WorldWideScience

Sample records for heat temperature radiant

  1. Effect of radiant heat transfer on the performance of high temperature heat exchanger

    International Nuclear Information System (INIS)

    Mori, Yasuo; Hijikata, Kunio; Yamada, Yukio

    1975-01-01

    The development of high temperature gas-cooled reactors is motivated by the consideration of the application of nuclear heat for industrial uses or direct steelmaking and chemical processes. For these purposes, reliable and efficient heat exchangers should be developed. This report analyzes the effect of radiant heat transfer on the performance of high temperature heat exchangers. The heat transfer model is as follows: the channel composed with two parallel adiabatic walls is divided with one parallel plate between the walls. Non-radiative fluid flows in the two separated channels in opposite direction. Heat transfer equations for this system were obtained, and these equations were solved by some approximate method and numerical analysis. The effect of radiation on heat transfer became larger as the radiant heat transfer between two walls was larger. In the heat exchangers of counter flow type, the thermal efficiency is controlled with three parameters, namely radiation-convection parameter, Stanton number and temperature difference. The thermal efficiency was larger with the increase of these parameters. (Iwase, T.)

  2. Radiometric measurements of wall temperatures in the 800 K to 1150 K range for a quartz radiant heating tube

    International Nuclear Information System (INIS)

    Blevins, L.G.; Sivathanu, Y.R.; Gore, J.P.; Shahien, M.A.

    1995-01-01

    Many industrial applications require heat transfer to a load in an inert environment, which can be achieved by using gas-fired radiant tubes. A radiant tube consists of a flame confined in a cylindrical metal or ceramic chamber. The flame heats the tube wall, which in turn radiates to the load. One important characteristic of radiant heating tubes is wall temperature uniformity. Numerical models of radiant tubes have been used to predict wall temperatures, but there is a lack of experimental data for validation. Recently, Namazian et al., Singh and Gorski, and Peters et al. have measured wall temperature profiles of radiant tubes using thermocouples. 13 refs., 3 figs

  3. High-temperature process heat reactor with solid coolant and radiant heat exchange

    International Nuclear Information System (INIS)

    Alekseev, A.M.; Bulkin, Yu.M.; Vasil'ev, S.I.

    1984-01-01

    The high temperature graphite reactor with the solid coolant in which heat transfer is realized by radiant heat exchange is described. Neutron-physical and thermal-technological features of the reactor are considered. The reactor vessel is made of sheet carbon steel in the form of a sealed rectangular annular box. The moderator is a set of graphite blocks mounted as rows of arched laying Between the moderator rows the solid coolant annular layings made of graphite blocks with high temperature nuclear fuel in the form of coated microparticles are placed. The coolant layings are mounted onto ring movable platforms, the continuous rotation of which is realizod by special electric drives. Each part of the graphite coolant laying consecutively passes through the reactor core neutron cut-off zones and technological zone. In the core the graphite is heated up to the temperature of 1350 deg C sufficient for effective radiant heat transfer. In the neutron cut-off zone the chain reaction and further graphite heating are stopped. In the technological zone the graphite transfers the accumulated heat to the walls of technological channels in which the working medium moves. The described reactor is supposed to be used in nuclear-chemical complex for ammonia production by the method of methane steam catalytic conversion

  4. The relationship between radiant heat, air temperature and thermal comfort at rest and exercise.

    Science.gov (United States)

    Guéritée, Julien; Tipton, Michael J

    2015-02-01

    The aims of the present work were to investigate the relationships between radiant heat load, air velocity and body temperatures with or without coincidental exercise to determine the physiological mechanisms that drive thermal comfort and thermoregulatory behaviour. Seven male volunteers wearing swimming trunks in 18°C, 22°C or 26°C air were exposed to increasing air velocities up to 3 m s(-1) and self-adjusted the intensity of the direct radiant heat received on the front of the body to just maintain overall thermal comfort, at rest or when cycling (60 W, 60 rpm). During the 30 min of the experiments, skin and rectal temperatures were continuously recorded. We hypothesized that mean body temperature should be maintained stable and the intensity of the radiant heat and the mean skin temperatures would be lower when cycling. In all conditions, mean body temperature was lower when facing winds of 3 m s(-1) than during the first 5 min, without wind. When facing winds, in all but the 26°C air, the radiant heat was statistically higher at rest than when exercising. In 26°C air mean skin temperature was lower at rest than when exercising. No other significant difference was observed. In all air temperatures, high correlation coefficients were observed between the air velocity and the radiant heat load. Other factors that we did not measure may have contributed to the constant overall thermal comfort status despite dropping mean skin and body temperatures. It is suggested that the allowance to behaviourally adjust the thermal environment increases the tolerance of cold discomfort. Copyright © 2014 Elsevier Inc. All rights reserved.

  5. Newborns' temperature submitted to radiant heat and to the Top Maternal device at birth.

    Science.gov (United States)

    Albuquerque, Rosemeire Sartori de; Mariani, Corintio; Bersusa, Ana Aparecida Sanches; Dias, Vanessa Macedo; Silva, Maria Izabel Mota da

    2016-08-08

    to compare the axillar temperatures of newborns that are put immediately after birth in skin-to-skin contact under the Top Maternal device, as compared to those in a radiant heat crib. comparatives observational study of the case-control type about temperature of 60 babies born at the Obstetric Center and Normal Delivery Center of a public hospital of the municipality of Sao Paulo, being them: 29 receiving assistance in heated crib and 31 in skin-to skin contact, shielded by a cotton tissue placed on mother's thorax, called Top Maternal. the temperature of the babies of the skin-to-skin contact group presented higher values in a larger share of the time measures verified, as compared to those that were placed in radiant heat crib, independently from the place of birth. Differences between the two groups were not statistically significant. the study contributes to generate new knowledge, supporting the idea of keeping babies with their mothers immediately after birth protected with the Maternal Top, without harming their wellbeing, as it keeps the axillar temperature in recommendable levels. comparar a temperatura axilar dos recém-nascidos acomodados - imediatamente após o nascimento - em contato pele a pele, sob o Top Maternal, em berço de calor radiante. estudo comparativo observacional do tipo Caso-Controle sobre a temperatura de 60 bebês nascidos no Centro Obstétrico e Centro de Parto Normal de um hospital público do município de São Paulo, sendo: 29 assistidos em berço aquecido e 31 em contato pele a pele, protegidos por uma malha de algodão colocada sobre o tórax da mãe, denominada Top Maternal. a temperatura dos bebês do grupo de contato pele a pele teve maior valor na maioria dos tempos verificados comparada à dos que foram colocados em berço de calor radiante, independentemente do local de nascimento. A diferença entre os grupos não foi estatisticamente significante. o estudo contribui com a geração de um novo conhecimento que sustenta a

  6. Estimation of Surface Temperature and Heat Flux by Inverse Heat Transfer Methods Using Internal Temperatures Measured While Radiantly Heating a Carbon/Carbon Specimen up to 1920 F

    Science.gov (United States)

    Pizzo, Michelle; Daryabeigi, Kamran; Glass, David

    2015-01-01

    The ability to solve the heat conduction equation is needed when designing materials to be used on vehicles exposed to extremely high temperatures; e.g. vehicles used for atmospheric entry or hypersonic flight. When using test and flight data, computational methods such as finite difference schemes may be used to solve for both the direct heat conduction problem, i.e., solving between internal temperature measurements, and the inverse heat conduction problem, i.e., using the direct solution to march forward in space to the surface of the material to estimate both surface temperature and heat flux. The completed research first discusses the methods used in developing a computational code to solve both the direct and inverse heat transfer problems using one dimensional, centered, implicit finite volume schemes and one dimensional, centered, explicit space marching techniques. The developed code assumed the boundary conditions to be specified time varying temperatures and also considered temperature dependent thermal properties. The completed research then discusses the results of analyzing temperature data measured while radiantly heating a carbon/carbon specimen up to 1920 F. The temperature was measured using thermocouple (TC) plugs (small carbon/carbon material specimens) with four embedded TC plugs inserted into the larger carbon/carbon specimen. The purpose of analyzing the test data was to estimate the surface heat flux and temperature values from the internal temperature measurements using direct and inverse heat transfer methods, thus aiding in the thermal and structural design and analysis of high temperature vehicles.

  7. Mapping temperature and radiant geothermal heat flux anomalies in the Yellowstone geothermal system using ASTER thermal infrared data

    Science.gov (United States)

    Vaughan, R. Greg; Lowenstern, Jacob B.; Keszthelyi, Laszlo P.; Jaworowski, Cheryl; Heasler, Henry

    2012-01-01

    The purpose of this work was to use satellite-based thermal infrared (TIR) remote sensing data to measure, map, and monitor geothermal activity within the Yellowstone geothermal area to help meet the missions of both the U.S. Geological Survey Yellowstone Volcano Observatory and the Yellowstone National Park Geology Program. Specifically, the goals were to: 1) address the challenges of remotely characterizing the spatially and temporally dynamic thermal features in Yellowstone by using nighttime TIR data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and 2) estimate the temperature, geothermal radiant emittance, and radiant geothermal heat flux (GHF) for Yellowstone’s thermal areas (both Park wide and for individual thermal areas). ASTER TIR data (90-m pixels) acquired at night during January and February, 2010, were used to estimate surface temperature, radiant emittance, and radiant GHF from all of Yellowstone’s thermal features, produce thermal anomaly maps, and update field-based maps of thermal areas. A background subtraction technique was used to isolate the geothermal component of TIR radiance from thermal radiance due to insolation. A lower limit for the Yellowstone’s total radiant GHF was established at ~2.0 GW, which is ~30-45% of the heat flux estimated through geochemical (Cl-flux) methods. Additionally, about 5 km2 was added to the geodatabase of mapped thermal areas. This work provides a framework for future satellite-based thermal monitoring at Yellowstone as well as exploration of other volcanic / geothermal systems on a global scale.

  8. Indoor temperatures for calculating room heat loss and heating capacity of radiant heating systems combined with mechanical ventilation systems

    DEFF Research Database (Denmark)

    Wu, Xiaozhou; Olesen, Bjarne W.; Fang, Lei

    2016-01-01

    change rates on the indoor temperatures were performed using the proposed model. When heated surface temperatures and air change rates were from 21.0 to 29.0 degrees C and from 0.5 to 4.0 h-1, the indoor temperatures for calculating the transmission heat loss and ventilation heat loss were between 20...

  9. Radiant Heating and Cooling Systems. Part one

    DEFF Research Database (Denmark)

    Kim, Kwan Woo; Olesen, Bjarne W.

    2015-01-01

    The use of radiant heating systems has several thousand years of history.1,2 The early stage of radiant system application was for heating purposes, where hot air from flue gas (cooking, fires) was circulated under floors or in walls. After the introduction of plastic piping water-based radiant...

  10. Electric radiant heating : a hot profitable idea

    Energy Technology Data Exchange (ETDEWEB)

    Lemieux, G. [Britech Corp., Toronto, ON (Canada)

    2006-09-15

    Due to the high cost of heating oil, natural gas and propane, floor mounted radiant heating systems are now proving to be a cost effective method of heating homes. The systems provide evenly distributed heat across the entire floor area. Unlike hydronic floor systems, radiant floor systems require no maintenance, and are easy to control because no mechanical rooms or boilers are required. The system is comprised of a series of resistant heating cables, a thermostat, and a solid state relay. The cables are installed in a poured concrete pad. Separate temperature control devices are used to heat individual areas of floorspace. Building automation systems can also control the heating system by using simple ambient air- and floor-mounted sensors in conjunction with relays to energize the heating cables. The cost of thermostats and heating cables to heat a standard 2000 square foot home are estimated at $9000.00, with an additional 64 hours of installation costs. It was noted that the systems may prove to be less costly in the long-term than hydronic systems, which require additional boilers, pumps and water treatments. Electric radiant heating can be an even more cost-effective application when used with thermal storage heating applications that use lower-cost off-peak electricity to generate and store heat in concrete floor slabs or ceramic bricks contained in insulated cabinets. It was concluded that radiant heating systems are a viable and cost-effective alternative to expensive hydronic systems, which are costly to install and maintain. 4 figs.

  11. Radiant heating of petroleum reservoirs; Aquecimento radiante de reservatorios petroliferos

    Energy Technology Data Exchange (ETDEWEB)

    Sidrim, Fernando A.C.

    1990-12-31

    This work presents a proposal of a simplified model for the enhanced oil recovery process through radiant heating of oil reservoirs. The resulting continuity, energy and motion equations were solved analytically for the prediction of the increase in well flow rates. The heat loss to adjacent formations and the necessary for the establishment of the temperature profile,which are transient terms of energy equation, have been neglected. Also, no temperature gradient in the axial direction has been modelled as a cylindrical wave propagating in a loss medium. It is concluded that: the inclusion of a radial conduction term in the energy equation led to higher flow rates than the ones predicted by the literature existing solution; if the absorption coefficient is too large, it is profitable to dry the reservoir around the well bore; the transient terms in the energy equation are significant for extended periods of well production. 47 refs., 18 figs., 4 tabs.

  12. Integrated thermal infrared imaging and Structure-from-Motion photogrametry to map apparent temperature and radiant hydrothermal heat flux at Mammoth Mountain, CA USA

    Science.gov (United States)

    Lewis, Aaron; George Hilley,; Lewicki, Jennifer L.

    2015-01-01

    This work presents a method to create high-resolution (cm-scale) orthorectified and georeferenced maps of apparent surface temperature and radiant hydrothermal heat flux and estimate the radiant hydrothermal heat emission rate from a study area. A ground-based thermal infrared (TIR) camera was used to collect (1) a set of overlapping and offset visible imagery around the study area during the daytime and (2) time series of co-located visible and TIR imagery at one or more sites within the study area from pre-dawn to daytime. Daytime visible imagery was processed using the Structure-from-Motion photogrammetric method to create a digital elevation model onto which pre-dawn TIR imagery was orthorectified and georeferenced. Three-dimensional maps of apparent surface temperature and radiant hydrothermal heat flux were then visualized and analyzed from various computer platforms (e.g., Google Earth, ArcGIS). We demonstrate this method at the Mammoth Mountain fumarole area on Mammoth Mountain, CA. Time-averaged apparent surface temperatures and radiant hydrothermal heat fluxes were observed up to 73.7 oC and 450 W m-2, respectively, while the estimated radiant hydrothermal heat emission rate from the area was 1.54 kW. Results should provide a basis for monitoring potential volcanic unrest and mitigating hydrothermal heat-related hazards on the volcano.

  13. Error analysis of thermocouple measurements in the Radiant Heat Facility

    International Nuclear Information System (INIS)

    Nakos, J.T.; Strait, B.G.

    1980-12-01

    The measurement most frequently made in the Radiant Heat Facility is temperature, and the transducer which is used almost exclusively is the thermocouple. Other methods, such as resistance thermometers and thermistors, are used but very rarely. Since a majority of the information gathered at Radiant Heat is from thermocouples, a reasonable measure of the quality of the measurements made at the facility is the accuracy of the thermocouple temperature data

  14. Radiant Heat Transfer in Reusable Surface Insulation

    Science.gov (United States)

    Hughes, T. A.; Linford, R. M. F.; Chmitt, R. J.; Christensen, H. E.

    1973-01-01

    During radiant testing of mullite panels, temperatures in the insulation and support structure exceeded those predicted on the basis of guarded hot plate thermal conductivity tests. Similar results were obtained during arc tunnel tests of mullite specimens. The differences between effective conductivity and guarded hot plate values suggested that radiant transfer through the mullite was occurring. To study the radiant transport, measurements were made of the infrared transmission through various insulating materials and fibers of interest to the shuttle program, using black body sources over the range of 780 to 2000 K. Experimental data were analyzed and scattering coefficients were derived for a variety of materials, fiber diameters, and source temperature.

  15. Influence of radiant heating treatments on fusion of high-temperature superconducting yttrium ceramics

    International Nuclear Information System (INIS)

    Bitenbaev, M.I.; Polyakov, A.I.

    1999-01-01

    Regardless of the fact that the materials made of HTSC-ceramics are promising, there is no any information about their successful practical application in publications. To our opinion, it is explained by the fact, first of all, that the conservative technologies of the powder metallurgy do not allow producing HTSC systems with excellent operating performance (structure homogeneity, long-term stability of Sc properties and etc.). This report presents outcomes of experiments on fusion of yttrium ceramics containing raw components irradiated by g-rays 60 Co under the temperature exceeding 500 degrees C. HTSC properties of ceramics were studied according to their differential spectra of radio-frequency (RF) field absorption. The RF absorption spectrum of yttrium ceramics samples produced according to conservative technology is sufficiently permitted triplet with the Sc transition temperatures range of 80 K, 90 K, 95 K. Irradiation under the increased temperatures and mechanical limitation allow producing samples of yttrium HTSC-ceramics with sufficient homogeneous structure and superconducting properties that are stable to air conditions for not less than one year

  16. Radiant zone heated particulate filter

    Science.gov (United States)

    Gonze, Eugene V [Pinckney, MI

    2011-12-27

    A system includes a particulate matter (PM) filter including an upstream end for receiving exhaust gas and a downstream end. A radiant zoned heater includes N zones, where N is an integer greater than one, wherein each of the N zones includes M sub-zones, where M is an integer greater than or equal to one. A control module selectively activates at least a selected one of the N zones to initiate regeneration in downstream portions of the PM filter from the one of the N zones, restricts exhaust gas flow in a portion of the PM filter that corresponds to the selected one of the N zones, and deactivates non-selected ones of the N zones.

  17. Performance of Radiant Heating Systems of Low-Energy Buildings

    Science.gov (United States)

    Sarbu, Ioan; Mirza, Matei; Crasmareanu, Emanuel

    2017-10-01

    After the introduction of plastic piping, the application of water-based radiant heating with pipes embedded in room surfaces (i.e., floors, walls, and ceilings), has significantly increased worldwide. Additionally, interest and growth in radiant heating and cooling systems have increased in recent years because they have been demonstrated to be energy efficient in comparison to all-air distribution systems. This paper briefly describes the heat distribution systems in buildings, focusing on the radiant panels (floor, wall, ceiling, and floor-ceiling). Main objective of this study is the performance investigation of different types of low-temperature heating systems with different methods. Additionally, a comparative analysis of the energy, environmental, and economic performances of floor, wall, ceiling, and floor-ceiling heating using numerical simulation with Transient Systems Simulation (TRNSYS) software is performed. This study showed that the floor-ceiling heating system has the best performance in terms of the lowest energy consumption, operation cost, CO2 emission, and the nominal boiler power. The comparison of the room operative air temperatures and the set-point operative air temperature indicates also that all radiant panel systems provide satisfactory results without significant deviations.

  18. 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.

  19. Interaction of chemical reactions and radiant heat transfer with temperature turbulent pulsations and its effect on heat traner in high-temperature gas flows

    International Nuclear Information System (INIS)

    Petukhov, B.S.; Zal'tsman, I.G.; Shikov, V.K.

    1980-01-01

    Methods of taking account of mutual effect of chemical transformations, radiation and turbulence in the calculations of heat transfer in gas flows are considered. Exponential functions of medium parameters are used to describe chemical sources and optical properties of media. It is shown using as an example the dissociation reaction C 2 reversible 2C that the effect of temperature and composition pulsations on recombination rates is negligibly small. It is also shown on the example of turbulent flow of hot molecular gas in a flat channel with cold walls that at moderate temperatures the effect of temperature pulsations on heat radiation flow can be significant (30-40%). The calculational results also show that there is a region in a turbulent boundary layer where the radiation greatly affects the coefficient of turbulent heat transfer

  20. Electric radiant heating or, why are plumbers getting our work?

    Energy Technology Data Exchange (ETDEWEB)

    Lemieux, G. [Britech, Toronto, ON (Canada)

    2009-02-15

    Electric radiant heating (ERH) technologies are now being installed in floors as a means of reducing heating costs. The radiant installations have seen a large increase in sales over the last decade, and are now being used in commercial applications. Sales of hydronic ERH systems have increased by 24 per cent over the last year. ERH systems are energy efficient and do not cause drafts. The systems consist of resistant heating cables installed within the floors of a room. The cables are supplied as loose cables and tracks with predetermined spacings or rugged, heavier cable that can be stapled onto wooden subfloors. Program temperature setbacks can be applied on a room-by-room basis. Electric thermal storage systems allow building owners to store heat in the floors and are ideal for use in combination with time-of-use electric metering. Some electric utilities are now promoting the use of electric thermal storage in order to reduce demand during peak times. Thermostats used with the systems should have floor sensors and ambient air sensors to control space heating in conjunction with the floor sensor. It was concluded that electrical contractors who gain knowledge in the application and installation of the systems will tap into a growing revenue stream. 5 figs.

  1. Electric radiant heating or, why are plumbers getting our work?

    International Nuclear Information System (INIS)

    Lemieux, G.

    2009-01-01

    Electric radiant heating (ERH) technologies are now being installed in floors as a means of reducing heating costs. The radiant installations have seen a large increase in sales over the last decade, and are now being used in commercial applications. Sales of hydronic ERH systems have increased by 24 per cent over the last year. ERH systems are energy efficient and do not cause drafts. The systems consist of resistant heating cables installed within the floors of a room. The cables are supplied as loose cables and tracks with predetermined spacings or rugged, heavier cable that can be stapled onto wooden subfloors. Program temperature setbacks can be applied on a room-by-room basis. Electric thermal storage systems allow building owners to store heat in the floors and are ideal for use in combination with time-of-use electric metering. Some electric utilities are now promoting the use of electric thermal storage in order to reduce demand during peak times. Thermostats used with the systems should have floor sensors and ambient air sensors to control space heating in conjunction with the floor sensor. It was concluded that electrical contractors who gain knowledge in the application and installation of the systems will tap into a growing revenue stream. 5 figs

  2. Performance analysis on solar-water compound source heat pump for radiant floor heating system

    Institute of Scientific and Technical Information of China (English)

    曲世林; 马飞; 仇安兵

    2009-01-01

    A solar-water compound source heat pump for radiant floor heating (SWHP-RFH) experimental system was introduced and analyzed. The SWHP-RFH system mainly consists of 11.44 m2 vacuum tube solar collector,1 000 L water tank assisted 3 kW electrical heater,a water source heat pump,the radiant floor heating system with cross-linked polyethylene (PE-X) of diameter 20 mm,temperature controller and solar testing system. The SWHP-RFH system was tested from December to February during the heating season in Beijing,China under different operation situations. The test parameters include the outdoor air temperature,solar radiation intensity,indoor air temperature,radiation floor average surface temperature,average surface temperature of the building envelope,the inlet and outlet temperatures of solar collector,the temperature of water tank,the heat medium temperatures of heat pump condenser side and evaporator side,and the power consumption includes the water source heat pump system,the solar source heat pump system,the auxiliary heater and the radiant floor heating systems etc. The experimental results were used to calculate the collector efficiency,heat pump dynamic coefficient of performance (COP),total energy consumption and seasonal heating performance during the heating season. The results indicate that the performance of the compound source heat pump system is better than that of the air source heat pump system. Furthermore,some methods are suggested to improve the thermal performance of each component and the whole SWHP-RFH system.

  3. Radiant Heating and Cooling Systems. Part two

    DEFF Research Database (Denmark)

    Kim, Kwan Woo; Olesen, Bjarne W.

    2015-01-01

    Control of the heating and cooling system needs to be able to maintain the indoor temperatures within the comfort range under the varying internal loads and external climates. To maintain a stable thermal environment, the control system needs to maintain the balance between the heat gain...

  4. Differences in the heat stress associated with white sportswear and being semi-nude in exercising humans under conditions of radiant heat and wind at a wet bulb globe temperature of greater than 28 °C.

    Science.gov (United States)

    Tsuji, Michio; Kume, Masashi; Tuneoka, Hideyuki; Yoshida, Tetsuya

    2014-08-01

    This study investigated whether wearing common white sportswear can reduce heat stress more than being semi-nude during exercise of different intensities performed under radiant heat and wind conditions, such as a hot summer day. After a 20-min rest period, eight male subjects performed three 20 min sessions of cycling exercise at a load intensity of 20 % or 50 % of their peak oxygen uptake (VO2peak) in a room maintained at a wet bulb globe temperature (WBGT) of 28.7 ± 0.1 °C using two spot lights and a fan (0.8 m/s airflow). Subjects wore common white sportswear (WS) consisting of a long-sleeved shirt (45 % cotton and 55 % polyester) and short pants (100 % polyester), or only swimming pants (SP) under the semi-nude condition. The mean skin temperature (Tsk) was greater when subjects wore SP than WS under both the 20 % and 50 % exercise conditions. During the 50 % exercise, the rating of perceived exertion (RPE) and thermal sensation (TS), and the increases in esophageal temperature (ΔTes) and heart rate were significantly higher (Pheat storage (S), calculated from the changes in the mean body temperature (0.9Tes + 0.1 Tsk), was significantly lower in the WS trials than in the SP trials during the 20 min resting period before exercise session. However, S was similar between conditions during the 20 % exercise, but was greater in the WS than in the SP trials during 50 % exercise. These results suggest that, under conditions of radiant heat and wind at a WBGT greater than 28 °C, the heat stress associated with wearing common WS is similar to that of being semi-nude during light exercise, but was greater during moderate exercise, and the storage of body heat can be reduced by wearing WS during rest periods.

  5. Experimental evaluation of heat transfer coefficients between radiant ceiling and room

    DEFF Research Database (Denmark)

    Causone, Francesco; Corgnati, Stefano P.; Filippi, Marco

    2009-01-01

    The heat transfer coefficients between radiant surfaces and room are influenced by several parameters: surfaces temperature distributions, internal gains, air movements. The aim of this paper is to evaluate the heat transfer coefficients between radiant ceiling and room in typical conditions...... of occupancy of an office or residential building. Internal gains were therefore simulated using heated cylinders and heat losses using cooled surfaces. Evaluations were developed by means of experimental tests in an environmental chamber. Heat transfer coefficient may be expressed separately for radiation...

  6. Effect of supply air temperature on air distribution in a room with radiant heating and mechanical ventilation

    DEFF Research Database (Denmark)

    Wu, Xiaozhou; Zhao, Jianing; Fang, Lei

    2017-01-01

    and the horizontal distribution of containment concentration in the breathing zone were measured as the supply air temperature ranged from 15.0°C (59°F)to 19.0°C (66.2°F). The results showed that the vertical air temperature differences were less than 0.3°C (32.5°F) with FH+MV or CH+MV and between 1.9°C (35.4°F...

  7. Operative temperature drifts and occupant satisfaction with thermal environment in three office buildings using radiant heating/ cooling system

    DEFF Research Database (Denmark)

    Kolarik, Jakub; Toftum, Jørn; Olesen, Bjarne W.

    2015-01-01

    , Madrid, Spain (16000 m2), TiFS, Padua, Italy (2200 m2). Continuous measurements of operative temperature were conducted at four workplaces in each building for one year. Occupants’ satisfaction was assessed by internet based questionnaire. Results showed that mostly exceeded limits were those for 4-hour...

  8. Control characteristics and heating performance analysis of automatic thermostatic valves for radiant slab heating system in residential apartments

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Byung-Cheon [Department of Building Equipment System Engineering, Kyungwon University, Seongnam City (Korea); Song, Jae-Yeob [Graduate School, Building Equipment System Engineering, Kyungwon University, Seongnam City (Korea)

    2010-04-15

    Computer simulations and experiments are carried out to research the control characteristics and heating performances for a radiant slab heating system with automatic thermostatic valves in residential apartments. An electrical equivalent R-C circuit is applied to analyze the unsteady heat transfer in the house. In addition, the radiant heat transfer between slabs, ceilings and walls in the room is evaluated by enclosure analysis method. Results of heating performance and control characteristics were determined from control methods such as automatic thermostatic valves, room air temperature-sensing method, water-temperature-sensing method, proportional control method, and On-Off control method. (author)

  9. Dynamic heat transfer modeling and parametric study of thermoelectric radiant cooling and heating panel system

    International Nuclear Information System (INIS)

    Luo, Yongqiang; Zhang, Ling; Liu, Zhongbing; Wang, Yingzi; Wu, Jing; Wang, Xiliang

    2016-01-01

    Highlights: • Dynamic model of thermoelectric radiant panel system is established. • The internal parameters of thermoelectric module are dynamically calculated in simulation. • Both artificial neural networks model and system model are verified through experiment data. • Optimized system structure is obtained through parametric study. - Abstract: Radiant panel system can optimize indoor thermal comfort with lower energy consumption. The thermoelectric radiant panel (TERP) system is a new and effective prototype of radiant system using thermoelectric module (TEM) instead of conventional water pipes, as heat source. The TERP can realize more stable and easier system control as well as lower initial and operative cost. In this study, an improved system dynamic model was established by combining analytical system model and artificial neural networks (ANN) as well as the dynamic calculation functions of internal parameters of TEM. The double integral was used for the calculation of surface average temperature of TERP. The ANN model and system model were in good agreement with experiment data in both cooling and heating mode. In order to optimize the system design structure, parametric study was conducted in terms of the thickness of aluminum panel and insulation, as well as the arrangement of TEMs on the surface of radiant panel. It was found through simulation results that the optimum thickness of aluminum panel and insulation are respectively around 1–2 mm and 40–50 mm. In addition, TEMs should be uniformly installed on the surface of radiant panel and each TEM should stand at the central position of a square-shaped typical region with length around 0.387–0.548 m.

  10. Integrated application of combined cooling, heating and power poly-generation PV radiant panel system of zero energy buildings

    Science.gov (United States)

    Yin, Baoquan

    2018-02-01

    A new type of combined cooling, heating and power of photovoltaic radiant panel (PV/R) module was proposed, and applied in the zero energy buildings in this paper. The energy system of this building is composed of PV/R module, low temperature difference terminal, energy storage, multi-source heat pump, energy balance control system. Radiant panel is attached on the backside of the PV module for cooling the PV, which is called PV/R module. During the daytime, the PV module was cooled down with the radiant panel, as the temperature coefficient influence, the power efficiency was increased by 8% to 14%, the radiant panel solar heat collecting efficiency was about 45%. Through the nocturnal radiant cooling, the PV/R cooling capacity could be 50 W/m2. For the multifunction energy device, the system shows the versatility during the heating, cooling and power used of building utilization all year round.

  11. Differences in the heat stress associated with white sportswear and being semi-nude in exercising humans under conditions of radiant heat and wind at a wet bulb globe temperature of greater than 28 °C

    Science.gov (United States)

    Tsuji, Michio; Kume, Masashi; Tuneoka, Hideyuki; Yoshida, Tetsuya

    2014-08-01

    This study investigated whether wearing common white sportswear can reduce heat stress more than being semi-nude during exercise of different intensities performed under radiant heat and wind conditions, such as a hot summer day. After a 20-min rest period, eight male subjects performed three 20 min sessions of cycling exercise at a load intensity of 20 % or 50 % of their peak oxygen uptake (VO2peak) in a room maintained at a wet bulb globe temperature (WBGT) of 28.7 ± 0.1 °C using two spot lights and a fan (0.8 m/s airflow). Subjects wore common white sportswear (WS) consisting of a long-sleeved shirt (45 % cotton and 55 % polyester) and short pants (100 % polyester), or only swimming pants (SP) under the semi-nude condition. The mean skin temperature was greater when subjects wore SP than WS under both the 20 % and 50 % exercise conditions. During the 50 % exercise, the rating of perceived exertion (RPE) and thermal sensation (TS), and the increases in esophageal temperature (ΔTes) and heart rate were significantly higher ( P < 0.001-0.05), or tended to be higher ( P < 0.07), in the WS than SP trials at the end of the third 20-min exercise session. The total sweat loss ( m sw,tot) was also significantly higher in the WS than in the SP trials ( P < 0.05). However, during the 20 % exercise, the m sw,tot during exercise, and the ΔTes, RPE and TS at the end of the second and third sessions of exercise did not differ significant between conditions. The heat storage (S), calculated from the changes in the mean body temperature (0.9Tes + 0.1 ), was significantly lower in the WS trials than in the SP trials during the 20 min resting period before exercise session. However, S was similar between conditions during the 20 % exercise, but was greater in the WS than in the SP trials during 50 % exercise. These results suggest that, under conditions of radiant heat and wind at a WBGT greater than 28 °C, the heat stress associated with wearing common WS is similar to that

  12. Numerical Model and Experimental Analysis of the Thermal Behavior of Electric Radiant Heating Panels

    Directory of Open Access Journals (Sweden)

    Giovanni Ferrarini

    2018-01-01

    Full Text Available Electric radiant heating panels are frequently selected during the design phase of residential and industrial heating systems, especially for retrofit of existing buildings, as an alternative to other common heating systems, such as radiators or air conditioners. The possibility of saving living and working space and the ease of installation are the main advantages of electric radiant solutions. This paper investigates the thermal performance of a typical electric radiant panel. A climatic room was equipped with temperature sensors and heat flow meters to perform a steady state experimental analysis. For the dynamic behavior, a mathematical model was created and compared to a thermographic measurement procedure. The results showed for the steady state an efficiency of energy transformation close to one, while in a transient thermal regime the time constant to reach the steady state condition was slightly faster than the typical ones of hydronic systems.

  13. Radiant heat exchange measurements for Tore Supra

    International Nuclear Information System (INIS)

    Chatain, D.; Disdier, F.; Gauthier, A.; Raffin, M.; Renaud, M.

    1984-03-01

    In order to minimize the energy consumption of the low temperature cryogenic system connected to the superconducting magnet of TORE-SUPRA, heat exchange from thermal radiation between the vacuum vessels and the thermal shields has been studied. Accordingly large scale cold and hot walls of T.S. have been simulated in a model with reduced dimensions. In this model, the experiment consists in the measurement of the thermal radiated power between two concentric cylindrical surfaces of stainless steel under vacuum conditions. The temperature of the external cylinder was kept constant at 80 K. The internal cylinder was bakeable up to 250 0 C. Various surface treatments were applied on the two cylinders (mechanical polishing and metal deposition of Al, Ag, Ni) [fr

  14. Radiant heat loss, an unexploited path for heat stress reduction in shaded cattle.

    Science.gov (United States)

    Berman, A; Horovitz, T

    2012-06-01

    Reducing thermal radiation on shaded animals reduces heat stress independently of other means of stress relief. Radiant heat exchange was estimated as a function of climate, shade structure, and animal density. Body surface portion exposed to radiant sources in shaded environments was determined by geometrical relations to determine angles of view of radiation sources (roof underside, sky, sun-exposed ground, shaded ground) on the animal's surface. The relative representation of environment radiation sources on the body surface was determined. Animal thermal radiation balance was derived from radiant heat gained from radiation sources (including surrounding animals) and that lost from the animal surface. The animal environment was assumed to have different shade dimensions and temperatures. These were summed to the radiant heat balance of the cow. The data formed served to estimate the effect of changes in intensity of radiation sources, roof and shaded surface dimensions, and animal density on radiant heat balance (Rbal) of cattle. Roof height effect was expressed by effect of roof temperature on Rbal. Roof underside temperature (35 to 75°C) effect on Rbal was reduced by roof height. If roof height were 4m, an increase in its underside temperature from 35 to 75°C would increase mean Rbal from -63 to -2 W·m⁻², whereas if roof height were 10 m, Rbal would only increase from -99 to -88 W·m⁻². A hot ground temperature increase from 35 to 65°C reduced mean Rbal heat loss from -45 to 3 W·m⁻². Increasing the surface of the shaded area had only a minor effect on Rbal and on the effect of hot ground on Rbal. Increasing shade roof height reduced the effect of roof temperature on Rbal to minor levels when height was > 8m. Increasing the roof height from 4 to 10 m decreased Rbal from -32 to -94 W·m⁻². Increasing indirect radiation from 100 to 500 W·m⁻² was associated with an increase in Rbal from -135 to +23 W·m⁻². Their combined effects were lower

  15. Electric radiant heating: A hot item in home comfort

    Energy Technology Data Exchange (ETDEWEB)

    Lemieux, G. [Britech Corp., Toronto, ON (Canada)

    2003-12-01

    Electric radiant heating as a floor warming system and its growing popularity in home comfort are discussed. Price can be as low as $2.00 per square foot; cost of operation may be as little as 30 cents per square foot per year, depending on time of use and local hydro rates. The use of radiant cable heating is said to have surged in popularity; it provides the same warmth and comfort as more expensive hydronic systems. Radiant cable is simple and inexpensive to install since unlike hydronic systems, it requires no complicated mechanical system with boiler, heat exchanger, valves, pumps and extensive controls. Nevertheless, prospective end users are warned to make sure that the cable is sturdy, tough, has multiple layers of protection with a thick grounding system and conductor core. In addition to heating floors, electric heating cables can also be used for snow and ice control and for melting in driveways and gutters. In these type of installations heavy duty cables are used which are installed under asphalt, concrete or interlocking stones. Thirty watts per square foot per hour is the typical requirement for melting snow and ice. Based on average electricity prices in Ontario, melting snow on an 800 square foot driveway would cost about $2.20 per hour. Assuming five hours for the system to clear the driveway, installing a heating system under the driveway could be an economically viable solution for the home owner, providing freedom from ice, the inconvenience of shovelling snow, and saving time and money.

  16. Radiant heating tests of several liquid metal heat-pipe sandwich panels

    International Nuclear Information System (INIS)

    Camarda, C.J.; Basiulis, A.

    1983-08-01

    Integral heat pipe sandwich panels, which synergistically combine the thermal efficiency of heat pipes and the structural efficiency of honeycomb sandwich construction, were conceived as a means of alleviating thermal stress problems in the Langley Scramjet Engine. Test panels which utilized two different wickable honeycomb cores, facesheets with screen mesh sintered to the internal surfaces, and a liquid metal working fluid (either sodium or potassium) were tested by radiant heating at various heat load levels. The heat pipe panels reduced maximum temperature differences by 31 percent with sodium working fluid and 45 percent with potassium working fluid. Results indicate that a heat pipe sandwich panel is a potential, simple solution to the engine thermal stress problem. Other interesting applications of the concept include: cold plates for electronic component and circuit card cooling, radiators for large space platforms, low distortion large area structures (e.g., space antennas) and laser mirrors

  17. Perceived air quality, thermal comfort, and SBS symptoms at low air temperature and increased radiant temperature

    DEFF Research Database (Denmark)

    Toftum, Jørn; Reimann, Gregers Peter; Foldbjerg, P.

    2002-01-01

    source present at the low temperature. To maintain overall thermal neutrality, the low air temperature was partly compensated for by individually controlled radiant heating, and partly by allowing subjects to modify clothing insulation. A reduction of the air temperature from 23 deg.C to 18 deg.......C suggested an improvement of the perceived air quality, while no systematic effect on symptom intensity was observed. The overall indoor environment was evaluated equally acceptable at both temperatures due to local thermal discomfort at the low air temperature....

  18. Ten questions about radiant heating and cooling systems

    DEFF Research Database (Denmark)

    Rhee, Kyu-Nam; Olesen, Bjarne W.; Kim, Kwang Woo

    2017-01-01

    studies on RHC systems in terms of comfort, heat transfer analysis, energy simulation, control strategy, system configurations and so on. Many studies have demonstrated that the RHC system is a good solution to improve indoor environmental quality while reducing building energy consumption for heating......Radiant heating and cooling (RHC) systems are being increasingly applied not only in residential but also in non-residential buildings such as commercial buildings, education facilities, and even large scale buildings such as airport terminals. Furthermore, with the combined ventilation system used...

  19. Study on coal char ignition by radiant heat flux.

    Science.gov (United States)

    Korotkikh, A. G.; Slyusarskiy, K. V.

    2017-11-01

    The study on coal char ignition by CO2-continuous laser was carried out. The coal char samples of T-grade bituminous coal and 2B-grade lignite were studied via CO2-laser ignition setup. Ignition delay times were determined at ambient condition in heat flux density range 90-200 W/cm2. The average ignition delay time value for lignite samples were 2 times lower while this difference is larger in high heat flux region and lower in low heat flux region. The kinetic constants for overall oxidation reaction were determined using analytic solution of simplified one-dimensional heat transfer equation with radiant heat transfer boundary condition. The activation energy for lignite char was found to be less than it is for bituminous coal char by approximately 20 %.

  20. Inverse optimal design of the radiant heating in materials processing and manufacturing

    Science.gov (United States)

    Fedorov, A. G.; Lee, K. H.; Viskanta, R.

    1998-12-01

    Combined convective, conductive, and radiative heat transfer is analyzed during heating of a continuously moving load in the industrial radiant oven. A transient, quasi-three-dimensional model of heat transfer between a continuous load of parts moving inside an oven on a conveyor belt at a constant speed and an array of radiant heaters/burners placed inside the furnace enclosure is developed. The model accounts for radiative exchange between the heaters and the load, heat conduction in the load, and convective heat transfer between the moving load and oven environment. The thermal model developed has been used to construct a general framework for an inverse optimal design of an industrial oven as an example. In particular, the procedure based on the Levenberg-Marquardt nonlinear least squares optimization algorithm has been developed to obtain the optimal temperatures of the heaters/burners that need to be specified to achieve a prescribed temperature distribution of the surface of a load. The results of calculations for several sample cases are reported to illustrate the capabilities of the procedure developed for the optimal inverse design of an industrial radiant oven.

  1. Present and projected future mean radiant temperature for three European cities

    Science.gov (United States)

    Thorsson, Sofia; Rayner, David; Lindberg, Fredrik; Monteiro, Ana; Katzschner, Lutz; Lau, Kevin Ka-Lun; Campe, Sabrina; Katzschner, Antje; Konarska, Janina; Onomura, Shiho; Velho, Sara; Holmer, Björn

    2017-09-01

    Present-day and projected future changes in mean radiant temperature, T mrt in one northern, one mid-, and one southern European city (represented by Gothenburg, Frankfurt, and Porto), are presented, and the concept of hot spots is adopted. Air temperature, T a , increased in all cities by 2100, but changes in solar radiation due to changes in cloudiness counterbalanced or exacerbated the effects on T mrt. The number of days with high T mrt in Gothenburg was relatively unchanged at the end of the century (+1 day), whereas it more than doubled in Frankfurt and tripled in Porto. The use of street trees to reduce daytime radiant heat load was analyzed using hot spots to identify where trees could be most beneficial. Hot spots, although varying in intensity and frequency, were generally confined to near sunlit southeast-southwest facing walls, in northeast corner of courtyards, and in open spaces in all three cities. By adding trees in these spaces, the radiant heat load can be reduced, especially in spaces with no or few trees. A set of design principles for reducing the radiant heat load is outlined based on these findings and existing literature.

  2. Radiant heat increases piglets’ use of the heated creep area on the critical days after birth

    DEFF Research Database (Denmark)

    Larsen, Mona Lilian Vestbjerg; Thodberg, Karen; Pedersen, Lene Juul

    2017-01-01

    The aim of the present study was to investigate how piglets’ use of a creep area is affected by using radiant heat compared to an incandescent light bulb. It was hypothesised that radiant heat would increase the use of the creep area. Twenty litters were randomly assigned to one of two heat sources...... in the creep area: (1) an incandescent light bulb (STANDARD, n=10) or (2) a radiant heat source (RADIANT, n=10) with five of each type of heat source in each of two batches. Observations on piglets’ position in the pen were made by scan sampling every ten minutes in a 4-hour period from 1100 to 1500 h on day 1......–7, 14 and 21 post partum. A higher percentage of piglets in the creep area was seen for RADIANT litters compared to STANDARD litters on day 2 (P=0.002) and day 3 (P=0.005), and percentage of piglets in the creep area increased for RADIANT litters from day 1 to 2 (P

  3. Exergy metrication of radiant panel heating and cooling with heat pumps

    International Nuclear Information System (INIS)

    Kilkis, Birol

    2012-01-01

    Highlights: ► Rational Exergy Management Model analytically relates heat pumps and radiant panels. ► Heat pumps driven by wind energy perform better with radiantpanels. ► Better CO 2 mitigation is possible with wind turbine, heat pump, radiant panel combination. ► Energy savings and thermo-mechanical performance are directly linked to CO 2 emissions. - Abstract: Radiant panels are known to be energy efficient sensible heating and cooling systems and a suitable fit for low-exergy buildings. This paper points out the little known fact that this may not necessarily be true unless their low-exergy demand is matched with low-exergy waste and alternative energy resources. In order to further investigate and metricate this condition and shed more light on this issue for different types of energy resources and energy conversion systems coupled to radiant panels, a new engineering metric was developed. Using this metric, which is based on the Rational Exergy Management Model, true potential and benefits of radiant panels coupled to ground-source heat pumps were analyzed. Results provide a new perspective in identifying the actual benefits of heat pump technology in curbing CO 2 emissions and also refer to IEA Annex 49 findings for low-exergy buildings. Case studies regarding different scenarios are compared with a base case, which comprises a radiant panel system connected to a natural gas-fired condensing boiler in heating and a grid power-driven chiller in cooling. Results show that there is a substantial CO 2 emission reduction potential if radiant panels are optimally operated with ground-source heat pumps driven by renewable energy sources, or optimally matched with combined heat and power systems, preferably running on alternative fuels.

  4. EXPERIMENTAL INVESTIGATION OF THE CONVECTIVE HEAT TRANSFER IN A SPIRALLY COILED CORRUGATED TUBE WITH RADIANT HEATING

    Directory of Open Access Journals (Sweden)

    Milan Đorđević

    2017-12-01

    Full Text Available The Archimedean spiral coil made of a transversely corrugated tube was exposed to radiant heating in order to represent a heat absorber of the parabolic dish solar concentrator. The main advantage of the considered innovative design solution is a coupling effect of the two passive methods for heat transfer enhancement - coiling of the flow channel and changes in surface roughness. The curvature ratio of the spiral coil varies from 0.029 to 0.234, while water and a mixture of propylene glycol and water are used as heat transfer fluids. The unique focus of this study is on specific boundary conditions since the heat flux upon the tube external surfaces varies not only in the circumferential direction, but in the axial direction as well. Instrumentation of the laboratory model of the heat absorber mounted in the radiation field includes measurement of inlet fluid flow rate, pressure drop, inlet and outlet fluid temperature and 35 type K thermocouples welded to the coil surface. A thermal analysis of the experimentally obtained data implies taking into consideration the externally applied radiation field, convective and radiative heat losses, conduction through the tube wall and convection to the internal fluid. The experimental results have shown significant enhancement of the heat transfer rate compared to spirally coiled smooth tubes, up to 240% in the turbulent flow regime.

  5. Radiant heat testing of the H1224A shipping/storage container

    Energy Technology Data Exchange (ETDEWEB)

    Harding, D.C.; Bobbe, J.G.; Stenberg, D.R.; Arviso, M.

    1994-05-01

    H1224A weapons containers have been used for years by the Departments of Energy and Defense to transport and store W78 warhead midsections. Although designed to protect the midsections only from low-energy impacts, a recent transportation risk assessment effort has identified a need to evaluate the container`s ability to protect weapons in more severe accident environments. Four radiant heat tests were performed: two each on an H1224A container (with a Mk12a Mod 6c mass mock-up midsection inside) and two on a low-cost simulated H1224A container (with a hollow Mk12 aeroshell midsections inside). For each unit tested, temperatures were recorded at numerous points throughout the container and midsection during a 4-hour 121{degrees}C (250{degrees}F) and 30-minute 1010{degrees}C (1850{degrees}F) radiant environment. Measured peak temperatures experienced by the inner walls of the midsections as a result of exposure to the high-temperature radiant environment ranged from 650{degrees} C to 980{degrees} C (1200{degrees} F to 1800{degrees}F) for the H1224A container and 770 {degrees} to 990 {degrees}C (1420{degrees} F to 1810{degrees}F) for the simulated container. The majority of both containers were completely destroyed during the high-temperature test. Temperature profiles will be used to benchmark analytical models and predict warhead midsection temperatures over a wide range of the thermal accident conditions.

  6. Numerical investigation on the convective heat transfer in a spiral coil with radiant heating

    Directory of Open Access Journals (Sweden)

    Đorđević Milan Lj.

    2016-01-01

    Full Text Available The objective of this study was to numerically investigate the heat transfer in spiral coil tube in the laminar, transitional, and turbulent flow regimes. The Archimedean spiral coil was exposed to radiant heating and should represent heat absorber of parabolic dish solar concentrator. Specific boundary conditions represent the uniqueness of this study, since the heat flux upon the tube external surfaces varies not only in the circumferential direction, but also in the axial direction. The curvature ratio of spiral coil varies from 0.029 at the flow inlet to 0.234 at the flow outlet, while the heat transfer fluid is water. The 3-D steady-state transport equations were solved using the Reynolds stress turbulence model. Results showed that secondary flows strongly affect the flow and that the heat transfer is strongly asymmetric, with higher values near the outer wall of spiral. Although overall turbulence levels were lower than in a straight pipe, heat transfer rates were larger due to the curvature-induced modifications of the mean flow and temperature fields. [Projekat Ministarstva nauke Republike Srbije, br. 42006

  7. Prediction of radiant heat flux from horizontal propane jet fire

    International Nuclear Information System (INIS)

    Zhou, Kuibin; Liu, Jiaoyan; Jiang, Juncheng

    2016-01-01

    Highlights: • Line source model for the radiant heat flux from horizontal jet fire is proposed. • A review on the difference between horizontal and vertical jet fires is conducted. • Effects of lift-off distance and flame shape are discussed for the line source model. • Line source model gives encouraging results relative to the validity of model system. - Abstract: Jet fires are often reported to occur in process industry with lots of hazardous heat energy released. A line source model describing the flame emissive power and subsequent heat flux radiated from a horizontal propane jet fire is evaluated through a testing against experimental fire data and comparison against other models. By a review on the jet flame behavior, the correlations of the lift-off distance, flame length and radiative fraction are proposed to close the line source model in theory. It is found that the fuel jet direction holds a considerable effect on the flame behavior by comparison between horizontal and vertical jet fires. Results indicate that the lift-off distance and the flame shape influence the model prediction to some extent. Comparison of model predictions against data collected in the near field and predictions from the point source model and multipoint source model gives encouraging results relative to the validity of model system.

  8. Subjective evaluation of different ventilation concepts combined with radiant heating and cooling

    DEFF Research Database (Denmark)

    Krajcik, Michal; Tomasi, Roberta; Simone, Angela

    2012-01-01

    Sixteen subjects evaluated the indoor environment in four experiments with different combinations of ventilation and radiant heating/cooling systems. Two test setups simulated a room in a low energy building with a single occupant during winter. The room was equipped either by a ventilation system...... supplying warm air space heating or by a combination of radiant floor heating and mixing ventilation system. Next two test setups simulated an office room with two occupants during summer, ventilated and cooled by a single displacement ventilation system or by a radiant floor cooling combined...

  9. Influence of radiant heating treatments on fusion of high-temperature superconducting yttrium ceramics; Vliyanie termoradiatsionnykh obrabotok na sintez vysokotempiraturnykh sverkhprovodyaschikh ittrievykh keramik

    Energy Technology Data Exchange (ETDEWEB)

    Bitenbaev, M I; Polyakov, A I [Inst. Yadernoj Fiziki Natsionalnogo Yadernogo Tsentra Respubliki Kazakhstan, Almaty (Kazakhstan)

    1999-07-01

    Regardless of the fact that the materials made of HTSC-ceramics are promising, there is no any information about their successful practical application in publications. To our opinion, it is explained by the fact, first of all, that the conservative technologies of the powder metallurgy do not allow producing HTSC systems with excellent operating performance (structure homogeneity, long-term stability of Sc properties and etc.). This report presents outcomes of experiments on fusion of yttrium ceramics containing raw components irradiated by g-rays {sup 60}Co under the temperature exceeding 500 degrees C. HTSC properties of ceramics were studied according to their differential spectra of radio-frequency (RF) field absorption. The RF absorption spectrum of yttrium ceramics samples produced according to conservative technology is sufficiently permitted triplet with the Sc transition temperatures range of 80 K, 90 K, 95 K. Irradiation under the increased temperatures and mechanical limitation allow producing samples of yttrium HTSC-ceramics with sufficient homogeneous structure and superconducting properties that are stable to air conditions for not less than one year.

  10. Solar–terrestrial radiant-energy regimes and temperature anomalies of natural and artificial turfs

    International Nuclear Information System (INIS)

    Jim, C.Y.

    2016-01-01

    Highlights: • Solar and terrestrial radian energy regimes affect temperature response of sports turfs. • Adjacent natural and artificial turfs were monitored with replications on sunny days. • Artificial turf has meager albedo, low specific heat and moisture to augment warming. • Artificial turf surface and substrate reach 70 °C but cool down effectively at night. • Artificial turf may induce heat stress on athletes in hot summer afternoon. - Abstract: Artificial turf can develop unusually high surface temperature on hot sunny days. Solar and terrestrial radiant energy regimes as key determinants of thermal performance deserve detailed investigation. This study evaluated six components of the radiant-energy environment of a natural turf (NT) and a contiguous artificial turf (AT) sports fields in Hong Kong: direct solar, reflected solar, net solar, sky thermal, ground thermal, and net thermal. Temperature was monitored at five positions: air at 150 cm, 50 cm and 15 cm height, turf surface, and substrate. The experiment included four replications, namely two summer sunny days, and two duplicated instrument sets at each turf site. The two sites reacted very differently to the same intense daily sum of solar radiation input of 23.70 MW m −2 with 9 h of bright sunshine (>120 W m −2 ), and daily sum of sky thermal radiation input of 38.59 MW m −2 . The maximum direct solar radiation reached 976.1 W m −2 at 1245 h. NT albedo of 0.23 vis-à-vis AT of merely 0.073, and higher moisture content and specific heat of NT materials, presented critical differences. The hydrophobic and generally dry plastic (polyethylene) pile-fibers and black rubber-granule infill materials have low specific heat. Intense incoming shortwave and longwave radiation absorbed readily by AT materials raised turf surface temperature to 70.2 °C and substrate 69.3 °C, in comparison with <40 °C at NT. A cascading warming effect was triggered, beginning with low albedo, high net solar

  11. An experimental study of thermal comfort at different combinations of air and mean radiant temperature

    DEFF Research Database (Denmark)

    Simone, Angela; Olesen, Bjarne W.

    2009-01-01

    It is often discussed if a person prefers a low air temperature (ta) and a high mean radiant temperature (tr), vice-versa or it does not matter as long as the operative temperature is acceptable. One of the hypotheses is that it does not matter for thermal comfort but for perceived air quality......, a lower air temperature is preferred. This paper presents an experimental study with 30 human subjects exposed to three different combinations of air- and mean radiant temperature with an operative temperature around 23 °C. The subjects gave subjective evaluations of thermal comfort and perceived air...... quality during the experiments. The PMV-index gave a good estimation of thermal sensation vote (TSV) when the air and mean radiant temperature were the same. In the environment with different air- and mean radiant temperatures, a thermal comfort evaluation shows an error up to 1 scale unit on the 7-point...

  12. Radiative heat exchange of a meteor body in the approximation of radiant heat conduction

    International Nuclear Information System (INIS)

    Pilyugin, N.N.; Chernova, T.A.

    1986-01-01

    The problem of the thermal and dynamic destruction of large meteor bodies moving in planetary atmospheres is fundamental for the clarification of optical observations and anomalous phenomena in the atmosphere, the determination of the physicochemical properties of meteoroids, and the explanation of the fall of remnants of large meteorites. Therefore, it is important to calculate the coefficient of radiant heat exchange (which is the determining factor under these conditions) for large meteor bodies as they move with hypersonic velocities in an atmosphere. The solution of this problem enables one to find the ablation of a meteorite during its aerodynamic heating and to determine the initial conditions for the solution of problems of the breakup of large bodies and their subsequent motion and ablation. Hypersonic flow of an inviscid gas stream over an axisymmetric blunt body is analyzed with allowance for radiative transfer in a thick-thin approximation. The gas-dynamic problem of the flow of an optically thick gas over a large body is solved by the method of asymptotic joined expansions, using a hypersonic approximation and local self-similarity. An equation is obtained for the coefficient of radiant heat exchange and the peculiarities of such heat exchange for meteor bodies of large size are noted

  13. Calculation codes for radiant heat transfers; Les codes de calcul de rayonnement thermique

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    This document reports on 12 papers about computerized simulation and modeling of radiant heat transfers and fluid flows in various industrial and domestic situations: space heating, metal industry (furnaces, boilers..), aerospace industry (turbojet engines, combustion chambers) etc.. This workshop was organized by the ``radiation`` section of the French society of thermal engineers. (J.S.)

  14. Calculation codes for radiant heat transfers; Les codes de calcul de rayonnement thermique

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-31

    This document reports on 12 papers about computerized simulation and modeling of radiant heat transfers and fluid flows in various industrial and domestic situations: space heating, metal industry (furnaces, boilers..), aerospace industry (turbojet engines, combustion chambers) etc.. This workshop was organized by the ``radiation`` section of the French society of thermal engineers. (J.S.)

  15. Radiant and convective heat transfer for flow of a transparent gas in a short tube with prescribed sinusoidal wall heat flux

    International Nuclear Information System (INIS)

    de Lemos, M.J.S.

    1982-01-01

    The present analysis accounts for radiant and convective heat transfer for a transparent fluid flowing in a short tube with prescribed wall heat flux. The heat flux distribution used was of sine shape with maximum at the middle of the tube. Such a solution is the approximate one for axial power in a nuclear reactor. The solutions for the tube wall and gas bulk temperatures were obtained by successive substitutions for the wall and gas balance energy equations. The results show a decrease of 30% for the maximum wall temperature using black surface (e = 1). In this same case, the increasing in the gas temperature shows a decrease of 58%

  16. Improvement on life and NO{sub x} discharge of radiant heat transfer tube heating system by the elasto-plasticity creep analysis; Dansosei kuripukaiseki ni yoru hosha dennetsukan kanetsu shisutemu no jumyo to NO{sub x} haishutsuryo no kaizen

    Energy Technology Data Exchange (ETDEWEB)

    Nakagawa, Futahiko; Ikaruda, Kunihiro; Abe, Yoshio; Arai, Norio

    1999-06-05

    Combustion thermal process using the radiant heat transfer tube has widely been applied as a heating method which separates the combustion atmosphere from the heating-e atmosphere in various heating furnace such as iron and steel industry. In this thermal process, in order to burn the fuel in tight space in radiant heat transfer service area, radiant heat transfer tube and burner life were short under high temperature and high-load combustion, and there was a problem that that and, burning characteristic such as NO{sub x} generation rate are improved was difficult. In this study, large temperature distribution by the combustion in the radiant heat transfer tube clarified that the life of the radiant heat transfer tube was shortened by elasto-plasticity creep analysis of the radiant heat transfer tube. Then, two steps combustion burner of the exhaust gas self recycling type was developed as a method for reducing the NO{sub x} generation rate, while the temperature distribution of the radiant heat transfer tube was equalized. As the result, it was possible to reduce over 20% in comparison with conventional two steps combustion burner, while radiant heat transfer tube and life of the burner are extended over the conventional double, in respect of the NO{sub x} generation rate. (translated by NEDO)

  17. Comparison of indoor air distribution and thermal environment for different combinations of radiant heating systems with mechanical ventilation systems

    DEFF Research Database (Denmark)

    Wu, Xiaozhou; Fang, Lei; Olesen, Bjarne W.

    2018-01-01

    A hybrid system with a radiant heating system and a mechanical ventilation system, which is regarded as an advanced heating, ventilation and air-conditioning (HVAC) system, has been applied in many modern buildings worldwide. To date, almost no studies focused on comparative analysis of the indoor...... air distribution and the thermal environment for all combinations of radiant heating systems with mechanical ventilation systems. Therefore, in this article, the indoor air distribution and the thermal environment were comparatively analyzed in a room with floor heating (FH) or ceiling heating (CH......) and mixing ventilation (MV) or displacement ventilation (DV) when the supply air temperature ranged from 15.0°C to 19.0°C. The results showed that the temperature effectiveness values were 1.05–1.16 and 0.95–1.02 for MV+ FH and MV+ CH, respectively, and they were 0.78–0.91 and 0.51–0.67 for DV + FH and DV...

  18. Study of thermosiphon and radiant panel passive heating systems for metal buildings

    Energy Technology Data Exchange (ETDEWEB)

    Biehl, F.A.; Schnurr, N.M.; Wray, W.O.

    1983-01-01

    A study of passive-heating systems appropriate for use on metal buildings is being conducted at Los Alamos National Laboratory for the Naval Civil Engineering Laboratory, Port Hueneme, California. The systems selected for study were chosen on the basis of their appropriateness for retrofit applications, although they are also suitable for new construction: simple radiant panels that communicate directly with the building interior and a backflow thermosiphon that provides heat indirectly.

  19. Solar heating by radiant floor: Experimental results and emission reduction obtained with a micro photovoltaic–heat pump system

    International Nuclear Information System (INIS)

    Izquierdo, M.; Agustín-Camacho, P. de

    2015-01-01

    Highlights: • This work presents a PVT multicrystalline solar heating system for buildings. • The PV DC electricity generated was converted to AC to drive an air–water heat pump. • Experimental results obtained from December 1, 2012 to April 30, 2013 are detailed. • An environmental study is also presented. - Abstract: An experimental research with a solar photovoltaic thermal (PVT) micro grid feeding a reversible air–water, 6 kW heating capacity heat pump, has been carried out from December 2012 to April 2013. Its purpose is to heat a laboratory that is used as a house prototype for the study of heating/cooling systems. It was built in accordance with the 2013 Spanish CTE, and has an area of 35 m 2 divided into two internal rooms: one of them housing the storage system, the solar controller, the inverter and the control system; the other one is occupied by three people. Its main thermal characteristics are: UA = 125 W/°C and a maximum thermal load about 6.0 kW at the initial time. The PVT field consists of 12 modules, with a total area of 15.7 m 2 and useful area of 14 m 2 . Each module is composed of 48 polycrystalline silicon cells of 243.4 cm 2 , which with a nominal efficiency 14% can generate a power of 180 W, being the total nominal power installed 2.16 kW. The PV system stores electricity in 250 Ah batteries from where is converted from DC to AC through a 3.0 kW inverter that feeds the heat pump. This works supplying 840 l/h of hot water at 35–45 °C to the radiant floor. The data storing system is recording variables such as solar radiation; temperatures; input power to batteries; heat produced; heat transferred by the radiant floor; heat pump’s COP; isolated ratio; and solar fraction. The objective of this work is to present and discuss the experimental results and the emission reduction of CO 2 obtained during the period from 01/12/2012 to 30/04/2013, including the detailed results of two representative days of Madrid’s climate: 28

  20. The efficacy of radiant heat controls on workers' heat stress around the blast furnace of a steel industry.

    Science.gov (United States)

    Giahi, Omid; Darvishi, Ebrahim; Aliabadi, Mohsen; Khoubi, Jamshid

    2015-01-01

    Workers' exposure to excessive heat in molten industries is mainly due to radiant heat from hot sources. The aim of this study was to evaluate the efficacy of radiant heat controls on workers heat stress around a typical blast furnace. Two main interventions were applied for reducing radiant heat around the blast furnace of a steel industry located in western Iran. These included using a heat absorbing system in the furnace body and installing reflective aluminum barrier in the main workstation. Heat stress indexes were measured before and after each intervention using the digital WBGT-meter. The results showed MRT and WBGT indexes decreased by 20 °C and 3.9 °C, respectively after using heat absorbing system and also decreased by 18.6 °C and 2.5 °C, respectively after installing a reflective barrier. These indexes decrease by 26.5 °C and 5.2 °C, respectively due to the simultaneous application of the two interventions which were statistically significant (p steel industries.

