Pressure drop and friction factor correlations of supercritical flow

International Nuclear Information System (INIS)

Fang Xiande; Xu Yu; Su Xianghui; Shi Rongrong

2012-01-01

Highlights: ► Survey and evaluation of friction factor models for supercritical flow. ► Survey of experimental study of supercritical flow. ► New correlation of friction factor for supercritical flow. - Abstract: The determination of the in-tube friction pressure drop under supercritical conditions is important to the design, analysis and simulation of transcritical cycles of air conditioning and heat pump systems, nuclear reactor cooling systems and some other systems. A number of correlations for supercritical friction factors have been proposed. Their accuracy and applicability should be examined. This paper provides a comprehensive survey of experimental investigations into the pressure drop of supercritical flow in the past decade and a comparative study of supercritical friction factor correlations. Our analysis shows that none of the existing correlations is completely satisfactory, that there are contradictions between the existing experimental results and thus more elaborate experiments are needed, and that the tube roughness should be considered. A new friction factor correlation for supercritical tube flow is proposed based on 390 experimental data from the available literature, including 263 data of supercritical R410A cooling, 45 data of supercritical R404A cooling, 64 data of supercritical carbon dioxide (CO 2 ) cooling and 18 data of supercritical R22 heating. Compared with the best existing model, the new correlation increases the accuracy by more than 10%.

Phase behavior for the poly(alkyl methacrylate)+supercritical CO{sub 2}+DME mixture at high pressures

Energy Technology Data Exchange (ETDEWEB)

Choi, Yong-Seok; Chio, Sang-Won; Byun, Hun-Soo [Chonnam National University, Yeosu (Korea, Republic of)

2016-01-15

The phase behavior curves of binary and ternary system were measured for poly(alkyl methacrylate) in supercritical CO{sub 2}, as well as for the poly(alkyl methacrylate)+dimethyl ether (DME) (or 1-butene) in CO{sub 2}. The solubility curves are reported for the poly(alkyl methacrylate)+DME in supercritical CO{sub 2} at temperature from (300 to 465) K and a pressure from (3.66 to 248) MPa. Also, The high-pressure static-type apparatus of cloud-point curve was tested by comparing the measured phase behavior data of the poly(methyl methacrylate) [PMMA]+CO{sub 2}+20.0 and 30.4 wt% methyl methacrylate (MMA) system with literature data of 10.4, 28.8 and 48.4 wt% MMA concentration. The phase behavior data for the poly(alkyl methacrylate)+CO{sub 2}+DME mixture were measured in changes of the pressure-temperature (p, T) slope and with DME concentrations. Also, the cloud-point pressure for the poly(alkyl methacrylate)+1- butene solution containing supercritical CO{sub 2} shows from upper critical solution temperature (UCST) region to lower critical solution temperature (LCST) region at concentration range from (0.0 to 95) wt% 1-butene at below 455 K and at below 245MPa.

Heat transfer test in a vertical tube using CO2 at supercritical pressures

International Nuclear Information System (INIS)

Kim, Hwan Yeol; Kim, Hyungrae; Song, Jin Ho; Cho, Bong Hyun; Bae, Yoon Yeong

2007-01-01

Heat transfer test facility, SPHINX (Supercritical Pressure Heat Transfer Investigation for NeXt Generation), was constructed at KAERI (Korea Atomic Energy Research Institute) for an investigation of the thermal-hydraulic behaviors of supercritical CO 2 at the various geometries of the test section. The test data will be used for the reactor core design of the SCWR (SuperCritical Water-cooled Reactor). As a working fluid, CO 2 was selected to make use of the low critical pressure and temperature of CO 2 compared with water. An experimental study was carried out in the SPHINX to investigate the characteristics of heat transfer and pressure drop at a vertical single tube with an inside diameter of 4.4 mm in case of an upward flow of supercritical CO 2 . The heat and mass fluxes were varied at a given pressure. The mass flux was in the range of 400-1,200 kg/m 2 s and the heat flux was chosen up to 150 kW/m 2 . The selected pressures were 7.75, 8.12, and 8.85 MPa. A heat transfer deterioration occurred at the lower mass fluxes. The experimental heat transfer coefficients were compared with the ones predicted by several existing correlations. The standard deviation was about 20% for each correlation and an apparent discrepancy was not found among the correlations. The major components of the pressure drop were a gravitational pressure drop and a frictional pressure drop. The frictional pressure drop increases as the mass flux and heat flux increase. (author)

Direct numerical simulation of heat transfer to CO2 at supercritical pressure in a vertical tube

International Nuclear Information System (INIS)

Bae, Joong-Hun; Yoo, Jung-Yul; Choi, Hae-Cheon

2003-01-01

In the present study, the turbulent heat transfer to CO 2 at supercritical pressure in a vertical tube is investigated using Direct Numerical Simulation (DNS), where no turbulence model is adopted. Heat transfer to the supercritical pressure fluids is characterized by rapid variation of thermodynamic/ thermo-physical properties in the fluids. This change in properties occurs within a very narrow range of temperature across the so-called pseudo-critical temperature, causing a peculiar behavior of heat transfer characteristics. The buoyancy effects associated with very large changes in density proved to play a major role in turbulent heat transfer to supercritical pressure fluids. Depending on the degree of buoyancy effects, turbulent heat transfer may increase or significantly decrease, resulting in a local hot spot along the wall. Based on the results of the present DNS study combined with theoretical considerations for turbulent mixed convection heat transfer, the basic mechanism of this local heat transfer deterioration is explained

Investigation of forced convection heat transfer of supercritical pressure water in a vertically upward internally ribbed tube

International Nuclear Information System (INIS)

Wang Jianguo; Li Huixiong; Guo Bin; Yu Shuiqing; Zhang Yuqian; Chen Tingkuan

2009-01-01

In the present paper, the forced convection heat transfer characteristics of water in a vertically upward internally ribbed tube at supercritical pressures were investigated experimentally. The six-head internally ribbed tube is made of SA-213T12 steel with an outer diameter of 31.8 mm and a wall thickness of 6 mm and the mean inside diameter of the tube is measured to be 17.6 mm. The experimental parameters were as follows. The pressure at the inlet of the test section varied from 25.0 to 29.0 MPa, and the mass flux was from 800 to 1200 kg/(m 2 s), and the inside wall heat flux ranged from 260 to 660 kW/m 2 . According to experimental data, the effects of heat flux and pressure on heat transfer of supercritical pressure water in the vertically upward internally ribbed tube were analyzed, and the characteristics and mechanisms of heat transfer enhancement, and also that of heat transfer deterioration, were also discussed in the so-called large specific heat region. The drastic changes in thermophysical properties near the pseudocritical points, especially the sudden rise in the specific heat of water at supercritical pressures, may result in the occurrence of the heat transfer enhancement, while the covering of the heat transfer surface by fluids lighter and hotter than the bulk fluid makes the heat transfer deteriorated eventually and explains how this lighter fluid layer forms. It was found that the heat transfer characteristics of water at supercritical pressures were greatly different from the single-phase convection heat transfer at subcritical pressures. There are three heat transfer modes of water at supercritical pressures: (1) normal heat transfer, (2) deteriorated heat transfer with low HTC but high wall temperatures in comparison to the normal heat transfer, and (3) enhanced heat transfer with high HTC and low wall temperatures in comparison to the normal heat transfer. It was also found that the heat transfer deterioration at supercritical pressures was

Large Eddy Simulations of turbulent flows at supercritical pressure

Energy Technology Data Exchange (ETDEWEB)

Kunik, C.; Otic, I.; Schulenberg, T., E-mail: claus.kunik@kit.edu, E-mail: ivan.otic@kit.edu, E-mail: thomas.schulenberg@kit.edu [Karlsruhe Inst. of Tech. (KIT), Karlsruhe (Germany)

2011-07-01

A Large Eddy Simulation (LES) method is used to investigate turbulent heat transfer to CO{sub 2} at supercritical pressure for upward flows. At those pressure conditions the fluid undergoes strong variations of fluid properties in a certain temperature range, which can lead to a deterioration of heat transfer (DHT). In this analysis, the LES method is applied on turbulent forced convection conditions to investigate the influence of several subgrid scale models (SGS-model). At first, only velocity profiles of the so-called inflow generator are considered, whereas in the second part temperature profiles of the heated section are investigated in detail. The results are statistically analyzed and compared with DNS data from the literature. (author)

Investigation on heat transfer characteristics and flow performance of Methane at supercritical pressures

Science.gov (United States)

Xian, Hong Wei; Oumer, A. N.; Basrawi, F.; Mamat, Rizalman; Abdullah, A. A.

2018-04-01

The aim of this study is to investigate the heat transfer and flow characteristic of cryogenic methane in regenerative cooling system at supercritical pressures. The thermo-physical properties of supercritical methane were obtained from the National institute of Standards and Technology (NIST) webbook. The numerical model was developed based on the assumptions of steady, turbulent and Newtonian flow. For mesh independence test and model validation, the simulation results were compared with published experimental results. The effect of four different performance parameter ranges namely inlet pressure (5 to 8 MPa), inlet temperature (120 to 150 K), heat flux (2 to 5 MW/m2) and mass flux (7000 to 15000 kg/m2s) on heat transfer and flow performances were investigated. It was found that the simulation results showed good agreement with experimental data with maximum deviation of 10 % which indicates the validity of the developed model. At low inlet temperature, the change of specific heat capacity at near-wall region along the tube length was not significant while the pressure drop registered was high. However, significant variation was observed for the case of higher inlet temperature. It was also observed that the heat transfer performance and pressure drop penalty increased when the mass flux was increased. Regarding the effect of inlet pressure, the heat transfer performance and pressure drop results decreased when the inlet pressure is increased.

Supercritical Water Reactors

International Nuclear Information System (INIS)

Bouchter, J.C.; Dufour, P.; Guidez, J.; Latge, C.; Renault, C.; Rimpault, G.

2014-01-01

The supercritical water reactor (SCWR) is one of the 6 concepts selected for the 4. generation of nuclear reactors. SCWR is a new concept, it is an attempt to optimize boiling water reactors by using the main advantages of supercritical water: only liquid phase and a high calorific capacity. The SCWR requires very high temperatures (over 375 C degrees) and very high pressures (over 22.1 MPa) to operate which allows a high conversion yield (44% instead of 33% for a PWR). Low volumes of coolant are necessary which makes the neutron spectrum shift towards higher energies and it is then possible to consider fast reactors operating with supercritical water. The main drawbacks of supercritical water is the necessity to use very high pressures which has important constraints on the reactor design, its physical properties (density, calorific capacity) that vary strongly with temperatures and pressures and its very high corrosiveness. The feasibility of the concept is not yet assured in terms of adequate materials that resist to corrosion, reactor stability, reactor safety, and reactor behaviour in accidental situations. (A.C.)

Stability analysis of supercritical-pressure light water-cooled reactor in constant pressure operation

International Nuclear Information System (INIS)

Suhwan, JI; Shirahama, H.; Koshizuka, S.; Oka, Y.

2001-01-01

The purpose of this study is to evaluate the thermal-hydraulic and the thermal-nuclear coupled stabilities of a supercritical pressure light water-cooled reactor. A stability analysis code at supercritical pressure is developed. Using this code, stabilities of full and partial-power reactor operating at supercritical pressure are investigated by the frequency-domain analysis. Two types of SCRs are analyzed; a supercritical light water reactor (SCLWR) and a supercritical water-cooled fast reactor (SCFR). The same stability criteria as Boiling Water Reactor are applied. The thermal-hydraulic stability of SCLWR and SCFR satisfies the criteria with a reasonable orifice loss coefficient. The decay ratio of the thermal-nuclear coupled stability in SCFR is almost zero because of a small coolant density coefficient of the fast reactor. The evaluated decay ratio of the thermal-nuclear coupled stability is 3,41 ∼ 10 -V at 100% power in SCFR and 0,028 at 100% power in SCLWR. The sensitivity is investigated. It is found that the thermal-hydraulic stability is sensitive to the mass flow rate strongly and the thermal-nuclear coupled stability to the coolant density coefficient. The bottom power peak distribution makes the thermal-nuclear stability worse and the thermal-nuclear stability better. (author)

Effects of Nozzle Configuration on Rock Erosion Under a Supercritical Carbon Dioxide Jet at Various Pressures and Temperatures

Directory of Open Access Journals (Sweden)

Man Huang

2017-06-01

Full Text Available The supercritical carbon dioxide (SC-CO2 jet offers many advantages over water jets in the field of oil and gas exploration and development. To take better advantage of the SC-CO2 jet, effects of nozzle configuration on rock erosion characteristics were experimentally investigated with respect to the erosion volume. A convergent nozzle and two Laval nozzles, as well as artificial cores were employed in the experiments. It was found that the Laval nozzle can enhance rock erosion ability, which largely depends on the pressure and temperature conditions. The enhancement increases with rising inlet pressure. Compared with the convergent nozzle, the Laval-1 nozzle maximally enhances the erosion volume by 10%, 21.2% and 30.3% at inlet pressures of 30, 40 and 50 MPa, respectively; while the Laval-2 nozzle maximally increases the erosion volume by 32.5%, 49.2% and 60%. Moreover, the enhancement decreases with increasing ambient pressure under constant inlet pressure or constant pressure drop. The growth of fluid temperature above the critical value can increase the enhancement. In addition, the jet from the Laval-2 nozzle with a smooth inner profile always has a greater erosion ability than that from the Laval-1 nozzle.

Experimental investigation on flow patterns of RP-3 kerosene under sub-critical and supercritical pressures

Science.gov (United States)

Wang, Ning; Zhou, Jin; Pan, Yu; Wang, Hui

2014-02-01

Active cooling with endothermic hydrocarbon fuel is proved to be one of the most promising approaches to solve the thermal problem for hypersonic aircraft such as scramjet. The flow patterns of two-phase flow inside the cooling channels have a great influence on the heat transfer characteristics. In this study, phase transition processes of RP-3 kerosene flowing inside a square quartz-glass tube were experimentally investigated. Three distinct phase transition phenomena (liquid-gas two phase flow under sub-critical pressures, critical opalescence under critical pressure, and corrugation under supercritical pressures) were identified. The conventional flow patterns of liquid-gas two phase flow, namely bubble flow, slug flow, churn flow and annular flow are observed under sub-critical pressures. Dense bubble flow and dispersed flow are recognized when pressure is increased towards the critical pressure whilst slug flow, churn flow and annular flow disappear. Under critical pressure, the opalescence phenomenon is observed. Under supercritical pressures, no conventional phase transition characteristics, such as bubbles are observed. But some kind of corrugation appears when RP-3 transfers from liquid to supercritical. The refraction index variation caused by sharp density gradient near the critical temperature is thought to be responsible for this corrugation.

Heat transfer in vertical pipe flow at supercritical pressures of water

International Nuclear Information System (INIS)

Loewenberg, M.F.

