Christoforos; Antonopoulos, Kimon A.

2017-01-01

Highlights: • A solar cooling system with ETC and a single effect absorption chiller is analyzed. • The analysis is dynamic and it is made for the city of Athens, Greece. • The analysis is energetic, exergetic and financial for all the summer period. • Firstly the system is optimized exergetically and after it is analyzed financially. • The optimum case is 450 m"2 of solar collectors coupled with a storage tank of 14 m"3. - Abstract: In this study, a solar cooling system of 100 kW is analyzed parametrically in dynamic basis for the city of Athens, Greece. The objective of this study is the design of a sustainable system, using energetic, exergetic and financial criteria. The examined system includes evacuated tube collectors, storage tank and a single stage absorption chiller operating with LiBr-H_2O working pair. Different combinations of collecting areas and storage tank volumes are tested in order to determine the most suitable cases exergetically. These optimum cases are evaluated financially and finally the system with the higher financial indexes is selected as the most suitable. More specifically, the collecting area is analyzed from 150 m"2 to 600 m"2 and the storage tank from 6 m"3 to 16 m"3. Finally, 450 m"2 of evacuated tube collectors with a 14 m"3 storage tank was proved to be the optimum solution financially with 15 years payback period and 67 k€ net present value.

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

Wasted Heat Engine Utilization in Central AC Condenser Type Water Chiller for Economical Energy Water Heaters

Directory of Open Access Journals (Sweden)

I Made Rasta

2012-11-01

Full Text Available Central AC type water chiller is a refrigeration machine that release heat to environment. Heat energy that released to environment comes from room heat load that absorbed by machine and heat from compressor. The best form in using this loss energy is heat recovery water heater technology, where this machine will take heat from condenser by a heat exchanger to heating water. Refrigerant will flow in the heat exchanger before entering condenser, after that refrigerant flow to other components such as, expansion valve, evaporator, compressor and than return again to condenser, this process will be cycling regularly (closed cycle. Based on experimental and analysis result especially for AC with capacity 2 Pk, and tank capacity 75 liter, with water heater recovery device obtained that: (1 Compressor power consumption decrease from 1.66 kW to 1.59kW. (2 Heat rejected from condenser and used by water heater has ratio 4.683 kJ/s and 1.59 kJ/s, with water heater efficiency is 32.2%. (3 Maximum water temperature can be reached are in range 34oC – 47.5oC in 10-150 minutes and flow rate is 0.5 – 2.5 liter /min

Advanced cogeneration and absorption chillers potential for service to Navy bases. Final report

Energy Technology Data Exchange (ETDEWEB)

Andrews, J.W.; Butcher, T.A.; Leigh, R.W.; McDonald, R.J.; Pierce, B.L.

1996-04-01

The US military uses millions of Btu`s of thermal energy to heat, cool and deliver process thermal energy to buildings on military bases, much of which is transmitted through a pipeline system incorporating thousands of miles of pipe. Much of this pipeline system is in disrepair and is nearing the end of its useful life, and the boilers which supply it are old and often inefficient. In 1993, Brookhaven National Laboratory (BNL) proposed to SERDP a three-year effort to develop advanced systems of coupled diesel cogenerators and absorption chillers which would be particularly useful in providing a continuation of the services now provided by increasingly antiquated district systems. In mid-February, 1995, BNL learned that all subsequent funding for our program had been canceled. BNL staff continued to develop the Program Plan and to adhere to the requirements of the Execution Plan, but began to look for ways in which the work could be made relevant to Navy and DoD energy needs even without the extensive development plan formerly envisioned. The entire program was therefore re-oriented to look for ways in which small scale cogeneration and absorption chilling technologies, available through procurement rather than development, could provide some solutions to the problem of deteriorated district heating systems. The result is, we believe, a striking new approach to the provision of building services on military bases: in many cases, serious study should be made of the possibility that the old district heating system should be removed or abandoned, and small-scale cogenerators and absorption chillers should be installed in each building. In the remainder of this Summary, we develop the rationale behind this concept and summarize our findings concerning the conditions under which this course of action would be advisable and the economic benefits which will accrue if it is followed. The details are developed in the succeeding sections of the report.

Evaluation of Carcass Quality for Coliforms, Salmonella and Psychrophiles on Evisceration and Chiller lines in Yazd Province Industrial Poultry Slaughterhouses

Directory of Open Access Journals (Sweden)

M Mofidi

2014-05-01

In general, it can be said that secondary contamination in the slaughter line along with gradual increase in temperature of the chiller can increase bacterial load of both coliforms and salmonella but it will not affect the amount of psychrophile bacteria. Due to some differences between the studied slaughterhouses, microbial load of coliform and salmonella can be acheived by improving the management and installation of appropriate aquipments in the evisceration line.

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

Efficient management vital to large, long-term engineering projects

International Nuclear Information System (INIS)

Wolfe, P.L.

1989-01-01

This article describes the ways in which firms manage large hazardous waste mitigation projects efficiently. Staffing concerns, control systems and report mechanisms critical to effective and timely management of these large-scale programs are explored

Performance evaluation of a solar adsorption chiller under different climatic conditions

International Nuclear Information System (INIS)

Alahmer, Ali; Wang, Xiaolin; Al-Rbaihat, Raed; Amanul Alam, K.C.; Saha, B.B.

2016-01-01

Highlights: • A solar adsorption cooling system was studied at different climatic conditions. • Effect of hot water temperature and flow rate on system performance was evaluated. • Solar collector area and tilting angle largely affected the system performance. • Economics of the solar adsorption cooling was analysed at real weather conditions. • Adsorption cooling could be potentially applied in cities with good solar radiation. - Abstract: Performance of an adsorption cooling system driven by solar thermal energy was studied under different climatic conditions. The effects of solar collector area, collector slope, hot water temperature and flow rate on the system performance were investigated using the real-time weather data of two cities: Perth, Australia (a representative city in the southern hemisphere) and Amman, Jordan (a representative city in the northern hemisphere). The simulation results showed that the two cities had similar solar radiation during the summer period and that the solar adsorption chiller could reliably provide cooling at a reasonably high system COP. For residential cooling with a total CPC (Compound Parabolic Collector) solar collector area of 36.22 m"2, the average system COP was 0.491 for Perth weather conditions and 0.467 for Amman weather conditions, respectively while the cooling capacity was 10.3 kW for Perth and 8.46 kW for Amman, respectively at peak times. Optimum performance occurred when the system run with the CPC collector slope of around 30°, the solar water storage tank volume of 1.4 m"3, inlet hot water temperature of 80 °C, and a hot water flow rate of 0.33 kg/s. An economic analysis was further investigated and the results showed that the solar driven adsorption cooling system could reduce the electricity consumption for Perth and Amman cities by 34% and 28%, respectively in comparison to a conventional vapour compression cooling system.

Energy efficiency supervision strategy selection of Chinese large-scale public buildings

International Nuclear Information System (INIS)

Jin Zhenxing; Wu Yong; Li Baizhan; Gao Yafeng

2009-01-01

This paper discusses energy consumption, building development and building energy consumption in China, and points that energy efficiency management and maintenance of large-scale public buildings is the breakthrough point of building energy saving in China. Three obstacles are lack of basic statistics data, lack of service market for building energy saving, and lack of effective management measures account for the necessity of energy efficiency supervision for large-scale public buildings. And then the paper introduces the supervision aims, the supervision system and the five basic systems' role in the supervision system, and analyzes the working mechanism of the five basic systems. The energy efficiency supervision system of large-scale public buildings takes energy consumption statistics as a data basis, Energy auditing as a technical support, energy consumption ration as a benchmark of energy saving and price increase beyond ration as a price lever, and energy efficiency public-noticing as an amplifier. The supervision system promotes energy efficiency operation and maintenance of large-scale public building, and drives a comprehensive building energy saving in China.

Energy efficiency supervision strategy selection of Chinese large-scale public buildings

Energy Technology Data Exchange (ETDEWEB)

Jin, Zhenxing; Li, Baizhan; Gao, Yafeng [The Faculty of Urban Construction and Environmental Engineering, Chongqing University, Chongqing (China); Key Laboratory of the Three Gorges Reservoir Region' s Eco-Environment, Ministry of Education, Chongqing 400045 (China); Wu, Yong [The Department of Science and Technology, Ministry of Construction, Beijing 100835 (China)

2009-06-15

This paper discusses energy consumption, building development and building energy consumption in China, and points that energy efficiency management and maintenance of large-scale public buildings is the breakthrough point of building energy saving in China. Three obstacles are lack of basic statistics data, lack of service market for building energy saving, and lack of effective management measures account for the necessity of energy efficiency supervision for large-scale public buildings. And then the paper introduces the supervision aims, the supervision system and the five basic systems' role in the supervision system, and analyzes the working mechanism of the five basic systems. The energy efficiency supervision system of large-scale public buildings takes energy consumption statistics as a data basis, Energy auditing as a technical support, energy consumption ration as a benchmark of energy saving and price increase beyond ration as a price lever, and energy efficiency public-noticing as an amplifier. The supervision system promotes energy efficiency operation and maintenance of large-scale public building, and drives a comprehensive building energy saving in China. (author)

Energy efficiency supervision strategy selection of Chinese large-scale public buildings

Energy Technology Data Exchange (ETDEWEB)

Jin Zhenxing [Faculty of Urban Construction and Environmental Engineering, Chongqing University, Chongqing (China); Key Laboratory of the Three Gorges Reservoir Region' s Eco-Environment, Ministry of Education, Chongqing 400045 (China)], E-mail: jinzhenxing33@sina.com; Wu Yong [Department of Science and Technology, Ministry of Construction, Beijing 100835 (China); Li Baizhan; Gao Yafeng [Faculty of Urban Construction and Environmental Engineering, Chongqing University, Chongqing (China); Key Laboratory of the Three Gorges Reservoir Region' s Eco-Environment, Ministry of Education, Chongqing 400045 (China)

2009-06-15

This paper discusses energy consumption, building development and building energy consumption in China, and points that energy efficiency management and maintenance of large-scale public buildings is the breakthrough point of building energy saving in China. Three obstacles are lack of basic statistics data, lack of service market for building energy saving, and lack of effective management measures account for the necessity of energy efficiency supervision for large-scale public buildings. And then the paper introduces the supervision aims, the supervision system and the five basic systems' role in the supervision system, and analyzes the working mechanism of the five basic systems. The energy efficiency supervision system of large-scale public buildings takes energy consumption statistics as a data basis, Energy auditing as a technical support, energy consumption ration as a benchmark of energy saving and price increase beyond ration as a price lever, and energy efficiency public-noticing as an amplifier. The supervision system promotes energy efficiency operation and maintenance of large-scale public building, and drives a comprehensive building energy saving in China.

Large Efficient Intelligent Heating Relay Station System

Science.gov (United States)

Wu, C. Z.; Wei, X. G.; Wu, M. Q.

2017-12-01

The design of large efficient intelligent heating relay station system aims at the improvement of the existing heating system in our country, such as low heating efficiency, waste of energy and serious pollution, and the control still depends on the artificial problem. In this design, we first improve the existing plate heat exchanger. Secondly, the ATM89C51 is used to control the whole system and realize the intelligent control. The detection part is using the PT100 temperature sensor, pressure sensor, turbine flowmeter, heating temperature, detection of user end liquid flow, hydraulic, and real-time feedback, feedback signal to the microcontroller through the heating for users to adjust, realize the whole system more efficient, intelligent and energy-saving.

Aerodynamic Limits on Large Civil Tiltrotor Sizing and Efficiency

Science.gov (United States)

Acree, C W.

2014-01-01

The NASA Large Civil Tiltrotor (2nd generation, or LCTR2) is a useful reference design for technology impact studies. The present paper takes a broad view of technology assessment by examining the extremes of what aerodynamic improvements might hope to accomplish. Performance was analyzed with aerodynamically idealized rotor, wing, and airframe, representing the physical limits of a large tiltrotor. The analysis was repeated with more realistic assumptions, which revealed that increased maximum rotor lift capability is potentially more effective in improving overall vehicle efficiency than higher rotor or wing efficiency. To balance these purely theoretical studies, some practical limitations on airframe layout are also discussed, along with their implications for wing design. Performance of a less efficient but more practical aircraft with non-tilting nacelles is presented.

Assessing the microbiomes of scalder and chiller tank waters throughout a typical commercial poultry processing day.

Science.gov (United States)

Rothrock, M J; Locatelli, A; Glenn, T C; Thomas, J C; Caudill, A C; Kiepper, B H; Hiett, K L

2016-10-01

The commercial poultry processing environment plays a significant role in reducing foodborne pathogens and spoilage organisms from poultry products prior to being supplied to consumers. While understanding the microbiological quality of these products is essential, little is known about the microbiota of processing water tanks within the processing plant. Therefore, the goal of this study was to assess the microbiomes of the scalder and chiller tanks during a typical commercial processing d, and determine how bacterial populations, including foodborne pathogens and spoilage organisms, change during the processing day in relation to the bacterial communities as a whole. Additionally, considering this is the first microbiomic analysis of processing tank waters, 2 water sampling methods also were compared. Results of this study show that Proteobacteria and Firmicutes represented over half of the sequences recovered from both tanks at the phylum level, but the microbiomic profiles needed to be analyzed at the genus level to observe more dynamic population shifts. Bacteria known to predominate in the live production environment were found to increase in the scalder tank and gram negative spoilage-related bacteria were found to decrease in the chiller tank throughout the processing day. Directly sampling the scalder water, as compared to analyzing filtered samples, resulted in significantly different microbiomic profiles dominated by Anoxybacillus species. While no sequences related to major foodborne pathogens were found, further sampling collection and processing optimization should provide researchers and the poultry industry a new tool to understand the ecological role of spoilage and pathogenic bacteria within processing tank waters. Published by Oxford University Press on behalf of Poultry Science Association 2016. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Energy Efficient Alternatives to Chlorofluorocarbons (CFCs)

Energy Technology Data Exchange (ETDEWEB)

None

1993-06-01

An assessment of the state of the art in refrigeration and insulation technologies is carried out to evaluate the potential for efficient substitutes for CFCs and HCFCs to facilitate the transition to a CFC-free environment. Opportunities for improved efficiency in domestic refrigeration, building chillers, commercial refrigeration and industrial refrigeration are evaluated. Needs for alternate refrigerants, improved components, and/or alternate cycles are identified. A summary of on-going research is presented in each area, and the potential roles of industry and government are considered. The most promising approaches for refrigeration technology fall into these categories: (1) improved vapor compressor cycles with alternate fluids, (2) Stirling cycle development and (3) advances in absorption technology. A summary of on-going research into advanced insulation, focused on vacuum-based insulation technology refrigeration is developed. Insulation applications considered include appliances, transport refrigeration, and buildings. Specific recommendations for a long-term R&D agenda are presented. The potential benefits, research, general approach, and probability of success are addressed.

Experimental studies of solar heat pipe used to operate absorption chiller in conditions of Vietnam

Energy Technology Data Exchange (ETDEWEB)

Hiep, Le Chi [Ho Chi Minh City Univ. of Tech., Ho Chi Minh City (Viet Nam); Quoc, Hoang An [Ho Chi Minh City Univ. of Tech. Education, Ho Chi Minh City (Viet Nam); Hung, Hoang Duong [Danang Univ. of Tech., Danang City (Viet Nam)

2008-07-01

Several models of solar heat pipe have been fabricated and tested. The experiments show that the flat plate model could be used to operate absorption chiller in the climate of southern part of Vietnam. Two main advantages of the selected solar heat pipe are low cost and easy fabrication at local conditions. It is expected that the selected solar heat pipe could attract attention of the community to develop the application of solar energy in Vietnam. Based on the current demand, the paper presents the experimental studies of the first generation of low cost solar heat pipe. The paper also discusses the ability of application of solar air conditioning in Vietnam and recommends the suitable diagram mixing solar energy with other heat source to operate stably the system. (orig.)

Energy efficient hybrid nanocomposite-based cool thermal storage air conditioning system for sustainable buildings

International Nuclear Information System (INIS)

Parameshwaran, R.; Kalaiselvam, S.

2013-01-01

The quest towards energy conservative building design is increasingly popular in recent years, which has triggered greater interests in developing energy efficient systems for space cooling in buildings. In this work, energy efficient silver–titania HiTES (hybrid nanocomposites-based cool thermal energy storage) system combined with building A/C (air conditioning) system was experimentally investigated for summer and winter design conditions. HiNPCM (hybrid nanocomposite particles embedded PCM) used as the heat storage material has exhibited 7.3–58.4% of improved thermal conductivity than at its purest state. The complete freezing time for HiNPCM was reduced by 15% which was attributed to its improved thermophysical characteristics. Experimental results suggest that the effective energy redistribution capability of HiTES system has contributed for reduction in the chiller nominal cooling capacity by 46.3% and 39.6% respectively, under part load and on-peak load operating conditions. The HiTES A/C system achieved 27.3% and 32.5% of on-peak energy savings potential in summer and winter respectively compared to the conventional A/C system. For the same operating conditions, this system yield 8.3%, 12.2% and 7.2% and 10.2% of per day average and yearly energy conservation respectively. This system can be applied for year-round space conditioning application without sacrificing energy efficiency in buildings. - Highlights: • Energy storage is acquired by HiTES (hybrid nanocomposites-thermal storage) system. • Thermal conductivity of HiNPCM (hybrid nanocomposites-PCM) was improved by 58.4%. • Freezing time of HiNPCM was reduced by 15% that enabled improved energy efficiency. • Chiller nominal capacity was reduced by 46.3% and 39.6% in on-peak and part load respectively. • HiTES A/C system achieved appreciable energy savings in the range of 8.3–12.2%

Estudo do resfriamento de carcaças de frango em chiller de imersão em água

OpenAIRE

Carciofi, Bruno Augusto Mattar

2005-01-01

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia de Alimentos O resfriamento industrial de carcaças de frango é normalmente efetuado em tanques de imersão em água (chillers). Nesta etapa, além da redução da temperatura, ocorre absorção de água pelas carcaças. Neste trabalho foram estudados diversos aspectos relacionados com a redução da temperatura e com a absorção de água por carcaças resfriadas por imersão, além ...

Quantum efficiency measurement system for large area CsI photodetectors

CERN Document Server

Cusanno, F; Colilli, S; Crateri, R; Fratoni, R; Frullani, S; Garibaldi, F; Giuliani, F; Gricia, M; Lucentini, M; Mostarda, A; Santavenere, F; Veneroni, P; Breuer, H; Iodice, M; Urciuoli, G M; De Cataldo, G; De Leo, R; Lagamba, L; Braem, André

2003-01-01

A proximity focusing freon/CsI RICH detector has been built for kaon physics at Thomas Jefferson National Accelerator Facility (TJNAF or Jefferson Lab), Hall A. The Cherenkov photons are detected by a UV photosensitive CsI film which has been obtained by vacuum evaporation. A dedicated evaporation facility for large area photocathodes has been built for this task. A measuring system has been built to allow the evaluation of the absolute quantum efficiency (QE) just after the evaporation. The evaporation facility is described here, as well as the quantum efficiency measurement device. Results of the QE on-line measurements, for the first time on large area photocathodes, are reported.

Energy-efficiency supervision systems for energy management in large public buildings: Necessary choice for China

International Nuclear Information System (INIS)

Feng Yanping; Wu Yong; Liu Changbin

2009-01-01

Buildings are important contributors to total energy consumption accounting for around 30% of all energy consumed in China. Of this, around two-fifths are consumed within urban homes, one-fifth within public buildings, and two-fifths within rural area. Government office buildings and large-scale public buildings are the dominant energy consumers in cities but their consumption can be largely cut back through improving efficiency. At present, energy management in the large public sector is a particular priority in China. Firstly, this paper discusses how the large public building is defined, and then energy performance in large public buildings is studied. The paper also describes barriers to improving energy efficiency of large public buildings in China and examines the energy-efficiency policies and programs adopted in United States and European Union. The energy-efficiency supervision (EES) systems developed to improve operation and maintenance practices and promote energy efficiency in large public sector are described. The benefits of the EES systems are finally summarized.

Energy-efficiency supervision systems for energy management in large public buildings. Necessary choice for China

Energy Technology Data Exchange (ETDEWEB)

Yan-ping, Feng [Beijing Jiaotong University, School of Economics and Management, Jiaoda Donglu18, 5-803, Beijing 100044 (China); Yong, Wu [Ministry of Housing and Urban-Rural Development, Beijing 100835 (China); Chang-bin, Liu [Beijing Institute of Civil Engineering and Architecture, Beijing 100044 (China)

2009-06-15

Buildings are important contributors to total energy consumption accounting for around 30% of all energy consumed in China. Of this, around two-fifths are consumed within urban homes, one-fifth within public buildings, and two-fifths within rural area. Government office buildings and large-scale public buildings are the dominant energy consumers in cities but their consumption can be largely cut back through improving efficiency. At present, energy management in the large public sector is a particular priority in China. Firstly, this paper discusses how the large public building is defined, and then energy performance in large public buildings is studied. The paper also describes barriers to improving energy efficiency of large public buildings in China and examines the energy-efficiency policies and programs adopted in United States and European Union. The energy-efficiency supervision (EES) systems developed to improve operation and maintenance practices and promote energy efficiency in large public sector are described. The benefits of the EES systems are finally summarized. (author)

Energy-efficiency supervision systems for energy management in large public buildings: Necessary choice for China

Energy Technology Data Exchange (ETDEWEB)

Feng Yanping [Beijing Jiaotong University, School of Economics and Management, Jiaoda Donglu18, 5-803, Beijing 100044 (China)], E-mail: fengyanping10@sohu.com; Wu Yong [Ministry of Housing and Urban-Rural Development, Beijing 100835 (China); Liu Changbin [Beijing Institute of Civil Engineering and Architecture, Beijing 100044 (China)

2009-06-15

Buildings are important contributors to total energy consumption accounting for around 30% of all energy consumed in China. Of this, around two-fifths are consumed within urban homes, one-fifth within public buildings, and two-fifths within rural area. Government office buildings and large-scale public buildings are the dominant energy consumers in cities but their consumption can be largely cut back through improving efficiency. At present, energy management in the large public sector is a particular priority in China. Firstly, this paper discusses how the large public building is defined, and then energy performance in large public buildings is studied. The paper also describes barriers to improving energy efficiency of large public buildings in China and examines the energy-efficiency policies and programs adopted in United States and European Union. The energy-efficiency supervision (EES) systems developed to improve operation and maintenance practices and promote energy efficiency in large public sector are described. The benefits of the EES systems are finally summarized.

Potential of district cooling in hot and humid climates

DEFF Research Database (Denmark)

Dominkovic, Dominik Franjo; Rashid, K. A. Bin Abdul; Romagnoli, A.

2017-01-01

Efficiently utilizing energy that is currently being wasted can significantly increase energy efficiency of the system, as well as reduce the carbon footprint. In hot climates with large cooling demands, excess waste heat can be utilized via absorption chillers to generate cold. Moreover, cold from...... liquefied natural gas gasification process can further provide energy source for meeting the cold demand. In order to connect the large sources of waste heat and cold energy with customers demanding the cold, a significant investment in district cooling grid is a necessity. In order to deal...

Large-area high-efficiency flexible PHOLED lighting panels

Science.gov (United States)

Pang, Huiqing; Mandlik, Prashant; Levermore, Peter A.; Silvernail, Jeff; Ma, Ruiqing; Brown, Julie J.

2012-09-01

Organic Light Emitting Diodes (OLEDs) provide various attractive features for next generation illumination systems, including high efficiency, low power, thin and flexible form factor. In this work, we incorporated phosphorescent emitters and demonstrated highly efficient white phosphorescent OLED (PHOLED) devices on flexible plastic substrates. The 0.94 cm2 small-area device has total thickness of approximately 0.25 mm and achieved 63 lm/W at 1,000 cd/m2 with CRI = 85 and CCT = 2920 K. We further designed and fabricated a 15 cm x 15 cm large-area flexible white OLED lighting panels, finished with a hybrid single-layer ultra-low permeability single layer barrier (SLB) encapsulation film. The flexible panel has an active area of 116.4 cm2, and achieved a power efficacy of 47 lm/W at 1,000 cd/m2 with CRI = 83 and CCT = 3470 K. The efficacy of the panel at 3,000 cd/m2 is 43 lm/W. The large-area flexible PHOLED lighting panel is to bring out enormous possibilities to the future general lighting applications.

Large-scale building energy efficiency retrofit: Concept, model and control

International Nuclear Information System (INIS)

Wu, Zhou; Wang, Bo; Xia, Xiaohua

2016-01-01

BEER (Building energy efficiency retrofit) projects are initiated in many nations and regions over the world. Existing studies of BEER focus on modeling and planning based on one building and one year period of retrofitting, which cannot be applied to certain large BEER projects with multiple buildings and multi-year retrofit. In this paper, the large-scale BEER problem is defined in a general TBT (time-building-technology) framework, which fits essential requirements of real-world projects. The large-scale BEER is newly studied in the control approach rather than the optimization approach commonly used before. Optimal control is proposed to design optimal retrofitting strategy in terms of maximal energy savings and maximal NPV (net present value). The designed strategy is dynamically changing on dimensions of time, building and technology. The TBT framework and the optimal control approach are verified in a large BEER project, and results indicate that promising performance of energy and cost savings can be achieved in the general TBT framework. - Highlights: • Energy efficiency retrofit of many buildings is studied. • A TBT (time-building-technology) framework is proposed. • The control system of the large-scale BEER is modeled. • The optimal retrofitting strategy is obtained.

Efficient algorithms for collaborative decision making for large scale settings

DEFF Research Database (Denmark)

Assent, Ira

2011-01-01

to bring about more effective and more efficient retrieval systems that support the users' decision making process. We sketch promising research directions for more efficient algorithms for collaborative decision making, especially for large scale systems.......Collaborative decision making is a successful approach in settings where data analysis and querying can be done interactively. In large scale systems with huge data volumes or many users, collaboration is often hindered by impractical runtimes. Existing work on improving collaboration focuses...... on avoiding redundancy for users working on the same task. While this improves the effectiveness of the user work process, the underlying query processing engine is typically considered a "black box" and left unchanged. Research in multiple query processing, on the other hand, ignores the application...

Efficient motif finding algorithms for large-alphabet inputs

Directory of Open Access Journals (Sweden)

Pavlovic Vladimir

2010-10-01

Full Text Available Abstract Background We consider the problem of identifying motifs, recurring or conserved patterns, in the biological sequence data sets. To solve this task, we present a new deterministic algorithm for finding patterns that are embedded as exact or inexact instances in all or most of the input strings. Results The proposed algorithm (1 improves search efficiency compared to existing algorithms, and (2 scales well with the size of alphabet. On a synthetic planted DNA motif finding problem our algorithm is over 10× more efficient than MITRA, PMSPrune, and RISOTTO for long motifs. Improvements are orders of magnitude higher in the same setting with large alphabets. On benchmark TF-binding site problems (FNP, CRP, LexA we observed reduction in running time of over 12×, with high detection accuracy. The algorithm was also successful in rapidly identifying protein motifs in Lipocalin, Zinc metallopeptidase, and supersecondary structure motifs for Cadherin and Immunoglobin families. Conclusions Our algorithm reduces computational complexity of the current motif finding algorithms and demonstrate strong running time improvements over existing exact algorithms, especially in important and difficult cases of large-alphabet sequences.

Energy efficient heating and ventilation of large halls

CERN Document Server

Hojer, Ondrej; Kabele, Karel; Kotrbaty, Miroslav; Sommer, Klaus; Petras, Dusan

2011-01-01

This guidebook is focused on modern methods for design, control and operation of energy efficient heating systems in large spaces and industrial halls. The book deals with thermal comfort, light and dark gas radiant heaters, panel radiant heating, floor heating and industrial air heating systems. Various heating systems are illustrated with case studies. Design principles, methods and modeling tools are presented for various systems.

Economic analysis of solar assisted absorption chiller for a commercial building

Science.gov (United States)

Antonyraj, Gnananesan

Dwindling fossil fuels coupled with changes in global climate intensified the drive to make use of renewable energy resources that have negligible impact on the environment. In this attempt, the industrial community produced various devices and systems to make use of solar energy for heating and cooling of building space as well as generate electric power. The most common components employed for collection of solar energy are the flat plate and evacuated tube collectors that produce hot water that can be employed for heating the building space. In order to cool the building, the absorption chiller is commonly employed that requires hot water at high temperatures for its operation. This thesis deals with economic analysis of solar collector and absorption cooling system to meet the building loads of a commercial building located in Chattanooga, Tennessee. Computer simulations are employed to predict the hourly building loads and performance of the flat plate and evacuated tube solar collectors using the hourly weather data. The key variables affecting the economic evaluation of such system are identified and the influence of these parameters is presented. The results of this investigation show that the flat plate solar collectors yield lower payback period compared to the evacuated tube collectors and economic incentives offered by the local and federal agencies play a major role in lowering the payback period.

Enhancements of thermal conductivities with Cu, CuO, and carbon nanotube nanofluids and application of MWNT/water nanofluid on a water chiller system

Directory of Open Access Journals (Sweden)

Lin Mark

2011-01-01

Full Text Available Abstract In this study, enhancements of thermal conductivities of ethylene glycol, water, and synthetic engine oil in the presence of copper (Cu, copper oxide (CuO, and multi-walled carbon nanotube (MWNT are investigated using both physical mixing method (two-step method and chemical reduction method (one-step method. The chemical reduction method is, however, used only for nanofluid containing Cu nanoparticle in water. The thermal conductivities of the nanofluids are measured by a modified transient hot wire method. Experimental results show that nanofluids with low concentration of Cu, CuO, or carbon nanotube (CNT have considerably higher thermal conductivity than identical base liquids. For CuO-ethylene glycol suspensions at 5 vol.%, MWNT-ethylene glycol at 1 vol.%, MWNT-water at 1.5 vol.%, and MWNT-synthetic engine oil at 2 vol.%, thermal conductivity is enhanced by 22.4, 12.4, 17, and 30%, respectively. For Cu-water at 0.1 vol.%, thermal conductivity is increased by 23.8%. The thermal conductivity improvement for CuO and CNT nanofluids is approximately linear with the volume fraction. On the other hand, a strong dependence of thermal conductivity on the measured time is observed for Cu-water nanofluid. The system performance of a 10-RT water chiller (air conditioner subject to MWNT/water nanofluid is experimentally investigated. The system is tested at the standard water chiller rating condition in the range of the flow rate from 60 to 140 L/min. In spite of the static measurement of thermal conductivity of nanofluid shows only 1.3% increase at room temperature relative to the base fluid at volume fraction of 0.001 (0.1 vol.%, it is observed that a 4.2% increase of cooling capacity and a small decrease of power consumption about 0.8% occur for the nanofluid system at a flow rate of 100 L/min. This result clearly indicates that the enhancement of cooling capacity is not just related to thermal conductivity alone. Dynamic effect, such as

Model-based optimization strategy of chiller driven liquid desiccant dehumidifier with genetic algorithm

International Nuclear Information System (INIS)

Wang, Xinli; Cai, Wenjian; Lu, Jiangang; Sun, Youxian; Zhao, Lei

2015-01-01

This study presents a model-based optimization strategy for an actual chiller driven dehumidifier of liquid desiccant dehumidification system operating with lithium chloride solution. By analyzing the characteristics of the components, energy predictive models for the components in the dehumidifier are developed. To minimize the energy usage while maintaining the outlet air conditions at the pre-specified set-points, an optimization problem is formulated with an objective function, the constraints of mechanical limitations and components interactions. Model-based optimization strategy using genetic algorithm is proposed to obtain the optimal set-points for desiccant solution temperature and flow rate, to minimize the energy usage in the dehumidifier. Experimental studies on an actual system are carried out to compare energy consumption between the proposed optimization and the conventional strategies. The results demonstrate that energy consumption using the proposed optimization strategy can be reduced by 12.2% in the dehumidifier operation. - Highlights: • Present a model-based optimization strategy for energy saving in LDDS. • Energy predictive models for components in dehumidifier are developed. • The Optimization strategy are applied and tested in an actual LDDS. • Optimization strategy can achieve energy savings by 12% during operation

Development of a Wind Directly Forced Heat Pump and Its Efficiency Analysis

Directory of Open Access Journals (Sweden)

Ching-Song Jwo

2013-01-01

Full Text Available The requirements of providing electric energy through the wind-forced generator to the heat pump for water cooling and hot water heating grow significantly by now. This study proposes a new technique to directly adopt the wind force to drive heat pump systems, which can effectively reduce the energy conversion losses during the processes of wind force energy converting to electric energy and electric energy converting to kinetic energy. The operation of heat pump system transfers between chiller and heat that are controlled by a four-way valve. The theoretical efficiency of the traditional method, whose heat pump is directly forced by wind, is 42.19%. The experimental results indicated average value for cool water producing efficiency of 54.38% in the outdoor temperature of 35°C and the indoor temperature of 25°C and the hot water producing efficiency of 52.25% in the outdoor temperature and the indoor temperature both of 10°C. We proposed a method which can improve the efficiency over 10% in both cooling and heating.

Solid oxide fuel cell/gas turbine trigeneration system for marine applications

Science.gov (United States)

Tse, Lawrence Kar Chung; Wilkins, Steven; McGlashan, Niall; Urban, Bernhard; Martinez-Botas, Ricardo

2011-03-01

Shipping contributes 4.5% to global CO2 emissions and is not covered by the Kyoto Agreement. One method of reducing CO2 emissions on land is combined cooling heating and power (CCHP) or trigeneration, with typical combined thermal efficiencies of over 80%. Large luxury yachts are seen as an ideal entry point to the off-shore market for this developing technology considering its current high cost. This paper investigates the feasibility of combining a SOFC-GT system and an absorption heat pump (AHP) in a trigeneration system to drive the heating ventilation and air conditioning (HVAC) and electrical base-load systems. A thermodynamic model is used to simulate the system, with various configurations and cooling loads. Measurement of actual yacht performance data forms the basis of this system simulation. It is found that for the optimum configuration using a double effect absorption chiller in Ship 1, the net electric power increases by 47% relative to the electrical power available for a conventional SOFC-GT-HVAC system. This is due to more air cooled to a lower temperature by absorption cooling; hence less electrical cooling by the conventional HVAC unit is required. The overall efficiency is 12.1% for the conventional system, 34.9% for the system with BROAD single effect absorption chiller, 43.2% for the system with double effect absorption chiller. This shows that the overall efficiency of a trigeneration system is far higher when waste heat recovery happens. The desiccant wheel hardly reduces moisture from the outdoor air due to a relative low mass flow rate of fuel cell exhaust available to dehumidify a very large mass flow rate of HVAC air, Hence, desiccant wheel is not recommended for this application.

Design and analysis of a waste gasification energy system with solid oxide fuel cells and absorption chillers

DEFF Research Database (Denmark)

Rokni, Masoud

2018-01-01

Energy saving is an open point in most European countries where energy policies are oriented to reduce the use of fossil fuels, greenhouses emissions and energy independence, and to increase the use of renewable energies. In the last several years, new technologies have been developed and some...... of them received subsidies to increase installation and reduce cost. This article presents a new sustainable trigeneration system (power, heat and cool) based on a solid oxide fuel cell (SOFC) system integrated with an absorption chiller for special applications such as hotels, resorts, hospitals, etc....... with a focus on plant design and performance. The proposal system is based on the idea of gasifying the municipal waste, producing syngas serving as fuel for the trigeneration system. Such advanced system when improved is thus self-sustainable without dependency on net grid, district heating and district...

Development of a high temperature solar powered water chiller. Volume 3. Phase I technical progress report, September 26, 1977--June 1, 1978

Energy Technology Data Exchange (ETDEWEB)

English, R. A.

1978-06-01

This section describes the conceptual design rationale and resulting design configuration as well as providing estimates of cost and performance. Because the development of the turbo-compressor design paralleled the development of the chiller system design, all of the cost and performance data are based on intermediate turbo-compressor performance data, as well as on unoptimized components. Optimized performance was computed at the very end of Phase I, and only a brief comparison is made to show the potential gains available. Updating of all the predicted performance data for the final conceptual design will await Phase II.

Superconductors and novel ceramics for future communication technologies. Project: Cooler and cryotechnology. Final report

International Nuclear Information System (INIS)

Haefner, H.U.; Rolff, N.; Thummes, G.

2004-02-01

The project involved the production of a 6W rate at 77K stirling chiller for a HTS telecommunication experiment on the 'International Space Station' (project partner Bosch Telecom) and the production of a prototype long-lived stirling pulsed tube chiller of 10W rate at 77K for future applications in telecommunication. The projected was terminated prematurely. The following results were obtained: 1. The low-capacity chiller 'Mono-Kaltfinger' (stirling cold finger with displacement piston) achieved up to 5.3% COP at 80 K. 2. The chilling capacity was 10 W at 80 K for a maximum compressor uptake of 250 W. 3. An efficient pulsed tube chiller was constructed, as well as 4. A long-lived compressor with flexure bearings. (orig.) [de

The study on the evaporation cooling efficiency and effectiveness of cooling tower of film type

International Nuclear Information System (INIS)

Li Yingjian; You Xinkui; Qiu Qi; Li Jiezhi

2011-01-01

Based on heat and mass transport mechanism of film type cooling, which was combined with an on-site test on counter flow film type cooling tower, a mathematical model on the evaporation and cooling efficiency and effectiveness has been developed. Under typical climatic conditions, air conditioning load and the operating condition, the mass and heat balances have been calculated for the air and the cooling water including the volume of evaporative cooling water. Changing rule has been measured and calculated between coefficient of performance (COP) and chiller load. The influences of air and cooling water parameters on the evaporative cooling efficiency were analyzed in cooling tower restrained by latent heat evaporative cooling, and detailed derivation and computation revealed that both the evaporative cooling efficiency and effectiveness of cooling tower are the same characteristics parameters of the thermal performance of a cooling tower under identical assumptions.

Solar driven air conditioning and refrigeration systems corresponding to various heating source temperatures

International Nuclear Information System (INIS)

Wang, R.Z.; Xu, Z.Y.; Pan, Q.W.; Du, S.; Xia, Z.Z.

2016-01-01

Highlights: • Modular silica gel–water adsorption chiller was designed and tested. • Single/double effect LiBr–water absorption chiller was operated and tested. • 1.n effect LiBr–water absorption chiller was proposed, designed and tested. • CaCl_2/AC–ammonia adsorption refrigerator was introduced and tested. • NH_3–H_2O absorption ice maker with better internal heat recovery was introduced. - Abstract: Solar driven air conditioning systems can cope with solar collectors working in a wide range of temperatures. Sorption systems, including absorption and adsorption refrigeration systems, are among the best choices for solar cooling. Five systems including modular silica gel–water adsorption chiller, single/double effect LiBr–water absorption chiller, 1.n effect LiBr–water absorption chiller, CaCl_2/AC (activated carbon)–ammonia adsorption refrigerator, and the water–ammonia absorption ice maker with better internal heat recovery were presented. The above five sorption chillers/refrigerators work under various driven temperatures and fulfill different refrigeration demands. The thermodynamic design and system development of the systems were shown. All these systems have improvements in comparison with existing systems and may offer good options for high efficient solar cooling in the near future.

Efficient characterisation of large deviations using population dynamics

Science.gov (United States)

Brewer, Tobias; Clark, Stephen R.; Bradford, Russell; Jack, Robert L.

2018-05-01

We consider population dynamics as implemented by the cloning algorithm for analysis of large deviations of time-averaged quantities. We use the simple symmetric exclusion process with periodic boundary conditions as a prototypical example and investigate the convergence of the results with respect to the algorithmic parameters, focussing on the dynamical phase transition between homogeneous and inhomogeneous states, where convergence is relatively difficult to achieve. We discuss how the performance of the algorithm can be optimised, and how it can be efficiently exploited on parallel computing platforms.

Metal-Organic Frameworks in Adsorption-Driven Heat Pumps: The Potential of Alcohols as Working Fluids.

Science.gov (United States)

de Lange, Martijn F; van Velzen, Benjamin L; Ottevanger, Coen P; Verouden, Karlijn J F M; Lin, Li-Chiang; Vlugt, Thijs J H; Gascon, Jorge; Kapteijn, Freek

2015-11-24

A large fraction of global energy is consumed for heating and cooling. Adsorption-driven heat pumps and chillers could be employed to reduce this consumption. MOFs are often considered to be ideal adsorbents for heat pumps and chillers. While most published works to date on this topic have focused on the use of water as a working fluid, the instability of many MOFs to water and the fact that water cannot be used at subzero temperatures pose certain drawbacks. The potential of using alcohol-MOF pairs in adsorption-driven heat pumps and chillers is investigated. To this end, 18 different selected MOF structures in combination with either methanol or ethanol as a working fluid are considered, and their potential is assessed on the basis of adsorption measurements and thermodynamic efficiencies. If alcohols are used instead of water, then (1) adsorption occurs at lower relative pressures for methanol and even lower pressure for ethanol, (2) larger pores can be utilized efficiently, as hysteresis is absent for pores smaller than 3.4 nm (2 nm for water), (3) larger pore sizes need to be employed to ensure the desired stepwise adsorption, (4) the effect of (polar/apolar) functional groups in the MOF is far less pronounced, (5) the energy released or taken up per cycle is lower, but heat and mass transfer may be enhanced, (6) stability of MOFs seems to be less of an issue, and (7) cryogenic applications (e.g., ice making) become feasible. From a thermodynamic perspective, UiO-67, CAU-3, and ZIF-8 seem to be the most promising MOFs for both methanol and ethanol as working fluids. Although UiO-67 might not be completely stable, both CAU-3 and ZIF-8 have the potential to be applied, especially in subzero-temperature adsorption chillers (AC).

Optimum hot water temperature for absorption solar cooling

Energy Technology Data Exchange (ETDEWEB)

Lecuona, A.; Ventas, R.; Venegas, M.; Salgado, R. [Dpto. Ingenieria Termica y de Fluidos, Universidad Carlos III de Madrid, Avda. Universidad 30, 28911 Leganes, Madrid (Spain); Zacarias, A. [ESIME UPA, IPN, Av. de las Granjas 682, Col. Santa Catarina, 02550, D.F. Mexico (Mexico)

2009-10-15

The hot water temperature that maximizes the overall instantaneous efficiency of a solar cooling facility is determined. A modified characteristic equation model is used and applied to single-effect lithium bromide-water absorption chillers. This model is based on the characteristic temperature difference and serves to empirically calculate the performance of real chillers. This paper provides an explicit equation for the optimum temperature of vapor generation, in terms of only the external temperatures of the chiller. The additional data required are the four performance parameters of the chiller and essentially a modified stagnation temperature from the detailed model of the thermal collector operation. This paper presents and discusses the results for small capacity machines for air conditioning of homes and small buildings. The discussion highlights the influence of the relevant parameters. (author)

High-Efficiency, Multijunction Solar Cells for Large-Scale Solar Electricity Generation

Science.gov (United States)

Kurtz, Sarah

2006-03-01

A solar cell with an infinite number of materials (matched to the solar spectrum) has a theoretical efficiency limit of 68%. If sunlight is concentrated, this limit increases to about 87%. These theoretical limits are calculated using basic physics and are independent of the details of the materials. In practice, the challenge of achieving high efficiency depends on identifying materials that can effectively use the solar spectrum. Impressive progress has been made with the current efficiency record being 39%. Today's solar market is also showing impressive progress, but is still hindered by high prices. One strategy for reducing cost is to use lenses or mirrors to focus the light on small solar cells. In this case, the system cost is dominated by the cost of the relatively inexpensive optics. The value of the optics increases with the efficiency of the solar cell. Thus, a concentrator system made with 35%- 40%-efficient solar cells is expected to deliver 50% more power at a similar cost when compare with a system using 25%-efficient cells. Today's markets are showing an opportunity for large concentrator systems that didn't exist 5-10 years ago. Efficiencies may soon pass 40% and ultimately may reach 50%, providing a pathway to improved performance and decreased cost. Many companies are currently investigating this technology for large-scale electricity generation. The presentation will cover the basic physics and more practical considerations to achieving high efficiency as well as describing the current status of the concentrator industry. This work has been authored by an employee of the Midwest Research Institute under Contract No. DE- AC36-99GO10337 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow

ESTIMATION OF EFFICIENCY PARTNERSHIP LARGE AND SMALL BUSINESS

Directory of Open Access Journals (Sweden)

Олег Васильевич Чабанюк

2014-05-01

Full Text Available In this  article, based on the definition of key factors and its components, developed an algorithm consistent, logically connected stages of the transition from the traditional enterprise to enterprise innovation typebased becoming intrapreneurship. Аnalysis of economic efficiency of innovative business idea is: based on the determination of experts the importance of the model parameters ensure the effectiveness of intrapreneurship by using methods of kvalimetricheskogo modeling expert estimates score calculated "efficiency intrapreneurship". On the author's projected optimum level indicator should exceed 0.5, but it should be noted that the achievement of this level is possible with the 2 - 3rd year of existence intraprenerskoy structure. The proposed method was tested in practice and can be used for the formation of intrapreneurship in large and medium-sized enterprises as one of the methods of implementation of the innovation activities of small businesses.DOI: http://dx.doi.org/10.12731/2218-7405-2013-10-50

Improving the computation efficiency of COBRA-TF for LWR safety analysis of large problems

International Nuclear Information System (INIS)

Cuervo, D.; Avramova, M. N.; Ivanov, K. N.

2004-01-01

A matrix solver is implemented in COBRA-TF in order to improve the computation efficiency of both numerical solution methods existing in the code, the Gauss elimination and the Gauss-Seidel iterative technique. Both methods are used to solve the system of pressure linear equations and relay on the solution of large sparse matrices. The introduced solver accelerates the solution of these matrices in cases of large number of cells. The execution time is reduced in half as compared to the execution time without using matrix solver for the cases with large matrices. The achieved improvement and the planned future work in this direction are important for performing efficient LWR safety analyses of large problems. (authors)

Efficient Disk-Based Techniques for Manipulating Very Large String Databases

KAUST Repository

Allam, Amin

2017-05-18

Indexing and processing strings are very important topics in database management. Strings can be database records, DNA sequences, protein sequences, or plain text. Various string operations are required for several application categories, such as bioinformatics and entity resolution. When the string count or sizes become very large, several state-of-the-art techniques for indexing and processing such strings may fail or behave very inefficiently. Modifying an existing technique to overcome these issues is not usually straightforward or even possible. A category of string operations can be facilitated by the suffix tree data structure, which basically indexes a long string to enable efficient finding of any substring of the indexed string, and can be used in other operations as well, such as approximate string matching. In this document, we introduce a novel efficient method to construct the suffix tree index for very long strings using parallel architectures, which is a major challenge in this category. Another category of string operations require clustering similar strings in order to perform application-specific processing on the resulting possibly-overlapping clusters. In this document, based on clustering similar strings, we introduce a novel efficient technique for record linkage and entity resolution, and a novel method for correcting errors in a large number of small strings (read sequences) generated by the DNA sequencing machines.

