21 CFR 890.5950 - Powered heating unit.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Powered heating unit. 890.5950 Section 890.5950...) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5950 Powered heating unit. (a) Identification. A powered heating unit is a device intended for medical purposes that...

Acceptance/Operational Test Report for Tank 241-AN-104 camera and camera purge control system

International Nuclear Information System (INIS)

Castleberry, J.L.

1995-11-01

This Acceptance/Operational Test Procedure (ATP/OTP) will document the satisfactory operation of the camera purge panel, purge control panel, color camera system and associated control components destined for installation. The final acceptance of the complete system will be performed in the field. The purge panel and purge control panel will be tested for its safety interlock which shuts down the camera and pan-and-tilt inside the tank vapor space during loss of purge pressure and that the correct purge volume exchanges are performed as required by NFPA 496. This procedure is separated into seven sections. This Acceptance/Operational Test Report documents the successful acceptance and operability testing of the 241-AN-104 camera system and camera purge control system

Design of a unit to produce hot distilled water for the same power consumption as a water heater

Science.gov (United States)

Bambenek, R. A.; Nuccio, P. P.

1973-01-01

Unit recovers 97% of water contained in pretreated waste water. Some factors are: cleansing agent prevents fouling of heat transfer surface by highly concentrated waste; absence of dynamic seals reduces required purge gas flow rate; and recycle loop maintains constant flushing process to carry cleansing agent across evaporation surface.

Demonstration of containment purge and vent valve operability for the Hope Creek Generating Station, Unit 1 (Docket No. 50-354)

International Nuclear Information System (INIS)

Kido, C.

1985-05-01

The containment purge and vent valve qualification program for the Hope Creek Generating Station has been reviewed by the NRC Licensing Support Section. The review indicates that the licensee has demonstrated the dependability of containment isolation against the buildup of containment pressure due to a LOCA/DBA with the restrictions that during operating conditions 1, 2, and 3 all purge and vent valves will be sealed closed and under administrative control, and during power ascension and descension conditions the 26 in. inboard valve (1-GS-HV-4952) will be used in series with the 2 in. bypass valve (1-GS-HV-4951) to control the release of containment pressure

Design and development of pressure and repressurization purge system for reusable space shuttle multilayer insulation system

Science.gov (United States)

1972-01-01

The experimental determination of purge bag materials properties, development of purge bag manufacturing techniques, experimental evaluation of a subscale purge bag under simulated operating conditions and the experimental evaluation of the purge pin concept for MLI purging are discussed. The basic purge bag material, epoxy fiberglass bounded by skins of FEP Teflon, showed no significant permeability to helium flow under normal operating conditions. Purge bag small scale manufacturing tests were conducted to develop tooling and fabrication techniques for use in full scale bag manufacture. A purge bag material layup technique was developed whereby the two plys of epoxy fiberglass enclosed between skins of FEP Teflon are vacuum bag cured in an oven in a single operation. The material is cured on a tool with the shape of a purge bag half. Plastic tooling was selected for use in bag fabrication. A model purge bag 0.6 m in diameter was fabricated and subjected to a series of structural and environmental tests simulating various flight type environments. Pressure cycling tests at high (450 K) and low (200 K) temperature as well as acoustic loading tests were performed. The purge bag concept proved to be structurally sound and was used for the full scale bag detailed design model.

TNKVNT: A model of the Tank 48 purge/ventilation exhaust system. Revision 1

International Nuclear Information System (INIS)

Shadday, M.A. Jr.

1996-04-01

The waste tank purge ventilation system for Tank 48 is designed to prevent dangerous concentrations of hydrogen or benzene from accumulating in the gas space of the tank. Fans pull the gas/water vapor mixture from the tank gas space and pass it sequentially through a demister, a condenser, a reheater, and HEPA filters before discharging to the environment. Proper operation of the HEPA filters requires that the gas mixture passing through them has a low relative humidity. The ventilation system has been modified by increasing the capacity of the fans and changing the condenser from a two-pass heat exchanger to a single-pass heat exchanger. It is important to understand the impact of these modifications on the operation of the system. A hydraulic model of the ventilation exhaust system has been developed. This model predicts the properties of the air throughout the system and the flowrate through the system, as functions of the tank gas space and environmental conditions. This document serves as a Software Design Report, a Software Coding report, and a User's Manual. All of the information required for understanding and using this code is herein contained: the governing equations are fully developed, the numerical algorithms are described in detail, and an extensively commented code listing is included. This updated version of the code models the entire purge ventilation system, and is therefore more general in its potential applications

The Initial Purging Policies after the 1965 Incident at Lubang Buaya

Directory of Open Access Journals (Sweden)

Yosef Djakababa

2013-01-01

Full Text Available After the Lubang Buaya incident on 1 October 1965 in which six top Indonesian Army generals and a lieutenant were killed, the Army began to implement a nationwide purging campaign with the assistance of civilian anti-communist groups. Thousands of PKI members, supporters and pro-Sukarno groups/individuals immediately became the target of this purge. For organisational purposes, several purging policies were released and then strictly enforced. The official purging policies that are highlighted in this paper are a series of initial directives that were released within days of the generals’ executions. They do not explicitly translate into orders to kill, but are more of a guideline to help anti-communist officials classify and contain communists and other PKI followers. This article attempts to show how these initial directives evolved and also discusses competing purge policies from non-military sources. The co-existence and overlapping nature of the various directives indicate that a power struggle existed between the anti-communist group led by General Soeharto and the presidium of the Dwikora Cabinet who were loyal to President Soekarno.

Air riding seal with purge cavity

Science.gov (United States)

Sexton, Thomas D; Mills, Jacob A

2017-08-15

An air riding seal for a turbine in a gas turbine engine, where an annular piston is axial moveable within an annular piston chamber formed in a stator of the turbine and forms a seal with a surface on the rotor using pressurized air that forms a cushion in a pocket of the annular piston. A purge cavity is formed on the annular piston and is connected to a purge hole that extends through the annular piston to a lower pressure region around the annular piston or through the rotor to an opposite side. The annular piston is sealed also with inner and outer seals that can be a labyrinth seal to form an additional seal than the cushion of air in the pocket to prevent the face of the air riding seal from overheating.

Solute transport in a well under slow-purge and no-purge conditions

Science.gov (United States)

Plummer, M. A.; Britt, S. L.; Martin-Hayden, J. M.

2010-12-01

Non-purge sampling techniques, such as diffusion bags and in-situ sealed samplers, offer reliable and cost-effective groundwater monitoring methods that are a step closer to the goal of real-time monitoring without pumping or sample collection. Non-purge methods are, however, not yet completely accepted because questions remain about how solute concentrations in an unpurged well relate to concentrations in the adjacent formation. To answer questions about how undisturbed well water samples compare to formation concentrations, and to provide the information necessary to interpret results from non-purge monitoring systems, we have conducted a variety of physical experiments and numerical simulations of flow and transport in and through monitoring wells under low-flow and ambient flow conditions. Previous studies of flow and transport in wells used a Darcy’s law - based continuity equation for flow, which is often justified under the strong, forced-convection flow caused by pumping or large vertical hydraulic potential gradients. In our study, we focus on systems with weakly forced convection, where density-driven free convection may be of similar strength. We therefore solved Darcy’s law for porous media domains and the Navier Stokes equations for flow in the well, and coupled solution of the flow equations to that of solute transport. To illustrate expected in-well transport behavior under low-flow conditions, we present results of three particular studies: (1) time-dependent effluent concentrations from a well purged at low-flow pumping rates, (2) solute-driven density effects in a well under ambient horizontal flow and (3) temperature-driven mixing in a shallow well subject to seasonal temperature variations. Results of the first study illustrate that assumptions about the nature of in-well flow have a significant impact on effluent concentration curves even during pumping, with Poiseuille-type flow producing more rapid removal of concentration differences

Energetic and Exergy Efficiency of a Heat Storage Unit for Building Heating

International Nuclear Information System (INIS)

Hazami, Mejdi; Kooli, Sami; Lazaar, Meriem; Farhat, Abdelhamid; Belghith, Ali

2009-01-01

This paper deals with a numerical and experimental investigation of a daily solar storage system conceived and built in Laboratoire de Maitrise des Technologies de l Energie (LMTE, Borj Cedria). This system consists mainly of the storage unit connected to a solar collector unit. The storage unit consists of a wooden case with dimension of 5 m 3 (5 m x 1m x 1m) filed with fin sand. Inside the wooden case was buried a network of a polypropylene capillary heat exchanger with an aperture area equal to 5 m 2 . The heat collection unit consisted of 5 m 2 of south-facing solar collector mounted at a 37 degree tilt angle. In order to evaluate the system efficiency during the charging period (during the day) and discharging period (during the night) an energy and exergy analyses were applied. Outdoor experiments were also carried out under varied environmental conditions for several consecutive days. Results showed that during the charging period, the average daily rates of thermal energy and exergy stored in the heat storage unit were 400 and 2.6 W, respectively. It was found that the net energy and exergy efficiencies in the charging period were 32 pour cent and 22 pour cent, respectively. During the discharging period, the average daily rates of the thermal energy and exergy recovered from the heat storage unit were 2 kW and 2.5 kW, respectively. The recovered heat from the heat storage unit was used for the air-heating of a tested room (4 m x 3 m x 3 m). The results showed that 30 pour cent of the total heating requirement of the tested room was obtained from the heat storage system during the whole night in cold seasons

Distinguishing Between Risk Factors for Bulimia Nervosa, Binge Eating Disorder, and Purging Disorder.

Science.gov (United States)

Allen, Karina L; Byrne, Susan M; Crosby, Ross D

2015-08-01

Binge eating disorder and purging disorder have gained recognition as distinct eating disorder diagnoses, but risk factors for these conditions have not yet been established. This study aimed to evaluate a prospective, mediational model of risk for the full range of binge eating and purging eating disorders, with attention to possible diagnostic differences. Specific aims were to determine, first, whether eating, weight and shape concerns at age 14 would mediate the relationship between parent-perceived childhood overweight at age 10 and a binge eating or purging eating disorder between age 15 and 20, and, second, whether this mediational model would differ across bulimia nervosa, binge eating disorder, and purging disorder. Participants (N = 1,160; 51 % female) were drawn from the Western Australian Pregnancy Cohort (Raine) Study, which has followed children from pre-birth to age 20. Eating disorders were assessed via self-report questionnaires when participants were aged 14, 17 and 20. There were 146 participants (82 % female) with a binge eating or purging eating disorder with onset between age 15 and 20 [bulimia nervosa = 81 (86 % female), binge eating disorder = 43 (74 % female), purging disorder = 22 (77 % female)]. Simple mediation analysis with bootstrapping was used to test the hypothesized model of risk, with early adolescent eating, weight and shape concerns positioned as a mediator between parent-perceived childhood overweight and later onset of a binge eating or purging eating disorder. Subsequently, a conditional process model (a moderated mediation model) was specified to determine if model pathways differed significantly by eating disorder diagnosis. In the simple mediation model, there was a significant indirect effect of parent-perceived childhood overweight on risk for a binge eating or purging eating disorder in late adolescence, mediated by eating, weight and shape concerns in early adolescence. In the conditional process model

Aquifer restoration system improvement using an acid fluid purge

International Nuclear Information System (INIS)

Hodder, E.A.; Peck, C.A.

1992-01-01

The implementation of a water pump acid purge procedure at a free-phase liquid hydrocarbon recovery site has increased water pump operational run times and improved the effectiveness of the aquifer restoration effort. Before introduction of this technique, pumps at some locations would fail within 14 days of operation due to CaSO 4 .2H 2 O (calcium sulfate) precipitate fouling. After acid purge implementation at these locations, pump operational life improved to an average of over 110 days. Other locations, where pump failures would occur within one month, were improved to approximately six months of operation. The increase in water pump run time has also improved the liquid hydrocarbon recovery rate by 2,000 gallons per day; representing a 20% increase for the aquifer restoration system. Other concepts tested in attempts to prolong pump life included: specially designed electric submersible pumps, submersible pump shrouds intended to reduce the fluid pressure shear that enhances CaSO 4 .2H 2 O precipitation, and high volume pneumatic gas lift pumps. Due to marginal pump life improvement or other undesirable operational features, these concepts were primarily ineffective. The purge apparatus utilizes an acid pump, hose, and discharge piping to deliver the solution directly into the inlet of an operating water pump. The water pumps used for this activity require stainless steel construction with Teflon or other acid resistant bearings and seals. Purges are typically conducted before sudden discharge pressure drops (greater than 15 psig) occur for the operating water pump. Depending on volume of precipitate accumulation and pump type, discharge pressure is restored after introduction of 10 to 40 gallons of hydrochloric acid solution. The acid purge procedure outlined herein eliminates operational downtime and does not require well head pump removal and the associated costs of industry cleaning procedures

Indoor unit for electric heat pump

Science.gov (United States)

Draper, R.; Lackey, R.S.; Fagan, T.J. Jr.; Veyo, S.E.; Humphrey, J.R.

1984-05-22

An indoor unit for an electric heat pump is provided in modular form including a refrigeration module, an air mover module, and a resistance heat package module, the refrigeration module including all of the indoor refrigerant circuit components including the compressor in a space adjacent the heat exchanger, the modules being adapted to be connected to air flow communication in several different ways as shown to accommodate placement of the unit in various orientations. 9 figs.

Realization of dynamic data migration and purge operations

International Nuclear Information System (INIS)

Wang Juan; Qiu Hongmao; Liu Junmin; Wang Xiaoming; Wang Hong; Zhong Bo; Lu Yuanlei; Xu Jin

2008-01-01

In the large scale real time data processing, with the time extend, the data in database system will be expanded, which declines the system capability. To solve the problem, this paper presents a method of migration and purge operations. New or updated database records within a specified time interval can be copied automatically from source database accounts to destination database accounts and the data in the source database will be deleted automatically after a specified period of time according to the rules using the method. The migration and purge operations have been realized in China National Data Center. (authors)

Evaluation of the Purge Water Management System (PWMS) monitor well sampling technology at SRS

International Nuclear Information System (INIS)

Hiergesell, R.A.; Cardoso-Neto, J.E.; Williams, D.W.

1997-01-01

Due to the complex issues surrounding Investigation Derived Waste (IDW) at SRS, the Environmental Restoration Division has been exploring new technologies to deal with the purge water generated during monitoring well sampling. Standard procedures for sampling generates copious amounts of purge water that must be managed as hazardous waste, when containing hazardous and/or radiological contaminants exceeding certain threshold levels. SRS has obtained Regulator approval to field test an innovative surface release prevention mechanism to manage purge water. This mechanism is referred to as the Purge Water Management System (PWMS) and consists of a collapsible bladder situated within a rigid metal tank

ATR/OTR-SY Tank Camera Purge System and in Tank Color Video Imaging System

International Nuclear Information System (INIS)

Werry, S.M.

1995-01-01

This procedure will document the satisfactory operation of the 101-SY tank Camera Purge System (CPS) and 101-SY in tank Color Camera Video Imaging System (CCVIS). Included in the CPRS is the nitrogen purging system safety interlock which shuts down all the color video imaging system electronics within the 101-SY tank vapor space during loss of nitrogen purge pressure

Acceptance/operational test procedure 101-AW tank camera purge system and 101-AW video camera system

International Nuclear Information System (INIS)

Castleberry, J.L.

1994-01-01

This procedure will document the satisfactory operation of the 101-AW Tank Camera Purge System (CPS) and the 101-AW Video Camera System. The safety interlock which shuts down all the electronics inside the 101-AW vapor space, during loss of purge pressure, will be in place and tested to ensure reliable performance. This procedure is separated into four sections. Section 6.1 is performed in the 306 building prior to delivery to the 200 East Tank Farms and involves leak checking all fittings on the 101-AW Purge Panel for leakage using a Snoop solution and resolving the leakage. Section 7.1 verifies that PR-1, the regulator which maintains a positive pressure within the volume (cameras and pneumatic lines), is properly set. In addition the green light (PRESSURIZED) (located on the Purge Control Panel) is verified to turn on above 10 in. w.g. and after the time delay (TDR) has timed out. Section 7.2 verifies that the purge cycle functions properly, the red light (PURGE ON) comes on, and that the correct flowrate is obtained to meet the requirements of the National Fire Protection Association. Section 7.3 verifies that the pan and tilt, camera, associated controls and components operate correctly. This section also verifies that the safety interlock system operates correctly during loss of purge pressure. During the loss of purge operation the illumination of the amber light (PURGE FAILED) will be verified

Heat transfer unit and method for prefabricated vessel

Science.gov (United States)

Tamburello, David A.; Kesterson, Matthew R; Hardy, Bruce J.

2017-11-07

Vessel assemblies, heat transfer units for prefabricated vessels, and methods for heat transfer prefabricated vessel are provided. A heat transfer unit includes a central rod, and a plurality of peripheral rods surrounding the central rod and connected to the central rod. The plurality of peripheral rods are movable between a first collapsed position and a second bowed position, wherein in the second bowed position a midpoint of each of the plurality of peripheral rods is spaced from the central rod relative to in the first position. The heat transfer unit further includes a heat transfer element connected to one of the plurality of peripheral rods.

Determination of cyclic volatile methylsiloxanes in biota with a purge and trap method.

Science.gov (United States)

Kierkegaard, Amelie; Adolfsson-Erici, Margaretha; McLachlan, Michael S

2010-11-15

The three cyclic volatile methylsiloxanes (cVMS), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6), are recently identified environmental contaminants. Methods for the trace analysis of these chemicals in environmental matrices are required. A purge and trap method to prepare highly purified sample extracts with a low risk of sample contamination is presented. Without prior homogenization, the sample is heated in water, and the cVMS are purged from the slurry and trapped on an Isolute ENV+ cartridge. They are subsequently eluted with n-hexane and analyzed with GC/MS. The method was tested for eight different matrices including ragworms, muscle tissue from lean and lipid-rich fish, cod liver, and seal blubber. Analyte recoveries were consistent within and between matrices, averaging 79%, 68%, and 56% for D4, D5, and D6, respectively. Good control of blank levels resulted in limits of quantification of 1.5, 0.6, and 0.6 ng/g wet weight. The repeatability was 12% (D5) and 15% (D6) at concentrations 9 and 2 times above the LOQ. The method was applied to analyze cVMS in fish from Swedish lakes, demonstrating that contamination in fish as a result of long-range atmospheric transport is low as compared to contamination from local sources.

DEM-CFD simulation of purge gas flow in a solid breeder pebble bed

Energy Technology Data Exchange (ETDEWEB)

Zhang, Hao [School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230027 (China); Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Li, Zhenghong [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); University of Science and Technology of China, Hefei 230027 (China); Guo, Haibing [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Ye, Minyou [School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230027 (China); Huang, Hongwen, E-mail: inpclane@sina.com [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China)

2016-12-15

Solid tritium breeding blanket applying pebble bed concept is promising for fusion reactors. Tritium bred in the pebble bed is purged out by inert gas. The flow characteristics of the purge gas are important for the tritium transport from the solid breeder materials. In this study, a randomly packed pebble bed was generated by Discrete Element Method (DEM) and verified by radial porosity distribution. The flow parameters of the purge gas in channels were solved by Computational Fluid Dynamics (CFD) method. The results show that the normalized velocity magnitudes have the same damped oscillating patterns with radial porosity distribution. Besides, the bypass flow near the wall cannot be ignored in this model, and it has a slight increase with inlet velocity. Furthermore, higher purging efficiency becomes with higher inlet velocity and especially higher in near wall region.

Numerical study on influences of bed resettling, breeding zone orientation, and purge gas on temperatures in solid breeders

Energy Technology Data Exchange (ETDEWEB)

Van Lew, Jon T., E-mail: jtvanlew@fusion.ucla.edu; Ying, Alice; Abdou, Mohamed

2016-11-01

Highlights: • Volume-conserving pebble fragmentation model in DEM to study thermomechanical responses to crushed pebbles in ensembles. • Parametric studies of ITER-relevant pebble beds with coupled CFD-DEM models. • Finding breeder temperatures are complex functions of orientation, fragmentation size, and packing fraction. • Recommendations of breeder unit orientation are given in terms of material selection. - Abstract: We apply coupled computational fluid dynamics and discrete element method (CFD-DEM) modeling tools with new numerical implementations of pebble fragmentation to study the combined effects of granular crushing and ensemble restructuring, granular fragment size, and initial packing for different breeder volume configurations. In typical solid breeder modules, heat removal from beds relies on maintaining pebble–pebble and pebble–wall contact integrity. However, contact is disrupted when an ensemble responds to individually crushed pebbles. Furthermore, restructuring of metastable packings after crushing events are, in part, dependent on gravity forces acting upon the pebbles. We investigate two representative pebble bed configurations under constant volumetric heat sources; modeling heat removed from beds via inter-particle conduction, purge gas convection, and contact between pebble beds and containers. In one configuration, heat is removed from at walls oriented parallel to the gravity vector (no gap formation possible); in the second, heat is removed at walls perpendicular to gravity, allowing for the possibility of gap formation between bed and wall. Judging beds on increase in maximum temperatures as a function of crushed pebble amount, we find that both pebble bed configurations to have advantageous features that manifest at different stages of pebble crushing. However, all configurations benefit from achieving high initial packing fractions.

Thermal analysis of LOFT waste gas processing system nitrogen supply for process line purge and blower seal

International Nuclear Information System (INIS)

Tatar, G.A.

1979-01-01

The LOFT Waste Gas Processing System uses gaseous nitrogen (GN 2 ) to purge the main process line and to supply pressure on the blower labyrinth seal. The purpose of this analysis was to determine the temperature of the GN 2 at the blower seals and the main process line. Since these temperatures were below 32 0 F the heat rate necessary to raise these temperatures was calculated. This report shows that the GN 2 temperatures at the points mentioned above were below 10 0 F. A heat rate into the GN 2 of 389 Watts added at the point where the supply line enters the vault would raise the GN 2 temperature above 32 0 F

AP600 containment purge radiological analysis

Energy Technology Data Exchange (ETDEWEB)

O`Connor, M.; Schulz, J.; Tan, C. [Bechtel Power Corporation (United States)] [and others

1995-02-01

The AP600 Project is a passive pressurized water reactor power plant which is part of the Design Certification and First-of-a-Kind Engineering effort under the Advanced Light Water Reactor program. Included in this process is the design of the containment air filtration system which will be the subject of this paper. We will compare the practice used by previous plants with the AP600 approach to meet the goals of industry standards in sizing the containment air filtration system. The radiological aspects of design are of primary significance and will be the focus of this paper. The AP600 Project optimized the design to combine the functions of the high volumetric flow rate, low volumetric flow rate, and containment cleanup and other filtration systems into one multi-functional system. This achieves a more simplified, standardized, and lower cost design. Studies were performed to determine the possible concentrations of radioactive material in the containment atmosphere and the effectiveness of the purge system to keep concentrations within 10CFR20 limits and within offsite dose objectives. The concentrations were determined for various reactor coolant system leakage rates and containment purge modes of operation. The resultant concentrations were used to determine the containment accessibility during various stages of normal plant operation including refueling. The results of the parametric studies indicate that a dual train purge system with a capacity of 4,000 cfm per train is more than adequate to control the airborne radioactivity levels inside containment during normal plant operation and refueling, and satisfies the goals of ANSI/ANS-56.6-1986 and limits the amount of radioactive material released to the environment per ANSI/ANS 59.2-1985 to provide a safe environment for plant personnel and offsite residents.

Sexual Orientation Disparities in Purging and Binge Eating From Early to Late Adolescence

Science.gov (United States)

Austin, S. Bryn; Ziyadeh, Najat J.; Corliss, Heather L.; Rosario, Margaret; Wypij, David; Haines, Jess; Camargo, Carlos A.; Field, Alison E.

2009-01-01

Purpose To describe patterns of purging and binge eating from early through late adolescence in female and male youth across a range of sexual orientations. Methods Using data from the prospective Growing Up Today Study, a large cohort of U.S. youth, we investigated trends in past-year self-reports of purging (ever vomit or use laxatives for weight control) and binge eating at least monthly. The analytic sample included 57,668 observations from repeated measures gathered from 13,795 youth ages 12 to 23 years providing information collected by self-administered questionnaires from six waves of data collection. We used multivariable logistic regression models to examine sexual orientation group (heterosexual, “mostly heterosexual,” bisexual, and lesbian/gay) differences in purging and binge eating throughout adolescence, with same-gender heterosexuals as the referent group and controlling for age and race/ethnicity. Results Throughout adolescence, in most cases, sexual orientation group differences were evident at the youngest ages and persisted through adolescence. Among females and compared to heterosexuals, “mostly heterosexuals,” bisexuals, and lesbians were more likely to report binge eating, but only “mostly heterosexuals” and bisexuals were also more likely to report purging. Among males, all three sexual orientation subgroups were more likely than heterosexual males to report both binge eating and purging. Within each orientation subgroup, females generally reported higher prevalence of purging and binge eating than did males. Conclusions Clinicians need to be alert to the risk of eating disordered behaviors in lesbian, gay, bisexual, and “mostly heterosexual” adolescents of both genders in order to better evaluate these youth and refer them for treatment. PMID:19699419

Characteristic regional cerebral blood flow patterns in anorexia nervosa patients with binge/purge behavior.

Science.gov (United States)

Naruo, T; Nakabeppu, Y; Sagiyama, K; Munemoto, T; Homan, N; Deguchi, D; Nakajo, M; Nozoe, S

2000-09-01

The authors' goal was to investigate the effect of imagining food on the regional cerebral blood flow (rCBF) of anorexia nervosa patients with and without habitual binge/purge behavior. The subjects included seven female patients with purely restrictive anorexia, seven female patients with anorexia and habitual binge/purge behavior, and seven healthy women. Single photon emission computed tomography examination was performed before and after the subjects were asked to imagine food. Changes in rCBF count ratios (percent change) were then calculated and compared. The subjects were also asked to assess their degree of fear regarding their control of food intake. The anorexia nervosa patients with habitual binge/purge behavior had a significantly higher percent change in the inferior, superior, prefrontal, and parietal regions of the right brain than the patients with purely restrictive anorexia and the healthy volunteers. The patients with habitual binge/purge behavior also had the highest level of apprehension in regard to food intake. Specific activation in cortical regions suggests an association between habitual binge/purge behavior and the food recognition process linked to anxiety in patients with anorexia nervosa.

Evaluation of Purging Solutions for Military Fuel Tanks

National Research Council Canada - National Science Library

Rhee, In-Sik

2003-01-01

.... It is also a biodegradable water based solvent. Because of this property, US Army has used this environmentally friendly solvent as a purging solution in all military fuel tanks including Heavy Expanded Mobility Truck (HEMTT...

Some performance characteristics of a fluidized bed heat recovery unit

International Nuclear Information System (INIS)

Militzer, J.; Basu, P.; Adaikkappan, N.

1985-01-01

The advantages of using fluidized bed heat recovery units with diesel engines are well documented. Two of those are: significantly less tube fouling and heat transfer coefficient four to five time higher than that of conventional shell and tube heat exchangers. The high concentration of soot in the exhaust gases of diesel engines make fouling a major concern in design of any kind of heat recovery unit. In the experiment a conventional fluidized bed heat exchanger was connected to the exhaust of a diesel engine mounted on a dynamometer. With this arrangement it was possible to test the heat recovery unit under a wide range of operating conditions. The main objective of this experiment was the determination of the performance characteristics of the heat recovery unit, especially with reference to its heat transfer and fouling characteristics. (author)

Method of controlling weld chamber purge and cover gas atmosphere

International Nuclear Information System (INIS)

Yeo, D.

1992-01-01

A method of controlling the gas atmosphere in a welding chamber includes detecting the absence of a fuel rod from the welding chamber and, in response thereto, initiating the supplying of a flow of argon gas to the chamber to purge air therefrom. Further, the method includes detecting the entry of a fuel rod in the welding chamber and, in response thereto, terminating the supplying of the flow of argon gas to the chamber and initiating the supplying of a flow of helium gas to the chamber to purge argon gas therefrom and displace the argon gas in the chamber. Also, the method includes detecting the withdrawal of the fuel rod from the welding chamber and, in response thereto, terminating the supplying of the flow of helium gas to the chamber and initiating the supplying of argon to the chamber to purge the air therefrom. The method also includes detecting the initiation of a weld cycle and, in response thereto, momentarily supplying a flow of argon gas to the welding electrode tip for initiating the welding arc. (Author)

Catalytic membrane reactor for tritium extraction system from He purge

International Nuclear Information System (INIS)

Santucci, Alessia; Incelli, Marco; Sansovini, Mirko; Tosti, Silvano

2016-01-01

Highlights: • In the HCBB blanket, the produced tritium is recovered by purging with helium; membrane technologies are able to separate tritium from helium. • The paper presents the results of two experimental campaigns. • In the first, a Pd–Ag diffuser for hydrogen separation is tested at several operating conditions. • In the second, the ability of a Pd–Ag membrane reactor for water decontamination is assessed by performing isotopic swamping and water gas shift reactions. - Abstract: In the Helium Cooled Pebble Bed (HCPB) blanket concept, the produced tritium is recovered purging the breeder with helium at low pressure, thus a tritium extraction system (TES) is foreseen to separate the produced tritium (which contains impurities like water) from the helium gas purge. Several R&D activities are running in parallel to experimentally identify most promising TES technologies: particularly, Pd-based membrane reactors (MR) are under investigation because of their large hydrogen selectivity, continuous operation capability, reliability and compactness. The construction and operation under DEMO relevant conditions (that presently foresee a He purge flow rate of about 10,000 Nm 3 /h and a H 2 /He ratio of 0.1%) of a medium scale MR is scheduled for next year, while presently preliminary experiments on a small scale reactor are performed to identify most suitable operative conditions and catalyst materials. This work presents the results of an experimental campaign carried out on a Pd-based membrane aimed at measuring the capability of this device in separating hydrogen from the helium. Many operative conditions have been investigated by considering different He/H 2 feed flow ratios, several lumen pressures and reactor temperatures. Moreover, the performances of a membrane reactor (composed of a Pd–Ag tube having a wall thickness of about 113 μm, length 500 mm and diameter 10 mm) in processing the water contained in the purge gas have been measured by using

Catalytic membrane reactor for tritium extraction system from He purge

Energy Technology Data Exchange (ETDEWEB)

Santucci, Alessia, E-mail: alessia.santucci@enea.it [ENEA for EUROfusion, Via E. Fermi 45, 00044 Frascati, Roma (Italy); Incelli, Marco [ENEA for EUROfusion, Via E. Fermi 45, 00044 Frascati, Roma (Italy); DEIM, University of Tuscia, Via del Paradiso 47, 01100 Viterbo (Italy); Sansovini, Mirko; Tosti, Silvano [ENEA for EUROfusion, Via E. Fermi 45, 00044 Frascati, Roma (Italy)

2016-11-01

Highlights: • In the HCBB blanket, the produced tritium is recovered by purging with helium; membrane technologies are able to separate tritium from helium. • The paper presents the results of two experimental campaigns. • In the first, a Pd–Ag diffuser for hydrogen separation is tested at several operating conditions. • In the second, the ability of a Pd–Ag membrane reactor for water decontamination is assessed by performing isotopic swamping and water gas shift reactions. - Abstract: In the Helium Cooled Pebble Bed (HCPB) blanket concept, the produced tritium is recovered purging the breeder with helium at low pressure, thus a tritium extraction system (TES) is foreseen to separate the produced tritium (which contains impurities like water) from the helium gas purge. Several R&D activities are running in parallel to experimentally identify most promising TES technologies: particularly, Pd-based membrane reactors (MR) are under investigation because of their large hydrogen selectivity, continuous operation capability, reliability and compactness. The construction and operation under DEMO relevant conditions (that presently foresee a He purge flow rate of about 10,000 Nm{sup 3}/h and a H{sub 2}/He ratio of 0.1%) of a medium scale MR is scheduled for next year, while presently preliminary experiments on a small scale reactor are performed to identify most suitable operative conditions and catalyst materials. This work presents the results of an experimental campaign carried out on a Pd-based membrane aimed at measuring the capability of this device in separating hydrogen from the helium. Many operative conditions have been investigated by considering different He/H{sub 2} feed flow ratios, several lumen pressures and reactor temperatures. Moreover, the performances of a membrane reactor (composed of a Pd–Ag tube having a wall thickness of about 113 μm, length 500 mm and diameter 10 mm) in processing the water contained in the purge gas have been

Purging sensitive science instruments with nitrogen in the STS environment

Science.gov (United States)

Lumsden, J. M.; Noel, M. B.

1983-01-01

Potential contamination of extremely sensitive science instruments during prelaunch, launch, and earth orbit operations are a major concern to the Galileo and International Solar Polar Mission (ISPM) Programs. The Galileo Program is developing a system to purify Shuttle supplied nitrogen gas for in-flight purging of seven imaging and non-imaging science instruments. Monolayers of contamination deposited on critical surfaces can degrade some instrument sensitivities as much as fifty percent. The purging system provides a reliable supply of filtered and fried nitrogen gas during these critical phases of the mission when the contamination potential is highest. The Galileo and ISPM Programs are including the system as Airborne Support Equipment (ASE).

Airflow and Heat Transfer in the Slot-Vented Room with Radiant Floor Heating Unit

Directory of Open Access Journals (Sweden)

Xiang-Long Liu

2012-01-01

Full Text Available Radiant floor heating has received increasing attention due to its diverse advantages, especially the energy saving as compared to the conventional dwelling heating system. This paper presents a numerical investigation of airflow and heat transfer in the slot-vented room with the radiant floor heating unit. Combination of fluid convection and thermal radiation has been implemented through the thermal boundary conditions. Spatial distributions of indoor air temperature and velocity, as well as the heat transfer rates along the radiant floor and the outer wall, have been presented and analyzed covering the domains from complete natural convection to forced convection dominated flows. The numerical results demonstrate that the levels of average temperature in the room with lateral slot-ventilation are higher than those without slot-ventilation, but lower than those in the room with ceiling slot-ventilation. Overall, the slot-ventilation room with radiant floor heating unit could offer better indoor air quality through increasing the indoor air temperature and fresh air exchanging rate simultaneously. Concerning the airborne pollutant transports and moisture condensations, the performance of radiant floor heating unit will be further optimized in our future researches.

Disturbance of gut satiety peptide in purging disorder.

Science.gov (United States)

Keel, Pamela K; Eckel, Lisa A; Hildebrandt, Britny A; Haedt-Matt, Alissa A; Appelbaum, Jonathan; Jimerson, David C

2018-01-01

Little is known about biological factors that contribute to purging after normal amounts of food-the central feature of purging disorder (PD). This study comes from a series of nested studies examining ingestive behaviors in bulimic syndromes and specifically evaluated the satiety peptide YY (PYY) and the hunger peptide ghrelin in women with PD (n = 25), bulimia nervosa-purging (BNp) (n = 26), and controls (n = 26). Based on distinct subjective responses to a fixed meal in PD (Keel, Wolfe, Liddle, DeYoung, & Jimerson, ), we tested whether postprandial PYY response was significantly greater and ghrelin levels significantly lower in women with PD compared to controls and women with BNp. Participants completed structured clinical interviews, self-report questionnaires, and laboratory assessments of gut peptide and subjective responses to a fixed meal. Women with PD demonstrated a significantly greater postprandial PYY response compared to women with BNp and controls, who did not differ significantly. PD women also endorsed significantly greater gastrointestinal distress, and PYY predicted gastrointestinal intestinal distress. Ghrelin levels were significantly greater in PD and BNp compared to controls, but did not differ significantly between eating disorders. Women with BNp endorsed significantly greater postprandial hunger, and ghrelin predicted hunger. PD is associated with a unique disturbance in PYY response. Findings contribute to growing evidence of physiological distinctions between PD and BNp. Future research should examine whether these distinctions account for differences in clinical presentation as this could inform the development of specific interventions for patients with PD. © 2017 Wiley Periodicals, Inc.

Driven exercise in the absence of binge eating: Implications for purging disorder.

Science.gov (United States)

Lydecker, Janet A; Shea, Megan; Grilo, Carlos M

2018-02-01

Purging disorder (PD) is characterized by recurrent purging without objectively large binge-eating episodes. PD has received relatively little attention, and questions remain about the clinical significance of "purging" by exercise that is driven or compulsive (i.e., as extreme compensatory or weight-control behavior). The little available research suggests that individuals who use exercise as a compensatory behavior might have less eating-disorder psychopathology than those who purge by vomiting or laxatives, but those studies have had smaller sample sizes, defined PD using low-frequency thresholds, and defined exercise without weight-compensatory or driven elements. Participants (N = 2,017) completed a web-based survey with established measures of eating-disorder psychopathology, depression, and physical activity. Participants were categorized (regular compensatory driven exercise, PD-E, n = 297; regular compensatory vomiting/laxatives, PD-VL, n = 59; broadly defined anorexia nervosa, AN, n = 20; and no eating-disordered behaviors, NED, n = 1,658) and compared. PD-E, PD-VL, and AN had higher eating-disorder psychopathology and physical activity than NED but did not significantly differ from each other on most domains. PD-VL and AN had higher depression than PD-E, which was higher than NED. Findings suggest that among participants with regularly compensatory behaviors without binge eating, those who use exercise alone have similar levels of associated eating-disorder psychopathology as those who use vomiting/laxatives, although they have lower depression levels and overall frequency of purging. Findings provide further support for the clinical significance of PD. Clinicians and researchers should recognize the severity of driven exercise as a compensatory behavior, and the need for further epidemiological and treatment research. © 2017 Wiley Periodicals, Inc.

Consumer Unit for Low Energy District Heating Net

DEFF Research Database (Denmark)

Paulsen, Otto; Fan, Jianhua; Furbo, Simon

2008-01-01

to reduce heat loss in the network. The consumer’s installation is a unit type with an accumulation tank for smoothing the heat load related to the domestic hot water. The building heat load is delivered by an under-floor heating system. The heavy under-floor heating system is assumed to smooth the room...... heat load on a daily basis, having a flow temperature control based on outdoor climate. The unit is designed for a near constant district heating water flow. The paper describes two concepts. The analyses are based on TRNSYS (Klein et al., 2006) simulation, supplied with laboratory verification......A low energy/ low temperature consumer installation is designed and analyzed. The consumer type is a low energy single family house 145 m2 with annual energy consumption in the range of 7000 kWh, incl. domestic hot water in a 2800 degree day climate. The network is an extreme low temperature system...

Cold Vacuum Drying (CVD) Facility Vacuum Purge System Chilled Water System Design Description. System 47-4

International Nuclear Information System (INIS)

IRWIN, J.J.

2000-01-01

This system design description (SDD) addresses the Vacuum Purge System Chilled Water (VPSCHW) system. The discussion that follows is limited to the VPSCHW system and its interfaces with associated systems. The reader's attention is directed to Drawings H-1-82162, Cold Vacuum Drying Facility Process Equipment Skid PandID Vacuum System, and H-1-82224, Cold Vacuum Drying Facility Mechanical Utilities Process Chilled Water PandID. Figure 1-1 shows the location and equipment arrangement for the VPSCHW system. The VPSCHW system provides chilled water to the Vacuum Purge System (VPS). The chilled water provides the ability to condense water from the multi-canister overpack (MCO) outlet gases during the MCO vacuum and purge cycles. By condensing water from the MCO purge gas, the VPS can assist in drying the contents of the MCO

Computer aided heat transfer analysis in a laboratory scaled heat exchanger unit

International Nuclear Information System (INIS)

Gunes, M.

1998-01-01

In this study. an explanation of a laboratory scaled heat exchanger unit and a software which is developed to analyze heat transfer. especially to use it in heat transfer courses, are represented. Analyses carried out in the software through sample values measured in the heat exchanger are: (l) Determination of heat transfer rate, logarithmic mean temperature difference and overall heat transfer coefficient; (2)Determination of convection heat transfer coefficient inside and outside the tube and the effect of fluid velocity on these; (3)Investigation of the relationship between Nusselt Number. Reynolds Number and Prandtl Number by using multiple non-linear regression analysis. Results are displayed on the screen graphically

Appetite Regulatory Hormones in Women With Anorexia Nervosa: Binge-Eating/Purging Versus Restricting Type

Science.gov (United States)

Eddy, Kamryn T.; Lawson, Elizabeth A.; Meade, Christina; Meenaghan, Erinne; Horton, Sarah E.; Misra, Madhusmita; Klibanski, Anne; Miller, Karen K.

2015-01-01

Objective Anorexia nervosa is a psychiatric illness characterized by low weight, disordered eating, and hallmark neuroendocrine dysfunction. Behavioral phenotypes are defined by predominant restriction or bingeing/purging; binge-eating/purging type anorexia nervosa is associated with poorer outcome. The pathophysiology underlying anorexia nervosa types is unknown, but altered hormones, known to be involved in eating behaviors, may play a role. Method To examine the role of anorexigenic hormones in anorexia nervosa subtypes, we examined serum levels of peptide YY (PYY; total and active [3-36] forms), brain-derived neurotrophic factor (BDNF), and leptin as primary outcomes in women with OSM-5 restricting type anorexia nervosa (n=50), binge-eating/purging type anorexia nervosa (n = 22), and healthy controls (n = 22).1n addition, women completed validated secondary outcome measures of eating disorder psychopathology (Eating Disorder Examination-Questionnaire) and depression and anxiety symptoms (Hamilton Rating Scales for Depression [HDRS] and Anxiety [HARS]). The study samples were collected from May 22, 2004, to February 7, 2012. Results Mean PYY 3-36 and leptin levels were lower and BDNF levels higher in binge-eating/purging type anorexia nervosa than in restricting type anorexia nervosa (all Pvalues anorexia nervosa types were significant (Panorexia nervosa, the anorexigenic hormones PYY, BDNF, and leptin are differentially regulated between the restricting and binge/purge types. Whether these hormone pathways play etiologic roles with regard to anorexia nervosa behavioral types or are compensatory merits further study. PMID:25098834

Purge Procedures and Leak Testing for the Morgan Breathing System (MBS) 2000 Closed-Circuit Oxygen Rebreather

National Research Council Canada - National Science Library

Fothergill, David

2005-01-01

.... Since purging accounts for most of the O2 used when breathing on the MBS 2000, optimizing the purge procedure will maximize the duration of the O2 supply and minimize oxygen leaks into the chamber atmosphere...

The dynamic behavior of pressure during purge process in the anode of a PEM fuel cell

Energy Technology Data Exchange (ETDEWEB)

Gou, Jun; Pei, Pucheng; Wang, Ying [State Key Laboratory of Automotive Safety and Energy, Tsinghua University, Beijing 100084 (China)

2006-11-22

A one-dimensional mathematic computational fluid dynamics model of a proton exchange membrane (PEM) fuel cell is presented in this paper to simulate the transient behavior of hydrogen pressure in the flow field during a typical dynamic process-the purge process. This model accounts for the mechanism of pressure wave transmission in the channels by employing the characteristic line method. A unique parameter-pressure swing, which represents the top value of pressure variation at certain point in the channel during the purge process, is brought up and studied as well as the pressure drop. The pressure distribution along the channel and the pressure drop during the purge process for different operating pressures, lengths of purge time, stoichiometric ratios and current densities are studied. The results indicate that the distributed pressure, pressure drop and pressure swing all increase with the increment of operating pressure. With a high operating pressure a second-falling stage can be seen in the pressure drop profile while with a relatively low operating pressure, a homogeneous distribution of pressure swing can be attained. A long purge time will provide enough time to show the whole part of the pressure drop curve, while only a part of the curve can be attained if a short purge time is adopted, but a relatively uniform distribution of pressure swing will show up at the moment. Compared with the condition of stoichiometric ratio 1, the pressure drop curve decreases more sharply after the top value and the pressure swing displays a more uniform distribution when the ratio is set beyond 1. Different current densities have no apparent influence on the pressure drop and the pressure swing during this transient process. All the distribution rules of related parameters deducted from this study will be helpful for optimizing the purging strategies on vehicles. (author)

Comparison of dialysis membrane diffusion samplers and two purging methods in bedrock wells

Science.gov (United States)

Imbrigiotta, T.E.; Ehlke, T.A.; Lacombe, P.J.; Dale, J.M.; ,

2002-01-01

Collection of ground-water samples from bedrock wells using low-flow purging techniques is problematic because of the random spacing, variable hydraulic conductivity, and variable contamination of contributing fractures in each well's open interval. To test alternatives to this purging method, a field comparison of three ground-water-sampling techniques was conducted on wells in fractured bedrock at a site contaminated primarily with volatile organic compounds. Constituent concentrations in samples collected with a diffusion sampler constructed from dialysis membrane material were compared to those in samples collected from the same wells with a standard low-flow purging technique and a hybrid (high-flow/low-flow) purging technique. Concentrations of trichloroethene, cis-1,2-dichloroethene, vinyl chloride, calcium, chloride, and alkalinity agreed well among samples collected with all three techniques in 9 of the 10 wells tested. Iron concentrations varied more than those of the other parameters, but their pattern of variation was not consistent. Overall, the results of nonparametric analysis of variance testing on the nine wells sampled twice showed no statistically significant difference at the 95-percent confidence level among the concentrations of volatile organic compounds or inorganic constituents recovered by use of any of the three sampling techniques.

Human reliability analysis for In-Tank Precipitation alignment and startup of emergency purge ventilation equipment

International Nuclear Information System (INIS)

Olsen, L.M.

1993-08-01

This report documents the methodology used for calculating the human error probability for establishing air based ventilation using emergency purge ventilation equipment on In-Tank Precipitation (ITP) processing tanks 48 and 49 after a failure of the nitrogen purge system following a seismic event. The analyses were performed according to THERP (Technique for Human Error Rate Prediction). The calculated human error probabilities are provided as input to the Fault Tree Analysis for the ITP Nitrogen Purge System. The analysis assumes a seismic event initiator leading to establishing air based ventilation on the ITP processing tanks 48 and 49. At the time of this analysis only the tanks and the emergency purge ventilation equipment are seismically qualified. Consequently, onsite and offsite power is assumed to be unavailable and all operator control actions are to be performed locally on the tank top. Assumptions regarding procedures, staffing, equipment locations, equipment tagging, equipment availability, and training were made and are documented in this report. The human error probability for establishing air based ventilation using the emergency purge ventilation equipment on In-Tank Precipitation processing tanks 48 and 49 after a failure of the nitrogen purge system following a seismic event is 4.2E-6 (median value on the lognormal scale). It is important to note that this result is predicated on the implementation of all of the assumptions listed in the ''Assumptions'' section of this report. This analysis was not based on the current conditions in ITP. The analysis is to be used as a tool to aid ITP operations personnel in achieving the training, procedural, and operational goals outlined in this document

N2 vs H20 as purge/hydrostatic head

International Nuclear Information System (INIS)

Mast, J.C.

1996-01-01

This document provides the information to explain to the customer the ETP for the N2 vs H20 as Purge/Hydrostatic Head. This ETP follows the format described in Issurance of New Characterization Equipment Engineering Desk Instructions, 75200-95-013

Low Temperature District Heating Consumer Unit with Micro Heat Pump for Domestic Hot Water Preparation

DEFF Research Database (Denmark)

Zvingilaite, Erika; Ommen, Torben Schmidt; Elmegaard, Brian

2012-01-01

In this paper we present and analyse the feasibility of a district heating (DH) consumer unit with micro heat pump for domestic hot water (DHW) preparation in a low temperature (40 °C) DH network. We propose a micro booster heat pump of high efficiency (COP equal to 5,3) in a consumer DH unit...... in order to boost the temperature of the district heating water for heating the DHW. The paper presents the main designs of the suggested system and different alternative micro booster heat pump concepts. Energy efficiency and thermodynamic performance of these concepts are calculated and compared....... The results show that the proposed system has the highest efficiency. Furthermore, we compare thermodynamic and economic performance of the suggested heat pump-based concept with different solutions, using electric water heater. The micro booster heat pump system has the highest annualised investment (390 EUR...

Better Fitness in Captive Cuvier's Gazelle despite Inbreeding Increase: Evidence of Purging?

Directory of Open Access Journals (Sweden)

Eulalia Moreno

Full Text Available Captive breeding of endangered species often aims at preserving genetic diversity and to avoid the harmful effects of inbreeding. However, deleterious alleles causing inbreeding depression can be purged when inbreeding persists over several generations. Despite its great importance both for evolutionary biology and for captive breeding programmes, few studies have addressed whether and to which extent purging may occur. Here we undertake a longitudinal study with the largest captive population of Cuvier's gazelle managed under a European Endangered Species Programme since 1975. Previous results in this population have shown that highly inbred mothers tend to produce more daughters, and this fact was used in 2006 to reach a more appropriate sex-ratio in this polygynous species by changing the pairing strategy (i.e., pairing some inbred females instead of keeping them as surplus individuals in the population. Here, by using studbook data we explore whether purging has occurred in the population by investigating whether after the change in pairing strategy a inbreeding and homozygosity increased at the population level, b fitness (survival increased, and c the relationship between inbreeding and juvenile survival, was positive. Consistent with the existence of purging, we found an increase in inbreeding coefficients, homozygosity and juvenile survival. In addition, we showed that in the course of the breeding programme the relationship between inbreeding and juvenile survival was not uniform but rather changed over time: it was negative in the early years, flat in the middle years and positive after the change in pairing strategy. We highlight that by allowing inbred individuals to mate in captive stocks we may favour sex-ratio bias towards females, a desirable managing strategy to reduce the surplus of males that force most zoos to use ethical culling and euthanizing management tools. We discuss these possibilities but also acknowledge that many

Evaluation of the Validity of Groundwater Samples Obtained Using the Purge Water Management System at SRS

International Nuclear Information System (INIS)

Beardsley, C.C.

1999-01-01

As part of the demonstration testing of the Purge Water Management System (PWMS) technology at the Savannah River Site (SRS), four wells were equipped with PWMS units in 1997 and a series of sampling events were conducted at each during 1997-1998. Three of the wells were located in A/M Area while the fourth was located at the Old Radioactive Waste Burial Ground in the General Separations Area.The PWMS is a ''closed-loop'', non-contact, system used to collect and return purge water to the originating aquifer after a sampling event without having significantly altered the water quality. One of the primary concerns as to its applicability at SRS, and elsewhere, is whether the PWMS might resample groundwater that is returned to the aquifer during the previous sampling event. The purpose of the present investigation was to compare groundwater chemical analysis data collected at the four test wells using the PWMS vs. historical data collected using the standard monitoring program methodology to determine if the PWMS provides representative monitoring samples.The analysis of the groundwater chemical concentrations indicates that the PWMS sampling methodology acquired representative groundwater samples at monitoring wells ABP-1A, ABP-4, ARP-3 and BGO-33C. Representative groundwater samples are achieved if the PWMS does not resample groundwater that has been purged and returned during a previous sampling event. Initial screening calculations, conducted prior to the selection of these four wells, indicated that groundwater velocities were high enough under the ambient hydraulic gradients to preclude resampling from occurring at the time intervals that were used at each well. Corroborating evidence included a tracer test that was conducted at BGO-33C, the high degree of similarity between analyte concentrations derived from the PWMS samples and those obtained from historical protocol sampling, as well as the fact that PWMS data extend all previously existing concentration

The role of heat pipes in intensified unit operations

International Nuclear Information System (INIS)

Reay, David; Harvey, Adam

2013-01-01

Heat pipes are heat transfer devices that rely, most commonly, on the evaporation and condensation of a working fluid contained within them, with passive pumping of the condensate back to the evaporator. They are sometimes referred to as ‘thermal superconductors’ because of their exceptionally high effective thermal conductivity (substantially higher than any metal). This, together with several other characteristics make them attractive to a range of intensified unit operations, particularly reactors. The majority of modern computers deploy heat pipes for cooling of the CPU. The application areas of heat pipes come within a number of broad groups, each of which describes a property of the heat pipe. The ones particularly relevant to chemical reactors are: i. Separation of heat source and sink. ii. Temperature flattening, or isothermalisation. iii. Temperature control. Chemical reactors, as a heat pipe application area, highlight the benefits of the heat pipe based on isothermalisation/temperature flattening device and on being a highly effective heat transfer unit. Temperature control, done passively, is also of relevance. Heat pipe technology offers a number of potential benefits to reactor performance and operation. The aim of increased yield of high purity, high added value chemicals means less waste and higher profitability. Other intensified unit operations, such as those employing sorption processes, can also profit from heat pipe technology. This paper describes several variants of heat pipe and the opportunities for their use in intensified plant, and will give some current examples. -- Highlights: ► Heat pipes – thermal superconductors – can lead to improved chemical reactor performance. ► Isothermalisation within a reactor vessel is an ideal application. ► The variable conductance heat pipe can control reaction temperatures within close limits. ► Heat pipes can be beneficial in intensified reactors

Computational fluid dynamic simulation of pressurizer safety valve loop seal purge phenomena in nuclear power plants

International Nuclear Information System (INIS)

Park, Jong Woon

2012-01-01

In Korean 3 Loop plants a water loop seal pipe is installed containing condensed water upstream of a pressurizer safety valve to protect the valve disk from the hot steam environment. The loop seal water purge time is a key parameter in safety analyses for overpressure transients, because it delays valve opening. The loop seal purge time is uncertain to measure by test and thus 3-dimensional realistic computational fluid dynamics (CFD) model is developed in this paper to predict the seal water purge time before full opening of the valve which is driven by steam after water purge. The CFD model for a typical pressurizer safety valve with a loop seal pipe is developed using the computer code of ANSYS CFX 11. Steady-state simulations are performed for full discharge of steam at the valve full opening. Transient simulations are performed for the loop seal dynamics and to estimate the loop seal purge time. A sudden pressure drop higher than 2,000 psia at the tip of the upper nozzle ring is expected from the steady-state calculation. Through the transient simulation, almost loop seal water is discharged within 1.2 second through the narrow opening between the disk and the nozzle of the valve. It can be expected that the valve fully opens at least before 1.2 second because constant valve opening is assumed in this CFX simulation, which is conservative because the valve opens fully before the loop seal water is completely discharged. The predicted loop seal purge time is compared with previous correlation. (orig.)