2007-05-01

A new reactor concept with light water at supercritical conditions is investigated in the framework of the European project ''High Performance Light Water Reactor'' (HPLWR). Characteristics of this reactor are the system pressure and the coolant outlet temperature above the critical point of water. Water is regarded as a single phase fluid under these conditions with a high energy density. This high energy density should be utilized in a technical application. Therefore in comparison with up to date nuclear power plants some constructive savings are possible. For instance, steam dryers or steam separators can be avoided in contrast to boiling water reactors. A thermal efficiency of about 44% can be accomplished at a system pressure of 25MPa through a water heat-up from 280 C to 510 C. To ensure this heat-up within the core reliable predictions of the heat transfer are necessary. Water as the working fluid changes its fluid properties dramatically during the heat up in the core. As such; the density in the core varies by the factor of seven. The motivation to develop a look-up table for heat transfer predications in supercritical water is due to the significant temperature dependence of the fluid properties of water. A systematic consolidation of experimental data was performed. Together with further developments of the methods to derive a look-up table made it possible to develop a look-up table for heat transfer in supercritical water in vertical flows. A look-up table predicts the heat transfer for different boundary conditions (e.g. pressure or heat flux) with tabulated data. The tabulated wall temperatures for fully developed turbulent flows can be utilized for different geometries by applying hydraulic diameters. With the developed look-up table the difficulty of choosing one of the many published correlations can be avoided. In general, the correlations have problems with strong fluid property variations. Strong property variations combined with high heat

Supercritical transitiometry of polymers.

Science.gov (United States)

Randzio, S L; Grolier, J P

1998-06-01

Employing supercritical fluids (SCFs) during polymers processing allows the unusual properties of SCFs to be exploited for making polymer products that cannot be obtained by other means. A new supercritical transitiometer has been constructed to permit study of the interactions of SCFs with polymers during processing under well-defined conditions of temperature and pressure. The supercritical transitiometer allows pressure to be exerted by either a supercritical fluid or a neutral medium and enables simultaneous determination of four basic parameters of a transition, i.e., p, T, Δ(tr)H and Δ(tr)V. This permits determination of the SCF effect on modification of the polymer structure at a given pressure and temperature and defines conditions to allow reproducible preparation of new polymer structures. Study of a semicrystalline polyethylene by this method has defined conditions for preparation of new microfoamed phases with good mechanical properties. The low densities and microporous structures of the new materials may make them useful for applications in medicine, pharmacy, or the food industry, for example.

Measurements of convective heat transfer to vertical upward flows of CO{sub 2} in circular tubes at near-critical and supercritical pressures

Energy Technology Data Exchange (ETDEWEB)

Zahlan, H., E-mail: hussamzahlan@gmail.com [Canadian Nuclear Laboratories, Chalk River, K0J 1J0 (Canada); Department of Mechanical Engineering, University of Ottawa, Ottawa, ON K1N 6N5 (Canada); Groeneveld, D. [Canadian Nuclear Laboratories, Chalk River, K0J 1J0 (Canada); Department of Mechanical Engineering, University of Ottawa, Ottawa, ON K1N 6N5 (Canada); Tavoularis, S. [Department of Mechanical Engineering, University of Ottawa, Ottawa, ON K1N 6N5 (Canada)

2015-08-15

downstream sections of the tubes. The collected data were reduced and compiled. The reported heat transfer database consists of more than 17,000 data points in the 8 and 22 mm tubes, along with pressure drop data for the 8 mm tube. The tables of heat transfer and pressure drop data are provided as separate files in electronic format. The results are presented in plots of wall temperature and heat transfer coefficient vs. bulk fluid enthalpy. The parametric trends of diameter, mass flux, pressure and heat flux on these wall temperature and heat transfer coefficient profiles have been plotted and discussed. The present supercritical heat transfer measurements are in good agreement with corresponding results reported by other investigators.

Safety analysis of a high temperature supercritical pressure light water cooled and moderated reactor

International Nuclear Information System (INIS)

Ishiwatari, Y.; Oka, Y.; Koshizuka, S.

2002-01-01

A safety analysis code for a high temperature supercritical pressure light water cooled reactor (SCLWR-H) with water rods cooled by descending flow, SPRAT-DOWN, is developed. The hottest channel, a water rod, down comer, upper and lower plenums, feed pumps, etc. are modeled as junction of nodes. Partial of the feed water flows downward from the upper dome of the reactor pressure vessel to the water rods. The accidents analyzed here are total loss of feed water flow, feed water pump seizure, and control rods ejection. All the accidents satisfy the criteria. The accident event at which the maximum cladding temperature is the highest is total loss of feedwater flow. The transients analyzed here are loss of feed water heating, inadvertent start-up of an auxiliary water supply system, partial loss of feed water flow, loss of offsite power, loss of load, and abnormal withdrawal of control rods. All the transients satisfied the criteria. The transient event for which the maximum cladding temperature is the highest is control rod withdrawal at normal operation. The behavior of loss of load transient is different from that of BWR. The power does not increase because loss of flow occurs and the density change is small. The sensitivities of the system behavior to various parameters during transients and accidents are analyzed. The parameters having strong influence are the capacity of the auxiliary water supply system, the coast down time of the main feed water pumps, and the time delay of the main feed water pumps trip. The control rod reactivity also has strong influence. (authors)

Advanced Thermal Storage for Central Receivers with Supercritical Coolants

Energy Technology Data Exchange (ETDEWEB)

Kelly, Bruce D.

2010-06-15

The principal objective of the study is to determine if supercritical heat transport fluids in a central receiver power plant, in combination with ceramic thermocline storage systems, offer a reduction in levelized energy cost over a baseline nitrate salt concept. The baseline concept uses a nitrate salt receiver, two-tank (hot and cold) nitrate salt thermal storage, and a subcritical Rankine cycle. A total of 6 plant designs were analyzed, as follows: Plant Designation Receiver Fluid Thermal Storage Rankine Cycle Subcritical nitrate salt Nitrate salt Two tank nitrate salt Subcritical Supercritical nitrate salt Nitrate salt Two tank nitrate salt Supercritical Low temperature H2O Supercritical H2O Two tank nitrate salt Supercritical High temperature H2O Supercritical H2O Packed bed thermocline Supercritical Low temperature CO2 Supercritical CO2 Two tank nitrate salt Supercritical High temperature CO2 Supercritical CO2 Packed bed thermocline Supercritical Several conclusions have been drawn from the results of the study, as follows: 1) The use of supercritical H2O as the heat transport fluid in a packed bed thermocline is likely not a practical approach. The specific heat of the fluid is a strong function of the temperatures at values near 400 °C, and the temperature profile in the bed during a charging cycle is markedly different than the profile during a discharging cycle. 2) The use of supercritical CO2 as the heat transport fluid in a packed bed thermocline is judged to be technically feasible. Nonetheless, the high operating pressures for the supercritical fluid require the use of pressure vessels to contain the storage inventory. The unit cost of the two-tank nitrate salt system is approximately $24/kWht, while the unit cost of the high pressure thermocline system is nominally 10 times as high. 3) For the supercritical fluids, the outer crown temperatures of the receiver tubes are in the range of 700 to 800 °C. At temperatures of 700 °C and above

Supercritical water gasification with decoupled pressure and heat transfer modules

KAUST Repository

Dibble, Robert

2017-09-14

The present invention discloses a system and method for supercritical water gasification (SCWG) of biomass materials wherein the system includes a SCWG reactor and a plurality of heat exchangers located within a shared pressurized vessel, which decouples the function of containing high pressure from the high temperature function. The present invention allows the heat transfer function to be conducted independently from the pressure transfer function such that the system equipment can be designed and fabricated in manner that would support commercial scaled-up SCWG operations. By using heat exchangers coupled to the reactor in a series configuration, significant efficiencies are achieved by the present invention SCWG system over prior known SCWG systems.

Effect of supercritical fluid density on nanoencapsulated drug particle size using the supercritical antisolvent method.

Science.gov (United States)

Kalani, Mahshid; Yunus, Robiah

2012-01-01

The reported work demonstrates and discusses the effect of supercritical fluid density (pressure and temperature of supercritical fluid carbon dioxide) on particle size and distribution using the supercritical antisolvent (SAS) method in the purpose of drug encapsulation. In this study, paracetamol was encapsulated inside L-polylactic acid, a semicrystalline polymer, with different process parameters, including pressure and temperature, using the SAS process. The morphology and particle size of the prepared nanoparticles were determined by scanning electron microscopy and transmission electron microscopy. The results revealed that increasing temperature enhanced mean particle size due to the plasticizing effect. Furthermore, increasing pressure enhanced molecular interaction and solubility; thus, particle size was reduced. Transmission electron microscopy images defined the internal structure of nanoparticles. Thermal characteristics of nanoparticles were also investigated via differential scanning calorimetry. Furthermore, X-ray diffraction pattern revealed the changes in crystallinity structure during the SAS process. In vitro drug release analysis determined the sustained release of paracetamol in over 4 weeks.

Turbulent convective heat transfer of methane at supercritical pressure in a helical coiled tube

Science.gov (United States)

Wang, Chenggang; Sun, Baokun; Lin, Wei; He, Fan; You, Yingqiang; Yu, Jiuyang

2018-02-01

The heat transfer of methane at supercritical pressure in a helically coiled tube was numerically investigated using the Reynolds Stress Model under constant wall temperature. The effects of mass flux ( G), inlet pressure ( P in) and buoyancy force on the heat transfer behaviors were discussed in detail. Results show that the light fluid with higher temperature appears near the inner wall of the helically coiled tube. When the bulk temperature is less than or approach to the pseudocritical temperature ( T pc ), the combined effects of buoyancy force and centrifugal force make heavy fluid with lower temperature appear near the outer-right of the helically coiled tube. Beyond the T pc , the heavy fluid with lower temperature moves from the outer-right region to the outer region owing to the centrifugal force. The buoyancy force caused by density variation, which can be characterized by Gr/ Re 2 and Gr/ Re 2.7, enhances the heat transfer coefficient ( h) when the bulk temperature is less than or near the T pc , and the h experiences oscillation due to the buoyancy force. The oscillation is reduced progressively with the increase of G. Moreover, h reaches its peak value near the T pc . Higher G could improve the heat transfer performance in the whole temperature range. The peak value of h depends on P in. A new correlation was proposed for methane at supercritical pressure convective heat transfer in the helical tube, which shows a good agreement with the present simulated results.

Design of experimental system for supercritical CO2 fracturing under confining pressure conditions

Science.gov (United States)

Wang, H.; Lu, Q.; Li, X.; Yang, B.; Zheng, Y.; Shi, L.; Shi, X.

2018-03-01

Supercritical CO2 has the characteristics of low viscosity, high diffusion and zero surface tension, and it is considered as a new fluid for non-polluting and non-aqueous fracturing which can be used for shale gas development. Fracturing refers to a method of utilizing the high-pressure fluid to generate fractures in the rock formation so as to improve the oil and gas flow conditions and increase the oil and gas production. In this article, a new type of experimental system for supercritical CO2 fracturing under confining pressure conditions is designed, which is based on characteristics of supercritical CO2, shale reservoir and down-hole environment. The experimental system consists of three sub-systems, including supercritical CO2 generation system, supercritical CO2 fracturing system and data analysis system. It can be used to simulate supercritical CO2 fracturing under geo-stress conditions, thus to study the rock initiation pressure, the formation of the rock fractures, fractured surface morphology and so on. The experimental system has successfully carried out a series of supercritical CO2 fracturing experiments. The experimental results confirm the feasibility of the experimental system and the high efficiency of supercritical CO2 in fracturing tight rocks.

Heat Transfer Characteristics for an Upward Flowing Supercritical Pressure CO{sub 2} in a Vertical Circular Tube

Energy Technology Data Exchange (ETDEWEB)

Kang, Deog Ji

2008-02-15

The SCWR(Super Critical Water-cooled Reactor) is one of the feasible options for the 4th generation nuclear power plant, which is being pursued by an international collaborative organization, the Gen IV International Forum(GIF). The major advantages of the SCWR include a high thermal efficiency and a maximum use of the existing technologies. In the SCWR, the coolant(water) of a supercritical pressure passes the pseudo-critical temperature as it flows upward through the sub-channels of the fuel assemblies. At certain conditions a heat transfer deterioration occurs near the pseudo-critical temperature and it may cause an excessive rise of the fuel surface temperature. Therefore, an accurate estimation of the heat transfer coefficient is necessary for the thermal-hydraulic design of the reactor core. A test facility, SPHINX(Supercritical Pressure Heat Transfer Investigation for the Next Generation), dedicated to produce heat transfer data and study flow characteristics, uses supercritical pressure CO{sub 2} as a surrogate medium to take advantage of the relatively low critical temperature and pressure: and similar physical properties with water. The produced data includes the temperature of the heating surface and the heat transfer coefficient at varying mass fluxes, heat fluxes, and operating pressures. The test section is a circular tube of ID 6.32 mm: it is almost the same as the hydraulic diameter of the sub-channel in the conceptional design presented by KAERI. The test range of the mass flux is 285 to 1200 kg/m{sup 2}s and the maximum heat flux is 170 kW/m{sup 2}. The tests were mainly performed for an inlet pressure of 8.12 MPa which is 1.1 times of critical pressure. With the test results of the wall temperature and the heat transfer coefficient, effects of mass flux, heat flux, inlet pressure, and the tube diameter on the heat transfer were studied. And the test results were compared with the existing correlations of the Nusselt number. In addition, New

Experimental study on the minimum drag coefficient of supercritical pressure water in horizontal tubes

International Nuclear Information System (INIS)

Lei, Xianliang; Li, Huixiong; Guo, YuMeng; Zhang, Qing; Zhang, Weiqiang; Zhang, Qian

2016-01-01

Highlights: • The minimum drag coefficient phenomenon (MDC) has been observed and further investigated. • Effects of heat flux, mass flux and pressure to MDC have been discussed. • A series of comparisons between existing correlations and data have been conducted. • Two correlations of drag coefficient are proposed for isothermal and nonisothermal flow. - Abstract: Hydraulic resistance and its components are of great importance for understanding the turbulence nature of supercritical fluid and establishing prediction methods. Under supercritical pressures, the hydraulic resistance of the fluid exhibits a “pit” in the regions near its pseudo-critical point, which is hereafter called the minimum drag coefficient phenomenon. However, this special phenomenon was paid a little attention before. Hence systematical experiments have been carried out to investigate the hydraulic resistance of supercritical pressure water in both adiabatic and heated horizontal tubes. Parametric effects of heat flux, pressure and mass fluxes to drag coefficient are further compared. It is found that almost all of the existing correlations don’t agree well with the experimental data due to the insufficient consideration of thermal-properties near the pseudocritical point. Two correlations of the drag coefficients are finally proposed by introducing the new variable of the derivative of density with respect to temperature or Prandtl number, which can better predict the drag coefficient of isothermal and nonisothermal flow respectively.

Development of a test facility for analyzing supercritical fluid blowdown

International Nuclear Information System (INIS)

Roberto, Thiago D.; Alvim, Antonio C.M.