Energy Efficiency of large Cryogenic Systems: the LHC Case and Beyond

CERN Document Server

Claudet, S; Ferlin, G; Lebrun, P; Tavian, L; Wagner, U

2013-01-01

Research infrastructures for high-energy and nuclear physics, nuclear fusion and production of high magnetic fields are increasingly based on applied superconductivity and associated cryogenics in their quest for scientific breakthroughs at affordable capital and operation costs, a condition for their acceptance and sustained funding by society. The thermodynamic penalty for operating at low temperature makes energy efficiency a key requirement for their large cryogenic systems, from conceptual design to procurement, construction and operation. Meeting this requirement takes a combined approach on several fronts in parallel: management of heat loads and sizing of cooling duties, distribution of cooling power matching the needs of the superconducting devices, efficient production of refrigeration, optimal control resting on precise instrumentation and diagnostics, as well as a targeted industrial procurement policy. The case of the Large Hadron Collider (LHC) at CERN is presented. Potential improvements for fu...

A research needs assessment: Energy efficient alternatives to chlorofluorocarbons (CFCs). Final reprot

Energy Technology Data Exchange (ETDEWEB)

1993-06-01

An assessment of the state of the art in refrigeration and insulation technologies is carried out to evaluate the potential for efficient substitutes for CFCs and HCFCs to facilitate the transition to a CFC-free environment. Opportunities for improved efficiency in domestic refrigeration, building chillers, commercial refrigeration and industrial refrigeration are evaluated. Needs for alternate refrigerants, improved components, and/or alternate cycles are identified. A summary of on-going research is presented in each area, and the potential roles of industry and government are considered. The most promising approaches for refrigeration technology fall into these categories: (1) improved vapor compressor cycles with alternate fluids, (2) Stirling cycle development and (3) advances in absorption technology. A summary of on-going research into advanced insulation, focused on vacuum -- based insulation technology refrigeration is developed. Insulation applications considered include appliances, transport refrigeration, and buildings. Specific recommendations for a long-term R&D agenda are present. The potential benefits, research, general approach, and probability of success are addressed.

SparseLeap: Efficient Empty Space Skipping for Large-Scale Volume Rendering

KAUST Repository

Hadwiger, Markus; Al-Awami, Ali K.; Beyer, Johanna; Agus, Marco; Pfister, Hanspeter

2017-01-01

Recent advances in data acquisition produce volume data of very high resolution and large size, such as terabyte-sized microscopy volumes. These data often contain many fine and intricate structures, which pose huge challenges for volume rendering, and make it particularly important to efficiently skip empty space. This paper addresses two major challenges: (1) The complexity of large volumes containing fine structures often leads to highly fragmented space subdivisions that make empty regions hard to skip efficiently. (2) The classification of space into empty and non-empty regions changes frequently, because the user or the evaluation of an interactive query activate a different set of objects, which makes it unfeasible to pre-compute a well-adapted space subdivision. We describe the novel SparseLeap method for efficient empty space skipping in very large volumes, even around fine structures. The main performance characteristic of SparseLeap is that it moves the major cost of empty space skipping out of the ray-casting stage. We achieve this via a hybrid strategy that balances the computational load between determining empty ray segments in a rasterization (object-order) stage, and sampling non-empty volume data in the ray-casting (image-order) stage. Before ray-casting, we exploit the fast hardware rasterization of GPUs to create a ray segment list for each pixel, which identifies non-empty regions along the ray. The ray-casting stage then leaps over empty space without hierarchy traversal. Ray segment lists are created by rasterizing a set of fine-grained, view-independent bounding boxes. Frame coherence is exploited by re-using the same bounding boxes unless the set of active objects changes. We show that SparseLeap scales better to large, sparse data than standard octree empty space skipping.

SparseLeap: Efficient Empty Space Skipping for Large-Scale Volume Rendering

KAUST Repository

Hadwiger, Markus

2017-08-28

Recent advances in data acquisition produce volume data of very high resolution and large size, such as terabyte-sized microscopy volumes. These data often contain many fine and intricate structures, which pose huge challenges for volume rendering, and make it particularly important to efficiently skip empty space. This paper addresses two major challenges: (1) The complexity of large volumes containing fine structures often leads to highly fragmented space subdivisions that make empty regions hard to skip efficiently. (2) The classification of space into empty and non-empty regions changes frequently, because the user or the evaluation of an interactive query activate a different set of objects, which makes it unfeasible to pre-compute a well-adapted space subdivision. We describe the novel SparseLeap method for efficient empty space skipping in very large volumes, even around fine structures. The main performance characteristic of SparseLeap is that it moves the major cost of empty space skipping out of the ray-casting stage. We achieve this via a hybrid strategy that balances the computational load between determining empty ray segments in a rasterization (object-order) stage, and sampling non-empty volume data in the ray-casting (image-order) stage. Before ray-casting, we exploit the fast hardware rasterization of GPUs to create a ray segment list for each pixel, which identifies non-empty regions along the ray. The ray-casting stage then leaps over empty space without hierarchy traversal. Ray segment lists are created by rasterizing a set of fine-grained, view-independent bounding boxes. Frame coherence is exploited by re-using the same bounding boxes unless the set of active objects changes. We show that SparseLeap scales better to large, sparse data than standard octree empty space skipping.

Application of an energy management system in combination with FMCS to high energy consuming IT industries of Taiwan

International Nuclear Information System (INIS)

Lee, Shin-Ku; Teng, Min-Cheng; Fan, Kuo-Shun; Yang, Kuan-Hsiung; Horng, Richard S.

2011-01-01

Research highlights: → A new FMCS architecture with an energy management system was developed. → The new coupling system was demonstrated feasible during in situ experiments. → A survey found that HVAC is the most energy intensive system in IT industries. → A 9.6% chiller efficiency increase and total 23.2% annual energy saving were reached. - Abstract: A commissioning unit with an energy management system (EMS) was developed to be used together with facility monitoring and control systems (FMCS). This paper describes the testing of the new coupling system, in which a detailed management program is embedded for real time control decision making. First, a survey was conducted to evaluate the current power consumption of the facility systems, and found that HVAC is the most energy intensive system. Then a case study was performed, while the plant was in operation, to demonstrate the feasibility of the new coupling system, and a 9.6% chiller efficiency increase and total 23.2% annual energy saving for the chillers were reached, by optimizing the part load ratio condition of chillers and pumps. The results from in situ experiments show that applying this energy management system to the IT industry is feasible. A better custom-made FMCS with EMS, and full scale testing to greatly increase the overall energy efficiency, is recommended.

Are large farms more efficient? Tenure security, farm size and farm efficiency: evidence from northeast China

Science.gov (United States)

Zhou, Yuepeng; Ma, Xianlei; Shi, Xiaoping

2017-04-01

How to increase production efficiency, guarantee grain security, and increase farmers' income using the limited farmland is a great challenge that China is facing. Although theory predicts that secure property rights and moderate scale management of farmland can increase land productivity, reduce farm-related costs, and raise farmer's income, empirical studies on the size and magnitude of these effects are scarce. A number of studies have examined the impacts of land tenure or farm size on productivity or efficiency, respectively. There are also a few studies linking farm size, land tenure and efficiency together. However, to our best knowledge, there are no studies considering tenure security and farm efficiency together for different farm scales in China. In addition, there is little study analyzing the profit frontier. In this study, we particularly focus on the impacts of land tenure security and farm size on farm profit efficiency, using farm level data collected from 23 villages, 811 households in Liaoning in 2015. 7 different farm scales have been identified to further represent small farms, median farms, moderate-scale farms, and large farms. Technical efficiency is analyzed with stochastic frontier production function. The profit efficiency is regressed on a set of explanatory variables which includes farm size dummies, land tenure security indexes, and household characteristics. We found that: 1) The technical efficiency scores for production efficiency (average score = 0.998) indicate that it is already very close to the production frontier, and thus there is little room to improve production efficiency. However, there is larger space to raise profit efficiency (average score = 0.768) by investing more on farm size expansion, seed, hired labor, pesticide, and irrigation. 2) Farms between 50-80 mu are most efficient from the viewpoint of profit efficiency. The so-called moderate-scale farms (100-150 mu) according to the governmental guideline show no

A thermodynamic perspective to study energy performance of vacuum-based membrane dehumidification

KAUST Repository

Bui, Thuan Duc; Kum Ja, M.; Gordon, Jeffrey M.; Ng, Kim Choon; Chua, Kian Jon

2017-01-01

In humid environments, decoupling the latent and sensible cooling loads - dehumidifying - can significantly improve chiller efficiency. Here, a basic limit for dehumidification efficiency is established from fundamental thermodynamics

High Efficiency Large-Angle Pancharatnam Phase Deflector Based on Dual Twist Design

Science.gov (United States)

2016-12-16

construction and characterization of a ±40° beam steering device with 90% diffraction efficiency based on our dual-twist design at 633nm wavelength...N. & Escuti, M. J. Achromatic Wollaston prism beam splitter using polarization gratings. Opt. Lett. 41, 4461–4463 (2016). 13. Slussarenko, S., et...High-efficiency large-angle Pancharatnam phase deflector based on dual-twist design Kun Gao1, Colin McGinty1, Harold Payson2, Shaun Berry2, Joseph

HAlign-II: efficient ultra-large multiple sequence alignment and phylogenetic tree reconstruction with distributed and parallel computing.

Science.gov (United States)

Wan, Shixiang; Zou, Quan

2017-01-01

Multiple sequence alignment (MSA) plays a key role in biological sequence analyses, especially in phylogenetic tree construction. Extreme increase in next-generation sequencing results in shortage of efficient ultra-large biological sequence alignment approaches for coping with different sequence types. Distributed and parallel computing represents a crucial technique for accelerating ultra-large (e.g. files more than 1 GB) sequence analyses. Based on HAlign and Spark distributed computing system, we implement a highly cost-efficient and time-efficient HAlign-II tool to address ultra-large multiple biological sequence alignment and phylogenetic tree construction. The experiments in the DNA and protein large scale data sets, which are more than 1GB files, showed that HAlign II could save time and space. It outperformed the current software tools. HAlign-II can efficiently carry out MSA and construct phylogenetic trees with ultra-large numbers of biological sequences. HAlign-II shows extremely high memory efficiency and scales well with increases in computing resource. THAlign-II provides a user-friendly web server based on our distributed computing infrastructure. HAlign-II with open-source codes and datasets was established at http://lab.malab.cn/soft/halign.

High-efficiency wavefunction updates for large scale Quantum Monte Carlo

Science.gov (United States)

Kent, Paul; McDaniel, Tyler; Li, Ying Wai; D'Azevedo, Ed

Within ab intio Quantum Monte Carlo (QMC) simulations, the leading numerical cost for large systems is the computation of the values of the Slater determinants in the trial wavefunctions. The evaluation of each Monte Carlo move requires finding the determinant of a dense matrix, which is traditionally iteratively evaluated using a rank-1 Sherman-Morrison updating scheme to avoid repeated explicit calculation of the inverse. For calculations with thousands of electrons, this operation dominates the execution profile. We propose a novel rank- k delayed update scheme. This strategy enables probability evaluation for multiple successive Monte Carlo moves, with application of accepted moves to the matrices delayed until after a predetermined number of moves, k. Accepted events grouped in this manner are then applied to the matrices en bloc with enhanced arithmetic intensity and computational efficiency. This procedure does not change the underlying Monte Carlo sampling or the sampling efficiency. For large systems and algorithms such as diffusion Monte Carlo where the acceptance ratio is high, order of magnitude speedups can be obtained on both multi-core CPU and on GPUs, making this algorithm highly advantageous for current petascale and future exascale computations.

Memory Efficient PCA Methods for Large Group ICA.

Science.gov (United States)

Rachakonda, Srinivas; Silva, Rogers F; Liu, Jingyu; Calhoun, Vince D

2016-01-01

Principal component analysis (PCA) is widely used for data reduction in group independent component analysis (ICA) of fMRI data. Commonly, group-level PCA of temporally concatenated datasets is computed prior to ICA of the group principal components. This work focuses on reducing very high dimensional temporally concatenated datasets into its group PCA space. Existing randomized PCA methods can determine the PCA subspace with minimal memory requirements and, thus, are ideal for solving large PCA problems. Since the number of dataloads is not typically optimized, we extend one of these methods to compute PCA of very large datasets with a minimal number of dataloads. This method is coined multi power iteration (MPOWIT). The key idea behind MPOWIT is to estimate a subspace larger than the desired one, while checking for convergence of only the smaller subset of interest. The number of iterations is reduced considerably (as well as the number of dataloads), accelerating convergence without loss of accuracy. More importantly, in the proposed implementation of MPOWIT, the memory required for successful recovery of the group principal components becomes independent of the number of subjects analyzed. Highly efficient subsampled eigenvalue decomposition techniques are also introduced, furnishing excellent PCA subspace approximations that can be used for intelligent initialization of randomized methods such as MPOWIT. Together, these developments enable efficient estimation of accurate principal components, as we illustrate by solving a 1600-subject group-level PCA of fMRI with standard acquisition parameters, on a regular desktop computer with only 4 GB RAM, in just a few hours. MPOWIT is also highly scalable and could realistically solve group-level PCA of fMRI on thousands of subjects, or more, using standard hardware, limited only by time, not memory. Also, the MPOWIT algorithm is highly parallelizable, which would enable fast, distributed implementations ideal for big

Memory efficient PCA methods for large group ICA

Directory of Open Access Journals (Sweden)

Srinivas eRachakonda

2016-02-01

Full Text Available Principal component analysis (PCA is widely used for data reduction in group independent component analysis (ICA of fMRI data. Commonly, group-level PCA of temporally concatenated datasets is computed prior to ICA of the group principal components. This work focuses on reducing very high dimensional temporally concatenated datasets into its group PCA space. Existing randomized PCA methods can determine the PCA subspace with minimal memory requirements and, thus, are ideal for solving large PCA problems. Since the number of dataloads is not typically optimized, we extend one of these methods to compute PCA of very large datasets with a minimal number of dataloads. This method is coined multi power iteration (MPOWIT. The key idea behind MPOWIT is to estimate a subspace larger than the desired one, while checking for convergence of only the smaller subset of interest. The number of iterations is reduced considerably (as well as the number of dataloads, accelerating convergence without loss of accuracy. More importantly, in the proposed implementation of MPOWIT, the memory required for successful recovery of the group principal components becomes independent of the number of subjects analyzed. Highly efficient subsampled eigenvalue decomposition techniques are also introduced, furnishing excellent PCA subspace approximations that can be used for intelligent initialization of randomized methods such as MPOWIT. Together, these developments enable efficient estimation of accurate principal components, as we illustrate by solving a 1600-subject group-level PCA of fMRI with standard acquisition parameters, on a regular desktop computer with only 4GB RAM, in just a few hours. MPOWIT is also highly scalable and could realistically solve group-level PCA of fMRI on thousands of subjects, or more, using standard hardware, limited only by time, not memory. Also, the MPOWIT algorithm is highly parallelizable, which would enable fast, distributed implementations

Measuring the efficiency of large pharmaceutical companies: an industry analysis.

Science.gov (United States)

Gascón, Fernando; Lozano, Jesús; Ponte, Borja; de la Fuente, David

2017-06-01

This paper evaluates the relative efficiency of a sample of 37 large pharmaceutical laboratories in the period 2008-2013 using a data envelopment analysis (DEA) approach. We describe in detail the procedure followed to select and construct relevant inputs and outputs that characterize the production and innovation activity of these pharmaceutical firms. Models are estimated with financial information from Datastream, including R&D investment, and the number of new drugs authorized by the European Medicines Agency (EMA) and the US Food and Drug Administration (FDA) considering the time effect. The relative performances of these firms-taking into consideration the strategic importance of R&D-suggest that the pharmaceutical industry is a highly competitive sector given that there are many laboratories at the efficient frontier and many inefficient laboratories close to this border. Additionally, we use data from S&P Capital IQ to analyze 2071 financial transactions announced by our sample of laboratories as an alternative way to gain access to new drugs, and we link these transactions with R&D investment and DEA efficiency. We find that efficient laboratories make on average more financial transactions, and the relative size of each transaction is larger. However, pharmaceutical companies that simultaneously are more efficient and invest more internally in R&D announce smaller transactions relative to total assets.

Optimizing Performance of a Thermal Energy Storage System

Science.gov (United States)

Subirats Soler, Monica

In this thesis, the problem of electricity demand shifting for the cooling needs of a large institution using a thermal energy storage (TES) tank is considered. The system is formed by electric chillers, cooling towers and a TES tank that can store energy for the cooling demand of most days, but not for the hottest ones. The goal is to supply all the cooling needed while minimizing the cost. This is done by shifting the cooling demand to night and early morning hours, when electricity is cheaper and due to lower temperatures, the chillers work more efficiently. This is all done with the help of the TES tank, that acts as a buffer storing chilled water. After a series of assumptions and simplifications, the cost function becomes convex and thus a minimum solution exists. However, from previous work only the chillers were considered, omitting the negative effect that other components of the system, such as cooling towers, had on the overall cost of operation. Using data from the operation of the power plant under real conditions, a method to model the whole system is presented in this thesis. In addition, the algorithm relied on the knowledge of an accurate prediction of the cooling demand, which obviously is not known in advance. A method to predict it starting from a forecasting of the temperature is presented. Finally, the algorithm can be easily modified to allow the imposition constraints that limit the maximum power use of chillers, during specific periods, in response to the overall needs of the micro-grid.

Survey State of the Art: Electrical Load Management Techniques and Equipment.

Science.gov (United States)

1986-10-31

setback 0 Sequenced start-up 0 Duty cycling 0 Holiday scheduling %~. Load shedding 0 Chiller control Optimized start-stop e Boiler control Cf Enthalpy...efficiency fac- and a local 80 column serial printer. tors, building loss factors, occupancy temperature setpoint and history. The optimized start and/or...capilt, water temperature, number of chillers optimal sarut-up of heating and cool- running and the percent operating lev . ing equipment can be

Development and analysis of sustainable energy systems for building HVAC applications

International Nuclear Information System (INIS)

Khalid, F.; Dincer, I.; Rosen, M.A.

2015-01-01

The main HVAC applications considered in this paper are heating and cooling. Three newly developed systems for heating and cooling applications in buildings are proposed and assessed. Energy and exergy analyses are performed to assess the performance of heating, cooling and overall systems for each case, and the effects of various parameters on the energy and exergy efficiencies are examined. Also, the effect of changing the energy input for each system is also found in terms of overall efficiency. The overall system energy efficiency is found to be highest for the natural gas operated system with a vapour absorption chiller (system 1) at 27.5% and lowest for the photovoltaic (PV) and solar thermal operated system with vapour compression chiller (system 3) at 19.9%. The overall system exergy efficiency is found to be highest for the PV and solar thermal operated system with vapour compression chiller (system 3) at 3.9% and lowest for the PV and solar thermal operated system with heat pump (system 2) at 1.2%, respectively. - Highlights: • Three HVAC systems for buildings using renewable energy sources are proposed and assessed. • A performance improvement study is undertaken. • Parametric studies are carried out to determine the effects of various parameters on energy and exergy efficiencies

Effect of the switching time on the performance of an adsorption chiller

International Nuclear Information System (INIS)

Hong, Sang Woo; Chung, Jae Dong; Kwon, Oh Kyung

2016-01-01

The switching time is an important operating condition that must be correctly anticipated for an effective adsorption cooling system. Before the adsorption (or desorption) process begins, time is required to cool down (or heat up) the bed temperature so that the bed pressure reaches the evaporator pressure (or condenser pressure). During the switching time, the supplied heat is reduced and pressure overload conditions can be avoided. The switching time cannot be estimated early on, and an improper switching time degrades the system performance. Thus, this study provides guideline with which to determine the required time to open this valve, i.e., the switching time, and carefully examines the thermo-physical behavior in the adsorption bed during this period. A two-dimensional numerical method with the composite sorbent of SWS-1L and a water pair is applied to a fin-tube type adsorption chiller. Three cases of no switching time, the optimal switching time and a double the optimal switching time are examined. The results show that no consideration of the switching time overestimates the performance of the adsorption cooling system in terms of the Coefficient of performance (COP) and the Specific cooling power (SCP). On the other hand, if the switching time exceeds the optimal value, the performance of the adsorption cooling system is also reduced compared to that when using the optimal switching time. The dependency of the optimal switching times on various design parameters, such as the fin pitch, fin height and heating temperature, is also examined.

Effect of the switching time on the performance of an adsorption chiller

Energy Technology Data Exchange (ETDEWEB)

Hong, Sang Woo; Chung, Jae Dong [Sejong University, Seoul (Korea, Republic of); Kwon, Oh Kyung [Korea Institute of Industrial Technology, Chonan (Korea, Republic of)

2016-05-15

The switching time is an important operating condition that must be correctly anticipated for an effective adsorption cooling system. Before the adsorption (or desorption) process begins, time is required to cool down (or heat up) the bed temperature so that the bed pressure reaches the evaporator pressure (or condenser pressure). During the switching time, the supplied heat is reduced and pressure overload conditions can be avoided. The switching time cannot be estimated early on, and an improper switching time degrades the system performance. Thus, this study provides guideline with which to determine the required time to open this valve, i.e., the switching time, and carefully examines the thermo-physical behavior in the adsorption bed during this period. A two-dimensional numerical method with the composite sorbent of SWS-1L and a water pair is applied to a fin-tube type adsorption chiller. Three cases of no switching time, the optimal switching time and a double the optimal switching time are examined. The results show that no consideration of the switching time overestimates the performance of the adsorption cooling system in terms of the Coefficient of performance (COP) and the Specific cooling power (SCP). On the other hand, if the switching time exceeds the optimal value, the performance of the adsorption cooling system is also reduced compared to that when using the optimal switching time. The dependency of the optimal switching times on various design parameters, such as the fin pitch, fin height and heating temperature, is also examined.

A novel highly efficient grating coupler with large filling factor used for optoelectronic integration

International Nuclear Information System (INIS)

Zhou Liang; Li Zhi-Yong; Zhu Yu; Li Yun-Tao; Yu Yu-De; Yu Jin-Zhong; Fan Zhong-Cao; Han Wei-Hua

2010-01-01

A novel highly efficient grating coupler with large filling factor and deep etching is proposed in silicon-on-insulator for near vertical coupling between the rib waveguide and optical fibre. The deep slots acting as high efficient scattering centres are analysed and optimized. As high as 60% coupling efficiency at telecom wavelength of 1550-nm and 3-dB bandwidth of 61 nm are predicted by simulation. A peak coupling efficiency of 42.1% at wavelength 1546-nm and 3-dB bandwidth of 37.6 nm are obtained experimentally. (classical areas of phenomenology)

Time-Efficient Cloning Attacks Identification in Large-Scale RFID Systems

Directory of Open Access Journals (Sweden)

Ju-min Zhao

2017-01-01

Full Text Available Radio Frequency Identification (RFID is an emerging technology for electronic labeling of objects for the purpose of automatically identifying, categorizing, locating, and tracking the objects. But in their current form RFID systems are susceptible to cloning attacks that seriously threaten RFID applications but are hard to prevent. Existing protocols aimed at detecting whether there are cloning attacks in single-reader RFID systems. In this paper, we investigate the cloning attacks identification in the multireader scenario and first propose a time-efficient protocol, called the time-efficient Cloning Attacks Identification Protocol (CAIP to identify all cloned tags in multireaders RFID systems. We evaluate the performance of CAIP through extensive simulations. The results show that CAIP can identify all the cloned tags in large-scale RFID systems fairly fast with required accuracy.

Analyzing price and efficiency dynamics of large appliances with the experience curve approach

International Nuclear Information System (INIS)

Weiss, Martin; Patel, Martin K.; Junginger, Martin; Blok, Kornelis

2010-01-01

Large appliances are major power consumers in households of industrialized countries. Although their energy efficiency has been increasing substantially in past decades, still additional energy efficiency potentials exist. Energy policy that aims at realizing these potentials faces, however, growing concerns about possible adverse effects on commodity prices. Here, we address these concerns by applying the experience curve approach to analyze long-term price and energy efficiency trends of three wet appliances (washing machines, laundry dryers, and dishwashers) and two cold appliances (refrigerators and freezers). We identify a robust long-term decline in both specific price and specific energy consumption of large appliances. Specific prices of wet appliances decline at learning rates (LR) of 29±8% and thereby much faster than those of cold appliances (LR of 9±4%). Our results demonstrate that technological learning leads to substantial price decline, thus indicating that the introduction of novel and initially expensive energy efficiency technologies does not necessarily imply adverse price effects in the long term. By extending the conventional experience curve approach, we find a steady decline in the specific energy consumption of wet appliances (LR of 20-35%) and cold appliances (LR of 13-17%). Our analysis suggests that energy policy might be able to bend down energy experience curves. (author)

Energy efficiency improving opportunities in a large Chinese shoe-making enterprise

International Nuclear Information System (INIS)

Ming Yang

2010-01-01

Energy consumption and energy intensity reduction opportunities are quite different from one enterprise to another. It is necessary to understand how much energy is used at individual enterprise, where the most energy is consumed and what the best opportunities are to invest in energy efficiency. Auditing energy efficiency was recently undertaken in one of the top 1000 largest Chinese enterprises. The objectives of this paper are to fill a gap in the literature of auditing energy efficiency for a Chinese manufacturing enterprise and to share the audited energy efficiency results. This paper concludes that if the enterprise invests USD 1.9 million to improve energy efficiency, the investment will be recovered in about 18 months. The net present value of the investment would be about USD 9.8 million at a discount rate of 12%. The investment will reduce a large amount of energy consumption at the enterprise based on its figures in 2008, including 15% of electricity, 40% of fuel oil, and 54% of diesel. Carbon reduction is also very cost-effective. Investment of one dollar in the enterprise will help cut carbon emission by 7.95 kg per year and generate $5.3 net revenue in the economic lifetime of the invested technology.

Efficient Approach for Harmonic Resonance Identification of Large Wind Power Plants

DEFF Research Database (Denmark)

Ebrahimzadeh, Esmaeil; Blaabjerg, Frede; Wang, Xiongfei

2016-01-01

Unlike conventional power systems where the resonance frequencies are mainly determined by the passive components parameters, large Wind Power Plants (WPPs) may introduce additional harmonic resonances because of the interactions of the wideband control systems of power converters with each other...... and with passive components. This paper presents an efficient approach for identification of harmonic resonances in large WPPs containing power electronic converters, cable, transformer, capacitor banks, shunt reactors, etc. The proposed approach introduces a large WPP as a Multi-Input Multi-Output (MIMO) control...... system by considering the linearized models of the inner control loops of grid-side converters. Therefore, the resonance frequencies of the WPP resulting from passive components and the control loop interactions are identified based on the determinant of the transfer function matrix of the introduced...

Efficient Partitioning of Large Databases without Query Statistics

Directory of Open Access Journals (Sweden)

Shahidul Islam KHAN

2016-11-01

Full Text Available An efficient way of improving the performance of a database management system is distributed processing. Distribution of data involves fragmentation or partitioning, replication, and allocation process. Previous research works provided partitioning based on empirical data about the type and frequency of the queries. These solutions are not suitable at the initial stage of a distributed database as query statistics are not available then. In this paper, I have presented a fragmentation technique, Matrix based Fragmentation (MMF, which can be applied at the initial stage as well as at later stages of distributed databases. Instead of using empirical data, I have developed a matrix, Modified Create, Read, Update and Delete (MCRUD, to partition a large database properly. Allocation of fragments is done simultaneously in my proposed technique. So using MMF, no additional complexity is added for allocating the fragments to the sites of a distributed database as fragmentation is synchronized with allocation. The performance of a DDBMS can be improved significantly by avoiding frequent remote access and high data transfer among the sites. Results show that proposed technique can solve the initial partitioning problem of large distributed databases.

Efficient Selection of Multiple Objects on a Large Scale

DEFF Research Database (Denmark)

Stenholt, Rasmus

2012-01-01

The task of multiple object selection (MOS) in immersive virtual environments is important and still largely unexplored. The diffi- culty of efficient MOS increases with the number of objects to be selected. E.g. in small-scale MOS, only a few objects need to be simultaneously selected. This may...... consuming. Instead, we have implemented and tested two of the existing approaches to 3-D MOS, a brush and a lasso, as well as a new technique, a magic wand, which automati- cally selects objects based on local proximity to other objects. In a formal user evaluation, we have studied how the performance...

High convergence efficiency design of flat Fresnel lens with large aperture

Science.gov (United States)

Ke, Jieyao; Zhao, Changming; Guan, Zhe

2018-01-01

This paper designed a circle-shaped Fresnel lens with large aperture as part of the solar pumped laser design project. The Fresnel lens designed in this paper simulate in size 1000mm×1000mm, focus length 1200mm and polymethyl methacrylate (PMMA) material in order to conduct high convergence efficiency. In the light of design requirement of concentric ring with same width of 0.3mm, this paper proposed an optimized Fresnel lens design based on previous sphere design and conduct light tracing simulation in Matlab. This paper also analyzed the effect of light spot size, light intensity distribution, optical efficiency under four conditions, monochromatic parallel light, parallel spectrum light, divergent monochromatic light and sunlight. Design by 550nm wavelength and under the condition of Fresnel reflection, the results indicated that the designed lens could convergent sunlight in diffraction limit of 11.8mm with a 78.7% optical efficiency, better than the sphere cutting design results of 30.4%.

Waste heat recovery options in a large gas-turbine combined power plant

Science.gov (United States)

Upathumchard, Ularee

This study focuses on power plant heat loss and how to utilize the waste heat in energy recovery systems in order to increase the overall power plant efficiency. The case study of this research is a 700-MW natural gas combined cycle power plant, located in a suburban area of Thailand. An analysis of the heat loss of the combustion process, power generation process, lubrication system, and cooling system has been conducted to evaluate waste heat recovery options. The design of the waste heat recovery options depends to the amount of heat loss from each system and its temperature. Feasible waste heat sources are combustion turbine (CT) room ventilation air and lubrication oil return from the power plant. The following options are being considered in this research: absorption chillers for cooling with working fluids Ammonia-Water and Water-Lithium Bromide (in comparison) and Organic Rankine Cycle (ORC) with working fluids R134a and R245fa. The absorption cycles are modeled in three different stages; single-effect, double-effect and half-effect. ORC models used are simple ORC as a baseline, ORC with internal regenerator, ORC two-phase flash expansion ORC and ORC with multiple heat sources. Thermodynamic models are generated and each system is simulated using Engineering Equation Solver (EES) to define the most suitable waste heat recovery options for the power plant. The result will be synthesized and evaluated with respect to exergy utilization efficiency referred as the Second Law effectiveness and net output capacity. Results of the models give recommendation to install a baseline ORC of R134a and a double-effect water-lithium bromide absorption chiller, driven by ventilation air from combustion turbine compartment. The two technologies yield reasonable economic payback periods of 4.6 years and 0.7 years, respectively. The fact that this selected power plant is in its early stage of operation allows both models to economically and effectively perform waste heat

Efficient reanalysis of structures by a direct modification method. [local stiffness modifications of large structures

Science.gov (United States)

Raibstein, A. I.; Kalev, I.; Pipano, A.

1976-01-01

A procedure for the local stiffness modifications of large structures is described. It enables structural modifications without an a priori definition of the changes in the original structure and without loss of efficiency due to multiple loading conditions. The solution procedure, implemented in NASTRAN, involved the decomposed stiffness matrix and the displacement vectors of the original structure. It solves the modified structure exactly, irrespective of the magnitude of the stiffness changes. In order to investigate the efficiency of the present procedure and to test its applicability within a design environment, several real and large structures were solved. The results of the efficiency studies indicate that the break-even point of the procedure varies between 8% and 60% stiffness modifications, depending upon the structure's characteristics and the options employed.

Efficient Similarity Search Using the Earth Mover's Distance for Large Multimedia Databases

DEFF Research Database (Denmark)

Assent, Ira; Wichterich, Marc; Meisen, Tobias

2008-01-01

Multimedia similarity search in large databases requires efficient query processing. The Earth mover's distance, introduced in computer vision, is successfully used as a similarity model in a number of small-scale applications. Its computational complexity hindered its adoption in large multimedia...... databases. We enable directly indexing the Earth mover's distance in structures such as the R-tree and the VA-file by providing the accurate 'MinDist' function to any bounding rectangle in the index. We exploit the computational structure of the new MinDist to derive a new lower bound for the EMD Min...

The Role of Absorption Cooling for Reaching Sustainable Energy Systems

Energy Technology Data Exchange (ETDEWEB)

Lindmark, Susanne

2005-07-01

This thesis focuses on the role and potential of absorption cooling in future energy systems. Two types of energy systems are investigated: a district energy system based on waste incineration and a distributed energy system with natural gas as fuel. In both cases, low temperature waste heat is used as driving energy for the absorption cooling. The main focus is to evaluate the absorption technology in an environmental perspective, in terms of reduced CO{sub 2} emissions. Economic evaluations are also performed. The reduced electricity when using absorption cooling instead of compression cooling is quantified and expressed as an increased net electrical yield. The results show that absorption cooling is an environmentally friendly way to produce cooling as it reduces the use of electrically driven cooling in the energy system and therefore also reduces global CO{sub 2} emissions. In the small-scale trigeneration system the electricity use is lowered with 84 % as compared to cooling production with compression chillers only. The CO{sub 2} emissions can be lowered to 45 CO{sub 2}/MWh{sub c} by using recoverable waste heat as driving heat for absorption chillers. However, the most cost effective cooling solution in a district energy system is a combination between absorption and compression cooling technologies according to the study. Absorption chillers have the potential to be suitable bottoming cycles for power production in distributed systems. Net electrical yields over 55 % may be reached in some cases with gas motors and absorption chillers. This small-scale system for cogeneration of power and cooling shows electrical efficiencies comparable to large-scale power plants and may contribute to reducing peak electricity demand associated with the cooling demand.

Large-scale cauliflower-shaped hierarchical copper nanostructures for efficient photothermal conversion

Science.gov (United States)

Fan, Peixun; Wu, Hui; Zhong, Minlin; Zhang, Hongjun; Bai, Benfeng; Jin, Guofan

2016-07-01

Efficient solar energy harvesting and photothermal conversion have essential importance for many practical applications. Here, we present a laser-induced cauliflower-shaped hierarchical surface nanostructure on a copper surface, which exhibits extremely high omnidirectional absorption efficiency over a broad electromagnetic spectral range from the UV to the near-infrared region. The measured average hemispherical absorptance is as high as 98% within the wavelength range of 200-800 nm, and the angle dependent specular reflectance stays below 0.1% within the 0-60° incident angle. Such a structured copper surface can exhibit an apparent heating up effect under the sunlight illumination. In the experiment of evaporating water, the structured surface yields an overall photothermal conversion efficiency over 60% under an illuminating solar power density of ~1 kW m-2. The presented technology provides a cost-effective, reliable, and simple way for realizing broadband omnidirectional light absorptive metal surfaces for efficient solar energy harvesting and utilization, which is highly demanded in various light harvesting, anti-reflection, and photothermal conversion applications. Since the structure is directly formed by femtosecond laser writing, it is quite suitable for mass production and can be easily extended to a large surface area.Efficient solar energy harvesting and photothermal conversion have essential importance for many practical applications. Here, we present a laser-induced cauliflower-shaped hierarchical surface nanostructure on a copper surface, which exhibits extremely high omnidirectional absorption efficiency over a broad electromagnetic spectral range from the UV to the near-infrared region. The measured average hemispherical absorptance is as high as 98% within the wavelength range of 200-800 nm, and the angle dependent specular reflectance stays below 0.1% within the 0-60° incident angle. Such a structured copper surface can exhibit an apparent

Dual fan, dual-duct system meets air quality, energy-efficiency needs

Energy Technology Data Exchange (ETDEWEB)

Schuler, M. [Pageau Morel and Associates, Montreal, Quebec (Canada)

1996-03-01

Canada`s Space Centre in Saint-Hubert Quebec is a 300,000 ft{sup 2} (27,871 m{sup 2}) complex that houses the headquarters of the Canadian Space Agency, the Canadian Astronaut Training Centre, mission ground control installations, research facilities, offices and the required support facilities. A comfortable, pleasant research environment was a primary concern for the Space Centre, given its elite clientele. The objectives were high indoor-air quality, design flexibility, energy efficiency and low capital costs. Dual duct systems which are the heart of the mechanical concept allowed the designers to meet these objectives. The Space Centre`s offices, laboratories and conference center are all served by dual-duct systems. All operate using an air economizer cycle. Gas boilers provide them with hot water for heating and steam for humidification while centrifugal chillers provide chilled water for cooling. This article describes the design.

Experimental results and thermodynamic analysis of a natural gas small scale cogeneration plant for power and refrigeration purposes

International Nuclear Information System (INIS)

Bazzo, Edson; Nacif de Carvalho, Alvaro; Matelli, José Alexandre

2013-01-01

In this work, experimental results are reported for a small scale cogeneration plant for power and refrigeration purposes. The plant includes a natural gas microturbine and an ammonia/water absorption chiller fired by steam. The system was tested under different turbine loads, steam pressures and chiller outlet temperatures. An evaluation based on the 1st and 2nd Laws of Thermodynamics was also performed. For the ambient temperature around 24 °C and microturbine at full load, the plant is able to provide 19 kW of saturated steam at 5.3 bar (161 °C), corresponding to 9.2 kW of refrigeration at −5 °C (COP = 0.44). From a 2nd law point-of-view, it was found that there is an optimal chiller outlet temperature that maximizes the chiller exergetic efficiency. As expected, the microturbine presented the highest irreversibilities, followed by the absorption chiller and the HRSG. In order to reduce the plant exergy destruction, it is recommended a new design for the HRSG and a new insulation for the exhaust pipe. -- Highlights: • A small scale cogeneration plant for power and refrigeration is proposed and analyzed. • The plant is based on a microturbine and a modified absorption chiller. • The plant is analysed based on 1st and 2nd laws of thermodynamics. • Experimental results are found for different power and refrigeration conditions. • The plant proved to be technically feasible

A combined sustainability index for electricity efficiency measures

International Nuclear Information System (INIS)

Goldrath, T.; Ayalon, O.; Shechter, M.

2015-01-01

One of the most substantial tools that serve decision makers in their efforts to reduce greenhouse gas emissions includes energy efficiency measures that in most cases benefit from governmental assistance for achieving electricity consumption reduction goals. This paper examines five energy efficiency measures, defining a combined sustainability index. A multi-criteria analysis of five predefined indices was developed (economic, environmental, technology, social and political), providing a combined index for each measure and a tool for identifying the preferred measure within a specific situation, based on its total sustainability score. In this research, a case study was conducted and the preferred measure was found to be municipal street lighting systems, based on its high political and social scores, and its relatively high installation potential. The second choice would be replacement of chillers in the industrial sector, and the least favorable measure is the replacement of water pumps in the water sector. The methodology described brings into account the technological specifications of the measure implemented, and the specific national conditions under which it is implemented. - Highlights: • A MCDA of five indices was developed to define a combined sustainability index. • Criteria defined were environment, technology, economy, social and political. • Five energy efficiency measures were rated, based on their total sustainability score. • Measures were in five main electricity consumption sectors. • The preferred measure found in the case study was municipal street lighting systems.

The design of integrated cooling processes in district heating systems; Kylprocessers design i fjaerrvaermesystem

Energy Technology Data Exchange (ETDEWEB)

Martin, Viktoria [Royal Inst. of Technology, Stockholm (SE). Dept. of Chemical Engineering and Technology; Setterwall, Fredrik [Fredrik Setterwall Konsult AB, Sollentuna (Sweden); Andersson, Mikael [AB Berglunds Rostfria, Boden (Sweden)

2005-07-01

This report presents the results from an investigation regarding the design of integrated cooling processes in district heating systems. Increasing investment levels in district heating networks combined with expanding comfort cooling demand makes heat-driven cooling processes extremely interesting. This solution has a great potential tbe cost effective. At the same time, the problem with the environmentally harmful refrigerants used in conventional vapor compression chillers is avoided. In many cases it is beneficial for the district heating provider to lower the supply and/or return temperatures in the network, at least for part of the year. In combined heat and power generation (CHP) a lower supply temperature means that the electricity yield increases. In this context, it is important to consider that conventional absorption chillers are designed to run on 120 deg C heat. However,they can work on heat with temperature as low as 80 deg C if a chiller with a large enough generator area is used, although this has a negative impact on the dimensions of other components and leads ta lower coefficient of performance. For these reasons low temperature driven absorption chillers have been developed in recent years. Two concepts (from different manufacturers) are now available on the market. Factors that affect the choice of district heat-integrated cooling processes have been investigated in this study. Key system aspects that embody a holistic view on the production of heating, cooling and power are especially highlighted. Important tasks have been: To quantify the following effects on the design of an integrated cooling process: the temperatures in the district heating net, available cooling water temperature (to cool the absorber and condenser), electricity price, and the composition of the energy system (e.g. fuel and CHP or power-only mode of operation). To analyze the potential of the low temperature driven chiller concept with regards to energy and cost

Numerical simulation of bubbles motion in lifting pipe of bubble pump for lithium bromide absorption chillers

International Nuclear Information System (INIS)

Gao, Hongtao; Liu, Bingbing; Yan, Yuying

2017-01-01

A bubble pump is proposed to replace the traditional mechanical solution pump in lithium bromide absorption chillers, for its advantageous feature that can be driven by industrial waste heat or solar energy or other low-grade energy. In two-stage bubble pump driven lithium bromide absorption refrigeration system, flow patterns in lifting pipe have significant effects on the performance of bubble pump. In this paper, the single bubble motion and the double bubbles coalescence in vertical ascending pipe are simulated by an improved free energy model of lattice Boltzmann method, in which the two-phase liquid to gas density ratio is 2778. The details of bubbles coalescence process are studied. Density and velocity of bubbles have been obtained. The computational results show that the initial radius of each bubble has a great influence on the coalescence time. The larger the initial bubble radius, the shorter the coalescence time. The pipe diameter has a little effect on the two bubbles coalescence time while it has a significant effect on the bubble velocity. As the pipe diameter increases, the bubble velocity increases. The obtained results are helpful for studying the transition mechanisms of two-phase flow patterns and useful for improving the bubble pump performance by controlling the flow patterns in lifting pipe.

Statistically and Computationally Efficient Estimating Equations for Large Spatial Datasets

KAUST Repository

Sun, Ying; Stein, Michael L.

2014-01-01

For Gaussian process models, likelihood based methods are often difficult to use with large irregularly spaced spatial datasets, because exact calculations of the likelihood for n observations require O(n3) operations and O(n2) memory. Various approximation methods have been developed to address the computational difficulties. In this paper, we propose new unbiased estimating equations based on score equation approximations that are both computationally and statistically efficient. We replace the inverse covariance matrix that appears in the score equations by a sparse matrix to approximate the quadratic forms, then set the resulting quadratic forms equal to their expected values to obtain unbiased estimating equations. The sparse matrix is constructed by a sparse inverse Cholesky approach to approximate the inverse covariance matrix. The statistical efficiency of the resulting unbiased estimating equations are evaluated both in theory and by numerical studies. Our methods are applied to nearly 90,000 satellite-based measurements of water vapor levels over a region in the Southeast Pacific Ocean.

Statistically and Computationally Efficient Estimating Equations for Large Spatial Datasets

KAUST Repository

Sun, Ying

2014-11-07

For Gaussian process models, likelihood based methods are often difficult to use with large irregularly spaced spatial datasets, because exact calculations of the likelihood for n observations require O(n3) operations and O(n2) memory. Various approximation methods have been developed to address the computational difficulties. In this paper, we propose new unbiased estimating equations based on score equation approximations that are both computationally and statistically efficient. We replace the inverse covariance matrix that appears in the score equations by a sparse matrix to approximate the quadratic forms, then set the resulting quadratic forms equal to their expected values to obtain unbiased estimating equations. The sparse matrix is constructed by a sparse inverse Cholesky approach to approximate the inverse covariance matrix. The statistical efficiency of the resulting unbiased estimating equations are evaluated both in theory and by numerical studies. Our methods are applied to nearly 90,000 satellite-based measurements of water vapor levels over a region in the Southeast Pacific Ocean.

Exergy efficiency enhancement of MSF desalination by heat recovery from hot distillate water stages

International Nuclear Information System (INIS)

Al-Weshahi, Mohammed A.; Anderson, Alexander; Tian, Guohong

2013-01-01

This detailed exergy analysis of a 3800 m 3 /h Multi-Stage Flash (MSF) desalination plant is based on the latest published thermodynamics properties of water and seawater. The parameters of the study were extracted from a validated model of MSF desalination using IPSEpro software. The results confirmed that the overall exergy efficiency of the unit is lower than would be desirable at only 5.8%. Exergy inputs were destroyed by 55%, 17%, 10%, 4.3%, and 14% respectively, in the heat recovery stages, brine heater, heat rejection stages, pumps and brine streams disposal. Moreover, the detail of the study showed that the lowest exergy destruction occurs in the first stage, increasing gradually in heat recovery stages and sharply in heat rejection stages. The study concludes that recovering the heat from the hot distillate water stages can improve unit exergy efficiency from its low 5.8% to a more economical 14%, with the hot water parameters suitable for powering other thermal systems such as absorption chiller and multi-effect desalination

The application of fuzzy control on energy saving for multi-unit room air-conditioners

International Nuclear Information System (INIS)

Chiou, C.B.; Chiou, C.H.; Chu, C.M.; Lin, S.L.