  1. Mathematical Modeling of Radiant Heat Transfer in Mirror Systems Considering Deep Reflecting Surface Defects

    Directory of Open Access Journals (Sweden)

    V. V. Leonov

    2014-01-01

    Full Text Available When designing large-sized mirror concentrating systems (MCS for high-temperature solar power plants, one must have at disposal reasonably reliable and economical methods and tools, making it possible to analyze its characteristics, to predict them depending on the operation conditions and accordingly to choose the most suitable system for the solution of particular task.Experimental determination of MCS characteristics requires complicated and expensive experimentation, having significant limitations on interpretation of the results, as well as limitations imposed due to the size of the structure. Therefore it is of particular interest to develop a mathematical model capable of estimating power characteristics of MCS considering the influence of operating conditions, design features, roughness and other surface defects.For efficient solution of the tasks the model must ensure simulation of solar radiant flux as well as simulation of geometrical and optical characteristics of reflection surface and their interaction. In this connection a statistical mathematical model of radiation heat exchange based on use of Monte Carlo methods and Finite Element Method was developed and realized in the software complex, making it possible to determine main characteristics of the MCS.In this paper the main attention is given to definition of MCS radiation characteristics with account for deep reflecting surface defects (cavities, craters. Deep cavities are not typical for MCS, but their occurrence is possible during operation as a result of erosion or any physical damage. For example, for space technology it is primarily micrometeorite erosion.

  2. Field tests on human tolerance to (LNG) fire radiant heat exposure, and attenuation effects of clothing and other objects

    International Nuclear Information System (INIS)

    Raj, Phani K.

    2008-01-01

    A series of field tests exposing mannequins clothed with civilian clothing to a 3 m x 3 m square liquefied natural gas (LNG) pool fire was conducted. Both single layer clothing and double layer clothing were used. The radiant heat flux incident outside the clothing and incident on the skin covered by clothing were measured using wide-angle radiometers, for durations of 100-200 s (per test). The levels of heat flux incident on the clothing were close to 5 kW/m 2 . The magnitude of the radiant heat attenuation factor (AF) across the thickness was determined. AF varies between 2 and higher for cotton and polyester clothing (thickness 0.286-1.347 mm); AF value of 6 was measured for 1.347 mm thickness. Single sheet newspaper held about 5 cm in front of mannequins and exposed to incident flux of 5 kW/m 2 resulted in AF of 5, and AF of 8 with double sheets. AF decreases linearly with increasing heat flux values and linearly increases with thickness. The author exposed himself, in normal civilian clothing (of full sleeve cotton/polyester shirt and jean pants), to radiant heat from a LNG fire. The exposure was for several tens of seconds to heat flux levels ranging from 3.5 kW/m 2 to 5 + kW/m 2 (exposure times from 25 s to 97 s at average heat flux values in the 4 kW/m 2 and 5 kW/m 2 range). Occasionally, he was exposed to (as high as) 7 kW/m 2 for durations of several seconds. He did not suffer any unbearable or even severe pain nor did he experience blisters or burns or any other injury on the unprotected skin of his body. The incident heat fluxes on the author were measured by a hand-held radiometer (with digital display) as well as by strapped on wide-angle radiometers connected to a computer. He could withstand the US regulatory criterion of 5 kW/m 2 (for 30 s) without suffering any damage or burns. Temperature measured on author's skin covered by clothing did not rise above the normal body temperature even after 200 s of exposure to 4 kW/m 2 average heat flux

  3. Behaviour of monolithic and laminated glass exposed to radiant heating

    NARCIS (Netherlands)

    Debuyser, M.; Sjöström, J.; Lange, D.; Honfi, D.; Sonck, D.; Belis, J.

    2017-01-01

    Glass is seeing a growing interest as a structural material as a result of its relatively good strength to weight ratio and the obvious aesthetic benefits of its use in buildings. However due to the sensitivity of glass to thermal shock and the considerably temperature-dependent behaviour of

  4. Numerical Modeling of Conjugate Thermogravitational Convection in a Closed System with a Radiant Energy Source in Conditions of Convective-Radiative Heat Exchange at the External Boundary

    Directory of Open Access Journals (Sweden)

    Nee Alexander

    2016-01-01

    Full Text Available Mathematical modeling of conjugate natural convection in a closed rectangular cavity with a radiant energy source in conditions of convective-radiative heat exchange at the external boundary was conducted. The radiant energy distribution was set by the Lambert’s law. Conduction and convection processes analysis showed that the air masses flow pattern is modified slightly over the time. The temperature increases in the gas cavity, despite the heat removal from the one of the external boundary. According to the results of the integral heat transfer analysis were established that the average Nusselt number (Nuav increasing occurs up to τ = 200 (dimensionless time. Further Nuav has changed insignificantly due to the temperature field equalization near the interfaces “gas – wall”.

  5. Experimental investigation and feasibility analysis on a capillary radiant heating system based on solar and air source heat pump dual heat source

    International Nuclear Information System (INIS)

    Zhao, M.; Gu, Z.L.; Kang, W.B.; Liu, X.; Zhang, L.Y.; Jin, L.W.; Zhang, Q.L.

    2017-01-01

    Graphical abstract: (a) Vertical temperature gradient in Case 3, (b) PMV and PPD of the test room in Case 3, (c) operating time of SPCTS and ASHP systems in Case 3 and (d) the proportion of SPCTS operating time. - Highlights: • A capillary heating system based on solar and air source heat pump was developed. • Influence of supply water temperature on solar energy saving rate was investigated. • Heating performance and thermal comfort of capillary heating system were analyzed. • Low temperature heating with capillary is suitable for solar heating system. - Abstract: Due to sustainable development, solar energy has drawn much attention and been widely applied in buildings. However, the application of solar energy is limited because of its instability, intermittency and low energy density in winter. In order to use low density and instable solar energy source for heating and improve the utilization efficiency of solar energy, a solar phase change thermal storage (SPCTS) heating system using a radiant-capillary-terminal (RCT) to effectively match the low temperature hot water, a phase change thermal storage (PCTS) to store and continuously utilize the solar energy, and an air source heat pump (ASHP) as an alternate energy, was proposed and set up in this research. Series of experiments were conducted to obtain the relation between the solar radiation utilization rate and the heating supply temperatures, and to evaluate the performance of the RCT module and the indoor thermal environment of the system for its practical application in a residential building in the north-western City of Xi’an, China. The results show that energy saving of the solar heating system can be significantly improved by reducing the supplied water temperature, and the supplied water temperature of the RCT would be no more than 35 °C. The capillary radiation heating can adopt a lower water temperature and create a good thermal comfort environment as well. These results may lead to the

  6. Analysis of directional radiative behavior and heating efficiency for a gas-fired radiant burner

    International Nuclear Information System (INIS)

    Li, B.X.; Lu, Y.P.; Liu, L.H.; Kudo, K.; Tan, H.P.

    2005-01-01

    For the purpose of energy conservation and uniform heating of object surface, a gas-fired porous radiant burner with a bundle of reflecting tubes is developed. A physical model is developed to simulate the directional radiative behavior of this heating device, in which the Monte Carlo method based on the concept of radiation distribution factor is used to compute the directional radiative behavior. The effects of relating parameters on the directional behavior of radiative heating and the heating efficiency are analyzed. With the increase of the length-to-radius ratio of tube, the radiation heating efficiency decreases, but the radiation energy incident on the object surface is more collimated. The radiation heating efficiency increases with the specular reflectivity. With the increase in length of tube segment with specular reflective surface, the radiation heating efficiency increases, but the extent of concentration and collimation of radiative energy decreases. For real design of the heating device, some trade-offs are needed to balance the radiation heating efficiency and the uniformity of radiative heating of object surface

  7. Experimental study including subjective evaluations of mixing and displacement ventilation combined with radiant floor heating/cooling system

    DEFF Research Database (Denmark)

    Krajcik, Michal; Tomasi, Roberta; Simone, Angela

    2013-01-01

    Sixteen subjects evaluated the indoor environment in four experiments with different combinations of ventilation systems and radiant heating/cooling systems. In the first two tests, the simulated residential room was equipped either by a mixing ventilation system supplying warm air for space heat...

  8. Energy flow and thermal comfort in buildings: Comparison of radiant and air-based heating & cooling systems

    DEFF Research Database (Denmark)

    Le Dréau, Jérôme

    Heating and cooling terminals can be classified in two main categories: convective terminals (e.g air conditioning, active chilled beam, fan coil) and radiant terminals. The two terminals have different modes of heat transfer: the first one is mainly based on convection, whereas the second one...... is based on both radiation and convection. This thesis focuses on characterizing the heat transfer from the terminal towards the space and on the parameters influencing the effectiveness of terminals. Therefore the comfort conditions and energy consumption of four types of terminals (active chilled beam...... losses, and an air-based terminal might be more energy-efficient than a radiant terminal (in terms of delivered energy). Regarding comfort, a similar global level has been observed for the radiant and air-based terminals in both numerical and experimental investigations. But the different terminals did...

  9. A Mini-channel Heat Exchanger System for Heating, Boiling, and Superheating Water by Radiant Combustion

    Science.gov (United States)

    2004-06-15

    al. (2002) and Yu, et al., (2002) Bowers and Mudawar (1994a) along with Peng and Peterson (1996) analyzed the geometry and layout of multiple...maintain a more uniform wall temperature; whereas, a single phase fluid must rise in temperature to absorb sensible heat. Qu and Mudawar (2002) and...experiments. In another study of the ONB, Qu and Mudawar (2002) varied flow conditions and visually observed the factors influ- encing ONB. They

  10. The effect of urban geometry on mean radiant temperature under future climate change: a study of three European cities.

    Science.gov (United States)

    Lau, Kevin Ka-Lun; Lindberg, Fredrik; Rayner, David; Thorsson, Sofia

    2015-07-01

    Future anthropogenic climate change is likely to increase the air temperature (T(a)) across Europe and increase the frequency, duration and magnitude of severe heat stress events. Heat stress events are generally associated with clear-sky conditions and high T(a), which give rise to high radiant heat load, i.e. mean radiant temperature (T(mrt)). In urban environments, T mrt is strongly influenced by urban geometry. The present study examines the effect of urban geometry on daytime heat stress in three European cities (Gothenburg in Sweden, Frankfurt in Germany and Porto in Portugal) under present and future climates, using T(mrt) as an indicator of heat stress. It is found that severe heat stress occurs in all three cities. Similar maximum daytime T(mrt) is found in open areas in all three cities despite of the latitudinal differences in average daytime T(mrt). In contrast, dense urban structures like narrow street canyons are able to mitigate heat stress in the summer, without causing substantial changes in T(mrt) in the winter. Although the T(mrt) averages are similar for the north-south and east-west street canyons in each city, the number of hours when T(mrt) exceeds the threshold values of 55.5 and 59.4 °C-used as indicators of moderate and severe heat stress-in the north-south canyons is much higher than that in the east-west canyons. Using statistically downscaled data from a regional climate model, it is found that the study sites were generally warmer in the future scenario, especially Porto, which would further exacerbate heat stress in urban areas. However, a decrease in solar radiation in Gothenburg and Frankfurt reduces T(mrt) in the spring, while the reduction in T(mrt) is somewhat offset by increasing T(a) in other seasons. It suggests that changes in the T(mrt) under the future scenario are dominated by variations in T(a). Nonetheless, the intra-urban differences remain relatively stable in the future. These findings suggest that dense urban

  11. Radiant heat transfers in turbojet engines. Two applications, three levels of modeling; Transferts radiatifs dans les foyers de turboreacteurs. Deux applications, trois niveaux de modelisation

    Energy Technology Data Exchange (ETDEWEB)

    Schultz, J L; Desaulty, M [SNECMA, Centre de Villaroche, 77 - Moissy-Cramayel (France); Taine, J [Ecole Centrale de Paris, Laboratoire EM2C. CNRS, 92 - Chatenay-Malabry (France)

    1997-12-31

    Several applications linked with the dimensioning of turbojet engines require the use of modeling of radiant heat transfers. Two different applications are presented in this study: the modeling of heat transfers in the main combustion chamber, and modeling of the infrared signature of the post-combustion chamber of a military engine. In the first application, two types of radiant heat transfer modeling are presented: a global modeling based on empirical considerations and used in rapid pre-dimensioning methods, and a modeling based on a grey gases concept and combined to a ray shooting type technique allowing the determination of local radiant heat flux values. In the second application, a specific modeling of the radiant heat flux is used in the framework of a ray shooting method. Each model represents a different level of successive approximations of the radiant heat transfer adapted to flow specificities and to the performance requested. (J.S.) 16 refs.

  12. Radiant heat transfers in turbojet engines. Two applications, three levels of modeling; Transferts radiatifs dans les foyers de turboreacteurs. Deux applications, trois niveaux de modelisation

    Energy Technology Data Exchange (ETDEWEB)

    Schultz, J.L.; Desaulty, M. [SNECMA, Centre de Villaroche, 77 - Moissy-Cramayel (France); Taine, J. [Ecole Centrale de Paris, Laboratoire EM2C. CNRS, 92 - Chatenay-Malabry (France)

    1996-12-31

    Several applications linked with the dimensioning of turbojet engines require the use of modeling of radiant heat transfers. Two different applications are presented in this study: the modeling of heat transfers in the main combustion chamber, and modeling of the infrared signature of the post-combustion chamber of a military engine. In the first application, two types of radiant heat transfer modeling are presented: a global modeling based on empirical considerations and used in rapid pre-dimensioning methods, and a modeling based on a grey gases concept and combined to a ray shooting type technique allowing the determination of local radiant heat flux values. In the second application, a specific modeling of the radiant heat flux is used in the framework of a ray shooting method. Each model represents a different level of successive approximations of the radiant heat transfer adapted to flow specificities and to the performance requested. (J.S.) 16 refs.

  13. A critical examination of the validity of simplified models for radiant heat transfer analysis.

    Science.gov (United States)

    Toor, J. S.; Viskanta, R.

    1972-01-01

    Examination of the directional effects of the simplified models by comparing the experimental data with the predictions based on simple and more detailed models for the radiation characteristics of surfaces. Analytical results indicate that the constant property diffuse and specular models do not yield the upper and lower bounds on local radiant heat flux. In general, the constant property specular analysis yields higher values of irradiation than the constant property diffuse analysis. A diffuse surface in the enclosure appears to destroy the effect of specularity of the other surfaces. Semigray and gray analyses predict the irradiation reasonably well provided that the directional properties and the specularity of the surfaces are taken into account. The uniform and nonuniform radiosity diffuse models are in satisfactory agreement with each other.

  14. Thermal inertia and radiating average Temperature. A brief analysis of some causes of discomfort; Inercia Termica y Temperatura media radiante. Un breve analisis de algunas causas de disconfort

    Energy Technology Data Exchange (ETDEWEB)

    Arroba, M.

    2008-07-01

    Radiant average temperature in walls is as important as dry air temperature to achieve thermal comfort of users of a local. An excessive discrepancy between these levels, or an asymmetric distribution of the surface temperature of fences, may cause localized thermal discomfort, an effect impossible to compensate by rising dry air temperature. Thermal inertia and its concentration must be properly studied in order to handle this parameters, inside or outside the building, on both sides of the cladding or none depending on the weather, the bio climatic strategies used, heating and air conditioning systems and planned use of the building. (Author)

  15. Radiant heat evaluation of concrete: a study of the erosion of concrete due to surface heating

    International Nuclear Information System (INIS)

    Chu, T.Y.

    1978-01-01

    Experiments were carried out to investigate the erosion of concrete under high surface heat flux in connection with the core-melt/concrete interaction studies. The dominate erosion mechanism was found to be melting at the surface accompanied by chemical decomposition of the concrete beneath the melt-solid interface. The erosion process reaches a steady state after an initial transient. The steady state is characterized by an essentially constant erosion rate at the surface and a nonvarying (with respect to the moving melt interface) temperature distribution within the concrete. For the range of incident heat flux 64 W/cm 2 to 118 W/cm 2 , the corresponding steady state erosion rate varies from approximately 8 cm/hr to 23 cm/hr. A simple ablation/melting model is proposed for the erosion process. The model was found to be able to correlate all temperature responses at various depths from all tests at large times and for temperatures above approximately 250 0 C

  16. Energy flow and thermal comfort in buildings: Comparison of radiant and air-based heating & cooling systems

    DEFF Research Database (Denmark)

    Le Dréau, Jérôme

    is based on both radiation and convection. This thesis focuses on characterizing the heat transfer from the terminal towards the space and on the parameters influencing the effectiveness of terminals. Therefore the comfort conditions and energy consumption of four types of terminals (active chilled beam...... losses, and an air-based terminal might be more energy-efficient than a radiant terminal (in terms of delivered energy). Regarding comfort, a similar global level has been observed for the radiant and air-based terminals in both numerical and experimental investigations. But the different terminals did...... not achieve the same uniformity in space. The active chilled beam theoretically achieves the most uniform comfort conditions (when disregarding the risk of draught), followed by the radiant ceiling. The least uniform conditions were obtained with the cooled floor due to large differences between the sitting...

  17. Effect of radiant heat at the birth site in farrowing crates on hypothermia and behaviour in neonatal piglets

    DEFF Research Database (Denmark)

    Andersen, Heidi Mai-Lis; Pedersen, Lene Juul

    2016-01-01

    It has been documented that floor heating of the farrowing area in loose housed sows improves survival of piglets significantly. However, today, the majority of farrowing pens are designed with crating of sows and slatted floor at the birth site. The aim of this study was to investigate whether...... providing radiant heat at the birth site to new-born piglets in pens with crated sows reduced hypothermia, time to first milk intake and growth of the piglets during the 1st week. Second parity Danish Landrace×Yorkshire sows (n=36) were randomly divided into two groups: Control (CG) and heat (HG......). In the area behind the sow (zone 1), two radiant heat panels were mounted above the slatted floor in the HG. The farrowings were attended, and the heaters were turned on at birth of first piglet and turned off 12 h after. Birth time, time to leave zone 1, time to first contact with udder and time to first...

  18. Modeling of mean radiant temperature based on comparison of airborne remote sensing data with surface measured data

    Science.gov (United States)

    Chen, Yu-Cheng; Chen, Chih-Yu; Matzarakis, Andreas; Liu, Jin-King; Lin, Tzu-Ping

    2016-06-01

    Assessment of outdoor thermal comfort is becoming increasingly important due to the urban heat island effect, which strongly affects the urban thermal environment. The mean radiant temperature (Tmrt) quantifies the effect of the radiation environment on humans, but it can only be estimated based on influencing parameters and factors. Knowledge of Tmrt is important for quantifying the heat load on human beings, especially during heat waves. This study estimates Tmrt using several methods, which are based on climatic data from a traditional weather station, microscale ground surface measurements, land surface temperature (LST) and light detection and ranging (LIDAR) data measured using airborne devices. Analytical results reveal that the best means of estimating Tmrt combines information about LST and surface elevation information with meteorological data from the closest weather station. The application in this method can eliminate the inconvenience of executing a wide range ground surface measurement, the insufficient resolution of satellite data and the incomplete data of current urban built environments. This method can be used to map a whole city to identify hot spots, and can be contributed to understanding human biometeorological conditions quickly and accurately.

  19. Research on the Improvement of a Natural Gas Fired Burner for the CHP Application in a Central Heating Boiler using Radiant Burner Technology

    Energy Technology Data Exchange (ETDEWEB)

    Bieleveld, T.

    2010-08-15

    minimized and more heat is transferred via radiation. Because the current engine-burner is of the surface burner type, a model for this burner type is established, showing typical burner characteristics. It is investigated how the radiant efficiency can be improved of this porous surface burner type. Using this burner technology, the maximum possible radiant heat flux would lead to an impractically large burner surface area. It is believed that the radiation efficiency of the burner can be greatly enhanced when combustion takes place inside a porous medium. By doing so, high material temperatures can be achieved due to internal radiation and the heat exchanger effect of the burner material downstream of the flame. The theoretical maximum burner performance is therefore investigated for a certain value of optimum temperature, for which the gas temperature and solid temperature are equal. It is found that a submerged flame inside a porous medium greatly enhances radiant efficiency. From previous, mainly experimental work on dual layer submerged combustion, preferable material parameters per layer are found and a suggestion is made for future practical analysis. Because of the high potential of the dual porous layer submerged radiant burner, a model for this type of burner is initiated. For ease of future changes and implementation, as well as to obtain knowledge on this type of burner, model development was performed by its future user, the author of this thesis.

  20. Smart Control of Air Climatization System in Function on the Values of Mean Local Radiant Temperature

    Directory of Open Access Journals (Sweden)

    Giuseppe Cannistraro

    2015-08-01

    Full Text Available The hygrothermal comfort indoor conditions are defined as: those environmental conditions in which an individual exposed, expresses a state of satisfaction. These conditions cannot always be achieved anywhere in an optimal way and economically; in some cases they can be obtained only in work environments specific areas. This could be explained because of air conditioning systems designing is generally performed both on the basis of the fundamental parameters’ average values, such as temperature, velocity and relative humidity (Ta, va e φa and derived parameters such as operating temperature and mean radiant one (Top eTmr. However, in some specific cases - large open-spaces or in case of radiating surfaces - the descriptors defining indoor comfort conditions, based on average values, do not provide the optimum values required during the air conditioning systems design phase. This is largely due to the variability of real environmental parameters values compared to the average ones taken as input in the calculation. The results obtained in previous scientific papers on the thermal comfort have been the driving element of this work. It offers a simple, original and clever way of thinking about the new domotic systems for air conditioning, based on the “local mean radiant temperature.” This is a very important parameter when one wants to analyze comfort in environments characterized by the presence of radiating surfaces, as will be seen hereinafter. In order to take into account the effects of radiative exchanges in the open-space workplace, where any occupant may find themselves in different temperature and humidity conditions, this paper proposes an action on the domotic climate control, with ducts and vents air distribution placed in different zones. Comparisons were performed between the parameters values representing the punctual thermal comfort, with the Predicted Mean Vote PMV, in an environment marked by radiating surfaces (i

  1. Solar radiation, phytoplankton pigments and the radiant heating of the equatorial Pacific warm pool

    Science.gov (United States)

    Siegel, David A.; Ohlmann, J. Carter; Washburn, Libe; Bidigare, Robert R.; Nosse, Craig T.; Fields, Erik; Zhou, Yimei

    1995-01-01

    Recent optical, physical, and biological oceanographic observations are used to assess the magnitude and variability of the penetrating flux of solar radiation through the mixed layer of the warm water pool (WWP) of the western equatorial Pacific Ocean. Typical values for the penetrative solar flux at the climatological mean mixed layer depth for the WWP (30 m) are approx. 23 W/sq m and are a large fraction of the climatological mean net air-sea heat flux (approx. 40 W/sq m). The penetrating solar flux can vary significantly on synoptic timescales. Following a sustained westerly wind burst in situ solar fluxes were reduced in response to a near tripling of mixed layer phytoplankton pigment concentrations. This results in a reduction in the penetrative flux at depth (5.6 W/sq m at 30 m) and corresponds to a biogeochemically mediated increase in the mixed layer radiant heating rate of 0.13 C per month. These observations demonstrate a significant role of biogeochemical processes on WWP thermal climate. We speculate that this biogeochemically mediated feedback process may play an important role in enhancing the rate at which the WWP climate system returns to normal conditions following a westerly wind burst event.

  2. Applying Fibre-Optic Distributed Temperature Sensing to Near-surface Temperature Dynamics of Broadacre Cereals During Radiant Frost Events.

    Science.gov (United States)

    Stutsel, B.; Callow, J. N.

    2017-12-01

    Radiant frost events, particularly those during the reproductive stage of winter cereal growth, cost growers millions of dollars in lost yield. Whilst synoptic drivers of frost and factors influencing temperature variation at the landscape scale are relatively well understood, there is a lack of knowledge surrounding small-scale temperature dynamics within paddocks and plot trials. Other work has also suggested a potential significant temperature gradient (several degrees) vertically from ground to canopy, but this is poorly constrained experimentally. Subtle changes in temperature are important as frost damage generally occurs in a very narrow temperature range (-2 to -5°C). Once a variety's damage threshold is reached, a 1°C difference in minimum temperature can increase damage from 10 to 90%. This study applies Distributed Temperature Sensing (DTS) using fibre optics to understand how minimum temperature evolves during a radiant frost. DTS assesses the difference in attenuation of Raman scattering of a light pulse travelling along a fibre optic cable to measure temperature. A bend insensitive multimode fibre was deployed in a double ended duplex configuration as a "fence" run through four times of sowing at a trial site in the Western Australian Wheatbelt. The fibre optic fence was 160m long and 800mm tall with the fibre optic cable spaced 100mm apart vertically, and calibrated in ambient water ( 10 to 15oC) and a chilled glycol ( -8 to-10 oC) baths. The temperature measurements had a spatial resolution of 0.65m and temporal resolution of 60s, providing 2,215 measurements every minute. The results of this study inform our understanding of the subtle temperature changes from the soil to canopy, providing new insight into how to place traditional temperature loggers to monitor frost damage. It also addresses questions of within-trial temperature variability, and provides an example of how novel techniques such as DTS can be used to improve the way temperature

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

    Science.gov (United States)

    Huang, Tao; Xiang, Yutong; Wang, Yonghong

    2017-05-01

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

  4. Study of radiation heating (part 1). UR spectroscopic characteristics of radiant heat source

    Energy Technology Data Exchange (ETDEWEB)

    Nagaoka, Yoshikazu; Ajisaka, Kazuhiro; Toyonaga, Hajime; Kitahata, Hiroki; Oshida, Shun' ichi; Sugihara, Tomonori

    1987-09-01

    There are many IR permeable substances. When this is heated with IR beam, UR beam penetrated into the substance and heat up the substance from the inside. In this case, the inside gets hot quicker than the surface which gives much difference in the finish of the product. Characteristics of permeation and absorption of the IR beam vary by the type of the substance and the wave-length of the UR beam. Examples of effectiveness of far infra-red heater are: Baking of rice cake. Baking of PVC granules as a slip-stop for a working gloves. Far infra-red sauna (sweating effect around 50/sup 0/C). Tokyo Gas Co., Ltd. and other companies introduced an IR spectroscopic radiometer of Minarad Systems of USA to establish a data exchange system in 1984. The spectroscopic radio-meter system consists of 3 components, i.e., a spectrophotometric radiometer, a black body furnace, and a computer for data processing. (14 figs, 5 tabs)

  5. PAIR INFLUENCE OF WIND SPEED AND MEAN RADIANT TEMPERATURE ON OUTDOOR THERMAL COMFORT OF HUMID TROPICAL ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    Sangkertadi Sangkertadi

    2016-01-01

    Full Text Available The purposes of this article is to explore knowledge of outdoor thermal comfort in humid tropical environment for urban activities especially for people in walking activity, and those who stationary/seated with moderate action. It will be characterized the pair influence of wind speed and radiant temperature on the outdoor thermal comfort. Many of researchers stated that those two microclimate variables give significant role on outdoor thermal comfort in tropical humid area. Outdoor Tropical Comfort (OTC model was used for simulation in this study. The model output is comfort scale that refers on ASHRAE definition. The model consists of two regression equations with variables of air temperature, globe temperature, wind speed, humidity and body posture, for two types of activity: walking and seated. From the results it can be stated that there is significant role of wind speed to reduce mean radiant temperature and globe temperature, when the velocity is elevated from 0.5 m/s to 2 m/s. However, the wind has not play significant role when the speed is changed from 2 m/s to 3.5 m/s. The results of the study may inspire us to implement effectiveness of electrical-fan equipment for outdoor space in order to get optimum wind speed, coupled with optimum design of shading devices to minimize radiant temperature for thermal comfort.

  6. Assessing the accuracy of globe thermometer method in predicting outdoor mean radiant temperature under Malaysia tropical microclimate

    Science.gov (United States)

    Khrit, N. G.; Alghoul, M. A.; Sopian, K.; Lahimer, A. A.; Elayeb, O. K.

    2017-11-01

    Assessing outdoor human thermal comfort and urban climate quality require experimental investigation of microclimatic conditions and their variations in open urban spaces. For this, it is essential to provide quantitative information on air temperature, humidity, wind velocity and mean radiant temperature. These parameters can be quantified directly except mean radiant temperature (Tmrt). The most accurate method to quantify Tmrt is integral radiation measurements (3-D shortwave and long-wave) which require using expensive radiometer instruments. To overcome this limitation the well-known globe thermometer method was suggested to calculate Tmrt. The aim of this study was to assess the possibility of using indoor globe thermometer method in predicting outdoor mean radiant temperature under Malaysia tropical microclimate. Globe thermometer method using small and large sizes of black-painted copper globes (50mm, 150mm) were used to estimate Tmrt and compare it with the reference Tmrt estimated by integral radiation method. The results revealed that the globe thermometer method considerably overestimated Tmrt during the middle of the day and slightly underestimated it in the morning and late evening. The difference between the two methods was obvious when the amount of incoming solar radiation was high. The results also showed that the effect of globe size on the estimated Tmrt is mostly small. Though, the estimated Tmrt by the small globe showed a relatively large amount of scattering caused by rapid changes in radiation and wind speed.

  7. The spectral optical properties and relative radiant heating contribution of dissolved and particulate matter in the surface waters across the Fram Strait

    DEFF Research Database (Denmark)

    Pavlov, A.K.; Granskog, M.A.; Stedmon, Colin

    autumns of 2009 and 2010 comprehensive observations were performed on transects along 79 N across the Fram Strait. Samples for chromophoric dissolved organic matter (CDOM) and particulate absorption were collected and analyzed together with distribution of temperature and salinity in surface waters (0......-100 m). Large spatial variations in the distribution of CDOM and particulate matter as well as in their relative contributions to total absorption were apparent, with high contrast between waters of Arctic and Atlantic origin. In addition, estimates of underwater light profiles and radiant heating rate...... (RHR) of the upper layer were obtained using a simplistic exponential RHR model. This is one of the first detailed overviews of sea water optical properties across the northern Fram Strait, and might have potential implications for biological, biogeochemical and physical processes in the region...

  8. Mathematical Modeling of the Thermal State of an Isothermal Element with Account of the Radiant Heat Transfer Between Parts of a Spacecraft

    Science.gov (United States)

    Alifanov, O. M.; Paleshkin, A. V.; Terent‧ev, V. V.; Firsyuk, S. O.

    2016-01-01

    A methodological approach to determination of the thermal state at a point on the surface of an isothermal element of a small spacecraft has been developed. A mathematical model of heat transfer between surfaces of intricate geometric configuration has been described. In this model, account was taken of the external field of radiant fluxes and of the differentiated mutual influence of the surfaces. An algorithm for calculation of the distribution of the density of the radiation absorbed by surface elements of the object under study has been proposed. The temperature field on the lateral surface of the spacecraft exposed to sunlight and on its shady side has been calculated. By determining the thermal state of magnetic controls of the orientation system as an example, the authors have assessed the contribution of the radiation coming from the solar-cell panels and from the spacecraft surface.

  9. Radiant cooling of an enclosure

    International Nuclear Information System (INIS)

    Chebihi, Abdeslam; Byun, Ki-Hong; Wen Jin; Smith, Theodore F.

    2006-01-01

    The purpose of this study is to analyze the potential for radiant cooling using the atmospheric sky window and to evaluate the desired characteristics of a radiant cooling material (RCM) applied to the ceiling window of a three-dimensional enclosure. The thermal characteristics of the system are governed by the geometry, ambient temperature, sky radiative temperature, amount of solar energy and its direction, heat transfer modes, wall radiative properties, and radiative properties of the RCMs. A semi-gray band analysis is utilized for the solar and infrared bands. The radiosity/irradiation method is used in each band to evaluate the radiant exchanges in the enclosure. The radiative properties for the RCM are varied in a parametric study to identify the desired properties of RCMs. For performance simulation of real RCMs, the radiative properties are calculated from spectral data. The desired solar property is a high reflectance for both opaque and semi-transparent RCMs. For a semi-transparent RCM, a low value of the solar transmittance is preferred. The desired infrared property is a high emittance for an opaque RCM. For a semi-transparent RCM, a high infrared transmittance is desired, and the emittance should be greater than zero

  10. Experimental and modelling analysis of an office building HVAC system based in a ground-coupled heat pump and radiant floor

    International Nuclear Information System (INIS)

    Villarino, José Ignacio; Villarino, Alberto; Fernández, Francisco Ángel

    2017-01-01

    Highlights: • A case study of a geothermal heat pump in an office building. • A numerical model in EnergyPlus is validated by experimental results. • An energy, economic and environmental analysis is presented. • A comparison with other technologies demonstrates the potential of the system. - Abstract: This paper shows the evaluation of the performance of a ground-coupled heat pump system monitored building providing heating, ventilating and air conditioning to an office building located in Madrid, in Spain. The system consists of one borehole exchanger, heat pump unit, radiant floor system, mechanical ventilation and data control system. A simulation model was performed with EnergyPlus software and validated. The analyzed period corresponds to the most unfavorable weather conditions in heating and cooling mode. The coefficient of performance obtained in heating and cooling mode was 3.86/5.29, considering all the energy consumption elements of the building and the thermal demand corresponding to an office operation. The CO_2 emissions obtained with a value of 34.68 kg corresponding to the period analyzed represents a low CO_2 emission system. The monitored temperatures reached set point values of 22 °C/25 °C, considered as acceptable comfort temperatures. The values obtained in the validated simulation model presented a deviation of 2% respected experimental results in heating and cooling mode. A comparative of COP_s_y_s and CO_2 emissions with other technologies is performed in order to analyze GCHP compared to other available technologies. The GCHP system is presented as a technology that can fully supply the HVAC conditions for a building and environmentally friendly.

  11. Improvement of life and NO{sub x} emission of radiant tube heating system by elastic-plastic creep analysis; Dansosei kuripu kaiseki ni yoru hosha dennetsukan kanetsu shisutemu no jumyo to NO{sub x} haishutsuryo no kaizen

    Energy Technology Data Exchange (ETDEWEB)

    Nakagawa, Tsuguhiko; Nuta, Kunihiro [Kawasaki Steel Corp., Okayama, (Japan). Mizushima Warks

    1999-03-10

    The radiant tube heating system has been widely applied to the furnaces which require isolation of the heating atmosphere from the combustion atmosphere. However, the conventional system has a short life and it is difficult to reduce NO{sub x} emission when it is used at a high furnace temperature under high combustion load, because the fuel is burned in a small space. In order to solve this problem, we have studied the cause of radiant tube life depends on the uniformity of the temperature distribution along the radiant tube. We have developed a new burner using a two-stage combustion method with exhaust gas self-recirculation. As a result, the file of the new system has been increased by a factor of two or more, and NO{sub x} emission has been reduced by 20 % from previous levels. This paper presents an outline of the elastic-plastic creep analysis and the new burner, and describes the effect of its use on system life. (author)

  12. Finite-elements modeling of radiant heat transfers between mobile surfaces; Modelisation par elements finis de transferts radiatifs entre surfaces mobiles

    Energy Technology Data Exchange (ETDEWEB)

    Daurelle, J V; Cadene, V; Occelli, R [Universite de Provence, 13 - Marseille (France)

    1997-12-31

    In the numerical modeling of thermal industrial problems, radiant heat transfers remain difficult to take into account and require important computer memory and long computing time. These difficulties are enhanced when radiant heat transfers are coupled with finite-elements diffusive heat transfers because finite-elements architecture is complex and requires a lot of memory. In the case of radiant heat transfers along mobile boundaries, the methods must be optimized. The model described in this paper concerns the radiant heat transfers between diffuse grey surfaces. These transfers are coupled with conduction transfers in the limits of the diffusive opaque domain. 2-D and 3-D geometries are analyzed and two configurations of mobile boundaries are considered. In the first configuration, the boundary follows the deformation of the mesh, while in the second, the boundary moves along the fixed mesh. Matter displacement is taken into account in the term of transport of the energy equation, and an appropriate variation of the thermophysical properties of the transition elements between the opaque and transparent media is used. After a description of the introduction of radiative limit conditions in a finite-elements thermal model, the original methods used to optimize calculation time are explained. Two examples of application illustrate the approach used. The first concerns the modeling of radiant heat transfers between fuel rods during a reactor cooling accident, and the second concerns the study of heat transfers inside the air-gap of an electric motor. The method of identification of the mobile surface on the fixed mesh is described. (J.S.) 12 refs.

  13. Finite-elements modeling of radiant heat transfers between mobile surfaces; Modelisation par elements finis de transferts radiatifs entre surfaces mobiles

    Energy Technology Data Exchange (ETDEWEB)

    Daurelle, J.V.; Cadene, V.; Occelli, R. [Universite de Provence, 13 - Marseille (France)

    1996-12-31

    In the numerical modeling of thermal industrial problems, radiant heat transfers remain difficult to take into account and require important computer memory and long computing time. These difficulties are enhanced when radiant heat transfers are coupled with finite-elements diffusive heat transfers because finite-elements architecture is complex and requires a lot of memory. In the case of radiant heat transfers along mobile boundaries, the methods must be optimized. The model described in this paper concerns the radiant heat transfers between diffuse grey surfaces. These transfers are coupled with conduction transfers in the limits of the diffusive opaque domain. 2-D and 3-D geometries are analyzed and two configurations of mobile boundaries are considered. In the first configuration, the boundary follows the deformation of the mesh, while in the second, the boundary moves along the fixed mesh. Matter displacement is taken into account in the term of transport of the energy equation, and an appropriate variation of the thermophysical properties of the transition elements between the opaque and transparent media is used. After a description of the introduction of radiative limit conditions in a finite-elements thermal model, the original methods used to optimize calculation time are explained. Two examples of application illustrate the approach used. The first concerns the modeling of radiant heat transfers between fuel rods during a reactor cooling accident, and the second concerns the study of heat transfers inside the air-gap of an electric motor. The method of identification of the mobile surface on the fixed mesh is described. (J.S.) 12 refs.

  14. Heat index and adjusted temperature as surrogates for wet bulb globe temperature to screen for occupational heat stress.

    Science.gov (United States)

    Bernard, Thomas E; Iheanacho, Ivory

    2015-01-01

    Ambient temperature and relative humidity are readily ava-ilable and thus tempting metrics for heat stress assessment. Two methods of using air temperature and relative humidity to create an index are Heat Index and Adjusted Temperature. The purposes of this article are: (1) to examine how well Heat Index and Adjusted Temperature estimated the wet bulb globe temperature (WBGT) index, and (2) to suggest how Heat Index and Adjusted Temperature can be used to screen for heat stress level. Psychrometric relationships were used to estimate values of actual WBGT for conditions of air temperature, relative humidity, and radiant heat at an air speed of 0.5 m/s. A relationship between Heat Index [°F] and WBGT [°C] was described by WBGT = -0.0034 HI(2) + 0.96 HI - 34. At lower Heat Index values, the equation estimated WBGTs that were ± 2 °C-WBGT around the actual value, and to about ± 0.5 °C-WBGT for Heat Index values > 100 °F. A relationship between Adjusted Temperature [°F] and WBGT [°C] was described by WBGT = 0.45 Tadj - 16. The actual WBGT was between 1 °C-WBGT below the estimated value and 1.4 °C-WBGT above. That is, there was a slight bias toward overestimating WBGT from Adjusted Temperature. Heat stress screening tables were constructed for metabolic rates of 180, 300, and 450 W. The screening decisions were divided into four categories: (1) exposure limit at rest. The authors do not recommend using Heat Index or Adjusted Temperature instead of WBGT, but they may be used to screen for circumstances when a more detailed analysis using WBGT is appropriate. A particular weakness is accounting for radiant heat; and neither air speed nor clothing was considered.

  15. Optimal design approach for heating irregular-shaped objects in three-dimensional radiant furnaces using a hybrid genetic algorithm-artificial neural network method

    Science.gov (United States)

    Darvishvand, Leila; Kamkari, Babak; Kowsary, Farshad

    2018-03-01

    In this article, a new hybrid method based on the combination of the genetic algorithm (GA) and artificial neural network (ANN) is developed to optimize the design of three-dimensional (3-D) radiant furnaces. A 3-D irregular shape design body (DB) heated inside a 3-D radiant furnace is considered as a case study. The uniform thermal conditions on the DB surfaces are obtained by minimizing an objective function. An ANN is developed to predict the objective function value which is trained through the data produced by applying the Monte Carlo method. The trained ANN is used in conjunction with the GA to find the optimal design variables. The results show that the computational time using the GA-ANN approach is significantly less than that of the conventional method. It is concluded that the integration of the ANN with GA is an efficient technique for optimization of the radiant furnaces.

  16. Experimental investigation of the influence of the air jet trajectory on convective heat transfer in buildings equipped with air-based and radiant cooling systems

    DEFF Research Database (Denmark)

    Le Dreau, Jerome; Heiselberg, Per; Jensen, Rasmus Lund

    2015-01-01

    -state and dynamic conditions. With the air-based cooling system, a dependency of the convective heat transfer on the air jet trajectory has been observed. New correlations have been developed, introducing a modified Archimedes number to account for the air flow pattern. The accuracy of the new correlations has been...... evaluated to±15%. Besides the study with an air-based cooling system, the convective heat transfer with a radiant cooling system has also been investigated. The convective flow at the activated surface is mainly driven by natural convection. For other surfaces, the complexity of the flow and the large......The complexity and diversity of airflow in buildings make the accurate definition of convective heat transfer coefficients (CHTCs) difficult. In a full-scale test facility, the convective heat transfer of two cooling systems (active chilled beam and radiant wall) has been investigated under steady...

  17. Field evaluation of performance of radiant heating/cooling ceiling panel system

    DEFF Research Database (Denmark)

    Li, Rongling; Yoshidomi, Togo; Ooka, Ryozo

    2015-01-01

    heating/coolingceiling panel system is used. However, no standard exists for the in situ performance evaluation of radiantheating/cooling ceiling systems; furthermore, no published database is available for comparison. Thus,this study aims to not only clarify the system performance but also to share our...... experience and our resultsfor them to serve as a reference for other similar projects. Here, the system performance in relation toits heating/cooling capacity and thermal comfort has been evaluated. The heat transfer coefficient fromwater to room was 3.7 W/(m2K) and 4.8 W/(m2K) for heating and cooling cases...

  18. Radiant Floor Cooling Systems

    DEFF Research Database (Denmark)

    Olesen, Bjarne W.

    2008-01-01

    In many countries, hydronic radiant floor systems are widely used for heating all types of buildings such as residential, churches, gymnasiums, hospitals, hangars, storage buildings, industrial buildings, and smaller offices. However, few systems are used for cooling.This article describes a floor...... cooling system that includes such considerations as thermal comfort of the occupants, which design parameters will influence the cooling capacity and how the system should be controlled. Examples of applications are presented....

  19. Performance Evaluation of Radiator and Radiant Floor Heating Systems for an Office Room Connected to a Ground-Coupled Heat Pump

    Directory of Open Access Journals (Sweden)

    Ioan Sarbu

    2016-03-01

    Full Text Available A ground-coupled heat pump (GCHP system used to provide the space heating for an office room is a renewable, high performance technology. This paper discusses vapour compression-based HP systems, briefly describing the thermodynamic cycle calculations, as well as the coefficient of performance (COP and CO2 emissions of a HP with an electro-compressor and compares different heating systems in terms of energy consumption, thermal comfort and environmental impact. It is focused on an experimental study performed to test the energy efficiency of the radiator or radiant floor heating system for an office room connected to a GCHP. The main performance parameters (COP and CO2 emissions are obtained for one month of operation of the GCHP system, and a comparative analysis of these parameters is presented. Additionally, two numerical simulation models of useful thermal energy and the system COP in heating mode are developed using the Transient Systems Simulation (TRNSYS software. Finally, the simulations obtained from TRNSYS software are analysed and compared to the experimental data, showing good agreement and thus validating the simulation models.

  20. Experimental and Numerical Study of the Radiant Induction-Unit and the Induction Radiant Air-Conditioning System

    Directory of Open Access Journals (Sweden)

    Qiang Si

    2016-12-01

    Full Text Available In this paper we proposed the novel air-conditioning system which combined induction ventilation and radiant air-conditioning. The indoor terminal device is the radiant induction-unit (RIDU. The RIDU is the induction unit combined with the pore radiant panel on which the copper pipes with rigid aluminum diffusion fins are installed. The two-stage evaporator chiller with the non-azeotropic mixture refrigerant is utilized in the system to reduce the initial investment in equipment. With the performance test and the steady state heat transfer model based on the theory of radiative heat transfer, the relationship between the induction ratio of the RIDU and the characteristic of the air supply was studied. Based on this, it is verified that the RIDU has a lower dew-point temperature and better anti-condensation performance than a traditional plate-type radiant panel. The characteristics of the radiation and convection heat transfer of the RIDU were studied. The total heat exchange of the RIDU can be 16.5% greater than that of the traditional plate-type radiant terminal.

  1. Air-to-Water Heat Pumps With Radiant Delivery in Low-Load Homes

    Energy Technology Data Exchange (ETDEWEB)

    Backman, C. [Alliance for Residential Building Innovation (ARBI), Davis, CA (United States); German, A. [Alliance for Residential Building Innovation (ARBI), Davis, CA (United States); Dakin, B. [Alliance for Residential Building Innovation (ARBI), Davis, CA (United States); Springer, D. [Alliance for Residential Building Innovation (ARBI), Davis, CA (United States)

    2013-12-01

    Space conditioning represents nearly 50% of average residential household energy consumption, highlighting the need to identify alternative cost-effective, energy-efficient cooling and heating strategies. As homes are better built, there is an increasing need for strategies that are particularly well suited for high performance, low load homes. ARBI researchers worked with two test homes in hot-dry climates to evaluate the in-situ performance of air-to-water heat pump systems, an energy efficient space conditioning solution designed to cost-effectively provide comfort in homes with efficient, safe, and durable operation. Two monitoring projects of test houses in hot-dry climates were initiated in 2010 to test this system. Both systems were fully instrumented and have been monitored over one year to capture complete performance data over the cooling and heating seasons. Results are used to quantify energy savings, cost-effectiveness, and system performance using different operating modes and strategies. A calibrated TRNSYS model was developed and used to evaluate performance in various climate regions. This strategy is most effective in tight, insulated homes with high levels of thermal mass (i.e. exposed slab floors).

  2. Air-to-Water Heat Pumps With Radiant Delivery in Low-Load Homes

    Energy Technology Data Exchange (ETDEWEB)

    Backman, C. [Alliance for Residential Building Innovation, Davis, CA (United States). Davis Energy Group; German, A. [Alliance for Residential Building Innovation, Davis, CA (United States). Davis Energy Group; Dakin, B. [Alliance for Residential Building Innovation, Davis, CA (United States). Davis Energy Group; Springer, D. [Alliance for Residential Building Innovation, Davis, CA (United States). Davis Energy Group

    2013-12-01

    Space conditioning represents nearly 50% of average residential household energy consumption, highlighting the need to identify alternative cost-effective, energy-efficient cooling and heating strategies. As homes are better built, there is an increasing need for strategies that are particularly well suited for high performance, low load homes. ARBI researchers worked with two test homes in hot-dry climates to evaluate the in-situ performance of air-to-water heat pump (AWHP) systems, an energy efficient space conditioning solution designed to cost-effectively provide comfort in homes with efficient, safe, and durable operation. Two monitoring projects of test houses in hot-dry climates were initiated in 2010 to test this system. Both systems were fully instrumented and have been monitored over one year to capture complete performance data over the cooling and heating seasons. Results are used to quantify energy savings, cost-effectiveness, and system performance using different operating modes and strategies. A calibrated TRNSYS model was developed and used to evaluate performance in various climate regions. This strategy is most effective in tight, insulated homes with high levels of thermal mass (i.e. exposed slab floors).

  3. Effects of blue diode laser (445 nm) and LED (430-480 nm) radiant heat treatments on dental glass ionomer restoratives

    Science.gov (United States)

    Dionysopoulos, Dimitrios; Tolidis, Kosmas; Strakas, Dimitrios; Gerasimou, Paris; Sfeikos, Thrasyvoulos; Gutknecht, Norbert

    2018-02-01

    The purpose of this in vitro study was to evaluate the effect of two radiant heat treatments on water sorption, solubility and surface roughness of three conventional glass ionomer cements by using a blue diode laser (445 nm) and a light emitting diode (LED) unit (430-480 nm). Thirty disk-shaped specimens were prepared for each tested GIC (Equia Fil, Ketac Universal Aplicap and Riva Self Cure). The experimental groups (n = 10) of the study were as follows: Group 1 was the control group, in Group 2 the specimens were irradiated for 60 s at the top surface using a LED light-curing unit and in Group 3 the specimens were irradiated for 60 s at the top surface using a blue light diode laser. Statistical analysis was performed using one-way ANOVA and Tukey post hoc tests at a level of significance of a = 0.05. Radiant heat treatments with both laser and LED devices significantly decreased water sorption and solubility (p tested GICs. Blue diode laser treatment was seemed to be more effective compared to LED treatment for some of the tested materials. There were no changes in surface roughness of the GICs after the treatments (p > 0.05). Among the tested materials there were differences in water sorption and solubility (p 0.05). The use of the blue diode laser for this radiant heat treatment was harmless for the surface of the tested GICs and may be advantageous for the longevity of their restorations.

  4. Low temperature nuclear heat

    Energy Technology Data Exchange (ETDEWEB)

    Kotakorpi, J.; Tarjanne, R. [comps.

    1977-08-01

    The meeting was concerned with the use of low grade nuclear heat for district heating, desalination, process heat, and agriculture and aquaculture. The sessions covered applications and demand, heat sources, and economics.

  5. Coupling of a discrete ordinate 3-D radiant heat transfer model with the PHOENICS fluid mechanics software; Couplage d`un modele radiatif tridimensionnel aux ordonnees discretes au logiciel de mecanique des fluides phoenics

    Energy Technology Data Exchange (ETDEWEB)

    Muller, J [IRSID, Institut de Recherches Siderurgie, 57 - Maizieres-les-Metz (France)

    1997-12-31

    Radiant heat transfer is the main solution retained in many iron and steel metallurgy installations (re-heating and annealing furnaces etc..). Today, it has become important to dispose of performing radiant heat transfer models in heat transfer and fluid mechanics simulation softwares, and well adapted to multidimensional industrial problems. This work presents the discrete ordinate radiant heat transfer model developed at the IRSID (the French institute of research in iron and steel metallurgy) and coupled with the PHOENICS heat transfer-fluid mechanics software. Three modeling approaches are presented concerning the radiative properties of gases (H{sub 2}O-CO{sub 2}). A ``weighted grey gases sum`` model gives satisfactory results for several 1-D validation cases. (J.S.) 20 refs.

  6. Coupling of a discrete ordinate 3-D radiant heat transfer model with the PHOENICS fluid mechanics software; Couplage d`un modele radiatif tridimensionnel aux ordonnees discretes au logiciel de mecanique des fluides phoenics

    Energy Technology Data Exchange (ETDEWEB)

    Muller, J. [IRSID, Institut de Recherches Siderurgie, 57 - Maizieres-les-Metz (France)

    1996-12-31

    Radiant heat transfer is the main solution retained in many iron and steel metallurgy installations (re-heating and annealing furnaces etc..). Today, it has become important to dispose of performing radiant heat transfer models in heat transfer and fluid mechanics simulation softwares, and well adapted to multidimensional industrial problems. This work presents the discrete ordinate radiant heat transfer model developed at the IRSID (the French institute of research in iron and steel metallurgy) and coupled with the PHOENICS heat transfer-fluid mechanics software. Three modeling approaches are presented concerning the radiative properties of gases (H{sub 2}O-CO{sub 2}). A ``weighted grey gases sum`` model gives satisfactory results for several 1-D validation cases. (J.S.) 20 refs.

  7. Influence of radiant energy exchange on the determination of convective heat transfer rates to Orbiter leeside surfaces during entry

    Science.gov (United States)

    Throckmorton, D. A.

    1982-01-01

    Temperatures measured at the aerodynamic surface of the Orbiter's thermal protection system (TPS), and calorimeter measurements, are used to determine heating rates to the TPS surface during atmospheric entry. On the Orbiter leeside, where convective heating rates are low, it is possible that a significant portion of the total energy input may result from solar radiation, and for the wing, cross radiation from the hot (relatively) Orbiter fuselage. In order to account for the potential impact of these sources, values of solar- and cross-radiation heat transfer are computed, based upon vehicle trajectory and attitude information and measured surface temperatures. Leeside heat-transfer data from the STS-2 mission are presented, and the significance of solar radiation and fuselage-to-wing cross-radiation contributions to total energy input to Orbiter leeside surfaces is assessed.

  8. Parameter optimization through performance analysis of model based control of a batch heat treatment furnace with low NO x radiant tube burner

    International Nuclear Information System (INIS)

    Tiwari, Manish Kumar; Mukhopadhyay, Achintya; Sanyal, Dipankar

    2005-01-01

    A model based control structure for heat treating a 0.5% C steel slab in a batch furnace with low NO x radiant tube burner is designed and tested for performance to yield optimal parameter values using the model developed in the companion paper. Combustion is considered in a highly preheated and product gas diluted mode. Controlled combustion with a proposed arrangement for preheating and diluting the air by recirculating the exhaust gas that can be retrofitted with an existing burner yields satisfactory performance and emission characteristics. Finally, the effect of variable property considerations are presented and critically analyzed

  9. Nonimaging radiant energy device

    Science.gov (United States)

    Winston, Roland; Ning, Xiaohui

    1993-01-01

    A nonimaging radiant energy device may include a hyperbolically shaped reflective element with a radiant energy inlet and a radiant energy outlet. A convex lens is provided at the radiant energy inlet and a concave lens is provided at the radiant energy outlet. Due to the provision of the lenses and the shape of the walls of the reflective element, the radiant energy incident at the radiant energy inlet within a predetermined angle of acceptance is emitted from the radiant energy outlet exclusively within an acute exit angle. In another embodiment, the radiant energy device may include two interconnected hyperbolically shaped reflective elements with a respective convex lens being provided at each aperture of the device.

  10. Design of energy efficient building with radiant slab cooling

    Science.gov (United States)

    Tian, Zhen

    2007-12-01

    Air-conditioning comprises a substantial fraction of commercial building energy use because of compressor-driven refrigeration and fan-driven air circulation. Core regions of large buildings require year-round cooling due to heat gains from people, lights and equipment. Negative environmental impacts include CO2 emissions from electric generation and leakage of ozone-depleting refrigerants. Some argue that radiant cooling simultaneously improves building efficiency and occupant thermal comfort, and that current thermal comfort models fail to reflect occupant experience with radiant thermal control systems. There is little field evidence to test these claims. The University of Calgary's Information and Communications Technology (ICT) Building, is a pioneering radiant slab cooling installation in North America. Thermal comfort and energy performance were evaluated. Measurements included: (1) heating and cooling energy use, (2) electrical energy use for lighting and equipment, and (3) indoor temperatures. Accuracy of a whole building energy simulation model was evaluated with these data. Simulation was then used to compare the radiant slab design with a conventional (variable air volume) system. The radiant system energy performance was found to be poorer mainly due to: (1) simultaneous cooling by the slab and heating by other systems, (2) omission of low-exergy (e.g., groundwater) cooling possible with the high cooling water temperatures possible with radiant slabs and (3) excessive solar gain and conductive heat loss due to the wall and fenestration design. Occupant thermal comfort was evaluated through questionnaires and concurrent measurement of workstation comfort parameters. Analysis of 116 sets of data from 82 occupants showed that occupant assessment was consistent with estimates based on current thermal comfort models. The main thermal comfort improvements were reductions in (1) local discomfort from draft and (2) vertical air temperature stratification. The

  11. Temperature distribution in spouted bed and heat transfer

    International Nuclear Information System (INIS)

    Takeda, Hiroshi; Yamamoto, Yutaka

    1976-01-01

    Temperature distribution in spouted bed was measured by using brass and graphite spouted beds so as to investigate heat transfer characteristic of spouted bed applied to an apparatus of PyC coating. These spouted beds are batch type and are spouted by air or nitrogen gas of room temperature, and the outer wall of beds are heated by nichrome or graphite heater. Particles used for experiments are alumina spherical particles and the diameter is 0.80 -- 1.12 mm. Temperature condition is in the range of 400 -- 1,400 0 C. In the neighborhood of 400 0 C, the spouting condition is stable, while the spouting condition becomes unstable in the case of above 1,000 0 C. This is caused by abrupt temperature increase of spouting gas. It was found that heat transfer coefficient h sub(w) of our low temperature experiments was closer to the calculated from Malek et al.'s equation, h sub(p) of our experiments was several times greater than the calculated from Uemaki et al.'s equation. On the other hand, h sub(p) of high temperature experiments was compared with an experimental relation for convective heat transfer of fluidized bed, it was found that Nu sub(p) of our experiments was nearly equal to or greater than the calculated from the relation, this would be caused by radiant heat transfer. (auth.)

  12. Daytime relapse of the mean radiant temperature based on the six-directional method under unobstructed solar radiation.

    Science.gov (United States)

    Kántor, Noémi; Lin, Tzu-Ping; Matzarakis, Andreas

    2014-09-01

    This study contributes to the knowledge about the capabilities of the popular "six-directional method" describing the radiation fields outdoors. In Taiwan, measurements were carried out with three orthogonally placed net radiometers to determine the mean radiant temperature (T(mrt)). The short- and long-wave radiation flux densities from the six perpendicular directions were recorded in the daylight hours of 12 days. During unobstructed direct irradiation, a specific daytime relapse was found in the temporal course of the T(mrt) values referring to the reference shapes of a standing man and also of a sphere. This relapse can be related to the short-wave fluxes reaching the body from the lateral directions. Through deeper analysis, an instrumental shortcoming of the six-directional technique was discovered. The pyranometer pairs of the same net radiometer have a 10-15-min long "blind spot" when the sun beams are nearly perpendicular to them. The blind-spot period is supposed to be shorter with steeper solar azimuth curve on the daylight period. This means that the locations with lower geographical latitude, and the summertime measurements, are affected less by this instrumental problem. A methodological shortcoming of the six-directional technique was also demonstrated. Namely, the sum of the short-wave flux densities from the lateral directions is sensitive to the orientation of the radiometers, and therefore by deviating from the original directions, the T(mrt) decrease on clear sunny days will occur in different times and will be different in extent.

  13. Temperature patterns in the gas infrared radiator heating area

    Directory of Open Access Journals (Sweden)

    Kurilenko N.I.

    2015-01-01

    Full Text Available The obtained results of experimental studies provide the basis for the heat transfer mechanism specification on the studied conditions that are typical for many practical applications. It was proved appropriateness of the natural convection and heat conduction process simulation while analyzing the heat transfer in rectangular enclosures with the radiant heating sources at the high bound.

  14. Advanced radiant combustion system. Final report, September 1989--September 1996

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, J.D.; Carswell, M.G.; Long, F.S.

    1996-09-01

    Results of the Advanced Radiant Combustion System (ARCS) project are presented in this report. This work was performed by Alzeta Corporation as prime contractor under a contract to the U.S. Department of Energy Office of Industrial Technologies as part of a larger DOE program entitled Research Program for Advanced Combustion Systems. The goals of the Alzeta ARCS project were to (a) Improve the high temperature performance characteristics of porous surface ceramic fiber burners, (b) Develop an Advanced Radiant Combustion System (ARCS) that combines combustion controls with an advanced radiant burner, and (c) Demonstrate the advanced burner and controls in an industrial application. Prior to the start of this project, Alzeta had developed and commercialized a porous surface radiant burner, the Pyrocore{trademark} burner. The product had been commercially available for approximately 5 years and had achieved commercial success in a number of applications ranging from small burners for commercial cooking equipment to large burners for low temperature industrial fluid heating applications. The burner was not recommended for use in applications with process temperatures above 1000{degrees}F, which prevented the burner from being used in intermediate to high temperature processes in the chemical and petroleum refining industries. The interest in increasing the maximum use temperature of the burner was motivated in part by a desire to expand the number of applications that could use the Pyrocore product, but also because many of the fluid sensitive heating applications of interest would benefit from the distributed flux characteristic of porous surface burners. Background information on porous surface radiant burners, and a discussion of advantages that would be provided by an improved product, are presented in Section 2.

  15. Modeling of radiant heat transfers in non-grey gases using the discrete ordinate method in association with a narrow bands statistical model; Modelisation des transferts radiatifs dans des gaz non gris par la methode des ordonnees discretes associee a un modele statistique a bandes etroites

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, A.B. de; Delmas, A; Sacadura, J F [Institut National des Sciences Appliquees (INSA), 69 - Villeurbanne (France)

    1997-12-31

    A formulation based on the use of the discrete ordinate method applied to the integral form of the radiant heat transfer equation is proposed for non-grey gases. The correlations between transmittances are neglected and no explicit wall reflexion is considered. The configuration analyzed consists in a flat layer of non-isothermal steam-nitrogen mixture. Cavity walls are grey with diffuse reflexion and emission. A narrow band statistical model is used to represent the radiative properties of the gas. The distribution of the radiative source term inside the cavity is calculated along two temperature profiles in a uniform steam concentration. Results obtained using this simplified approach are in good agreement with those found in the literature for the same temperature and concentration distributions. This preliminary study seems to indicate that the algorithm based on the integration of radiant heat transfer along the luminance path is less sensitive to de-correlation effects than formulations based on the differential form the the radiant heat transfer. Thus, a more systematic study of the influence of the neglecting of correlations on the integral approach is analyzed in this work. (J.S.) 16 refs.