2015-01-01

The generation IV nuclear reactors under development mostly use supercritical fluids as the working fluid because higher temperatures improve the thermal efficiency. Supercritical fluids are used by modern nuclear power plants to achieve thermal efficiencies of around 45%. With water as the supercritical working fluid, these plants operate at a high temperature and pressure. However, experiments on supercritical water are limited by technical and financial difficulties. These difficulties can be overcome by using model fluids, which have more feasible supercritical conditions and exhibit a lower critical pressure and temperature. Experimental research is normally used to determine the conditions under which model fluids represent supercritical fluids under steady-state conditions. A fluid-to-fluid scaling approach has been proposed to determine model fluids that can represent supercritical fluids in a transient state. This paper presents an application of fractional scale analysis to determine the simulation parameters for a depressurization test facility. Carbon dioxide (CO 2 ) and R134a gas were considered as the model fluids because their critical point conditions are more feasible than those of water. The similarities of water (prototype), CO 2 (model) and R134a (model) for depressurization in a pressure vessel were analyzed. (author)

Two Dimensional CFD Analyses on the Heat Transfer for a Supercritical Pressure CO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Cho, Bong Hyun; Kim, Young In; Bae, Yoon Yeong [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

2005-07-01

The Supercritical Water Cooled Reactor(SCWR) operates in a pressure around 25MPa and temperature of 293{approx}510 .deg. C. In order to study the heat transfer behaviors and good comparisons between the various fluids, a heat transfer test loop(SPHINX) using CO{sub 2} has been constructed in KAERI as a part of international research program, I-NERI. At a supercritical pressure, the heat transfer coefficient is much larger than that estimated from the Dittus-Boelter correlation for a relatively large flow rate with moderate wall heat flux conditions. This phenomenon was explained by the rapid variations of the physical properties near the wall with the temperature. On the contrary, the heat transfer becomes worse when the bulk fluid enthalpy is below the pseudo-critical enthalpy under a low flow rate with large heat flux conditions. This phenomenon is called 'deteriorated heat transfer', and which is explained as the modification of the shear stress distribution across the tube to a buoyancy and/or acceleration in a low density layer near the wall, with the consequence of a turbulence. The upward vertical flow of CO{sub 2} through a uniformly heated tube of 4.4 mm in diameter and 3m long(heated length is 2.1m) was investigated numerically using the CFD code, FLUENT. Through the numerical simulations, we have attempted to obtain a physically meaningful insight into the heat transfer mechanisms at a supercritical pressure.

Research and development of the supercritical-pressure light water cooled reactor

International Nuclear Information System (INIS)

Oka, Yoshiaki

2003-01-01

The concept of high temperature reactor cooled by light water (SCR) has been developed at the University of Tokyo since 1989. Major elements of reactor conceptual design and safety were studied. It includes fuel rod design, core design of thermal and fast reactors, plant heat balance, safety design, accident and transient analysis, LOCA, PSA, plant control, start-up and stability. The big advantage of the SCR concept is that the temperatures of major components such as reactor pressure vessel, control rod drive mechanisms, containments, coolant pumps, main steam piping and turbines are within the temperatures of the components of LWR and supercritical FPP in spite of the high outlet coolant temperature. The experience of these components of LWR and supercritical fossil Fired Power Plants (FPP) will be fully utilized for SCR. Although the concept was developed at the University of Tokyo mostly with our own funds and resources, four funding was/is provided for the research in Japan so far. Those are TEPCO studies with Japanese vendors in 1994 and 1995. JSPS (Monbusho) funding of pulse radiolysis of supercritical water to the University of Tokyo, Japanese-NERI program of METI to Toshiba team on thermal hydraulics, corrosion and plant system and Japanese-NERI program of MEXT on water chemistry to the University of Tokyo. The concept was taken as the reference of HPLWR study in Europe with funding of EU in 2000 and 2001. The concept was evaluated in the Generation 4 reactor program in USA. It was selected as only one water-cooled Generation 4 reactor. This paper describes the overview of the conceptual design at the University of Tokyo and R and D in the world

Modelling of heat transfer to fluids at a supercritical pressure

International Nuclear Information System (INIS)

Shuisheng, He

2014-01-01

A key feature of Supercritical Water-cooled Reactor (SCWR) is that, by raising the pressure of the reactor coolant fluid above the critical value, a phase change crisis is avoided. However, the changes in water density as it flows through the core of an SCWR are actually much higher than in the current water-cooled reactors. In a typical design, the ratio of the density of water at the core inlet to that at exit is as high as 7:1. Other fluid properties also vary significantly, especially around the pseudo-critical temperature (at which the specific heat capacity peaks). As a result, turbulent flow and heat transfer behaviour in the core is extremely complex and under certain conditions, significant heat transfer deterioration can potentially occur. Consequently, understanding and being able to predict flow and heat transfer phenomena under normal steady operation conditions and in start-up and hypothetical fault conditions are fundamental to the design of SCWR. There have been intensive studies on flow and heat transfer to fluids at supercritical pressure recently and several excellent review papers have been published. In the talk, we will focus on some turbulence modelling issues encountered in CFD simulations. The talk will first discuss some flow and heat transfer issues related to fluids at supercritical pressures and their potential implications in SCWR, and some recent developments in the understanding and modelling techniques of such problems, which will be followed by an outlook for some future developments.Factors which have a major influence on the flow and will be discussed are buoyancy and flow acceleration due to thermal expansion (both are due to density variations but involve different mechanisms) and the nonuniformity of other fluid properties. In addition, laminar-turbulent flow transition coupled with buoyancy and flow acceleration plays an important role in heat transfer effectiveness and wall temperature in the entrance region but such

Heat transfer and pressure drop of supercritical carbon dioxide flowing in several printed circuit heat exchanger channel patterns

International Nuclear Information System (INIS)

Carlson, M.; Kruizenga, A.; Anderson, M.; Corradini, M.

2012-01-01

Closed-loop Brayton cycles using supercritical carbon dioxide (SCO 2 ) show potential for use in high-temperature power generation applications including High Temperature Gas Reactors (HTGR) and Sodium-Cooled Fast Reactors (SFR). Compared to Rankine cycles SCO 2 Brayton cycles offer similar or improved efficiency and the potential for decreased capital costs due to a reduction in equipment size and complexity. Compact printed-circuit heat exchangers (PCHE) are being considered as part of several SCO 2 Brayton designs to further reduce equipment size with increased energy density. Several designs plan to use a gas cooler operating near the pseudo-critical point of carbon dioxide to benefit from large variations in thermophysical properties, but further work is needed to validate correlations for heat transfer and pressure-drop characteristics of SCO 2 flows in candidate PCHE channel designs for a variety of operating conditions. This paper presents work on experimental measurements of the heat transfer and pressure drop behavior of miniature channels using carbon dioxide at supercritical pressure. Results from several plate geometries tested in horizontal cooling-mode flow are presented, including a straight semi-circular channel, zigzag channel with a bend angle of 80 degrees, and a channel with a staggered array of extruded airfoil pillars modeled after a NACA 0020 airfoil with an 8.1 mm chord length facing into the flow. Heat transfer coefficients and bulk temperatures are calculated from measured local wall temperatures and local heat fluxes. The experimental results are compared to several methods for estimating the friction factor and Nusselt number of cooling-mode flows at supercritical pressures in millimeter-scale channels. (authors)

Destruction of energetic materials by supercritical water oxidation

International Nuclear Information System (INIS)

Beulow, S.J.; Dyer, R.B.; Harradine, D.M.; Robinson, J.M.; Oldenborg, R.C.; Funk, K.A.; McInroy, R.E.; Sanchez, J.A.; Spontarelli, T.

1993-01-01

Supercritical water oxidation is a relatively low-temperature process that can give high destruction efficiencies for a variety of hazardous chemical wastes. Results are presented examining the destruction of high explosives and propellants in supercritical water and the use of low temperature, low pressure hydrolysis as a pretreatment process. Reactions of cyclotrimethylene trinitramine (RDX), cyclotetramethylene tetranitramine (HMX), nitroguanidine (NQ), pentaerythritol tetranitrate (PETN), and 2,4,6-trinitrotoluene (TNT) are examined in a flow reactor operated at temperatures between 400 degrees C and 650 degrees C. Explosives are introduced into the reactor at concentrations below the solubility limits. For each of the compounds, over 99.9% is destroyed in less than 30 seconds at temperatures above 600 degrees C. The reactions produce primarily N 2 , N 2 O,CO 2 , and some nitrate and nitrite ions. The distribution of reaction products depends on reactor pressure, temperature, and oxidizer concentration. Kinetics studies of the reactions of nitrate and nitrite ions with various reducing reagents in supercritical water show that they can be rapidly and completely destroyed at temperatures above 525 degrees C. The use of slurries and hydrolysis to introduce high concentrations of explosives into a supercritical water reactor is examined. For some compounds the rate of reaction depends on particle size. The hydrolysis of explosives at low temperatures (<100 degrees C) and low pressures (<1 atm) under basic conditions produces water soluble, non-explosive products which are easily destroyed by supercritical water oxidation. Large pieces of explosives (13 cm diameter) have been successfully hydrolyzed. The rate, extent, and products of the hydrolysis depend on the type and concentration of base. Results from the base hydrolysis of triple base propellant M31A1E1 and the subsequent supercritical water oxidation of the hydrolysis products are presented

Inelastic X-ray scattering experiments at extreme conditions: high temperatures and high pressures

Directory of Open Access Journals (Sweden)

S.Hosokawa

2008-03-01

Full Text Available In this article, we review the present status of experimental techniques under extreme conditions of high temperature and high pressure used for inelastic X-ray scattering (IXS experiments of liquid metals, semiconductors, molten salts, molecular liquids, and supercritical water and methanol. For high temperature experiments, some types of single-crystal sapphire cells were designed depending on the temperature of interest and the sample thickness for the X-ray transmission. Single-crystal diamond X-ray windows attached to the externally heated high-pressure vessel were used for the IXS experiment of supercritical water and methanol. Some typical experimental results are also given, and the perspective of IXS technique under extreme conditions is discussed.

Oxidation performance of high temperature steels and coatings for future supercritical power plants

Energy Technology Data Exchange (ETDEWEB)

Auerkari, Pertti; Salonen, Jorma; Toivonen, Aki; Penttilae, Sami [VTT, Espoo (Finland); Haekkilae, Juha [Foster Wheeler Energia, Varkaus (Finland); Aguero, Alina; Gutierrez, Marcos; Muelas, Raul [INTA, Madrid (Spain); Fry, Tony [NPL (United Kingdom)

2010-07-01

The operating efficiency of current and future thermal power plants is largely dependent on the applied temperature and pressure, which are in part limited by the internal oxidation resistance of the structural materials in the steam systems. Alternative and reference materials for such systems have been tested within the COST 536 (ACCEPT) project, including bulk reference materials (ferritic P92 and austenitic 316 LN steels) and several types of coatings under supercritical combined (oxygen) water chemistry (150 ppb DO) at 650 C/300 bar. The testing results from a circulating USC autoclave showed that under such conditions the reference bulk steels performed poorly, with extensive oxidation already after relatively short term exposure to the supercritical medium. Better protection was attained by suitable coatings, although there were clear differences in the protective capabilities between different coating types, and some challenges remain in applying (and repairing) coatings for the internal surfaces of welded structures. The materials performance seems to be worse in supercritical than in subcritical conditions, and this appears not to be only due to the effect of temperature. The implications are considered from the point of view of the operating conditions and materials selection for future power plants. (orig.)

Effects of Supercritical Environment on Hydrocarbon-fuel Injection

Institute of Scientific and Technical Information of China (English)

Bongchul Shin; Dohun Kim; Min Son; Jaye Koo

2017-01-01

In this study,the effects of environment conditions on decane were investigated.Decane was injected in subcritical and supercritical ambient conditions.The visualization chamber was pressurized to 1.68 MPa by using nitrogen gas at a temperature of 653 K for subcritical ambient conditions.For supercritical ambient conditions,the visualization chamber was pressurized to 2.52 MPa by using helium at a temperature of 653 K.The decane injection in the pressurized chamber was visualized via a shadowgraph technique and gradient images were obtained by a post processing method.A large variation in density gradient was observed at jet interface in the case of subcritical injection in subcritical ambient conditions.Conversely,for supercritical injection in supercritical ambient conditions,a small density gradient was observed at the jet interface.In a manner similar to that observed in other cases,supercritical injection in subcritical ambient conditions differed from supercritical ambient conditions such as sphere shape liquid.Additionally,there were changes in the interface,and the supercritical injection core width was thicker than that in the subcritical injection.Furthermore,in cases with the same injection conditions,the change in the supercritical ambient normalized core width was smaller than the change in the subcritical ambient normalized core width owing to high specific heat at the supercritical injection and small phase change at the interface.Therefore,the interface was affected by the changing ambient condition.Given that the effect of changing the thermodynamic properties of propellants could be essential for a variable thrust rocket engine,the effects of the ambient conditions were investigated experimentally.

Effects of supercritical environment on hydrocarbon-fuel injection

Science.gov (United States)

Shin, Bongchul; Kim, Dohun; Son, Min; Koo, Jaye

2017-04-01

In this study, the effects of environment conditions on decane were investigated. Decane was injected in subcritical and supercritical ambient conditions. The visualization chamber was pressurized to 1.68 MPa by using nitrogen gas at a temperature of 653 K for subcritical ambient conditions. For supercritical ambient conditions, the visualization chamber was pressurized to 2.52 MPa by using helium at a temperature of 653 K. The decane injection in the pressurized chamber was visualized via a shadowgraph technique and gradient images were obtained by a post processing method. A large variation in density gradient was observed at jet interface in the case of subcritical injection in subcritical ambient conditions. Conversely, for supercritical injection in supercritical ambient conditions, a small density gradient was observed at the jet interface. In a manner similar to that observed in other cases, supercritical injection in subcritical ambient conditions differed from supercritical ambient conditions such as sphere shape liquid. Additionally, there were changes in the interface, and the supercritical injection core width was thicker than that in the subcritical injection. Furthermore, in cases with the same injection conditions, the change in the supercritical ambient normalized core width was smaller than the change in the subcritical ambient normalized core width owing to high specific heat at the supercritical injection and small phase change at the interface. Therefore, the interface was affected by the changing ambient condition. Given that the effect of changing the thermodynamic properties of propellants could be essential for a variable thrust rocket engine, the effects of the ambient conditions were investigated experimentally.

Supercritical water natural circulation flow stability experiment research

Energy Technology Data Exchange (ETDEWEB)

Ma, Dongliang; Zhou, Tao; Li, Bing [North China Electric Power Univ., Beijing (China). School of Nuclear Science and Engineering; North China Electric Power Univ., Beijing (China). Inst. of Nuclear Thermalhydraulic Safety and Standardization; North China Electric Power Univ., Beijing (China). Beijing Key Lab. of Passive Safety Technology for Nuclear Energy; Huang, Yanping [Nuclear Power Institute of China, Chengdu (China). Science and Technology on Reactor System Design Technology Lab.