2009-01-01

Most research, on energy saving methods for air-conditioners have focused on large chillers as its subject. As most school offices, laboratories, and classrooms are equipped with unitary systems for air-conditioning, this paper discusses methods for energy savings with regard to unitary systems. This paper will put forward the fuzzy temperature control method for multi-unit air-conditioners to enhance energy efficiency. The results show that the use of fuzzy control is efficient for energy saving as well as causing temperature control be steadier, even if there is a change to the thermal loading, the fuzzy control system is able to control the air-conditioning in stable conditions

Quantum Monte Carlo for large chemical systems: implementing efficient strategies for peta scale platforms and beyond

International Nuclear Information System (INIS)

Scemama, Anthony; Caffarel, Michel; Oseret, Emmanuel; Jalby, William

2013-01-01

Various strategies to implement efficiently quantum Monte Carlo (QMC) simulations for large chemical systems are presented. These include: (i) the introduction of an efficient algorithm to calculate the computationally expensive Slater matrices. This novel scheme is based on the use of the highly localized character of atomic Gaussian basis functions (not the molecular orbitals as usually done), (ii) the possibility of keeping the memory footprint minimal, (iii) the important enhancement of single-core performance when efficient optimization tools are used, and (iv) the definition of a universal, dynamic, fault-tolerant, and load-balanced framework adapted to all kinds of computational platforms (massively parallel machines, clusters, or distributed grids). These strategies have been implemented in the QMC-Chem code developed at Toulouse and illustrated with numerical applications on small peptides of increasing sizes (158, 434, 1056, and 1731 electrons). Using 10-80 k computing cores of the Curie machine (GENCI-TGCC-CEA, France), QMC-Chem has been shown to be capable of running at the peta scale level, thus demonstrating that for this machine a large part of the peak performance can be achieved. Implementation of large-scale QMC simulations for future exa scale platforms with a comparable level of efficiency is expected to be feasible. (authors)

Heat Driven Cooling in District Energy Systems; Vaermedriven Kyla

Energy Technology Data Exchange (ETDEWEB)

Rydstrand, Magnus; Martin, Viktoria; Westermark, Mats [Royal Inst. of Technology, Stockholm (Sweden). Dept. of Chemical Engineering and Technology

2004-07-01

This report is reviewing different heat driven technologies for the production of cooling. It is shown that the supply of cooling gives the highest fuel utilization if heat from CHP production is used for the production of cooling instead of maximizing the electricity output in a condensing plant. High fuel utilization is reached since the direct production of cooling from heat is a thermodynamic shortcut as compared to the production of electricity as an intermediate product before cooling is produced. At direct production of cooling from heat it is possible to obtain 70 percent of the obtainable cooling of an ideal process. If electricity is produced from heat, 70 percent electricity could be obtained as compared to an ideal process. If this electricity would be used for the production of cooling 70 percent of the obtainable cooling in an ideal process would the result. The total production of cooling from heat with electricity as an intermediate product would therefore give 50 percent cooling as compared to an ideal process. Hence, heat driven cooling will give more cooling for a given fuel input. In the review of the different heat driven cooling options it was found that there are many alternatives suitable for different applications. Absorption cooling is suitable for water distributed cooling if the latent cooling load is low. Desiccant cooling is believed to have a large market in climates (applications) with high latent cooling loads. In the energy efficiency evaluation it is found that the highest fuel utilization is given for a central production of electricity using either district heating or district cooling as the energy carrier to supply cooling. In fact the potential of district heating as the energy carrier is thought to be the largest in large cities with humid climates. Further it is found that the chiller heat sink can contribute significantly to the cost in many applications, especially if water and/or electricity consumption are issues with

Assessment of clean development mechanism potential of large-scale energy efficiency measures in heavy industries

International Nuclear Information System (INIS)

Hayashi, Daisuke; Krey, Matthias

2007-01-01

This paper assesses clean development mechanism (CDM) potential of large-scale energy efficiency measures in selected heavy industries (iron and steel, cement, aluminium, pulp and paper, and ammonia) taking India and Brazil as examples of CDM project host countries. We have chosen two criteria for identification of the CDM potential of each energy efficiency measure: (i) emission reductions volume (in CO 2 e) that can be expected from the measure and (ii) likelihood of the measure passing the additionality test of the CDM Executive Board (EB) when submitted as a proposed CDM project activity. The paper shows that the CDM potential of large-scale energy efficiency measures strongly depends on the project-specific and country-specific context. In particular, technologies for the iron and steel industry (coke dry quenching (CDQ), top pressure recovery turbine (TRT), and basic oxygen furnace (BOF) gas recovery), the aluminium industry (point feeder prebake (PFPB) smelter), and the pulp and paper industry (continuous digester technology) offer promising CDM potential

Efficient heat generation in large-area graphene films by electromagnetic wave absorption

Science.gov (United States)

Kang, Sangmin; Choi, Haehyun; Lee, Soo Bin; Park, Seong Chae; Park, Jong Bo; Lee, Sangkyu; Kim, Youngsoo; Hong, Byung Hee

2017-06-01

Graphene has been intensively studied due to its outstanding electrical and thermal properties. Recently, it was found that the heat generation by Joule heating of graphene is limited by the conductivity of graphene. Here we suggest an alternative method to generate heat on a large-area graphene film more efficiently by utilizing the unique electromagnetic (EM) wave absorption property of graphene. The EM wave induces an oscillating magnetic moment generated by the orbital motion of moving electrons, which efficiently absorbs the EM energy and dissipate it as a thermal energy. In this case, the mobility of electron is more important than the conductivity, because the EM-induced diamagnetic moment is directly proportional to the speed of electron in an orbital motion. To control the charge carrier mobility of graphene we functionalized substrates with self-assembled monolayers (SAM). As the result, we find that the graphene showing the Dirac voltage close to zero can be more efficiently heated by EM waves. In addition, the temperature gradient also depends on the number of graphene. We expect that the efficient and fast heating of graphene films by EM waves can be utilized for smart heating windows and defogging windshields.

Efficient transfer of large-area graphene films onto rigid substrates by hot pressing.

Science.gov (United States)

Kang, Junmo; Hwang, Soonhwi; Kim, Jae Hwan; Kim, Min Hyeok; Ryu, Jaechul; Seo, Sang Jae; Hong, Byung Hee; Kim, Moon Ki; Choi, Jae-Boong

2012-06-26

Graphene films grown on metal substrates by chemical vapor deposition (CVD) method have to be safely transferred onto desired substrates for further applications. Recently, a roll-to-roll (R2R) method has been developed for large-area transfer, which is particularly efficient for flexible target substrates. However, in the case of rigid substrates such as glass or wafers, the roll-based method is found to induce considerable mechanical damages on graphene films during the transfer process, resulting in the degradation of electrical property. Here we introduce an improved dry transfer technique based on a hot-pressing method that can minimize damage on graphene by neutralizing mechanical stress. Thus, we enhanced the transfer efficiency of the large-area graphene films on a substrate with arbitrary thickness and rigidity, evidenced by scanning electron microscope (SEM) and atomic force microscope (AFM) images, Raman spectra, and various electrical characterizations. We also performed a theoretical multiscale simulation from continuum to atomic level to compare the mechanical stresses caused by the R2R and the hot-pressing methods, which also supports our conclusion. Consequently, we believe that the proposed hot-pressing method will be immediately useful for display and solar cell applications that currently require rigid and large substrates.

Optimal design and operation of a thermal storage system for a chilled water plant serving pharmaceutical buildings

Energy Technology Data Exchange (ETDEWEB)

Henze, Gregor P. [University of Nebraska, Architectural Engineering, Omaha, NE 68182 (United States); Biffar, Bernd; Kohn, Dietmar [Boehringer Ingelheim Pharma GmbH and Co. KG, Biberach D-88400 (Germany); Becker, Martin P. [University of Applied Sciences Biberach, Architectural Engineering, Biberach D-88400 (Germany)

2008-07-01

A group of buildings in the pharmaceutical industry located in Southern Germany is experiencing a trend of growing cooling loads to be met by the chilled water plant composed of 10 chillers of greatly varying cost effectiveness. With a capacity shortfall inevitable, the question arises whether to install an additional chiller or improve the utilization of the existing chillers, in particular those with low operating costs per unit cooling, through the addition of a chilled water thermal energy storage (TES) system. To provide decision support in this matter, an optimization environment was developed and validated that adopts mixed integer programming as the approach to optimizing the chiller dispatch for any load condition, while an overarching dynamic programming based optimization approach optimizes the charge/discharge strategy of the TES system. In this fashion, the chilled water plant optimization is decoupled but embedded in the TES control optimization. The approach was selected to allow for arbitrary constraints and optimization horizons, while ensuring a global optimum to the problem. Optimization scenarios have been defined that include current load conditions as well cooling loads that are elevated by 25% from current conditions in order to reflect the expected growth in cooling demand in the near future; both scenarios analyzed the impact of storage capacity by investigating several TES tank capacities. The annual optimization runs revealed that - based on the elevated cooling load scenario - the smallest TES system pays back the incremental investment necessary for the TES system in about three years; based on today's cooling loads the static payback is approximately six years. As the efficiency and cost of operating the existing chillers vary over a wide range, the TES system allows for a reduction in operating costs for the chilled water plant by avoiding the operation of inefficient chillers (such as the single-stage absorption type) and

Tropical Zero Energy Office Building

DEFF Research Database (Denmark)

Reimann, Gregers Peter; Kristensen, Poul Erik

2006-01-01

The new headquarter for Pusat Tenaga Malaysia is designed to be a Zero Emission Office Building (ZEO). A full range of passive and active energy efficiency measures are implemented such that the building will need no more electricity than what can be produced via its own Building Integrated PV...... lighting. These measures include the use of high efficient lighting controlled according to demand, high efficiency pumps and fans, a high efficiency chiller, and use of energy efficient office equipment. The buildings PV system is connected to the grid. Solar electricity is exported to the grid during...... of 24 – 26 oC can be maintained throughout the office hours. The PV roof of the building serves multiple purposes. During daytime, the roof becomes the powerplant of the building, and during nighttime, the PV roof becomes the “cooling tower” for the chiller. The roof will be covered by a thin water film...

Efficient purification and concentration of viruses from a large body of high turbidity seawater.

Science.gov (United States)

Sun, Guowei; Xiao, Jinzhou; Wang, Hongming; Gong, Chaowen; Pan, Yingjie; Yan, Shuling; Wang, Yongjie

2014-01-01

Marine viruses are the most abundant entities in the ocean and play crucial roles in the marine ecological system. However, understanding of viral diversity on large scale depends on efficient and reliable viral purification and concentration techniques. Here, we report on developing an efficient method to purify and concentrate viruses from large body of high turbidity seawater. The developed method characterizes with high viral recovery efficiency, high concentration factor, high viral particle densities and high-throughput, and is reliable for viral concentration from high turbidity seawater. Recovered viral particles were used directly for subsequent analysis by epifluorescence microscopy, transmission electron microscopy and metagenomic sequencing. Three points are essential for this method:•The sampled seawater (>150 L) was initially divided into two parts, water fraction and settled matter fraction, after natural sedimentation.•Both viruses in the water fraction concentrated by tangential flow filtration (TFF) and viruses isolated from the settled matter fraction were considered as the whole viral community in high turbidity seawater.•The viral concentrates were re-concentrated by using centrifugal filter device in order to obtain high density of viral particles.

Performance of LiCl Impregnated Mesoporous Material Coating over Corrugated Heat Exchangers in a Solid Sorption Chiller

Directory of Open Access Journals (Sweden)

Hongzhi Liu

2018-06-01

Full Text Available The composite material made by impregnating 40 wt. % lithium chloride (LiCl into the mesopores of a kind of natural porous rock (Wakkanai Siliceous Shale: WSS micropowders (short for “WSS + 40 wt. % LiCl” had been developed previously, and can be regenerated below 100 °C with a cooling coefficient of performance (COP of approximately 0.3 when adopted as a sorbent in a sorption cooler. In this study, experiments have been carried out on an intermittent solid sorption chiller with the WSS + 40 wt. % LiCl coating over two aluminum corrugated heat exchangers. Based on the experimental condition (regeneration temperature of 80 °C, condensation temperature of 30 °C in the desorption process; sorption temperature of 30 °C and evaporation temperature of 12 °C in the sorption process, the water sorption amount changes from 20 wt. % to 70 wt. % in one sorption cooling cycle. Moreover, a specific cooling power (SCP of 86 W/kg, a volumetric specific cooling power (VSCP of 42 W/dm3, and a specific sorption power of 170 W/kg can be achieved with a total sorption and desorption time of 20 min. The obtained cooling COP is approximately 0.16.

An energy-efficient data gathering protocol in large wireless sensor network

Science.gov (United States)

Wang, Yamin; Zhang, Ruihua; Tao, Shizhong

2006-11-01

Wireless sensor network consisting of a large number of small sensors with low-power transceiver can be an effective tool for gathering data in a variety of environment. The collected data must be transmitted to the base station for further processing. Since a network consists of sensors with limited battery energy, the method for data gathering and routing must be energy efficient in order to prolong the lifetime of the network. In this paper, we presented an energy-efficient data gathering protocol in wireless sensor network. The new protocol used data fusion technology clusters nodes into groups and builds a chain among the cluster heads according to a hybrid of the residual energy and distance to the base station. Results in stochastic geometry are used to derive the optimum parameter of our algorithm that minimizes the total energy spent in the network. Simulation results show performance superiority of the new protocol.

Low R&D Efficiency in Large Pharmaceutical Companies

DEFF Research Database (Denmark)

Madsen, Erik Strøjer; Wu, Yanqing

2016-01-01

Large pharmaceutical companies will face serious challenges in the future when several of their blockbuster drugs run out of patents, and meanwhile a growing political pressure to stop the fast increase in health care expenditures has merged. The recent wave of mergers and acquisitions (M&A) within...... the industry can be seen as an effective means to reduce costs and compensate for the reduced earnings from patented drugs. The paper examines the main development in expenditure on research and development (R&D) and number of patents in the industry with a focus on the role of company size. The analysis...... builds on a data set containing information of both patents and R&D expenditure from the world’s top 90 largest pharmaceutical companies, as well as their account data from 2002 to 2013. The empirical part estimates the firm size effect on R&D efficiency and the amount of investment allocated to R...

Production and efficiency of large wildland fire suppression effort: A stochastic frontier analysis.

Science.gov (United States)

Katuwal, Hari; Calkin, David E; Hand, Michael S

2016-01-15

This study examines the production and efficiency of wildland fire suppression effort. We estimate the effectiveness of suppression resource inputs to produce controlled fire lines that contain large wildland fires using stochastic frontier analysis. Determinants of inefficiency are identified and the effects of these determinants on the daily production of controlled fire line are examined. Results indicate that the use of bulldozers and fire engines increase the production of controlled fire line, while firefighter crews do not tend to contribute to controlled fire line production. Production of controlled fire line is more efficient if it occurs along natural or built breaks, such as rivers and roads, and within areas previously burned by wildfires. However, results also indicate that productivity and efficiency of the controlled fire line are sensitive to weather, landscape and fire characteristics. Copyright © 2015 Elsevier Ltd. All rights reserved.

Implementing effect of energy efficiency supervision system for government office buildings and large-scale public buildings in China

International Nuclear Information System (INIS)

Zhao Jing; Wu Yong; Zhu Neng

2009-01-01

The Chinese central government released a document to initiate a task of energy efficiency supervision system construction for government office buildings and large-scale public buildings in 2007, which marks the overall start of existing buildings energy efficiency management in China with the government office buildings and large-scale public buildings as a breakthrough. This paper focused on the implementing effect in the demonstration region all over China for less than one year, firstly introduced the target and path of energy efficiency supervision system, then described the achievements and problems during the implementing process in the first demonstration provinces and cities. A certain data from the energy efficiency public notice in some typical demonstration provinces and cities were analyzed statistically. It can be concluded that different functional buildings have different energy consumption and the average energy consumption of large-scale public buildings is too high in China compared with the common public buildings and residential buildings. The obstacles need to be overcome afterward were summarized and the prospects for the future work were also put forward in the end.

Implementing effect of energy efficiency supervision system for government office buildings and large-scale public buildings in China

Energy Technology Data Exchange (ETDEWEB)

Zhao Jing [School of Environmental Science and Engineering, Tianjin University, Tianjin 300072 (China)], E-mail: zhaojing@tju.edu.cn; Wu Yong [Department of Science and Technology, Ministry of Housing and Urban-Rural Development of the People' s Republic of China, Beijing 100835 (China); Zhu Neng [School of Environmental Science and Engineering, Tianjin University, Tianjin 300072 (China)

2009-06-15

The Chinese central government released a document to initiate a task of energy efficiency supervision system construction for government office buildings and large-scale public buildings in 2007, which marks the overall start of existing buildings energy efficiency management in China with the government office buildings and large-scale public buildings as a breakthrough. This paper focused on the implementing effect in the demonstration region all over China for less than one year, firstly introduced the target and path of energy efficiency supervision system, then described the achievements and problems during the implementing process in the first demonstration provinces and cities. A certain data from the energy efficiency public notice in some typical demonstration provinces and cities were analyzed statistically. It can be concluded that different functional buildings have different energy consumption and the average energy consumption of large-scale public buildings is too high in China compared with the common public buildings and residential buildings. The obstacles need to be overcome afterward were summarized and the prospects for the future work were also put forward in the end.

Implementing effect of energy efficiency supervision system for government office buildings and large-scale public buildings in China

Energy Technology Data Exchange (ETDEWEB)

Zhao, Jing; Zhu, Neng [School of Environmental Science and Engineering, Tianjin University, Tianjin 300072 (China); Wu, Yong [Department of Science and Technology, Ministry of Housing and Urban-Rural Development of the People' s Republic of China, Beijing 100835 (China)

2009-06-15

The Chinese central government released a document to initiate a task of energy efficiency supervision system construction for government office buildings and large-scale public buildings in 2007, which marks the overall start of existing buildings energy efficiency management in China with the government office buildings and large-scale public buildings as a breakthrough. This paper focused on the implementing effect in the demonstration region all over China for less than one year, firstly introduced the target and path of energy efficiency supervision system, then described the achievements and problems during the implementing process in the first demonstration provinces and cities. A certain data from the energy efficiency public notice in some typical demonstration provinces and cities were analyzed statistically. It can be concluded that different functional buildings have different energy consumption and the average energy consumption of large-scale public buildings is too high in China compared with the common public buildings and residential buildings. The obstacles need to be overcome afterward were summarized and the prospects for the future work were also put forward in the end. (author)

Efficient graph-based dynamic load-balancing for parallel large-scale agent-based traffic simulation

NARCIS (Netherlands)

Xu, Y.; Cai, W.; Aydt, H.; Lees, M.; Tolk, A.; Diallo, S.Y.; Ryzhov, I.O.; Yilmaz, L.; Buckley, S.; Miller, J.A.

2014-01-01

One of the issues of parallelizing large-scale agent-based traffic simulations is partitioning and load-balancing. Traffic simulations are dynamic applications where the distribution of workload in the spatial domain constantly changes. Dynamic load-balancing at run-time has shown better efficiency

A solvent- and vacuum-free route to large-area perovskite films for efficient solar modules

Science.gov (United States)

Chen, Han; Ye, Fei; Tang, Wentao; He, Jinjin; Yin, Maoshu; Wang, Yanbo; Xie, Fengxian; Bi, Enbing; Yang, Xudong; Grätzel, Michael; Han, Liyuan

2017-10-01

Recent advances in the use of organic-inorganic hybrid perovskites for optoelectronics have been rapid, with reported power conversion efficiencies of up to 22 per cent for perovskite solar cells. Improvements in stability have also enabled testing over a timescale of thousands of hours. However, large-scale deployment of such cells will also require the ability to produce large-area, uniformly high-quality perovskite films. A key challenge is to overcome the substantial reduction in power conversion efficiency when a small device is scaled up: a reduction from over 20 per cent to about 10 per cent is found when a common aperture area of about 0.1 square centimetres is increased to more than 25 square centimetres. Here we report a new deposition route for methyl ammonium lead halide perovskite films that does not rely on use of a common solvent or vacuum: rather, it relies on the rapid conversion of amine complex precursors to perovskite films, followed by a pressure application step. The deposited perovskite films were free of pin-holes and highly uniform. Importantly, the new deposition approach can be performed in air at low temperatures, facilitating fabrication of large-area perovskite devices. We reached a certified power conversion efficiency of 12.1 per cent with an aperture area of 36.1 square centimetres for a mesoporous TiO2-based perovskite solar module architecture.

A novel solar-assisted heat pump driven by photovoltaic/thermal collectors: Dynamic simulation and thermoeconomic optimization

International Nuclear Information System (INIS)

Calise, Francesco; Dentice d'Accadia, Massimo; Figaj, Rafal Damian; Vanoli, Laura

2016-01-01

This paper presents a dynamic simulation model and a thermo-economic analysis of a novel polygeneration system based on a solar-assisted heat pump and an adsorption chiller, both driven by PVT (photovoltaic/thermal) collectors. The aim of this work is to design and dynamically simulate a novel ultra-high efficient solar heating and cooling system. The overall plant layout is designed to supply electricity, space heating and cooling and domestic hot water for a small residential building. The system combines solar cooling, solar-assisted heat pump and photovoltaic/thermal collector technologies in a novel solar polygeneration system. In fact, the polygeneration system is based on a PVT solar field, coupled with a water-to-water electric heat pump or to an adsorption chiller. PVT collectors simultaneously produce electricity and thermal energy. During the winter, hot water produced by PVT collectors primarily supplies the evaporator of the heat pump, whereas in summer, solar energy supplies an adsorption chiller providing the required space cooling. All year long, solar thermal energy in excess is converted into DHW (domestic hot water). The system model was developed in TRNSYS environment. 1-year dynamic simulations are performed for different case studies in various weather conditions. The results are analysed on different time bases presenting energetic, environmental and economic performance data. Finally, a sensitivity analysis and a thermoeconomic optimization were performed, in order to determine the set of system design/control parameters that minimize the simple pay-back period. The results showed a total energy efficiency of the PVT of 49%, a heat pump yearly coefficient of performance for heating mode above 4 and a coefficient of performance of the adsorption chiller of 0.55. Finally, it is also concluded that system performance is highly sensitive to the PVT field area. The system is profitable when a capital investment subsidy of 50% is considered

Selection and Implementation of Single Building EMCS (Energy Monitoring and Control Systems).

Science.gov (United States)

1983-08-01

Setpoint Night Setback 161 Figure 20: Dual Setpoint Night Setback/up 162 Figure 21: Centrifugal Chiller Reset 166 Figure 22: Centrifugal Chiller Capacity...Program outputs. Hot water temperature. Application notes. A dedicated local loop controller may be implemented. Chiller optimization . The chiller ... optimization program can be implemented in chilled water plants with multiple chillers . Based on chiller operating data and the energy input requirements

LOD-based clustering techniques for efficient large-scale terrain storage and visualization

Science.gov (United States)

Bao, Xiaohong; Pajarola, Renato

2003-05-01

Large multi-resolution terrain data sets are usually stored out-of-core. To visualize terrain data at interactive frame rates, the data needs to be organized on disk, loaded into main memory part by part, then rendered efficiently. Many main-memory algorithms have been proposed for efficient vertex selection and mesh construction. Organization of terrain data on disk is quite difficult because the error, the triangulation dependency and the spatial location of each vertex all need to be considered. Previous terrain clustering algorithms did not consider the per-vertex approximation error of individual terrain data sets. Therefore, the vertex sequences on disk are exactly the same for any terrain. In this paper, we propose a novel clustering algorithm which introduces the level-of-detail (LOD) information to terrain data organization to map multi-resolution terrain data to external memory. In our approach the LOD parameters of the terrain elevation points are reflected during clustering. The experiments show that dynamic loading and paging of terrain data at varying LOD is very efficient and minimizes page faults. Additionally, the preprocessing of this algorithm is very fast and works from out-of-core.

Large pollen loads of a South African asclepiad do not interfere with the foraging behaviour or efficiency of pollinating honey bees

Science.gov (United States)

Coombs, G.; Dold, A. P.; Brassine, E. I.; Peter, C. I.

2012-07-01

The pollen of asclepiads (Asclepiadoideae, Apocynaceae) and most orchids (Orchidaceae) are packaged as large aggregations known as pollinaria that are removed as entire units by pollinators. In some instances, individual pollinators may accumulate large loads of these pollinaria. We found that the primary pollinator of Cynanchum ellipticum (Apocynaceae—Asclepiadoideae), the honey bee Apis mellifera, accumulate very large agglomerations of pollinaria on their mouthparts when foraging on this species. We tested whether large pollinarium loads negatively affected the foraging behaviour and foraging efficiency of honey bees by slowing foraging speeds or causing honey bees to visit fewer flowers, and found no evidence to suggest that large pollinarium loads altered foraging behaviour. C. ellipticum displayed consistently high levels of pollination success and pollen transfer efficiency (PTE). This may be a consequence of efficiently loading large numbers of pollinaria onto pollinators even when primary points of attachment on pollinators are already occupied and doing so in a manner that does not impact the foraging behaviour of pollinating insects.

Large guanidinium cation mixed with methylammonium in lead iodide perovskites for 19% efficient solar cells

Science.gov (United States)

Jodlowski, Alexander D.; Roldán-Carmona, Cristina; Grancini, Giulia; Salado, Manuel; Ralaiarisoa, Maryline; Ahmad, Shahzada; Koch, Norbert; Camacho, Luis; de Miguel, Gustavo; Nazeeruddin, Mohammad Khaja

2017-12-01

Organic-inorganic lead halide perovskites have shown photovoltaic performances above 20% in a range of solar cell architectures while offering simple and low-cost processability. Despite the multiple ionic compositions that have been reported so far, the presence of organic constituents is an essential element in all of the high-efficiency formulations, with the methylammonium and formamidinium cations being the sole efficient options available to date. In this study, we demonstrate improved material stability after the incorporation of a large organic cation, guanidinium, into the MAPbI3 crystal structure, which delivers average power conversion efficiencies over 19%, and stabilized performance for 1,000 h under continuous light illumination, a fundamental step within the perovskite field.

Evaluation of a fast power demand response strategy using active and passive building cold storages for smart grid applications

International Nuclear Information System (INIS)

Cui, Borui; Wang, Shengwei; Yan, Chengchu; Xue, Xue

2015-01-01

Highlights: • A fast power demand response strategy is developed for smart grid applications. • The developed strategy can provide immediate and stepped power demand reduction. • The demand reduction and building indoor temperature can be predicted accurately. • The demand reduction during the DR event is stable. - Abstract: Smart grid is considered as a promising solution in improving the power reliability and sustainability where demand response is one important ingredient. Demand response (DR) is a set of demand-side activities to reduce or shift electricity use to improve the electric grid efficiency and reliability. This paper presents the investigations on the power demand alternation potential for buildings involving both active and passive cold storages to support the demand response of buildings connected to smart grids. A control strategy is developed to provide immediate and stepped power demand reduction through shutting chiller(s) down when requested. The primary control objective of the developed control strategy is to restrain the building indoor temperature rise as to maintain indoor thermal comfort within certain level during the DR event. The chiller power reduction is also controlled under certain power reduction set-point. The results show that stepped and significant power reduction can be achieved through shutting chiller(s) down when requested. The power demand reduction and indoor temperature during the DR event can be also predicted accurately. The power demand reduction is stable which is predictable for the system operators

Increasing a large petrochemical company efficiency by improvement of decision making process

OpenAIRE

Kirin Snežana D.; Nešić Lela G.

2010-01-01

The paper shows the results of a research conducted in a large petrochemical company, in a state under transition, with the aim to "shed light" on the decision making process from the aspect of personal characteristics of the employees, in order to use the results to improve decision making process and increase company efficiency. The research was conducted by a survey, i.e. by filling out a questionnaire specially made for this purpose, in real conditions, during working hours. The sample of...

Analysis of electrical audit and energy efficiency in building Hotel BC, North Jakarta

Science.gov (United States)

Wahyudi Biantoro, Agung

2018-03-01

The Hotel BC is using power source from PLN with capacity of 4300 kVA which is divided into 3 units of 2000 kVA transformer. Transformers are used to supply the load of Mall tenants, and Utility loads, such as Chiller, pumps and others. Problems found in the field are complaints from the hotel regarding the safety of electrical installations and wasteful, inefficient electrical costs. The purpose of this study is to check the electrical installation in the building and determine the Energy Use Intensity (EUI) and the cost of payment according to usage based on historical data of the building then compare it with the EUI standard of Ministry of Energy and Mineral Resources of Indonesia. The method used is survey measurement method and quantitative descriptive analysis by comparing in general condition of energy consumption of this building with standard issued by Ministry of Energy and Mineral Resources of Indonesia. The EUI is average 645.58 kWh/m2/year, or 53.79 kWh/m2/month, this is inefficient category, because its EUI value is > 24 kWh / m2 / month. For Electrical audit on imaging thermal test at Panel Out Going of chiller pump, 200 ampere, the highest temperature is 97.3° C, at 200 ampere phase S termination, and this is included in the major category. The numbers of hot spots on the Capacitor bank panels are 10 major points and Chiller panel has 10 major. There are many major points and they are quite dangerous because they can cause fire hazard on the panel. The AC average temperature and humidity distribution did not meet the standard of SNI (Indonesia National Standard).

Modeling Chilled-Water Storage System Components for Coupling to a Small Modular Reactor in a Nuclear Hybrid Energy System

Science.gov (United States)

Misenheimer, Corey Thomas

The intermittency of wind and solar power puts strain on electric grids, often forcing carbonbased and nuclear sources of energy to operate in a load-follow mode. Operating nuclear reactors in a load-follow fashion is undesirable due to the associated thermal and mechanical stresses placed on the fuel and other reactor components. Various Thermal Energy Storage (TES) elements and ancillary energy applications can be coupled to nuclear (or renewable) power sources to help absorb grid instabilities caused by daily electric demand changes and renewable intermittency, thereby forming the basis of a candidate Nuclear Hybrid Energy System (NHES). During the warmer months of the year in many parts of the country, facility air-conditioning loads are significant contributors to the increase in the daily peak electric demand. Previous research demonstrated that a stratified chilled-water storage tank can displace peak cooling loads to off-peak hours. Based on these findings, the objective of this work is to evaluate the prospect of using a stratified chilled-water storage tank as a potential TES reservoir for a nuclear reactor in a NHES. This is accomplished by developing time-dependent models of chilled-water system components, including absorption chillers, cooling towers, a storage tank, and facility cooling loads appropriate for a large office space or college campus, as a callable FORTRAN subroutine. The resulting TES model is coupled to a high-fidelity mPower-sized Small Modular Reactor (SMR) Simulator, with the goal of utilizing excess reactor capacity to operate several sizable chillers in order to keep reactor power constant. Chilled-water production via single effect, lithium bromide (LiBr) absorption chillers is primarily examined in this study, although the use of electric chillers is briefly explored. Absorption chillers use hot water or low-pressure steam to drive an absorption-refrigeration cycle. The mathematical framework for a high-fidelity dynamic

DCDM1: Lessons Learned from the World's Most Energy Efficient Data Center

Energy Technology Data Exchange (ETDEWEB)

Sickinger, David E [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Van Geet, Otto D [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Carter, Thomas [Johnson Controls

2018-05-03

This presentation discusses the holistic approach to design the world's most energy-efficient data center, which is located at the U.S. Department of Energy National Renewable Energy Laboratory (NREL). This high-performance computing (HPC) data center has achieved a trailing twelve-month average power usage effectiveness (PUE) of 1.04 and features a chiller-less design, component-level warm-water liquid cooling, and waste heat capture and reuse. We provide details of the demonstrated PUE and energy reuse effectiveness (ERE) and lessons learned during four years of production operation. Recent efforts to dramatically reduce the water footprint will also be discussed. Johnson Controls partnered with NREL and Sandia National Laboratories to deploy a thermosyphon cooler (TSC) as a test bed at NREL's HPC data center that resulted in a 50% reduction in water usage during the first year of operation. The Thermosyphon Cooler Hybrid System (TCHS) integrates the control of a dry heat rejection device with an open cooling tower.

Increase energy efficiency in the cold production; Steigerung der Energieeffizienz in der Kaelteerzeugung

Energy Technology Data Exchange (ETDEWEB)

Paatzsch, Rene [Institut fuer Luft- und Kaeltetechnik gGmbH, Dresden (Germany). Hauptbereich Kaelte- und Waermepumpentechnik; Berg, Hans-Peter [Boehringer Ingelheim Pharma GmbH und Co. KG, Ingelheim (Germany)

2011-12-15

According to a study by ILK Dresden the cold production in the field of pharmaceutical manufacturing at Boehringer has been adjusted. By installing a turbo chiller and the sliding control of the cooling water temperature depending on the wet bulb temperature the COP of the cold production was improved of 3.1 to 4.5 currently. (orig.)

Government regulation and associated innovations in building energy-efficiency supervisory systems for large-scale public buildings in a market economy

International Nuclear Information System (INIS)

Dai Xuezhi; Wu Yong; Di Yanqiang; Li Qiaoyan

2009-01-01

The supervision of energy efficiency in government office buildings and large-scale public buildings is the main embodiment for government implementation of Public Administration in the fields of resource saving and environmental protection. Aimed at improving the current situation of lack of government administration in building energy efficiency, this paper proposes the concept of 'change and redesign of governmental supervision in building energy efficiency', repositioning the role of government supervision. Based on this theory and other related theories in regulation economic and modern management, this paper analyzes and researches the action and function of all level governments in execution of the supervisory system of building energy efficiency in government office buildings and large-scale public buildings. This paper also defines the importance of government supervision in energy-efficiency system. Finally, this paper analyzes and researches the interaction mechanism between government and owners of different type buildings, government and energy-efficiency service institution with gambling as main features. This paper also presents some measurements to achieve a common benefit community in implementation of building energy-efficiency supervisory system.

Government regulation and associated innovations in building energy-efficiency supervisory systems for large-scale public buildings in a market economy

Energy Technology Data Exchange (ETDEWEB)

Dai Xuezhi [China Academy of Building Research, Beijing 100013 (China)], E-mail: daixz9999@126.com; Wu Yong [Ministry of Housing and Urban-Rural Development of the People' s Republic of China, Beijing 100835 (China); Di Yanqiang [China Academy of Building Research, Beijing 100013 (China); Li Qiaoyan [Department of Building, School of Design and Environment, National University of Singapore (Singapore)

2009-06-15

The supervision of energy efficiency in government office buildings and large-scale public buildings is the main embodiment for government implementation of Public Administration in the fields of resource saving and environmental protection. Aimed at improving the current situation of lack of government administration in building energy efficiency, this paper proposes the concept of 'change and redesign of governmental supervision in building energy efficiency', repositioning the role of government supervision. Based on this theory and other related theories in regulation economic and modern management, this paper analyzes and researches the action and function of all level governments in execution of the supervisory system of building energy efficiency in government office buildings and large-scale public buildings. This paper also defines the importance of government supervision in energy-efficiency system. Finally, this paper analyzes and researches the interaction mechanism between government and owners of different type buildings, government and energy-efficiency service institution with gambling as main features. This paper also presents some measurements to achieve a common benefit community in implementation of building energy-efficiency supervisory system.

Government regulation and associated innovations in building energy-efficiency supervisory systems for large-scale public buildings in a market economy

Energy Technology Data Exchange (ETDEWEB)

Dai, Xuezhi; Di, Yanqiang [China Academy of Building Research, Beijing 100013 (China); Wu, Yong [Ministry of Housing and Urban-Rural Development of the People' s Republic of China, Beijing 100835 (China); Li, Qiaoyan [Department of Building, School of Design and Environment, National University of Singapore (Singapore)

2009-06-15

The supervision of energy efficiency in government office buildings and large-scale public buildings is the main embodiment for government implementation of Public Administration in the fields of resource saving and environmental protection. Aimed at improving the current situation of lack of government administration in building energy efficiency, this paper proposes the concept of 'change and redesign of governmental supervision in building energy efficiency', repositioning the role of government supervision. Based on this theory and other related theories in regulation economic and modern management, this paper analyzes and researches the action and function of all level governments in execution of the supervisory system of building energy efficiency in government office buildings and large-scale public buildings. This paper also defines the importance of government supervision in energy-efficiency system. Finally, this paper analyzes and researches the interaction mechanism between government and owners of different type buildings, government and energy-efficiency service institution with gambling as main features. This paper also presents some measurements to achieve a common benefit community in implementation of building energy-efficiency supervisory system. (author)

Air conditioning using an air-cooled single effect lithium bromide absorption chiller: Results of a trial conducted in Madrid in August 2005

International Nuclear Information System (INIS)

Izquierdo, M.; Lizarte, R.; Marcos, J.D.; Gutierrez, G.

2008-01-01

Trials were conducted to determine the performance of a commercial (Rotartica 045v) 4.5-kW air-cooled, single effect LiBr/H 2 O absorption chiller for residential use. The experiments were run at La Poveda, Arganda del Rey, Madrid, in August 2005. Three typical August days, with different outdoor temperatures, were chosen for the study. The hot water inlet temperature in the generator varied throughout the day from 80 to 107 o C. Thermal demand was calculated, along with period energy balance and COP. Variations in machine component temperatures were recorded and chilling power and the daily COP calculated for each of the three days. The results for the period as a whole showed that cooling power tended to decline with rising outdoor dry bulb temperatures. At temperatures from 35 to 41.3 o C the chilled water outlet temperature in the evaporator climbed to over 15 o C. The average COP for the period, when auxiliary equipment was included into the calculations, was 0.37

Performance study of a dual power source residential CCHP system based on PEMFC and PTSC

International Nuclear Information System (INIS)

Chen, Xi; Gong, Guangcai; Wan, Zhongmin; Zhang, Caizhi; Tu, Zhengkai

2016-01-01

Highlights: • A novel dual power source residential CCHP system model is proposed. • Low temperature and high current density guarantee the high efficiency of PTSC. • High system efficiency can be obtained at a relatively low solar radiation. • Government subsidy is a crucial factor to improve system economic performance. • System environmental performance is discussed by parametric study. - Abstract: This paper presents an innovative, hybrid residential CCHP system based on fuel cell and solar technologies that can provide electric power, heating and cooling. The CCHP system consists of a proton exchange membrane fuel cell (PEMFC) stack, parabolic trough solar collector (PTSC), double-effect absorption chiller and their relevant accessories. The effects of key operating parameters for PEMFC and PTSC systems (e.g.: current density, operating temperature and solar radiation) on the system thermodynamic performance are analyzed and discussed. The results show that the PEMFC operation temperature has a significant influence on the PTSC output performance in a hybrid CCHP system and that the PTSC also plays an important role as a bridge between the PEMFC stack and absorption chiller. The maximum efficiency of a hybrid system can reach 80.5%, which is higher than conventional CCHP systems, due to the high efficiency of PEMFC, PTSC and double-effect absorption chiller. The economic and environmental analysis of CCHP system are also performed, the results indicate the project is practicable, meanwhile, high current density and solar radiation and low operating temperature can improve pollutant emissions reduction of the system.

Data Mining for Efficient and Accurate Large Scale Retrieval of Geophysical Parameters

Science.gov (United States)

Obradovic, Z.; Vucetic, S.; Peng, K.; Han, B.

2004-12-01

Our effort is devoted to developing data mining technology for improving efficiency and accuracy of the geophysical parameter retrievals by learning a mapping from observation attributes to the corresponding parameters within the framework of classification and regression. We will describe a method for efficient learning of neural network-based classification and regression models from high-volume data streams. The proposed procedure automatically learns a series of neural networks of different complexities on smaller data stream chunks and then properly combines them into an ensemble predictor through averaging. Based on the idea of progressive sampling the proposed approach starts with a very simple network trained on a very small chunk and then gradually increases the model complexity and the chunk size until the learning performance no longer improves. Our empirical study on aerosol retrievals from data obtained with the MISR instrument mounted at Terra satellite suggests that the proposed method is successful in learning complex concepts from large data streams with near-optimal computational effort. We will also report on a method that complements deterministic retrievals by constructing accurate predictive algorithms and applying them on appropriately selected subsets of observed data. The method is based on developing more accurate predictors aimed to catch global and local properties synthesized in a region. The procedure starts by learning the global properties of data sampled over the entire space, and continues by constructing specialized models on selected localized regions. The global and local models are integrated through an automated procedure that determines the optimal trade-off between the two components with the objective of minimizing the overall mean square errors over a specific region. Our experimental results on MISR data showed that the combined model can increase the retrieval accuracy significantly. The preliminary results on various

Large thermoelectric efficiency of doped polythiophene junction: A density functional study

Science.gov (United States)

Golsanamlou, Zahra; Bagheri Tagani, Meysam; Rahimpour Soleimani, Hamid

2018-06-01

The thermoelectric properties of polythiophene (PT) coupled to the Au (111) electrodes are studied based on density functional theory with nonequilibrium Green function formalism. Specially, the effect of Li and Cl adsorbents on the thermoelectric efficiency of the PT junction is investigated in different concentrations of the dopants for two lengths of the PT. Results show that the presence of dopants can bring the structural changes in the oligomer and modify the arrangement of the molecular levels leading to the dramatic changes in the transmission spectra of the junction. Therefore, the large enhancement in thermopower and consequently figure of merit is obtained by dopants which makes the doped PT junction as a beneficial thermoelectric device.

Function and application of ammonia-water adsorption refrigeration cycles; Funktion und Anwendung von Ammoniak-Wasser-Absorptionskaeltemaschinen

Energy Technology Data Exchange (ETDEWEB)

Heyse, Christoph; Stuerzebecher, Wolfgang [Tranter Solarice GmbH, Artern (Germany); Cibis, Dominik [Europaeische Studienakademie Kaelte-Klima-Lueftung, Maintal (Germany)

2012-07-01

The pursuit of the nations for more energy efficiency and environmentally friendly handling of nature and its resources is growing steadily. This new dimension of environmental awareness led to the fact that Germany has set the goal to become one of the most energy efficient and environmentally friendly economies of the world. Inter alia research and development in the areas of energy efficiency and renewable energy benefit from this. The meanwhile strongly forgotten potential of absorption chillers used for more than 150 years was due to rising energy costs and the rethinking in dealing with existing energy sources, newly discovered. The application of absorption chillers can be found everywhere, where a lot of heat is released unused into the environment. The implementation of the absorption refrigeration technology in power systems can have enormous energetic and thus ecological and economical benefits. Currently, mainly gas-fired cogeneration units whose main purpose is the generation of electricity can be used as heat sources. Particularly versatile is the application of NH{sub 3}-H{sub 2}O absorbers where heating temperatures are located at 100 Celsius and cooling temperatures up to -10 Celsius are needed, for example for air conditioning of buildings, cooling of food-stuff or for process cooling. The contribution under consideration reports on an overview of the working principle of ammonia water absorption chillers and presents various applications and uses in line with a combined power-heat-coldness coupling.

Evaluation of solar thermal driven cooling system in office buildings in Saudi Arabia

Science.gov (United States)

Linjawi, Majid T.; Talal, Qazi; Al-Sulaiman, Fahad A.

2017-11-01

In this study solar driven absorption chiller is used to reduce the peak cooling load in office buildings in Saudi Arabia for different selected cities. The study is conducted for six cities of Abha, Dhahran, Hail, Jeddah, Nejran and Riyadh under three operating durations of 4, 6, and 8 hours using flat plate or evacuated tube collectors. The energy analysis concluded that flat plate collectors are better than evacuated tube collectors. However, the results from economic analysis suggest that while proposing a gas fired absorption chiller will reduce running costs, further reduction by using solar collectors is not feasible because of its high initial cost. At the best case scenario the Net Present Value of a 10 Ton Absorption chiller operated by natural gas boiler and two large flat plate collectors (12m2 each) running for 8 hours/day, 5days/week has a value of 117,000 and Internal Rate of Return (IRR) of 12%. Solar driven absorption chiller could be more feasible if the gas prices increases or the solar collector prices decreases significantly. Finally, government economic incentives and taxes are recommended to provide a boost for the feasibility of such projects.

An efficient and novel computation method for simulating diffraction patterns from large-scale coded apertures on large-scale focal plane arrays

Science.gov (United States)

Shrekenhamer, Abraham; Gottesman, Stephen R.

2012-10-01

A novel and memory efficient method for computing diffraction patterns produced on large-scale focal planes by largescale Coded Apertures at wavelengths where diffraction effects are significant has been developed and tested. The scheme, readily implementable on portable computers, overcomes the memory limitations of present state-of-the-art simulation codes such as Zemax. The method consists of first calculating a set of reference complex field (amplitude and phase) patterns on the focal plane produced by a single (reference) central hole, extending to twice the focal plane array size, with one such pattern for each Line-of-Sight (LOS) direction and wavelength in the scene, and with the pattern amplitude corresponding to the square-root of the spectral irradiance from each such LOS direction in the scene at selected wavelengths. Next the set of reference patterns is transformed to generate pattern sets for other holes. The transformation consists of a translational pattern shift corresponding to each hole's position offset and an electrical phase shift corresponding to each hole's position offset and incoming radiance's direction and wavelength. The set of complex patterns for each direction and wavelength is then summed coherently and squared for each detector to yield a set of power patterns unique for each direction and wavelength. Finally the set of power patterns is summed to produce the full waveband diffraction pattern from the scene. With this tool researchers can now efficiently simulate diffraction patterns produced from scenes by large-scale Coded Apertures onto large-scale focal plane arrays to support the development and optimization of coded aperture masks and image reconstruction algorithms.

Electrical efficiency and renewable energy - Economical alternatives to large-scale power generation

International Nuclear Information System (INIS)

Oettli, B.; Hammer, S.; Moret, F.; Iten, R.; Nordmann, T.

2010-05-01

This final report for WWF Switzerland, Greenpeace Switzerland, the Swiss Energy Foundation SES, Pro Natura and the Swiss Cantons of Basel City and Geneva takes a look at the energy-relevant effects of the propositions made by Swiss electricity utilities for large-scale power generation. These proposals are compared with a strategy that proposes investments in energy-efficiency and the use of renewable sources of energy. The effects of both scenarios on the environment and the risks involved are discussed, as are the investments involved. The associated effects on the Swiss national economy are also discussed. For the efficiency and renewables scenario, two implementation variants are discussed: Inland investments and production are examined as are foreign production options and/or import from foreign countries. The methods used in the study are introduced and discussed. Investment and cost considerations, earnings and effects on employment are also reviewed. The report is completed with an extensive appendix which, amongst other things, includes potential reviews, cost estimates and a discussion on 'smart grids'

A method for real-time memory efficient implementation of blob detection in large images

Directory of Open Access Journals (Sweden)

Petrović Vladimir L.

2017-01-01

Full Text Available In this paper we propose a method for real-time blob detection in large images with low memory cost. The method is suitable for implementation on the specialized parallel hardware such as multi-core platforms, FPGA and ASIC. It uses parallelism to speed-up the blob detection. The input image is divided into blocks of equal sizes to which the maximally stable extremal regions (MSER blob detector is applied in parallel. We propose the usage of multiresolution analysis for detection of large blobs which are not detected by processing the small blocks. This method can find its place in many applications such as medical imaging, text recognition, as well as video surveillance or wide area motion imagery (WAMI. We explored the possibilities of usage of detected blobs in the feature-based image alignment as well. When large images are processed, our approach is 10 to over 20 times more memory efficient than the state of the art hardware implementation of the MSER.

A new framework to increase the efficiency of large-scale solar power plants.

Science.gov (United States)

Alimohammadi, Shahrouz; Kleissl, Jan P.

2015-11-01

A new framework to estimate the spatio-temporal behavior of solar power is introduced, which predicts the statistical behavior of power output at utility scale Photo-Voltaic (PV) power plants. The framework is based on spatio-temporal Gaussian Processes Regression (Kriging) models, which incorporates satellite data with the UCSD version of the Weather and Research Forecasting model. This framework is designed to improve the efficiency of the large-scale solar power plants. The results are also validated from measurements of the local pyranometer sensors, and some improvements in different scenarios are observed. Solar energy.

A novel polygeneration system integrating photovoltaic/thermal collectors, solar assisted heat pump, adsorption chiller and electrical energy storage: Dynamic and energy-economic analysis

International Nuclear Information System (INIS)

Calise, Francesco; Figaj, Rafal Damian; Vanoli, Laura

2017-01-01

Highlights: • Space heating/cooling, domestic hot water and electrical energy are provided by the system. • Two different users are investigated: fitness center and office. • The influence of the battery system on system economic performance is scarce. • Net metering contract is more profitable compared to simplified purchase/resale arrangement one. - Abstract: In this paper a dynamic simulation model and a thermo-economic analysis of a novel polygeneration system are presented. The system includes photovoltaic/thermal collectors coupled with a solar-assisted heat pump, an adsorption chiller and an electrical energy storage. The modelled plant supplies electrical energy, space heating and cooling and domestic hot water. The produced solar thermal energy is used during the winter to supply the heat pump evaporator, providing the required space heating. In summer, solar thermal energy is used to drive an adsorption chiller providing the required space cooling. All year long, solar thermal energy in excess, with respect to the space heating and cooling demand, is used to produce domestic hot water. The produced electrical energy is self-consumed by both user and system auxiliary equipment and/or supplied to the grid. The system model includes a detailed electrical energy model for user storage and exchange with the grid along with a detailed building model. This study is a continuation of previous works recently presented by the authors. In particular, the present paper focuses on the real electrical demands of several types of users and on the analysis of the comfort of building users. Differently from the works previously published by the authors, the present work bases the calculations on measured electrical demands of real users (fitness center and offices). The system performance is analyzed with two different electricity supply contracts: net metering and simplified purchase/resale arrangement. Daily, weekly and yearly results are presented. Finally, a

Efficiency calibration and coincidence summing correction for large arrays of NaI(Tl) detectors in soccer-ball and castle geometries

International Nuclear Information System (INIS)

Anil Kumar, G.; Mazumdar, I.; Gothe, D.A.