Computational fluid dynamic simulation of pressurizer safety valve loop seal purge phenomena in nuclear power plants

Energy Technology Data Exchange (ETDEWEB)

Park, Jong Woon [Dongguk Univ., Gyeongju (Korea, Republic of). Nuclear and Energy Engineering Dept.

2012-11-15

In Korean 3 Loop plants a water loop seal pipe is installed containing condensed water upstream of a pressurizer safety valve to protect the valve disk from the hot steam environment. The loop seal water purge time is a key parameter in safety analyses for overpressure transients, because it delays valve opening. The loop seal purge time is uncertain to measure by test and thus 3-dimensional realistic computational fluid dynamics (CFD) model is developed in this paper to predict the seal water purge time before full opening of the valve which is driven by steam after water purge. The CFD model for a typical pressurizer safety valve with a loop seal pipe is developed using the computer code of ANSYS CFX 11. Steady-state simulations are performed for full discharge of steam at the valve full opening. Transient simulations are performed for the loop seal dynamics and to estimate the loop seal purge time. A sudden pressure drop higher than 2,000 psia at the tip of the upper nozzle ring is expected from the steady-state calculation. Through the transient simulation, almost loop seal water is discharged within 1.2 second through the narrow opening between the disk and the nozzle of the valve. It can be expected that the valve fully opens at least before 1.2 second because constant valve opening is assumed in this CFX simulation, which is conservative because the valve opens fully before the loop seal water is completely discharged. The predicted loop seal purge time is compared with previous correlation. (orig.)

Effect of the purging gas on properties of Ti stabilized AISI 321 stainless steel TIG welds

Energy Technology Data Exchange (ETDEWEB)

Taban, Emel; Kaluc, Erdinc; Aykan, T. Serkan [Kocaeli Univ. (Turkey). Dept. of Mechanical Engineering

2014-07-01

Gas purging is necessary to provide a high quality of stainless steel pipe welding in order to prevent oxidation of the weld zone inside the pipe. AISI 321 stabilized austenitic stainless steel pipes commonly preferred in refinery applications have been welded by the TIG welding process both with and without the use of purging gas. As purging gases, Ar, N{sub 2}, Ar + N{sub 2} and N{sub 2} + 10% H{sub 2} were used, respectively. The aim of this investigation is to detect the effect of purging gas on the weld joint properties such as microstructure, corrosion, strength and impact toughness. Macro sections and microstructures of the welds were investigated. Chemical composition analysis to obtain the nitrogen, oxygen and hydrogen content of the weld root was done by Leco analysis. Ferrite content of the beads including root and cap passes were measured by a ferritscope. Vickers hardness (HV10) values were obtained. Intergranular and pitting corrosion tests were applied to determine the corrosion resistance of all welds. Type of the purging gas affected pitting corrosion properties as well as the ferrite content and nitrogen, oxygen and hydrogen contents at the roots of the welds. Any hot cracking problems are not predicted as the weld still solidifies with ferrite in the primary phase as confirmed by microstructural and ferrite content analysis. Mechanical testing showed no significant change according to the purge gas. AISI 321 steel and 347 consumable compositions would permit use of nitrogen rich gases for root shielding without a risk of hot cracking.

Characterization of heat emission of light-curing units.

Science.gov (United States)

Wahbi, Mohammed A; Aalam, F A; Fatiny, F I; Radwan, S A; Eshan, I Y; Al-Samadani, K H

2012-04-01

This study was designed to analyze the heat emissions produced by light-curing units (LCUs) of different intensities during their operation. The null hypothesis was that the tested LCUs would show no differences in their temperature rises. FIVE COMMERCIALLY AVAILABLE LCUS WERE TESTED: a "Flipo" plasma arc, "Cromalux 100" quartz-tungsten-halogen, "L.E. Demetron 1" second-generation light-emitting diode (LED), and "Blue Phase C5" and "UltraLume 5" third-generation LED LCUs. The intensity of each LCU was measured with two radiometers. The temperature rise due to illumination was registered with a type-K thermocouple, which was connected to a computer-based data acquisition system. Temperature changes were recorded in continues 10 and 20 s intervals up to 300 s. The Flipo (ARC) light source revealed the highest mean heat emission while the L.E. Demetron 1 LED showing the lowest mean value at 10 and 20 s exposure times. Moreover, Cromalux (QTH) recorded the second highest value for all intervals (12.71, 14.63, 14.60) of heat emission than Blue Phase C5 (LED) (12.25, 13.87, 13.69), interestingly at 20 s illumination for all intervals the highest results (18.15, 19.27, 20.31) were also recorded with Flipo (PAC) LCU, and the lowest (6.71, 5.97, 5.55) with L.E. Demetron 1 LED, while Blue Phase C5 (LED) recorded the second highest value at the 1st and 2nd 20 s intervals (14.12, 11.84, 10.18) of heat emission than Cromalux (QTH) (12.26, 11.43, 10.26). The speed of temperature or heat rise during the 10 and 20 s depends on light intensity of emitted light. However, the QTH LCU was investigated resulted in a higher temperature rise than LED curing units of the same power density. The PAC curing unit induced a significantly higher heat emission and temperature increase in all periods, and data were statistically different than the other tested groups (p < .05). LED (Blue Phase C5) was not statistically significant (p < .05) (at 10 s) than QTH units, also LED (Blue

Human Reliability Analysis for In-Tank Precipitation Alignment and Startup of Emergency Purge Ventilation Equipment. Revision 3

International Nuclear Information System (INIS)

Shapiro, B.J.; Britt, T.E.

1994-10-01

This report documents the methodology used for calculating the human error probability for establishing air based ventilation using emergency purge ventilation equipment on In-Tank Precipitation (ITP) processing tanks 48 and 49 after failure of the nitrogen purge system following a seismic event. The analyses were performed according to THERP (Technique for Human Error Rate Prediction) as described in NUREG/CR-1278-F, ''Handbook of Human Reliability Analysis with Emphasis on Nuclear Power Plant Applications.'' The calculated human error probabilities are provided as input to the Fault Tree Analysis for the ITP Nitrogen Purge System

Experimental Evaluation of a Total Heat Recovery Unit with Polymer Membrane Foils

DEFF Research Database (Denmark)

Fang, Lei; Yuan, Shu; Nie, Jinzhe

2014-01-01

A laboratory experimental study was conducted to investigate the energy performance of a total heat recovery unit using a polymer membranes heat exchanger. The study was conducted in twin climate chambers. One of the chambers simulated outdoor climate conditions and the other simulated the climate...... condition indoors. The airflows taken from the two chambers were connected into the total heat recovery unit and exchange heat in a polymer membrane foil heat exchanger installed inside the unit. The temperature and humidity of the air upstream and downstream of the heat exchanger were measured. Based...... on the measured temperature and humidity values, the temperature, humidity, and enthalpy efficiencies of the total heat recovery unit were calculated. The experiment was conducted in different combinations of outdoor climate conditions simulating warm and humid outdoor climates and air-conditioned indoor climate...

The Role of Non-Suicidal Self-Injury and Binge-Eating/Purging Behaviours in Family Functioning in Eating Disorders.

Science.gov (United States)

Depestele, Lies; Claes, Laurence; Dierckx, Eva; Baetens, Imke; Schoevaerts, Katrien; Lemmens, Gilbert M D

2015-09-01

This study aimed to investigate family functioning of restrictive and binge-eating/purging eating disordered adolescents with or without non-suicidal self-injury (NSSI), as perceived by the patients and their parents (mothers and fathers). In total, 123 patients (between 14 and 24 years), 98 mothers and 79 fathers completed the Family Assessment Device. Patients completed the Self-Injury Questionnaire-Treatment Related and the Symptom Checklist 90-Revised. No main effects were found of restrictive versus binge-eating/purging behaviour nor of presence/absence of NSSI. For the parents, a significant interaction between binge-eating/purging behaviour and NSSI emerged: Mothers and fathers reported worse family functioning in the binge-eating/purging group in presence of NSSI, whereas mothers reported worse family functioning in the restrictive group without NSSI. Parental perception of family functioning is affected by the combined presence of binge-eating/purging behaviour and NSSI. This finding should be taken into account when treating families living with eating disorders. Copyright © 2015 John Wiley & Sons, Ltd and Eating Disorders Association.

Autologous bone marrow purging with LAK cells.

Science.gov (United States)

Giuliodori, L; Moretti, L; Stramigioli, S; Luchetti, F; Annibali, G M; Baldi, A

1993-12-01

In this study we will demonstrate that LAK cells, in vitro, can lyse hematologic neoplastic cells with a minor toxicity of the staminal autologous marrow cells. In fact, after bone marrow and LAK co-culture at a ratio of 1/1 for 8 hours, the inhibition on the GEMM colonies resulted to be 20% less compared to the untreated marrow. These data made LAK an inviting agent for marrow purging in autologous bone marrow transplantation.

Radiological Design Summary Report for TRU Vent and Purge Process

International Nuclear Information System (INIS)

Taus, L.B.

2004-01-01

This report contains top-level requirements for the various areas of radiological protection for workers. Detailed quotations of the requirements for applicable regulatory documents can be found in the accompanying Implementation Guide. For the purposes of demonstrating compliance with these requirements, per Engineering Standard 01064, shall consider / shall evaluate indicates that the designer must examine the requirement for the design and either incorporate or provide a technical justification as to why the requirement is not incorporated. The Transuranic Vent and Purge process is not a project, but is considered a process change. This process has been performed successfully by Solid Waste on lower activity TRU drums. This summary report applies a graded approach and describes how the Transuranic Vent and Purge process meets each of the applicable radiological design criteria and requirements specified in Manual WSRC-TM-95-1, Engineering Standard Number 01064

FMECA about pre-treatment system for purge gas of test blanket module in ITER

International Nuclear Information System (INIS)

Fu Wanfa; Luo Deli; Tang Tao

2012-01-01

The pre-treatment system for purge gas of TBM will be installed in Port Cell for installing TBM in ITER, the function of which includes filtering purge gas, removing HTO, cooling, and adjusting flow rate, etc. The purge gas treated will be conveyed into TES (Tritium Extraction System). The technological process and system components in pre-treatment system were introduced. Tritium releasing risk was regarded as failure criterion; failure mode, effects and criticality analysis (FMECA) were carried out and several weaknesses or failure mode in the system were found. Besides, risk priority number (RPN) and failure mode criticality were calculated. Finally, some design improvement measures and usage compensation measures were given. At last, four important potential failure modes were found out. The analysis will provide the design basis for reducing risk of excessive tritium releasing, which is also a useful assist for safety analysis about other tritium system. (authors)

Propellant and Purge System Contamination "2007: A Summer of Fun"

Science.gov (United States)

Galloway, Randy

2010-01-01

This slide presentation reviews the propellant and purge system contamination that occurred during the summer of 2007 at Stennis Space Center. During this period Multiple propellant/pressurant system contamination events prompted a thorough investigation, the results of which are reviewed.

Heating unit of Berovo by co-generation (Macedonia)

International Nuclear Information System (INIS)

Armenski, Slave; Dimitrov, Konstantin; Tashevski, Done

1999-01-01

A plant for combined heat and electric power production, for central heating of the town Berovo (Macedonia) is proposed. The common reason to use a co-generation unit is the energy efficiency and a significant reduction of environmental pollution. The heat consumption of town Berovo is analyzed and determined. Based on the energy consumption of a whole power plant, e. i. the plant for combined and simultaneous production of power is proposed. The quantity of annually heat and electrical production and annually coal consumption are estimated. (Author)

An application of the gas-fired chilling and heating units to domestic houses

Energy Technology Data Exchange (ETDEWEB)

Choi, J.H.; Yang, Y.M.; Chae, J.M.; Bang, H.S.; Kwon, O.B.; Yoo, S.I.; Kim, T.H. [R and D Center, Korea Gas Co. (Korea); Lee, T.W.; Kim, T.H.; Kim, B.H.; Hwang, I.J.; Kim, J.Y.; Kim, C.D.; Park, S.J. [Korea Institute of Construction Technology (Korea)

1999-10-01

Following researches and considerations were performed in this study for an efficient application of gas-fired chilling and heating units to the residential buildings. (1) Status of domestic cooling and heating for residential building. (2) Various introduction schemes of outdoor unit. (3) Design exclusive area for the gas appliance and installation of it. (4) Ventilation of exhaust gas and heat. (5) Prepare the installation specifications or standards for gas-fired chilling and heating units. (6) Design technique of plumbing for cooling and heating. (7) Evaluation of unit's capacity considering the thermal load of domestic buildings. (8) Cooling and heating system with the unit. (9) Fundamental test for evaluation of applicability. (10) Actual design and construction of experimental house for an application and a demonstration of the developed gas units. (11) Field test for cooling and heating. (12) Evaluation of economic efficiency. (13) Establish a business potential. (14) Establishment of legal and systematic support, energy rate. (15) Troubleshooting in the course of development and application of the new gas appliance. 41 refs., 214 figs., 52 tabs.

Analysis of Thermal Design of Heating Units with Meteorological Climate Peculiarities

Science.gov (United States)

Seminenko, A. S.; Elistratova, Y. V.; Pererva, M. I.; Moiseev, M. V.

2018-03-01

This article is devoted to the analysis of thermal design of heating units, one of the compulsory calculations of heating systems, which ensures their stable and efficient operation. The article analyses the option of a single-pipe heating system with shifted end-capping areas and the overhead supply main; the difference is shown in the calculation results between heat balance equation of the heating unit and calculation of the actual heat flux (heat transfer coefficient) taking into account deviation from the standardized (technical passport) operating conditions. The calculation of the thermal conditions of residential premises is given, the deviation of the internal air temperature is shown taking into account the discrepancy between the calculation results for thermal energy.

Evaluation of the Tekmar 3100 Purge and Trap Agilent GC/MSD system for VOC analysis

Energy Technology Data Exchange (ETDEWEB)

Li, K.; Fingas, M.F. [Environment Canada, Ottawa, ON (Canada). Emergencies Science and Technology Div

2004-07-01

This presentation described the Tekmar automated purge and trap (PAT) modular analyzer for detecting and quantifying volatile organic compounds (VOCs) in relatively clean water samples. A large percentage of emergency response work involves VOC analysis under various matrices such as water or soil. PAT analysis is an extraction method in which the VOCs from a liquid sample are purged by helium and concentrated on an internal trap, where the analytes are thermally desorbed into a gas chromatograph or a gas chromatograph/mass spectrometer (GS/MS). This high degree of concentration results in good detection limits. The performance of the Tekmar PAT 31000 concentrator with autosampler and GC/MS system was evaluated using a 1 ppb and 100 ppb standard of the Method 524 mixture for some selected VOC on the list. The study also examined the purging parameters such as time and temperature. It also examined a new way of introducing gaseous samples through the 3-way purge vessel valve on the concentrator. The objective was to determine if the versatility of the system could be extended by using the the same instrument configuration for air sampling. Preliminary results indicate that it is not yet practical to use the system for air sampling. 3 tabs., 4 figs.

Bulimia Nervosa/Purging Disorder.

Science.gov (United States)

Castillo, Marigold; Weiselberg, Eric

2017-04-01

Bulimia nervosa was first described in 1979 by British psychiatrist Gerald Russell as a "chronic phase of anorexia nervosa" in which patients overeat and then use compensatory mechanisms, such as self-induced vomiting, laxatives, or prolonged periods of starvation. The characterization of bulimia nervosa continues to evolve with the introduction of the DSM-5 in 2013. In this article, the epidemiology and risk factors of bulimia nervosa are identified and reviewed, along with the medical complications and psychiatric comorbidities. The evaluation of a patient with suspected bulimia nervosa is addressed, with an emphasis on acquiring a complete and thorough history as well as discovering any comorbidities that are present. Management of the patient involves both medical interventions and behavioral counseling in order to address physical, psychological, and social needs. Lastly, a new diagnosis introduced in the DSM-5, purging disorder, is described and discussed. Copyright © 2017 Mosby, Inc. All rights reserved.

Outdoor unit construction for an electric heat pump

Science.gov (United States)

Draper, R.; Lackey, R.S.

1984-09-11

The outdoor unit for an electric heat pump is provided with an upper portion containing propeller fan means for drawing air through the lower portion containing refrigerant coil means in the form of four discrete coils connected together in a subassembly forming a W shape, the unit being provided with four adjustable legs which are retracted in shipment, and are adjusted on site to elevate the unit to a particular height suitable for the particular location in which the unit is installed. 4 figs.

Colonic diverticular bleeding: urgent colonoscopy without purging and endoscopic treatment with epinephrine and hemoclips

Directory of Open Access Journals (Sweden)

Ignacio Couto-Worner

2013-09-01

Full Text Available Diverticular disease is the most frequent cause of lower gastrointestinal bleeding. Most of the times, bleeding stops without any intervention but in 10-20 % of the cases it is necessary to treat the hemorrhage. Several modalities of endoscopic treatment have been described after purging the colon. We present five cases of severe diverticular bleeding treated with injection of epinephrine and hemoclips. All the colonoscopies were performed without purging of the colon in an emergency setting, with correct visualization of the point of bleeding. Patients recovered well avoiding other aggressive procedures such as angiography or surgery.

Fermentative hydrogen production in a system using anaerobic digester sludge without heat-treatment as a biomass source

Energy Technology Data Exchange (ETDEWEB)

Shizas, I.; Bagley, D.M. [Toronto Univ., Toronto, ON (Canada). Dept. of Civil Engineering

2004-07-01

A study at a Canadian waste treatment plant showed that raw sewage entering had nine times the energy content needed to run the plant. Therefore plants such as these could potentially become net energy producers. A common practice in laboratory-scale demonstration units is to use heat treatments to kill methanogens that consume hydrogen and retain only spore-forming fermentative bacteria. This heat treatment is energy intensive and therefore would be best omitted from a large-scale operation. Also, methanogens seem to be ubiquitous and it may not be possible to prevent their reintroduction in a commercial set up. This paper reports on studies to see if methanogens can be kept to an acceptable level by control of pH and by keeping the solids retention time down to about ten hours. When fed glucose the reactor initially had a productivity of approximately 7.9 per cent. After purging with carbon dioxide and nitrogen gas, productivity increased to more than 20 per cent on the first day. Hydrogenotrophic methanogens then established themselves in the reactor, reducing hydrogen productivity during the second non-purged phase by 80 per cent. The methods examined did not eliminate hydrogen-consuming methanogens for longer than a week, and thus it was suggested that the matter needs further study. 13 refs., 3 figs.

Human Reliability Analysis for In-Tank Precipitation Alignment and Startup of Emergency Purge Ventilation Equipment. Revision 4

International Nuclear Information System (INIS)

Shapiro, B.J.; Britt, T.E.

1995-06-01

This report documents the methodology used for calculating the human error probability for establishing air based ventilation using emergency purge ventilation equipment on In-Tank Precipitation (ITP) processing tanks 48 and 49 after a failure of the nitrogen purge system following a seismic event. The analyses were performed according to THERP (Technique for Human Error Rate Prediction) as describes in NUREG/CR-1278-F

Major design issues of molten carbonate fuel cell power generation unit

Energy Technology Data Exchange (ETDEWEB)

Chen, T.P.

1996-04-01

In addition to the stack, a fuel cell power generation unit requires fuel desulfurization and reforming, fuel and oxidant preheating, process heat removal, waste heat recovery, steam generation, oxidant supply, power conditioning, water supply and treatment, purge gas supply, instrument air supply, and system control. These support facilities add considerable cost and system complexity. Bechtel, as a system integrator of M-C Power`s molten carbonate fuel cell development team, has spent substantial effort to simplify and minimize these supporting facilities to meet cost and reliability goals for commercialization. Similiar to other fuels cells, MCFC faces design challenge of how to comply with codes and standards, achieve high efficiency and part load performance, and meanwhile minimize utility requirements, weight, plot area, and cost. However, MCFC has several unique design issues due to its high operating temperature, use of molten electrolyte, and the requirement of CO2 recycle.

Sustainability assessment of heat exchanger units for spray dryers

International Nuclear Information System (INIS)

Caglayan, Hasan; Caliskan, Hakan

2017-01-01

In this study, the sustainability assessment is performed to the system known as heat exchanger unit with spray dryer. The five-different dead state temperatures (0-5-10-15-20 °C) are considered. It is found that the heat exchanger has the highest energy efficiency (63.32%), while the overall system has the lowest one (5.56%). So, the combination of the spray dryer with the heat exchanger is more effective. On the other hand, the overall exergy efficiency of the system is lower than the heat exchanger and spray dryer for all of the dead state (environmental) temperatures. The exergy efficiency of the heat exchanger is inversely proportional to the dead state temperature, and the maximum rate is found as 49.65% at 0 °C. Furthermore, the exergy efficiencies of the spray dryer and overall system are directly proportional to the dead state temperatures, and the corresponding maximum rates are found to be 26.41% and 24.32% at 20 °C, respectively. Also, the exergy destruction is directly proportional to the dead state temperatures. The minimum and maximum exergy destruction rates are found at the dead state temperatures of 0 °C and 20 °C, respectively. Furthermore, the most sustainable system is found as the heat exchanger unit. - Highlights: • Thermodynamic analyses of industrial heat exchangers and spray dryers. • Sustainability of heat exchangers for spray dryers. • Dead state temperature effects on exergy efficiencies of heat exchangers and spray dryers.

Investigation of the purging effect on a dead-end anode PEM fuel cell-powered vehicle during segments of a European driving cycle

International Nuclear Information System (INIS)

Gomez, Alberto; Sasmito, Agus P.; Shamim, Tariq

2015-01-01

Highlights: • Experimental study of a dead-end anode PEM fuel cell stack during a driving cycle. • Low purging duration is preferred at high current. • High purging frequency can sustain a better performance over time. • Lower cathode stoichiometry is preferred to minimize the parasitic loads. - Abstract: The dynamic performance of the PEM fuel cell is one of the key factors for successful operation of a fuel cell-powered vehicle. Maintaining fast time response while keeping stable and high stack performance is of importance, especially during acceleration and deceleration. In this paper, we evaluate the transient response of a PEM fuel cell stack with a dead-end anode during segments of a legislated European driving cycle together with the effect of purging factors. The PEM fuel cell stack comprises of 24 cells with a 300 cm"2 active catalyst area and operates at a low hydrogen and air pressure. Humidified air is supplied to the cathode side and the dry hydrogen is fed to the anode. The liquid coolant is circulated to the stack and the radiator to maintain the thermal envelope throughout the stack. The stack performance deterioration over time is prevented by utilizing the purging, which removes the accumulated water and impurities. The effect of purging period, purging duration, coolant flow rate and cathode stoichiometry are examined with regard to the fuel cell’s transient performance during the driving cycle. The results show that a low purging duration may avoid the undesired deceleration at a high current, and a high purging period may sustain a better performance over time. Moreover, the coolant flow rate is found to be an important parameter, which affects the stack temperature–time response of the cooling control and the stack performance, especially at high operating currents.

Implementation of a fully automated process purge-and-trap gas chromatograph at an environmental remediation site

International Nuclear Information System (INIS)

Blair, D.S.; Morrison, D.J.

1997-01-01

The AQUASCAN, a commercially available, fully automated purge-and-trap gas chromatograph from Sentex Systems Inc., was implemented and evaluated as an in-field, automated monitoring system of contaminated groundwater at an active DOE remediation site in Pinellas, FL. Though the AQUASCAN is designed as a stand alone process analytical unit, implementation at this site required additional hardware. The hardware included a sample dilution system and a method for delivering standard solution to the gas chromatograph for automated calibration. As a result of the evaluation the system was determined to be a reliable and accurate instrument. The AQUASCAN reported concentration values for methylene chloride, trichloroethylene, and toluene in the Pinellas ground water were within 20% of reference laboratory values

Kinetic modeling of the purging of activated carbon after short term methyl iodide loading

International Nuclear Information System (INIS)

Friedrich, V.; Lux, I.

1991-01-01

A bimolecular reaction model containing the physico-chemical parameters of the adsorption and desorption was developed earlier to describe the kinetics of methyl iodide retention by activated carbon adsorber. Both theoretical model and experimental investigations postulated constant upstream methyl iodide concentration till the maximum break-through. The work reported here includes the extension of the theoretical model to the general case when the concentration of the challenging gas may change in time. The effect of short term loading followed by purging with air, and an impulse-like increase in upstream gas concentration has been simulated. The case of short term loading and subsequent purging has been experimentally studied to validate the model. The investigations were carried out on non-impregnated activated carbon. A 4 cm deep carbon bed had been challenged by methyl iodide for 30, 90, 120 and 180 min and then purged with air, downstream methyl iodide concentration had been measured continuously. The main characteristics of the observed downstream concentration curves (time and slope of break-through, time and amplitude of maximum values) showed acceptable agreement with those predicted by the model

Experimental investigations on cylindrical latent heat storage units with sodium acetate trihydrate composites utilizing supercooling

DEFF Research Database (Denmark)

Dannemand, Mark; Johansen, Jakob Berg; Kong, Weiqiang

2016-01-01

Latent heat storage units utilizing stable supercooling of sodium acetate trihydrate (SAT) composites were tested in a laboratory. The stainless steel units were 1.5 m high cylinders with internal heat exchangers of tubes with fins. One unit was tested with 116 kg SAT with 6% extra water. Another...... in the thickened phase change material after melting. The heat content in the fully charged state and the heat released after solidification of the supercooled SAT mixtures at ambient temperature was higher for the unit with the thickened SAT mixture. The heat discharged after solidification of the supercooled SAT...

Purging of an air-filled vessel by horizontal injection of steam

Energy Technology Data Exchange (ETDEWEB)

Smith, B.L.; Andreani, M

2000-07-01

Reported here are results from an idealised 2D problem in which cold air is purged from a large vessel by a steam jet. The focus of the study is the prediction of the evolution of the flow regimes resulting from changes in the relative importance of buoyancy and inertia forces, and time histories of the temperature and concentration fields. Global parameters of interest are the mixture concentration at the vessel outlet and the total time taken to purge the air. The Computational Fluid Dynamics (CFD) code CFX-4 has been used to perform calculations for different inlet velocities, covering a range of (densimetric) Froude numbers from Fr=0.8 (buoyancy dominated) to Fr=7.1 (inertia dominated). Animations have been used to help understand the dynamics of the flow transitions, and temperature and concentration histories at specific monitoring points have been compared with coarse-mesh predictions obtained using the containment code GOTHIC. (authors)

Purging of an air-filled vessel by horizontal injection of steam

International Nuclear Information System (INIS)

Smith, B.L.; Andreani, M.

2000-01-01

Reported here are results from an idealised 2D problem in which cold air is purged from a large vessel by a steam jet. The focus of the study is the prediction of the evolution of the flow regimes resulting from changes in the relative importance of buoyancy and inertia forces, and time histories of the temperature and concentration fields. Global parameters of interest are the mixture concentration at the vessel outlet and the total time taken to purge the air. The Computational Fluid Dynamics (CFD) code CFX-4 has been used to perform calculations for different inlet velocities, covering a range of (densimetric) Froude numbers from Fr=0.8 (buoyancy dominated) to Fr=7.1 (inertia dominated). Animations have been used to help understand the dynamics of the flow transitions, and temperature and concentration histories at specific monitoring points have been compared with coarse-mesh predictions obtained using the containment code GOTHIC. (authors)

Alternative Procedure of Heat Integration Tehnique Election between Two Unit Processes to Improve Energy Saving

Science.gov (United States)

Santi, S. S.; Renanto; Altway, A.

2018-01-01

The energy use system in a production process, in this case heat exchangers networks (HENs), is one element that plays a role in the smoothness and sustainability of the industry itself. Optimizing Heat Exchanger Networks (HENs) from process streams can have a major effect on the economic value of an industry as a whole. So the solving of design problems with heat integration becomes an important requirement. In a plant, heat integration can be carried out internally or in combination between process units. However, steps in the determination of suitable heat integration techniques require long calculations and require a long time. In this paper, we propose an alternative step in determining heat integration technique by investigating 6 hypothetical units using Pinch Analysis approach with objective function energy target and total annual cost target. The six hypothetical units consist of units A, B, C, D, E, and F, where each unit has the location of different process streams to the temperature pinch. The result is a potential heat integration (ΔH’) formula that can trim conventional steps from 7 steps to just 3 steps. While the determination of the preferred heat integration technique is to calculate the potential of heat integration (ΔH’) between the hypothetical process units. Completion of calculation using matlab language programming.

Local area water removal analysis of a proton exchange membrane fuel cell under gas purge conditions.

Science.gov (United States)

Lee, Chi-Yuan; Lee, Yu-Ming; Lee, Shuo-Jen

2012-01-01

In this study, local area water content distribution under various gas purging conditions are experimentally analyzed for the first time. The local high frequency resistance (HFR) is measured using novel micro sensors. The results reveal that the liquid water removal rate in a membrane electrode assembly (MEA) is non-uniform. In the under-the-channel area, the removal of liquid water is governed by both convective and diffusive flux of the through-plane drying. Thus, almost all of the liquid water is removed within 30 s of purging with gas. However, liquid water that is stored in the under-the-rib area is not easy to remove during 1 min of gas purging. Therefore, the re-hydration of the membrane by internal diffusive flux is faster than that in the under-the-channel area. Consequently, local fuel starvation and membrane degradation can degrade the performance of a fuel cell that is started from cold.

Lamotrigine use in patients with binge eating and purging, significant affect dysregulation, and poor impulse control.

Science.gov (United States)

Trunko, Mary Ellen; Schwartz, Terry A; Marzola, Enrica; Klein, Angela S; Kaye, Walter H

2014-04-01

Some patients with symptoms of binge eating and purging are successfully treated with specific serotonin reuptake inhibitors (SSRIs), but others experience only partial or no benefit. Significant affect dysregulation and poor impulse control may be characteristics that limit responsiveness. We report on the treatment of five patients with bulimia nervosa (BN), anorexia nervosa-binge/purge type (AN-B/P) or eating disorder not otherwise specified (EDNOS), using the anticonvulsant lamotrigine after inadequate response to SSRIs. Following addition of lamotrigine to an antidepressant in four cases, and switch from an antidepressant to lamotrigine in one case, patients experienced substantial improvement in mood reactivity and instability, impulsive drives and behaviors, and eating-disordered symptoms. These findings raise the possibility that lamotrigine, either as monotherapy or as an augmenting agent to antidepressants, may be useful in patients who binge eat and purge, and have significant affect dysregulation with poor impulse control. Copyright © 2013 Wiley Periodicals, Inc.

The Moderating Role of Purging Behaviour in the Relationship Between Sexual/Physical Abuse and Nonsuicidal Self-Injury in Eating Disorder Patients.

Science.gov (United States)

Gonçalves, Sónia; Machado, Bárbara; Silva, Cátia; Crosby, Ross D; Lavender, Jason M; Cao, Li; Machado, Paulo P P

2016-03-01

This study sought to examine predictors of nonsuicidal self-injury (NSSI) in eating disorder patients and to evaluate the moderating role of purging behaviours in the relationship between a theorised predictor (i.e. sexual/physical abuse) and NSSI. Participants in this study were 177 female patients with eating disorders (age range = 14-38 years) who completed semistructured interviews assessing eating disorder symptoms and eating disorder-related risk factors (e.g. history of sexual and physical abuse, history of NSSI and feelings of fatness). Results revealed that 65 participants (36.7%) reported lifetime engagement in NSSI, and 48 participants (27.1%) reported a history of sexual/physical abuse. Early onset of eating problems, lower BMI, feeling fat, a history of sexual/physical abuse and the presence of purging behaviours were all positively associated with the lifetime occurrence of NSSI. The relationship between sexual/physical abuse before eating disorder onset and lifetime NSSI was moderated by the presence of purging behaviours, such that the relationship was stronger in the absence of purging. These findings are consistent with the notion that purging and NSSI may serve similar functions in eating disorder patients (e.g. emotion regulation), such that the presence of purging may attenuate the strength of the association between sexual/physical abuse history (which is also associated with elevated NSSI risk) and engagement in NSSI behaviours. Copyright © 2015 John Wiley & Sons, Ltd and Eating Disorders Association.

Cardiac Risk and Disordered Eating: Decreased R Wave Amplitude in Women with Bulimia Nervosa and Women with Subclinical Binge/Purge Symptoms.

Science.gov (United States)

Green, Melinda; Rogers, Jennifer; Nguyen, Christine; Blasko, Katherine; Martin, Amanda; Hudson, Dominique; Fernandez-Kong, Kristen; Kaza-Amlak, Zauditu; Thimmesch, Brandon; Thorne, Tyler

2016-11-01

The purpose of the present study was threefold. First, we examined whether women with bulimia nervosa (n = 12) and women with subthreshold binge/purge symptoms (n = 20) showed decreased mean R wave amplitude, an indicator of cardiac risk, on electrocardiograph compared to asymptomatic women (n = 20). Second, we examined whether this marker was pervasive across experimental paradigms, including before and after sympathetic challenge tasks. Third, we investigated behavioural predictors of this marker, including binge frequency and purge frequency assessed by subtype (dietary restriction, excessive exercise, self-induced vomiting, and laxative abuse). Results of a 3 (ED symptom status) × 5 (experimental condition) mixed factorial ANCOVA (covariates: body mass index, age) indicated women with bulimia nervosa and women with subclinical binge/purge symptoms demonstrated significantly reduced mean R wave amplitude compared to asymptomatic women; this effect was pervasive across experimental conditions. Multiple regression analyses showed binge and purge behaviours, most notably laxative abuse as a purge method, predicted decreased R wave amplitude across all experimental conditions. Copyright © 2016 John Wiley & Sons, Ltd and Eating Disorders Association. Copyright © 2016 John Wiley & Sons, Ltd and Eating Disorders Association.

Characterizations of gas purge valves for liquid alignment and gas removal in a microfluidic chip

International Nuclear Information System (INIS)

Chuang, Han-Sheng; Thakur, Raviraj; Wereley, Steven T

2012-01-01

Two polydimethylsiloxane (PDMS) gas purge valves for excessive gas removal in general lab-on-a-chip applications are presented in this paper. Both valves are devised based on a three-layer configuration comprising a top layer for liquid channels, a membrane and a bottom layer for gas channels. The pneumatic valves work as a normal gateway for fluids when the membrane is bulged down (open state) by vacuum or pushed up (closed state) by pressure. In the closed state, the air in front of a liquid can be removed through a small notch or a permeable PDMS membrane by compressing the liquid. The purge valve with a small notch across its valve seat, termed surface-tension (ST) valve, can be operated with pressure under 11.5 kPa. The liquid is mainly retained by the surface tension resulting from the hydrophobic channel walls. In contrast, the purge valve with vacuum-filled grooves adjacent to a liquid channel, termed gas-permeation (GP) valve, can be operated at pressure above 5.5 kPa. Based on the principle of gas permeation, the excessive air can be slowly removed through the vent grooves. Detailed evaluations of both valves in a pneumatically driven microfluidic chip were conducted. Specifically, the purge valves enable users to remove gas and passively align liquids at desired locations without using sensing devices or feedback circuits. Finally, a rapid mixing reaction was successfully performed with the GP valves, showing their practicability as incorporated in a microfluidic chip. (paper)

Analysis and Choice of Optimal Heating Ventilation Air Conditioning System for a Teaching Unit

Directory of Open Access Journals (Sweden)

Marina Verdeş

2007-01-01

Full Text Available Under the conditions of present society in which providing an optimum interior comfort is confronted with the necessity of the energy consumption reduction, solving this problem depends on the factors which contribute to the achievements of this comfort. Modern buildings -- implicitly teaching unit -- may be equipped with installations which have low energy consumption, respective a heating, cooling and ventilating integrated system with heat pumps system which can assure all the required comfort conditions. This paper underlines the necessity to use the heat pump in heating system for a teaching unit, energetic and economic guides and the possibility to increase them when using cooling and heating mixed. The solution of heat pumps for heating of the teaching unit and the energetic and economic advantages of the system is made in study.

Evaluation of heat stress in dry cleaner units:A case study in Qom, Iran

Directory of Open Access Journals (Sweden)

Javad Malakouti

2016-04-01

Full Text Available Background & Aims of the Study: Nowadays, heat stress is one of the most harmful physical agents in workplaces. According to the consequences of heat stress and have no information about it in Qom dry cleaner units, Iran, this study have been designed to evaluate the heat stress among workers of dry cleaner units in Qom province of Iran, in Jul-Aug 2011. Materials & Methods: This cross-sectional study was conducted in 113 units of active dry cleaner units. WBGT (Wet Bulb Globe Temperature index was selected for heat stress evaluation. In order to measure the requisite parameters, WBGT meter made of Casella Company had been used according to ISO 7243. Data had been analyzed according to Occupational Exposure Limits (OELs with SPSS V.16, using analysis of variance, independent T and LSD tests. Results: The average of WBGT index in Qom dry cleaner units of Iran were 28.98±1.64 °C. The average of WBGT index in 66.4% of units was up to 28°C. The average of relative humidity was 42.86%, the average of wet bulb temperature and globe temperature were 25.56°C and 36.72°C, respectively. The findings showed a significant correlation between the average of WBGT index and the standard recommendation level (p<0.0001. In dry cleaner units with less than 10 m2 area, heat stress was higher than other units  significantly (p<0.05. Conclusions: Heat stress in many dry cleaner units in Qom, Iran, was more than recommended OELs. Because of wet bulb and globe temperature in units were high value, the most important measures to heat controls, are technical engineering controls such as  radiation shield, insulation on boilers and modify the cooling systems.

Developing maintenance technologies for FBR's heat exchanger units by advanced laser processing

International Nuclear Information System (INIS)

Nishimura, Akihiko; Shimada, Yukihiro

2011-01-01

Laser processing technologies were developed for the purpose of maintenance of FBR's heat exchanger units. Ultrashort laser processing fabricated fiber Bragg grating sensor for seismic monitoring. Fiber laser welding with a newly developed robot system repair cracks on inner wall of heat exchanger tubes. Safety operation of the heat exchanger units will be improved by the advanced laser processing technologies. These technologies are expected to be applied to the maintenance for the next generation FBRs. (author)

Dynamic performance of a high-temperature PEM (proton exchange membrane) fuel cell – Modelling and fuzzy control of purging process

International Nuclear Information System (INIS)

Zhang, Caizhi; Liu, Zhitao; Zhang, Xiongwen; Chan, Siew Hwa; Wang, Youyi

2016-01-01

To improve fuel utilization of HT-PEMFC (high-temperature proton exchange membrane fuel cell), which normally operates under dead-end mode, with properly periodical purging to flush out the accumulated water vapour in the anode flow-field is necessary, otherwise the performance of HT-PEMFC would drop gradually. In this paper, a semi-empirical dynamic voltage model of HT-PEMFC is developed for controller design purpose via fitting the experimental data and validated with experimental results. Then, a fuzzy controller is designed to schedule the purging based on the obtained model. According to the result, the developed model well reflects transient characteristics of HT-PEMFC voltage and the fuzzy controller offers good performance for purging scheduling under uncertain load demands. - Highlights: • A semi-empirical dynamic voltage model of HT-PEMFC is developed for control design. • The model is developed via fitting and validated with experimental results. • A fuzzy controller is designed to schedule the purging based on the obtained model.

Effect of nitrogen crossover on purging strategy in PEM fuel cell systems

DEFF Research Database (Denmark)

Rabbani, Raja Abid; Rokni, Masoud

2013-01-01

A comprehensive study on nitrogen crossover in polymer electrolyte membrane fuel cell (PEMFC) system with anode recirculation is conducted and associated purging strategies are discussed. Such systems when employed in automobiles are subjected to continuous changes in load and external operating...

SOME METHODS FOR SAVING HEAT ENERGY WHILE MANUFACTURING VERTICAL INSULATING GLASS UNITS

Directory of Open Access Journals (Sweden)

S. A. Shybeka

2018-01-01

Full Text Available The paper proposes and considers two constructive methods for saving heat energy while manufacturing vertical insulating glass units with various gas filling of inter-glass space. The first method presupposes manufacturing of insulating glass units having specific thickness which is calculated in accordance with specific features of convective heat exchange in the closed loop circuit. Value of the heat-exchange coefficient depends on gas properties which is filling a chamber capacity (coefficients of thermal conductivity, volumetric expansion, kinematic viscosity, thermometric conducivity, temperature difference on the boundary of interlayer and its thickness. It has been shown that while increasing thickness of gas layer convective heat exchange coefficient is initially decreasing up to specific value and then after insignificant increase it practically remains constant. In this connection optimum thicknesses of filled inter-layers for widely-spread gas in production (dry air, argon, krypton, xenon and for carbon dioxide have determined in the paper. Manufacturing of insulating glass units with large thickness of gas chamber practically does not lead to an increase in resistance to heat transfer but it will increase gas consumption rate. The second industrial economic method is interrelated with application of carbon dioxide СО2 as a filler of inter-glass space which has some advantages in comparison with other gases (small cost due to abundance, nontoxicity, transparency for visual light and absorption of heat rays. Calculations have shown that application of carbon dioxide will make it possible to increase resistance to heat transfer of one-chamber glass unit by 0.05 m²×K/W (with emissivity factor of internal glass – 0.837 or by 0.16 m²×K/W (with emission factor – 0.1 in comparison with the glass unit where a chamber is filled with dry air.

Selective removal of water in purge and cold-trap capillary gas chromatographic analysis of volatile organic traces in aqueous samples

NARCIS (Netherlands)

Noij, T.H.M.; van Es, A.J.J.; Cramers, C.A.M.G.; Rijks, J.A.; Dooper, R.P.M.

1987-01-01

The design and features of an on-line purge and cold-trap pre-concentration device for rapid analysis of volatile organic compounds in aqueous samples are discussed. Excessive water is removed from the purge gas by a condenser or a water permeable membrane in order to avoid blocking of the capillary

Simulation of a passive house coupled with a heat pump/organic Rankine cycle reversible unit

DEFF Research Database (Denmark)

Dumont, Olivier; Carmo, Carolina; Randaxhe, François

2014-01-01

This paper presents a dynamic model of a passive house located in Denmark with a large solar absorber, a horizontal ground heat exchanger coupled with a HP/ORC unit. The HP/ORC reversible unit is a module able to work as an Organic Rankine Cycle (ORC) or as a heat pump (HP). There are 3 possible ...... presents a higher global COP because the heat produced on the roof can heat the storage directly.......This paper presents a dynamic model of a passive house located in Denmark with a large solar absorber, a horizontal ground heat exchanger coupled with a HP/ORC unit. The HP/ORC reversible unit is a module able to work as an Organic Rankine Cycle (ORC) or as a heat pump (HP). There are 3 possible...... modes that need to be chosen optimally depending on the weather conditions, the heat demand and the temperature level of the storage. The ORC mode is activated, as long as the heat demand of the house is covered by the storage to produce electricity based upon the heat generated by the solar roof...

Less symptomatic, but equally impaired: Clinical impairment in restricting versus binge-eating/purging subtype of anorexia nervosa.

Science.gov (United States)

Reas, Deborah Lynn; Rø, Øyvind

2018-01-01

This study investigated subtype differences in eating disorder-specific impairment in a treatment-seeking sample of individuals with anorexia nervosa (AN). The Clinical Impairment Assessment (CIA) and the Eating Disorder Examination-Questionnaire (EDE-Q) were administered to 142 patients. Of these, 54.9% were classified as restricting type (AN-R) and 45.1% were classified as binge-eating/purging type (AN-B/P) based on an average weekly occurrence of binge eating and/or purging episodes (≥4 episodes/28days). Individuals with AN-B/P exhibited higher levels of core ED psychopathology (dietary restraint, eating concern, shape/weight concerns) in addition to the expected higher frequency of binge/purge episodes. No significant differences existed between AN subtypes in the severity of ED-related impairment. Weight/shape concerns and binge eating frequency significantly predicted level of impairment. Differential associations were observed between the type of ED pathology that significantly contributed to impairment according to AN subtype. Although those with AN-B/P displayed higher levels of core attitudinal and behavioral ED pathology than AN-R, no significant differences in ED-specific impairment were found between AN subtypes. Eating disorder-related impairment in AN was not related to the severity of underweight or purging behaviors, but was uniquely and positively associated with weight/shape concerns and binge eating frequency. Copyright © 2018 Elsevier Ltd. All rights reserved.

In-well time-of-travel approach to evaluate optimal purge duration during low-flow sampling of monitoring wells

Science.gov (United States)

Harte, Philip T.

2017-01-01

A common assumption with groundwater sampling is that low (time until inflow from the high hydraulic conductivity part of the screened formation can travel vertically in the well to the pump intake. Therefore, the length of the time needed for adequate purging prior to sample collection (called optimal purge duration) is controlled by the in-well, vertical travel times. A preliminary, simple analytical model was used to provide information on the relation between purge duration and capture of formation water for different gross levels of heterogeneity (contrast between low and high hydraulic conductivity layers). The model was then used to compare these time–volume relations to purge data (pumping rates and drawdown) collected at several representative monitoring wells from multiple sites. Results showed that computation of time-dependent capture of formation water (as opposed to capture of preexisting screen water), which were based on vertical travel times in the well, compares favorably with the time required to achieve field parameter stabilization. If field parameter stabilization is an indicator of arrival time of formation water, which has been postulated, then in-well, vertical flow may be an important factor at wells where low-flow sampling is the sample method of choice.

Organic Rankine cycle unit for waste heat recovery on ships (PilotORC)

DEFF Research Database (Denmark)

Haglind, Fredrik; Montagud, Maria E. Mondejar; Andreasen, Jesper Graa

The project PilotORC was aimed at evaluating the technical and economic feasibility of the use of organic Rankine cycle (ORC) units to recover low-temperature waste heat sources (i.e. exhaust gases, scavenge air, engine cooling system, and lubricant oil system) on container vessels. The project...... included numerical simulations and experimental tests on a 125 kW demonstration ORC unit that utilizes the waste heat of the main engine cooling system on board one of Mærsk's container vessels. During the design of the demonstration ORC unit, different alternatives for the condenser were analyzed in order...... of using ORC units for maritime applications, and the relevance of this technology for new-building projects. Firstly, an evaluation of the waste heat resources available on board Mærsk containers fleet, and an estimation of the potential energy recovery by means of the ORC technology was performed...

Trial production of ceramic heat storage unit and study on thermal properties and thermal characteristics of the heat storage unit. Mixed salts of Na2CO3, MgCl2 and CaCl2 as heat storage medium

International Nuclear Information System (INIS)

Shiina, Yasuaki

1998-12-01

Heat storage technique of high temperature and high density latent heat can be applied to an accumulator of heat generated by nuclear power plant in the night and to a thermal load absorber. For the practical use of the heat storage technique, it is important to improve heat exchange characteristics between heat storage medium, such as molten salts, and heat transfer fluid because of low thermal conductivity of the molten salts, to improve durability among molten salt and structure materials and to develop the molten salt with stable thermal properties for a long period. Considering the possibility for the improvement of heat exchange characteristics of phase change heat storage system by absorbing molten salt in porous ceramics with high thermal conductivity, high temperature proof and high resistance to corrosion, several samples of the ceramics heat storage unit were made. Basic characteristics of the samples (strength, thermal properties, temperature characteristics during phase change) were measured experimentally and analytically to study the utility and applicability of the samples for the heat storage system. The results show that the heat storage unit should be used in inactive gas condition because water in the air absorbed in the molten salts would yield degeneration of properties and deterioration of strength and that operation temperature should be confined near fusion temperature because some molten salts would be vaporized and mass would be decreased in considerable high temperature. The results also show that when atmospheric temperature changes around the melting temperature, change in ceramic temperature becomes small. This result suggests the possibility that ceramic heat storage unit could be used as thermal load absorber. (J.P.N.)

Does haplodiploidy purge inbreeding depression in rotifer populations?

Directory of Open Access Journals (Sweden)

Ana M Tortajada

2009-12-01

Full Text Available Inbreeding depression is an important evolutionary factor, particularly when new habitats are colonized by few individuals. Then, inbreeding depression by drift could favour the establishment of later immigrants because their hybrid offspring would enjoy higher fitness. Rotifers are the only major zooplanktonic group where information on inbreeding depression is still critically scarce, despite the fact that in cyclical parthenogenetic rotifers males are haploid and could purge deleterious recessive alleles, thereby decreasing inbreeding depression.We studied the effects of inbreeding in two populations of the cyclical parthenogenetic rotifer Brachionus plicatilis. For each population, we compared both the parental fertilization proportion and F1 fitness components from intraclonal (selfed and interclonal (outcrossed crosses. The parental fertilization proportion was similar for both types of crosses, suggesting that there is no mechanism to avoid selfing. In the F1 generation of both populations, we found evidence of inbreeding depression for the fitness components associated with asexual reproduction; whereas inbreeding depression was only found for one of the two sexual reproduction fitness components measured.Our results show that rotifers, like other major zooplanktonic groups, can be affected by inbreeding depression in different stages of their life cycle. These results suggest that haplodiploidy does not purge efficiently deleterious recessive alleles. The inbreeding depression detected here has important implications when a rotifer population is founded and intraclonal crossing is likely to occur. Thus, during the foundation of new populations inbreeding depression may provide opportunities for new immigrants, increasing gene flow between populations, and affecting genetic differentiation.

Does Haplodiploidy Purge Inbreeding Depression in Rotifer Populations?

Science.gov (United States)

Tortajada, Ana M.; Carmona, María José; Serra, Manuel

2009-01-01

Background Inbreeding depression is an important evolutionary factor, particularly when new habitats are colonized by few individuals. Then, inbreeding depression by drift could favour the establishment of later immigrants because their hybrid offspring would enjoy higher fitness. Rotifers are the only major zooplanktonic group where information on inbreeding depression is still critically scarce, despite the fact that in cyclical parthenogenetic rotifers males are haploid and could purge deleterious recessive alleles, thereby decreasing inbreeding depression. Methodology/Principal Findings We studied the effects of inbreeding in two populations of the cyclical parthenogenetic rotifer Brachionus plicatilis. For each population, we compared both the parental fertilization proportion and F1 fitness components from intraclonal (selfed) and interclonal (outcrossed) crosses. The parental fertilization proportion was similar for both types of crosses, suggesting that there is no mechanism to avoid selfing. In the F1 generation of both populations, we found evidence of inbreeding depression for the fitness components associated with asexual reproduction; whereas inbreeding depression was only found for one of the two sexual reproduction fitness components measured. Conclusions/Significance Our results show that rotifers, like other major zooplanktonic groups, can be affected by inbreeding depression in different stages of their life cycle. These results suggest that haplodiploidy does not purge efficiently deleterious recessive alleles. The inbreeding depression detected here has important implications when a rotifer population is founded and intraclonal crossing is likely to occur. Thus, during the foundation of new populations inbreeding depression may provide opportunities for new immigrants, increasing gene flow between populations, and affecting genetic differentiation. PMID:19997616

40 CFR 63.6092 - Are duct burners and waste heat recovery units covered by subpart YYYY?

Science.gov (United States)

2010-07-01

... Combustion Turbines What This Subpart Covers § 63.6092 Are duct burners and waste heat recovery units covered by subpart YYYY? No, duct burners and waste heat recovery units are considered steam generating units... 40 Protection of Environment 12 2010-07-01 2010-07-01 true Are duct burners and waste heat...