2017-12-15

The Thermal hydraulic characteristics of supercritical water natural circulation plays an important role in the safety of the Generation-IV supercritical water-cooled reactors. Hence it is crucial to conduct the natural circulation heat transfer experiment of supercritical water. The heat transfer characteristics have been studied under different system pressures in the natural circulation systems. Results show that the fluctuations in the subcritical flow rate (for natural circulation) is relatively small, as compared to the supercritical flow rate. By increasing the heating power, it is observed that the amplitude (and time period) of the fluctuation tends to become larger for the natural circulation of supercritical water. This tends to show the presence of flow instability in the supercritical water. It is possible to observe the flow instability phenomenon when the system pressure is suddenly reduced from the supercritical pressure state to the subcritical state. At the test outlet section, the temperature is prone to increase suddenly, whereas the blocking effect may be observed in the inlet section of the experiment.

Supercritical Water Reactor Cycle for Medium Power Applications

International Nuclear Information System (INIS)

BD Middleton; J Buongiorno

2007-01-01

Scoping studies for a power conversion system based on a direct-cycle supercritical water reactor have been conducted. The electric power range of interest is 5-30 MWe with a design point of 20 MWe. The overall design objective is to develop a system that has minimized physical size and performs satisfactorily over a broad range of operating conditions. The design constraints are as follows: Net cycle thermal efficiency (ge)20%; Steam turbine outlet quality (ge)90%; and Pumping power (le)2500 kW (at nominal conditions). Three basic cycle configurations were analyzed. Listed in order of increased plant complexity, they are: (1) Simple supercritical Rankine cycle; (2) All-supercritical Brayton cycle; and (3) Supercritical Rankine cycle with feedwater preheating. The sensitivity of these three configurations to various parameters, such as reactor exit temperature, reactor pressure, condenser pressure, etc., was assessed. The Thermoflex software package was used for this task. The results are as follows: (a) The simple supercritical Rankine cycle offers the greatest hardware simplification, but its high reactor temperature rise and reactor outlet temperature may pose serious problems from the viewpoint of thermal stresses, stability and materials in the core. (b) The all-supercritical Brayton cycle is not a contender, due to its poor thermal efficiency. (c) The supercritical Rankine cycle with feedwater preheating affords acceptable thermal efficiency with lower reactor temperature rise and outlet temperature. (d) The use of a moisture separator improves the performance of the supercritical Rankine cycle with feedwater preheating and allows for a further reduction of the reactor outlet temperature, thus it was selected for the next step. Preliminary engineering design of the supercritical Rankine cycle with feedwater preheating and moisture separation was performed. All major components including the turbine, feedwater heater, feedwater pump, condenser, condenser pump

Study of the effects of elevated pressure and temperature on the evaporation of a single fuel droplet

International Nuclear Information System (INIS)

Memon, A.A.; Memon, M.A.; Durrani, H.A.

1991-01-01

The experimental studies were made on the evaporation of single fuel droplet in high pressure and high temperature gaseous environments. The time history of the size and the temperature of an evaporating droplet suspended on a fine quartz thread was recorded using a movie camera and an oscilloscope. The fuel used was n-heptane. The experimental range of conditions consists of gas pressure from 0 atg to 50 atg, gas temperature from 100 c to 500 c which correspond to the subcritical, critical and supercritical state of a droplet. The evaporation rate, the life time and the wet-bulb temperature of a droplet were obtained. The results showed that the temperature of an evaporating droplet increased with an increase in gas pressure and temperature, through it did not reach the critical temperature of fuel even at supercritical environments. It was evident that with an increase in gas pressure, the evaporation rate increased at high gas temperature while it decreased at low gas temperature. (author)

Development of an Accelerated Methodology to Study Degradation of Materials in Supercritical Water for Application in High Temperature Power Plants

Science.gov (United States)

Rodriguez, David

The decreasing supply of fossil fuel sources, coupled with the increasing concentration of green house gases has placed enormous pressure to maximize the efficiency of power generation. Increasing the outlet temperature of these power plants will result in an increase in operating efficiency. By employing supercritical water as the coolant in thermal power plants (nuclear reactors and coal power plants), the plant efficiency can be increased to 50%, compared to traditional reactors which currently operate at 33%. The goal of this dissertation is to establish techniques to characterize the mechanical properties and corrosion behavior of materials exposed to supercritical water. Traditionally, these tests have been long term exposure tests spanning months. The specific goal of this dissertation is to develop a methodology for accelerated estimation of corrosion rates in supercritical water that can be sued as a screening tool to select materials for long term testing. In this study, traditional methods were used to understand the degradation of materials in supercritical water and establish a point of comparison to the first electrochemical studies performed in supercritical water. Materials studied included austenitic steels (stainless steel 304, stainless steel 316 and Nitronic 50) and nickel based alloys (Inconel 625 and 718). Surface chemistry of the oxide layer was characterized using scanning electron microscopy, X-ray diffraction, FT-IR, Raman and X-ray photoelectron spectroscopies. Stainless steel 304 was subjected to constant tensile load creep tests in water at a pressure of 27 MPa and at temperatures of 200 °C, 315 °C and supercritical water at 450 °C for 24 hours. It was determined that the creep rate for stainless steel 304 exposed to supercritical water would be unacceptable for use in service. It was observed that the formation of hematite was favored in subcritical temperatures, while magnetite was formed in the supercritical region. Corrosion of

Calculation of partial molar volume of components in supercritical ammonia synthesis system

Institute of Scientific and Technical Information of China (English)

Cunwen WANG; Chuanbo YU; Wen CHEN; Weiguo WANG; Yuanxin WU; Junfeng ZHANG

2008-01-01

The partial molar volumes of components in supercritical ammonia synthesis system are calculated in detail by the calculation formula of partial molar volume derived from the R-K equation of state under different conditions. The objectives are to comprehend phase beha-vior of components and to provide the theoretic explana-tion and guidance for probing novel processes of ammonia synthesis under supercritical conditions. The conditions of calculation are H2/N2= 3, at a concentra-tion of NH3 in synthesis gas ranging from 2% to 15%, Concentration of medium in supercritical ammonia syn-thesis system ranging from 20% to 50%, temperature ran-ging from 243 K to 699 K and pressure ranging from 0.1 MPa to 187 MPa. The results show that the ammonia synthesis system can reach supercritical state by adding a suitable supercritical medium and then controlling the reaction conditions. It is helpful for the supercritical ammonia synthesis that medium reaches supercritical state under the conditions of the corresponding total pres-sure and components near the normal temperature or near the critical temperature of medium or in the range of tem-perature of industrialized ammonia synthesis.

Bio-oil production from biomass via supercritical fluid extraction

Energy Technology Data Exchange (ETDEWEB)

Durak, Halil, E-mail: halildurak@yyu.edu.tr [Yuzuncu Yıl University, Vocational School of Health Services, 65080, Van (Turkey)

2016-04-18

Supercritical fluid extraction is used for producing bio-fuel from biomass. Supercritical fluid extraction process under supercritical conditions is the thermally disruption process of the lignocellulose or other organic materials at 250-400 °C temperature range under high pressure (4-5 MPa). Supercritical fluid extraction trials were performed in a cylindrical reactor (75 mL) in organic solvents (acetone, ethanol) under supercritical conditions with (calcium hydroxide, sodium carbonate) and without catalyst at the temperatures of 250, 275 and 300 °C. The produced liquids at 300 °C in supercritical liquefaction were analyzed and characterized by elemental, GC-MS and FT-IR. 36 and 37 different types of compounds were identified by GC-MS obtained in acetone and ethanol respectively.

Bio-oil production from biomass via supercritical fluid extraction

International Nuclear Information System (INIS)

Durak, Halil

2016-01-01

Supercritical fluid extraction is used for producing bio-fuel from biomass. Supercritical fluid extraction process under supercritical conditions is the thermally disruption process of the lignocellulose or other organic materials at 250-400 °C temperature range under high pressure (4-5 MPa). Supercritical fluid extraction trials were performed in a cylindrical reactor (75 mL) in organic solvents (acetone, ethanol) under supercritical conditions with (calcium hydroxide, sodium carbonate) and without catalyst at the temperatures of 250, 275 and 300 °C. The produced liquids at 300 °C in supercritical liquefaction were analyzed and characterized by elemental, GC-MS and FT-IR. 36 and 37 different types of compounds were identified by GC-MS obtained in acetone and ethanol respectively.

Experimental investigation of a low-temperature organic Rankine cycle (ORC) engine under variable heat input operating at both subcritical and supercritical conditions

International Nuclear Information System (INIS)

Kosmadakis, George; Manolakos, Dimitris; Papadakis, George

2016-01-01

Highlights: • Small-scale ORC engine with converted scroll expander is installed at laboratory. • Design suitable for supercritical operation. • ORC engine tested at temperature equal to 95 °C. • Focus is given on expansion and thermal efficiency. • Supercritical operation showed some promising performance. - Abstract: The detailed experimental investigation of an organic Rankine cycle (ORC) is presented, which is designed to operate at supercritical conditions. The net capacity of this engine is almost 3 kW and the laboratory testing of the engine includes the variation of the heat input and of the hot water temperature. The maximum heat input is 48 kW_t_h, while the hot water temperature ranges from 65 up to 100°C. The tests are conducted at the laboratory and the heat source is a controllable electric heater, which can keep the hot water temperature constant, by switching on/off its electrical resistances. The expansion machine is a modified scroll compressor with major conversions, in order to be able to operate with safety at high pressure (or even supercritical at some conditions). The ORC engine is equipped with a dedicated heat exchanger of helical coil design, suitable for such applications. The speeds of the expander and ORC pump are regulated with frequency inverters, in order to control the cycle top pressure and heat input. The performance of all components is evaluated, while special attention is given on the supercritical heat exchanger and the scroll expander. The performance tests examined here concern the variation of the heat input, while the hot water temperature is equal to 95 °C. The aim is to examine the engine performance at the design conditions, as well as at off-design ones. Especially the latter ones are very important, since this engine will be coupled with solar collectors at the final configuration, where the available heat is varied to a great extent. The engine has been measured at the laboratory, where a thermal

High Materials Performance in Supercritical CO2 in Comparison with Atmospheric Pressure CO2 and Supercritical Steam

Energy Technology Data Exchange (ETDEWEB)

Holcomb, Gordon [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Tylczak, Joseph [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Carney, Casey [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Dogan, Omer N. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)

2017-02-26

This presentation covers environments (including advanced ultra-supercritical (A-USC) steam boiler/turbine and sCO2 indirect power cycle), effects of pressure, exposure tests, oxidation results, and mechanical behavior after exposure.

Supercritical Water Mixture (SCWM) Experiment

Science.gov (United States)

Hicks, Michael C.; Hegde, Uday G.

2012-01-01

The subject presentation, entitled, Supercritical Water Mixture (SCWM) Experiment, was presented at the International Space Station (ISS) Increment 33/34 Science Symposium. This presentation provides an overview of an international collaboration between NASA and CNES to study the behavior of a dilute aqueous solution of Na2SO4 (5% w) at near-critical conditions. The Supercritical Water Mixture (SCWM) investigation, serves as important precursor work for subsequent Supercritical Water Oxidation (SCWO) experiments. The SCWM investigation will be performed in DECLICs High Temperature Insert (HTI) for the purpose of studying critical fluid phenomena at high temperatures and pressures. The HTI includes a completely sealed and integrated test cell (i.e., Sample Cell Unit SCU) that will contain approximately 0.3 ml of the aqueous test solution. During the sequence of tests, scheduled to be performed in FY13, temperatures and pressures will be elevated to critical conditions (i.e., Tc = 374C and Pc = 22 MPa) in order to observe salt precipitation, precipitate agglomeration and precipitate transport in the presence of a temperature gradient without the influences of gravitational forces. This presentation provides an overview of the motivation for this work, a description of the DECLIC HTI hardware, the proposed test sequences, and a brief discussion of the scientific research objectives.

Experiments on the basic behavior of supercritical CO{sub 2} natural circulation

Energy Technology Data Exchange (ETDEWEB)

Liu, Guangxu [CNNC Key Laboratory on Nuclear Reactor Thermal Hydraulics Technology, Nuclear Power Institute of China (China); Huang, Yanping, E-mail: hyanping007@163.com [CNNC Key Laboratory on Nuclear Reactor Thermal Hydraulics Technology, Nuclear Power Institute of China (China); Wang, Junfeng; Lv, Fa [CNNC Key Laboratory on Nuclear Reactor Thermal Hydraulics Technology, Nuclear Power Institute of China (China); Leung, Laurence K.H. [Canadian Nuclear Laboratories, 286 Plant Road, Chalk River, Ontario (Canada)

2016-04-15

Highlights: • Steady-state behavior of supercritical CO{sub 2} natural circulation was studied. • Effects of pressure and inlet temperature were carefully investigated. • No instabilities were found in present study. • The maximum of mass flow was obtained at outlet temperature much higher than T{sub pc}. • Inlet temperature has vital effect on mass flow rate. - Abstract: To study the steady-state characteristics of supercritical carbon dioxide natural circulation, experiments were carried out in a simple rectangular loop with vertically placed heating section. The effects of system pressure and inlet temperature on the system behavior were also investigated. No instabilities were found in the present experiments. The maximum of mass flow rate was obtained at a heating section outlet temperature much higher than the pseudo-critical temperature. The maximum value of mass flow rate increased with system pressure just as in two-phase natural circulation systems. Inlet temperature significantly affected the steady-state characteristics of supercritical carbon dioxide natural circulation system. A small temperature difference of 14 °C in the natural circulation system could induce a mass flow rate with considerably high Re up to 9.1 × 10{sup 4}, which indicates the potential for supercritical carbon dioxide to be used as a high efficient natural circulation working fluid.

Preliminary Study on the High Efficiency Supercritical Pressure Water-Cooled Reactor for Electricity Generation

Energy Technology Data Exchange (ETDEWEB)

Bae, Yoon Yeong; Park, Jong Kyun; Cho, Bong Hyun and others

2006-01-15

This research has been performed to introduce a concept of supercritical pressure water cooled reactor(SCWR) in Korea The area of research includes core conceptual design, evaluation of candidate fuel, fluid systems conceptual design with mechanical consideration, preparation of safety analysis code, and construction of supercritical pressure heat transfer test facility, SPHINX, and preliminary test. As a result of the research, a set of tools for the reactor core design has been developed and the conceptual core design with solid moderator was proposed. The direct thermodynamic cycle has been studied to find a optimum design. The safety analysis code has also been adapted to supercritical pressure condition. A supercritical pressure CO2 heat transfer test facility has been constructed and preliminary test proved the facility works as expected. The result of this project will be good basis for the participation in the international collaboration under GIF GEN-IV program and next 5-year mid and long term nuclear research program of MOST. The heat transfer test loop, SPHINX, completed as a result of this project may be used for the power cycle study as well as further heat transfer study for the various geometries.