2009-01-01

Efficiency calibration and coincidence summing correction have been performed for two large arrays of NaI(Tl) detectors in two different configurations. They are, a compact array of 32 conical detectors of pentagonal and hexagonal shapes in soccer-ball geometry and an array of 14 straight hexagonal NaI(Tl) detectors in castle geometry. Both of these arrays provide a large solid angle of detection, leading to considerable coincidence summing of gamma rays. The present work aims to understand the effect of coincidence summing of gamma rays while determining the energy dependence of efficiencies of these two arrays. We have carried out extensive GEANT4 simulations with radio-nuclides that decay with a two-step cascade, considering both arrays in their realistic geometries. The absolute efficiencies have been simulated for gamma energies from 700 to 2800 keV using four different double-photon emitters, namely, 60 Co, 46 Sc, 94 Nb and 24 Na. The efficiencies so obtained have been corrected for coincidence summing using the method proposed by Vidmar et al. . The simulations have also been carried out for the same energies assuming mono-energetic point sources, for comparison. Experimental measurements have also been carried out using calibrated point sources of 137 Cs and 60 Co. The simulated and the experimental results are found to be in good agreement. This demonstrates the reliability of the correction method for efficiency calibration of two large arrays in very different configurations.

Efficiency calibration and coincidence summing correction for large arrays of NaI(Tl) detectors in soccer-ball and castle geometries

Energy Technology Data Exchange (ETDEWEB)

Anil Kumar, G., E-mail: anilg@tifr.res.i [Department of Nuclear and Atomic Physics, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005 (India); Mazumdar, I.; Gothe, D.A. [Department of Nuclear and Atomic Physics, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005 (India)

2009-11-21

Efficiency calibration and coincidence summing correction have been performed for two large arrays of NaI(Tl) detectors in two different configurations. They are, a compact array of 32 conical detectors of pentagonal and hexagonal shapes in soccer-ball geometry and an array of 14 straight hexagonal NaI(Tl) detectors in castle geometry. Both of these arrays provide a large solid angle of detection, leading to considerable coincidence summing of gamma rays. The present work aims to understand the effect of coincidence summing of gamma rays while determining the energy dependence of efficiencies of these two arrays. We have carried out extensive GEANT4 simulations with radio-nuclides that decay with a two-step cascade, considering both arrays in their realistic geometries. The absolute efficiencies have been simulated for gamma energies from 700 to 2800 keV using four different double-photon emitters, namely, {sup 60}Co, {sup 46}Sc, {sup 94}Nb and {sup 24}Na. The efficiencies so obtained have been corrected for coincidence summing using the method proposed by Vidmar et al. . The simulations have also been carried out for the same energies assuming mono-energetic point sources, for comparison. Experimental measurements have also been carried out using calibrated point sources of {sup 137}Cs and {sup 60}Co. The simulated and the experimental results are found to be in good agreement. This demonstrates the reliability of the correction method for efficiency calibration of two large arrays in very different configurations.

Increasing utilisation of district heating through absorption cooling technology; Oekat fjaerrvaermeutnyttjande med hjaelp av absorptionstekniken

Energy Technology Data Exchange (ETDEWEB)

Bjurstroem, Henrik; Ingvarsson, Paul; Zinko, Heimo

2010-10-15

The purpose of the research project presented in this report was to find ways to return a lower temperature from the generator of the chillers in a supply/return connection. The initial target is 40 deg C. Ideally, the absorption chiller and possible ulterior uses of the remaining heat in the heat carrier (the water flowing through the generator) should be as close as possible to a pure heat load. The hot-water driven absorption chillers used today to produce cooling in DH networks are exclusively so-called single-effect (Sweden) chillers with water and lithium bromide as working pair. This study aims at raising as much as possible the upper bounds on the absorption chiller capacity that may be connected to a DH network, by lowering the temperature at the outlet. To this end, several approaches have been used: - A search for alternative designs of the absorption chiller, focusing on commercially available and tested technology, both those yielding a large temperature decrease over the generator and those that may be operated at lower temperatures than the conventional solutions; - An examination of the impact of further uses of the remaining heat on temperature in the return line. larger. Smaller units are considered only if they can be used to illustrate a principle. As a complement to this investigation, a few other issues have been treated: - What temperature levels should a system actually be designed for? - The LAVA method to calculate the impact of supply and return temperatures in the DH network on the economics of power production is presented; - Interesting technical solutions using desiccant-aided evaporative cooling are shortly described; - The modern developments in the field of working pairs (refrigerant and absorbent) are reviewed. Assumptions made here are that there is a significant demand for cooling, and that the demand is large enough to justify operating the cogeneration plant at a load level exceeding its lowest acceptable part load rather than

The Event Communication Vector of Efficiency of Moroccan Large Companies

Directory of Open Access Journals (Sweden)

Najwa El Omari

2016-06-01

Full Text Available The event communication has for objective to give another dimension to the company or to the brand, by bringing it out of its daily life and by developing relations with its target public, around their centers of interests. It may be by sharing the same passions, by making live feelings to a group, by federating and by creating links; because today we need a more emotional and more real component. Since a few years, the event communication seems to be "revisited" by companies and appears to stand out as an alternative to media or other more traditional tools. For the upholders of the relationship marketing, this communication delivers “a social message which affects the spectator or the auditor in its inhalation to be a part of a social, sports or artistic community” (Perlstein and Picket, 1985. Therefore, we are going to expose our researches and would try to answer the following problem: "what is the impact of the event communication on the Moroccan large company, independently of any different parasite variable? ". The objective of our research is to try to make notions understand around the event communication, and especially the evaluation of its added value on the efficiency of the Moroccan large company. To try to answer these questions derived of our problem, our research will concentrate on: a first theoretical part around a set of concepts, a second part will be the object of an empirical study.

High-efficiency targeted editing of large viral genomes by RNA-guided nucleases.

Science.gov (United States)

Bi, Yanwei; Sun, Le; Gao, Dandan; Ding, Chen; Li, Zhihua; Li, Yadong; Cun, Wei; Li, Qihan

2014-05-01

A facile and efficient method for the precise editing of large viral genomes is required for the selection of attenuated vaccine strains and the construction of gene therapy vectors. The type II prokaryotic CRISPR-Cas (clustered regularly interspaced short palindromic repeats (CRISPR)-associated (Cas)) RNA-guided nuclease system can be introduced into host cells during viral replication. The CRISPR-Cas9 system robustly stimulates targeted double-stranded breaks in the genomes of DNA viruses, where the non-homologous end joining (NHEJ) and homology-directed repair (HDR) pathways can be exploited to introduce site-specific indels or insert heterologous genes with high frequency. Furthermore, CRISPR-Cas9 can specifically inhibit the replication of the original virus, thereby significantly increasing the abundance of the recombinant virus among progeny virus. As a result, purified recombinant virus can be obtained with only a single round of selection. In this study, we used recombinant adenovirus and type I herpes simplex virus as examples to demonstrate that the CRISPR-Cas9 system is a valuable tool for editing the genomes of large DNA viruses.

High-efficiency targeted editing of large viral genomes by RNA-guided nucleases.

Directory of Open Access Journals (Sweden)

Yanwei Bi

2014-05-01

Full Text Available A facile and efficient method for the precise editing of large viral genomes is required for the selection of attenuated vaccine strains and the construction of gene therapy vectors. The type II prokaryotic CRISPR-Cas (clustered regularly interspaced short palindromic repeats (CRISPR-associated (Cas RNA-guided nuclease system can be introduced into host cells during viral replication. The CRISPR-Cas9 system robustly stimulates targeted double-stranded breaks in the genomes of DNA viruses, where the non-homologous end joining (NHEJ and homology-directed repair (HDR pathways can be exploited to introduce site-specific indels or insert heterologous genes with high frequency. Furthermore, CRISPR-Cas9 can specifically inhibit the replication of the original virus, thereby significantly increasing the abundance of the recombinant virus among progeny virus. As a result, purified recombinant virus can be obtained with only a single round of selection. In this study, we used recombinant adenovirus and type I herpes simplex virus as examples to demonstrate that the CRISPR-Cas9 system is a valuable tool for editing the genomes of large DNA viruses.

Innovation-driven efficient development of the Longwangmiao Fm large-scale sulfur gas reservoir in Moxi block, Sichuan Basin

Directory of Open Access Journals (Sweden)

Xinhua Ma

2016-03-01

Full Text Available The Lower Cambrian Longwangmiao Fm gas reservoir in Moxi block of the Anyue Gas field, Sichuan Basin, is the largest single-sandbody integrated carbonate gas reservoir proved so far in China. Notwithstanding this reservoir's advantages like large-scale reserves and high single-well productivity, there are multiple complicated factors restricting its efficient development, such as a median content of hydrogen sulfide, low porosity and strong heterogeneity of fracture–cave formation, various modes of gas–water occurrences, and close relation between overpressure and stress sensitivity. Up till now, since only a few Cambrian large-scale carbonate gas reservoirs have ever been developed in the world, there still exists some blind spots especially about its exploration and production rules. Besides, as for large-scale sulfur gas reservoirs, the exploration and construction is costly, and production test in the early evaluation stage is severely limited, all of which will bring about great challenges in productivity construction and high potential risks. In this regard, combining with Chinese strategic demand of strengthening clean energy supply security, the PetroChina Southwest Oil & Gas Field Company has carried out researches and field tests for the purpose of providing high-production wells, optimizing development design, rapidly constructing high-quality productivity and upgrading HSE security in the Longwangmiao Fm gas reservoir in Moxi block. Through the innovations of technology and management mode within 3 years, this gas reservoir has been built into a modern large-scale gas field with high quality, high efficiency and high benefit, and its annual capacity is now up to over 100 × 108 m3, with a desirable production capacity and development indexes gained as originally anticipated. It has become a new model of large-scale gas reservoirs with efficient development, providing a reference for other types of gas reservoirs in China.

The performance of a temperature cascaded cogeneration system producing steam, cooling and dehumidification

KAUST Repository

Myat, Aung

2013-02-01

This paper discusses the performance of a temperature-cascaded cogeneration plant (TCCP), equipped with an efficient waste heat recovery system. The TCCP, also called a cogeneration system, produces four types of useful energy-namely, (i) electricity, (ii) steam, (iii) cooling and (iv) dehumidification-by utilizing single fuel source. The TCCP comprises a Capstone C-30 micro-turbine that generates nominal capacity of 26 kW of electricity, a compact and efficient waste heat recovery system and a host of waste-heat-activated devices, namely (i) a steam generator, (ii) an absorption chiller, (iii) an adsorption chiller and (iv) a multi-bed desiccant dehumidifier. The performance analysis was conducted under different operation conditions such as different exhaust gas temperatures. It was observed that energy utilization factor could be as high as 70% while fuel energy saving ratio was found to be 28%. © 2013 Desalination Publications.

New configurations of a heat recovery absorption heat pump integrated with a natural gas boiler for boiler efficiency improvement

International Nuclear Information System (INIS)

Qu, Ming; Abdelaziz, Omar; Yin, Hongxi

2014-01-01

Highlights: • Thermal and heat transfer models of absorption heat pumps driven by exhaust gas, hot water, or natural gas. • Natural gas boiler combustion model. • Heat exchanger for condensing. • Experimental data of a hot water absorption heat pump. • Economic assessment of heat recovery absorption heat pump for improving natural gas boilers. - Abstract: Conventional natural gas-fired boilers exhaust flue gas direct to the atmosphere at 150–200 °C, which, at such temperatures, contains large amount of energy and results in relatively low thermal efficiency ranging from 70% to 80%. Although condensing boilers for recovering the heat in the flue gas have been developed over the past 40 years, their present market share is still less than 25%. The major reason for this relatively slow acceptance is the limited improvement in the thermal efficiency of condensing boilers. In the condensing boiler, the temperature of the hot water return at the range of 50–60 °C, which is used to cool the flue gas, is very close to the dew point of the water vapor in the flue gas. Therefore, the latent heat, the majority of the waste heat in the flue gas, which is contained in the water vapor, cannot be recovered. This paper presents a new approach to improve boiler thermal efficiency by integrating absorption heat pumps with natural gas boilers for waste heat recovery (HRAHP). Three configurations of HRAHPs are introduced and discussed. The three configurations are modeled in detail to illustrate the significant thermal efficiency improvement they attain. Further, for conceptual proof and validation, an existing hot water-driven absorption chiller is operated as a heat pump at operating conditions similar to one of the devised configurations. An overall system performance and economic analysis are provided for decision-making and as evidence of the potential benefits. These three configurations of HRAHP provide a pathway to achieving realistic high-efficiency natural

Study on the simulation of heat pump heating and cooling systems to hospital building

International Nuclear Information System (INIS)

Choi, Young Don; Han, Seong Ho; Cho, Sung Hwan; Kim, Du Sung; Um, Chul Jun

2008-01-01

In Korea, air source heat pump system is less efficient than conventional heat source facilities, because the air temperature in winter season is so low that COP of air source heat pump system drops below 3.0. Therefore, the study on the application of heat pump heating and cooling systems is crucial for the efficient popularization of heat pump. In this work, we present the dynamic analysis of energy consumption for the large hospital building by heat resistance-capacitance method. The system simulation of water storage air source heat pump is additionally performed by changing sizes and locations of the hospital building. The computed results show that energy cost of water storage air source heat pump is low, so it is more economical than absorption chiller and heater

Roll-coating fabrication of flexible large area small molecule solar cells with power conversion efficiency exceeding 1%

DEFF Research Database (Denmark)

Liu, Wenqing; Liu, Shiyong; Zawacka, Natalia Klaudia

2014-01-01

All solution-processed flexible large area small molecule bulk heterojunction solar cells were fabricated via roll-coating technology. Our devices were produced from slot-die coating on a lab-scale mini roll-coater under ambient conditions without the use of spin-coating or vacuum evaporation.......01%, combined with an open circuit voltage of 0.73 V, a short-circuit current density of 3.13 mA cm (2) and a fill factor of 44% were obtained for the device with SM1, which was the first example reported for efficient roll-coating fabrication of flexible large area small molecule solar cells with PCE exceeding...... methods. Four diketopyrrolopyrrole based small molecules (SMs 1-4) were utilized as electron donors with (6,6)phenyl- C61-butyric acid methyl ester as an acceptor and their photovoltaic performances based on roll-coated devices were investigated. The best power conversion efficiency (PCE) of 1...

Energy-efficient electrical machines by new materials. Superconductivity in large electrical machines

International Nuclear Information System (INIS)

Frauenhofer, Joachim; Arndt, Tabea; Grundmann, Joern

2013-01-01

The implementation of superconducting materials in high-power electrical machines results in significant advantages regarding efficiency, size and dynamic behavior when compared to conventional machines. The application of HTS (high-temperature superconductors) in electrical machines allows significantly higher power densities to be achieved for synchronous machines. In order to gain experience with the new technology, Siemens carried out a series of development projects. A 400 kW model motor for the verification of a concept for the new technology was followed by a 4000 kV A generator as highspeed machine - as well as a low-speed 4000 kW propeller motor with high torque. The 4000 kVA generator is still employed to carry out long-term tests and to check components. Superconducting machines have significantly lower weight and envelope dimensions compared to conventional machines, and for this reason alone, they utilize resources better. At the same time, operating losses are slashed to about half and the efficiency increases. Beyond this, they set themselves apart as a result of their special features in operation, such as high overload capability, stiff alternating load behavior and low noise. HTS machines provide significant advantages where the reduction of footprint, weight and losses or the improved dynamic behavior results in significant improvements of the overall system. Propeller motors and generators,for ships, offshore plants, in wind turbine and hydroelectric plants and in large power stations are just some examples. HTS machines can therefore play a significant role when it comes to efficiently using resources and energy as well as reducing the CO 2 emissions.

The green computing book tackling energy efficiency at large scale

CERN Document Server

Feng, Wu-chun

2014-01-01

Low-Power, Massively Parallel, Energy-Efficient Supercomputers The Blue Gene TeamCompiler-Driven Energy Efficiency Mahmut Kandemir and Shekhar Srikantaiah An Adaptive Run-Time System for Improving Energy Efficiency Chung-Hsing Hsu, Wu-chun Feng, and Stephen W. PooleEnergy-Efficient Multithreading through Run-Time Adaptation Exploring Trade-Offs between Energy Savings and Reliability in Storage Systems Ali R. Butt, Puranjoy Bhattacharjee, Guanying Wang, and Chris GniadyCross-Layer Power Management Zhikui Wang and Parthasarathy Ranganathan Energy-Efficient Virtualized Systems Ripal Nathuji and K

Highly efficient blue organic light emitting device using indium-free transparent anode Ga:ZnO with scalability for large area coating

International Nuclear Information System (INIS)

Wang Liang; Matson, Dean W.; Polikarpov, Evgueni; Swensen, James S.; Bonham, Charles C.; Cosimbescu, Lelia; Gaspar, Daniel J.; Padmaperuma, Asanga B.; Berry, Joseph J.; Ginley, David S.

2010-01-01

Organic light emitting devices have been achieved with an indium-free transparent anode, Ga doped ZnO (GZO). A large area coating technique was used (RF magnetron sputtering) to deposit the GZO films onto glass. The respective organic light emitting devices exhibited an operational voltage of 3.7 V, an external quantum efficiency of 17%, and a power efficiency of 39 lm/W at a current density of 1 mA/cm 2 . These parameters are well within acceptable standards for blue OLEDs to generate a white light with high enough brightness for general lighting applications. It is expected that high-efficiency, long-lifetime, large area, and cost-effective white OLEDs can be made with these indium-free anode materials.

Efficient Meshfree Large Deformation Simulation of Rainfall Induced Soil Slope Failure

Science.gov (United States)

Wang, Dongdong; Li, Ling

2010-05-01

An efficient Lagrangian Galerkin meshfree framework is presented for large deformation simulation of rainfall-induced soil slope failure. Detailed coupled soil-rainfall seepage equations are given for the proposed formulation. This nonlinear meshfree formulation is featured by the Lagrangian stabilized conforming nodal integration method where the low cost nature of nodal integration approach is kept and at the same time the numerical stability is maintained. The initiation and evolution of progressive failure in the soil slope is modeled by the coupled constitutive equations of isotropic damage and Drucker-Prager pressure-dependent plasticity. The gradient smoothing in the stabilized conforming integration also serves as a non-local regularization of material instability and consequently the present method is capable of effectively capture the shear band failure. The efficacy of the present method is demonstrated by simulating the rainfall-induced failure of two typical soil slopes.

Design of a Generic and Flexible Data Structure for Efficient Formulation of Large Scale Network Problems

DEFF Research Database (Denmark)

Quaglia, Alberto; Sarup, Bent; Sin, Gürkan

2013-01-01

structure for efficient formulation of enterprise-wide optimization problems is presented. Through the integration of the described data structure in our synthesis and design framework, the problem formulation workflow is automated in a software tool, reducing time and resources needed to formulate large......The formulation of Enterprise-Wide Optimization (EWO) problems as mixed integer nonlinear programming requires collecting, consolidating and systematizing large amount of data, coming from different sources and specific to different disciplines. In this manuscript, a generic and flexible data...... problems, while ensuring at the same time data consistency and quality at the application stage....

Efficient querying of large process model repositories

NARCIS (Netherlands)

Jin, Tao; Wang, Jianmin; La Rosa, M.; Hofstede, ter A.H.M.; Wen, Lijie

2013-01-01

Recent years have seen an increased uptake of business process management technology in industries. This has resulted in organizations trying to manage large collections of business process models. One of the challenges facing these organizations concerns the retrieval of models from large business

An Efficient Approach to Mining Maximal Contiguous Frequent Patterns from Large DNA Sequence Databases

Directory of Open Access Journals (Sweden)

Md. Rezaul Karim

2012-03-01

Full Text Available Mining interesting patterns from DNA sequences is one of the most challenging tasks in bioinformatics and computational biology. Maximal contiguous frequent patterns are preferable for expressing the function and structure of DNA sequences and hence can capture the common data characteristics among related sequences. Biologists are interested in finding frequent orderly arrangements of motifs that are responsible for similar expression of a group of genes. In order to reduce mining time and complexity, however, most existing sequence mining algorithms either focus on finding short DNA sequences or require explicit specification of sequence lengths in advance. The challenge is to find longer sequences without specifying sequence lengths in advance. In this paper, we propose an efficient approach to mining maximal contiguous frequent patterns from large DNA sequence datasets. The experimental results show that our proposed approach is memory-efficient and mines maximal contiguous frequent patterns within a reasonable time.

Solar air-conditioning. Proceedings

Energy Technology Data Exchange (ETDEWEB)

NONE

2009-07-01

European countries (Ignasi Gurruchaga); (21) Optimisation potential of a large solar adsorption cooling plant (Antoine Dalibard); (22) Planning, commissioning and practical experience with first summer of operation of a cost effective solar air conditioning system for a Canteen at Munich Airport (Carsten Hindenburg); (23) Energy and economic performance of solar cooling systems (Ursula Eicker); (24) Solar-driven adsorption chiller controlled by hot and cooling water temperature (Jan Albers); (25) Comparative results of monitored solar assisted heating and cooling installations (Wolfram Sparber); (26) Heating and cooling with a small scale solar driven adsorption chiller combined with a borehole system - recent results (Tomas Nunez); (27) Solar heating and cooling - Town hall Gleisdorf (Alexander Thuer); (28) Solar dessicant cooling system operating in Palermo (Italy): Results and Validation of simulation models (Marco Beccali); (29) The application of a liquid-dessicant air conditioner to solar cooling (Andrew Lowenstein); (30) A compact solid adsorption chiller for solar air conditioning (Robert Critoph); (31) Development of a two-stage absorption chiller for solar-assisted cooling and heating (Manuel Riepl); (32) Ionic liquids - a promising solution for solar absorption chillers? (Annett Kuehn);(33) Parabolic trough design optimization for high temperature lift solar cooling applications (Marcello Aprile); (34) Tentative R and D program forgetting adsorbents effective for solar air conditioning (Yury Aristov); (35) An energy efficient solar driven two-stage rotary desiccant cooling system: Experiment and case study (Yanjun Dai); (36) Performance of a flat plate collector-regenerator that uses earth-to-air heat exchangers for regeneration of water-lithium chloride solution in a solar coolant plant (Roberto Bruno); (37) 350 KW of dual solar cooling for optimal flexibility and economic performance (Roel de Coninck); (38) Global performance of a solar absorption cooling

Cost-efficient foundation structures for large offshore wind farms

International Nuclear Information System (INIS)

Birch, C.; Gormsen, C.; Lyngesen, S.; Rasmussen, J. L.; Juhl, H.

1997-01-01

This paper presents the results of the development of a cost-efficient foundation for large (1.5 MW) offshore wind farms at water depth of 5 to 11 m. Previously, medium sized wind turbines (500 kW) in Denmark have been installed offshore at water depths of approximately 5 m on concrete gravity foundations. The installation of larger turbines at greater depth does, however, hold great promise in terms of wind environment and environmental considerations. The costs of a traditional gravity foundation at these increased water depths is expected to be prohibitive, and the aim of the project has been to reduce the foundations costs in general. This paper describes the theoretical basis for the geotechnical and structural design of three alternative concepts and presents an optimised layout of each based on a research and development project. The basis has been a wind farm consisting of 100 turbines. The R and D project has been undertaken by the consulting engineers Nellemann, Nielsen and Rauschenberger A/S (Gravity foundation), LICengineering A/S (Mono pile) and Ramboell (Tripod) in co-operation with the Danish utility engineering companies Elkraft and Elsamprojekt A/S. The project was partly financed by the participants and by the Danish Energy Agency through their 1996 Energy Research Programme (EFP-96). (au) 18 refs

Site dependent factors affecting the economic feasibility of solar powered absorption cooling

Science.gov (United States)

Bartlett, J. C.

1978-01-01

A procedure was developed to evaluate the cost effectiveness of combining an absorption cycle chiller with a solar energy system. A basic assumption of the procedure is that a solar energy system exists for meeting the heating load of the building, and that the building must be cooled. The decision to be made is to either cool the building with a conventional vapor compression cycle chiller or to use the existing solar energy system to provide a heat input to the absorption chiller. Two methods of meeting the cooling load not supplied by solar energy were considered. In the first method, heat is supplied to the absorption chiller by a boiler using fossil fuel. In the second method, the load not met by solar energy is net by a conventional vapor compression chiller. In addition, the procedure can consider waste heat as another form of auxiliary energy. Commercial applications of solar cooling with an absorption chiller were found to be more cost effective than the residential applications. In general, it was found that the larger the chiller, the more economically feasible it would be. Also, it was found that a conventional vapor compression chiller is a viable alternative for the auxiliary cooling source, especially for the larger chillers. The results of the analysis gives a relative rating of the sites considered as to their economic feasibility of solar cooling.

Large-Grain Tin-Rich Perovskite Films for Efficient Solar Cells via Metal Alloying Technique.

Science.gov (United States)

Tavakoli, Mohammad Mahdi; Zakeeruddin, Shaik Mohammed; Grätzel, Michael; Fan, Zhiyong

2018-03-01

Fast research progress on lead halide perovskite solar cells has been achieved in the past a few years. However, the presence of lead (Pb) in perovskite composition as a toxic element still remains a major issue for large-scale deployment. In this work, a novel and facile technique is presented to fabricate tin (Sn)-rich perovskite film using metal precursors and an alloying technique. Herein, the perovskite films are formed as a result of the reaction between Sn/Pb binary alloy metal precursors and methylammonium iodide (MAI) vapor in a chemical vapor deposition process carried out at 185 °C. It is found that in this approach the Pb/Sn precursors are first converted to (Pb/Sn)I 2 and further reaction with MAI vapor leads to the formation of perovskite films. By using Pb-Sn eutectic alloy, perovskite films with large grain sizes up to 5 µm can be grown directly from liquid phase metal. Consequently, using an alloying technique and this unique growth mechanism, a less-toxic and efficient perovskite solar cell with a power conversion efficiency (PCE) of 14.04% is demonstrated, while pure Sn and Pb perovskite solar cells prepared in this manner yield PCEs of 4.62% and 14.21%, respectively. It is found that this alloying technique can open up a new direction to further explore different alloy systems (binary or ternary alloys) with even lower melting point. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Operational Efficiency and Productivity Improvement Initiatives in a Large Cardiac Catheterization Laboratory.

Science.gov (United States)

Reed, Grant W; Hantz, Scott; Cunningham, Rebecca; Krishnaswamy, Amar; Ellis, Stephen G; Khot, Umesh; Rak, Joe; Kapadia, Samir R

2018-02-26

This study sought to report outcomes from an efficiency improvement project in a large cardiac cath lab. Operational inefficiencies are common in the cath lab, yet solutions are challenging. A detailed report describing and providing solutions for these inefficiencies may be valuable in guiding improvements in productivity. In this observational study, the authors report metrics of efficiency before and after a cath lab quality improvement program in June 2014. Main outcomes included lab room start times, room turnaround times, laboratory use, and employee satisfaction. Time series analysis was used to assess trend over time. Chi-square testing and analysis of variance were used to assess change before and after the initiative. The principal changes included implementation of a pyramidal nursing schedule, increased use of an electronic scheduling system, and increased utilization of a preparation and recovery area. Comparing before with after the program, start times improved an average of 17 min, and on-time starts improved from 61.8% to 81.7% (p = 0.0024). Turnaround times improved from 20.5 min to 16.4 min (trend p productivity. This knowledge may be helpful in assisting other cath labs in similar efficiency improvement initiatives. Copyright © 2018 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Current fluctuations in quantum absorption refrigerators

Science.gov (United States)

Segal, Dvira

2018-05-01

Absorption refrigerators transfer thermal energy from a cold bath to a hot bath without input power by utilizing heat from an additional "work" reservoir. Particularly interesting is a three-level design for a quantum absorption refrigerator, which can be optimized to reach the maximal (Carnot) cooling efficiency. Previous studies of three-level chillers focused on the behavior of the averaged cooling current. Here, we go beyond that and study the full counting statistics of heat exchange in a three-level chiller model. We explain how to obtain the complete cumulant generating function of the refrigerator in a steady state, then derive a partial cumulant generating function, which yields closed-form expressions for both the averaged cooling current and its noise. Our analytical results and simulations are beneficial for the design of nanoscale engines and cooling systems far from equilibrium, with their performance optimized according to different criteria, efficiency, power, fluctuations, and dissipation.

Efficient assembly of de novo human artificial chromosomes from large genomic loci

Directory of Open Access Journals (Sweden)

Stromberg Gregory

2005-07-01

Full Text Available Abstract Background Human Artificial Chromosomes (HACs are potentially useful vectors for gene transfer studies and for functional annotation of the genome because of their suitability for cloning, manipulating and transferring large segments of the genome. However, development of HACs for the transfer of large genomic loci into mammalian cells has been limited by difficulties in manipulating high-molecular weight DNA, as well as by the low overall frequencies of de novo HAC formation. Indeed, to date, only a small number of large (>100 kb genomic loci have been reported to be successfully packaged into de novo HACs. Results We have developed novel methodologies to enable efficient assembly of HAC vectors containing any genomic locus of interest. We report here the creation of a novel, bimolecular system based on bacterial artificial chromosomes (BACs for the construction of HACs incorporating any defined genomic region. We have utilized this vector system to rapidly design, construct and validate multiple de novo HACs containing large (100–200 kb genomic loci including therapeutically significant genes for human growth hormone (HGH, polycystic kidney disease (PKD1 and ß-globin. We report significant differences in the ability of different genomic loci to support de novo HAC formation, suggesting possible effects of cis-acting genomic elements. Finally, as a proof of principle, we have observed sustained ß-globin gene expression from HACs incorporating the entire 200 kb ß-globin genomic locus for over 90 days in the absence of selection. Conclusion Taken together, these results are significant for the development of HAC vector technology, as they enable high-throughput assembly and functional validation of HACs containing any large genomic locus. We have evaluated the impact of different genomic loci on the frequency of HAC formation and identified segments of genomic DNA that appear to facilitate de novo HAC formation. These genomic loci

Hi-Corrector: a fast, scalable and memory-efficient package for normalizing large-scale Hi-C data.

Science.gov (United States)

Li, Wenyuan; Gong, Ke; Li, Qingjiao; Alber, Frank; Zhou, Xianghong Jasmine

2015-03-15

Genome-wide proximity ligation assays, e.g. Hi-C and its variant TCC, have recently become important tools to study spatial genome organization. Removing biases from chromatin contact matrices generated by such techniques is a critical preprocessing step of subsequent analyses. The continuing decline of sequencing costs has led to an ever-improving resolution of the Hi-C data, resulting in very large matrices of chromatin contacts. Such large-size matrices, however, pose a great challenge on the memory usage and speed of its normalization. Therefore, there is an urgent need for fast and memory-efficient methods for normalization of Hi-C data. We developed Hi-Corrector, an easy-to-use, open source implementation of the Hi-C data normalization algorithm. Its salient features are (i) scalability-the software is capable of normalizing Hi-C data of any size in reasonable times; (ii) memory efficiency-the sequential version can run on any single computer with very limited memory, no matter how little; (iii) fast speed-the parallel version can run very fast on multiple computing nodes with limited local memory. The sequential version is implemented in ANSI C and can be easily compiled on any system; the parallel version is implemented in ANSI C with the MPI library (a standardized and portable parallel environment designed for solving large-scale scientific problems). The package is freely available at http://zhoulab.usc.edu/Hi-Corrector/. © The Author 2014. Published by Oxford University Press.

Growing vertical ZnO nanorod arrays within graphite: efficient isolation of large size and high quality single-layer graphene.

Science.gov (United States)

Ding, Ling; E, Yifeng; Fan, Louzhen; Yang, Shihe

2013-07-18

We report a unique strategy for efficiently exfoliating large size and high quality single-layer graphene directly from graphite into DMF dispersions by growing ZnO nanorod arrays between the graphene layers in graphite.

A highly efficient multi-core algorithm for clustering extremely large datasets

Directory of Open Access Journals (Sweden)

Kraus Johann M

2010-04-01

Full Text Available Abstract Background In recent years, the demand for computational power in computational biology has increased due to rapidly growing data sets from microarray and other high-throughput technologies. This demand is likely to increase. Standard algorithms for analyzing data, such as cluster algorithms, need to be parallelized for fast processing. Unfortunately, most approaches for parallelizing algorithms largely rely on network communication protocols connecting and requiring multiple computers. One answer to this problem is to utilize the intrinsic capabilities in current multi-core hardware to distribute the tasks among the different cores of one computer. Results We introduce a multi-core parallelization of the k-means and k-modes cluster algorithms based on the design principles of transactional memory for clustering gene expression microarray type data and categorial SNP data. Our new shared memory parallel algorithms show to be highly efficient. We demonstrate their computational power and show their utility in cluster stability and sensitivity analysis employing repeated runs with slightly changed parameters. Computation speed of our Java based algorithm was increased by a factor of 10 for large data sets while preserving computational accuracy compared to single-core implementations and a recently published network based parallelization. Conclusions Most desktop computers and even notebooks provide at least dual-core processors. Our multi-core algorithms show that using modern algorithmic concepts, parallelization makes it possible to perform even such laborious tasks as cluster sensitivity and cluster number estimation on the laboratory computer.

Doubling the annual coefficient of performance of air-conditioning units by taking advantage of small temperature lifts; Verdoppelung der Jahresarbeitszahl von Klimakaelteanlagen durch Ausnuetzung eines kleinen Temperaturhubes

Energy Technology Data Exchange (ETDEWEB)

Wellig, B.; Kegel, B.; Meier, M.

2006-07-01

The seasonal performance factor (SPF) of chilled water systems (CWS) is closely related to the temperature lift, i.e. the difference between the temperature of the heat source and the heat sink. In many applications in building services engineering, a temperature lift of 10-20 K is in principle sufficient. However, the potential for highly efficient refrigerating systems is not fully exploited as standard chillers are designed for lifts of 30-60 K. The exergy analysis of typical CWS shows that the external exergy losses are greater than the exergy losses of the chiller. The second-law (or exergetic) efficiency is usually far below 10%. It is therefore important to avoid unnecessarily high temperature lifts. Measurements on refrigeration systems in two office buildings have shown that even in state-of-the-art CWS, considerable energy savings (up to 50%) can be achieved by persistent use of small temperature lifts. However, SPF-values around 5-6 can hardly be exceeded in systems with electric driven chillers. SPFs higher than 10 or even above 20 can only be reached with optimized free cooling processes. Basic decisions, which ultimately lead to CWS with unnecessarily high temperature lifts, are taken in the early project stages. Therefore, this study presents guidelines for the design and operation of CWS with small temperature lifts. The implementation of these simple measures will lead to a considerable reduction of energy consumption and operating costs. (author)

Roll-to-Roll printed large-area all-polymer solar cells with 5% efficiency based on a low crystallinity conjugated polymer blend

Science.gov (United States)

Gu, Xiaodan; Zhou, Yan; Gu, Kevin; Kurosawa, Tadanori; Yan, Hongping; Wang, Cheng; Toney, Micheal; Bao, Zhenan

The challenge of continuous printing in high efficiency large-area organic solar cells is a key limiting factor for their widespread adoption. We present a materials design concept for achieving large-area, solution coated all-polymer bulk heterojunction (BHJ) solar cells with stable phase separation morphology between the donor and acceptor. The key concept lies in inhibiting strong crystallization of donor and acceptor polymers, thus forming intermixed, low crystallinity and mostly amorphous blends. Based on experiments using donors and acceptors with different degree of crystallinity, our results showed that microphase separated donor and acceptor domain sizes are inversely proportional to the crystallinity of the conjugated polymers. This methodology of using low crystallinity donors and acceptors has the added benefit of forming a consistent and robust morphology that is insensitive to different processing conditions, allowing one to easily scale up the printing process from a small scale solution shearing coater to a large-scale continuous roll-to-roll (R2R) printer. We were able to continuously roll-to-roll slot die print large area all-polymer solar cells with power conversion efficiencies of 5%, with combined cell area up to 10 cm2. This is among the highest efficiencies realized with R2R coated active layer organic materials on flexible substrate. DOE BRIDGE sunshot program. Office of Naval Research.

Large area flexible polymer solar cells with high efficiency enabled by imprinted Ag grid and modified buffer layer

International Nuclear Information System (INIS)

Lu, Shudi; Lin, Jie; Liu, Kong; Yue, Shizhong; Ren, Kuankuan; Tan, Furui; Wang, Zhijie; Jin, Peng; Qu, Shengchun; Wang, Zhanguo

2017-01-01

To take a full advantage of polymer semiconductors on realization of large-area flexible photovoltaic devices, herein, we fabricate polymer solar cells on the basis of polyethylene terephthalate (PET) with imprinted Ag grid as transparent electrode. The key fabrication procedure is the adoption of a modified PEDOT:PSS (PH1000) solution for spin-coating the buffer layer to form a compact contact with the substrate. In comparison with the devices with intrinsic PEDOT:PSS buffer layer, the advanced devices present a much higher efficiency of 6.51%, even in a large device area of 2.25 cm"2. Subsequent characterizations reveal that such devices show an impressive performance stability as the bending angle is enlarged to 180° and bending time is up to 1000 cycles. Not only providing a general methodology to construct high efficient and flexible polymer solar cells, this paper also involves deep insights on device working mechanism in bending conditions.

Solar cooling - comparative study between thermal and electrical use in industrial buildings

Science.gov (United States)

Badea, N.; Badea, G. V.; Epureanu, A.; Frumuşanu, G.

2016-08-01

The increase in the share of renewable energy sources together with the emphasis on the need for energy security bring to a spotlight the field of trigeneration autonomous microsystems, as a solution to cover the energy consumptions, not only for isolated industrial buildings, but also for industrial buildings located in urban areas. The use of solar energy for cooling has been taken into account to offer a cooling comfort in the building. Cooling and air- conditioned production are current applications promoting the use of solar energy technologies. Solar cooling systems can be classified, depending on the used energy, in electrical systems using mechanical compression chillers and systems using thermal compression by absorption or adsorption. This comparative study presents the main strengths and weaknesses of solar cooling obtained: i) through the transformation of heat resulted from thermal solar panels combined with adsorption chillers, and ii) through the multiple conversion of electricity - photovoltaic panels - battery - inverter - combined with mechanical compression chillers. Both solutions are analyzed from the standpoints of energy efficiency, dynamic performances (demand response), and costs sizes. At the end of the paper, experimental results obtained in the climatic condition of Galafi city, Romania, are presented.

Productivity and efficiency of economic activity of the Lower Silesia's large area farms in comparison with other large area farms in Poland

Directory of Open Access Journals (Sweden)

Stanisław Minta

2009-01-01

Full Text Available The paper shows economical and financial situation of the agricultural companies which have most of the grounds in lease. Analysed objects were settled on Lower Silesia (the province in the south – west Poland. The main part of the results of research was about productivity and efficiency of economic resources in these objects. The research was made in years 2000-2002. The results of research in analyzed Lower Silesia’s companies were compared with the best Polish large area farms in order of law and organisation forms: leased farms, private farms and partnerships of Polish public agency AWRSP.

Aerial radiation survey techniques for efficient characterization of large areas

International Nuclear Information System (INIS)

Sydelko, T.; Riedhauser, S.

2006-01-01

Full text: Accidental or intentional releases of radioactive isotopes over potentially very large surface areas can pose serious health risks to humans and ecological receptors. Timely and appropriate responses to these releases depend upon rapid and accurate characterization of impacted areas. These characterization efforts can be adversely impacted by heavy vegetation, rugged terrain, urban environments, and the presence of unknown levels of radioactivity. Aerial survey techniques have proven highly successful in measuring gamma emissions from radiological contaminates of concern quickly, efficiently, and safely. Examples of accidental releases include the unintentional distribution of uranium mining ores during transportation, the loss of uranium processing and waste materials, unintentional nuclear power plant emissions into the atmosphere, and the distribution of isotopes during major flooding events such as the one recently occurring in New Orleans. Intentional releases have occurred during the use of deleted uranium ammunition test firing and war time use by military organizations. The threat of radiological dispersion device (dirty bomb) use by terrorists is currently a major concern of many major cities worldwide. The U.S. Department of Energy, in cooperation with its Remote Sensing Laboratory and Argonne National Laboratory, has developed a sophisticated aerial measurement system for identifying the locations, types, and quantities of gamma emitting radionuclides over extremely large areas. Helicopter mounted Nal detectors are flown at low altitude and constant speed along parallel paths measuring the full spectrum of gamma activity. Analytical procedures are capable of distinguishing between radiological contamination and changes in natural background emissions. Mapped and tabular results of these accurate, timely and cost effective aerial gamma radiation surveys can be used to assist with emergency response actions, if necessary, and to focus more

Exergy analysis and optimization of a thermal management system with phase change material for hybrid electric vehicles

International Nuclear Information System (INIS)

Javani, N.; Dincer, I.; Naterer, G.F.; Yilbas, B.S.

2014-01-01

In the present study, energy and exergy analyses are conducted to investigate a new cooling system of hybrid electric vehicles (HEVs). A latent heat thermal energy storage system is integrated with an active refrigeration cycle where octadecane is selected as the phase change material (PCM). The liquid cooling system flows through the chiller following a conventional vapor compression cooling cycle. The latent heat shell and the tube heat exchanger operate in parallel with the chiller and a fraction of coolant enters the heat exchanger and, therefore, decreases the heat load of the chiller, leading to a lower work required by the compressor. The exergy destruction rate and the exergy efficiency of each component in a hybrid thermal management system (TMS) are calculated. In addition, the effects of parameters such as the fraction of coolant entering the heat storage system (PCM mass fraction), evaporator temperature, and compressor pressure ratio on the system performance are investigated. The findings of the exergy analysis reveal that the overall exergy efficiency of the system with PCM presence is 31%, having the largest exergy destruction rate of 0.4 kW and the heat exchangers have lower exergy efficiency as compared to other components. In addition, the results of the parametric study show that an increase in PCM mass fraction results in an increase in exergy efficiency of the system. An environmental impact assessment is also conducted and the results show that an increase in exergy efficiency of the cooling system reduces greenhouse gasses and also increases the sustainability of the system. Moreover, a multi-objective optimization using the genetic algorithm is performed by incorporating two objective functions, namely exergy efficiency to be maximized and total cost rate of the system to be minimized. A Pareto frontier is obtained and a single desirable optimal solution is selected based on LINMAP decision-making process. The results show that the maximum

Performance analysis and optimization of power plants with gas turbines

Science.gov (United States)

Besharati-Givi, Maryam

The gas turbine is one of the most important applications for power generation. The purpose of this research is performance analysis and optimization of power plants by using different design systems at different operation conditions. In this research, accurate efficiency calculation and finding optimum values of efficiency for design of chiller inlet cooling and blade cooled gas turbine are investigated. This research shows how it is possible to find the optimum design for different operation conditions, like ambient temperature, relative humidity, turbine inlet temperature, and compressor pressure ratio. The simulated designs include the chiller, with varied COP and fogging cooling for a compressor. In addition, the overall thermal efficiency is improved by adding some design systems like reheat and regenerative heating. The other goal of this research focuses on the blade-cooled gas turbine for higher turbine inlet temperature, and consequently, higher efficiency. New film cooling equations, along with changing film cooling effectiveness for optimum cooling air requirement at the first-stage blades, and an internal and trailing edge cooling for the second stage, are innovated for optimal efficiency calculation. This research sets the groundwork for using the optimum value of efficiency calculation, while using inlet cooling and blade cooling designs. In the final step, the designed systems in the gas cycles are combined with a steam cycle for performance improvement.

Numerical simulation of energy efficiency measures: control and operational strategies

International Nuclear Information System (INIS)

Ardehali, M. M.

2006-01-01

The inherent limitation in performance of building envelop components and heating ventilating and air conditioning (HVAC) equipment necessitates the examination of operational strategies for improvement in energy-efficient operation of buildings. Due to the ease of installation and increasing availability of electronic controllers, operational strategies that could be programmed are of particular interest. The Iowa Energy Center in the US has taken the initiative to conduct the necessary assessment of current HVAC technology and the commonly-used operational strategies for commercial and industrial buildings, as applied to the midwestern part of the country, with weather and energy cost data for Des Moines, Iowa. The first part of this study focused on the energy consumption and cost effectiveness of HVAC systems. The objectives of the second part is concerned with examination of various operational strategies, namely, night purge (NP), fan optimum start and stop (OSS), condenser water reset (CWR), and chilled water reset (CHWR) applied to order and newer-type commercial office buildings. The indoor air quality requirement are met and the latest applicable energy rates from local utility companies are used. The results show that, in general, NP is not an effective strategy in buildings with low thermal mass storage, OSS reduced fan energy, and CWR and CHWR could be effective and require chillers with multi-stage unloading characteristics. The most operationally efficient strategies are the combination of OSS, CWR, and CHWR for the older-type building, and OSS for the newer-type building. Economically, the most effective is the OSS strategy for the older-type building and the CHWR strategy for the newer-type building.(Author)

Focused ultrasound-facilitated brain drug delivery using optimized nanodroplets: vaporization efficiency dictates large molecular delivery

Science.gov (United States)

Wu, Shih-Ying; Fix, Samantha M.; Arena, Christopher B.; Chen, Cherry C.; Zheng, Wenlan; Olumolade, Oluyemi O.; Papadopoulou, Virginie; Novell, Anthony; Dayton, Paul A.; Konofagou, Elisa E.

2018-02-01

Focused ultrasound with nanodroplets could facilitate localized drug delivery after vaporization with potentially improved in vivo stability, drug payload, and minimal interference outside of the focal zone compared with microbubbles. While the feasibility of blood-brain barrier (BBB) opening using nanodroplets has been previously reported, characterization of the associated delivery has not been achieved. It was hypothesized that the outcome of drug delivery was associated with the droplet’s sensitivity to acoustic energy, and can be modulated with the boiling point of the liquid core. Therefore, in this study, octafluoropropane (OFP) and decafluorobutane (DFB) nanodroplets were used both in vitro for assessing their relative vaporization efficiency with high-speed microscopy, and in vivo for delivering molecules with a size relevant to proteins (40 kDa dextran) to the murine brain. It was found that at low pressures (300-450 kPa), OFP droplets vaporized into a greater number of microbubbles compared to DFB droplets at higher pressures (750-900 kPa) in the in vitro study. In the in vivo study, successful delivery was achieved with OFP droplets at 300 kPa and 450 kPa without evidence of cavitation damage using ¼ dosage, compared to DFB droplets at 900 kPa where histology indicated tissue damage due to inertial cavitation. In conclusion, the vaporization efficiency of nanodroplets positively impacted the amount of molecules delivered to the brain. The OFP droplets due to the higher vaporization efficiency served as better acoustic agents to deliver large molecules efficiently to the brain compared with the DFB droplets.