Centrifugal Compressor Unit-based Heat Energy Recovery at Compressor Stations

Directory of Open Access Journals (Sweden)

V. S. Shadrin

2016-01-01

Full Text Available About 95% of the electricity consumed by air compressor stations around the world, is transformed into thermal energy, which is making its considerable contribution to global warming. The present article dwells on the re-use (recovery of energy expended for air compression.The article presents the energy analysis of the process of compressing air from the point of view of compressor drive energy conversion into heat energy. The temperature level of excess heat energy has been estimated in terms of a potential to find the ways of recovery of generated heat. It is shown that the temperature level formed by thermal energy depends on the degree of air compression and the number of stages of the compressor.Analysis of technical characteristics of modern equipment from leading manufacturers, as well as projects of the latest air compressor stations have shown that there are two directions for the recovery of heat energy arising from the air compression: Resolving technological problems of compressor units. The use of the excess heat generation to meet the technology objectives of the enterprise. This article examines the schematic diagrams of compressor units to implement the idea of heat recovery compression to solve technological problems: Heating of the air in the suction line during operation of the compressor station in winter conditions. Using compression heat to regenerate the adsorbent in the dryer of compressed air.The article gives an equity assessment of considered solutions in the total amount of heat energy of compressor station. Presented in the present work, the analysis aims to outline the main vectors of technological solutions that reduce negative impacts of heat generation of compressor stations on the environment and creating the potential for reuse of energy, i.e. its recovery.

Thermal performance analysis of a phase change thermal storage unit for space heating

Energy Technology Data Exchange (ETDEWEB)

Halawa, E.; Saman, W. [Institute for Sustainable Systems and Technologies School of Advanced Manufacturing and Mechanical Engineering, University of South Australia, Mawson Lakes SA 5095 (Australia)

2011-01-15

This paper presents the results of a comprehensive numerical study on the thermal performance of an air based phase change thermal storage unit (TSU) for space heating. The unit is designed for integration into space heating and cooling systems. The unit consists of a number of one dimensional phase change material (PCM) slabs contained in a rectangular duct where air passes between the slabs. The numerical analysis was based on an experimentally validated model. A parametric study has been carried out including the study on the effects of charge and discharge temperature differences, air mass flow rate, slab thicknesses, air gaps and slab dimensions on the air outlet temperatures and heat transfer rates of the thermal storage unit. The paper introduces and discusses quantities called charge and discharge temperature differences which play an important role in the melting and freezing processes. (author)

Environmental assessment for decontamination of the Three Mile Island Unit 2 reactor building atmosphere. Addendum 2. Draft NRC staff report for public comment

Energy Technology Data Exchange (ETDEWEB)

NONE

1980-04-01

The reactor building purge system is an existing system originally installed for purging the reactor building atmosphere during normal operation or maintenance conditions. Use of the reactor building purge system in conjunction with the hydrogen control subsystem evaluated in Section 6.1 represents a variation in the purging alternative for decontaminating the Unit 2 reactor building atmosphere. This variation in the purging alternative would function only under meteorological conditions favorable to atmospheric dispersion. The reactor building purge system is capable of purging the building at flow rates of 5,000-50,000 cfm. Actual purge rates authorized during any time interval would be dependent on meteorological conditions and reactor building concentrations. Like the hydrogen control subsystem, this system would remove reactor building atmosphere through a filter system and discharge it through the 160-ft plant vent stack to the environment. The advantage of using the reactor building purge system in conjunction with the hydrogen control system is that it could decontaminate the reactor building atmosphere in a total elapsed purge time as short as approximately 5 days, as compared with the 60 days that would be required if the hydrogen purge subsystem were used alone. Use of this variation in the purge alternative would result in the release of radioactive materials to the environment. However, calculations based on actual meteorological and release-rate data would be used to monitor radioactive releases so that they do not exceed the requirements of 10 CFR Part 20, the design objectives of 10 CFR Part 50, Appendix 1 and the applicable requirements of 40 CFR 190.10.

Spent Nuclear Fuel (SNF) Project Cask and MCO Helium Purge System Design Review Completion Report - Project A.5 and A.6

International Nuclear Information System (INIS)

ARD, K.E.

2000-01-01

This report documents the results of the design verification performed on the Cask and Multiple Canister Over-pack (MCO) Helium Purge System. The helium purge system is part of the Spent Nuclear Fuel (SNF) Project Cask Loadout System (CLS) at 100K area. The design verification employed the ''Independent Review Method'' in accordance with Administrative Procedure (AP) EN-6-027-01

The urban heat island dynamics during heat waves: a study of cities in the United States

Science.gov (United States)

Hu, Leiqiu

2016-04-01

The urban heat island (UHI) is a common phenomenon describing that metropolitan areas are usually warmer than their rural surroundings. This effect is compounded by extreme heat events, which are a leading cause of weather-related human mortality in many countries worldwide. However, the spatial and diurnal variability of temperature and humidity in urban and adjacent rural areas during extreme heat events is not well measured and therefore not well understood. The recently developed dataset of near-surface air and dew temperature from MODIS atmospheric profiles and the new method for the UHI quantification--urban heat island curve are used to quantify the urban climatic changes during heat waves in cities of the United States. The enhanced and weakened UHIs are observed in various cities. The causes of UHI changes during heat waves are discussed, including climate region, vegetation type and amount, city geolocation, etc.

A New Approach for Heating the Plastics Injection Units

Directory of Open Access Journals (Sweden)

Virgilius Vasilache

2010-06-01

Full Text Available The plastics injection molding machines are one of the most eager consumers of energy. The plasticizing unit itself is the most important energetic consumer among the subassemblies of these machines; that is why this subassembly is the target of most actions of consumption decreasing on such machines. Our concerns on this direction got the shape of developing a new heating system for the plasticizing unit, which system was already patented [1].

Seasonal patterns of birth for subjects with bulimia nervosa, binge eating, and purging: results from the National Women's Study.

Science.gov (United States)

Brewerton, Timothy D; Dansky, Bonnie S; O'Neil, Patrick M; Kilpatrick, Dean G

2012-01-01

Studies of birth patterns in anorexia nervosa have shown relative increases between March and August, while studies in Bulimia Nervosa (BN) have been negative. Since there are no studies using representative, nonclinical samples, we looked for seasonal birth patterns in women with BN and in those who ever endorsed bingeing or purging. A national, representative sample of 3,006 adult women completed structured telephone interviews including screenings for bulimia nervosa (BN) and questions about month, date, and year of birth. Season of birth was calculated using traditional definitions. Differences across season of birth between subjects with (n = 85) and without BN (n = 2,898), those with (n = 749) and without bingeing (n = 2,229), and those with (n = 267) and without any purging (n = 2,715) were compared using chi-square analyses. There were significant differences across season of birth between subjects: (1) with and without BN (p = 0.033); (2) with and without bingeing (p = 0.034), and; (3) with and without purging (p = 0.001). Fall had the highest relative number of births for all categories, while spring had the lowest. In a national representative study of nontreatment seeking subjects significant differences in season of birth were found for subjects with lifetime histories of BN, binge eating and purging. © 2011 by Wiley Periodicals, Inc. (Int J Eat Disord 2012). Copyright © 2011 Wiley Periodicals, Inc.

Molecular purging of multiple myeloma cells by ex-vivo culture and retroviral transduction of mobilized-blood CD34+ cells

Directory of Open Access Journals (Sweden)

Corneo Gianmarco

2007-07-01

Full Text Available Abstract Background Tumor cell contamination of the apheresis in multiple myeloma is likely to affect disease-free and overall survival after autografting. Objective To purge myeloma aphereses from tumor contaminants with a novel culture-based purging method. Methods We cultured myeloma-positive CD34+ PB samples in conditions that retained multipotency of hematopoietic stem cells, but were unfavourable to survival of plasma cells. Moreover, we exploited the resistance of myeloma plasma cells to retroviral transduction by targeting the hematopoietic CD34+ cell population with a retroviral vector carrying a selectable marker (the truncated form of the human receptor for nerve growth factor, ΔNGFR. We performed therefore a further myeloma purging step by selecting the transduced cells at the end of the culture. Results Overall recovery of CD34+ cells after culture was 128.5%; ΔNGFR transduction rate was 28.8% for CD34+ cells and 0% for CD138-selected primary myeloma cells, respectively. Recovery of CD34+ cells after ΔNGFR selection was 22.3%. By patient-specific Ig-gene rearrangements, we assessed a decrease of 0.7–1.4 logs in tumor load after the CD34+ cell selection, and up to 2.3 logs after culture and ΔNGFR selection. Conclusion We conclude that ex-vivo culture and retroviral-mediated transduction of myeloma leukaphereses provide an efficient tumor cell purging.

Heat stress assessment in artistic glass units.

Science.gov (United States)

d'AMBROSIO Alfano, Francesca Romana; Palella, Boris Igor; Riccio, Giuseppe; Bartalini, Massimo; Strambi, Fabio; Malchaire, Jacques

2018-04-07

Heat stress in glass industry is mainly studied in large and highly mechanized manufacturing Units. To the contrary, few studies were carried out in small factories specialized in hand-made products. To stress the need of combined objective and medical surveys in these environments, this paper deals with a simultaneous climatic and physiological investigation of working conditions in artistic crystal glass factories in Tuscany (Italy). The microclimatic monitoring, through a continuous survey has been carried out in early spring. The main physiological parameters (metabolic rate, heart rate, tympanic temperature and water loss) were measured over the whole shifts. The results show that, despite the arduousness of the working conditions, the heat stress levels are physiologically tolerable. The predictions made using the PHS model at the Analysis level described in ISO 15265 agree closely to the observed values, validating the use of PHS model in these conditions. This model was then used to analyse what is likely to be the situation during the summer. It is concluded that the heat constraint will be very high and that some steps must be taken from the spring to monitor closely the exposed workers in the summer and take measures to prevent any heat accident.

Integrating Solar Heating into an Air Handling Unit to Minimize Energy Consumption

OpenAIRE

Wilson, Scott A

2010-01-01

The purpose of this project was to test a method of integrating solar heating with a small commercial air handling unit (AHU). In order to accomplish this a heat exchanger was placed in the reheat position of the AHU and piped to the solar heating system. This heat exchanger is used to supplement or replace the existing electric reheat. This method was chosen for its ability to utilize solar energy on a more year round basis when compared to a traditional heating system. It allows solar h...

Flow characteristics analysis of purge gas in unitary pebble beds by CFD simulation coupled with DEM geometry model for fusion blanket

Energy Technology Data Exchange (ETDEWEB)

Chen, Youhua [University of Science and Technology of China, Hefei, Anhui, 230027 (China); Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); Chen, Lei [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); Liu, Songlin, E-mail: slliu@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); Luo, Guangnan [University of Science and Technology of China, Hefei, Anhui, 230027 (China); Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China)

2017-01-15

Highlights: • A unitary pebble bed was built to analyze the flow characteristics of purge gas based on DEM-CFD method. • Flow characteristics between particles were clearly displayed. • Porosity distribution, velocity field distribution, pressure field distribution, pressure drop and the wall effects on velocity distribution were studied. - Abstract: Helium is used as the purge gas to sweep tritium out when it flows through the lithium ceramic and beryllium pebble beds in solid breeder blanket for fusion reactor. The flow characteristics of the purge gas will dominate the tritium sweep capability and tritium recovery system design. In this paper, a computational model for the unitary pebble bed was conducted using DEM-CFD method to study the purge gas flow characteristics in the bed, which include porosity distribution between pebbles, velocity field distribution, pressure field distribution, pressure drop as well as the wall effects on velocity distribution. Pebble bed porosity and velocity distribution with great fluctuations were found in the near-wall region and detailed flow characteristics between pebbles were displayed clearly. The results show that the numerical simulation model has an error with about 11% for estimating pressure drop when compared with the Ergun equation.

Cooperation of Horizontal Ground Heat Exchanger with the Ventilation Unit During Summer - Case Study

Science.gov (United States)

Romańska-Zapała, Anna; Furtak, Marcin; Dechnik, Mirosław

2017-10-01

Renewable energy sources are used in the modern energy-efficient buildings to improve their energy balance. One of them is used in the mechanical ventilation system ground air heat exchanger (earth-air heat exchanger - EAHX). This solution, right after heat recovery from exhaust air (recuperation), allows the reduction in the energy needed to obtain the desired temperature of supply air. The article presents the results of "in situ" measurements of pipe ground air heat exchanger cooperating with the air handling unit, supporting cooling the building in the summer season, in Polish climatic conditions. The laboratory consists of a ventilation unit intake - exhaust with rotor for which the source of fresh air is the air intake wall and two air intakes field cooperating with the tube with ground air heat exchangers. Selection of the source of fresh air is performed using sprocket with actuators. This system is part of the ventilation system of the Malopolska Laboratory of Energy-Efficient Building (MLBE) building of Cracow University of Technology. The measuring system are, among others, the sensors of parameters of air inlets and outlets of the heat exchanger channels EAHX and weather station that senses the local weather conditions. The measurement data are recorded and archived by the integrated process control system in the building of MLBE. During the study measurements of operating parameters of the ventilation unit cooperating with the selected source of fresh air were performed. Two cases of operation of the system: using EAHX heat exchanger and without it, were analyzed. Potentially the use of ground air heat exchanger in the mechanical ventilation system can reduce the energy demand for heating or cooling rooms by the pre-adjustment of the supply air temperature. Considering the results can be concluded that the continuous use of these exchangers is not optimal. This relationship is appropriate not only on an annual basis for the transitional periods (spring

Assessment of the Performance of a Ventilated Window Coupled with a Heat Recovery Unit through the Co-Heating Test

Directory of Open Access Journals (Sweden)

Ludovico Danza

2016-01-01

Full Text Available The aim of the article is to describe the results of an experimental campaign based on the assessment of a heat recovery unit coupled with a dynamic window. Two fully monitored and calibrated outdoor test cells are used, in order to evaluate the energy performance and the related thermal comfort. The former presents a traditional window with double-glazing, aluminum frame and indoor blind and a centrifugal extractor for the air circulation. The latter is equipped with a dynamic window with ventilated and blinded double-glazing provided with a heat exchanger. The connection of the dynamic window and heat recovery unit provides different actions: heat recovery; heat transfer reduction; pre-heating before the exchanger. Different operating configurations allowed the trends of the dynamic system to be assessed in different seasons in terms of energy saving, thermal comfort behavior and energy efficiency. The results showed an overall lower consumption of the innovative system, both in winter and summer, with 20% and 15% energy saving, respectively. In general, the dynamic system provided the best comfort conditions, even if it involves a worse behavior than expected, in the summer season.

Performance investigation on a multi-unit heat pump for simultaneous temperature and humidity control

International Nuclear Information System (INIS)

Fan, Hongming; Shao, Shuangquan; Tian, Changqing

2014-01-01

Highlights: • A multi-unit heat pump is proposed for simultaneous temperature and humidity control. • Condensation heat is non, partly or fully recovered for temperature regulation. • Highly integrated heat pump for residential cooling, dehumidification and heating. • High energy saving potential for all-year-round operation in wet and warm regions. - Abstract: A multi-unit heat pump is presented for simultaneous humidity and temperature control to improve the energy efficiency and the thermal comfort. Two parallel connected condensers are employed in the system, locating at the back of the indoor evaporator and the outdoor unit, respectively. The heat pump can operate in four modes, including heating, cooling and dehumidification without and/or with partial or total condensing heat recovery. The experimental investigation shows that the temperature control capacity is from 3.5 kW for cooling to 3.8 kW for heating with the cooling and heating efficiency higher than 3.5 kW kW −1 , and the dehumidification rate is about 2.0 kg h −1 with the efficiency about 2.0 kg h −1 kW −1 . The supply air temperature and humidity can be simultaneously regulated with high accuracy and high efficiency by adjusting the indoor and/or outdoor air volumes. It provides an integrated and effective solution for simultaneous indoor air temperature and humidity control for all-year-round operation in residential buildings

Large-Scale Combined Heat and Power (CHP) Generation at Loviisa Nuclear Power Plant Unit 3

International Nuclear Information System (INIS)

Bergroth, N.

2010-01-01

Fortum has applied for a Decision in Principle concerning the construction of a new nuclear power plant unit (Loviisa 3) ranging from 2800-4600 MWth at its site located at the southern coast of Finland. An attractive alternative investigated is a co-generation plant designed for large-scale district heat generation for the Helsinki metropolitan area that is located approximately 75 km west of the site. The starting point is that the district heat generation capacity of 3 unit would be around 1 000 MWth.The possibility of generating district heat for the metropolitan area by Loviisa's two existing nuclear power plant units was investigated back in the 1980s, but it proved unpractical at the time. With the growing concern of the climate change and the subsequent requirements on heat and power generation, the idea is much more attractive today, when recognising its potential to decrease Finland's carbon dioxide emissions significantly. Currently the district heat generation in metropolitan area is based on coal and natural gas, producing some five to seven million tonnes of carbon dioxide emissions annually. Large-scale combined heat and power (CHP) generation at the 3 unit could cut this figure by up to four million tonnes. This would decrease carbon dioxide emissions by as much as six percent. In addition, large-scale CHP generation would increase the overall efficiency of the new unit significantly and hence, reduce the environmental impact on the local marine environment by cutting heat discharges into the Gulf of Nuclear energy has been used for district heating in several countries both in dedicated nuclear heating plants and in CHP generation plants. However, the heat generation capacity is usually rather limited, maximum being around 250 MWth per unit. Set against this, the 3 CHP concept is much more ambitious, not only because of the much larger heat generation output envisaged, but also because the district heating water would have to be transported over a

The cool seal system: a practical solution to the shaft seal problem and heat related complications with implantable rotary blood pumps.

Science.gov (United States)

Yamazaki, K; Mori, T; Tomioka, J; Litwak, P; Antaki, J F; Tagusari, O; Koyanagi, H; Griffith, B P; Kormos, R L

1997-01-01

A critical issue facing the development of an implantable, rotary blood pump is the maintenance of an effective seal at the rotating shaft. Mechanical seals are the most versatile type of seal in wide industrial applications. However, in a rotary blood pump, typical seal life is much shorter than required for chronic support. Seal failure is related to adhesion and aggregation of heat denatured blood proteins that diffuse into the lubricating film between seal faces. Among the blood proteins, fibrinogen plays an important role due to its strong propensity for adhesion and low transition temperature (approximately 50 degrees C). Once exposed to temperature exceeding 50 degrees C, fibrinogen molecules fuse together by multi-attachment between heat denatured D-domains. This quasi-polymerized fibrin increases the frictional heat, which proliferates the process into seal failure. If the temperature of the seal faces is maintained well below 50 degrees C, a mechanical seal would not fail in blood. Based on this "Cool-Seal" concept, we developed a miniature mechanical seal made of highly thermally conductive material (SiC), combined with a recirculating purge system. A large supply of purge fluid is recirculated behind the seal face to augment convective heat transfer to maintain the seal temperature below 40 degrees C. It also cools all heat generating pump parts (motor coil, bearing, seal). The purge consumption has been optimized to virtually nil (seal system has now been incorporated into our intraventricular axial flow blood pump (IVAP) and newly designed centrifugal pump. Ongoing in vivo evaluation of these systems has demonstrated good seal integrity for more than 160 days. The Cool-Seal system can be applied to any type of rotary blood pump (axial, diagonal, centrifugal, etc.) and offers a practical solution to the shaft seal problem and heat related complications, which currently limit the use of implantable rotary blood pumps.

Heat recovery from UPS units - Analysis of a first unit and technology assessment; Waermerueckgewinnung in USV-Anlagen. Analyse einer Erstanlage und Potentialabschaetzung

Energy Technology Data Exchange (ETDEWEB)

Stahl, S.; Schlegel, A.

2009-11-15

UPS units (uninterruptible power supply) generate large heat losses, which have to be dissipated with cooling units. awtec has developed a unique UPS system with integrated heat recovery which was installed in 2001 (Building Gretag/SAP in Regensdorf) and which is still running error-free. With this system the waste heat can be recovered and electrical energy for the refrigeration system can be saved likewise. The measured data shows that during the heating season, the unit transfers virtually all heat loss (about 20 MWh/year) to the space heating system. The building's refrigeration system, however, has its own heat recovery system, so the actual annual energy savings can be estimated to be only about 4 MWh of electricity. The prototype shows that awtec built a robust unit which - given an appropriate cooling and heating system - has the potential for high energy savings (without central heat recovery system: 4 MWh electric + 20 MWh thermal) without increased investment. Based on the UPS heat recovery development, previous projects of the Swiss Federal Office of Energy and a market survey, scenarios for the cooling and heat recovery from UPS units were developed. Since the same concepts also apply to the cooling of servers and other IT components, they were also included in the analysis. The scenario analysis shows that a high potential for savings of electric energy and heat exists in this area. In particular, the direct cooling of the IT components with cooling water offers big benefits for heat recovery and free cooling (cooling without the use of the refrigeration system) compared to conventional air cooling. These direct cooling systems are currently mainly used for special applications or as a fallback in case of overheating problems. Passive cooling through geothermal probes, which are now mainly used for buildings with small heat pump systems, provides an interesting approach to the cooling of IT equipment in accordance with the temperature level. It

Heat-transfer, inside of the ground heat-transfer units, from liquid, additionally cooling the oil-immersed transformer

Directory of Open Access Journals (Sweden)

Madyshev Ilnur

2017-01-01

Full Text Available A device for cooling the oil-immersed transformer by means of thermoelectric transducers has been developed. Their operating principle is based on the fact that at night at minimum ambient temperature, the cold is accumulated inside of a vessel due to formation of water ice layer on the developed surfaces of thermoelectric transducers` ribs. Melting of this layer is used in the hottest time of a day for additional cooling of transformer oil in the cooling system of the transformer. Pre-cooling of the circulating water takes place in vertical ground heat-transfer units (VGHT units, mounted into ground drilled boreholes. Certain estimate calculations of the heat-transfer process have been carried out.

Calculation method for the seasonal performance of heat pump compact units and validation. Appendix

Energy Technology Data Exchange (ETDEWEB)

Wemhoener, C.; Dott, R.; Afjei, Th. [University of Applied Sciences Northwestern Switzerland, Institute of Energy in Buildings, Muttenz (Switzerland); Huber, H.; Helfenfinger, D.; Keller, P.; Furter, R. [University of Applied Sciences Lucerne (HTA), Test center HLKS, Horw (Switzerland)

2007-02-15

This appendix to a comprehensive final report for the Swiss Federal Office of Energy (SFOE) presents the results of tests made on compact heat pump units that have been developed for the heating of low energy consumption houses built to MINERGIE or MINERGIE-P standards. The tests on these units, which combine the functions of space heating, domestic hot water preparation and ventilation in one unit are presented and discussed. Test conditions are described; these cover ventilation, acoustic, hygiene and safety aspects. Detailed results from the two test objects - buildings built to MINERGIE and MINERGIE-P low energy consumption standards - are presented and discussed. The calculation methods used are examined and discussed.

Calculation method for the seasonal performance of heat pump compact units and validation. Final report

Energy Technology Data Exchange (ETDEWEB)

Wemhoener, C.; Dott, R.; Afjei, Th. [University of Applied Sciences Northwestern Switzerland, Institute of Energy in Buildings, Muttenz (Switzerland); Huber, H.; Helfenfinger, D.; Keller, P.; Furter, R. [University of Applied Sciences Lucerne (HTA), Test center HLKS, Horw (Switzerland)

2007-02-15

This comprehensive final report for the Swiss Federal Office of Energy (SFOE) takes a look at compact heat pump units that have been developed for the heating of low energy consumption houses built to MINERGIE or MINERGIE-P standards. These units, which combine the functions of space heating, domestic hot water preparation and ventilation in one unit are described. A testing procedure developed at the University of Applied Science in Lucerne, Switzerland, using a test rig for the measurement of the seasonal performance factor (SPF) is described. A calculation method based on temperature classes for the calculation of the SPF of combined heat pump systems for space heating and domestic hot water preparation that was developed by the Institute of Energy in Buildings at the University of Applied Sciences Northwestern Switzerland is examined. Two pilot plants allowing detailed field monitoring of two compact units are described. One pilot plant installed in a single-family house built to MINERGIE standard in Gelterkinden, Switzerland, provided data on a compact unit. These results of measurements made on this and a further installation in a MINERGIE-P ultra-low energy consumption house in Zeiningen, Switzerland, are presented and discussed. Calculation methods, including exergy considerations are reviewed and their validation is discussed.

Empirical Analysis for the Heat Exchange Effectiveness of a Thermoelectric Liquid Cooling and Heating Unit

Directory of Open Access Journals (Sweden)

Hansol Lim

2018-03-01

Full Text Available This study aims to estimate the performance of thermoelectric module (TEM heat pump for simultaneous liquid cooling and heating and propose empirical models for predicting the heat exchange effectiveness. The experiments were conducted to investigate and collect the performance data of TEM heat pump where the working fluid was water. A total of 57 sets of experimental data were statistically analyzed to estimate the effects of each independent variable on the heat exchange effectiveness using analysis of variance (ANOVA. To develop the empirical model, the six design parameters were measured: the number of transfer units (NTU of the heat exchangers (i.e., water blocks, the inlet water temperatures and temperatures of water blocks at the cold and hot sides of the TEM. As a result, two polynomial equations predicting heat exchange effectiveness at the cold and hot sides of the TEM heat pump were derived as a function of the six selected design parameters. Also, the proposed models and theoretical model of conventional condenser and evaporator for heat exchange effectiveness were compared with the additional measurement data to validate the reliability of the proposed models. Consequently, two conclusions have been made: (1 the possibility of using the TEM heat pump for simultaneous cooling and heating was examined with the maximum temperature difference of 30 °C between cold and hot side of TEM, and (2 it is revealed that TEM heat pump has difference with the conventional evaporator and condenser from the comparison results between the proposed models and theoretical model due to the heat conduction and Joule effect in TEM.

Emission factors of modern wood-pellet heating units under typical heating conditions - Final report; Emissionsfaktoren moderner Pelletkessel unter typischen Heizbedingungen - Schlussbericht

Energy Technology Data Exchange (ETDEWEB)

Good, J.; Nussbaumer, T.

2009-12-15

This final report for the Swiss Federal Office of Energy (SFOE) reports on the results of measurements made concerning the emission factors of two modern wood-pellet heating units under typical heating conditions. Using simulations, typical operation in single-family homes and apartment blocks were examined. Emissions during the different phases of operation were examined. Systems with and without buffer storage were also examined. The minimum running times to be striven for are quoted which would lead to a reduction of emissions to an acceptable level. The characteristic operating modes for the two heating units and the results obtained for various emissions are presented and discussed.

Comparison of the heat generation of light curing units.

Science.gov (United States)

Bagis, Bora; Bagis, Yildirim; Ertas, Ertan; Ustaomer, Seda

2008-02-01

The aim of this study was to evaluate the heat generation of three different types of light curing units. Temperature increases were recorded from a distance of 1 mm from a thermocouple to the tip of three different types of light curing units including one quartz-tungsten halogen (QTH), one plasma arc (PAC), and one light emitting diode (LED) unit. An experimental model was designed to fix the 1 mm distance between the tip of the light curing units and the thermocouple wire. Temperature changes were recorded in 10 second intervals up to 40 seconds. (10, 20, 30, and 40 seconds). Temperature measurements were repeated three times for every light curing unit after a one hour standby period. Statistical analysis of the results was performed using the analysis of variance (ANOVA) and the Bonferroni Test. The highest temperature rises (54.4+/-1.65 degrees C) occurred during activation of a PAC light curing unit for every test period (pdamage to the pulp.

Heat recovery unit operation of HVAC system in IMEF

International Nuclear Information System (INIS)

Paek, S. R.; Oh, Y. W.; Song, E. S.; Park, D. K.; Joo, Y. S.; Hong, K. P.

2003-01-01

HVAC system including a supply and exhaust air system in IMEF(Irradiated Materials Examination Facility) is an essential facility for preventing a leakage of radioactive materials and for a preservation of a working environment. It costs a lot to operate the HVAC system in IMEF because our ventilation type is once-through system, and an air flow is maintained from low level contamination area to high level and maintained high turns of ventilation air under certain conditions. As HRU(Heat Recovery Unit) at HVAC system based on PIEF(Post Irradiation Examination Facility) operation experiences is designed and adopted, it prevents from a heating coil freezing destruction in winter and makes much energy saving etc.. Heat pipe type HRU is adopted in IMEF, and a construction and operation result of HRU is examined

Accelerating the energy policy turnaround with combined heat and power units; Mit Blockheizkraftwerken die Energiewende rund machen

Energy Technology Data Exchange (ETDEWEB)

Lange, Joerg; Geiler, Nikolaus [Klimabuendnis Freiburg, Freiburg im Breisgau (Germany)

2013-03-15

No other type of decentralized power plants transforms natural gas to electric power so efficiently as a combined heat and power unit. In the long term, the climate-friendly effect using renewable hydrogen or renewably generated 'natural gas' even could be increased. Thus, combined heat and power units are ideal to achieve the national climate change objectives. Despite their advantages, the implementation of combined heat and power units advances only sluggishly.

Thermal-economic optimization of an air-cooled heat exchanger unit

International Nuclear Information System (INIS)

Alinia Kashani, Amir Hesam; Maddahi, Alireza; Hajabdollahi, Hassan

2013-01-01

Thermodynamic modeling and optimal design of an air-cooled heat exchanger (ACHE) unit are developed in this study. For this purpose, ε–NTU method and mathematical relations are applied to estimate the fluids outlet temperatures and pressure drops in tube and air sides. The main goal of this study is minimizing of two conflicting objective functions namely the temperature approach and the minimum total annual cost, simultaneously. For this purpose, fast and elitist non-dominated sorting genetic-algorithm (NSGA-II) is applied to minimize the objective functions by considering ten design parameters. In addition, a set of typical constraints, governing on the ACHE unit design, is subjected to obtain more practical optimum design points. Furthermore, sensitivity analysis of change in the objective functions, when the optimum design parameters vary, is conducted and the degree of each parameter on conflicting objective functions has been investigated. Finally, a selection procedure of the best optimum point is introduced and final optimum design point is determined. -- Highlights: ► Multi-objective optimization of air-cooled heat exchanger. ► Considering ten new design parameters in this type of heat exchanger. ► A detailed cost function is used to estimate the heat exchanger investment cost. ► Presenting a mathematical relation for optimum total cost vs. temperature approach. ► The sensitivity analysis of parameters in the optimum situation

Rapid improvements in emotion regulation predict intensive treatment outcome for patients with bulimia nervosa and purging disorder.

Science.gov (United States)

MacDonald, Danielle E; Trottier, Kathryn; Olmsted, Marion P

2017-10-01

Rapid and substantial behavior change (RSBC) early in cognitive behavior therapy (CBT) for eating disorders is the strongest known predictor of treatment outcome. Rapid change in other clinically relevant variables may also be important. This study examined whether rapid change in emotion regulation predicted treatment outcomes, beyond the effects of RSBC. Participants were diagnosed with bulimia nervosa or purging disorder (N = 104) and completed ≥6 weeks of CBT-based intensive treatment. Hierarchical regression models were used to test whether rapid change in emotion regulation variables predicted posttreatment outcomes, defined in three ways: (a) binge/purge abstinence; (b) cognitive eating disorder psychopathology; and (c) depression symptoms. Baseline psychopathology and emotion regulation difficulties and RSBC were controlled for. After controlling for baseline variables and RSBC, rapid improvement in access to emotion regulation strategies made significant unique contributions to the prediction of posttreatment binge/purge abstinence, cognitive psychopathology of eating disorders, and depression symptoms. Individuals with eating disorders who rapidly improve their belief that they can effectively modulate negative emotions are more likely to achieve a variety of good treatment outcomes. This supports the formal inclusion of emotion regulation skills early in CBT, and encouraging patient beliefs that these strategies are helpful. © 2017 Wiley Periodicals, Inc.

Thermodynamic investigation of waste heat driven desalination unit based on humidification dehumidification (HDH) processes

International Nuclear Information System (INIS)

He, W.F.; Xu, L.N.; Han, D.; Gao, L.; Yue, C.; Pu, W.H.

2016-01-01

Highlights: • HDH desalination system powered by waste heat is proposed. • Performance of the desalination unit and the relevant heat recovery effect is calculated. • Sensitive analysis of the performance for the HDH desalination system is investigated. • Mathematical model based on the first and second laws of thermodynamics is established. - Abstract: Humidification dehumidification (HDH) technology is an effective pattern to separate freshwater from seawater or brackish water. In this paper, a closed-air open-water (CAOW) desalination unit coupled with plate heat exchangers (PHEs) is applied to recover the waste heat from the gas exhaust. Sensitivity analysis for the HDH desalination unit as well as the PHEs from the key parameters including the top and initial temperature of the seawater, operation pressure, and the terminal temperature difference (TTD) of the PHEs are accomplished, and the corresponding performance of the whole HDH desalination system is calculated and presented. The simulation results show that the balance condition of the dehumidifier is allowed by the basic thermodynamic laws, followed by a peak value of gained-output-ratio (GOR) and a bottom value of total specific entropy generation. It is concluded that excellent results including the system performance, heat recovery effect and investment of the PHEs can be simultaneously obtained with a low top temperature, while the obtained desalination performance and the heat recovery effect from other measures are always conflicting. Different from other parameters of the desalination unit, the terminal temperature difference of the PHEs has little influences on the final value of GOR.

A heated vapor cell unit for DAVLL in atomic rubidium

OpenAIRE

McCarron, Daniel J.; Hughes, Ifan G.; Tierney, Patrick; Cornish, Simon L.

2007-01-01

The design and performance of a compact heated vapor cell unit for realizing a dichroic atomic vapor laser lock (DAVLL) for the D2 transitions in atomic rubidium is described. A 5 cm-long vapor cell is placed in a double-solenoid arrangement to produce the required magnetic field; the heat from the solenoid is used to increase the vapor pressure and correspondingly the DAVLL signal. We have characterized experimentally the dependence of important features of the DAVLL signal on magnetic field...

Method for heating of the primary circuit of WWER electric power units at cold start-up

International Nuclear Information System (INIS)

Ivanov, I.N.; Dimitrov, B.D.; Korkinova, M.I.

1982-01-01

The method increases the heating rate and shorten the start-up time of the electric power units. It comprises a primary stopping of the reactor core heating and provides a forced circulation of the heat-carrier through the circulation cycles of the primary circuit. The thermal energy is supplied in one or several steam generators in the secondary circuit of an NPP operating unit. 1 cl., 3 figs

The energy efficiency ratio of heat storage in one shell-and-one tube phase change thermal energy storage unit

International Nuclear Information System (INIS)

Wang, Wei-Wei; Wang, Liang-Bi; He, Ya-Ling

2015-01-01

Highlights: • A parameter to indicate the energy efficiency ratio of PCTES units is defined. • The characteristics of the energy efficiency ratio of PCTES units are reported. • A combined parameter of the physical properties of the working mediums is found. • Some implications of the energy efficiency ratio in design of PCTES units are analyzed. - Abstract: From aspect of energy consuming to pump heat transfer fluid, there is no sound basis on which to create an optimum design of a thermal energy storage unit. Thus, it is necessary to develop a parameter to indicate the energy efficiency of such unit. This paper firstly defines a parameter that indicates the ratio of heat storage of phase change thermal energy storage unit to energy consumed in pumping heat transfer fluid, which is called the energy efficiency ratio, then numerically investigates the characteristics of this parameter. The results show that the energy efficiency ratio can clearly indicate the energy efficiency of a phase change thermal energy storage unit. When the fluid flow of a heat transfer fluid is in a laminar state, the energy efficiency ratio is larger than in a turbulent state. The energy efficiency ratio of a shell-and-tube phase change thermal energy storage unit is more sensitive to the outer tube diameter. Under the same working conditions, within the heat transfer fluids studied, the heat storage property of the phase change thermal energy storage unit is best for water as heat transfer fluid. A combined parameter is found to indicate the effects of both the physical properties of phase change material and heat transfer fluid on the energy efficiency ratio

Thermal Efficiency of Cogeneration Units with Multi-Stage Reheating for Russian Municipal Heating Systems

Directory of Open Access Journals (Sweden)

Evgeny Lisin

2016-04-01

Full Text Available This paper explores the layout of an optimum process for supplying heat to Russian municipal heating systems operating in a market environment. We analyze and compare the standard cogeneration unit design with two-stage reheating of service water coming from controlled extraction locations and layouts that employ three in-line reheaters with heat the supply controlled by a rotary diaphragm and qualitative/quantitative methods (so-called “uncontrolled extraction”. Cogeneration unit designs are benchmarked in terms of their thermal efficiency expressed as a fuel consumption rate. The specific fuel consumption rate on electricity production is viewed as a key parameter of thermal efficiency.

Heat transfer and thermal storage performance of an open thermosyphon type thermal storage unit with tubular phase change material canisters

International Nuclear Information System (INIS)

Wang, Ping-Yang; Hu, Bo-Wen; Liu, Zhen-Hua

2015-01-01

Highlights: • A novel open heat pipe thermal storage unit is design to improve its performance. • Mechanism of its operation is phase-change heat transfer. • Tubular canisters with phase change material were placed in thermal storage unit. • Experiment and analysis are carried out to investigate its operation properties. - Abstract: A novel open thermosyphon-type thermal storage unit is presented to improve design and performance of heat pipe type thermal storage unit. In the present study, tubular canisters filled with a solid–liquid phase change material are vertically placed in the middle of the thermal storage unit. The phase change material melts at 100 °C. Water is presented as the phase-change heat transfer medium of the thermal storage unit. The tubular canister is wrapped tightly with a layer of stainless steel mesh to increase the surface wettability. The heat transfer mechanism of charging/discharging is similar to that of the thermosyphon. Heat transfer between the heat resource or cold resource and the phase change material in this device occurs in the form of a cyclic phase change of the heat-transfer medium, which occurs on the surface of the copper tubes and has an extremely high heat-transfer coefficient. A series of experiments and theoretical analyses are carried out to investigate the properties of the thermal storage unit, including power distribution, start-up performance, and temperature difference between the phase change material and the surrounding vapor. The results show that the whole system has excellent heat-storage/heat-release performance

Linking Excessive Heat with Daily Heat-Related Mortality over the Coterminous United States

Science.gov (United States)

Quattrochi, Dale A.; Crosson, William L.; Al-Hamdan, Mohammad Z.; Estes, Maurice G., Jr.

2014-01-01

In the United States, extreme heat is the most deadly weather-related hazard. In the face of a warming climate and urbanization, which contributes to local-scale urban heat islands, it is very likely that extreme heat events (EHEs) will become more common and more severe in the U.S. This research seeks to provide historical and future measures of climate-driven extreme heat events to enable assessments of the impacts of heat on public health over the coterminous U.S. We use atmospheric temperature and humidity information from meteorological reanalysis and from Global Climate Models (GCMs) to provide data on past and future heat events. The focus of research is on providing assessments of the magnitude, frequency and geographic distribution of extreme heat in the U.S. to facilitate public health studies. In our approach, long-term climate change is captured with GCM outputs, and the temporal and spatial characteristics of short-term extremes are represented by the reanalysis data. Two future time horizons for 2040 and 2090 are compared to the recent past period of 1981- 2000. We characterize regional-scale temperature and humidity conditions using GCM outputs for two climate change scenarios (A2 and A1B) defined in the Special Report on Emissions Scenarios (SRES). For each future period, 20 years of multi-model GCM outputs are analyzed to develop a 'heat stress climatology' based on statistics of extreme heat indicators. Differences between the two future and the past period are used to define temperature and humidity changes on a monthly time scale and regional spatial scale. These changes are combined with the historical meteorological data, which is hourly and at a spatial scale (12 km) much finer than that of GCMs, to create future climate realizations. From these realizations, we compute the daily heat stress measures and related spatially-specific climatological fields, such as the mean annual number of days above certain thresholds of maximum and minimum air

Engineering task plan for purged light system

International Nuclear Information System (INIS)

BOGER, R.M.

1999-01-01

A purged, closed circuit television system is currently used to video inside of waste tanks. The video is used to support inspection and assessment of the tank interiors, waste residues, and deployed hardware. The system is also used to facilitate deployment of new equipment. A new light source has been requested by Characterization Project Operations (CPO) for the video system. The current light used is mounted on the camera and provides 75 watts of light, which is insufficient for clear video. Other light sources currently in use on the Hanford site either can not be deployed in a 4-inch riser or do not meet the ignition source controls. The scope of this Engineering Task Plan is to address all activities associated with the specification and procurement of a light source for use with the existing CPO video equipment. The installation design change to tank farm facilities is not within the scope of this ETP

An investigation of the joint longitudinal trajectories of low body weight, binge eating, and purging in women with anorexia nervosa and bulimia nervosa

Science.gov (United States)

Lavender, Jason M.; De Young, Kyle P.; Franko, Debra L.; Eddy, Kamryn T.; Kass, Andrea E.; Sears, Meredith S.; Herzog, David B.

2015-01-01

Objectives To describe the longitudinal course of three core eating disorder symptoms – low body weight, binge eating, and purging – in women with anorexia nervosa (AN) and bulimia nervosa (BN) using a novel statistical approach. Method Treatment-seeking women with AN (n=136) or BN (n=110) completed the Eating Disorders Longitudinal Interval Follow-Up Evaluation interview every six months, yielding weekly eating disorder symptom data for a five-year period. Semi-parametric mixture modeling was used to identify longitudinal trajectories for the three core symptoms. Results Four individual trajectories were identified for each eating disorder symptom. The number and general shape of the individual trajectories was similar across symptoms, with each model including trajectories depicting stable absence and stable presence of symptoms as well as one or more trajectories depicting the declining presence of symptoms. Unique trajectories were found for low body weight (fluctuating presence) and purging (increasing presence). Conjunction analyses yielded the following joint trajectories: low body weight and binge eating, low body weight and purging, and binge eating and purging. Conclusions The course of individual eating disorder symptoms among patients with AN and BN is highly variable. Future research identifying clinical predictors of trajectory membership may inform treatment and nosological research. PMID:22072404

An investigation of the joint longitudinal trajectories of low body weight, binge eating, and purging in women with anorexia nervosa and bulimia nervosa.

Science.gov (United States)

Lavender, Jason M; De Young, Kyle P; Franko, Debra L; Eddy, Kamryn T; Kass, Andrea E; Sears, Meredith S; Herzog, David B

2011-12-01

To describe the longitudinal course of three core eating disorder symptoms-low body weight, binge eating, and purging-in women with anorexia nervosa (AN) and bulimia nervosa (BN) using a novel statistical approach. Treatment-seeking women with AN (n = 136) or BN (n = 110) completed the Eating Disorders Longitudinal Interval Follow-Up Evaluation interview every 6 months, yielding weekly eating disorder symptom data for a 5-year period. Semiparametric mixture modeling was used to identify longitudinal trajectories for the three core symptoms. Four individual trajectories were identified for each eating disorder symptom. The number and general shape of the individual trajectories was similar across symptoms, with each model including trajectories depicting stable absence and stable presence of symptoms as well as one or more trajectories depicting the declining presence of symptoms. Unique trajectories were found for low body weight (fluctuating presence) and purging (increasing presence). Conjunction analyses yielded the following joint trajectories: low body weight and binge eating, low body weight and purging, and binge eating and purging. The course of individual eating disorder symptoms among patients with AN and BN is highly variable. Future research identifying clinical predictors of trajectory membership may inform treatment and nosological research. Copyright © 2010 Wiley Periodicals, Inc.

Determination of (4-methylcyclohexyl)methanol isomers by heated purge-and-trap GC/MS in water samples from the 2014 Elk River, West Virginia, chemical spill

Science.gov (United States)

Foreman, William T.; Rose, Donna L.; Chambers, Douglas B.; Crain, Angela S.; Murtagh, Lucinda K.; Thakellapalli, Haresh; Wang, Kung K.

2015-01-01

A heated purge-and-trap gas chromatography/mass spectrometry method was used to determine the cis- and trans-isomers of (4-methylcyclohexyl)methanol (4-MCHM), the reported major component of the Crude MCHM/Dowanol™ PPh glycol ether material spilled into the Elk River upriver from Charleston, West Virginia, on January 9, 2014. The trans-isomer eluted first and method detection limits were 0.16-μg L−1trans-, 0.28-μg L−1cis-, and 0.4-μg L−1 Total (total response of isomers) 4-MCHM. Estimated concentrations in the spill source material were 491-g L−1trans- and 277-g L−1cis-4-MCHM, the sum constituting 84% of the source material assuming its density equaled 4-MCHM. Elk River samples collected ⩽ 3.2 km downriver from the spill on January 15 had low (⩽2.9 μg L−1 Total) 4-MCHM concentrations, whereas the isomers were not detected in samples collected 2 d earlier at the same sites. Similar 4-MCHM concentrations (range 4.2–5.5 μg L−1 Total) occurred for samples of the Ohio River at Louisville, Kentucky, on January 17, ∼630 km downriver from the spill. Total 4-MCHM concentrations in Charleston, WV, office tap water decreased from 129 μg L−1 on January 27 to 2.2 μg L−1on February 3, but remained detectable in tap samples through final collection on February 25 indicating some persistence of 4-MCHM within the water distribution system. One isomer of methyl 4-methylcyclohexanecarboxylate was detected in all Ohio River and tap water samples, and both isomers were detected in the source material spilled.

Energy Savings and Breakeven Costs for Residential Heat Pump Water Heaters in the United States

Energy Technology Data Exchange (ETDEWEB)

Maguire, Jeff [National Renewable Energy Lab. (NREL), Golden, CO (United States); Burch, Jay [National Renewable Energy Lab. (NREL), Golden, CO (United States); Merrigan, Tim [National Renewable Energy Lab. (NREL), Golden, CO (United States); Ong, Sean [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2013-07-01

Heat pump water heaters (HPWHs) have recently re-emerged in the U.S. residential water heating market and have the potential to provide homeowners with significant energy savings. However, there are questions as to the actual performance and energy savings potential of these units, in particular in regards to the heat pump's performance in unconditioned space and the impact of the heat pump on space heating and cooling loads when it is located in conditioned space. To help answer these questions, NREL performed simulations of a HPWH in both conditioned and unconditioned space at over 900 locations across the continental United States and Hawaii. Simulations included a Building America benchmark home so that any interaction between the HPWH and the home's HVAC equipment could be captured. Comparisons were performed to typical gas and electric water heaters to determine the energy savings potential and cost effectiveness of a HPWH relative to these technologies. HPWHs were found to have a significant source energy savings potential when replacing typical electric water heaters, but only saved source energy relative to gas water heater in the most favorable installation locations in the southern United States. When replacing an electric water heater, the HPWH is likely to break even in California, the southern United States, and parts of the northeast in most situations. However, the HPWH will only break even when replacing a gas water heater in a few southern states.

Heating great residential units with combustion-motor heat pumps

Energy Technology Data Exchange (ETDEWEB)

Vossen, W

1982-10-01

Economic usage of combustion-motor heat pumps requires: reliable technology and delivery of the heat pump; design and operation. The heat pump must be integrated perfectly into the heating system. This contributions is based on a three-year operational experience with over 150 heat pumps used mainly in residential and administrative buildings (plus commercial buildings, swimming pools, sport centres etc.). These are heat pumps operating on the compression principle with natural gas, liquid gas, or fuel oil.

Performance analysis of phase-change material storage unit for both heating and cooling of buildings

Science.gov (United States)

Waqas, Adeel; Ali, Majid; Ud Din, Zia

2017-04-01

Utilisation of solar energy and the night ambient (cool) temperatures are the passive ways of heating and cooling of buildings. Intermittent and time-dependent nature of these sources makes thermal energy storage vital for efficient and continuous operation of these heating and cooling techniques. Latent heat thermal energy storage by phase-change materials (PCMs) is preferred over other storage techniques due to its high-energy storage density and isothermal storage process. The current study was aimed to evaluate the performance of the air-based PCM storage unit utilising solar energy and cool ambient night temperatures for comfort heating and cooling of a building in dry-cold and dry-hot climates. The performance of the studied PCM storage unit was maximised when the melting point of the PCM was ∼29°C in summer and 21°C during winter season. The appropriate melting point was ∼27.5°C for all-the-year-round performance. At lower melting points than 27.5°C, declination in the cooling capacity of the storage unit was more profound as compared to the improvement in the heating capacity. Also, it was concluded that the melting point of the PCM that provided maximum cooling during summer season could be used for winter heating also but not vice versa.

The loss of essential oil components induced by the Purge Time in the Pressurized Liquid Extraction (PLE) procedure of Cupressus sempervirens.

Science.gov (United States)

Dawidowicz, Andrzej L; Czapczyńska, Natalia B; Wianowska, Dorota

2012-05-30

The influence of different Purge Times on the effectiveness of Pressurized Liquid Extraction (PLE) of volatile oil components from cypress plant matrix (Cupressus sempervirens) was investigated, applying solvents of diverse extraction efficiencies. The obtained results show the decrease of the mass yields of essential oil components as a result of increased Purge Time. The loss of extracted components depends on the extrahent type - the greatest mass yield loss occurred in the case of non-polar solvents, whereas the smallest was found in polar extracts. Comparisons of the PLE method with Sea Sand Disruption Method (SSDM), Matrix Solid-Phase Dispersion Method (MSPD) and Steam Distillation (SD) were performed to assess the method's accuracy. Independent of the solvent and Purge Time applied in the PLE process, the total mass yield was lower than the one obtained for simple, short and relatively cheap low-temperature matrix disruption procedures - MSPD and SSDM. Thus, in the case of volatile oils analysis, the application of these methods is advisable. Copyright © 2012 Elsevier B.V. All rights reserved.

He II Heat Exchanger Test Unit for the LHC Inner Triplet

CERN Document Server

Blanco-Viñuela, E; Huang, Y; Nicol, T H; Peterson, T; Van Weelderen, R

2002-01-01

The Inner Triplet Heat Exchanger Test Unit (IT-HXTU) is a 30-m long thermal model designed at Fermilab, built in US industry, fully automated and tested at CERN as part of the US LHC program to develop the LHC Interaction Region quadrupole system. The cooling scheme of the IT-HXTU is based on heat exchange between stagnant pressurized He II in the magnet cold mass and saturated He II (two-phase) flowing in a heat exchanger located outside of and parallel to the cold mass. The purposes of this test are, among others, to validate the proposed cooling scheme and to define an optimal control strategy to be implemented in the future LHC accelerator. This paper discusses the results for the heat exchanger test runs and emphasizes the thermal and hydraulic behavior of He II for the inner triplet cooling scheme.

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)

Development of the heat treatment system for the 40 T hybrid magnet superconducting outsert.

Science.gov (United States)

Chen, W G; Chen, Z M; Chen, Z Y; Huang, P C; He, P; Zhu, J W

2011-10-01

The heat treatment of Nb(3)Sn coil with the glass fabric insulation is one of the key and critical processes for the outsert solenoids of the 40 T hybrid magnet, which could be wound with cable-in-conduit conductors using the insulation-wind-and-react technique. The manufacturing of the large vertical type vacuum/Ar atmosphere-protection heat treatment system has been completed and recently installed in the High Magnetic Filed Laboratory, Chinese Academy of Sciences. The heat treatment system composed mainly the furnace, the purging gas supply system, the control system, the gas impurities monitoring system, and so on. At present, the regulation and testing of the heat treatment system has been successfully finished, and all of technical parameters meet or exceed specifications.

Comparison of Advanced Residential Water Heating Technologies in the United States

Energy Technology Data Exchange (ETDEWEB)

Maguire, Jeff [National Renewable Energy Lab. (NREL), Golden, CO (United States); Fang, Xia [National Renewable Energy Lab. (NREL), Golden, CO (United States); Wilson, Eric [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2013-05-01

In this study, gas storage, gas tankless, condensing, electric storage, heat pump, and solar water heaters were simulated in several different climates across the United States, installed in both conditioned and unconditioned space and subjected to several different draw profiles. While many pre-existing models were used, new models of condensing and heat pump water heaters were created specifically for this work. In each case modeled, the whole house was simulated along with the water heater to capture any interactions between the water heater and the space conditioning equipment.

Krohne Flow Indicator and High Flow Alarm - Local Indicator and High Flow Alarm of Helium Flow from the SCHe Purge Lines C and D to the Process Vent

International Nuclear Information System (INIS)

MISKA, C.R.

2000-01-01

Flow Indicators/alarms FI/FSH-5*52 and -5*72 are located in the process vent lines connected to the 2 psig SCHe purge lines C and D. They monitor the flow from the 2 psig SCHe purge going to the process vent. The switch/alarm is non-safety class GS

Purging of acute myeloid leukaemia cells from stem cell grafts by hyperthermia : enhancement of the therapeutic index by the tetrapeptide AcSDKP and the alkyl-lysophospholipid ET-18-OCH3

NARCIS (Netherlands)

Wierenga, PK; Setroikromo, R; Vellenga, E; Kampinga, HH

2000-01-01

Hyperthermia has been shown to be a potential purging modality in autologous stem cell transplantation settings owing to its selective toxicity towards leukaemic cells, We describe two approaches to further increase the therapeutic index of the hyperthermic purging modality by using normal murine

A basic study on Thermosyphon-type thermal storage unit (TSU) using Nanofluid as the heat transfer medium

Science.gov (United States)

Li, Shuang-Fei; Wang, Ping-Yang; Liu, Zhen-hua

2018-05-01

This study proposed a novel thermosyphon-type thermal storage unit using water-based CuO nanofluid as the phase-change heat transfer medium. Seven tubular canisters containing solid-liquid phase-change material (PCM) with peak melting temperature of 100 °C were placed vertically into the center of the TSU which is a vertical cylindrical vessel made of stainless steel. Coat formed by depositing nanoparticles during the phase-change process was adopted to increase the wettability of the heat transfer surfaces of the canisters. We investigated the phase-change heat transfer, as well as the heat-storage and heat-release properties, of the TSU through experimental and computational analysis. Our results demonstrate that this thermal storage unit construction can propose good heat transfer and heat-storage/heat-release performance. The coating of nanoparticles onto the heat transfer surfaces increases the surface wettability and improves both the evaporation and condensation heat transfer. The main thermal resistance in the TSU results from the conductive heat transfer inside of the PCM. All phase-change thermal resistance of liquid film in charging and discharging processes can be ignored in this TSU.