Development of out-of-core concepts for a supercritical-water, pressure-tube reactor

International Nuclear Information System (INIS)

Diamond, W.T.

2010-01-01

One of the Generation IV programs at Chalk River Laboratories has as its prime focus the development of out-of-core concepts for the SuperCritical Water (SCW) pressure tube reactor under development in Canada. A number of technical issues associated with the interface of out-of-core components and the pressure tubes of a SCW pressure tube reactor are being investigated. This article focuses on several aspects of out-of-core components and layouts, building upon concepts that have been developed during the past few years. The efforts are strongly focused on concepts for a fuel channel that can be fabricated with the tight lattice pitch (typically 230 to 250 mm) that may be required for some applications such as utilization of a thorium fuel cycle. It is not practical to adapt concepts with a tight lattice pitch while using the thicker materials required for the higher temperatures and pressures required for supercritical operation. A change in lattice pitch or configuration is required to accommodate the component size increases. This presentation will cover a number of new concepts developed to produce feeders and end fittings for the harsh conditions of a SCW pressure tube reactor. These components are then developed into conceptual models of a Gen IV pressure tube reactor mounted in both horizontal and vertical orientations. Full 3-D solid models of both concepts will be demonstrated as well as a 1/10th-scale model of one face of a horizontal concept that has been built from components made with a 3-D printer. (author)

Coiled tubing drilling with supercritical carbon dioxide

Science.gov (United States)

Kolle , Jack J.

2002-01-01

A method for increasing the efficiency of drilling operations by using a drilling fluid material that exists as supercritical fluid or a dense gas at temperature and pressure conditions existing at a drill site. The material can be used to reduce mechanical drilling forces, to remove cuttings, or to jet erode a substrate. In one embodiment, carbon dioxide (CO.sub.2) is used as the material for drilling within wells in the earth, where the normal temperature and pressure conditions cause CO.sub.2 to exist as a supercritical fluid. Supercritical carbon dioxide (SC--CO.sub.2) is preferably used with coiled tube (CT) drilling equipment. The very low viscosity SC--CO.sub.2 provides efficient cooling of the drill head, and efficient cuttings removal. Further, the diffusivity of SC--CO.sub.2 within the pores of petroleum formations is significantly higher than that of water, making jet erosion using SC--CO.sub.2 much more effective than water jet erosion. SC--CO.sub.2 jets can be used to assist mechanical drilling, for erosion drilling, or for scale removal. A choke manifold at the well head or mud cap drilling equipment can be used to control the pressure within the borehole, to ensure that the temperature and pressure conditions necessary for CO.sub.2 to exist as either a supercritical fluid or a dense gas occur at the drill site. Spent CO.sub.2 can be vented to the atmosphere, collected for reuse, or directed into the formation to aid in the recovery of petroleum.

Design of a supercritical water-cooled reactor. Pressure vessel and internals

Energy Technology Data Exchange (ETDEWEB)

Fischer, Kai

2008-08-15

The High Performance Light Water Reactor (HPLWR) is a light water reactor with supercritical steam conditions which has been investigated within the 5th Framework Program of the European Commission. Due to the supercritical pressure of 25 MPa, water, used as moderator and as coolant, flows as a single phase through the core and can be directly fed to the turbine. Using the technology of coal fired power plants with supercritical steam conditions, the heat-up in the core is done in several steps to achieve the targeted high steam outlet temperature of 500.C without exceeding available cladding material limits. Based on a first design of a fuel assembly cluster for a HPLWR with a single pass core, the surrounding internals and the reactor pressure vessel (RPV) are dimensioned for the first time, following the safety standards of the nuclear safety standards commission in Germany. Furthermore, this design is extended to the incorporation of core arrangements with two and three passes. The design of the internals and the RPV are verified using mechanical or, in the case of large thermal deformations, combined mechanical and thermal stress analyses. Additionally, a passive safety component for the feedwater inlet of the RPV of the HPLWR is designed. Its purpose is the reduction of the mass flow rate in case of a LOCA for a feedwater line break until further steps are executed. Starting with a simple vortex diode, several steps are executed to enhance the performance of the diode and adapt it to this application. Then, this first design is further optimized using combined 1D and 3D flow analyses. Parametric studies determine the performance and characteristic for changing mass flow rates for this backflow limiter. (orig.)

Analytical approximations for thermophysical properties of supercritical nitrogen (SCN) to be used in futuristic high temperature superconducting (HTS) cables

Energy Technology Data Exchange (ETDEWEB)

Dondapati, Raja Sekhar, E-mail: drsekhar@ieee.org [School of Mechanical Engineering, Lovely Professional University, Phagwara, Punjab 144401 (India); Ravula, Jeswanth [School of Mechanical Engineering, Lovely Professional University, Phagwara, Punjab 144401 (India); Thadela, S. [Department of Mechanical Engineering, Andhra University, Visakhapatnam, Andhra Pradesh (India); Usurumarti, Preeti Rao [Department of Mechanical Engineering, P.V.K. Institute of Technology, Anantapur, Andhra Pradesh (India)

2015-12-15

Future power transmission applications demand higher efficiency due to the limited resources of energy. In order to meet such demand, a novel method of transmission is being developed using High Temperature Superconducting (HTS) cables. However, these HTS cables need to be cooled below the critical temperature of superconductors used in constructing the cable to retain the superconductivity. With the advent of new superconductors whose critical temperatures having reached up to 134 K (Hg based), a need arises to find a suitable coolant which can accommodate the heating loads on the superconductors. The present work proposes, Supercritical Nitrogen (SCN) to be a feasible coolant to achieve the required cooling. Further, the feasibility of proposed coolant to be used in futuristic HTS cables is investigated by studying the thermophysical properties such as density, viscosity, specific heat and thermal conductivity with respect to temperature (T{sub C} + 10 K) and pressure (P{sub C} + 10 bar). In addition, few temperature dependent analytical functions are developed for thermophysical properties of SCN which are useful in predicting thermohydraulic performance (pressure drop, pumping power and cooling capacity) using numerical or computational techniques. Also, the developed analytical functions are used to calculate the pumping power and the temperature difference between inlet and outlet of HTS cable. These results are compared with those of liquid nitrogen (LN2) and found that the circulating pumping power required to pump SCN is significantly smaller than that to pump LN2. Further, it is found that the temperature difference between the inlet and outlet is smaller as compared to that when LN2 is used, SCN can be preferred to cool long length Hg based HTS cables. - Highlights: • Analytical functions are developed for thermophysical properties of Supercritical Nitrogen. • Error analysis shows extremely low errors in the developed analytical functions. �

Analytical approximations for thermophysical properties of supercritical nitrogen (SCN) to be used in futuristic high temperature superconducting (HTS) cables

International Nuclear Information System (INIS)

Dondapati, Raja Sekhar; Ravula, Jeswanth; Thadela, S.; Usurumarti, Preeti Rao

2015-01-01

Future power transmission applications demand higher efficiency due to the limited resources of energy. In order to meet such demand, a novel method of transmission is being developed using High Temperature Superconducting (HTS) cables. However, these HTS cables need to be cooled below the critical temperature of superconductors used in constructing the cable to retain the superconductivity. With the advent of new superconductors whose critical temperatures having reached up to 134 K (Hg based), a need arises to find a suitable coolant which can accommodate the heating loads on the superconductors. The present work proposes, Supercritical Nitrogen (SCN) to be a feasible coolant to achieve the required cooling. Further, the feasibility of proposed coolant to be used in futuristic HTS cables is investigated by studying the thermophysical properties such as density, viscosity, specific heat and thermal conductivity with respect to temperature (T_C + 10 K) and pressure (P_C + 10 bar). In addition, few temperature dependent analytical functions are developed for thermophysical properties of SCN which are useful in predicting thermohydraulic performance (pressure drop, pumping power and cooling capacity) using numerical or computational techniques. Also, the developed analytical functions are used to calculate the pumping power and the temperature difference between inlet and outlet of HTS cable. These results are compared with those of liquid nitrogen (LN2) and found that the circulating pumping power required to pump SCN is significantly smaller than that to pump LN2. Further, it is found that the temperature difference between the inlet and outlet is smaller as compared to that when LN2 is used, SCN can be preferred to cool long length Hg based HTS cables. - Highlights: • Analytical functions are developed for thermophysical properties of Supercritical Nitrogen. • Error analysis shows extremely low errors in the developed analytical functions. �

Precipitation of fluticasone propionate microparticles using supercritical antisolvent

Directory of Open Access Journals (Sweden)

A Vatanara

2009-03-01

Full Text Available ABSTRACT Background: The ability of supercritical fluids (SCFs, such as carbon dioxide, to dissolve and expand or extract organic solvents and as result lower their solvation power, makes it possible the use of SCFs for the precipitation of solids from organic solutions. The process could be the injection of a solution of the substrate in an organic solvent into a vessel which is swept by a supercritical fluid. The aim of this study was to ascertain the feasibility of supercritical processing to prepare different particulate forms of fluticasone propionate (FP, and to evaluate the influence of different liquid solvents and precipitation temperatures on the morphology, size and crystal habit of particles. Method: The solution of FP in organic solvents, was precipitated by supercritical carbon dioxide (SCCO2 at two pressure and temperature levels. Effects of process parameters on the physicochemical characteristics of harvested microparticles were evaluated. Results: Particle formation was observed only at the lower selected pressure, whilst at the higher pressure, no precipitation of particles was occurred due to dissolution of FP in supercritical antisolvent. The micrographs of the produced particles showed different morphologies for FP obtained from different conditions. The results of thermal analysis of the resulted particles showed that changes in the processing conditions didn't influence thermal behavior of the precipitated particles. Evaluation of the effect of temperature on the size distribution of particles showed that increase in the temperature from 40 oC to 50 oC, resulted in reduction of the mean particle size from about 30 µm to about 12 μm. ‍Conclusion: From the results of this study it may be concluded that, processing of FP by supercritical antisolvent could be an approach for production of diverse forms of the drug and drastic changes in the physical characteristics of microparticles could be achieved by changing the

Substantial rate enhancements of the esterification reaction of phthalic anhydride with methanol at high pressure and using supercritical CO2 as a co-solvent in a glass microreactor

NARCIS (Netherlands)

Benito-Lopez, F.; Tiggelaar, Roald M.; Salblut, K.; Huskens, Jurriaan; Egberink, Richard J.M.; Reinhoudt, David; Gardeniers, Johannes G.E.; Verboom, Willem

2007-01-01

The esterification reaction of phthalic anhydride with methanol was performed at different temperatures in a continuous flow glass microreactor at pressures up to 110 bar and using supercritical CO2 as a co-solvent. The design is such that supercritical CO2 can be generated inside the microreactor.

Development status and application prospect of supercritical-pressure light water cooled reactor

International Nuclear Information System (INIS)

Li Manchang; Wang Mingli

2006-01-01

The Supercritical-pressure Light Water Cooled Reactor (SCWR) is selected by the Generation IV International Forum (GIF) as one of the six Generation IV nuclear systems that will be developed in the future, and it is an innovative design based on the existing technologies used in LWR and supercritical coal-fired plants. Technically, SCWR may be based on the design, construction and operation experiences in existing PWR and supercritical coal-fired plants, which means that there is no insolvable technology difficulties. Since PWR technology will be adopted in the near term and medium term projects in China, and considering the sustainable development of the technology, it is an inevitable choice to research and develop the nuclear system of supercritical light water cooled reactor. (authors)

Discussion of heat transfer phenomena in fluids at supercritical pressure with the aid of CFD models

International Nuclear Information System (INIS)

Sharabi, Medhat; Ambrosini, Walter

2009-01-01

The paper discusses heat transfer enhancement and deterioration phenomena observed in experimental data for fluids at supercritical pressure. The results obtained by the application of various CFD turbulence models in the prediction of experimental data for water and carbon dioxide flowing in circular tubes are firstly described. On this basis, the capabilities of the addressed models in predicting the observed phenomena are shortly discussed. Then, the analysis focuses on further results obtained by a low-Reynolds number k - ε model addressing one of the considered experimental apparatuses by changing the operating conditions. In particular, the usual imposed heat flux boundary condition is changed to assigned wall temperature, in order to highlight effects otherwise impossible to point out. The obtained results, supported by considerations drawn from experimental information, allow comparing the trends observed for heat transfer deterioration at supercritical pressure with those typical of the thermal crisis in boiling systems, clarifying old concepts of similarity among them

Experimental investigations on heat transfer to CO{sub 2} flowing upward in a narrow annulus at supercritical pressures

Energy Technology Data Exchange (ETDEWEB)

Kim, Hwan Yeol; Kim, Hyung Rae; Kang, Deog Ji; Song, Jin Ho; Bae, Yoon Yeong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2008-03-15

Heat transfer experiments in an annulus passage were performed using SPHINX (Supercritical Pressure Heat transfer Investigation for NeXt generation), which was constructed at KAERI (Korea Atomic Energy Research Institute), to investigate the heat transfer behaviors of supercritical CO{sub 2}. CO{sub 2} was selected as the working fluid to utilize its low critical pressure and temperature when compared with water. The mass flux was in the range of 400 to 1200 kg/m{sup 2} s and the heat flux was chosen at rates up to 150 kW/m{sup 2}. The selected pressures were 7.75 and 8.12 MPa. At lower mass fluxes, heat transfer deterioration occurs if the heat flux increases beyond a certain value. Comparison with the tube test results showed that the degree of heat transfer deterioration in the heat flux was smaller than that in the tube. In addition, the Nusselt number correlation for a normal heat transfer mode is presented.