Using memory-efficient algorithm for large-scale time-domain modeling of surface plasmon polaritons propagation in organic light emitting diodes

Science.gov (United States)

Zakirov, Andrey; Belousov, Sergei; Valuev, Ilya; Levchenko, Vadim; Perepelkina, Anastasia; Zempo, Yasunari

2017-10-01

We demonstrate an efficient approach to numerical modeling of optical properties of large-scale structures with typical dimensions much greater than the wavelength of light. For this purpose, we use the finite-difference time-domain (FDTD) method enhanced with a memory efficient Locally Recursive non-Locally Asynchronous (LRnLA) algorithm called DiamondTorre and implemented for General Purpose Graphical Processing Units (GPGPU) architecture. We apply our approach to simulation of optical properties of organic light emitting diodes (OLEDs), which is an essential step in the process of designing OLEDs with improved efficiency. Specifically, we consider a problem of excitation and propagation of surface plasmon polaritons (SPPs) in a typical OLED, which is a challenging task given that SPP decay length can be about two orders of magnitude greater than the wavelength of excitation. We show that with our approach it is possible to extend the simulated volume size sufficiently so that SPP decay dynamics is accounted for. We further consider an OLED with periodically corrugated metallic cathode and show how the SPP decay length can be greatly reduced due to scattering off the corrugation. Ultimately, we compare the performance of our algorithm to the conventional FDTD and demonstrate that our approach can efficiently be used for large-scale FDTD simulations with the use of only a single GPGPU-powered workstation, which is not practically feasible with the conventional FDTD.

An efficient top-down approach for the fabrication of large-aspect-ratio g-C3N4 nanosheets with enhanced photocatalytic activities.

Science.gov (United States)

Tong, Jincheng; Zhang, Li; Li, Fei; Li, Mingming; Cao, Shaokui

2015-09-28

Graphitic carbon nitride (g-C3N4) nanosheets with large aspect ratios were fabricated from bulk g-C3N4 through an efficient top-down approach of moderate disintegration-exfoliation using diluted H2SO4 as an "efficient knife". By prior disintegration in a diluted H2SO4 solution, the exfoliation of bulk g-C3N4 was effectively accelerated. The as-prepared g-C3N4 nanosheets possess a two-dimensional (2D) thin-layer structure with seven-atom thickness, a large lateral size of about 1 μm, and a high specific surface area of 80 m(2) g(-1). Compared with the bulk precursor, the g-C3N4 nanosheets showed much higher efficiency of photogenerated charge transfer and separation, and consequently exhibited enhanced photocatalytic activity toward hydrogen evolution and pollutant decomposition under both full-sunlight and visible-light irradiation.

77 FR 49443 - Decision and Order Granting a Waiver to Sanyo From the Department of Energy Residential...

Science.gov (United States)

2012-08-16

.... (4) Representations. Sanyo may make representations about the energy use of its hybrid wine chiller... decision and order, Sanyo shall be required to test and rate its hybrid wine chiller/beverage center basic models using an alternate test procedure that requires Sanyo to test the wine chiller compartment at 55...

Biofuels done right: land efficient animal feeds enable large environmental and energy benefits.

Science.gov (United States)

Dale, Bruce E; Bals, Bryan D; Kim, Seungdo; Eranki, Pragnya

2010-11-15

There is an intense ongoing debate regarding the potential scale of biofuel production without creating adverse effects on food supply. We explore the possibility of three land-efficient technologies for producing food (actually animal feed), including leaf protein concentrates, pretreated forages, and double crops to increase the total amount of plant biomass available for biofuels. Using less than 30% of total U.S. cropland, pasture, and range, 400 billion liters of ethanol can be produced annually without decreasing domestic food production or agricultural exports. This approach also reduces U.S. greenhouse gas emissions by 670 Tg CO₂-equivalent per year, or over 10% of total U.S. annual emissions, while increasing soil fertility and promoting biodiversity. Thus we can replace a large fraction of U.S. petroleum consumption without indirect land use change.

Solar cooling in the hardware-in-the-loop test; Solare Kuehlung im Hardware-in-the-Loop-Test

Energy Technology Data Exchange (ETDEWEB)

Lohmann, Sandra; Radosavljevic, Rada; Goebel, Johannes; Gottschald, Jonas; Adam, Mario [Fachhochschule Duesseldorf (Germany). Erneuerbare Energien und Energieeffizienz E2

2012-07-01

The first part of the BMBF-funded research project 'Solar cooling in the hardware-in-the-loop test' (SoCool HIL) deals with the simulation of a solar refrigeration system using the simulation environment Matlab / Simulink with the toolboxes Stateflow and Carnot. Dynamic annual simulations and DoE supported parameter variations were used to select meaningful system configurations, control strategies and dimensioning of components. The second part of this project deals with hardware-in-the-loop tests using the 17.5 kW absorption chiller of the company Yazaki Europe Limited (Hertfordshire, United Kingdom). For this, the chiller is operated on a test bench in order to emulate the behavior of other system components (solar circuit with heat storage, recooling, buildings and cooling distribution / transfer). The chiller is controlled by a simulation of the system using MATLAB / Simulink / Carnot. Based on the knowledge on the real dynamic performance of the chiller the simulation model of the chiller can then be validated. Further tests are used to optimize the control of the chiller to the current cooling load. In addition, some changes in system configurations (for example cold backup) are tested with the real machine. The results of these tests and the findings on the dynamic performance of the chiller are presented.

Enabling the Distributed Generation Market of High Temperature Fuel Cell and Absorption Chiller Systems to Support Critical and Commercial Loads

Science.gov (United States)

DiMola, Ashley M.

Buildings account for over 18% of the world's anthropogenic Greenhouse Gas (GHG) emissions. As a result, a technology that can offset GHG emissions associated with buildings has the potential to save over 9 Giga-tons of GHG emissions per year. High temperature fuel cell and absorption chiller (HTFC/AC) technology offers a relatively low-carbon option for meeting cooling and electric loads for buildings while producing almost no criteria pollutants. GHG emissions in the state of California would decrease by 7.48 million metric tons per year if every commercial building in the State used HTFC/AC technology to meet its power and cooling requirements. In order to realize the benefits of HTFC/AC technology on a wide scale, the distributed generation market needs to be exposed to the technology and informed of its economic viability and real-world potential. This work characterizes the economics associated with HTFC/AC technology using select scenarios that are representative of realistic applications. The financial impacts of various input factors are evaluated and the HTFC/AC simulations are compared to the economics of traditional building utilities. It is shown that, in addition to the emissions reductions derived from the systems, HTFC/AC technology is financially preferable in all of the scenarios evaluated. This work also presents the design of a showcase environment, centered on a beta-test application, that presents (1) system operating data gathered using a custom data acquisition module, and (2) HTFC/AC technology in a clear and approachable manner in order to serve the target audience of market stakeholders.

Modeling of a Cogeneration System with a Micro Gas Turbine Operating at Partial Load Conditions

Directory of Open Access Journals (Sweden)

José Carlos Dutra

2017-06-01

Full Text Available The integration of absorption chillers in micro-cogeneration systems based on micro-gas turbines can be useful as an appropriate strategy to increase the total system energy efficiency. Since it is an area intensive in technology, it is necessary to develop and use models of simulation, which can predict the behavior of the whole system and of each component individually, at different operating conditions. This work is part of a research project in high efficiency cogeneration systems, whose purpose at this stage is to model a micro-cogeneration system, which is composed of a micro gas turbine, Capstone C30, a compact cross flow finned tube heat exchanger and an absorption chiller. The entire model is composed of specifically interconnected models, developed and validated for each component. The simulation of the microturbine used a thermodynamic analytic model, which contains a procedure used to obtain the micro turbine characteristic performance curves, which is closed with the thermodynamic Brayton cycle model. In the cogeneration system discussed in this paper, the compact heat exchanger was used to heat thermal oil, which drives an absorption chiller. It was designed, characterized and installed in a cogeneration system installed at the Centre d'Innovació Tecnològica en Revalorització Energètica i Refrigeració, Universtat Rovira i Virgili. Its design led to the heat exchanger model, which was coupled with the micro turbine model. Presented in this work is a comparison between the data from the model and the experiments, demonstrating good agreement between both results.

Site-specific investigations of aquifer thermal energy storage for space and process cooling

International Nuclear Information System (INIS)

Brown, D.R.

1991-01-01

This paper reports on the Pacific Northwest Laboratory (PNL) that has completed three preliminary site-specific feasibility studies that investigated aquifer thermal energy storage (ATES) for reducing space and process cooling costs. Chilled water stored in an ATES system could be used to meet all or part of the process and/or space cooling loads at the three facilities investigated. Seasonal or diurnal chill ATES systems could be significantly less expensive than a conventional electrically-driven, load-following chiller system at one of the three sites, depending on the cooling water loop return temperature and presumed future electricity escalation rate. For the other two sites investigated, a chill ATES system would be economically competitive with conventional chillers if onsite aquifer characteristics were improved. Well flow rates at one of the sites were adequate, but the expected thermal recovery efficiency was too low. The reverse of this situation was found at the other site, where the thermal recovery efficiency was expected to be adequate, but well flow rates were too low

Large fog collectors: New strategies for collection efficiency and structural response to wind pressure

Science.gov (United States)

Holmes, Robert; Rivera, Juan de Dios; de la Jara, Emilio

2015-01-01

Most studies of large fog collectors (LFC) have focused on the collection efficiency, the amount of water collected, or economic and social aspects, but have not addressed the effects of strong winds on the system. Wind pressure is directly related to fog water collection efficiency but on the other hand may cause serious damage on the structure of LFCs. This study focuses in the effects of wind pressure on the components of the LFC as an integral system, and the ways to face strong winds with no significant damage. For this purpose we analysed cases of mechanical failure of LFCs both in our experimental station at Peña Blanca in Chile and elsewhere. The effects of wind pressure can be described as a sequence of physical processes, starting with the mesh deformation as a way of adapting to the induced stresses. For a big enough pressure, local stress concentrations generate a progressive rupture of the mesh. In cases where the mesh is sufficiently strong the wind force causes the partial or total collapse of the structure. Usually the weakest part is the mesh, especially close to where it is attached to the structure. The way the mesh is attached to the frame or cable of the structure is particularly important since it can induce significant stress concentrations. Mesh failure before the structure failure may be considered as a mechanical fuse, since it is cheaper to repair. However, more practical mechanical fuses can be conceived. In relation to structural performance and water collection efficiency, we propose a new design strategy that considers a three-dimensional spatial display of the collection screen, oblique incidence angle of wind on mesh and small mesh area between the supporting frame. The proposed design strategies consider both the wind pressure on mesh and structure and the collection efficiency as an integral solution for the LFC. These new design strategies are the final output of this research. Applying these strategies a multi-funnel LFC is

Kinetically Controlled Synthesis of Pt-Based One-Dimensional Hierarchically Porous Nanostructures with Large Mesopores as Highly Efficient ORR Catalysts.

Science.gov (United States)

Fu, Shaofang; Zhu, Chengzhou; Song, Junhua; Engelhard, Mark H; Xia, Haibing; Du, Dan; Lin, Yuehe

2016-12-28

Rational design and construction of Pt-based porous nanostructures with large mesopores have triggered significant considerations because of their high surface area and more efficient mass transport. Hydrochloric acid-induced kinetically controlled reduction of metal precursors in the presence of soft template F-127 and hard template tellurium nanowires has been successfully demonstrated to construct one-dimensional hierarchical porous PtCu alloy nanostructures with large mesopores. Moreover, the electrochemical experiments demonstrated that the PtCu hierarchically porous nanostructures synthesized under optimized conditions exhibit enhanced electrocatalytic performance for oxygen reduction reaction in acid media.

Kinetically Controlled Synthesis of Pt-Based One-Dimensional Hierarchically Porous Nanostructures with Large Mesopores as Highly Efficient ORR Catalysts

Energy Technology Data Exchange (ETDEWEB)

Fu, Shaofang; Zhu, Chengzhou; Song, Junhua; Engelhard, Mark H.; Xia, Haibing; Du, Dan; Lin, Yuehe

2016-12-28

Rational design and construction of Pt-based porous nanostructures with large mesopores have triggered significant considerations because of their high surface area and more efficient mass transport. Hydrochloric acid-induced kinetic reduction of metal precursors in the presence of soft template F-127 and hard template tellurium nanowires has been successfully demonstrated to construct one-dimensional hierarchical porous PtCu alloy nanostructures with large mesopores. Moreover, the electrochemical experiments demonstrated that the resultant PtCu hierarchically porous nanostructures with optimized composition exhibit enhanced electrocatalytic performance for oxygen reduction reaction.

Efficient inference of population size histories and locus-specific mutation rates from large-sample genomic variation data.

Science.gov (United States)

Bhaskar, Anand; Wang, Y X Rachel; Song, Yun S

2015-02-01

With the recent increase in study sample sizes in human genetics, there has been growing interest in inferring historical population demography from genomic variation data. Here, we present an efficient inference method that can scale up to very large samples, with tens or hundreds of thousands of individuals. Specifically, by utilizing analytic results on the expected frequency spectrum under the coalescent and by leveraging the technique of automatic differentiation, which allows us to compute gradients exactly, we develop a very efficient algorithm to infer piecewise-exponential models of the historical effective population size from the distribution of sample allele frequencies. Our method is orders of magnitude faster than previous demographic inference methods based on the frequency spectrum. In addition to inferring demography, our method can also accurately estimate locus-specific mutation rates. We perform extensive validation of our method on simulated data and show that it can accurately infer multiple recent epochs of rapid exponential growth, a signal that is difficult to pick up with small sample sizes. Lastly, we use our method to analyze data from recent sequencing studies, including a large-sample exome-sequencing data set of tens of thousands of individuals assayed at a few hundred genic regions. © 2015 Bhaskar et al.; Published by Cold Spring Harbor Laboratory Press.

Application of Pareto-efficient combustion modeling framework to large eddy simulations of turbulent reacting flows

Science.gov (United States)

Wu, Hao; Ihme, Matthias

2017-11-01

The modeling of turbulent combustion requires the consideration of different physico-chemical processes, involving a vast range of time and length scales as well as a large number of scalar quantities. To reduce the computational complexity, various combustion models are developed. Many of them can be abstracted using a lower-dimensional manifold representation. A key issue in using such lower-dimensional combustion models is the assessment as to whether a particular combustion model is adequate in representing a certain flame configuration. The Pareto-efficient combustion (PEC) modeling framework was developed to perform dynamic combustion model adaptation based on various existing manifold models. In this work, the PEC model is applied to a turbulent flame simulation, in which a computationally efficient flamelet-based combustion model is used in together with a high-fidelity finite-rate chemistry model. The combination of these two models achieves high accuracy in predicting pollutant species at a relatively low computational cost. The relevant numerical methods and parallelization techniques are also discussed in this work.

MODELING AND DESIGN STUDY USING HFC-236EA AS AN ALTERNATIVE REFRIGERANT IN A CENTRIFUGAL COMPRESSOR

Science.gov (United States)

The report gives results of an investigation of the operation of a centrifugal compressor--part of a chlorofluorocarbon (CFC)-114 chiller installation--with the new refrigerant hydrofluorocarbon (HFC)-236ea, a proposed alternative to CFC-114. A large set of CFC-236ea operating da...

Ultra-high efficiency photovoltaic cells for large scale solar power generation.

Science.gov (United States)

Nakano, Yoshiaki

2012-01-01

The primary targets of our project are to drastically improve the photovoltaic conversion efficiency and to develop new energy storage and delivery technologies. Our approach to obtain an efficiency over 40% starts from the improvement of III-V multi-junction solar cells by introducing a novel material for each cell realizing an ideal combination of bandgaps and lattice-matching. Further improvement incorporates quantum structures such as stacked quantum wells and quantum dots, which allow higher degree of freedom in the design of the bandgap and the lattice strain. Highly controlled arrangement of either quantum dots or quantum wells permits the coupling of the wavefunctions, and thus forms intermediate bands in the bandgap of a host material, which allows multiple photon absorption theoretically leading to a conversion efficiency exceeding 50%. In addition to such improvements, microfabrication technology for the integrated high-efficiency cells and the development of novel material systems that realizes high efficiency and low cost at the same time are investigated.

MacroBac: New Technologies for Robust and Efficient Large-Scale Production of Recombinant Multiprotein Complexes.

Science.gov (United States)

Gradia, Scott D; Ishida, Justin P; Tsai, Miaw-Sheue; Jeans, Chris; Tainer, John A; Fuss, Jill O

2017-01-01

Recombinant expression of large, multiprotein complexes is essential and often rate limiting for determining structural, biophysical, and biochemical properties of DNA repair, replication, transcription, and other key cellular processes. Baculovirus-infected insect cell expression systems are especially well suited for producing large, human proteins recombinantly, and multigene baculovirus systems have facilitated studies of multiprotein complexes. In this chapter, we describe a multigene baculovirus system called MacroBac that uses a Biobricks-type assembly method based on restriction and ligation (Series 11) or ligation-independent cloning (Series 438). MacroBac cloning and assembly is efficient and equally well suited for either single subcloning reactions or high-throughput cloning using 96-well plates and liquid handling robotics. MacroBac vectors are polypromoter with each gene flanked by a strong polyhedrin promoter and an SV40 poly(A) termination signal that minimize gene order expression level effects seen in many polycistronic assemblies. Large assemblies are robustly achievable, and we have successfully assembled as many as 10 genes into a single MacroBac vector. Importantly, we have observed significant increases in expression levels and quality of large, multiprotein complexes using a single, multigene, polypromoter virus rather than coinfection with multiple, single-gene viruses. Given the importance of characterizing functional complexes, we believe that MacroBac provides a critical enabling technology that may change the way that structural, biophysical, and biochemical research is done. © 2017 Elsevier Inc. All rights reserved.

Oblate hemispheroidal Large Ruthenium Particles Supported on Calcium Amide as Efficient Catalysts for Ammonia Decomposition.

Science.gov (United States)

Kishida, Kazuhisa; Kitano, Masaaki; Inoue, Yasunori; Sasase, Masato; Nakao, Takuya; Tada, Tomofumi; Abe, Hitoshi; Niwa, Yasuhiro; Yokoyama, Toshiharu; Hara, Michikazu; Hosono, Hideo

2018-03-30

Ammonia decomposition is positioned as an important technology for abstracting hydrogen from ammonia toward the realization of a hydrogen economy. Here, we report that oblate hemispheroidal large Ru particles on Ca(NH₂)₂ function as efficient catalysts for ammonia decomposition. The turnover frequency (TOF) of Ru/Ca(NH₂)₂ increased by two orders of magnitude as the Ru particle size was increased from 1.5 to 8.4 nm. More than 90% ammonia decomposition was achieved over Ru/Ca(NH₂)₂ with oblate hemispheroidal large Ru particles at 360 ºC, which is comparable to that of alkali-promoted Ru catalysts with small Ru particle sizes. XAFS analyses revealed that Ru particles are immobilized on Ca(NH₂)₂ by Ru-N bonding formed at the metal-support interface, which leads to oblate hemispheroidal Ru particles. Such a strong metal-support interaction in the Ru/Ca(NH₂)₂ is also substantiated by density functional theory calculations. The high activity of Ru/Ca(NH₂)₂ with large Ru particles primarily originates from the shape and appropriate size of Ru particles with a high density of active sites rather than the electron-donating ability of Ca(NH₂)₂. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Project W-320, 241-C-106 sluicing HVAC calculations, Volume 1

International Nuclear Information System (INIS)

Bailey, J.W.

1998-01-01

This supporting document has been prepared to make the FDNW calculations for Project W-320, readily retrievable. The report contains the following calculations: Exhaust airflow sizing for Tank 241-C-106; Equipment sizing and selection recirculation fan; Sizing high efficiency mist eliminator; Sizing electric heating coil; Equipment sizing and selection of recirculation condenser; Chiller skid system sizing and selection; High efficiency metal filter shielding input and flushing frequency; and Exhaust skid stack sizing and fan sizing

Project W-320, 241-C-106 sluicing HVAC calculations, Volume 1

Energy Technology Data Exchange (ETDEWEB)

Bailey, J.W.

1998-08-07

This supporting document has been prepared to make the FDNW calculations for Project W-320, readily retrievable. The report contains the following calculations: Exhaust airflow sizing for Tank 241-C-106; Equipment sizing and selection recirculation fan; Sizing high efficiency mist eliminator; Sizing electric heating coil; Equipment sizing and selection of recirculation condenser; Chiller skid system sizing and selection; High efficiency metal filter shielding input and flushing frequency; and Exhaust skid stack sizing and fan sizing.

Double utilization of the roof. 'Solar green roofs' - the advantages are in the combination; Das Dach zweifach nutzen. 'SolarGruenDaecher - die Vorteile liegen in der Kombination

Energy Technology Data Exchange (ETDEWEB)

Mann, Gunter

2013-06-01

Air conditioners cooling with solar energy have already existed for a long time. The core principles are adsorption chillers, absorption chillers and DEC chillers. However, these chillers are relatively expensive compared to air conditioners in compression technology and therefore not often used in the mass market. Since January 2013, Sedna Aire Europe GmbH (Dortmund, Federal Republic of Germany) offers solar-assisted air-conditioners that cost the same as commercial non-solar comparable equipment and enable significant cost savings from the first year. In addition, these air-conditioners are designed as heat pumps, which can be heated.

Efficient operation scheduling for adsorption chillers using predictive optimization-based control methods

Science.gov (United States)

Bürger, Adrian; Sawant, Parantapa; Bohlayer, Markus; Altmann-Dieses, Angelika; Braun, Marco; Diehl, Moritz

2017-10-01

Within this work, the benefits of using predictive control methods for the operation of Adsorption Cooling Machines (ACMs) are shown on a simulation study. Since the internal control decisions of series-manufactured ACMs often cannot be influenced, the work focuses on optimized scheduling of an ACM considering its internal functioning as well as forecasts for load and driving energy occurrence. For illustration, an assumed solar thermal climate system is introduced and a system model suitable for use within gradient-based optimization methods is developed. The results of a system simulation using a conventional scheme for ACM scheduling are compared to the results of a predictive, optimization-based scheduling approach for the same exemplary scenario of load and driving energy occurrence. The benefits of the latter approach are shown and future actions for application of these methods for system control are addressed.

Efficient parallel and out of core algorithms for constructing large bi-directed de Bruijn graphs

Directory of Open Access Journals (Sweden)

Vaughn Matthew

2010-11-01

Full Text Available Abstract Background Assembling genomic sequences from a set of overlapping reads is one of the most fundamental problems in computational biology. Algorithms addressing the assembly problem fall into two broad categories - based on the data structures which they employ. The first class uses an overlap/string graph and the second type uses a de Bruijn graph. However with the recent advances in short read sequencing technology, de Bruijn graph based algorithms seem to play a vital role in practice. Efficient algorithms for building these massive de Bruijn graphs are very essential in large sequencing projects based on short reads. In an earlier work, an O(n/p time parallel algorithm has been given for this problem. Here n is the size of the input and p is the number of processors. This algorithm enumerates all possible bi-directed edges which can overlap with a node and ends up generating Θ(nΣ messages (Σ being the size of the alphabet. Results In this paper we present a Θ(n/p time parallel algorithm with a communication complexity that is equal to that of parallel sorting and is not sensitive to Σ. The generality of our algorithm makes it very easy to extend it even to the out-of-core model and in this case it has an optimal I/O complexity of Θ(nlog(n/BBlog(M/B (M being the main memory size and B being the size of the disk block. We demonstrate the scalability of our parallel algorithm on a SGI/Altix computer. A comparison of our algorithm with the previous approaches reveals that our algorithm is faster - both asymptotically and practically. We demonstrate the scalability of our sequential out-of-core algorithm by comparing it with the algorithm used by VELVET to build the bi-directed de Bruijn graph. Our experiments reveal that our algorithm can build the graph with a constant amount of memory, which clearly outperforms VELVET. We also provide efficient algorithms for the bi-directed chain compaction problem. Conclusions The bi

Efficient parallel and out of core algorithms for constructing large bi-directed de Bruijn graphs.

Science.gov (United States)

Kundeti, Vamsi K; Rajasekaran, Sanguthevar; Dinh, Hieu; Vaughn, Matthew; Thapar, Vishal

2010-11-15

Assembling genomic sequences from a set of overlapping reads is one of the most fundamental problems in computational biology. Algorithms addressing the assembly problem fall into two broad categories - based on the data structures which they employ. The first class uses an overlap/string graph and the second type uses a de Bruijn graph. However with the recent advances in short read sequencing technology, de Bruijn graph based algorithms seem to play a vital role in practice. Efficient algorithms for building these massive de Bruijn graphs are very essential in large sequencing projects based on short reads. In an earlier work, an O(n/p) time parallel algorithm has been given for this problem. Here n is the size of the input and p is the number of processors. This algorithm enumerates all possible bi-directed edges which can overlap with a node and ends up generating Θ(nΣ) messages (Σ being the size of the alphabet). In this paper we present a Θ(n/p) time parallel algorithm with a communication complexity that is equal to that of parallel sorting and is not sensitive to Σ. The generality of our algorithm makes it very easy to extend it even to the out-of-core model and in this case it has an optimal I/O complexity of Θ(nlog(n/B)Blog(M/B)) (M being the main memory size and B being the size of the disk block). We demonstrate the scalability of our parallel algorithm on a SGI/Altix computer. A comparison of our algorithm with the previous approaches reveals that our algorithm is faster--both asymptotically and practically. We demonstrate the scalability of our sequential out-of-core algorithm by comparing it with the algorithm used by VELVET to build the bi-directed de Bruijn graph. Our experiments reveal that our algorithm can build the graph with a constant amount of memory, which clearly outperforms VELVET. We also provide efficient algorithms for the bi-directed chain compaction problem. The bi-directed de Bruijn graph is a fundamental data structure for

An efficient method based on the uniformity principle for synthesis of large-scale heat exchanger networks

International Nuclear Information System (INIS)

Zhang, Chunwei; Cui, Guomin; Chen, Shang

2016-01-01

Highlights: • Two dimensionless uniformity factors are presented to heat exchange network. • The grouping of process streams reduces the computational complexity of large-scale HENS problems. • The optimal sub-network can be obtained by Powell particle swarm optimization algorithm. • The method is illustrated by a case study involving 39 process streams, with a better solution. - Abstract: The optimal design of large-scale heat exchanger networks is a difficult task due to the inherent non-linear characteristics and the combinatorial nature of heat exchangers. To solve large-scale heat exchanger network synthesis (HENS) problems, two dimensionless uniformity factors to describe the heat exchanger network (HEN) uniformity in terms of the temperature difference and the accuracy of process stream grouping are deduced. Additionally, a novel algorithm that combines deterministic and stochastic optimizations to obtain an optimal sub-network with a suitable heat load for a given group of streams is proposed, and is named the Powell particle swarm optimization (PPSO). As a result, the synthesis of large-scale heat exchanger networks is divided into two corresponding sub-parts, namely, the grouping of process streams and the optimization of sub-networks. This approach reduces the computational complexity and increases the efficiency of the proposed method. The robustness and effectiveness of the proposed method are demonstrated by solving a large-scale HENS problem involving 39 process streams, and the results obtained are better than those previously published in the literature.

Solar cooling between thermal and photovoltaic: An energy and economic comparative study in the Mediterranean conditions

International Nuclear Information System (INIS)

Noro, M.; Lazzarin, R.M.

2014-01-01

This paper considers different cooling systems and investigates the most promising alternatives when solar energy is to be used to supply the cooling demand. All the systems are evaluated during a summer cooling season by the energetic and economic point of view by dynamic simulation for two different climates. For Milan (Cfb climate) the highest OSE (overall system efficiency) is reached by LiBr (lithium-bromide) double effect absorption chiller driven by parabolic through collector (0.53). In terms of the collecting surface area, the best systems for Milan feature 0.08 m 2  MJ −1 per day both for electric system (mono-crystalline photovoltaic coupled to water cooled chiller) and thermal system (PTC (parabolic trough collectors) coupled to double effect water-LiBr absorption chiller). Southern latitudes like Trapani (Csa climate) allow a quite better performance for thermal solar cooling solutions. The NPV (net present worths) of electric solar cooling solutions are favorable with respect to the traditional solution and the DPV (discounted payback periods) are all lower than the period of economic analysis above all for water cooled chillers. Finally a sensitivity analysis of the specific investment cost (€ MJ −1 per day) is carried out regarding the investment cost of collectors, the solar ratio and the interest rate. - Highlights: • Solar cooling is obtained with solar thermal or PV (photovoltaic) with easy available equipment. • In the past PV driven systems for solar cooling were not considered as too expensive. • An energy/economic comparison is carried out for the various solar cooling systems. • Sensitivity analyses are carried out varying different parameters

50.4% slope efficiency thulium-doped large-mode-area fiber laser fabricated by powder technology.

Science.gov (United States)

Darwich, Dia; Dauliat, Romain; Jamier, Raphaël; Benoit, Aurélien; Auguste, Jean-Louis; Grimm, Stephan; Kobelke, Jens; Schwuchow, Anka; Schuster, Kay; Roy, Philippe

2016-01-15

We report on a triple clad large-mode-area Tm-doped fiber laser with 18 μm core diameter manufactured for the first time by an alternative manufacturing process named REPUSIL. This reactive powder sinter material enables similar properties compared to conventional CVD-made fiber lasers, while offering the potential of producing larger and more uniform material. The fiber characterization in a laser configuration provides a slope efficiency of 47.7% at 20°C, and 50.4% at 0°C with 8 W output power, with a laser peak emission at 1970 nm. Finally, a beam quality near the diffraction-limit (M(x,y)2<1.1) is proved.

Cogeneration and beyond: The need and opportunity for high efficiency, renewable community energy systems

International Nuclear Information System (INIS)

Gleason, T.C.J.

1992-06-01

The justification, strategies, and technology options for implementing advanced district heating and cooling systems in the United States are presented. The need for such systems is discussed in terms of global warming, ozone depletion, and the need for a sustainable energy policy. Strategies for implementation are presented in the context of the Public Utilities Regulatory Policies Act and proposed new institutional arrangements. Technology opportunities are highlighted in the areas of advanced block-scale cogeneration, CFC-free chiller technologies, and renewable sources of heating and cooling that are particularly applicable to district systems

The optimal operation of cooling tower systems with variable-frequency control

Science.gov (United States)

Cao, Yong; Huang, Liqing; Cui, Zhiguo; Liu, Jing

2018-02-01

This study investigates the energy performance of chiller and cooling tower systems integrated with variable-frequency control for cooling tower fans and condenser water pumps. With regard to an example chiller system serving an office building, Chiller and cooling towers models were developed to assess how different variable-frequency control methods of cooling towers fans and condenser water pumps influence the trade-off between the chiller power, pump power and fan power under various operating conditions. The matching relationship between the cooling tower fans frequency and condenser water pumps frequency at optimal energy consumption of the system is introduced to achieve optimum system performance.

Increasing on-target cleavage efficiency for CRISPR/Cas9-induced large fragment deletion in Myxococcus xanthus.

Science.gov (United States)

Yang, Ying-Jie; Wang, Ye; Li, Zhi-Feng; Gong, Ya; Zhang, Peng; Hu, Wen-Chao; Sheng, Duo-Hong; Li, Yue-Zhong

2017-08-16

The CRISPR/Cas9 system is a powerful tool for genome editing, in which the sgRNA binds and guides the Cas9 protein for the sequence-specific cleavage. The protocol is employable in different organisms, but is often limited by cell damage due to the endonuclease activity of the introduced Cas9 and the potential off-target DNA cleavage from incorrect guide by the 20 nt spacer. In this study, after resolving some critical limits, we have established an efficient CRISPR/Cas9 system for the deletion of large genome fragments related to the biosynthesis of secondary metabolites in Myxococcus xanthus cells. We revealed that the high expression of a codon-optimized cas9 gene in M. xanthus was cytotoxic, and developed a temporally high expression strategy to reduce the cell damage from high expressions of Cas9. We optimized the deletion protocol by using the tRNA-sgRNA-tRNA chimeric structure to ensure correct sgRNA sequence. We found that, in addition to the position-dependent nucleotide preference, the free energy of a 20 nt spacer was a key factor for the deletion efficiency. By using the developed protocol, we achieved the CRISPR/Cas9-induced deletion of large biosynthetic gene clusters for secondary metabolites in M. xanthus DK1622 and its epothilone-producing mutant. The findings and the proposals described in this paper were suggested to be workable in other organisms, for example, other Gram negative bacteria with high GC content.

Highly efficient periodically poled KTP-isomorphs with large apertures and extreme domain aspect-ratios

Science.gov (United States)

Canalias, Carlota; Zukauskas, Andrius; Tjörnhamman, Staffan; Viotti, Anne-Lise; Pasiskevicius, Valdas; Laurell, Fredrik

2018-02-01

Since the early 1990's, a substantial effort has been devoted to the development of quasi-phased-matched (QPM) nonlinear devices, not only in ferroelectric oxides like LiNbO3, LiTaO3 and KTiOPO4 (KTP), but also in semiconductors as GaAs, and GaP. The technology to implement QPM structures in ferroelectric oxides has by now matured enough to satisfy the most basic frequency-conversion schemes without substantial modification of the poling procedures. Here, we present a qualitative leap in periodic poling techniques that allows us to demonstrate devices and frequency conversion schemes that were deemed unfeasible just a few years ago. Thanks to our short-pulse poling and coercive-field engineering techniques, we are able to demonstrate large aperture (5 mm) periodically poled Rb-doped KTP devices with a highly-uniform conversion efficiency over the whole aperture. These devices allow parametric conversion with energies larger than 60 mJ. Moreover, by employing our coercive-field engineering technique we fabricate highlyefficient sub-µm periodically poled devices, with periodicities as short as 500 nm, uniform over 1 mm-thick crystals, which allow us to realize mirrorless optical parametric oscillators with counter-propagating signal and idler waves. These novel devices present unique spectral and tuning properties, superior to those of conventional OPOs. Furthermore, our techniques are compatible with KTA, a KTP isomorph with extended transparency in the mid-IR range. We demonstrate that our highly-efficient PPKTA is superior both for mid-IR and for green light generation - as a result of improved transmission properties in the visible range. Our KTP-isomorph poling techniques leading to highly-efficient QPM devices will be presented. Their optical performance and attractive damage thresholds will be discussed.

Energy analysis of a trigeneration plant based on solid oxide fuel cell and organic Rankine cycle

International Nuclear Information System (INIS)

Al-Sulaiman, F.A.; Dincer, I.; Hamdullahpur, F.

2009-01-01

In this paper, energy analysis of a trigeneration plant based on Solid Oxide Fuel cell (SOFC) and organic Rankine cycle (ORC) is carried out. The physical and thermodynamic elements of the plant include a SOFC, ORC, a heating process and a single-effect absorption chiller. The waste heat from the SOFC is used as an input heat to the ORC. In turn, the waste heat from the ORC is used to heat the inlet water, and to provide the heat needed for the single-effect absorption chiller. The results obtained from this study show that the highest cycle efficiency that can be attained under the proposed scheme is 48% and the highest SOFC efficiency is 43%. Furthermore, it is found that the highest net work rate is 435 kW and the highest SOFC-AC work rate is 337 kW. At a current density higher than 0.87 A/cm 2 , the SOFC and cycle efficiencies drop abruptly because of the sharp increase in the voltage losses of the SOFC. At a current density of 0.75 A/cm 2 , the highest SOFC efficiency of 41% is obtained at the inlet fuel cell temperature of 890 K. The change in the inlet pressure of the turbine has insignificant effect on the efficiencies of the ORC and overall cycle. The study shows the effect of both the current density and the inlet fuel cell temperature on the cell voltage and voltage loss. (author)

Energy conservation applications of microprocessors

Energy Technology Data Exchange (ETDEWEB)

Shih, James Y.

1979-07-01

A survey of the application of microprocessors for industrial and commercial energy conservation has been made. Microprocessor applications for HVAC, chiller control, and automotive equipment are discussed. A case study of successful replacement of a conventional cooling plant control is recounted. The rapid advancement of microelectronic technology will affect efficient energy control, more sophisticated control methodology, and more investment in controls.

Linking plant functional trait plasticity and the large increase in forest water use efficiency

Science.gov (United States)

Mastrotheodoros, Theodoros; Pappas, Christoforos; Molnar, Peter; Burlando, Paolo; Keenan, Trevor F.; Gentine, Pierre; Gough, Christopher M.; Fatichi, Simone

2017-09-01

Elevated atmospheric CO2 concentrations are expected to enhance photosynthesis and reduce stomatal conductance, thus increasing plant water use efficiency. A recent study based on eddy covariance flux observations from Northern Hemisphere forests showed a large increase in inherent water use efficiency (IWUE). Here we used an updated version of the same data set and robust uncertainty quantification to revisit these contemporary IWUE trends. We tested the hypothesis that the observed IWUE increase could be attributed to interannual trends in plant functional traits, potentially triggered by environmental change. We found that IWUE increased by 1.3% yr-1, which is less than previously reported but still larger than theoretical expectations. Numerical simulations with the Tethys-Chloris ecosystem model using temporally static plant functional traits cannot explain this increase. Simulations with plant functional trait plasticity, i.e., temporal changes in model parameters such as specific leaf area and maximum Rubisco capacity, match the observed trends in IWUE. Our results show that trends in plant functional traits, equal to 1.0% yr-1, can explain the observed IWUE trends. Thus, at decadal or longer time scales, trait plasticity could potentially influence forest water, carbon, and energy fluxes with profound implications for both the monitoring of temporal changes in plant functional traits and their representation in Earth system models.

Optimization of the electron collection efficiency of a large area MCP-PMT for the JUNO experiment

International Nuclear Information System (INIS)

Chen, Lin; Tian, Jinshou; Liu, Chunliang; Wang, Yifang; Zhao, Tianchi; Liu, Hulin; Wei, Yonglin; Sai, Xiaofeng; Chen, Ping; Wang, Xing; Lu, Yu; Hui, Dandan; Guo, Lehui; Liu, Shulin; Qian, Sen; Xia, Jingkai; Yan, Baojun; Zhu, Na; Sun, Jianning; Si, Shuguang

2016-01-01

A novel large-area (20-inch) photomultiplier tube based on microchannel plate (MCP-PMTs) is proposed for the Jiangmen Underground Neutrino Observatory (JUNO) experiment. Its photoelectron collection efficiency C e is limited by the MCP open area fraction (A open ). This efficiency is studied as a function of the angular (θ), energy (E) distributions of electrons in the input charge cloud and the potential difference (U) between the PMT photocathode and the MCP input surface, considering secondary electron emission from the MCP input electrode. In CST Studio Suite, Finite Integral Technique and Monte Carlo method are combined to investigate the dependence of C e on θ, E and U. Results predict that C e can exceed A open , and are applied to optimize the structure and operational parameters of the 20-inch MCP-PMT prototype. C e of the optimized MCP-PMT is expected to reach 81.2%. Finally, the reduction of the penetration depth of the MCP input electrode layer and the deposition of a high secondary electron yield material on the MCP are proposed to further optimize C e .

Norwegian participation in the IEA Heat Pump Programme Annex 34 - final report

Energy Technology Data Exchange (ETDEWEB)

Nordtvedt, S.R.

2012-07-01

This report is the Norwegian team contribution to Task A within the IEA Heat Pumps Programme Annex 34 on #Left Double Quotation Mark#Thermally driven heat pumps#Right Double Quotation Mark#. It aims to give an overview of the thermally driven heat pump (TDHP) and chiller (TDC) market, recent developments in the area of TDHP and TDC, as well as to give an outlook of the progress of this technology. There are no Norwegian manufacturers on the TDHP market. There are only seven existing thermally driven absorption system installations in Norway. Three are district heat driven water/LiBr chillers, one is a steam driven water/LiBr chiller, one water/LiBr heat pump for flue gas condensation in a wood chip heating unit, and two gas driven ammonia-water chillers. The future market for thermally driven heat pumps and chillers in Norway is expected to be in combination of biomass, district heat or waste heat. (Author)

An efficient implementation of 3D high-resolution imaging for large-scale seismic data with GPU/CPU heterogeneous parallel computing

Science.gov (United States)

Xu, Jincheng; Liu, Wei; Wang, Jin; Liu, Linong; Zhang, Jianfeng

2018-02-01

De-absorption pre-stack time migration (QPSTM) compensates for the absorption and dispersion of seismic waves by introducing an effective Q parameter, thereby making it an effective tool for 3D, high-resolution imaging of seismic data. Although the optimal aperture obtained via stationary-phase migration reduces the computational cost of 3D QPSTM and yields 3D stationary-phase QPSTM, the associated computational efficiency is still the main problem in the processing of 3D, high-resolution images for real large-scale seismic data. In the current paper, we proposed a division method for large-scale, 3D seismic data to optimize the performance of stationary-phase QPSTM on clusters of graphics processing units (GPU). Then, we designed an imaging point parallel strategy to achieve an optimal parallel computing performance. Afterward, we adopted an asynchronous double buffering scheme for multi-stream to perform the GPU/CPU parallel computing. Moreover, several key optimization strategies of computation and storage based on the compute unified device architecture (CUDA) were adopted to accelerate the 3D stationary-phase QPSTM algorithm. Compared with the initial GPU code, the implementation of the key optimization steps, including thread optimization, shared memory optimization, register optimization and special function units (SFU), greatly improved the efficiency. A numerical example employing real large-scale, 3D seismic data showed that our scheme is nearly 80 times faster than the CPU-QPSTM algorithm. Our GPU/CPU heterogeneous parallel computing framework significant reduces the computational cost and facilitates 3D high-resolution imaging for large-scale seismic data.

Efficient structure from motion on large scenes using UAV with position and pose information

Science.gov (United States)

Teng, Xichao; Yu, Qifeng; Shang, Yang; Luo, Jing; Wang, Gang

2018-04-01

In this paper, we exploit prior information from global positioning systems and inertial measurement units to speed up the process of large scene reconstruction from images acquired by Unmanned Aerial Vehicles. We utilize weak pose information and intrinsic parameter to obtain the projection matrix for each view. As compared to unmanned aerial vehicles' flight altitude, topographic relief can usually be ignored, we assume that the scene is flat and use weak perspective camera to get projective transformations between two views. Furthermore, we propose an overlap criterion and select potentially matching view pairs between projective transformed views. A robust global structure from motion method is used for image based reconstruction. Our real world experiments show that the approach is accurate, scalable and computationally efficient. Moreover, projective transformations between views can also be used to eliminate false matching.

Trigeneration in food retail: An energetic, economic and environmental evaluation for a supermarket application

International Nuclear Information System (INIS)

Sugiartha, N.; Tassou, S.A.; Chaer, I.; Marriott, D.

2009-01-01

This paper presents results on the evaluation of energy utilisation efficiency and economic and environmental performance of a micro-gas turbine (MGT) based trigeneration system for supermarket applications. A spreadsheet energy model has been developed for the analysis of trigeneration systems and a 2800 m 2 sales area supermarket was selected for the feasibility study. Historical energy demand data were used for the analysis, which considered factors such as the fraction of the heat output used to drive the absorption chillers, the chiller COP and the difference between electricity and gas prices. The results showed that energy and environmental benefits can be obtained from the application of trigeneration systems to supermarkets compared to conventional systems. The payback period of natural gas driven trigeneration systems and greenhouse gas emissions savings will depend on the relative gas and electricity prices and the COP of the vapour compression and absorption systems. It was also shown that operation at full electrical output gives a better performance than a heat load-following strategy due to the reduction of the electrical generation efficiency of the MGT unit at part load conditions.

Development of large area, high efficiency amorphous silicon solar cell

Energy Technology Data Exchange (ETDEWEB)

Yoon, K.S.; Kim, S.; Kim, D.W. [Yu Kong Taedok Institute of Technology (Korea, Republic of)

1996-02-01

The objective of the research is to develop the mass-production technologies of high efficiency amorphous silicon solar cells in order to reduce the costs of solar cells and dissemination of solar cells. Amorphous silicon solar cell is the most promising option of thin film solar cells which are relatively easy to reduce the costs. The final goal of the research is to develop amorphous silicon solar cells having the efficiency of 10%, the ratio of light-induced degradation 15% in the area of 1200 cm{sup 2} and test the cells in the form of 2 Kw grid-connected photovoltaic system. (author) 35 refs., 8 tabs., 67 figs.

Out-coupling membrane for large-size organic light-emitting panels with high efficiency and improved uniformity

Energy Technology Data Exchange (ETDEWEB)

Ding, Lei, E-mail: dinglei@sust.edu.cn [College of Electrical and Information Engineering, Shaanxi University of Science and Technology, Xi’an, Shaanxi 710021 (China); Wang, Lu-Wei [College of Electrical and Information Engineering, Shaanxi University of Science and Technology, Xi’an, Shaanxi 710021 (China); Zhou, Lei, E-mail: zhzhlei@gmail.com [Faculty of Mathematics and Physics, Huaiyin Institute of Technology, Huai' an 223003 (China); Zhang, Fang-hui [College of Electrical and Information Engineering, Shaanxi University of Science and Technology, Xi’an, Shaanxi 710021 (China)

2016-12-15

Highlights: • An out-coupling membrane embedded with a scattering film of SiO{sub 2} spheres and polyethylene terephthalate (PET) plastic was successfully developed for 150 × 150 mm{sup 2} OLEDs. • Remarkable enhancement in efficiency was achieved from the OLEDs with out- coupling membrane. • The uniformity of large-size GOLED lighting panel is remarkably improved. - Abstract: An out-coupling membrane embedded with a scattering film of SiO{sub 2} spheres and polyethylene terephthalate (PET) plastic was successfully developed for 150 × 150 mm{sup 2} green OLEDs. Comparing with a reference OLED panel, an approximately 1-fold enhancement in the forward emission was obtained with an out-coupling membrane adhered to the surface of the external glass substrate of the panel. Moreover, it was verified that the emission color at different viewing angles can be stabilized without apparent spectral distortion. Particularly, the uniformity of the large-area OLEDs was greatly improved. Theoretical calculation clarified that the improved performance of the lighting panels is primarily attributed to the effect of particle scattering.

Efficient Computation of Sparse Matrix Functions for Large-Scale Electronic Structure Calculations: The CheSS Library.

Science.gov (United States)

Mohr, Stephan; Dawson, William; Wagner, Michael; Caliste, Damien; Nakajima, Takahito; Genovese, Luigi

2017-10-10

We present CheSS, the "Chebyshev Sparse Solvers" library, which has been designed to solve typical problems arising in large-scale electronic structure calculations using localized basis sets. The library is based on a flexible and efficient expansion in terms of Chebyshev polynomials and presently features the calculation of the density matrix, the calculation of matrix powers for arbitrary powers, and the extraction of eigenvalues in a selected interval. CheSS is able to exploit the sparsity of the matrices and scales linearly with respect to the number of nonzero entries, making it well-suited for large-scale calculations. The approach is particularly adapted for setups leading to small spectral widths of the involved matrices and outperforms alternative methods in this regime. By coupling CheSS to the DFT code BigDFT, we show that such a favorable setup is indeed possible in practice. In addition, the approach based on Chebyshev polynomials can be massively parallelized, and CheSS exhibits excellent scaling up to thousands of cores even for relatively small matrix sizes.

Case study: improving efficiency in a large hospital laboratory.