A basic study on Thermosyphon-type thermal storage unit (TSU) using Nanofluid as the heat transfer medium

Science.gov (United States)

Li, Shuang-Fei; Wang, Ping-Yang; Liu, Zhen-hua

2017-11-01

This study proposed a novel thermosyphon-type thermal storage unit using water-based CuO nanofluid as the phase-change heat transfer medium. Seven tubular canisters containing solid-liquid phase-change material (PCM) with peak melting temperature of 100 °C were placed vertically into the center of the TSU which is a vertical cylindrical vessel made of stainless steel. Coat formed by depositing nanoparticles during the phase-change process was adopted to increase the wettability of the heat transfer surfaces of the canisters. We investigated the phase-change heat transfer, as well as the heat-storage and heat-release properties, of the TSU through experimental and computational analysis. Our results demonstrate that this thermal storage unit construction can propose good heat transfer and heat-storage/heat-release performance. The coating of nanoparticles onto the heat transfer surfaces increases the surface wettability and improves both the evaporation and condensation heat transfer. The main thermal resistance in the TSU results from the conductive heat transfer inside of the PCM. All phase-change thermal resistance of liquid film in charging and discharging processes can be ignored in this TSU.

Experimental investigations on prototype heat storage units utilizing stable supercooling of sodium acetate trihydrate mixtures

DEFF Research Database (Denmark)

Dannemand, Mark; Dragsted, Janne; Fan, Jianhua

2016-01-01

Laboratory tests of two heat storage units based on the principle of stable supercooling of sodium acetate trihydrate (SAT) mixtures were carried out. One unit was filled with 199.5 kg of SAT with 9% extra water to avoid phase separation of the incongruently melting salt hydrate. The other unit...

Modeling and simulation of ammonia removal from purge gases of ammonia plants using a catalytic Pd-Ag membrane reactor

International Nuclear Information System (INIS)

Rahimpour, M.R.; Asgari, A.

2008-01-01

In this work, the removal of ammonia from synthesis purge gas of an ammonia plant has been investigated. Since the ammonia decomposition is thermodynamically limited, a membrane reactor is used for complete decomposition. A double pipe catalytic membrane reactor is used to remove ammonia from purge gas. The purge gas is flowing in the reaction side and is converted to hydrogen and nitrogen over nickel-alumina catalyst. The hydrogen is transferred through the Pd-Ag membrane of tube side to the shell side. A mathematical model including conservation of mass in the tube and shell side of reactor is proposed. The proposed model was solved numerically and the effects of different parameters on the rector performance were investigated. The effects of pressure, temperature, flow rate (sweep ratio), membrane thickness and reactor diameter have been investigated in the present study. Increasing ammonia conversion was observed by raising the temperature, sweep ratio and reducing membrane thickness. When the pressure increases, the decomposition is gone toward completion but, at low pressure the ammonia conversion in the outset of reactor is higher than other pressures, but complete destruction of the ammonia cannot be achieved. The proposed model can be used for design of an industrial catalytic membrane reactor for removal of ammonia from ammonia plant and reducing NO x emissions

Thermal Analysis of a Thermal Energy Storage Unit to Enhance a Workshop Heating System Driven by Industrial Residual Water

Directory of Open Access Journals (Sweden)

Wenqiang Sun

2017-02-01

Full Text Available Various energy sources can be used for room heating, among which waste heat utilization has significantly improved in recent years. However, the majority of applicable waste heat resources are high-grade or stable thermal energy, while the low-grade or unstable waste heat resources, especially low-temperature industrial residual water (IRW, are insufficiently used. A thermal energy storage (TES unit with paraffin wax as a phase change material (PCM is designed to solve this problem in a pharmaceutical plant. The mathematical models are developed to simulate the heat storage and release processes of the TES unit. The crucial parameters in the recurrence formulae are determined: the phase change temperature range of the paraffin wax used is 47 to 56 °C, and the latent heat is 171.4 kJ/kg. Several thermal behaviors, such as the changes of melting radius, solidification radius, and fluid temperature, are simulated. In addition, the amount of heat transferred, the heat transfer rate, and the heat storage efficiency are discussed. It is presented that the medicine production unit could save 10.25% of energy consumption in the investigated application.

Early emergence of anthropogenically forced heat waves in the western United States and Great Lakes

Science.gov (United States)

Lopez, Hosmay; West, Robert; Dong, Shenfu; Goni, Gustavo; Kirtman, Ben; Lee, Sang-Ki; Atlas, Robert

2018-05-01

Climate projections for the twenty-first century suggest an increase in the occurrence of heat waves. However, the time at which externally forced signals of anthropogenic climate change (ACC) emerge against background natural variability (time of emergence (ToE)) has been challenging to quantify, which makes future heat-wave projections uncertain. Here we combine observations and model simulations under present and future forcing to assess how internal variability and ACC modulate US heat waves. We show that ACC dominates heat-wave occurrence over the western United States and Great Lakes regions, with ToE that occurred as early as the 2020s and 2030s, respectively. In contrast, internal variability governs heat waves in the northern and southern Great Plains, where ToE occurs in the 2050s and 2070s; this later ToE is believed to be a result of a projected increase in circulation variability, namely the Great Plain low-level jet. Thus, greater mitigation and adaptation efforts are needed in the Great Lakes and western United States regions.

Experimental investigations on cylindrical latent heat storage units with sodium acetate trihydrate composites utilizing supercooling

DEFF Research Database (Denmark)

Dannemand, Mark; Johansen, Jakob Berg; Kong, Weiqiang

2016-01-01

unit was tested with 116.3 kg SAT with 0.5% Xanthan rubber as a thickening agent and 4.4% graphite powder. The heat exchange capacity rate during charge was significantly lower for the unit with SAT and Xanthan rubber compared to the unit with SAT and extra water. This was due to less convection...

Quantification of prominent volatile compounds responsible for muskmelon and watermelon aroma by purge and trap extraction followed by gas chromatography-mass spectrometry determination.

Science.gov (United States)

Fredes, Alejandro; Sales, Carlos; Barreda, Mercedes; Valcárcel, Mercedes; Roselló, Salvador; Beltrán, Joaquim

2016-01-01

A dynamic headspace purge-and-trap (DHS-P&T) methodology for the determination and quantification of 61 volatile compounds responsible for muskmelon and watermelon aroma has been developed and validated. The methodology is based on the application of purge-and-trap extraction followed by gas chromatography coupled to (ion trap) mass spectrometry detection. For this purpose two different P&T sorbent cartridges have been evaluated. The influence of different extraction factors (sample weight, extraction time, and purge flow) on extraction efficiency has been studied and optimised using response surface methodology. Precision, expressed as repeatability, has been evaluated by analysing six replicates of real samples, showing relative standard deviations between 3% and 27%. Linearity has been studied in the range of 10-6130 ng mL(-1) depending on the compound response, showing coefficients of correlation between 0.995 and 0.999. Detection limits ranged between 0.1 and 274 ng g(-1). The methodology developed is well suited for analysis of large numbers of muskmelon and watermelon samples in plant breeding programs. Copyright © 2015 Elsevier Ltd. All rights reserved.

Incorporation of Condensation Heat Transfer in a Flow Network Code

Science.gov (United States)

Anthony, Miranda; Majumdar, Alok

2002-01-01

Pure water is distilled from waste water in the International Space Station. The distillation assembly consists of an evaporator, a compressor and a condenser. Vapor is periodically purged from the condenser to avoid vapor accumulation. Purged vapor is condensed in a tube by coolant water prior to entering the purge pump. The paper presents a condensation model of purged vapor in a tube. This model is based on the Finite Volume Method. In the Finite Volume Method, the flow domain is discretized into multiple control volumes and a simultaneous analysis is performed.

Reciprocal associations between negative affect, binge eating, and purging in the natural environment in women with bulimia nervosa.

Science.gov (United States)

Lavender, Jason M; Utzinger, Linsey M; Cao, Li; Wonderlich, Stephen A; Engel, Scott G; Mitchell, James E; Crosby, Ross D

2016-04-01

Although negative affect (NA) has been identified as a common trigger for bulimic behaviors, findings regarding NA following such behaviors have been mixed. This study examined reciprocal associations between NA and bulimic behaviors using real-time, naturalistic data. Participants were 133 women with bulimia nervosa (BN) according to the 4th edition of the Diagnostic and Statistical Manual of Mental Disorders who completed a 2-week ecological momentary assessment protocol in which they recorded bulimic behaviors and provided multiple daily ratings of NA. A multilevel autoregressive cross-lagged analysis was conducted to examine concurrent, first-order autoregressive, and prospective associations between NA, binge eating, and purging across the day. Results revealed positive concurrent associations between all variables across all time points, as well as numerous autoregressive associations. For prospective associations, higher NA predicted subsequent bulimic symptoms at multiple time points; conversely, binge eating predicted lower NA at multiple time points, and purging predicted higher NA at 1 time point. Several autoregressive and prospective associations were also found between binge eating and purging. This study used a novel approach to examine NA in relation to bulimic symptoms, contributing to the existing literature by directly examining the magnitude of the associations, examining differences in the associations across the day, and controlling for other associations in testing each effect in the model. These findings may have relevance for understanding the etiology and/or maintenance of bulimic symptoms, as well as potentially informing psychological interventions for BN. (c) 2016 APA, all rights reserved).

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

International Nuclear Information System (INIS)

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

2014-01-01

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

A Direct Heat Exchanger Unit used for Domestic Hot Water Supply in a Single-family House Supplied by Low Energy District Heating

DEFF Research Database (Denmark)

Brand, Marek; Thorsen, Jan Eric; Svendsen, Svend

2010-01-01

The increasing number of new and renovated buildings with reduced heating requirements will soon make traditional District Heating (DH) systems uneconomic. To keep DH competitive in the future, the heat loss in DH networks needs to be reduced. One option is to reduce the supply temperature of DH...... as much as possible. This requires a review of the behaviour of the whole domestic hot water (DHW) supply system with focus on the user comfort and overall costs. This paper describes some practical approaches to the implementation of this Low Energy District Heating (LEDH) concept. It reports...... on the testing of the dynamic behaviour of an Instantaneous Heat Exchanger Unit(IHEU) designed for DHW heating and space heating in detached family houses supplied by LEDH ensuring an entry-to-substation temperature of 51 °C. We measured the time it takes for the IHEU to produce DHW with a temperature of 42 °C...

A purge-and-trap capillary column gas chromatographic method for the measurement of halocarbons in water and air

Energy Technology Data Exchange (ETDEWEB)

Happell, J.D.; Wallace, D.W.R.; Wills, K.D.; Wilke, R.J.; Neill, C.C.

1996-06-01

This report describes an automated, accurate, precise and sensitive capillary column purge- and -trap method capable of quantifying CFC-12, CFC-11, CFC-113, CH{sub 3}CCL{sub 3}, and CCL{sub 4} during a single chromatographic analysis in either water or gas phase samples.

Experimental characterization, modeling and simulation of a wood pellet micro-combined heat and power unit used as a heat source for a residential building

Energy Technology Data Exchange (ETDEWEB)

Thiers, Stephane; Aoun, Bernard; Peuportier, Bruno [MINES ParisTech, CEP - Centre Energetique et Procedes, 60 Boulevard St Michel, 75272 Paris Cedex 06 (France)

2010-06-15

Cogeneration provides heat and power in a more efficient way than separate production. Micro-cogeneration (micro-CHP) is an emerging solution for the improvement of energy and environmental assessments of residential buildings. A wood pellet Stirling engine micro-CHP unit has been studied in order to characterize its annual performance when integrated to a building. First, through a test bench experiment, both transient and steady state behaviors of the micro-CHP unit have been characterized and modeled. Then a more complete model representing a hot water and heating system including the micro-CHP unit and a stratified storage tank has been carried out. This model has been coupled to a building model. A sensitivity analysis by simulation shows that the dimensioning of different elements of the system strongly influences its global energy performance. (author)

Frequency of deflagration in the in-tank precipitation process tanks due to loss of nitrogen purge system

International Nuclear Information System (INIS)

Jansen, J.M.; Mason, C.L.; Olsen, L.M.; Shapiro, B.J.; Gupta, M.K.; Britt, T.E.

1994-01-01

High-level liquid wastes (HLLW) from the processing of nuclear material at the Savannah River Site (SRS) are stored in large tanks in the F- and H-Area tank farms. The In-Tank Precipitation (ITP) process is one step in the processing and disposal of HLLW. The process hazards review for the ITP identified the need to implement provisions that minimize deflagration/explosion hazards associated with the process. The objective of this analysis is to determine the frequency of a deflagration in Tank 48 and/or 49 due to nitrogen purge system failures (including external events) and coincident ignition source. A fault tree of the nitrogen purge system coupled with ignition source probability is used to identify dominant system failures that contribute to the frequency of deflagration. These system failures are then used in the recovery analysis. Several human actions, recovery actions, and repair activities are identified that reduce total frequency. The actions are analyzed and quantified as part of a Human Reliability Analysis (HRA). The probabilities of failure of these actions are applied to the fault tree cutsets and the event trees

Characterization of a Gas-Purge Method to Access 11C-Carbon-Dioxide Radioactivity in Blood

International Nuclear Information System (INIS)

Ng, Y.; Green, M.A.

2014-01-01

Carbon-11 (t 1/2 : 20 minutes) labeled radiotracers, such as 11 C-acetate and 11 C-palmitate are widely used in positron emission tomography (PET) for noninvasive evaluation of myocardial metabolism under varied physiological conditions. These tracers are attractive probes of tissue physiology, because they are simply radiolabeled versions of the native biochemical substrates. One of the major metabolites generated by these tracers upon the administration is 11 CO 2 produced via the citric acid cycle. In quantitative modeling of 11 C-acetate and 11 C-palmitate PET data, the fraction of blood 11 C radioactivity present as 11 CO 2 needs to be measured to obtain a correct radiotracer arterial input function. Accordingly, the literature describes a method whereby the total blood 11 C-activity is counted in blood samples treated with base solution, while the fraction of 11 CO 2 is measured after the blood is treated with acid followed by a 10 minutes gas-purge. However, a detailed description of the experimental validation of this method was not provided. The goal of this study was to test the reliability of a 10-minute gas purging method used to assay 11 CO 2 radioactivity in blood. (author)

Exertional heat stroke management strategies in United States high school football.

Science.gov (United States)

Kerr, Zachary Y; Marshall, Stephen W; Comstock, R Dawn; Casa, Douglas J

2014-01-01

The 5-year period of 2005-2009 saw more exertional heat stroke-related deaths in organized sports than any other 5-year period in the past 35 years. The risk of exertional heat stroke appears highest in football, particularly during the preseason. To estimate the incidence of exertional heat stroke events and assess the utilization of exertional heat stroke management strategies during the 2011 preseason in United States high school football programs. Cross-sectional study; Level of evidence, 3. A self-administered online questionnaire addressing the incidence of exertional heat stroke events and utilization of exertional heat stroke management strategies (eg, removing athlete's football equipment, calling Emergency Medical Services [EMS]) was completed in May to June 2012 by 1142 (18.0%) athletic trainers providing care to high school football athletes during the 2011 preseason. Among all respondents, 20.3% reported treating at least 1 exertional heat stroke event. An average of 0.50 ± 1.37 preseason exertional heat stroke events were treated per program. Athletic trainers responding to exertional heat stroke reported using an average of 6.6 ± 1.8 management strategies. The most common management strategies were low-level therapeutic interventions such as removing the athlete's football equipment (98.2%) and clothing (77.8%) and moving the athlete to a shaded area (91.6%). Few athletic trainers reported active management strategies such as calling EMS (29.3%) or using a rectal thermometer to check core body temperature (0.9%). Athletic trainers in states with mandated preseason heat acclimatization guidelines reported a higher utilization of management strategies such as cooling the athlete through air conditioning (90.1% vs 65.0%, respectively; P football programs. The standard of care is (and should be) to treat proactively; therefore, treatment is not a perfect proxy for incidence. Nevertheless, there is an urgent need for improved education and awareness of

HEAT STORAGE SYSTEM WITH PHASE CHANGE MATERIALS IN COGENERATION UNITS: STUDY OF PRELIMINARY MODEL

Directory of Open Access Journals (Sweden)

Claudio Caprara

2008-12-01

Full Text Available The continuous increase in the mechanization of farm activities, the rise in fuel prices and the environmental aspects concerning gas emissions are the main driving forces behind efforts toward more effective use of renewable energy sources and cogeneration systems even in agricultural and cattle farms. Nevertheless these systems are still not very suitable for this purpose because of their little flexibility in following the changing energy demand as opposed to the extremely various farm load curves, both in daytime and during the year. In heat recovery systems, the available thermal energy supply is always linked to power production, thus it does not usually coincide in time with the heat demand. Hence some form of thermal energy storage (TES is necessary in order to reach the most effective utilization of the energy source. This study deals with the modelling of a packed bed latent heat TES unit, integrating a cogeneration system made up of a reciprocating engine. The TES unit contains phase change materials (PCMs filled in spherical capsules, which are packed in an insulated cylindrical storage tank. Water is used as heat transfer fluid (HTF to transfer heat from the tank to the final uses, and exhausts from the engine are used as thermal source. PCMs are considered especially for their large heat storage capacity and their isothermal behaviour during the phase change processes. Despite their high energy storage density, most of them have an unacceptably low thermal conductivity, hence PCMs encapsulation technique is adopted in order to improve heat transfer. The special modular configuration of heat exchange tubes and the possibility of changing water flow through them allow to obtain the right amount of thermal energy from the tank, according to the hourly demand of the day. The model permits to choose the electrical load of the engine, the dimensions of the tank and the spheres, thickness and diameter of heat exchanger and the nature of

Heat recovery from a cement plant with a Marnoch Heat Engine

International Nuclear Information System (INIS)

Saneipoor, P.; Naterer, G.F.; Dincer, I.

2011-01-01

This paper examines the performance of a new Marnoch Heat Engine (MHE) that recovers waste heat from within a typical cement plant. Two MHE units with compressed air as the working fluid are installed to recover the waste heat. The first unit on the main stack has four pairs of shell and tube heat exchangers. The second heat recovery unit is installed on a clinker quenching system. This unit operates with three pairs of shell and tube heat exchangers. The recovered heat is converted to electricity through the MHE system and used internally within the cement plant. A predictive model and results are presented and discussed. The results show the promising performance of the MHE's capabilities for efficient generation of electricity from waste heat sources in a cement plant. The new heat recovery system increases the efficiency of the cement plant and lowers the CO 2 emissions from the clinker production process. Moreover, it reduces the amount of waste heat to the environment and lowers the temperature of the exhaust gases. - Highlights: → This paper examines the thermodynamic performance of a new Marnoch Heat Engine (MHE) that recovers waste heat to produce electricity and improve the operating efficiency of a typical cement plant. → The first unit of the MHE on the main stack has four pairs of shell and tube heat exchangers and the second heat recovery unit is installed on a clinker quenching system. → Both predicted and experimental results demonstrate the promising performance of the MHE's capabilities for efficient generation of electricity from waste heat sources in a cement plant.

District space heating potential of low temperature hydrothermal geothermal resources in the southwestern United States. Technical report

Energy Technology Data Exchange (ETDEWEB)

McDevitt, P.K.; Rao, C.R.

1978-10-01

A computer simulation model (GIRORA-Nonelectric) is developed to study the economics of district space heating using geothermal energy. GIRORA-Nonelectric is a discounted cashflow investment model which evaluates the financial return on investment for space heating. This model consists of two major submodels: the exploration for and development of a geothermal anomaly by a geothermal producer, and the purchase of geothermal fluid by a district heating unit. The primary output of the model is a calculated rate of return on investment earned by the geothermal producer. The results of the sensitivity analysis of the model subject to changes in physical and economic parameters are given in this report. Using the results of the economic analysis and technological screening criteria, all the low temperature geothermal sites in Southwestern United States are examined for economic viability for space heating application. The methodology adopted and the results are given.

HEAT ENGINEERING TESTING OF AIR COOLING UNIT OF HORIZONTAL TYPE

OpenAIRE

Rohachov, Valerii Andriiovych; Semeniako, Oleksandr Volodymyrovych; Лазоренко, Р. О.; Середа, Р. М.; Parafeinyk, Volodymyr Petrovych

2018-01-01

The results of the thermal tests of the section of air cooler, the heat-exchange surface of which is made up of chess package of bimetal finned tubes are presented. The methods of research are presented, the experimental stand is described, the measurement errors are given. The efficiency of the experimental stand and the accuracy of the experimental data on it are confirmed. Proposed to use the stand for researches of air cooling units with other types and sections of finned tubes.

Study of the thermal behavior of a latent heat cold storage unit operating under frosting conditions

International Nuclear Information System (INIS)

Simard, A.P.; Lacroix, M.

2003-01-01

A study is performed of the thermal behavior of a latent heat cold storage unit operating under frosting conditions. This unit is employed to maintain the temperature inside the refrigerated compartment of a truck below 265 K. The system consists of parallel plates filled with a phase change material (PCM) that absorbs heat from the flow of warm moist air. A mathematical model for the system is first presented and, next, validated with numerical and experimental data. It is then exploited to assess the effects of design parameters and operating conditions on the performance of the system. The recommended thickness and distance separating the PCM plates are found to be 50x10 -3 and 30x10 -3 m, respectively. The results indicate that the performance of the unit is enhanced by turbulent air flow in spite of the increased pressure loss and accentuated frost growth. The unit also performs well even when the surrounding relative humidity is 100%

Increases in frontostriatal connectivity are associated with response to dorsomedial repetitive transcranial magnetic stimulation in refractory binge/purge behaviors

Directory of Open Access Journals (Sweden)

Katharine Dunlop

2015-01-01

Conclusions: Enhanced frontostriatal connectivity was associated with responders to dmPFC-rTMS for binge/purge behavior. rTMS caused paradoxical suppression of frontostriatal connectivity in nonresponders. rs-fMRI could prove critical for optimizing stimulation parameters in a future sham-controlled trial of rTMS in disordered eating.

Possibility of using adsorption refrigeration unit in district heating network

Science.gov (United States)

Grzebielec, Andrzej; Rusowicz, Artur; Jaworski, Maciej; Laskowski, Rafał

2015-09-01

Adsorption refrigeration systems are able to work with heat sources of temperature starting with 50 °C. The aim of the article is to determine whether in terms of technical and economic issues adsorption refrigeration equipment can work as elements that produce cold using hot water from the district heating network. For this purpose, examined was the work of the adsorption air conditioning equipment cooperating with drycooler, and the opportunities offered by the district heating network in Warsaw during the summer. It turns out that the efficiency of the adsorption device from the economic perspective is not sufficient for production of cold even during the transitional period. The main problem is not the low temperature of the water supply, but the large difference between the coefficients of performance, COPs, of adsorption device and a traditional compressor air conditioning unit. When outside air temperature is 25 °C, the COP of the compressor type reaches a value of 4.49, whereas that of the adsorption device in the same conditions is 0.14. The ratio of the COPs is 32. At the same time ratio between the price of 1 kWh of electric power and 1 kWh of heat is only 2.85. Adsorption refrigeration equipment to be able to compete with compressor devices, should feature COPads efficiency to be greater than 1.52. At such a low driving temperature and even changing the drycooler into the evaporative cooler it is not currently possible to achieve.

Reactor containment purge and vent valve performance experiments

International Nuclear Information System (INIS)

Hunter, J.A.; Steele, R.; Watkins, J.C.

1985-01-01

Three nuclear-designed butterfly valves typical of those used in domestic nuclear power plant containment purge and vent applications were tested. For a comparison of responses, two eight-inch nominal pipe size valves with differing internal design were tested. For extrapolation insights, a 24-inch nominal pipe size valve was also tested. The valve experiments were performed with various piping configurations and valve disc orientations to the flow, to simulate various installation options in field application. As a standard for comparing the effects of the installation options, testing was also performed in a standard ANSI test section. Test cycles were performed at inlet pressures of 5 to 60 psig, while monitoring numerous test parameters, such as the valve disc position, valve shaft torque, mass flow rate, and the pressure and temperature at multiple locations throughout the test section. An experimental data base was developed to assist in the evaluation of the current analytical methods and to determine the influence of inlet pressure, inlet duct geometry, and valve orientation to the flow media on valve torque requirements, along with any resulting limitations to the extrapolation methods. 2 refs., 15 figs

Heat pipes and heat pipe exchangers for heat recovery systems

Energy Technology Data Exchange (ETDEWEB)

Vasiliev, L L; Grakovich, L P; Kiselev, V G; Kurustalev, D K; Matveev, Yu

1984-01-01

Heat pipes and heat pipe exchangers are of great importance in power engineering as a means of recovering waste heat of industrial enterprises, solar energy, geothermal waters and deep soil. Heat pipes are highly effective heat transfer units for transferring thermal energy over large distance (tens of meters) with low temperature drops. Their heat transfer characteristics and reliable working for more than 10-15 yr permit the design of new systems with higher heat engineering parameters.

Optimal usage of low temperature heat sources to supply district heating by heat pumps

DEFF Research Database (Denmark)

Pieper, Henrik; Ommen, Torben Schmidt; Markussen, Wiebke Brix

2017-01-01

This paper presents a theoretical study on the optimal usage of different low temperature heat sources to supply district heating by heat pumps. The study is based on data for the Copenhagen region. The heat sources were prioritized based on the coefficient of performance calculated for each hour...... and the covered demand of each heat source as well as required peak unit capacity. The results showed that heat pumps using different heat sources yield better performance than a heat pump based on a single one. The performance was influenced by the composition of the different heat sources. It was found that 78......% groundwater, 22% seawater and 0% air resulted in highest COP of 3.33 for the given heat demand. Furthermore, the implementation of rule based short term storage made peak units redundant. The variation in base load capacity showed that heat pumps utilizing the analyzed heat sources could perform very...

Research of the heat exchanging processes running in the heating and hot water supply loops of the coil heat exchangers

Directory of Open Access Journals (Sweden)

Ірина Геннадіївна Шитікова

2016-11-01

Full Text Available The fuel-energy complex research has made it possible to disclose a huge power-saving potential in the municipal heat-and-power engineering. Power-and-resource-saving units and systems are becoming extremely urgent because of the power engineering crisis expansion. The self-adjusting heat supply system from the individual heating points with the heat-accumulating units and coil heat exchangers for independent heating and water supply systems has been examined. Coil heat exchangers are used in municipal heating for heat transfer (e.g. geothermal waters for the independent mains of the heating and hot water supply systems. The heat engineering calculation of the heating and accumulating unit with the coil heat exchanger for independent heat supply systems from individual heater was performed and experimental data were received at the experimental industrial unit under the laboratory conditions. The peculiarities of the flows in the intertubular space, their influence on the heat exchange and temperatures of the first and intermediate mains have been shown. It is important to know the processes running inside the apparatus to be able to improve the technical characteristics of the three-loop coil heat exchanger. The task solution will make it possible to save the materials consumption for the three-loop coil heat exchangers in the future

Fundamental research on the gravity assisted heat pipe thermal storage unit (GAHP-TSU) with porous phase change materials (PCMs) for medium temperature applications

International Nuclear Information System (INIS)

Hu, Bo-wen; Wang, Qian; Liu, Zhen-Hua

2015-01-01

Highlights: • A novel gravity-assisted heat pipe thermal storage unit (GAHP-TSU) is presented and tested. • Composite granular solid–liquid PCM is piled up as the porous medium layer in GAHP-TSU. • GAHP-TSU avoids the major obstacle of low thermal conductivity of the PCM. • GAHP-TSU enables the thermal storage unit with outstanding heat transfer performance. - Abstract: In this study, a novel gravity-assisted heat pipe type thermal storage unit (GAHP-TSU) has been presented for the potential application in solar air conditioning and refrigeration systems, in which composite granular solid–liquid PCMs compounded by RT100 and high-density polyethylene with phase change temperature of 100 °C are piled up as a porous PCMs medium layer. Water is used as heat transfer fluid in the GAHP-TSU. The heat transfer mechanism of heat storage/release in the GAHP-TSU is similar to that of the gravity-assisted heat pipe, which is superior to traditional direct-contact or indirect-contact thermal storage units. The properties of start-up, heat transfer characteristics on the stages of heat absorption and release of the GAHP-TSU are studied in detailed, including necessary calculations based on heat transfer theory. The results show that the whole system is almost isothermal at the temperature over 70 °C and the heat transfer properties are excellent both for heat absorption and release stages. The GAHP-TSU device with low thermal conductivity of the PCMs is promising in potential industry applications

Evaluation of the performance of combined cooling, heating, and power systems with dual power generation units

International Nuclear Information System (INIS)

Knizley, Alta A.; Mago, Pedro J.; Smith, Amanda D.

2014-01-01

The benefits of using a combined cooling, heating, and power system with dual power generation units (D-CCHP) is examined in nine different U.S. locations. One power generation unit (PGU) is operated at base load while the other is operated following the electric load. The waste heat from both PGUs is used for heating and for cooling via an absorption chiller. The D-CCHP configuration is studied for a restaurant benchmark building, and its performance is quantified in terms of operational cost, primary energy consumption (PEC), and carbon dioxide emissions (CDE). Cost spark spread, PEC spark spread, and CDE spark spread are examined as performance indicators for the D-CCHP system. D-CCHP system performance correlates well with spark spreads, with higher spark spreads signifying greater savings through implementation of a D-CCHP system. A new parameter, thermal difference, is introduced to investigate the relative performance of a D-CCHP system compared to a dual PGU combined heat and power system (D-CHP). Thermal difference, together with spark spread, can explain the variation in savings of a D-CCHP system over a D-CHP system for each location. The effect of carbon credits on operational cost savings with respect to the reference case is shown for selected locations. - Highlights: • We investigate benefits from using combined cooling, heating, and power systems. • A dual power generation unit configuration is considered for CCHP and CHP. • Spark spreads for cost, energy, and emissions correlate with potential savings. • Thermal difference parameter helps to explain variations in potential savings. • Carbon credits may increase cost savings where emissions savings are possible

Study of regeneration system of 300 MW power unit based on nondeaerating heat balance diagram at reduced load

Science.gov (United States)

Esin, S. B.; Trifonov, N. N.; Sukhorukov, Yu. G.; Yurchenko, A. Yu.; Grigor'eva, E. B.; Snegin, I. P.; Zhivykh, D. A.; Medvedkin, A. V.; Ryabich, V. A.

2015-09-01

More than 30 power units of thermal power stations, based on the nondeaerating heat balance diagram, successfully operate in the former Soviet Union. Most of them are power units with a power of 300 MW, equipped with HTGZ and LMZ turbines. They operate according to a variable electric load curve characterized by deep reductions when undergoing night minimums. Additional extension of the range of power unit adjustment makes it possible to maintain the dispatch load curve and obtain profit for the electric power plant. The objective of this research is to carry out estimated and experimental processing of the operating regimes of the regeneration system of steam-turbine plants within the extended adjustment range and under the conditions when the constraints on the regeneration system and its equipment are removed. Constraints concerning the heat balance diagram that reduce the power unit efficiency when extending the adjustment range have been considered. Test results are presented for the nondeaerating heat balance diagram with the HTGZ turbine. Turbine pump and feed electric pump operation was studied at a power unit load of 120-300 MW. The reliability of feed pump operation is confirmed by a stable vibratory condition and the absence of cavitation noise and vibration at a frequency that characterizes the cavitation condition, as well as by oil temperature maintenance after bearings within normal limits. Cavitation performance of pumps in the studied range of their operation has been determined. Technical solutions are proposed on providing a profitable and stable operation of regeneration systems when extending the range of adjustment of power unit load. A nondeaerating diagram of high-pressure preheater (HPP) condensate discharge to the mixer. A regeneration system has been developed and studied on the operating power unit fitted with a deaeratorless thermal circuit of the system for removing the high-pressure preheater heating steam condensate to the mixer

Environmental and energy efficiency evaluation of residential gas and heat pump heating

International Nuclear Information System (INIS)

Ganji, A.R.

1993-01-01

Energy efficiency and source air pollutant emission factors of gas heaters, gas engine heat pumps, and electric heat pumps for domestic heating have been evaluated and compared. The analysis shows that with the present state of technology, gas engine heat pumps have the highest energy efficiency followed by electric heat pumps and then gas heaters. Electric heat pumps produce more than twice as much NO x , and comparable CO 2 and CO per unit of useful heating energy compared to natural gas heaters. CO production per unit of useful heating energy from gas engine heat pumps without any emission control is substantially higher than electric heat pumps and natural gas heaters. NO x production per unit of useful heating energy from natural gas engine heat pumps (using lean burn technology) without any emission control is about the same as effective NO x production from electric heat pumps. Gas engine heat pumps produce about one-half CO 2 compared to electric heat pumps

Energy Savings and Breakeven Cost for Residential Heat Pump Water Heaters in the United States

Energy Technology Data Exchange (ETDEWEB)

Maguire, J.; Burch, J.; Merrigan, T.; Ong, S.

2013-07-01

Heat pump water heaters (HPWHs) have recently reemerged in the U.S. residential water heating market and have the potential to provide homeowners with significant energy savings. However, there are questions as to the actual performance and energy savings potential of these units, in particular in regards to the heat pump's performance in unconditioned space and the impact of the heat pump on space heating and cooling loads when it is located in conditioned space. To help answer these questions, simulations were performed of a HPWH in both conditioned and unconditioned space at over 900 locations across the continental United States and Hawaii. Simulations included a Building America benchmark home so that any interaction between the HPWH and the home's HVAC equipment could be captured. Comparisons were performed to typical gas and electric water heaters to determine the energy savings potential and cost effectiveness of a HPWH relative to these technologies. HPWHs were found to have a significant source energy savings potential when replacing typical electric water heaters, but only saved source energy relative to gas water heater in the most favorable installation locations in the southern US. When replacing an electric water heater, the HPWH is likely to break even in California, the southern US, and parts of the northeast in most situations. However, the HPWH will only break even when replacing a gas water heater in a few southern states.

Possibility of using adsorption refrigeration unit in district heating network

Directory of Open Access Journals (Sweden)

Grzebielec Andrzej

2015-09-01

Full Text Available Adsorption refrigeration systems are able to work with heat sources of temperature starting with 50 °C. The aim of the article is to determine whether in terms of technical and economic issues adsorption refrigeration equipment can work as elements that produce cold using hot water from the district heating network. For this purpose, examined was the work of the adsorption air conditioning equipment cooperating with drycooler, and the opportunities offered by the district heating network in Warsaw during the summer. It turns out that the efficiency of the adsorption device from the economic perspective is not sufficient for production of cold even during the transitional period. The main problem is not the low temperature of the water supply, but the large difference between the coefficients of performance, COPs, of adsorption device and a traditional compressor air conditioning unit. When outside air temperature is 25 °C, the COP of the compressor type reaches a value of 4.49, whereas that of the adsorption device in the same conditions is 0.14. The ratio of the COPs is 32. At the same time ratio between the price of 1 kWh of electric power and 1 kWh of heat is only 2.85. Adsorption refrigeration equipment to be able to compete with compressor devices, should feature COPads efficiency to be greater than 1.52. At such a low driving temperature and even changing the drycooler into the evaporative cooler it is not currently possible to achieve.

Split heat pipe heat recovery system

OpenAIRE

E. Azad

2008-01-01

This paper describes a theoretical analysis of a split heat pipe heat recovery system. The analysis is based on an Effectiveness-NTU approach to deduce its heat transfer characteristics. In this study the variation of overall effectiveness of heat recovery with the number of transfer units are presented. Copyright , Manchester University Press.

Test procedure for calibration, grooming and alignment of the LDUA Purge Air Supply System

International Nuclear Information System (INIS)

Potter, J.D.

1995-01-01

The Light Duty Utility Arm (LDUA) is a remotely operated manipulator used to enter into underground waste tanks through one of the tank risers. National Electric Code requirements mandate that the in-tank portions of the LDUA be maintained at a positive pressure for entrance into a flammable atmosphere. The LDUA Purge Air Supply System (PASS) is a small, portable air compressor, which provides a constant low flow of instrument grade air for this purpose. This procedure is used to assure that the instrumentation and equipment comprising the PASS is properly adjusted in order to achieve its intended functions successfully

Measurement of residual solvents in a drug substance by a purge-and-trap method.

Science.gov (United States)

Lakatos, Miklós

2008-08-05

The purge-and-trap (P&T) gas extraction method combined with gas chromatography was studied for its suitability for quantitative residual solvents determination in a water-soluble active pharmaceutical ingredient (API). Some analytical method performance characteristics were investigated, namely, the repeatability, the accuracy and the detection limit of determination. The results show that the P&T technique is--as expected--more sensitive than the static headspace, thus it can be used for the determination of residual solvents pertaining to the ICH Class 1 group. It was found that it could be an alternative sample preparation method besides the static headspace (HS) method.

Heat Flow and Geothermal Potential in the South-Central United States

International Nuclear Information System (INIS)

Negraru, Petru T.; Blackwell, David D.; Erkan, Kamil

2008-01-01

Geothermal exploration is typically limited to high-grade hydrothermal reservoirs that are usually found in the western United States, yet large areas with subsurface temperatures above 150 deg. C at economic drilling depths can be found east of the Rocky Mountains. The object of this paper is to present new heat flow data and to evaluate the geothermal potential of Texas and adjacent areas. The new data show that, west of the Ouachita Thrust Belt, the heat flow values are lower than east of the fault zone. Basement heat flow values for the Palo Duro and Fort Worth Basins are below 50 mW/m 2 while, in the frontal zone of the belt, they can exceed 60 mW/m 2 . Further east, along the Balcones fault system the heat flow is in general higher than 55 mW/m 2 . The eastern most heat flow sites are in Louisiana and they show very high heat flow (over 80 mW/m 2 ), which is associated with the apparently highly radioactive basement of the Sabine uplift. The geothermal resource in this area is large and diverse, and can be divided in high grade (temperature above 150 deg. C) convective systems, conductive based enhanced geothermal systems and geothermal/geopressured systems. One of the most attractive areas east of the cordillera extends from eastern Texas across Louisiana and Arkansas to western Mississippi. Here temperatures reach exploitation range at depths below 4 km, and tapping such a resource from shut in hydrocarbon fields is relatively easy. The initial costs of the development can be greatly reduced if existing hydrocarbon infrastructure is used, and therefore using shut-in hydrocarbon fields for geothermal purposes should not be neglected

Optimization model of a system of crude oil distillation units with heat integration and metamodeling

International Nuclear Information System (INIS)

Lopez, Diana C; Mahecha, Cesar A; Hoyos, Luis J; Acevedo, Leonardo; Villamizar Jaime F

2010-01-01

The process of crude distillation impacts the economy of any refinery in a considerable manner. Therefore, it is necessary to improve it taking good advantage of the available infrastructure, generating products that conform to the specifications without violating the equipment operating constraints or plant restrictions at industrial units. The objective of this paper is to present the development of an optimization model for a Crude Distillation Unit (CDU) system at a ECOPETROL S.A. refinery in Barrancabermeja, involving the typical restrictions (flow according to pipeline capacity, pumps, distillation columns, etc) and a restriction that has not been included in bibliographic reports for this type of models: the heat integration of streams from Atmospheric Distillation Towers (ADTs) and Vacuum Distillation Towers (VDT) with the heat exchanger networks for crude pre-heating. On the other hand, ADTs were modeled with Metamodels in function of column temperatures and pressures, pump a rounds flows and return temperatures, stripping steam flows, Jet EBP ASTM D-86 and Diesel EBP ASTM D-86. Pre-heating trains were modeled with mass and energy balances, and design equation of each heat exchanger. The optimization model is NLP, maximizing the system profit. This model was implemented in GAMSide 22,2 using the CONOPT solver and it found new operating points with better economic results than those obtained with the normal operation in the real plants. It predicted optimum operation conditions of 3 ADTs for constant composition crude and calculated the yields and properties of atmospheric products, additional to temperatures and duties of 27 Crude Oil exchangers.

Sizing Combined Heat and Power Units and Domestic Building Energy Cost Optimisation

Directory of Open Access Journals (Sweden)

Dongmin Yu

2017-06-01

Full Text Available Many combined heat and power (CHP units have been installed in domestic buildings to increase energy efficiency and reduce energy costs. However, inappropriate sizing of a CHP may actually increase energy costs and reduce energy efficiency. Moreover, the high manufacturing cost of batteries makes batteries less affordable. Therefore, this paper will attempt to size the capacity of CHP and optimise daily energy costs for a domestic building with only CHP installed. In this paper, electricity and heat loads are firstly used as sizing criteria in finding the best capacities of different types of CHP with the help of the maximum rectangle (MR method. Subsequently, the genetic algorithm (GA will be used to optimise the daily energy costs of the different cases. Then, heat and electricity loads are jointly considered for sizing different types of CHP and for optimising the daily energy costs through the GA method. The optimisation results show that the GA sizing method gives a higher average daily energy cost saving, which is 13% reduction compared to a building without installing CHP. However, to achieve this, there will be about 3% energy efficiency reduction and 7% input power to rated power ratio reduction compared to using the MR method and heat demand in sizing CHP.

Model of a thermal energy storage device integrated into a solar assisted heat pump system for space heating

International Nuclear Information System (INIS)

Badescu, Viorel

2003-01-01

Details about modelling a sensible heat thermal energy storage (TES) device integrated into a space heating system are given. The two main operating modes are described. Solar air heaters provide thermal energy for driving a vapor compression heat pump. The TES unit ensures a more efficient usage of the collected solar energy. The TES operation is modeled by using two non-linear coupled partial differential equations for the temperature of the storage medium and heat transfer fluid, respectively. Preliminary results show that smaller TES units provide a higher heat flux to the heat pump vaporiser. This makes the small TES unit discharge more rapidly during time periods with higher thermal loads. The larger TES units provide heat during longer time periods, even if the heat flux they supply is generally smaller. The maximum heat flux is extracted from the TES unit during the morning. Both the heat pump COP and exergy efficiency decrease when the TES unit length increases. Also, the monthly thermal energy stored by the TES unit and the monthly energy necessary to drive the heat pump compressor are increased by increasing the TES unit length

Cogeneration of heat and electricity from rape oil with a little CHP unit in a car wash

International Nuclear Information System (INIS)

Pilz, H.D.; Thomas, S.; Zeilinger, J.

2002-01-01

Environmentally friendly energy supply system for smaller houses is described. In Elsbett system the so-called multi fuel engine starts the combined electricity and heat production unit. In such a system one can use also natural fuels, animal oils and fats besides heating oil. Therefore no additional CO 2 is produced, but it will be brought to the balanced natural circle

The Purge of National Teaching in Morella (1936-1945 | La depuración del magisterio nacional en Morella (1936-1945

Directory of Open Access Journals (Sweden)

Marta García Monfort

2015-12-01

Full Text Available The outbreak of the Civil War, apart from spreading havoc and blood all through Spain, caused some kind of deeply rooted social breakdown generating an endless thirst for revenge. While the military structures were deploying their strategy on the battlefield, the apparatus of power of both sides was establishing mechanisms of coercion and control mainly aimed at the submission of controlled territory. In this context, the purge of National Teachers favoured an ideological selection based on terror with preventive and punitive purposes. After the military conflict, under Francoist authorities the purge continued systematically, and with a repressive orientation, until the fifties. This analysis seeks to describe the idiosyncrasies of the purging processes developed in Republican Morella (1936-1938 and further in Franco’s regime (1939-1945. | El estallido de la Guerra Civil, además de sembrar de dolor y sangre la geografía española, provocará una ruptura social de hondo raigambre que generará en la sociedad una interminable sed de venganza. Al mismo tiempo que las estructuras militares desplegaban su estrategia en el campo de batalla, los aparatos de poder de los dos bandos establecieron unos mecanismos de coacción y control encaminados en primera instancia a la sumisión del territorio dominado. En este contexto, la depuración del Magisterio Nacional propiciará una selección ideológica con unos fines preventivos y punitivos. Finalizada la contienda bélica, la purga continuará sistematizada y con un carácter represivo de la mano de las autoridades franquistas hasta la década de los cincuenta aproximadamente. Este análisis trata de describir la idiosincrasia de los procesos depuradores desarrollados en la Morella republicana (1936-1938 y, posteriormente, en la franquista (1939-1945.

Sizing Combined Heat and Power Units and Domestic Building Energy Cost Optimisation

OpenAIRE

Dongmin Yu; Yuanzhu Meng; Gangui Yan; Gang Mu; Dezhi Li; Simon Le Blond

2017-01-01

Many combined heat and power (CHP) units have been installed in domestic buildings to increase energy efficiency and reduce energy costs. However, inappropriate sizing of a CHP may actually increase energy costs and reduce energy efficiency. Moreover, the high manufacturing cost of batteries makes batteries less affordable. Therefore, this paper will attempt to size the capacity of CHP and optimise daily energy costs for a domestic building with only CHP installed. In this paper, electricity ...

Adolescent risk factors for purging in young women: findings from the national longitudinal study of adolescent health

OpenAIRE

Stephen, Eric M; Rose, Jennifer; Kenney, Lindsay; Rosselli-Navarra, Francine; Weissman, Ruth Striegel

2014-01-01

Background There exists a dearth of prospective adolescent eating disorder studies with samples that are large enough to detect small or medium sized effects for risk factors, that are generalizable to the broader population, and that follow adolescents long enough to fully capture the period of development when the risk of eating disorder symptoms occurring is highest. As a result, the purpose of this study was to examine psychosocial risk factors for purging for weight control in a national...

Development of a new distillation unit combined with compressed heat pump (heat integrated distillation column (HIDiC)) (eco-energy city project)

Energy Technology Data Exchange (ETDEWEB)

Nakanishi, Toshinari; Aso, Kazumasa [Kimura Chemical Plants Co., Ltd., Amagasaki City, Hyogo (Japan); Takamatsu, Takeichiro [Research Inst. of Industrial Technology, Suita-City, Osaka (Japan); Nakaiwa, Masaru [National Inst. of Materials and Chemical Research, Tsukuba, Ibaraki (Japan); Noda, Hideo; Kuratani, Nobuyuki [Kansai Chemical Engineearing Co., Ltd., Amagasaki-city, Hyogo (Japan); Yoshida, Kazufumi [Maruzen Petrochemical Co., Ltd., 25-10, Tokyo (Japan)

1999-07-01

To reduce the irreversible loss the Heat Integrated Distillation Column (HIDiC) is proposed by application of heat-pump technology. (Distillation column, which is an energy consuming separation unit, has been widely used in oil refinery and the other chemical-related plants. The reason why it is a major energy consumer is that a large amount of irreversible loss occurs in heat transfer within the process.) In this paper, current results on the study of HIDiC in both simulations and experiments are shown. HIDiC must be operated at a higher pressure in the rectifying section so as to make its temperature higher than that of the stripping section which stands parallel with the rectifying section. That makes heat transfer from the rectifying section to the stripping section. Because of vaporization in the stripping section and condensation in the rectifying section, the energy for the reboiler can be saved. The degree of energy saving can be expected to be much more than 30%, although the exact value depends on the characteristics of mixture to be separated. (The degree of energy saving is higher than the above, if the exhaust vapor from the HIDiC is used to heat the feed or the other processes.) To save energy by the HIDiC, high separation performances and heat transfer capabilities are required. It has been found out that the HIDiC, whose shape is like vertical shell and tube heat exchanger was enough to be practical use of the HIDiC from the static design principle points of view. (orig.)

Optimal coordinated scheduling of combined heat and power fuel cell, wind, and photovoltaic units in micro grids considering uncertainties

International Nuclear Information System (INIS)

Bornapour, Mosayeb; Hooshmand, Rahmat-Allah; Khodabakhshian, Amin; Parastegari, Moein

2016-01-01

In this paper, a stochastic model is proposed for coordinated scheduling of combined heat and power units in micro grid considering wind turbine and photovoltaic units. Uncertainties of electrical market price; the speed of wind and solar radiation are considered using a scenario-based method. In the method, scenarios are generated using roulette wheel mechanism based on probability distribution functions of input random variables. Using this method, the probabilistic specifics of the problem are distributed and the problem is converted to a deterministic one. The type of the objective function, coordinated scheduling of combined heat and power, wind turbine, and photovoltaic units change this problem to a mixed integer nonlinear one. Therefore to solve this problem modified particle swarm optimization algorithm is employed. The mentioned uncertainties lead to an increase in profit. Moreover, the optimal coordinated scheduling of renewable energy resources and thermal units in micro grids increase the total profit. In order to evaluate the performance of the proposed method, its performance is executed on modified 33 bus distributed system as a micro grid. - Highlights: • Stochastic model is proposed for coordinated scheduling of renewable energy sources. • The effect of combined heat and power is considered. • Maximizing profits of micro grid is considered as objective function. • Considering the uncertainties of problem lead to profit increasing. • Optimal scheduling of renewable energy sources and thermal units increases profit.

Heat recovery system series arrangements

Science.gov (United States)

Kauffman, Justin P.; Welch, Andrew M.; Dawson, Gregory R.; Minor, Eric N.

2017-11-14

The present disclosure is directed to heat recovery systems that employ two or more organic Rankine cycle (ORC) units disposed in series. According to certain embodiments, each ORC unit includes an evaporator that heats an organic working fluid, a turbine generator set that expands the working fluid to generate electricity, a condenser that cools the working fluid, and a pump that returns the working fluid to the evaporator. The heating fluid is directed through each evaporator to heat the working fluid circulating within each ORC unit, and the cooling fluid is directed through each condenser to cool the working fluid circulating within each ORC unit. The heating fluid and the cooling fluid flow through the ORC units in series in the same or opposite directions.

Analysis of the use of waste heat obtained from coal-fired units in Organic Rankine Cycles and for brown coal drying

International Nuclear Information System (INIS)

Łukowicz, Henryk; Kochaniewicz, Andrzej

2012-01-01

The ever-increasing restrictions on greenhouse gas emissions have created a need for new energy technologies. One way to meet these new requirements is to optimise the efficiency of power units. This paper presents two energy technologies that, if used, will increase the efficiency of electricity generation. One of the most effective ways to improve the efficiency of brown coal-fired units is by drying the coal that is fed into the boiler. Here, we describe a technology that uses the waste heat obtained from exhaust gases. This paper also presents an analysis of the feasibility of and potential for using waste heat obtained from exhaust gases to feed Organic Rankine Cycles (ORCs). Several low-temperature working fluids were considered, which were selected based on properties that were best suited for these types of cycles. The impact of these working fluids on the efficiency and capacity of the ORC was also examined. The calculations for ORCs fed with waste heat obtained from exhaust gases from hard coal- and brown coal-fired boilers were compared. -- Highlights: ► We describe a technology that uses the waste heat obtained from exhaust gases. ► The impact of using different working fluids with a low boiling point is examined. ► We describe integrating the ORC with the power unit. ► The use of waste heat from boiler exhaust gases to dry brown coal is proposed. ► We demonstrate a possible increase in power unit efficiency.

Nuclear safety inspection in treatment process for SG heat exchange tubes deficiency of unit 1, TNPS

International Nuclear Information System (INIS)

Zhang Chunming; Song Chenxiu; Zhao Pengyu; Hou Wei

2006-01-01

This paper describes treatment process for SG heat exchange tubes deficiency of Unit 1, TNPS, nuclear safety inspection of Northern Regional Office during treatment process for deficiency and further inspection after deficiency had been treated. (authors)

Study on constraints for heat removal duties of the main fractionator in delayed coking units

International Nuclear Information System (INIS)

Lei, Yang; Zhang, Bingjian; Qi, Xin; Chen, Qinglin; Hui, Chi-Wai

2014-01-01

A novel method is presented in this paper to quantitatively define the heat removal of the main fractionator in delayed coking units on the basis of a fractionating precision diagram (Houghland diagram) and column grand composite curve (CGCC). By referring to the CGCC method, several envelopes are illustrated at draw trays including the top pumparound draw, diesel draw, intermediate pumparound draw and gas oil draw, the energy and material balances are then calculated. Assuming practical near-minimum thermodynamic condition (PNMTC), the minimum liquid reflux flow is zero in the envelope for pumparound trays without product draw and the minimum liquid reflux flow is defined by Houghland diagram for pumparound trays with product draw. The PNMTC-CGCC is constructed by calculating the enthalpy-flow deficit to quantitatively define the heat removal constraints in each envelope. Meanwhile, the corresponding practical heat removal curve is constructed. A case study shows that the high temperature heat removal ratio within the main fractionator increased by 8%. The proposed method offers heat removal inequality constraints for the model to optimize the heat integration between the main fractionator and the heat exchanger network. - Highlights: • A novel method defines the heat removal constraints of the main fractionator. • Fractionating precision diagram and column grand composite curve are combined. • The results are the inequality constraints in a simultaneous optimization model

A heated vapor cell unit for dichroic atomic vapor laser lock in atomic rubidium.