Elements of Design Consideration of Once-Through Cycle, Supercritical-Pressure Light Water Cooled Reactor

International Nuclear Information System (INIS)

Yoshiaki Oka; Sei-ichi Koshizuka; Yuki Ishiwatari; Akifumi Yamaji

2002-01-01

The paper describes elements of design consideration of supercritical-pressure, light water cooled reactors as well as the status and prospects of the research and development. It summarizes the results of the conceptual design study at the University of Tokyo from 1989. The research and development started in Japan, Europe and USA. The major advantages of the reactors are 1. Compact reactor and turbines due to high specific enthalpy of supercritical water 2.Simple plant system because of the once-through coolant cycle 3.Use of the experience of LWR and fossil-fired power plants. The temperatures of the major components such as reactor pressure vessel, coolant pipes, pumps and turbines are within the experience, in spite of the high outlet coolant temperature. 4.Similarity to LWR safety design and criteria, but no burnout phenomenon 5.Potential cost reduction due to smaller material expenditure and short construction period 6.The smallest reactor not in power rating, but in plant sizes. 7.High-thermal efficiency and low coolant flow rate because of high enthalpy rise. 8.Water cooled reactors potentially free from SCC (stress corrosion cracking) problems. 9.Compatibility of tight-fuel-lattice fast reactor core due to small coolant flow rate, potentially easy shift to fast breeder reactor without changing coolant technology. 10.Potential of producing energy products such as hydrogen and high quality hydro carbons. (authors)

Supercritical-pressure light water cooled reactors

CERN Document Server

Oka, Yoshiaki

2014-01-01

This book focuses on the latest reactor concepts, single pass core and experimental findings in thermal hydraulics, materials, corrosion, and water chemistry. It highlights research on supercritical-pressure light water cooled reactors (SCWRs), one of the Generation IV reactors that are studied around the world. This book includes cladding material development and experimental findings on heat transfer, corrosion and water chemistry. The work presented here will help readers to understand the fundamental elements of reactor design and analysis methods, thermal hydraulics, materials and water

Heat transfer in CO{sub 2} at supercritical pressures in an eccentric annular channel

Energy Technology Data Exchange (ETDEWEB)

Bae, Yoon-Yeong, E-mail: yybae@kaeri.re.kr

2013-12-15

Highlights: • Heat transfer under supercritical pressure in an eccentric annular channel pressure was studied. • The studied geometry was an eccentric annular channel with an eccentricity of 0.33. • The effect of spacer as a turbulence generator was investigated. • The effects of the mass flux, heat flux, and pressure were investigated. • The obtained data were evaluated against the correlation. - Abstract: An experimental investigation of a supercritical heat transfer in an eccentric annular channel was performed using a supercritical heat transfer test facility, SPHINX, at the Korea Atomic Energy Research Institute (KAERI). The eccentric channel was built by placing a 9.5 mm outer diameter heater rod in a 12.5 mm inner diameter tube with an eccentricity of 0.33. The narrowest gap was 1 mm, and the widest gap was 2 mm. The rod was heated indirectly by an imbedded Nickel Chrome heating wire made of NCHW1. Three simple spacers were installed to see their effect, if any, on the heat transfer. The mass fluxes were 400 and 1200 kg/m{sup 2} s, and the heat flux was varied between 30 and 150 kW/m{sup 2} such that the pseudo-critical point was located within the test section as long as possible. When this was not the case, several tests with stepwise increased inlet temperatures were performed so that at least one of them included the pseudo-critical point. The tests were performed at two different pressures of 7.75 and 8.12 MPa to check the pressure effect. The influence of the gap size was clearly seen with the eccentric channel, if not significant. The wall temperatures along the narrowest gap were higher than those along the widest gap as expected, while it was reversed at the end part of the test section. The test results for the eccentric channel were not much different from those for the concentric channel of a similar gap size. As we have seen from the plain tube test, the diameter effect on the heat transfer was also not significant in this test. On the

Supercritical extraction of lycopene from tomato industrial wastes with ethane.

Science.gov (United States)

Nobre, Beatriz P; Gouveia, Luisa; Matos, Patricia G S; Cristino, Ana F; Palavra, António F; Mendes, Rui L

2012-07-11

Supercritical fluid extraction of all-E-lycopene from tomato industrial wastes (mixture of skins and seeds) was carried out in a semi-continuous flow apparatus using ethane as supercritical solvent. The effect of pressure, temperature, feed particle size, solvent superficial velocity and matrix initial composition was evaluated. Moreover, the yield of the extraction was compared with that obtained with other supercritical solvents (supercritical CO₂ and a near critical mixture of ethane and propane). The recovery of all-E-lycopene increased with pressure, decreased with the increase of the particle size in the initial stages of the extraction and was not practically affected by the solvent superficial velocity. The effect of the temperature was more complex. When the temperature increased from 40 to 60 °C the recovery of all-E-lycopene increased from 80 to 90%. However, for a further increase to 80 °C, the recovery remained almost the same, indicating that some E-Z isomerization could have occurred, as well as some degradation of lycopene. The recovery of all-E-lycopene was almost the same for feed samples with different all-E-lycopene content. Furthermore, when a batch with a higher all-E-lycopene content was used, supercritical ethane and a near critical mixture of ethane and propane showed to be better solvents than supercritical CO₂ leading to a faster extraction with a higher recovery of the carotenoid.

Conceptual mechanical design for a pressure-tube type supercritical water-cooled reactor

Energy Technology Data Exchange (ETDEWEB)

Yetisir, M.; Diamond, W.; Leung, L.K.H.; Martin, D.; Duffey, R. [Atomic Energy of Canada Limited, Chalk River, ON (Canada)

2011-07-01

This paper presents a conceptual mechanical design for a heavy-water-moderated pressure-tube supercritical water (SCW) reactor, which has evolved from the well-established CANDU nuclear reactor. As in the current designs, the pressure-tube SCW reactor uses a calandria vessel and, as a result, many of today's technologies (such as the shutdown safety systems) can readily be adopted with small changes. Because the proposed concept uses a low-pressure moderator, it does not require a pressure vessel that is subject to the full SCW pressure and temperature conditions. The proposed design uses batch refueling and hence, the reactor core is orientated vertically. Significant simplifications result in the design with the elimination of on line fuelling systems, fuel channel end fittings and fuel channel closure seals and thus utilize the best features of Light Water Reactor (LWR) and Heavy Water Reactor (HWR) technologies. The safety goal is based on achieving a passive 'no core melt' configuration for the channels and core, so the mechanical features and systems directly reflect this desired attribute. (author)

Conceptual mechanical design for a pressure-tube type supercritical water-cooled reactor

International Nuclear Information System (INIS)

Yetisir, M.; Diamond, W.; Leung, L.K.H.; Martin, D.; Duffey, R.

2011-01-01

This paper presents a conceptual mechanical design for a heavy-water-moderated pressure-tube supercritical water (SCW) reactor, which has evolved from the well-established CANDU nuclear reactor. As in the current designs, the pressure-tube SCW reactor uses a calandria vessel and, as a result, many of today's technologies (such as the shutdown safety systems) can readily be adopted with small changes. Because the proposed concept uses a low-pressure moderator, it does not require a pressure vessel that is subject to the full SCW pressure and temperature conditions. The proposed design uses batch refueling and hence, the reactor core is orientated vertically. Significant simplifications result in the design with the elimination of on line fuelling systems, fuel channel end fittings and fuel channel closure seals and thus utilize the best features of Light Water Reactor (LWR) and Heavy Water Reactor (HWR) technologies. The safety goal is based on achieving a passive 'no core melt' configuration for the channels and core, so the mechanical features and systems directly reflect this desired attribute. (author)

Supercritical carbon dioxide extraction of pigments from Bixa orellana seeds (experiments and modeling

Directory of Open Access Journals (Sweden)

B. P. Nobre

2006-06-01

Full Text Available Supercritical CO2 extraction of the pigments from Bixa orellana seeds was carried out in a flow apparatus at a pressure of 200 bar and a temperature of 40 ºC at two fluid flow rates (0.67g/min and 1.12g/min. The efficiency of the extraction was low (only about 1% of the pigment was extracted. The increase in flow rate led to a decrease in pigment recovery. A large increase in recovery (from 1% to 45% was achieved using supercritical carbon dioxide with 5 mol % ethanol as extraction fluid at pressures of 200 and 300 bar and temperatures of 40 and 60 ºC. Although the increase in temperature and pressure led to an increase in recovery, the changes in flow rate did not seem to affect it. Furthermore, two plug flow models were applied to describe the supercritical extraction of the pigments from annatto seeds. Mass transfer coefficients were determined and compared well with those obtained by other researchers with similar models for the supercritical extraction of solutes from plant materials.

27.12 MHz plasma generation in supercritical carbon dioxide

International Nuclear Information System (INIS)

Kawashima, Ayato; Toyota, Hiromichi; Nomura, Shinfuku; Takemori, Toshihiko; Mukasa, Shinobu; Maehara, Tsunehiro; Yamashita, Hiroshi

2007-01-01

An experiment was conducted for generating high-frequency plasma in supercritical carbon dioxide; it is expected to have the potential for applications in various types of practical processes. It was successfully generated at 6-20 MPa using electrodes mounted in a supercritical cell with a gap of 1 mm. Emission spectra were then measured to investigate the physical properties of supercritical carbon dioxide plasma. The results indicated that while the emission spectra for carbon dioxide and carbon monoxide could be mainly obtained at a low pressure, the emission spectra for atomic oxygen could be obtained in the supercritical state, which increased with the pressure. The temperature of the plasma in supercritical state was estimated to be approximately 6000-7000 K on the assumption of local thermodynamic equilibrium and the calculation results of thermal equilibrium composition in this state showed the increase of atomic oxygen by the decomposition of CO 2

Temperature and pressure effects on solubility in supercritical carbon dioxide and retention in supercritical fluid chromatography

NARCIS (Netherlands)

Lou, X.W.; Janssen, J.G.M.; Cramers, C.A.M.G.

1997-01-01

Solubilities of some polycyclic aromatic hydrocarbons (PAHs) in supercritical carbon dioxide were measured with a procedure based on a direct on-line combination of a saturation cell to a flame ionization detector. Acenaphthene, anthrance and chrysene were selected as the test solutes. A method was

Effect of turbulence models on predicting convective heat transfer to hydrocarbon fuel at supercritical pressure

Directory of Open Access Journals (Sweden)

Tao Zhi

2016-10-01

Full Text Available A variety of turbulence models were used to perform numerical simulations of heat transfer for hydrocarbon fuel flowing upward and downward through uniformly heated vertical pipes at supercritical pressure. Inlet temperatures varied from 373 K to 663 K, with heat flux ranging from 300 kW/m2 to 550 kW/m2. Comparative analyses between predicted and experimental results were used to evaluate the ability of turbulence models to respond to variable thermophysical properties of hydrocarbon fuel at supercritical pressure. It was found that the prediction performance of turbulence models is mainly determined by the damping function, which enables them to respond differently to local flow conditions. Although prediction accuracy for experimental results varied from condition to condition, the shear stress transport (SST and launder and sharma models performed better than all other models used in the study. For very small buoyancy-influenced runs, the thermal-induced acceleration due to variations in density lead to the impairment of heat transfer occurring in the vicinity of pseudo-critical points, and heat transfer was enhanced at higher temperatures through the combined action of four thermophysical properties: density, viscosity, thermal conductivity and specific heat. For very large buoyancy-influenced runs, the thermal-induced acceleration effect was over predicted by the LS and AB models.

Thermal stability of biodiesel in supercritical methanol

Energy Technology Data Exchange (ETDEWEB)

Hiroaki Imahara; Eiji Minami; Shusaku Hari; Shiro Saka [Kyoto University, Kyoto (Japan). Department of Socio-Environmental Energy Science

2008-01-15

Non-catalytic biodiesel production technologies from oils/fats in plants and animals have been developed in our laboratory employing supercritical methanol. Due to conditions in high temperature and high pressure of the supercritical fluid, thermal stability of fatty acid methyl esters and actual biodiesel prepared from various plant oils was studied in supercritical methanol over a range of its condition between 270{sup o}C/17 MPa and 380{sup o}C/56 MPa. In addition, the effect of thermal degradation on cold flow properties was studied. As a result, it was found that all fatty acid methyl esters including poly-unsaturated ones were stable at 270{sup o}C/17 MPa, but at 350{sup o}C/43 MPa, they were partly decomposed to reduce the yield with isomerization from cis-type to trans-type. These behaviors were also observed for actual biodiesel prepared from linseed oil, safflower oil, which are high in poly-unsaturated fatty acids. Cold flow properties of actual biodiesel, however, remained almost unchanged after supercritical methanol exposure at 270{sup o}C/17 MPa and 350{sup o}C/43 MPa. For the latter condition, however, poly-unsaturated fatty acids were sacrificed to be decomposed and reduced in yield. From these results, it was clarified that reaction temperature in supercritical methanol process should be lower than 300{sup o}C, preferably 270{sup o}C with a supercritical pressure higher than 8.09 MPa, in terms of thermal stabilization for high-quality biodiesel production. 9 refs., 3 figs., 4 tabs.

Stability analysis of fluid at supercritical pressure in a heated channel

International Nuclear Information System (INIS)

Gallaway, T.; Podowski, M. Z.

2010-01-01

The Supercritical Water Reactor (SCWR) is one of several reactor design concepts included in the Generation IV International Advanced Reactor Design Program. This reactor design is based upon current light water reactors and supercritical fossil-fuel power plants. Water at supercritical pressures is used as the reactor coolant. At these conditions, there is no phase change in the coolant; however the fluid properties undergo significant variation, particularly in the pseudo-critical region. The fluid density may decrease by a factor of six with increasing temperature. It has been seen before that variations in fluid density can lead to density-wave oscillations in two-phase flow systems in general and boiling water reactors in particular. Such instabilities may cause many undesired problems for reactor operation and safety. Similar issues must be addressed in the design and safety analysis of SCWRs. The objective of the present work has been the development of a detailed one-dimensional model of instabilities in a heated channel corresponding to the geometry and flow conditions in the proposed typical SCWRs. The new model is capable of analyzing in detail transient effects of local property variations in parallel channels subject to a constant pressure drop boundary condition. In particular, such a model can be used to establish SCWR power limits imposed by the onset of instabilities in the hot channel of the reactor. Both time and frequency-domain methods of stability analysis have been developed. The latter method is particularly important since it is not associated with any numerical issues, is very accurate, and allows for establishing general stability boundaries in a computationally effective manner. Model testing has included a study of dependence of the proposed spatial discretization scheme on the accuracy of calculations. A parametric study has also been performed on the effect of channel operating conditions on flow oscillations. Finally, a stability map

Experimental investigation of convection heat transfer of CO2 at supercritical pressures in a vertical circular tube at high Re

International Nuclear Information System (INIS)

Li Zhihui; Jiang Peixue

2008-01-01

Convection heat transfer during the upward flow of CO 2 at supercritical pressures in a vertical circular tube (d in = 2 mm) at high Reynolds numbers was investigated experimentally, and the effects of heat fluxes, mass fluxes, inlet temperatures, pressures, buoyancy and thermal acceleration on the convection heat transfer was analyzed. The results show that the tube wall temperature occurs abnormally distribution for high heat-fluxes with upward flow. The degree of deteriorated heat transfer increases with increasing heat flux. Increasing of the mass flux delays the occurrence of the deterioration of heat transfer and weakens the deterioration of heat transfer down-stream section. The inlet temperature strongly influences the heat transfer. The deterioration degree of heat transfer decreases with increasing pressure. (authors)

Complete Fiber/Copper Cable Solution for Long-Term Temperature and Pressure Measurement in Supercritical Reservoirs and EGS Wells

Energy Technology Data Exchange (ETDEWEB)

Pastouret, Alan [Draka Cableteq USA, Inc., North Dighton, MA (United States); Gooijer, Frans [Draka Cableteq USA, Inc., North Dighton, MA (United States); Overton, Bob [Draka Cableteq USA, Inc., North Dighton, MA (United States); Jonker, Jan [Draka Cableteq USA, Inc., North Dighton, MA (United States); Curley, Jim [Draka Cableteq USA, Inc., North Dighton, MA (United States); Constantine, Walter [Draka Cableteq USA, Inc., North Dighton, MA (United States); Waterman, Kendall Miller [Draka Cableteq USA, Inc., North Dighton, MA (United States)