Science.gov (United States)

Bartel, Marilynn

2004-01-01

Saint Francis Health System (SFHS) consists of three hospitals and one clinic: Saint Francis Hospital (SFH); Broken Arrow Medical Center; Laureate Psychiatric Hospital; and Warren Clinic. SFHS has 670 physicians on staff and serves medical (oncology, orthopedic, neurology, and renal), surgical, cardiac, women and infant, pediatric, transplant, and trauma patients in Tulsa County, Oklahoma, which has a population of 660,000. SFH incorporates 706 staffed beds, including 126 pediatric beds and 119 critical care beds. Each year, the health system averages 38,000 admissions, 70,000 emergency department visits, 25,000 surgeries, and 3,500 births. Saint Francis Laboratory is located within the main hospital facility (SFH) and functions as a core lab for the health system. The lab also coordinates lab services with Saint Francis Heart Hospital, a physician-system joint venture. The Optimal Equipment Configuration (OEC) Project was designed by the Clinical Laboratory Services division of Premier, a group purchasing organization, with the goal of determining whether laboratories could improve efficiency and decrease unit cost by using a single-source vendor. Participants included seven business partners (Abbott, Bayer, Beckman/Coulter, Dade/Behring, J&J/ Ortho, Olympus, and Roche) and 21 laboratory sites (a small, mid-sized, and large site for each vendor). SFH laboratory staff embraced Premier's concept and viewed the OEC project as an opportunity to "energize" laboratory operations. SFH partnered with Abbott, their primary equipment vendor, for the project. Using resources and tools made available through the project, the laboratory was re-engineered to simplify workflow, increase productivity, and decrease costs by adding automation and changing to centralized specimen processing. Abbott and SFH shared a common vision for the project and enhanced their partnership through increased communication and problem solving. Abbott's area representatives provided for third

Optimization of the electron collection efficiency of a large area MCP-PMT for the JUNO experiment

Energy Technology Data Exchange (ETDEWEB)

Chen, Lin, E-mail: chenlin@opt.cn [State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics (XIOPM), Chinese Academy of Sciences (CAS), Xi’an 710119 (China); Graduate School of Chinese Academy of Sciences (CAS), Beijing 100049 (China); Xi’an Jiaotong University, Xi’an 710049 (China); Tian, Jinshou [Graduate School of Chinese Academy of Sciences (CAS), Beijing 100049 (China); Liu, Chunliang [Xi’an Jiaotong University, Xi’an 710049 (China); Wang, Yifang; Zhao, Tianchi [Institute of High Energy Physics (IHEP) of CAS, Beijing 100049 (China); Liu, Hulin; Wei, Yonglin; Sai, Xiaofeng [Graduate School of Chinese Academy of Sciences (CAS), Beijing 100049 (China); Chen, Ping [State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics (XIOPM), Chinese Academy of Sciences (CAS), Xi’an 710119 (China); Graduate School of Chinese Academy of Sciences (CAS), Beijing 100049 (China); Wang, Xing; Lu, Yu [Graduate School of Chinese Academy of Sciences (CAS), Beijing 100049 (China); Hui, Dandan; Guo, Lehui [State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics (XIOPM), Chinese Academy of Sciences (CAS), Xi’an 710119 (China); Graduate School of Chinese Academy of Sciences (CAS), Beijing 100049 (China); Liu, Shulin; Qian, Sen; Xia, Jingkai; Yan, Baojun; Zhu, Na [Institute of High Energy Physics (IHEP) of CAS, Beijing 100049 (China); Sun, Jianning; Si, Shuguang [North Night Vision Technology (NNVT) CO., LTD, Nanjing 210110 (China); and others

2016-08-11

A novel large-area (20-inch) photomultiplier tube based on microchannel plate (MCP-PMTs) is proposed for the Jiangmen Underground Neutrino Observatory (JUNO) experiment. Its photoelectron collection efficiency C{sub e} is limited by the MCP open area fraction (A{sub open}). This efficiency is studied as a function of the angular (θ), energy (E) distributions of electrons in the input charge cloud and the potential difference (U) between the PMT photocathode and the MCP input surface, considering secondary electron emission from the MCP input electrode. In CST Studio Suite, Finite Integral Technique and Monte Carlo method are combined to investigate the dependence of C{sub e} on θ, E and U. Results predict that C{sub e} can exceed A{sub open}, and are applied to optimize the structure and operational parameters of the 20-inch MCP-PMT prototype. C{sub e} of the optimized MCP-PMT is expected to reach 81.2%. Finally, the reduction of the penetration depth of the MCP input electrode layer and the deposition of a high secondary electron yield material on the MCP are proposed to further optimize C{sub e}.

Solar cooling systems. Classification and energetic evaluation; Solare Kuehlsysteme. Klassifizierung und energetische Bewertung

Energy Technology Data Exchange (ETDEWEB)

Hennig, Jakob [Technische Univ. Bergakademie Freiberg (Germany); Hafner, Armin [SINTEF Energy Research, Trondheim (Norway); Eikevik, Trygve M. [NTNU, Trondheim (Norway)

2012-07-01

The investigation of alternative, sustainable concepts for cold production is worthwhile in times of increasing energy demand for cooling and air conditioning applications. Energy sources such as solar radiation can help to reduce the burden on the environment and energy networks. Solar electricity from photovoltaic cells or solar power from solar collectors can be used in refrigerating equipment (such as cold vapor compression chiller, absorption chiller, adsorption chillers, open systems, thermo-mechanical systems or ejector-based systems) are fed in order to produce the desired coldness. In many cases, the temporal coincidence of radiation supply and cooling requirements makes the solar cooling to a promising concept, especially at sites with a high solar radiation, large cooling demand, high energy prices, or insufficient access to public power grids. A model-based investigation of different solar cooling systems with an equivalent cooling capacity was carried out. The results show that the performance potential strongly depends on the selected technology and the site of the system. A balanced daily energy balance can be achieved with an appropriately dimensioned solar power plant with cooling concept. Depending on the system and interpretation, primary energy savings or a primary energy overhead can be achieved within a year in comparison to a conventional system.

An Efficient Approach for Fast and Accurate Voltage Stability Margin Computation in Large Power Grids

Directory of Open Access Journals (Sweden)

Heng-Yi Su

2016-11-01

Full Text Available This paper proposes an efficient approach for the computation of voltage stability margin (VSM in a large-scale power grid. The objective is to accurately and rapidly determine the load power margin which corresponds to voltage collapse phenomena. The proposed approach is based on the impedance match-based technique and the model-based technique. It combines the Thevenin equivalent (TE network method with cubic spline extrapolation technique and the continuation technique to achieve fast and accurate VSM computation for a bulk power grid. Moreover, the generator Q limits are taken into account for practical applications. Extensive case studies carried out on Institute of Electrical and Electronics Engineers (IEEE benchmark systems and the Taiwan Power Company (Taipower, Taipei, Taiwan system are used to demonstrate the effectiveness of the proposed approach.

Study of a cogeneration system (power and cooling) operating with two distinct prime-movers; Estudo de um sistema de cogeracao (potencia eletrica e refrigeracao) operando com dois motores termicos distintos

Energy Technology Data Exchange (ETDEWEB)

Benito, Yipsy Roque; Parise, Jose Alberto Reis [Pontificia Univ. Catolica do Rio de Janeiro (PUC-Rio), RJ (Brazil). Dept. de Engenharia Mecanica], e-mail: gipsyrb@mec.puc-rio.br, e-mail: parise@mec.puc-rio.br; Vargas, Jose Viriato Coelho [Universidade Federal do Parana (DEM/UFPR), Curitiba, PR (Brazil). Dept. de Engenharia Mecanica], e-mail: jvargas@demec.ufpr.br

2006-07-01

When dealing with complex thermal systems generating different energy products from a single fuel source (for example, as in the present work, electric and refrigeration power, with two gas-powered prime movers), one has to find the most energy efficient production scheme. To that end, each load demand (power and cooling), the efficiencies of each component, the cooling to power load ratio and the power distribution among the prime-movers, all have to be considered. This work presents the main equations for the energy balance of a cogeneration system with two primemovers (a gas turbine and an internal combustion engine), a waste heat driven absorption chiller and an auxiliary vapor compression chiller. The energy conservation equation was applied for each control volume comprising the system. Three possible cases were defined according to how cooling power demand and cooling power produced by the waste heat driven absorption cycle compared. As a result, characteristic performance curves were obtained for a typical application, allowing for the determination of maximum global efficiency values (represented by an energy conversion ratio) as a function of: the electric power to cooling power demand ratio, of the power generation distribution ratio among the two prime-movers, and of the part-load ratio operation of each prime mover. The resulting system of equations was solved by the software EES (Engineering Equation Solver{sup R}). (author)

Saving Energy in Industrial Companies: Case Studies of Energy Efficiency Programs in Large U.S. Industrial Corporations and the Role of Ratepayer-Funded Support

Energy Technology Data Exchange (ETDEWEB)

None, None

2017-03-08

This paper is designed for companies looking to cut costs through energy savings, ratepayer-funded program administrators interested in increasing large industrial company participation in energy efficiency program offerings, and state utility commissions.

Efficient One-click Browsing of Large Trajectory Sets

DEFF Research Database (Denmark)

Krogh, Benjamin Bjerre; Andersen, Ove; Lewis-Kelham, Edwin

2014-01-01

presents a novel query type called sheaf, where users can browse trajectory data sets using a single mouse click. Sheaves are very versatile and can be used for location-based advertising, travel-time analysis, intersection analysis, and reachability analysis (isochrones). A novel in-memory trajectory...... index compresses the data by a factor of 12.4 and enables execution of sheaf queries in 40 ms. This is up to 2 orders of magnitude faster than existing work. We demonstrate the simplicity, versatility, and efficiency of sheaf queries using a real-world trajectory set consisting of 2.7 million...

Toward efficient task assignment and motion planning for large-scale underwater missions

Directory of Open Access Journals (Sweden)

Somaiyeh MahmoudZadeh

2016-10-01

Full Text Available An autonomous underwater vehicle needs to possess a certain degree of autonomy for any particular underwater mission to fulfil the mission objectives successfully and ensure its safety in all stages of the mission in a large-scale operating field. In this article, a novel combinatorial conflict-free task assignment strategy, consisting of an interactive engagement of a local path planner and an adaptive global route planner, is introduced. The method takes advantage of the heuristic search potency of the particle swarm optimization algorithm to address the discrete nature of routing-task assignment approach and the complexity of nondeterministic polynomial-time-hard path planning problem. The proposed hybrid method is highly efficient as a consequence of its reactive guidance framework that guarantees successful completion of missions particularly in cluttered environments. To examine the performance of the method in a context of mission productivity, mission time management, and vehicle safety, a series of simulation studies are undertaken. The results of simulations declare that the proposed method is reliable and robust, particularly in dealing with uncertainties, and it can significantly enhance the level of a vehicle’s autonomy by relying on its reactive nature and capability of providing fast feasible solutions.

Temporal development and chemical efficiency of positive streamers in a large scale wire-plate reactor as a function of voltage waveform parameters

NARCIS (Netherlands)

Winands, G.J.J.; Liu, Zhen; Pemen, A.J.M.; Heesch, van E.J.M.; Yan, K.; Veldhuizen, van E.M.

2006-01-01

In this paper a large-scale pulsed corona system is described in which pulse parameters such as pulse rise-time, peak voltage, pulse width and energy per pulse can be varied. The chemical efficiency of the system is determined by measuring ozone production. The temporal and spatial development of

An Efficient Pipeline Wavefront Phase Recovery for the CAFADIS Camera for Extremely Large Telescopes

Directory of Open Access Journals (Sweden)

Eduardo Magdaleno

2009-12-01

Full Text Available In this paper we show a fast, specialized hardware implementation of the wavefront phase recovery algorithm using the CAFADIS camera. The CAFADIS camera is a new plenoptic sensor patented by the Universidad de La Laguna (Canary Islands, Spain: international patent PCT/ES2007/000046 (WIPO publication number WO/2007/082975. It can simultaneously measure the wavefront phase and the distance to the light source in a real-time process. The pipeline algorithm is implemented using Field Programmable Gate Arrays (FPGA. These devices present architecture capable of handling the sensor output stream using a massively parallel approach and they are efficient enough to resolve several Adaptive Optics (AO problems in Extremely Large Telescopes (ELTs in terms of processing time requirements. The FPGA implementation of the wavefront phase recovery algorithm using the CAFADIS camera is based on the very fast computation of two dimensional fast Fourier Transforms (FFTs. Thus we have carried out a comparison between our very novel FPGA 2D-FFTa and other implementations.

Meniscus-assisted solution printing of large-grained perovskite films for high-efficiency solar cells

Science.gov (United States)

He, Ming; Li, Bo; Cui, Xun; Jiang, Beibei; He, Yanjie; Chen, Yihuang; O'Neil, Daniel; Szymanski, Paul; Ei-Sayed, Mostafa A.; Huang, Jinsong; Lin, Zhiqun

2017-07-01

Control over morphology and crystallinity of metal halide perovskite films is of key importance to enable high-performance optoelectronics. However, this remains particularly challenging for solution-printed devices due to the complex crystallization kinetics of semiconductor materials within dynamic flow of inks. Here we report a simple yet effective meniscus-assisted solution printing (MASP) strategy to yield large-grained dense perovskite film with good crystallization and preferred orientation. Intriguingly, the outward convective flow triggered by fast solvent evaporation at the edge of the meniscus ink imparts the transport of perovskite solutes, thus facilitating the growth of micrometre-scale perovskite grains. The growth kinetics of perovskite crystals is scrutinized by in situ optical microscopy tracking to understand the crystallization mechanism. The perovskite films produced by MASP exhibit excellent optoelectronic properties with efficiencies approaching 20% in planar perovskite solar cells. This robust MASP strategy may in principle be easily extended to craft other solution-printed perovskite-based optoelectronics.

Integrating fuel cell power systems into building physical plants

Energy Technology Data Exchange (ETDEWEB)

Carson, J. [KCI Technologies, Inc., Hunt Valley, MD (United States)

1996-12-31

This paper discusses the integration of fuel cell power plants and absorption chillers to cogenerate chilled water or hot water/steam for all weather air conditioning as one possible approach to building system applications. Absorption chillers utilize thermal energy in an absorption based cycle to chill water. It is feasible to use waste heat from fuel cells to provide hydronic heating and cooling. Performance regimes will vary as a function of the supply and quality of waste heat. Respective performance characteristics of fuel cells, absorption chillers and air conditioning systems will define relationships between thermal and electrical load capacities for the combined systems. Specifically, this paper develops thermodynamic relationships between bulk electrical power and cooling/heating capacities for combined fuel cell and absorption chiller system in building applications.

Open access tools for quality-assured and efficient data entry in a large, state-wide tobacco survey in India.

Science.gov (United States)

Shewade, Hemant Deepak; Vidhubala, E; Subramani, Divyaraj Prabhakar; Lal, Pranay; Bhatt, Neelam; Sundaramoorthi, C; Singh, Rana J; Kumar, Ajay M V

2017-01-01

A large state-wide tobacco survey was conducted using modified version of pretested, globally validated Global Adult Tobacco Survey (GATS) questionnaire in 2015-22016 in Tamil Nadu, India. Due to resource constrains, data collection was carrid out using paper-based questionnaires (unlike the GATS-India, 2009-2010, which used hand-held computer devices) while data entry was done using open access tools. The objective of this paper is to describe the process of data entry and assess its quality assurance and efficiency. In EpiData language, a variable is referred to as 'field' and a questionnaire (set of fields) as 'record'. EpiData software was used for double data entry with adequate checks followed by validation. Teamviewer was used for remote training and trouble shooting. The EpiData databases (one each for each district and each zone in Chennai city) were housed in shared Dropbox folders, which enabled secure sharing of files and automatic back-up. Each database for a district/zone had separate file for data entry of household level and individual level questionnaire. Of 32,945 households, there were 111,363 individuals aged ≥15 years. The average proportion of records with data entry errors for a district/zone in household level and individual level file was 4% and 24%, respectively. These are the errors that would have gone unnoticed if single entry was used. The median (inter-quartile range) time taken for double data entry for a single household level and individual level questionnaire was 30 (24, 40) s and 86 (64, 126) s, respectively. Efficient and quality-assured near-real-time data entry in a large sub-national tobacco survey was performed using innovative, resource-efficient use of open access tools.

Efficiency profile method to study the hit efficiency of drift chambers

International Nuclear Information System (INIS)

Abyzov, A.; Bel'kov, A.; Lanev, A.; Spiridonov, A.; Walter, M.; Hulsbergen, W.

2002-01-01

A method based on the usage of efficiency profile is proposed to estimate the hit efficiency of drift chambers with a large number of channels. The performance of the method under real conditions of the detector operation has been tested analysing the experimental data from the HERA-B drift chambers

On asymptotically efficient simulation of large deviation probabilities.

NARCIS (Netherlands)

Dieker, A.B.; Mandjes, M.R.H.

2005-01-01

ABSTRACT: Consider a family of probabilities for which the decay is governed by a large deviation principle. To find an estimate for a fixed member of this family, one is often forced to use simulation techniques. Direct Monte Carlo simulation, however, is often impractical, particularly if the

Efficient Topology Estimation for Large Scale Optical Mapping

CERN Document Server

Elibol, Armagan; Garcia, Rafael

2013-01-01

Large scale optical mapping methods are in great demand among scientists who study different aspects of the seabed, and have been fostered by impressive advances in the capabilities of underwater robots in gathering optical data from the seafloor. Cost and weight constraints mean that low-cost ROVs usually have a very limited number of sensors. When a low-cost robot carries out a seafloor survey using a down-looking camera, it usually follows a predefined trajectory that provides several non time-consecutive overlapping image pairs. Finding these pairs (a process known as topology estimation) is indispensable to obtaining globally consistent mosaics and accurate trajectory estimates, which are necessary for a global view of the surveyed area, especially when optical sensors are the only data source. This book contributes to the state-of-art in large area image mosaicing methods for underwater surveys using low-cost vehicles equipped with a very limited sensor suite. The main focus has been on global alignment...

Increasing the efficiency of the TOUGH code for running large-scale problems in nuclear waste isolation

International Nuclear Information System (INIS)

Nitao, J.J.

1990-08-01

The TOUGH code developed at Lawrence Berkeley Laboratory (LBL) is being extensively used to numerically simulate the thermal and hydrologic environment around nuclear waste packages in the unsaturated zone for the Yucca Mountain Project. At the Lawrence Livermore National Laboratory (LLNL) we have rewritten approximately 80 percent of the TOUGH code to increase its speed and incorporate new options. The geometry of many requires large numbers of computational elements in order to realistically model detailed physical phenomena, and, as a result, large amounts of computer time are needed. In order to increase the speed of the code we have incorporated fast linear equation solvers, vectorization of substantial portions of code, improved automatic time stepping, and implementation of table look-up for the steam table properties. These enhancements have increased the speed of the code for typical problems by a factor of 20 on the Cray 2 computer. In addition to the increase in computational efficiency we have added several options: vapor pressure lowering; equivalent continuum treatment of fractures; energy and material volumetric, mass and flux accounting; and Stefan-Boltzmann radiative heat transfer. 5 refs

ON THE ECONOMIC EFFICIENCY OF ORGANIZATIONS: TOWARD A SOLUTION OF THE EFFICIENT GOVERNMENT ENTERPRISE PARADOX

Directory of Open Access Journals (Sweden)

Robert E. Wright

2007-01-01

Full Text Available The modern widely-held joint-stock corporation appears to epitomize the economically efficient large-scale organization. Some scholars observe, however, that other types of organizations, including government-owned enterprises, have also achieved high degrees of efficiency and that some joint stock corporations have been inefficient. It is here argued that the economic efficiency of organizations is largely a function of two major variables—markets tructure and incentives within the organization—and not organizational form or ownership structure per se. Case studies of two business firms: a mutual life insurer and a family-controlled publisher, and two industries: higher education and custom construction, demonstrate the importance of internal incentives and market structures to organizational economic efficiency.

Efficient numerical methods for the large-scale, parallel solution of elastoplastic contact problems

KAUST Repository

Frohne, Jö rg; Heister, Timo; Bangerth, Wolfgang

2015-01-01

© 2016 John Wiley & Sons, Ltd. Quasi-static elastoplastic contact problems are ubiquitous in many industrial processes and other contexts, and their numerical simulation is consequently of great interest in accurately describing and optimizing production processes. The key component in these simulations is the solution of a single load step of a time iteration. From a mathematical perspective, the problems to be solved in each time step are characterized by the difficulties of variational inequalities for both the plastic behavior and the contact problem. Computationally, they also often lead to very large problems. In this paper, we present and evaluate a complete set of methods that are (1) designed to work well together and (2) allow for the efficient solution of such problems. In particular, we use adaptive finite element meshes with linear and quadratic elements, a Newton linearization of the plasticity, active set methods for the contact problem, and multigrid-preconditioned linear solvers. Through a sequence of numerical experiments, we show the performance of these methods. This includes highly accurate solutions of a three-dimensional benchmark problem and scaling our methods in parallel to 1024 cores and more than a billion unknowns.

Efficient numerical methods for the large-scale, parallel solution of elastoplastic contact problems

KAUST Repository

Frohne, Jörg

2015-08-06

© 2016 John Wiley & Sons, Ltd. Quasi-static elastoplastic contact problems are ubiquitous in many industrial processes and other contexts, and their numerical simulation is consequently of great interest in accurately describing and optimizing production processes. The key component in these simulations is the solution of a single load step of a time iteration. From a mathematical perspective, the problems to be solved in each time step are characterized by the difficulties of variational inequalities for both the plastic behavior and the contact problem. Computationally, they also often lead to very large problems. In this paper, we present and evaluate a complete set of methods that are (1) designed to work well together and (2) allow for the efficient solution of such problems. In particular, we use adaptive finite element meshes with linear and quadratic elements, a Newton linearization of the plasticity, active set methods for the contact problem, and multigrid-preconditioned linear solvers. Through a sequence of numerical experiments, we show the performance of these methods. This includes highly accurate solutions of a three-dimensional benchmark problem and scaling our methods in parallel to 1024 cores and more than a billion unknowns.

Evaluation of biochar powder on oxygen supply efficiency and global warming potential during mainstream large-scale aerobic composting.

Science.gov (United States)

He, Xueqin; Chen, Longjian; Han, Lujia; Liu, Ning; Cui, Ruxiu; Yin, Hongjie; Huang, Guangqun

2017-12-01

This study investigated the effects of biochar powder on oxygen supply efficiency and global warming potential (GWP) in the large-scale aerobic composting pattern which includes cyclical forced-turning with aeration at the bottom of composting tanks in China. A 55-day large-scale aerobic composting experiment was conducted in two different groups without and with 10% biochar powder addition (by weight). The results show that biochar powder improves the holding ability of oxygen, and the duration time (O 2 >5%) is around 80%. The composting process with above pattern significantly reduce CH 4 and N 2 O emissions compared to the static or turning-only styles. Considering the average GWP of the BC group was 19.82% lower than that of the CK group, it suggests that rational addition of biochar powder has the potential to reduce the energy consumption of turning, improve effectiveness of the oxygen supply, and reduce comprehensive greenhouse effects. Copyright © 2017. Published by Elsevier Ltd.

Maximization of primary energy savings of solar heating and cooling systems by transient simulations and computer design of experiments

International Nuclear Information System (INIS)

Calise, F.; Palombo, A.; Vanoli, L.

2010-01-01

In this paper, the simulation of the performance of solar-assisted heating and cooling systems is analyzed. Three different plant layouts are considered: (i) the first one consists of evacuated solar collectors and a single-stage LiBr-H 2 O absorption chiller; here in order to integrate the system in case of insufficient solar radiation, an electric water-cooled chiller is activated; (ii) configuration of the secondly considered system is similar to the first one, but the absorption chiller and the solar collector area are sized for balancing about 30% of the building cooling load only; (iii) the layout of the thirdly considered system differs from the first one since the auxiliary electric chiller is replaced by a gas-fired heater. Such system configurations also include: circulation pumps, storage tanks, feedback controllers, mixers, diverters and on/off hysteresis controllers. All such devices are modelled for maximizing the system energy efficiency. In order to simulate the systems' performance for dynamic heating/cooling loads, a single-lumped capacitance building is also modelled and implemented in the computer code. A cost model is also developed in order to calculate the systems' operating and capital costs. All the models and the relative simulations are carried out by TRNSYS. A design of experiment procedure is also included. By such tool the effects of the system operating parameters' variation on the relative energy efficiency are analyzed. In addition, the set of synthesis/design variables maximizing the system's energetic performance can be also identified. The annual primary energy saving is chosen as the optimization objective function, whereas collector slope, pump flows, set-point temperatures and tank volume are selected as optimizing system design variables. A case study was developed for an office building located in South Italy. Here, the energetic and the economic analysis for all the three considered system layouts are carried out. The

Ground source heat pump performance in case of high humidity soil and yearly balanced heat transfer

International Nuclear Information System (INIS)

Schibuola, Luigi; Tambani, Chiara; Zarrella, Angelo; Scarpa, Massimiliano

2013-01-01

Highlights: • GSHPs are simulated in case of humid soil and yearly balanced heat transfer. • Humid soil and yearly balanced heat transfer imply higher compactness of GSHPs. • Resulting GSHPs are compared with other traditional and innovative HVAC systems. • GSHPs score best, especially in case of inverter-driven compressors. - Abstract: Ground source heat pump (GSHP) systems are spreading also in Southern Europe, due to their high energy efficiency both in heating and in cooling mode. Moreover, they are particularly suitable in historical cities because of difficulties in the integration of heating/cooling systems into buildings subjected to historical preservation regulations. In these cases, GSHP systems, especially the ones provided with borehole heat exchangers, are a suitable solution instead of gas boilers, air-cooled chillers or cooling towers. In humid soils, GSHP systems are even more interesting because of their enhanced performance due to higher values of soil thermal conductivity and capacity. In this paper, GSHP systems operating under these boundary conditions are analyzed through a specific case study set in Venice and related to the restoration of an historical building. With this analysis the relevant influences of soil thermal conductivity and yearly balanced heat transfer in the design of the borehole field are shown. In particular, the paper shows the possibility to achieve higher compactness of the borehole field footprint area when yearly balanced heat transfer in the borehole field is expected. Then, the second set of results contained in the paper shows how GSHP systems designed for high humidity soils and yearly balanced heat loads at the ground side, even if characterized by a compact footprint area, may still ensure better performance than other available and more common technologies such as boilers, air-cooled chillers, chillers coupled with cooling towers and heat pumps and chillers coupled with lagoon water. As a consequence

Ab-sorption machines for heating and cooling in future energy systems - Final report

Energy Technology Data Exchange (ETDEWEB)

Tozer, R.; Gustafsson, M.

2000-12-15

safety etc. The lack of trained maintenance people is a major concern. A brief survey of R&D activities is given in Chapter 5. In Chapter 6, Future Opportunities, an analysis of the market factors shows that the market pull favours sorption technologies in different ways. A chart shows, in decreasing order of market pull, the following technologies: Direct-fired or boiler-driven absorption chillers; and Absorption chillers driven by waste heat, heat recovery or combined heat and power (CHP) systems. Far less prominent are: Absorption heat pumps; then Absorption heat transformers; and finally Adsorption chillers. The chart shows that environmental benefit is inversely proportional to the market pull and share of sorption technologies. The main market barriers are considered to be the relatively high first costs of absorption plant, and the lack of knowledge of sorption technology by technicians, engineers, and professionals. In practice, different technologies are found to be most suitable for different countries, mainly depending on their energy infrastructure and particularly on how the country's electricity is produced. Recommendations are made regarding policies to promote sorption technology (where it is environmentally beneficial), and with regard to future R&D. In Chapter 7, Conclusions, it is emphasised that the application of sorption technology is not in all cases the best choice for the environment. Detailed conclusions are that: Direct-fired chillers should be phased out slowly, in the short and medium term; Encouragement should be given to absorption and adsorption chillers using waste heat, heat recovery or applied heat; Sorption chillers applied to CHP systems have an existing market pull, and benefit the environment. However, the overall efficiency has to be relatively high with respect to each nation's power production, throughout the life of the system; Absorption heat pumps (including reversible heat pumps) will be available on the market in

Nitrogen use efficiency (NUE)

NARCIS (Netherlands)

Oenema, O.

2015-01-01

There is a need for communications about resource use efficiency and for measures to increase the use efficiency of nutrients in relation to food production. This holds especially for nitrogen. Nitrogen (N) is essential for life and a main nutrient element. It is needed in relatively large

From energy efficiency towards resource efficiency within the Ecodesign Directive

DEFF Research Database (Denmark)

Bundgaard, Anja Marie; Mosgaard, Mette; Remmen, Arne

2017-01-01

on the most significant environmental impact has often resulted in a focus on energy efficiency in the use phase. Therefore, the Ecodesign Directive should continue to target resource efficiency aspects but also consider environ- mental aspects with a large improvement potential in addition to the most...... significant environmental impact. For the introduction of resource efficiency requirements into the Ecodesign Directive, these requirements have to be included in the preparatory study. It is therefore recommended to broaden the scope of the Methodology for the Ecodesign of Energy-related products and the Eco......The article examines the integration of resource efficiency into the European Ecodesign Directive. The purpose is to analyse the processes and stakeholder interactions, which formed the basis for integrating resource efficiency requirements into the implementing measure for vacuum cleaners...

Electro-spray deposition of a mesoporous TiO2 charge collection layer: toward large scale and continuous production of high efficiency perovskite solar cells.

Science.gov (United States)

Kim, Min-cheol; Kim, Byeong Jo; Yoon, Jungjin; Lee, Jin-wook; Suh, Dongchul; Park, Nam-gyu; Choi, Mansoo; Jung, Hyun Suk

2015-12-28

The spin-coating method, which is widely used for thin film device fabrication, is incapable of large-area deposition or being performed continuously. In perovskite hybrid solar cells using CH(3)NH(3)PbI(3) (MAPbI(3)), large-area deposition is essential for their potential use in mass production. Prior to replacing all the spin-coating process for fabrication of perovskite solar cells, herein, a mesoporous TiO(2) electron-collection layer is fabricated by using the electro-spray deposition (ESD) system. Moreover, impedance spectroscopy and transient photocurrent and photovoltage measurements reveal that the electro-sprayed mesoscopic TiO(2) film facilitates charge collection from the perovskite. The series resistance of the perovskite solar cell is also reduced owing to the highly porous nature of, and the low density of point defects in, the film. An optimized power conversion efficiency of 15.11% is achieved under an illumination of 1 sun; this efficiency is higher than that (13.67%) of the perovskite solar cell with the conventional spin-coated TiO(2) films. Furthermore, the large-area coating capability of the ESD process is verified through the coating of uniform 10 × 10 cm(2) TiO(2) films. This study clearly shows that ESD constitutes therefore a viable alternative for the fabrication of high-throughput, large-area perovskite solar cells.

Large nuclear steam turbine plants

International Nuclear Information System (INIS)

Urushidani, Haruo; Moriya, Shin-ichi; Tsuji, Kunio; Fujita, Isao; Ebata, Sakae; Nagai, Yoji.

1986-01-01

The technical development of the large capacity steam turbines for ABWR plants was partially completed, and that in progress is expected to be completed soon. In this report, the outline of those new technologies is described. As the technologies for increasing the capacity and heightening the efficiency, 52 in long blades and moisture separating heaters are explained. Besides, in the large bore butterfly valves developed for making the layout compact, the effect of thermal efficiency rise due to the reduction of pressure loss can be expected. As the new technology on the system side, the simplification of the turbine system and the effect of heightening the thermal efficiency by high pressure and low pressure drain pumping-up method based on the recent improvement of feed water quality are discussed. As for nuclear steam turbines, the actual records of performance of 1100 MW class, the largest output at present, have been obtained, and as a next large capacity machine, the development of a steam turbine of 1300 MWe class for an ABWR plant is in progress. It can be expected that by the introduction of those new technologies, the plants having high economical efficiency are realized. (Kako, I.)

Energy performance of supermarket refrigeration and air conditioning integrated systems working with natural refrigerants

International Nuclear Information System (INIS)

Cecchinato, Luca; Corradi, Marco; Minetto, Silvia

2012-01-01

The current trends in commercial refrigeration aim at reducing the synthetic refrigerant charge, either by minimising the internal volume of the circuit or by utilising natural refrigerants, and at energy saving. The energy efficiency of supermarkets can be improved by optimising components design, recovering thermal and refrigerating energy, adopting innovative technology solutions, integrating the HVAC system with medium temperature and low temperature refrigeration plants and, finally, reducing thermal loads on refrigerated cases. This study aims at investigating the performance of different lay-out and technological solutions where only natural refrigerants are used and at finding the potential for improving energy efficiency over the traditional systems in different climates. In the analysis, chillers and heat pumps working with ammonia or propane, medium temperature systems working with ammonia or propane and carbon dioxide as heat transfer fluid or with carbon dioxide as the refrigerant and low temperature systems working with carbon dioxide are considered and benchmarked with a state-of-the-art HFCs based plant. The most efficient investigated solution enables an annual energy saving higher than 15% with respect to the baseline solution for all the considered climates. - Highlights: ► Different natural refrigerants supermarket HVAC and R integrated systems are analysed. ► Some of the proposed solutions offer a significant benefit over the baseline one. ► Up to 18.7% energy saving is achieved in the considered climates. ► The refrigeration unit condensation by the AC chiller offers the poorest results.

New cooling regulation technology of secondary cooling station in DCS

Energy Technology Data Exchange (ETDEWEB)

Zhou, Xuan; Yan, Jun-wei; Zhu, Dong-sheng; Liu, Fei-long; Lei, Jun-xi [The Key Lab of Enhanced Heat Transfer and Energy Conservation of Ministry of Education, School of Chemical and Energy Engineering, South China University of Technology, Guangzhou 510641 (China); Liang, Lie-quan [The Key Lab of E-Commerce Market Application Technology of Guangdong Province, Guangdong University of Business Studies, Guangzhou 510320 (China)

2008-07-01

In this paper, a kind of new control technology of secondary cooling station (constant flow rate/variable temperature difference) in district cooling system (DCS) is proposed in view of serial consequences including low efficiency and high operating cost caused by low temperature of supply water in DCS. This technology has been applied in DCS of Guangzhou University City. The result has already indicated that such technology can increase the supply and return temperatures of buildings, return water temperature of primary side in the plate heat exchanger unit, moreover, the efficiency of both the chiller and the whole system are improved significantly. (author)

Dynamic classification system in large-scale supervision of energy efficiency in buildings

International Nuclear Information System (INIS)

Kiluk, S.

2014-01-01

Highlights: • Rough set approximation of classification improves energy efficiency prediction. • Dynamic features of diagnostic classification allow for its precise prediction. • Indiscernibility in large population enhances identification of process features. • Diagnostic information can be refined by dynamic references to local neighbourhood. • We introduce data exploration validation based on system dynamics and uncertainty. - Abstract: Data mining and knowledge discovery applied to the billing data provide the diagnostic instruments for the evaluation of energy use in buildings connected to a district heating network. To ensure the validity of an algorithm-based classification system, the dynamic properties of a sequence of partitions for consecutive detected events were investigated. The information regarding the dynamic properties of the classification system refers to the similarities between the supervised objects and migrations that originate from the changes in the building energy use and loss similarity to their neighbourhood and thus represents the refinement of knowledge. In this study, we demonstrate that algorithm-based diagnostic knowledge has dynamic properties that can be exploited with a rough set predictor to evaluate whether the implementation of classification for supervision of energy use aligns with the dynamics of changes of district heating-supplied building properties. Moreover, we demonstrate the refinement of the current knowledge with the previous findings and we present the creation of predictive diagnostic systems based on knowledge dynamics with a satisfactory level of classification errors, even for non-stationary data

Case Study for the ARRA-Funded Ground Source Heat Pump Demonstration at Ball State University

Energy Technology Data Exchange (ETDEWEB)

Im, Piljae [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Liu, Xiaobing [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Henderson, Jr., Hugh [CDH Energy Corp., Beijing (China)

2016-12-01

With funding provided by the American Recovery and Reinvestment Act (ARRA), 26 ground-source heat pump (GSHP) projects were competitively selected in 2009 to demonstrate the benefits of GSHP systems and innovative technologies for cost reduction and/or performance improvement. One of the selected demonstration projects is a district central GSHP system installed at Ball State University (BSU) in Muncie, IN. Prior to implementing the district GSHP system, 47 major buildings in BSU were served by a central steam plant with four coal-fired and three natural-gas-fired steam boilers. Cooling was provided by five water-cooled centrifugal chillers at the District Energy Station South (DESS). The new district GSHP system replaced the existing coal-fired steam boilers and conventional water-cooled chillers. It uses ground-coupled heat recovery (HR) chillers to meet the simultaneous heating and cooling demands of the campus. The actual performance of the GSHP system was analyzed based on available measured data from August 2015 through July 2016, construction drawings, maintenance records, personal communications, and construction costs. Since Phase 1 was funded in part by the ARRA grant, it is the focus of this case study. The annual energy consumption of the GSHP system was calculated based on the available measured data and other related information. It was compared with the performance of a baseline scenario— a conventional water-cooled chiller and natural-gas-fired boiler system, both of which meet the minimum energy efficiencies allowed by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE 90.1-2013). The comparison was made to determine source energy savings, energy cost savings, and CO2 emission reductions achieved by the GSHP system. A cost analysis was performed to evaluate the simple payback of the GSHP system. The following sections summarize the results of the analysis, the lessons learned, and recommendations for improvement

Evaluation of economical efficiency of the Osaki large hydroponic facilities; Osaki ogata suiko shisetsu no keizaisei hyoka

Energy Technology Data Exchange (ETDEWEB)

Yonezawa, K [Chugoku Electric Power Co. Inc., Hiroshima (Japan)

1996-03-25

A demonstrative test was conducted to verify economical efficiency of practical scale hydroponic horticulture under structure making use of a part of the Osaki thermal power plant to be constructed. In the test, the hydroponic culture of leek and tomatoes was carried out for six years starting 1989 to study its economical efficiency. Using the M-type hydroponic culture facilities, the structures are 1200m wide, 29m long, and 21 tons in the culture liquid level in case of leek, and 350m wide, 29m long, and 10 tons in the culture liquid level in case of tomatoes. The evaluation was made estimating the crop amount of leek as about 35 tons and that of tomatoes as about 60 tons and regarding that the sales amount is equal to the crop amount. The sales amount of leek is 28 million yen, and when seeking income/expenditure from expenses, deficit of 1 million yen per 30 a cannot be avoided excluding the equipment depreciation cost. As to tomatoes, the shipment cost is approximately 14 million yen without the equipment depreciation cost, but the sales amount is approximately 13-19 million yen largely affected by the unit price. A study on the sale method is needed. 7 figs., 11 tabs.

An Investigation of the High Efficiency Estimation Approach of the Large-Scale Scattered Point Cloud Normal Vector

Directory of Open Access Journals (Sweden)

Xianglin Meng

2018-03-01

Full Text Available The normal vector estimation of the large-scale scattered point cloud (LSSPC plays an important role in point-based shape editing. However, the normal vector estimation for LSSPC cannot meet the great challenge of the sharp increase of the point cloud that is mainly attributed to its low computational efficiency. In this paper, a novel, fast method-based on bi-linear interpolation is reported on the normal vector estimation for LSSPC. We divide the point sets into many small cubes to speed up the local point search and construct interpolation nodes on the isosurface expressed by the point cloud. On the premise of calculating the normal vectors of these interpolated nodes, a normal vector bi-linear interpolation of the points in the cube is realized. The proposed approach has the merits of accurate, simple, and high efficiency, because the algorithm only needs to search neighbor and calculates normal vectors for interpolation nodes that are usually far less than the point cloud. The experimental results of several real and simulated point sets show that our method is over three times faster than the Elliptic Gabriel Graph-based method, and the average deviation is less than 0.01 mm.

Energy Efficiency Roadmap for Uganda, Making Energy Efficiency Count. Executive Summary

Energy Technology Data Exchange (ETDEWEB)

de la Rue du Can, Stephane; Pudleiner, David; Jones, David; Khan, Aleisha

2017-06-15

Like many countries in Sub-Saharan Africa, Uganda has focused its energy sector investments largely on increasing energy access by increasing energy supply. The links between energy efficiency and energy access, the importance of energy efficiency in new energy supply, and the multiple benefits of energy efficiency for the level and quality of energy available, have been largely overlooked. Implementing energy efficiency in parallel with expanding both the electricity grid and new clean energy generation reduces electricity demand and helps optimize the power supply so that it can serve more customers reliably at minimum cost. Ensuring efficient appliances are incorporated into energy access efforts provides improved energy services to customers. Energy efficiency is an important contributor to access to modern energy. This Energy Efficiency Roadmap for Uganda (Roadmap) is a response to the important role that electrical energy efficiency can play in meeting Uganda’s energy goals. Power Africa and the United Nations Sustainable Energy for All (SEforALL) initiatives collaborated with more than 24 stakeholders in Uganda to develop this document. The document estimates that if the most efficient technologies on the market were adopted, 2,224 gigawatt hours could be saved in 2030 across all sectors, representing 31% of the projected load. This translates into 341 megawatts of peak demand reductions, energy access to an additional 6 million rural customers and reduction of carbon dioxide emissions by 10.6 million tonnes in 2030. The Roadmap also finds that 91% of this technical potential is cost-effective, and 47% is achievable under conservative assumptions. The Roadmap prioritizes recommendations for implementing energy efficiency and maximizing benefits to meet the goals and priorities established in Uganda’s 2015 SEforALL Action Agenda. One important step is to create and increase demand for efficiency through long-term enabling policies and financial incentives

A thermodynamic perspective to study energy performance of vacuum-based membrane dehumidification

KAUST Repository

Bui, Thuan Duc

2017-05-13

In humid environments, decoupling the latent and sensible cooling loads - dehumidifying - can significantly improve chiller efficiency. Here, a basic limit for dehumidification efficiency is established from fundamental thermodynamics. This is followed by the derivation of how this limit is modified when the pragmatic constraint of a finite flux must be accommodated. These limits allow one to identify promising system modifications, and to quantify their impact. The focus is on vacuum-based membrane dehumidification. New high-efficiency configurations are formulated, most notably, by coupling pumping with condensation. More than an order-of-magnitude improvement in efficiency is achievable. It is contingent on water vapor exiting at its saturation pressure rather than at ambient pressure. Sensitivity studies to recovery ratio, temperature, relative humidity and membrane selectivity are also presented.

Energy Demands and Efficiency Strategies in Data Center Buildings

Energy Technology Data Exchange (ETDEWEB)

Shehabi, Arman [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2009-09-01

Information technology (IT) is becoming increasingly pervasive throughout society as more data is digitally processed, stored, and transferred. The infrastructure that supports IT activity is growing accordingly, and data center energy demands haveincreased by nearly a factor of four over the past decade. Data centers house IT equipment and require significantly more energy to operate per unit floor area thanconventional buildings. The economic and environmental ramifications of continued data center growth motivate the need to explore energy-efficient methods to operate these buildings. A substantial portion of data center energy use is dedicated to removing the heat that is generated by the IT equipment. Using economizers to introduce large airflow rates of outside air during favorable weather could substantially reduce the energy consumption of data center cooling. Cooling buildings with economizers is an established energy saving measure, but in data centers this strategy is not widely used, partly owing to concerns that the large airflow rates would lead to increased indoor levels of airborne particles, which could damage IT equipment. The environmental conditions typical of data centers and the associated potential for equipment failure, however, are not well characterized. This barrier to economizer implementation illustrates the general relationship between energy use and indoor air quality in building design and operation. This dissertation investigates how building design and operation influence energy use and indoor air quality in data centers and provides strategies to improve both design goals simultaneously.As an initial step toward understanding data center air quality, measurements of particle concentrations were made at multiple operating northern California data centers. Ratios of measured particle concentrations in conventional data centers to the corresponding outside concentrations were significantly lower than those reported in the literature

Novel Controls for Time-Dependent Economic Dispatch of Combined Cooling Heating and Power (CCHP)

Energy Technology Data Exchange (ETDEWEB)

Samuelsen, Scott; Brouwer, Jack

2013-08-31

The research and development effort detailed in this report directly addresses the challenge of reducing U.S. industrial energy and carbon intensity by contributing to an increased understanding of potential CCHP technology, the CCHP market and the challenges of widespread adoption. This study developed a number of new tools, models, and approaches for the design, control, and optimal dispatch of various CCHP technologies. The UC Irvine campus served as a ‘living laboratory’ of new CCHP technologies and enabled the design and demonstration of several novel control methods. In particular, the integration of large scale thermal energy storage capable of shifting an entire day of cooling demand required a novel approach to the CCHP dispatch optimization. The thermal energy storage proved an economically viable resource which reduced both costs and emissions by enabling generators and chillers to operate under steady high efficiency conditions at all times of the day.

Stochastic efficiency: five case studies

International Nuclear Information System (INIS)

Proesmans, Karel; Broeck, Christian Van den

2015-01-01

Stochastic efficiency is evaluated in five case studies: driven Brownian motion, effusion with a thermo-chemical and thermo-velocity gradient, a quantum dot and a model for information to work conversion. The salient features of stochastic efficiency, including the maximum of the large deviation function at the reversible efficiency, are reproduced. The approach to and extrapolation into the asymptotic time regime are documented. (paper)

Development of Natural Gas Fired Combined Cycle Plant for Tri-Generation of Power, Cooling and Clean Water Using Waste Heat Recovery: Techno-Economic Analysis

OpenAIRE

Mohan, Gowtham; Dahal, Sujata; Kumar, Uday; Martin, Andrew; Kayal, Hamid

2014-01-01

Tri-generation is one of the most efficient ways for maximizing the utilization of available energy. Utilization of waste heat (flue gases) liberated by the Al-Hamra gas turbine power plant is analyzed in this research work for simultaneous production of: (a) electricity by combining steam rankine cycle using heat recovery steam generator (HRSG); (b) clean water by air gap membrane distillation (AGMD) plant; and (c) cooling by single stage vapor absorption chiller (VAC). The flue gases liber...

78 FR 28163 - Zentox Corporation; Withdrawal of Food Additive Petition

Science.gov (United States)

2013-05-14

... antimicrobial agent in poultry process chiller water. FOR FURTHER INFORMATION CONTACT: Judith Kidwell, Center... Zentox Corp., c/o Burdock Group, 801 North Orange Ave., suite 710, Orlando, FL 32801, had filed a food... safe use of monochloramine as an antimicrobial agent in poultry process chiller water. Zentox Corp. has...

A Solar Heating and Cooling System in a Nearly Zero-Energy Building: A Case Study in China

Directory of Open Access Journals (Sweden)

Zhifeng Sun

2017-01-01

Full Text Available The building sector accounts for more than 40% of the global energy consumption. This consumption may be lowered by reducing building energy requirements and using renewable energy in building energy supply systems. Therefore, a nearly zero-energy building, incorporating a solar heating and cooling system, was designed and built in Beijing, China. The system included a 35.17 kW cooling (10-RT absorption chiller, an evacuated tube solar collector with an aperture area of 320.6 m2, two hot-water storage tanks (with capacities of 10 m3 and 30 m3, respectively, two cold-water storage tanks (both with a capacity of 10 m3, and a 281 kW cooling tower. Heat pump systems were used as a backup. At a value of 25.2%, the obtained solar fraction associated with the cooling load was close to the design target of 30%. In addition, the daily solar collector efficiency and the chiller coefficient of performance (COP varied from 0.327 to 0.507 and 0.49 to 0.70, respectively.

Thermoeconomic analysis of an integrated multi-effect desalination thermal vapor compression (MED-TVC) system with a trigeneration system using triple-pressure HRSG

Science.gov (United States)

Ghaebi, Hadi; Abbaspour, Ghader

2018-05-01

In this research, thermoeconomic analysis of a multi-effect desalination thermal vapor compression (MED-TVC) system integrated with a trigeneration system with a gas turbine prime mover is carried out. The integrated system comprises of a compressor, a combustion chamber, a gas turbine, a triple-pressure (low, medium and high pressures) heat recovery steam generator (HRSG) system, an absorption chiller cycle (ACC), and a multi-effect desalination (MED) system. Low pressure steam produced in the HRSG is used to drive absorption chiller cycle, medium pressure is used in desalination system and high pressure superheated steam is used for heating purposes. For thermodynamic and thermoeconomic analysis of the proposed integrated system, Engineering Equation Solver (EES) is used by employing mass, energy, exergy, and cost balance equations for each component of system. The results of the modeling showed that with the new design, the exergy efficiency in the base design will increase to 57.5%. In addition, thermoeconomic analysis revealed that the net power, heating, fresh water and cooling have the highest production cost, respectively.