Science.gov (United States)

McCarron, Daniel J; Hughes, Ifan G; Tierney, Patrick; Cornish, Simon L

2007-09-01

The design and performance of a compact heated vapor cell unit for realizing a dichroic atomic vapor laser lock (DAVLL) for the D(2) transitions in atomic rubidium is described. A 5 cm long vapor cell is placed in a double-solenoid arrangement to produce the required magnetic field; the heat from the solenoid is used to increase the vapor pressure and correspondingly the DAVLL signal. We have characterized experimentally the dependence of important features of the DAVLL signal on magnetic field and cell temperature. For the weaker transitions both the amplitude and gradient of the signal are increased by an order of magnitude.

A heated vapor cell unit for dichroic atomic vapor laser lock in atomic rubidium

International Nuclear Information System (INIS)

McCarron, Daniel J.; Hughes, Ifan G.; Tierney, Patrick; Cornish, Simon L.

2007-01-01

The design and performance of a compact heated vapor cell unit for realizing a dichroic atomic vapor laser lock (DAVLL) for the D 2 transitions in atomic rubidium is described. A 5 cm long vapor cell is placed in a double-solenoid arrangement to produce the required magnetic field; the heat from the solenoid is used to increase the vapor pressure and correspondingly the DAVLL signal. We have characterized experimentally the dependence of important features of the DAVLL signal on magnetic field and cell temperature. For the weaker transitions both the amplitude and gradient of the signal are increased by an order of magnitude

Technical evaluation of the electrical, instrumentation, and control design aspects of the override of containment purge valve isolation and other engineered safety feature signals for the Fort Calhoun Nuclear Power Plant

International Nuclear Information System (INIS)

Hackett, D.B.

1980-01-01

This report documents the technical evaluation of the electrical, instrumentation, and control design aspects of the override of containment purge valve isolation and other engineered safety feature signals for the Fort Calhoun nuclear power plant. The review criteria are based on IEEE Std-279-1971 requirements for the safety signals to all purge and ventilation isolation valves. This report is supplied as part of the Selected Electrical, Instrumentation, and Control Systems Issues Program being conducted for the US Nuclear Regulatory Commission by Lawrence Livermore Laboratory

Primary energy savings using heat storage for biomass heating systems

Directory of Open Access Journals (Sweden)

Mitrović Dejan M.

2012-01-01

Full Text Available District heating is an efficient way to provide heat to residential, tertiary and industrial users. The heat storage unit is an insulated water tank that absorbs surplus heat from the boiler. The stored heat in the heat storage unit makes it possible to heat even when the boiler is not working, thus increasing the heating efficiency. In order to save primary energy (fuel, the boiler operates on nominal load every time it is in operation (for the purpose of this research. The aim of this paper is to analyze the water temperature variation in the heat storage, depending on the heat load and the heat storage volume. Heat load is calculated for three reference days, with average daily temperatures from -5 to 5°C. The primary energy savings are also calculated for those days in the case of using heat storage in district heating.[Projekat Ministarstva nauke Republike Srbije, br. TR 33051: The concept of sustainable energy supply of settlements with energy efficient buildings

Development of a unit suitable for corrosion monitoring in district heating systems. Experiences with the LOCOR-cell test method

DEFF Research Database (Denmark)

Andersen, Asbjørn; Hilbert, Lisbeth Rischel

2004-01-01

A by-pass unit suitable for placement of a number of different probes for corrosion monitoring has been designed. Also measurements of water parameters are allowed in a side stream from the unit. The project is a part of the Nordic Innovation Fund project KORMOF. The by-pass unit has been installed...... in 6 pressurised circulating heating systems and in one cooling system. 7 different corrosion monitoring methods have been used to study corrosion rates and types in dependency of water chemistry. This paper describes the design of the by-pass unit including water analysis methods. It also describes...... the purpose, background and gained results of one of the used monitoring techniques, the crevice corrosion measurements obtained by the LOCOR-Cell„§. The crevice corrosion cell was developed by FORCE Technology in a previous district heating project financed by Nordic Industrial Fund (1)(2). Results from...

Optimization model of a system of crude oil distillation units whit heat integration and meta modeling

International Nuclear Information System (INIS)

Lopez, Diana C; Mahecha, Cesar A; Hoyos, Luis J; Acevedo, Leonardo; Villamizar Jaime F

2009-01-01

The process of crude distillation impacts the economy of any refinery in a considerable manner. Therefore, it is necessary to improve it taking good advantage of the available infrastructure, generating products that conform to the specifications without violating the equipment operating constraints or plant restrictions at industrial units. The objective of this paper is to present the development of an optimization model for a Crude Distillation Unit (CDU) system at a ECOPETROL S.A. refinery in Barrancabermeja, involving the typical restrictions (flow according to pipeline capacity, pumps, distillation columns, etc) and a restriction that has not been included in bibliographic reports for this type of models: the heat integration of streams from Atmospheric Distillation Towers (ADTs) and Vacuum Distillation Towers (VDT) with the heat exchanger networks for crude pre-heating. On the other hand, ADTs were modeled with Meta models in function of column temperatures and pressures, pumparounds flows and return temperatures, stripping steam flows, Jet EBP ASTM D-86 and Diesel EBP ASTM D-86. Pre-heating trains were modeled with mass and energy balances, and design equation of each heat exchanger. The optimization model is NLP, maximizing the system profit. This model was implemented in GAMSide 22,2 using the CONOPT solver and it found new operating points with better economic results than those obtained with the normal operation in the real plants. It predicted optimum operation conditions of 3 ADTs for constant composition crude and calculated the yields and properties of atmospheric products, additional to temperatures and duties of 27 Crude Oil exchangers.

Investigation of the Dynamic Melting Process in a Thermal Energy Storage Unit Using a Helical Coil Heat Exchanger

Directory of Open Access Journals (Sweden)

Xun Yang

2017-08-01

Full Text Available In this study, the dynamic melting process of the phase change material (PCM in a vertical cylindrical tube-in-tank thermal energy storage (TES unit was investigated through numerical simulations and experimental measurements. To ensure good heat exchange performance, a concentric helical coil was inserted into the TES unit to pipe the heat transfer fluid (HTF. A numerical model using the computational fluid dynamics (CFD approach was developed based on the enthalpy-porosity method to simulate the unsteady melting process including temperature and liquid fraction variations. Temperature measurements using evenly spaced thermocouples were conducted, and the temperature variation at three locations inside the TES unit was recorded. The effects of the HTF inlet parameters were investigated by parametric studies with different temperatures and flow rate values. Reasonably good agreement was achieved between the numerical prediction and the temperature measurement, which confirmed the numerical simulation accuracy. The numerical results showed the significance of buoyancy effect for the dynamic melting process. The system TES performance was very sensitive to the HTF inlet temperature. By contrast, no apparent influences can be found when changing the HTF flow rates. This study provides a comprehensive solution to investigate the heat exchange process of the TES system using PCM.

Industrial excess heat for district heating in Denmark

International Nuclear Information System (INIS)

Bühler, Fabian; Petrović, Stefan; Karlsson, Kenneth; Elmegaard, Brian

2017-01-01

Highlights: •Method for utilisation potential of industrial excess heat for district heating. •Industrial excess heat from thermal processes is quantified at single production units. •Linking of industrial excess heat sources and district heating demands done in GIS. •Excess heat recovery using direct heat transfer and heat pumps. •5.1% of the Danish district heating demand could be supplied by industrial excess heat. -- Abstract: Excess heat is available from various sources and its utilisation could reduce the primary energy use. The accessibility of this heat is however dependent amongst others on the source and sink temperature, amount and potential users in its vicinity. In this work a new method is developed which analyses excess heat sources from the industrial sector and how they could be used for district heating. This method first allocates excess heat to single production units by introducing and validating a new approach. Spatial analysis of the heat sources and consumers are then performed to evaluate the potential for using them for district heating. In this way the theoretical potential of using the excess heat for covering the heating demand of buildings is determined. Through the use of industry specific temperature profiles the heat usable directly or via heat pumps is further found. A sensitivity analysis investigates the impact of future energy efficiency measures in the industry, buildings and the district heating grid on the national potential. The results show that for the case study of Denmark, 1.36 TWh of district heat could be provided annually with industrial excess heat from thermal processes which equals 5.1% of the current demand. More than half of this heat was found to be usable directly, without the need for a heat pump.

Utilising heat from nuclear waste for space heating

International Nuclear Information System (INIS)

Deacon, D.

1982-01-01

A heating unit utilising the decay heat from irradiated material comprises a storage envelope for the material associated with a heat exchange system, means for producing a flow of air over the heat exchange system to extract heat from the material, an exhaust duct capable of discharging the heated air to the atmosphere, and means for selectively diverting at least some of the heated air to effect the required heating. With the flow of air over the heat exchange system taking place by a natural thermosyphon process the arrangement is self regulating and inherently reliable. (author)

Centrifugal LabTube platform for fully automated DNA purification and LAMP amplification based on an integrated, low-cost heating system.

Science.gov (United States)

Hoehl, Melanie M; Weißert, Michael; Dannenberg, Arne; Nesch, Thomas; Paust, Nils; von Stetten, Felix; Zengerle, Roland; Slocum, Alexander H; Steigert, Juergen

2014-06-01

This paper introduces a disposable battery-driven heating system for loop-mediated isothermal DNA amplification (LAMP) inside a centrifugally-driven DNA purification platform (LabTube). We demonstrate LabTube-based fully automated DNA purification of as low as 100 cell-equivalents of verotoxin-producing Escherichia coli (VTEC) in water, milk and apple juice in a laboratory centrifuge, followed by integrated and automated LAMP amplification with a reduction of hands-on time from 45 to 1 min. The heating system consists of two parallel SMD thick film resistors and a NTC as heating and temperature sensing elements. They are driven by a 3 V battery and controlled by a microcontroller. The LAMP reagents are stored in the elution chamber and the amplification starts immediately after the eluate is purged into the chamber. The LabTube, including a microcontroller-based heating system, demonstrates contamination-free and automated sample-to-answer nucleic acid testing within a laboratory centrifuge. The heating system can be easily parallelized within one LabTube and it is deployable for a variety of heating and electrical applications.

Parameter effect of a phase change thermal energy storage unit with one shell and one finned tube on its energy efficiency ratio and heat storage rate

International Nuclear Information System (INIS)

Wang, Wei-Wei; Wang, Liang-Bi; He, Ya-Ling

2016-01-01

Highlights: • The parameter effect on the performance of PCTES unit using fins is reported. • The configurations of PCTES unit using fins in optimum performance are suggested. • Two parameters to indicate the effects of PCM and tube material properties are found. • The working conditions of PCTES unit using fins in optimum performance are analyzed. - Abstract: The performance of a phase change thermal energy storage (PCTES) unit using circular finned tube is affected by many parameters. Thorough studies of the parameter effect on the performance of PCTES unit are strongly required in its optimum design process. Based on a reported energy efficiency ratio and a newly defined parameter named the heat storage rate, the parameter effect on the performance of PCTES unit using circular finned tube is numerically investigated. When the fin pitch is greater than 4 times of the inner radius of the tube, the fin height and the fin thickness have little effect on the energy efficiency ratio and the heat storage rate. When the fin pitch is small, the performance of PCTES unit becomes better using large fin height and width. The energy efficiency ratio and the heat storage rate are more sensitive to the outer tube diameter. The performance of PCTES unit using circular finned tube is best when water is used as the heat transfer fluid (HTF). When the fluid flow of HTF is in a laminar state, the energy efficiency ratio and the heat storage rate are larger than that in a turbulent state.

Determination of C6-C10 aromatic hydrocarbons in water by purge-and-trap capillary gas chromatography

Science.gov (United States)

Eganhouse, R.P.; Dorsey, T.F.; Phinney, C.S.; Westcott, A.M.

1993-01-01

A method is described for the determination of the C6-C10 aromatic hydrocarbons in water based on purge-and-trap capillary gas chromatography with flame ionization and mass spectrometric detection. Retention time data and 70 eV mass spectra were obtained for benzene and all 35 C7-C10 aromatic hydrocarbons. With optimized chromatographic conditions and mass spectrometric detection, benzene and 33 of the 35 alkylbenzenes can be identified and measured in a 45-min run. Use of a flame ionization detector permits the simultaneous determination of benzene and 26 alkylbenzenes.

Monitoring and understanding changes in heat waves, cold waves, floods, and droughts in the United States: State of knowledge

Science.gov (United States)

Peterson, Thomas C.; Heim, Richard R.; Hirsch, Robert M.; Kaiser, Dale P.; Brooks, Harold; Diffenbaugh, Noah S.; Dole, Randall M.; Giovannettone, Jason P.; Guirguis, Kristen; Karl, Thomas R.; Katz, Richard W.; Kunkel, Kenneth E.; Lettenmaier, Dennis P.; McCabe, Gregory J.; Paciorek, Christopher J.; Ryberg, Karen R.; K Wolter, BS Silva; Schubert, Siegfried; Silva, Viviane B. S.; Stewart, Brooke C.; Vecchia, Aldo V.; Villarini, Gabriele; Vose, Russell S.; Walsh, John; Wehner, Michael; Wolock, David; Wolter, Klaus; Woodhouse, Connie A.; Wuebbles, Donald

2013-01-01

Weather and climate extremes have been varying and changing on many different time scales. In recent decades, heat waves have generally become more frequent across the United States, while cold waves have been decreasing. While this is in keeping with expectations in a warming climate, it turns out that decadal variations in the number of U.S. heat and cold waves do not correlate well with the observed U.S. warming during the last century. Annual peak flow data reveal that river flooding trends on the century scale do not show uniform changes across the country. While flood magnitudes in the Southwest have been decreasing, flood magnitudes in the Northeast and north-central United States have been increasing. Confounding the analysis of trends in river flooding is multiyear and even multidecadal variability likely caused by both large-scale atmospheric circulation changes and basin-scale “memory” in the form of soil moisture. Droughts also have long-term trends as well as multiyear and decadal variability. Instrumental data indicate that the Dust Bowl of the 1930s and the drought in the 1950s were the most significant twentieth-century droughts in the United States, while tree ring data indicate that the megadroughts over the twelfth century exceeded anything in the twentieth century in both spatial extent and duration. The state of knowledge of the factors that cause heat waves, cold waves, floods, and drought to change is fairly good with heat waves being the best understood.

Solar heating system

Science.gov (United States)

Schreyer, James M.; Dorsey, George F.

1982-01-01

An improved solar heating system in which the incident radiation of the sun is absorbed on collector panels, transferred to a storage unit and then distributed as heat for a building and the like. The improvement is obtained by utilizing a storage unit comprising separate compartments containing an array of materials having different melting points ranging from 75.degree. to 180.degree. F. The materials in the storage system are melted in accordance with the amount of heat absorbed from the sun and then transferred to the storage system. An efficient low volume storage system is provided by utilizing the latent heat of fusion of the materials as they change states in storing and releasing heat for distribution.

Experimental analysis of an air-to-air heat recovery unit for balanced ventilation systems in residential buildings

International Nuclear Information System (INIS)

Fernandez-Seara, Jose; Diz, Ruben; Uhia, Francisco J.; Dopazo, Alberto; Ferro, Jose M.

2011-01-01

This paper deals with the experimental analysis of an air-to-air heat recovery unit equipped with a sensible polymer plate heat exchanger (PHE) for balanced ventilation systems in residential buildings. The PHE is arranged in parallel triangular ducts. An experimental facility was designed to reproduce the typical outdoor and exhaust air conditions with regard to temperature and humidity. The unit was tested under balanced operation conditions, as commonly used in practice. A set of tests was conducted under the reference operating conditions to evaluate the PHE performance. Afterwards, an experimental parametric analysis was conducted to investigate the influence of changing the operating conditions on the PHE performance. Experiments were carried out varying the inlet fresh air temperature, the exhaust air relative humidity and the air flow rate. The experimental results are shown and discussed in this paper.

Sensors for Metering Heat Flux Area Density and Metrological Equipment for the Heat Flux Density Measurement

Science.gov (United States)

Doronin, D. O.

2018-04-01

The demand in measuring and studies of heat conduction of various media is very urgent now. This article considers the problem of heat conduction monitoring and measurement in various media and materials in any industries and branches of science as well as metrological support of the heat flux measurement equipment. The main study objects are both the sensors manufactured and facilities onto which these sensors will be installed: different cladding structures of the buildings, awnings, rocket fairings, boiler units, internal combustion engines. The Company develops and manufactures different types of heat flux sensors: thermocouple, thin-film, heterogeneous gradient as well as metrological equipment for the gauging calibration of the heat flux density measurement. The calibration shall be performed using both referencing method in the unit and by fixed setting of the heat flux in the unit. To manufacture heterogeneous heat flux gradient sensors (HHFGS) the Company developed and designed a number of units: diffusion welding unit, HHFGS cutting unit. Rather good quality HHFGS prototypes were obtained. At this stage the factory tests on the equipment for the heat flux density measurement equipment are planned. A high-sensitivity heat flux sensor was produced, now it is tested at the Construction Physics Research Institute (Moscow). It became possible to create thin-film heat flux sensors with the sensitivity not worse than that of the sensors manufactured by Captec Company (France). The Company has sufficient premises to supply the market with a wide range of sensors, to master new sensor manufacture technologies which will enable their application range.

Global Warming Impacts on Heating and Cooling Degree-Days in the United States

Science.gov (United States)

Petri, Y.; Caldeira, K.

2014-12-01

Anthropogenic climate change is expected to significantly alter residential air conditioning and space heating requirements, which account for 41% of U.S. household energy expenditures. The degree-day method can be used for reliable estimation of weather related building energy consumption and costs, as well as outdoor climatic thermal comfort. Here, we use U.S. Climate Normals developed by NOAA based on weather station observations along with Climate Model Intercomparison Project phase 5 (CMIP5) multi-model ensemble simulations. We add the projected change in heating and cooling degree-days based on the climate models to the estimates based on the NOAA U.S. Climate Normals to project future heating and cooling degree-days. We find locations with the lowest and highest combined index of cooling (CDDs) and heating degree-days (HDDs) for the historical period (1981 - 2010) and future period (2080 - 2099) under the Representation Concentration Pathway 8.5 (RCP8.5) climate change scenario. Our results indicate that in both time frames and among the lower 48 states, coastal areas in the West and South California will have the smallest degree-day sum (CDD + HDD), and hence from a climatic perspective become the best candidates for residential real estate. The Rocky Mountains region in Wyoming, in addition to northern Minnesota and North Dakota, will have the greatest CDD + HDD. While global warming is projected to reduce the median heating and cooling demand (- 5%) at the end of the century, CDD + HDD will decrease in the North, with an opposite effect in the South. This work could be helpful in deciding where to live in the United States based on present and future thermal comfort, and could also provide a basis for estimates of changes in heating and cooling energy demand.

Optimal stochastic coordinated scheduling of proton exchange membrane fuel cell-combined heat and power, wind and photovoltaic units in micro grids considering hydrogen storage

International Nuclear Information System (INIS)

Bornapour, Mosayeb; Hooshmand, Rahmat-Allah; Khodabakhshian, Amin; Parastegari, Moein

2017-01-01

Highlights: •Stochastic model is proposed for coordinated scheduling of renewable energy sources. •The effect of combined heat and power is considered. •Hydrogen storage is considered for fuel cells. •Maximizing profits of micro grid is considered as objective function. •Considering the uncertainties of problem lead to profit increasing. -- Abstract: Nowadays, renewable energy sources and combined heat and power units are extremely used in micro grids, so it is necessary to schedule these units to improve the performance of the system. In this regard, a stochastic model is proposed in this paper to schedule proton exchange membrane fuel cell-combined heat and power, wind turbines, and photovoltaic units coordinately in a micro grid while considering hydrogen storage. Hydrogen storage strategy is considered for the operation of proton exchange membrane fuel cell-combined heat and power units. To consider stochastic generation of renewable energy source units in this paper, a scenario-based method is used. In this method, the uncertainties of electrical market price, the wind speed, and solar irradiance are considered. This stochastic scheduling problem is a mixed integer- nonlinear programming which considers the proposed objective function and variables of coordinated scheduling of PEMFC-CHP, wind turbines and photovoltaic units. It also considers hydrogen storage strategy and converts it to a mixed integer nonlinear problem. In this study a modified firefly algorithm is used to solve the problem. This method is examined on modified 33-bus distributed network as a MG for its performance.

Thermodynamic comparison and efficiency enhancement mechanism of coal to alternative fuel systems

International Nuclear Information System (INIS)

Ji, Xiaozhou; Li, Sheng; Gao, Lin; Jin, Hongguang

2016-01-01

Highlights: • Energy and exergy analysis are presented to three coal-to-alternative-fuels systems. • Internal reasons for performance differences for different systems are disclosed. • The temperature and heat release of synthesis reactions are key to plant efficiency. • The distillation unit and purge gas recovery are important to efficiency enhancement. - Abstract: Coal to alternative fuels is an important path to enforce energy security and to provide clean energy. In this paper, we use exergy analysis and energy utilization diagram (EUD) methods to disclose the internal reasons for performance differences in typical coal to alternative fuel processes. ASPEN plus software is used to simulate the coal-based energy systems, and the simulation results are verified with engineering data. Results show that coal to substitute natural gas (SNG) process has a higher exergy efficiency of 56.56%, while the exergy efficiency of traditional coal to methanol process is 48.65%. It is indicated that three key factors impact the performance enhancement of coal to alternative fuel process: (1) whether the fuel is distillated, (2) the synthesis temperature and the amount of heat release from reactions, and (3) whether the chemical purge gases from synthesis and distillation units are recovered. Distillation unit is not recommended and synthesis at high temperature and with large heat release is preferable for coal to alternative fuel systems. Gasification is identified as the main source of exergy destruction, and thereby how to decrease its destruction is the key direction of plant efficiency improvement in the future. Also, decreasing the power consumption in air separation unit by seeking for advanced technologies, i.e. membrane, or using another kind of oxidant is another direction to improve plant performance.

Experimental analysis of an air–water heat pump with micro-channel heat exchanger

International Nuclear Information System (INIS)

Brignoli, Riccardo; Cecchinato, Luca; Zilio, Claudio

2013-01-01

A multi-port extruded (MPE) aluminium flat tube air heat exchanger was compared to a round tube finned coil (FC). The MPE heat exchanger has parallel flow vertical tube configuration with headers in horizontal position and conventional folded louvred fins. The two heat exchangers were mounted on a 10 kW cooling capacity R410A packaged air heat pump. They were sized to approximately obtain the same cooling and heating capacities in chiller and heating mode, respectively. Climatic room steady state tests without frosting phenomena occurring during heat pump operation, demonstrated that the round tube and the flat tube heat exchanger performance are comparable. The MPE heat exchanger was tested with different refrigerant inlet distributor/outlet tubes configurations to investigate the effect of liquid refrigerant distribution. Cycling frosting/defrosting operations were tested with two equivalent machines placed in parallel outdoor and working at full load condition, one of the units was equipped with the MPE heat exchanger while the other mounted a standard finned coil. Penalization factors were analytically introduced to evaluate frosting associated heating energy and energy efficiency degradation. Test results indicate that both the heat pumps are penalized by frost formation but both the penalization factors are higher for the MPE-unit than the FC-unit one in the −6 to 4 °C air dry bulb temperature range. For the two units, a roughly linear dependence of the heating energy penalization factor and of the energy efficiency factor from the difference between outdoor air and saturated air at the evaporation temperature humidity ratio can be pointed out. - Highlights: ► A multi-port aluminium flat tube heat exchanger was compared to a round tube finned one in a heat pump application. ► In steady state tests without frosting the round and the flat tube heat exchanger are comparable. ► Different inlet distributor/outlet tubes configurations were tested to

Trace moisture emissions from heated metal surfaces in hydrogen service

International Nuclear Information System (INIS)

Funke, Hans H.; Yao Jianlong; Raynor, Mark W.

2004-01-01

The formation of trace moisture by exposure of dry heated surfaces of 316 L stainless-steel, Restek Silcosteel registered , and nickel 1/8 in. outer diameter line segments to purified Ar and H 2 was studied using atmospheric pressure ionization mass spectrometry at flow rates of 2 slpm. Prior to H 2 exposure, adsorbed moisture was removed by heating incrementally to 500 deg. C in an argon matrix, where the Restek Silcosteel registered material released a maximum of 50 ppb moisture at 300 deg. C and moisture spikes from the Ni and stainless-steel surfaces reached several 100 ppb. Upon exposure to H 2 , persistent low ppb moisture emissions due to the reduction of surface oxide species were observed at temperatures as low as 100 deg. C. Spikes at 300-500 deg. C ranged from ∼100 ppb for the stainless-steel lines to 400 ppb for the Restek Silcosteel registered material. The observed moisture emissions have to be considered as a potential contamination source for high-purity processes utilizing H 2 purge at elevated temperatures

40 CFR 75.81 - Monitoring of Hg mass emissions and heat input at the unit level.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 16 2010-07-01 2010-07-01 false Monitoring of Hg mass emissions and... AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTINUOUS EMISSION MONITORING Hg Mass Emission Provisions § 75.81 Monitoring of Hg mass emissions and heat input at the unit level. The owner or operator of the...

Mathematical modelling and optimization of a large-scale combined cooling, heat, and power system that incorporates unit changeover and time-of-use electricity price

International Nuclear Information System (INIS)

Zhu, Qiannan; Luo, Xianglong; Zhang, Bingjian; Chen, Ying

2017-01-01

Highlights: • We propose a novel superstructure for the design and optimization of LSCCHP. • A multi-objective multi-period MINLP model is formulated. • The unit start-up cost and time-of-use electricity prices are involved. • Unit size discretization strategy is proposed to linearize the original MINLP model. • A case study is elaborated to demonstrate the effectiveness of the proposed method. - Abstract: Building energy systems, particularly large public ones, are major energy consumers and pollutant emission contributors. In this study, a superstructure of large-scale combined cooling, heat, and power system is constructed. The off-design unit, economic cost, and CO_2 emission models are also formulated. Moreover, a multi-objective mixed integer nonlinear programming model is formulated for the simultaneous system synthesis, technology selection, unit sizing, and operation optimization of large-scale combined cooling, heat, and power system. Time-of-use electricity price and unit changeover cost are incorporated into the problem model. The economic objective is to minimize the total annual cost, which comprises the operation and investment costs of large-scale combined cooling, heat, and power system. The environmental objective is to minimize the annual global CO_2 emission of large-scale combined cooling, heat, and power system. The augmented ε–constraint method is applied to achieve the Pareto frontier of the design configuration, thereby reflecting the set of solutions that represent optimal trade-offs between the economic and environmental objectives. Sensitivity analysis is conducted to reflect the impact of natural gas price on the combined cooling, heat, and power system. The synthesis and design of combined cooling, heat, and power system for an airport in China is studied to test the proposed synthesis and design methodology. The Pareto curve of multi-objective optimization shows that the total annual cost varies from 102.53 to 94.59 M

Thermal performance evaluation of a latent heat storage unit for late evening cooking in a solar cooker having three reflectors

Energy Technology Data Exchange (ETDEWEB)

Buddhi, D.; Sharma, A. [Devi Ahilya University, Indore (India). School of Energy and Environmental Studies, Thermal Energy Storage Laboratory; Sharma, S.D. [Mie University, Tsu (Japan). Faculty of Engineering, Department of Architecture

2003-04-01

In this paper, a phase change material (PCM) storage unit for a solar cooker was designed and developed to store energy during sunshine hours. The stored energy was utilised to cook food in the late evening. Commercial grade acetanilide (melting point 118.9 {sup o}C, latent heat of fusion 222 kJ/kg) was used as a latent heat storage material. Evening cooking experiments were conducted with different loads and loading times during the winter season. The experimental results showed that late evening cooking is possible in a solar cooker having three reflectors to enhance the incident solar radiation with the PCM storage unit. (author)

Cold and heat waves in the United States.

Science.gov (United States)

Barnett, A G; Hajat, S; Gasparrini, A; Rocklöv, J

2012-01-01

Extreme cold and heat waves, characterized by a number of cold or hot days in succession, place a strain on people's cardiovascular and respiratory systems. The increase in deaths due to these waves may be greater than that predicted by extreme temperatures alone. We examined cold and heat waves in 99 US cities for 14 years (1987-2000) and investigated how the risk of death depended on the temperature threshold used to define a wave, and a wave's timing, duration and intensity. We defined cold and heat waves using temperatures above and below cold and heat thresholds for two or more days. We tried five cold thresholds using the first to fifth percentiles of temperature, and five heat thresholds using the 95-99 percentiles. The extra wave effects were estimated using a two-stage model to ensure that their effects were estimated after removing the general effects of temperature. The increases in deaths associated with cold waves were generally small and not statistically significant, and there was even evidence of a decreased risk during the coldest waves. Heat waves generally increased the risk of death, particularly for the hottest heat threshold. Cold waves of a colder intensity or longer duration were not more dangerous. Cold waves earlier in the cool season were more dangerous, as were heat waves earlier in the warm season. In general there was no increased risk of death during cold waves above the known increased risk associated with cold temperatures. Cold or heat waves earlier in the cool or warm season may be more dangerous because of a build up in the susceptible pool or a lack of preparedness for extreme temperatures. Copyright © 2011 Elsevier Inc. All rights reserved.

Spent nuclear fuel project cold vacuum drying facility vacuum and purge system design description

Energy Technology Data Exchange (ETDEWEB)

IRWIN, J.J.

1998-11-30

This document provides the System Design Description (SDD) for the Cold Vacuum Drying Facility (CVDF) Vacuum and Purge System (VPS) . The SDD was developed in conjunction with HNF-SD-SNF-SAR-O02, Safety Analysis Report for the Cold Vacuum Drying Facility, Phase 2, Supporting Installation of Processing Systems (Garvin 1998), The HNF-SD-SNF-DRD-002, 1998, Cold Vacuum Drying Facility Design Requirements, and the CVDF Design Summary Report. The SDD contains general descriptions of the VPS equipment, the system functions, requirements and interfaces. The SDD provides references for design and fabrication details, operation sequences and maintenance. This SDD has been developed for the SNFP Operations Organization and shall be updated, expanded, and revised in accordance with future design, construction and startup phases of the CVDF until the CVDF final ORR is approved.

Spent nuclear fuel project cold vacuum drying facility vacuum and purge system design description

International Nuclear Information System (INIS)

IRWIN, J.J.

1998-01-01

This document provides the System Design Description (SDD) for the Cold Vacuum Drying Facility (CVDF) Vacuum and Purge System (VPS) . The SDD was developed in conjunction with HNF-SD-SNF-SAR-O02, Safety Analysis Report for the Cold Vacuum Drying Facility, Phase 2, Supporting Installation of Processing Systems (Garvin 1998), The HNF-SD-SNF-DRD-002, 1998, Cold Vacuum Drying Facility Design Requirements, and the CVDF Design Summary Report. The SDD contains general descriptions of the VPS equipment, the system functions, requirements and interfaces. The SDD provides references for design and fabrication details, operation sequences and maintenance. This SDD has been developed for the SNFP Operations Organization and shall be updated, expanded, and revised in accordance with future design, construction and startup phases of the CVDF until the CVDF final ORR is approved

Flow boiling heat transfer and pressure drop characteristics of R134a, R1234yf and R1234ze in a plate heat exchanger for organic Rankine cycle units

DEFF Research Database (Denmark)

Zhang, Ji; Desideri, Adriano; Kærn, Martin Ryhl

2017-01-01

. This paper is aimed at obtaining flow boiling heat transfer and pressure drop characteristics in a plate heat exchanger under the working conditions prevailing in the evaporator of organic Rankine cycle units. Two hydrofluoroolefins R1234yf and R1234ze, and one hydrofluorocarbon R134a, were selected...... as the working fluids. The heat transfer coefficients and pressure drops of the three working fluids were measured with varying saturation temperatures, mass fluxes, heat fluxes and outlet vapour qualities, which range from 60°C to 80°C, 86 kg/m2 s to 137 kg/m2 s, 9.8 kW/m2 to 36.8 kW/m2 and 0.5 to 1...... developed that are more suitable for evaporation in organic Rankine cycles. The experimental results indicate that heat transfer coefficients are strongly dependent upon the heat flux and saturation temperature. Moreover, the results suggest better thermal-hydraulic performance for R1234yf than the other...

Heat and power from combustibles

International Nuclear Information System (INIS)

Zogg, M.

2002-01-01

This article compares four ways of generating heat and power from liquid and gaseous fuels. Various combinations of conventional boilers, heat pumps, combined heat and power units and combined-cycle power plants are considered and the ratio of heat to electrical power produced is discussed. Fuel requirements for the four combinations are looked at and net emissions of carbon dioxide, oxides of nitrogen and carbon monoxide presented in graphical form. The author makes recommendations on the choice of the technology to be used to generate heat and electricity for different heat/power ratios and criticises the all too slack emission limits for small combined heat and power units

Design and operation of gas-heated thermal pumping units

Energy Technology Data Exchange (ETDEWEB)

Rostek, H A [Ruhrgas A.G., Essen (Germany, F.R.)

1979-03-01

The first gas heat pump systems have been operated since spring 1977. These are applied in living houses, school, swimming pools, and sport places and administration buildings. The heating performance of these systems is 150-3800 kW. Two of these systems, one in a swimming pool and one in a house for several families are operating, each of them for one heating period. The operational experiences with these gas heat pumps are reported on, basing on measurement results. The experience gathered from the operation of gas heat pumps systems is applied to the planning of other plants. The development of a standardized gas heat pump-series is emphasized.

A study of the reverse cycle defrosting performance on a multi-circuit outdoor coil unit in an air source heat pump – Part I: Experiments

International Nuclear Information System (INIS)

Qu, Minglu; Xia, Liang; Deng, Shiming; Jiang, Yiqiang

2012-01-01

Highlights: ► We experimental study the defrosting performance on a multi-circuit outdoor coil unit in an ASHP unit. ► We find that defrosting is quicker on the airside of upper circuits than that on the lower circuits. ► We discuss the effects of downwards flowing of the melted frost along the outdoor coil surface on defrosting performance. -- Abstract: When an air source heat pump (ASHP) unit operates in heating mode, frost can be accumulated on the surface of its finned outdoor coil which normally has multiple parallel circuits on its refrigerant side for minimized refrigerant pressure loss and enhanced heat transfer efficiency. On its airside, however, there is usually no segmentation corresponding to the number of refrigerant circuit. Frosting deteriorates the operation and energy efficiency of the ASHP unit and periodic defrosting becomes necessary. Currently the most widely used standard defrosting method for ASHPs is reverse cycle defrost. This paper, the first part of a two-part series, reports on the experimental part of a study of the reverse cycle defrosting performance on a multi-circuit outdoor coil unit in an experimental 6.5 kW heating capacity residential ASHP unit. Firstly the experimental ASHP unit is described and experimental procedures detailed. Secondly, the experimental results are reported. This is followed by the discussion on the effects of downwards flowing of the melted frost along a multi-circuit outdoor coil surface on defrosting performance. Finally, the evaluation of the defrosting efficiency for the experimental ASHP unit is provided. In the second part of the series, a modeling analysis on the effects of downwards flowing of the melted frost along the multi-circuit outdoor coil surface on defrosting performance of the experimental ASHP unit will be presented.

Use of Artificial Neural Networks for Prediction of Convective Heat Transfer in Evaporative Units

Directory of Open Access Journals (Sweden)

Romero-Méndez Ricardo

2014-01-01

Full Text Available Convective heat transfer prediction of evaporative processes is more complicated than the heat transfer prediction of single-phase convective processes. This is due to the fact that physical phenomena involved in evaporative processes are very complex and vary with the vapor quality that increases gradually as more fluid is evaporated. Power-law correlations used for prediction of evaporative convection have proved little accuracy when used in practical cases. In this investigation, neural-network-based models have been used as a tool for prediction of the thermal performance of evaporative units. For this purpose, experimental data were obtained in a facility that includes a counter-flow concentric pipes heat exchanger with R134a refrigerant flowing inside the circular section and temperature controlled warm water moving through the annular section. This work also included the construction of an inverse Rankine refrigeration cycle that was equipped with measurement devices, sensors and a data acquisition system to collect the experimental measurements under different operating conditions. Part of the data were used to train several neural-network configurations. The best neural-network model was then used for prediction purposes and the results obtained were compared with experimental data not used for training purposes. The results obtained in this investigation reveal the convenience of using artificial neural networks as accurate predictive tools for determining convective heat transfer rates of evaporative processes.

Regional implications of heat flow of the Snake River Plain, Northwestern United States

Science.gov (United States)

Blackwell, D. D.

1989-08-01

The Snake River Plain is a major topographic feature of the Northwestern United States. It marks the track of an upper mantle and crustal melting event that propagated across the area from southwest to northeast at a velocity of about 3.5 cm/yr. The melting event has the same energetics as a large oceanic hotspot or plume and so the area is the continental analog of an oceanic hotspot track such as the Hawaiian Island-Emperor Seamount chain. Thus, the unique features of the area reflect the response of a continental lithosphere to a very energetic hotspot. The crust is extensively modified by basalt magma emplacement into the crust and by the resulting massive rhyolite volcanism from melted crustal material, presently occurring at Yellowstone National Park. The volcanism is associated with little crustal extension. Heat flow values are high along the margins of the Eastern and Western Snake River Plains and there is abundant evidence for low-grade geothermal resources associated with regional groundwater systems. The regional heat flow pattern in the Western Snake River Plains reflects the influence of crustal-scale thermal refraction associated with the large sedimentary basin that has formed there. Heat flow values in shallow holes in the Eastern Snake River Plains are low due to the Snake River Plains aquifer, an extensive basalt aquifer where water flow rates approach 1 km/yr. Below the aquifer, conductive heat flow values are about 100 mW m -2. Deep holes in the region suggest a systematic eastward increase in heat flow in the Snake River Plains from about 75-90 mW m -2 to 90-110 mW m -2. Temperatures in the upper crust do not behave similarly because the thermal conductivity of the Plio-Pleistocene sedimentary rocks in the west is lower than that in the volcanic rocks characteristic of the Eastern Snake River Plains. Extremely high heat loss values (averaging 2500 mW m -2) and upper crustal temperatures are characteristic of the Yellowstone caldera.

Low-Cost Gas Heat Pump for Building Space Heating

Energy Technology Data Exchange (ETDEWEB)

Garrabrant, Michael [Stone Mountain Technologies, Inc., Johnson City, TN (United States); Keinath, Christopher [Stone Mountain Technologies, Inc., Johnson City, TN (United States)

2016-10-11

Gas-fired residential space heating in the U.S is predominantly supplied by furnaces and boilers. These technologies have been approaching their thermodynamic limit over the past 30 years and improvements for high efficiency units have approached a point of diminishing return. Electric heat pumps are growing in popularity but their heating performance at low ambient temperatures is poor. The development of a low-cost gas absorption heat pump would offer a significant improvement to current furnaces and boilers, and in heating dominated climate zones when compared to electric heat pumps. Gas absorption heat pumps (GAHP) exceed the traditional limit of thermal efficiency encountered by typical furnaces and boilers, and maintain high levels of performance at low ambient temperatures. The project team designed and demonstrated two low-cost packaged prototype GAHP space heating systems during the course of this investigation. Led by Stone Mountain Technologies Inc. (SMTI), with support from A.O. Smith, and the Gas Technology Institute (GTI), the cross-functional team completed research and development tasks including cycle modeling, 8× scaling of a compact solution pump, combustion system development, breadboard evaluation, fabrication of two packaged prototype units, third party testing of the first prototype, and the evaluation of cost and energy savings compared to high and minimum efficiency gas options. Over the course of the project and with the fabrication of two Alpha prototypes it was shown that this technology met or exceeded most of the stated project targets. At ambient temperatures of 47, 35, 17 and -13°F the prototypes achieved gas based coefficients of performance of 1.50, 1.44, 1.37, and 1.17, respectively. Both units operated with parasitic loads well below the 750 watt target with the second Alpha prototype operating 75-100 watts below the first Alpha prototype. Modulation of the units at 4:1 was achieved with the project goal of 2:1 modulation

Analytical characterization and optimization in the determination of trihalomethanes on drinking water by purge and trap coupled to a gas chromatography

International Nuclear Information System (INIS)

Costa Junior, Nelson Vicente da

2010-01-01

This work shows an analytical methodology developed and optimized to determine trihalomethanes level THMs, in drinking water samples, using purge and trap coupled to gas chromatography (GC-PT). THMs are byproducts water chlorination, these compounds must have a maximum of 100 μg.L -1 under Brazilian law, due these compounds be suspected human carcinogens base on studies in laboratory animals. The technique of purge and trap efficiently extracts these compounds from water, and the gas chromatograph separates the THMs. The GC uses a light polarity column and electron capture detector. This detector is selective and more sensitive in the detection of these compounds. The methodology was validated in terms of: linearity, selectivity, accuracy, precision, quantification limit, detection limit and robustness. The detection limit was less than 0,5 μg.L -1 . The accuracy and precision were adequate for testing the trace compounds. The drinking water samples were collected in the city of Suzano-SP, which belongs to 'Alto do Tiete', in this region lay 'Tiete' river with predominant vegetation. The THMs compound found in drinking water at higher concentrations was chloroform where the spread of values found between 15,9 to 111,0 μg.L -1 in drinking water. (author)

Heat pumps as a way to Low or Zero Emission district heating systems

Directory of Open Access Journals (Sweden)

Jadwiszczak Piotr

2017-01-01

In traditional district heating (DH system heat is generated from fossil fuel (FF combustion in heating only boilers (HOB or in combined heat and power (CHP plants. It results in greenhouse gases and other pollutants emission. The reduction of emission is one of the main target in EU climate policy. Among the alternative technologies in DH heat pumps (HP play a crucial role and enable to decrease or even eliminate emission to create a low or zero emission (LZE DH system. The emission reduction effect of integration the large scale HP units into DH systems can by defined by four groups of factors: the share of HP in the heat demand, the heat source for HP, the driving energy for HP and heat sink for HP. This paper illustrates the main options for large scale HP units application for LZE DH based on HP technology.

Industrial excess heat for district heating in Denmark

DEFF Research Database (Denmark)

Bühler, Fabian; Petrovic, Stefan; Karlsson, Kenneth Bernard

2017-01-01

analyses excess heat sources from the industrial sector and how they could be used for district heating. This method first allocates excess heat to single production units by introducing and validating a new approach. Spatial analysis of the heat sources and consumers are then performed to evaluate...... the potential for using them for district heating. In this way the theoretical potential of using the excess heat for covering the heating demand of buildings is determined. Through the use of industry specific temperature profiles the heat usable directly or via heat pumps is further found. A sensitivity...... analysis investigates the impact of future energy efficiency measures in the industry, buildings and the district heating grid on the national potential. The results show that for the case study of Denmark, 1.36 TWh of district heat could be provided annually with industrial excess heat from thermal...

Heat Mortality Versus Cold Mortality: A Study of Conflicting Databases in the United States.

Science.gov (United States)

Dixon, P. G.; Brommer, D. M.; Hedquist, B. C.; Kalkstein, A. J.; Goodrich, G. B.; Walter, J. C.; Dickerson, C. C., IV; Penny, S. J.; Cerveny, R. S.

2005-07-01

Studies, public reports, news reports, and Web sites cite a wide range of values associated with deaths resulting from excessive heat and excessive cold. For example, in the United States, the National Climatic Data Center's Storm Data statistics of temperature- related deaths are skewed heavily toward heat-related deaths, while the National Center for Health Statistics Compressed Mortality Database indicates the reverse—4 times more people die of “excessive cold” conditions in a given year than of “excessive heat.” In this study, we address the fundamental differences in the various temperature-related mortality databases, assess their benefits and limitations, and offer suggestions as to their use. These datasets suffer from potential incompleteness of source information, long compilation times, limited quality control, and the subjective determination of a direct versus indirect cause of death. In general, these separate mortality datasets should not be combined or compared, particularly with regard to policy determination. The use of gross mortality numbers appears to be one of the best means of determining temperature-related mortality, but those data must be detrended into order to remove a persistent winter-dominant death maximum and are difficult to obtain on a regional daily basis.

Experimental investigation on AC unit integrated with sensible heat storage (SHS)

Science.gov (United States)

Aziz, N. A.; Amin, N. A. M.; Majid, M. S. A.; Hussin, A.; Zhubir, S.

2017-10-01

The growth in population and economy has increases the energy demand and raises the concerns over the sustainable energy source. Towards the sustainable development, energy efficiency in buildings has become a prime objective. In this paper, the integration of thermal energy storage was studied. This paper presents an experimental investigation on the performance of an air conditioning unit integrated with sensible heat storage (SHS) system. The results were compared to the conventional AC systems in the terms of average electricity usage, indoor temperature and the relative humidity inside the experimented room (cabin container). Results show that the integration of water tank as an SHS reduces the electricity usage by 5%, while the integration of well-insulated water tank saves up to 8% of the electricity consumption.

Satiation deficits and binge eating: Probing differences between bulimia nervosa and purging disorder using an ad lib test meal.

Science.gov (United States)

Keel, Pamela K; Haedt-Matt, Alissa A; Hildebrandt, Britny; Bodell, Lindsay P; Wolfe, Barbara E; Jimerson, David C

2018-04-11

Purging disorder (PD) has been included as a named condition within the DSM-5 category of Other Specified Feeding or Eating Disorder and differs from bulimia nervosa (BN) in the absence of binge-eating episodes. The current study evaluated satiation through behavioral and self-report measures to understand how this construct may explain distinct symptom presentations for bulimia nervosa (BN) and purging disorder (PD). Women (N = 119) were recruited from the community if they met DSM-5 criteria for BN (n = 57), PD (n = 31), or were free of eating pathology (n = 31 controls). Participants completed structured clinical interviews and questionnaires and an ad lib test meal during which they provided reports of subjective states. Significant group differences were found on self-reported symptoms, ad lib test meal intake, and subjective responses to food intake between individuals with eating disorders and controls and between BN and PD. Further, ad lib intake was associated with self-reported frequency and size of binge episodes. In a multivariable model, the amount of food consumed during binges as reported during clinical interviews predicted amount of food consumed during the ad lib test meal, controlling for other binge-related variables. Satiation deficits distinguish BN from PD and appear to be specifically linked to the size of binge episodes. Future work should expand exploration of physiological bases of these differences to contribute to novel interventions. Copyright © 2018 Elsevier Ltd. All rights reserved.

Different attention bias patterns in anorexia nervosa restricting and binge/purge types.

Science.gov (United States)

Gilon Mann, Tal; Hamdan, Sami; Bar-Haim, Yair; Lazarov, Amit; Enoch-Levy, Adi; Dubnov-Raz, Gal; Treasure, Janet; Stein, Daniel

2018-04-03

Patients with anorexia nervosa (AN) have been shown to display both elevated anxiety and attentional biases in threat processing. In this study, we compared threat-related attention patterns of patients with AN restricting type (AN-R; n = 32), AN binge/purge type (AN-B/P; n = 23), and healthy controls (n = 19). A dot-probe task with either eating disorder-related or general and social anxiety-related words was used to measure attention patterns. Severity of eating disorder symptoms, depression, anxiety, and stress were also assessed. Patients with AN-R showed vigilance to both types of threat words, whereas patients with AN-B/P showed avoidance of both threat types. Healthy control participants did not show any attention bias. Attention bias was not associated with any of the demographic, clinical, and psychometric parameters introduced. These findings suggest that there are differential patterns of attention allocation in patients with AN-R and AN-B/P. More research is needed to identify what causes/underlies these differential patterns. Copyright © 2018 John Wiley & Sons, Ltd and Eating Disorders Association.

Combined Heat and Power Dispatch Considering Heat Storage of Both Buildings and Pipelines in District Heating System for Wind Power Integration

Directory of Open Access Journals (Sweden)

Ping Li

2017-06-01

Full Text Available The strong coupling between electric power and heat supply highly restricts the electric power generation range of combined heat and power (CHP units during heating seasons. This makes the system operational flexibility very low, which leads to heavy wind power curtailment, especially in the region with a high percentage of CHP units and abundant wind power energy such as northeastern China. The heat storage capacity of pipelines and buildings of the district heating system (DHS, which already exist in the urban infrastructures, can be exploited to realize the power and heat decoupling without any additional investment. We formulate a combined heat and power dispatch model considering both the pipelines’ dynamic thermal performance (PDTP and the buildings’ thermal inertia (BTI, abbreviated as the CPB-CHPD model, emphasizing the coordinating operation between the electric power and district heating systems to break the strong coupling without impacting end users’ heat supply quality. Simulation results demonstrate that the proposed CPB-CHPD model has much better synergic benefits than the model considering only PDTP or BTI on wind power integration and total operation cost savings.

Safety provision during heating of coal downcast shafts with gas heat generators using degassed methane

Directory of Open Access Journals (Sweden)

В. Р. Алабьев

2017-06-01

Together with heat generators of mixed type the article also describes a working principle of heat generator of indirect action type, which to the fullest extent possible meets requirements of Russian Federation legislation and regulation for application of this heat generators in coal mines conditions. The article has a principal working scheme of heat unit layout using this type of generator. It is shown that after development of corresponding normative documents regulating processes of design, construction and operation of heating units using heaters of indirect action, their application in Russian coal mines will be possible without breaking Safety standards and rules.

Flue gas moisture capacity calculation at the outlet of the condensation heat recovery unit

Directory of Open Access Journals (Sweden)

Galashov Nikolay

2017-01-01

Full Text Available As a result, study equation has been obtained which determine the flue gas moisture capacity at the outlet of the condensation heat recovery unit with an error of less than 1%. It possible to at the temperature of the flue gas below the dew point and the known air-fuel ratio efficient. The equation can be used to calculate plants operating on products of gas combustion without Use of tables and programs for calculating the water-vapor saturation pressure.

Improved solar heating systems

Science.gov (United States)

Schreyer, J.M.; Dorsey, G.F.

1980-05-16

An improved solar heating system is described in which the incident radiation of the sun is absorbed on collector panels, transferred to a storage unit and then distributed as heat for a building and the like. The improvement is obtained by utilizing a storage unit comprising separate compartments containing an array of materials having different melting points ranging from 75 to 180/sup 0/F. The materials in the storage system are melted in accordance with the amount of heat absorbed from the sun and then transferred to the storage system. An efficient low volume storage system is provided by utilizing the latent heat of fusion of the materials as they change states in storing ad releasing heat for distribution.

Distributed heat generation in a district heating system

OpenAIRE

Lennermo, Gunnar; Lauenberg, Patrick

2016-01-01

District heating (OH) systems need to be improved  regarding integration  of decentralised  heat generation. Micro production, prosumers and smart grids are terms becoming more and more common  in  connection  to  the  power  grid.  Concerning district  heating,  the  development  is slower, although improving. Today there are a number of such decentralised units for heat generation,  mainly  solar,  that have been partly evaluated.  Previous  studies  have shown  that there is a need to deve...

Manufacturing A Refrigerator with Heat Recovery Unit

Directory of Open Access Journals (Sweden)

Mustafa Mohammed Kadhim

2018-02-01

Full Text Available This study aims to exploite the rejected heating energy from condenser and benefit from it to reheat the foods and other materials. It can also be employed to improve the coefficient of performance of a refrigerator at the same time by using approximately the same consumption electrical energy used to operate the compressor and refrigerator in general. This idea has been implemented by manufacturing of a refrigerator with using additional part has the same metal and condenser pipe diameters but its surface area does not exceed 40% from total surface area of the condenser and its design as an insulated cabinet from all sides to prevent heat leakage through it and located between the compressor and the condenser. Small electrical fan has been added inside this cabinet to provide a suitable air circulation and a homogenous temperature distribution inside the cabinet space. It is expected that the super heating energy of refrigerant (R134a which comes out of the compressor would be removed  inside this cabinet and this insist to condensate the refrigerant (cooling fluid with a rate higher than that used in the normal refrigerator only. Three magnetic valves have been used in order to control the refrigerant flow in state of operation the refrigerator only or to gather with heating cabinet. To measure the temperatures at each process of the simple vapor compression refrigeration cycle, nine temperature sensors at input and output of each compressor, condenser and an evaporator in additional to input of cabinet and inside it and on evaporator surface have been provided. Five pressure gages have been used to measure the value of pressure and compare it for the two states of operation. The consumption of electrical energy  can be calculated by adding an ammeter and a voltmeter and compare between the consumption energy of both states. The obtained results show that there is an improvement in the coeffecient of performance in state of operation the

A novel algorithm for demand-control of a single-room ventilation unit with a rotary heat exchanger

DEFF Research Database (Denmark)

Smith, Kevin Michael; Jansen, Anders Lund; Svendsen, Svend

in the indoor environment. Based on these values, a demand-control algorithm varies fan speeds to change airflow rates and varies the rotational speed of the heat exchanger to modulate heat and moisture recovery. The algorithm varies airflow rates to provide free cooling and limit CO2 concentrations and varies...... moisture recovery by varying the rotational speed and then safely unbalances airflows in a worst-case scenario. In the algorithm, frost protection and minimum supply temperature take the highest priority and override other controls. This paper documents the proposed demand control algorithm and analyses...... its impacts on compliance of building regulations in Denmark. The paper presents an algorithm that manufacturers can program into their controls. The commercially available single-room ventilation unit with a rotary heat exchanger uses this algorithm coded in the C language. Future work will document...