  16. Modeling of radiant heat transfers in non-grey gases using the discrete ordinate method in association with a narrow bands statistical model; Modelisation des transferts radiatifs dans des gaz non gris par la methode des ordonnees discretes associee a un modele statistique a bandes etroites

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, A.B. de; Delmas, A.; Sacadura, J.F. [Institut National des Sciences Appliquees (INSA), 69 - Villeurbanne (France)

    1996-12-31

    A formulation based on the use of the discrete ordinate method applied to the integral form of the radiant heat transfer equation is proposed for non-grey gases. The correlations between transmittances are neglected and no explicit wall reflexion is considered. The configuration analyzed consists in a flat layer of non-isothermal steam-nitrogen mixture. Cavity walls are grey with diffuse reflexion and emission. A narrow band statistical model is used to represent the radiative properties of the gas. The distribution of the radiative source term inside the cavity is calculated along two temperature profiles in a uniform steam concentration. Results obtained using this simplified approach are in good agreement with those found in the literature for the same temperature and concentration distributions. This preliminary study seems to indicate that the algorithm based on the integration of radiant heat transfer along the luminance path is less sensitive to de-correlation effects than formulations based on the differential form the the radiant heat transfer. Thus, a more systematic study of the influence of the neglecting of correlations on the integral approach is analyzed in this work. (J.S.) 16 refs.

  17. High temperature industrial heat pumps

    Energy Technology Data Exchange (ETDEWEB)

    Berghmans, J. (Louvain Univ., Heverlee (Belgium). Inst. Mechanica)

    1990-01-01

    The present report intends to describe the state of the art of high temperature industrial heat pumps. A description is given of present systems on the market. In addition the research and development efforts on this subject are described. Compression (open as well as closed cycle) systems, as well as absorption heat pumps (including transformers), are considered. This state of the art description is based upon literature studies performed by a team of researchers from the Katholieke Universiteit Leuven, Belgium. The research team also analysed the economics of heat pumps of different types under the present economic conditions. The heat pumps are compared with conventional heating systems. This analysis was performed in order to evaluate the present condition of the heat pump in the European industry.

  18. Heat transfer from a high temperature condensable mixture

    International Nuclear Information System (INIS)

    Chan, S.H.; Cho, D.H.; Condiff, D.W.

    1978-01-01

    A new development in heat transfer is reported. It is concerned with heat transfer from a gaseous mixture that contains a condensable vapor and is at very high temperature. In the past, heat transfer associated with either a condensable mixture at low temperature or a noncondensable mixture at high temperature has been investigated. The former reduces to the classical problem of fog formation in, say, atmosphere where the rate of condensation is diffusion controlled (molecular or conductive diffusions). In the presence of noncondensable gases, heat transfer to a cooler boundary by this mechanism is known to be drastically reduced. In the latter case, where the high temperature mixture is noncondensable, radiative transfer may become dominant and a vast amount of existing literature exists on this class of problem. A fundamentally different type of problem of relevance to recent advances in open cycle MHD power plants and breeder reactor safety is considered. In the advanced coal-fired power plant using MHD as a topping cycle, a condensable mixture is encountered at temperatures of 2000 to 3000 0 . Condensation of the vaporized slag and seed materials at such a high temperature can take place in the MHD generator channel as well as in the radiant boiler. Similarly, in breeder reactor accident analyses involving hypothetical core disruptive accidents, a UO 2 vapor mixture at 400 0 K or higher is often considered. Since the saturation temperature of UO 2 at one atmosphere is close to 4000 0 K, condensation is also likely at a very high temperature. Accordingly, an objective of the present work is to provide an understanding of heat transfer and condensation mechanics insystems containing a high temperature condensable mixture. The results of the study show that, when a high temperature mixture is in contact with a cooler surface, a thermal boundary layer develops rapidly because of intensive radiative cooling from the mixture

  19. Effects of Floor Covering Resistance of a Radiant Floor on System Energy and Exergy Performances

    DEFF Research Database (Denmark)

    Kazanci, Ongun Berk; Shukuya, Masanori; Olesen, Bjarne W.

    2016-01-01

    Floor covering resistance (material and thickness) can be influenced by subjective choices (architectural design, interior design, texture, etc.) with significant effects on the performance of a radiant heating and cooling system. To study the effects of floor covering resistance on system...... performance, a water-based radiant floor heating and cooling system (dry, wooden construction) was considered to be coupled to an air-to-water heat pump, and the effects of varying floor covering resistances (0.05 m2K/W, 0.09 m2K/W and 0.15 m2K/W) on system performance were analyzed in terms of energy...... and exergy. In order to achieve the same heating and cooling outputs, higher average water temperatures are required in the heating mode (and lower temperatures in the cooling mode) with increasing floor covering resistance. These temperature requirements decrease the heat pump’s performance (lower...

  20. Heat balance model for a human body in the form of wet bulb globe temperature indices.

    Science.gov (United States)

    Sakoi, Tomonori; Mochida, Tohru; Kurazumi, Yoshihito; Kuwabara, Kohei; Horiba, Yosuke; Sawada, Shin-Ichi

    2018-01-01

    The purpose of this study is to expand the empirically derived wet bulb globe temperature (WBGT) index to a rational thermal index based on the heat balance for a human body. We derive the heat balance model in the same form as the WBGT for a human engaged in moderate intensity work with a metabolic heat production of 174W/m 2 while wearing typical vapor-permeable clothing under shady and sunny conditions. Two important relationships are revealed based on this derivation: (1) the natural wet bulb and black globe temperature coefficients in the WBGT coincide with the heat balance equation for a human body with a fixed skin wettedness of approximately 0.45 at a fixed skin temperature; and (2) the WBGT can be interpreted as the environmental potential to increase skin temperature rather than the heat storage rate of a human body. We propose an adjustment factor calculation method that supports the application of WBGT for humans dressed in various clothing types and working under various air velocity conditions. Concurrently, we note difficulties in adjusting the WBGT by using a single factor for humans wearing vapor-impermeable protective clothing. The WBGT for shady conditions does not need adjustment depending on the positive radiant field (i.e., when a radiant heat source exists), whereas that for the sunny condition requires adjustments because it underestimates heat stress, which may result in insufficient human protection measures. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Heat pipes for temperature control

    International Nuclear Information System (INIS)

    Groll, M.

    1978-01-01

    Heat pipes have known for years as effective constructional elements for temperature control. With the aid of special techniques (gas, liquid, steam, and voltage control), special operating characteristics can be obtained, e.g. variable heat conduction or diode behaviour. Their main field of application is in spacecraft technology and in nuclear technology in the isothermalisation of irradiation capsules. The different control techniques are presented and critically evaluated on the basis of characteristic properties like heat transfer capacity, volume and mass requirements, complexity of structure and production, reliability, and temperature control characteristics. Advantages and shortcomings of the different concepts are derived and compared. The state of the art of these control techniques is established on the basis of four development levels. Finally, the necessity and direction of further R + D activities are discussed, and suggestions are made for further work. (orig./HP) [de

  2. Radiant recuperator modelling and design

    Directory of Open Access Journals (Sweden)

    Knežević Suzana D.

    2017-01-01

    Full Text Available Recuperators are frequently used in glass production and metallurgical processes to preheat combustion air by heat exchange with high temperature flue gases. Mass and energy balances of a 15 m high, concurrent radiant recuperator used in a glass fiber production process are given. The balances are used: for validation of a cell modeling method that predicts the performance of different recuperator designs, and for finding a simple solution to improve the existing recuperator. Three possible solutions are analyzed: to use the existing recuperator as a countercurrent one, to add an extra cylinder over the existing construction, and to make a system that consists of a central pipe and two concentric annular ducts. In the latter, two air streams flow in opposite directions, whereas air in the inner annular passage flows concurrently or countercurrently to flue gases. Compared with the concurrent recuperator, the countercurrent has only one drawback: the interface temperature is higher at the bottom. The advantages are: lower interface temperature at the top where the material is under maximal load, higher efficiency, and smaller pressure drop. Both concurrent and countercurrent double pipe-in-pipe systems are only slightly more efficient than pure concurrent and countercurrent recuperators, respectively. Their advantages are smaller interface temperatures whereas the disadvantages are their costs and pressure drops. To implement these solutions, the average velocities should be: for flue gas around 5 m/s, for air in the first passage less than 2 m/s, and for air in the second passage more than 25 m/s. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. EE 33027

  3. Design and construction of radiant panel for cooling and heating with photovoltaic and thermoelectric element modules; Taiyo denchi to netsuden soshi module wo mochiita fukusha reidanbo panel no sekkei oyobi shisaku

    Energy Technology Data Exchange (ETDEWEB)

    Sato, M; Tani, T [Science University of Tokyo, Tokyo (Japan); Kadotani, K; Imaizumi, H [Komatsu Ltd., Tokyo (Japan)

    1997-11-25

    Utilizing cooling properties and current voltage characteristics of a small cooling panel using thermoelectric elements which had been fabricated previously on a trial basis, design and prototype production were executed on a large radiant cooling and heating panel driven by photovoltaic cell modules. The panel design set the cooling area to about 0.5 m {sup 2} and the number of elements to 70 pieces, and optimum number of elements in series and parallel connection was derived. As a result of the analysis, it was made clear that the optimum number of thermoelectric module arrays in series and parallel connection varies depending on insolation intensity. It was found preferable that the number of parallel connection array be set to one to two in a region or time period in which low insolation intensity is distributed in greater amount. In the case where high insolation intensity is distributed in a greater amount, setting it to two to three is preferable. By using the structured design method and the HASP Tokyo data, thermoelectric element modules were interconnected with 35 modules in series and two in parallel on a cooling panel installed on the roof of the Science University of Tokyo. A simulation result revealed that the average temperature difference on the cooled surface in summer is 4.37 degC, and the solar cell utilization rate is 0.67. It is necessary in the future to improve heat dissipation efficiency and area ratio. 1 ref., 12 figs., 5 tabs.

  4. Energy efficiency and indoor thermal perception. A comparative study between radiant panel and portable convective heaters

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Ahmed Hamza H.; Morsy, Mahmoud Gaber [Department of Mechanical Engineering, Faculty of Engineering, Assiut University, Assiut, 71516 (Egypt)

    2010-11-15

    This study investigates experimentally the thermal perception of indoor environment for evaluating the ability of radiant panel heaters to produce thermal comfort for space occupants as well as the energy consumption in comparison with conventional portable natural convective heaters. The thermal perception results show that, compared with conventional convection heater, a radiantly heated office room maintains a lower ambient air temperature while providing equal levels of thermal perception on the thermal dummy head as the convective heater and saves up to 39.1% of the energy consumption per day. However, for human subjects' vote experiments, the results show that for an environmentally controlled test room at outdoor environment temperatures of 0C and 5C, using two radiant panel heaters with a total capacity of 580 W leads to a better comfort sensation than the conventional portable natural convective heater with a 670 W capacity, with an energy saving of about 13.4%. In addition, for an outdoor environment temperature of 10C, using one radiant panel heater with a capacity of 290 W leads to a better comfort sensation than the conventional convection heater with a 670 W capacity, with an energy saving of about 56.7%. From the analytical results, it is found that distributing the radiant panel heater inside the office room, one on the wall facing the window and the other on the wall close to the window, provides the best operative temperature distribution within the room.

  5. Radiant heat transfer during the natural evaporation from free surfaces exposed to solar radiation; Transferencia de calor radiante durante a evaporacao natural em superficies livres expostas a radiacao solar

    Energy Technology Data Exchange (ETDEWEB)

    Teixeira, C O.M. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia; Hackenberg, C M [Universidade Federal do Rio de Janeiro, RJ (Brazil). Escola de Quimica

    1985-12-31

    In this work a conductive-convective-radiant model which includes phase change behavior, is developed in order to determine the rate of evaporation from free surface exposed to solar radiation and consequently the most important parameters, and their effects, on the design of salt solutions concentrating natural evaporation reservoirs may be analysed. The numerical solutions of the resulting of system of equations are shown to represent very well the experimental results measured on evaporation chambers specially built for daily operations. The thermal effect of spectrally selective surfaces as coating agents for the reservoir is also analysed. (author). 11 refs., 8 figs

  6. A controlled, randomized, comparative study of a radiant heat bandage on the healing of stage 3-4 pressure ulcers: a pilot study.

    Science.gov (United States)

    Thomas, David R; Diebold, Marilyn R; Eggemeyer, Linda M

    2005-01-01

    Pressure ulcers, like other chronic wounds, fail to proceed through an orderly and timely process to produce anatomical or functional integrity. Treatment of pressure ulcers is directed to improving host factors and providing an optimum wound environment. In addition to providing a moist wound environment, it has been theorized that preventing hypothermia in a wound and maintaining a normothermic state might improve wound healing. Forty-one subjects with a stage 3 or stage 4 truncal pressure ulcer >1.0 cm(2) were recruited from outpatient clinics, long-term care nursing homes, and a rehabilitation center. The experimental group was randomized to a radiant-heat dressing device and the control group was randomized to a hydrocolloid dressing, with or without a calcium alginate filler. Subjects were followed until healed or for 12 weeks. Eight subjects (57%) in the experimental group had complete healing of their pressure ulcer compared with 7 subjects (44%) with complete healing in the control group (P = .46). Although a 13% difference in healing rate between the two arms of the study was found, this difference was not statistically significant. At almost all points along the healing curve, the proportion not healed was higher in the control arm.

  7. Air-To-Water Heat Pumps with Radiant Delivery in Low Load Homes: Tucson, Arizona and Chico, California (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2013-11-01

    Space conditioning represents nearly 50% of average residential household energy consumption, highlighting the need to identify alternative cost-effective, energy-efficient cooling and heating strategies. As homes are better built, there is an increasing need for strategies that are particularly well suited for high performance, low load homes. ARBI researchers worked with two test homes in hot-dry climates to evaluate the in-situ performance of air-to-water heat pump (AWHP) systems, an energy efficient space conditioning solution designed to cost-effectively provide comfort in homes with efficient, safe, and durable operation. Two monitoring projects of test houses in hot-dry climates were initiated in 2010 to test this system. Both systems were fully instrumented and have been monitored over one year to capture complete performance data over the cooling and heating seasons. Results are used to quantify energy savings, cost-effectiveness, and system performance using different operating modes and strategies. A calibrated TRNSYS model was developed and used to evaluate performance in various climate regions. This strategy is most effective in tight, insulated homes with high levels of thermal mass (i.e. exposed slab floors).

  8. High temperature heat exchange: nuclear process heat applications

    International Nuclear Information System (INIS)

    Vrable, D.L.

    1980-09-01

    The unique element of the HTGR system is the high-temperature operation and the need for heat exchanger equipment to transfer nuclear heat from the reactor to the process application. This paper discusses the potential applications of the HTGR in both synthetic fuel production and nuclear steel making and presents the design considerations for the high-temperature heat exchanger equipment

  9. Radiant absorption characteristics of corrugated curved tubes

    Directory of Open Access Journals (Sweden)

    Đorđević Milan Lj.

    2017-01-01

    Full Text Available The utilization of modern paraboloidal concentrators for conversion of solar radiation into heat energy requires the development and implementation of compact and efficient heat absorbers. Accurate estimation of geometry influence on absorption characteristics of receiver tubes is an important step in this process. This paper deals with absorption characteristics of heat absorber made of spirally coiled tubes with transverse circular corrugations. Detailed 3-D surface-to-surface Hemicube method was applied to compare radiation performances of corrugated and smooth curved tubes. The numerical results were obtained by varying the tube curvature ratio and incident radiant heat flux intensity. The details of absorption efficiency of corrugated tubes and the effect of curvature on absorption properties for both corrugated and smooth tubes were presented. The results may have significance to further analysis of highly efficient heat absorbers exposed to concentrated radiant heating. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 42006

  10. Experimental evaluation of an active solar thermoelectric radiant wall system

    International Nuclear Information System (INIS)

    Liu, ZhongBing; Zhang, Ling; Gong, GuangCai; Han, TianHe

    2015-01-01

    Highlights: • A novel active solar thermoelectric radiant wall are proposed and tested. • The novel wall can control thermal flux of building envelope by using solar energy. • The novel wall can eliminate building envelop thermal loads and provide cooling capacity for space cooling. • Typical application issues including connection strategies, coupling with PV system etc. are discussed. - Abstract: Active solar thermoelectric radiant wall (ASTRW) system is a new solar wall technology which integrates thermoelectric radiant cooling and photovoltaic (PV) technologies. In ASTRW system, a PV system transfers solar energy directly into electrical energy to power thermoelectric cooling modes. Both the thermoelectric cooling modes and PV system are integrated into one enclosure surface as radiant panel for space cooling and heating. Hence, ASTRW system presents fundamental shift from minimizing building envelope energy losses by optimizing the insulation thickness to a new regime where active solar envelop is designed to eliminate thermal loads and increase the building’s solar gains while providing occupant comfort in all seasons. This article presents an experimental study of an ASTRW system with a dimension of 1580 × 810 mm. Experimental results showed that the inner surface temperature of the ASTRW is 3–8 °C lower than the indoor temperature of the test room, which indicated that the ASTRW system has the ability to control thermal flux of building envelope by using solar energy and reduce the air conditioning system requirements. Based on the optimal operating current of TE modules and the analysis based upon PV modeling theories, the number and type of the electrical connections for the TE modules in ASTRW system are discussed in order to get an excellent performance in the operation of the ASTRW system

  11. Heat Transfer in Metal Foam Heat Exchangers at High Temperature

    Science.gov (United States)

    Hafeez, Pakeeza

    Heat transfer though open-cell metal foam is experimentally studied for heat exchanger and heat shield applications at high temperatures (˜750°C). Nickel foam sheets with pore densities of 10 and 40 pores per linear inch (PPI), have been used to make the heat exchangers and heat shields by using thermal spray coating to deposit an Inconel skin on a foam core. Heat transfer measurements were performed on a test rig capable of generating hot gas up to 1000°C. The heat exchangers were tested by exposing their outer surface to combustion gases at a temperature of 550°C and 750°C while being cooled by air flowing through them at room temperature at velocities up to 5 m/s. The temperature rise of the air, the surface temperature of the heat exchangers and the air temperature inside the heat exchanger were measured. The volumetric heat transfer coefficient and Nusselt number were calculated for different velocities. The heat transfer performance of the 40PPI sample brazed with the foil is found to be the most efficient. Pressure drop measurements were also performed for 10 and 40PPI metal foam. Thermographic measurements were done on 40PPI foam heat exchangers using a high temperature infrared camera. A high power electric heater was used to produce hot air at 300°C that passed over the foam heat exchanger while the cooling air was blown through it. Heat shields were made by depositing porous skins on metal foam and it was observed that a small amount of coolant leaking through the pores notably reduces the heat transfer from the hot gases. An analytical model was developed based assuming local thermal non-equilibrium that accounts for the temperature difference between solid and fluid phase. The experimental results are found to be in good agreement with the predicted values of the model.

  12. An oral TRPV1 antagonist attenuates laser radiant-heat-evoked potentials and pain ratings from UV(B)-inflamed and normal skin.

    Science.gov (United States)

    Schaffler, Klaus; Reeh, Peter; Duan, W Rachel; Best, Andrea E; Othman, Ahmed A; Faltynek, Connie R; Locke, Charles; Nothaft, Wolfram

    2013-02-01

    Laser (radiant-heat) evoked potentials (LEPs) from vertex-EEG peak-to-peak (PtP) amplitude were used to determine acute antinociceptive/antihyperalgesic efficacy of ABT-102, a novel TRPV1 antagonist efficacious in preclinical pain models, compared with active controls and placebo in normal and UV(B)-inflamed skin. This was a randomized, placebo- and active-controlled, double-blind, intra-individual, crossover trial. Twenty-four healthy subjects received six sequences of single doses of ABT-102 (0.5, 2, 6 mg), etoricoxib 90 mg, tramadol 100 mg and placebo. Painful stimuli were induced by CO(2) -laser on normal and UV(B) -inflamed skin. LEPs and visual analogue scale (VAS-pain) ratings were taken at baseline and hourly up to 8 h post-dose from both skin types. Compared with placebo, significant mean decreases in the primary variable of LEP PtP-amplitude from UV(B)-inflamed skin were observed with ABT-102 6 mg (P < 0.001), ABT-102 2 mg (P = 0.002), tramadol 100 mg (P < 0.001), and etoricoxib 90 mg (P = 0.001) over the 8 h period; ABT-102 0.5 mg was similar to placebo. ABT-102 6 mg was superior to active controls over the 8 h period (P < 0.05) whereas ABT-102 2 mg was comparable. Improvements in VAS scores compared with placebo were observed with ABT-102 6 mg (P < 0.001) and ABT-102 2 mg (P = 0.002). ABT-102 average plasma concentrations were 1.3, 4.4 and 9.4 ng ml(-1) for the 0.5, 2 and 6 mg doses, respectively. There were no clinically significant safety findings. TRPV-1 antagonism appears promising in the management of clinical pain, but requires further investigation. © 2012 Abbott. British Journal of Clinical Pharmacology © 2012 The British Pharmacological Society.

  13. High temperature absorption compression heat pump for industrial waste heat

    DEFF Research Database (Denmark)

    Reinholdt, Lars; Horntvedt, B.; Nordtvedt, S. R.

    2016-01-01

    Heat pumps are currently receiving extensive interest because they may be able to support the integration of large shares of fluctuating electricity production based on renewable sources, and they have the potential for the utilization of low temperature waste heat from industry. In most industries......, the needed temperature levels often range from 100°C and up, but until now, it has been quite difficult to find heat pump technologies that reach this level, and thereby opening up the large-scale heat recovery in the industry. Absorption compression heat pumps can reach temperatures above 100°C......, and they have proved themselves a very efficient and reliable technology for applications that have large temperature changes on the heat sink and/or heat source. The concept of Carnot and Lorenz efficiency and its use in the analysis of system integration is shown. A 1.25 MW system having a Carnot efficiency...

  14. High temperature alloys and ceramic heat exchanger

    International Nuclear Information System (INIS)

    Okamoto, Masaharu

    1984-04-01

    From the standpoint of energy saving, the future operating temperatures of process heat and gas turbine plants will become higher. For this purpose, ceramics is the most promissing candidate material in strength for application to high-temperature heat exchangers. This report deals with a servey of characteristics of several high-temperature metallic materials and ceramics as temperature-resistant materials; including a servey of the state-of-the-art of ceramic heat exchanger technologies developed outside of Japan, and a study of their application to the intermediate heat exchanger of VHTR (a very-high-temperature gas-cooled reactor). (author)

  15. The effects of mixing air distribution and heat load arrangement on the performance of ceiling radiant panels under cooling mode of operation

    DEFF Research Database (Denmark)

    Mustakallio, Panu; Kosonen, Risto; Melikov, Arsen Krikor

    2016-01-01

    arrangement and air distribution generated in a room by linear slot diffuser, radial multi-nozzle diffuser and radial swirl induction unit on the cooling power of radiant panels was compared. The impact on the thermal environment was also studied. Measurements were carried out without and with supply air...

  16. High temperature thermoacoustic heat pump

    Energy Technology Data Exchange (ETDEWEB)

    Tijani, H.; Spoelstra, S. [Energy research Centre of the Netherlands, 1755 ZG Petten (Netherlands)

    2012-06-15

    Thermoacoustic technology can provide new types of heat pumps that can be deployed in different applications. A thermoacoustic heat pumps can for example be applied in dwellings to generate cooling or heating. Typically, space and water heating makes up about 60% of domestics and offices energy consumption. The application of heat pumps can contribute to achieve energy savings and environmental benefits by reducing CO2 and NOx emissions. This paper presents the study of a laboratory scale thermoacoustic-Stirling heat pump operating between 10C and 80C which can be applied in domestics and offices. The heat pump is driven by a thermoacoustic-Stirling engine. The experimental results show that the heat pump pumps 250 W of heat at 60C at a drive ratio of 3.6% and 200 W at 80C at a drive ratio of 3.5 %. The performance for both cases is about 40% of the Carnot performance. The design, construction, and performance measurements of the heat pump will be presented and discussed.

  17. High Temperature Thermoacoustic Heat Pump

    Energy Technology Data Exchange (ETDEWEB)

    Tijani, H.; Spoelstra, S. [ECN Biomass and Energy Efficiency, Petten (Netherlands)

    2012-07-15

    Thermoacoustic technology can provide new types of heat pumps that can be deployed in different applications. Thermoacoustic heat pumps can for example be applied in dwellings to generate cooling or heating. Typically, space and water heating makes up about 60% of domestic and office energy consumption. The application of heat pumps can contribute to achieve energy savings and environmental benefits by reducing CO2 and NOx emissions. This paper presents the study of a laboratory scale thermoacoustic-Stirling heat pump operating between 10C and 80C which can be applied in domestics and offices. The heat pump is driven by a thermoacoustic-Stirling engine. The experimental results show that the heat pump pumps 250 W of heat at 60C at a drive ratio of 3.6 % and 200 W at 80C at a drive ratio of 3.5 %. The performance for both cases is about 40% of the Carnot performance. The design, construction, and performance measurements of the heat pump will be presented and discussed.

  18. Novikov Engine with Fluctuating Heat Bath Temperature

    Science.gov (United States)

    Schwalbe, Karsten; Hoffmann, Karl Heinz

    2018-04-01

    The Novikov engine is a model for heat engines that takes the irreversible character of heat fluxes into account. Using this model, the maximum power output as well as the corresponding efficiency of the heat engine can be deduced, leading to the well-known Curzon-Ahlborn efficiency. The classical model assumes constant heat bath temperatures, which is not a reasonable assumption in the case of fluctuating heat sources. Therefore, in this article the influence of stochastic fluctuations of the hot heat bath's temperature on the optimal performance measures is investigated. For this purpose, a Novikov engine with fluctuating heat bath temperature is considered. Doing so, a generalization of the Curzon-Ahlborn efficiency is found. The results can help to quantify how the distribution of fluctuating quantities affects the performance measures of power plants.

  19. Integrated Temperature Sensors based on Heat Diffusion

    NARCIS (Netherlands)

    Van Vroonhoven, C.P.L.

    2015-01-01

    This thesis describes the theory, design and implementation of a new class of integrated temperature sensors, based on heat diffusion. In such sensors, temperature is sensed by measuring the time it takes for heat to diffuse through silicon. An on-chip thermal delay can be determined by geometry and

  20. Sensitivity analysis of the thermal performance of radiant and convective terminals for cooling buildings

    DEFF Research Database (Denmark)

    Le Dréau, J.; Heiselberg, P.

    2014-01-01

    Heating and cooling terminals can be classified in two main categories: convective terminals (e.g. active chilled beam, air conditioning) and radiant terminals. The mode of heat transfer of the two emitters is different: the first one is mainly based on convection, whereas the second one is based...... conducted to determine the parameters influencing their thermal performance the most. The air change rate, the outdoor temperature and the air temperature stratification have the largest effect on the cooling need (maintaining a constant operative temperature). For air change rates higher than 0.5 ACH...

  1. 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.

  2. Design manual. [High temperature heat pump for heat recovery system

    Energy Technology Data Exchange (ETDEWEB)

    Burch, T.E.; Chancellor, P.D.; Dyer, D.F.; Maples, G.

    1980-01-01

    The design and performance of a waste heat recovery system which utilizes a high temperature heat pump and which is intended for use in those industries incorporating indirect drying processes are described. It is estimated that use of this heat recovery system in the paper, pulp, and textile industries in the US could save 3.9 x 10/sup 14/ Btu/yr. Information is included on over all and component design for the heat pump system, comparison of prime movers for powering the compressor, control equipment, and system economics. (LCL)

  3. Radiant energy collection and conversion apparatus and method

    Science.gov (United States)

    Hunt, A.J.

    The apparatus for collecting radiant energy and converting to alternate energy forms includes a housing having an interior space and a radiation transparent window allowing solar radiation to be received in the interior space of the housing. Means are provided for passing a stream of fluid past the window and for injecting radiation absorbent particles in said fluid stream. The particles absorb the radiation and because of their very large surface area, quickly release the heat to the surrounding fluid stream. The fluid stream particle mixture is heated until the particles vaporize. The fluid stream is then allowed to expand in, for example, a gas turbine to produce mechanical energy. In an aspect of the present invention properly sized particles need not be vaporized prior to the entrance of the fluid stream into the turbine, as the particles will not damage the turbine blades. In yet another aspect of the invention, conventional fuel injectors are provided to inject fuel into the fluid stream to maintain the proper temperature and pressure of the fluid stream should the source of radiant energy be interrupted. In yet another aspect of the invention, an apparatus is provided which includes means for providing a hot fluid stream having hot particles disbursed therein which can radiate energy, means for providing a cooler fluid stream having cooler particles disbursed therein, which particles can absorb radiant energy and means for passing the hot fluid stream adjacent the cooler fluid stream to warm the cooler fluid and cooler particles by the radiation from the hot fluid and hot particles.

  4. Medium Deep High Temperature Heat Storage

    Science.gov (United States)

    Bär, Kristian; Rühaak, Wolfram; Schulte, Daniel; Welsch, Bastian; Chauhan, Swarup; Homuth, Sebastian; Sass, Ingo

    2015-04-01

    Heating of buildings requires more than 25 % of the total end energy consumption in Germany. Shallow geothermal systems for indirect use as well as shallow geothermal heat storage systems like aquifer thermal energy storage (ATES) or borehole thermal energy storage (BTES) typically provide low exergy heat. The temperature levels and ranges typically require a coupling with heat pumps. By storing hot water from solar panels or thermal power stations with temperatures of up to 110 °C a medium deep high temperature heat storage (MDHTS) can be operated on relatively high temperature levels of more than 45 °C. Storage depths of 500 m to 1,500 m below surface avoid conflicts with groundwater use for drinking water or other purposes. Permeability is typically also decreasing with greater depth; especially in the crystalline basement therefore conduction becomes the dominant heat transport process. Solar-thermal charging of a MDHTS is a very beneficial option for supplying heat in urban and rural systems. Feasibility and design criteria of different system configurations (depth, distance and number of BHE) are discussed. One system is designed to store and supply heat (300 kW) for an office building. The required boreholes are located in granodioritic bedrock. Resulting from this setup several challenges have to be addressed. The drilling and completion has to be planned carefully under consideration of the geological and tectonical situation at the specific site.

  5. PERFORMANCE EVALUATION OF CEILING RADIANT COOLING SYSTEM IN COMPOSITE CLIMATE

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Anuj [Malaviya National Institute of Technology (MNIT), Jaipur, India; Mathur, Jyotirmay [Malaviya National Institute of Technology (MNIT), Jaipur, India; Bhandari, Mahabir S [ORNL

    2015-01-01

    Radiant cooling systems are proving to be an energy efficient solution due to higher thermal capacity of cooling fluid especially for the buildings that require individual zone controls and where the latent loads are moderate. The Conventional air conditioners work at very low temperature i.e.5-8 c (refrigerant evaporator inlet) while the radiant cooling systems, also referred as high temperature cooling system, work at high temperatures i.e. 14-18 c. The radiant cooling systems can maintain lower MRT (Mean Radiant Temperature) as ceiling panels maintain uniform temperature gradient inside room and provide higher human comfort. The radiant cooling systems are relatively new systems and their operation and energy savings potential are not quantified for a large number of buildings and operational parameters. Moreover, there are only limited numbers of whole building simulation studies have been carried out for these systems to have a full confidence in the capability of modelling tools to simulate these systems and predict the impact of various operating parameters. Theoretically, savings achieve due to higher temperature set point of chilled water, which reduces chiller-running time. However, conventional air conditioner runs continuously to maintain requisite temperature. In this paper, experimental study for performance evaluation of radiant cooling system carried out on system installed at Malaviya National Institute of Technology Jaipur. This paper quantifies the energy savings opportunities and effective temperature by radiant cooling system at different chilled water flow rates and temperature range. The data collected/ analysed through experimental study will used for calibration and validation of system model of building prepared in building performance simulation software. This validated model used for exploring optimized combinations of key parameters for composite climate. These optimized combinations will used in formulation of radiant cooling system

  6. Industrial waste heat utilization for low temperature district heating

    International Nuclear Information System (INIS)

    Fang, Hao; Xia, Jianjun; Zhu, Kan; Su, Yingbo; Jiang, Yi

    2013-01-01

    Large quantities of low grade waste heat are discharged into the environment, mostly via water evaporation, during industrial processes. Putting this industrial waste heat to productive use can reduce fossil fuel usage as well as CO 2 emissions and water dissipation. The purpose of this paper is to propose a holistic approach to the integrated and efficient utilization of low-grade industrial waste heat. Recovering industrial waste heat for use in district heating (DH) can increase the efficiency of the industrial sector and the DH system, in a cost-efficient way defined by the index of investment vs. carbon reduction (ICR). Furthermore, low temperature DH network greatly benefits the recovery rate of industrial waste heat. Based on data analysis and in-situ investigations, this paper discusses the potential for the implementation of such an approach in northern China, where conventional heat sources for DH are insufficient. The universal design approach to industrial-waste-heat based DH is proposed. Through a demonstration project, this approach is introduced in detail. This study finds three advantages to this approach: (1) improvement of the thermal energy efficiency of industrial factories; (2) more cost-efficient than the traditional heating mode; and (3) CO 2 and pollutant emission reduction as well as water conservation. -- Highlights: •We review situation of industrial waste heat recovery with a global perspective. •We present a way to analyze the potential to utilize industrial waste heat for DH. •Northern China has huge potential for using low-grade industrial waste heat for DH. •A demonstration project is introduced using the universal approach we propose. •It proves huge benefits for factories, heat-supply companies and the society

  7. Influence on Heat Transfer Coefficient of Heat Exchanger by Velocity and Heat Transfer Temperature Difference

    Directory of Open Access Journals (Sweden)

    WANG Fang

    2017-04-01

    Full Text Available Aimed to insufficient heat transfer of heat exchanger, research the influence on the heat transfer coefficient impacted by velocity and heat transfer temperature difference of tube heat exchanger. According to the different heat transfer temperature difference and gas velocity,the experimental data were divided into group. Using the control variable method,the above two factors were analyzed separately. K一△T and k一:fitting curve were clone to obtain empirical function. The entire heat exchanger is as the study object,using numerical simulation methods,porous media,k一£model,second order upwind mode,and pressure一velocity coupling with SIMPLE algorithm,the entire heat exchanger temperature field and the heat transfer coefficient distribution were given. Finally the trend of the heat transfer coefficient effected by the above two factors was gotten.

  8. Heat exchangers and recuperators for high temperature waste gases

    Science.gov (United States)

    Meunier, H.

    General considerations on high temperature waste heat recovery are presented. Internal heat recovery through combustion air preheating and external heat recovery are addressed. Heat transfer and pressure drop in heat exchanger design are discussed.

  9. Design and construction of a regenerative radiant tube burner

    International Nuclear Information System (INIS)

    Henao, Diego Alberto; Cano C, Carlos Andres; Amell Arrieta, Andres A.

    2002-01-01

    The technological development of the gas industry in Colombia, aiming at efficient and safe use of the natural gas, requires the assimilation and adaptation of new generation, technologies for this purpose in this article results are presented on the design, construction and characterization of a prototype of a burner of regenerative radiant robe with a thermal power of 9,94 kW and a factor of air 1,05. This system takes advantage of the high exit temperature of the combustion smokes, after they go trough a metallic robe where they transfer the heat by radiation, to heat a ceramic channel that has the capacity to absorbing a part of the heat of the smokes and then transferring them to a current of cold air. The benefits of air heating are a saving in fuel, compared with other processes that don't incorporate the recovery of heat from the combustion gases. In this work it was possible to probe a methodology for the design of this type of burners and to reach maximum temperatures of heating of combustion air of 377,9 centigrade degrees, using a material available in the national market, whose regenerative properties should be studied in depth

  10. Magnetic heat pumping near room temperature

    Science.gov (United States)

    Brown, G. V.

    1976-01-01

    It is shown that magnetic heat pumping can be made practical at room temperature by using a ferromagnetic material with a Curie point at or near operating temperature and an appropriate regenerative thermodynamic cycle. Measurements are performed which show that gadolinium is a resonable working material and it is found that the application of a 7-T magnetic field to gadolinium at the Curie point (293 K) causes a heat release of 4 kJ/kg under isothermal conditions or a temperature rise of 14 K under adiabatic conditions. A regeneration technique can be used to lift the load of the lattice and electronic heat capacities off the magnetic system in order to span a reasonable temperature difference and to pump as much entropy per cycle as possible

  11. Temperature distributions of a conductively heated filament

    International Nuclear Information System (INIS)

    Tamura, Koji; Ohba, Hironori; Shibata, Takemasa

    1999-07-01

    Temperature distributions of a heated filament were measured. A W-Re(5%) filament (0.25 mm in diameter, 24.7 mm in length) was conductively heated by currents between 5A and 7A with a DC power supply, and the surface of the filament was imaged with a charge coupled device (CCD) camera through a monochromatic filter. The spectral radiation intensity at the filament center region was almost uniform. Since the temperature distribution was also uniform and the energy loss by thermal conduction was negligible, temperature in this region was determined from the energy balance between applied power and radiation loss. Temperature distribution of the filament was determined based on the Planck's law of radiation from the spectral radiation intensity ratio of the filament surface using obtained temperature as a reference. It was found that temperature distribution of a filament was easily measured by this method. (author)

  12. 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...

  13. Radiant exchange in partially specular architectural environments

    Science.gov (United States)

    Beamer, C. Walter; Muehleisen, Ralph T.

    2003-10-01

    The radiant exchange method, also known as radiosity, was originally developed for thermal radiative heat transfer applications. Later it was used to model architectural lighting systems, and more recently it has been extended to model acoustic systems. While there are subtle differences in these applications, the basic method is based on solving a system of energy balance equations, and it is best applied to spaces with mainly diffuse reflecting surfaces. The obvious drawback to this method is that it is based around the assumption that all surfaces in the system are diffuse reflectors. Because almost all architectural systems have at least some partially specular reflecting surfaces in the system it is important to extend the radiant exchange method to deal with this type of surface reflection. [Work supported by NSF.

  14. Numerical Simulation of the Thermal Process in a W-Shape Radiant Tube Burner

    Science.gov (United States)

    Wang, Yi; Li, Jiyong; Zhang, Lifeng; Ling, Haitao; Li, Yanlong

    2014-07-01

    In the current work, three-dimensional mathematical models were developed for the heat transfer and combustion in a W-shape radiant tube burner (RTB) and were solved using Fluent software (ANSYS Inc., Canonsburg, PA). The standard k- ɛ model, nonpremixed combustion model, and the discrete ordinate model were used for the modeling of turbulence, combustion, and radiant heat transfer, respectively. In addition, the NO x postprocessor was used for the prediction of the NO emission. A corresponding experiment was performed for the validation of mathematical models. The details of fluid flow, heat transfer, and combustion in the RTB were investigated. Moreover, the effect of the air/fuel ratio (A/F) and air staging on the performance of RTB was studied with the reference indexes including heat efficiency, maximum temperature difference on shell wall, and NO emission at the outlet. The results indicated that a low speed zone formed in the vicinity of the combustion chamber outlet, and there were two relative high-temperature zones in the RTB, one in combustion chamber that favored the flame stability and the other from the main flame in the RTB. The maximum temperature difference was 95.48 K. As the A/F increased, the temperature increased first and then decreased. As the ratio of the primary to secondary air increased, the recirculation zone at the outlet of combustion chamber shrank gradually to disappear, and the flame length was longer and the temperature in flame decreased correspondingly.

  15. Thermal model of attic systems with radiant barriers

    Energy Technology Data Exchange (ETDEWEB)

    Wilkes, K.E.

    1991-07-01

    This report summarizes the first phase of a project to model the thermal performance of radiant barriers. The objective of this phase of the project was to develop a refined model for the thermal performance of residential house attics, with and without radiant barriers, and to verify the model by comparing its predictions against selected existing experimental thermal performance data. Models for the thermal performance of attics with and without radiant barriers have been developed and implemented on an IBM PC/AT computer. The validity of the models has been tested by comparing their predictions with ceiling heat fluxes measured in a number of laboratory and field experiments on attics with and without radiant barriers. Cumulative heat flows predicted by the models were usually within about 5 to 10 percent of measured values. In future phases of the project, the models for attic/radiant barrier performance will be coupled with a whole-house model and further comparisons with experimental data will be made. Following this, the models will be utilized to provide an initial assessment of the energy savings potential of radiant barriers in various configurations and under various climatic conditions. 38 refs., 14 figs., 22 tabs.

  16. Measurement of radiant properties of ceramic foam

    International Nuclear Information System (INIS)

    Hoornstra, J.; Turecky, M.; Maatman, D.

    1994-07-01

    An experimental facility is described for the measurement of the normal spectral and total emissivity and transmissivity of semi-transparent materials in the temperature range of 600 C to 1200 C. The set-up was used for the measurement of radiation properties of highly porous ceramic foam which is used in low NO x radiant burners. Emissivity and transmissivity data were measured and are presented for coated and uncoated ceramic foam of different thicknesses. (orig.)

  17. Application of a radiant heat transfer model to complex industrial reactive flows: combustion chambers, electric arcs; Application d`un modele de transfert radiatif a des ecoulements reactifs industriels complexes: chambres de combustion, arcs electriques

    Energy Technology Data Exchange (ETDEWEB)

    Mechitoua, N; Dalsecco, S; Delalondre, C; Simonin, O [Electricite de France (EDF), 78 - Chatou (France). Lab. National d` Hydraulique

    1997-12-31

    The direction of studies and researches (DER) of Electricite de France (EdF) has been involved for several years in a research program on turbulent reactive flows. The objectives of this program concern: the reduction of pollutant emissions from existing fossil-fueled power plants, the study of new production means (fluidized beds), and the promotion of electric power applications in the industry. An important part of this program is devoted to the development and validation of 3-D softwares and to the modeling of physical phenomena. This paper presents some industrial applications (furnaces, boilers, electric arcs) for which radiant heat transfers play an important role and the radiation models used. (J.S.) 8 refs.

  18. Application of a radiant heat transfer model to complex industrial reactive flows: combustion chambers, electric arcs; Application d`un modele de transfert radiatif a des ecoulements reactifs industriels complexes: chambres de combustion, arcs electriques

    Energy Technology Data Exchange (ETDEWEB)

    Mechitoua, N.; Dalsecco, S.; Delalondre, C.; Simonin, O. [Electricite de France (EDF), 78 - Chatou (France). Lab. National d`Hydraulique

    1996-12-31

    The direction of studies and researches (DER) of Electricite de France (EdF) has been involved for several years in a research program on turbulent reactive flows. The objectives of this program concern: the reduction of pollutant emissions from existing fossil-fueled power plants, the study of new production means (fluidized beds), and the promotion of electric power applications in the industry. An important part of this program is devoted to the development and validation of 3-D softwares and to the modeling of physical phenomena. This paper presents some industrial applications (furnaces, boilers, electric arcs) for which radiant heat transfers play an important role and the radiation models used. (J.S.) 8 refs.

  19. Radiant Ceiling Panels Combined with Localized Methods for Improved Thermal Comfort of Both Patient and Medical Staff in Patient Room

    DEFF Research Database (Denmark)

    Mori, Sakura; Barova, Mariya; Bolashikov, Zhecho Dimitrov

    2012-01-01

    The objectives were to identify whether ceiling installed radiant heating panels can provide thermal comfort to the occupants in a patient room, and to determine a method for optimal thermal environment to both patient and medical staff simultaneously. The experiments were performed in a climate...... mattress were used to provide local heating for the patient. The effects of the methods were identified by comparing the manikin based equivalent temperatures. The optimal thermal comfort level for both patient and medical staff would obtained when two conventional cotton blankets were used with extra...... chamber resembling a single-bed patient room under convective air conditioning alone or combined with the ceiling installed radiant heating panels. Two thermal manikins simulated a patient lying in the bed and a doctor standing next to the patient. Conventional cotton blanket, electric blanket, electric...

  20. Desalination by very low temperature nuclear heat

    International Nuclear Information System (INIS)

    Saari, Risto

    1977-01-01

    A new sea water desalination method has been developed: Nord-Aqua Vacuum Evaporation, which utilizes waste heat at a very low temperature. The requisite vacuum is obtained by the aid of a barometric column and siphon, and the dissolved air is removed from the vacuum by means of water flows. According to test results from a pilot plant, the process is operable if the waste heat exists at a temperature 7degC higher than ambient. The pumping energy which is then required is 9 kcal/kg, or 1.5% of the heat of vaporization of water. Calculations reveal that the method is economically considerably superior to conventional distilling methods. (author)

  1. Assessing heat exchanger performance data using temperature ...

    African Journals Online (AJOL)

    In addition, any calculated performance acceptance criteria must also consider uncertainty and error in the experimental measurements of temperature and flow. However, most statistical methods are complex and not easily applied to heat exchangers such as those that serve the power plant industry where data are difficult ...

  2. Heat transfer and temperature distribution in fuel

    International Nuclear Information System (INIS)

    Katanic-Popovic, J.; Stevanovic, M.

    1966-01-01

    This paper describes methods and procedures for determining the integral, mean and effective heat conductivity and temperature distribution in fuel, with the experimental solutions for measuring these parameters. A procedure for measuring the integral conductivity by measuring the power generated in the fuel is given [sr

  3. Radiant-and-plasma technology for coal processing

    Directory of Open Access Journals (Sweden)

    Vladimir Messerle

    2012-12-01

    Full Text Available Radiant-and-plasma technology for coal processing is presented in the article. Thermodynamic computation and experiments on plasma processing of bituminous coal preliminary electron-beam activated were fulfilled in comparison with plasma processing of the coal. Positive influence of the preliminary electron-beam activation of coal on synthesis gas yield was found. Experiments were carried out in the plasma gasifier of 100 kW power. As a result of the measurements of material and heat balance of the process gave the following integral indicators: weight-average temperature of 2200-2300 K, and carbon gasification degree of 82,4-83,2%. Synthesis gas yield at thermochemical preparation of raw coal dust for burning was 24,5% and in the case of electron-beam activation of coal synthesis gas yield reached 36,4%, which is 48% higher.

  4. Measurement of low-temperature specific heat

    International Nuclear Information System (INIS)

    Stewart, G.R.

    1983-01-01

    The measurement of low-temperature specific heat (LTSH) (0.1 K< T<60 K) has seen a number of breakthroughs both in design concepts and instrumentation in the last 15 years: particularly in small sample calorimetry. This review attempts to provide an overview of both large and small sample calorimetry techniques at temperatures below 60 K, with sufficient references to enable more detailed study. A comprehensive review is made of the most reliable measurements of the LTSH of 84 of the elements to illustrate briefly some of the problems of measurements and analysis, as well as to provide additional references. More detail is devoted to three special areas of low-temperature calorimetry that have seen rapid development recently: (1) measurement of the specific heat of highly radioactive samples, (2) measurement of the specific heat of materials in high magnetic fields (18 T), and (3) measurement of the specific heat of very small (100 μg) samples. The review ends with a brief discussion of the frontier research currently underway on microcalorimetry for nanogram sample weights

  5. Cyclic high temperature heat storage using borehole heat exchangers

    Science.gov (United States)

    Boockmeyer, Anke; Delfs, Jens-Olaf; Bauer, Sebastian

    2016-04-01

    The transition of the German energy supply towards mainly renewable energy sources like wind or solar power, termed "Energiewende", makes energy storage a requirement in order to compensate their fluctuating production and to ensure a reliable energy and power supply. One option is to store heat in the subsurface using borehole heat exchangers (BHEs). Efficiency of thermal storage is increasing with increasing temperatures, as heat at high temperatures is more easily injected and extracted than at temperatures at ambient levels. This work aims at quantifying achievable storage capacities, storage cycle times, injection and extraction rates as well as thermal and hydraulic effects induced in the subsurface for a BHE storage site in the shallow subsurface. To achieve these aims, simulation of these highly dynamic storage sites is performed. A detailed, high-resolution numerical simulation model was developed, that accounts for all BHE components in geometrical detail and incorporates the governing processes. This model was verified using high quality experimental data and is shown to achieve accurate simulation results with excellent fit to the available experimental data, but also leads to large computational times due to the large numerical meshes required for discretizing the highly transient effects. An approximate numerical model for each type of BHE (single U, double U and coaxial) that reduces the number of elements and the simulation time significantly was therefore developed for use in larger scale simulations. The approximate numerical model still includes all BHE components and represents the temporal and spatial temperature distribution with a deviation of less than 2% from the fully discretized model. Simulation times are reduced by a factor of ~10 for single U-tube BHEs, ~20 for double U-tube BHEs and ~150 for coaxial BHEs. This model is then used to investigate achievable storage capacity, injection and extraction rates as well as induced effects for

  6. Heating tar sands formations to visbreaking temperatures

    Science.gov (United States)

    Karanikas, John Michael [Houston, TX; Colmenares, Tulio Rafael [Houston, TX; Zhang, Etuan [Houston, TX; Marino, Marian [Houston, TX; Roes, Augustinus Wilhelmus Maria [Houston, TX; Ryan, Robert Charles [Houston, TX; Beer, Gary Lee [Houston, TX; Dombrowski, Robert James [Houston, TX; Jaiswal, Namit [Houston, TX

    2009-12-22

    Methods for treating a tar sands formation are described herein. Methods may include heating at least a section of a hydrocarbon layer in the formation from a plurality of heaters located in the formation. The heat may be controlled so that at least a majority of the section reaches an average temperature of between 200.degree. C. and 240.degree. C., which results in visbreaking of at least some hydrocarbons in the section. At least some visbroken hydrocarbon fluids may be produced from the formation.

  7. Integration of space heating and hot water supply in low temperature district heating

    DEFF Research Database (Denmark)

    Elmegaard, Brian; Ommen, Torben Schmidt; Markussen, Michael

    2016-01-01

    District heating may supply many consumers efficiently, but the heat loss from the pipes to the ground is a challenge. The heat loss may be lowered by decreasing the network temperatures for which reason low temperature networks are proposed for future district heating. The heating demand...... of the consumers involves both domestic hot water and space heating. Space heating may be provided at low temperature in low energy buildings. Domestic hot water, however, needs sufficient temperatures to avoid growth of legionella. If the network temperature is below the demand temperature, supplementary heating...... is required by the consumer. We study conventional district heating at different temperatures and compare the energy and exergetic efficiency and annual heating cost to solutions that utilize electricity for supplementary heating of domestic hot water in low temperature district heating. This includes direct...

  8. Self-heating, gamma heating and heat loss effects on resistance temperature detector (RTD) accuracy

    International Nuclear Information System (INIS)

    Qian, T.; Hinds, H.W.; Tonner, P.

    1997-01-01

    Resistance temperature detectors (RTDs) are extensively used in CANDU nuclear power stations for measuring various process and equipment temperatures. Accuracy of measurement is an important performance parameter of RTDs and has great impact on the thermal power efficiency and safety of the plant. There are a number of factors that contribute to some extent to RTD measurement error. Self-heating, gamma heating and the heat-loss throughout conduction of the thermowell are three of these factors. The degree to which these three affect accuracy of RTDs used for the measurement of reactor inlet header temperature (RIHT) has been analyzed and is presented in this paper. (author)

  9. High temperature nuclear heat for isothermal reformer

    International Nuclear Information System (INIS)

    Epstein, M.

    2000-01-01

    High temperature nuclear heat can be used to operate a reformer with various feedstock materials. The product synthesis gas can be used not only as a source for hydrogen and as a feedstock for many essential chemical industries, such as ammonia and other products, but also for methanol and synthetic fuels. It can also be burnt directly in a combustion chamber of a gas turbine in an efficient combined cycle and generate electricity. In addition, it can be used as fuel for fuel cells. The reforming reaction is endothermic and the contribution of the nuclear energy to the calorific value of the final product (synthesis gas) is about 25%, compared to the calorific value of the feedstock reactants. If the feedstock is from fossil origin, the nuclear energy contributes to a substantial reduction in CO 2 emission to the atmosphere. The catalytic steam reforming of natural gas is the most common process. However, other feedstock materials, such as biogas, landfill gas and CO 2 -contaminated natural gas, can be reformed as well, either directly or with the addition of steam. The industrial steam reformers are generally fixed bed reactors, and their performance is strongly affected by the heat transfer from the furnace to the catalyst tubes. In top-fired as well as side-fired industrial configurations of steam reformers, the radiation is the main mechanism of heat transfer and convection heat transfer is negligible. The flames and the furnace gas constitute the main sources of the heat. In the nuclear reformers developed primarily in Germany, in connection with the EVA-ADAM project (closed cycle), the nuclear heat is transferred from the nuclear reactor coolant gas by convection, using a heating jacket around the reformer tubes. In this presentation it is proposed that the helium in a secondary loop, used to cool the nuclear reactor, will be employed to evaporate intermediate medium, such as sodium, zinc and aluminum chloride. Then, the vapors of the medium material transfer

  10. Quantum Heat Engine and Negative Boltzmann Temperature

    International Nuclear Information System (INIS)

    Xi Jing-Yi; Quan Hai-Tao

    2017-01-01

    To clarify the ambiguity on negative Boltzmann temperature in literature, we study the Carnot and the Otto cycle with one of the heat reservoirs at the negative Boltzmann temperature based on a canonical ensemble description. The work extraction, entropy production and the efficiency of these cycles are explored. Conditions for constructing and properties of these thermodynamic cycles are elucidated. We find that the apparent “violation” of the second law of thermodynamics in these cycles are due to the fact that the traditional definition of thermodynamic efficiency is inappropriate in this situation. When properly understanding the efficiency and the adiabatic processes, in which the system crosses over “absolute ZERO” in a limit sense, the Carnot cycle with one of the heat reservoirs at a negative Boltzmann temperature can be understood straightforwardly, and it contradicts neither the second nor the third law of thermodynamics. Hence, negative Boltzmann temperature is a consistent concept in thermodynamics. We use a two-level system and an Ising spin system to illustrate our central results. (paper)

  11. Measured Performance of a Low Temperature Air Source Heat Pump

    Energy Technology Data Exchange (ETDEWEB)

    R.K. Johnson

    2013-09-01

    A 4-ton Low Temperature Heat Pump (LTHP) manufactured by Hallowell International was installed in a residence near New Haven, Connecticut and monitored over two winters of operation. After attending to some significant service issues, the heat pump operated as designed. This report should be considered a review of the dual compressor “boosted heat pump” technology. The Low Temperature Heat Pump system operates with four increasing levels of capacity (heat output) as the outdoor temperature drops.

  12. CDC WONDER: Daily Air Temperatures and Heat Index

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Daily Air Temperature and Heat Index data available on CDC WONDER are county-level daily average air temperatures and heat index measures spanning the years...

  13. Radiant non-catalytic recuperative reformer

    Energy Technology Data Exchange (ETDEWEB)

    Khinkis, Mark J.; Kozlov, Aleksandr P.

    2017-10-31

    A radiant, non-catalytic recuperative reformer has a flue gas flow path for conducting hot exhaust gas from a thermal process and a reforming mixture flow path for conducting a reforming mixture. At least a portion of the reforming mixture flow path is positioned adjacent to the flue gas flow path to permit heat transfer from the hot exhaust gas to the reforming mixture. The reforming mixture flow path contains substantially no material commonly used as a catalyst for reforming hydrocarbon fuel (e.g., nickel oxide, platinum group elements or rhenium), but instead the reforming mixture is reformed into a higher calorific fuel via reactions due to the heat transfer and residence time. In a preferred embodiment, a portion of the reforming mixture flow path is positioned outside of flue gas flow path for a relatively large residence time.

  14. Experimental measurement of variation of heat transfer coefficient and temperature gradients in 16'' deep fluidised beds

    International Nuclear Information System (INIS)

    Blacker, P.T.; McLain, D.R.

    1962-04-01

    The object of the experiments was to choose suitable particulate materials for a fluidised bed cooler, to test a deep fluidised bed for uniformity of heat transfer coefficient, and to explore the temperature distribution in a centrally heated annular fluidised bed. This memorandum records the techniques used and some of the practical aspects involved, together with the performance results obtained, for the assistance of other experimenters who may wish to use fluidised beds as a laboratory technique. Mathematical correlation of the results has not been attempted since some of the properties of the bed material were not known and to determine them was beyond the scope of the work programme. Rather, we have compared our results with those of other experimenters. Graphite tubes, for use in steady state thermal stress experiments, are to be heated by a graphite radiant heater situated in the bore and cooled on the outer surface. The tubes are 2 cm. bore, 8 cm. outside diameter and 48 cm. long. The outside temperature of the tubes is to be between 500 deg. C. and 1500 deg. C. It is estimated that the heat transfer rate required for fracture at the outer surface is 30 watts/cm 2 . This could readily be achieved by cooling with liquid metals, water or high velocity gas. However, serious problems of either materials compatibility or mechanical complexity make these undesirable. A water-cooled fluidised bed of compatible solids fluidised with nitrogen gas can overcome most of these problems and give heat transfer coefficients close to that required, vis. about 0.1 w/cm C . A coolant bed about 20'' long would be required and an annulus of about 2'' radial width round the specimen was considered to be practicable

  15. Experimental measurement of variation of heat transfer coefficient and temperature gradients in 16'' deep fluidised beds

    Energy Technology Data Exchange (ETDEWEB)

    Blacker, P T; McLain, D R [Reactor Development Division, Atomic Energy Establishment, Winfrith, Dorchester, Dorset (United Kingdom)

    1962-04-15

    The object of the experiments was to choose suitable particulate materials for a fluidised bed cooler, to test a deep fluidised bed for uniformity of heat transfer coefficient, and to explore the temperature distribution in a centrally heated annular fluidised bed. This memorandum records the techniques used and some of the practical aspects involved, together with the performance results obtained, for the assistance of other experimenters who may wish to use fluidised beds as a laboratory technique. Mathematical correlation of the results has not been attempted since some of the properties of the bed material were not known and to determine them was beyond the scope of the work programme. Rather, we have compared our results with those of other experimenters. Graphite tubes, for use in steady state thermal stress experiments, are to be heated by a graphite radiant heater situated in the bore and cooled on the outer surface. The tubes are 2 cm. bore, 8 cm. outside diameter and 48 cm. long. The outside temperature of the tubes is to be between 500 deg. C. and 1500 deg. C. It is estimated that the heat transfer rate required for fracture at the outer surface is 30 watts/cm{sup 2}. This could readily be achieved by cooling with liquid metals, water or high velocity gas. However, serious problems of either materials compatibility or mechanical complexity make these undesirable. A water-cooled fluidised bed of compatible solids fluidised with nitrogen gas can overcome most of these problems and give heat transfer coefficients close to that required, vis. about 0.1 w/cm C . A coolant bed about 20'' long would be required and an annulus of about 2'' radial width round the specimen was considered to be practicable.

  16. Innovative system for delivery of low temperature district heating

    OpenAIRE

    Ianakiev, A; Cui, JM; Garbett, S; Filer, A

    2017-01-01

    An innovative low temperature district heating (LTDH) local network is developed in Nottingham, supported by the REMOURBAN project, part of the H2020 Smart City and Community Lighthouse scheme. It was proposed that a branch emanating from the return pipe of the existing district heating system in Nottingham would be created to use low temperature heating for the first time on such scale in the UK. The development is aimed to extract unused heat from existing district heating system and to mak...

  17. Non-uniform velocity profile mechanism for flame stabilization in a porous radiant burner

    Energy Technology Data Exchange (ETDEWEB)

    Catapan, R.C.; Costa, M. [Mechanical Engineering Department, Instituto Superior Tecnico, Technical University of Lisbon, Avenida Rovisco Pais, 1049-001 Lisbon (Portugal); Oliveira, A.A.M. [Mechanical Engineering Department, Federal University of Santa Catarina, Campus Universitario Professor Joao David Ferreira Lima, 88040-900 Florianopolis, SC (Brazil)

    2011-01-15

    Industrial processes where the heating of large surfaces is required lead to the possibility of using large surface porous radiant burners. This causes additional temperature uniformity problems, since it is increasingly difficult to evenly distribute the reactant mixture over a large burner surface while retaining its stability and keeping low pollutant emissions. In order to allow for larger surface area burners, a non-uniform velocity profile mechanism for flame stabilization in a porous radiant burner using a single large injection hole is proposed and analyzed for a double-layered burner operating in open and closed hot (laboratory-scale furnace, with temperature-controlled, isothermal walls) environments. In both environments, local mean temperatures within the porous medium have been measured. For lower reactant flow rate and ambient temperature the flame shape is conical and anchored at the rim of the injection hole. As the volumetric flow rate or furnace temperature is raised, the flame undergoes a transition to a plane flame stabilized near the external burner surface. However, the stability range envelope remains the same in both regimes. (author)

  18. Integration of Space Heating and Hot Water Supply in Low Temperature District Heating

    DEFF Research Database (Denmark)

    Elmegaard, Brian; Ommen, Torben Schmidt; Markussen, Michael

    2014-01-01

    pipes, where the water is at the highest temperature. The heat loss may be lowered by decreasing the temperatures in the network for which reason low temperature networks are proposed as a low loss solution for future district heating. However, the heating demand of the consumers involve both domestic......District heating makes it possible to provide heat for many consumers in an efficient manner. In particular, district heating based on combined heat and power production is highly efficient. One disadvantage of district heating is that there is a significant heat loss from the pipes...... to the surrounding ground. In larger networks involving both transmission and distribution systems, the heat loss is most significant from the distribution network. An estimate is that about 80-90 % of the heat loss occurs in the distribution system. In addition, the heat loss is naturally highest from the forward...

  19. Challenges in Smart Low-Temperature District Heating Development

    DEFF Research Database (Denmark)

    Li, Hongwei; Wang, Stephen Jia

    2014-01-01

    Previous research and development shows that low temperature district heating (LTDH) system is economic feasible for low energy buildings and buildings at sparse areas. Coupling with reduced network temperature and well-designed district heating (DH) networks, LTDH can reduce network heat loss by...