Acoustic Emission of Large PRSEUS Structures (Pultruded Rod Stitched Efficient Unitized Structure)

Science.gov (United States)

Horne, Michael R.; Juarez, Peter D.

2016-01-01

In the role of structural health monitoring (SHM), Acoustic Emission (AE) analysis is being investigated as an effective method for tracking damage development in large composite structures under load. Structures made using Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) for damage tolerant, light, and economical airframe construction are being pursued by The Boeing Company and NASA under the Environmentally Responsible Aircraft initiative (ERA). The failure tests of two PRSEUS substructures based on the Boeing Hybrid Wing Body fuselage concept were conducted during third quarter 2011 and second quarter 2015. One fundamental concern of these tests was determining the effectiveness of the stitched integral stiffeners to inhibit damage progression. By design, severe degradation of load carrying capability should not occur prior to Design Ultimate Load (DUL). While minor damage prior to DUL was anticipated, the integral stitching should not fail since this would allow a stiffener-skin delamination to progress rapidly and alter the transfer of load into the stiffeners. In addition, the stiffeners should not fracture because they are fundamental to structural integrity. Getting the best information from each AE sensor is a primary consideration because a sparse network of sensors is implemented. Sensitivity to stiffener-contiguous degradation is supported by sensors near the stiffeners, which increases the coverage per sensor via AE waveguide actions. Some sensors are located near potentially critical areas or "critical zones" as identified by numerical analyses. The approach is compared with the damage progression monitored by other techniques (e.g. ultrasonic C-scan).

AFEAP cloning: a precise and efficient method for large DNA sequence assembly.

Science.gov (United States)

Zeng, Fanli; Zang, Jinping; Zhang, Suhua; Hao, Zhimin; Dong, Jingao; Lin, Yibin

2017-11-14

Recent development of DNA assembly technologies has spurred myriad advances in synthetic biology, but new tools are always required for complicated scenarios. Here, we have developed an alternative DNA assembly method named AFEAP cloning (Assembly of Fragment Ends After PCR), which allows scarless, modular, and reliable construction of biological pathways and circuits from basic genetic parts. The AFEAP method requires two-round of PCRs followed by ligation of the sticky ends of DNA fragments. The first PCR yields linear DNA fragments and is followed by a second asymmetric (one primer) PCR and subsequent annealing that inserts overlapping overhangs at both sides of each DNA fragment. The overlapping overhangs of the neighboring DNA fragments annealed and the nick was sealed by T4 DNA ligase, followed by bacterial transformation to yield the desired plasmids. We characterized the capability and limitations of new developed AFEAP cloning and demonstrated its application to assemble DNA with varying scenarios. Under the optimized conditions, AFEAP cloning allows assembly of an 8 kb plasmid from 1-13 fragments with high accuracy (between 80 and 100%), and 8.0, 11.6, 19.6, 28, and 35.6 kb plasmids from five fragments at 91.67, 91.67, 88.33, 86.33, and 81.67% fidelity, respectively. AFEAP cloning also is capable to construct bacterial artificial chromosome (BAC, 200 kb) with a fidelity of 46.7%. AFEAP cloning provides a powerful, efficient, seamless, and sequence-independent DNA assembly tool for multiple fragments up to 13 and large DNA up to 200 kb that expands synthetic biologist's toolbox.

Power, heat and cooling production for a group of buildings (CHCP); Integrerade loesningar foer produktion av kraft, vaerme och kyla (CHCP) i grupper av byggnader med el-, vaerme- och kylbehov

Energy Technology Data Exchange (ETDEWEB)

Nelson, Corfitz [Svenskt Gastekniskt Center AB, Malmoe (Sweden); Bjurstroem, Henrik; Cronholm, Lars-Aake; Forsberg, Maya [AaF-Energi och Miljoe AB, Stockholm (Sweden)

2005-04-01

Small-scale production and distribution of power, heat and cooling (CHCP) for a group of buildings is described in this report on a general level. Possible system solutions are identified and a summary of the state-of-the-art is provided. Costs have been compared for different system solutions using a fictitious group of buildings in a case study. CHCP (Combined Heat, Cooling and Power) is an acronym used for a compact cogeneration unit (CHP) that also provides cooling, where cooling may be produced using an absorption cooling machine. The advantage of heat-driven cooling process combined with a cogeneration unit offers is an increase of the annual number of hours during which the cogeneration is operated. This should lead to an increased competitiveness for small-scale cogeneration also in Sweden, which should become even better if the price for electricity continues to increase. Systems with cogeneration and cooling are often associated with the concept of 'distributed generation' of electricity and with units in single buildings such as hotels, hospitals, offices, shopping centers etc. They could also be considered for groups of buildings connected to a small distribution network for district heating, and district cooling. Both steam and hot water are possible energy carriers. The focus of the study was small-scale cogeneration units in the range 0,1 to 2 MW{sub e} with natural gas as fuel. For the sake of the analysis of profitability and of investment, a fictitious area has been defined with four buildings: two hotels, an office and a shopping centre. The maximum total heat and cooling loads of this area are 8 MW heat and 3.5 MW cooling. The alternatives to heat-only boilers and electric chillers in each building studied were based on piping networks. The results from the calculations show that local production of electric power, heat and cooling is possible in buildings and areas with large energy consumption. With prices and assumptions as in the

PWR Core II blanket fuel disposition recommendation of storage option study

International Nuclear Information System (INIS)

Dana, C.M.

1995-01-01

After review of the options available for current storage of T Plant Fuel the recommended option is wet storage without the use of chillers. A test has been completed that verifies the maximum temperature reached is below the industrial standard for storage of spent fuel. This option will be the least costly and still maintain the fuel in a safe environment. The options that were evaluated included dry storage with and without chillers, and wet storage with and without chillers. Due to the low decay heat of the Shippingport Core II Blanket fuel assemblies the fuel pool temperature will not exceed 100 deg. F

Efficient adaptive retrieval and mining in large multimedia databases

DEFF Research Database (Denmark)

Assent, Ira

for a variety of features such as color, shape or texture. Time series data is prevalent for sensor measurements, stock data, and may even be applied to shapes and other features as well. For these data types, effective adaptable similarity models are usually computationally far too complex for usage in large...

76 FR 69147 - Energy Conservation Program for Consumer Products: Proposed Determination To Treat Non-Compressor...

Science.gov (United States)

2011-11-08

... use for such products, (e.g., thermoelectric wine chillers) is likely to exceed the 100 kilowatt-hour.... DOE's analysis describes both the burdens and benefits of potential standards, pursuant to 42 U.S.C... efforts to amend the standards for these products, interested parties urged DOE to include wine chillers...

Exergetic and energetic comparison of LiCl-H_2O and LiBr-H_2O working pairs in a solar absorption cooling system

International Nuclear Information System (INIS)

Bellos, Evangelos; Tzivanidis, Christos; Antonopoulos, Kimon A.

2016-01-01

Highlights: • Two working pairs (LiCl-H_2O and LiBr-H_2O) are examined in a solar absorption chiller. • The examined single effect absorption chiller is driven by flat plate collectors. • The system is analyzed energetically and energetically for 3 ambient temperatures. • LiCl-H_2O performs better than LiBr-H_2O in all the examined cases. • The optimum operating temperature is lower for the case of pair LiCl-H_2O. - Abstract: The objective of this study is to investigate the use of an alternative working pair in a solar absorption cooling system. LiCl-H_2O is the new examined pair and it is compared energetically and exegetically with the conventional pair LiBr-H_2O, which is the most usual in air-conditioning applications. The simplest solar cooling system is analyzed in order to focus in the comparison between these working fluids. Specifically, flat plate collectors, coupled with a storage tank, feed the single effect absorption chiller which produces 250 kW cooling at 10 °C. The two pairs are examined parametrically for various heat source temperature levels and for three ambient temperature levels (25 °C, 30 °C and 35 °C). The minimization of the collecting area, which means maximum exergetic efficiency, is the optimization goal in every case. The final results show that LiCl-H_2O pair performs better in all cases by giving greater exergetic efficiency. More specifically, about 8% lower collecting area is required to cover the demanded cooling load with this working pair. Another interesting result is that the optimum heat source temperature for the LiCl-H_2O is roughly lower than the respective for the LiBr-H_2O. The system is analyzed in steady state with the commercial software Engineering Equator Solver (EES).

Efficient adaptive retrieval and mining in large multimedia databases

DEFF Research Database (Denmark)

Assent, Ira

2009-01-01

for a variety of features such as color, shape or texture. Time series data is prevalent for sensor measurements, stock data, and may even be applied to shapes and other features as well. For these data types, effective adaptable similarity 3 models are usually computationally far too complex for usage in large...

Efficient Cross-Device Query Processing

NARCIS (Netherlands)

H. Pirk (Holger)

2012-01-01

htmlabstractThe increasing diversity of hardware within a single system promises large performance gains but also poses a challenge for data management systems. Strategies for the efficient use of hardware with large performance differences are still lacking. For example, existing research on GPU

An accurate and efficient method for large-scale SSR genotyping and applications.

Science.gov (United States)

Li, Lun; Fang, Zhiwei; Zhou, Junfei; Chen, Hong; Hu, Zhangfeng; Gao, Lifen; Chen, Lihong; Ren, Sheng; Ma, Hongyu; Lu, Long; Zhang, Weixiong; Peng, Hai

2017-06-02

Accurate and efficient genotyping of simple sequence repeats (SSRs) constitutes the basis of SSRs as an effective genetic marker with various applications. However, the existing methods for SSR genotyping suffer from low sensitivity, low accuracy, low efficiency and high cost. In order to fully exploit the potential of SSRs as genetic marker, we developed a novel method for SSR genotyping, named as AmpSeq-SSR, which combines multiplexing polymerase chain reaction (PCR), targeted deep sequencing and comprehensive analysis. AmpSeq-SSR is able to genotype potentially more than a million SSRs at once using the current sequencing techniques. In the current study, we simultaneously genotyped 3105 SSRs in eight rice varieties, which were further validated experimentally. The results showed that the accuracies of AmpSeq-SSR were nearly 100 and 94% with a single base resolution for homozygous and heterozygous samples, respectively. To demonstrate the power of AmpSeq-SSR, we adopted it in two applications. The first was to construct discriminative fingerprints of the rice varieties using 3105 SSRs, which offer much greater discriminative power than the 48 SSRs commonly used for rice. The second was to map Xa21, a gene that confers persistent resistance to rice bacterial blight. We demonstrated that genome-scale fingerprints of an organism can be efficiently constructed and candidate genes, such as Xa21 in rice, can be accurately and efficiently mapped using an innovative strategy consisting of multiplexing PCR, targeted sequencing and computational analysis. While the work we present focused on rice, AmpSeq-SSR can be readily extended to animals and micro-organisms. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

Energy Performance and CO2 Emissions of HVAC Systems in Commercial Buildings

Directory of Open Access Journals (Sweden)

Rafat Al-Waked

2017-10-01

Full Text Available Energy performance of buildings has attracted much attention among building physicists and engineers worldwide. The effects of building heating; ventilation; and air conditioning (HVAC systems’ design upgrade on the building energy performance are the focus of the current study. The adopted HVAC system consisted of chilled ceiling and chilled beam systems served by a centrifugal water chiller. An energy simulation study was undertaken in accordance with the national Australian built environment rating system-rules for collecting and using data. A three-dimensional simulation study was carried out utilizing the virtual environment-integrated environmental solutions software. Results from the current study have shown the importance of utilizing energy-efficient HVAC systems and HVAC strategies for achieving a high building energy star rating. Recommended strategies in order to achieve the nominated star rating; as predicted by the simulation analysis; were presented. Moreover; the effects of solar radiation inside the building atrium were significant; which cannot be overcome by simply installing a low shading coefficient glazing type at the atrium skylight. In addition to providing chilled ceiling technology; a high efficiency chiller and low energy lighting; it is recommended that the building be well tuned during the commissioning period. The current approach could be extended to accommodate higher energy ratings of commercial buildings at different locations worldwide.

Efficient stochastic approaches for sensitivity studies of an Eulerian large-scale air pollution model

Science.gov (United States)

Dimov, I.; Georgieva, R.; Todorov, V.; Ostromsky, Tz.

2017-10-01

Reliability of large-scale mathematical models is an important issue when such models are used to support decision makers. Sensitivity analysis of model outputs to variation or natural uncertainties of model inputs is crucial for improving the reliability of mathematical models. A comprehensive experimental study of Monte Carlo algorithms based on Sobol sequences for multidimensional numerical integration has been done. A comparison with Latin hypercube sampling and a particular quasi-Monte Carlo lattice rule based on generalized Fibonacci numbers has been presented. The algorithms have been successfully applied to compute global Sobol sensitivity measures corresponding to the influence of several input parameters (six chemical reactions rates and four different groups of pollutants) on the concentrations of important air pollutants. The concentration values have been generated by the Unified Danish Eulerian Model. The sensitivity study has been done for the areas of several European cities with different geographical locations. The numerical tests show that the stochastic algorithms under consideration are efficient for multidimensional integration and especially for computing small by value sensitivity indices. It is a crucial element since even small indices may be important to be estimated in order to achieve a more accurate distribution of inputs influence and a more reliable interpretation of the mathematical model results.

A measurement of the efficiency for the detection of neutrons in the momentum range 200 to 3200 MeV/c, in large volume liquid scintillation counters

International Nuclear Information System (INIS)

Brown, R.M.; Clark, A.G.; Duke, P.J.

1976-04-01

A description is given of a system of 194 large volume liquid scintillation counters designed to detect neutrons in an experiment on the reaction π - p → π 0 n in the resonance region. The detection efficiency of the system has been determined, as a function of neutron momentum, in three separate measurements, covering the range 200 to 3200 MeV/c. Below 400 MeV/c the efficiency shows the expected momentum dependence near threshold, rising to a maximum of 50% near 300 MeV/c and then falling to 43% near 400 MeV/c. In the region 400 to 700 MeV/c the efficiency rises to 47% near 600 MeV/c and falls again to 43%, an effect not seen before; the efficiency was expected to be almost momentum independent in this region. Above the threshold for inelastic processes in nucleon-nucleon collision (approximately 800 MeV/c) the efficiency rises significantly reaching a maximum value of 65% above 1700 MeV/c. (author)

Metrology measurements for large-aperture VPH gratings

Science.gov (United States)

Zheng, Jessica R.; Gers, Luke; Heijmans, Jeroen

2013-09-01

The High Efficiency and Resolution Multi Element Spectrograph (HERMES) for the Australian Astronomical Observatory (AAO) uses four large aperture, high angle of incidence volume phase holographic gratings (VPHG) for high resolution `Galactic archaeology' spectroscopy. The large clear aperture, the high diffraction efficiency, the line frequency homogeneity, and mosaic alignment made manufacturing and testing challenging. We developed new metrology systems at the AAO to verify the performance of these VPH gratings. The measured diffraction efficiencies and line frequency of the VPH gratings received so far meet the vendor's provided data. The wavefront quality for the Blue VPH grating is good but the Green and Red VPH gratings need to be post polishing.

Electrical efficiency and renewable energy - Economical alternatives to large-scale power generation; Stromeffizienz und erneuerbare Energien - Wirtschaftliche alternative zu Grosskraftwerken

Energy Technology Data Exchange (ETDEWEB)

Oettli, B.; Hammer, S.; Moret, F.; Iten, R. [Infras, Zuerich (Switzerland); Nordmann, T. [TNC Consulting AG, Erlenbach (Switzerland)

2010-05-15

This final report for WWF Switzerland, Greenpeace Switzerland, the Swiss Energy Foundation SES, Pro Natura and the Swiss Cantons of Basel City and Geneva takes a look at the energy-relevant effects of the propositions made by Swiss electricity utilities for large-scale power generation. These proposals are compared with a strategy that proposes investments in energy-efficiency and the use of renewable sources of energy. The effects of both scenarios on the environment and the risks involved are discussed, as are the investments involved. The associated effects on the Swiss national economy are also discussed. For the efficiency and renewables scenario, two implementation variants are discussed: Inland investments and production are examined as are foreign production options and/or import from foreign countries. The methods used in the study are introduced and discussed. Investment and cost considerations, earnings and effects on employment are also reviewed. The report is completed with an extensive appendix which, amongst other things, includes potential reviews, cost estimates and a discussion on 'smart grids'

The Benefit of Variable-Speed Turbine Operation for Low Temperature Thermal Energy Power Recovery

OpenAIRE

Brasz, Joost J.

2014-01-01

This paper analyzes, given the large variation in turbine discharge pressure with changing ambient temperatures, whether variable-speed radial-inflow turbine operation has a similar benefit for Organic Rankine Cycle (ORC) power recovery systems as variable-speed centrifugal compression has for chiller applications. The benefit of variable-speed centrifugal compression over fixed-speed operation is a reduction in annual electricity consumption of almost 40 %. Air-conditioning systems are by ne...

Efficient large-scale graph data optimization for intelligent video surveillance

Science.gov (United States)

Shang, Quanhong; Zhang, Shujun; Wang, Yanbo; Sun, Chen; Wang, Zepeng; Zhang, Luming

2017-08-01

Society is rapidly accepting the use of a wide variety of cameras Location and applications: site traffic monitoring, parking Lot surveillance, car and smart space. These ones here the camera provides data every day in an analysis Effective way. Recent advances in sensor technology Manufacturing, communications and computing are stimulating.The development of new applications that can change the traditional Vision system incorporating universal smart camera network. This Analysis of visual cues in multi camera networks makes wide Applications ranging from smart home and office automation to large area surveillance and traffic surveillance. In addition, dense Camera networks, most of which have large overlapping areas of cameras. In the view of good research, we focus on sparse camera networks. One Sparse camera network using large area surveillance. As few cameras as possible, most cameras do not overlap Each other’s field of vision. This task is challenging Lack of knowledge of topology Network, the specific changes in appearance and movement Track different opinions of the target, as well as difficulties Understanding complex events in a network. In this review in this paper, we present a comprehensive survey of recent studies Results to solve the problem of topology learning, Object appearance modeling and global activity understanding sparse camera network. In addition, some of the current open Research issues are discussed.

RAM-efficient external memory sorting

DEFF Research Database (Denmark)

Arge, Lars; Thorup, Mikkel

2013-01-01

In recent years a large number of problems have been considered in external memory models of computation, where the complexity measure is the number of blocks of data that are moved between slow external memory and fast internal memory (also called I/Os). In practice, however, internal memory time...... often dominates the total running time once I/O-efficiency has been obtained. In this paper we study algorithms for fundamental problems that are simultaneously I/O-efficient and internal memory efficient in the RAM model of computation....

Review of energy-efficient train control and timetabling

NARCIS (Netherlands)

Scheepmaker, G.M.; Goverde, R.M.P.; Kroon, LG

2016-01-01

The energy consumption of trains is highly efficient due to the low friction between steel wheels and rails, although the efficiency is also influenced largely by the driving strategy applied and the scheduled running times in the timetable. Optimal energy-efficient driving strategies can reduce

Direct Digital Control Study.

Science.gov (United States)

1985-02-01

Deck - Cold Deck Reset Reheat Coil Reset Steam Boiler Optimization [lot Water Outside Air Reset Chiller Optimization Chiller Water Temperature Reset...with programming techniques for each type of installed DDC in order to effect changes in operating setpoints and application programs. *Communication...can be changed without recailbration of instrumentation devices. Changes to the application software, operating setpoints and parameters require the

Combined solar collector and energy storage system

Science.gov (United States)

Jensen, R. N. (Inventor)

1980-01-01

A combined solar energy collector, fluid chiller and energy storage system is disclosed. A movable interior insulated panel in a storage tank is positionable flush against the storage tank wall to insulate the tank for energy storage. The movable interior insulated panel is alternately positionable to form a solar collector or fluid chiller through which the fluid flows by natural circulation.

SA-SSR: a suffix array-based algorithm for exhaustive and efficient SSR discovery in large genetic sequences.

Science.gov (United States)

Pickett, B D; Karlinsey, S M; Penrod, C E; Cormier, M J; Ebbert, M T W; Shiozawa, D K; Whipple, C J; Ridge, P G

2016-09-01

Simple Sequence Repeats (SSRs) are used to address a variety of research questions in a variety of fields (e.g. population genetics, phylogenetics, forensics, etc.), due to their high mutability within and between species. Here, we present an innovative algorithm, SA-SSR, based on suffix and longest common prefix arrays for efficiently detecting SSRs in large sets of sequences. Existing SSR detection applications are hampered by one or more limitations (i.e. speed, accuracy, ease-of-use, etc.). Our algorithm addresses these challenges while being the most comprehensive and correct SSR detection software available. SA-SSR is 100% accurate and detected >1000 more SSRs than the second best algorithm, while offering greater control to the user than any existing software. SA-SSR is freely available at http://github.com/ridgelab/SA-SSR CONTACT: perry.ridge@byu.edu Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press.

Energy Conservation: Heating Navy Hangars

Science.gov (United States)

1984-07-01

temperature, IF Tf Inside air temperature 1 foot above the floor, OF T. Inside design temperature, IF To Hot water temperature setpoint , OF TON Chiller ...systems capable of optimizing energy usage base-wide. An add-on to an existing large scale EMCS is probably the first preference, followed by single...the building comfort conditions are met during hours of building occupancy. 2. Optimized Start/Stop turns on equipment at the latest possible time and

Adding large EM stack support

KAUST Repository

Holst, Glendon

2016-12-01

Serial section electron microscopy (SSEM) image stacks generated using high throughput microscopy techniques are an integral tool for investigating brain connectivity and cell morphology. FIB or 3View scanning electron microscopes easily generate gigabytes of data. In order to produce analyzable 3D dataset from the imaged volumes, efficient and reliable image segmentation is crucial. Classical manual approaches to segmentation are time consuming and labour intensive. Semiautomatic seeded watershed segmentation algorithms, such as those implemented by ilastik image processing software, are a very powerful alternative, substantially speeding up segmentation times. We have used ilastik effectively for small EM stacks – on a laptop, no less; however, ilastik was unable to carve the large EM stacks we needed to segment because its memory requirements grew too large – even for the biggest workstations we had available. For this reason, we refactored the carving module of ilastik to scale it up to large EM stacks on large workstations, and tested its efficiency. We modified the carving module, building on existing blockwise processing functionality to process data in manageable chunks that can fit within RAM (main memory). We review this refactoring work, highlighting the software architecture, design choices, modifications, and issues encountered.

Experiments of cooling photovoltaic panel by desorption process; Dacchaku hanno wo riyoshita taiyoko hatsuden panel no ondo josho yokusei jikken

Energy Technology Data Exchange (ETDEWEB)

Akisawa, A; Inoue, S; Kashiwagi, T [Tokyo University of Agriculture and Technology, Tokyo (Japan)

1997-11-25

It is important to cool a photovoltaic (PV) panel, because increased panel temperature is accompanied by decreased power generation efficiency. The authors have proposed a PV power generation system combined with an adsorption chiller driven by low-temperature heat, and simulated temperature changes during the desorption cycle, where the chiller utilizes endothermic reactions of an adsorbent during the desorption cycle. Described herein are results of the tests carried out to validate possibility of controlling panel temperature increase. The system consists of the PV panel with which a bed packed with an adsorbent is monolithically combined, condenser and evaporator. It generates power during the daytime by sunbeams, and provides low-temperature heat during the nighttime by the evaporator. In particular, ice can be produced when methanol and activated coal are used as the adsorbate and adsorbent. It has an advantage of effective utilization of energy as the heat source, which has been merely dissipated by the conventional system in the air. Such a system is expected to be useful for promoting effective utilization of solar energy and for peak power shaving in summer. The initial targets are achieved by the tests. 4 refs., 10 figs.

Water, a Refrigerant (L`eau, un Frigorigène)

DEFF Research Database (Denmark)

Paul, Joachim

2003-01-01

In the light of the ongoing discussions about the availability and the future of synthetic or natural refrigerants "water" is the most attractive fluid for chillers and icemakers because of the low energy demand, the intrinsic safety and the low costs both for the fluid itself and for the install......In the light of the ongoing discussions about the availability and the future of synthetic or natural refrigerants "water" is the most attractive fluid for chillers and icemakers because of the low energy demand, the intrinsic safety and the low costs both for the fluid itself...... since many years any refrigerant with OPD and GWP, Denmark has put up a law in 2001 which includes hefty taxes on HFC. This tax is added to the price of refrigerants and lies between 17 and 44 EURO/kg for the common fluids. The goal of taxation is clear: To make GWP refrigerants unattractive because...... of their price. In conjunction with tax comes a phase-out scenario which shall be effective from 2006. The options for "natural" refrigerants without ODP and GWP are limited to five fluids which are ammonia (toxic), carbon dioxide (very high pressures), hydrocarbons (flammable), air (relatively low efficiencies...

Efficient Feature-Driven Visualization of Large-Scale Scientific Data

Energy Technology Data Exchange (ETDEWEB)

Lu, Aidong

2012-12-12

Very large, complex scientific data acquired in many research areas creates critical challenges for scientists to understand, analyze, and organize their data. The objective of this project is to expand the feature extraction and analysis capabilities to develop powerful and accurate visualization tools that can assist domain scientists with their requirements in multiple phases of scientific discovery. We have recently developed several feature-driven visualization methods for extracting different data characteristics of volumetric datasets. Our results verify the hypothesis in the proposal and will be used to develop additional prototype systems.

The benefits of energy efficiency - why wait?

NARCIS (Netherlands)

Blok, K.; Breevoort, P. van

2012-01-01

Improving energy efficiency globally leads to many benefits. First and foremost, improved energy efficiency of equipment, buildings, vehicles and industrial processes will lead to a reduction of the use of electricity, heat and fuels. This will save large amounts of money. Moreover,

Local actions to reduce greenhouse gas emissions in the context of national action plans

International Nuclear Information System (INIS)

Harvey, L.D.D.

1995-01-01

Municipalities can play a number of important roles to complement national actions to limit greenhouse gas emissions: (i) by facilitating comprehensive, city-wide building retrofit activities; (ii) by facilitating the development and/or expansion of community integrated energy systems involving district heating, district cooling, and cogeneration of electricity; and (iii) by promoting urban intensification to reduce the need to use the private automobile. Innovative institutional and financial mechanism are needed to overcome some of the persistent barriers to more efficient energy use in buildings and a number of concepts, which are currently being considered by the City of Toronto as part of its programme to reduce CO 2 emissions by 20% from the 1988 level by 2005, are discussed here. These concepts involve using public securitization funds to leverage private sector funds for energy efficiency retrofits and a number of measures to reduce financing and retrofit transaction costs. Even where surplus electricity generating capacity exists at the regional scale, reduced electricity demand can still result in avoided utility system costs if transmission bottlenecks and future transmission and transformer upgrade costs are reduced. Finally, given the need to replace or modify many of the existing commercial chillers due to the phase out of CFC's, a window of opportunity exists during the next few years to provide alternative, chlorocarbon-free district cooling systems based on absorption chillers using waste heat from electricity generation, with significant (30-65%) CO 2 emission savings. (au)

Energy and Process Assessment Protocol for Industrial Buildings

Science.gov (United States)

2007-05-01

condenser surfaces of fouling 6.31 Raise evaporator or lower condenser water temperature 6.2 Optimize chiller sequencing 6.33 Use two-speed or...F increase in CHW supply setpoint the chiller compression motor load will DECREASE 1.5 percent. This is a zero cost ECO. 3.5 Decrease Conden. CTW...energy assessments, universities conducting energy assessment, and Energy Service Performance Contractors) perform Industrial and Energy Optimization

An Efficient and Reliable Statistical Method for Estimating Functional Connectivity in Large Scale Brain Networks Using Partial Correlation.

Science.gov (United States)

Wang, Yikai; Kang, Jian; Kemmer, Phebe B; Guo, Ying

2016-01-01

Currently, network-oriented analysis of fMRI data has become an important tool for understanding brain organization and brain networks. Among the range of network modeling methods, partial correlation has shown great promises in accurately detecting true brain network connections. However, the application of partial correlation in investigating brain connectivity, especially in large-scale brain networks, has been limited so far due to the technical challenges in its estimation. In this paper, we propose an efficient and reliable statistical method for estimating partial correlation in large-scale brain network modeling. Our method derives partial correlation based on the precision matrix estimated via Constrained L1-minimization Approach (CLIME), which is a recently developed statistical method that is more efficient and demonstrates better performance than the existing methods. To help select an appropriate tuning parameter for sparsity control in the network estimation, we propose a new Dens-based selection method that provides a more informative and flexible tool to allow the users to select the tuning parameter based on the desired sparsity level. Another appealing feature of the Dens-based method is that it is much faster than the existing methods, which provides an important advantage in neuroimaging applications. Simulation studies show that the Dens-based method demonstrates comparable or better performance with respect to the existing methods in network estimation. We applied the proposed partial correlation method to investigate resting state functional connectivity using rs-fMRI data from the Philadelphia Neurodevelopmental Cohort (PNC) study. Our results show that partial correlation analysis removed considerable between-module marginal connections identified by full correlation analysis, suggesting these connections were likely caused by global effects or common connection to other nodes. Based on partial correlation, we find that the most significant

Representing Large Virtual Worlds

NARCIS (Netherlands)

Kol, T.R.

2018-01-01

The ubiquity of large virtual worlds and their growing complexity in computer graphics require efficient representations. This means that we need smart solutions for the underlying storage of these complex environments, but also for their visualization. How the virtual world is best stored and how

Exergetic Analysis of a Novel Solar Cooling System for Combined Cycle Power Plants

Directory of Open Access Journals (Sweden)

Francesco Calise

2016-09-01

Full Text Available This paper presents a detailed exergetic analysis of a novel high-temperature Solar Assisted Combined Cycle (SACC power plant. The system includes a solar field consisting of innovative high-temperature flat plate evacuated solar thermal collectors, a double stage LiBr-H2O absorption chiller, pumps, heat exchangers, storage tanks, mixers, diverters, controllers and a simple single-pressure Combined Cycle (CC power plant. Here, a high temperature solar cooling system is coupled with a conventional combined cycle, in order to pre-cool gas turbine inlet air in order to enhance system efficiency and electrical capacity. In this paper, the system is analyzed from an exergetic point of view, on the basis of an energy-economic model presented in a recent work, where the obtained main results show that SACC exhibits a higher electrical production and efficiency with respect to the conventional CC. The system performance is evaluated by a dynamic simulation, where detailed simulation models are implemented for all the components included in the system. In addition, for all the components and for the system as whole, energy and exergy balances are implemented in order to calculate the magnitude of the irreversibilities within the system. In fact, exergy analysis is used in order to assess: exergy destructions and exergetic efficiencies. Such parameters are used in order to evaluate the magnitude of the irreversibilities in the system and to identify the sources of such irreversibilities. Exergetic efficiencies and exergy destructions are dynamically calculated for the 1-year operation of the system. Similarly, exergetic results are also integrated on weekly and yearly bases in order to evaluate the corresponding irreversibilities. The results showed that the components of the Joule cycle (combustor, turbine and compressor are the major sources of irreversibilities. System overall exergetic efficiency was around 48%. Average weekly solar collector

An Efficient Method to Evaluate Intermolecular Interaction Energies in Large Systems Using Overlapping Multicenter ONIOM and the Fragment Molecular Orbital Method

Science.gov (United States)

Asada, Naoya; Fedorov, Dmitri G.; Kitaura, Kazuo; Nakanishi, Isao; Merz, Kenneth M.

2012-01-01

We propose an approach based on the overlapping multicenter ONIOM to evaluate intermolecular interaction energies in large systems and demonstrate its accuracy on several representative systems in the complete basis set limit at the MP2 and CCSD(T) level of theory. In the application to the intermolecular interaction energy between insulin dimer and 4′-hydroxyacetanilide at the MP2/CBS level, we use the fragment molecular orbital method for the calculation of the entire complex assigned to the lowest layer in three-layer ONIOM. The developed method is shown to be efficient and accurate in the evaluation of the protein-ligand interaction energies. PMID:23050059

Common challenge in resource efficiency improvement

International Nuclear Information System (INIS)

La Motta, Sergio; Peronaci, Marcello

2015-01-01

Energy efficiency and technology improvements on their own will not achieve the Low Carbon Societies (LCS) goals. Thus, resource efficiency and a circular economy are keys to a low carbon society. Resource efficiency improvement potential has been analysed from the industrial and territorial management perspectives. Exploring synergies between LCS and the larger area of sustainable development and green economy, highlighting co-benefits and trade-offs, is of utmost importance to pave the way to a more equitable and largely participated low carbon transition.

Efficient Large-Scale 2D Culture System for Human Induced Pluripotent Stem Cells and Differentiated Cardiomyocytes

Directory of Open Access Journals (Sweden)

Shugo Tohyama

2017-11-01

Full Text Available Cardiac regenerative therapies utilizing human induced pluripotent stem cells (hiPSCs are hampered by ineffective large-scale culture. hiPSCs were cultured in multilayer culture plates (CPs with active gas ventilation (AGV, resulting in stable proliferation and pluripotency. Seeding of 1 × 106 hiPSCs per layer yielded 7.2 × 108 hiPSCs in 4-layer CPs and 1.7 × 109 hiPSCs in 10-layer CPs with pluripotency. hiPSCs were sequentially differentiated into cardiomyocytes (CMs in a two-dimensional (2D differentiation protocol. The efficiency of cardiac differentiation using 10-layer CPs with AGV was 66%–87%. Approximately 6.2–7.0 × 108 cells (4-layer and 1.5–2.8 × 109 cells (10-layer were obtained with AGV. After metabolic purification with glucose- and glutamine-depleted and lactate-supplemented media, a massive amount of purified CMs was prepared. Here, we present a scalable 2D culture system using multilayer CPs with AGV for hiPSC-derived CMs, which will facilitate clinical applications for severe heart failure in the near future.

Benchmarking urban energy efficiency in the UK

International Nuclear Information System (INIS)

Keirstead, James

2013-01-01

This study asks what is the ‘best’ way to measure urban energy efficiency. There has been recent interest in identifying efficient cities so that best practices can be shared, a process known as benchmarking. Previous studies have used relatively simple metrics that provide limited insight on the complexity of urban energy efficiency and arguably fail to provide a ‘fair’ measure of urban performance. Using a data set of 198 urban UK local administrative units, three methods are compared: ratio measures, regression residuals, and data envelopment analysis. The results show that each method has its own strengths and weaknesses regarding the ease of interpretation, ability to identify outliers and provide consistent rankings. Efficient areas are diverse but are notably found in low income areas of large conurbations such as London, whereas industrial areas are consistently ranked as inefficient. The results highlight the shortcomings of the underlying production-based energy accounts. Ideally urban energy efficiency benchmarks would be built on consumption-based accounts, but interim recommendations are made regarding the use of efficiency measures that improve upon current practice and facilitate wider conversations about what it means for a specific city to be energy-efficient within an interconnected economy. - Highlights: • Benchmarking is a potentially valuable method for improving urban energy performance. • Three different measures of urban energy efficiency are presented for UK cities. • Most efficient areas are diverse but include low-income areas of large conurbations. • Least efficient areas perform industrial activities of national importance. • Improve current practice with grouped per capita metrics or regression residuals

How to harvest efficient laser from solar light

Science.gov (United States)

Zhao, Changming; Guan, Zhe; Zhang, Haiyang

2018-02-01

Solar Pumped Solid State Lasers (SPSSL) is a kind of solid state lasers that can transform solar light into laser directly, with the advantages of least energy transform procedure, higher energy transform efficiency, simpler structure, higher reliability, and longer lifetime, which is suitable for use in unmanned space system, for solar light is the only form of energy source in space. In order to increase the output power and improve the efficiency of SPSSL, we conducted intensive studies on the suitable laser material selection for solar pump, high efficiency/large aperture focusing optical system, the optimization of concave cavity as the second focusing system, laser material bonding and surface processing. Using bonded and grooved Nd:YAG rod as laser material, large aperture Fresnel lens as the first stage focusing element, concave cavity as the second stage focusing element, we finally got 32.1W/m2 collection efficiency, which is the highest collection efficiency in the world up to now.

Reducing a solar-assisted air-conditioning system’s energy consumption by applying real-time occupancy sensors and chilled water storage tanks throughout the summer: A case study

International Nuclear Information System (INIS)

Rosiek, S.; Batlles, F.J.

2013-01-01

Highlights: • We present an innovative occupancy and chilled water storage-based operation mode. • This mode was implemented to the solar-assisted air-conditioning system. • It permits to save 42% of total electrical energy during one cooling period. • It allows storing the excess cooling capacity of the absorption chiller. • It prevents the sudden start/stop (on/off cycles) of the absorption chiller. - Abstract: This study describes an innovative occupancy and chilled-water storage-based operation sequence implemented in a solar-assisted air-conditioning system. The core purpose of this solar-assisted air-conditioning system is to handle the cooling and heating load of the Solar Energy Research Centre (CIESOL), thus minimising its environmental impact. In this study, the cooling mode was investigated with special attention focused on the chilled-water storage circuit. The critical concern is that the solar-assisted air-conditioning system should always operate considering the actual load conditions, not using an abstract maximum load that is predetermined during the system’s design process, which can lead to energy waste during periods of low occupancy. Thus, the fundamental problem is to identify the optimum operation sequence for the solar-assisted air-conditioning system that provides the best energy performance. The significance of this work lies in the demonstration of a new operation strategy that utilises real-time occupancy monitoring and chilled-water storage tanks to improve the efficiency of solar-assisted air-conditioning systems, thereby reducing their electricity consumption. Adopting this strategy resulted in a large energy-saving potential. The results demonstrate that during one cooling period, it is possible to conserve approximately 42% of the total electrical energy consumed by the system prior to the adoption of this operation strategy

BESST--efficient scaffolding of large fragmented assemblies.

Science.gov (United States)

Sahlin, Kristoffer; Vezzi, Francesco; Nystedt, Björn; Lundeberg, Joakim; Arvestad, Lars

2014-08-15

The use of short reads from High Throughput Sequencing (HTS) techniques is now commonplace in de novo assembly. Yet, obtaining contiguous assemblies from short reads is challenging, thus making scaffolding an important step in the assembly pipeline. Different algorithms have been proposed but many of them use the number of read pairs supporting a linking of two contigs as an indicator of reliability. This reasoning is intuitive, but fails to account for variation in link count due to contig features.We have also noted that published scaffolders are only evaluated on small datasets using output from only one assembler. Two issues arise from this. Firstly, some of the available tools are not well suited for complex genomes. Secondly, these evaluations provide little support for inferring a software's general performance. We propose a new algorithm, implemented in a tool called BESST, which can scaffold genomes of all sizes and complexities and was used to scaffold the genome of P. abies (20 Gbp). We performed a comprehensive comparison of BESST against the most popular stand-alone scaffolders on a large variety of datasets. Our results confirm that some of the popular scaffolders are not practical to run on complex datasets. Furthermore, no single stand-alone scaffolder outperforms the others on all datasets. However, BESST fares favorably to the other tested scaffolders on GAGE datasets and, moreover, outperforms the other methods when library insert size distribution is wide. We conclude from our results that information sources other than the quantity of links, as is commonly used, can provide useful information about genome structure when scaffolding.

Investigation of the radiative efficiency and threshold in InGaN laser diodes under the influence of efficiency droop

International Nuclear Information System (INIS)

Ryu, Han-Youl

2012-01-01

Based on the rate equation model of semiconductor lasers, the radiative efficiency and threshold current density of InGaN-based blue laser diodes (LDs) are theoretically investigated, including the effect of efficiency droop in the InGaN quantum wells. The peak point of the radiative efficiency versus current density relation is used as the parameter of the rate equation analysis. The threshold current density of InGaN blue LDs is found to depend strongly on the maximum radiative efficiency at low current density, implying that improving the maximum efficiency is important to maintain a high radiative efficiency at a large current density and to achieve a low-threshold lasing action under the influence of efficiency droop.

Efficient statistically accurate algorithms for the Fokker-Planck equation in large dimensions

Science.gov (United States)

Chen, Nan; Majda, Andrew J.

2018-02-01

Solving the Fokker-Planck equation for high-dimensional complex turbulent dynamical systems is an important and practical issue. However, most traditional methods suffer from the curse of dimensionality and have difficulties in capturing the fat tailed highly intermittent probability density functions (PDFs) of complex systems in turbulence, neuroscience and excitable media. In this article, efficient statistically accurate algorithms are developed for solving both the transient and the equilibrium solutions of Fokker-Planck equations associated with high-dimensional nonlinear turbulent dynamical systems with conditional Gaussian structures. The algorithms involve a hybrid strategy that requires only a small number of ensembles. Here, a conditional Gaussian mixture in a high-dimensional subspace via an extremely efficient parametric method is combined with a judicious non-parametric Gaussian kernel density estimation in the remaining low-dimensional subspace. Particularly, the parametric method provides closed analytical formulae for determining the conditional Gaussian distributions in the high-dimensional subspace and is therefore computationally efficient and accurate. The full non-Gaussian PDF of the system is then given by a Gaussian mixture. Different from traditional particle methods, each conditional Gaussian distribution here covers a significant portion of the high-dimensional PDF. Therefore a small number of ensembles is sufficient to recover the full PDF, which overcomes the curse of dimensionality. Notably, the mixture distribution has significant skill in capturing the transient behavior with fat tails of the high-dimensional non-Gaussian PDFs, and this facilitates the algorithms in accurately describing the intermittency and extreme events in complex turbulent systems. It is shown in a stringent set of test problems that the method only requires an order of O (100) ensembles to successfully recover the highly non-Gaussian transient PDFs in up to 6

The Efficiency and Productivity Analysis of Large Logistics Providers Services in Korea

Directory of Open Access Journals (Sweden)

Hong Gyun Park

2015-12-01

Full Text Available In the fierce competition at the global logistics markets, Korean logistics providers were deemed more vulnerable than global logistics providers in terms of the quality and price competitiveness. To strengthen their competitiveness, logistics providers in Korea have focused on delivering integrated logistics services. In this regard, the Korean government has enacted the “Integrated Logistics Industry Certification Act” in 2006 to assist integrated logistics providers to offer logistics services based on their specialization and differentiation. It has been several years since the system was implemented, and the evaluation of the system implementation was necessary. Hence, in our study, we attempt to examine the efficiency and productivity of fourteen certified Korean logistics providers employing the DEA (Data Envelopment Analysis method with a five-year panel data since the inception of the Act. Through our static and dynamic analyses, We found that Pantos Logistics and HYUNDAI Glovis are running their businesses at the highest level of efficiency and Hanjin Transportation was the most stable company in their logistics operation.

Air purification in industrial plants producing automotive rubber components in terms of energy efficiency

Directory of Open Access Journals (Sweden)

Grzebielec Andrzej

2017-04-01

Full Text Available In automotive industry plants, which use injection molding machines for rubber processing, tar contaminates air to such an extent that air fails to enter standard heat recovery systems. Accumulated tar clogs ventilation heat recovery exchangers in just a few days. In the plant in which the research was conducted, tar contamination causes blockage of ventilation ducts. The effect of this phenomenon was that every half year channels had to be replaced with new ones, since the economic analysis has shown that cleaning them is not cost-efficient. Air temperature inside such plants is often, even in winter, higher than 30°C. The air, without any means of heat recovery, is discharged outside the buildings. The analyzed plant uses three types of media for production: hot water, cold water at 14°C (produced in a water chiller, and compressed air, generated in a unit with a rated power consumption of 180 kW. The aim of the study is to determine the energy efficiency improvement of this type of manufacturing plant. The main problem to solve is to provide an air purification process so that air can be used in heat recovery devices. The next problem to solve is to recover heat at such a temperature level that it would be possible to produce cold for technological purposes without air purification. Experimental studies have shown that air purification is feasible. By using one microjet head, a total of 75% of tar particles was removed from the air; by using 4 heads, a purification efficiency of 93% was obtained. This method of air purification causes air temperature to decrease from 35°C to 20°C, which significantly reduces the potential for heat recovery. The next step of the research was designing a cassette-plate heat exchanger to exchange heat without air purification. The economic analysis of such a solution revealed that replacing the heat exchanger with a new one even once a year was not cost-efficient. Another issue examined in the context of

Energy Monitoring and Control Systems Operator Training - Recommended Qualifications, Staffing, Job Description, and Training Requirements for EMCS Operators.

Science.gov (United States)

1982-06-01

start/stop chiller optimization , and demand limiting were added. The system monitors a 7,000 ton chiller plant and controls 74 air handlers. The EMCS does...Modify analog limits. g. Adjust setpoints of selected controllers. h. Select manual or automatic control modes. i. Enable and disable individual points...or event schedules and controller setpoints ; make nonscheduled starts and stops of equipment or disable field panels when required for routine

Maximizing Efficiency in Two-step Solar-thermochemical Fuel Production

Energy Technology Data Exchange (ETDEWEB)

Ermanoski, I. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

2015-05-01

Widespread solar fuel production depends on its economic viability, largely driven by the solar-to-fuel conversion efficiency. In this paper, the material and energy requirements in two-step solar-thermochemical cycles are considered.The need for advanced redox active materials is demonstrated, by considering the oxide mass flow requirements at a large scale. Two approaches are also identified for maximizing the efficiency: optimizing reaction temperatures, and minimizing the pressure in the thermal reduction step by staged thermal reduction. The results show that each approach individually, and especially the two in conjunction, result in significant efficiency gains.

Trigeneration in waste to energy plants for expanding the efficiency; Kraft-Waerme-Kaelte-Kopplung bei Muellverbrennungsanlagen zur erweiterten Energieeffizienzsteigerung

Energy Technology Data Exchange (ETDEWEB)

Reil, Eberhard [Fernwaerme Wien GmbH, Wien (Austria)

2010-05-15

An impressive metamorphosis changed Waste to Energy plants from originally environmental risky plants to high sophisticated end of pipe technology sites to finally high efficient Energy production plants. Such described plants are situated in urban places to aware the connections into efficient power grids and district heating networks to provide the base load the whole year round. Nowadays the request for cooling is steady rising and again Waste to energy plants, connected to a district cooling network, takes over an important role for the supply. Such concepts are only marketable, if the required criteria's for efficiency are fulfilled. Such criteria's within Europe are the greenhouse gas emission factor and the primary energy factor. Both proof the efficiency of a system according to sustainability and environmental acceptance. Such criteria's are the result of the EU target to enhance the renewable within the energy supply while a more efficient use of site energy should take place. The Vienna Model was chosen as best practice sample. The district heating network is connected to all Waste to energy plants as well to the gas fired CHP plants in Vienna. The peak demand for the supply is realized by gas fired hot water boilers. In 2006 Fernwaerme Wien started to set up a district cooling network. The base load for the cooling derives from absorption chillers driven by heat from the waste to energy plants. According the EN standard 15316 part 4 and 5, method for calculation of system energy requirements and system efficiencies, the primary energy factor and CO2 factor has been defined for the Vienna model and as a consequence of that also for the waste to energy plant Pfaffenau. The average primary energy factor of the Vienna model calculated for the years 2006 to 2008 is 0,21 for the renewable part. According to the result the savings on primary energy have been 42 % and equates to 6,9 TWh/a. The reduc tion of the greenhouse gas emissions has been

Time-Efficient High-Resolution Large-Area Nano-Patterning of Silicon Dioxide

DEFF Research Database (Denmark)

Lin, Li; Ou, Yiyu; Aagesen, Martin

2017-01-01

A nano-patterning approach on silicon dioxide (SiO2) material, which could be used for the selective growth of III-V nanowires in photovoltaic applications, is demonstrated. In this process, a silicon (Si) stamp with nanopillar structures was first fabricated using electron-beam lithography (EBL....... In addition, high time efficiency can be realized by one-spot electron-beam exposure in the EBL process combined with NIL for mass production. Furthermore, the one-spot exposure enables the scalability of the nanostructures for different application requirements by tuning only the exposure dose. The size...