2015-11-13

High Temperature insulated wire and optical fiber cable is a key enabling technology for the Geothermal Technologies Program (GTP). Without insulated electrical wires and optical fiber, downhole temperature and pressure sensors, flow meters and gauges cannot communicate with the surface. Unfortunately, there are currently no insulated electrical wire or fiber cable constructions capable of surviving for extended periods of deployment in a geothermal well (240-325°C) or supercritical (374°C) reservoir. This has severely hindered engineered reservoir creation, management and utilization, as hot zones and cool water intrusions cannot be understood over time. The lack of a insulated electrical wire and fiber cable solution is a fundamental limitation to the viability of this energy source. The High Temperature Downhole Tools target specification is development of tools and sensors for logging and monitoring wellbore conditions at depths of up to 10,000 meters and temperatures up to 374oC. It well recognized in the industry that no current electronic or fiber cable can be successfully deployed in a well and function successfully for more a few days at temperatures over 240oC. The goal of this project was to raise this performance level significantly. Prysmian Group’s objective in this project was to develop a complete, multi-purpose cable solution for long-term deployment in geothermal wells/reservoirs that can be used with the widest variety of sensors. In particular, the overall project objective was to produce a manufacturable cable design that can perform without serious degradation: • At temperatures up to 374°C; • At pressures up to 220 bar; • In a hydrogen-rich environment; and • For the life of the well (> 5 years). This cable incorporates: • Specialty optical fibers, with specific glass chemistry and high temperature and pressure protective coatings for data communication and distributed temperature and pressure sensing, and • High-temperature

γ-Radiolysis of benzophenone aqueous solution at elevated temperatures up to supercritical condition

International Nuclear Information System (INIS)

Miyazaki, Toyoaki; Katsumura, Yosuke; Lin Mingzhang; Muroya, Yusa; Kudo, Hisaaki; Asano, Masaharu; Yoshida, Masaru

2006-01-01

A product analysis study of γ-irradiated benzophenone aqueous solutions from room temperature to 400 deg. C has been carried out by the combination of a flow irradiation system and a liquid chromatographic method. At room temperature, the main decomposition products are phenol and hydroxybenzophenone isomers. In high temperature and supercritical water solutions, 9-fluorenone appears as an important product and the G-value of benzophenone consumption depends significantly on the water density under supercritical conditions

Experimental study on methanol recovery through flashing vaporation in continuous production of biodiesel via supercritical methanol

International Nuclear Information System (INIS)

Wang Cunwen; Chen Wen; Wang Weiguo; Wu Yuanxin; Chi Ruan; Tang Zhengjiao

2011-01-01

To improve the oil conversion, high methanol/oil molar ratio is required in the continuous production of biodiesel via supercritical methanol transesterification in tubular reactor. And thus the subsequent excess methanol recovery needs high energy consumption. Based on the feature of high temperature and high pressure in supercritical methanol transesterification, excess methanol recovery in reaction system by flashing vaporation is conducted and the effect of reaction temperature, reaction pressure and flashing pressure on methanol recovery and methanol concentration in gas phase is discussed in detail in this article. Results show that at the reaction pressure of 9-15 MPa and the reaction temperature of 240-300 o C, flashing pressure has significant influence on methanol recovery and methanol content in gas phase, which can be effectively improved by reducing flashing pressure. At the same time, reaction temperature and reaction pressure also have an important effect on methanol recovery and methanol content in gas phase. At volume flow of biodiesel and methanol 1:2, tubular reactor pressure 15 MPa, tubular reactor temperature 300 o C and the flashing pressure 0.4 MPa, methanol recovery is more than 85% and methanol concentration of gas phase (mass fraction) is close to 99% after adiabatic braising; therefore, the condensate liquid of gas phase can be injected directly into methanol feedstock tank to be recycled. Research abstracts: Biodiesel is an important alternative energy, and supercritical methanol transesterification is a new and green technology to prepare biodiesel with some obvious advantages. But it also exists some problems: high reaction temperature, high reaction pressure and large molar ratio of methanol/oil will cause large energy consumption which restricts supercritical methanol for the industrial application of biodiesel. So a set of tubular reactor-coupled flashing apparatus is established for continuous preparing biodiesel in supercritical

Pressure drop effects on selectivity and resolution in packed-column supercritical fluid chromatography

NARCIS (Netherlands)

Lou, X.W.; Janssen, J.G.M.; Snijders, H.M.J.; Cramers, C.A.M.G.

1996-01-01

The influence of pressure drop on retention, selectivity, plate height and resolution was investigated systematically in packed supercritical fluid chromatography (SFC) using pure carbon dioxide as the mobile phase. Numerical methods developed previously which enabled the prediction of pressure

Supercritical solvent extraction of oil sand bitumen

Science.gov (United States)

Imanbayev, Ye. I.; Ongarbayev, Ye. K.; Tileuberdi, Ye.; Mansurov, Z. A.; Golovko, A. K.; Rudyk, S.

2017-08-01

The supercritical solvent extraction of bitumen from oil sand studied with organic solvents. The experiments were performed in autoclave reactor at temperature above 255 °C and pressure 29 atm with stirring for 6 h. The reaction resulted in the formation of coke products with mineral part of oil sands. The remaining products separated into SARA fractions. The properties of the obtained products were studied. The supercritical solvent extraction significantly upgraded extracted natural bitumen.

Numerical investigation of flow instability in parallel channels with supercritical water

International Nuclear Information System (INIS)

Shitsi, Edward; Debrah, Seth Kofi; Agbodemegbe, Vincent Yao; Ampomah-Amoako, Emmanuel

2017-01-01

Highlights: •Supercritical flow instability in parallel channels is investigated. •Flow dynamics and heat transfer characteristics are analyzed. •Mass flow rate, pressure, heating power, and axial power shape have significant effects on flow instability. •Numerical results are validated with experimental results. -- Abstract: SCWR is one of the selected Gen IV reactors purposely for electricity generation in the near future. It is a promising technology with higher efficiency compared to current LWRs but without the challenges of heat transfer and its associated flow instability. Supercritical flow instability is mainly caused by sharp change in the coolant properties around the pseudo-critical point of the working fluid and research into this phenomenon is needed to address concerns of flow instability at supercritical pressures. Flow instability in parallel channels at supercritical pressures is investigated in this paper using a three dimensional (3D) numerical tool (STAR-CCM+). The dynamics characteristics such as amplitude and period of out-of-phase inlet mass flow oscillation at the heated channel inlet, and heat transfer characteristic such as maximum outlet temperature of the heated channel outlet temperature oscillation are discussed. Influences of system parameters such as axial power shape, pressure, mass flow rate, and gravity are discussed based on the obtained mass flow and temperature oscillations. The results show that the system parameters have significant effect on the amplitude of the mass flow oscillation and maximum temperature of the heated outlet temperature oscillation but have little effect on the period of the mass flow oscillation. The amplitude of mass flow oscillation and maximum temperature of the heated channel outlet temperature oscillation increase with heating power. The numerical results when compared to experiment data show that the 3D numerical tool (STAR-CCM+) could capture dynamics and heat transfer characteristics of

Wavelet neural network modeling in QSPR for prediction of solubility of 25 anthraquinone dyes at different temperatures and pressures in supercritical carbon dioxide.

Science.gov (United States)

Tabaraki, R; Khayamian, T; Ensafi, A A

2006-09-01

A wavelet neural network (WNN) model in quantitative structure property relationship (QSPR) was developed for predicting solubility of 25 anthraquinone dyes in supercritical carbon dioxide over a wide range of pressures (70-770 bar) and temperatures (291-423 K). A large number of descriptors were calculated with Dragon software and a subset of calculated descriptors was selected from 18 classes of Dragon descriptors with a stepwise multiple linear regression (MLR) as a feature selection technique. Six calculated and two experimental descriptors, pressure and temperature, were selected as the most feasible descriptors. The selected descriptors were used as input nodes in a wavelet neural network (WNN) model. The wavelet neural network architecture and its parameters were optimized simultaneously. The data was randomly divided to the training, prediction and validation sets. The predictive ability of the model was evaluated using validation data set. The root mean squares error (RMSE) and mean absolute errors were 0.339 and 0.221, respectively, for the validation data set. The performance of the WNN model was also compared with artificial neural network (ANN) model and the results showed the superiority of the WNN over ANN model.

Supercritical Fluid Chromatography/Fourier Transform Infrared Spectroscopy Of Food Components

Science.gov (United States)

Calvey, Elizabeth M.; Page, Samuel W.; Taylor, Larry T.

1989-12-01

Supercritical fluid (SF) technologies are being investigated extensively for applications in food processing. The number of SF-related patents issued testifies to the level of interest. Among the properties of materials at temperatures and pressures above their critical points (supercritical fluids) is density-dependent solvating power. Supercritical CO2 is of particular interest to the food industry because of its low critical temperature (31.3°C) and low toxicity. Many of the components in food matrices react or degrade at elevated temperatures and may be adversely affected by high temperature extractions. Likewise, these components may not be amenable to GC analyses. Our SF research has been in the development of methods employing supercritical fluid chromatography (SFC) and extraction (SFE) coupled to a Fourier transform infrared (FT-IR) spectrometer to investigate food composition. The effects of processing techniques on the isomeric fatty acid content of edible oils and the analysis of lipid oxidation products using SFC/FT-IR with a flow-cell interface are described.

Recent Experimental Efforts on High-Pressure Supercritical Injection for Liquid Rockets and Their Implications

Directory of Open Access Journals (Sweden)

Bruce Chehroudi

2012-01-01

Full Text Available Pressure and temperature of the liquid rocket thrust chambers into which propellants are injected have been in an ascending trajectory to gain higher specific impulse. It is quite possible then that the thermodynamic condition into which liquid propellants are injected reaches or surpasses the critical point of one or more of the injected fluids. For example, in cryogenic hydrogen/oxygen liquid rocket engines, such as Space Shuttle Main Engine (SSME or Vulcain (Ariane 5, the injected liquid oxygen finds itself in a supercritical condition. Very little detailed information was available on the behavior of liquid jets under such a harsh environment nearly two decades ago. The author had the opportunity to be intimately involved in the evolutionary understanding of injection processes at the Air Force Research Laboratory (AFRL, spanning sub- to supercritical conditions during this period. The information included here attempts to present a coherent summary of experimental achievements pertinent to liquid rockets, focusing only on the injection of nonreacting cryogenic liquids into a high-pressure environment surpassing the critical point of at least one of the propellants. Moreover, some implications of the results acquired under such an environment are offered in the context of the liquid rocket combustion instability problem.

Effect temperature of supercritical CO2 fluid extraction on phytochemical analysis and antioxidant activity of Zingiber officinale Roscoe

Science.gov (United States)

Sondari, Dewi; Irawadi, Tun Tedja; Setyaningsih, Dwi; Tursiloadi, Silvester

2017-11-01

Supercritical fluid extraction of Zingiber officinale Roscoe has been carried out at a pressure of 16 MPa, with temperatures between 20-40 °C, during extraction time of 6 hours and the flow rate of CO2 fluid 5.5 ml/min. The result of supercritical method was compared with the extraction maceration using a mixture of water and ethanol (70% v/v) for 24 hours. The main content in ginger that has a main role as an antioxidant is a gingerol compound that can help neutralize the damaging effects caused by free radicals in the body, as anti-coagulant, and inhibit the occurrence of blood clots. This study aims to determine the effect of temperature on chemical components contained in rough extract of Zingiber officinale Roscoe and its antioxidant activity, total phenol and total flavonoid content. To determine the chemical components contained in the crude extract of Zingiber officinale Roscoe extracted by supercritical fluid and maceration extraction, GC-MS analysis was performed. Meanwhile, the antioxidant activity of the extract was evaluated based on a 2.2-diphenyl-1-picrylhydrazyl (DPPH) free radical damping method. The results of the analysis show that the result of ginger extract by using the supercritical CO2 extraction method has high antioxidant activity than by using maceration method. The highest total phenol content and total flavonoids were obtained on ginger extraction using supercritical CO2 fluid extraction, indicating that phenol and flavonoid compounds contribute to antioxidant activity. Chromatographic analysis showed that the chemical profile of ginger extract containing oxygenated monoterpenes, monoterpene hydrocarbons, sesquiterpene hydrocarbons, oxygenated monoterpene gingerol and esters. In supercritical fluid extraction, the compounds that can be identified at a temperature of 20-40 °C contain 27 compounds, and 11 compounds from the result of maceration extract. The main component of Zingiber officinale Roscoe extracted using supercritical fluid

Heat transfer study under supercritical pressure conditions

International Nuclear Information System (INIS)

Yamashita, Tohru; Yoshida, Suguru; Mori, Hideo; Morooka, Shinichi; Komita, Hideo; Nishida, Kouji

2003-01-01

Experiments were performed on heat transfer and pressure drop of a supercritical pressure fluid flowing upward in a uniformly heated vertical tube of a small diameter, using HCFC22 as a test fluid. Following results were obtained. (1) Characteristics of the heat transfer are similar to those for the tubes of large diameter. (2) The effect of tube diameter on the heat transfer was seen for a 'normal heat transfer, but not for a 'deteriorated' heat transfer. (3) The limit heat flux for the occurrence of deterioration in heat transfer becomes larger with smaller diameter tube. (4) The Watts and Chou correlation has the best prediction performance for the present data in the 'normal' heat transfer region. (5) Frictional pressure drop becomes smaller than that for an isothermal flow in the region near the pseudocritical point, and this reduction was more remarkable for the deteriorated' heat transfer. (author)

Numerical Analysis of Flow and Heat Transfer Characteristics of CO2 at Vapour and Supercritical Phases in Micro-Channels

Directory of Open Access Journals (Sweden)

Rao N.T.

2016-01-01

Full Text Available Supercritical carbon dioxide (CO2 has special thermal properties with better heat transfer and flow characteristics. Due to this reason, supercritical CO2 is being used recently in air-condition and refrigeration systems to replace non environmental friendly refrigerants. Even though many researches have been done, there are not many literatures for heat transfer and flow characteristics of supercritical CO2. Therefore, the main purpose of this study is to develop flow and heat transfer CFD models on two different phases; vapour and supercritical of CO2 to investigate the heat transfer characteristics and pressure drop in micro-channels. CO2 is considered to be in different phases with different flow pressures but at same temperature. For the simulation, the CO2 flow was assumed to be turbulent, nonisothermal and Newtonian. The numerical results for both phases are compared. From the numerical analysis, for both vapour and supercritical phases, the heat energy from CO2 gas transferred to water to attain thermal equilibrium. The temperature of CO2 at vapour phase decreased 1.78% compared to supercritical phase, which decreased for 0.56% from the inlet temperature. There was a drastic increase of 72% for average Nu when the phase changed from vapour to supercritical. The average Nu decreased rapidly about 41% after total pressure of 9.0 MPa. Pressure drop (ΔP increased together with Reynolds number (Re for vapour and supercritical phases. When the phase changed from vapour to supercritical, ΔP was increased about 26%. The results obtained from this study can provide information for further investigations on supercritical CO2.