  20. Industrial Heat Pump for a High Temperature District Heating Application

    DEFF Research Database (Denmark)

    Poulsen, Claus Nørgaard

    by excess thermal energy from thermal solar panels. An industrial heat pump system using the natural refrigerant ammonia, is extracting the thermal energy from the storage when needed, and produce hot water at 85°C, for the district heating grid. The heat pump also acts as contributor to electricity grid...

  1. Energy and exergy analysis of low temperature district heating network

    DEFF Research Database (Denmark)

    Li, Hongwei; Svendsen, Svend

    2012-01-01

    is designed to supply heating for 30 low energy detached residential houses. The network operational supply/return temperature is set as 55 °C/25 °C, which is in line with a pilot project carried out in Denmark. Two types of in-house substations are analyzed to supply the consumer domestic hot water demand...... energy/exergy losses and increase the quality match between the consumer heating demand and the district heating supply.......Low temperature district heating with reduced network supply and return temperature provides better match of the low quality building heating demand and the low quality heating supply from waste heat or renewable energy. In this paper, a hypothetical low temperature district heating network...

  2. Natural convection heat transfer of fluid with temperature-dependent specific heat

    International Nuclear Information System (INIS)

    Tanaka, Amane; Kubo, Shinji; Akino, Norio

    1998-01-01

    The present study investigates natural convection from a heated vertical plate of fluid with temperature-dependent specific heat, which is introduced as a model of microencapsulated phase change material slurries (MCPCM slurries). The temperature dependence of specific heat is represented by Gauss function with three physical parameters (peak temperature, width of phase change temperature and latent heat). Boundary layer equations are solved numerically, and the velocity and temperature fields of the flow are obtained. The relation between the heat transfer coefficients and the physical parameters of specific heat is discussed. The results show that the velocities and temperatures are smaller, and the heat transfer coefficients are larger comparing with those of the fluid with constant specific heat. (author)

  3. Low-temperature heating systems and public administration

    Energy Technology Data Exchange (ETDEWEB)

    Boerner, H

    1981-06-01

    The even temperature distribution and comfortable climate in rooms heated by low-temperature heating systems is mostly due to one of the preconditions of this type of heating system namely, efficient thermal insulation of the rooms. Thermal insulation is already required as part of the pertinent legal regulations but it is also in the interest of the builder-owner as it will, in the long run, greatly reduce the heating cost.

  4. Fabrication of lithium/C-103 alloy heat pipes for sharp leading edge cooling

    Science.gov (United States)

    Ai, Bangcheng; Chen, Siyuan; Yu, Jijun; Lu, Qin; Han, Hantao; Hu, Longfei

    2018-05-01

    In this study, lithium/C-103 alloys heat pipes are proposed for sharp leading edge cooling. Three models of lithium/C-103 alloy heat pipes were fabricated. And their startup properties were tested by radiant heat tests and aerothermal tests. It is found that the startup temperature of lithium heat pipe was about 860 °C. At 1000 °C radiant heat tests, the operating temperature of lithium/C-103 alloy heat pipe is lower than 860 °C. Thus, startup failure occurs. At 1100 °C radiant heat tests and aerothermal tests, the operating temperature of lithium/C-103 alloy heat pipe is higher than 860 °C, and the heat pipe starts up successfully. The startup of lithium/C-103 alloy heat pipe decreases the leading edge temperature effectively, which endows itself good ablation resistance. After radiant heat tests and aerothermal tests, all the heat pipe models are severely oxidized because of the C-103 poor oxidation resistance. Therefore, protective coatings are required for further applications of lithium/C-103 alloy heat pipes.

  5. The ADAM and EVE project: Heat transfer at ambient temperature

    International Nuclear Information System (INIS)

    Boltendahl, U.; Harth, R.

    1980-01-01

    In the nuclear research plant at Juelich a new heating system is at present being developed as part of the Nuclear Long-distance Heating Project. Helium is heated up in a high-temperature reactor. The heat chemically converts a gas mixture in a reformer plant (EVE). The gases 'charged' with energy can be transported through tubes over any distance required at ambient temperatures. In a methanisation plant (ADAM) the gases react with one another, releasing the energy in the form of heat which can be used for heating air or water. (orig.) [de

  6. Energy and exergy analysis of low temperature district heating network

    International Nuclear Information System (INIS)

    Li, Hongwei; Svendsen, Svend

    2012-01-01

    Low temperature district heating with reduced network supply and return temperature provides better match of the low quality building heating demand and the low quality heating supply from waste heat or renewable energy. In this paper, a hypothetical low temperature district heating network is designed to supply heating for 30 low energy detached residential houses. The network operational supply/return temperature is set as 55 °C/25 °C, which is in line with a pilot project carried out in Denmark. Two types of in-house substations are analyzed to supply the consumer domestic hot water demand. The space heating demand is supplied through floor heating in the bathroom and low temperature radiators in the rest of rooms. The network thermal and hydraulic conditions are simulated under steady state. A district heating network design and simulation code is developed to incorporate the network optimization procedure and the network simultaneous factor. Through the simulation, the overall system energy and exergy efficiencies are calculated and the exergy losses for the major district heating system components are identified. Based on the results, suggestions are given to further reduce the system energy/exergy losses and increase the quality match between the consumer heating demand and the district heating supply. -- Highlights: ► Exergy and energy analysis for low and medium temperature district heating systems. ► Different district heating network dimensioning methods are analyzed. ► Major exergy losses are identified in the district heating network and the in-house substations. ► Advantages to apply low temperature district heating are highlighted through exergy analysis. ► The influence of thermal by-pass on system exergy/energy performance is analyzed.

  7. Calculation of Vertical Temperature Gradients in Heated Rooms

    DEFF Research Database (Denmark)

    Overby, H.; Steen-Thøde, Mogens

    This paper deals with a simple model which predicts the vertical temperature gradient in a heated room. The gradient is calculated from a dimensionless temperature profile which is determined by two room air temperatures only, the mean temperature in the occupied zone and the mean temperature...

  8. Human local and total heat losses in different temperature.

    Science.gov (United States)

    Wang, Lijuan; Yin, Hui; Di, Yuhui; Liu, Yanfeng; Liu, Jiaping

    2016-04-01

    This study investigates the effects of operative temperature on the local and total heat losses, and the relationship between the heat loss and thermal sensation. 10 local parts of head, neck, chest, abdomen, upper arm, forearm, hand, thigh, leg and foot are selected. In all these parts, convection, radiation, evaporation, respiration, conduction and diffusion heat losses are analyzed when operative temperature is 23, 28, 33 and 37 °C. The local heat losses show that the radiation and convection heat losses are mainly affected by the area of local body, and the heat loss of the thigh is the most in the ten parts. The evaporation heat loss is mainly affected by the distribution of sweat gland, and the heat loss of the chest is the most. The total heat loss of the local body shows that in low temperature, the thigh, leg and chest have much heat loss, while in high temperature, the chest, abdomen, thigh and head have great heat loss, which are useful for clothing design. The heat losses of the whole body show that as the operative temperature increases, the radiation and convection heat losses decrease, the heat losses of conduction, respiration, and diffusion are almost constant, and the evaporation heat loss increases. By comparison, the heat loss ratios of the radiation, convection and sweat evaporation, are in agreement with the previous researches. At last, the formula about the heat loss ratio of convection and radiation is derived. It's useful for thermal comfort evaluation and HVAC (heating, ventilation and air conditioning) design. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Mapping of low temperature heat sources in Denmark

    DEFF Research Database (Denmark)

    Bühler, Fabian; Holm, Fridolin Müller; Huang, Baijia

    2015-01-01

    heat. The total accessible waste heat potential is found to be approximately 266 PJ per year with 58 % of it below 100 °C. In the natural heat category, temperatures below 20 °C originate from ambient air, sea water and shallow geothermal energy, and temperatures up to 100 °C are found for solar...... and deep geothermal energy. The theoretical solar thermal potential alone would be above 500 PJ per year. For the development of advanced thermodynamic cycles for the integration of heat sources in the Danish energy system, several areas of interest are determined. In the maritime transport sector a high......Low temperature heat sources are available in many applications, ranging from waste heat from industrial processes and buildings to geothermal and solar heat sources. Technical advancements, such as heat pumps with novel cycle design and multi-component working fluids, make the utilisation of many...

  10. Performance evaluation of radiant cooling system application on a university building in Indonesia

    Science.gov (United States)

    Satrio, Pujo; Sholahudin, S.; Nasruddin

    2017-03-01

    The paper describes a study developed to estimate the energy savings potential of a radiant cooling system installed in an institutional building in Indonesia. The simulations were carried out using IESVE to evaluate thermal performance and energy consumption The building model was calibrated using the measured data for the installed radiant system. Then this calibrated model was used to simulate the energy consumption and temperature distribution to determine the proportional energy savings and occupant comfort under different systems. The result was radiant cooling which integrated with a Dedicated Outside Air System (DOAS) could make 41,84% energy savings compared to the installed cooling system. The Computational Fluid Dynamics (CFD) simulation showed that a radiant system integrated with DOAS provides superior human comfort than a radiant system integrated with Variable Air Volume (VAV). Percentage People Dissatisfied was kept below 10% using the proposed system.

  11. Utilization of low-temperature heat sources for heat and power production

    DEFF Research Database (Denmark)

    Haglind, Fredrik; Elmegaard, Brian

    2014-01-01

    Low-temperature heat sources are available in many applications, ranging from waste heat from marine diesel engines, industries and refrigeration plants to biomass, geothermal and solar heat sources. There is a great potential for enhancing the utilization of these heat sources by novel...

  12. A study on heat resistance of high temperature resistant coating

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Liping; Wang, Xueying; Zhang, Qibin; Qin, Yanlong; Lin, Zhu [Research Institute of Engineering Technology of CNPC, Tianjin (China)

    2005-04-15

    A high temperature resistant coating has been developed, which is mainly for heavy oil production pipes deserved the serious corrosion. The coating has excellent physical and mechanical performance and corrosion resistance at room and high temperature. In order to simulate the underground working condition of heavy oil pipes,the heat resistance of the high temperature resistant coating has been studied. The development and a study on the heat resistance of the DHT high temperature resistance coating have been introduced in this paper

  13. A study on heat resistance of high temperature resistant coating

    International Nuclear Information System (INIS)

    Zhang, Liping; Wang, Xueying; Zhang, Qibin; Qin, Yanlong; Lin, Zhu

    2005-01-01

    A high temperature resistant coating has been developed, which is mainly for heavy oil production pipes deserved the serious corrosion. The coating has excellent physical and mechanical performance and corrosion resistance at room and high temperature. In order to simulate the underground working condition of heavy oil pipes,the heat resistance of the high temperature resistant coating has been studied. The development and a study on the heat resistance of the DHT high temperature resistance coating have been introduced in this paper

  14. Can riparian vegetation shade mitigate the expected rise in stream temperatures due to climate change during heat waves in a human-impacted pre-alpine river?

    Directory of Open Access Journals (Sweden)

    H. Trimmel

    2018-01-01

    Full Text Available Global warming has already affected European rivers and their aquatic biota, and climate models predict an increase of temperature in central Europe over all seasons. We simulated the influence of expected changes in heat wave intensity during the 21st century on water temperatures of a heavily impacted pre-alpine Austrian river and analysed future mitigating effects of riparian vegetation shade on radiant and turbulent energy fluxes using the deterministic Heat Source model. Modelled stream water temperature increased less than 1.5 °C within the first half of the century. Until 2100, a more significant increase of around 3 °C in minimum, maximum and mean stream temperatures was predicted for a 20-year return period heat event. The result showed clearly that in a highly altered river system riparian vegetation was not able to fully mitigate the predicted temperature rise caused by climate change but would be able to reduce water temperature by 1 to 2 °C. The removal of riparian vegetation amplified stream temperature increases. Maximum stream temperatures could increase by more than 4 °C even in annual heat events. Such a dramatic water temperature shift of some degrees, especially in summer, would indicate a total shift of aquatic biodiversity. The results demonstrate that effective river restoration and mitigation require re-establishing riparian vegetation and emphasize the importance of land–water interfaces and their ecological functioning in aquatic environments.

  15. Can riparian vegetation shade mitigate the expected rise in stream temperatures due to climate change during heat waves in a human-impacted pre-alpine river?

    Science.gov (United States)

    Trimmel, Heidelinde; Weihs, Philipp; Leidinger, David; Formayer, Herbert; Kalny, Gerda; Melcher, Andreas

    2018-01-01

    Global warming has already affected European rivers and their aquatic biota, and climate models predict an increase of temperature in central Europe over all seasons. We simulated the influence of expected changes in heat wave intensity during the 21st century on water temperatures of a heavily impacted pre-alpine Austrian river and analysed future mitigating effects of riparian vegetation shade on radiant and turbulent energy fluxes using the deterministic Heat Source model. Modelled stream water temperature increased less than 1.5 °C within the first half of the century. Until 2100, a more significant increase of around 3 °C in minimum, maximum and mean stream temperatures was predicted for a 20-year return period heat event. The result showed clearly that in a highly altered river system riparian vegetation was not able to fully mitigate the predicted temperature rise caused by climate change but would be able to reduce water temperature by 1 to 2 °C. The removal of riparian vegetation amplified stream temperature increases. Maximum stream temperatures could increase by more than 4 °C even in annual heat events. Such a dramatic water temperature shift of some degrees, especially in summer, would indicate a total shift of aquatic biodiversity. The results demonstrate that effective river restoration and mitigation require re-establishing riparian vegetation and emphasize the importance of land-water interfaces and their ecological functioning in aquatic environments.

  16. Optimization criteria for low temperature waste heat utilization

    International Nuclear Information System (INIS)

    Kranebitter, F.

    1977-01-01

    A special case in this field is the utilization of very low temperature waste heat. The temperature level under consideration in this paper is in the range between the body temperature of human beings and their environment. The waste heat from power generation and industrial processes is also considered. Thermal energy conversion will be mainly accomplished by heat cycles where discharged waste heat is reverse proportional to the upper cycle temperature. Limiting this upper cycle temperature by technological reasons the optimization of the heat cycle will depend on the nature of the cycle itself and specially on the temperature selected for the heat discharge. The waste heat discharge is typical for the different kinds of heat cycles and the paper presents the four most important of them. Feasible heat transfer methods and their economic evaluations are discussed and the distillation processes will be the basis for further considerations. The waste heat utilization for distillation purposes could be realized by three different cycles, the open cycle, the closed cycle and the multy cycle. Resulting problems as deaeration of large water streams and removal of the dissolved gases and their solutions are also discussed. (M.S.)

  17. Application of Abaqus to analysis of the temperature field in elements heated by moving heat sources

    Directory of Open Access Journals (Sweden)

    W. Piekarska

    2010-10-01

    Full Text Available Numerical analysis of thermal phenomena occurring during laser beam heating is presented in this paper. Numerical models of surface andvolumetric heat sources were presented and the influence of different laser beam heat source power distribution on temperature field wasanalyzed. Temperature field was obtained by a numerical solution the transient heat transfer equation with activity of inner heat sources using finite element method. Temperature distribution analysis in welded joint was performed in the ABAQUS/Standard solver. The DFLUXsubroutine was used for implementation of the movable welding heat source model. Temperature-depended thermophysical properties for steelwere assumed in computer simulations. Temperature distribution in laser beam surface heated and butt welded plates was numericallyestimated.

  18. Dynamic ignition regime of condensed system by radiate heat flux

    International Nuclear Information System (INIS)

    Arkhipov, V A; Zolotorev, N N; Korotkikh, A G; Kuznetsov, V T

    2017-01-01

    The main ignition characteristics of high-energy materials are the ignition time and critical heat flux allowing evaluation of the critical conditions for ignition, fire and explosive safety for the test solid propellants. The ignition process is typically studied in stationary conditions of heat input at constant temperature of the heating surface, environment or the radiate heat flux on the sample surface. In real conditions, ignition is usually effected at variable time-dependent values of the heat flux. In this case, the heated layer is formed on the sample surface in dynamic conditions and significantly depends on the heat flux change, i.e. increasing or decreasing falling heat flux in the reaction period of the propellant sample. This paper presents a method for measuring the ignition characteristics of a high-energy material sample in initiation of the dynamic radiant heat flux, which includes the measurement of the ignition time when exposed to a sample time varying radiant heat flux given intensity. In case of pyroxyline containing 1 wt. % of soot, it is shown that the ignition times are reduced by 20–50 % depending on the initial value of the radiant flux density in initiation by increasing or decreasing radiant heat flux compared with the stationary conditions of heat supply in the same ambient conditions. (paper)

  19. Low Temperature District Heating for Future Energy Systems

    DEFF Research Database (Denmark)

    Schmidt, Dietrich; Kallert, Anna; Blesl, Markus

    2017-01-01

    of the building stock. Low temperature district heating (LTDH) can contribute significantly to a more efficient use of energy resources as well as better integration of renewable energy (e.g. geothermal or solar heat), and surplus heat (e.g. industrial waste heat) into the heating sector. LTDH offers prospects......The building sector is responsible for more than one third of the final energy consumption of societies and produces the largest amount of greenhouse gas emissions of all sectors. This is due to the utilisation of combustion processes of mainly fossil fuels to satisfy the heating demand...... for both the demand side (community building structure) and the supply side (network properties or energy sources). Especially in connection with buildings that demand only low temperatures for space heating. The utilisation of lower temperatures reduces losses in pipelines and can increase the overall...

  20. Exergy and Energy Analysis of Low Temperature District Heating Network

    DEFF Research Database (Denmark)

    Li, Hongwei; Svendsen, Svend

    is in line with a pilot project that is carrying out in Denmark with network supply/return temperature at 55oC/25 oC. The consumer domestic hot water (DHW) demand is supplied with a special designed district heating (DH) storage tank. The space heating (SH) demand is supplied with a low temperature radiator......Low temperature district heating (LTDH) with reduced network supply and return temperature provides better match of the low quality building thermal demand and the low quality waste heat supply. In this paper, an exemplary LTDH network was designed for 30 low energy demand residential houses, which....... The network thermal and hydraulic conditions were simulated under steady state with an in-house district heating network design and simulation code. Through simulation, the overall system energetic and exergetic efficiencies were calculated and the exergy losses for the major district heating system...

  1. District Heating Expansion Potential with Low-Temperature and End-Use Heat Savings

    DEFF Research Database (Denmark)

    Nielsen, Steffen; Grundahl, Lars

    2018-01-01

    District heating has the potential to play a key role in the transition towards a renewable energy system. However, the development towards reduced heat demands threatens the feasibility of district heating. Despite this challenge, opportunity exists in the form of fourth generation district...... heating, which operates at lower temperatures and enables better renewable integration. This article investigates this challenge by examining the district heating potential within three scenarios: The first is a reference scenario with current heat demand and temperatures, the second includes heat demand...... costs. The models are applied using an example case of The Northern Region of Denmark. The article concludes that the district heating potential is highest in the reference scenario. When heat savings are introduced, district heating expansions, in most cases, will not be feasible. Introducing low...

  2. Temperature Assessment of Heating Stage for a Thermoforming Equipment

    International Nuclear Information System (INIS)

    Mohd Ghazali, F.A.; Ab Rahim, M.F.; Jaafar, A.A.; Ahmad, M.N.

    2016-01-01

    Thermoforming is a well-known manufacturing process in the productions of various plastic household and industrial solutions. The heating of a plastic sheet allows the plastic to soften and within its forming window temperature the sheet can replicate a required shape when pressed against a mould. Hence, the heating process is an important thermoforming stage that determine uniformity of the material distribution. This article proposed an experimental approach to investigate the thermal characteristics of the heating section of a low cost thermoforming equipment designed for teaching and research purposes. The temperatures of air and a model of a stretched heated plastic sheet were measured and analysed. The experimental data indicates that the spatial temperatures distribution was not localised and the temperature history of the infrared heating agrees well with those given by fast response thermocouples. The findings suggest that the spatial uniformity of temperature can be reasonably evaluated by using the proposed method. (paper)

  3. Heats pipes for temperature homogenization: A literature review

    International Nuclear Information System (INIS)

    Blet, Nicolas; Lips, Stéphane; Sartre, Valérie

    2017-01-01

    Highlights: • This paper is a review based on more than sixty references. • The review is sorted into various application fields. • Quantitative values of thermal gradients are compared with and without heat pipes. • Specificities of mentioned heat pipes are compared to other functions of heat pipes. - Abstract: Heat pipes offer high effective heat transfer in a purely passive way. Other specific properties of heat pipes, like temperature homogenization, can be also reached. In this paper, a literature review is carried out in order to investigate the existing heat pipe systems mainly aiming the reduction of temperature gradients. The review gathering more than sixty references is sorted into various application fields, like thermal management of electronics, of storage vessels or of satellites, for which the management of the temperature uniformity differs by the isothermal surface area, temperature ranges or the targeted precision of the temperature flattening. A summary of heat pipe characteristics for this function of temperature homogenization is then performed to identify their specificities, compared to other applications of heat pipes.

  4. Natural convection heat transfer coefficient for newborn baby - Thermal manikin assessed convective heat loses

    Science.gov (United States)

    Ostrowski, Ziemowit; Rojczyk, Marek

    2017-11-01

    The energy balance and heat exchange for newborn baby in radiant warmer environment are considered. The present study was performed to assess the body dry heat loss from an infant in radiant warmer, using copper cast anthropomorphic thermal manikin and controlled climate chamber laboratory setup. The total body dry heat losses were measured for varying manikin surface temperatures (nine levels between 32.5 °C and 40.1 °C) and ambient air temperatures (five levels between 23.5 °C and 29.7 °C). Radiant heat losses were estimated based on measured climate chamber wall temperatures. After subtracting radiant part, resulting convective heat loses were compared with computed ones (based on Nu correlations for common geometries). Simplified geometry of newborn baby was represented as: (a) single cylinder and (b) weighted sum of 5 cylinders and sphere. The predicted values are significantly overestimated relative to measured ones by: 28.8% (SD 23.5%) for (a) and 40.9% (SD 25.2%) for (b). This showed that use of adopted general purpose correlations for approximation of convective heat losses of newborn baby can lead to substantial errors. Hence, new Nu number correlating equation is proposed. The mean error introduced by proposed correlation was reduced to 1.4% (SD 11.97%), i.e. no significant overestimation. The thermal manikin appears to provide a precise method for the noninvasive assessment of thermal conditions in neonatal care.

  5. 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...

  6. Radiant floor cooling coupled with dehumidification systems in residential buildings: A simulation-based analysis

    International Nuclear Information System (INIS)

    Zarrella, Angelo; De Carli, Michele; Peretti, Clara

    2014-01-01

    Highlights: • The floor radiant cooling in a typical apartment is analyzed. • Dehumidification devices, fan-coil and mechanical ventilation are compared. • The results are analyzed in terms of both thermal comfort and energy consumption. • The energy consumption of the dehumidifiers is higher than that of other systems. • The mechanical ventilation decreases the moisture level better than other systems. - Abstract: The development of radiant cooling has stimulated an interest in new systems based on coupling ventilation with radiant cooling. However, radiant cooling systems may cause condensation to form on an active surface under warm and humid conditions during the cooling season. This phenomenon occurs when surface temperature falls below dew point. To prevent condensation, air humidity needs to be reduced with a dehumidification device or a mechanical ventilation system. There are two main options to achieve this. The first is to use dehumidification devices that reduce humidity, but are not coupled with ventilation, i.e. devices that handle room air and leave air change to infiltrations. The second is to combine a mechanical ventilation system with dehumidifying finned coils. This study analyzes the floor radiant cooling of a typical residential apartment within a multi-storey building in three Italian climate zones by means of a detailed simulation tool. Five systems were compared in terms of both indoor thermal comfort and energy consumption: radiant cooling without dehumidification; radiant cooling with a soft dehumidification device; radiant cooling with a dehumidification device which also supplies sensible cooling; radiant cooling coupled with fan coils; and radiant cooling with a mechanical ventilation system which dehumidifies and cools

  7. Determination of Ground Heat Exchangers Temperature Field in Geothermal Heat Pumps

    Science.gov (United States)

    Zhurmilova, I.; Shtym, A.

    2017-11-01

    For the heating and cooling supply of buildings and constructions geothermal heat pumps using low-potential ground energy are applied by means of ground exchangers. The process of heat transfer in a system of ground exchangers is a phenomenon of complex heat transfer. The paper presents a mathematical modeling of heat exchange processes, the temperature fields are built which are necessary for the determination of the ground array that ensures an adequate supply of low potential energy excluding the freezing of soil around the pipes in the ground heat exchangers and guaranteeing a reliable operation of geothermal heat pumps.

  8. Temperature-gated thermal rectifier for active heat flow control.

    Science.gov (United States)

    Zhu, Jia; Hippalgaonkar, Kedar; Shen, Sheng; Wang, Kevin; Abate, Yohannes; Lee, Sangwook; Wu, Junqiao; Yin, Xiaobo; Majumdar, Arun; Zhang, Xiang

    2014-08-13

    Active heat flow control is essential for broad applications of heating, cooling, and energy conversion. Like electronic devices developed for the control of electric power, it is very desirable to develop advanced all-thermal solid-state devices that actively control heat flow without consuming other forms of energy. Here we demonstrate temperature-gated thermal rectification using vanadium dioxide beams in which the environmental temperature actively modulates asymmetric heat flow. In this three terminal device, there are two switchable states, which can be regulated by global heating. In the "Rectifier" state, we observe up to 28% thermal rectification. In the "Resistor" state, the thermal rectification is significantly suppressed (Rectifier state. This temperature-gated rectifier can have substantial implications ranging from autonomous thermal management of heating and cooling systems to efficient thermal energy conversion and storage.

  9. Innovative system for delivery of low temperature district heating

    Directory of Open Access Journals (Sweden)

    Anton Ivanov Ianakiev

    2017-01-01

    Full Text Available An innovative Low Temperature District Heating (LTDH local network is developed in Nottingham, supported by REMOURBAN project, part of the H2020 Smart City and Community Lighthouse scheme. It was proposed that a branch emanating from the return pipe of the of the existing district heating system in Nottingham would be created to use low temperature heating for the first time in UK. The development is aimed to extract wasted (unused heat from existing district heating system and make it more efficient and profitable. Four maisonette blocks of 94 low-raised flats, at Nottingham demo site of the REMOURBAN project will be connected to this new LTDH system. The scheme will provide a primary supply of heat and hot water at approximately 50oC to 60oC. Innovated solutions have been put forward to overcome certain barriers, such as legionella related risks and peak loads during extreme heating seasons and occasional maintenance.

  10. Low Temperature District Heating for Future Energy Systems

    DEFF Research Database (Denmark)

    Ford, Rufus; Pietruschka, Dirk; Sipilä, Kari

    participants being VTT Technical Research Centre of Finland (VTT), Technical University of Denmark (DTU), Norwegian University of Science and Technology (NTNU), Stuttgart Technology University of Applied Sciences (HFT) and SSE Enterprise in United Kingdom. The demonstration cases described in the report......This report titled “Case studies and demonstrations” is the subtask D report of the IEA DHC|CHP Annex TS1 project “Low Temperature District Heating for Future Energy Systems” carried out between 2013 and 2016. The project was led by Fraunhofer Institute for Building Physics (IBP) with the other...... include examples on low temperature district heating systems, solar heating in a district heating system, heat pump based heat supply and energy storages for both peak load management and for seasonal heat storage. Some demonstrations have been implemented while others are at planning phase...

  11. Thermometry, calorimetry, and mean body temperature during heat stress.

    Science.gov (United States)

    Kenny, Glen P; Jay, Ollie

    2013-10-01

    Heat balance in humans is maintained at near constant levels through the adjustment of physiological mechanisms that attain a balance between the heat produced within the body and the heat lost to the environment. Heat balance is easily disturbed during changes in metabolic heat production due to physical activity and/or exposure to a warmer environment. Under such conditions, elevations of skin blood flow and sweating occur via a hypothalamic negative feedback loop to maintain an enhanced rate of dry and evaporative heat loss. Body heat storage and changes in core temperature are a direct result of a thermal imbalance between the rate of heat production and the rate of total heat dissipation to the surrounding environment. The derivation of the change in body heat content is of fundamental importance to the physiologist assessing the exposure of the human body to environmental conditions that result in thermal imbalance. It is generally accepted that the concurrent measurement of the total heat generated by the body and the total heat dissipated to the ambient environment is the most accurate means whereby the change in body heat content can be attained. However, in the absence of calorimetric methods, thermometry is often used to estimate the change in body heat content. This review examines heat exchange during challenges to heat balance associated with progressive elevations in environmental heat load and metabolic rate during exercise. Further, we evaluate the physiological responses associated with heat stress and discuss the thermal and nonthermal influences on the body's ability to dissipate heat from a heat balance perspective.

  12. MODELING OF TEMPERATURE FIELDS IN A SOLID HEAT ACCUMULLATORS

    Directory of Open Access Journals (Sweden)

    S. S. Belimenko

    2016-10-01

    Full Text Available Purpose. Currently, one of the priorities of energy conservation is a cost savings for heating in commercial and residential buildings by the stored thermal energy during the night and its return in the daytime. Economic effect is achieved due to the difference in tariffs for the cost of electricity in the daytime and at night. One of the most common types of devices that allow accumulating and giving the resulting heat are solid heat accumulators. The main purpose of the work: 1 software development for the calculation of the temperature field of a flat solid heat accumulator, working due to the heat energy accumulation in the volume of thermal storage material without phase transition; 2 determination the temperature distribution in its volumes at convective heat transfer. Methodology. To achieve the study objectives a heat transfer theory and Laplace integral transform were used. On its base the problems of determining the temperature fields in the channels of heat accumulators, having different cross-sectional shapes were solved. Findings. Authors have developed the method of calculation and obtained solutions for the determination of temperature fields in channels of the solid heat accumulator in conditions of convective heat transfer. Temperature fields over length and thickness of channels were investigated. Experimental studies on physical models and industrial equipment were conducted. Originality. For the first time the technique of calculating the temperature field in the channels of different cross-section for the solid heat accumulator in the charging and discharging modes was proposed. The calculation results are confirmed by experimental research. Practical value. The proposed technique is used in the design of solid heat accumulators of different power as well as full-scale production of them was organized.

  13. Hyperbolic heat conduction, effective temperature, and third law for nonequilibrium systems with heat flux

    Science.gov (United States)

    Sobolev, S. L.

    2018-02-01

    Some analogies between different nonequilibrium heat conduction models, particularly random walk, the discrete variable model, and the Boltzmann transport equation with the single relaxation time approximation, have been discussed. We show that, under an assumption of a finite value of the heat carrier velocity, these models lead to the hyperbolic heat conduction equation and the modified Fourier law with relaxation term. Corresponding effective temperature and entropy have been introduced and analyzed. It has been demonstrated that the effective temperature, defined as a geometric mean of the kinetic temperatures of the heat carriers moving in opposite directions, acts as a criterion for thermalization and is a nonlinear function of the kinetic temperature and heat flux. It is shown that, under highly nonequilibrium conditions when the heat flux tends to its maximum possible value, the effective temperature, heat capacity, and local entropy go to zero even at a nonzero equilibrium temperature. This provides a possible generalization of the third law to nonequilibrium situations. Analogies and differences between the proposed effective temperature and some other definitions of a temperature in nonequilibrium state, particularly for active systems, disordered semiconductors under electric field, and adiabatic gas flow, have been shown and discussed. Illustrative examples of the behavior of the effective temperature and entropy during nonequilibrium heat conduction in a monatomic gas and a strong shockwave have been analyzed.

  14. Application of 'SPICE' to predict temperature distribution in heat pipes

    Energy Technology Data Exchange (ETDEWEB)

    Li, H M; Liu, Y; Damodaran, M [Nanyang Technological Univ., Singapore (SG). School of Mechanical and Production Engineering

    1991-11-01

    This article presents a new alternative approach to predict temperature distribution in heat pipes. In this method, temperature distribution in a heat pipe, modelled as an analogous electrical circuit, is predicted by applying SPICE, a general-purpose circuit simulation program. SPICE is used to simulate electrical circuit designs before the prototype is assembled. Useful predictions are obtained for heat pipes with and without adiabatic sections and for heat pipes with various evaporator and condenser lengths. Comparison of the predicted results with experiments demonstrates fairly good agreement. It is also shown how interdisciplinary developments could be used appropriately. (author).

  15. Ground Source Heat Supply in Moscow Oblast: Temperature Potential and Sustainable Depth of Heat Wells

    Science.gov (United States)

    Vasil'ev, G. P.; Gornov, V. F.; Dmitriev, A. N.; Kolesova, M. V.; Yurchenko, V. A.

    2018-01-01

    The paper is devoted to a problem of increasing the efficiency of low-potential geothermal heat in heat pump systems of residential buildings the Moscow oblast of Russia, including Moscow. Estimates of a natural geothermal potential in the Moscow oblast (based on climatological data for the period from 1982 to 2011) are presented and a "Typical climatic year of natural soil temperature variations for the geoclimatic conditions of the Moscow oblast, including the city of Moscow" is proposed. Numerical simulation of the influence of geothermal energy potential and the depth of heat wells on the efficiency of ground source heat pump systems for the heat supply of residential buildings is carried out. Analysis of the numerical simulation showed that the operation of a heat pump system in a house heating mode under the geoclimatic conditions of the Moscow oblast leads to a temperature drop of the heat-exchange medium circulating through heat wells to 5-6°C by the end of the first 10 years of operation, and the process stabilizes by the 15th year of operation, and further changes in the heat-exchange medium temperature do not any longer significantly affect the temperature of the heat-exchange medium in the heat well. In this case, the exact dependence of the heat-exchange medium temperature drop on the depth is not revealed. Data on the economically expedient heat well depth for the conditions of the Moscow oblast ensuring a net present value for the whole residential building life cycle are presented. It is found that the heat well depth of 60 m can be considered as an endpoint for the Moscow oblast, and a further heat well deepening is economically impractical.

  16. Close-Spaced High Temperature Knudsen Flow.

    Science.gov (United States)

    1986-07-15

    radiant heat source assembly was substituted for the brazed molybdenum one in order to achieve higher radiant heater temperatures . 2.1.4 Experimental...at very high temperature , and ground flat. The molybdenum is then chemically etched to the desired depth using an etchant which does not affect...RiB6 295 -CLSE PCED HIGH TEMPERATURE KNUDSEN FLOU(U) RASOR I AiASSOCIATES INC SUNNYVALE CA J 8 MCVEY 15 JUL 86 NSR-224 AFOSR-TR-87-1258 F49628-83-C

  17. Performance of ultra low temperature district heating systems with utility plant and booster heat pumps

    DEFF Research Database (Denmark)

    Ommen, Torben Schmidt; Thorsen, Jan Eric; Markussen, Wiebke Brix

    2017-01-01

    The optimal integration of booster heat pumps in ultra low temperature district heating (ULTDH) was investigated and compared to the performance of low temperature district heating. Two possible heat production technologies for the DH networks were analysed, namely extraction combined heat...... temperature and the heat consumption profile. For reference conditions, the optimal return of ULTDH varies between 21 °C and 27 °C. When using a central HP to supply the DH system, the resulting coefficient of system performance (COSP) was in the range of 3.9 (-) to 4.7 (-) for equipment with realistic...... component efficiencies and effectiveness, when including the relevant parameters such as DH system pressure and heat losses. By using ULTDH with booster HPs, performance improvements of 12% for the reference calculations case were found, if the system was supplied by central HPs. Opposite results were found...

  18. Thermochemical heat storage for high temperature applications. A review

    Energy Technology Data Exchange (ETDEWEB)

    Felderhoff, Michael [Max-Planck-Institut fuer Kohlenforschung, Muelheim an der Ruhr (Germany); Urbanczyk, Robert; Peil, Stefan [Institut fuer Energie- und Umwelttechnik e.V. (IUTA), Duisburg (Germany)

    2013-07-01

    Heat storage for high temperature applications can be performed by several heat storage techniques. Very promising heat storage methods are based on thermochemical gas solid reactions. Most known systems are metal oxide/steam (metal hydroxides), carbon dioxide (metal carbonates), and metal/hydrogen (metal hydrides) systems. These heat storage materials posses high gravimetric and volumetric heat storage densities and because of separation of the reaction products and their storage in different locations heat losses can be avoided. The reported volumetric heat storage densities are 615, 1340 and 1513 [ kWh m{sup -3}] for calcium hydroxide Ca(OH){sub 2}, calcium carbonate CaCO{sub 3} and magnesium iron hydride Mg{sub 2}FeH{sub 6} respectively. Additional demands for gas storage decrease the heat storage density, but metal hydride systems can use available hydrogen storage possibilities for example caverns, pipelines and chemical plants. (orig.)

  19. High temperature heat pipe experiments in low earth orbit

    International Nuclear Information System (INIS)

    Woloshun, K.; Merrigan, M.A.; Sena, J.T.; Critchley, E.

    1993-01-01

    Although high temperature, liquid metal heat pipe radiators have become a standard component on most high power space power system designs, there is no experimental data on the operation of these heat pipes in a zero gravity or micro-gravity environment. Experiments to benchmark the transient and steady state performance of prototypical heat pipe space radiator elements are in preparation for testing in low earth orbit. It is anticipated that these heat pipes will be tested aborad the Space Shuttle in 1995. Three heat pipes will be tested in a cargo bay Get Away Special (GAS) canister. The heat pipes are SST/potassium, each with a different wick structure; homogeneous, arterial, and annular gap, the heat pipes have been designed, fabricated, and ground tested. In this paper, the heat pipe designs are specified, and transient and steady-state ground test data are presented

  20. Pulmonary artery and intestinal temperatures during heat stress and cooling

    DEFF Research Database (Denmark)

    Pearson, James; Ganio, Matthew S; Seifert, Thomas

    2012-01-01

    In humans, whole body heating and cooling are used to address physiological questions where core temperature is central to the investigated hypotheses. Core temperature can be measured in various locations throughout the human body. The measurement of intestinal temperature is increasingly used...

  1. Optimization of Temperature Schedule Parameters on Heat Supply in Power-and-Heat Supply Systems

    Directory of Open Access Journals (Sweden)

    V. A. Sednin

    2009-01-01

    Full Text Available The paper considers problems concerning optimization of a temperature schedule in the district heating systems with steam-turbine thermal power stations having average initial steam parameters. It has been shown in the paper that upkeeping of an optimum network water temperature permits to increase an energy efficiency of heat supply due to additional systematic saving of fuel. 

  2. Exergetic evaluation of heat pump booster configurations in a low temperature district heating network

    DEFF Research Database (Denmark)

    Ommen, Torben Schmidt; Elmegaard, Brian

    2012-01-01

    In order to minimise losses in a district heating network, one approach is to lower the temperature difference between working media and soil. Considering only direct heat exchange, the minimum forward temperature level is determined by the demand side, as energy services are required at a certai...

  3. Fusion blanket high-temperature heat transfer

    International Nuclear Information System (INIS)

    Fillo, J.A.

    1983-01-01

    Deep penetration of 14 MeV neutrons makes two-temperature region blankets feasible. A relatively low-temperature (approx. 300 0 C) metallic structure is the vacuum/coolant pressure boundary, while the interior of the blanket, which is a simple packed bed of nonstructural material, operates at very high temperatures (>1000 0 C). The water-cooled shell structure is thermally insulated from the steam-cooled interior. High-temperature steam can dramatically increase the efficiency of electric power generation, as well as produce hydrogen and oxygen-based synthetic fuels at high-efficiency

  4. 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...

  5. Generation, insulated confinement, and heating of ultra-high temperature plasmas

    International Nuclear Information System (INIS)

    Bass, R.W.

    1986-01-01

    This invention relates to the production and maintenance in steady state of ultra-high temperature confined plasmas, particularly those created by full ionization of a volume of some hydrogenic gas such as deuterium. The target mass is surrounded with an ambient fluid medium at a predetermined pressure. Pulsed energy is projected upon the target mass to bring it to a predetermined temperature and to fully ionize it; this energy may be pulsed photon energy or pulsed particle-beam kinetic energy. An electrostatic double layer is formed spontaneously between the ionized mass and the ambient medium, providing thermal insulation and leaving the dominant energy loss to be bremmstrahlung losses. The bremmstrahlung losses are compensated for completely by supplying additional radiant energy to the ionized mass to maintain its temperature. The frequency range of the additional radiant energy is selected so as to be absorbable by the ionized mass, and its power level is adjusted to maintain the ionized mass in a substantially steady state. The static pressure of the ambient medium is increased, thereby equally increasing the static pressure of the ionized mass so as to enable the mass to absorb more of the radiant energy and increasing its temperature but also increasing its power losses. Simultaneously the radius and temperature of the mass are monitored and the power level of the radiant energy supply is increased to as to compensate for the power losses. The minimum feasible size of the plasma is less than a centimeter in diameter, while there is no constraint on maximum feasible size. This invention may be practiced with commercially-available lasers and microwave beam generators

  6. Effect of heat treatment temperature on microstructure

    Indian Academy of Sciences (India)

    The results of electrochemical performance measurements for the HCSs as anode material for lithium ion batteries indicate that the discharge capacity of the HCSs is improved after heat treatment at 800°C compared with the as-prepared HCSs and have a maximum value of 357 mAh/g and still retains 303 mAh/g after 40 ...

  7. Can high temperature steam electrolysis function with geothermal heat?

    International Nuclear Information System (INIS)

    Sigurvinsson, J.; Mansilla, C.; Werkoff, F.; Lovera, P.

    2007-01-01

    It is possible to improve the performance of electrolysis processes by operating at a high temperature. This leads to a reduction in electricity consumption but requires a part of the energy necessary for the dissociation of water to be in the form of thermal energy. Iceland produces low cost electricity and very low cost geothermal heat. However, the temperature of geothermal heat is considerably lower than the temperature required at the electrolyser's inlet, making heat exchangers necessary to recuperate part of the heat contained in the gases at the electrolyser's outlet. A techno-economic optimisation model devoted to a high-temperature electrolysis (HTE) process which includes electrolysers as well as a high temperature heat exchanger network was created. Concerning the heat exchangers, the unit costs used in the model are based on industrial data. For the electrolyser cells, the unit cost scaling law and the physical sub-model we used were formulated using analogies with solid oxide fuel cells. The method was implemented in a software tool, which performs the optimisation using genetic algorithms. The first application of the method is done by taking into account the prices of electricity and geothermal heat in the Icelandic context. It appears that even with a geothermal temperature as low as 230 degrees C, the HTE could compete with alkaline electrolysis. (authors)

  8. The influence of heat sink temperature on the seasonal efficiency of shallow geothermal heat pumps

    Science.gov (United States)

    Pełka, Grzegorz; Luboń, Wojciech; Sowiżdżał, Anna; Malik, Daniel

    2017-11-01

    Geothermal heat pumps, also known as ground source heat pumps (GSHP), are the most efficient heating and cooling technology utilized nowadays. In the AGH-UST Educational and Research Laboratory of Renewable Energy Sources and Energy Saving in Miękinia, shallow geothermal heat is utilized for heating. In the article, the seasonal efficiency of two geothermal heat pump systems are described during the 2014/2015 heating season, defined as the period between 1st October 2014 and 30th April 2015. The first system has 10.9 kW heating capacity (according to European Standard EN 14511 B0W35) and extracts heat from three vertical geothermal loops at a depth of 80m each. During the heating season, tests warmed up the buffer to 40°C. The second system has a 17.03 kW heating capacity and extracts heat from three vertical geothermal loops at a depth of 100 m each, and the temperature of the buffer was 50°C. During the entire heating season, the water temperatures of the buffers was constant. Seasonal performance factors were calculated, defined as the quotient of heat delivered by a heat pump to the system and the sum of electricity consumed by the compressor, source pump, sink pump and controller of heat pumps. The measurements and calculations give the following results: - The first system was supplied with 13 857 kWh/a of heat and consumed 3 388 kWh/a electricity. The SPF was 4.09 and the average temperature of outlet water from heat pump was 40.8°C, and the average temperature of brine flows into the evaporator was 3.7 °C; - The second system was supplied with 12 545 kWh/a of heat and consumed 3 874 kWh/a electricity. The SPF was 3.24 and the average temperature of outlet water from heat pump was 51.6°C, and the average temperature of brine flows into the evaporator was 5.3°C. To summarize, the data shown above presents the real SPF of the two systems. It will be significant in helping to predict the SPF of objects which will be equipped with ground source heat pumps.

  9. Lauric and palmitic acids eutectic mixture as latent heat storage material for low temperature heating applications

    International Nuclear Information System (INIS)

    Tuncbilek, Kadir; Sari, Ahmet; Tarhan, Sefa; Erguenes, Gazanfer; Kaygusuz, Kamil

    2005-01-01

    Palmitic acid (PA, 59.8 deg. C) and lauric acid (LA, 42.6 deg. C) are phase change materials (PCM) having quite high melting temperatures which can limit their use in low temperature solar applications such as solar space heating and greenhouse heating. However, their melting temperatures can be tailored to appropriate value by preparing a eutectic mixture of the lauric and the palmitic acids. In the present study, the thermal analysis based on differential scanning calorimetry (DSC) technique shows that the mixture of 69.0 wt% LA and 31 wt% PA forms a eutectic mixture having melting temperature of 35.2 deg. C and the latent heat of fusion of 166.3 J g -1 . This study also considers the experimental determination of the thermal characteristics of the eutectic mixture during the heat charging and discharging processes. Radial and axial temperature distribution, heat transfer coefficient between the heat transfer fluid (HTF) pipe and the PCM, heat recovery rate and heat charging and discharging fractions were experimentally established employing a vertical concentric pipe-in-pipe energy storage system. The changes of these characteristics were evaluated with respect to the effect of inlet HTF temperature and mass flow rate. The DSC thermal analysis and the experimental results indicate that the LA-PA eutectic mixture can be a potential material for low temperature thermal energy storage applications in terms of its thermo-physical and thermal characteristics

  10. Achieving low return temperature for domestic hot water preparation by ultra-low-temperature district heating

    DEFF Research Database (Denmark)

    Yang, Xiaochen; Svendsen, Svend

    2017-01-01

    District heating (DH) is a cost-effective method of heat supply, especially to area with high heat density. Ultra-low-temperature district heating (ULTDH) is defined with supply temperature at 35-45 degrees C. It aims at making utmost use of the available low-temperature energy sources. In order...... to achieve high efficiency of the ULTDH system, the return temperature should be as low as possible. For the energy-efficient buildings in the future, it is feasible to use ULTDH to cover the space heating demand. However, considering the comfort and hygiene requirements of domestic hot water (DHW...... lower return temperature and higher efficiency for DHW supply, an innovative substation was devised, which replaced the bypass with an instantaneous heat exchanger and a micro electric storage tank. The energy performance of the proposed substation and the resulting benefits for the DH system...

  11. Measured Performance of a Low Temperature Air Source Heat Pump

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, R. K. [Johnson Research LLC, Pueblo West, CO (United States)

    2013-09-01

    A 4-ton Low Temperature Heat Pump (LTHP) manufactured by Hallowell International was installed in a residence near New Haven, Connecticut and monitored over two winters of operation. After attending to some significant service issues, the heat pump operated as designed. This report should be considered a review of the dual compressor 'boosted heat pump' technology. The Low Temperature Heat Pumpsystem operates with four increasing levels of capacity (heat output) as the outdoor temperature drops. The system was shown to select capacity correctly, supplying the appropriate amount of heat to the house across the full range of outdoor temperatures. The system's Coefficient of Performance (Seasonal COP, or SCOP) over two entire winters was calculated, based on measured data, to be 3.29over the first winter and 2.68 over the second winter. A second seasonal efficiency calculation by a different method yielded a SCOP of 2.78 for the first winter and 2.83 for the second winter. This second seasonal efficiency calculation was determined by comparing measured heat pump energy use to the in situ energy use with resistance heat alone. This method is the ratio of the slopes of thedaily energy use load lines.

  12. Temperature field distribution of coal seam in heat injection

    OpenAIRE

    Zhang Zhizhen; Peng Weihong; Shang Xiaoji; Wang Kun; Li Heng; Ma Wenming

    2017-01-01

    In this article, we present a natural boundary element method (NBEM) to solve the steady heat flow problem with heat sources in a coal seam. The boundary integral equation is derived to obtain the temperature filed distribution of the coal seam under the different injecting conditions.

  13. Effect of sintering temperature and heating mode on consolidation of ...

    Indian Academy of Sciences (India)

    ratures ranging from 570–630 ◦C. Microwave sintering at a heating rate of as high as 22◦. C/min resulted in ... The effect of heating mode and sintering temperature are discussed .... the compacts. This is attributed to the Zn evaporated from the.

  14. Effect of heat treatment temperature on binder thermal conductivities

    International Nuclear Information System (INIS)

    Wagner, P.

    1975-12-01

    The effect of heat treatment on the thermal conductivities of a pitch and a polyfurfuryl alcohol binder residue was investigated. Graphites specially prepared with these two binders were used for the experiments. Measured thermal conductivities were treated in terms of a two-component system, and the binder thermal conductivities were calculated. Both binder residues showed increased thermal conductivity with increased heat treatment temperature

  15. The Effects of the Heat and Moisture Exchanger on Humidity, Airway Temperature, and Core Body Temperature

    National Research Council Canada - National Science Library

    Delventhal, Mary

    1999-01-01

    Findings from several studies have demonstrated that the use of a heat and moisture exchanger increases airway humidity, which in turn increases mean airway temperature and prevents decreases in core body temperature...

  16. Differential effects of ambient temperature on warm cell responses to infrared radiation in the bloodsucking bug Rhodnius prolixus.

    Science.gov (United States)

    Zopf, Lydia M; Lazzari, Claudio R; Tichy, Harald

    2014-03-01

    Thermoreceptors provide animals with background information about the thermal environment, which is at least indirectly a prerequisite for thermoregulation and assists bloodsucking insects in the search for their host. Recordings from peg-in-pit sensilla and tapered hairs on the antennae of the bug Rhodnius prolixus revealed two physiologically different types of warm cells. Both types responded more strongly to temperature pulses produced by switching between two air streams at different constant temperatures than to infrared radiation pulses employed in still air. In addition, both warm cells were better able to discriminate small changes in air temperature than in infrared radiation. As convective and radiant heat determines the discharge, it is impossible for a single warm cell to signal the nature of the stimulus unequivocally. Individual responses are ambiguous, not with regard to temperature change, but with regard to its source. We argue that the bugs use mechanical flow information to differentiate between pulses of convective and radiant heat. However, if pulses of radiant heat occur together with a constant temperature air stream, the mechanical cues would not allow avoiding ambiguity that convective heat introduces into radiant heat stimulation. In this situation, the warm cell in the tapered hairs produced stronger responses than those in the peg-in-pit sensilla. The reversal in the excitability of the two types of warm cells provides a criterion by which to distinguish the combination of convective and radiant heat from the stimuli presented alone.

  17. Survey of high-temperature nuclear heat application

    International Nuclear Information System (INIS)

    Kirch, N.; Schaefer, M.

    1984-01-01

    Nuclear heat application at high temperatures can be divided into two areas - use of high-temperature steam up to 550 deg. C and use of high-temperature helium up to about 950 deg. C. Techniques of high-temperature steam and heat production and application are being developed in several IAEA Member States. In all these countries the use of steam for other than electricity production is still in a project definition phase. Plans are being discussed about using steam in chemical industries, oil refineries and for new synfuel producing plants. The use of nuclear generated steam for oil recovery from sands and shale is also being considered. High-temperature nuclear process heat production gives new possibilities for the application of nuclear energy - hard coals, lignites, heavy oils, fuels with problems concerning transport, handling and pollution can be converted into gaseous or liquid energy carriers with no loss of their energy contents. The main methods for this conversion are hydrogasification with hydrogen generated by nuclear heated steam reformers and steam gasification. These techniques will allow countries with large coal resources to replace an important part of their natural gas and oil consumption. Even countries with no fossil fuels can benefit from high-temperature nuclear heat - hydrogen production by thermochemical water splitting, nuclear steel making, ammonia production and the chemical heat-pipe system are examples in this direction. (author)

  18. Inverse heat transfer problem in digital temperature control in plate fin and tube heat exchangers

    Science.gov (United States)

    Taler, Dawid; Sury, Adam

    2011-12-01

    The aim of the paper is a steady-state inverse heat transfer problem for plate-fin and tube heat exchangers. The objective of the process control is to adjust the number of fan revolutions per minute so that the water temperature at the heat exchanger outlet is equal to a preset value. Two control techniques were developed. The first is based on the presented mathematical model of the heat exchanger while the second is a digital proportional-integral-derivative (PID) control. The first procedure is very stable. The digital PID controller becomes unstable if the water volumetric flow rate changes significantly. The developed techniques were implemented in digital control system of the water exit temperature in a plate fin and tube heat exchanger. The measured exit temperature of the water was very close to the set value of the temperature if the first method was used. The experiments showed that the PID controller works also well but becomes frequently unstable.

  19. High temperature reactor for the production of low temperature heat

    International Nuclear Information System (INIS)

    Muehlensiep, J.

    1986-12-01

    In this report the conditions of nuclear working reactors for district heating are described for the use in suburban areas. The design of a HTR is analysed under the point of view of safety and costs for the components and for the arrangement possibilities. The size of system is chosen by analysing important parameters for construction. The layout is determined by the retention of fission products in the coated particles of the fuel under conditions of hypothetical accidents. Based on stated data a HTR reactor for district heating will be designed. The speciality is a square shaped core which has the advantage to conduct the afterheat fastly to the outside of the pressure vessel in case of hypothetical accidents. Caused by the shape of the core the heat exchangers may be installed next to the core, the shutdown rods are maintained into reflector borings where they have a high efficiency. The whole primary circuit is surrounded by the reactor pressure vessel and is adjusted in an underground concrete cell. (orig./GL) [de

  20. Heat Transfer and Cooling Techniques at Low Temperature

    CERN Document Server

    Baudouy, B

    2014-07-17

    The first part of this chapter gives an introduction to heat transfer and cooling techniques at low temperature. We review the fundamental laws of heat transfer (conduction, convection and radiation) and give useful data specific to cryogenic conditions (thermal contact resistance, total emissivity of materials and heat transfer correlation in forced or boiling flow for example) used in the design of cooling systems. In the second part, we review the main cooling techniques at low temperature, with or without cryogen, from the simplest ones (bath cooling) to the ones involving the use of cryocoolers without forgetting the cooling flow techniques.

  1. Heat Transfer and Cooling Techniques at Low Temperature

    Energy Technology Data Exchange (ETDEWEB)

    Baudouy, B [Saclay (France)

    2014-07-01

    The first part of this chapter gives an introduction to heat transfer and cooling techniques at low temperature. We review the fundamental laws of heat transfer (conduction, convection and radiation) and give useful data specific to cryogenic conditions (thermal contact resistance, total emissivity of materials and heat transfer correlation in forced or boiling flow for example) used in the design of cooling systems. In the second part, we review the main cooling techniques at low temperature, with or without cryogen, from the simplest ones (bath cooling) to the ones involving the use of cryocoolers without forgetting the cooling flow techniques.

  2. Temperature Oscillations in Loop Heat Pipes - A Revisit

    Science.gov (United States)

    Ku, Jentung

    2018-01-01

    Three types of temperature oscillation have been observed in the loop heat pipes. The first type is an ultra-high frequency temperature oscillation with a period on the order of seconds or less. This type of temperature oscillation is of little significance in spacecraft thermal control because the amplitude is in the noise level. The second type is a high frequency, low amplitude temperature oscillation with a period on the order of seconds to minutes and an amplitude on the order of one Kelvin. It is caused by the back-and-forth movement of the vapor front near the inlet or outlet of the condenser. The third type is a low frequency, high amplitude oscillation with a period on the order of hours and an amplitude on the order of tens of Kelvin. It is caused by the modulation of the net heat load into the evaporator by the attached large thermal mass which absorbs and releases energy alternately. Several papers on LHP temperature oscillation have been published. This paper presents a further study on the underlying physical processes during the LHP temperature oscillation, with an emphasis on the third type of temperature oscillation. Specifically, equations governing the thermal and hydraulic behaviors of LHP operation will be used to describe interactions among LHP components, heat source, and heat sink. The following sequence of events and their interrelationship will also be explored: 1) maxima and minima of reservoir and thermal mass temperatures; 2) the range of the vapor front movement inside the condenser; 3) rates of change of the reservoir and thermal mass temperatures; 4) the rate of heat absorption and heat release by the thermal mass and the rate of vapor front movement; and 5) inflection points of the reservoir and thermal mass temperatures.

  3. Externally fired gas turbine cycles with high temperature heat exchangers utilising Fe-based ODS alloy tubing

    International Nuclear Information System (INIS)

    Olsson, F.; Svensson, S.-A.; Duncan, R.

    2001-01-01

    This work is part of the BRITE / EuRAM Project 'Development of Torsional Grain Structures to Improve Biaxial Creep Performance of Fe-based ODS Alloy Tubing for Biomass Power Plant'. The main goal of this project is to heat exchanger tubes working at 1100 o C and above. The paper deals with design implications of a biomass power plant, using an indirectly fired gas turbine with a high temperature heat exchanger containing Fe-based ODS alloy tubing. In the current heat exchanger design, ODS alloy tubing is used in a radiant section, using a bayonet type tube arrangement. This enables the use of straight sections of ODS tubing and reduces the amount of material required. In order to assess the potential of the power plant system, thermodynamic calculations have been conducted. Both co-generation and condensing applications are studied and results so far indicate that the electrical efficiency is high, compared to values reached by conventional steam cycle power plants of the same size (approx. 5 MW e ). (author)

  4. Modeling of hydronic radiant cooling of a thermally homeostatic building using a parametric cooling tower

    International Nuclear Information System (INIS)

    Ma, Peizheng; Wang, Lin-Shu; Guo, Nianhua

    2014-01-01

    Highlights: • Investigated cooling of thermally homeostatic buildings in 7 U.S. cities by modeling. • Natural energy is harnessed by cooling tower to extract heat for building cooling. • Systematically studied possibility and conditions of using cooling tower in buildings. • Diurnal ambient temperature amplitude is taken into account in cooling tower cooling. • Homeostatic building cooling is possible in locations with large ambient T amplitude. - Abstract: A case is made that while it is important to mitigate dissipative losses associated with heat dissipation and mechanical/electrical resistance for engineering efficiency gain, the “architect” of energy efficiency is the conception of best heat extraction frameworks—which determine the realm of possible efficiency. This precept is applied to building energy efficiency here. Following a proposed process assumption-based design method, which was used for determining the required thermal qualities of building thermal autonomy, this paper continues this line of investigation and applies heat extraction approach investigating the extent of building partial homeostasis and the possibility of full homeostasis by using cooling tower in one summer in seven selected U.S. cities. Cooling tower heat extraction is applied parametrically to hydronically activated radiant-surfaces model-buildings. Instead of sizing equipment as a function of design peak hourly temperature as it is done in heat balance design-approach of selecting HVAC equipment, it is shown that the conditions of using cooling tower depend on both “design-peak” daily-mean temperature and the distribution of diurnal range in hourly temperature (i.e., diurnal temperature amplitude). Our study indicates that homeostatic building with natural cooling (by cooling tower alone) is possible only in locations of special meso-scale climatic condition such as Sacramento, CA. In other locations the use of cooling tower alone can only achieve homeostasis

  5. Multi-Temperature Heat Pump with Cascade Compressor Connection

    Directory of Open Access Journals (Sweden)

    Sit M.L.

    2017-08-01

    Full Text Available The object of the study is a multifunctional heat pump with several evaporators and condensers designed for simultaneous provision of technological processes with heat and cold. The aim of the work is the development and study of the scheme for this type of heat pumps, which ensures minimum irreversibility in the "compressor-gas coolers" chain, without the use of adjustable ejectors installed after evaporators and used as flow mixers. The obtained technical solution ensures the stabilization of the heat pump coefficient of performance (COP and prescribed thermal regimes of heat exchangers at a variable flow rate of the refrigerant. The novelty of the elaboration is inclusion a compressor of the first stage with a serially connected intermediate heat exchanger and a control valve that are located before the compressor inlet of the second stage of the heat pump, which allows to establish a rational pressure after the first stage of the compressors. A scheme is proposed for regulating the temperature at the inlet of the first stage compressors by regulating the flow through the primary circuits of the recuperative heat exchangers. The first stage compressor control system allows providing the required modes of operation of the heat pump. It is established, because of the exergetic analysis of the sections of the hydraulic circuit of heat pump located between the evaporators and gas coolers that the reduction of irreversible losses in the heat pump is ensured due to the optimal choice of the superheat value of the gas after the evaporators.

  6. Active ion temperature measurement with heating neutral beam

    International Nuclear Information System (INIS)

    Miura, Yukitoshi; Matsuda, Toshiaki; Yamamoto, Shin

    1987-03-01

    When the heating neutral-beam (hydrogen beam) is injected into a deuterium plasma, the density of neutral particles is increased locally. By using this increased neutral particles, the local ion temperature is measured by the active charge-exchange method. The analyzer is the E//B type mass-separated neutral particle energy analyzer and the measured position is about one third outside of the plasma radius. The deuterium energy spectrum is Maxwellian, and the temperature is increased from 350 eV to 900 eV during heating. Since the local hydrogen to deuterium density concentration and the density of the heating neutral-beam as well as the ion temperature can be obtained good S/N ratio, the usefulness of this method during neutral-beam heating is confirmed by this experiment. (author)

  7. Temperature distribution of the energy consumed as heat in Canada

    International Nuclear Information System (INIS)

    Puttagunta, V.R.

    1974-10-01

    The amount of energy consumed as heat (excluding thermal generation of electricity) in Canada is estimated from statistical data available on the total consumption of energy for the years 1958 to 2000. Based on some actual plant data and other statistical information this energy consumption is sub-divided into four temperature categories: high (>260 degrees C), intermediate (140-260 degrees C), low (100-140 degrees C), and space heating (<100 degrees C). The results of this analysis show that approximately half of all the energy consumed in Canada has an end use as heat. Less than 10 percent of the energy consumed as heat is in the high temperature category, 12 to 14 percent is in the intermediate temperature range, 21 to 27 percent is in the low temperature range, and 50 to 58 percent is used for space heating. Over 90 percent of the energy consumed as heat in Canada is within the temperature capability of the CANDU-PHW reactor. (author)

  8. Analysis of temperature distribution in a heat conducting fiber with ...

    African Journals Online (AJOL)

    The temperature distribution in a heat conducting fiber is computed using the Galerkin Finite Element Method in the present study. The weak form of the governing differential equation is obtained and nodal temperatures for linear and quadratic interpolation functions for different mesh densities are calculated for Neumann ...