Design of A District Heating System Including The Upgrading of Residual Industrial Waste Heat

NARCIS (Netherlands)

Falcao, P.W.; Mesbah, A.; Suherman, M.V.; Wennekes, S.

2005-01-01

This study was aimed to evaluate the feasibility of using a waste heat stream from DSM for a District Heating System. A conceptual design was carried out with emphasis on the unit for upgrading the residual waste heat. Having reviewed heat pump technology, mechanical heat pump was found to be the

Decentralized central heating

Energy Technology Data Exchange (ETDEWEB)

Savic, S.; Hudjera, A.

1994-08-04

The decentralized central heating is essentially based on new technical solutions for an independent heating unit, which allows up to 20% collectible energy savings and up to 15% savings in built-in-material. These savings are already made possible by the fact that the elements described under point A are thus eliminated from the classical heating. The thus superfluous made elements are replaced by new technical solutions described under point B - technical problem - and point E - patent claim. The technical solutions described in detail under point B and point E form together a technical unit and are essential parts of the invention protected by the patent. (author)

Selection of cooling fluid for an organic Rankine cycle unit recovering heat on a container ship sailing in the Arctic region

DEFF Research Database (Denmark)

Suárez de la Fuente, Santiago; Larsen, Ulrik; Pierobon, Leonardo

2017-01-01

As Arctic sea ice coverage declines it is expected that marine traffic could increase in this northern region due to shorter routes. Navigating in the Arctic offers opportunities and challenges for waste heat recovery systems (WHRS). Lower temperatures require larger heating power on board, hence...... air as coolant. This paper explores the use of two different coolants, air and seawater, for an organic Rankine cycle (ORC) unit using the available waste heat in the scavenge air system of a container ship navigating in Arctic Circle. Using a two-step single objective optimisation process, detailed...

Heat and Mass Transfer during Hydrogen Generation in an Array of Fuel Bars of a BWR Using a Periodic Unit Cell

Directory of Open Access Journals (Sweden)

H. Romero-Paredes

2012-01-01

Full Text Available This paper presents, the numerical analysis of heat and mass transfer during hydrogen generation in an array of fuel cylinder bars, each coated with a cladding and a steam current flowing outside the cylinders. The analysis considers the fuel element without mitigation effects. The system consists of a representative periodic unit cell where the initial and boundary-value problems for heat and mass transfer were solved. In this unit cell, we considered that a fuel element is coated by a cladding with steam surrounding it as a coolant. The numerical simulations allow describing the evolution of the temperature and concentration profiles inside the nuclear reactor and could be used as a basis for hybrid upscaling simulations.

Break-Even Cost for Residential Solar Water Heating in the United States: Key Drivers and Sensitivities

Energy Technology Data Exchange (ETDEWEB)

Cassard, H.; Denholm, P.; Ong, S.

2011-02-01

This paper examines the break-even cost for residential rooftop solar water heating (SWH) technology, defined as the point where the cost of the energy saved with a SWH system equals the cost of a conventional heating fuel purchased from the grid (either electricity or natural gas). We examine the break-even cost for the largest 1,000 electric and natural gas utilities serving residential customers in the United States as of 2008. Currently, the break-even cost of SWH in the United States varies by more than a factor of five for both electricity and natural gas, despite a much smaller variation in the amount of energy saved by the systems (a factor of approximately one and a half). The break-even price for natural gas is lower than that for electricity due to a lower fuel cost. We also consider the relationship between SWH price and solar fraction and examine the key drivers behind break-even costs. Overall, the key drivers of the break-even cost of SWH are a combination of fuel price, local incentives, and technical factors including the solar resource location, system size, and hot water draw.

Heat stress control in the TMI-2 [Three Mile Island Unit 2] defueling and decontamination activities

International Nuclear Information System (INIS)

Schork, J.S.; Parfitt, B.A.

1988-01-01

During the initial stages of the Three Mile Island Unit 2 (TMI-2) defueling and decontamination activities for the reactor building, it was realized that the high levels of loose radioactive contamination would require the use of extensive protective clothing by entry personnel. While there was no doubt that layered protective clothing protects workers from becoming contaminated, it was recognized that these same layers of clothing would impose a very significant heat stress burden. To prevent the potentially serious consequences of a severe reaction to heat stress by workers in the hostile environment of the TMI-2 reactor building and yet maintain the reasonable work productivity necessary to perform the recovery adequately, an effective program of controlling worker exposure to heat stress had to be developed. Body-cooling devices produce a flow of cool air, which is introduced close to the skin to remove body heat through convection and increased sweat evaporation. The cooling effect produced by the Vortex tube successfully protected the workers from heat stress, however, there were several logistical and operational problems that hindered extensive use of these devices. The last type of cooling garment examined was the frozen water garment (FWG) developed by Elizier Kamon at the Pennsylvania State University as part of an Electric Power Research Institute research grant. Personal protection, i.e., body cooling, engineering controls, and administrative controls, have been implemented successfully

Exergo-economic analysis of finned tube for waste heat recovery including phase change heat transfer

International Nuclear Information System (INIS)

Wu, Shuang Ying; Jiu, Jing Rui; Xiao, Lan; Li, You Rong; Liu, Chao; Xu, Jin Liang

2013-01-01

In this paper, an exergo-economic criterion, i.e. the net profit per unit transferred heat load, is established from the perspective of exergy recovery to evaluate the performance of finned tube used in waste heat recovery. Also, the dimensionless exergy change number is introduced to investigate the effect of the flow (mechanical) exergy loss rate on the recovered thermal exergy. Selecting R245fa as a working fluid and exhaust flue gas as a heat source, the effects of the internal Reynolds number Re_i, the external Reynolds number Re_o , the unit cost of thermal exergy ε_q , the geometric parameter of finned tube η_oβ and the phase change temperature T_v etc. on the performance of finned tube are discussed in detail. The results show that the higher T_v and η_oβ, and lower Re_i may lead to the negligible flow(mechanical) exergy loss rate. There exists an optimal value of Re_i where the net profit per unit transferred heat load peaks, while the variations of Re_o, ε_q and T_v cause monotonic change of the net profit per unit transferred heat load. The phase change temperature exerts relatively greater influence on the exergo-economic performance of finned tube in comparison with other parameters. And there exists a critical phase change temperature, where the net profit per unit transferred heat load is equal to zero.

ANALYSIS OF THE INFLUENCE OF PARAMETERS OF CONTROL OF HEATING POWER GENERATING UNITS ON FUEL CONSUMPTION

Directory of Open Access Journals (Sweden)

Shchinnikov P.A.

2011-04-01

Full Text Available It is presented analysis of the influence of parameters of state of the process of control on the increase of the fuel consumption of heat power generating units. There are presented results of calculations of the increase of the fuel consumption at the deviation of the working steam temperature and pressure from rated values. Result of calculus is compared with the experiment.

A novel surgical strategy for secondary hyperparathyroidism: Purge parathyroidectomy.

Science.gov (United States)

Shan, Cheng-Xiang; Qiu, Nian-Cun; Zha, Si-Luo; Liu, Miao-E; Wang, Qiang; Zhu, Pei-Pei; Du, Zhi-Peng; Xia, Chun-Yan; Qiu, Ming; Zhang, Wei

2017-07-01

This study was intended to demonstrate the feasibility and efficacy of purge parathyroidectomy (PPTX) for patients with secondary hyperparathyroidism (SHPT). The "seed, environment, and soil" medical hypothesis was first raised, following review of the literatures, to demonstrate the possible causes of persistence or recurrence of SHPT after parathyroidectomy. Subsequently, the novel surgical strategy of PPTX was proposed, which involves comprehensive resection of the fibro-fatty tissues, including visible or invisible parathyroid, within the region surrounded by the thyroid cartilage, bilateral carotid artery sheath, and the brachiocephalic artery. The perioperative information and clinical outcomes of patients who underwent PPTX from June 2016 to December 2016 were analyzed. In total, PPTX was performed safely in nine patients with SHPT from June 2016 to December 2016. The operative time for PPTX ranged from 95 to 135 min, and blood loss ranged from 20 to 40 mL. No patients with perioperative death, bleeding, convulsions, or recurrent laryngeal nerve injury were reported. The preoperative concentration of PTH ranged from 1062 to 2879 pg/mL, and from 12.35 to 72.69 pg/mL on the first day after surgery. In total, 37 parathyroid glands were resected. The postoperative pathologic examination showed that supernumerary or ectopic parathyroid tissues were found within the "non-parathyroid" tissues in three patients. No cases encountered persistence or recurrence of SHPT, or severe hypocalcemia during the follow-up period. PPTX involves comprehensive resection of supernumerary and ectopic parathyroid tissues, which may provide a more permanent means of reducing PTH levels. Copyright © 2017. Published by Elsevier Ltd.

Heat balance calculation and feasibility analysis for initial startup of Fuqing nuclear turbine unit with non-nuclear steam

International Nuclear Information System (INIS)

He Liu; Xiao Bo; Song Yumeng

2014-01-01

Non-nuclear steam run up compared with nuclear steam run up, can verify the design, manufacture, installation quality of the unit, at the same time shorten the follow-up duration of the entire group ready to start debugging time. In this paper, starting from the first law of thermodynamics, Analyzed Heat balance Calculation and Feasibility analysis for Initial startup of Fuqing nuclear Turbine unit with Non-nuclear steam, By the above calculation, to the system requirements and device status on the basis of technical specifications, confirmed the feasibility of Non-nuclear steam running up in theory. After the implementation of the Non-nuclear turn of Fuqing unit, confirmed the results fit with the actual process. In summary, the Initial startup of Fuqing turbine unit with Non-nuclear steam is feasible. (authors)

Process for forming thin film, heat treatment process of thin film sheet, and heat treatment apparatus therefor

International Nuclear Information System (INIS)

Watanabe, S.

1984-01-01

The invention provides a process for forming a magnetic thin film on a base film, a heat treatment process of a thin film sheet consisting of the base film and the magnetic thin film, and an apparatus for performing heat treatment of the thin film sheet. Tension applied to the thin film sheet is substantially equal to that applied to the base film when the magnetic thin film is formed thereon. Then, the thin film sheet is treated with heat. The thin film sheet is heated with a given temperature gradient to a reactive temperature at which heat shrinkage occurs, while the tension is being applied thereto. Thereafter, the thin film sheet to which the tension is still applied is cooled with substantially the same temperature gradient as applied in heating. The heat treatment apparatus has a film driving unit including a supply reel, a take-up reel, a drive source and guide rollers; a heating unit including heating plates, heater blocks and a temperature controller for heating the sheet to the reactive temperature; and a heat insulating unit including a thermostat and another temperature controller for maintaining the sheet at the nonreactive temperature which is slightly lower than the reactive temperature

Heat waves in the United States: mortality risk during heat waves and effect modification by heat wave characteristics in 43 U.S. communities.

Science.gov (United States)

Anderson, G Brooke; Bell, Michelle L

2011-02-01

Devastating health effects from recent heat waves, and projected increases in frequency, duration, and severity of heat waves from climate change, highlight the importance of understanding health consequences of heat waves. We analyzed mortality risk for heat waves in 43 U.S. cities (1987-2005) and investigated how effects relate to heat waves' intensity, duration, or timing in season. Heat waves were defined as ≥ 2 days with temperature ≥ 95th percentile for the community for 1 May through 30 September. Heat waves were characterized by their intensity, duration, and timing in season. Within each community, we estimated mortality risk during each heat wave compared with non-heat wave days, controlling for potential confounders. We combined individual heat wave effect estimates using Bayesian hierarchical modeling to generate overall effects at the community, regional, and national levels. We estimated how heat wave mortality effects were modified by heat wave characteristics (intensity, duration, timing in season). Nationally, mortality increased 3.74% [95% posterior interval (PI), 2.29-5.22%] during heat waves compared with non-heat wave days. Heat wave mortality risk increased 2.49% for every 1°F increase in heat wave intensity and 0.38% for every 1-day increase in heat wave duration. Mortality increased 5.04% (95% PI, 3.06-7.06%) during the first heat wave of the summer versus 2.65% (95% PI, 1.14-4.18%) during later heat waves, compared with non-heat wave days. Heat wave mortality impacts and effect modification by heat wave characteristics were more pronounced in the Northeast and Midwest compared with the South. We found higher mortality risk from heat waves that were more intense or longer, or those occurring earlier in summer. These findings have implications for decision makers and researchers estimating health effects from climate change.

Loss of residual heat removal system: Diablo Canyon, Unit 2, April 10, 1987

International Nuclear Information System (INIS)

1987-06-01

This report presents the findings of an NRC Augmented Inspection Team (AIT) investigation into the circumstances associated with the loss of residual heat removal (RHR) system capability for a period of approximately one and one-half hours at the Diablo Canyon, Unit 2 reactor facility on April 10, 1987. This event occurred while the Diablo Canyon, Unit 2, a pressurized water reactor, was shutdown with the reactor coolant system (RCS) water level drained to approximately mid-level of the hot leg piping. The reactor containment building equipment hatch was removed at the time of the event, and plant personnel were in the process of removing the primary side manways to gain access into the steam generator channel head areas. Thus, two fission product barriers were breached throughout the event. The RCS temperature increased from approximately 87 0 F to bulk boiling conditions without RCS temperature indication available to the plant operators. The RCS was subsequently pressurized to approximately 7 to 10 psig. The NRC AIT members concluded that the Diablo Canyon, Unit 2 plant was, at the time of the event, in a condition not previously analyzed by the NRC staff. The AIT findings from this event appear significant and generic to other pressurized water reactor facilities licensed by the NRC

Microwave processing heats up

Science.gov (United States)

Microwaves are a common appliance in many households. In the United States microwave heating is the third most popular domestic heating method food foods. Microwave heating is also a commercial food processing technology that has been applied for cooking, drying, and tempering foods. It's use in ...

Mechanical ventilation with heat recovery in arctic climate

DEFF Research Database (Denmark)

Kragh, Jesper; Svendsen, Svend

2005-01-01

Mechanical ventilations systems with highly effective heat recovery units in arctic climate have problems with condensing water from the extracted humid indoor air. If the condensing water freezes to ice in the heat recovery unit, the airflow rate will quickly diminish due to the increasing...... pressure drop. Preheating the inlet air (outdoor air) to a temperature just above 0ºC is typically used to solve the problem. To minimize the energy cost, a more efficient solution to the problem is therefore desirable. In this project a new design of a heat recovery unit has been developed to the low......-energy house in Sisimiut, which is capable of continuously defrosting itself. The disadvantage of the unit is that it is quite big compared with other units. In this paper the new heat recovery unit is described and laboratory measurements are presented showing that the unit is capable of continuously...

Stochastic PSO-based heat and power dispatch under environmental constraints incorporating CHP and wind power units

Energy Technology Data Exchange (ETDEWEB)

Piperagkas, G.S.; Anastasiadis, A.G.; Hatziargyriou, N.D. [National Technical University of Athens, School of Electrical and Computer Engineering, Electric Power Division, 9, Iroon Polytechneiou Str., GR-15773 Zografou, Athens (Greece)

2011-01-15

In this paper an extended stochastic multi-objective model for economic dispatch (ED) is proposed, that incorporates in the optimization process heat and power from CHP units and expected wind power. Stochastic restrictions for the CO{sub 2}, SO{sub 2} and NO{sub x} emissions are used as inequality constraints. The ED problem is solved using a multi-objective particle swarm optimization technique. The available wind power is estimated from a transformation of the wind speed considered as a random variable to wind power. Simulations are performed on the modified IEEE 30 bus network with 2 cogeneration units and actual wind data. Results concerning minimum cost and emissions reduction options are finally drawn. (author)

HEAT PUMP USING SUBSOIL WATERS AS LOW TEMPERATURE HEAT SOURCE

Directory of Open Access Journals (Sweden)

Denysova Alla

2015-08-01

Full Text Available One of the basic directions of perfection of heat supply systems is the tendency of transition to the low-temperature heating systems based on application of heat pump installations. We consider heat supply system with heat pump installations using subsoil waters. Numerical simulation of thermal processes in the elements of a single-stage and double-stage heat pump systems has been worked out. Values of depths of wells and their quantity, necessary for effective operation of the offered installations, and values of capacity of electric water pumps for subsoil waters unit are calculated. Capacity of compressor electric drive and coefficient of performance of heat pump for the conditions of the city of Odessa are presented.

Design and functionality of a segmented heat-storage prototype utilizing stable supercooling of sodium acetate trihydrate in a solar heating system

DEFF Research Database (Denmark)

Englmair, Gerald; Moser, Christoph; Furbo, Simon

2018-01-01

acetate trihydrate composites to conserve the latent heat of fusion for long-term heat storage. A control strategy directed heat from a solar collector array to either the PCM storage or a water buffer storage. Several PCM units had to be charged in parallel when the solar collector output peaked at 16 k......A solar heating system with 22.4m2 of solar collectors, a heat storage prototype consisting of four 200 kg phase-change material (PCM) storage units, and a 735 L water tank was designed to improve solar heat supply in single-family houses. The PCM storage utilized stable supercooling of sodium......W. A single unit was charged with 27.4 kWh of heat within four hours on a sunny day, and the PCM temperature increased from 20 °C to 80 °C. The sensible heat from a single PCM unit was transferred to the water tank starting with about 32 kW of thermal power after it had fully melted at 80 °C. A mechanical...

Experimental study of enhancing heating performance of the air-source heat pump by using a novel heat recovery device designed for reusing the energy of the compressor shell

International Nuclear Information System (INIS)

Huang, Bi; Jian, Qifei; Luo, Lizhong; Zhao, Jing

2017-01-01

Highlights: • A novel heat recovery device was designed and tested. • Aiming at avoiding liquid slugging in cold areas. • Recovery of the waste energy of compressor housing. • Refrigerant is heated with the energy recovered before it is sucked into the compressor. • Requires no extra power while the recovery system is operating. - Abstract: A novel heat recovery device designed to recover the heat that is released from the outer surface of heat pump compressors, and to enhance the performance of heat pumps in cold areas was made and tested in this study. The novel heat recovery device consists of three fundamental units: a heat absorption unit, a heat emission unit and heat pipes. An amount of work focused on recovering the heat of compressors through oil system, but few studies concentrated on the housing. The main advantage of the heat recovery device is no need for extra energy consumption for its only driving force is the temperature difference between the compressor shell and the working fluid inside the suction line. The experimental results were obtained from a series of tests with a R410A air-source heat pump. Effects of the device are analyzed with respect of the suction temperature, temperature distribution among the housing, input power and exergy destruction. Moreover, the impact on the heating capacity is also discussed. Further, direction for improvement is also given based on the analysis.

Stochastic Multicriteria Acceptability Analysis for Evaluation of Combined Heat and Power Units

Directory of Open Access Journals (Sweden)

Haichao Wang

2014-12-01

Full Text Available Combined heat and power (CHP is a promising technology that can contribute to energy efficiency and environmental protection. More CHP-based energy systems are planned for the future. This makes the evaluation and selection of CHP systems very important. In this paper, 16 CHP units representing different technologies are taken into account for multicriteria evaluation with respect to the end users’ requirements. These CHP technologies cover a wide range of power outputs and fuel types. They are evaluated from the energy, economy and environment (3E points of view, specifically including the criteria of efficiency, investment cost, electricity cost, heat cost, CO2 production and footprint. Uncertainties and imprecision are common both in criteria measurements and weights, therefore the stochastic multicriteria acceptability analysis (SMAA model is used in aiding this decision making problem. These uncertainties are treated better using a probability distribution function and Monte Carlo simulation in the model. Moreover, the idea of “feasible weight space (FWS” which represents the union of all preference information from decision makers (DMs is proposed. A complementary judgment matrix (CJM is introduced to determine the FWS. It can be found that the idea of FWS plus CJM is well compatible with SMAA and thus make the evaluation reliable.

Electric heating of a unit for uranium trioxide production

International Nuclear Information System (INIS)

Faron, R.; Striff, A.

1985-01-01

Ammonium diuranate U 2 O 7 (NH 4 ) 2 containing about 50% of water is dried and transformed by calcination in uranium trioxide UO 3 . Drying and calcination was obtained by air heated by two burners using domestic fuel. In 1984 the plant was transformed for utilization of electric heating improving maintenance cost, decreasing heat losses and by energy saving the payback period on investment is of 2.6 years [fr

Reward Dependence and Harm Avoidance among Patients with Binge-Purge Type Eating Disorders.

Science.gov (United States)

Gat-Lazer, Sigal; Geva, Ronny; Gur, Eitan; Stein, Daniel

2017-05-01

The Cloninger's Psychobiological Model of Temperament and Character includes temperamental dimensions such as reward dependence (RD) and harm avoidance (HA). Studies of RD differentiate between sensitivity to reward (SR) versus to punishment (SP). We investigated the interrelationship between HA and RD in acutely ill patients with binge/purge (B/P) type eating disorders (EDs) and following symptomatic stabilization. Fifty patients with B/P EDs were assessed at admission to inpatient treatment, 36 of whom were reassessed at discharge. Thirty-six controls were similarly assessed. Participants completed Tridimensional Personality Questionnaire (TPQ), Sensitivity to Punishment and Sensitivity to Reward Questionnaire (SPSRQ), and took the Gambling Task. Patients with B/P EDs had higher TPQ-RD and lower TPQ-HA accompanied by lower SPSRQ-SR and SPSRQ-SP. SPSRQ-SP correlated positively and negatively with TPQ-HA and TPQ-RD, respectively. Combination of lower TPQ-HA, lower SPSRQ-SP, and greater risk-taking inclination may maintain disordered eating in patients with B/P EDs. Copyright © 2017 John Wiley & Sons, Ltd and Eating Disorders Association. Copyright © 2017 John Wiley & Sons, Ltd and Eating Disorders Association.

The epidemiology of occupational heat exposure in the United States: a review of the literature and assessment of research needs in a changing climate

Science.gov (United States)

Gubernot, Diane M.; Anderson, G. Brooke; Hunting, Katherine L.

2014-10-01

In recent years, the United States has experienced record-breaking summer heat. Climate change models forecast increasing US temperatures and more frequent heat wave events in the coming years. Exposure to environmental heat is a significant, but overlooked, workplace hazard that has not been well-characterized or studied. The working population is diverse; job function, age, fitness level, and risk factors to heat-related illnesses vary. Yet few studies have examined or characterized the incidence of occupational heat-related morbidity and mortality. There are no federal regulatory standards to protect workers from environmental heat exposure. With climate change as a driver for adaptation and prevention of heat disorders, crafting policy to characterize and prevent occupational heat stress for both indoor and outdoor workers is increasingly sensible, practical, and imperative.

Heat networks in France in 2014. Heat networks: which price for the consumer?

International Nuclear Information System (INIS)

Reynaud, Didier; Gong, Zheng; Moreau, Sylvain; Bottin, Anne; Reperant, Patricia

2016-04-01

A first document publishes and comments various statistics regarding heat networks in France in 2014: distribution in terms of quantity of supplied heat, main urban units, distribution in terms of urban unit size and in terms of community type (land, isolated town, outskirts, centre town). It also indicates the types, percentages and evolution of energies consumed in these heat networks, the shares of fossil and renewable energies, and the distribution of networks in terms of energy type. Some regional data are briefly commented (energy shares in each region, number of primary housing connected to an urban heating network). This publication also indicates methodological aspects and the definitions of the main components and characteristics of a heat network. Notably based on some of these data, the second document comments the price of heat supplied in these heat networks in 2014 as these prices are not regulated and depend on agreements between clients and providers. These prices are analysed in terms of linear thermal density, of heat quantity supplied by delivery point, of sector (industry, housing, office building), of rate of renewable energy, and of operator status (public service delegation or private ownership)

Heat illness and death among workers - United States, 2012-2013.

Science.gov (United States)

Arbury, Sheila; Jacklitsch, Brenda; Farquah, Opeyemi; Hodgson, Michael; Lamson, Glenn; Martin, Heather; Profitt, Audrey

2014-08-08

Exposure to heat and hot environments puts workers at risk for heat stress, which can result in heat illnesses and death. This report describes findings from a review of 2012‒2013 Occupational Safety and Health Administration (OSHA) federal enforcement cases (i.e., inspections) resulting in citations under paragraph 5(a)(1), the "general duty clause" of the Occupational Safety and Health Act of 1970. That clause requires that each employer "furnish to each of his employees employment and a place of employment which are free from recognized hazards that are causing or are likely to cause death or serious physical harm to his employees". Because OSHA has not issued a heat standard, it must use 5(a)(1) citations in cases of heat illness or death to enforce employers' obligations to provide a safe and healthy workplace. During the 2-year period reviewed, 20 cases of heat illness or death were cited for federal enforcement under paragraph 5(a)(1) among 18 private employers and two federal agencies. In 13 cases, a worker died from heat exposure, and in seven cases, two or more employees experienced symptoms of heat illness. Most of the affected employees worked outdoors, and all performed heavy or moderate work, as defined by the American Conference of Governmental Industrial Hygienists. Nine of the deaths occurred in the first 3 days of working on the job, four of them occurring on the worker's first day. Heat illness prevention programs at these workplaces were found to be incomplete or absent, and no provision was made for the acclimatization of new workers. Acclimatization is the result of beneficial physiologic adaptations (e.g., increased sweating efficiency and stabilization of circulation) that occur after gradually increased exposure to heat or a hot environment. Whenever a potential exists for workers to be exposed to heat or hot environments, employers should implement heat illness prevention programs (including acclimatization requirements) at their

Evaluating the energy and CO2 emissions impacts of shifts in residential water heating in the United States

International Nuclear Information System (INIS)

Sanders, Kelly T.; Webber, Michael E.

2015-01-01

Water heating represented nearly 13% of 2010 residential energy consumption making it an important target for energy conservation efforts. The objective of this work is to identify spatially-resolved strategies for energy conservation, since little analysis has been done to identify how regional characteristics affect the energy consumed for water heating. We present a first-order thermodynamic analysis, utilizing ab initio calculations and regression methods, to quantify primary energy consumption and CO 2 emissions with regional specificity by considering by considering local electricity mixes, heat rates, solar radiation profiles, heating degrees days, and water heating unit sales for 27 regions of the US. Results suggest that shifting from electric towards natural gas or solar water heating offered primary energy and CO 2 emission reductions in most US regions, but these reductions varied considerably according to regional electricity mix and solar resources. We find that regions that would benefit most from technology transitions, are often least likely to switch due to limited economic incentives. Our results suggest that federal energy factor metrics, which ignore upstream losses in power generation, are insufficient in informing consumers about the energy performance of residential end use appliances. - Highlights: • US energy factor ratings for water heaters ignore upstream losses. • Switching from electric storage water heating reduces CO 2 emissions in most US regions. • Regions with greatest potential for CO 2 avoidance are least likely to shift technologies. • Benefits vary significantly according to climate and regional electricity fuel mix

Heat Roadmap Europe

DEFF Research Database (Denmark)

Connolly, David; Mathiesen, Brian Vad; Lund, Henrik

2015-01-01

This document is a summary of the key technical inputs for the modelling of the heat strategy for Europe outlined in the latest Heat Roadmap Europe studies [1, 2]. These studies quantify the impact of alternative heating strategies for Europe in 2030 and 2050. The study is based on geographical...... information systems (GIS) and energy system analyses. In this report, the inputs for other modelling tools such as PRIMES are presented, in order to enable other researches to generate similar heating scenarios for Europe. Although Heat Roadmap Europe presents a complete heat strategy for Europe, which...... includes energy efficiency, individual heating units (such as boilers and heat pumps), and heat networks, the recommendations here are primarily relating to the potential and modelling of district heating. Although other solutions will play a significant role in decarbonising the heating and cooling sector...

Solar/electric heating systems for the future energy system

DEFF Research Database (Denmark)

Furbo, Simon; Dannemand, Mark; Perers, Bengt

elements/heat pump, advanced heat storage tanks and advanced control systems. Heat is produced by solar collectors in sunny periods and by electrical heating elements/heat pump. The electrical heating elements/heat pump will be in operation in periods where the heat demand cannot be covered by solar energy....... The aim is to use the auxiliary heating units when the electricity price is low, e.g. due to large electricity production by wind turbines. The unit is equipped with an advanced control system where the control of the auxiliary heating is based on forecasts of the electricity price, the heat demand...

Non-linear advanced control of the LHC inner triplet heat exchanger test unit

International Nuclear Information System (INIS)

Vinuela, E. Blanco; Cubillos, J. Casas; Prada Moraga, C. de; Cristea, S.

2002-01-01

The future Large Hadron Collider (LHC) at CERN will include eight interaction region final focus magnet systems, the so-called 'Inner Triplet', one on each side of the four beam collision points. The Inner Triplets will be cooled in a static bath of pressurized He II nominally at 1.9 K. This temperature is a control parameter and has very severe constraints in order to avoid the transition from the superconducting to normal resistive state. The main difference in these special zones with respect to a regular LHC cell is higher dynamic heat load unevenly distributed which modifies largely the process characteristics and hence the controller performance. Several control strategies have already been tested at CERN in a pilot plant (LHC String Test) which reproduced a LHC half-cell. In order to validate a common control structure along the whole LHC ring, a Nonlinear Model Predictive Control (NMPC) has been developed and implemented in the Inner Triplet Heat Exchanger Unit (IT-HXTU) at CERN. Automation of the Inner Triplet setup and the advanced control techniques deployed based on the Model Based Predictive Control (MBPC) principle are presented

Evaluation of RELAP5 MOD 3.1.1 code with GIRAFFE Test Facility: Phase 1, Step 2 nitrogen venting tests

International Nuclear Information System (INIS)

Boyer, B.D.; Slovik, G.C.; Rohatgl, U.S.

1995-01-01

The Simplified Boiling Water Reactor (SBWR) proposed by General Electric (GE) is an advanced light water reactor (ALWR) design that utilizes passive safety systems. The PCCS is a series of heat exchangers submerged in water and open to the containment. Since the containment is inerted with nitrogen during normal operation, the PCCS must condense the steam in the presence of noncondensable gases during an accident. To model the transient behavior of the SBWR with a system code, the code should properly simulate the expected phenomena. To validate the applicability of RELAP5 MOD 3.1.1, the data from three Phase 1, Step 2 nitrogen venting tests at Toshiba's Gravity-Driven Integral Full-Height Test for Passive Heat Removal facility and RELAP5 calculations of these tests were compared. The comparison of the GIRAFFE data against the results from the RELAP5 calculations showed that it can predict condensation and gas purging phenomena occurring in the long-term decay heat rejection phase. In this phase of the transient, condensation in the PCCS is the only means to reject heat from the SBWR containment. In the two tests where the nitrogen purge vent line was at its deepest submergence in the Suppression Pool (SIP), the RELAP5 results mirrored the behavior of the containment pressures and of the water levels in the Horizontal Vent (HV) and the nitrogen purge line tube of the GIRAFFE data. However, in the test with the shallowest purge line submergence, there was appreciable direct contact condensation on the pool surface of the HV despite modeling efforts to deter these phenomena. This surface condensation, unobserved in the GIRAFFE tests, was a major cause of RELAP5 predicting early containment depressurization and the subsequent early rise in HV and nitrogen purge line water levels. The present RELAP5 MOD3.1.1 interfacial heat and mass transfer model does not properly degrade direct contact steam condensation in the presence of noncondensable gases sitting on a pool

Identification of Aroma Compounds of Lamiaceae Species in Turkey Using the Purge and Trap Technique

Directory of Open Access Journals (Sweden)

Ahmet Salih Sonmezdag

2017-02-01

Full Text Available The present research was planned to characterize the aroma composition of important members of the Lamiaceae family such as Salvia officinalis, Lavandula angustifolia and Mentha asiatica. Aroma components of the S. officinalis, L. angustifolia and M. asiatica were extracted with the purge and trap technique with dichloromethane and analyzed with the gas chromatography–mass spectrometry (GC–MS technique. A total of 23, 33 and 33 aroma compounds were detected in Salvia officinalis, Lavandula angustifolia and Mentha asiatica, respectively including, acids, alcohols, aldehydes, esters, hydrocarbons and terpenes. Terpene compounds were both qualitatively and quantitatively the major chemical group among the identified aroma compounds, followed by esters. The main terpene compounds were 1,8-cineole, sabinene and linalool in Salvia officinalis, Lavandula angustifolia and Mentha asiatica, respectively. Among esters, linalyl acetate was the only and most important ester compound which was detected in all samples.

Identification of Aroma Compounds of Lamiaceae Species in Turkey Using the Purge and Trap Technique

Science.gov (United States)

Sonmezdag, Ahmet Salih; Kelebek, Hasim; Selli, Serkan

2017-01-01

The present research was planned to characterize the aroma composition of important members of the Lamiaceae family such as Salvia officinalis, Lavandula angustifolia and Mentha asiatica. Aroma components of the S. officinalis, L. angustifolia and M. asiatica were extracted with the purge and trap technique with dichloromethane and analyzed with the gas chromatography–mass spectrometry (GC–MS) technique. A total of 23, 33 and 33 aroma compounds were detected in Salvia officinalis, Lavandula angustifolia and Mentha asiatica, respectively including, acids, alcohols, aldehydes, esters, hydrocarbons and terpenes. Terpene compounds were both qualitatively and quantitatively the major chemical group among the identified aroma compounds, followed by esters. The main terpene compounds were 1,8-cineole, sabinene and linalool in Salvia officinalis, Lavandula angustifolia and Mentha asiatica, respectively. Among esters, linalyl acetate was the only and most important ester compound which was detected in all samples. PMID:28231089

Development of a gas fired Vuilleumier heat pump for residential heating

DEFF Research Database (Denmark)

Carlsen, Henrik

1989-01-01

A natural gas-driven heat pump based on the Vuilleumier principle has been developed for use in single-family houses. The pump has a heat output of 7.5 kW at a coefficient of performance of 1.62 based on the lower heat content of the gas fuel. The heat pump uses helium as working fluid at 20 MPa...... mean pressure, and it is designed as a semihermetic unit. A crank mechanism distinguished by very small loads on the piston rings was developed. The advantages and disadvantages of the Vuilleumier principle for heat-driven heat pumps are discussed. Results of the extensive experimental work...... are presented. A new 20 kW Vuilleumier heat pump is briefly described...

Refrigeration Playbook. Heat Reclaim; Optimizing Heat Rejection and Refrigeration Heat Reclaim for Supermarket Energy Conservation

Energy Technology Data Exchange (ETDEWEB)

Reis, Chuck [CTA Architects Engineers, Boise, ID (United States); Nelson, Eric [CTA Architects Engineers, Boise, ID (United States); Armer, James [CTA Architects Engineers, Boise, ID (United States); Johnson, Tim [CTA Architects Engineers, Boise, ID (United States); Hirsch, Adam [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Doebber, Ian [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2015-03-01

The purpose of this playbook and accompanying spreadsheets is to generalize the detailed CBP analysis and to put tools in the hands of experienced refrigeration designers to evaluate multiple applications of refrigeration waste heat reclaim across the United States. Supermarkets with large portfolios of similar buildings can use these tools to assess the impact of large-scale implementation of heat reclaim systems. In addition, the playbook provides best practices for implementing heat reclaim systems to achieve the best long-term performance possible. It includes guidance on operations and maintenance as well as measurement and verification.

Comparison of heat-testing methodology.

Science.gov (United States)

Bierma, Mark M; McClanahan, Scott; Baisden, Michael K; Bowles, Walter R

2012-08-01

Patients with irreversible pulpitis occasionally present with a chief complaint of sensitivity to heat. To appropriately diagnose the offending tooth, a variety of techniques have been developed to reproduce this chief complaint. Such techniques cause temperature increases that are potentially damaging to the pulp. Newer electronic instruments control the temperature of a heat-testing tip that is placed directly against a tooth. The aim of this study was to determine which method produced the most consistent and safe temperature increase within the pulp. This consistency facilitates the clinician's ability to differentiate between a normal pulp and irreversible pulpitis. Four operators applied the following methods to each of 4 extracted maxillary premolars (for a total of 16 trials per method): heated gutta-percha, heated ball burnisher, hot water, and a System B unit or Elements unit with a heat-testing tip. Each test was performed for 60 seconds, and the temperatures were recorded via a thermocouple in the pulp chamber. Analysis of the data was performed by using the intraclass correlation coefficient. The least consistent warming was found with hot water. The heat-testing tip also demonstrated greater consistency between operators compared with the other methods. Hot water and the heated ball burnisher caused temperature increases high enough to damage pulp tissue. The Elements unit with a heat-testing tip provides the most consistent warming of the dental pulp. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Direct Heat

Energy Technology Data Exchange (ETDEWEB)

Lienau, P J

1990-01-01

Potential resources and applications of earth heat in the form of geothermal energy are large. United States direct uses amount to 2,100 MWt thermal and worldwide 8,850 MWt above a reference temperature of 35 degrees Celsius. Space and district heating are the major direct uses of geothermal energy. Equipment employed in direct use projects is of standard manufacture and includes downhole and circulation pumps, transmission and distribution pipelines, heat exchangers and convectors, heat pumps and chillers. Direct uses of earth heat discussed are space and district heating, greenhouse heating and fish farming, process and industrial applications. The economic feasibility of direct use projects is governed by site specific factors such as location of user and resource, resource quality, system load factor and load density, as well as financing. Examples are presented of district heating in Klamath Falls, and Elko. Further developments of direct uses of geothermal energy will depend on matching user needs to the resource, and improving load factors and load density.

Impacts of global warming on residential heating and cooling degree-days in the United States.

Science.gov (United States)

Petri, Yana; Caldeira, Ken

2015-08-04

Climate change is expected to decrease heating demand and increase cooling demand for buildings and affect outdoor thermal comfort. Here, we project changes in residential heating degree-days (HDD) and cooling degree-days (CDD) for the historical (1981-2010) and future (2080-2099) periods in the United States using median results from the Climate Model Intercomparison Project phase 5 (CMIP5) simulations under the Representation Concentration Pathway 8.5 (RCP8.5) scenario. We project future HDD and CDD values by adding CMIP5 projected changes to values based on historical observations of US climate. The sum HDD + CDD is an indicator of locations that are thermally comfortable, with low heating and cooling demand. By the end of the century, station median HDD + CDD will be reduced in the contiguous US, decreasing in the North and increasing in the South. Under the unmitigated RCP8.5 scenario, by the end of this century, in terms of HDD and CDD values considered separately, future New York, NY, is anticipated to become more like present Oklahoma City, OK; Denver, CO, becomes more like Raleigh, NC, and Seattle, WA, becomes more like San Jose, CA. These results serve as an indicator of projected climate change and can help inform decision-making.

Impacts of global warming on residential heating and cooling degree-days in the United States

Science.gov (United States)

Petri, Yana; Caldeira, Ken

2015-01-01

Climate change is expected to decrease heating demand and increase cooling demand for buildings and affect outdoor thermal comfort. Here, we project changes in residential heating degree-days (HDD) and cooling degree-days (CDD) for the historical (1981–2010) and future (2080–2099) periods in the United States using median results from the Climate Model Intercomparison Project phase 5 (CMIP5) simulations under the Representation Concentration Pathway 8.5 (RCP8.5) scenario. We project future HDD and CDD values by adding CMIP5 projected changes to values based on historical observations of US climate. The sum HDD + CDD is an indicator of locations that are thermally comfortable, with low heating and cooling demand. By the end of the century, station median HDD + CDD will be reduced in the contiguous US, decreasing in the North and increasing in the South. Under the unmitigated RCP8.5 scenario, by the end of this century, in terms of HDD and CDD values considered separately, future New York, NY, is anticipated to become more like present Oklahoma City, OK; Denver, CO, becomes more like Raleigh, NC, and Seattle, WA, becomes more like San Jose, CA. These results serve as an indicator of projected climate change and can help inform decision-making. PMID:26238673

A modeling approach for district heating systems with focus on transient heat transfer in pipe networks

DEFF Research Database (Denmark)

Mohammadi, Soma; Bojesen, Carsten

2015-01-01

the temperature in DH systems. The main focus is on modeling transient heat transfer in pipe networks regarding the time delays between the heat supply unit and the consumers, the heat loss in the pipe networks and the consumers’ dynamic heat loads. A pseudo-dynamic approach is adopted and also the implicit...... district heating networks [DHN] characteristics. This paper is presenting a new developed model, which reflects the thermo-dynamic behavior of DHN. It is designed for tree network topologies. The purpose of the model is to serve as a basis for applying a variety of scenarios towards lowering...... finite element method is applied to simulate transient temperature changes in pipe networks. The model is calculating time series data related to supply temperature to the DHN from heat production units, heat loads and return temperature related to each consumer to calculate dynamic temperature changes...

Low resource ventilation unit; Ressourcebesparende ventilationsenhed

Energy Technology Data Exchange (ETDEWEB)

Drivsholm, C.

2012-03-15

In the project a resource-saving ventilation device was developed which is based on the use of a regenerator and a reversible air flow. The regenerator is placed in the building envelope, and the concept works in the way that the heat in the air during ventilation is stored in the regenerator and brought back into the building by a reversible air change. The heated air is blown from inside the building out through the regenerator. In this way the regenerator accumulates the heat in the air. Over a period of 30-120 seconds, the regenerator capacity is utilized. When the regenerator cannot be further heated, the air flow is reversed and there is now blown cold air through the regenerator. Thereby the heat from the regenerator is released to the cold fresh air. Thus, the fresh air brings heat back into the building, whereby the air is replaced with a limited heat loss. Ventilation with a regenerator is described as micro-ventilation. The developed micro-ventilation unit was tested by the Danish Technological Institute. The test results shows that the unit performs according to expectations: 1) The heat recovery is 85%; 2) The flow through the unit is 80m3 per hour in a 5 section unit; 3) The noise level is 30 db(A) in a representative room; 4) The energy consumption is <300 J/m3. The unit is introduced into the market, and the first plants have been sold. (LN)

Solar unit

Energy Technology Data Exchange (ETDEWEB)

Sukhanov, A M; Trushevskiy, S N; Tveryanovich, E V

1982-01-01

A solar unit is proposed which contains an inclined solar collector with supply and outlet pipelines, the first of which is connected to the source of a heat carrier, while the second is connected through the valve to the tank for collecting heated heat carrier equipped with a device for recovery. In order to improve the effectiveness of heating the heat carrier, it additionally contains a concentrator of solar radiation and a device for maintaining a level of the heat carrier in the collector in the zone of the focal spot of the concentrator, while the heat pipeline is connected to the source of the heat carrier with the help of a device for maintaining the level of the heat carrier.

Energy and cost savings potential of oscillating heat pipes for waste heat recovery ventilation

Directory of Open Access Journals (Sweden)

Govinda Mahajan

2017-11-01

Full Text Available The feasibility of using finned oscillating heat pipes (OHPs for heat exchange between counter-flowing air streams in HVAC air systems (i.e., outdoor and exhaust air flows, along with the associated cost savings in typical North American climates, is investigated. For a prescribed temperature difference and volumetric flow rate of air, rudimentary design parameters for a viable OHP Heat Recovery Ventilator (OHP-HRV were determined using the ε-NTU (effectiveness-Number of Transfer Unit method. The two-phase heat transfer within the OHP-HRV is modeled via effective evaporation/condensation heat transfer coefficients, while the latent heat transfer required to initiate OHP operation via boiling and evaporation is also considered. Results suggest that an OHP-HRV can possess a reasonable pressure drop (5 kW. The proposed OHP-HRV can possess an effectiveness near 0.5 and can pre-cool/heat HVAC air by >5°C. Potential energy and cost savings associated with using an OHP-HRV were estimated for commercial building envelopes in various regions of the United States. It is found that the proposed OHP-HRV can save more than $2500 annually in cities that have continental climatic conditions, such as Chicago and Denver, and for the selected locations the average yearly cost savings per building is found to be on-the-order of $700. Overall, the OHP-HRV shows potential in effectively reducing energy consumption and the operational cost of air handling units in buildings.

Development of a method for calculating steady-state equipment sensible heat ratio of direct expansion air conditioning units

International Nuclear Information System (INIS)

Xia Liang; Chan, M.Y.; Deng Shiming

2008-01-01

A complete set of calculation method for steady-state equipment sensible heat ratio (SHR) for a direct expansion (DX) cooling coil has been developed and reported. The method was based on the fundamentals of energy conservation and heat and mass transfer taking place in the DX cooling coil, and was experimentally validated using an experimental DX A/C rig. With the method developed, the effect of refrigerant evaporating temperature at fixed inlet air conditions on equipment SHR has been theoretically analyzed. The validated method can be useful in further studying the inherent operating characteristics of a DX air conditioning (A/C) unit and in developing suitable control strategies for achieving higher energy efficiency and better indoor thermal environment

Field tests for the comparative evaluation of heat and enthalpy exchangers in compact ventilation units; Feldvergleich von Waerme- und Enthalpieuebertragern in Kompakt-Lueftungsgeraeten - Schlussbericht

Energy Technology Data Exchange (ETDEWEB)

Frei, B.

2007-07-01

In an efficiency review on low energy buildings promoted by the Swiss Federal Office of Energy, low air humidity has been measured during thousands of annual hours. Modern compact ventilation units are being increasingly offered with transmission of heat and moisture. One possibility to raise the air humidity level is an enthalpy exchanger with steam-permeable membranes. With an enthalpy exchanger you can not only recover heat but also a good part of the humidity of the return air. In a comparative field study alternate applications with enthalpy or heat exchangers have been analysed at four different locations. Also calculations have been made to estimate how a rotating heat exchanger with ion-exchange resin would have performed. The comparative field study has shown that the enthalpy exchanger is able to raise the humidity level. Conditions for this are internal humidity loads, balanced air volume rates which correspond to occupancy as well as low leakages of the ventilation unit. Over-moistening due to the system with enthalpy exchanger was not found. The measurements have been affected by a sequence of winter months which have been partially warmer than usual. Otherwise the difference between enthalpy and heat exchangers would have been more significant. (author)

Waste heat recovery for offshore applications

DEFF Research Database (Denmark)

Pierobon, Leonardo; Kandepu, Rambabu; Haglind, Fredrik

2012-01-01

vary in the range 20-30%. There are several technologies available for onshore gas turbines (and low/medium heat sources) to convert the waste heat into electricity. For offshore applications it is not economical and practical to have a steam bottoming cycle to increase the efficiency of electricity...... production, due to low gas turbine outlet temperature, space and weight restrictions and the need for make-up water. A more promising option for use offshore is organic Rankine cycles (ORC). Moreover, several oil and gas platforms are equipped with waste heat recovery units to recover a part of the thermal...... energy in the gas turbine off-gas using heat exchangers, and the recovered thermal energy acts as heat source for some of the heat loads on the platform. The amount of the recovered thermal energy depends on the heat loads and thus the full potential of waste heat recovery units may not be utilized...

Performance of a reversible heat pump/organic Rankine cycle unit coupled with a passive house to get a positive energy building

DEFF Research Database (Denmark)

Dumont, Olivier; Carmo, Carolina; Fontaine, Valentin

2016-01-01

This paper presents an innovative technology that can be used to deliver more renewable electricity production than the total electrical consumption of a building while covering the heat demand on a yearly basis. The technology concept uses a heat pump (HP), slightly modified to revert its cycle...... and generate electricity, coupled to a solar thermal collector roof. This reversible HP/organic Rankine cycle unit presents three operating modes: direct heating, HP and organic Rankine cycle. This work focuses on describing the dynamic model of the multi-component system followed by a techno-economic analysis......Wh/year and total electrical consumption of 2318 kWh/year) with a 138.8 m2 solar roof in Denmark....

Heat Stroke

DEFF Research Database (Denmark)

Mørch, Sofie Søndergaard; Andersen, Johnny Dohn Holmgren; Bestle, Morten Heiberg

2017-01-01

not diagnosed until several days after admittance; hence treatment with cooling was delayed. Both patients were admitted to the intensive care unit, where they were treated with an external cooling device and received treatment for complications. Both cases ended fatally. As global warming continues, more heat......Heat stroke is an acute, life-threatening emergency characterized clinically by elevated body temperature and central nervous system dysfunction. Early recognition and treatment including aggressive cooling and management of life-threatening systemic complications are essential to reduce morbidity...... and mortality. This case report describes two Danish patients diagnosed with heat stroke syndrome during a heat wave in the summer of 2014. Both patients were morbidly obese and had several predisposing illnesses. However since heat stroke is a rare condition in areas with temperate climate, they were...

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.

Overall conductance and heat transfer area minimization of refrigerators and heat pumps with finite heat reservoirs

International Nuclear Information System (INIS)

Sarkar, J.; Bhattacharyya, Souvik

2007-01-01

In the present study, the overall conductance and the overall heat transfer area per unit capacity of refrigeration and heat pump systems have been minimized analytically considering both internal and external irreversibilities with variable temperature (finite capacity) heat reservoirs. Hot and cold side refrigerant temperatures, conductance and heat transfer area ratios have been optimized to attain this goal. The results have been verified with the more elaborate numerical optimization results obtained for ammonia based vapour compression refrigeration and heat pump systems working with variable temperature reservoirs. It is observed that the analytical results for optimum refrigerant temperatures, minimum overall conductance and heat transfer area deviate marginally from the numerically optimized results (within 1%), if one assumes a constant heat rejection temperature. The deviation of minimum overall conductance and heat transfer area is more (about 20%), if one considers both the desuperheating and condensation regions separately. However, in the absence of complex and elaborate numerical models, the simple analytical results obtained here can be used as reasonably accurate preliminary guidelines for optimization of refrigeration and heat pump systems

Simultaneous determination of eight common odors in natural water body using automatic purge and trap coupled to gas chromatography with mass spectrometry.

Science.gov (United States)

Deng, Xuwei; Liang, Gaodao; Chen, Jun; Qi, Min; Xie, Ping

2011-06-17

Production and fate of taste and odor (T&O) compounds in natural waters are a pressing environmental issue. Simultaneous determination of these complex compounds (covering a wide range of boiling points) has been difficult. A simple and sensitive method for the determination of eight malodors products of cyanobacterial blooms was developed using automatic purge and trap (P&T) coupled with gas chromatography-mass spectrometry (GC-MS). This extraction and concentration technique is solvent-free. Dimethylsulfide (DMS), dimethyltrisulfide (DMTS), 2-isopropyl-3-methoxypyrazine (IPMP), 2-isobutyl-3-methoxypyrazine (IBMP), 2-methylisoborneol (MIB), β-cyclocitral, geosmin (GSM) and β-ionone were separated within 15.3 min. P&T uses trap #07 and high-purity nitrogen purge gas. The calibration curves of the eight odors show good linearity in the range of 1-500 ng/L with a correlation coefficient above 0.999 (levels=8) and with residuals ranging from approximately 83% to 124%. The limits of detection (LOD) (S/N=3) are all below 1.5 ng/L that of GSM is even lower at 0.08 ng/L. The relative standard deviations (RSD) are between 3.38% and 8.59% (n=5) and recoveries of the analytes from water samples of a eutrophic lake are between 80.54% and 114.91%. This method could be widely employed for monitoring these eight odors in natural waters. Copyright © 2011 Elsevier B.V. All rights reserved.

Binge Eating, Purging, or Both: Eating Disorder Psychopathology Findings from an Internet Community Survey

Science.gov (United States)

Roberto, Christina A.; Grilo, Carlos M.; Masheb, Robin M.; White, Marney A.

2010-01-01

Objective This study aimed to compare bulimia nervosa (BN), binge eating disorder (BED), and purging disorder (PD) on clinically significant variables and examine the utility of once versus twice-weekly diagnostic thresholds for disturbed eating behaviors. Method 234 women with BN, BED, or PD were identified through self-report measures via an online survey and categorized based on either once-weekly or twice-weekly disturbed eating behaviors. Results BN emerged as a more severe disorder than BED and PD. The three groups differed significantly in self-reported restraint and disinhibition and the BN and BED groups reported higher levels of depression than PD. For BN, those engaging in behaviors twice-weekly versus once-weekly were more symptomatic. Discussion The BN, BED, and PD groups differed in clinically meaningful ways. Future research need to clarify the relationship between mood disturbances and eating behaviors. Reducing the twice-weekly behavior threshold for BN would capture individuals with clinically significant eating disorders, though the twice-weekly threshold may provide important information about disorder severity for both BN and BED. PMID:19862702

The influence of heat exchanger design on the synthesis of heat exchanger networks

Directory of Open Access Journals (Sweden)

Liporace F.S.