Efficient preparation of large-block-code ancilla states for fault-tolerant quantum computation

Science.gov (United States)

Zheng, Yi-Cong; Lai, Ching-Yi; Brun, Todd A.

2018-03-01

Fault-tolerant quantum computation (FTQC) schemes that use multiqubit large block codes can potentially reduce the resource overhead to a great extent. A major obstacle is the requirement for a large number of clean ancilla states of different types without correlated errors inside each block. These ancilla states are usually logical stabilizer states of the data-code blocks, which are generally difficult to prepare if the code size is large. Previously, we have proposed an ancilla distillation protocol for Calderbank-Shor-Steane (CSS) codes by classical error-correcting codes. It was assumed that the quantum gates in the distillation circuit were perfect; however, in reality, noisy quantum gates may introduce correlated errors that are not treatable by the protocol. In this paper, we show that additional postselection by another classical error-detecting code can be applied to remove almost all correlated errors. Consequently, the revised protocol is fully fault tolerant and capable of preparing a large set of stabilizer states sufficient for FTQC using large block codes. At the same time, the yield rate can be boosted from O (t-2) to O (1 ) in practice for an [[n ,k ,d =2 t +1

Energetic retrofitting of industrial heat supply systems. Possibilities of enhancing the efficiency and energy conservation at large combustion engineering plants; Energetische Modernisierung industrieller Waermeversorgungssysteme. Moeglichkeiten der Effizienzsteigerung und der Energieeinsparung an grossen feuerungstechnischen Anlagen

Energy Technology Data Exchange (ETDEWEB)

NONE

2011-12-15

In the contribution under consideration, the Deutsche Energie-Agentur GmbH (Berlin, Federal Republic of Germany) reports on an energetic modernization of industrial heat supply systems. Possibilities of an enhancement of the energetic efficiency and energy conservation at large combustion engineering plants are described. After an introduction to this theme, the author of this contribution provides an overview of the optimization of heat supply systems, and reports on the following aspects: Optimisation of the heat demand; energy efficient heat generation; heat recovery; energy efficient conversion technology and generation technology; associate partners for more energy efficiency in industry and commerce; best practice examples.

Analysis of thermal energy storage for a pharmaceutical company

Energy Technology Data Exchange (ETDEWEB)

Henze, Gregor P. [Colorado Univ., Boulder, CO (US). Dept. of Civil, Environmental and Architectural Engineering (CEAE); Biffar, Bernd; Wienecke, Marcus [Boehringer Ingelheim Pharma GmbH und Co. KG, Biberach (Germany); Becker, Martin P. [Biberach Univ. of Applied Sciences (Germany). Dept. of Architectural and Energy Engineering

2009-07-01

A pharmaceutical facility located in Southern Germany is experiencing a trend of growing cooling loads to be met by the chilled water plant composed of ten chillers of greatly varying cost effectiveness. With a capacity shortfall inevitable, the question arises whether to install an additional chiller or improve the utilization of the existing chillers, in particular those with low operating costs per unit cooling, through the addition of a chilled water thermal energy storage (TES) system. To provide decision support in this matter, an optimization environment was developed and validated that adopts mixed integer programming as the approach to optimizing the chiller dispatch for any load condition, while an overarching dynamic programming based optimization approach optimizes the charge/discharge strategy of the TES system. In this fashion, the chilled water plant optimization is decoupled but embedded in the TES control optimization. The approach was selected to allow for arbitrary constraints and optimization horizons, while ensuring a global optimum to the problem. The results show that a relatively small TES tank provides significant economic and operational benefits. Yet, in order to facilitate long-term supply security, a larger TES tank capacity was decided on and the TES system was constructed in 2008. (orig.)

Advanced Large Area Plastic Scintillator Project (ALPS): Final Report

International Nuclear Information System (INIS)

Jordan, David V.; Reeder, Paul L.; Todd, Lindsay C.; Warren, Glen A.; McCormick, Kathleen R.; Stephens, Daniel L.; Geelhood, Bruce D.; Alzheimer, James M.; Crowell, Shannon L.; Sliger, William A.

2008-01-01

The advanced Large-Area Plastic Scintillator (ALPS) Project at Pacific Northwest National Laboratory investigated possible technological avenues for substantially advancing the state-of-the-art in gamma-ray detection via large-area plastic scintillators. The three predominant themes of these investigations comprised the following: * Maximizing light collection efficiency from a single large-area sheet of plastic scintillator, and optimizing hardware event trigger definition to retain detection efficiency while exploiting the power of coincidence to suppress single-PMT 'dark current' background; * Utilizing anti-Compton vetoing and supplementary spectral information from a co-located secondary, or 'Back' detector, to both (1) minimize Compton background in the low-energy portion of the 'Front' scintillator's pulse-height spectrum, and (2) sharpen the statistical accuracy of the front detector's low-energy response prediction as implemented in suitable energy-windowing algorithms; and * Investigating alternative materials to enhance the intrinsic gamma-ray detection efficiency of plastic-based sensors

Real-time simulation of large-scale floods

Science.gov (United States)

Liu, Q.; Qin, Y.; Li, G. D.; Liu, Z.; Cheng, D. J.; Zhao, Y. H.

2016-08-01

According to the complex real-time water situation, the real-time simulation of large-scale floods is very important for flood prevention practice. Model robustness and running efficiency are two critical factors in successful real-time flood simulation. This paper proposed a robust, two-dimensional, shallow water model based on the unstructured Godunov- type finite volume method. A robust wet/dry front method is used to enhance the numerical stability. An adaptive method is proposed to improve the running efficiency. The proposed model is used for large-scale flood simulation on real topography. Results compared to those of MIKE21 show the strong performance of the proposed model.

Evaluating the potential of process sites for waste heat recovery

International Nuclear Information System (INIS)

Oluleye, Gbemi; Jobson, Megan; Smith, Robin; Perry, Simon J.

2016-01-01

Highlights: • Analysis considers the temperature and duties of the available waste heat. • Models for organic Rankine cycles, absorption heat pumps and chillers proposed. • Exploitation of waste heat from site processes and utility systems. • Concept of a site energy efficiency introduced. • Case study presented to illustrate application of the proposed methodology. - Abstract: As a result of depleting reserves of fossil fuels, conventional energy sources are becoming less available. In spite of this, energy is still being wasted, especially in the form of heat. The energy efficiency of process sites (defined as useful energy output per unit of energy input) may be increased through waste heat utilisation, thereby resulting in primary energy savings. In this work, waste heat is defined and a methodology developed to identify the potential for waste heat recovery in process sites; considering the temperature and quantity of waste heat sources from the site processes and the site utility system (including fired heaters and, the cogeneration, cooling and refrigeration systems). The concept of the energy efficiency of a site is introduced – the fraction of the energy inputs that is converted into useful energy (heat or power or cooling) to support the methodology. Furthermore, simplified mathematical models of waste heat recovery technologies using heat as primary energy source, including organic Rankine cycles (using both pure and mixed organics as working fluids), absorption chillers and absorption heat pumps are developed to support the methodology. These models are applied to assess the potential for recovery of useful energy from waste heat. The methodology is illustrated for an existing process site using a case study of a petroleum refinery. The energy efficiency of the site increases by 10% as a result of waste heat recovery. If there is an infinite demand for recovered energy (i.e. all the recoverable waste heat sources are exploited), the site

Techno-economic assessment for the integration into a multi-product plant based on cascade utilization of geothermal energy

International Nuclear Information System (INIS)

Rubio-Maya, Carlos; Pastor Martínez, Edgar; Romero, Carlos E.; Ambriz Díaz, Víctor M.; Pacheco-Ibarra, J. Jesús

2016-01-01

Highlights: • Cascade utilization of low- and mid-temperature geothermal energy is presented. • The system consists of three thermal levels producing power, ice and useful heat. • A techno-economic analysis is performed evaluating energy and economic benefits. • A simple optimization algorithm was developed to optimize system benefits. • Inconvenience of low thermal efficiency and high capital cost of ORC were overcome. - Abstract: The Organic Rankine Cycle (ORC) is a technology that has reached maturity in cogeneration or waste heat applications. However, due to low thermal efficiency and high capital cost of ORC machines, geothermal-based ORC applications represent only a small percent sharing of the geothermal power capacity worldwide. Several countries have reported a great potential of low- and mid-temperature geothermal energy, representing an opportunity to explore a more efficient ORC integration into non-conventional applications of geothermal energy. One alternative, resembling the polygeneration concept, is known as cascade utilization of geothermal energy, where different energy outputs or products can be obtained at the same time, while improving thermal and economic performance. In this paper, a techno-economic analysis for the selection of small capacity ORC machines and absorption chillers (for ice production), to be integrated into a polygeneration plant that makes use of geothermal energy in a cascade arrangement, is presented. A simple cascade system that consists of three sequential thermal levels, producing simultaneously power, ice and useful heat is proposed, considering typical temperatures of geothermal zones in Mexico. A simple optimization algorithm, based on energy and economic models, including binary variables and manufacturer’s data, was developed to evaluate and determine optimal ORC and absorption chiller units. Results show, firstly, that inconvenience of low thermal efficiency and high capital cost of ORC machines can

Energy Optimization Assessment at U.S. Army Installations: Fort Bliss, TX

Science.gov (United States)

2008-09-01

Log dampers, temperatures, actuator signals, and other parameters to identify problems. Adjust chiller and boiler setpoints and control curves...installation. The lowest setpoints were found in the Centennial Club, with 52 °F during unoccupied hours (morn- ing). The chillers ran pretty much fully loaded...ER D C/ CE R L TR -0 8 -1 5 Energy Optimization Assessment at U.S. Army Installations Fort Bliss, TX David M. Underwood, Alexander M

Energy Optimization Assessment at U.S. Army Installations: West Point Military Academy, NY

Science.gov (United States)

2008-09-01

chillers to work unnecessarily more than needed. Other buildings had setpoints at different areas above 55 °F. Many buildings are air-conditioned and... optimal . The cost of 12.5 cents/KWh makes it unlikely, especially where steam adsorption chillers exist. 11.8.2 Solution Use the existing steam...ER D C/ CE R L TR -0 8 -1 4 Energy Optimization Assessment at U.S. Army Installations West Point Military Academy, NY David M

An Efficient Format for Nearly Constant-Time Access to Arbitrary Time Intervals in Large Trace Files

Directory of Open Access Journals (Sweden)

Anthony Chan

2008-01-01

Full Text Available A powerful method to aid in understanding the performance of parallel applications uses log or trace files containing time-stamped events and states (pairs of events. These trace files can be very large, often hundreds or even thousands of megabytes. Because of the cost of accessing and displaying such files, other methods are often used that reduce the size of the tracefiles at the cost of sacrificing detail or other information. This paper describes a hierarchical trace file format that provides for display of an arbitrary time window in a time independent of the total size of the file and roughly proportional to the number of events within the time window. This format eliminates the need to sacrifice data to achieve a smaller trace file size (since storage is inexpensive, it is necessary only to make efficient use of bandwidth to that storage. The format can be used to organize a trace file or to create a separate file of annotations that may be used with conventional trace files. We present an analysis of the time to access all of the events relevant to an interval of time and we describe experiments demonstrating the performance of this file format.

Transport Coefficients from Large Deviation Functions

OpenAIRE

Gao, Chloe Ya; Limmer, David T.

2017-01-01

We describe a method for computing transport coefficients from the direct evaluation of large deviation functions. This method is general, relying on only equilibrium fluctuations, and is statistically efficient, employing trajectory based importance sampling. Equilibrium fluctuations of molecular currents are characterized by their large deviation functions, which are scaled cumulant generating functions analogous to the free energies. A diffusion Monte Carlo algorithm is used to evaluate th...

The plant efficiency of fusion power stations

International Nuclear Information System (INIS)

Darvas, J.; Foerster, S.

1976-01-01

Due to the circulating energy, lower efficiencies are to be expected with fusion power plants than with nuclear fission power plants. According to the systems analysis, the mirror machine is not very promising as a power plant. The plant efficiency of the laser fusion strongly depends on the laser efficiency about which one can only make speculative statements at present. The Tokamak requires a relatively low circulating energy and is certainly able to compete regarding efficiency as long as the consumption time can be kept large (> 100 sec) and the dead time between the power pulses small ( [de

Thermoeconomic and environmental analyses of a low water consumption combined steam power plant and refrigeration chillers – Part 1: Energy and economic modelling and analysis

International Nuclear Information System (INIS)

Ifaei, Pouya; Rashidi, Jouan; Yoo, ChangKyoo

2016-01-01

Highlights: • Proposing two energy systems by combining refrigeration chillers and power plants. • Model-based comparison of the systems through energy and economic standpoints. • Reducing total annual costs of the base system up to 4.7% by process integration. • Decreasing the water loss in wet cooling towers by up to 18% in the proposed system. • Suggesting a water-fuel economic management strategy based on parametric analysis. - Abstract: Two novel configurations are proposed to replace the conventional Rankine cycle based steam power plants (SPP) with natural draft wet cooling towers (NDWCT) as cooling units. Closed feedwater heater unit of the base SPP-NDWCT system is eliminated in order to combine a vapor compression refrigeration (VCR) and an absorption heat pump (ABHP) with the base SPP-NDWCT system. Both VCR-SPP-NDWCT and ABHP-SPP-NDWCT systems are integrated to decrease the NDWCT load which could result in water losses decrease. In part one of the presented two-part paper, model-based energy and economic analyses are performed to compare systems performance and applicability. The temperature difference at pinch point and temperature difference between the hot and cold sides of the heat exchangers which were used for systems integration in VCR-SPP-NDWCT, and the absorber pressure and temperature in ABHP-SPP-NDWCT system are studied using parametric analysis procedure. A water-fuel management strategy is also introduced for the ABHP-SPP-NDWCT system according to the influence of the absorber pressure changes on system water and fuel consumption. In part 2, environmental and thermoeconomic analyses are performed to complete a comprehensive study on designing steam power plants. The results of part 1 showed that water losses and total annual costs decreased by 1–18% and 0–4.7% for the ABHP-SPP-NDWCT system but increased by 11% and 60% for the VCR-SPP-NDWCT system, respectively.

Advanced Large Area Plastic Scintillator Project (ALPS): Final Report

Energy Technology Data Exchange (ETDEWEB)

Jordan, David V.; Reeder, Paul L.; Todd, Lindsay C.; Warren, Glen A.; McCormick, Kathleen R.; Stephens, Daniel L.; Geelhood, Bruce D.; Alzheimer, James M.; Crowell, Shannon L.; Sliger, William A.

2008-02-05

The advanced Large-Area Plastic Scintillator (ALPS) Project at Pacific Northwest National Laboratory investigated possible technological avenues for substantially advancing the state-of-the-art in gamma-ray detection via large-area plastic scintillators. The three predominant themes of these investigations comprised the following: * Maximizing light collection efficiency from a single large-area sheet of plastic scintillator, and optimizing hardware event trigger definition to retain detection efficiency while exploiting the power of coincidence to suppress single-PMT "dark current" background; * Utilizing anti-Compton vetoing and supplementary spectral information from a co-located secondary, or "Back" detector, to both (1) minimize Compton background in the low-energy portion of the "Front" scintillator's pulse-height spectrum, and (2) sharpen the statistical accuracy of the front detector's low-energy response prediction as impelmented in suitable energy-windowing algorithms; and * Investigating alternative materials to enhance the intrinsic gamma-ray detection efficiency of plastic-based sensors.

Efficiency and Loading Evaluation of High Efficiency Mist Eliminators (HEME) - 12003

Energy Technology Data Exchange (ETDEWEB)

Giffin, Paxton K.; Parsons, Michael S.; Waggoner, Charles A. [Institute for Clean Energy Technology, Mississippi State University, 205 Research Blvd Starkville, MS 39759 (United States)

2012-07-01

High efficiency mist eliminators (HEME) are filters primarily used to remove moisture and/or liquid aerosols from an air stream. HEME elements are designed to reduce aerosol and particulate load on primary High Efficiency Particulate Air (HEPA) filters and to have a liquid particle removal efficiency of approximately 99.5% for aerosols down to sub-micron size particulates. The investigation presented here evaluates the loading capacity of the element in the absence of a water spray cleaning system. The theory is that without the cleaning system, the HEME element will suffer rapid buildup of solid aerosols, greatly reducing the particle loading capacity. Evaluation consists of challenging the element with a waste surrogate dry aerosol and di-octyl phthalate (DOP) at varying intervals of differential pressure to examine the filtering efficiency of three different element designs at three different media velocities. Also, the elements are challenged with a liquid waste surrogate using Laskin nozzles and large dispersion nozzles. These tests allow the loading capacity of the unit to be determined and the effectiveness of washing down the interior of the elements to be evaluated. (authors)

High Quantum Efficiency OLED Lighting Systems

Energy Technology Data Exchange (ETDEWEB)

Shiang, Joseph [General Electric (GE) Global Research, Fairfield, CT (United States)

2011-09-30

The overall goal of the program was to apply improvements in light outcoupling technology to a practical large area plastic luminaire, and thus enable the product vision of an extremely thin form factor high efficiency large area light source. The target substrate was plastic and the baseline device was operating at 35 LPW at the start of the program. The target LPW of the program was a >2x improvement in the LPW efficacy and the overall amount of light to be delivered was relatively high 900 lumens. Despite the extremely difficult challenges associated with scaling up a wet solution process on plastic substrates, the program was able to make substantial progress. A small molecule wet solution process was successfully implemented on plastic substrates with almost no loss in efficiency in transitioning from the laboratory scale glass to large area plastic substrates. By transitioning to a small molecule based process, the LPW entitlement increased from 35 LPW to 60 LPW. A further 10% improvement in outcoupling efficiency was demonstrated via the use of a highly reflecting cathode, which reduced absorptive loss in the OLED device. The calculated potential improvement in some cases is even larger, ~30%, and thus there is considerable room for optimism in improving the net light coupling efficacy, provided absorptive loss mechanisms are eliminated. Further improvements are possible if scattering schemes such as the silver nanowire based hard coat structure are fully developed. The wet coating processes were successfully scaled to large area plastic substrate and resulted in the construction of a 900 lumens luminaire device.

DTU International Energy Report 2012: Energy efficiency improvements

DEFF Research Database (Denmark)

Increased energy efficiency can reduce global CO2 emissions over the period to 2050 with up to 25%. On the top of that large profits can be gained for very little investment. Energy efficiency improvements can save investment in new energy infrastructure, cut fuel costs, increase competitiveness...... and increase consumer welfare. Thus, it is natural for DTU International Energy Report 2012 to take up this issue and analyze the global, regional and national challenges in exploiting energy efficiency and promote research and development in energy efficiency....

Microbiological analysis of critical points in the chicken industry

Directory of Open Access Journals (Sweden)

Rogério Luis Cansian

2005-05-01

Full Text Available This work is focused on identifying microbial contamination in the scalding asepsis and cooling processes as well as in fresh sausages obtained. Salmonella was identified in two scald water samples but was absent in the water from chiller and in the final product, which might be explained in terms of chlorine addition and temperature reduction. The analysis revealed that MPN of Escherichia coli was in the range of O objetivo deste trabalho foi identificar a contaminação microbiana no processo de escaldagem, assepsia e resfriamento do frango (chiller, e em linguiças de frango produzidas a partir destes. As amostras foram coletadas em um frigorífico de aves, em sete datas e analisadas em triplicata. A presença de Salmonella foi detectada em duas amostras da água de escaldagem não estando mais presente na água do chiller e nem no produto final. Isto se deve à redução de temperatura da água e adição de cloro. O NMP de coliformes fecais variou entre < 1 a 11/ml na água de escaldagem e < 1 a 64/ml na água do chiller, que embora em padrões aceitáveis, mostram tendência de acréscimo no chiller, devido principalmente ao processo de evisceração. As contagens de Aeromonas variaram de 5 a 3,5x10¹UFC/ml na água de escaldagem e 9 a 3,7x10²UFC/ml na água do chiller. Este acréscimo se deve, provavelmente, por Aeromonas ser psicrófila e também devido a retirada das víceras. As análises de linguiça de frango mostraram acréscimo nas contagens de Aeromonas, apresentando até 2,5x10³UFC/g. Esta tendência de aumento de crescimento no produto final, aliado a capacidade de causar infecções de Aeromonas demonstram a necessidade de incluir a análise destas nas avaliações microbiológicas de alimentos.

Solar hybrid cooling system for high-tech offices in subtropical climate - Radiant cooling by absorption refrigeration and desiccant dehumidification

International Nuclear Information System (INIS)

Fong, K.F.; Chow, T.T.; Lee, C.K.; Lin, Z.; Chan, L.S.

2011-01-01

Highlights: → A solar hybrid cooling system is proposed for high-tech offices in subtropical climate. → An integration of radiant cooling, absorption refrigeration and desiccant dehumidification. → Year-round cooling and energy performances were evaluated through dynamic simulation. → Its annual primary energy consumption was lower than conventional system up to 36.5%. → The passive chilled beams were more energy-efficient than the active chilled beams. - Abstract: A solar hybrid cooling design is proposed for high cooling load demand in hot and humid climate. For the typical building cooling load, the system can handle the zone cooling load (mainly sensible) by radiant cooling with the chilled water from absorption refrigeration, while the ventilation load (largely latent) by desiccant dehumidification. This hybrid system utilizes solar energy for driving the absorption chiller and regenerating the desiccant wheel. Since a high chilled water temperature generated from the absorption chiller is not effective to handle the required latent load, desiccant dehumidification is therefore involved. It is an integration of radiant cooling, absorption refrigeration and desiccant dehumidification, which are powered up by solar energy. In this study, the application potential of the solar hybrid cooling system was evaluated for the high-tech offices in the subtropical climate through dynamic simulation. The high-tech offices are featured with relatively high internal sensible heat gains due to the intensive office electric equipment. The key performance indicators included the solar fraction and the primary energy consumption. Comparative study was also carried out for the solar hybrid cooling system using two common types of chilled ceilings, the passive chilled beams and active chilled beams. It was found that the solar hybrid cooling system was technically feasible for the applications of relatively higher cooling load demand. The annual primary energy

Room-Temperature and Solution-Processable Cu-Doped Nickel Oxide Nanoparticles for Efficient Hole-Transport Layers of Flexible Large-Area Perovskite Solar Cells.

Science.gov (United States)

He, Qiqi; Yao, Kai; Wang, Xiaofeng; Xia, Xuefeng; Leng, Shifeng; Li, Fan

2017-12-06

Flexible perovskite solar cells (PSCs) using plastic substrates have become one of the most attractive points in the field of thin-film solar cells. Low-temperature and solution-processable nanoparticles (NPs) enable the fabrication of semiconductor thin films in a simple and low-cost approach to function as charge-selective layers in flexible PSCs. Here, we synthesized phase-pure p-type Cu-doped NiO x NPs with good electrical properties, which can be processed to smooth, pinhole-free, and efficient hole transport layers (HTLs) with large-area uniformity over a wide range of film thickness using a room-temperature solution-processing technique. Such a high-quality inorganic HTL allows for the fabrication of flexible PSCs with an active area >1 cm 2 , which have a power conversion efficiency over 15.01% without hysteresis. Moreover, the Cu/NiO x NP-based flexible devices also demonstrate excellent air stability and mechanical stability compared to their counterpart fabricated on the pristine NiO x films. This work will contribute to the evolution of upscaling flexible PSCs with a simple fabrication process and high device performances.

An efficient algorithm for 3D space time kinetics simulations for large PHWRs

International Nuclear Information System (INIS)

Jain, Ishi; Fernando, M.P.S.; Kumar, A.N.

2012-01-01

In nuclear reactor physics and allied areas like shielding, various forms of neutron transport equation or its approximation namely the diffusion equation have to be solved to estimate neutron flux distribution. This paper presents an efficient algorithm yielding accurate results along with promising gain in computational work. (author)

A dynamic model of an innovative high-temperature solar heating and cooling system

Directory of Open Access Journals (Sweden)

Buonomano Annamaria

2016-01-01

Full Text Available In this paper a new simulation model of a novel solar heating and cooling system based on innovative high temperature flat plate evacuated solar thermal collector is presented. The system configuration includes: flat-plate evacuated solar collectors, a double-stage LiBr-H2O absorption chiller, gas-fired auxiliary heater, a closed loop cooling tower, pumps, heat exchangers, storage tanks, valves, mixers and controllers. The novelty of this study lies in the utilization of flat-plate stationary solar collectors, manufactured by TVP Solar, rather than concentrating ones (typically adopted for driving double-stage absorption chillers. Such devices show ultra-high thermal efficiencies, even at very high (about 200°C operating temperatures, thanks to the high vacuum insulation. Aim of the paper is to analyse the energy and economic feasibility of such novel technology, by including it in a prototypal solar heating and cooling system. For this purpose, the solar heating and cooling system design and performance were analysed by means of a purposely developed dynamic simulation model, implemented in TRNSYS. A suitable case study is also presented. Here, the simulated plant is conceived for the space heating and cooling and the domestic hot water production of a small building, whose energy needs are fulfilled through a real installation (settled also for experimental purposes built up close to Naples (South Italy. Simulation results show that the investigated system is able to reach high thermal efficiencies and very good energy performance. Finally, the economic analysis shows results comparable to those achieved through similar renewable energy systems.

Economically viable large-scale hydrogen liquefaction

Science.gov (United States)

Cardella, U.; Decker, L.; Klein, H.

2017-02-01

The liquid hydrogen demand, particularly driven by clean energy applications, will rise in the near future. As industrial large scale liquefiers will play a major role within the hydrogen supply chain, production capacity will have to increase by a multiple of today’s typical sizes. The main goal is to reduce the total cost of ownership for these plants by increasing energy efficiency with innovative and simple process designs, optimized in capital expenditure. New concepts must ensure a manageable plant complexity and flexible operability. In the phase of process development and selection, a dimensioning of key equipment for large scale liquefiers, such as turbines and compressors as well as heat exchangers, must be performed iteratively to ensure technological feasibility and maturity. Further critical aspects related to hydrogen liquefaction, e.g. fluid properties, ortho-para hydrogen conversion, and coldbox configuration, must be analysed in detail. This paper provides an overview on the approach, challenges and preliminary results in the development of efficient as well as economically viable concepts for large-scale hydrogen liquefaction.

Comparative performance analysis of ice plant test rig with TiO2-R-134a nano refrigerant and evaporative cooled condenser

OpenAIRE

Amrat Kumar Dhamneya; S.P.S. Rajput; Alok Singh

2018-01-01

The nanoparticle is used in chillers for increasing system performance. The increasing concentration of nanoparticles (TiO2) in refrigerant increases the performances of the system due decreasing compressor work done and enhance heat transfer rate. For hot and dry climate condition, performances of air-cooled condenser minimize, and C. O. P. decreases extensively in chillers due to heat transfer rate decreases in the condenser. In the condenser, nano-refrigerants are not cool at the desired l...

Fourth Annual Report on Energy Efficiency

International Nuclear Information System (INIS)

Di Franco, Nino; Bertini, Ilaria; Federici, Alessandro; Moneta Roberto

2015-01-01

Here we present the main elements of the annual report on energy efficiency 2015. The results indicate that, thanks to national policies for energy efficiency, Italy saved over 7.5 million tons of oil equivalent per year in the period 2005-2013. Compared to the National Plan for Energy Efficiency 2014, the report shows that the 2020 objectives have already been achieved for more than 20%, with residential (35.7% of the target) and industry (26.6%) among the sectors that contributed most to this result. Substantial savings could result from the agribusiness sector through the dissemination of efficient technologies in the logistics and large retail chains. A key role lies with the banks: 86% of banks has developed products dedicated to efficiency, necessitating guidelines for replicability of projects, and audit and rating to assess their quality [it

90 measurement of technical efficiency and its determinants in crop ...

African Journals Online (AJOL)

OLUWOLE AKINNAGBE

They found that education, number of working animals, credit per acre and number of extension visits significantly increased cost efficiency while large land holding size significantly decreased cost efficiency. In single estimation approach of the technical efficiency model for Indian farmers,. Colli et al (1998), found that years ...

Application of optimization techniques on lumped HVAC models for energy conservation

Energy Technology Data Exchange (ETDEWEB)

Wemhoff, A.P. [Department of Mechanical Engineering, Villanova University, Villanova, PA 19085 (United States)

2010-12-15

Heating, ventilating, and air conditioning (HVAC) systems comprise nearly one third of annual household energy consumption in the United States. HVAC energy use can be reduced by applying controls. This study applies a novel control method on a system with arbitrary steady-state and transient load distributions. The new method uses multi-dimensional interpolation between optimized control configurations for various steady-state load distributions. Demonstration of the new method on a two-room HVAC system predicts power savings for an arbitrary steady load that is nearly equivalent to that using a Variable-Air-Volume (VAV) with chiller modulation. However, the new method provides better energy savings for arbitrary transient loads: 19% energy savings over an uncontrolled system compared to energy savings of 6% for a VAV with chiller modulation. The average transient temperature deviation from setpoint using the new method is slightly better than that using VAV with chiller modulation. (author)

Development of Innovative Heating and Cooling Systems Using Renewable Energy Sources for Non-Residential Buildings

Directory of Open Access Journals (Sweden)

Cinzia Buratti

2013-10-01

Full Text Available Industrial and commercial areas are synonymous with high energy consumption, both for heating/cooling and electric power requirements, which are in general associated to a massive use of fossil fuels producing consequent greenhouse gas emissions. Two pilot systems, co-funded by the Italian Ministry for the Environment, have been created to upgrade the heating/cooling systems of two existing buildings on the largest industrial estate in Umbria, Italy. The upgrade was specifically designed to improve the system efficiency and to cover the overall energy which needs with renewable energy resources. In both cases a solar photovoltaic plant provides the required electric power. The first system features a geothermal heat pump with an innovative layout: a heat-storage water tank, buried just below ground level, allows a significant reduction of the geothermal unit size, hence requiring fewer and/or shorter boreholes (up to 60%–70%. In the other system a biomass boiler is coupled with an absorption chiller machine, controlling the indoor air temperature in both summer and winter. In this case, lower electricity consumption, if compared to an electric compression chiller, is obtained. The first results of the monitoring of summer cooling are presented and an evaluation of the performance of the two pilot systems is given.

Absorption cooling sources atmospheric emissions decrease by implementation of simple algorithm for limiting temperature of cooling water

Science.gov (United States)

Wojdyga, Krzysztof; Malicki, Marcin

2017-11-01

Constant strive to improve the energy efficiency forces carrying out activities aimed at reduction of energy consumption hence decreasing amount of contamination emissions to atmosphere. Cooling demand, both for air-conditioning and process cooling, plays an increasingly important role in the balance of Polish electricity generation and distribution system in summer. During recent years' demand for electricity during summer months has been steadily and significantly increasing leading to deficits of energy availability during particularly hot periods. This causes growing importance and interest in trigeneration power generation sources and heat recovery systems producing chilled water. Key component of such system is thermally driven chiller, mostly absorption, based on lithium-bromide and water mixture. Absorption cooling systems also exist in Poland as stand-alone systems, supplied with heating from various sources, generated solely for them or recovered as waste or useless energy. The publication presents a simple algorithm, designed to reduce the amount of heat for the supply of absorption chillers producing chilled water for the purposes of air conditioning by reducing the temperature of the cooling water, and its impact on decreasing emissions of harmful substances into the atmosphere. Scale of environmental advantages has been rated for specific sources what enabled evaluation and estimation of simple algorithm implementation to sources existing nationally.

Adaptive Origami for Efficiently Folded Structures

Science.gov (United States)

2016-02-01

heating. Although a large fold angle at a high temperature is desirable in order to extrapolate the origami geometry toward closure, more emphasis is...AFRL-RQ-WP-TR-2016-0020 ADAPTIVE ORIGAMI FOR EFFICIENTLY FOLDED STRUCTURES James J. Joo and Greg Reich Design and Analysis Branch... ORIGAMI FOR EFFICIENTLY FOLDED STRUCTURES 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S) James J

ArCLight—A Compact Dielectric Large-Area Photon Detector

Directory of Open Access Journals (Sweden)

Martin Auger

2018-02-01

Full Text Available ArgonCube Light readout system (ArCLight is a novel device for detecting scintillation light over large areas with Photon Detection Efficiency (PDE of the order of a few percent. Its robust technological design allows for efficient use in large-volume particle detectors, such as Liquid Argon Time Projection Chambers (LArTPCs or liquid scintillator detectors. Due to its dielectric structure it can be placed inside volumes with high electric field. It could potentially replace vacuum PhotoMultiplier Tubes (PMTs in applications where high PDE is not required. The photon detection efficiency for a 10 × 10 cm2 detector prototype was measured to be in the range of 0.8% to 2.2% across the active area.

Extravasal occlusion of large vessels with titanic clips: efficiency, indications, and contraindications.

Science.gov (United States)

Vasilenko, Yu V; Kim, A I; Kotov, S A

2002-11-01

The mechanism of extravasal occlusion of blood vessels with titanic clips "Atrauclip" and "Ligaclip extra" was studied in order to reveal indications and contraindications to their use. Occlusion with the clips of both types was ineffective in vessels with a diameter of >7.0 mm. Arteritis or the presence of an intravascular occlusion facility in the vessel were also the contraindications for clip occlusion. In overcases the procedure of occlusion with titanic clips was efficient and atraumatic.

Computational Model of a Biomass Driven Absorption Refrigeration System

Directory of Open Access Journals (Sweden)

Munyeowaji Mbikan

2017-02-01

Full Text Available The impact of vapour compression refrigeration is the main push for scientists to find an alternative sustainable technology. Vapour absorption is an ideal technology which makes use of waste heat or renewable heat, such as biomass, to drive absorption chillers from medium to large applications. In this paper, the aim was to investigate the feasibility of a biomass driven aqua-ammonia absorption system. An estimation of the solid biomass fuel quantity required to provide heat for the operation of a vapour absorption refrigeration cycle (VARC is presented; the quantity of biomass required depends on the fuel density and the efficiency of the combustion and heat transfer systems. A single-stage aqua-ammonia refrigeration system analysis routine was developed to evaluate the system performance and ascertain the rate of energy transfer required to operate the system, and hence, the biomass quantity needed. In conclusion, this study demonstrated the results of the performance of a computational model of an aqua-ammonia system under a range of parameters. The model showed good agreement with published experimental data.

Energy efficiency in Swedish industry

International Nuclear Information System (INIS)

Zhang, Shanshan; Lundgren, Tommy; Zhou, Wenchao

2016-01-01

This paper assesses energy efficiency in Swedish industry. Using unique firm-level panel data covering the years 2001–2008, the efficiency estimates are obtained for firms in 14 industrial sectors by using data envelopment analysis (DEA). The analysis accounts for multi-output technologies where undesirable outputs are produced alongside with the desirable output. The results show that there was potential to improve energy efficiency in all the sectors and relatively large energy inefficiencies existed in small energy-use industries in the sample period. Also, we assess how the EU ETS, the carbon dioxide (CO_2) tax and the energy tax affect energy efficiency by conducting a second-stage regression analysis. To obtain consistent estimates for the regression model, we apply a modified, input-oriented version of the double bootstrap procedure of Simar and Wilson (2007). The results of the regression analysis reveal that the EU ETS and the CO_2 tax did not have significant influences on energy efficiency in the sample period. However, the energy tax had a positive relation with the energy efficiency. - Highlights: • We use DEA to estimate firm-level energy efficiency in Swedish industry. • We examine impacts of climate and energy policies on energy efficiency. • The analyzed policies are Swedish carbon and energy taxes and the EU ETS. • Carbon tax and EU ETS did not have significant influences on energy efficiency. • The energy tax had a positive relation with energy efficiency.

Efficient Multidisciplinary Analysis Approach for Conceptual Design of Aircraft with Large Shape Change

Science.gov (United States)

Chwalowski, Pawel; Samareh, Jamshid A.; Horta, Lucas G.; Piatak, David J.; McGowan, Anna-Maria R.

2009-01-01

The conceptual and preliminary design processes for aircraft with large shape changes are generally difficult and time-consuming, and the processes are often customized for a specific shape change concept to streamline the vehicle design effort. Accordingly, several existing reports show excellent results of assessing a particular shape change concept or perturbations of a concept. The goal of the current effort was to develop a multidisciplinary analysis tool and process that would enable an aircraft designer to assess several very different morphing concepts early in the design phase and yet obtain second-order performance results so that design decisions can be made with better confidence. The approach uses an efficient parametric model formulation that allows automatic model generation for systems undergoing radical shape changes as a function of aerodynamic parameters, geometry parameters, and shape change parameters. In contrast to other more self-contained approaches, the approach utilizes off-the-shelf analysis modules to reduce development time and to make it accessible to many users. Because the analysis is loosely coupled, discipline modules like a multibody code can be easily swapped for other modules with similar capabilities. One of the advantages of this loosely coupled system is the ability to use the medium- to high-fidelity tools early in the design stages when the information can significantly influence and improve overall vehicle design. Data transfer among the analysis modules are based on an accurate and automated general purpose data transfer tool. In general, setup time for the integrated system presented in this paper is 2-4 days for simple shape change concepts and 1-2 weeks for more mechanically complicated concepts. Some of the key elements briefly described in the paper include parametric model development, aerodynamic database generation, multibody analysis, and the required software modules as well as examples for a telescoping wing

Efficient network monitoring for large data acquisition systems

International Nuclear Information System (INIS)

Savu, D.O.; Martin, B.; Al-Shabibi, A.; Sjoen, R.; Batraneanu, S.M.; Stancu, S.N.

2012-01-01

Though constantly evolving and improving, the available network monitoring solutions have limitations when applied to the infrastructure of a high speed realtime data acquisition (DAQ) system. DAQ networks are particular computer networks where experts have to pay attention to both individual subsections as well as system wide traffic flows while monitoring the network. The ATLAS Network at the Large Hadron Collider (LHC) has more than 200 switches interconnecting 3500 hosts and totaling 8500 high speed links. The use of heterogeneous tools for monitoring various infrastructure parameters, in order to assure optimal DAQ system performance, proved to be a tedious and time consuming task for experts. To alleviate this problem we used our networking and DAQ expertise to build a flexible and scalable monitoring system providing an intuitive user interface with the same look and feel irrespective of the data provider that is used. Our system uses custom developed components for critical performance monitoring and seamlessly integrates complementary data from auxiliary tools, such as NAGIOS, information services or custom databases. A number of techniques (e.g. normalization, aggregation and data caching) were used in order to improve the user interface response time. The end result is a unified monitoring interface, for fast and uniform access to system statistics, which significantly reduced the time spent by experts for ad-hoc and post-mortem analysis. (authors)

Efficient computation of Laguerre polynomials

NARCIS (Netherlands)

A. Gil (Amparo); J. Segura (Javier); N.M. Temme (Nico)

2017-01-01

textabstractAn efficient algorithm and a Fortran 90 module (LaguerrePol) for computing Laguerre polynomials . Ln(α)(z) are presented. The standard three-term recurrence relation satisfied by the polynomials and different types of asymptotic expansions valid for . n large and . α small, are used

Phonetic search methods for large speech databases

CERN Document Server

Moyal, Ami; Tetariy, Ella; Gishri, Michal

2013-01-01

“Phonetic Search Methods for Large Databases” focuses on Keyword Spotting (KWS) within large speech databases. The brief will begin by outlining the challenges associated with Keyword Spotting within large speech databases using dynamic keyword vocabularies. It will then continue by highlighting the various market segments in need of KWS solutions, as well as, the specific requirements of each market segment. The work also includes a detailed description of the complexity of the task and the different methods that are used, including the advantages and disadvantages of each method and an in-depth comparison. The main focus will be on the Phonetic Search method and its efficient implementation. This will include a literature review of the various methods used for the efficient implementation of Phonetic Search Keyword Spotting, with an emphasis on the authors’ own research which entails a comparative analysis of the Phonetic Search method which includes algorithmic details. This brief is useful for resea...

Modeling and simulation of an activated carbon–CO2 four bed based adsorption cooling system

International Nuclear Information System (INIS)

Jribi, Skander; Saha, Bidyut Baran; Koyama, Shigeru; Bentaher, Hatem

2014-01-01

Highlights: • A transient mathematical model of a 4-bed adsorption chiller is proposed. • The performances of the cyclic-steady-state system are presented for different heating and cooling water inlet temperatures. • The desorption pressure has a big influence in the performances. • With 80 kg of Maxsorb III, the CO 2 based adsorption chiller produces 2 kW of cooling power and presents a COP of 0.1. - Abstract: In this study, a transient mathematical model of a 4-bed adsorption chiller using Maxsorb III as the adsorbent and CO 2 as the refrigerant has been analyzed. The performances of the cyclic-steady-state system are presented for different heating and cooling water inlet temperatures. It is found that the desorption pressure has a big influence in the performances due to the low critical point of CO 2 (T c = 31 °C). With 80 kg of Maxsorb III, the CO 2 based adsorption chiller produces 2 kW of cooling power and presents a COP of 0.1, at driving heat source temperature of 95 °C along with a cooling temperature of 27 °C and at optimum desorption pressure of 79 bar. The present thermal compression air-conditioning system could be driven with solar energy or waste heat from internal combustion engines and therefore is suitable for both residential and mobile air-conditioning applications

Analysis of ice cool thermal storage for a clinic building in Kuwait

International Nuclear Information System (INIS)

Sebzali, M.J.; Rubini, P.A.

2006-01-01

In Kuwait, air conditioning (AC) systems consume 61% and 40% of the peak electrical load and total electrical energy, respectively. This is due to a very high ambient temperature for the long summer period extended from April to October and the low energy cost. This paper gives an overview of the electrical peak and energy consumption in Kuwait, and it has been found that the average increase in the annual peak electrical demand and energy consumption for the year 1998-2002 was 6.2% and 6.4%, respectively. One method of reducing the peak electrical demand of AC systems during the day period is by incorporating an ice cool thermal storage (ICTS) with the AC system. A clinic building has been selected to study the effects of using an ICTS with different operation strategies such as partial (load levelling), partial (demand limiting) and full storage operations on chiller and storage sizes, reduction of peak electrical demand and energy consumption of the chiller for selected charging and discharging hours. It has been found that the full storage operation has the largest chiller and storage capacities, energy consumption and peak electrical reduction. However, partial storage (load levelling) has the smallest chiller and storage capacities and peak electrical reduction. This paper also provides a detailed comparison of using ICTS operating strategies with AC and AC systems without ICTS

A review of challenges to determining and demonstrating efficiency of large fire management

Science.gov (United States)

Matthew P. Thompson; Francisco Rodriguez y Silva; David E. Calkin; Michael S. Hand

2017-01-01

Characterising the impacts of wildland fire and fire suppression is critical information for fire management decision-making. Here, we focus on decisions related to the rare larger and longer-duration fire events, where the scope and scale of decision-making can be far broader than initial response efforts, and where determining and demonstrating efficiency of...

Large-area NbN superconducting nanowire avalanche photon detectors with saturated detection efficiency

Science.gov (United States)

Murphy, Ryan P.; Grein, Matthew E.; Gudmundsen, Theodore J.; McCaughan, Adam; Najafi, Faraz; Berggren, Karl K.; Marsili, Francesco; Dauler, Eric A.

2015-05-01

Superconducting circuits comprising SNSPDs placed in parallel—superconducting nanowire avalanche photodetectors, or SNAPs—have previously been demonstrated to improve the output signal-to-noise ratio (SNR) by increasing the critical current. In this work, we employ a 2-SNAP superconducting circuit with narrow (40 nm) niobium nitride (NbN) nanowires to improve the system detection efficiency to near-IR photons while maintaining high SNR. Additionally, while previous 2-SNAP demonstrations have added external choke inductance to stabilize the avalanching photocurrent, we show that the external inductance can be entirely folded into the active area by cascading 2-SNAP devices in series to produce a greatly increased active area. We fabricated series-2-SNAP (s2-SNAP) circuits with a nanowire length of 20 μm with cascades of 2-SNAPs providing the choke inductance necessary for SNAP operation. We observed that (1) the detection efficiency saturated at high bias currents, and (2) the 40 nm 2-SNAP circuit critical current was approximately twice that for a 40 nm non-SNAP configuration.

Accounting for immunoprecipitation efficiencies in the statistical analysis of ChIP-seq data

NARCIS (Netherlands)

Bao, Yanchun; Vinciotti, Veronica; Wit, Ernst; 't Hoen, Peter A C

2013-01-01

Background: ImmunoPrecipitation (IP) efficiencies may vary largely between different antibodies and between repeated experiments with the same antibody. These differences have a large impact on the quality of ChIP-seq data: a more efficient experiment will necessarily lead to a higher signal to

Exergetic performance analysis of a recirculating aquaculture system

International Nuclear Information System (INIS)

Kucuk, Haydar; Midilli, Adnan; Ozdemir, Atilla; Cakmak, Eyuep; Dincer, Ibrahim

2010-01-01

This paper examines exergetic aspects of a Recirculation Aquaculture System (RAS) for Black Sea trout (Salmo trutta labrax) fingerling rearing at the Trabzon Central Fisheries Research Institute, Turkey. In its thermodynamic analysis, each component of the RAS is treated as a steady-state steady flow system and its exergetic efficiencies are studied. In addition, the following parameters are measured and recorded in experiments: the mass flow rates, inlet and outlet temperatures and of the system components, surrounding temperatures, and electrical work utilized by the components in the RAS. Based on these experimental data, inlet and outlet exergy values, exergy losses, and exergetic efficiencies of each component in the system are determined to assess their performance. Moreover, the overall system exergy efficiency is determined. The results show that exergy efficiencies of the system components are highly affected by varying input exergy flows as a function of the surrounding temperature and chiller's operating period.

Responding to high energy prices: energy management services

International Nuclear Information System (INIS)

Raynolds, M.

2001-01-01

Rapid growth in the number and sophistication of energy management companies has been observed in the wake of rising energy prices. These companies offer energy-efficiency consulting services to utilities, government and industry with the promise of improved cost efficiency, marketplace competitiveness and environmental commitments. The environmental benefits result from the reduction in emissions and pollutants associated with power production and natural gas used for space heating. In general, the stock in trade of these energy management companies is the energy audit involving evaluation of existing equipment in buildings and facilities and the resulting recommendations to install energy-efficient equipment such as lighting retrofits, boiler replacement, chiller replacement, variable speed drives, high-efficiency motors, improved insulation and weather proofing, water heaters and piping. The North American market for energy management services was estimated in 1997 at $208 billion (rising to $350 billion by 2004). Current market penetration is less than two per cent

Design and simulation of a heat transformer of a directly solar-driven diffusion absorption chiller; Auslegung und Simulation von Waermeuebertragern einer direkt solarthermisch angetriebenen Diffusions-Absorptionskaeltemaschine