  9. Direct evaluation of transient surface temperatures and heat fluxes

    International Nuclear Information System (INIS)

    Axford, R.A.

    1975-08-01

    Evaluations of transient surface temperatures resulting from the absorption of radiation are required in laser fusion reactor systems studies. A general method for the direct evaluation of transient surface temperatures and heat fluxes on the boundaries of bounded media is developed by constructing fundamental solutions of the scalar Helmholtz equation and performing certain elementary integrations

  10. Hovering in the heat: effects of environmental temperature on heat regulation in foraging hummingbirds.

    Science.gov (United States)

    Powers, Donald R; Langland, Kathleen M; Wethington, Susan M; Powers, Sean D; Graham, Catherine H; Tobalske, Bret W

    2017-12-01

    At high temperature (greater than 40°C) endotherms experience reduced passive heat dissipation (radiation, conduction and convection) and increased reliance on evaporative heat loss. High temperatures challenge flying birds due to heat produced by wing muscles. Hummingbirds depend on flight for foraging, yet inhabit hot regions. We used infrared thermography to explore how lower passive heat dissipation during flight impacts body-heat management in broad-billed ( Cynanthus latirostris , 3.0 g), black-chinned ( Archilochus alexandri , 3.0 g), Rivoli's ( Eugenes fulgens , 7.5 g) and blue-throated ( Lampornis clemenciae , 8.0 g) hummingbirds in southeastern Arizona and calliope hummingbirds ( Selasphorus calliope , 2.6 g) in Montana. Thermal gradients driving passive heat dissipation through eye, shoulder and feet dissipation areas are eliminated between 36 and 40°C. Thermal gradients persisted at higher temperatures in smaller species, possibly allowing them to inhabit warmer sites. All species experienced extended daytime periods lacking thermal gradients. Broad-billed hummingbirds lacking thermal gradients regulated the mean total-body surface temperature at approximately 38°C, suggesting behavioural thermoregulation. Blue-throated hummingbirds were inactive when lacking passive heat dissipation and hence might have the lowest temperature tolerance of the four species. Use of thermal refugia permitted hummingbirds to tolerate higher temperatures, but climate change could eliminate refugia, forcing distributional shifts in hummingbird populations.

  11. Power generation from low-temperature heat source

    Energy Technology Data Exchange (ETDEWEB)

    Lakew, Amlaku Abie

    2012-07-01

    The potential of low-temperature heat sources for power production has been discussed for decades. The diversity and availability of low-temperature heat sources makes it interesting for power production. The thermodynamic power cycle is one of the promising technologies to produce electricity from low-temperature heat sources. There are different working fluids to be used in a thermodynamic power cycle. Working fluid selection is essential for the performance of the power cycle. Over the last years, different working fluid screening criteria have been used. In broad speaking the screening criteria can be grouped as thermodynamic performance, component size requirement, economic performance, safety and environmental impact. Screening of working fluids at different heat source temperatures (80-200 Celsius degrees) using thermodynamic performance (power output and exergy efficiency) and component size (heat exchanger and turbine) is investigated. It is found that the 'best' working fluid depends on the criteria used and heat source temperature level. Transcritical power cycles using carbon dioxide as a working fluid is studied to produce power at 100 Celsius degrees. Carbon dioxide is an environmentally friendly refrigerant. The global warming potential of carbon dioxide is 1. Furthermore, because of its low critical temperature (31 Celsius degrees), carbon dioxide can operate in a transcritical power cycle for lower heat source temperatures. A transcritical configuration avoids the problem of pinching which otherwise would happened in subcritical power cycle. In the process, better temperature matching is achieved and more heat is extracted. Thermodynamic analysis of transcritical cycle is performed; it is found that there is an optimal operating pressure for highest net power output. The pump work is a sizable fraction of the work produced by the turbine. The effect of efficiency deterioration of the pump and the turbine is compared. When the

  12. Low-temperature nuclear heat applications: Nuclear power plants for district heating

    International Nuclear Information System (INIS)

    1987-08-01

    The IAEA reflected the needs of its Member States for the exchange of information in the field of nuclear heat application already in the late 1970s. In the early 1980s, some Member States showed their interest in the use of heat from electricity producing nuclear power plants and in the development of nuclear heating plants. Accordingly, a technical committee meeting with a workshop was organized in 1983 to review the status of nuclear heat application which confirmed both the progress made in this field and the renewed interest of Member States in an active exchange of information about this subject. In 1985 an Advisory Group summarized the Potential of Low-Temperature Nuclear Heat Application; the relevant Technical Document reviewing the situation in the IAEA's Member States was issued in 1986 (IAEA-TECDOC-397). Programme plans were made for 1986-88 and the IAEA was asked to promote the exchange of information, with specific emphasis on the design criteria, operating experience, safety requirements and specifications for heat-only reactors, co-generation plants and power plants adapted for heat application. Because of a growing interest of the IAEA's Member States about nuclear heat employment in the district heating domaine, an Advisory Group meeting was organized by the IAEA on ''Low-Temperature Nuclear Heat Application: Nuclear Power Plants for District Heating'' in Prague, Czechoslovakia in June 1986. The information gained up to 1986 and discussed during this meeting is embodied in the present Technical Document. 22 figs, 11 tabs

  13. Heating and Domestic Hot Water Systems in Buildings Supplied by Low-Temperature District Heating

    DEFF Research Database (Denmark)

    Brand, Marek

    solutions simply redirect the bypassed water back to the DH network without additional cooling, but bypassed water can instead be redirected to floor heating in the bathroom to be further cooled and thus reduce heat loss from the DH network while improving comfort for occupants and still ensure fast DHW...... increased risk of Legionella if the DH substation and DHW system are designed for the low-temperature supply conditions. To ensure the fast provision of DHW during non-heating periods, the supply service pipe should be kept warm, preferably with the bypass solution redirecting the bypass flow to bathroom...... temperature. To accord with the literature, the modelling of internal heat gains reflected the improved efficiency of equipment by reduction of value from 5W/m2 to 4.2W/m2, also modelled as intermittent heat gains based on a realistic week schedule. Furthermore, the indoor set-point temperature was increased...

  14. Pressurized Recuperator For Heat Recovery In Industrial High Temperature Processes

    Directory of Open Access Journals (Sweden)

    Gil S.

    2015-09-01

    Full Text Available Recuperators and regenerators are important devices for heat recovery systems in technological lines of industrial processes and should have high air preheating temperature, low flow resistance and a long service life. The use of heat recovery systems is particularly important in high-temperature industrial processes (especially in metallurgy where large amounts of thermal energy are lost to the environment. The article presents the process design for a high efficiency recuperator intended to work at high operating parameters: air pressure up to 1.2 MPa and temperature of heating up to 900°C. The results of thermal and gas-dynamic calculations were based on an algorithm developed for determination of the recuperation process parameters. The proposed technical solution of the recuperator and determined recuperation parameters ensure its operation under maximum temperature conditions.

  15. The Heat Is On! Using Particle Models to Change Students' Conceptions of Heat and Temperature

    Science.gov (United States)

    Hitt, Austin Manning; Townsend, J. Scott

    2015-01-01

    Elementary, middle-level, and high school science teachers commonly find their students have misconceptions about heat and temperature. Unfortunately, student misconceptions are difficult to modify or change and can prevent students from learning the accurate scientific explanation. In order to improve our students' understanding of heat and…

  16. Increase of COP for heat transformer in water purification systems. Part I - Increasing heat source temperature

    International Nuclear Information System (INIS)

    Siqueiros, J.; Romero, R.J.

    2007-01-01

    The integration of a water purification system in a heat transformer allows a fraction of heat obtained by the heat transformer to be recycled, increasing the heat source temperature. Consequently, the evaporator and generator temperatures are also increased. For any operating conditions, keeping the condenser and absorber temperatures and also the heat load to the evaporator and generator, a higher value of COP is obtained when only the evaporator and generator temperatures are increased. Simulation with proven software compares the performance of the modeling of an absorption heat transformer for water purification (AHTWP) operating with water/lithium bromide, as the working fluid-absorbent pair. Plots of enthalpy-based coefficients of performance (COP ET ) and the increase in the coefficient of performance (COP) are shown against absorber temperature for several thermodynamic operating conditions. The results showed that proposed (AHTWP) system is capable of increasing the original value of COP ET more than 120%, by recycling part of the energy from a water purification system. The proposed system allows to increase COP values from any experimental data for water purification or any other distillation system integrated to a heat transformer, regardless of the actual COP value and any working fluid-absorbent pair

  17. Entropy Generation of Desalination Powered by Variable Temperature Waste Heat

    Directory of Open Access Journals (Sweden)

    David M. Warsinger

    2015-10-01

    Full Text Available Powering desalination by waste heat is often proposed to mitigate energy consumption and environmental impact; however, thorough technology comparisons are lacking in the literature. This work numerically models the efficiency of six representative desalination technologies powered by waste heat at 50, 70, 90, and 120 °C, where applicable. Entropy generation and Second Law efficiency analysis are applied for the systems and their components. The technologies considered are thermal desalination by multistage flash (MSF, multiple effect distillation (MED, multistage vacuum membrane distillation (MSVMD, humidification-dehumidification (HDH, and organic Rankine cycles (ORCs paired with mechanical technologies of reverse osmosis (RO and mechanical vapor compression (MVC. The most efficient technology was RO, followed by MED. Performances among MSF, MSVMD, and MVC were similar but the relative performance varied with waste heat temperature or system size. Entropy generation in thermal technologies increases at lower waste heat temperatures largely in the feed or brine portions of the various heat exchangers used. This occurs largely because lower temperatures reduce recovery, increasing the relative flow rates of feed and brine. However, HDH (without extractions had the reverse trend, only being competitive at lower temperatures. For the mechanical technologies, the energy efficiency only varies with temperature because of the significant losses from the ORC.

  18. Rapid self-heating and internal temperature sensing of lithium-ion batteries at low temperatures

    International Nuclear Information System (INIS)

    Zhang, Guangsheng; Ge, Shanhai; Xu, Terrence; Yang, Xiao-Guang; Tian, Hua; Wang, Chao-Yang

    2016-01-01

    Highlights: • Self-heating lithium-ion battery (SHLB) structure provided a practical solution to the poor performance at subzero temperatures. • We report an improved SHLB that heats from −20 °C to 0 °C in 12.5 seconds, or 56% more rapidly, while consuming 24% less energy than previously reported. • The nickel foil heating element embedded inside a SHLB cell plays a dominant role in rapid self-heating. • The embedded nickel foil can simultaneously perform as an internal temperature sensor (ITS). • 2-sheet design self-heats faster than 1-sheet design due to more uniform internal temperature distribution. - Abstract: The recently discovered self-heating lithium-ion battery structure provided a practical solution to the poor performance at subzero temperatures that has hampered battery technology for decades. Here we report an improved self-heating lithium-ion battery (SHLB) that heats from −20 °C to 0 °C in 12.5 seconds, or 56% more rapidly, while consuming 24% less energy than that reported previously. We reveal that a nickel foil heating element embedded inside a SHLB cell plays a dominant role in self-heating and we experimentally demonstrate that a 2-sheet design can achieve dramatically accelerated self-heating due to more uniform internal temperature distribution. We also report, for the first time, that this embedded nickel foil can simultaneously perform as an internal temperature sensor (ITS) due to the perfectly linear relationship between the foil’s electrical resistance and temperature.

  19. Decentralized substations for low-temperature district heating with no Legionella risk, and low return temperatures

    International Nuclear Information System (INIS)

    Yang, Xiaochen; Li, Hongwei; Svendsen, Svend

    2016-01-01

    To improve energy efficiency and give more access to renewable energy sources, low-temperature district heating (LTDH) is a promising concept to be realized in the future. However, concern about Legionella proliferation restricts applying low-temperature district heating in conventional systems with domestic hot water (DHW) circulation. In this study, a system with decentralized substations was analysed as a solution to this problem. Furthermore, a modification for the decentralized substation system were proposed in order to reduce the average return temperature. Models of conventional system with medium-temperature district heating, decentralized substation system with LTDH, and innovative decentralized substation system with LTDH were built based on the information of a case building. The annual distribution heat loss and the operating costs of the three scenarios were calculated and compared. From the results, realizing LTDH by the decentralized substation unit, 30% of the annual distribution heat loss inside the building can be saved compared to a conventional system with medium-temperature district heating. Replacing the bypass pipe with an in-line supply pipe and a heat pump, the innovative decentralized substation system can reduce distribution heat loss by 39% compared to the conventional system and by 12% compared to the normal decentralized substation system with bypass. - Highlights: • The system of decentralized substations can realize low-temperature district heating without running the risk of Legionella. • Decentralized substations help reduce the distribution heat loss inside the building compared to conventional system. • A new concept that can reduce the return temperature for district heating is proposed and analysed.

  20. Thermal power generation during heat cycle near room temperature

    Science.gov (United States)

    Shibata, Takayuki; Fukuzumi, Yuya; Kobayashi, Wataru; Moritomo, Yutaka

    2018-01-01

    We demonstrate that a sodium-ion secondary battery (SIB)-type thermocell consisting of two types of Prussian blue analogue (PBA) with different electrochemical thermoelectric coefficients (S EC ≡ ∂V/∂T V and T are the redox potential and temperature, respectively) produces electrical energy during heat cycles. The device produces an electrical energy of 2.3 meV/PBA per heat cycle between 295 K (= T L) and 323 K (= T H). The ideal thermal efficiency (η = 1.0%), which is evaluated using the heat capacity (C = 4.16 meV/K) of ideal Na2Co[Fe(CN)6], reaches 11% of the Carnot efficiency (ηth = 8.7%). Our SIB-type thermocell is a promising thermoelectric device that harvests waste heat near room temperature.

  1. Calculation of the fuel temperature field under heat release and heat conductance transient conditions

    International Nuclear Information System (INIS)

    Kazakov, E.K.; Chernukhina, G.M.

    1974-01-01

    Results of calculation of the temperature distribution in an annular fuel element at transient thermal conductivity and heat release values are given. The calculation has been carried out by the mesh technique with the third-order boundary conditions for the inner surface assumed and with heat fluxes and temperatures at the zone boundaries to be equal. Three variants of solving the problem of a stationary temperature field are considered for failed fuel elements with clad flaking or cracks. The results obtained show the nonuniformity of the fuel element temperature field to depend strongly on the perturbation parameter at transient thermal conductivity and heat release values. In case of can flaking at a short length, the core temperature rises quickly after flaking. While evaluating superheating, one should take into account the symmetry of can flaking [ru

  2. Temperature dependence of heat sensitization and thermotolerance induction with ethanol

    International Nuclear Information System (INIS)

    Henle, K.J.; Nagle, W.A.; Moss, A.J.

    1987-01-01

    Cytoxicity of 1 M ethanol was strongly temperature dependent; survival curves between 34 0 and 39 0 C were similar to heat survival curves between 40 and 45 0 without ethanol. Ethanol was non-toxic at 22 0 ; at 34.5 0 and 35.5 0 ethanol survival curves were biphasic. The major effect of 1 M ethanol was an effective temperature shift of 6.4 Celsius degrees, although temperatures between 34 0 and 36 0 caused additional sensitization reminiscent of the stepdown heating phenomenon. Induction of thermotolerance with equitoxic ethanol exposures at 35.5 0 and 37 0 or with heat alone (10 min, 45 0 ) resulted in tolerance development with similar kinetics; in contrast, ethanol exposures at 22 0 did not induce any tolerance development with similar kinetics; in contrast, ethanol exposures at 22 0 did not induce any tolerance to hyperthermia. These data provide a rationale for conflicting reports in the literature regarding thermotolerance induction by ethanol and suggest that ethanol causes ''heat'' stress at temperatures that are generally considered to be physiological. This interpretation predicts that the use of ethanol and other organic solvents in high concentrations will cause effects at 37 0 that normally occur only at hyperthermic temperatures, including membrane perturbations and HSP synthesis, and that ''physiological'' temperatures must be precisely controlled under those conditions

  3. Heat capacity characterization at phase transition temperature of Agl superionic

    International Nuclear Information System (INIS)

    Widowati, Arie

    2000-01-01

    The phase transition of Agl superionic conductor was investigated by calorometric. A single phase transition was found at (153±5) o C which corresponds to the α - β transition. Calorimetric measurement showed an anomalously high heat capacity with a large discontinues change in the Arrhenius plot, was found above the transition temperature of β - α phase. The maximum heat capacity was found to be ±19.7 cal/gmol. Key words : superionic conductor, thermal capacity

  4. Low temperature specific heat anomalies in melanins and tumor melanosomes

    Energy Technology Data Exchange (ETDEWEB)

    Mizutani, U [Carnegie--Mellon Univ., Pittsburgh; Massalski, T B; McGinness, J E; Corry, P M

    1976-02-12

    Human malignant melanoma cells obtained at autopsy were used. Data indicate that melanins exhibit a large linear term (50-200 erg g/sup -1/K/sup -2/) and that they seem to undergo a phase transition as indicated by the heat capacity near 1.9/sup 0/K. A table is presented to show low temperature specific heat data for melanin samples. The measurements include two anomalies, a transition and an unusually high linear contribution. (HLW)

  5. The future of the low temperature district heating reactor

    International Nuclear Information System (INIS)

    Lu Yingzhong; Wang Dazhong; Ma Changwen; Dong Duo; Tian Jiafu.

    1984-01-01

    In this paper, the role, development and situation of the low temperature district heating reactor (LTDHR) are briefly summarized. There are four types of LTDHR. They are PWR, reactor with boiling in the chimney, organic reactor and swimming pool reactor. The features of these reactors are introduced. The situation and role of the LTDHR in the future of the energy system are also discussed. The experiment on nuclear district heating with the swimming pool reactor in Qinghua Univ. is described briefly. (Author)

  6. Future changes of temperature and heat waves in Ontario, Canada

    Science.gov (United States)

    Li, Zhong; Huang, Guohe; Huang, Wendy; Lin, Qianguo; Liao, Renfei; Fan, Yurui

    2018-05-01

    Apparent changes in the temperature patterns in recent years brought many challenges to the province of Ontario, Canada. As the need for adapting to climate change challenges increases, the development of reliable climate projections becomes a crucial task. In this study, a regional climate modeling system, Providing Regional Climates for Impacts Studies (PRECIS), is used to simulate the temperature patterns in Ontario. Three PRECIS runs with a resolution of 25 km × 25 km are carried out to simulate the present (1961-1990) temperature variations. There is a good match between the simulated and observed data, which validates the performance of PRECIS in reproducing temperature changes in Ontario. Future changes of daily maximum, mean, and minimum temperatures during the period 2071-2100 are then projected under the IPCC SRES A2 and B2 emission scenarios using PRECIS. Spatial variations of annual mean temperature, mean diurnal range, and temperature seasonality are generated. Furthermore, heat waves defined based on the exceedance of local climatology and their temporal and spatial characteristics are analyzed. The results indicate that the highest temperature and the most intensive heat waves are most likely to occur at the Toronto-Windsor corridor in Southern Ontario. The Northern Ontario, in spite of the relatively low projected temperature, would be under the risk of long-lasting heat waves, and thus needs effective measures to enhance its climate resilience in the future. This study can assist the decision makers in better understanding the future temperature changes in Ontario and provide decision support for mitigating heat-related loss.

  7. Heat experiment design to estimate temperature dependent thermal properties

    International Nuclear Information System (INIS)

    Romanovski, M

    2008-01-01

    Experimental conditions are studied to optimize transient experiments for estimating temperature dependent thermal conductivity and volumetric heat capacity. A mathematical model of a specimen is the one-dimensional heat equation with boundary conditions of the second kind. Thermal properties are assumed to vary nonlinearly with temperature. Experimental conditions refer to the thermal loading scheme, sampling times and sensor location. A numerical model of experimental configurations is studied to elicit the optimal conditions. The numerical solution of the design problem is formulated on a regularization scheme with a stabilizer minimization without a regularization parameter. An explicit design criterion is used to reveal the optimal sensor location, heating duration and flux magnitude. Results obtained indicate that even the strongly nonlinear experimental design problem admits the aggregation of its solution and has a strictly defined optimal measurement scheme. Additional region of temperature measurements with allowable identification error is revealed.

  8. Characteristic functions of quantum heat with baths at different temperatures

    Science.gov (United States)

    Aurell, Erik

    2018-06-01

    This paper is about quantum heat defined as the change in energy of a bath during a process. The presentation takes into account recent developments in classical strong-coupling thermodynamics and addresses a version of quantum heat that satisfies quantum-classical correspondence. The characteristic function and the full counting statistics of quantum heat are shown to be formally similar. The paper further shows that the method can be extended to more than one bath, e.g., two baths at different temperatures, which opens up the prospect of studying correlations and heat flow. The paper extends earlier results on the expected quantum heat in the setting of one bath [E. Aurell and R. Eichhorn, New J. Phys. 17, 065007 (2015), 10.1088/1367-2630/17/6/065007; E. Aurell, Entropy 19, 595 (2017), 10.3390/e19110595].

  9. Heat Transfer Modeling for Rigid High-Temperature Fibrous Insulation

    Science.gov (United States)

    Daryabeigi, Kamran; Cunnington, George R.; Knutson, Jeffrey R.

    2012-01-01

    Combined radiation and conduction heat transfer through a high-temperature, high-porosity, rigid multiple-fiber fibrous insulation was modeled using a thermal model previously used to model heat transfer in flexible single-fiber fibrous insulation. The rigid insulation studied was alumina enhanced thermal barrier (AETB) at densities between 130 and 260 kilograms per cubic meter. The model consists of using the diffusion approximation for radiation heat transfer, a semi-empirical solid conduction model, and a standard gas conduction model. The relevant parameters needed for the heat transfer model were estimated from steady-state thermal measurements in nitrogen gas at various temperatures and environmental pressures. The heat transfer modeling methodology was evaluated by comparison with standard thermal conductivity measurements, and steady-state thermal measurements in helium and carbon dioxide gases. The heat transfer model is applicable over the temperature range of 300 to 1360 K, pressure range of 0.133 to 101.3 x 10(exp 3) Pa, and over the insulation density range of 130 to 260 kilograms per cubic meter in various gaseous environments.

  10. SCEPTIC, Pressure Drop, Flow Rate, Heat Transfer, Temperature in Reactor Heat Exchanger

    International Nuclear Information System (INIS)

    Kattchee, N.; Reynolds, W.C.

    1975-01-01

    1 - Nature of physical problem solved: SCEPTIC is a program for calculating pressure drop, flow rates, heat transfer rates, and temperature in heat exchangers such as fuel elements of typical gas or liquid cooled nuclear reactors. The effects of turbulent and heat interchange between flow passages are considered. 2 - Method of solution: The computation procedure amounts to a nodal of lumped parameter type of calculation. The axial mesh size is automatically selected to assure that a prescribed accuracy of results is obtained. 3 - Restrictions on the complexity of the problem: Maximum number of subchannels is 25, maximum number of heated surfaces is 46

  11. High-temperature gas-cooled reactors and process heat

    International Nuclear Information System (INIS)

    Kasten, P.R.

    1980-01-01

    High-Temperature Gas-Cooled Reactors (HTGRs) are fueled with ceramic-coated microspheres of uranium and thorium oxides/carbides embedded in graphite blocks which are cooled with helium. Promising areas of HTGR application are in cogeneration, energy transport using Heat Transfer Salt, recovery of oils from oil shale, steam reforming of methane for chemical production, coal gasification, and in energy transfer using chemical heat jpipes in the long term. Further, HTGRs could be used as the energy source for hydrogen production through thermochemical water splitting in the long term. The potential market for Process Heat HTGRs is 100-200 large units by about the year 2020

  12. The Specific Heat of Matter at Low Temperatures

    CERN Document Server

    Tari, A

    2003-01-01

    Recent discoveries of new materials and improvements in calorimetric techniques have given new impetus to the subject of specific heat. Nevertheless, there is a serious lack of literature on the subject. This invaluable book, which goes some way towards remedying that, is concerned mainly with the specific heat of matter at ordinary temperatures. It discusses the principles that underlie the theory of specific heat and considers a number of theoretical models in some detail. The subject matter ranges from traditional materials to those recently discovered - heavy fermion compounds, high temper

  13. High temperature nuclear process heat systems for chemical processes

    International Nuclear Information System (INIS)

    Jiacoletti, R.J.

    1976-01-01

    The development planning and status of the very high temperature gas cooled reactor as a source of industrial process heat is presented. The dwindling domestic reserves of petroleum and natural gas dictate major increases in the utilization of coal and nuclear sources to meet the national energy demand. The nuclear process heat system offers a unique combination of the two that is environmentally and economically attractive and technically sound. Conceptual studies of several energy-intensive processes coupled to a nuclear heat source are presented

  14. Heat exchanger for transfering heat produced in a high temperature reactor to an intermediate circuit gas

    International Nuclear Information System (INIS)

    Barchewitz, E.; Baumgaertner, H.

    1985-01-01

    The invention is concerned with improving the arrangement of a heat exchanger designed to transfer heat from the coolant gas circuit of a high temperature reactor to a gas which is to be used for a process heat plant. In the plant the material stresses are to be kept low at high differential pressures and temperatures. According to the invention the tube bundles designed as boxes are fixed within the heat exchanger closure by means of supply pipes having got loops. For conducting the hot gas the heat exchanger has got a central pipe leading out of the reactor vessel through the pod closure and having got only one point of fixation, lying in this closure. Additional advantageous designs are mentioned. (orig./PW)

  15. Potential of low-temperature nuclear heat applications

    International Nuclear Information System (INIS)

    1986-12-01

    At present, more than one third of the fossil fuel currently used is being consumed to produce space heating and to meet industrial needs in many countries of the world. Imported oil still represents a large portion of this fossil fuel and despite its present relatively low price future market evolutions with consequent upward cost revisions cannot be excluded. Thus the displacement of the fossil fuel by cheaper low-temperature heat produced in nuclear power plants is a matter which deserves careful consideration. Technico-economic studies in many countries have shown that the use of nuclear heat is fully competitive with most of fossil-fuelled plants, the higher investment costs being offset by lower production cost. Another point in favour of heat generation by nuclear source is its indisputable advantage in terms of benefits to the environment. The IAEA activity plans for 1985-86 concentrate on information exchange with specific emphasis on the design criteria, operating experience, safety requirements and specifications of heat-only reactors, co-generation plants and existing power plants backfitted for additional heat applications. The information gained up to 1985 was discussed during the Advisory Group Meeting on the Potential of Low-Temperature Nuclear Heat Applications held in the Federal Institute for Reactor Research, Wuerenlingen, Switzerland in September 1985 and, is included in the present Technical Document

  16. Surface temperature and surface heat flux determination of the inverse heat conduction problem for a slab

    International Nuclear Information System (INIS)

    Kuroyanagi, Toshiyuki

    1983-07-01

    Based on an idea that surface conditions should be a reflection of interior temperature and interior heat flux variation as inverse as interior conditions has been determined completely by the surface temperature and/on surface heat flux as boundary conditions, a method is presented for determining the surface temperature and the surface heat flux of a solid when the temperature and heat flux at an interior point are a prescribed function of time. The method is developed by the integration of Duhumels' integral which has unknown temperature or unknown heat flux in its integrand. Specific forms of surface condition determination are developed for a sample inverse problem: slab. Ducussing the effect of a degree of avairable informations at an interior point due to damped system and the effect of variation of surface conditions on those formulations, it is shown that those formulations are capable of representing the unknown surface conditions except for small time interval followed by discontinuous change of surface conditions. The small un-resolved time interval is demonstrated by a numerical example. An evaluation method of heat flux at an interior point, which is requested by those formulations, is discussed. (author)

  17. Effect of radiation heat transfer on the performance of high temperature heat exchanger, (2)

    International Nuclear Information System (INIS)

    Yamada, Yukio; Mori, Yasuo; Hijikata, Kunio.

    1977-01-01

    In high temperature helium gas-cooled reactors, the nuclear energy can be utilized effectively, and the safety is excellent as compared with conventional reactors. They are advantageous also in view of environmental problems. In this report, the high temperature heat exchanger used for heating steam with the helium from a high temperature gas reactor is modeled, and the case that radiating gas flow between parallel plates is considered. Analysis was made on the case of one channel and constant heat flux and on the model for a counter-flow type heat exchanger with two channels, and the effect of radiation on the heat transfer in laminar flow and turbulent flow regions was clarified theoretically. The basic equations, the method of approximate solution and the results of calculation are explained. When one dimensional radiation was considered, the representative temperature Tr regarding fluid radiation was introduced, and its relation to mean mixing temperature Tm was determined. It was clarified that the large error in the result did not arise even if Tr was taken equally to Tm, especially in case of turbulent flow. The error was practically negligible when the rate of forced convection heat transfer in case of radiating medium flow was taken same as that in the case without radiation. (Kako, I.)

  18. Temperature and heat flux scaling laws for isoviscous, infinite Prandtl number mixed heating convection.

    Science.gov (United States)

    Vilella, Kenny; Deschamps, Frederic

    2018-04-01

    Thermal evolution of terrestrial planets is controlled by heat transfer through their silicate mantles. A suitable framework for modelling this heat transport is a system including bottom heating (from the core) and internal heating, e.g., generated by secular cooling or by the decay of radioactive isotopes. The mechanism of heat transfer depends on the physical properties of the system. In systems where convection is able to operate, two different regimes are possible depending on the relative amount of bottom and internal heating. For moderate internal heating rates, the system is composed of active hot upwellings and cold downwellings. For large internal heating rates, the bottom heat flux becomes negative and the system is only composed of active cold downwellings. Here, we build theoretical scaling laws for both convective regimes following the approach of Vilella & Kaminski (2017), which links the surface heat flux and the temperature jump across both the top and bottom thermal boundary layer (TBL) to the Rayleigh number and the dimensionless internal heating rate. Theoretical predictions are then verified against numerical simulations performed in 2D and 3D-Cartesian geometry, and covering a large range of the parameter space. Our theoretical scaling laws are more successful in predicting the thermal structure of systems with large internal heating rates than that of systems with no or moderate internal heating. The differences between moderate and large internal heating rates are interpreted as differences in the mechanisms generating thermal instabilities. We identified three mechanisms: conductive growth of the TBL, instability impacting, and TBL erosion, the last two being present only for moderate internal heating rates, in which hot plumes are generated at the bottom of the system and are able to reach the surface. Finally, we apply our scaling laws to the evolution of the early Earth, proposing a new model for the cooling of the primordial magma ocean

  19. Pressure drop and heat transfer characteristics of a high-temperature printed circuit heat exchanger

    International Nuclear Information System (INIS)

    Chen, Minghui; Sun, Xiaodong; Christensen, Richard N.; Skavdahl, Isaac; Utgikar, Vivek; Sabharwall, Piyush

    2016-01-01

    Highlights: • Pressure drop and heat transfer characteristics of a high-temperature printed circuit heat exchanger have been obtained. • Comparisons of experimental data and available correlations have been performed. • New Fanning friction factor and heat transfer correlations for the test PCHE are developed. - Abstract: Printed circuit heat exchanger (PCHE) is one of the leading intermediate heat exchanger (IHX) candidates to be employed in the very-high-temperature gas-cooled reactors (VHTRs) due to its capability for high-temperature, high-pressure applications. In the current study, a reduced-scale zigzag-channel PCHE was fabricated using Alloy 617 plates for the heat exchanger core and Alloy 800H pipes for the headers. The pressure drop and heat transfer characteristics of the PCHE were investigated experimentally in a high-temperature helium test facility (HTHF) at The Ohio State University. The PCHE helium inlet temperatures and pressures were varied up to 464 °C/2.7 MPa for the cold side and 802 °C/2.7 MPa for the hot side, respectively, while the maximum helium mass flow rates on both sides of the PCHE reached 39 kg/h. The corresponding maximum channel Reynolds number was approximately 3558, covering the laminar flow and laminar-to-turbulent flow transition regimes. New pressure drop and heat transfer correlations for the current zigzag channels with rounded bends were developed based on the experimental data. Comparisons between the experimental data and the results obtained from the available PCHE and straight circular pipe correlations were conducted. Compared to the heat transfer performance in straight circular pipes, the zigzag channels provided little advantage in the laminar flow regime but significant advantage near the transition flow regime.

  20. Heat Exchangers for Utilization of the Heat of High-Temperature Geothermal Brines

    Science.gov (United States)

    Alkhasov, A. B.; Alkhasova, D. A.

    2018-03-01

    The basic component of two-circuit geothermal systems is the heat exchanger. When used in geothermal power systems, conventional shell-and-tube and plate heat exchangers cause problems related to the cleaning of the latter from salt-deposition and corrosion products. Their lifetime does not exceed, as a rule, 1 year. To utilize the heat of high-temperature geothermal brines, a heat exchanger of the "tube-in-tube" type is proposed. A heat exchanger of this design has been operated for several years in Ternair geothermal steam field; in this heat exchanger, the thermal potential of the saline thermal water is transferred to the fresh water of the secondary circuit of the heating system for apartment houses. The reduction in the weight and size characteristics of the heat exchangers is a topical problem that can be solved with the help of heat transfer enhancers. To enhance the heat transfer process in the heat exchanger, longitudinal ribbing of the heat exchange surface is proposed. The increase in the heat exchange surface from the heat carrier side by ribbing results in an increase in the amount of the heat transferred from the heating agent. The heat exchanger is easy to manufacture and is assembled out of components comprised of two concentrically positioned tubes of a definite length, 3-6 m, serially connected with each other. The method for calculation of the impact of the number and the size of the longitudinal ribs on the heat transfer in the well heat exchanger is presented and a criterion for the selection of the optimal number and design parameters of the ribs is formulated. To prevent the corrosion and salt deposition in the heat exchanger, the use of an effective OEDFK (oxyethylidenediphosphonic acid) agent is proposed. This agent has a long-lasting corrosion-inhibiting and antiscaling effect, which is explained by the formation of a strongly adhesive chelate layer difficult to wash off the surface. The passivating OEDFK layer is restored by periodical

  1. Recovery Temperature, Transition, and Heat Transfer Measurements at Mach 5

    Science.gov (United States)

    Brinich, Paul F.

    1961-01-01

    Schlieren, recovery temperature, and heat-transfer measurements were made on a hollow cylinder and a cone with axes alined parallel to the stream. Both the cone and cylinder were equipped with various bluntnesses, and the tests covered a Reynolds number range up to 20 x 10(exp 6) at a free-stream Mach number of 4.95 and wall to free-stream temperature ratios from 1.8 to 5.2 (adiabatic). A substantial transition delay due to bluntness was found for both the cylinder and the cone. For the present tests (Mach 4.95), transition was delayed by a factor of 3 on the cylinder and about 2 on the cone, these delays being somewhat larger than those observed in earlier tests at Mach 3.1. Heat-transfer tests on the cylinder showed only slight effects of wall temperature level on transition location; this is to be contrasted to the large transition delays observed on conical-type bodies at low surface temperatures at Mach 3.1. The schlieren and the peak-recovery-temperature methods of detecting transition were compared with the heat-transfer results. The comparison showed that the first two methods identified a transition point which occurred just beyond the end of the laminar run as seen in the heat-transfer data.

  2. Decentralized substations for low-temperature district heating with no Legionella risk, and low return temperatures

    DEFF Research Database (Denmark)

    Yang, Xiaochen; Li, Hongwei; Svendsen, Svend

    2016-01-01

    . From the results, realizing LTDH by the decentralized substation unit, 30% of the annual distribution heat loss inside the building can be saved compared to a conventional system with medium-temperature district heating. Replacing the bypass pipe with an in-line supply pipe and a heat pump...... with domestic hot water (DHW) circulation. In this study, a system with decentralized substations was analysed as a solution to this problem. Furthermore, a modification for the decentralized substation system were proposed in order to reduce the average return temperature. Models of conventional system...... with medium-temperature district heating, decentralized substation system with LTDH, and innovative decentralized substation system with LTDH were built based on the information of a case building. The annual distribution heat loss and the operating costs of the three scenarios were calculated and compared...

  3. Process heat cogeneration using a high temperature reactor

    International Nuclear Information System (INIS)

    Alonso, Gustavo; Ramirez, Ramon; Valle, Edmundo del; Castillo, Rogelio

    2014-01-01

    Highlights: • HTR feasibility for process heat cogeneration is assessed. • A cogeneration coupling for HTR is proposed and process heat cost is evaluated. • A CCGT process heat cogeneration set up is also assessed. • Technical comparison between both sources of cogeneration is performed. • Economical competitiveness of the HTR for process heat cogeneration is analyzed. - Abstract: High temperature nuclear reactors offer the possibility to generate process heat that could be used in the oil industry, particularly in refineries for gasoline production. These technologies are still under development and none of them has shown how this can be possible and what will be the penalty in electricity generation to have this additional product and if the cost of this subproduct will be competitive with other alternatives. The current study assesses the likeliness of generating process heat from Pebble Bed Modular Reactor to be used for a refinery showing different plant balances and alternatives to produce and use that process heat. An actual practical example is presented to demonstrate the cogeneration viability using the fact that the PBMR is a modular small reactor where the cycle configuration to transport the heat of the reactor to the process plant plays an important role in the cycle efficiency and in the plant economics. The results of this study show that the PBMR would be most competitive when capital discount rates are low (5%), carbon prices are high (>30 US$/ton), and competing natural gas prices are at least 8 US$/mmBTU

  4. Process heat cogeneration using a high temperature reactor

    Energy Technology Data Exchange (ETDEWEB)

    Alonso, Gustavo, E-mail: gustavoalonso3@gmail.com [Instituto Nacional de Investigaciones Nucleares, Carretera Mexico-Toluca s/n, Ocoyoacac, Edo. De Mexico 52750 (Mexico); Instituto Politécnico Nacional, Unidad Profesional Adolfo Lopez Mateos, Ed. 9, Lindavista, D.F. 07300 (Mexico); Ramirez, Ramon [Instituto Nacional de Investigaciones Nucleares, Carretera Mexico-Toluca s/n, Ocoyoacac, Edo. De Mexico 52750 (Mexico); Valle, Edmundo del [Instituto Politécnico Nacional, Unidad Profesional Adolfo Lopez Mateos, Ed. 9, Lindavista, D.F. 07300 (Mexico); Castillo, Rogelio [Instituto Nacional de Investigaciones Nucleares, Carretera Mexico-Toluca s/n, Ocoyoacac, Edo. De Mexico 52750 (Mexico)

    2014-12-15

    Highlights: • HTR feasibility for process heat cogeneration is assessed. • A cogeneration coupling for HTR is proposed and process heat cost is evaluated. • A CCGT process heat cogeneration set up is also assessed. • Technical comparison between both sources of cogeneration is performed. • Economical competitiveness of the HTR for process heat cogeneration is analyzed. - Abstract: High temperature nuclear reactors offer the possibility to generate process heat that could be used in the oil industry, particularly in refineries for gasoline production. These technologies are still under development and none of them has shown how this can be possible and what will be the penalty in electricity generation to have this additional product and if the cost of this subproduct will be competitive with other alternatives. The current study assesses the likeliness of generating process heat from Pebble Bed Modular Reactor to be used for a refinery showing different plant balances and alternatives to produce and use that process heat. An actual practical example is presented to demonstrate the cogeneration viability using the fact that the PBMR is a modular small reactor where the cycle configuration to transport the heat of the reactor to the process plant plays an important role in the cycle efficiency and in the plant economics. The results of this study show that the PBMR would be most competitive when capital discount rates are low (5%), carbon prices are high (>30 US$/ton), and competing natural gas prices are at least 8 US$/mmBTU.

  5. Performance correlations for high temperature potassium heat pipes

    International Nuclear Information System (INIS)

    Merrigan, M.A.; Keddy, E.S.; Sena, J.T.

    1987-01-01

    Potassium heat pipes designed for operation at a nominal temperature of 775K have been developed for use in a heat pipe cooled reactor design. The heat pipes operate in a gravity assist mode with a maximum required power throughput of approximately 16 kW per heat pipe. Based on a series of sub-scale experiments with 2.12 and 3.2 cm diameter heat pipes the prototypic heat pipe diameter was set at 5.7 cm with a simple knurled wall wick used in the interests of mechanical simplicity. The performance levels required for this design had been demonstrated in prior work with gutter assisted wicks and emphasis in the present work was on the attainment of similar performance with a simplified wick structure. The wick structure used in the experiment consisted of a pattern of knurled grooves in the internal wall of the heat pipe. The knurl depth required for the planned heat pipe performance was determined by scaling of wick characteristic data from the sub-scale tests. These tests indicated that the maximum performance limits of the test heat pipes did not follow normal entrainment limit predictions for textured wall gravity assist heat pipes. Test data was therefore scaled to the prototype design based on the assumption that the performance was controlled by an entrainment parameter based on the liquid flow depth in the groove structure. This correlation provided a reasonable fit to the sub-scale test data and was used in scale up of the design from the 8.0 cm 2 cross section of the largest sub-scale heat pipe to the 25.5 cm 2 cross section prototype. Correlation of the model predictions with test data from the prototype is discussed

  6. CARS Temperature Measurements in a Combustion-Heated Supersonic Jet

    Science.gov (United States)

    Tedder, S. A.; Danehy, P. M.; Magnotti, G.; Cutler, A. D.

    2009-01-01

    Measurements were made in a combustion-heated supersonic axi-symmetric free jet from a nozzle with a diameter of 6.35 cm using dual-pump Coherent Anti-Stokes Raman Spectroscopy (CARS). The resulting mean and standard deviation temperature maps are presented. The temperature results show that the gas temperature on the centerline remains constant for approximately 5 nozzle diameters. As the heated gas mixes with the ambient air further downstream the mean temperature decreases. The standard deviation map shows evidence of the increase of turbulence in the shear layer as the jet proceeds downstream and mixes with the ambient air. The challenges of collecting data in a harsh environment are discussed along with influences to the data. The yield of the data collected is presented and possible improvements to the yield is presented are discussed.

  7. On Chaotic Behavior of Temperature Distribution in a Heat Exchanger

    Science.gov (United States)

    Bagyalakshmi, Morachan; Gangadharan, Saisundarakrishnan; Ganesh, Madhu

    The objective of this paper is to introduce the notion of fractional derivatives in the energy equations and to study the chaotic nature of the temperature distribution in a heat exchanger with variation of temperature dependent transport properties. The governing fractional partial differential equations are transformed to a set of recurrence relations using fractional differential transform method and solved using inverse transform. The approximate analytical solution obtained by the proposed method has good agreement with the existing results.

  8. Comparative technical-economic analysis of the low temperature heating systems

    International Nuclear Information System (INIS)

    Sharevski, Vasko; Sharevski, Milan

    1994-01-01

    A method for comparative technical-economic analysis between low temperature heating systems and heating systems with fossil fuel boiler plant, heat pump heating system and electrical heating systems is presented. The single and combined heating systems are analyzed. The technical-economic priority application of the heating system is determined according to the prices of the low temperature heat energy, fossil fuel heat energy, electrical energy, as well as to the coefficient of the annual use of the installed heating capacity, investment expenses, structure of the combined heating system and coefficient of performances of the heat pump. The combined heating system, composed with a low temperature heating subsystem, which is used to cover the base heat demands, and a oil boiler plant heating subsystem, for the top heat demands, have technical-economic justification and wide range of priority application, in comparison with single heating systems. (author)

  9. Waste Heat Recovery from a High Temperature Diesel Engine

    Science.gov (United States)

    Adler, Jonas E.

    Government-mandated improvements in fuel economy and emissions from internal combustion engines (ICEs) are driving innovation in engine efficiency. Though incremental efficiency gains have been achieved, most combustion engines are still only 30-40% efficient at best, with most of the remaining fuel energy being rejected to the environment as waste heat through engine coolant and exhaust gases. Attempts have been made to harness this waste heat and use it to drive a Rankine cycle and produce additional work to improve efficiency. Research on waste heat recovery (WHR) demonstrates that it is possible to improve overall efficiency by converting wasted heat into usable work, but relative gains in overall efficiency are typically minimal ( 5-8%) and often do not justify the cost and space requirements of a WHR system. The primary limitation of the current state-of-the-art in WHR is the low temperature of the engine coolant ( 90 °C), which minimizes the WHR from a heat source that represents between 20% and 30% of the fuel energy. The current research proposes increasing the engine coolant temperature to improve the utilization of coolant waste heat as one possible path to achieving greater WHR system effectiveness. An experiment was performed to evaluate the effects of running a diesel engine at elevated coolant temperatures and to estimate the efficiency benefits. An energy balance was performed on a modified 3-cylinder diesel engine at six different coolant temperatures (90 °C, 100 °C, 125 °C, 150 °C, 175 °C, and 200 °C) to determine the change in quantity and quality of waste heat as the coolant temperature increased. The waste heat was measured using the flow rates and temperature differences of the coolant, engine oil, and exhaust flow streams into and out of the engine. Custom cooling and engine oil systems were fabricated to provide adequate adjustment to achieve target coolant and oil temperatures and large enough temperature differences across the

  10. Radiation effects on heat transfer in heat exchangers, (2)

    International Nuclear Information System (INIS)

    Mori, Yasuo; Watanabe, Kenji; Taira, Tatsuji.

    1980-01-01

    In a high temperature gas-cooled reactor system, in which the working fluid exchanges heat at high temperature near 1000 deg C, the heat transfer acceleration by positively utilizing the radiation heat transfer between solid surfaces should be considered. This paper reports on the results of experiment and analysis for the effects of radiant heat on the heat transfer performance at elevated temperature by applying the heat transfer-accelerating method using radiators to the heat exchanger with tube bundle composed of two channels of heating and heated sides. As the test heat exchangers, a parallel counter flow exchanger and the cross flow exchanger simulating helical tubes were employed, and the results studied on the characteristics of each heat exchanger are described. The plates placed in parallel to flow in every space of the tube bundle arranged in a matrix were used as the heat transfer accelerator. The effects of acceleration with the plates were the increase of heat transmission from 12 to 24% and 12 to 38% in the parallel flow and cross flow heat exchangers, respectively. Also, it was clarified that the theoretical analysis, in which it was assumed that the region within pitch S and two radiator plates, with a heat-transferring tube placed at the center, is the minimum domain for calculation, and that the heat exchange by radiation occurs only between the domain and the adjacent domains, can estimate the heat transfer-accelerating effect and the temperature distribution in a heat exchanger with sufficient accuracy. (Wakatsuki, Y.)

  11. Characteristics of infrared thermometers manufactured in Japan and calibration methods for sky radiant emittance

    International Nuclear Information System (INIS)

    Wang, X.; Horiguchi, I.; Machimura, T.

    1993-01-01

    Infrared thermometers to measure surface temperature have been increasingly adopted in recent years. The characteristics of the IR thermometer, however, are not well known.IR thermometers manufactured in Japan systematically adjust for ambient radiation based on the internal temperature of the thermometer. If, therefore, there is a large difference between the internal temperature of the IR thermometer and the apparent temperature associated with the surrounding radiation, a large error will be induced into the measured surface temperature.The purpose of our research was to determine the characteristics and measurement errors of IR thermometers. Experiments were performed with regard to the following items: (1) Measurement errors related to the internal temperature of the IR thermometer. (2) Linearity of the output signal of the IR thermometer. (3) Response of the output signal to changes in the emissivity setting. (4) Effect of sky radiant emittance on the measured surface temperature. (5) Calibration method for the terrestrial surface.The following is a summary of the results: Measurement error is affected by the internal temperature of the IR thermometer. Measurement accuracy is improved with a controlled internal temperature of 20-30°C. The measurement error becomes larger at emissivity settings under 0.7.The measurement error outdoors was not proportional to the downward longwave radiation, but to the sky radiant temperature measured by the IR thermometer. Calibration for sky radiant emittance was improved by using the difference between sky radiant temperature and air temperature.When the surface temperature measured by the infrared thermometer is plotted against the surface temperature measured by thermocouple, the sky radiant emittance error is obtained from the Y intercept. Additionally, the difference between true temperature and output of the IR thermometer for a reference plate was compared to that obtained for vegetation, and the RMS obtained was

  12. High temperature heat capacities and electrical conductivities of boron carbides

    International Nuclear Information System (INIS)

    Matsui, Tsuneo; Arita, Yuri; Naito, Keiji; Imai, Hisashi

    1991-01-01

    The heat capacities and the electrical conductivities of B x C(x=3, 4, 5) were measured by means of direct heating pulse calorimetry in the temperature range from 300 to 1500 K. The heat capacities of B x C increased with increasing x value. This increase in the heat capacity is probably related to the change of the lattice vibration mode originated from the reduction of the stiffness of the intericosahedral chain accompanied with a change from C-B-C to C-B-B chains. A linear relationship between the logarithm of σT (σ is the electrical conductivity and T is the absolute temperature) of B x C and the reciprocal temperature was observed, indicating the presence of small polaron hopping as the predominant conduction mechanism. The electrical conductivity of B x C also increased with increasing x value (from 4 to 5) due to an increase of the polaron hopping of holes between carbon atoms at geometrically nonequivalent sites, since these nonequivalent sites of carbon atoms were considered to increase in either B 11 C icosahedra or in icosahedral chains with increasing x. The electrical conductivity of B 3 C was higher than that of B 4 C, which is probably due to the precipitation of high-conducting carbon. The thermal conductivity and the thermodynamic quantities of B 4 C were also determined precisely from the heat capacity value. (orig.)

  13. Effect of re-heating on the hot electron temperature

    International Nuclear Information System (INIS)

    Estabrook, K.; Rosen, M.

    1980-01-01

    Resonant absorption is the direct conversion of the transverse laser light to longitudinal electron plasma waves (epw) at the critical density [10 21 (1.06 μm/lambda 0 ) 2 cm -3 ]. The oscillating longitudinal electric field of the epw heats the electrons by accelerating them down the density gradient to a temperature of approximately 21T/sub e/ 0 25 ([I(W/cm 2 )/10 16 ](lambda 0 /1.06 μm) 2 ) 0 4 . This section extends the previous work by studying the effects of magnetic fields and collisions (albedo) which return the heated electrons for further heating. A magnetic field increases their temperature and collisions do not

  14. Influence of heat treatment temperature on bonding and oxidation ...

    Indian Academy of Sciences (India)

    The effects of heat treatment temperature on the morphology, composition, chemical bonds, oxidation resistance and compressive strength of diamond particles coated with TiO2 films were characterized through scanning electron microscopy, Fourier transform infrared, Raman spectroscopy, X-ray diffraction analysis, X-ray ...

  15. Influence of heat treatment temperature on bonding and oxidation ...

    Indian Academy of Sciences (India)

    Administrator

    Diamond; TiO2 film; heat treatment temperature; anti-oxidation; mechanical properties. 1. Introduction. Due to its ..... figure 4a, which was due to the change of chemical envi- ronment of ... graphite, diamond, diamond-like carbon and carbon.10.

  16. Color, Temperature and Heat: Exploring University Students Mental Thoughts

    Science.gov (United States)

    Canlas, Ian Phil

    2016-01-01

    Color, temperature and heat are among the concepts in science that are interconnected. These concepts are introduced to learners even before they enter the basic education. On the other hand, in school, it is formally introduced to them not only in science but also in the humanities. The foregoing study attempted to explore the mental thoughts of…

  17. TEMPERATURE DISTRIBUTION MONITORING AND ANALYSES AT DIFFERENT HEATING CONTROL PRINCIPLES

    DEFF Research Database (Denmark)

    Simone, Angela; Rode, Carsten; Olesen, Bjarne W.

    2010-01-01

    under different control strategies of the heating system (Pseudo Random Binary Sequence signal controlling all the heaters (PRBS) or thermostatic control of the heaters (THERM)). A comparison of the measured temperatures within the room, for the five series of experiments, shows a better correlation...

  18. Fast temperature programming in gas chromatography using resistive heating

    NARCIS (Netherlands)

    Dallüge, J.; Ou-Aissa, R.; Vreuls, J.J.; Brinkman, U.A.T.; Veraart, J.R.

    1999-01-01

    The features of a resistive-heated capillary column for fast temperature-programmed gas chromatography (GC) have been evaluated. Experiments were carried out using a commercial available EZ Flash GC, an assembly which can be used to upgrade existing gas chromatographs. The capillary column is placed

  19. The theory of heat radiation

    CERN Document Server

    Planck, Max

    2003-01-01

    Nobel laureate's classic exposition of the theory of radiant heat in terms of quantum action. Kirchoff's law, black radiation, Maxwell's radiation pressure, entropy, other topics. 1914 edition. Bibliography.

  20. Startup analysis for a high temperature gas loaded heat pipe

    Science.gov (United States)

    Sockol, P. M.

    1973-01-01

    A model for the rapid startup of a high-temperature gas-loaded heat pipe is presented. A two-dimensional diffusion analysis is used to determine the rate of energy transport by the vapor between the hot and cold zones of the pipe. The vapor transport rate is then incorporated in a simple thermal model of the startup of a radiation-cooled heat pipe. Numerical results for an argon-lithium system show that radial diffusion to the cold wall can produce large vapor flow rates during a rapid startup. The results also show that startup is not initiated until the vapor pressure p sub v in the hot zone reaches a precise value proportional to the initial gas pressure p sub i. Through proper choice of p sub i, startup can be delayed until p sub v is large enough to support a heat-transfer rate sufficient to overcome a thermal load on the heat pipe.

  1. High temperature reactor and application to nuclear process heat

    Energy Technology Data Exchange (ETDEWEB)

    Schulten, R; Kugeler, K [Kernforschungsanlage Juelich G.m.b.H. (Germany, F.R.)

    1976-01-01

    The principle of high temperature nuclear process heat is explained and the main applications (hydrogasification of coal, nuclear chemical heat pipe, direct reduction of iron ore, coal gasification by steam and water splitting) are described in more detail. The motivation for the introduction of nuclear process heat to the market, questions of cost, of raw material resources and environmental aspects are the next point of discussion. The new technological questions of the nuclear reactor and the status of development are described, especially information about the fuel elements, the hot gas ducts, the contamination and some design considerations are added. Furthermore the status of development of helium heated steam reformers, the main results of the work until now and the further activities in this field are explained.

  2. Small reactors for low-temperature nuclear heat applications

    International Nuclear Information System (INIS)

    1988-06-01

    In accordance with the Member States' calls for information exchange in the field of nuclear heat application (NHA) two IAEA meetings were organized already in 1976 and 1977. After this ''promising period'', the development of relevant programmes in IAEA Member States was slowed down and therefore only after several years interruption a new Technical Committee Meeting with a Workshop was organized in late 1983, to review the status of NHA, after a few new specific plans appeared in some IAEA Member States in the early 1980's for the use of heat from existing or constructed NPPs and for developing nuclear heating plants (NHP). In June 1987 an Advisory Group Meeting was convened in Winnipeg, Canada, to discuss and formulate a state-of-the-art review on ''Small Reactors for Low Temperature Nuclear Heat Application''. Information on this subject gained up to 1987 in the Member States whose experts attended this meeting is embodied in the present Technical Report. Figs and tabs

  3. Suppression of the sonic heat transfer limit in high-temperature heat pipes

    Science.gov (United States)

    Dobran, Flavio

    1989-08-01

    The design of high-performance heat pipes requires optimization of heat transfer surfaces and liquid and vapor flow channels to suppress the heat transfer operating limits. In the paper an analytical model of the vapor flow in high-temperature heat pipes is presented, showing that the axial heat transport capacity limited by the sonic heat transfer limit depends on the working fluid, vapor flow area, manner of liquid evaporation into the vapor core of the evaporator, and lengths of the evaporator and adiabatic regions. Limited comparisons of the model predictions with data of the sonic heat transfer limits are shown to be very reasonable, giving credibility to the proposed analytical approach to determine the effect of various parameters on the axial heat transport capacity. Large axial heat transfer rates can be achieved with large vapor flow cross-sectional areas, small lengths of evaporator and adiabatic regions or a vapor flow area increase in these regions, and liquid evaporation in the evaporator normal to the main flow.

  4. Influence of ambient temperatures on performance of a CO2 heat pump water heating system

    International Nuclear Information System (INIS)

    Yokoyama, Ryohei; Shimizu, Takeshi; Ito, Koichi; Takemura, Kazuhisa

    2007-01-01

    In residential applications, an air-to-water CO 2 heat pump is used in combination with a domestic hot water storage tank, and the performance of this system is affected significantly not only by instantaneous ambient air and city water temperatures but also by hourly changes of domestic hot water consumption and temperature distribution in the storage tank. In this paper, the performance of a CO 2 heat pump water heating system is analyzed by numerical simulation. A simulation model is created based on thermodynamic equations, and the values of model parameters are estimated based on measured data for existing devices. The calculated performance is compared with the measured one, and the simulation model is validated. The system performance is clarified in consideration of seasonal changes of ambient air and city water temperatures

  5. Mask humidity during CPAP: influence of ambient temperature, heated humidification and heated tubing.

    Science.gov (United States)

    Nilius, Georg; Domanski, Ulrike; Schroeder, Maik; Woehrle, Holger; Graml, Andrea; Franke, Karl-Josef

    2018-01-01

    Mucosal drying during continuous positive airway pressure (CPAP) therapy is problematic for many patients. This study assessed the influence of ambient relative humidity (rH) and air temperature (T) in winter and summer on mask humidity during CPAP, with and without mask leak, and with or without heated humidification ± heated tubing. CPAP (8 and 12 cmH 2 O) without humidification (no humidity [nH]), with heated humidification controlled by ambient temperature and humidity (heated humidity [HH]) and HH plus heated tubing climate line (CL), with and without leakage, were compared in 18 subjects with OSA during summer and winter. The absolute humidity (aH) and the T inside the mask during CPAP were significantly lower in winter versus summer under all applied conditions. Overall, absolute humidity differences between summer and winter were statistically significant in both HH and CL vs. nH ( p humidification or with standard HH. Clinically-relevant reductions in aH were documented during CPAP given under winter conditions. The addition of heated humidification, using a heated tube to avoid condensation is recommended to increase aH, which could be useful in CPAP users complaining of nose and throat symptoms.

  6. Elevated-temperature tensile properties of three heats of commercially heat-treated Alloy 718

    International Nuclear Information System (INIS)

    Booker, M.K.; Booker, B.L.P.

    1980-03-01

    Three heats of commercially heat-treated alloy 718 were tensile tested over the temperature range from room temperature to 816 degree C and at nominal strain rates from 6.7 x 10 -6 to 6.7 x 10 -3 /s. We examined data for yield strength, ultimate tensile strength, uniform elongation, total elongation, and reduction in area and also inspected tensile stress-strain behavior. Yield and ultimate tensile strengths for commercially heat-treated alloy 718 decrease very gradually with temperature from room temperature up to about 600 degree C for a strain rate of 6.7 x 10 -5 /s or to about 700 degree C for a strain rate of 6.7 x 10 -4 /s. Above these temperatures the strength drops off fairly rapidly. Reduction in area and total elongation data show minimum around 700 degree C, with each ductility measure falling to 10% or less at the minimum. This minimum is more pranced and occurs at lower temperatures as strain rate decreases. Up to about 600 degree C the ductility is typically around 30%. As the temperature reaches 816 degree C the ductility again increases to perhaps 60%. The uniform elongation (plastic strain at peak load) decreases only slightly with temperature to about 500 degree C then drops off rapidly and monotonically with temperature, reaching values less than 1% at 816 degree C. At the highest test temperatures the load maximum may result, not from necking of the specimen, but from overaging of the precipitation-hardened microstructure. Stress-strain curves showed serrated deformations in the temperature range from 316 to 649 degree C, although they occur only for the faster strain rates at the supper end of this temperature range. The serrations can be quite large, involving load drops of perhaps 40 to 80 MPa. The serrations typically begin within the first 2% of deformation and continue until fracture, although exceptions were noted. 16 refs., 14 figs., 3 tabs

  7. Threshold heating temperature for magnetic hyperthermia: Controlling the heat exchange with the blocking temperature of magnetic nanoparticles

    Science.gov (United States)

    Pimentel, B.; Caraballo-Vivas, R. J.; Checca, N. R.; Zverev, V. I.; Salakhova, R. T.; Makarova, L. A.; Pyatakov, A. P.; Perov, N. S.; Tishin, A. M.; Shtil, A. A.; Rossi, A. L.; Reis, M. S.

    2018-04-01

    La0.75Sr0.25MnO3 nanoparticles with average diameter close to 20.9 nm were synthesized using a sol-gel method. Measurements showed that the heating process stops at the blocking temperaturesignificantly below the Curie temperature. Measurements of Specific Absorption Rate (SAR) as a function of AC magnetic field revealed a superquadratic power law, indicating that, in addition to usual Néel and Brown relaxation, the hysteresis also plays an important role in the mechanism of heating. The ability to control the threshold heating temperature, a low remanent magnetization and a low field needed to achieve the magnetic saturation are the advantages of this material for therapeutic magnetic hyperthermia.

  8. Temperature control with high performance gravity-assist heat pipes

    International Nuclear Information System (INIS)

    Kemme, J.E.; Deverall, J.E.; Keddy, E.S.; Phillips, J.R.; Ranken, W.A.

    1975-01-01

    The development of high performance heat pipes for controlling the temperature of irradiation experiments in the Experimental Breeder Reactor (EBR-II) is described. Because this application involves vertical operation in a gravity-assist mode with the evaporator down, several tests were made with sodium and potassium heat pipes in this position to establish their performance limits as a function of operating temperature. Best performance was achieved with a new wick structure consisting of a fine porous liner next to the heat-pipe wall and four helical channels next to the vapor passage. Also, a new modification of heat-pipe theory was discovered for determining performance limits for this type of wick. In its most rudimentary form, this modification says that the dynamic pressure gradient in the vapor stream cannot exceed the gravity gradient causing return of liquid. Once this modification was expressed in the form of a limiting equation, and a term was added to account for the slight capillary force developed in the channels, good agreement was obtained between calculated limits and those measured in several tests with both sodium and potassium. These tests showed rather conclusively that only half of the liquid head in the evaporator section was causing return of condensate, whereas existing theory predicts that the full head of liquid in the heat pipe is available for condensate return. (U.S.)