2000-01-01

Full Text Available Heat exchanger network (HEN synthesis has been traditionally performed without accounting for a more detailed unit design, which is important since the final HEN may require unfeasible units. Recently, publications on this matter have appeared, as well as softwares that simultaneously perform synthesis and units design. However, these publications do not clearly show the influence of the new added features on the final HEN. Hence, this work aims at showing that units' design can strongly affect the final HEN. Improvements on heat transfer area and total annual cost estimations, which influence the HEN structural evolution, are the main responsible for that. It is also shown the influence of some design bounds settings, which can indicate an unfeasible unit design and, therefore, the need for a new match search or the maintenance of a loop. An example reported in the literature is used to illustrate the discussion.

Comparison of LCA results of low temperature heat plant using electric heat pump, absorption heat pump and gas-fired boiler

International Nuclear Information System (INIS)

Nitkiewicz, Anna; Sekret, Robert

2014-01-01

Highlights: • Usage of geothermal heat pump can bring environmental benefits. • The lowest environmental impact for whole life cycle is obtained for absorption heat pump. • The value of heat pump COP has a significant influence on environmental impact. • In case of coal based power generation the damage to human health is significant. - Abstract: This study compares the life cycle impacts of three heating plant systems which differ in their source of energy and the type of system. The following heating systems are considered: electric water-water heat pump, absorption water-water heat pump and natural gas fired boiler. The heat source for heat pump systems is low temperature geothermal source with temperature below 20 °C and spontaneous outflow 24 m 3 /h. It is assumed that the heat pumps and boiler are working in monovalent system. The analysis was carried out for heat networks temperature characteristic at 50/40 °C which is changing with outdoor temperature during heating season. The environmental life cycle impact is evaluated within life cycle assessment methodological framework. The method used for life cycle assessment is eco-indicator ‘99. The functional unit is defined as heating plant system with given amount of heat to be delivered to meet local heat demand in assumed average season. The data describing heating plant system is derived from literature and energy analysis of these systems. The data describing the preceding life cycle phases: extraction of raw materials and fuels, production of heating devices and their transportation is taken from Ecoinvent 2.0 life cycle inventory database. The results were analyzed on three levels of indicators: single score indicator, damage category indicators and impact category indicator. The indicators were calculated for characterization, normalization and weighting phases as well. SimaPro 7.3.2 is the software used to model the systems’ life cycle. The study shows that heating plants using a low

Complementary-relationship-based 30 year normals (1981-2010) of monthly latent heat fluxes across the contiguous United States

Science.gov (United States)

Szilagyi, Jozsef

2015-11-01

Thirty year normal (1981-2010) monthly latent heat fluxes (ET) over the conterminous United States were estimated by a modified Advection-Aridity model from North American Regional Reanalysis (NARR) radiation and wind as well as Parameter-Elevation Regressions on Independent Slopes Model (PRISM) air and dew-point temperature data. Mean annual ET values were calibrated with PRISM precipitation (P) and validated against United States Geological Survey runoff (Q) data. At the six-digit Hydrologic Unit Code level (sample size of 334) the estimated 30 year normal runoff (P - ET) had a bias of 18 mm yr-1, a root-mean-square error of 96 mm yr-1, and a linear correlation coefficient value of 0.95, making the estimates on par with the latest Land Surface Model results but without the need for soil and vegetation information or any soil moisture budgeting.

Energy Analysis of Cascade Heating with High Back-Pressure Large-Scale Steam Turbine

Directory of Open Access Journals (Sweden)

Zhihua Ge

2018-01-01

Full Text Available To reduce the exergy loss that is caused by the high-grade extraction steam of traditional heating mode of combined heat and power (CHP generating unit, a high back-pressure cascade heating technology for two jointly constructed large-scale steam turbine power generating units is proposed. The Unit 1 makes full use of the exhaust steam heat from high back-pressure turbine, and the Unit 2 uses the original heating mode of extracting steam condensation, which significantly reduces the flow rate of high-grade extraction steam. The typical 2 × 350 MW supercritical CHP units in northern China were selected as object. The boundary conditions for heating were determined based on the actual climatic conditions and heating demands. A model to analyze the performance of the high back-pressure cascade heating supply units for off-design operating conditions was developed. The load distributions between high back-pressure exhaust steam direct supply and extraction steam heating supply were described under various conditions, based on which, the heating efficiency of the CHP units with the high back-pressure cascade heating system was analyzed. The design heating load and maximum heating supply load were determined as well. The results indicate that the average coal consumption rate during the heating season is 205.46 g/kWh for the design heating load after the retrofit, which is about 51.99 g/kWh lower than that of the traditional heating mode. The coal consumption rate of 199.07 g/kWh can be achieved for the maximum heating load. Significant energy saving and CO2 emission reduction are obtained.

Distribution characteristics of volatile methylsiloxanes in Tokyo Bay watershed in Japan: Analysis of surface waters by purge and trap method.

Science.gov (United States)

Horii, Yuichi; Minomo, Kotaro; Ohtsuka, Nobutoshi; Motegi, Mamoru; Nojiri, Kiyoshi; Kannan, Kurunthachalam

2017-05-15

Surface waters including river water and effluent from sewage treatment plants (STPs) were collected from Tokyo Bay watershed, Japan, and analyzed for seven cyclic and linear volatile methylsiloxanes (VMSs), i.e., D3, D4, D5, D6, L3, L4, and L5 by an optimized purge and trap extraction method. The total concentrations of seven VMSs (ΣVMS) in river water ranged from watershed was estimated at 2300kg. Our results indicate widespread distribution of VMSs in Tokyo Bay watershed and the influence of domestic wastewater discharges as a source of VMSs in the aquatic environment. Copyright © 2017 Elsevier B.V. All rights reserved.

ENERGY EFFICIENCY OF DIFFERENT WAYS OF CENTRAL HEATING

Directory of Open Access Journals (Sweden)

A. E. Piir

2015-01-01

Full Text Available  The article shows the calculation comparison of fuel for producing of heat-line water with a help of different technological installations, transforming (converting high-grade heat from burning process of fuel or in the process of non-reversible heat exchange with coolant (heating agent, or with a help of heat engines, which allow to decrease losses of working efficiency and thus to reduce the use of fuel. There were considered five types of plants beginning from the  simplest  one  up  to  the  most  complex  in  two  variants,  when  the  heat  exchangers and machines are perfect (ideal and when equipment has the known degree of efficiency (perfection:1 water-heat boiler station, working on organic fuel;2 electrical boiler station, obtaining energy on power transmission lines from condensing power station;3 line heater of TPP, obtaining steam from heating turbine;4 line heater CPP, powered by steam from pressure reducing unit;5 heat pump, producing energy on power supply lines from TPP.In this article were investigated three ideal reversible ways of transformation of   high- grade heat into low-grade heat with a help of decreasing and increasing and combined (suggested by the authors heat transformers and their thermodynamic equivalence was shown in this article. And there were suggested universal installation for electric energy generation, cold and heat of two grades for heat-water supply and the heating process on the base of gascompressors   gas turbines. These results are so important (actual for power engineers of the countries with  increasing consumption  of organic  fuel and  its enhancement in  value and realizing programs of energy saving .The analysis shows, that the quality of produced low-grade heat per unit of used high-grade heat for ideal plants (installations is: electrical boiler unit – 0.7;  water boiler unit – 1.0; for heat pump, heating turbine, combined heat transformers   – 4

Heat unit accumulation and inflorescence and fruit development in ‘Ubá’ mango trees grown in Visconde do Rio Branco-MG

Directory of Open Access Journals (Sweden)

Lorena Moreira Carvalho Lemos

2018-04-01

Full Text Available Abstract There are little information in the scientific literature on flowering and fruiting of ‘Ubá’ mango trees. These information enables to know the proportion of hermaphrodite flowers in inflorescence, fruit set percentage and developmental stages of the fruit. In this study evaluations on inflorescence and fruit development of the ‘Ubá’ mango tree (Mangifera indica L. were carried out, as well as the determination of the required number of heat units for full fruit development. Thirty branches whose terminal buds were swollen were selected from five mango trees. With the aid of a camera and a caliper, the panicle and fruit development were evaluated weekly until full fruit development. A digital thermometer was used to record ambient temperatures during fruit development in order to estimate the number of heat units required for complete development of the fruits. Male and hermaphrodite flowers of the panicles were also identified and counted. The developmental cycle of ‘Ubá’ mango from the beginning of apical bud swelling to commercial harvest of the fruit lasted 168 days in 2011 and 154 days in 2012. The number of hermaphrodite flowers and the percentage of fruit set in the inflorescence in 2011 were 32.3 and 0.066%, respectively; and 122.1 and 0.099% in 2012, respectively. There was accumulation of 3,173 heat units from flower bud swelling to full development of the ‘Ubá’ mangoes.

Solvarmeanlæg med naturgaskedel/solbeholder-unit og oliefyr/solbeholder-unit. Ydelser og erfaringer fra praksis

DEFF Research Database (Denmark)

Furbo, Simon; Vejen, Niels Kristian; Frederiksen, Karsten Vinkler

1999-01-01

of the natural gas burner/oil fired boiler and of the circulation pump of the loop so that the heat left in the loop outside the solar tank after every period of operation is reduced to a minimum.Measurements have been carried out in practice for three solar heating systems based on the new units. Additional......Manufacturers have during the last few years started marketing of newly developed natural gas burner/solar tank- and oil fired boiler/solar tank-units.These units make it possible to reduce the costs of solar heating systems, because an electric heating element is not built into the solar tank...... the pipes connecting the natural gas burner/oil fired boiler and the top spiral of the solar tank and from the natural gas burner/oil fired boiler. Furthermore, the unit with a fixed design of the natural gas burner/oil fired boiler - top spiral loop open up the possibility of an optimum control...

Automatic analyzer of the coefficient of excess air and products of chemical under firing of heat and power engineering installations

Energy Technology Data Exchange (ETDEWEB)

Babushkin, V V; Furman, N I; Shcherban, A N; Tarasevich, V N

1981-01-01

A sensor of the combustion quality of gas and oil fuel in boiler furnaces which is intended to be used for automatic measurement of an excess amount of 0/sub 2/ and fuel components, and also of associated elements present in a stoichiometric ratio of 0/sub 2/ and fuel components in the waste gasses is proposed. The AST-2 fuel combustion analyzer is developed based on this sensor. It consists of a sample preparation unit of the controlled environment and a power source. The sample preparation unit is determined by the structural engineering specifics of the power unit in which the fuel combustion controlled process is carried out. The sample preparation unit, which is made for 11 open-hearth ovens of ''Azovstal''' factory, is intended for drying and purging of mechanical and aggressive impurities the samples of the gas to be analyzed and additional reagents, and also for controlling and monitoring constancy and amount of pressure, temperature, and humidity.

Large-Scale Liquid Hydrogen Testing of Variable Density Multilayer Insulation with a Foam Substrate

Science.gov (United States)

Martin, J. J.; Hastings, L.

2001-01-01

The multipurpose hydrogen test bed (MHTB), with an 18-cu m liquid hydrogen tank, was used to evaluate a combination foam/multilayer combination insulation (MLI) concept. The foam element (Isofoam SS-1171) insulates during ground hold/ascent flight, and allowed a dry nitrogen purge as opposed to the more complex/heavy helium purge subsystem normally required. The 45-layer MLI was designed for an on-orbit storage period of 45 days. Unique WI features include a variable layer density, larger but fewer double-aluminized Mylar perforations for ascent to orbit venting, and a commercially established roll-wrap installation process that reduced assembly man-hours and resulted in a roust, virtually seamless MLI. Insulation performance was measured during three test series. The spray-on foam insulation (SOFI) successfully prevented purge gas liquefaction within the MLI and resulted in the expected ground hold heat leak of 63 W/sq m. The orbit hold tests resulted in heat leaks of 0.085 and 0.22 W/sq m with warm boundary temperatures of 164 and 305 K, respectively. Compared to the best previously measured performance with a traditional MLI system, a 41-percent heat leak reduction with 25 fewer MLI layers was achieved. The MHTB MLI heat leak is half that calculated for a constant layer density MLI.

Experimental comparison between R409A and R437A performance in a heat pump unit

Directory of Open Access Journals (Sweden)

Duarte M. V.

2017-04-01

Full Text Available This paper reports an experimental comparison between the use of the refrigerants R409A and R437A in a heat pump unit designed and developed to work with R12. Although the use of both refrigerants in new equipments were abolished in EU and US according the new F-Gas Regulation of EU and SNAP, they still being used as options for R12 in old equipments, especially in developing countries. Both refrigerants were studied for the same test conditions, according to two groups of tests: group A (variation of the heat source temperature and group B (variation of refrigerant flow rate. The results obtained showed that the R437A presents a higher discharge pressure and a lower discharge temperature. The heating and cooling capacities of both refrigerants were similar, as well as the exergetic efficiency. For the group A of tests the COP of both refrigerants was similar and for the group B of tests the R409A presented an average COP 15% higher. According to the results obtained it is recommended the use of R409A in old equipments (as transition refrigerant until the acquisition of equipments operating with refrigerants with low-GWP becomes technically and economic feasible.

Flexibility of a combined heat and power system with thermal energy storage for district heating

International Nuclear Information System (INIS)

Nuytten, Thomas; Claessens, Bert; Paredis, Kristof; Van Bael, Johan; Six, Daan

2013-01-01

Highlights: ► A generic model for flexibility assessment of thermal systems is proposed. ► The model is applied to a combined heat and power system with thermal energy storage. ► A centrally located storage offers more flexibility compared to individual units. ► Increasing the flexibility requires both a more powerful CHP and a larger buffer. - Abstract: The trend towards an increased importance of distributed (renewable) energy resources characterized by intermittent operation redefines the energy landscape. The stochastic nature of the energy systems on the supply side requires increased flexibility at the demand side. We present a model that determines the theoretical maximum of flexibility of a combined heat and power system coupled to a thermal energy storage solution that can be either centralized or decentralized. Conventional central heating, to meet the heat demand at peak moments, is also available. The implications of both storage concepts are evaluated in a reference district. The amount of flexibility created in the district heating system is determined by the approach of the system through delayed or forced operation mode. It is found that the distinction between the implementation of the thermal energy storage as a central unit or as a collection of local units, has a dramatic effect on the amount of available flexibility

CO{sub 2} reduction: potential of heat pumps when used together with combined heat and power units; Potentiel energetique des pompes a chaleur combinees au couplage chaleur-force. Pour une reduction maximale des emissions de CO{sub 2} et pour une production de courant fossile avec reduction des emissions de CO{sub 2} en Suisse - Rapport final

Energy Technology Data Exchange (ETDEWEB)

Rognon, F.

2005-07-01

This final report for the Swiss Federal Office of Energy (SFOE) presents the results of a project that examined the potential of using heat pumps in combination with Combined Heat and Power (CHP) units as a replacement for fossil-fuel fired heating units in Switzerland. The electrical power produced by the CHP units can be used to provide power for the drives of heat pump systems. The author states that the fossil fuel consumption and the resulting emissions of carbon dioxide can be halved using this combination. Also, even more efficient systems using power produced in larger combined-cycle power generation are discussed. Further examples of how fossil-fired power generation in combination with heat pumps can not only replace fossil-fuelled heating systems but also provide additional electricity too are given. This overview includes figures on the potential of such combined systems.

Vapor Compression and Thermoelectric Heat Pump Heat Exchangers for a Condensate Distillation System: Design and Experiment

Science.gov (United States)

Erickson, Lisa R.; Ungar, Eugene K.

2013-01-01

Maximizing the reuse of wastewater while minimizing the use of consumables is critical in long duration space exploration. One of the more promising methods of reclaiming urine is the distillation/condensation process used in the cascade distillation system (CDS). This system accepts a mixture of urine and toxic stabilizing agents, heats it to vaporize the water and condenses and cools the resulting water vapor. The CDS wastewater flow requires heating and its condensate flow requires cooling. Performing the heating and cooling processes separately requires two separate units, each of which would require large amounts of electrical power. By heating the wastewater and cooling the condensate in a single heat pump unit, mass, volume, and power efficiencies can be obtained. The present work describes and compares two competing heat pump methodologies that meet the needs of the CDS: 1) a series of mini compressor vapor compression cycles and 2) a thermoelectric heat exchanger. In the paper, the system level requirements are outlined, the designs of the two heat pumps are described in detail, and the results of heat pump performance tests are provided. A summary is provided of the heat pump mass, volume and power trades and a selection recommendation is made.

Large-scale heat pumps in sustainable energy systems: System and project perspectives

Directory of Open Access Journals (Sweden)

Blarke Morten B.

2007-01-01

Full Text Available This paper shows that in support of its ability to improve the overall economic cost-effectiveness and flexibility of the Danish energy system, the financially feasible integration of large-scale heat pumps (HP with existing combined heat and power (CHP plants, is critically sensitive to the operational mode of the HP vis-à-vis the operational coefficient of performance, mainly given by the temperature level of the heat source. When using ground source for low-temperature heat source, heat production costs increases by about 10%, while partial use of condensed flue gasses for low-temperature heat source results in an 8% cost reduction. Furthermore, the analysis shows that when a large-scale HP is integrated with an existing CHP plant, the projected spot market situation in The Nordic Power Exchange (Nord Pool towards 2025, which reflects a growing share of wind power and heat-supply constrained power generation electricity, further reduces the operational hours of the CHP unit over time, while increasing the operational hours of the HP unit. In result, an HP unit at half the heat production capacity as the CHP unit in combination with a heat-only boiler represents as a possibly financially feasible alternative to CHP operation, rather than a supplement to CHP unit operation. While such revised operational strategy would have impacts on policies to promote co-generation, these results indicate that the integration of large-scale HP may jeopardize efforts to promote co-generation. Policy instruments should be designed to promote the integration of HP with lower than half of the heating capacity of the CHP unit. Also it is found, that CHP-HP plant designs should allow for the utilization of heat recovered from the CHP unit’s flue gasses for both concurrent (CHP unit and HP unit and independent operation (HP unit only. For independent operation, the recovered heat is required to be stored. .

Climate Change and Health Risks from Extreme Heat and Air Pollution in the Eastern United States

Science.gov (United States)

Limaye, V.; Vargo, J.; Harkey, M.; Holloway, T.; Meier, P.; Patz, J.

2013-12-01

Climate change is expected to exacerbate health risks from exposure to extreme heat and air pollution through both direct and indirect mechanisms. Directly, warmer ambient temperatures promote biogenic emissions of ozone precursors and favor the formation of ground-level ozone, while an anticipated increase in the frequency of stagnant air masses will allow fine particulates to accumulate. Indirectly, warmer summertime temperatures stimulate energy demand and exacerbate polluting emissions from the electricity sector. Thus, while technological adaptations such as air conditioning can reduce risks from exposures to extreme heat, they can trigger downstream damage to air quality and public health. Through an interdisciplinary modeling effort, we quantify the impacts of climate change on ambient temperatures, summer energy demand, air quality, and public health. The first phase of this work explores how climate change will directly impact the burden of heat-related mortality. Climatic patterns, demographic trends, and epidemiologic risk models suggest that populations in the eastern United States are likely to experience an increasing heat stress mortality burden in response to rising summertime air temperatures. We use North American Regional Climate Change Assessment Program modeling data to estimate mid-century 2-meter air temperatures and humidity across the eastern US from June-August, and quantify how long-term changes in actual and apparent temperatures from present-day will affect the annual burden of heat-related mortality across this region. With the US Environmental Protection Agency's Environmental Benefits Mapping and Analysis Program, we estimate health risks using concentration-response functions, which relate temperature increases to changes in annual mortality rates. We compare mid-century summertime temperature data, downscaled using the Weather Research and Forecasting model, to 2007 baseline temperatures at a 12 km resolution in order to estimate

Optimum Design of Heat Exchangers Networks Part-2: case study: Atmospheric Crude Distillation Unit

International Nuclear Information System (INIS)

Gabr, E.M.A.; EI-Temtamy, S.A.; Deriasl, S.F.; Moustafa, H.A.

2004-01-01

In this paper the computerized framework introduced in part-I for Heat Exchanger Network Synthesis (HENS) with optimality conditions of achieving the least operating and capital cost has been applied on an industrial atmospheric distillation unit existing in one of the Egyptian refineries . The application includes two types of designing: grass-root and revamp of the existing design. For the final grass-root design, the saving of utilities is 50% of the actual consumption while the net annual saving reaches 2,193,690 S/year .For revamping of existing design the % saving of hot and cold utilities are 38.1% and 43.2% respectively and the annual saving of 1,723,104 $/year is achieved

Studies on split heat pipe type adsorption ice-making test unit for fishing boats: Choice of heat pipe medium and experiments under unsteady heating sources

International Nuclear Information System (INIS)

Wang, L.W.; Wang, R.Z.; Lu, Z.S.; Chen, C.J.

2006-01-01

The split heat pipe type compound adsorption ice maker for fishing boats not only has the advantage of large volume cooling density but also has the advantage of less power consumption and high heat transfer performance. The available heat pipe media for the split heat pipe type compound adsorption ice maker, which are methanol, acetone and water are studied and compared in this paper, and the heat pipe medium of water shows the better performance for the reason of its stable heating and cooling process and high heat transfer performance. Considering the waste heat recovered from the diesel engine on fishing boats varies when the velocity of the fishing boat changes, the refrigeration performances at the condition of different values of heating power are studied while water is used as the heat pipe medium. Results show that the cooling power, as while as COP and SCP decrease when the heating power decreases. The highest COP and SCP are 0.41 and 731 W/kg, respectively, at the highest heating power of 4.2 kW, and the values decrease by 22% and 33%, respectively, when the heating power decreases by 15%. The values decrease by 32% and 51%, respectively, when the heating power decreases by 30%. The performance of the adsorption ice maker for the fishing boat with the 6160A type diesel engine is estimated, and the results show that the cooling power and ice productivity are as high as 5.44 kW and 1032 kg ice per day, respectively, even if the recovered waste heat decreases by 30% compared with the normal value. It can satisfy the ice requirements of such a fishing boat

An experimental study on defrosting heat supplies and energy consumptions during a reverse cycle defrost operation for an air source heat pump

International Nuclear Information System (INIS)

Dong Jiankai; Deng Shiming; Jiang Yiqiang; Xia Liang; Yao Yang

2012-01-01

For a space heating air source heat pump (ASHP) unit, when its outdoor coil surface temperature is below both the air dew point temperature and the freezing point of water, frost will form on its outdoor coil surface. Frosting affects its operational performance and energy efficiency. Therefore, periodic defrosting is necessary. Currently, the most widely used standard defrosting method for ASHP units is reverse cycle defrost. The energy that should have been used for space heating is used to melt frost, vaporize the melted frost off outdoor coil surface and heat ambient air during defrosting. It is therefore necessary to study the sources of heat supplies and the end-uses of the heat supplied during a reverse cycle defrost operation. In this paper, firstly, an experimental setup is described and experimental procedures are detailed. This is followed by reporting the experimental results and the evaluation of defrosting efficiency for the experimental ASHP unit. Finally, an evaluation of defrosting heat supplies and energy consumptions during a revere cycle defrost operation for the experimental ASHP unit is presented. The experimental and evaluation results indicated that the heat supply from indoor air contributed to 71.8% of the total heat supplied for defrosting and 59.4% of the supplied energy was used for melting frost. The maximum defrosting efficiency could be up to 60.1%. - Highlights: ► Heat supply and consumption during reverse cycle defrost was experimentally studied. ► Indoor air contributed to >70% of total heat supply when indoor fan was turned on. ► ∼60% of the supplied energy was used for melting frost. ► Alternate heat supply other than indoor air should be explored.

Design of SES-10 nuclear reactor for district heating

International Nuclear Information System (INIS)

Cuttler, J.M.

1991-03-01

The SES-10 units are unpressurized, pool-type nuclear reactors of 10MW rating, designed for supplying energy to hot water district heating systems, economically and without pollution. Water for heat distribution is brought to a maximum temperature of 85 degrees C. Conventional heating units supplement the output from SES-10 units for peak load and during maintenance. The SES-10 is housed in a low-cost building, with a double-walled pool in the ground. A naturally circulating primary system and a pumped secondary system transport heat from the reactor to the distribution system. The unit is fully automated and easy to maintain. Because of the many active and passive safety features, it is feasible to license the SES-10 for operation in a city and easy to explain it to the public for their acceptance. The core lasts approximately 43 months at a capacity factor of 70%, and the cost of heat is expected to be 2 to 2.5 cents/kWh

Heat losses and thermal performance of commercial combined solar and pellet heating systems

OpenAIRE

Fiedler, Frank; Persson, Tomas; Bales, Chris; Nordlander, Svante

2004-01-01

Various pellet heating systems are marketed in Sweden, some of them in combination with a solar heating system. Several types of pellet heating units are available and can be used for a combined system. This article compares four typical combined solar and pellet heating systems: System 1 and 2 two with a pellet stove, system 3 with a store integrated pellet burner and system 4 with a pellet boiler. The lower efficiency of pellet heaters compared to oil or gas heaters increases the primary en...

Research of waste heat energy efficiency for absorption heat pump recycling thermal power plant circulating water

Science.gov (United States)

Zhang, Li; Zhang, Yu; Zhou, Liansheng; E, Zhijun; Wang, Kun; Wang, Ziyue; Li, Guohao; Qu, Bin

2018-02-01

The waste heat energy efficiency for absorption heat pump recycling thermal power plant circulating water has been analyzed. After the operation of heat pump, the influences on power generation and heat generation of unit were taken into account. In the light of the characteristics of heat pump in different operation stages, the energy efficiency of heat pump was evaluated comprehensively on both sides of benefits belonging to electricity and benefits belonging to heat, which adopted the method of contrast test. Thus, the reference of energy efficiency for same type projects was provided.

The critical role of extreme heat for maize production in the United States

Science.gov (United States)

Lobell, David B.; Hammer, Graeme L.; McLean, Greg; Messina, Carlos; Roberts, Michael J.; Schlenker, Wolfram

2013-05-01

Statistical studies of rainfed maize yields in the United States and elsewhere have indicated two clear features: a strong negative yield response to accumulation of temperatures above 30°C (or extreme degree days (EDD)), and a relatively weak response to seasonal rainfall. Here we show that the process-based Agricultural Production Systems Simulator (APSIM) is able to reproduce both of these relationships in the Midwestern United States and provide insight into underlying mechanisms. The predominant effects of EDD in APSIM are associated with increased vapour pressure deficit, which contributes to water stress in two ways: by increasing demand for soil water to sustain a given rate of carbon assimilation, and by reducing future supply of soil water by raising transpiration rates. APSIM computes daily water stress as the ratio of water supply to demand, and during the critical month of July this ratio is three times more responsive to 2°C warming than to a 20% precipitation reduction. The results suggest a relatively minor role for direct heat stress on reproductive organs at present temperatures in this region. Effects of elevated CO2 on transpiration efficiency should reduce yield sensitivity to EDD in the coming decades, but at most by 25%.

A Modified Entropy Generation Number for Heat Exchangers

Institute of Scientific and Technical Information of China (English)

无

1996-01-01

This paper demonstrates the difference between the entropy generation number method proposed by Bejian and the method of entropy generation per unit amount of heat transferred in analyzing the ther-modynamic performance of heat exchangers,points out the reason for leading to the above difference.A modified entropy generation number for evaluating the irreversibility of heat exchangers is proposed which is in consistent with the entropy generation per unit amount of heat transferred in entropy generation analysis.The entropy generated by friction is also investigated.Results show that when the entropy generated by friction in heat exchangers in taken into account,there is a minimum total entropy generation number while the NTU and the ratio of heat capacity rates vary.The existence of this minimum is the prerequisite of heat exchanger optimization.

A nuclear reactor for district heating

International Nuclear Information System (INIS)

Bancroft, A.R.; Fenton, N.

1989-07-01

Global energy requirements are expected to double over the next 40 years. In the northern hemisphere, many countries consume in excess of 25 percent of their primary energy supply for building heating. Satisfying this need, within the constraints now being acknowledged for sustainable global development, provides an important opportunity for district heating. Fuel-use flexibility, energy and resource conservation, and reduced atmospheric pollution from acid gases and greenhouse gases, are important features offered by district heating systems. Among the major fuel options, only hydro-electricity and nuclear heat completely avoid emissions of combustion gases. To fill the need for an economical nuclear heat source, Atomic Energy of Canada Limited has designed a 10 MW plant that is suitable as a heat source within a network or as the main supply to large individual users. Producing hot water at temperatures below 100 degrees C, it incorporates a small pool-type reactor based on AECL's successful SLOWPOKE Research Reactor. A 2 MW prototype for the commercial unit is now being tested at the Whiteshell Nuclear Research Establishment in Manitoba. With capital costs of $7 million (Canadian), unit energy costs are projected to be $0.02/kWh for a 10 MW unit operating in a heating grid over a 30-year period. By keeping the reactor power low and the water temperature below 100 degrees C, much of the complexity of the large nuclear power plants can be avoided, thus allowing these small, safe nuclear heating systems to be economically viable

Analysis of the heat transfer in double and triple concentric tube heat exchangers

Science.gov (United States)

Rădulescu, S.; Negoiţă, L. I.; Onuţu, I.

2016-08-01

The tubular heat exchangers (shell and tube heat exchangers and concentric tube heat exchangers) represent an important category of equipment in the petroleum refineries and are used for heating, pre-heating, cooling, condensation and evaporation purposes. The paper presents results of analysis of the heat transfer to cool a petroleum product in two types of concentric tube heat exchangers: double and triple concentric tube heat exchangers. The cooling agent is water. The triple concentric tube heat exchanger is a modified constructive version of double concentric tube heat exchanger by adding an intermediate tube. This intermediate tube improves the heat transfer by increasing the heat area per unit length. The analysis of the heat transfer is made using experimental data obtained during the tests in a double and triple concentric tube heat exchanger. The flow rates of fluids, inlet and outlet temperatures of water and petroleum product are used in determining the performance of both heat exchangers. Principally, for both apparatus are calculated the overall heat transfer coefficients and the heat exchange surfaces. The presented results shows that triple concentric tube heat exchangers provide better heat transfer efficiencies compared to the double concentric tube heat exchangers.

‘That’s when we started using the living room’ : lessons from a local history of domestic heating in the United Kingdom

NARCIS (Netherlands)

Kuijer, L.; Watson, M.

Indoor climate control forms a major share of residential energy demand. Policy measures to curb this demand tend to focus on energy-efficient technologies. However, while the energy efficiency of domestic heat provision in the United Kingdom (UK) has increased considerably over the past century,

A review of magnetic heat pump technology

International Nuclear Information System (INIS)

Barclay, J.A.

1990-01-01

The area of technology classified as heat pumps generally refers to refrigerators, heat pumps and heat engines. This review is restricted to the literature on magnetic refrigerators and magnetic heat pumps which are referred to interchangeably. Significant progress has been made on the development of engineering prototypes of cryogenic, nonregenerative magnetic refrigerators utilizing conductive heat transfer in the 0.1 K to 20 K temperature range. Advances have also been made in analysis of regenerative magnetic refrigerators and heat pumps utilizing the active magnetic regeneration (AMR) concept. Units based on AMR are being modeled, designed and/or built to operate in various temperature ranges including 1.8-4.5 K, 4-15 K, 15-85 K, and 270-320 K. The near room temperature units have been scaled to 50 kW as both refrigerators and heat pumps. The progress of magnetic refrigeration over the last three years is summarized and discussed

Reactor waste heat utilization and district heating reactors. Nuclear district heating in Sweden - Regional reject heat utilization schemes and small heat-only reactors

International Nuclear Information System (INIS)

Hannerz, K.; Larsson, Y.; Margen, P.

1977-01-01

A brief review is given of the current status of district heating in Sweden. In future, district heating schemes will become increasingly interesting as a means of utilizing heat from nuclear reactors. Present recommendations in Sweden are that large reactors should not be located closer than about 20 km from large population centres. Reject heat from such reactors is cheap at source. To minimize the cost of long distance hot water transmission large heat rates must be transmitted. Only areas with large populations can meet this requirement. The three areas of main interest are Malmoe/Lund/Helsingborg housing close to 0.5 million; Greater Stockholm housing 1 to 1.5 million and Greater Gothenburg housing about 0.5 million people. There is an active proposal that the Malmoe/Lund/Helsingborg region would be served by a third nuclear unit at Barsebaeck, located about 20 km from Malmoe/Lund and supplying 950 MW of base load heat. Preliminary proposals for Stockholm involve a 2000 MW heat supply; proposals for Gothenburg are more tentative. The paper describes progress on these proposals and their technology. It also outlines technology under development to increase the economic range of large scale heat transport and to make distribution economic even for low heat-density family housing estates. Regions apart from the few major urban areas mentioned above require the adoption of a different approach. To this end the development of a small, simple low-temperature reactor for heat-only production suitable for urban location has been started in Sweden in close contact with Finland. Some results of the work in progress are presented, with emphasis on the safety requirements. An outline is given in the paper as to how problems of regional heat planning and institutional and legislative issues are being approached

Miniature Heat Pipes

Science.gov (United States)

1997-01-01

Small Business Innovation Research contracts from Goddard Space Flight Center to Thermacore Inc. have fostered the company work on devices tagged "heat pipes" for space application. To control the extreme temperature ranges in space, heat pipes are important to spacecraft. The problem was to maintain an 8-watt central processing unit (CPU) at less than 90 C in a notebook computer using no power, with very little space available and without using forced convection. Thermacore's answer was in the design of a powder metal wick that transfers CPU heat from a tightly confined spot to an area near available air flow. The heat pipe technology permits a notebook computer to be operated in any position without loss of performance. Miniature heat pipe technology has successfully been applied, such as in Pentium Processor notebook computers. The company expects its heat pipes to accommodate desktop computers as well. Cellular phones, camcorders, and other hand-held electronics are forsible applications for heat pipes.

Thermoacoustic refrigerators and engines comprising cascading stirling thermodynamic units

Science.gov (United States)

Backhaus, Scott; Swift, Greg

2013-06-25

The present invention includes a thermoacoustic assembly and method for improved efficiency. The assembly has a first stage Stirling thermal unit comprising a main ambient heat exchanger, a regenerator and at least one additional heat exchanger. The first stage Stirling thermal unit is serially coupled to a first end of a quarter wavelength long coupling tube. A second stage Stirling thermal unit comprising a main ambient heat exchanger, a regenerator, and at least one additional heat exchanger, is serially coupled to a second end of the quarter wavelength long coupling tube.

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

Energy Technology Data Exchange (ETDEWEB)

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

1989-08-01

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

Design of SES-10 nuclear reactor for district heating

International Nuclear Information System (INIS)

Cuttler, J.M.

1991-01-01

The SES-10 units are unpressurized, pool-type nuclear reactors of 10 MW rating, designed for supplying energy to hot water district heating systems, economically and without pollution. Water for heat distribution is brought to a maximum temperature of 85 o C. Conventional heating units supplement the output from SES-10 units for peak load and during maintenance. The SES-10 is housed in a low-cost building, with a double-walled pool in the ground. A naturally circulating primary system and a pumped secondary system transport heat from the reactor to the distribution system. The unit is fully automated and easy to maintain. Because of the many active and passive safety features, it is feasible to license the SES-10 for operation in a city and easy to explain it to the public for their acceptance. The core lasts approximately 43 months at a capacity factor of 70%, and the cost of heat is expected to be 2 to 2.5 cents/kWh. (author) 8 figs

Conceptual design of a FGM thermoelectric energy conversion system for high temperature heat source. 1. Design of thermoelectric energy conversion unit

International Nuclear Information System (INIS)

Kambe, Mitsuru; Teraki, Junichi; Hirano, Toru.

1996-01-01

Thermoelectric (TE) power conversion system has been focused as a candidate of direct energy conversion systems for high temperature heat source to meet the various power requirements in next century. A concept of energy conversion unit by using TE cell elements combined with FGM compliant pads has been presented to achieve high thermal energy density as well as high energy conversion efficiency. An energy conversion unit consists of 8 couples of P-N cell elements sandwiched between two FGM compliant pads. Performance analysis revealed that the power generated by this unit was 11 watts which is nearly ten times as much as conventional unit of the same size. Energy conversion efficiency of 12% was expected based on the assumption of ZT = 1. All the member of compliant pads as well as TE cells could be bonded together to avoid thermal resistance. (author)

Heat exchanger with dirt separator for the use of the heat energy of waste water

Energy Technology Data Exchange (ETDEWEB)

1975-11-13

Well-known heat exchanger systems consist of separate heat exchangers and dirt separators. In the case here in question both devices form a unit. A finned tube heat exchanger is positioned in the center of the dirt separator and is given extra protection through deflection sheets. A safety overflow is supplied so that no residue can appear in the waste water line when decanting.

Cernavoda NPP Unit 1: Ensuring heat sink at very low Danube river levels

International Nuclear Information System (INIS)

Urjan, D.

2005-01-01

Full text: On August 24, 2003 the summer heat wave has caused the Danube River to drop to its lowest level in more than a century, forcing a government commission of experts and a team of technical specialists from Cernavoda NPP to close Romania's unique nuclear reactor in operation at Cernavoda. The paper presents some of the required actions needed for plant shutdown and ensuring adequate fuel cooling at very low suction bay levels, due to the Danube River level drop (Danube waters cools the reactor). The water level in the Danube River at Cernavoda village, where the reactor is located, fell to a depth of less than three meters (10 feet) on Saturday, down from its usual level of almost seven meters (23 feet). Consequently, the Unit 1 nuclear power plant was shut down Sunday due to this record drought, which left insufficient water to cool down the reactor. Operating Instruction procedures were elaborated in order to provide a logical sequence of actions when the bay level decreases under 2.25 m, or the estimated level after 3 days will be lower than 1.8 m. When Raw Service Water (RSW) is lost, Recirculated Cooling Water (RCW) will remain in service only for Moderator, ESC, HT Pumps, HT Purification, D/C Cooler, LAC's, and D 2 O Feed Pump. Alternate water sources, like potable water and water from the fire protection system were taken in consideration in order to ensure heat sink to the RCW loads. At the same time, in case of total loss of Class III and Class IV Power, and Stand-By Diesel Generators unavailable because of the loss of heat sink provided by the RSW, Emergency Power System (EPS) was configured to supply directly the Class III Power 6 kV bus (BUG bus). Economical Impact According to a report, closing the nuclear plant costs Romania $500,000 a day. The total cost includes also losses due to a 40 percent reduction in hydroelectric power generation due to reduced river flow. The country had to cease power exports until the reactor comes back on line

Permeation rates for RTF metal hydride vessels

International Nuclear Information System (INIS)

Klein, J.E.

1992-01-01

Contamination rates have been estimated for the RTF nitrogen heating and cooling system (NH and CS) due to tritium permeation through the walls of metal hydride vessels. Tritium contamination of the NH and CS will be seen shortly after start-up of the RTF with the majority of it coming from the TCAP units. Contamination rates of the NH and CS are estimated to exceed 400 Ci/year after three years of operation and will elevate tritium concentrations in the NH and CS above 6 x 10 -3 μCi/cc. To reduce tritium activity in the NH and CS, a stripper or ''getter'' bed may need to be installed in the NH and CS. Increasing the purge rate of nitrogen from the NH and CS is shown to be an impractical method for reducing tritium activity due to the high purge rates required. Stripping of the NH and CS nitrogen in the glove box stripper system will give a temporary lowering of tritium activity in the NH and CS, but tritium activity will return to its previous level in approximately two weeks

Heat extraction from turbines of Czechoslovak nuclear power plants for district heating

International Nuclear Information System (INIS)

Drahy, J.

1985-01-01

Two design are described of SKODA extraction turbines for Czechoslovak nuclear power plants with WWER-440 and WWER-1000 reactors. 220 MW steam turbines were originally designed as pure condensation turbines with uncontrolled steam extraction. Optimal ways are now being sought for their use for heating hot water for district heating. For district heating of the town of Trnava, the nuclear power plant at Jaslovske Bohunice will provide a two-step heating of water from 70 to 120 degC with a heat supply of 60 MW th from one turbine unit. The ratio of obtained heat power to lost electric power is 5.08. Investigations showed the possibility of extracting 85 MW th of heat from uncontrolled steam extraction, this at three-step water heating from 60 to 145 degC, the ratio of gained and lost power being 7.14. Information is presented on the SKODA 220 MW turbine with steam extraction for heat supply purposes and on the 1000 MW turbine with 893 MW th heat extraction. The specifications of both types are given. (Pu)

Design of the breeder units in the new HCPB modular blanket concept and material requirements

International Nuclear Information System (INIS)

Boccaccini, L.V.; Fischer, U.; Hermsmeyer, S.; Reimann, J.; Xu, Z.; Koehly, C.

2004-01-01

A major revision of the DEMO HCPB blanket concept took place in 2002-2003 as consequence of the results of the EU Power Plant Conceptual Study. In particular, it was decided to give up the previous maintenance schema based on segments in favour of a large module concept extrapolated from ITER. The adaptation of the HCPB concept to these modules (typical dimension at the FW of 2.0 x 2.0 m) required a complete revision of the box. The coolant flow scheme is based on a radial He flow (at 8 MPa) in order to have the entire manifold system in the rear part of the box. Furthermore, the requirement of a box capable of withstanding the coolant pressure of 8 MPa in case of an in-box LOCA led to a design of modules with an internal stiffening grid in toroidal and poloidal direction This grid results in cells open in the rear radial direction with toroidal-poloidal dimensions of about 20 cm x 20 cm that accommodate the breeder units. These units contain the ceramic breeder (CB) and the Beryllium in form of pebble beds and have to assure the main functions of the blanket, namely, a tritium breeding ratio significantly above one, heat removal with a temperature control in the beds and in the structure, mechanical stability of the beds and extraction of the produced tritium. Due to the relatively high quantity of steel necessary to assure the mechanical stability of the box, a strong requirement for the design of these units is to minimise the amount of steel to improve the neutronic performance. A satisfactory design has been achieved with a radial-toroidal bed configuration similar to the old DEMO design reaching the Tritium self-sufficiency with a radial depth of 47 cm, using monosized Beryllium and CB beds and, using Li 4 SiO 4 , a 6 Li enrichment of about 40%. This design allows a satisfactory control of the maximum acceptable temperatures in the CB and Be beds and the steel structure. The design of the breeder units has not been yet analysed thermo-mechanically in detail

Low Temperature Heating and High Temperature Cooling in Buildings

DEFF Research Database (Denmark)

Kazanci, Ongun Berk

A heating and cooling system could be divided into three parts: terminal units (emission system), distribution system, and heating and cooling plant (generation system). The choice of terminal unit directly affects the energy performance, and the indoor environment in that space. Therefore, a hol...

Fuel fired heat sources

Energy Technology Data Exchange (ETDEWEB)

Ortlinghaus, U

1977-09-08

Fuel fired heat sources with a valve-controlled ignition and main burner, whose flame is monitored and whose control valve is closed or opened by a controller according to the control deviation between actual and reference heat source temperature, previously suffered the disadvantage of high consumption of ignition gas. According to the invention this disadvantage is avoided by closing the ignition valve from the controller via a delay unit and having the delay time of the delay unit controlled either by the temperature measured by the sensor or increasing it with increasing deviation of the actual value of pre-temperature from the reference value of the pre-temperature.

Market Potential for Residential Biomass Heating Equipment: Stochastic and Econometric Assessments

OpenAIRE

Adee Athiyaman

2015-01-01

This paper provides estimates of market potential for biomass-residential-heating equipment in the US: that is, the greatest amount of biomass-residential-heating equipment that can be sold by the industry. The author's analysis is limited to biomass equipment used most to heat the housing unit. Assuming that households equipped with 10+ year old primary heating devices will replace rather than repair the devices he predicts that approximately 1.4 million units of residential home heating equ...

Performance Evaluation of Air-Based Heat Rejection Systems

Directory of Open Access Journals (Sweden)

Hannes Fugmann

2015-01-01

Full Text Available On the basis of the Number of Transfer Units (NTU method a functional relation between electric power for fans/pumps and effectiveness in dry coolers and wet cooling towers is developed. Based on this relation, a graphical presentation method of monitoring and simulation data of heat rejection units is introduced. The functional relation allows evaluating the thermodynamic performance of differently sized heat rejection units and comparing performance among them. The method is used to evaluate monitoring data of dry coolers of different solar cooling field projects. The novelty of this approach is that performance rating is not limited by a design point or standardized operating conditions of the heat exchanger, but is realizable under flexible conditions.

Regenerator heat exchanger – calculation of heat recovery efficiency and pressure loss

DEFF Research Database (Denmark)

Pomianowski, Michal Zbigniew; Heiselberg, Per Kvols

Performance of heat exchangers is determined based on two main parameters: efficiency to exchange / recover heat and pressure loss due to friction between fluid and exchanger surfaces. These two parameters are contradicting each other which mean that the higher is efficiency the higher becomes...... pressure loss. The aim of the optimized design of heat exchanger is to reach the highest or the required heat efficiency and at the same time to keep pressure losses as low as possible keeping total exchanger size within acceptable size. In this report is presented analytical calculation method...... to calculate efficiency and pressure loss in the regenerator heat exchanger with a fixed matrix that will be used in the decentralized ventilation unit combined in the roof window. Moreover, this study presents sensitivity study of regenerator heat exchanger performance, taking into account, such parameters as...

Heat pipe air preheater for gas-/oil-fired power plants

International Nuclear Information System (INIS)

Teixeira, D.P.

1993-02-01

With the rising costs of fuel, utilities are constantly looking for ways to improve the net plant heat rate of new and existing units. Significant heat rate improvements can be obtained by reducing the exit stack flue gas temperature. This project evaluated two technologies to reduce flue gas temperatures: heat pipes and liquid-coupled heat exchangers. The specific unit chosen for evaluating these systems was Pacific Gas ampersand Electric's 750 MW Moss Landing Power Plant, Unit 7. Both natural gas and low sulfur (0.5%) fuel oil are fired at this plant. Accordingly, the heat exchangers were required to operate on both fuels. This study investigated the heat recovery installation through the preliminary engineering level of detail. At the conclusion of this effort, the results indicated that neither concept was economically attractive for the retrofit situation involved. In addition, several major technical questions remained unresolved concerning the design of a single heat-exchange device capable of operating on gas (sulfur-free) and oil (sulfur-containing) environments over the full normal operating load range. While the technologies this study reviewed have been installed in actual power plant applications, the site-specific aspects of Moss Landing Unit 7 significantly influenced the estimated costs and performance of each alternative. Using more cost-effective and corrosion-resistant materials may help reduce costs. The following conditions would further enhance the viability of lowering exit gas temperatures: Higher capacity factors; rising fuel costs; greater use of sulfur-free fuels, such as natural gas; lower manufacturing costs for heat exchanger technologies; or new unit application

The Swiss heating reactor (SHR) for district heating of small communities

International Nuclear Information System (INIS)

Burgsmueller, P.; Jacobi, A.Jr.; Jaeger, J.F.; Klaentschi, M.J.; Seifritz, W.; Vuillemier, F.; Wegmann, F.

1987-01-01

With fossil fuel running out in a foreseeable future, it is essential to develop substitution strategies. Some 40-50 % of the heat demand in industrial countries is below 120 degrees C, for space heating and warm water production, causing a corresponding fraction of air pollution by SO 2 and to a lesser extent NO x if fossil fuels are used. Yet, contemporary LWR technology makes it feasible to supply a district heating network without basically new reactor development. Units in the power range 10-50 MW are most suitable for Switzerland, both in respect of network size and of the democratic decision making structure. A small BWR for heating purpose is being developed by parts of the Swiss Industry and the Swiss Federal Institute for Reactor Research (EIR). The economic target of 100-120 SFr/MWh heat at the consumer's seems achievable. (author)

Mechanical ventilation with heat recovery in cold climates

DEFF Research Database (Denmark)

Kragh, Jesper; Rose, Jørgen; Svendsen, Svend

2005-01-01

Building ventilation is necessary to achieve a healthy and comfortable indoor environment, but as energy prices continue to rise it is necessary to reduce the energy consumption. Using mechanical ventilation with heat recovery reduces the ventilation heat loss significantly, but in cold climates...... freezes to ice. The analysis of measurements from existing ventilation systems with heat recovery used in single-family houses in Denmark and a test of a standard heat recovery unit in the laboratory have clearly shown that this problem occurs when the outdoor temperature gets below approximately –5º......C. Due to the ice problem mechanical ventilation systems with heat recovery are often installed with an extra preheating system reducing the energy saving potential significantly. New designs of high efficient heat recovery units capable of continuously defrosting the ice without using extra energy...

Operational Performance Characterization of a Heat Pump System Utilizing Recycled Water as Heat Sink and Heat Source in a Cool and Dry Climate

Directory of Open Access Journals (Sweden)

Piljae Im

2018-01-01

Full Text Available The wastewater leaving from homes and businesses contains abundant low-grade energy, which can be utilized through heat pump technology to heat and cool buildings. Although the energy in the wastewater has been successfully utilized to condition buildings in other countries, it is barely utilized in the United States, until recently. In 2013, the Denver Museum of Nature & Science at Denver, the United States implemented a unique heat pump system that utilizes recycled wastewater from a municipal water system to cool and heat its 13,000 m2 new addition. This recycled water heat pump (RWHP system uses seven 105 kW (cooling capacity modular water-to-water heat pumps (WWHPs. Each WWHP uses R-410A refrigerant, has two compressors, and can independently provide either 52 °C hot water (HW or 7 °C chilled water (CHW to the building. This paper presents performance characterization results of this RWHP system based on the measured data from December 2014 through August 2015. The annual energy consumption of the RWHP system was also calculated and compared with that of a baseline Heating, Ventilation, and Air Conditioning (HVAC system which meets the minimum energy efficiencies that are allowed by American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE 90.1-2013. The performance analysis results indicate that recycled water temperatures were favorable for effective operation of heat pumps. As a result, on an annual basis, the RWHP system avoided 50% of source energy consumption (resulting from reduction in natural gas consumption although electricity consumption was increased slightly, reduced CO2 emissions by 41%, and saved 34% in energy costs as compared with the baseline system.

Champagne Heat Pump

Science.gov (United States)

Jones, Jack A.

2004-01-01

The term champagne heat pump denotes a developmental heat pump that exploits a cycle of absorption and desorption of carbon dioxide in an alcohol or other organic liquid. Whereas most heat pumps in common use in the United States are energized by mechanical compression, the champagne heat pump is energized by heating. The concept of heat pumps based on other absorption cycles energized by heat has been understood for years, but some of these heat pumps are outlawed in many areas because of the potential hazards posed by leakage of working fluids. For example, in the case of the water/ammonia cycle, there are potential hazards of toxicity and flammability. The organic-liquid/carbon dioxide absorption/desorption cycle of the champagne heat pump is similar to the water/ammonia cycle, but carbon dioxide is nontoxic and environmentally benign, and one can choose an alcohol or other organic liquid that is also relatively nontoxic and environmentally benign. Two candidate nonalcohol organic liquids are isobutyl acetate and amyl acetate. Although alcohols and many other organic liquids are flammable, they present little or no flammability hazard in the champagne heat pump because only the nonflammable carbon dioxide component of the refrigerant mixture is circulated to the evaporator and condenser heat exchangers, which are the only components of the heat pump in direct contact with air in habitable spaces.

A Benders decomposition approach for a combined heat and power economic dispatch

International Nuclear Information System (INIS)

Abdolmohammadi, Hamid Reza; Kazemi, Ahad

2013-01-01

Highlights: • Benders decomposition algorithm to solve combined heat and power economic dispatch. • Decomposing the CHPED problem into master problem and subproblem. • Considering non-convex heat-power feasible region efficiently. • Solving 4 units and 5 units system with 2 and 3 co-generation units, respectively. • Obtaining better or as well results in terms of objective values. - Abstract: Recently, cogeneration units have played an increasingly important role in the utility industry. Therefore the optimal utilization of multiple combined heat and power (CHP) systems is an important optimization task in power system operation. Unlike power economic dispatch, which has a single equality constraint, two equality constraints must be met in combined heat and power economic dispatch (CHPED) problem. Moreover, in the cogeneration units, the power capacity limits are functions of the unit heat productions and the heat capacity limits are functions of the unit power generations. Thus, CHPED is a complicated optimization problem. In this paper, an algorithm based on Benders decomposition (BD) is proposed to solve the economic dispatch (ED) problem for cogeneration systems. In the proposed method, combined heat and power economic dispatch problem is decomposed into a master problem and subproblem. The subproblem generates the Benders cuts and master problem uses them as a new inequality constraint which is added to the previous constraints. The iterative process will continue until upper and lower bounds of the objective function optimal values are close enough and a converged optimal solution is found. Benders decomposition based approach is able to provide a good framework to consider the non-convex feasible operation regions of cogeneration units efficiently. In this paper, a four-unit system with two cogeneration units and a five-unit system with three cogeneration units are analyzed to exhibit the effectiveness of the proposed approach. In all cases, the

Solar heating and cooling of buildings

Science.gov (United States)

Bourke, R. D.; Davis, E. S.