  9. Radiant coolers - Theory, flight histories, design comparisons and future applications

    Science.gov (United States)

    Donohoe, M. J.; Sherman, A.; Hickman, D. E.

    1975-01-01

    Radiant coolers have been developed for application to the cooling of infrared detectors aboard NASA earth observation systems and as part of the Defense Meteorological Satellite Program. The prime design constraints for these coolers are the location of the cooler aboard the satellite and the satellite orbit. Flight data from several coolers indicates that, in general, design temperatures are achieved. However, potential problems relative to the contamination of cold surfaces are also revealed by the data. A comparison among the various cooler designs and flight performances indicates design improvements that can minimize the contamination problem in the future.

  10. The influence of river water temperature annual variation to the moderator heat exchangers heat flux

    International Nuclear Information System (INIS)

    Nita, I. P.

    2015-01-01

    The Main Moderator heat exchangers are the most important consumers supplied by Recirculated Cooling Water (RCW) System. In order to determine an appropriate operating configuration of the RCW system it is needed to determine the flowrate required by the Main Moderator consumers, in real time. From operating experience, the required RCW flowrate necessary to be supplied to the main moderator heat exchangers is much lower than design flowrate. In installation, there are no flow elements that could measure especially that flow. However, there are two control valves which regulate the flow to the main moderator heaters; they control the outlet temperature of the moderator to 69"oC. That leads to the requirement of calculating the flowrate function of the outside temperature for all possible temperatures during a calendar year. One considered all possible temperatures during an operating year, and more, going beyond design point, up to 36"oC, temperature that can occur during quick transients after forth RCW pump starting. The calculation was made to verify the capacity of heat exchanger to remove the designed 100 MW(t) in the new condition of reducing moderator temperature outlet from 77 to 69°C. The obtained model was validated using field temperatures and flow measurements and the conclusion was the model can accurately predict how the RCW system operates in all year operation conditions. (authors)

  11. Utilization of low temperature heat for environmentally friendly electricity production

    DEFF Research Database (Denmark)

    Andreasen, Jesper Graa; Elmegaard, Brian; Haglind, Fredrik

    2014-01-01

    the benefits of using mixtures compared to pure fluids as working fluids in organic Rankine cycles. In order to do so, thermodynamic and economic analyses are carried out, first on an overall cycle level, and next on component level including detailed modelling of heat exchangers, pumps and expanders involving...... project collaborators with expertise in these areas. In addition to this, novel innovative cycle layouts are developed with the aim of increasing the economic feasibility of utilizing low temperature heat. As an example, this can be achieved by implementing separators in the power cycle to create optimal...

  12. Heat transfer from a high temperature condensable mixture

    International Nuclear Information System (INIS)

    Chan, S.H.; Cho, D.H.; Condiff, D.W.

    1980-01-01

    Bulk condensation and heat transfer in a very hot gaseous mixture that contains a vapor component condensable at high temperature are investigated. A general formulation of the problem is presented in various forms. Analytical solutions for three specific cases involving both one- and two-component two-phase mixtures are obtained. It is shown that a detached fog formation is induced by rapid radiative cooling from the mixture. The formation of radiatively induced fog is found to be an interesting and important phenomenon as it not only exhibits unique features different from the conventional diffusion induced fog, but also greatly enhances heat transfer from the mixture to the boundary. (author)

  13. Heat exchangers for high-temperature thermodynamic cycles

    International Nuclear Information System (INIS)

    Fraas, A.P.

    1975-01-01

    The special requirements of heat exchangers for high temperature thermodynamic cycles are outlined and discussed with particular emphasis on cost and thermal stress problems. Typical approaches that have been taken to a comprehensive solution intended to meet all of the many boundary conditions are then considered by examining seven typical designs including liquid-to-liquid heat exchangers for nuclear plants, a heater for a closed cycle gas turbine coupled to a fluidized bed coal combustion chamber, steam generators for nuclear plants, a fossil fuel-fired potassium boiler, and a potassium condenser-steam generator. (auth)

  14. Solar-assisted heat pump – A sustainable system for low-temperature water heating applications

    International Nuclear Information System (INIS)

    Chaturvedi, S.K.; Gagrani, V.D.; Abdel-Salam, T.M.

    2014-01-01

    Highlights: • DX-SAHP water heaters systems are economical as well as energy conserving. • The economic analysis is performed using the life cycle cost (LCC) analysis. • LCC can be optimized with respect to the collector area at a specific temperature. • For high load temperature range a two stage heat pump system is more appropriate. - Abstract: Direct expansion solar assisted heat pump systems (DX-SAHP) have been widely used in many applications including water heating. In the DX-SAHP systems the solar collector and the heat pump evaporator are integrated into a single unit in order to transfer the solar energy to the refrigerant. The present work is aimed at studying the use of the DX-SAHP for low temperature water heating applications. The novel aspect of this paper involves a detailed long-term thermo-economic analysis of the energy conservation potential and economic viability of these systems. The thermal performance is simulated using a computer program that incorporates location dependent radiation, collector, economic, heat pump and load data. The economic analysis is performed using the life cycle cost (LCC) method. Results indicate that the DX-SAHP water heaters systems when compared to the conventional electrical water heaters are both economical as well as energy conserving. The analysis also reveals that the minimum value of the system life cycle cost is achieved at optimal values of the solar collector area as well as the compressor displacement capacity. Since the cost of SAHP system presents a barrier to mass scale commercialization, the results of the present study indicating that the SAHP life cycle cost can be minimized by optimizing the collector area would certainly be helpful in lowering, if not eliminating, the economic barrier to these systems. Also, at load temperatures higher than 70 °C, the performance of the single stage heat pump degrades to the extent that its cost and efficiency advantages over the electric only system are

  15. Measurement of a surface heat flux and temperature

    Science.gov (United States)

    Davis, R. M.; Antoine, G. J.; Diller, T. E.; Wicks, A. L.

    1994-04-01

    The Heat Flux Microsensor is a new sensor which was recently patented by Virginia Tech and is just starting to be marketed by Vatell Corp. The sensor is made using the thin-film microfabrication techniques directly on the material that is to be measured. It consists of several thin-film layers forming a differential thermopile across a thermal resistance layer. The measured heat flux q is proportional to the temperature difference across the resistance layer q= k(sub g)/delta(sub g) x (t(sub 1) - T(sub 2)), where k(sub g) is the thermal conductivity and delta (sub g) is the thickness of the thermal resistance layer. Because the gages are sputter coated directly onto the surface, their total thickness is less than 2 micrometers, which is two orders of magnitude thinner than previous gages. The resulting temperature difference across the thermal resistance layer (delta is less than 1 micrometer) is very small even at high heat fluxes. To generate a measurable signal many thermocouple pairs are put in series to form a differential thermopile. The combination of series thermocouple junctions and thin-film design creates a gage with very attractive characteristics. It is not only physically non-intrusive to the flow, but also causes minimal disruption of the surface temperature. Because it is so thin, the response time is less than 20 microsec. Consequently, the frequency response is flat from 0 to over 50 kHz. Moreover, the signal of the Heat Flux Microsensor is directly proportional to the heat flux. Therefore, it can easily be used in both steady and transient flows, and it measures both the steady and unsteady components of the surface heat flux. A version of the Heat Flux Microsensor has been developed to meet the harsh demands of combustion environments. These gages use platinum and platinum-10 percent rhodium as the thermoelectric materials. The thermal resistance layer is silicon monoxide and a protective coating of Al2O3 is deposited on top of the sensor. The

  16. Promising materials for HTGR high temperature heat exchangers

    International Nuclear Information System (INIS)

    Kuznetsov, E.V.; Tokareva, T.B.; Ryabchenkov, A.V.; Novichkova, O.V.; Starostin, Yu.D.

    1989-01-01

    The service conditions for high-temperature heat-exchangers with helium coolant of HTGRs and requirements imposed on materials for their production are discussed. The choice of nickel-base alloys with solid-solution hardening for long-term service at high temperatures is grounded. Results of study on properties and structure of types Ni-25Cr-5W-5Mo and Ni-20Cr-20W alloy in the temperature range of 900 deg. - 1,000 deg. C are given. The ageing of Ni-25Cr-5W-5Mo alloy at 900 deg. - 950 deg. C results in decreased corrosion-mechanical properties and is caused by the change of structural metal stability. Alloy with 20% tungsten retains a high stability of both structure and properties after prolonged exposure in helium at above temperatures. The alloy has also increased resistance to delayed fracture and low-cycle fatigue at high temperatures. The developed alloy of type Ni-20Cr-20W with microalloying is recommended for production of tubes for HTGR high-temperature heat-exchangers with helium coolant. (author). 3 refs, 8 figs

  17. On the urban heat island effect dependence on temperature trends

    International Nuclear Information System (INIS)

    Camilloni, I.; Barros, V.

    1997-01-01

    For US, Argentine and Australian cities, yearly mean urban to rural temperature differences (ΔT u-r ) and rural temperatures (T r ) are negatively correlated in almost every case, suggesting that urban heat island intensity depends, among other parameters on the temperature itself. This negative correlation is related to the fact that interannual variability of temperature is generally lower in urban environments than in rural areas. This seems to hold true at low frequencies leading to opposite trends in the two variables. Hence, urban stations are prone to have lower trends in absolute value than rural ones. Therefore, regional data sets including records from urban locations, in addition to urban growth bias may have a second type of urban bias associated with temperature trends. A bulk estimate of this second urban bias trend for the contiguous United States during 1901-1984 indicates that it could be of the same order as the urban growth bias and of opposite sign. If these results could be extended to global data, it could be expected that the spurious influence of urban growth on global temperature trends during warming periods will be offset by the diminishing of the urban heat island intensity. 36 refs., 7 figs., 2 tabs

  18. High-temperature process heat applications with an HTGR

    International Nuclear Information System (INIS)

    Quade, R.N.; Vrable, D.L.

    1980-04-01

    An 842-MW(t) HTGR-process heat (HTGR-PH) design and several synfuels and energy transport processes to which it could be coupled are described. As in other HTGR designs, the HTGR-PH has its entire primary coolant system contained in a prestressed concrete reactor vessel (PCRV) which provides the necessary biological shielding and pressure containment. The high-temperature nuclear thermal energy is transported to the externally located process plant by a secondary helium transport loop. With a capability to produce hot helium in the secondary loop at 800 0 C (1472 0 F) with current designs and 900 0 C (1652 0 F) with advanced designs, a large number of process heat applications are potentially available. Studies have been performed for coal liquefaction and gasification using nuclear heat

  19. Containment for low temperature district nuclear-heating reactor

    International Nuclear Information System (INIS)

    He Shuyan; Dong Duo

    1992-03-01

    Integral arrangement is adopted for Low Temperature District Nuclear-heating Reactor. Primary heat exchangers, control rod drives and spent fuel elements are put in the reactor pressure vessel together with reactor core. Primary coolant flows through reactor core and primary heat exchangers in natural circulation. Primary coolant pipes penetrating the wall of reactor pressure vessel are all of small diameters. The reactor vessel constitutes the main part of pressure boundary of primary coolant. Therefore the small sized metallic containment closed to the wall of reactor vessel can be used for the reactor. Design principles and functions of the containment are as same as the containment for PWR. But the adoption of small sized containment brings about some benefits such as short period of manufacturing, relatively low cost, and easy for sealing. Loss of primary coolant accident would not be happened during the rupture accident of primary coolant pressure boundary inside the containment owing to its intrinsic safety

  20. Effect of heat-treatment on elevated temperature fatigue-crack growth behavior of two heats of Alloy 718

    International Nuclear Information System (INIS)

    Mills, W.J.; James, L.A.

    1978-05-01

    The room temperature and elevated temperature fatigue-crack growth behavior of two heats of Alloy 718 was characterized within a linear-elastic fracture mechanics framework. Two different heat-treatments were used: the ''conventional'' (ASTM A637) treatment, and a ''modified'' heat-treatment designed to improve the toughness of Alloy 718 base metal and weldments. Heat-to-heat variations in the fatigue-crack propagation behavior were observed in the conventionally-treated material. On the other hand, no heat-to-heat variations were observed in the modified condition. Furthermore, both heats of Alloy 718 exhibited superior fatigue-crack growth resistance when given the modified heat-treatment. Electron fractographic examination of Alloy 718 fatigue fracture surfaces revealed that the operative crack growth mechanisms were dependent on heat-treatment, temperature, and ΔK level

  1. Uniformity factor of temperature difference in heat exchanger networks

    International Nuclear Information System (INIS)

    Chen, Shang; Cui, Guo-min

    2016-01-01

    Highlights: • A uniformity factor of temperature (UFTD) is proposed to heat exchanger network (HEN). • A novel stage-wise superstructure with inner utilities is presented based on UFTD. • New model and DE method is combined as an optimization method. • Optimal HEN structures with inner utilities can be obtained with new method. - Abstract: A uniformity factor of temperature difference (UFTD) is proposed and set up to guide the optimization of Heat exchanger network (HEN). At first, the factor is presented to evaluate the whole enhancement of HEN by handling the logical mean temperature difference as two-dimensional discrete temperature field in system. Then, the factor is applied to different HENs, of which the comparison indicates that a more uniform discrete temperature field leads to a lower UFTD which correlated with a better whole enhancement to improve the optimization level of HEN. A novel stage-wise superstructure model where inner utility can be generated is presented for further analysis of correlation between UFTD and the efficiency of HEN, and more optimal HEN structures can be obtained as inner utility added. Inner utility appears to violate the thermodynamic law, but it makes the discrete temperature field more uniform and improves the heat transfer efficiency of the whole HEN, which brings much more profit than the side effect of inner utility. In sum, the UFTD can not only evaluate the optimization level of the HEN, but also be an optimization object to design new HEN with higher efficiency of energy utilization and lower total annual cost.

  2. Loop Heat Pipe Temperature Oscillation Induced by Gravity Assist and Reservoir Heating

    Science.gov (United States)

    Ku, Jentung; Garrison, Matt; Patel, Deepak; Robinson, Frank; Ottenstein, Laura

    2015-01-01

    The Laser Thermal Control System (LCTS) for the Advanced Topographic Laser Altimeter System (ATLAS) to be installed on NASA's Ice, Cloud, and Land Elevation Satellite (ICESat-2) consists of a constant conductance heat pipe and a loop heat pipe (LHP) with an associated radiator. During the recent thermal vacuum testing of the LTCS where the LHP condenser/radiator was placed in a vertical position above the evaporator and reservoir, it was found that the LHP reservoir control heater power requirement was much higher than the analytical model had predicted. Even with the control heater turned on continuously at its full power, the reservoir could not be maintained at its desired set point temperature. An investigation of the LHP behaviors found that the root cause of the problem was fluid flow and reservoir temperature oscillations, which led to persistent alternate forward and reversed flow along the liquid line and an imbalance between the vapor mass flow rate in the vapor line and liquid mass flow rate in the liquid line. The flow and temperature oscillations were caused by an interaction between gravity and reservoir heating, and were exacerbated by the large thermal mass of the instrument simulator which modulated the net heat load to the evaporator, and the vertical radiator/condenser which induced a variable gravitational pressure head. Furthermore, causes and effects of the contributing factors to flow and temperature oscillations intermingled.

  3. Temperature rise and Heat build up inside a parked Car

    Science.gov (United States)

    Coady, Rose; Maheswaranathan, Ponn

    2001-11-01

    We have studied the heat build up inside a parked car under the hot summer Sun. Inside and outside temperatures were monitored every ten seconds from 9 AM to about 4 PM for a 2000 Toyota Camry parked in a Winthrop University parking lot without any shades or trees. Two PASCO temperature sensors, one inside the car and the other outside the car, are used along with PASCO-750 interface to collect the data. Data were collected under the following conditions while keeping track of the outside weather: fully closed windows, slightly open windows, half way open windows, fully open windows, and with window shades inside and outside. Inside temperatures reached as high as 150 degrees Fahrenheit on a sunny day with outside high temperature of about 100 degrees Fahrenheit. These results will be presented along with results from car cover and window tint manufacturers and suggestions to keep your car cool next time you park it under the Sun.

  4. Shape Effect on the Temperature Field during Microwave Heating Process

    Directory of Open Access Journals (Sweden)

    Zhijun Zhang

    2018-01-01

    Full Text Available Aiming at improving the food quality during microwave process, this article mainly focused on the numerical simulation of shape effect, which was evaluated by microwave power absorption capability and temperature distribution uniformity in a single sample heated in a domestic microwave oven. This article only took the electromagnetic field and heat conduction in solid into consideration. The Maxwell equations were used to calculate the distribution of microwave electromagnetic field distribution in the microwave cavity and samples; then the electromagnetic energy was coupled as the heat source in the heat conduction process in samples. Quantitatively, the power absorption capability and temperature distribution uniformity were, respectively, described by power absorption efficiency (PAE and the statistical variation of coefficient (COV. In addition, we defined the comprehensive evaluation coefficient (CEC to describe the usability of a specific sample. In accordance with volume or the wave numbers and penetration numbers in the radial and axial directions of samples, they can be classified into different groups. And according to the PAE, COV, and CEC value and the specific need of microwave process, an optimal sample shape and orientation could be decided.

  5. Heating temperature effect on ferritic grain size of rotor steel

    International Nuclear Information System (INIS)

    Cheremnykh, V.G.; Derevyankin, E.V.; Sakulin, A.A.

    1983-01-01

    The heating temperature effect on ferritic grain size of two steels 13Kh1M1FA and 25Kh1M1FA is evaluated. It is shown that exposure time increase at heating temperatures below 1000 deg C up to 10h changes but slightly the size of the Cr-Mo-V ferritic grain of rotor steel cooled with 25 deg C/h rate. Heating up to 1000 deg C and above leads to substantial ferritic grain growth. The kinetics of ferritic grain growth is determined by the behaviour of phases controlling the austenitic grain growth, such as carbonitrides VCsub(0.14)Nsub(0.78) in 13Kh1M1FA steel and VCsub(0.18)Nsub(0.72) in 25Kh1M1FA steel. Reduction of carbon and alloying elements content in steel composition observed at the liquation over rotor length leads to a certain decrease of ferritic grain resistance to super heating

  6. Energy and Heat Fluctuations in a Temperature Quench

    Energy Technology Data Exchange (ETDEWEB)

    Zannetti, M.; Corberi, F. [Dipartimento di Fisica “E. Caianiello”, and CNISM, Unità di Salerno, Università di Salerno, via Giovanni Paolo II 132, 84084 Fisciano (Italy); Gonnella, G. [Dipartimento di Fisica, Università di Bari and INFN, Sezione di Bari, via Amendola 173, 70126 Bari (Italy); Piscitelli, A., E-mail: mrc.zannetti@gmail.com, E-mail: corberi@sa.infn.it, E-mail: gonnella@ba.infn.it, E-mail: antps@hotmial.it [Division of Physical Sciences, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371 (Singapore)

    2014-10-15

    Fluctuations of energy and heat are investigated during the relaxation following the instantaneous temperature quench of an extended system. Results are obtained analytically for the Gaussian model and for the large N model quenched below the critical temperature T{sub c}. The main finding is that fluctuations exceeding a critical threshold do condense. Though driven by a mechanism similar to that of Bose—Einstein condensation, this phenomenon is an out-of-equilibrium feature produced by the breaking of energy equipartition occurring in the transient regime. The dynamical nature of the transition is illustrated by phase diagrams extending in the time direction. (general)

  7. Feedforward temperature control using a heat flux microsensor

    OpenAIRE

    Lartz, Douglas John

    1993-01-01

    The concept of using heat flux measurements to provide the input for a feedforward temperature control loop is investigated. The feedforward loop is added to proportional and integral feedback control to increase the speed of the response to a disturbance. Comparison is made between the feedback and the feedback plus feedforward control laws. The control law with the feedforward control loop is also compared to the conventional approach of adding derivative control to speed up ...

  8. Status of high-temperature heat-pipe technology

    International Nuclear Information System (INIS)

    Ranken, W.A.

    1982-01-01

    This paper discusses the application of heat pipes to nuclear reactor space power systems. Characteristics of the device that favor such an application are described and recent results of current technology development programs are presented. Research areas that will need to be addressed in demonstrating that adequate lifetimes can be achieved with evaporation/condensation cycles operating at high temperatures in a reactor environment are also discussed

  9. The effective neutron temperature in heated graphite sleeves

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, J A; Small, V G [General Reactor Physics Division, Atomic Energy Establishment, Winfrith, Dorchester, Dorset (United Kingdom)

    1963-08-15

    In a series of oscillator measurements carried out in the reactor NERO the variation of the relative reaction rates of cadmium and boron absorbers has been used to determine the effective neutron temperature inside heated graphite sleeves. This work extends the scope of similar oscillator measurements previously carried out in DIMPLE, in that the bulk moderator is now graphite as opposed to D{sub 2}O in the former case. (author)

  10. Methods of total spectral radiant flux realization at VNIIOFI

    Science.gov (United States)

    Ivashin, Evgeniy; Lalek, Jan; Rybczyński, Andrzej; Ogarev, Sergey; Khlevnoy, Boris; Dobroserdov, Dmitry; Sapritsky, Victor

    2018-02-01

    VNIIOFI carries out works on realization of independent methods for realization of the total spectral radiant flux (TSRF) of incoherent optical radiation sources - reference high-temperature blackbodies (BB), halogen lamps, and LED with quasi-Lambert spatial distribution of radiance. The paper describes three schemes for measuring facilities using photometers, spectroradiometers and computer-controlled high class goniometer. The paper describes different approaches for TSRF realization at the VNIIOFI National radiometric standard on the basis of high-temperature BB and LED sources, and gonio-spectroradiometer. Further, they are planned to be compared, and the use of fixed-point cells (in particular, based on the high-temperature δ(MoC)-C metal-carbon eutectic with a phase transition temperature of 2583 °C corresponding to the metrological optical “source-A”) as an option instead of the BB is considered in order to enhance calibration accuracy.

  11. Conversion of medium and low temperature heat to power

    Science.gov (United States)

    Fischer, Johann; Wendland, Martin; Lai, Ngoc Anh

    2013-04-01

    Presently most electricity is produced in power plants which use high temperature heat supplied by coal, oil, gas or nuclear fission and Clausius-Rankine cycles (CRC) with water as working fluid (WF). On the other hand, geo-, solar-, ocean-, and biogenic-heat have medium and low temperatures. At these temperatures, however, the use of other WF and/or other cycles can yield higher efficiencies than those of the water-CRC. For an assessment of the efficiency we model systems which include the heat transfer to and from the WF and the cycle. Optimization criterion is the exergy efficiency defined as the ratio of the net power output to the incoming exergy flow of the heat carrier. First, for a better understanding we discuss some thermodynamic properties of the WFs: 1) the critical point parameters, 2) the shape of the vapour- liquid coexistence curve in the temperature vs entropy (T,s)-diagram which may be either bell-shaped or overhanging [1,2], and 3) the shape of sub- and supercritical isobars for pure fluids and fluid mixtures. Second, we show that the problems of a CRC with water at lower temperatures are 1) the shape of the T,s-diagram and 2) the exergy loss during heat transfer to the WF. The first problem can be overcome by using an organic working fluid in the CRC which then is called organic Rankine cycle (ORC). The second problem is reduced by supercritical organic Rankine cycles (sORC) [1,2], trilateral cycles (TLC) and the more general power-flash cycles (PFC) [2], and organic flash cycles (OFC) [3]. Next, selected results for systems with the above mentioned cycles will be presented. The heat carrier inlet temperatures THC range from 120°C to 350°C.The pure working fluids are water, refrigerants, alkanes, aromates and siloxanes and have to be selected to match with THC. It is found that TLC with water have the highest efficiencies but show very large volume flows at lower temperatures. Moreover, expansion machines for TLC and PFC are still under

  12. Measuring the temperature history of isochorically heated warm dense metals

    Science.gov (United States)

    McGuffey, Chris; Kim, J.; Park, J.; Moody, J.; Emig, J.; Heeter, B.; Dozieres, M.; Beg, Fn; McLean, Hs

    2017-10-01

    A pump-probe platform has been designed for soft X-ray absorption spectroscopy near edge structure measurements in isochorically heated Al or Cu samples with temperature of 10s to 100s of eV. The method is compatible with dual picosecond-class laser systems and may be used to measure the temperature of the sample heated directly by the pump laser or by a laser-driven proton beam Knowledge of the temperature history of warm dense samples will aid equation of state measurements. First, various low- to mid-Z targets were evaluated for their suitability as continuum X-ray backlighters over the range 200-1800 eV using a 10 J picosecond-class laser with relativistic peak intensity Alloys were found to be more suitable than single-element backlighters. Second, the heated sample package was designed with consideration of target thickness and tamp layers using atomic physics codes. The results of the first demonstration attempts will be presented. This work was supported by the U.S. DOE under Contract No. DE-SC0014600.

  13. Sea water desalination utilizing waste heat by low temperature evaporation

    International Nuclear Information System (INIS)

    Raha, A.; Srivastava, A.; Rao, I.S.; Majumdar, M.; Srivastava, V.K.; Tewari, P.K.

    2007-01-01

    Economics of a process is controlled by management of energy and resources. Fresh water has become most valued resource in industries. Desalination is a process by which fresh water resource is generated from sea water or brackish water, but it is an energy intensive process. The energy cost contributes around 25-40% to the total cost of the desalted water. Utilization of waste heat from industrial streams is one of the ecofriendly ways to produce low cost desalted water. Keeping this in mind Low Temperature Evaporation (LTE) desalination technology utilizing low quality waste heat in the form of hot water (as low as 50 deg C) or low pressure steam (0.13 bar) has been developed for offshore and land based applications to produce high purity water (conductivity < 2μS/cm) from sea water. The probability of the scale formation is practically eliminated by operating it at low temperature and controlling the brine concentration. It also does not require elaborate chemical pretreatment of sea water except chlorination, so it has no environmental impact. LTE technology has found major applications in nuclear reactors where large quantity of low quality waste heat is available to produce high quality desalted water for make up water requirement replacing conventional ion exchange process. Successful continuous operation of 30 Te/day LTE desalination plant utilizing waste heat from nuclear research reactor has demonstrated the safety, reliability, extreme plant availability and economics of nuclear desalination by LTE technology. It is also proposed to utilize waste heat from Main Heat Transport (MHT) purification circuit of Advanced Heavy Water Reactor (AHWR) to produce about 250 Te/ day high quality desalinated water by Low Temperature Evaporation (LTE) process for the reactor make up and plant utilization. Recently we have commissioned a 50 Te/day 2-effect low temperature desalination plant with cooling tower where the specific energy and cooling water requirement are

  14. Optimization of temperature field of tobacco heat shrink machine

    Science.gov (United States)

    Yang, Xudong; Yang, Hai; Sun, Dong; Xu, Mingyang

    2018-06-01

    A company currently shrinking machine in the course of the film shrinkage is not compact, uneven temperature, resulting in poor quality of the shrinkage of the surface film. To solve this problem, the simulation and optimization of the temperature field are performed by using the k-epsilon turbulence model and the MRF model in fluent. The simulation results show that after the mesh screen structure is installed at the suction inlet of the centrifugal fan, the suction resistance of the fan can be increased and the eddy current intensity caused by the high-speed rotation of the fan can be improved, so that the internal temperature continuity of the heat shrinkable machine is Stronger.

  15. Thermal Conditions in a Simulated Office Environment with Convective and Radiant Cooling Systems

    DEFF Research Database (Denmark)

    Mustakallio, Panu; Bolashikov, Zhecho Dimitrov; Kostov, Kalin

    2013-01-01

    velocity and turbulent intensity were measured and draft rate levels calculated in the room. Manikin-based equivalent temperature (MBET) was determined by two thermal manikins to identify the impact of the local thermal conditions generated by the studied systems on occupants’ thermal comfort. The results......The thermal conditions in a two person office room were measured with four air conditioning systems: chilled beam (CB), chilled beam with radiant panel (CBR), chilled ceiling with ceiling installed mixing ventilation (CCMV) and four desk partition mounted local radiant cooling panels with mixing...

  16. Modelling of Temperature Profiles and Transport Scaling in Auxiliary Heated Tokamaks

    DEFF Research Database (Denmark)

    Callen, J.D.; Christiansen, J.P.; Cordey, J.G.

    1987-01-01

    time , the heating effectiveness η, and the energy offset W(0). Considering both the temperature profile responses and the global transport scaling, the constant heat pinch or excess temperature gradient model is found to best characterize the present JET data. Finally, new methods are proposed......The temperature profiles produced by various heating profiles are calculated from local heat transport models. The models take the heat flux to be the sum of heat diffusion and a non-diffusive heat flow, consistent with local measurements of heat transport. Two models are developed analytically...... in detail: (i) a heat pinch or excess temperature gradient model with constant coefficients; and (ii) a non-linear heat diffusion coefficient (χ) model. Both models predict weak (lesssim20%) temperature profile responses to physically relevant changes in the heat deposition profile – primarily because...

  17. Ground surface temperature and continental heat gain: uncertainties from underground

    International Nuclear Information System (INIS)

    Beltrami, Hugo; Matharoo, Gurpreet S; Smerdon, Jason E

    2015-01-01

    Temperature changes at the Earth's surface propagate and are recorded underground as perturbations to the equilibrium thermal regime associated with the heat flow from the Earth's interior. Borehole climatology is concerned with the analysis and interpretation of these downward propagating subsurface temperature anomalies in terms of surface climate. Proper determination of the steady-state geothermal regime is therefore crucial because it is the reference against which climate-induced subsurface temperature anomalies are estimated. Here, we examine the effects of data noise on the determination of the steady-state geothermal regime of the subsurface and the subsequent impact on estimates of ground surface temperature (GST) history and heat gain. We carry out a series of Monte Carlo experiments using 1000 Gaussian noise realizations and depth sections of 100 and 200 m as for steady-state estimates depth intervals, as well as a range of data sampling intervals from 10 m to 0.02 m. Results indicate that typical uncertainties for 50 year averages are on the order of ±0.02 K for the most recent 100 year period. These uncertainties grow with decreasing sampling intervals, reaching about ±0.1 K for a 10 m sampling interval under identical conditions and target period. Uncertainties increase for progressively older periods, reaching ±0.3 K at 500 years before present for a 10 m sampling interval. The uncertainties in reconstructed GST histories for the Northern Hemisphere for the most recent 50 year period can reach a maximum of ±0.5 K in some areas. We suggest that continuous logging should be the preferred approach when measuring geothermal data for climate reconstructions, and that for those using the International Heat Flow Commission database for borehole climatology, the steady-state thermal conditions should be estimated from boreholes as deep as possible and using a large fitting depth range (∼100 m). (letter)

  18. Low temperature heat capacity of scandium and alloys of scandium

    Energy Technology Data Exchange (ETDEWEB)

    Tsang, T. W.E.

    1977-12-01

    The heat capacity of three electrotransport purified scandium samples has been measured from 1 to 20/sup 0/K. The resultant electronic specific heat constant and Debye temperature are 10.337 +- 0.015 mJ/gm-atom K/sup 2/ and 346.7 +- 0.8/sup 0/K respectively, and these values are believed to be truly representative of intrinsic scandium. Alloying studies have also been carried out to investigate the band structure of scandium based on the rigid band model, with zirconium to raise the electron concentration and magnesium to lower it. The results are then compared to the theoretical band structure calculations. Low temperature heat capacity measurements have also been made on some dilute Sc-Fe alloys. An anomaly is observed in the C/T vs. T/sup 2/ plot, but the C vs. T curve shows no evidence of magnetic ordering down to 1/sup 0/K, and electrical resistance measurement from 4 to 0.3/sup 0/K also indicates that no magnetic ordering took place.

  19. Soil temperature distribution around a U-tube heat exchanger in a multi-function ground source heat pump system

    International Nuclear Information System (INIS)

    Li Shuhong; Yang Weihua; Zhang Xiaosong

    2009-01-01

    The imbalance of heat extracted from the earth by the underground heat exchangers in winter and ejected into it in summer is expected to affect the long term performance of conventional ground source heat pump (GSHP) in territories with a cold winter and a warm summer such as the middle and downstream areas of the Yangtze River in China. This paper presents a new multi-function ground source heat pump (MFGSHP) system which supplies hot water as well as space cooling/heating to mitigate the soil imbalance of the extracted and ejected heat by a ground source heat pump system. The heat transfer characteristic is studied and the soil temperature around the underground heat exchangers are simulated under a typical climatic condition of the Yangtze River. A three-dimensional model was constructed with the commercial computational fluid dynamics software FLUENT based on the inner heat source theory. Temperature distribution and variation trend of a tube cluster of the underground heat exchanger are simulated for the long term performance. The results show that the soil temperature around the underground tube keeps increasing due to the surplus heat ejected into the earth in summer, which deteriorates the system performance and may lead to the eventual system deterioration. The simulation shows that MFGSHP can effectively alleviate the temperature rise by balancing the heat ejected to/extracted from underground by the conventional ground source heat pump system. The new system also improves the energy efficiency.

  20. Solar radiation and cooling load calculation for radiant systems: Definition and evaluation of the Direct Solar Load

    DEFF Research Database (Denmark)

    Causone, Francesco; Corgnati, Stefano P.; Filippi, Marco

    2010-01-01

    The study of the influence of solar radiation on the built environment is a basic issue in building physics and currently it is extremely important because glazed envelopes are widely used in contemporary architecture. In the present study, the removal of solar heat gains by radiant cooling systems...... is investigated. Particular attention is given to the portion of solar radiation converted to cooling load, without taking part in thermal absorption phenomena due to the thermal mass of the room. This specific component of the cooling load is defined as the Direct Solar Load. A simplified procedure to correctly...... calculate the magnitude of the Direct Solar Load in cooling load calculations is proposed and it is implemented with the Heat Balance method and the Radiant Time Series method. The F ratio of the solar heat gains directly converted to cooling load, in the case of a low thermal mass radiant ceiling...

  1. Mask humidity during CPAP: influence of ambient temperature, heated humidification and heated tubing

    Directory of Open Access Journals (Sweden)

    Nilius G

    2018-05-01

    Full Text Available Georg Nilius,1,2 Ulrike Domanski,1 Maik Schroeder,1 Holger Woehrle,3,4 Andrea Graml,4 Karl-Josef Franke,1,2 1Helios Klinik Hagen-Ambrock, Department of Pneumology, Hagen, Germany; 2Department of Internal Medicine, Witten-Herdecke University, Witten, Germany; 3Sleep and Ventilation Center Blaubeuren, Respiratory Center Ulm, Ulm, Germany; 4ResMed Science Center, ResMed Germany, Martinsried, Germany Purpose: Mucosal drying during continuous positive airway pressure (CPAP therapy is problematic for many patients. This study assessed the influence of ambient relative humidity (rH and air temperature (T in winter and summer on mask humidity during CPAP, with and without mask leak, and with or without heated humidification ± heated tubing. Methods: CPAP (8 and 12 cmH2O without humidification (no humidity [nH], with heated humidification controlled by ambient temperature and humidity (heated humidity [HH] and HH plus heated tubing climate line (CL, with and without leakage, were compared in 18 subjects with OSA during summer and winter. Results: The absolute humidity (aH and the T inside the mask during CPAP were significantly lower in winter versus summer under all applied conditions. Overall, absolute humidity differences between summer and winter were statistically significant in both HH and CL vs. nH (p < 0.05 in the presence and absence of mouth leak. There were no significant differences in aH between HH and CL. However, in-mask temperature during CL was higher (p < 0.05 and rH lower than during HH. In winter, CPAP with CL was more likely to keep rH constant at 80% than CPAP without humidification or with standard HH. Conclusion: Clinically-relevant reductions in aH were documented during CPAP given under winter conditions. The addition of heated humidification, using a heated tube to avoid condensation is recommended to increase aH, which could be useful in CPAP users complaining of nose and throat symptoms. Keywords: continuous positive

  2. Radiant Barriers Save Energy in Buildings

    Science.gov (United States)

    2014-01-01

    Langley Research Center needed to coat the Echo 1 satellite with a fine mist of vaporized metal, and collaborated with industry to create "radiant barrier technology." In 2010, Ryan Garrett learned about a new version of the technology resistant to oxidation and founded RadiaSource in Ogden, Utah, to provide the NASA-derived technology for applications in homes, warehouses, gymnasiums, and agricultural settings.

  3. Effects of cryogen spray cooling and high radiant exposures on selective vascular injury during laser irradiation of human skin.

    Science.gov (United States)

    Tunnell, James W; Chang, David W; Johnston, Carol; Torres, Jorge H; Patrick, Charles W; Miller, Michael J; Thomsen, Sharon L; Anvari, Bahman

    2003-06-01

    Increasing radiant exposure offers a means to increase treatment efficacy during laser-mediated treatment of vascular lesions, such as port-wine stains; however, excessive radiant exposure decreases selective vascular injury due to increased heat generation within the epidermis and collateral damage to perivascular collagen. To determine if cryogen spray cooling could be used to maintain selective vascular injury (ie, prevent epidermal and perivascular collagen damage) when using high radiant exposures (16-30 J/cm2). Observational study. Academic hospital and research laboratory. Twenty women with normal abdominal skin (skin phototypes I-VI). Skin was irradiated with a pulsed dye laser (wavelength = 585 nm; pulse duration = 1.5 milliseconds; 5-mm-diameter spot) using various radiant exposures (8-30 J/cm2) without and with cryogen spray cooling (50- to 300-millisecond cryogen spurts). Hematoxylin-eosin-stained histologic sections from each irradiated site were examined for the degree of epidermal damage, maximum depth of red blood cell coagulation, and percentage of vessels containing perivascular collagen coagulation. Long cryogen spurt durations (>200 milliseconds) protected the epidermis in light-skinned individuals (skin phototypes I-IV) at the highest radiant exposure (30 J/cm2); however, epidermal protection could not be achieved in dark-skinned individuals (skin phototypes V-VI) even at the lowest radiant exposure (8 J/cm2). The red blood cell coagulation depth increased with increasing radiant exposure (to >2.5 mm for skin phototypes I-IV and to approximately 1.2 mm for skin phototypes V-VI). In addition, long cryogen spurt durations (>200 milliseconds) prevented perivascular collagen coagulation in all skin types. Cryogen spurt durations much longer than those currently used in therapy (>200 milliseconds) may be clinically useful for protecting the epidermis and perivascular tissues when using high radiant exposures during cutaneous laser therapies

  4. High-temperature ultrasonic measurements applied to directly heated samples

    International Nuclear Information System (INIS)

    Moore, R.I.; Taylor, R.E.

    1984-01-01

    High-temperature ultrasonic measurements of Young's modulus were made of graphite samples heated directly. The samples were cylindrical rods of the same geometry as that used in the multiproperty apparatus for simultaneous/consecutive measurements of a number of thermophysical properties to high temperatures. The samples were resonated in simple longitudinal vibration modes. Measurements were performed up to 2000 K. Incorporation of ultrasonic measurements of Young's modulus in the capabilities of the multiproperty apparatus is valuable because (i) ultrasonic measurements can be related to normal destructive measurements of this property; (ii) they can be used for screening materials or acceptance testing of specimens; (iii) they can be used to increase the understanding of thermophysical properties and property correlations. (author)

  5. Energy efficient heating and ventilation of large halls

    CERN Document Server

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

    2011-01-01

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

  6. Combined cycle power plant with integrated low temperature heat (LOTHECO)

    International Nuclear Information System (INIS)

    Kakaras, E.; Doukelis, A.; Leithner, R.; Aronis, N.

    2004-01-01

    The major driver to enhance the efficiency of the simple gas turbine cycle has been the increase in process conditions through advancements in materials and cooling methods. Thermodynamic cycle developments or cycle integration are among the possible ways to further enhance performance. The current paper presents the possibilities and advantages from the LOTHECO natural gas-fired combined cycle concept. In the LOTHECO cycle, low-temperature waste heat or solar heat is used for the evaporation of injected water droplets in the compressed air entering the gas turbine's combustion chamber. Following a description of this innovative cycle, its advantages are demonstrated by comparison between different gas turbine power generation systems for small and large-scale applications, including thermodynamic and economic analysis. A commercial gas turbine (ALSTOM GT10C) has been selected and computed with the heat mass balance program ENBIPRO. The results from the energy analysis are presented and the features of each concept are discussed. In addition, the exergy analysis provides information on the irreversibilities of each process and suggested improvements. Finally, the economic analysis reveals that the combined cycle plant with a heavy-duty gas turbine is the most efficient and economic way to produce electricity at base load. However, on a smaller scale, innovative designs, such as the LOTHECO concept, are required to reach the same level of performance at feasible costs

  7. Low temperature heat capacity of lutetium and lutetium hydrogen alloys

    International Nuclear Information System (INIS)

    Thome, D.K.

    1977-10-01

    The heat capacity of high purity electrotransport refined lutetium was measured between 1 and 20 0 K. Results for theta/sub D/ were in excellent agreement with theta values determined from elastic constant measurements. The heat capacity of a series of lutetium-hydrogen solid solution alloys was determined and results showed an increase in γ from 8.2 to about 11.3 mJ/g-atom-K 2 for hydrogen content increasing from zero to about one atomic percent. Above one percent hydrogen γ decreased with increasing hydrogen contents. The C/T data showed an increase with temperature decreasing below about 2.5 0 K for samples with 0.1 to 1.5 atomic percent hydrogen. This accounts for a large amount of scatter in theta/sub D/ versus hydrogen content in this range. The heat capacity of a bulk sample of lutetium dihydride was measured between 1 and 20 0 K and showed a large increase in theta/sub D/ and a large decrease in γ compared to pure lutetium

  8. A RADIANT AIR-CONDITIONING SYSTEM USING SOLAR-DRIVEN

    Directory of Open Access Journals (Sweden)

    S. A. ABDALLA

    2006-12-01

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

  9. Towards a Future of District Heating Systems with Low-Temperature Operation together with Non-Fossil Fuel Heat Sources

    DEFF Research Database (Denmark)

    Tol, Hakan; Dinçer, Ibrahim; Svendsen, Svend

    2012-01-01

    This study focused on investigation of non-fossil fuel heat sources to be supplied to low-energy district heating systems operating in low temperature such as 55 C and 25 C in terms of, respectively, supply and return. Vast variety of heat sources classed in categories such as fossil fuel...

  10. Students’ Conception on Heat and Temperature toward Science Process Skill

    Science.gov (United States)

    Ratnasari, D.; Sukarmin, S.; Suparmi, S.; Aminah, N. S.

    2017-09-01

    This research is aimed to analyze the effect of students’ conception toward science process skill. This is a descriptive research with subjects of the research were 10th-grade students in Surakarta from high, medium and low categorized school. The sample selection uses purposive sampling technique based on physics score in national examination four latest years. Data in this research collecting from essay test, two-tier multiple choice test, and interview. Two-tier multiple choice test consists of 30 question that contains an indicator of science process skill. Based on the result of the research and analysis, it shows that students’ conception of heat and temperature affect science process skill of students. The students’ conception that still contains the wrong concept can emerge misconception. For the future research, it is suggested to improve students’ conceptual understanding and students’ science process skill with appropriate learning method and assessment instrument because heat and temperature is one of physics material that closely related with students’ daily life.

  11. Secondary heat exchanger design and comparison for advanced high temperature reactor

    International Nuclear Information System (INIS)

    Sabharwall, P.; Kim, E. S.; Siahpush, A.; McKellar, M.; Patterson, M.

    2012-01-01

    Next generation nuclear reactors such as the advanced high temperature reactor (AHTR) are designed to increase energy efficiency in the production of electricity and provide high temperature heat for industrial processes. The efficient transfer of energy for industrial applications depends on the ability to incorporate effective heat exchangers between the nuclear heat transport system and the industrial process heat transport system. This study considers two different types of heat exchangers - helical coiled heat exchanger and printed circuit heat exchanger - as possible options for the AHTR secondary heat exchangers with distributed load analysis and comparison. Comparison is provided for all different cases along with challenges and recommendations. (authors)

  12. Elevated-Temperature Tests Under Static and Aerodynamic Conditions on Honeycomb-Core Sandwich Panels

    Science.gov (United States)

    Groen, Joseph M.; Johnson, Aldie E., Jr.

    1959-01-01

    Stainless-steel honeycomb-core sandwich panels which differed primarily in skin thicknesses were tested at elevated temperatures under static and aerodynamic conditions. The results of these tests were evaluated to determine the insulating effectiveness and structural integrity of the panels. The static radiant-heating tests were performed in front of a quartz-tube radiant heater at panel skin temperatures up to 1,5000 F. The aerodynamic tests were made in a Mach 1.4 heated blowdown wind tunnel. The tunnel temperature was augmented by additional heat supplied by a radiant heater which raised the panel surface temperature above 8000 F during air flow. Static radiant-heating tests of 2 minutes duration showed that all the panels protected the load-carrying structure about equally well. Thin-skin panels showed an advantage for this short-time test over thick-skin panels from a standpoint of weight against insulation. Permanent inelastic strains in the form of local buckles over each cell of the honeycomb core caused an increase in surface roughness. During the aero- dynamic tests all of the panels survived with little or no damage, and panel flutter did not occur.

  13. Development of a solar thermal storage system suitable for the farmhouse heating in northeast China

    Energy Technology Data Exchange (ETDEWEB)

    Jang, M.K. [Shenyang Agricultural Univ., Shenyang (China)

    2010-07-01

    This study reported on the performance of a passive solar radiant floor heating system designed for standard energy-saving farmhouses in northeast China. Weather data in the region was analyzed in terms of solar radiation, temperature, humidity and light levels. The heating characteristics of the building materials such as windows, doors, walls and roofs were also analyzed along with the indoor thermal environment of the farmhouse. The heating load was then calculated along with the size of the thermal storage element and the area of the collector element. The passive solar radiant floor heating system was designed for heating during the winter and cooling in summer. According to the results, the heating characteristics of the system have the potential to improve farming villages environment and the use of renewable energy.

  14. Flue gas heat recovery operating below the dew point and its utilisation for low temperature heating installations

    Energy Technology Data Exchange (ETDEWEB)

    Wilsdorf, J.

    1986-11-01

    This paper deals at first with the characteristics of two principal systems for the flue gas heat recovery by reducing the temperature below the dew point. With test results on experimental plants are shown the typical differences between surface and direct contact heat exchange. A second part informs about experiences from the application for low temperature heating installations, especially about thermodynamics condensate quality and technical design. The possible increasing of the efficiency ranges between 10 to 20 per cent.

  15. Experimental Study of the Performance of Air Source Heat Pump Systems Assisted by Low-Temperature Solar-Heated Water

    Directory of Open Access Journals (Sweden)

    Jinshun Wu

    2013-01-01

    Full Text Available Due to the low temperatures, the heating efficiency of air source heat pump systems during the winter is very low. To address this problem, a low-temperature solar hot water system was added to a basic air source heat pump system. Several parameters were tested and analyzed. The heat collection efficiency of the solar collector was analyzed under low-temperature conditions. The factors that affect the performance of the heat pumps, such as the fluid temperature, pressure, and energy savings, were analyzed for cases where the solar energy auxiliary heat pump and the air source heat pump are used independently. The optimal heating temperature and the changes in the fluid temperature were determined. The influence of the compression ratio and the coefficient of performance (COP were investigated theoretically. The results revealed the parameters that are important to the performance of the system. Several measures for improving the COP of the heat pump units are provided for other applications and future research.

  16. Surface radiant flux densities inferred from LAC and GAC AVHRR data

    Science.gov (United States)

    Berger, F.; Klaes, D.

    To infer surface radiant flux densities from current (NOAA-AVHRR, ERS-1/2 ATSR) and future meteorological (Envisat AATSR, MSG, METOP) satellite data, the complex, modular analysis scheme SESAT (Strahlungs- und Energieflüsse aus Satellitendaten) could be developed (Berger, 2001). This scheme allows the determination of cloud types, optical and microphysical cloud properties as well as surface and TOA radiant flux densities. After testing of SESAT in Central Europe and the Baltic Sea catchment (more than 400scenes U including a detailed validation with various surface measurements) it could be applied to a large number of NOAA-16 AVHRR overpasses covering the globe.For the analysis, two different spatial resolutions U local area coverage (LAC) andwere considered. Therefore, all inferred results, like global area coverage (GAC) U cloud cover, cloud properties and radiant properties, could be intercompared. Specific emphasis could be made to the surface radiant flux densities (all radiative balance compoments), where results for different regions, like Southern America, Southern Africa, Northern America, Europe, and Indonesia, will be presented. Applying SESAT, energy flux densities, like latent and sensible heat flux densities could also be determined additionally. A statistical analysis of all results including a detailed discussion for the two spatial resolutions will close this study.

  17. Case study of low-temperature heating in an existing single-family house-A test of methods for simulation of heating system temperatures

    DEFF Research Database (Denmark)

    Østergaard, Dorte Skaarup; Svendsen, Svend

    2016-01-01

    and the calculated indoor temperatures and radiator return temperatures were compared to temperatures measured in the case house. The results showed that the detail of the simulation model has a large influence on the results obtained. The estimated return temperatures from the radiators varied by up to 16 degrees C...... depending on the assumptions made in the simulation model. The results indicated that a detailed building simulation model can provide a good estimate of the actual heating system operation, provided that actual radiators and realistic indoor temperatures are taken into account in the model. (C) 2016......Low-temperature heating provides an efficient way of heating our buildings. To obtain a high efficiency it is important that the heating systems in the buildings are operated with both low supply and return temperatures. This study set out to investigate how typical assumptions in the modelling...

  18. Utilisation of bleed steam heat to increase the upper heat source temperature in low-temperature ORC

    Science.gov (United States)

    Mikielewicz, Dariusz; Mikielewicz, Jarosław

    2011-12-01

    In the paper presented is a novel concept to utilize the heat from the turbine bleed to improve the quality of working fluid vapour in the bottoming organic Rankine cycle (ORC). That is a completely novel solution in the literature, which contributes to the increase of ORC efficiency and the overall efficiency of the combined system of the power plant and ORC plant. Calculations have been accomplished for the case when available is a flow rate of low enthalpy hot water at a temperature of 90 °C, which is used for preliminary heating of the working fluid. That hot water is obtained as a result of conversion of exhaust gases in the power plant to the energy of hot water. Then the working fluid is further heated by the bleed steam to reach 120 °C. Such vapour is subsequently directed to the turbine. In the paper 5 possible working fluids were examined, namely R134a, MM, MDM, toluene and ethanol. Only under conditions of 120 °C/40 °C the silicone oil MM showed the best performance, in all other cases the ethanol proved to be best performing fluid of all. Results are compared with the "stand alone" ORC module showing its superiority.

  19. Bypass valve and coolant flow controls for optimum temperatures in waste heat recovery systems

    Science.gov (United States)

    Meisner, Gregory P

    2013-10-08

    Implementing an optimized waste heat recovery system includes calculating a temperature and a rate of change in temperature of a heat exchanger of a waste heat recovery system, and predicting a temperature and a rate of change in temperature of a material flowing through a channel of the waste heat recovery system. Upon determining the rate of change in the temperature of the material is predicted to be higher than the rate of change in the temperature of the heat exchanger, the optimized waste heat recovery system calculates a valve position and timing for the channel that is configurable for achieving a rate of material flow that is determined to produce and maintain a defined threshold temperature of the heat exchanger, and actuates the valve according to the calculated valve position and calculated timing.

  20. Dynamic behavior of radiant cooling system based on capillary tubes in walls made of high performance concrete

    DEFF Research Database (Denmark)

    Mikeska, Tomás; Svendsen, Svend

    2015-01-01

    elements made of high performance concrete. The influence of the radiant cooling system on the indoor climate of the test room in terms of the air, surface and operative temperatures and velocities was investigated.The results show that the temperature of the room air can be kept in a comfortable range...... using cooling water for the radiant cooling system with a temperature only about 4K lower than the temperature of the room air. The relatively high speed reaction of the designed system is a result of the slim construction of the sandwich wall elements made of high performance concrete. (C) 2015...... the small amount of fresh air required by standards to provide a healthy indoor environment.This paper reports on experimental analyses evaluating the dynamic behavior of a test room equipped with a radiant cooling system composed of plastic capillary tubes integrated into the inner layer of sandwich wall...

  1. High temperature heat recovery systems; Les recuperateurs de chaleur a haute temperature

    Energy Technology Data Exchange (ETDEWEB)

    Martin, L.

    2003-07-15

    A state-of-the-art of high temperature heat recovery systems has been made to highlight the advantages of recovery in different energy cycles, and to compare the different geometries, materials and fabrication processes used by the different manufacturers. This leads to define the criteria that a heat recovery system must satisfy in gas turbine cogeneration applications. The pre-dimensioning of a recovery system has been performed in order to compare different geometries and to evaluate them with respect to the criteria defined in the bibliographic study. Finally, the new configuration of the 'Claire' loop has permitted to experimentally characterize a recovery system with an innovative technology based on an helical geometry. These tests have permitted to obtain the global data of the recovery system (efficiency, pressure drop, global exchange coefficient, friction coefficient, velocity and temperature profiles) and to position it with respect to the criteria defined in the bibliographic study. (J.S.)

  2. Energy efficiency of electrical infrared heating elements

    International Nuclear Information System (INIS)

    Brown, K.J.; Farrelly, R.; O’Shaughnessy, S.M.; Robinson, A.J.

    2016-01-01

    Highlights: • Characterization of the radiant energy efficiency of infrared heating elements. • Performed for a commercially available ceramic heater element for two cases. • Total radiant power and net radiant efficiency is computed. • Radiant efficiencies are strongly dependant on the input power to the element. • In-plane efficiencies depend on the distance from the heater. - Abstract: A measurement system has been designed to characterize the radiant energy efficiency of infrared heating elements. The system also allows for measurement of the radiant heat flux distribution emitted from radiant heater assemblies. To facilitate these, a 6-axis robotic arm is fitted with a Schmidt–Boelter radiant heat flux gauge. A LabVIEW interface operates the robot and positions the sensor in the desired location and subsequently acquires the desired radiant heat flux measurement. To illustrate the functionality of the measurement system and methodology, radiant heat flux distributions and efficiency calculations are performed for a commercially available ceramic heater element for two cases. In the first, a spherical surface is traced around the entire heater assembly and the total radiant power and net radiant efficiency is computed. In the second, 50 cm × 50 cm vertical planes are traced parallel to the front face of the heater assembly at distances between 10 cm and 50 cm and the in-plane power and efficiencies are computed. The results indicate that the radiant efficiencies are strongly dependant on the input power to the element and, for the in-plane efficiencies, depend on the distance from the heater.

  3. Blanchability and sensory quality of large runner peanuts blanched in a radiant wall oven using infrared radiation.

    Science.gov (United States)

    Kettler, Katrina; Adhikari, Koushik; Singh, Rakesh K

    2017-10-01

    The main factors behind the growing popularity of infrared radiation heating in food processing include its energy efficiency, food quality retention and process speed, as well as the simplicity of equipment. Infrared radiation was employed as an alternative heat treatment to the conventional hot air method used in peanut blanching. The present study aimed to investigate the application of infrared heating for blanching peanuts and determine their blanchability and sensory quality under various processing conditions. The total blanchabilities (expressed as a percentage of total blanched) of the infrared radiation trials (radiant wall oven) at 343 °C for 1.5 min, 316 °C for 1.5 min, 288 °C for 1.5 min and 343 °C for 1 min did not differ significantly compared to the hot air control trials (impingement oven) at 100 °C for 30 and 20 min. All infrared trials had significantly lower (P infrared samples demonstrated the possible initiation of oxidation for the conventionally blanched sample at 18 weeks of storage at 24 °C (room temperature), with no indication of oxidation in the infrared samples stored at the same temperature. Infrared radiation peanut blanching is a viable alternative to conventional hot air blanching because of the shorter process time and longer shelf-life, as evident from the sensory storage study. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  4. Development of a unified sizing method for gas radiation heating facilities used in large-volume buildings; Developpement d'une methode de dimensionnement unifiee d'installations de chauffage radiant gaz pour les batiments de grand volume

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez, M.; Bego, L.; Douls, Y.; Le Dean, P.; Paradowski, V. [Gaz de France, GDF, Dir. de la Recherche, 75 - Paris (France)

    2000-07-01

    Builders now have perfect command of the natural gas heating technique used for large-volume buildings. However, the sizing of heating facilities still leaves grounds for discussion, whatever the energies actually used. Accordingly, between 1997 and 1999, the ATG (technical association of the Gas industry in France), seven French manufacturers of 'large volume' heating equipment, the Chaleur Et Rayonnement (CER) association and Gaz de France decided to collaborate and develop a 'unified sizing method' for heating facilities using radiating emitters. During the first year of the study, the above partners worked on the said method (theoretical thermal study of the radiative phenomena, and then adaptation to the methods currently used by the various manufacturers). In 1998, with the support of the ADEME (the French environment and energy control agency), the partners tested the method on five industrial buildings (studying the thermal behavior and making air renewal measurements with search gases). This work made it possible to either confirm or adapt the theoretical evaluations which had been made originally. In 1999, a software program was produced to make the developed method more user friendly. The program can be used to determine the power to be installed, but also to assess the quality of the chosen configuration of the emitters (unit power, inclination, orientation) for optimum customer comfort. (authors)

  5. The effect of direct heating and cooling of heat regulation centers on body temperature

    Science.gov (United States)

    Barbour, H. G.

    1978-01-01

    Experiments were done on 28 rabbits in which puncture instruments were left in the brain for 1-2 days until the calori-puncture hyperthermia had passed and the body temperature was again normal. The instrument remaining in the brain was then used as a galvanic electrode and a second fever was produced, this time due to the electrical stimulus. It was concluded that heat is a centrally acting antipyretic and that cold is a centrally acting stimulus which produces hyperpyrexia cold-induced fever.

  6. Use of local convective and radiant cooling at warm environment

    DEFF Research Database (Denmark)

    Melikov, Arsen Krikor; Krejcirikova, Barbora; Kaczmarczyk, Jan

    2012-01-01

    The effect of four local cooling devices (convective, radiant and combined) on SBS symptoms reported by 24 subjects at 28 ˚C and 50% RH was studied. The devices studied were: (1) desk cooling fan, (2) personalized ventilation providing clean air, (3) two radiant panels and (4) two radiant panels...... and with radiant panel with attached fans, which also helped people to feel less fatigue. The SBS symptoms increased the most when the cooling fan, generating movement of polluted room air, was used....

  7. Mathematical Simulation of Temperature Profiles within Microwave Heated Wood Made for Wood-Based Nano composites

    International Nuclear Information System (INIS)

    Li, X.; He, X.; Lv, J.; Wu, Y.; Luo, Y.; Chen, H.

    2013-01-01

    High intensive microwave pretreatment is a new method to modify wood for the fabrication of wood-based nano composites. Based on the physical law on heat transfer, a mathematical model to describe the temperature profiles within wood heated by high intensive microwave was established and simulated in this research. The results showed that the temperature profiles within wood were related to microwave heating methods; The temperature inside wood firstly increased and then gradually decreased along the direction of microwave transmission when the unilateral microwave heating was applied, and the temperature difference along the thickness direction of wood was very significant; The temperature with wood firstly increased and then gradually decreased from the wood surface to interior when the bilateral microwave heating was applied. Compared with the unilateral microwave heating, bilateral microwave heating is a better microwave heating method for the more uniform wood microwave pretreatment.

  8. High-Temperature Reactor For Power Generation and District Heating

    International Nuclear Information System (INIS)

    Herzberger, Karlheinz

    1987-01-01

    The multinational BBC Brown Brave Group, which has its head-quarters in Baden/Switzerland, was founded in 1891. Its German company is Brown, Brave and CIEs AGM, Mannheim. The field of operation covers wide areas of electrical engineering: These includes mainly the manufacture of installations and equipment for the generation, conversion, distribution and utilization of electric power, with special emphasis on the capital goods sector. BBC erects turnkey power plants and manufactures electrical equipment for industrial plants and urban transport and main line trains. Also of major importance are standard electrical products such as motors, switches, cables, semiconductor devices as well as measuring and control equipment. In the field of nuclear power BBC is engaged in particular in the development and construction of high-temperature reactors for the generation of electric power and process heat. The following presentation gives a short view on the milestones of the HTR development achieved in 1987

  9. Ambient temperature testing of the G-tunnel heated block

    International Nuclear Information System (INIS)

    Zimmerman, R.M.; Board, M.P.; Hardin, E.L.; Voegele, M.D.

    1984-01-01

    The G-Tunnel heated block experiment is being conducted on the Nevada Test Site (NTS) as part of the Nevada Nuclear Waste Storage Investigations project (NNWSI). The purpose of the ambient temperature testing phase is to evaluate rock-mass mechanical properties of a block (≅8 m/sup 3/) under biaxial stress changes up to 7.5 MPa above an initialization in situ value of 3.1 MPa. Results indicate that the modulus of deformation ranges from 9.7 to 17.0 GPa and Poisson's ratio ranges from 0.21 to 0.33. In general, the higher values of the modulus and Poisson's ratio were influenced by fracture propagations parallel to the compressive stress field. Other measurements indicated that cross-hole compression (p) wave velocities and single fracture permeability values were relatively insensitive to stress changes above the in situ value

  10. Haze heats Pluto's atmosphere yet explains its cold temperature.

    Science.gov (United States)

    Zhang, Xi; Strobel, Darrell F; Imanaka, Hiroshi

    2017-11-15

    Pluto's atmosphere is cold and hazy. Recent observations have shown it to be much colder than predicted theoretically, suggesting an unknown cooling mechanism. Atmospheric gas molecules, particularly water vapour, have been proposed as a coolant; however, because Pluto's thermal structure is expected to be in radiative-conductive equilibrium, the required water vapour would need to be supersaturated by many orders of magnitude under thermodynamic equilibrium conditions. Here we report that atmospheric hazes, rather than gases, can explain Pluto's temperature profile. We find that haze particles have substantially larger solar heating and thermal cooling rates than gas molecules, dominating the atmospheric radiative balance from the ground to an altitude of 700 kilometres, above which heat conduction maintains an isothermal atmosphere. We conclude that Pluto's atmosphere is unique among Solar System planetary atmospheres, as its radiative energy equilibrium is controlled primarily by haze particles instead of gas molecules. We predict that Pluto is therefore several orders of magnitude brighter at mid-infrared wavelengths than previously thought-a brightness that could be detected by future telescopes.

  11. Free of pollution gas - an utopia or attainable goal? Gas radiant burner with a small capacity

    International Nuclear Information System (INIS)

    Hofbauer, P.; Bornscheuer, W.

    1993-01-01

    The firm Viessmann has developed a gas radiant burner for boiler capacities up to 100 kN combusting gas with extremely low pollutant emissions. This is possible since from the reaction zone a considerable part of the combustion heat is delivered through radiation by means of a glowing special steel structure. The theoretical fundamentals are explained by means of considerations regarding the equilibrium and a reaction kinetic numerical model. (orig.) [de

  12. Application of roof radiant burners in large pusher-type furnaces

    Directory of Open Access Journals (Sweden)

    A. Varga

    2009-07-01

    Full Text Available The paper deals with the application of roof flat-flame burners in the pusher-type steel slab reheating furnaces, after furnace reconstruction and replacement of conventional torch burners, with the objective to increase the efficiency of radiative heat transfer from the refractory roof to the charge. Based on observations and on measurements of the construction and process parameters under operating conditions, the advantages and disadvantages of indirectly oriented radiant heat transfer are analysed in relation to the heat transfer in classically fired furnaces.

  13. Comparison of radiant and convective cooling of office room: effect of workstation layout

    DEFF Research Database (Denmark)

    Bolashikov, Zhecho Dimitrov; Melikov, Arsen Krikor; Rezgals, Lauris

    2014-01-01

    and compared. The room was furnished with two workstations, two laptops and two thermal manikins resembling occupants. Two heat load levels, design (65 W/m2) and usual (39 W/m2), were generated by adding heat from warm panels simulating solar radiation. Two set-ups were studied: occupants sitting......The impact of heat source location (room layout) on the thermal environment generated in a double office room with four cooling ventilation systems - overhead ventilation, chilled ceiling with overhead ventilation, active chilled beam and active chilled beam with radiant panels was measured...

  14. The annual number of days that solar heated water satisfies a specified demand temperature

    Energy Technology Data Exchange (ETDEWEB)

    Yohanis, Y.G. [Thermal Systems Engineering Group, Faculty of Engineering, University of Ulster, BT37 0QB Northern Ireland (United Kingdom); Popel, O.; Frid, S.E. [Non-traditional Renewable Energy Sources, Institute for High Temperatures, Russian Academy of Sciences, 13/19 Izhorskaya str., IVTAN, Moscow 127412 (Russian Federation); Norton, B. [Dublin Institute of Technology, Aungier Street, Dublin 2 (Ireland)

    2006-08-15

    An analysis of solar water heating systems determines the number of days in each month when solar heated water wholly meets demand above a set temperature. The approach has been used to investigate the potential contribution to water heating loads of solar water heating in two UK locations. Correlations between the approach developed and the use of solar fractions are discussed. (author)

  15. High temperature superconducting current lead test facility with heat pipe intercepts

    International Nuclear Information System (INIS)

    Blumenfeld, P.E.; Prenger, C.; Roth, E.W.; Stewart, J.A.

    1998-01-01

    A high temperature superconducting (HTS) current lead test facility using heat pipe thermal intercepts is under development at the Superconducting Technology Center at Los Alamos National Laboratory. The facility can be configured for tests at currents up to 1,000 A. Mechanical cryocoolers provide refrigeration to the leads. Electrical isolation is maintained by intercepting thermal energy from the leads through cryogenic heat pipes. HST lead warm end temperature is variable from 65 K to over 90 K by controlling heat pipe evaporator temperature. Cold end temperature is variable up to 30 K. Performance predictions in terms of heat pipe evaporator temperature as a function of lead current are presented for the initial facility configuration, which supports testing up to 200 A. Measurements are to include temperature and voltage gradient in the conventional and HTS lead sections, temperature and heat transfer rate in the heat pipes. as well as optimum and off-optimum performance of the conventional lead sections

  16. Industrial heat pumps for high temperatures - a pilot project; Industrielle varmepumper for hoeje temperaturer - et forprojekt

    Energy Technology Data Exchange (ETDEWEB)

    Johansson, M. [Dansk Energi Analyse A/S, Frederiksberg (Denmark); Weel, M.; Mikkelsen, J. [Weel and Sandvig, Kgs. Lyngby (Denmark)

    2012-03-15

    This project investigates the possibility of using mass produced and inexpensive turbo compressor technology for heat pumping in the industry. The compressors are designed for the compression of air and used by the automotive industry in connection with turbo-chargers. The heat pumps are primarily intended to use water as the working medium, which in addition to having no environmental loads, is suitable for the heat pumping at temperatures above about 60 deg. C and up to about 200 deg. C, a temperature level which is considerably higher than what has previously been observed covered with heat pumping. In this project, a Danish-produced high-speed gear (Rotrex) is used, which has just been developed to said compressor technology. In cooperation with Rotrex, the modifications relevant to a standard unit were analyzed and assessed. The project identified some areas of industry where heat pumping using this technology is considered to be attractive. A pilot plant operating with steam in a total of 12 hours is demonstrated. In more than 3 hours, the pilot plant was coupled so that it delivered useful heat supply to the evaporator. The plant has during the tests worked satisfactorily, and there is no evidence of problems with leaks in the compressor shaft sealings, neither in relation to the leakage of oil or steam, which was one of the central issues to clarify with the demonstration. In the limited testing period no problems were detected that could not be immediately resolved, i.e. the transmission in the form of a belt drive with high speed from the engine to the friction gear. In the determination of the performance of the compressor during the trial operation with steam as a working medium, it is shown that the conversion efficiency are within the expected range when taking into account the uncertainties in the measurements and the calculation method. In the experiment, no measurement of steam flow through the compressor was made, because of a greatly reduced

  17. Research on suitable heating conditions during local PWHT. Pt. 1. Influence of heating conditions on temperature distribution

    International Nuclear Information System (INIS)

    Tanaka, Jinkichi; Horii, Yukihiko; Sato, Masanobu; Murakawa, Hidekazu; Wang Jianhua

    1999-01-01

    To improve weld joint properties a heat treatment so called post weld heat treatment (PWHT) is often implemented for steel weldment. Generally, the PWHT is conducted in a furnace at a factory. But in site welds such as the girth joint of pipe, a local PWHT is applied using electric heater and so on. In the local PWHT steep temperature gradient occurs depending on the heating condition and it leads to rise of the thermal stress in addition to the welding residual stress. However, heating condition is not always defined the same in some standards. Therefore, suitable heat conditions for the local PWHT were studied supposing the power plant and so on experimentally and theoretically. Temperature distribution and thermal strains under different heating conditions were measured during the local PWHT using carbon steel pipes of 340 mm in diameter and 53 mm in wall thickness. The temperature gradient, thermal strain were also analyzed using Finite Element Method (FEM) as axis-symmetric model. Further, the influences of pipe size and heat transfer coefficient on the temperature distribution were analyzed and suitable heating source widths for various pipe sizes were proposed from the viewpoint of temperature distribution. (orig.)

  18. An Empirical Temperature Variance Source Model in Heated Jets

    Science.gov (United States)

    Khavaran, Abbas; Bridges, James

    2012-01-01

    An acoustic analogy approach is implemented that models the sources of jet noise in heated jets. The equivalent sources of turbulent mixing noise are recognized as the differences between the fluctuating and Favre-averaged Reynolds stresses and enthalpy fluxes. While in a conventional acoustic analogy only Reynolds stress components are scrutinized for their noise generation properties, it is now accepted that a comprehensive source model should include the additional entropy source term. Following Goldstein s generalized acoustic analogy, the set of Euler equations are divided into two sets of equations that govern a non-radiating base flow plus its residual components. When the base flow is considered as a locally parallel mean flow, the residual equations may be rearranged to form an inhomogeneous third-order wave equation. A general solution is written subsequently using a Green s function method while all non-linear terms are treated as the equivalent sources of aerodynamic sound and are modeled accordingly. In a previous study, a specialized Reynolds-averaged Navier-Stokes (RANS) solver was implemented to compute the variance of thermal fluctuations that determine the enthalpy flux source strength. The main objective here is to present an empirical model capable of providing a reasonable estimate of the stagnation temperature variance in a jet. Such a model is parameterized as a function of the mean stagnation temperature gradient in the jet, and is evaluated using commonly available RANS solvers. The ensuing thermal source distribution is compared with measurements as well as computational result from a dedicated RANS solver that employs an enthalpy variance and dissipation rate model. Turbulent mixing noise predictions are presented for a wide range of jet temperature ratios from 1.0 to 3.20.

  19. Metabolic Heat Regenerated Temperature Swing Adsorption for CO2, Thermal and Humidity Control, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Metabolic heat regenerated Temperature Swing Adsorption (MTSA) technology is proposed for a Portable Life Support System to remove and reject heat and carbon dioxide...

  20. Control of surface temperature of an aluminum alloy billet by air flow during a heating process at elevated temperature

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Young [KITECH, Cheonan (Korea, Republic of); Park, Joon Hong [Dong-A University, Busan (Korea, Republic of)

    2016-06-15

    The procedure of semi-solid forming is composed of heating a billet, forming, compression holding and ejecting step. There are several methods to heat a billet during semi-solid forming process such as electric heating and induction heating. Usually in semi-solid forming process, induction heating has been adopted to achieve more uniform temperature of semi-solid material. Although induction heating is better method than any others, however, there is still difference of temperature between internal part and surface part of semi-solid material. Worse yet, in case of high liquid fraction of semi-solid material, liquid of the billet will flow down though solid of the billet still remains, which is very difficult to handle. In the present study, induction heating of the billet during thixoforging process with forced surface cooling has been performed to obtain more uniform distribution of temperature, microstructure and shape of the billet. Distribution of temperature of the billets was measured and compared with that of conventional distribution of temperature. Microscopic and macroscopic aspects of the billets were discussed according to location of the measuring points. By this new induction heating method, not only temperature distributions over the whole billet become uniform, but also control of temperature distribution between inside and outside part of the billet is possible as user's experimental intentions,.

  1. Improving thermal performance of an existing UK district heat network: a case for temperature optimization

    DEFF Research Database (Denmark)

    Tunzi, Michele; Boukhanouf, Rabah; Li, Hongwei

    2018-01-01

    This paper presents results of a research study into improving energy performance of small-scale district heat network through water supply and return temperature optimization technique. The case study involves establishing the baseline heat demand of the estate’s buildings, benchmarking...... the existing heat network operating parameters, and defining the optimum supply and return temperature. A stepwise temperature optimization technique of plate radiators heat emitters was applied to control the buildings indoor thermal comfort using night set back temperature strategy of 21/18 °C....... It was established that the heat network return temperature could be lowered from the current measured average of 55 °C to 35.6 °C, resulting in overall reduction of heat distribution losses and fuel consumption of 10% and 9% respectively. Hence, the study demonstrates the potential of operating existing heat...

  2. Weak Solution and Weakly Uniformly Bounded Solution of Impulsive Heat Equations Containing “Maximum” Temperature

    Directory of Open Access Journals (Sweden)

    Oyelami, Benjamin Oyediran

    2013-09-01

    Full Text Available In this paper, criteria for the existence of weak solutions and uniformly weak bounded solution of impulsive heat equation containing maximum temperature are investigated and results obtained. An example is given for heat flow system with impulsive temperature using maximum temperature simulator and criteria for the uniformly weak bounded of solutions of the system are obtained.

  3. 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

  4. Performance analysis of double organic Rankine cycle for discontinuous low temperature waste heat recovery

    International Nuclear Information System (INIS)

    Wang Dongxiang; Ling Xiang; Peng Hao

    2012-01-01

    This research proposes a double organic Rankine cycle for discontinuous waste heat recovery. The optimal operation conditions of several working fluids have been calculated by a procedure employing MATLAB and REFPROP. The influence of outlet temperature of heat source on the net power output, thermal efficiency, power consumption, mass flow rate, expander outlet temperature, cycle irreversibility and exergy efficiency at a given pinch point temperature difference (PPTD) has been analyzed. Pinch point analysis has also been employed to obtain a thermodynamic understanding of the ORC performance. Of all the working fluids investigated, some performances between each working fluid are rather similar. For a fixed low temperature heat source, the optimal operation condition should be mainly determined by the heat carrier of the heat source, and working fluids have limited influence. Lower outlet temperature of heat source does not always mean more efficient energy use. Acetone exhibits the least exergy destruction, while R245fa possesses the maximal exergy efficiency at a fixed PPTD. Wet fluids exhibit lower thermal efficiency than the others with the increasing of PPTD at a fixed outlet temperature of heat source. Dry and isentropic fluids offer attractive performance. - Highlights: ► We propose a double organic Rankine cycle for discontinuous waste heat recovery. ► Performance of organic Rankine cycle (ORC) is analyzed by pinch point analysis. ► The heat carrier of the heat source determines ORC optimal operation condition. ► Design of ORC heat exchangers prefers lower pinch point temperature difference.

  5. Phase change based cooling for high burst mode heat loads with temperature regulation above the phase change temperature

    Science.gov (United States)

    The United States of America as represented by the United States Department of Energy

    2009-12-15

    An apparatus and method for transferring thermal energy from a heat load is disclosed. In particular, use of a phase change material and specific flow designs enables cooling with temperature regulation well above the fusion temperature of the phase change material for medium and high heat loads from devices operated intermittently (in burst mode). Exemplary heat loads include burst mode lasers and laser diodes, flight avionics, and high power space instruments. Thermal energy is transferred from the heat load to liquid phase change material from a phase change material reservoir. The liquid phase change material is split into two flows. Thermal energy is transferred from the first flow via a phase change material heat sink. The second flow bypasses the phase change material heat sink and joins with liquid phase change material exiting from the phase change material heat sink. The combined liquid phase change material is returned to the liquid phase change material reservoir. The ratio of bypass flow to flow into the phase change material heat sink can be varied to adjust the temperature of the liquid phase change material returned to the liquid phase change material reservoir. Varying the flowrate and temperature of the liquid phase change material presented to the heat load determines the magnitude of thermal energy transferred from the heat load.

  6. Analysis of microwave heating of materials with temperature-dependent properties

    International Nuclear Information System (INIS)

    Ayappa, K.G.; Davis, H.T.; Davis, E.A.; Gordon, J.

    1991-01-01

    In this paper transient temperature profiles in multilayer slabs are predicted, by simultaneously solving Maxwell's equations with the heat conduction equation, using Galerkin-finite elements. It is assumed that the medium is homogeneous and has temperature-dependent dielectric and thermal properties. The method is illustrated with applications involving the heating of food and polymers with microwaves. The temperature dependence of dielectric properties affects the heating appreciably, as is shown by comparison with a constant property model

  7. Heat capacity measurements on ThO2 by temperature modulated differential scanning calorimetry (TMDSC)

    International Nuclear Information System (INIS)

    Venkatakrishnan, R.; Nagarajan, K.; Vasudeva Rao, P.R.

    2001-01-01

    Heat capacity measurements were carried out on ThO 2 in the temperature range 330-820 K by using temperature modulated DSC. An underlying heating rate of 5 K. min -1 , a temperature modulation with an amplitude of 0.398K and a period of 150s were used for these measurements. The heat capacity values are within ± 2-4% of the literature data. (author)

  8. Depression of the Superfluid Transition Temperature in 4He by a Heat Flow

    International Nuclear Information System (INIS)

    Yin Liang; Qi Xin; Lin Peng

    2014-01-01

    The depression of the superfluid transition temperature T λ in 4 He by a heat flow Q is studied. A small sealed cell with a capillary is introduced and a stable and flat superfluid transition temperature plateau is easily obtained by controlling the temperature of the variable-temperature platform and the bottom chamber of the sealed cell. Owing to the depression effect of the superfluid transition temperature by the heat flow, the heat flow through the capillary is changed by the temperature control to obtain multiple temperature plateaus of different heat flows. The thermometer self-heating effect, the residual heat leak of the 4.2 K environment, the temperature difference on the He II liquid column, the Kapiza thermal resistance between the liquid helium and the copper surface of the sealed cell, the temperature gradient of the sealed cell, the static pressure of the He II liquid column and other factors have influence on the depression effect and the influence is analyzed in detail. Twenty experiments of the depression of the superfluid transition temperature in 4 He by heat flow are made with four sealed cells in one year. The formula of the superfluid transition temperature pressured by the heat flow is T λ (Q) = −0.00000103Q + 2.1769108, and covers the range 229 ≤ Q ≤ 6462 μW/cm 2

  9. A Numerical Study on the Heat Transfer Characteristics of a Solar Thermal Receiver with High-temperature Heat Pipes

    International Nuclear Information System (INIS)

    Park, Young Hark; Jung, Eui Guk; Boo, Joon Hong

    2007-01-01

    A numerical analysis was conducted to predict the heat transfer characteristics of a solar receiver which is subject to very high heat fluxes and temperatures for solar thermal applications. The concentration ratio of the solar receiver ranges from 200 to 1000 and the concentrated heat is required to be transported to a certain distance for specific applications. The study deals with a solar receiver incorporating high-temperature sodium heat pipe as well as typical one that employs a molten-salt circulation loop. The isothermal characteristics in the receiver section is of major concern. The diameter of the solar thermal receiver was 120 mm and the length was 400 mm. For the molten-salt circulation type receiver, 48 axial channels of the same dimensions were attached to the outer wall of the receiver with even spacing in the circumferential direction. The molten salt fed through the channels by forced convection using a special pump. For the heat pipe receiver, the channels are changed to high-temperature sodium heat pipes. Commercial softwares were employed to deal with the radiative heat transfer inside the receiver cavity and the convection heat transfer along the channels. The numerical results are compared and analyzed from the view point of high-temperature solar receiver

  10. Validation of the uncertainty budget for soft X-ray radiant power measurement using a cryogenic radiometer

    International Nuclear Information System (INIS)

    Rabus, H.; Klein, R.; Scholze, F.; Thornagel, R.; Ulm, G.

    2002-01-01

    The cryogenic radiometer SYRES, a thermal detector based on the electrical substitution principle, has been used as the primary detector standard for radiant power measurement in the ultraviolet, vacuum ultraviolet and soft X-ray spectral ranges. In order to investigate the possibility of radiant energy being deposited in its absorber cavity without being transformed into heat when detecting soft X-rays, SYRES has been directly compared with the electron storage ring BESSY 1, a primary radiometric source standard of calculable spectral radiant power. To this end, the integral radiant power emitted by the storage ring,into a solid angle defined by a high-precision aperture was measured with SYRES. The experiments were conducted at two nominal energies of the circulating electrons, 800 MeV and 340 MeV, to study the influence of the different spectral distributions of the synchrotron radiation. For the original graphite-coated cavity absorber, significant discrepancies were found which could be traced back to the ablation of the graphite coating from the copper cavity body. In the case of the new gold-coated cavity absorber, the calculated and measured values of the radiant power agreed in all experiments within the combined relative uncertainties of typically 2.5 x 10 -3 (k = 1). (author)

  11. Process Heat Exchanger Options for the Advanced High Temperature Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Piyush Sabharwall; Eung Soo Kim; Michael McKellar; Nolan Anderson

    2011-06-01

    The work reported herein is a significant intermediate step in reaching the final goal of commercial-scale deployment and usage of molten salt as the heat transport medium for process heat applications. The primary purpose of this study is to aid in the development and selection of the required heat exchanger for power production and process heat application, which would support large-scale deployment.

  12. Process Heat Exchanger Options for Fluoride Salt High Temperature Reactor

    International Nuclear Information System (INIS)

    Sabharwall, Piyush; Kim, Eung Soo; McKellar, Michael; Anderson, Nolan

    2011-01-01

    The work reported herein is a significant intermediate step in reaching the final goal of commercial-scale deployment and usage of molten salt as the heat transport medium for process heat applications. The primary purpose of this study is to aid in the development and selection of the required heat exchanger for power production and process heat application, which would support large-scale deployment.

  13. Process Heat Exchanger Options for Fluoride Salt High Temperature Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Piyush Sabharwall; Eung Soo Kim; Michael McKellar; Nolan Anderson

    2011-04-01

    The work reported herein is a significant intermediate step in reaching the final goal of commercial-scale deployment and usage of molten salt as the heat transport medium for process heat applications. The primary purpose of this study is to aid in the development and selection of the required heat exchanger for power production and process heat application, which would support large-scale deployment.

  14. Analysis and research on promising solutions of low temperature district heating without risk of legionella

    DEFF Research Database (Denmark)

    Yang, Xiaochen; Li, Hongwei; Fog, Jette M.

    2014-01-01

    Most regulations of domestic hot water supply temperature is around 55-60 oC, which potentially requires higher district heating temperature. However, high supply temperature of district heating causes many problems, such as the high heating loss, and obstacles for applying renewable energy...... resources. The most crucial restriction for applying low temperature district heating is the worry about the breakout of legionella, which exists preferably in low temperature hot water systems. Several novel techniques such as electric tracing and flat station were investigated for such dilemma. The pros...... and cons were compared in this paper. Both the energy and economy saving ratios were analysed comparing with high temperature supply scenario. Furthermore, the viability of the applications in different types of buildings for low temperature district heating (LTDH) was also discussed by using dynamic...

  15. Simultaneous determination of reference free-stream temperature and convective heat transfer coefficients

    International Nuclear Information System (INIS)

    Jeong, Gi Ho; Song, Ki Bum; Kim, Kui Soon

    2001-01-01

    This paper deals with the development of a new method that can obtain heat transfer coefficient and reference free stream temperature simultaneously. The method is based on transient heat transfer experiments using two narrow-band TLCs. The method is validated through error analysis in terms of the random uncertainties in the measured temperatures. It is shown how the uncertainties in heat transfer coefficient and free stream temperature can be reduced. The general method described in this paper is applicable to many heat transfer models with unknown free stream temperature

  16. The effects of heated and room-temperature abdominal lavage solutions on core body temperature in dogs undergoing celiotomy.

    Science.gov (United States)

    Nawrocki, Michael A; McLaughlin, Ron; Hendrix, P K

    2005-01-01

    To document the magnitude of temperature elevation obtained with heated lavage solutions during abdominal lavage, 18 dogs were lavaged with sterile isotonic saline intraoperatively (i.e., during a celiotomy). In nine dogs, room-temperature saline was used. In the remaining nine dogs, saline heated to 43+/-2 degrees C (110+/-4 degrees F) was used. Esophageal, rectal, and tympanic temperatures were recorded every 60 seconds for 15 minutes after initiation of the lavage. Temperature levels decreased in dogs lavaged with room-temperature saline. Temperature levels increased significantly in dogs lavaged with heated saline after 2 to 6 minutes of lavage, and temperatures continued to increase throughout the 15-minute lavage period.

  17. A study of heat capacity temperature limit of BWR

    International Nuclear Information System (INIS)

    Wang, Shih-Jen; Chen, Jyh-Jun; Chien, Chun-Sheng; Teng, Jyh-Tong

    2012-01-01

    Highlights: ► The purpose of this study is to verify the HCTL. ► MAAP4 was used as code to generate a realistic and convenient HCTL. ► The current HCTL curve causes confusing in reading data. ► The revised HCTL curves developed in this study. ► Users can obtain important parameters from the revised HCTL without confusion and interpolation. - Abstract: Heat capacity temperature limit (HCTL) is an important parameter for operation of BWR. Current version of the HCTL was derived, based on simple model of computation aids (CA) of BWR owners’ group (BWROG). However, some parts of the current HCTL are confusing to the users in reading data. The purpose of this study is to verify the HCTL by applying the MAAP4 code to the field of emergency operating procedure (EOP). The trends of HCTL generated by MAAP4 code are consistent with those obtained from CA. A series of revised HCTL evaluated at various times after scram are provided and the confusing part is eliminated.

  18. A study of heat capacity temperature limit of BWR

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shih-Jen, E-mail: sjenwang@iner.gov.tw [Institute of Nuclear Energy Research (INER), 1000, Wunhua Rd., Jiaan Village, Longtan Township, Taoyuan County 32546, Taiwan (China); Chen, Jyh-Jun [Department of Mechanical Engineering, Chung Yuan Christian University, 200, Chung Pei Rd., Chung Li City, Taoyuan County 32023, Taiwan (China); Chien, Chun-Sheng [Institute of Nuclear Energy Research (INER), 1000, Wunhua Rd., Jiaan Village, Longtan Township, Taoyuan County 32546, Taiwan (China); Teng, Jyh-Tong [Department of Mechanical Engineering, Chung Yuan Christian University, 200, Chung Pei Rd., Chung Li City, Taoyuan County 32023, Taiwan (China)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer The purpose of this study is to verify the HCTL. Black-Right-Pointing-Pointer MAAP4 was used as code to generate a realistic and convenient HCTL. Black-Right-Pointing-Pointer The current HCTL curve causes confusing in reading data. Black-Right-Pointing-Pointer The revised HCTL curves developed in this study. Black-Right-Pointing-Pointer Users can obtain important parameters from the revised HCTL without confusion and interpolation. - Abstract: Heat capacity temperature limit (HCTL) is an important parameter for operation of BWR. Current version of the HCTL was derived, based on simple model of computation aids (CA) of BWR owners' group (BWROG). However, some parts of the current HCTL are confusing to the users in reading data. The purpose of this study is to verify the HCTL by applying the MAAP4 code to the field of emergency operating procedure (EOP). The trends of HCTL generated by MAAP4 code are consistent with those obtained from CA. A series of revised HCTL evaluated at various times after scram are provided and the confusing part is eliminated.

  19. Simulated Lunar Testing of Metabolic Heat Regenerated Temperature Swing Adsorption

    Science.gov (United States)

    Padilla, Sebastian A.; Bower, Chad E.; Iacomini, Christie S.; Paul, Heather L.

    2012-01-01

    Metabolic heat regenerated Temperature Swing Adsorption (MTSA) technology is being developed for thermal and carbon dioxide (CO2) control for a Portable Life Support System (PLSS), as well as water recycling. An Engineering Development Unit (EDU) of the MTSA Subassembly (MTSAS) was designed and assembled for optimized Martian operations, but also meets system requirements for lunar operations. For lunar operations the MTSA sorption cycle is driven via a vacuum swing between suit ventilation loop pressure and lunar vacuum. The focus of this effort was testing in a simulated lunar environment. This environment was simulated in Paragon's EHF vacuum chamber. The objective of the testing was to evaluate the full cycle performance of the MTSA Subassembly EDU, and to assess CO2 loading and pressure drop of the wash coated aluminum reticulated foam sorbent bed. Lunar environment testing proved out the feasibility of pure vacuum swing operation, making MTSA a technology that can be tested and used on the Moon prior to going to Mars. Testing demonstrated better than expected CO2 Nomenclature loading on the sorbent and nearly replicates the equilibrium data from the sorbent manufacturer. This exceeded any of the previous sorbent loading tests performed by Paragon. Subsequently, the increased performance of the sorbent bed design indicates future designs will require less mass and volume than the current EDU rendering MTSA as very competitive for Martian PLSS applications.

  20. Experimental study of energy performance in low-temperature hydronic heating systems

    DEFF Research Database (Denmark)

    Hesaraki, Arefeh; Bourdakis, Eleftherios; Ploskić, Adnan

    2015-01-01

    Energy consumption, thermal environment and environmental impacts were analytically and experimentally studied for different types of heat emitters. The heat emitters studied were conventional radiator, ventilation radiator, and floor heating with medium-, low-, and very-low-temperature supply....... The supply water temperature in all measurements for conventional radiator was significantly higher than ventilation radiator and floor heating; namely, 45°C. Experimental results indicated that the mean indoor temperature was close to the acceptable level of 22°C in all cases. For energy calculations......, it was assumed that all heat emitters were connected to a ground-source heat pump. Analytical calculations showed that using ventilation radiator and floor heating instead of conventional radiator resulted in a saving of 17% and 22% in heat pump's electricity consumption, respectively. This would reduce the CO2...

  1. A thermoacoustic engine capable of utilizing multi-temperature heat sources

    International Nuclear Information System (INIS)

    Qiu Limin; Wang Bo; Sun Daming; Liu Yu; Steiner, Ted

    2009-01-01

    Low-grade energy is widespread. However, it cannot be utilized with high thermal efficiency directly. Following the principle of thermal energy cascade utilization, a thermoacoustic engine (TE) with a new regenerator that can be driven by multiple heat sources at different temperature levels is proposed. Taking a regenerator that utilizes heat sources at two temperatures as an example, theoretical research has been conducted on a traveling-wave TE with the new regenerator to predict its performance. Experimental verification is also done to demonstrate the benefits of the new regenerator. Results indicate that a TE with the new regenerator utilizing additional heat at a lower temperature experiences an increase in pressure ratio, acoustic power, efficiency, and exergy efficiency with proper heat input at an appropriate temperature at the mid-heater. A regenerator that uses multi-temperature heat sources can provide a means of recovering lower grade heat.

  2. Coupled heat transfer in high temperature transporting system with semitransparent/opaque material

    International Nuclear Information System (INIS)

    Du Shenghua; Xia Xinjin

    2010-01-01

    The heat transfer model of the aerodynamic heating coupled with radiative cooling was developed. The thermal protect system includes the higher heat flux region with high temperature semitransparent material, the heat transporting channel and the lower heat flux region with metal. The control volume method was combined with the Monte Carlo method to calculate the coupled heat transfer of the transporting system, and the thermal equilibrium equation for the transporting channel was solved simultaneously. The effect of the aeroheating flux radio, the area ratio of radiative surfaces, the convective heat transfer coefficient of the heat transporting channel on the radiative surface temperature and the fluid temperature in the heat transporting channel were analyzed. The effect of radiation and conduction in the semitransparent material was discussed. The result shows that to increase the convective heat transfer coefficient in heat flux channel can enhance the heat transporting ability of the system, but the main parameter to effect on the temperature of the heat transporting system is the area ratio of radiative surfaces. (authors)

  3. Solar hybrid cooling system for high-tech offices in subtropical climate - Radiant cooling by absorption refrigeration and desiccant dehumidification

    International Nuclear Information System (INIS)

    Fong, K.F.; Chow, T.T.; Lee, C.K.; Lin, Z.; Chan, L.S.

    2011-01-01

    Highlights: → A solar hybrid cooling system is proposed for high-tech offices in subtropical climate. → An integration of radiant cooling, absorption refrigeration and desiccant dehumidification. → Year-round cooling and energy performances were evaluated through dynamic simulation. → Its annual primary energy consumption was lower than conventional system up to 36.5%. → The passive chilled beams were more energy-efficient than the active chilled beams. - Abstract: A solar hybrid cooling design is proposed for high cooling load demand in hot and humid climate. For the typical building cooling load, the system can handle the zone cooling load (mainly sensible) by radiant cooling with the chilled water from absorption refrigeration, while the ventilation load (largely latent) by desiccant dehumidification. This hybrid system utilizes solar energy for driving the absorption chiller and regenerating the desiccant wheel. Since a high chilled water temperature generated from the absorption chiller is not effective to handle the required latent load, desiccant dehumidification is therefore involved. It is an integration of radiant cooling, absorption refrigeration and desiccant dehumidification, which are powered up by solar energy. In this study, the application potential of the solar hybrid cooling system was evaluated for the high-tech offices in the subtropical climate through dynamic simulation. The high-tech offices are featured with relatively high internal sensible heat gains due to the intensive office electric equipment. The key performance indicators included the solar fraction and the primary energy consumption. Comparative study was also carried out for the solar hybrid cooling system using two common types of chilled ceilings, the passive chilled beams and active chilled beams. It was found that the solar hybrid cooling system was technically feasible for the applications of relatively higher cooling load demand. The annual primary energy

  4. Investigation of ammonia/water hybrid absorption/compression heat pumps for heat supply temperatures above 100 °C

    DEFF Research Database (Denmark)

    Jensen, Jonas Kjær; Reinholdt, Lars; Markussen, Wiebke Brix

    2014-01-01

    The hybrid absorption/compression heat pump (HACHP) using ammonia-water as working fluid is a promising technology for development of a high temperature industrial heat pump. This is due to two properties inherent to the use of zeotropic mixtures: non-isothermal phase change and reduced vapour...... using these components. A technically and economically feasible solution is defined as one that satisfies constraints on the coefficient of performance (COP), low and high pressure, compressor discharge temperature and volumetric heat capacity. The ammonia mass fraction of the rich solution...

  5. A METHOD FOR EVALUATION OF NON-UNIFORM RADIANT-CONVECTIVE LOAD ON HUMAN BODY DURING MENTAL WORK

    Directory of Open Access Journals (Sweden)

    Lenka Prokšová Zuská

    2017-10-01

    Full Text Available The objective of this study was to develop a documentation for the amendment of the microclimatic part of the Czech Government Regulation, particularly in a non-uniform radiant-convective load evaluation. Changes in regulation were made based on experimental data obtained on a group of experimental individuals in a climatic chamber. One of the objectives of the climatic chamber experiments was to evaluate whether there was a possibility to use an alternative method, which utilizes a new value – stereotemperature, for the assessment. A group of 24 women was exposed to a non-uniform radiant-convective load in a climatic chamber for 1 hour during their computer work. Measurements were divided according to the globe temperature into 3 stages. The physical parameters of air were continuously measured: the air temperature, globe temperature, air velocity, radiant temperature, relative humidity, stereotemperature and physiological parameters. Thermal sensations of experimental subjects were expressed in the seven-point scale according to EN ISO 7730. The thermal sensation correlated very well with the difference of stereotemperature and the globe temperature. The stereotemperature correlated very well with the radiant temperature. In this work, the composed equations were used to develop the limit values for the thermal stress evaluation in the uniform and non-uniform thermal environment at workplaces. It is possible to determine how the body of an exposed person perceives the non-uniform climatic conditions in the indoor environment, by adding the stereotemperature to government regulations.

  6. Thermal analysis of heat and power plant with high temperature reactor and intermediate steam cycle

    Directory of Open Access Journals (Sweden)

    Fic Adam

    2015-03-01

    Full Text Available Thermal analysis of a heat and power plant with a high temperature gas cooled nuclear reactor is presented. The main aim of the considered system is to supply a technological process with the heat at suitably high temperature level. The considered unit is also used to produce electricity. The high temperature helium cooled nuclear reactor is the primary heat source in the system, which consists of: the reactor cooling cycle, the steam cycle and the gas heat pump cycle. Helium used as a carrier in the first cycle (classic Brayton cycle, which includes the reactor, delivers heat in a steam generator to produce superheated steam with required parameters of the intermediate cycle. The intermediate cycle is provided to transport energy from the reactor installation to the process installation requiring a high temperature heat. The distance between reactor and the process installation is assumed short and negligable, or alternatively equal to 1 km in the analysis. The system is also equipped with a high temperature argon heat pump to obtain the temperature level of a heat carrier required by a high temperature process. Thus, the steam of the intermediate cycle supplies a lower heat exchanger of the heat pump, a process heat exchanger at the medium temperature level and a classical steam turbine system (Rankine cycle. The main purpose of the research was to evaluate the effectiveness of the system considered and to assess whether such a three cycle cogeneration system is reasonable. Multivariant calculations have been carried out employing the developed mathematical model. The results have been presented in a form of the energy efficiency and exergy efficiency of the system as a function of the temperature drop in the high temperature process heat exchanger and the reactor pressure.

  7. Analysis of the Potential of Low-Temperature Heat Pump Energy Sources

    Directory of Open Access Journals (Sweden)

    Pavel Neuberger

    2017-11-01

    Full Text Available The paper deals with an analysis of temperatures of ground masses in the proximities of linear and slinky-type HGHE (horizontal ground heat exchanger. It evaluates and compares the potentials of HGHEs and ambient air. The reason and aim of the verification was to gain knowledge of the temperature course of the monitored low-temperature heat pump energy sources during heating periods and periods of stagnation and to analyse the knowledge in terms of the potential to use those sources for heat pumps. The study was conducted in the years 2012–2015 during three heating periods and three periods of HGHEs stagnation. The results revealed that linear HGHE had the highest temperature potential of the observed low-temperature heat pump energy sources. The average daily temperatures of the ground mass surrounding the linear HGHE were the highest ranging from 7.08 °C to 9.20 °C during the heating periods, and having the lowest temperature variation range of 12.62–15.14 K, the relative frequency of the average daily temperatures of the ground mass being the highest at 22.64% in the temperature range containing the mode of all monitored temperatures in a recorded interval of [4.10, 6.00] °C. Ambient air had lower temperature potential than the monitored HGHEs.

  8. Lithium bromide high-temperature absorption heat pump: coefficient of performance and exergetic efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Izquierdo, M [Consejo Superior de Investigaciones Cientificas, Madrid (ES). Inst. de Optica; Aroca, S [Escuela Tecnica Superior de Ingenieros Industriales, Valladolid (ES). Catedratico de Ingenieria Termica

    1990-04-01

    A theoretical study of a lithium bromide absorption heat pump, used as a machine type I and aimed to produce heat at 120{sup 0}C via waste heat sources at 60{sup 0}C, is given. Real performance conditions are stated for each component of the machine. By means of thermodynamic diagrams (p, t, x) and (h, x), the required data are obtained for calculation of the heat recovered in the evaporator Q{sub e}, the heat delivered to the absorber Q{sub a} and to the condenser Q{sub c}, and the heat supplied to the generator Q{sub g}. The heat delivered by the hot solution to the cold solution in the heat recovered Q{sub r}, and the work W{sub p} done by the solution pump are calculated. The probable COP is calculated as close to 1.4 and the working temperature in the generator ranges from 178 to 200{sup 0}C. The heat produced by the heat pump is 22% cheaper than that obtained from a cogeneration system comprising a natural gas internal combustion engine and high temperature heat pump with mechanical compression. Compared with a high temperature heat pump with mechanical compression, the heat produced by the absorption heat pump is 31% cheaper. From (h, x) and (s, x) diagrams, exergy losses for each component can be determined leading to an exergetic efficiency of 75% which provides the quality index of the absorption cycle. (author).

  9. Performance analysis for an irreversible variable temperature heat reservoir closed intercooled regenerated Brayton cycle

    International Nuclear Information System (INIS)

    Wang Wenhua; Chen Lingen; Sun Fengrui; Wu Chih

    2003-01-01

    In this paper, the theory of finite time thermodynamics is used in the performance analysis of an irreversible closed intercooled regenerated Brayton cycle coupled to variable temperature heat reservoirs. The analytical formulae for dimensionless power and efficiency, as functions of the total pressure ratio, the intercooling pressure ratio, the component (regenerator, intercooler, hot and cold side heat exchangers) effectivenesses, the compressor and turbine efficiencies and the thermal capacity rates of the working fluid and the heat reservoirs, the pressure recovery coefficients, the heat reservoir inlet temperature ratio, and the cooling fluid in the intercooler and the cold side heat reservoir inlet temperature ratio, are derived. The intercooling pressure ratio is optimized for optimal power and optimal efficiency, respectively. The effects of component (regenerator, intercooler and hot and cold side heat exchangers) effectivenesses, the compressor and turbine efficiencies, the pressure recovery coefficients, the heat reservoir inlet temperature ratio and the cooling fluid in the intercooler and the cold side heat reservoir inlet temperature ratio on optimal power and its corresponding intercooling pressure ratio, as well as optimal efficiency and its corresponding intercooling pressure ratio are analyzed by detailed numerical examples. When the heat transfers between the working fluid and the heat reservoirs are executed ideally, the pressure drop losses are small enough to be neglected and the thermal capacity rates of the heat reservoirs are infinite, the results of this paper replicate those obtained in recent literature

  10. 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

  11. Expieriences On Low-Temperature District Heating In Lystrup – Denmark

    DEFF Research Database (Denmark)

    Thorsen, Jan Eric; Christiansen, Christian Holm; Brand, Marek

    2011-01-01

    by implementing Low-temperature district heating systems. Demonstration cases in EnergyFlexHouse and Boligforeningen Ringgården” EUDP 2011. A key challenge for optimum and competitive district heating (DH) system operation is reducing heat loss in networks. Today building regulations in most countries demand...

  12. The Influence Of Burner Locations In The Heating Furnace On The Charge Temperature Field

    Directory of Open Access Journals (Sweden)

    Rywotycki M.

    2015-09-01

    Full Text Available Charge heating in industrial furnaces is a difficult and complex process. There are many physical phenomena which influence heat transfer. At the charge surface heat transfer takes place by radiation and convection. In order to ensure correct operation of the technological system, it is necessary to achieve the required charge temperature in the whole volume and ensure its uniformity.

  13. Study on boiling heat transfer of high temperature liquid sodium

    International Nuclear Information System (INIS)

    Sakurai, Akira

    1978-01-01

    In the Intitute of Atomic Energy, Kyoto University, fundamental studies on steady state and non-steady state heat flow are underway in connection with reactor design and the safety in a critical accident in a sodium-cooled fast breeder reactor. First, the experimental apparatus for sodium heat transfer and the testing system are described in detail. The apparatus is composed of sodium-purifying section including the plugging meter for measuring purity and cold trap, the pool boiling test section for experimenting natural convection boiling heat transfer, the forced convection boiling test section for experimenting forced convection boiling heat transfer, and gas system. Next, the experimental results by the author and the data obtained so far are compared regarding heat transfer in sodium natural convection and stable nucleating boiling and critical heat flux. The effect of liquid head on a heater on boiling heat transfer coefficient and critical heat flux under the condition of low system pressure in most fundamental pool boiling was elucidated quantitatively, which has been overlooked in previous studies. It was clarified that this is the essentially important problem that can not be overlooked. From this point of view, expressions on heat transfer were also re-investigated. (Wakatsuki, Y.)

  14. Influence of Gas-Liquid Interface on Temperature Wave of Pulsating Heat Pipe

    Directory of Open Access Journals (Sweden)

    Ying Zhang

    2018-01-01

    Full Text Available The influence of the interface on the amplitude and phase of the temperature wave and the relationship between the attenuation of the temperature wave and the gas-liquid two-phase physical parameters are studied during the operation of the pulsating heat pipe. The numerical simulation shows that the existence of the phase interface changes the direction of the temperature gradient during the propagation of the temperature wave, which increases the additional “thermal resistance.” The relative size of the gas-liquid two-phase thermal conductivity affects the propagation direction of heat flow at phase interface directly. The blockage of the gas plug causes hysteresis in the phase of the temperature wave, the relative size of the gas-liquid two-phase temperature coefficient will gradually increase the phase of the temperature wave, and the time when the heat flow reaches the peak value is also advanced. The attenuation of the temperature wave is almost irrelevant to the absolute value of the density, heat capacity, and thermal conductivity of the gas-liquid two phases, and the ratio of the thermal conductivity of the gas-liquid two phases is related. When the temperature of the heat pipe was changed, the difference of heat storage ability between gas and liquid will lead to the phenomenon of heat reflux and becomes more pronounced with the increases of the temperature wave.

  15. Influence of time presetting procedure for rapid local heat;.ng on brazing temperature conditions

    International Nuclear Information System (INIS)

    Lezhnin, G.P.; Tul'skikh, V.E.

    1985-01-01

    Correlation of known and suggested presetting procedures for heating period during induction brazing was conducted. It is shown that brazing time must be established considering heat propagation during heating in order to obtain the assigned joint temperature regardless of heating rate change. Methods for temperature calculation in assigned zones of the joint are suggested. The suggested presetting procedure for heating time was applied for induction vacuum brazing of a tube of 12Kh18N10T steel to a pipe connection of VT20 alloy

  16. The study of development of welded compact plate heat exchanger for high temperature and pressure

    International Nuclear Information System (INIS)

    Park, Jae Hong; Lim, Hyug; Kim, Jung Kyu; Cho, Sung Youl; Kwon, Oh Boong

    2009-01-01

    In view of space saving, the design of more compact heat exchangers is relatively important. Also, to meet the demand for saving energy and resources today, manufacturers are trying to enhance efficiency and reduce the size and weight of heat exchangers. Over the past decade, there has been tremendous advancement in the manufacturing technology of high efficiency heat exchangers. This has allowed the use of smaller and high performance heat exchangers. Consequently, the use of smaller and high performance heat exchanger becomes popular in the design of heat exchangers. Welded compact plate heat exchanger is used in high temperature and pressure. In the design of heat exchanger, it is necessary to understand the heat transfer characteristics, so performance data are provided to help design of this type heat exchanger.

  17. Effect of microwave-assisted heating on chalcopyrite leaching of kinetics, interface temperature and surface energy

    Directory of Open Access Journals (Sweden)

    Tong Wen

    Full Text Available The microwave-assisted leaching was a new approach to intensify the copper recovery from chalcopyrite by hydrometallurgy. In this work, the effect of microwave-assisted heating on chalcopyrite leaching of kinetics, interfacial reaction temperature and surface energy were investigated. The activation energy of chalcopyrite leaching was affected indistinctively by the microwave-assisted heating (39.1 kJ/mol compared with the conventional heating (43.9 kJ/mol. However, the boiling point of the leaching system increased through microwave-assisted heating. Because of the improved boiling point and the selective heating of microwave, the interfacial reaction temperature increased significantly, which gave rise to the increase of the leaching recovery of copper. Moreover, the surface energy of the chalcopyrite through microwave-assisted heating was also enhanced, which was beneficial to strengthen the leaching of chalcopyrite. Keywords: Microwave-assisted heating, Chalcopyrite, Leaching kinetics, Interface temperature, Surface energy

  18. Heat waves measured with MODIS land surface temperature data predict changes in avian community structure

    Science.gov (United States)

    Thomas P. Albright; Anna M. Pidgeon; Chadwick D. Rittenhouse; Murray K. Clayton; Curtis H. Flather; Patrick D. Culbert; Volker C. Radeloff

    2011-01-01

    Heat waves are expected to become more frequent and severe as climate changes, with unknown consequences for biodiversity. We sought to identify ecologically-relevant broad-scale indicators of heat waves based on MODIS land surface temperature (LST) and interpolated air temperature data and assess their associations with avian community structure. Specifically, we...

  19. Heat Capacity of Room-Temperature Ionic Liquids: A Critical Review

    Science.gov (United States)

    Paulechka, Yauheni U.

    2010-09-01

    Experimental data on heat capacity of room-temperature ionic liquids in the liquid state were compiled and critically evaluated. The compilation contains data for 102 aprotic ionic liquids from 63 literature references and covers the period of time from 1998 through the end of February 2010. Parameters of correlating equations for temperature dependence of the heat capacities were developed.

  20. Determination of Factors Related to Students' Understandings of Heat, Temperature and Internal Energy Concepts

    Science.gov (United States)

    Gurcay, Deniz; Gulbas, Etna

    2018-01-01

    The purpose of this research is to investigate the relationships between high school students' learning approaches and logical thinking abilities and their understandings of heat, temperature and internal energy concepts. Learning Approach Questionnaire, Test of Logical Thinking and Three-Tier Heat, Temperature and Internal Energy Test were used…

  1. Twin solution calorimeter determines heats of formation of alloys at high temperatures

    Science.gov (United States)

    Darby, J. B., Jr.; Kleb, R.; Kleppa, O. J.

    1968-01-01

    Calvert-type, twin liquid metal solution calorimeter determines the heats of formation of transition metal alloys at high temperatures. The twin differential calorimeter measures the small heat effects generated over extended periods of time, has maximum operating temperature of 1073 degrees K and an automatic data recording system.

  2. The TX-model - a quantitative heat loss analysis of district heating pipes by means of IR surface temperature measurements

    Energy Technology Data Exchange (ETDEWEB)

    Zinki, Heimo [ZW Energiteknik, Nykoeping (Sweden)

    1996-11-01

    The aim of this study was to investigate the possibility of analysing the temperature profile at the ground surface above buried district heating pipes in such a way that would enable the quantitative determination of heat loss from the pair of pipes. In practical applications, it is supposed that this temperature profile is generated by means of advanced IR-thermography. For this purpose, the principle of the TX - model has been developed, based on the fact that the heat losses from pipes buried in the ground have a temperature signature on the ground surface. Qualitative analysis of this temperature signature is very well known and in practical use for detecting leaks from pipes. These techniques primarily make use of relative changes of the temperature pattern along the pipe. In the quantitative heat loss analysis, however, it is presumed that the temperature profile across the pipes is related to the pipe heat loss per unit length. The basic idea is that the integral of the temperature profile perpendicular to the pipe, called TX, is a function of the heat loss, but is also affected by other parameters such as burial depth, heat diffusivity, wind, precipitation and so on. In order to analyse the parameters influencing the TX- factor, a simulation model for the energy balance at the ground surface has been developed. This model includes the heat flow from the pipe to the surface and the heat exchange at the surface with the environment due to convection, latent heat change, solar and long wave radiation. The simulation gives the surprising result that the TX factor is by and large unaffected during the course of a day even when the sun is shining, as long as other climate conditions are relatively stable (low wind, no rain, no shadows). The results from the simulations were verified at different sites in Denmark, Finland, Sweden and USA through a co-operative research program organised and partially financed by the IEA District Heating Programme, Task III, and

  3. Low-temperature heat capacity of molybdenum borides

    International Nuclear Information System (INIS)

    Bolgar, A.S.; Klinder, A.V.; Novoseletskaya, L.M.; Turov, V.P.; Klochkov, L.A.; Lyashchenko, A.B.

    1988-01-01

    Heat capacity of molybdenum borides Mo 2 B, MoB, Mo 2 B 5 is studied for the first time in the 60-300 K range using the adiabatic method. Standard (at 298.15 K) thermodynamic functions (enthalpy, heat capacity, entropy, reduced Gibbs energy) of molybdenum borides are calculated

  4. Temperature mapping, thermal diffusivity and subsoil heat flux at ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    vide an understanding of the gain or loss of heat by the soil from the atmosphere. Many studies made earlier have been related to sim- ilar issues such as prediction of soil tempera- tures; heat storage variations; thermal diffusivity of the soil, etc. (Kelkar et al 1980; Chowdhury et al 1991; Lamba and Khambete 1991; Retnaku ...

  5. Exergy analysis for stationary flow systems with several heat exchange temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Lampinen, M J; Heikkinen, M A [Helsinki Univ. of Technology, Espoo (Finland). Dept. of Energy Engineering

    1995-07-01

    A thermodynamic theory of exergy analysis for a stationary flow system having several heat inputs and outputs at different temperature levels is presented. As a new result a relevant reference temperature of the surroundings is derived for each case. Also a general formula which combines exergy analysis with a modified Carnot efficiency is derived. The results are illustrated by numerical examples for mechanical multi-circuit heat pump cycles, for a Brayton process and for an absorption heat pump. (Author)

  6. Thermal environment in simulated offices with convective and radiant cooling systems under cooling (summer) mode of operation

    DEFF Research Database (Denmark)

    Mustakallio, Panu; Bolashikov, Zhecho Dimitrov; Kostov, Kalin

    2016-01-01

    The thermal environment in a double office room and in a six-person meeting room obtained with chilled beam (CB), chilled beam with radiant panel (CBR), chilled ceiling with ceiling installed mixing ventilation (CCMV) and four desk partition-mounted local radiant cooling panels with mixing...... calculated. Manikin-based equivalent temperature (MBET) was determined by using two thermal manikins to identify the impact of the local thermal conditions generated by the studied systems on occupants' thermal perception. The results revealed that the differences in the thermal conditions achieved...

  7. Experimental investigation on heating performance of heat pump for electric vehicles at −20 °C ambient temperature

    International Nuclear Information System (INIS)

    Qin, Fei; Xue, Qingfeng; Albarracin Velez, Giovanny Marcelo; Zhang, Guiying; Zou, Huiming; Tian, Changqing

    2015-01-01

    Highlights: • An ASHP system with refrigerant injection for EVs is designed, for cold regions. • The heat performances of the system are tested at −20 °C ambient temperature. • The system cycle process with refrigerant injection are analyzed on lgP-H diagrams. • The effects of refrigerant injection, dryness, and in-car inlet state are discussed. • The new system can improve heating and own better application prospect. - Abstract: Since the performance of conventional air source heat pump (ASHP) for electric vehicles (EVs) is apt to decline sharply in low ambient temperature, it will consume more electricity of the cell, and affect driving mileage in cold regions. Aiming at developing high efficiency heating system for EVs in cold regions, an ASHP system applying refrigerant injection for EVs is designed, as well as the test bench is built to investigate its performance. According to the operation condition of EVs, heating performances are tested on different in-car inlet air temperature and various fresh air ratios under −20 °C ambient temperature. The system cycle process with refrigerant injection, as well as the influences of refrigerant injection and dryness are also analyzed and discussed. The results show that the heating capacity of the ASHP with refrigerant injection can be increased up to 31%, and in comparison with the conventional heat pump system its heating performance is better when in-car inlet temperature is above −10 °C. Therefore, ASHP with refrigerant injection has great potentiality to be applied for the EVs in cold regions

  8. Use of a commercial heat transfer code to predict horizontally oriented spent fuel rod surface temperatures

    International Nuclear Information System (INIS)

    Wix, S.D.; Koski, J.A.

    1993-03-01

    Radioactive spent fuel assemblies are a source of hazardous waste that will have to be dealt with in the near future. It is anticipated that the spent fuel assemblies will be transported to disposal sites in spent fuel transportation casks. In order to design a reliable and safe transportation cask, the maximum cladding temperature of the spent fuel rod arrays must be calculated. A comparison between numerical calculations using commercial thermal analysis software packages and experimental data simulating a horizontally oriented spent fuel rod array was performed. Twelve cases were analyzed using air and helium for the fill gas, with three different heat dissipation levels. The numerically predicted temperatures are higher than the experimental data for all levels of heat dissipation with air as the fill gas. The temperature differences are 4 degree C and 23 degree C for the low heat dissipation and high heat dissipation, respectively. The temperature predictions using helium as a fill gas are lower for the low and medium heat dissipation levels, but higher at the high heat dissipation. The temperature differences are 1 degree C and 6 degree C for the low and medium heat dissipation, respectively. For the high heat dissipation level, the temperature predictions are 16 degree C higher than the experimental data. Differences between the predicted and experimental temperatures can be attributed to several factors. These factors include experimental uncertainty in the temperature and heat dissipation measurements, actual convection effects not included in the model, and axial heat flow in the experimental data. This work demonstrates that horizontally oriented spent fuel rod surface temperature predictions can be made using existing commercial software packages. This work also shows that end effects will be increasingly important as the amount of dissipated heat increases

  9. Elevated exhaust temperature, zoned, electrically-heated particulate matter filter

    Science.gov (United States)

    Gonze, Eugene V [Pinckney, MI; Bhatia, Garima [Bangalore, IN

    2012-04-17

    A system includes an electrical heater and a particulate matter (PM) filter that is arranged one of adjacent to and in contact with the electrical heater. A control module selectively increases an exhaust gas temperature of an engine to a first temperature and that initiates regeneration of the PM filter using the electrical heater while the exhaust gas temperature is above the first temperature. The first temperature is greater than a maximum exhaust gas temperature at the PM filter during non-regeneration operation and is less than an oxidation temperature of the PM.

  10. Fabrication of High-Temperature Heat Exchangers by Plasma Spraying Exterior Skins on Nickel Foams

    Science.gov (United States)

    Hafeez, P.; Yugeswaran, S.; Chandra, S.; Mostaghimi, J.; Coyle, T. W.

    2016-06-01

    Thermal-sprayed heat exchangers were tested at high temperatures (750 °C), and their performances were compared to the foam heat exchangers made by brazing Inconel sheets to their surface. Nickel foil was brazed to the exterior surface of 10-mm-thick layers of 10 and 40 PPI nickel foam. A plasma torch was used to spray an Inconel coating on the surface of the foil. A burner test rig was built to produce hot combustion gases that flowed over exposed face of the heat exchanger. Cooling air flowed through the foam heat exchanger at rates of up to 200 SLPM. Surface temperature and air inlet/exit temperature were measured. Heat transfer to air flowing through the foam was significantly higher for the thermally sprayed heat exchangers than for the brazed heat exchangers. On an average, thermally sprayed heat exchangers show 36% higher heat transfer than conventionally brazed foam heat exchangers. At low flow rates, the convective resistance is large (~4 × 10-2 m2 K/W), and the effect of thermal contact resistance is negligible. At higher flow rates, the convective resistance decreases (~2 × 10-3 m2 K/W), and the lower contact resistance of the thermally sprayed heat exchanger provides better performance than the brazed heat exchangers.

  11. Dedicated low temperature nuclear district heating plants: Rationale and prospects

    International Nuclear Information System (INIS)

    Goetzmann, C.A.

    1997-01-01

    Space heating accounts for a substantial fraction of the end-energy consumption in a large number of industrialized countries. Accordingly, efforts have been under way since many years to utilize nuclear energy as a source for district heating. The paper describes the key technical and institutional issues affecting the implementation of such technology. It is argued that the basic case for nuclear district heating is sound but that its introduction merits and drawbacks strongly depend on local circumstances. (author). 4 figs, 1 tab

  12. Dedicated low temperature nuclear district heating plants: Rationale and prospects

    Energy Technology Data Exchange (ETDEWEB)

    Goetzmann, C A [Division of Nuclear Power, International Atomic Energy Agency, Vienna (Austria)

    1997-09-01

    Space heating accounts for a substantial fraction of the end-energy consumption in a large number of industrialized countries. Accordingly, efforts have been under way since many years to utilize nuclear energy as a source for district heating. The paper describes the key technical and institutional issues affecting the implementation of such technology. It is argued that the basic case for nuclear district heating is sound but that its introduction merits and drawbacks strongly depend on local circumstances. (author). 4 figs, 1 tab.

  13. Inverse heat transfer analysis of a functionally graded fin to estimate time-dependent base heat flux and temperature distributions

    International Nuclear Information System (INIS)

    Lee, Haw-Long; Chang, Win-Jin; Chen, Wen-Lih; Yang, Yu-Ching

    2012-01-01

    Highlights: ► Time-dependent base heat flux of a functionally graded fin is inversely estimated. ► An inverse algorithm based on the conjugate gradient method and the discrepancy principle is applied. ► The distributions of temperature in the fin are determined as well. ► The influence of measurement error and measurement location upon the precision of the estimated results is also investigated. - Abstract: In this study, an inverse algorithm based on the conjugate gradient method and the discrepancy principle is applied to estimate the unknown time-dependent base heat flux of a functionally graded fin from the knowledge of temperature measurements taken within the fin. Subsequently, the distributions of temperature in the fin can be determined as well. It is assumed that no prior information is available on the functional form of the unknown base heat flux; hence the procedure is classified as the function estimation in inverse calculation. The temperature data obtained from the direct problem are used to simulate the temperature measurements. The influence of measurement errors and measurement location upon the precision of the estimated results is also investigated. Results show that an excellent estimation on the time-dependent base heat flux and temperature distributions can be obtained for the test case considered in this study.

  14. Application of heat pump by using the earth temperature gradient for winter heating and summer cooling

    International Nuclear Information System (INIS)

    Gacevski, Marijan; Tanev, Pepi

    2003-01-01

    Because of the rapid technique development as well as modern human life, in order to satisfy the energy needs it is necessary to use a new apparatus and devices. In this manner, the electric power consumption, especially for heating and cooling, rapidly increases. One of the possible ways to reduce the consumption of electric energy for heating and cooling is that, to use heat pumps. In this paper a heat pump that uses the heat of the earth by a horizontal polyethylene pipe heat exchanger is proposed. Also, all parameters are examined and comparison with already existing ones is done. The heat gradient of the earth in spite of saving electrical energy is analyzed as well. (Original)

  15. Energy balance of droplets impinging onto a wall heated above the Leidenfrost temperature

    International Nuclear Information System (INIS)

    Dunand, P.; Castanet, G.; Gradeck, M.; Maillet, D.; Lemoine, F.

    2013-01-01

    Highlights: • Measurement techniques are combined to characterize the heat lost due to liquid vaporization. • The wall heat flux is estimated by infrared thermography associated with inverse heat conduction. • The liquid heating is characterized by the two-color Laser-Induced Fluorescence thermometry. • Results reveal how the heat fluxes vary with the droplet sizes and the Weber number. -- Abstract: This work is an experimental study aiming at characterizing the heat transfers induced by the impingement of water droplets (diameter 80–180 μm) on a thin nickel plate heated by electromagnetic induction. The temperature of the rear face of the nickel sample is measured by means of an infrared camera and the heat removed from the wall due to the presence of the droplets is estimated using a semi-analytical inverse heat conduction model. In parallel, the temperature of the droplets is measured using the two-color Laser-Induced Fluorescence thermometry (2cLIF) which has been extended to imagery for the purpose of these experiments. The measurements of the variation in the droplet temperature occurring during an impact allow determining the sensible heat removed by the liquid. Measurements are performed at wall conditions well above the Leidenfrost temperature. Different values of the Weber numbers corresponding to the bouncing and splashing regimes are tested. Comparisons between the heat flux removed from the wall and the sensible heat gained by the liquid allows estimating the heat flux related to liquid evaporation. Results reveal that the respective level of the droplet sensible heat and the heat lost due to liquid vaporization can vary significantly with the droplet sizes and the Weber number

  16. Recovery of low temperature heat in oil mills

    Directory of Open Access Journals (Sweden)

    Carré Patrick

    2012-11-01

    Full Text Available Energy consumption in oil mills is a major item of costs and a sensitive point in the production of biofuels. To improve their performance, industrials can recover lowtemperature heat thanks to a new technology of heat exchangers suitable for treating granular solid materials. Information about the energy requirements of the rapeseed crushing being not readily available, the article gives a detailed assessment of consumption items (per ton of seed: 263 MJ for preparation operations and 284 MJ for solvent extraction. These exchangers used as pre-conditioners saves about 55 MJ.t−1 of heat by use of steam condensates. We could go further in use of these devices on the one hand to recover heat from press cake and meal, and secondly to use recovered energy to dry and warm up the seeds before pre-pressing. In this configuration, the energy savings could reach 38% of current needs.