1975-01-01

Solar energy has been used for space heating and water heating for many years. A less common application, although technically feasible, is solar cooling. This paper describes the techniques employed in the heating and cooling of buildings, and in water heating. The potential for solar energy to displace conventional energy sources is discussed. Water heating for new apartments appears to have some features which could make it a place to begin the resurgence of solar energy applications in the United States. A project to investigate apartment solar water heating, currently in the pilot plant construction phase, is described.

Probabilistic assessment of the potential indoor air impacts of vent-free gas heating appliances in energy-efficient homes in the United States.

Science.gov (United States)

Whitmyre, Gary K; Pandian, Muhilan D

2018-06-01

Use of vent-free gas heating appliances for supplemental heating in U.S. homes is increasing. However, there is currently a lack of information on the potential impact of these appliances on indoor air quality for homes constructed according to energy-efficient and green building standards. A probabilistic analysis was conducted to estimate the impact of vent-free gas heating appliances on indoor air concentrations of carbon monoxide (CO), nitrogen dioxide (NO 2 ), carbon dioxide (CO 2 ), water vapor, and oxygen in "tight" energy-efficient homes in the United States. A total of 20,000 simulations were conducted for each Department of Energy (DOE) heating region to capture a wide range of home sizes, appliance features, and conditions, by varying a number of parameters, e.g., room volume, house volume, outdoor humidity, air exchange rates, appliance input rates (Btu/hr), and house heat loss factors. Predicted airborne levels of CO were below the U.S. Environmental Protection Agency (EPA) standard of 9 ppm for all modeled cases. The airborne concentrations of NO 2 were below the U.S. Consumer Product Safety Commission (CPSC) guideline of 0.3 ppm and the Health Canada benchmark of 0.25 ppm in all cases and were below the World Health Organization (WHO) standard of 0.11 ppm in 99-100% of all cases. Predicted levels of CO 2 were below the Health Canada standard of 3500 ppm for all simulated cases. Oxygen levels in the room of vent-free heating appliance use were not significantly reduced. The great majority of cases in all DOE regions were associated with relative humidity (RH) levels from all indoor water vapor sources that were less than the EPA-recommended 70% RH maximum to avoid active mold and mildew growth. The conclusion of this investigation is that when installed in accordance with the manufacturer's instructions, vent-free gas heating appliances maintain acceptable indoor air quality in tight energy-efficient homes, as defined by the standards referenced in

Solar/electric heating systems for the future energy system

Energy Technology Data Exchange (ETDEWEB)

Furbo, S.; Dannemand, M.; Perers, B. [and others

2013-05-15

The aim of the project is to elucidate how individual heating units for single family houses are best designed in order to fit into the future energy system. The units are based on solar energy, electrical heating elements/heat pump, advanced heat storage tanks and advanced control systems. Heat is produced by solar collectors in sunny periods and by electrical heating elements/heat pump. The electrical heating elements/heat pump will be in operation in periods where the heat demand cannot be covered by solar energy. The aim is to use the auxiliary heating units when the electricity price is low, e.g. due to large electricity production by wind turbines. The unit is equipped with an advanced control system where the control of the auxiliary heating is based on forecasts of the electricity price, the heat demand and the solar energy production. Consequently, the control is based on weather forecasts. Three differently designed heating units are tested in a laboratory test facility. The systems are compared on the basis of: 1) energy consumption for the auxiliary heating; 2) energy cost for the auxiliary heating; 3) net utilized solar energy. Starting from a normal house a solar combi system (for hot water and house heating) can save 20-30% energy cost, alone, depending on sizing of collector area and storage volume. By replacing the heat storage with a smart tank based on electric heating elements and a smart control based on weather/load forecast and electricity price information 24 hours ahead, another 30-40% can be saved. That is: A solar heating system with a solar collector area of about 10 m{sup 2}, a smart tank based on electric heating element and a smart control system, can reduce the energy costs of the house by at least 50%. No increase of heat storage volume is needed to utilize the smart control. The savings in % are similar for different levels of building insulation. As expected a heat pump in the system can further reduce the auxiliary electricity

Ventilation with heat recovery

DEFF Research Database (Denmark)

Tommerup, Henrik M.; Svendsen, Svend

2005-01-01

This paper presents the experiences from the use of ventilation with heat recovery in several experimental single-family houses developed and built within the last four years to meet the new Danish energy requirements of 2005. Included are descriptions of the ventilation system components...... and the main functional demands as well as measurements of the thermal efficiency, electricity consumptions and building air tightness. The paper addresses the aspects of minimizing the heat loss from the duct system and the heat recovery unit (when placed in an unheated attic space) in order to obtain...

Development and fabrication of heat-sterilizable inhalation therapy equipment

Science.gov (United States)

Irons, A. S.

1974-01-01

The development of a completely heat sterilizable intermittent positive pressure breathing (IPPB) ventilator in an effort to reduce the number of hospital acquired infections is reported. After appropriate changes in materials and design were made, six prototype units were fabricated and were successfully field tested in local hospitals. Most components of the modified ventilators are compatible with existing machines. In all but a few instances, such as installation of bacteria-retentive filters and a modified venturi, the change over from non-heat-sterilizable to sterilizable units was accomplished by replacement of heat labile materials with heat stable materials.

D0 HVAC System Heat Pump Controller Programming, Networking, and Operating Information

International Nuclear Information System (INIS)

Anderson, B.

1999-01-01

The purpose of this engineering note is to provide the necessary information to setup, program, and network the Electronic Systems USA Heat Pump Controller with the LON network card and Intellution Fix32 to operate properly within the HVAC system at D-Zero. The heat pump controllers are used for local temperature control of the office environments on the fifth and six floors of D-Zero. Heat pump units 1-6 are located in the ceiling of the sixth floor. Heat pump units 7-12 are found in the fifth floor ceiling. Heat pump unit 13 is in the Southeast corner of the fifth floor. Prior to installation the heat pump controller must be properly prepared to operate correctly in the HVAC system. Each heat pump unit must contain firmware (software) version 1.31 to operate properly on the network. Controllers with version 1.30 will not be able to communicate over the LON network. The manufacturer can only update the firmware version. Before installation a series of heat pump setpoints must be manually set using the Intelligent Stat. Connect the Intelligent Stat via the serial cable or wired connection.

Dual-stroke heat pump field performance

Science.gov (United States)

Veyo, S. E.

1984-11-01

Two nearly identical proprototype systems, each employing a unique dual-stroke compressor, were built and tested. One was installed in an occupied residence in Jeannette, Pa. It has provided the heating and cooling required from that time to the present. The system has functioned without failure of any prototypical advanced components, although early field experience did suffer from deficiencies in the software for the breadboard micro processor control system. Analysis of field performance data indicates a heating performance factor (HSPF) of 8.13 Stu/Wa, and a cooling energy efficiency (SEER) of 8.35 Scu/Wh. Data indicate that the beat pump is oversized for the test house since the observed lower balance point is 3 F whereas 17 F La optimum. Oversizing coupled with the use of resistance heat ot maintain delivered air temperature warmer than 90 F results in the consumption of more resistance heat than expected, more unit cycling, and therefore lower than expected energy efficiency. Our analysis indicates that with optimal mixing the dual stroke heat pump will yield as HSFF 30% better than a single capacity heat pump representative of high efficiency units in the market place today for the observed weather profile.

District heating with SLOWPOKE energy systems

International Nuclear Information System (INIS)

Lynch, G.F.

1988-03-01

The SLOWPOKE Energy System, a benign nuclear heat source designed to supply 10 thermal megawatts in the form of hot water for local heating systems in buildings and institutions, is at the forefront of these developments. A demonstration unit has been constructed in Canada and is currently undergoing an extensive test program. Because the nuclear heat source is small, operates at atmospheric pressure, and produces hot water below 100 degrees Celcius, intrinsic safety features will permit minimum operator attention and allow the heat source to be located close to the load and hence to people. In this way, a SLOWPOKE Energy System can be considered much like the oil- or coal-fired furnace it is designed to replace. The low capital investment requirements, coupled with a high degree of localization, even for the first unit, are seen as attractive features for the implementation of SLOWPOKE Energy Systems in many countries

Behavior of copper corrosion products in water loops of heat-exchange units

International Nuclear Information System (INIS)

Zarembo, V.I.; Kritskii, V.G.; Slobodov, A.A.; Puchkov, L.V.

1989-01-01

This communication is dedicated to an examination of copper corrosion products (CP) in the conditions of real aqueous-chemical regime (ACR) parameters. The deposition of these CP in steam-generating zones (up to 85% of their total amount) stimulate local types of corrosion. The solubility in Cu CP (Cu 2 O, CuO, Cu(OH) 2 )-water (H 2 O)-gas (H 2 , O 2 )-conditioning additives (HCl, KOH) systems was determined by computer modeling according to the minimum Gibbs energy criterion on the basis of selected and matched thermodynamic constants for various chemical forms of copper under standard conditions. As a result of the authors' calculations they obtained the solubilities in water of CuO, Cu 2 O and Cu(OH) 2 when changing the dosage of active gases from 0 to 10 -2 mole/kg of water, of acid or equal to that of saturated vapor of pure water. Thus, they were able to monitor the behavior of copper CP in conditions modeling those of real ACR in operating heat exchange units, including in conditions deviating from the standard

Economic feasibility of heat supply from nuclear power plants in the United States

International Nuclear Information System (INIS)

Roe, K.K.; Oliker, I.

1987-01-01

Nuclear energy is regarded as competitive for urban district heating applications. Hot water heat transoport systems of up to 50 miles are feasible for heat loads over 1500 MWt, and heat load density of over 130 MWt/mi 2 is most suitable for nuclear applications. An incremental approach and a nuclear plant design provision for future heat extraction are recommended. Nuclear district heating technology status is discussed, particularly turbine design. Results of a study for retrofitting a major existing nuclear power plant to cogeneration operation are presented. The study indicates that for transmission distances up to 20 miles it is economical to generate and transport between 600 and 1200 MWt of district heat (author)

Heat transfer pipe shielding device for heat exchanger

International Nuclear Information System (INIS)

Hanawa, Jun.

1991-01-01

The front face and the rear face of a frame that surrounds the circumference of the water chamber body of a multi-tube heat exchanger are covered by a rotational shielding plate. A slit is radially formed to the shielding plate for the insertion of a probe or cleaner to the heat transfer pipe and a deflector is disposed on the side opposite to the slit. The end of the heat transfer pipe to be inspected is exposed to the outer side by way of the slit by the rotation of the shielding plate, and the probe or cleaner is inserted in the heat transfer pipe to conduct an eddy current injury monitoring test or cleaning. The inside of the water chamber and the heat transfer pipe is exhausted by a ventilation nozzle disposed to the frame. Accordingly, a shielding effect upon inspection and cleaning can be obtained and, in addition, inspection and exhaustion at the cleaning position can be conducted easily. Since the operation for attachment and detachment is easy, the effect of reducing radiation dose per unit can be obtained by the shortening of the operation time. (N.H.)

Rapid response to intensive treatment for bulimia nervosa and purging disorder: A randomized controlled trial of a CBT intervention to facilitate early behavior change.

Science.gov (United States)

MacDonald, Danielle E; McFarlane, Traci L; Dionne, Michelle M; David, Lauren; Olmsted, Marion P

2017-09-01

Rapid response to cognitive behavior therapy (CBT) for eating disorders (i.e., rapid and substantial change to key eating disorder behaviors in the initial weeks of treatment) robustly predicts good outcome at end-of-treatment and in follow up. The objective of this study was to determine whether rapid response to day hospital (DH) eating disorder treatment could be facilitated using a brief adjunctive CBT intervention focused on early change. 44 women (average age 27.3 [8.4]; 75% White, 6.3% Black, 6.9% Asian) were randomly assigned to 1 of 2 4-session adjunctive interventions: CBT focused on early change, or motivational interviewing (MI). DH was administered as usual. Outcomes included binge/purge frequency, Eating Disorder Examination-Questionnaire and Difficulties in Emotion Regulation Scale. Intent-to-treat analyses were used. The CBT group had a higher rate of rapid response (95.7%) compared to MI (71.4%; p = .04, V = .33). Those who received CBT also had fewer binge/purge episodes (p = .02) in the first 4 weeks of DH. By end-of-DH, CBT participants made greater improvements on overvaluation of weight and shape (p = .008), and emotion regulation (ps .05). The results of this study demonstrate that rapid response can be clinically facilitated using a CBT intervention that explicitly encourages early change. This provides the foundation for future research investigating whether enhancing rates of rapid response using such an intervention results in improved longer term outcomes. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

The increase performance BMF-14 calcination unit

International Nuclear Information System (INIS)

Triyono

2013-01-01

The heating element of performance increase BMF-14 calcination unit has been installed. The activity includes: installation and function test heating element step by step. The main component includes: kanthal heating element type with size long 58,2 cm diameter 0,9 cm slot total 28, flexible cable resists heat 30 Amperes, band cable heat resists and flexible clamp. The heating elements installation includes from 3 groups and every groups have 4 heating elements to connectly series. Every group connecting to every phase RST and neutral for getting electric voltage 380 Volts follow contact relay 3 phases to controlling by digital temperature control. The resulting installation of heating element in the BMF-14 calcination unit showed that: BMF-14 calcination unit can be again of the setting temperature step by step. In the step I get optimal temperature 560 °C test time 1068 minutes with rate velocity heat 0 to 18,0 °C/minutes with current between 5,8 to 6,4 Amperes voltage 103 to 123 Volts (phase R and T). In the step II gets optimal temperature 600 °C test time 265 minutes getting rate velocity heat 0 to 40,3 °C/minutes with current 3,8 to 8,5 Amperes voltage 76 to 142 Volts (phase RST). In the step III gets optimal temperature 1000 °C test time 107 minutes getting rate velocity heat 0 to 53,5 °C/minutes with current 9,7 to 12,5 Amperes voltage 215 to 225 Volts (phase RST). (author)

Building Space Heating with a Solar-Assisted Heat Pump Using Roof-Integrated Solar Collectors

Directory of Open Access Journals (Sweden)

Zhiyong Yang

2011-03-01

Full Text Available A solar assisted heat pump (SAHP system was designed by using a roof-integrated solar collector as the evaporator, and then it was demonstrated to provide space heating for a villa in Tianjin, China. A building energy simulation tool was used to predict the space heating load and a three dimensional theoretical model was established to analyze the heat collection performance of the solar roof collector. A floor radiant heating unit was used to decrease the energy demand. The measurement results during the winter test period show that the system can provide a comfortable living space in winter, when the room temperature averaged 18.9 °C. The average COP of the heat pump system is 2.97 and with a maximum around 4.16.

The Analysis of Loop Seal Purge Time for the KHNP Pressurizer Safety Valve Test Facility Using the GOTHIC Code

Energy Technology Data Exchange (ETDEWEB)

Kim, Young Ae; Kim, Chang Hyun; Kweon, Gab Joo; Park, Jong Woon [Korea Hydro and Nuclear Power Co., Ltd., Daejeon (Korea, Republic of)

2007-10-15

The pressurizer safety valves (PSV) in Pressurized Water Reactors are required to provide the overpressure protection for the Reactor Coolant System (RCS) during the overpressure transients. Korea Hydro and Nuclear Power Company (KHNP) plans to build the PSV test facility for the purpose of providing the PSV pop-up characteristics and the loop seal dynamics for the new safety analysis. When the pressurizer safety valve is mounted in a loop seal configuration, the valve must initially pass the loop seal water prior to popping open on steam. The loop seal in the upstream of PSV prevents leakage of hydrogen gas or steam through the safety valve seat. This paper studies on the loop seal clearing dynamics using GOTHIC-7.2a code to verify the effects of loop seal purge time on the reactor coolant system overpressure.

Heat transfer analysis of underground U-type heat exchanger of ground source heat pump system.

Science.gov (United States)

Pei, Guihong; Zhang, Liyin

2016-01-01

Ground source heat pumps is a building energy conservation technique. The underground buried pipe heat exchanging system of a ground source heat pump (GSHP) is the basis for the normal operation of an entire heat pump system. Computational-fluid-dynamics (CFD) numerical simulation software, ANSYS-FLUENT17.0 have been performed the calculations under the working conditions of a continuous and intermittent operation over 7 days on a GSHP with a single-well, single-U and double-U heat exchanger and the impact of single-U and double-U buried heat pipes on the surrounding rock-soil temperature field and the impact of intermittent operation and continuous operation on the outlet water temperature. The influence on the rock-soil temperature is approximately 13 % higher for the double-U heat exchanger than that of the single-U heat exchanger. The extracted energy of the intermittent operation is 36.44 kw·h higher than that of the continuous mode, although the running time is lower than that of continuous mode, over the course of 7 days. The thermal interference loss and quantity of heat exchanged for unit well depths at steady-state condition of 2.5 De, 3 De, 4 De, 4.5 De, 5 De, 5.5 De and 6 De of sidetube spacing are detailed in this work. The simulation results of seven working conditions are compared. It is recommended that the side-tube spacing of double-U underground pipes shall be greater than or equal to five times of outer diameter (borehole diameter: 180 mm).

Necessity for usage of geothermal heat pump

International Nuclear Information System (INIS)

Dimitrov, Konstantin; Armenski, Slave; Gacevski, Marijan

2004-01-01

Every day we are witnesses of constantly rapid increase of consumption of Electric energy in R. of Macedonia as so as in the other countries in all the world. This rapid increase of consumption of Electric energy independent of a lot of electrical units, which are applying in human life like: homes, administration and publication objects, as well as in industry. All of this conditions make us to thinking how is possible more rational consumption of electric energy in all areas in human life. One of the possible manners to reduce the consumption of electrical energy for heating and cooling is to use geothermal heat pumps. In this paper will be proposed geothermal heat pump, which is going to use the heat of earth by vertical and horizontal cupper pipe heat exchanger with data from-GHP (Geothermal Heat Pump) NORDIC, factory in Canada. Also, it will be examined all parameters and done comparison with already existing ones. It is analyzed comparison of GHP with other energy units and what it means for rational consumption of electric energy, economic saving and ecology saving. (Author)

Simulation and experimental study of solar-absorption heat transformer integrating with two-stage high temperature vapor compression heat pump

Directory of Open Access Journals (Sweden)

Nattaporn Chaiyat

2014-11-01

Full Text Available In this study, simulation and experiment studies of a 10 kW solar H2O–LiBr absorption heat transformer (AHT integrating with a two-stage vapor compression heat pump (VCHP were carried out. The whole system was named as compression/absorption heat transformer (CAHT. The VCHP was used to recover rejected heat at the AHT condenser which was transferred back to the AHT evaporator at a higher temperature. The AHT unit took solar heat from a set of flat-plate solar collectors in parallel connection. R-134a and R-123 were refrigerants in the VCHP cycle. From the simulation, the total cycle coefficient (COP of the solar-CAHT was 0.71 compared with 0.49 of the normal solar-AHT. From the experiment, the total cycle COPs of the solar-CAHT and the solar-AHT were 0.62 and 0.39, respectively. The experimental results were lower than those of the simulated models due to the oversize of the experimental compressor. The annual expense of the solar-CAHT was found to be 5113 USD which was lower than 5418 USD of the solar-AHT. So it could be concluded that the modified unit was beneficial than the normal unit in terms of energy efficiency and economic expense.

Technical Note: A fully automated purge and trap GC-MS system for quantification of volatile organic compound (VOC fluxes between the ocean and atmosphere

Directory of Open Access Journals (Sweden)

S. J. Andrews

2015-04-01

Full Text Available The oceans are a key source of a number of atmospherically important volatile gases. The accurate and robust determination of trace gases in seawater is a significant analytical challenge, requiring reproducible and ideally automated sample handling, a high efficiency of seawater–air transfer, removal of water vapour from the sample stream, and high sensitivity and selectivity of the analysis. Here we describe a system that was developed for the fully automated analysis of dissolved very short-lived halogenated species (VSLS sampled from an under-way seawater supply. The system can also be used for semi-automated batch sampling from Niskin bottles filled during CTD (conductivity, temperature, depth profiles. The essential components comprise a bespoke, automated purge and trap (AutoP & T unit coupled to a commercial thermal desorption and gas chromatograph mass spectrometer (TD-GC-MS. The AutoP & T system has completed five research cruises, from the tropics to the poles, and collected over 2500 oceanic samples to date. It is able to quantify >25 species over a boiling point range of 34–180 °C with Henry's law coefficients of 0.018 and greater (CH22l, kHcc dimensionless gas/aqueous and has been used to measure organic sulfurs, hydrocarbons, halocarbons and terpenes. In the eastern tropical Pacific, the high sensitivity and sampling frequency provided new information regarding the distribution of VSLS, including novel measurements of a photolytically driven diurnal cycle of CH22l within the surface ocean water.

Performance of double source boiler with coal-fired and solar power tower heat for supercritical power generating unit

International Nuclear Information System (INIS)

Zhang, Maolong; Du, Xiaoze; Pang, Liping; Xu, Chao; Yang, Lijun

2016-01-01

An approach of high-efficiency utilization of solar energy was proposed, by which the high concentrated heat received by the solar tower was integrated to the supercritical coal-fired boiler. Two schemes that solar energy was used to heat superheat steam or subcooled feed water were presented. The thermodynamic and heat transfer models were established. For a practical 660 MW supercritical power generating unit, the standard coal consumption of power generation could be decreased by more than 17 g/kWh by such double source boiler. The drawbacks of both schemes were found and then were amended by adding a flue gas bypass to the boiler. It also can be concluded that the maximum solar contribution of two schemes for the gross power generation are 6.11% and 4.90%, respectively. The solar power efficiency of the re-modified designs were demonstrated be superior to that of PS10. In terms of turbine efficiency, the comparisons with Solar Two plant having similar initial temperature found that the efficiency of Scheme I was 5.25% higher than that of Solar Two while the advantage of Scheme II was existing either. Additionally, in two schemes with flue bypass when the medium was extracted, the thermal efficiency of boiler could be improved as well. - Highlights: • High concentrated solar tower heat is integrated to the supercritical coal-fired boiler. • The double source boiler can use solar energy to heat superheat steam or subcooled feed water. • Power generating coal consumption can be reduced by more than 17 g/kWh by the double source boiler. • The solar contribution of double source boiler for the gross power generation can be as high as 6.11%.

Quantity, Quality, and Availability of Waste Heat from United States Thermal Power Generation.

Science.gov (United States)

Gingerich, Daniel B; Mauter, Meagan S

2015-07-21

Secondary application of unconverted heat produced during electric power generation has the potential to improve the life-cycle fuel efficiency of the electric power industry and the sectors it serves. This work quantifies the residual heat (also known as waste heat) generated by U.S. thermal power plants and assesses the intermittency and transport issues that must be considered when planning to utilize this heat. Combining Energy Information Administration plant-level data with literature-reported process efficiency data, we develop estimates of the unconverted heat flux from individual U.S. thermal power plants in 2012. Together these power plants discharged an estimated 18.9 billion GJ(th) of residual heat in 2012, 4% of which was discharged at temperatures greater than 90 °C. We also characterize the temperature, spatial distribution, and temporal availability of this residual heat at the plant level and model the implications for the technical and economic feasibility of its end use. Increased implementation of flue gas desulfurization technologies at coal-fired facilities and the higher quality heat generated in the exhaust of natural gas fuel cycles are expected to increase the availability of residual heat generated by 10.6% in 2040.

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...

Experimental study on heat pipe assisted heat exchanger used for industrial waste heat recovery

International Nuclear Information System (INIS)

Ma, Hongting; Yin, Lihui; Shen, Xiaopeng; Lu, Wenqian; Sun, Yuexia; Zhang, Yufeng; Deng, Na

2016-01-01

Highlights: • A heat pipe heat exchanger (HPHE) was used to recycle the waste heat in a slag cooling process of steel industry. • An specially designed on-line cleaning device was construed and used to enhance the heat transfer of HPHE. • The performance characteristics of a HPHE has been assessed by integrating the first and second law of thermodynamics. • The optimum operation conditions was determined by integrating the first and the second law of thermodynamics. - Abstract: Steel industry plays an important role economically in China. A great amount of hot waste liquids and gases are discharged into environment during many steelmaking processes. These waste liquids and gases have crucial energy saving potential, especially for steel slag cooling process. It could be possible to provide energy saving by employing a waste heat recovery system (WHRS). The optimum operation condition was assessed by integrating the first and the second law of thermodynamics for a water–water heat pipe heat exchanger (HPHE) for a slag cooling process in steel industry. The performance characteristics of a HPHE has been investigated experimentally by analyzing heat transfer rate, heat transfer coefficient, effectiveness, exergy efficiency and number of heat transfer units (NTU). A specially designed on-line cleaning device was used to clean the heat exchange tubes and enhance heat transfer. The results indicated that the exergy efficiency increased with the increment of waste water mass flow rate at constant fresh water mass flow rate, while the effectiveness decreased at the same operation condition. As the waste water mass flow rate varied from 0.83 m"3/h to 1.87 m"3/h, the effectiveness and exergy efficiency varied from 0.19 to 0.09 and from 34% to 41%, respectively. In the present work, the optimal flow rates of waste water and fresh water were 1.20 m"3/h and 3.00 m"3/h, respectively. The on-line cleaning device had an obvious effect on the heat transfer, by performing

Results of Steam-Water-Oxygen Treatment of the Inside of Heating Surfaces in Heat-Recovery Steam Generators of the PGU-800 Power Unit at the Perm' District Thermal Power Station

Science.gov (United States)

Ovechkina, O. V.; Zhuravlev, L. S.; Drozdov, A. A.; Solomeina, S. V.

2018-05-01

Prestarting, postinstallation steam-water-oxygen treatment (SWOT) of the natural circulation/steam reheat heat-recovery steam generators (HRSG) manufactured by OAO Krasny Kotelshchik was performed at the PGU-800 power unit of the Perm District Thermal Power Station (GRES). Prior to SWOT, steam-oxygen cleaning, passivation, and preservation of gas condensate heaters (GCH) of HRSGs were performed for 10 h using 1.3MPa/260°C/70 t/h external steam. After that, test specimens were cut out that demonstrated high strength of the passivating film. SWOT of the inside of the heating surfaces was carried out during no-load operation of the gas turbine unit with an exhaust temperature of 280-300°C at the HRSG inlet. The steam turbine was shutdown, and the generated steam was discharged into the atmosphere. Oxygen was metered into the discharge pipeline of the electricity-driven feed pumps and downcomers of the evaporators. The behavior of the concentration by weight of iron compounds and the results of investigation of cutout specimens by the drop or potentiometric method indicate that the steam-water-oxygen process makes it possible to remove corrosion products and reduce the time required to put a boiler into operation. Unlike other processes, SWOT does not require metal-intensive cleaning systems, temporary metering stations, and structures for collection of the waste solution.

Exergy costing for energy saving in combined heating and cooling applications

International Nuclear Information System (INIS)

Nguyen, Chan; Veje, Christian T.; Willatzen, Morten; Andersen, Peer

2014-01-01

Highlights: • We investigate the basis for cost apportioning of simultaneous heating and cooling. • Two thermoeconomic methods based on energy and exergy costing is demonstrated. • The unit cost of heating and cooling for a heat pump system is found and compared. • Energy costing may obstruct efficient use of energy. • Exergy costing provides the most rational cost apportioning for energy saving. - Abstract: The aim of this study is to provide a price model that motivates energy saving for a combined district heating and cooling system. A novel analysis using two thermoeconomic methods for apportioning the costs to heating and cooling provided simultaneously by an ammonia heat pump is demonstrated. In the first method, referred to as energy costing, a conventional thermoeconomic analysis is used. Here the ammonia heat pump is subject to a thermodynamic analysis with mass and energy balance equations. In the second method referred to as exergy costing, an exergy based economic analysis is used, where exergy balance equations are used in conjunction with mass and energy balance equations. In both costing methods the thermodynamic analysis is followed by an economic analysis which includes investment and operating costs. For both methods the unit costs of heating and cooling are found and compared. The analysis shows that the two methods yield significantly different results. Rather surprisingly, it is demonstrated that the exergy costing method results in about three times higher unit cost for heating than for cooling as opposed to equal unit costs when using the energy method. Further the exergy-based cost for heating changes considerably with the heating temperature while that of cooling is much less affected

POTENTIAL USE OF PHASE CHANGE MATERIALS IN GREENHOUSES HEATING: COMPARISON WITH A TRADITIONAL SYSTEM

Directory of Open Access Journals (Sweden)

Claudio Caprara

2009-09-01

Full Text Available In order to use solar radiation as thermal energy source, heat storage equipments result necessary in each application where continuous supply is required, because of the natural unsteady intensity of radiation during the day. Thermal solar collectors are especially suitable for low temperature applications, since their efficiency decreases when an high inlet temperature of fluid flowing through them is established. On the other hand, low temperatures and low temperature gaps, above all, make very difficult to use traditional sensible heat storing units (water tanks, because of the very large amounts of material required. In this work, a traditional sensible heat storage system is compared with a latent heat storing unit based on phase change materials (PCMs. As a case study, a 840 m3 greenhouse heating application was considered with an inside constant temperature of 18°C. It is thought to be heated by using single layer plate thermal solar collectors as energy source. Inlet temperature of the collectors fluid (HTF was fixed at 35°C (little higher than melting temperature of PCMs and a constant flux of 12 l/m2 hour was established as technical usual value. At these conditions, 215m2 solar panels exposed surface resulted necessary. The sensible heat storage system considered here is a traditional water tank storing unit equipped with two pipe coils, respectively for heat exchanges with HTF from collectors and water flux for greenhouse heating. Available DT for heat exchange is estimated as the difference of minimum HTF temperature (in outlet from the collectors and the required water temperature for greenhouse heating. The latent heat storing unit is instead a series of copper rectangular plate shells which a phase change material is filled in (Na2SO4⋅10H2O. Heat transfer fluids flow through thin channels between adjacent plates, so that a large heat exchange available surface is achieved. The developed computational model (Labview software

Double-effect absorption heat pump, phase 3

Science.gov (United States)

Cook, F. B.; Cremean, S. P.; Jatana, S. C.; Johnson, R. A.; Malcosky, N. D.

1987-06-01

The RD&D program has resulted in design, development and testing of a packaged prototype double-effect generator cycle absorption gas heat pump for the residential and small commercial markets. The 3RT heat pump prototype has demonstrated a COPc of 0.82 and a COPh of 1.65 at ARI rating conditions. The heat pump prototype includes a solid state control system with built-in diagnostics. The absorbent/refrigerant solution thermophysical properties were completely characterized. Commercially available materials of construction were identified for all heat pump components. A corrosion inhibitor was identified and tested in both static and dynamic environments. The safety of the heat pump was analyzed by using two analytical approaches. Pioneer Engineering estimated the factory standard cost to produce the 3RT heat pump at $1,700 at a quantity of 50,000 units/year. One United States patent was allowed covering the heat pump technology, and two divisional applications and three Continuation-in-Park Applications were filed with the U.S.P.T.O. Corresponding patent coverage was applied for in Canada, the EEC, Australia, and Japan. Testing of the prototype heat pump is continuing, as are life tests of multiple pump concepts amd long-term dynamic corrosion tests. Continued development and commercialization of gas absorption heat pumps based on the technology are recommended.

Urban Heat Wave Hazard Assessment

Science.gov (United States)

Quattrochi, Dale A.; Jedlovec, Gary; Meyer, Paul J.; LaFontaine, Frank J.; Crane, Dakota L.

2016-01-01

Heat waves are the largest cause of environment-related deaths globally. On average, over 6,000 people in the United States alone are hospitalized each summer due to excessive heat. Key elements leading to these disasters are elevated humidity and the urban heat island effect, which act together to increase apparent temperature and amplify the effects of a heat wave. Urban demographics and socioeconomic factors also play a role in determining individual risk. Currently, advisories of impending heat waves are often too generalized, with limited or no spatial variability over urban regions. This frequently contributes to a lack of specific response on behalf of the population. A goal of this project is to develop a product that has the potential to provide more specific heat wave guidance invoking greater awareness and action.

Combined heat and power unit using renewable raw materials. A cogeneration power plant with wood chips and pellets; BHKW auf Basis nachwachsender Rohstoffe. KWK mit Holzhackschnitzeln und Pellets

Energy Technology Data Exchange (ETDEWEB)

Lennartz, Marc Wilhelm

2013-07-15

The combined heat and power units of the next generation operate with renewable resources. The plants working with wood chips or pellets now are ready for mass production. So, farmers and foresters, trade and municipalities may pile in the decentralized, energetic self-sufficiency. Two companies have developed procedures with which combined heat and power plants based can be operated on wood chips or pellets.

Calorie estimation accuracy and menu labeling perceptions among individuals with and without binge eating and/or purging disorders.

Science.gov (United States)

Roberto, Christina A; Haynos, Ann F; Schwartz, Marlene B; Brownell, Kelly D; White, Marney A

2013-09-01

Menu labeling is a public health policy that requires chain restaurants in the USA to post kilocalorie information on their menus to help consumers make informed choices. However, there is concern that such a policy might promote disordered eating. This web-based study compared individuals with self-reported binge eating disorder (N = 52), bulimia nervosa (N = 25), and purging disorder (N = 17) and those without eating disorders (No ED) (N = 277) on restaurant calorie information knowledge and perceptions of menu labeling legislation. On average, people answered 1.46 ± 1.08 questions correctly (out of 6) (25%) on a calorie information quiz and 92% of the sample was in favor of menu labeling. The findings did not differ based on eating disorder, dieting, or weight status, or race/ethnicity. The results indicated that people have difficulty estimating the calories in restaurant meals and individuals with and without eating disorders are largely in favor of menu labeling laws.

Numerical Study of the Dynamic Response of Heat and Mass Transfer to Operation Mode Switching of a Unitized Regenerative Fuel Cell

Directory of Open Access Journals (Sweden)

Hong Xiao

2016-12-01

Full Text Available Knowledge concerning the complicated changes of mass and heat transfer is desired to improve the performance and durability of unitized regenerative fuel cells (URFCs. In this study, a transient, non-isothermal, single-phase, and multi-physics mathematical model for a URFC based on the proton exchange membrane is generated to investigate transient responses in the process of operation mode switching from fuel cell (FC to electrolysis cell (EC. Various heat generation mechanisms, including Joule heat, reaction heat, and the heat attributed to activation polarizations, have been considered in the transient model coupled with electrochemical reaction and mass transfer in porous electrodes. The polarization curves of the steady-state models are validated by experimental data in the literatures. Numerical results reveal that current density, gas mass fractions, and temperature suddenly change with the sudden change of operating voltage in the mode switching process. The response time of temperature is longer than that of current density and gas mass fractions. In both FC and EC modes, the cell temperature and gradient of gas mass fraction in the oxygen side are larger than that in the hydrogen side. The temperature difference of the entire cell is less than 1.5 K. The highest temperature appears at oxygen-side catalyst layer under the FC mode and at membrane under a more stable EC mode. The cell is exothermic all the time. These dynamic responses and phenomena have important implications for heat analysis and provide proven guidelines for the improvement of URFCs mode switching.

Scheduling of radio-controlled heating load

International Nuclear Information System (INIS)

Fox, B.; McCartney, A.I.; McCann, B.M.

1998-01-01

An economic loading program has been adapted to enable it to obtain an optimum heat-load profile to meet the forecast heat requirement. The heat load is represented by a 'generator' whose load is constrained to be negative. The incremental cost of this unit is a heat energy price. This is adjusted to obtain a heat profile containing the requisite energy. The profile is then used by a dynamic programming algorithm to derive a commitment pattern for each block. A case study is presented which shows that the procedure can minimise heat energy cost. It is also shown that use of the proposed method results in less generator load cycling. This reduced regulation duty should improve reliability. (author)

SLOWPOKE: heating reactors in the urban environment

International Nuclear Information System (INIS)

Hilborn, J.W.; Lynch, G.F.

1988-06-01

Since global energy requirements are expected to double over the next 40 years, nuclear heating could become as important as nuclear electricity generation. To fill that need, AECL has designed a 10 MW nuclear heating plant for large buildings. Producing hot water at temperatures below 100 degrees Celsius, it incorporates a small pool-type reactor based on the successful SLOWPOKE Research Reactor. A 2 MW prototype is now being tested at the Whiteshell Nuclear Research Establishment in Manitoba, and the design of a 10 MW commercial unit is well advanced. With capital costs in the range $5 million to $7 million, unit energy costs could be as low as $0.02 per kWh, for a unit operating at 50% load factor over a 25-year period. By keeping the reactor power low and the water temperature below 100 degrees Celsius, much of the complexity of the large nuclear power plants can be avoided, thus allowing these small, safe, nuclear heating systems to be economically viable

Heat Roadmap Europe 3 (STRATEGO)

DEFF Research Database (Denmark)

Connolly, David; Hansen, Kenneth; Drysdale, David

Heat Roadmap Europe 3 is from work package 2 of the STRATEGO project (http://stratego-project.eu/). It quantifies the impact of implementing various energy efficiency measures in the heating and cooling sectors of five EU Member States: Czech Republic, Croatia, Italy, Romania, and the United...... of approximately €1.1 trillion in energy efficiency measures across all five of these countries, between 2010 and 2050, will save enough fuel to reduce the costs of their energy systems. After considering both the initial investment and the resulting savings, the total annual cost of the heating, cooling......, and electricity sectors is reduced by an average of ~15% in each country. These initial investments are primarily required in heat savings for the buildings, district heating in urban areas, and electric heat pumps in rural areas. In essence, energy efficiency measures in the heating sector will enable EU Member...

Open heat exchanger for improved heat efficiency in geothermal spas

Energy Technology Data Exchange (ETDEWEB)

Nasrabady, S.J.; Palsson, H.; Saevarsdottir, G.A.

2008-09-15

Hot spas and Jacuzzis are popular in Iceland due to the abundance of reasonably prized geothermal heat available. However the water from the district heating system is too warm to be admitted directly into the spa. For safety reasons the water is mixed with cold water, in order to reduce temperature from about 80 deg C down to 45 deg C, which leads to wasting a large quantity of heat. Therefore a design is suggested here that enables the feeding of geothermal water directly into the spa, omitting the step of mixing it with cold water. The idea is to employ an open heat exchanger that transfers heat from the geothermal water to the bulk water in the spa, before letting it mix with the spa water. A case study was done for one particular spa. Heat load was calculated and measured when the spa was in use, and when it was unused. A design is suggested employing a circular double-plate which is to be placed at the bottom of the spa. This unit will function as an open heat exchanger feeding district heating water into the spa. Free convection takes place at the upper side of the upper plate and forced convection below the upper plate. Heat transfer coefficient for both was calculated. Using results from calculations, temperature distribution at critical parts of spa and plate was modeled. Results are reasonable and promising for a good design that may considerably reduce the energy expenses for a continuously heated geothermal spa

Determination of biodegradation process of benzene, toluene, ethylbenzene and xylenes in seabed sediment by purge and trap gas chromatography

Energy Technology Data Exchange (ETDEWEB)

Han, Dongqiang [Key Lab. for Atomic and Molecular Nanosciences of Education Ministry, Tsinghua Univ., Beijing (China). Dept. of Physics; China Pharmaceutical Univ., Nanjing (China). Physics Teaching and Research Section, Dept. of Basic Sciences; Ma, Wanyun; Chen, Dieyan [Key Lab. for Atomic and Molecular Nanosciences of Education Ministry, Tsinghua Univ., Beijing (China). Dept. of Physics

2007-12-15

Benzene, toluene, ethylbenzene, and xylenes (BTEX) are commonly found in crude oil and are used in geochemical investigations as direct indicators of the presence of oil and gas. BTEX are easily volatile and can be degraded by microorganisms, which affect their precise measurement seriously. A method for determining the biodegradation process of BTEX in seabed sediment using dynamic headspace (purge and trap) gas chromatography with a photoionization detector (PID) was developed, which had a detection limit of 7.3-13.2 ng L{sup -1} and a recovery rate of 91.6-95.0%. The decrease in the concentration of BTEX components was monitored in seabed sediment samples, which was caused by microorganism biodegradation. The results of BTEX biodegradation process were of great significance in the collection, transportation, preservation, and measurement of seabed sediment samples in the geochemical investigations of oil and gas. (orig.)

Heat planning for fossil-fuel-free district heating areas with extensive end-use heat savings: A case study of the Copenhagen district heating area in Denmark

International Nuclear Information System (INIS)

Harrestrup, M.; Svendsen, S.

2014-01-01

The Danish government plans to make the Danish energy system to be completely free of fossil fuels by 2050 and that by 2035 the energy supply for buildings and electricity should be entirely based on renewable energy sources. To become independent from fossil fuels, it is necessary to reduce the energy consumption of the existing building stock, increase energy efficiency, and convert the present heat supply from fossil fuels to renewable energy sources. District heating is a sustainable way of providing space heating and domestic hot water to buildings in densely populated areas. This paper is a theoretical investigation of the district heating system in the Copenhagen area, in which heat conservation is related to the heat supply in buildings from an economic perspective. Supplying the existing building stock from low-temperature energy resources, e.g. geothermal heat, might lead to oversized heating plants that are too expensive to build in comparison with the potential energy savings in buildings. Long-term strategies for the existing building stock must ensure that costs are minimized and that investments in energy savings and new heating capacity are optimized and carried out at the right time. - Highlights: • We investigate how much heating consumption needs to be reduced in a district heating area. • We examine fossil-fuel-free supply vs. energy conservations in the building stock. • It is slightly cost-beneficial to invest in energy renovation from today for a societal point of view. • It is economically beneficial for district heating companies to invest in energy renovations from today. • The cost per delivered heat unit is lower when energy renovations are carried out from today

Metallurgical investigation of cracking of the isolation valve downstream piping of regenerative heat exchanger at beaver valley unit 1 station

International Nuclear Information System (INIS)

Rao, G.V.

1998-01-01

A metallurgical investigation was conducted to establish the mechanism and cause of cracking in the regenerative heat exchanger piping at Beaver Valley Unit 1 PWR station in the USA. The investigation, which was centered on an eight inch long pipe section containing the cracking included surface examinations, metallographic and fractographic examinations, and chemistry evaluations. The results of the examinations showed that there were two types of pipe degradation mechanisms that affected the type 304 stainless schedule 40 piping. These consisted of localized corrosive attack on the OD surface due to the presence of chlorides, sulphates and phosphates, and transgranular stress corrosion cracking in the pipe wall due to the presence of chloride contaminants. The overall results of the investigation showed that the introduction of contaminants from external sources other than pipe insulation was the cause of heat exchanger pipe cracking. (author)

Heat exchanger

Energy Technology Data Exchange (ETDEWEB)

Harada, F; Yanagida, T; Fujie, K; Futawatari, H

1975-04-30

The purpose of this construction is the improvement of heat transfer in finned tube heat exchangers, and therefore the improvement of its efficiency or its output per unit volume. This is achieved by preventing the formation of flow boundary layers in gaseous fluid. This effect always occurs on flow of smooth adjacent laminae, and especially if these have pipes carrying liquid passing through them; it worsens the heat transfer of such a boundary layer considerably compared to that in the turbulent range. The fins, which have several rows of heat exchange tubes passing through them, are fixed at a small spacing on theses tubes. The fins have slots cut in them by pressing or punching, where the pressed-out material remains as a web, which runs parallel to the level of the fin and at a small distance from it. These webs and slots are arranged radially around every tube hole, e.g. 6 in number. For a suitable small tube spacing, two adjacent tubes opposite each other have one common slot. Many variants of such slot arrangements are illustrated.

On-line purge-and-trap-gas chromatography with flame ionization detection as an alternative analytical method for dimethyl sulphide trace release from marine algae

Energy Technology Data Exchange (ETDEWEB)

Careri, M.; Musci, M.; Bianchi, F.; Mucchino, C. [Parma Univ., Parma (Italy). Dipt. di Chimica Generale ed Inorganica, Chimica Analitica e Chimica Fisica; Azzoni, R.; Viaroli, P. [Parma Univ., Parma (Italy). Dipt. di Scienze Ambientali

2001-10-01

The release of dimethyl sulphide (DMS) by the seaweed Ulva spp at trace level was studied in aqueous solutions at different salinities, temperature and light intensities. For this purpose, the purge-and-trap technique combined with gas chromatography-flame ionization detection was used. The analytical method was evaluated in terms of linearity range, limit of detection, precision and accuracy by considering 10% (w/v) and 30% (w/v) synthetic seawater as aqueous matrices. Calculation of the recovery function evidenced a matrix influence. The method of standard addition was then used for an accurate determination of DMS in synthetic seawater reproduction the matrix effect. DMS fluxes were analysed in batch cultures of Ulva spp reproducing the conditions which usually occur in the Sacca di Goro lagoon (Northern Adriatic Sea, Italy). [Italian] Il rilascio di dimetilsolfuro (DMS) in tracce da parte della macroalga Ulva spp e' stato studiato in soluzioni acquose di differente salinita' mediante la tecnica purge-and-trap accoppiata on-line alla gascromatografia con rivelazione a ionizzazione di fiamma (GC-FID). Il metodo analitico e' stato validato in termini di linearita' di risposta, di limite di rivelabilita', precisione e accuratezza considerando come matrice acqua di mare sintetica a diversa salinita' (10%0 m/v e 30%0 m/v). Il calcolo della funzione di recupero ha consentito di verificare la presenza di errori sistematici dovuti all'effetto matrice. Il metodo sviluppato e' stato quindi applicato a matrici ambientali allo scopo di verificare il rilascio di DMS da parte di Ulva spp, operando in condizioni ambientali simili a quelle che si verificano nella Sacca di Goro (Ferrara, Italia).

Malone-brayton cycle engine/heat pump

Science.gov (United States)

Gilmour, Thomas A.

1994-07-01

A machine, such as a heat pump, and having an all liquid heat exchange fluid, operates over a more nearly ideal thermodynamic cycle by adjustment of the proportionality of the volumetric capacities of a compressor and an expander to approximate the proportionality of the densities of the liquid heat exchange fluid at the chosen working pressures. Preferred forms of a unit including both the compressor and the expander on a common shaft employs difference in axial lengths of rotary pumps of the gear or vane type to achieve the adjustment of volumetric capacity. Adjustment of the heat pump system for differing heat sink conditions preferably employs variable compression ratio pumps.

LAS DEPURACIONES DE FUNCIONARIOS COMO ELEMENTO DE CONTROL POLÍTICO: EL CASO DE GUADALAJARA = THE PURGES OF CIVIL SERVANTS AS A POLITICAL WAY OF CONTROL: THE CASE OF GUADALAJARA

Directory of Open Access Journals (Sweden)

Juan Carlos Berlinches Balbacid

2015-04-01

Full Text Available Habitualmente cuando hablamos de represión franquista, solemos pensar en fusilamientos y penas de cárcel. Evidentemente la justicia franquista fue mucho más,  y quiso llegar también a las depuraciones laborales. Los que no estaban muertos o en prisión ahora tenían que hacer frente a la pérdida de su trabajo. Para conocer cómo funcionó toda esta maquinaria represiva, se han consultado los expedientes relacionados con la depuración de los funcionarios del ayuntamiento de Guadalajara y de la Diputación Provincial de Guadalajara. Partiendo de la ley que regulaba todo este proceso, se han analizado los casos relacionados con estas dos instituciones, estableciendo las partes que componían estos expedientes y el funcionamiento de ambos tribunales. Fruto de este análisis veremos como en algunos casos lo que hay es un cambio de “fichas”, funcionarios depurados en 1936 ahora recuperaban su puesto de trabajo, y otros que habían accedido al cargo en julio de 1936 ahora eran inhabilitados.Habitually, when we talk about Francoism repression we tend to think about firing squad executions and prison sentences. Obviously, Franco’s justice meant much more than that and intended to reach labour purges. Those who were not dead or in prison had to face their job loss now. To know how this repression machine worked, the records related to the civil servant purges have been consulted, both in the City Council and the County Council of Guadalajara. On the basis of the law that regulated this process, the cases related to these two institutions have been analysed, establishing the parts that formed these files and the functioning of both courts. Fruit of this analysis, it will be seen how in some cases there is a change of “cards”; purged civil servants in 1936 could recover their positions, while those who had taken on their post in July 1936 were now barred.

Experimental study on heat transfer performance of fin-tube exchanger and PSHE for waste heat recovery

Science.gov (United States)

Chen, Ting; Bae, Kyung Jin; Kwon, Oh Kyung

2018-02-01

In this paper, heat transfer characteristics of fin-tube heat exchanger and primary surface heat exchanger (PSHE) used in waste heat recovery were investigated experimentally. The flow in the fin-tube heat exchanger is cross flow and in PSHE counter flow. The variations of friction factor and Colburn j factor with air mass flow rate, and Nu number with Re number are presented. Various comparison methods are used to evaluate heat transfer performance, and the results show that the heat transfer rate of the PSHE is on average 17.3% larger than that of fin-tube heat exchanger when air mass flow rate is ranging from 1.24 to 3.45 kg/min. However, the PSHE causes higher pressure drop, and the fin-tube heat exchanger has a wider application range which leads to a 31.7% higher value of maximum heat transfer rate compared to that of the PSHE. Besides, under the same fan power per unit frontal surface, a higher heat transfer rate value is given in the fin-tube heat exchanger.

Cooling and Heating Season Impacts of Right-Sizing of Fixed- and Variable-Capacity Heat Pumps With Attic and Indoor Ductwork

Energy Technology Data Exchange (ETDEWEB)

Cummings, James [Building America Partnership for Improved Residential Construction, Cocoa, FL (United States); Withers, Charles [Building America Partnership for Improved Residential Construction, Cocoa, FL (United States); Kono, Jamie [Building America Partnership for Improved Residential Construction, Cocoa, FL (United States)

2015-06-24

A new generation of full variable-capacity air-conditioning (A/C) and heat pump units has come on the market that promises to deliver very high cooling and heating efficiency. The units are controlled differently than standard single-capacity (fixed-capacity) systems. Instead of cycling on at full capacity and cycling off when the thermostat is satisfied, the new units can vary their capacity over a wide range (approximately 40%–118% of nominal full capacity) and stay on for 60%–100% more hours per day than the fixed-capacity systems depending on load-to-capacity ratios. Two-stage systems were not evaluated in this research effort.

Possible uses of nuclear energy in central heating of Ankara

International Nuclear Information System (INIS)

Agirsoy, L.

1987-01-01

In this master thesis, a study was carried out for the district heating of the plateau region where the population and air pollution densities are the highest. First the heat requirements of differently populated regions were calculated, then by taking different temperature decreases of hot water in buildings; flow rates, pipe diameters and pressure losses corres-ponding to these temperature decreases were obtained. An optimum division of total heat load as peak and base loads was studied and it was seen that the unit heat cost could be lowered by employing two stations for the heating of buildings. The optimum division and unit heat cost calculations were carried out for various alternative heating systems and it was seen that nuclear combined cycle base-load station and a peak-load station operating on fuel-oil was obtained to be the most advantageous system from an economic point of view. (author)

Heat and Humidity in the City: Neighborhood Heat Index Variability in a Mid-Sized City in the Southeastern United States.

Science.gov (United States)

Hass, Alisa L; Ellis, Kelsey N; Reyes Mason, Lisa; Hathaway, Jon M; Howe, David A

2016-01-11

Daily weather conditions for an entire city are usually represented by a single weather station, often located at a nearby airport. This resolution of atmospheric data fails to recognize the microscale climatic variability associated with land use decisions across and within urban neighborhoods. This study uses heat index, a measure of the combined effects of temperature and humidity, to assess the variability of heat exposure from ten weather stations across four urban neighborhoods and two control locations (downtown and in a nearby nature center) in Knoxville, Tennessee, USA. Results suggest that trees may negate a portion of excess urban heat, but are also associated with greater humidity. As a result, the heat index of locations with more trees is significantly higher than downtown and areas with fewer trees. Trees may also reduce heat stress by shading individuals from incoming radiation, though this is not considered in this study. Greater amounts of impervious surfaces correspond with reduced evapotranspiration and greater runoff, in terms of overall mass balance, leading to a higher temperature, but lower relative humidity. Heat index and relative humidity were found to significantly vary between locations with different tree cover and neighborhood characteristics for the full study time period as well as for the top 10% of heat index days. This work demonstrates the need for high-resolution climate data and the use of additional measures beyond temperature to understand urban neighborhood exposure to extreme heat, and expresses the importance of considering vulnerability differences among residents when analyzing neighborhood-scale impacts.