  17. Heat flow study at the Chinese Continental Scientific Drilling site: Borehole temperature, thermal conductivity, and radiogenic heat production

    Science.gov (United States)

    He, Lijuan; Hu, Shengbiao; Huang, Shaopeng; Yang, Wencai; Wang, Jiyang; Yuan, Yusong; Yang, Shuchun

    2008-02-01

    The Chinese Continental Scientific Drilling (CCSD) Project offers a unique opportunity for studying the thermal regime of the Dabie-Sulu ultrahigh-pressure metamorphic belt. In this paper, we report measurements of borehole temperature, thermal conductivity, and radiogenic heat production from the 5158 m deep main hole (CCSD MH). We have obtained six continuous temperature profiles from this borehole so far. The temperature logs show a transient mean thermal gradient that has increased from 24.38 to 25.28 K km-1 over a period of about 1.5 years. We measured thermal conductivities and radiogenic heat productions on more than 400 core samples from CCSD MH. The measured thermal conductivities range between 1.71 and 3.60 W m-1 K-1, and the radiogenic heat productions vary from 0.01 μW m-3 to over 5.0 μW m-3, with a mean value of 1.23 ± 0.82 μW m-3 for the upper 5-km layer of the crust. The heat productions in CCSD MH appear to be more rock-type than depth-dependent and, over the depth range of CCSD MH, do not fit the popular model of heat production decreasing exponentially with increasing depth. The measured heat flow decreases with depth from ˜75 mW m-2 near the surface to ˜66 mW m-2 at a depth of 4600 m. High heat flow anomalies occur at ˜1000 and ˜2300 m, and low anomalies occur at 3300-4000 m. A preliminary two-dimensional numerical model suggests that both radiogenic heat production and thermal refraction due to structural heterogeneity are at least partially responsible for the vertical variation of heat flow in CCSD MH.

  18. Direct conversion of infrared radiant energy for space power applications

    Science.gov (United States)

    Finke, R. C.

    1982-01-01

    A proposed technology to convert the earth radiant energy (infrared albedo) for spacecraft power is presented. The resultant system would eliminate energy storage requirements and simplify the spacecraft design. The design and performance of a infrared rectenna is discussed.

  19. Evaluations of different domestic hot water preparing methods with ultra-low-temperature district heating

    DEFF Research Database (Denmark)

    Yang, Xiaochen; Li, Hongwei; Svendsen, Svend

    2016-01-01

    of Legionella in the DHW (domestic hot water) and assure the comfortable temperature, all substations were installed with supplementary heating devices. Detailed measurements were taken in the substations, including the electricity demand of the supplementary heating devices. To compare the energy and economic......This study investigated the performances of five different substation configurations in single-family houses supplied with ULTDH (ultra-low-temperature district heating). The temperature at the heat plant is 46 degrees C and around 40 degrees C at the substations. To avoid the proliferation...... performance of the substations, separate models were built based on standard assumptions. The relative heat and electricity delivered for preparing DHW were calculated. The results showed that substations with storage tanks and heat pumps have high relative electricity demand, which leads to higher integrated...

  20. Effect of Heat Flux on the Specimen Temperature of an LBE Capsule

    International Nuclear Information System (INIS)

    Kang, Y. H.; Park, S. J.; Cho, M. S.; Choo, K. N.; Lee, Y. S.

    2011-01-01

    For application of high-temperature irradiation tests in the HANARO reactor for Gen IV reactor material development, a number of newly designed LBE capsules have been investigated at KAERI since 2008. Recent study on heat transfer experiment of an LBE capsule with a single heater has shown that the specimen temperature of the mock-up increased linearly with an increase of heat input. The work highlighted only the heat transfer capability of an LBE capsule with a single heater as a simulated specimen in a liquid metal medium. Hence, a new LBE capsule with multi specimen sets has been designed and fabricated for the heat transfer experiment of an LBE capsule of 11M-01K. In this paper, a series of thermal analyses and heat transfer experiments for a newly designed LBE capsule was implemented to study the effect of an increase in the value of heat input and its influence on temperature distribution in the capsule mock-up

  1. Basic thermo-fluid dynamic problems in high temperature heat exchangers

    International Nuclear Information System (INIS)

    McEligot, D.M.

    1986-01-01

    The authors consider high temperature heat exchangers to be ones where the heat transfer coefficients cannot be predicted confidently by classical analyses for pure forced convection with constant fluid properties. Alternatively, one could consider heat exchangers operating above some arbitrary temperature, say 1000F or 600C perhaps, to be at high temperature conditions. In that case, most common working fluids will be superheated vapors or gases. While some liquid metal heat exchangers are designed to operate in this range, the heat transfer coefficients of liquid metals are usually sufficiently high that the dominant thermal resistance would be due to the second fluid. This paper concentrates on convective heat transfer with gases. Typical applications include modular gas cooled nuclear reactors, proposed nuclear propulsion systems and space power plants, and superheaters in Rankine steam cycles

  2. Heat and fuel coupled operation of a high temperature polymer electrolyte fuel cell with a heat exchanger methanol steam reformer

    Science.gov (United States)

    Schuller, G.; Vázquez, F. Vidal; Waiblinger, W.; Auvinen, S.; Ribeirinha, P.

    2017-04-01

    In this work a methanol steam reforming (MSR) reactor has been operated thermally coupled to a high temperature polymer electrolyte fuel cell stack (HT-PEMFC) utilizing its waste heat. The operating temperature of the coupled system was 180 °C which is significantly lower than the conventional operating temperature of the MSR process which is around 250 °C. A newly designed heat exchanger reformer has been developed by VTT (Technical Research Center of Finland LTD) and was equipped with commercially available CuO/ZnO/Al2O3 (BASF RP-60) catalyst. The liquid cooled, 165 cm2, 12-cell stack used for the measurements was supplied by Serenergy A/S. The off-heat from the electrochemical fuel cell reaction was transferred to the reforming reactor using triethylene glycol (TEG) as heat transfer fluid. The system was operated up to 0.4 A cm-2 generating an electrical power output of 427 Wel. A total stack waste heat utilization of 86.4% was achieved. It has been shown that it is possible to transfer sufficient heat from the fuel cell stack to the liquid circuit in order to provide the needed amount for vaporizing and reforming of the methanol-water-mixture. Furthermore a set of recommendations is given for future system design considerations.

  3. Analysis of temperature glide matching of heat pumps with zeotropic working fluid mixtures for different temperature glides

    DEFF Research Database (Denmark)

    Zühlsdorf, Benjamin; Jensen, Jonas Kjær; Cignitti, Stefano

    2018-01-01

    refrigerants. This approach enables a match of the temperature glide of sink and source with the temperature of the working fluid during phase change and thus, a reduction of the exergy destruction due to heat transfer. The model was evaluated for four different boundary conditions. The exergy destruction due...

  4. The Integration Of Process Heat Applications To High Temperature Gas Reactors

    International Nuclear Information System (INIS)

    McKellar, Michael G.

    2011-01-01

    A high temperature gas reactor, HTGR, can produce industrial process steam, high-temperature heat-transfer gases, and/or electricity. In conventional industrial processes, these products are generated by the combustion of fossil fuels such as coal and natural gas, resulting in significant emissions of greenhouse gases such as carbon dioxide. Heat or electricity produced in an HTGR could be used to supply process heat or electricity to conventional processes without generating any greenhouse gases. Process heat from a reactor needs to be transported by a gas to the industrial process. Two such gases were considered in this study: helium and steam. For this analysis, it was assumed that steam was delivered at 17 MPa and 540 C and helium was delivered at 7 MPa and at a variety of temperatures. The temperature of the gas returning from the industrial process and going to the HTGR must be within certain temperature ranges to maintain the correct reactor inlet temperature for a particular reactor outlet temperature. The returning gas may be below the reactor inlet temperature, ROT, but not above. The optimal return temperature produces the maximum process heat gas flow rate. For steam, the delivered pressure sets an optimal reactor outlet temperature based on the condensation temperature of the steam. ROTs greater than 769.7 C produce no additional advantage for the production of steam.

  5. Modelling temperature dynamics of a district heating system in Naestved, Denmark-A case study

    International Nuclear Information System (INIS)

    Gabrielaitiene, Irina; Bohm, Benny; Sunden, Bengt

    2007-01-01

    Modelling the temperature dynamics of a district heating system is typically validated for a single pipe or a system with limited information about dynamic consumer behaviour. In the present work, time dependent consumer data from the Naestved district heating system was used to investigate the ability of modelling tools to represent the temperature profile distortion throughout an entire heating system network. The Naestved district heating subsystem was modelled by two approaches (the node method developed at the Technical University of Denmark and the software TERMIS), and these modelling results were compared with measured data. The results indicate that the discrepancies between the predicted and measured temperatures are pronounced for consumers located in pipelines at distant pipelines containing numerous bends and fittings. Additionally, it was found that representing the consumer behaviour on an annual average basis introduced a deviation between the predicted and the measured return temperatures at the heat source

  6. An assessment of high school students' conceptual structures of heat and temperature through concept maps

    Science.gov (United States)

    Aykutlu, Isil; Bezen, Sevim; Bayrak, Celal

    2017-02-01

    This study is a qualitative one conducted in order to determine 9th, 10th, and 11th grade high school students' conceptual structures of heat and temperature through concept maps. The study was realized with the participation of a total of 80 students. As data gathering tool, a concept map developed by the researchers, which includes such items as heat, temperature, and matter, was used. Students were asked to form a concept map by using the concepts in the form and the concepts they thought were related with these. Data obtained from the research was analyzed via content analysis. As a result of the study, it was determined that students have misconceptions and lack of knowledge of heat and temperature. Lastly, the following can be given as examples of students' misconceptions or lack of knowledge: they think temperature comes into being as a result of heat and that heat is a kind of energy.

  7. Computer calculation of heat capacity of natural gases over a wide range of pressure and temperature

    Energy Technology Data Exchange (ETDEWEB)

    Dranchuk, P.M. (Alberta Univ., Edmonton, AB (Canada)); Abou-Kassem, J.H. (Pennsylvania State Univ., University Park, PA (USA))

    1992-04-01

    A method is presented whereby specific heats or heat capacities of natural gases, both sweet and sour, at elevated pressures and temperatures may be made suitable to modern-day machine calculation. The method involves developing a correlation for ideal isobaric heat capacity as a function of gas gravity and pseudo reduced temperature over the temperature range of 300 to 1500 K, and a mathematical equation for the isobaric heat capacity departure based on accepted thermodynamic principles applied to an equation of state that adequately describes the behavior of gases to which the Standing and Katz Z factor correlation applies. The heat capacity departure equation is applicable over the range of 0.2 {le} Pr {le} 15 and 1.05 {le} Tr {le} 3, where Pr and Tr refer to the reduced pressure and temperature respectively. The significance of the method presented lies in its utility and adaptability to computer applications. 25 refs., 2 figs., 4 tabs.

  8. Modelling temperature-dependent heat production over decades in High Arctic coal waste rock piles

    DEFF Research Database (Denmark)

    Hollesen, Jørgen; Elberling, Bo; Jansson, P.E.

    2011-01-01

    Subsurface heat production from oxidation of pyrite is an important process that may increase subsurface temperatures within coal waste rock piles and increase the release of acid mine drainage, AMD. Waste rock piles in the Arctic are especially vulnerable to changes in subsurface temperatures...... such as heat production from coal oxidation may be equally important....... as the release of AMD normally is limited by permafrost. Here we show that temperatures within a 20 year old heat-producing waste rock pile in Svalbard (78°N) can be modelled by the one-dimensional heat and water flow model (CoupModel) with a new temperature-dependent heat-production module that includes both...

  9. Heat treated 9 Cr-1 Mo steel material for high temperature application

    Science.gov (United States)

    Jablonski, Paul D.; Alman, David; Dogan, Omer; Holcomb, Gordon; Cowen, Christopher

    2012-08-21

    The invention relates to a composition and heat treatment for a high-temperature, titanium alloyed, 9 Cr-1 Mo steel exhibiting improved creep strength and oxidation resistance at service temperatures up to 650.degree. C. The novel combination of composition and heat treatment produces a heat treated material containing both large primary titanium carbides and small secondary titanium carbides. The primary titanium carbides contribute to creep strength while the secondary titanium carbides act to maintain a higher level of chromium in the finished steel for increased oxidation resistance, and strengthen the steel by impeding the movement of dislocations through the crystal structure. The heat treated material provides improved performance at comparable cost to commonly used high-temperature steels such as ASTM P91 and ASTM P92, and requires heat treatment consisting solely of austenization, rapid cooling, tempering, and final cooling, avoiding the need for any hot-working in the austenite temperature range.

  10. Theoretical simulation of the dual-heat-flux method in deep body temperature measurements.

    Science.gov (United States)

    Huang, Ming; Chen, Wenxi

    2010-01-01

    Deep body temperature reveals individual physiological states, and is important in patient monitoring and chronobiological studies. An innovative dual-heat-flux method has been shown experimentally to be competitive with the conventional zero-heat-flow method in its performance, in terms of measurement accuracy and step response to changes in the deep temperature. We have utilized a finite element method to model and simulate the dynamic process of a dual-heat-flux probe in deep body temperature measurements to validate the fundamental principles of the dual-heat-flux method theoretically, and to acquire a detailed quantitative description of the thermal profile of the dual-heat-flux probe. The simulation results show that the estimated deep body temperature is influenced by the ambient temperature (linearly, at a maximum rate of 0.03 °C/°C) and the blood perfusion rate. The corresponding depth of the estimated temperature in the skin and subcutaneous tissue layer is consistent when using the dual-heat-flux probe. Insights in improving the performance of the dual-heat-flux method were discussed for further studies of dual-heat-flux probes, taking into account structural and geometric considerations.

  11. Thermal characteristics of high-temperature R718 heat pumps with turbo compressor thermal vapor recompression

    International Nuclear Information System (INIS)

    Šarevski, Milan N.; Šarevski, Vasko N.

    2017-01-01

    Highlights: • High pressure ratio, high speed, transonic R718 centrifugal compressors. • High efficient industrial evaporators/concentrators with turbo thermal vapor recompression. • Utilization of waste heat from industrial thermal and processing systems. • R718 is an ideal refrigerant for the novel high-temperature industrial heat pumps. • Application of single-stage R718 centrifugal compressors. - Abstract: Characteristics of R718 centrifugal compressors are analyzed and range of their applications in industrial high-temperature heat pumps, district heating systems and geothermal green house heating systems are estimated. Implementation of turbo compressor thermal vapor recompression in industrial evaporating/concentrating plants for waste heat utilization results in a high energy efficiency and in other technical, economical and environmental benefits. A novel concept of turbo compression R718 heat pumps is proposed and an assessment of their thermal characteristics is presented for utilization of waste heat from industrial thermal plants and systems (boilers, furnaces, various technological and metallurgical cooling processes, etc.), and for applications in district heating and geothermal green house heating systems. R718 is an ideal refrigerant for the novel high-temperature turbo compression industrial heat pumps. Direct evaporation and condensation are advantages of the proposed system which lead to higher COP, and to simplification of the plant and lower cost.

  12. Investigation of heat flux processes governing the increase of groundwater temperatures beneath cities

    Science.gov (United States)

    Bayer, P.; Menberg, K.; Zhu, K.; Blum, P.

    2012-12-01

    In the subsurface of many cities there are widespread and persistent thermal anomalies. These so-called subsurface urban heat islands (UHIs), which also stimulate warming of urban aquifers, are triggered by various processes. Possible heat sources are basements of buildings, leakage of sewage systems, buried district heating networks, re-injection of cooling water and solar irradiation on paved surfaces. In the current study, the reported groundwater temperatures in several Central European cities, such as Berlin, Cologne (Germany) and Zurich (Switzerland) are compared. Available data sets are supplemented by temperature measurements and depth profiles in observation wells. Trend analyses are conducted with time series of groundwater temperatures, and three-dimensional groundwater temperature maps are provided. In all investigated cities, pronounced positive temperature anomalies are present. The distribution of groundwater temperatures appears to be spatially and temporally highly variable. Apparently, the increased heat input into the urban subsurface is controlled by very local and site-specific parameters. In the long-run, the combination of various heat sources results in an extensive temperature increase. In many cases, the maximum temperature elevation is found close to the city center. Regional groundwater temperature differences between the city center and the rural background are up to 5 °C, with local hot spots of even more pronounced anomalies. Particular heat sources, like cooling water injections or case-specific underground constructions, can cause local temperatures > 20 °C in the subsurface. Examination of the long-term variations in isotherm maps shows that temperatures have increased by about 1 °C in the city, as well as in the rural background areas over the last decades. This increase could be reproduced with trend analysis of temperature data gathered from several groundwater wells. Comparison between groundwater and air temperatures in the

  13. Adolfo Bartoli and the problem of radiant heat

    DEFF Research Database (Denmark)

    Kragh, Helge; Carazza, Bruno

    1989-01-01

    development of black-body theory and light pressure research. This influence was mainly due to Boltzmann, who came to the Stefan-Boltzmann radiation law via a reworking of Bartoli's thought experiment. However, contrary to what is usually assumed, Bartoli was himself reluctant to admit the existence of light...

  14. Ten questions about radiant heating and cooling systems

    DEFF Research Database (Denmark)

    Rhee, Kyu-Nam; Olesen, Bjarne W.; Kim, Kwang Woo

    2017-01-01

    to extend the applicability of the RHC system are providing the continuous impetus for research on RHC systems. This paper summarizes the important issues involved in the research on RHC system, whereby ten questions and answers concerning the RHC system are discussed, which will help researchers to conduct...

  15. Heat source reconstruction from noisy temperature fields using an optimised derivative Gaussian filter

    Science.gov (United States)

    Delpueyo, D.; Balandraud, X.; Grédiac, M.

    2013-09-01

    The aim of this paper is to present a post-processing technique based on a derivative Gaussian filter to reconstruct heat source fields from temperature fields measured by infrared thermography. Heat sources can be deduced from temperature variations thanks to the heat diffusion equation. Filtering and differentiating are key-issues which are closely related here because the temperature fields which are processed are unavoidably noisy. We focus here only on the diffusion term because it is the most difficult term to estimate in the procedure, the reason being that it involves spatial second derivatives (a Laplacian for isotropic materials). This quantity can be reasonably estimated using a convolution of the temperature variation fields with second derivatives of a Gaussian function. The study is first based on synthetic temperature variation fields corrupted by added noise. The filter is optimised in order to reconstruct at best the heat source fields. The influence of both the dimension and the level of a localised heat source is discussed. Obtained results are also compared with another type of processing based on an averaging filter. The second part of this study presents an application to experimental temperature fields measured with an infrared camera on a thin plate in aluminium alloy. Heat sources are generated with an electric heating patch glued on the specimen surface. Heat source fields reconstructed from measured temperature fields are compared with the imposed heat sources. Obtained results illustrate the relevancy of the derivative Gaussian filter to reliably extract heat sources from noisy temperature fields for the experimental thermomechanics of materials.

  16. Ambient temperature and added heat wave effects on hospitalizations in California from 1999 to 2009.

    Science.gov (United States)

    Sherbakov, Toki; Malig, Brian; Guirguis, Kristen; Gershunov, Alexander; Basu, Rupa

    2018-01-01

    Investigators have examined how heat waves or incremental changes in temperature affect health outcomes, but few have examined both simultaneously. We utilized distributed lag nonlinear models (DLNM) to explore temperature associations and evaluate possible added heat wave effects on hospitalizations in 16 climate zones throughout California from May through October 1999-2009. We define heat waves as a period when daily mean temperatures were above the zone- and month-specific 95th percentile for at least two consecutive days. DLNMs were used to estimate climate zone-specific non-linear temperature and heat wave effects, which were then combined using random effects meta-analysis to produce an overall estimate for each. With higher temperatures, admissions for acute renal failure, appendicitis, dehydration, ischemic stroke, mental health, non-infectious enteritis, and primary diabetes were significantly increased, with added effects from heat waves observed for acute renal failure and dehydration. Higher temperatures also predicted statistically significant decreases in hypertension admissions, respiratory admissions, and respiratory diseases with secondary diagnoses of diabetes, though heat waves independently predicted an added increase in risk for both respiratory types. Our findings provide evidence that both heat wave and temperature exposures can exert effects independently. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Radiant-Heat Spray Calcination Studies; Calcination par Pulverisation et Chauffage Radiant; 0418 0421 0421 041b 0415 0414 041e 0412 0410 041d 0418 042f 041d 0410 041a 0410 041b 042c 0426 0418 041d 0410 0422 041e 0420 0410 0425 0424 041e 0420 0421 0423 041d 041e 0427 041d 041e 0413 041e 0422 0418 041f 0410 0421 041d 0410 0413 0420 0415 0412 0410 041d 0418 0415 041c 0422 0415 041f 041b 041e 0412 042b 041c 0418 0417 041b 0423 0427 0415 041d 0418 0415 041c ; Estudios de Calcinacion por Pulverizacion y Calentamiento Radiante

    Energy Technology Data Exchange (ETDEWEB)

    Allemann, R. T.; Moore, R. L.; Upson, U. L. [Hanford Laboratories General Electric Co., Richland, WA (United States)

    1963-02-15

    The radiant-heat spray calcination process for conversion of liquid wastes to solids is described and the design of a one-gallon-per-hour spray calcination unit coupled with a small melt pot, capable of being run separately as a pot calciner, is discussed. The units were designed to test the feasibility of the calcination process with actual Purex plant waste in terms of the process as a unit operation, off-gas treatment, fission-product behaviour, condensate and calcined waste characteristics. The entire system was made to fit into an available 7-1/2 ft x 15 ft x 15 ft tall, manipulator-equipped, shielded cell which is also described. Included in the design discussion are: the resistance heating of the spray calciner column, thermal insulation of the column, spray nozzle, method of nozzle replacement, induction heating of the melt pot, radioactivity scanner for the pot, off-gas processing system including condenser, scrubber and filters, off-gas sampling device, liquid sampling device, wash-down system, feed system, instrumentation and control methods. The experience gained in operating the calciners and associated equipment is discussed. Experimental results presented show the effectiveness of off-gas decontamination and behaviour of gross chemical constituents and some specific fission products. (author) [French] Les auteurs etudient le procede de calcination par pulverisation et chauffage radiant utilise pour transformer les dechets liquides en solides; ils decrivent notamment une installation de calcination par pulverisation (d'une capacite de 1 gallon par heure) accouplee a un petit creuset que l'on peut utiliser separement comme creuset de calcination. Cet ensemble- a ete concu pour etudier la possibilite de calciner des dechets reels resultant du traitement Purex, en tenant compte des facteurs suivants: operations dans un seul appareil, traitement des gaz d'echappement, comportement des produits de fission, caracteristiques du condense et des dechets

  18. Cooling load calculation by the radiant time series method - effect of solar radiation models

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Alexandre M.S. [Universidade Estadual de Maringa (UEM), PR (Brazil)], E-mail: amscosta@uem.br

    2010-07-01

    In this work was analyzed numerically the effect of three different models for solar radiation on the cooling load calculated by the radiant time series' method. The solar radiation models implemented were clear sky, isotropic sky and anisotropic sky. The radiant time series' method (RTS) was proposed by ASHRAE (2001) for replacing the classical methods of cooling load calculation, such as TETD/TA. The method is based on computing the effect of space thermal energy storage on the instantaneous cooling load. The computing is carried out by splitting the heat gain components in convective and radiant parts. Following the radiant part is transformed using time series, which coefficients are a function of the construction type and heat gain (solar or non-solar). The transformed result is added to the convective part, giving the instantaneous cooling load. The method was applied for investigate the influence for an example room. The location used was - 23 degree S and 51 degree W and the day was 21 of January, a typical summer day in the southern hemisphere. The room was composed of two vertical walls with windows exposed to outdoors with azimuth angles equals to west and east directions. The output of the different models of solar radiation for the two walls in terms of direct and diffuse components as well heat gains were investigated. It was verified that the clear sky exhibited the less conservative (higher values) for the direct component of solar radiation, with the opposite trend for the diffuse component. For the heat gain, the clear sky gives the higher values, three times higher for the peek hours than the other models. Both isotropic and anisotropic models predicted similar magnitude for the heat gain. The same behavior was also verified for the cooling load. The effect of room thermal inertia was decreasing the cooling load during the peak hours. On the other hand the higher thermal inertia values are the greater for the non peak hours. The effect

  19. Increasing the efficiency of heating systems by reducing the flue gas temperature below the dew point

    Energy Technology Data Exchange (ETDEWEB)

    Kremer, H.

    1981-06-01

    This paper deals with the fundamentals and technical possibilities of increasing the combustion efficiency of gas-fired heating units for domestic heating by cooling the flue gases below their water vapor saturation temperature. The improvement of the efficiency can be more than 15% in comparison even to modern warm water heating boilers. Important however is the availability of cooling fluids of sufficiently low temperatures which could be recirculated heating water, freshwater and air. Different possible applications of this method are discussed in detail.

  20. Design of the steam reformer for the HTR-10 high temperature process heat application

    International Nuclear Information System (INIS)

    Ju Huaiming; Xu Yuanhui; Jia Haijun

    2000-01-01

    The 10 MW High Temperature Reactor Test Module (HTR-10) is being constructed now and planned to be operational in 2000. One of the objectives is to develop the high temperature process heat application. The methane steam reformer is one of the key-facilities for the nuclear process heat application system. The paper describes the conceptual design of the HTR-10 Steam Reformer with He heating, and the design optimization computer code. It can be used to perform sensitivity analysis for parameters, and to improve the design. Principal parameters and construction features of the HTR-10 reformer heated by He are introduced. (author)

  1. Performance evaluation of thermophotovoltaic GaSb cell technology in high temperature waste heat

    Science.gov (United States)

    Utlu, Z.; Önal, B. S.

    2018-02-01

    In this study, waste heat was evaluated and examined by means of thermophotovoltaic systems with the application of energy production potential GaSb cells. The aim of our study is to examine GaSb cell technology at high temperature waste heat. The evaluation of the waste heat to be used in the system is designed to be used in the electricity, industry and iron and steel industry. Our work is research. Graphic analysis is done with Matlab program. The high temperature waste heat graphs applied on the GaSb cell are in the results section. Our study aims to provide a source for future studies.

  2. Examination of thermophotovoltaic GaSb cell technology in low and medium temperatures waste heat

    Science.gov (United States)

    Utlu, Z.; Önal, B. S.

    2018-02-01

    In this study, waste heat was evaluated and examined by means of thermophotovoltaic systems with the application of energy production potential GaSb cells. The aim of our study is to examine GaSb cell technology at low and medium temperature waste heat. The evaluation of the waste heat to be used in the system is designed to be used in the electricity, industry and iron and steel industry. Our work is research. Graphic analysis is done with Matlab program. The low and medium temperature waste heat graphs applied on the GaSb cell are in the results section. Our study aims to provide a source for future studies.

  3. The influence of heated or cooled seats on the acceptable ambient temperature range

    DEFF Research Database (Denmark)

    Zhang, Y.F.; Wyon, David Peter; Fang, Lei

    2007-01-01

    series, subjects were preconditioned to be too hot, while in other series they were preconditioned to be thermally neutral. They reported their thermal sensations, overall thermal acceptability and comfort on visual analogue scales at regular intervals. Instantaneous heat flow to the seat was measured...... continuously. At each ambient room temperature, the percentage dissatisfied was found to be a second-order polynomial function of local heat flow. Zero heat flow was preferred at an air temperature of 22 degrees C and the heat flow that minimized the percentage dissatisfied was found to be a single linear...

  4. Increased Heat Generation in Postcardiac Arrest Patients During Targeted Temperature Management Is Associated With Better Outcomes.

    Science.gov (United States)

    Uber, Amy J; Perman, Sarah M; Cocchi, Michael N; Patel, Parth V; Ganley, Sarah E; Portmann, Jocelyn M; Donnino, Michael W; Grossestreuer, Anne V

    2018-04-03

    Assess if amount of heat generated by postcardiac arrest patients to reach target temperature (Ttarget) during targeted temperature management is associated with outcomes by serving as a proxy for thermoregulatory ability, and whether it modifies the relationship between time to Ttarget and outcomes. Retrospective cohort study. Urban tertiary-care hospital. Successfully resuscitated targeted temperature management-treated adult postarrest patients between 2008 and 2015 with serial temperature data and Ttarget less than or equal to 34°C. None. Time to Ttarget was defined as time from targeted temperature management initiation to first recorded patient temperature less than or equal to 34°C. Patient heat generation ("heat units") was calculated as inverse of average water temperature × hours between initiation and Ttarget × 100. Primary outcome was neurologic status measured by Cerebral Performance Category score; secondary outcome was survival, both at hospital discharge. Univariate analyses were performed using Wilcoxon rank-sum tests; multivariate analyses used logistic regression. Of 203 patients included, those with Cerebral Performance Category score 3-5 generated less heat before reaching Ttarget (median, 8.1 heat units [interquartile range, 3.6-21.6 heat units] vs median, 20.0 heat units [interquartile range, 9.0-33.5 heat units]; p = 0.001) and reached Ttarget quicker (median, 2.3 hr [interquartile range, 1.5-4.0 hr] vs median, 3.6 hr [interquartile range, 2.0-5.0 hr]; p = 0.01) than patients with Cerebral Performance Category score 1-2. Nonsurvivors generated less heat than survivors (median, 8.1 heat units [interquartile range, 3.6-20.8 heat units] vs median, 19.0 heat units [interquartile range, 6.5-33.5 heat units]; p = 0.001) and reached Ttarget quicker (median, 2.2 hr [interquartile range, 1.5-3.8 hr] vs median, 3.6 hr [interquartile range, 2.0-5.0 hr]; p = 0.01). Controlling for average water temperature between initiation and Ttarget, the

  5. The effect of air velocity on heat stress at increased air temperature

    DEFF Research Database (Denmark)

    Bjerg, B.; Wang, Xiaoshuai; Zhang, Guoqiang

    Increased air velocity is a frequently used method to reduce heat stress of farm animals housed in warm conditions. The main reason why the method works is that higher air velocity increases the convective heat release from the animals. Convective heat release from the animals is strongly related...... to the temperature difference between the surfaces of animals and the surrounding air, and this temperature difference declines when the air temperature approaches the animal body temperature. Consequently it can it by expected that the effect of air velocity decreases at increased air temperature. The literature...... on farm animals in warm conditions includes several thermal indices which incorporate the effect of air velocities. But, surprisingly none of them predicts a decreased influence of air velocity when the air temperature approaches the animal body temperature. This study reviewed published investigations...

  6. Temperature distribution and heat radiation of patterned surfaces at short wavelengths

    Science.gov (United States)

    Emig, Thorsten

    2017-05-01

    We analyze the equilibrium spatial distribution of surface temperatures of patterned surfaces. The surface is exposed to a constant external heat flux and has a fixed internal temperature that is coupled to the outside heat fluxes by finite heat conductivity across the surface. It is assumed that the temperatures are sufficiently high so that the thermal wavelength (a few microns at room temperature) is short compared to all geometric length scales of the surface patterns. Hence the radiosity method can be employed. A recursive multiple scattering method is developed that enables rapid convergence to equilibrium temperatures. While the temperature distributions show distinct dependence on the detailed surface shapes (cuboids and cylinder are studied), we demonstrate robust universal relations between the mean and the standard deviation of the temperature distributions and quantities that characterize overall geometric features of the surface shape.

  7. Effect of External Pressure Drop on Loop Heat Pipe Operating Temperature

    Science.gov (United States)

    Jentung, Ku; Ottenstein, Laura; Rogers, Paul; Cheung, Kwok; Obenschain, Arthur F. (Technical Monitor)

    2002-01-01

    This paper discusses the effect of the pressure drop on the operating temperature in a loop heat pipe (LHP). Because the evaporator and the compensation chamber (CC) both contain two-phase fluid, a thermodynamic constraint exists between the temperature difference and the pressure drop for these two components. As the pressure drop increases, so will the temperature difference. The temperature difference in turn causes an increase of the heat leak from the evaporator to the CC, resulting in a higher CC temperature. Furthermore, the heat leak strongly depends on the vapor void fraction inside the evaporator core. Tests were conducted by installing a valve on the vapor line so as to vary the pressure drop, and by charging the LHP with various amounts of fluid. Test results verify that the LHP operating temperature increases with an increasing differential pressure, and the temperature increase is a strong function of the fluid inventory in the loop.

  8. Design considerations for CRBRP heat transport system piping operating at elevated temperatures

    International Nuclear Information System (INIS)

    Pollono, L.P.; Mello, R.M.

    1979-01-01

    The heat transport system sodium piping for the Clinch River Breeder Reactor Plant (CRBRP) within the reactor containment building must withstand high temperatures for long periods of time. Each phase of the mechanical design process of the piping system is influenced by elevated temperature considerations which include material thermal creep effects, ratchetting caused by rapid temperature transients and stress relaxation, and material degradation effects. The structural design philosophy taken to design the CRBRP piping operating in a high temperature environment is described. The resulting design of the heat transport system piping is presented along with a discussion of special features that resulted from the elevated temperature considerations

  9. Influence of heating temperature on bainite transformation proceeding in chromium-nickel-molybdenum steels

    International Nuclear Information System (INIS)

    Kaletin, Yu.M.; Kaletin, A.Yu.

    1983-01-01

    The purpose of the present paper is to investigate the effect of heating and cooling from austenization temperature on development of bainite transformation in 37KhN3MFA and 18Kh2N4MA structural alloyed steels. The metallographical analysis of specimens has revealed that first crystals of bainite under slow heating up to 770-790 deg C appear at the temperature of about 500 deg C and at 475 deg C there has been much bainite over the whole cross section of the specimen. It is revealed that an increase of heating temperature and cooling rate replace the starting point of bainite transformation upwards. The strongest displacement of the point Bsub(S) into hogh-temperature range takes place after heating steel with the initial bainite structure in intercritical temperature range

  10. Validity of Devices That Assess Body Temperature During Outdoor Exercise in the Heat

    OpenAIRE

    Casa, Douglas J; Becker, Shannon M; Ganio, Matthew S; Brown, Christopher M; Yeargin, Susan W; Roti, Melissa W; Siegler, Jason; Blowers, Julie A; Glaviano, Neal R; Huggins, Robert A; Armstrong, Lawrence E; Maresh, Carl M

    2007-01-01

    Context: Rectal temperature is recommended by the National Athletic Trainers' Association as the criterion standard for recognizing exertional heat stroke, but other body sites commonly are used to measure temperature. Few authors have assessed the validity of the thermometers that measure body temperature at these sites in athletic settings.

  11. Transient temperature variations during the self-heating of a plasma by thermonuclear reactions

    Energy Technology Data Exchange (ETDEWEB)

    Greyber, Howard D [University of California Radiation Laboratory, Livermore, CA (United States)

    1958-07-01

    The motivation for this work arose from an observation by Rosenbluth that in a different but related physical situation, the electron temperature) could exceed ion temperature, during transient heating. We have undertaken to trace the transient temperatures to be expected in an idealized physical situation that still bears some resemblance to what one envisions for the Controlled Thermonuclear Reactor.

  12. The Optimal Evaporation Temperature of Subcritical ORC Based on Second Law Efficiency for Waste Heat Recovery

    Directory of Open Access Journals (Sweden)

    Xiaoxiao Xu

    2012-03-01

    Full Text Available The subcritical Organic Rankine Cycle (ORC with 28 working fluids for waste heat recovery is discussed in this paper. The effects of the temperature of the waste heat, the critical temperature of working fluids and the pinch temperature difference in the evaporator on the optimal evaporation temperature (OET of the ORC have been investigated. The second law efficiency of the system is regarded as the objective function and the evaporation temperature is optimized by using the quadratic approximations method. The results show that the OET will appear for the temperature ranges investigated when the critical temperatures of working fluids are lower than the waste heat temperatures by 18 ± 5 K under the pinch temperature difference of 5 K in the evaporator. Additionally, the ORC always exhibits the OET when the pinch temperature difference in the evaporator is raised under the fixed waste heat temperature. The maximum second law efficiency will decrease with the increase of pinch temperature difference in the evaporator.

  13. Preliminary study on high temperature heat exchanger for nuclear steel making

    Energy Technology Data Exchange (ETDEWEB)

    Mori, Y [Tokyo Inst. of Tech. (Japan); Ikegami, H

    1975-03-01

    In the high temperature heat exchanger as well as the steam reformer, several technical problems should be solved before realizing a nuclear plant complex for iron and steel making. Research has been carried out on heat exchanger between helium and steam, hydrogen permeation through super alloys, hydrogen removal using a titanium sponge, and creep and carburization performance of super alloys. The primary coolant used is helium having a pressure of approximately 12 kg/cm/sup 2/G and a temperature of approximately 1100/sup 0/C measured at the inlet of the high temperature heat exchanger, i.e., the test section. Steam, hydrogen and carbon monoxide are used as secondary coolants.

  14. Applying the principles of thermoeconomics to the organic Rankine Cycle for low temperature waste heat recovery

    International Nuclear Information System (INIS)

    Xiao, F.; Lilun, Q.; Changsun, S.

    1989-01-01

    In this paper, thermoeconomic principle is used to study the selection of working fluids and the option of the cycle parameters in the organic Rankine cycle of low temperature waste heat recovery. The parameter ξ, the product of the ratio of waste heat recovery and real cycle thermal efficiency, is suggested as a unified thermodynamic criterion for the selection of the working fluids. The mathematical expressions are developed to determine the optimal boiling temperature and the optimal pin point temperature difference in the heat recovery exchanger by way of thermoeconomic principle

  15. Temperature anisotropy in a cyclotron resonance heated tokamak plasma and the generation of poloidal electric field

    International Nuclear Information System (INIS)

    Choe, W.; Ono, M.; Chang, C.S.

    1994-11-01

    The temperature anisotropy generated by cyclotron resonance heating of tokamak plasmas is calculated and the poloidal equilibrium electric field due to the anisotropy is studied. For the calculation of anisotropic temperatures, bounce-averaged Fokker-Planck equation with a bi-Maxwellian distribution function of heated particles is solved, assuming a moderate wave power and a constant quasilinear cyclotron resonance diffusion coefficient. The poloidal electrostatic potential variation is found to be proportional to the particle density and the degree of temperature anisotropy of warm species created by cyclotron resonance heating

  16. The potential to supply low temperature district heating to existing building area

    DEFF Research Database (Denmark)

    Li, Hongwei; Svendsen, Svend

    2013-01-01

    Low-temperature district heating (LTDH) has the advantages as reduced network heat loss, improved quality match between energy supply and energy demand, and increased utilization of low-grade waste heat and renewable energy. The LTDH represents the next generation district heating (DH) system...... to supply existing building areas which are characterized with high heating demand needs to be examined. In this paper, the DH network deliverable capacity to supply LTDH to an existing building area is studied based on building thermal performance and DH network hydraulic performance simulation....

  17. A mathematical model to predict the effect of heat recovery on the wastewater temperature in sewers.

    Science.gov (United States)

    Dürrenmatt, David J; Wanner, Oskar

    2014-01-01

    Raw wastewater contains considerable amounts of energy that can be recovered by means of a heat pump and a heat exchanger installed in the sewer. The technique is well established, and there are approximately 50 facilities in Switzerland, many of which have been successfully using this technique for years. The planning of new facilities requires predictions of the effect of heat recovery on the wastewater temperature in the sewer because altered wastewater temperatures may cause problems for the biological processes used in wastewater treatment plants and receiving waters. A mathematical model is presented that calculates the discharge in a sewer conduit and the spatial profiles and dynamics of the temperature in the wastewater, sewer headspace, pipe, and surrounding soil. The model was implemented in the simulation program TEMPEST and was used to evaluate measured time series of discharge and temperatures. It was found that the model adequately reproduces the measured data and that the temperature and thermal conductivity of the soil and the distance between the sewer pipe and undisturbed soil are the most sensitive model parameters. The temporary storage of heat in the pipe wall and the exchange of heat between wastewater and the pipe wall are the most important processes for heat transfer. The model can be used as a tool to determine the optimal site for heat recovery and the maximal amount of extractable heat. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Effect of foam on temperature prediction and heat recovery potential from biological wastewater treatment.

    Science.gov (United States)

    Corbala-Robles, L; Volcke, E I P; Samijn, A; Ronsse, F; Pieters, J G

    2016-05-15

    Heat is an important resource in wastewater treatment plants (WWTPs) which can be recovered. A prerequisite to determine the theoretical heat recovery potential is an accurate heat balance model for temperature prediction. The insulating effect of foam present on the basin surface and its influence on temperature prediction were assessed in this study. Experiments were carried out to characterize the foam layer and its insulating properties. A refined dynamic temperature prediction model, taking into account the effect of foam, was set up. Simulation studies for a WWTP treating highly concentrated (manure) wastewater revealed that the foam layer had a significant effect on temperature prediction (3.8 ± 0.7 K over the year) and thus on the theoretical heat recovery potential (30% reduction when foam is not considered). Seasonal effects on the individual heat losses and heat gains were assessed. Additionally, the effects of the critical basin temperature above which heat is recovered, foam thickness, surface evaporation rate reduction and the non-absorbed solar radiation on the theoretical heat recovery potential were evaluated. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Experimental Study on Compression/Absorption High-Temperature Hybrid Heat Pump with Natural Refrigerant Mixture

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ji Young; Park, Seong Ryong; Baik, Young Jin; Chang, Ki Chang; Ra, Ho Sang; Kim, Min Sung [Korea Institute of Energy Research, Daejeon (Korea, Republic of); Kim, Yong Chan [Korea University, Seoul (Korea, Republic of)

    2011-12-15

    This research concerns the development of a compression/absorption high-temperature hybrid heat pump that uses a natural refrigerant mixture. Heat pumps based on the compression/absorption cycle offer various advantages over conventional heat pumps based on the vapor compression cycle, such as large temperature glide, temperature lift, flexible operating range, and capacity control. In this study, a lab-scale prototype hybrid heat pump was constructed with a two-stage compressor, absorber, desorber, desuperheater, solution heat exchanger, solution pump, liquid/vapor separator, and rectifier as the main components. The hybrid heat pump system operated at 10-kW-class heating capacity producing hot water whose temperature was more than 90 .deg. C when the heat source and sink temperatures were 50 .deg. C. Experiments with various NH{sub 3}/H{sub 2}O mass fractions and compressor/pump circulation ratios were performed on the system. From the study, the system performance was optimized at a specific NH{sub 3} concentration.

  20. Evaluating infant core temperature response in a hot car using a heat balance model.

    Science.gov (United States)

    Grundstein, Andrew J; Duzinski, Sarah V; Dolinak, David; Null, Jan; Iyer, Sujit S

    2015-03-01

    Using a 1-year old male infant as the model subject, the objectives of this study were to measure increased body temperature of an infant inside an enclosed vehicle during the work day (8:00 am-4:00 pm) during four seasons and model the time to un-compensable heating, heat stroke [>40 °C (>104 °F)], and critical thermal maximum [>42 °C (>107.6 °F)]. A human heat balance model was used to simulate a child's physiological response to extreme heat exposure within an enclosed vehicle. Environmental variables were obtained from the nearest National Weather Service automated surface observing weather station and from an observational vehicular temperature study conducted in Austin, Texas in 2012. In all four seasons, despite differences in starting temperature and solar radiation, the model infant reached heat stroke and demise before 2:00 pm. Time to heat stroke and demise occurred most rapidly in summer, at intermediate durations in fall and spring, and most slowly in the winter. In August, the model infant reached un-compensable heat within 20 min, heat stroke within 105 min, and demise within 125 min. The average rate of heating from un-compensable heat to heat stroke was 1.7 °C/h (3.0 °F/h) and from heat stroke to demise was 4.8 °C/h (8.5 °F/h). Infants left in vehicles during the workday can reach hazardous thermal thresholds quickly even with mild environmental temperatures. These results provide a seasonal analogue of infant heat stroke time course. Further effort is required to create a universally available forensic tool to predict vehicular hyperthermia time course to demise.

  1. Temperature control of evaporators in automotive waste heat recovery systems

    NARCIS (Netherlands)

    Oom, M.E.E.; Feru, E.; de Jager, A.G.; de Lange, H.C.; Ouwerkerk, H.

    2017-01-01

    his paper presents a control strategy for the steam generation process in automotive waste heat recovery systems that are based on the subcritical Rankine cycle. The central question is how to regulate the flow of water into the evaporator such that dry steam is generated at its outlet, subject to

  2. 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.

  3. A heat conduction simulator to estimate lung temperature distribution during percutaneous transthoracic cryoablation for lung cancer

    International Nuclear Information System (INIS)

    Futami, Hikaru; Arai, Tsunenori; Yashiro, Hideki; Nakatsuka, Seishi; Kuribayashi, Sachio; Izumi, Youtaro; Tsukada, Norimasa; Kawamura, Masafumi

    2006-01-01

    To develop an evaluation method for the curative field when using X-ray CT imaging during percutaneous transthoracic cryoablation for lung cancer, we constructed a finite-element heat conduction simulator to estimate temperature distribution in the lung during cryo-treatment. We calculated temperature distribution using a simple two-dimensional finite element model, although the actual temperature distribution spreads in three dimensions. Temperature time-histories were measured within 10 minutes using experimental ex vivo and in vivo lung cryoablation conditions. We adjusted specific heat and thermal conductivity in the heat conduction calculation and compared them with measured temperature time-histories ex vivo. Adjusted lung specific heat was 3.7 J/ (g·deg C) for unfrozen lung and 1.8 J/ (g·deg C) for frozen lung. Adjusted lung thermal conductivity in our finite element model fitted proportionally to the exponential function of lung density. We considered the heat input by blood flow circulation and metabolic heat when we calculated the temperature time-histories during in vivo cryoablation of the lung. We assumed that the blood flow varies in inverse proportion to the change in blood viscosity up to the maximum blood flow predicted from cardiac output. Metabolic heat was set as heat generation in the calculation. The measured temperature time-histories of in vivo cryoablation were then estimated with an accuracy of ±3 deg C when calculated based on this assumption. Therefore, we successfully constructed a two-dimensional heat conduction simulator that is capable of estimating temperature distribution in the lung at the time of first freezing during cryoablation. (author)

  4. Simplified Building Thermal Model Used for Optimal Control of Radiant Cooling System

    Directory of Open Access Journals (Sweden)

    Lei He

    2016-01-01

    Full Text Available MPC has the ability to optimize the system operation parameters for energy conservation. Recently, it has been used in HVAC systems for saving energy, but there are very few applications in radiant cooling systems. To implement MPC in buildings with radiant terminals, the predictions of cooling load and thermal environment are indispensable. In this paper, a simplified thermal model is proposed for predicting cooling load and thermal environment in buildings with radiant floor. In this thermal model, the black-box model is introduced to derive the incident solar radiation, while the genetic algorithm is utilized to identify the parameters of the thermal model. In order to further validate this simplified thermal model, simulated results from TRNSYS are compared with those from this model and the deviation is evaluated based on coefficient of variation of root mean square (CV. The results show that the simplified model can predict the operative temperature with a CV lower than 1% and predict cooling loads with a CV lower than 10%. For the purpose of supervisory control in HVAC systems, this simplified RC thermal model has an acceptable accuracy and can be used for further MPC in buildings with radiation terminals.

  5. Improved spacers for high temperature gas-cooled heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Nordstroem, L A [Swiss Federal Institute for Reactor Research, Wuerenlingen (Switzerland)

    1984-07-01

    Experimental and analytical investigations in the field of heat exchanger thermohydraulics have been performed at EIR for many years, Basic studies have been carried out on heat transfer and pressure loss for tube bundles of different geometries and tube surfaces. As a part of this overall R+D programme for heat exchangers, investigations have been carried out on spacer pressure loss in bundles with longitudinal flow. An analytical spacer pressure loss model was developed which could handle different types of subchannel within the bundle. The model has been evaluated against experiments, using about 25 spacers of widely differing geometries. In a gas-cooled reactor it is important to keep the pressure loss over the primary circuit heat exchangers to a minimum. In exchangers with grid spacers these contribute a significant proportion of the overall bundle losses. For example, in the HHT Recuperator, with a shell-side pressure loss of 3.5 % of the inlet pressure, the spacers cause about one half of this loss. Reducing the loss to, say, 2.5 % results in an overall increase in plant efficiency by more than 1 % - a significant improvement Preliminary analysis identified 5 geometries in particular which were chosen for experimental evaluation as part of a joint project with the SULZER Company, to develop a low pressure-loss spacer for HHT heat exchangers (longitudinal counter-flow He/He and He/H{sub 2}O designs). The aim of the tests was to verify the low pressure-loss characteristics of these spacer grid types, as well as the quality of the results calculated by the computer code analytical model. The experimental and analytical results are compared in this report.

  6. Impact of heat stress on crop yield—on the importance of considering canopy temperature

    International Nuclear Information System (INIS)

    Siebert, Stefan; Ewert, Frank; Eyshi Rezaei, Ehsan; Kage, Henning; Graß, Rikard

    2014-01-01

    Increasing crop productivity while simultaneously reducing the environmental footprint of crop production is considered a major challenge for the coming decades. Even short episodes of heat stress can reduce crop yield considerably causing low resource use efficiency. Studies on the impact of heat stress on crop yields over larger regions generally rely on temperatures measured by standard weather stations at 2 m height. Canopy temperatures measured in this study in field plots of rye were up to 7 °C higher than air temperature measured at typical weather station height with the differences in temperatures controlled by soil moisture contents. Relationships between heat stress and grain number derived from controlled environment studies were only confirmed under field conditions when canopy temperature was used to calculate stress thermal time. By using hourly mean temperatures measured by 78 weather stations located across Germany for the period 1994–2009 it is estimated, that mean yield declines in wheat due to heat stress during flowering were 0.7% when temperatures are measured at 2 m height, but yield declines increase to 22% for temperatures measured at the ground. These results suggest that canopy temperature should be simulated or estimated to reduce uncertainty in assessing heat stress impacts on crop yield. (letter)

  7. Experimental demonstration of a tailored-width microchannel heat exchanger configuration for uniform wall temperature

    International Nuclear Information System (INIS)

    Riera, S; Barrau, J; Rosell, J I; Omri, M; Fréchette, L G

    2013-01-01

    In this work, an experimental study of a novel microfabricated heat sink configuration that tends to uniform the wall temperature, even with increasing flow temperature, is presented. The design consists of a series of microchannel sections with stepwise varying width. This scheme counteracts the flow temperature increase by reducing the local thermal resistance along the flow path. A test apparatus with uniform heat flux and distributed wall temperature measurements was developed for microchannel heat exchanger characterisation. The energy balance is checked and the temperature distribution is analysed for each test. The results show that the wall temperature decreases slightly along the flow path while the fluid temperature increases, highlighting the strong impact of this approach. For a flow rate of 16 ml/s, the mean thermal resistance of the heat sink is 2,35·10 −5 m 2 ·K/W which enhances the results compared to the millimeter scale channels nearly three-fold. For the same flow rate and a heat flux of 50 W/cm 2 , the temperature uniformity, expressed as the standard deviation of the wall temperature, is around 6 °C

  8. Modeling, Prediction, and Control of Heating Temperature for Tube Billet

    Directory of Open Access Journals (Sweden)

    Yachun Mao

    2015-01-01

    Full Text Available Annular furnaces have multivariate, nonlinear, large time lag, and cross coupling characteristics. The prediction and control of the exit temperature of a tube billet are important but difficult. We establish a prediction model for the final temperature of a tube billet through OS-ELM-DRPLS method. We address the complex production characteristics, integrate the advantages of PLS and ELM algorithms in establishing linear and nonlinear models, and consider model update and data lag. Based on the proposed model, we design a prediction control algorithm for tube billet temperature. The algorithm is validated using the practical production data of Baosteel Co., Ltd. Results show that the model achieves the precision required in industrial applications. The temperature of the tube billet can be controlled within the required temperature range through compensation control method.

  9. Technical assessment of electric heat boosters in low-temperature district heating based on combined heat and power analysis

    DEFF Research Database (Denmark)

    Cai, Hanmin; You, Shi; Wang, Jiawei

    2018-01-01

    This paper provides a technical assessment of electric heat boosters (EHBs) in low-energy districts. The analysis is based on a hypothetical district with 23 terraced single-family houses supplied by both a lowtemperature district heating (LTDH) network and a low-voltage network (LVN). Two case...

  10. Heat insulating structure for use in transporting and handling gas of high temperature and pressure

    International Nuclear Information System (INIS)

    Mathusima, T.; Sato, T.; Uenishi, A.

    1980-01-01

    A heat insulating structure is described that has a heat-resistant tube disposed in a tubular cylindrical body and defining a passage for a high temperature gas, a heat insulating material disposed between the tube and the tubular cylindrical body and adapted to prevent the heat possessed by the gas from being transmitted to the tubular cylindrical body, and a spring adapted to bias the heat insulating material toward the inner surface of the tubular cylindrical body, so as to prevent the formation of a bypass passage for the gas including the gap between the tubular cylindrical body and the heat insulating material. The heat insulating material consists of a plurality of fibrous heat insulating materials mainly consisting of bulky fibrous materials and a plurality of shaped fibrous heat insulating materials. These fibrous heat insulating materials and the shaped fibrous heat insulating materials are arranged alternatingly and independently in the axial direction. In each of the bulky fibrous heat insulating material, disposed is a spring for biasing the shaped fibrous heat insulating material in the axial direction

  11. Heat-flow and temperature control in Tian–Calvet microcalorimeters: toward higher detection limits

    International Nuclear Information System (INIS)

    Vilchiz-Bravo, L E; Pacheco-Vega, A; Handy, B E

    2010-01-01

    Strategies based on the principle of heat flow and temperature control were implemented, and experimentally tested, to increase the sensitivity of a Tian–Calvet microcalorimeter for measuring heats of adsorption. Here, both heat-flow and temperature control schemes were explored to diminish heater-induced thermal variations within the heat sink element, hence obtaining less noise in the baseline signal. PID controllers were implemented within a closed-loop system to perform the control actions in a calorimetric setup. The experimental results demonstrate that the heat flow control strategy provided a better baseline stability when compared to the temperature control. The effects on the results stemming from the type of power supply used were also investigated

  12. Book of presentations of the International Workshop on High Temperature Heat Pumps

    DEFF Research Database (Denmark)

    Modern society moves towards an electrifed energy system based on wind, solarand other renewable sources. Utilizing these sources effciently by heat pumps ishighly attractive and a significant potential for improving the energy system byextensive adaptation of heat pumping technology in all fields...... exists. However, challenges are present for heat pump technology. In particular for high temperature applications like industrial processes and to some extent district heating, heat pumps are not yet commercially available. In some countries the expansion already occurs, but other places the development...... is much more limited. Some obstacles relate to regulations and boundary conditions which may not be favorablefor heat pumps and electrification. But, the level of the technology willprobably also improve with regards to temperature limits, efficiency, capacity, and economy, and hence inherently become...

  13. Identifying the optimal supply temperature in district heating networks - A modelling approach

    DEFF Research Database (Denmark)

    Mohammadi, Soma; Bojesen, Carsten

    2014-01-01

    of this study is to develop a model for thermo-hydraulic calculation of low temperature DH system. The modelling is performed with emphasis on transient heat transfer in pipe networks. The pseudo-dynamic approach is adopted to model the District Heating Network [DHN] behaviour which estimates the temperature...... dynamically while the flow and pressure are calculated on the basis of steady state conditions. The implicit finite element method is applied to simulate the transient temperature behaviour in the network. Pipe network heat losses, pressure drop in the network and return temperature to the plant...... are calculated in the developed model. The model will serve eventually as a basis to find out the optimal supply temperature in an existing DHN in later work. The modelling results are used as decision support for existing DHN; proposing possible modifications to operate at optimal supply temperature....

  14. Comparison of Low-temperature District Heating Concepts in a Long-Term Energy System Perspective

    DEFF Research Database (Denmark)

    Lund, Rasmus Søgaard; Østergaard, Dorte Skaarup; Yang, Xiaochen

    2017-01-01

    renewable energy systems. This study compares three alternative concepts for DH temperature level: Low temperature (55/25 °C), Ultra-low temperature with electric boosting (45/25 °C), and Ultra-low temperature with heat pump boosting (35/20 °C) taking into account the grid losses, production efficiencies......District heating (DH) systems are important components in an energy efficient heat supply. With increasing amounts of renewable energy, the foundation for DH is changing and the approach to its planning will have to change. Reduced temperatures of DH are proposed as a solution to adapt it to future...... and building requirements. The scenarios are modelled and analysed in the analysis tool EnergyPLAN and compared on primary energy supply and socioeconomic costs. The results show that the low temperature solution (55/25°C) has the lowest costs, reducing the total costs by about 100 M€/year in 2050....

  15. Temperature fluctuation of sodium in annular flow channel heated by single-pin with blockage

    International Nuclear Information System (INIS)

    Miyazaki, Keiji; Kimura, Jiro; Ogawa, Masuro; Okada, Toshio

    1978-01-01

    Root mean square (RMS) value and power spectral density (PSD) of temperature fluctuation were measured with use of forced-circulating sodium in an annular channel (6.5 mm I.D., 20mm O.D.) with concentric disk to simulate blockage (about 80%) of sodium flow. The experimental range of the heat flux was 40 -- 150 W/cm 2 and the bulk flow velocity 0.14--0.41m/sec (Re=7.7x10 3 --2.3x10 4 ) under a temperature of 500--800 0 C. The RMS value measured at the exit of heating section (150mm downstream from the blockage) is larger by a factor of 2 -- 3 than that in the wake (10 -- 20mm downstream from the blockage), marking a few deg.C for a heat flux of 105W/cm 2 and a flow velocity of 0.27m/sec. The RMS value is proportional to the wall-to-bulk-fluid temperature difference in heat transfer, presenting the similar dependence on the heat flux and flow velocity. The fluctuations of temperature are greatly attenuated in the upper unheated section where the radial temperature gradient is absent, and consequently it is suggested that the fluctuations of temperature should be caused by the local turbulence of flow, such as a vortex street due to blockage in the present experiment, under the presence of large gradient of temperature near the heating surface. (auth.)

  16. Temperatures and heating energy in New Zealand houses from a nationally representative study - HEEP

    Energy Technology Data Exchange (ETDEWEB)

    French, L.J.; Camilleri, M.J.; Isaacs, N.P.; Pollard, A.R. [BRANZ Ltd., Private Bag 50 908, Porirua City (New Zealand)

    2007-07-15

    The household energy end-use project (HEEP) has collected energy and temperature data from a randomly selected, nationally representative sample of about 400 houses throughout New Zealand. This database has been used to explore the drivers of indoor temperatures and heating energy. Initial analysis of the winter living room temperatures shows that heating type, climate and house age are the key drivers. On average, houses heated by solid fuel are the warmest, with houses heated by portable LPG and electric heaters the coldest. Over the three winter months, living rooms are below 20 {sup o}C for 83% of the time - and the living room is typically the warmest room. Central heating is in only 5% of houses. Solid fuel is the dominant heating fuel in houses. The lack of air conditioning means that summer temperatures are affected by passive influences (e.g. house design, construction). Summer temperatures are strongly influenced by the house age and the local climate - together these variables explain 69% of the variation in daytime (9 a.m. to 5 p.m.) living room temperatures. In both summer and winter newer (post-1978) houses are warmer - this is beneficial in winter, but the high temperatures in summer are potentially uncomfortable. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-06-15

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

  18. Validation of the uncertainty budget for soft X-ray radiant power measurement using a cryogenic radiometer

    CERN Document Server

    Rabus, H; Scholze, F; Thornagel, R; Ulm, G

    2002-01-01

    The cryogenic radiometer SYRES, a thermal detector based on the electrical substitution principle, has been used as the primary detector standard for radiant power measurement in the ultraviolet, vacuum ultraviolet and soft X-ray spectral ranges. In order to investigate the possibility of radiant energy being deposited in its absorber cavity without being transformed into heat when detecting soft X-rays, SYRES has been directly compared with the electron storage ring BESSY 1, a primary radiometric source standard of calculable spectral radiant power. To this end, the integral radiant power emitted by the storage ring,into a solid angle defined by a high-precision aperture was measured with SYRES. The experiments were conducted at two nominal energies of the circulating electrons, 800 MeV and 340 MeV, to study the influence of the different spectral distributions of the synchrotron radiation. For the original graphite-coated cavity absorber, significant discrepancies were found which could be traced back to th...

  19. Effect of tunnel cross section on gas temperatures and heat fluxes in case of large heat release rate

    International Nuclear Information System (INIS)

    Fan, Chuan Gang; Li, Ying Zhen; Ingason, Haukur; Lönnermark, Anders

    2016-01-01

    Highlights: • The effect of tunnel cross section together with ventilation velocity was studied. • Ceiling temperature varies clearly with tunnel height, but little with tunnel width. • Downstream temperature decreases with increasing tunnel dimensions. • HRR is an important factor that influences decay rate of excess gas temperature. • An equation considering both tunnel dimensions and HRR was developed. - Abstract: Tests with liquid and solid fuels in model tunnels (1:20) were performed and analysed in order to study the effect of tunnel cross section (width and height) together with ventilation velocity on ceiling gas temperatures and heat fluxes. The model tunnel was 10 m long with varying width (0.3 m, 0.45 m and 0.6 m) and height (0.25 m and 0.4 m). Test results show that the maximum temperature under the ceiling is a weak function of heat release rate (HRR) and ventilation velocity for cases with HRR more than 100 MW at full scale. It clearly varies with the tunnel height and is a weak function of the tunnel width. With a lower tunnel height, the ceiling is closer to the base of continuous flame zone and the temperatures become higher. Overall, the gas temperature beneath the ceiling decreases with the increasing tunnel dimensions, and increases with the increasing longitudinal ventilation velocity. The HRR is also an important factor that influences the decay rate of excess gas temperature, and a dimensionless HRR integrating HRR and other two key parameters, tunnel cross-sectional area and distance between fuel centre and tunnel ceiling, was introduced to account for the effect. An equation for the decay rate of excess gas temperature, considering both the tunnel dimensions and HRR, was developed. Moreover, a larger tunnel cross-sectional area will lead to a smaller heat flux.

  20. A high temperature heating device for the study of fission product release from nuclear fuel

    International Nuclear Information System (INIS)

    Svedkauskaite-Le Gore, Jolanta; Kivel, Niko; Guenther-Leopold, Ines

    2010-01-01

    At the Paul Scherrer Institute a high temperature inductive heating furnace, which can heat fuel samples up to 2300 deg. C, has been developed in order to study the release of fission products. The furnace can be directly connected to an inductively coupled plasma mass spectrometer for online monitoring of the released elements and does not require their trapping before measurement. This paper describes the design of the inductive heating furnace, discusses its operating parameters, limitations and illustrates foreseen applications. (authors)