Development and validation of spectroscopic methods for monitoring density changes in pressurized gaseous and supercritical fluid systems.

Science.gov (United States)

Blatchford, Marc A; Wallen, Scott L

2002-04-15

The further development of new processes utilizing liquid or supercritical CO2 as a solvent will benefit from the rational design of new CO2-philes. Understanding solvation structures and mechanisms of these molecules is an important part of this process. In such studies, determining the change in density as a function of the measured thermodynamic conditions (pressure and temperature) provides an excellent means of directly monitoring the solution conditions in the detection volume for a given technique. By integrating spectroscopic peaks, changes in area can be used to determine changes in analyte concentration in the detection volume, and thus, it should be possible to monitor the system density in situ. In the present study, we examine the utility of Raman and NMR spectroscopy as a means of following changes in solution density conditions and validate this approach in pure fluids and gases (N2 and CO2) and supercritical fluid mixtures (acetaldehyde vapor in N2). In addition, we present the design of a simple, inexpensive cell for conducting Raman and NMR measurements under moderate pressure conditions.

Thermodynamic Optimization of Supercritical CO{sub 2} Brayton Cycles

Energy Technology Data Exchange (ETDEWEB)

Rhim, Dong-Ryul; Park, Sung-Ho; Kim, Su-Hyun; Yeom, Choong-Sub [Institute for Advanced Engineering, Yongin (Korea, Republic of)

2015-05-15

The supercritical CO{sub 2} Brayton cycle has been studied for nuclear applications, mainly for one of the alternative power conversion systems of the sodium cooled fast reactor, since 1960's. Although the supercritical CO{sub 2} Brayton cycle has not been expected to show higher efficiency at lower turbine inlet temperature over the conventional steam Rankine cycle, the higher density of supercritical CO{sub 2} like a liquid in the supercritical region could reduce turbo-machinery sizes, and the potential problem of sodium-water reaction with the sodium cooled fast reactor might be solved with the use of CO{sub 2} instead of water. The supercritical CO{sub 2} recompression Brayton cycle was proposed for the better thermodynamic efficiency than for the simple supercritical CO{sub 2} Brayton cycle. Thus this paper presents the efficiencies of the supercritical CO{sub 2} recompression Brayton cycle along with several decision variables for the thermodynamic optimization of the supercritical CO{sub 2} recompression Brayton cycle. The analytic results in this study show that the system efficiency reaches its maximum value at a compressor outlet pressure of 200 bars and a recycle fraction of 30 %, and the lower minimum temperature approach at the two heat exchangers shows higher system efficiency as expected.

Size and pressure effects on glass transition temperature of poly (methyl methacrylate) thin films

International Nuclear Information System (INIS)

Lang, X.Y.; Zhang, G.H.; Lian, J.S.; Jiang, Q.

2006-01-01

A simple and unified model, without any adjustable parameter, is developed for size and pressure effects on glass transition temperatures of nanopolymers. The model is based on a model for size dependent glass transition temperature of nanopolymer glasses under ambient pressure, and a pressure-dependent function of the root of mean-square displacement of atom vibration. It is found that the size- and pressure-dependent glass transition temperatures of free-standing films or supported films having weak interaction with substrates decreases with decreasing of pressure and size. However, the glass transition temperature of supported films having strong interaction with substrates increases with the increase of pressure and the decrease of size. The predicted results correspond with available experimental evidences for atactic-Poly (methyl methacrylate) thin films under hydrostatic pressure or under the pressure induced by supercritical fluid CO 2 . In addition, the predicted glass transition temperature of isotactic-Poly (methyl methacrylate) thin films under ambient pressure is consistent with available experimental evidences

Successful treatment with supercritical water oxidation

International Nuclear Information System (INIS)

Jensen, R.

1994-01-01

Supercritical Water Oxidation (SCWO) operates in a totally enclosed system. It uses water at high temperatures and high pressure to chemically change wastes. Oily substances become soluble and complex hydrocarbons are converted into water and carbon dioxide. Research and development on SCWO is described

The effect of low-concentration inorganic materials on the behaviour of supercritical water

Energy Technology Data Exchange (ETDEWEB)

Imre, A.R., E-mail: imre@aeki.kfki.h [KFKI Atomic Energy Research Institute, POB 49, Budapest (Hungary); Hazi, G.; Horvath, A.; Maraczy, Cs. [KFKI Atomic Energy Research Institute, POB 49, Budapest (Hungary); Mazur, V.; Artemenko, S. [Odessa State Academy of Refrigeration, 1/3 Dvoryanslaya Str., 65026, Odessa (Ukraine)

2011-01-15

Research highlights: Small amount of inorganic materials (like corrosion products) can be dissolved in the supercritical water. Pseudo-critical temperature and other properties will be changed. Thermal and hydraulic behaviours of the SCW with small amount of contaminants differ in great extent from the behaviour of pure SCW. - Abstract: Supercritical water is a promising working fluid in the new Generation IV nuclear power plants. Due to the presence of the pseudo-critical line, the thermo-hydraulics (thermal and flow properties) and the physical chemistry of the supercritical water differ significantly from the pressurized hot water used in pressurized water reactors. In this study we would like to analyse the effect of small amount of inorganic material on the thermo-hydraulics of the supercritical water cooled nuclear reactors and other, non-nuclear supercritical water loops.

Model validation and parametric study of fluid flows and heat transfer of aviation kerosene with endothermic pyrolysis at supercritical pressure

Directory of Open Access Journals (Sweden)

Keke Xu

2015-12-01

Full Text Available The regenerative cooling technology is a promising approach for effective thermal protection of propulsion and power-generation systems. A mathematical model has been used to examine fluid flows and heat transfer of the aviation kerosene RP-3 with endothermic fuel pyrolysis at a supercritical pressure of 5 MPa. A pyrolytic reaction mechanism, which consists of 18 species and 24 elementary reactions, is incorporated to account for fuel pyrolysis. Detailed model validations are conducted against a series of experimental data, including fluid temperature, fuel conversion rate, various product yields, and chemical heat sink, fully verifying the accuracy and reliability of the model. Effects of fuel pyrolysis and inlet flow velocity on flow dynamics and heat transfer characteristics of RP-3 are investigated. Results reveal that the endothermic fuel pyrolysis significantly improves the heat transfer process in the high fluid temperature region. During the supercritical-pressure heat transfer process, the flow velocity significantly increases, caused by the drastic variations of thermophysical properties. Under all the tested conditions, the Nusselt number initially increases, consistent with the increased flow velocity, and then slightly decreases in the high fluid temperature region, mainly owing to the decreased heat absorption rate from the endothermic pyrolytic chemical reactions.

Heat Transfer Experiment with Supercritical CO2 Flowing Upward in a Circular Tube

International Nuclear Information System (INIS)

Kim, Hyung Rae; Kim, Hwan Yeol; Song, Jin Ho; Kim, Hee Dong; Bae, Yoon Yeong

2005-01-01

SCWR (SuperCritical Water-cooled Reactor) is one of the six reactor candidates selected in the Gen-IV project, which aims at the development of new reactors with enhanced economy and safety. Heat transfer experiments under supercritical conditions are required in relevant geometries for the proper prediction of thermo-hydraulic phenomena in a reactor core. A heat transfer test loop, named as SPHINX (Supercritical Pressure Heat Transfer Investigation for NeXt generation), has been constructed in KAERI. The loop uses carbon dioxide as a surrogate fluid for water since the critical pressure and temperature of CO 2 are much lower those of water. As a first stage of heat transfer experiments, a single tube test is being performed in the test loop. Controlled parameters for the tests are operating pressure, mass flux, and heat flux. Wall temperatures are measured along the tube. Experimental data are compared with existing correlations

Transesterification of rapeseed and palm oils in supercritical methanol and ethanol

International Nuclear Information System (INIS)

Biktashev, Sh.A.; Usmanov, R.A.; Gabitov, R.R.; Gazizov, R.A.; Gumerov, F.M.; Gabitov, F.R.; Abdulagatov, I.M.; Yarullin, R.S.; Yakushev, I.A.

2011-01-01

The results of the rapeseed and palm oils transesterification with supercritical methanol and ethanol were presented. The studies were performed using the experimental setups which are working in batch and continuous regimes. The effect of reaction conditions (temperature, pressure, oil to alcohol ratio, reaction time) on the biodiesel production (conversion yield) was studied. Also the effect of preliminary ultrasonic treatment (ultrasonic irradiation, emulsification of immiscible oil and alcohol mixture) of the initial reagents (emulsion preparation) on the stage before transesterification reaction conduction on the conversion yield was studied. We found that the preliminary ultrasonic treatment of the initial reagents increases considerably the conversion yield. Optimal technological conditions were determined to be as follows: pressure within 20-30 MPa, temperature within 573-623 K. The optimal values of the oil to alcohol ratio strongly depend on preliminary treatment of the reaction mixture. The study showed that the conversion yield at the same temperature with 96 wt.% of ethanol is higher than with 100 wt.% of methanol. -- Highlights: → The results of the rapeseed and palm oils transesterification with supercritical methanol and ethanol were presented. → The effect of reaction conditions (temperature, pressure, oil to alcohol ratio, reaction time) on the biodiesel production (conversion yield) was studied. → Transesterification of vegetable oil with supercritical alcohols. → Effect of temperature and pressure on conversion yield. → Preliminary ultrasonic treatment of the vegetable oil+methanol mixture.

Computational Modeling of Supercritical and Transcritical Flows

Science.gov (United States)

2017-01-09

Acentric factor I. Introduction Liquid rocket and gas turbine engines operate at high pressures . For gas turbines, the combustor pressurecan be 60 − 100...equation of state for several reduced pressures . The model captures the high density at very low temperatures and the supercritical behavior at high reduced...physical meaning. The temperature range over which the three roots are present is bounded by TL on the low side and TH on the high side. Figure 2: Roots

Selective extraction of hydrocarbons, phosphonates and phosphonic acids from soils by successive supercritical fluid and pressurized liquid extractions.

Science.gov (United States)

Chaudot, X; Tambuté, A; Caude, M

2000-01-14

Hydrocarbons, dialkyl alkylphosphonates and alkyl alkylphosphonic acids are selectively extracted from spiked soils by successive implementation of supercritical carbon dioxide, supercritical methanol-modified carbon dioxide and pressurized water. More than 95% of hydrocarbons are extracted during the first step (pure supercritical carbon dioxide extraction) whereas no organophosphorus compound is evidenced in this first extract. A quantitative extraction of phosphonates is achieved during the second step (methanol-modified supercritical carbon dioxide extraction). Polar phosphonic acids are extracted during a third step (pressurized water extraction) and analyzed by gas chromatography under methylated derivatives (diazomethane derivatization). Global recoveries for these compounds are close to 80%, a loss of about 20% occurring during the derivatization process (co-evaporation with solvent). The developed selective extraction method was successfully applied to a soil sample during an international collaborative exercise.

Thermal circuit and supercritical steam generator of the BGR-300 nuclear power plant

International Nuclear Information System (INIS)

Afanas'ev, B.P.; Godik, I.B.; Komarov, N.F.; Kurochnkin, Yu.P.

1979-01-01

Secondary coolant circuit and a steam generator for supercritical steam parameters of the BGR-300 reactor plant are described. The BGR-300 plant with a 300 MW(e) high-temperature gas-cooled fast reactor is developed as a pilot commercial plant. It is shown that the use of a supercritical pressure steam increases the thermal efficiency of the plant and descreases thermal releases to the environment, permits to use home-made commercial turbine plants of large unit power. The proposed supercritical pressure steam generator has considerable advantages from the viewpoint of heat transfer and hydrodynamical processes

CANDU with supercritical water coolant: conceptual design features

International Nuclear Information System (INIS)

Spinks, N.

1997-01-01

An advanced CANDU reactor, with supercritical water as coolant, has many attractive design features. The pressure exceeds 22 MPa but coolant temperatures in excess of 370 degrees C can be reached without encountering the two-phase region with its associated fuel-dry-out and flow-instability problems. Increased coolant temperature leads to increased plant thermodynamic efficiency reducing unit energy cost through reduced specific capital cost and reduced fueling cost. Increased coolant temperature leads to reduced void reactivity via reduced coolant in-core density. Light water becomes a coolant option. To preserve neutron economy, an advanced fuel channel is needed and is described below. A supercritical-water-cooled CANDU can evolve as fuel capabilities evolve to withstand increasing coolant temperatures. (author)

Oxidation of oily sludge in supercritical water

International Nuclear Information System (INIS)

Cui Baochen; Cui Fuyi; Jing Guolin; Xu Shengli; Huo Weijing; Liu Shuzhi

2009-01-01

The oxidation of oily sludge in supercritical water is performed in a batch reactor at reaction temperatures between 663 and 723 K, the reaction times between 1 and 10 min and pressure between 23 and 27 MPa. Effect of reaction parameters such as reaction time, temperature, pressure, O 2 excess and initial COD on oxidation of oily sludge is investigated. The results indicate that chemical oxygen demand (COD) removal rate of 92% can be reached in 10 min. COD removal rate increases as the reaction time, temperature and initial COD increase. Pressure and O 2 excess have no remarkable affect on reaction. By taking into account the dependence of reaction rate on COD concentration, a global power-law rate expression was regressed from experimental data. The resulting pre-exponential factor was 8.99 x 10 14 (mol L -1 ) -0.405 s -1 ; the activation energy was 213.13 ± 1.33 kJ/mol; and the reaction order for oily sludge (based on COD) is 1.405. It was concluded that supercritical water oxidation (SCWO) is a rapidly emerging oily sludge processing technology.

Selective free radical reactions using supercritical carbon dioxide.

Science.gov (United States)

Cormier, Philip J; Clarke, Ryan M; McFadden, Ryan M L; Ghandi, Khashayar

2014-02-12

We report herein a means to modify the reactivity of alkenes, and particularly to modify their selectivity toward reactions with nonpolar reactants (e.g., nonpolar free radicals) in supercritical carbon dioxide near the critical point. Rate constants for free radical addition of the light hydrogen isotope muonium to ethylene, vinylidene fluoride, and vinylidene chloride in supercritical carbon dioxide are compared over a range of pressures and temperatures. Near carbon dioxide's critical point, the addition to ethylene exhibits critical speeding up, while the halogenated analogues display critical slowing. This suggests that supercritical carbon dioxide as a solvent may be used to tune alkene chemistry in near-critical conditions.

Advanced Supercritical Carbon Dioxide Brayton Cycle Development

Energy Technology Data Exchange (ETDEWEB)

Anderson, Mark [Univ. of Wisconsin, Madison, WI (United States); Sienicki, James [Argonne National Lab. (ANL), Argonne, IL (United States); Moisseytsev, Anton [Argonne National Lab. (ANL), Argonne, IL (United States); Nellis, Gregory [Univ. of Wisconsin, Madison, WI (United States); Klein, Sanford [Univ. of Wisconsin, Madison, WI (United States)

2015-10-21

Fluids operating in the supercritical state have promising characteristics for future high efficiency power cycles. In order to develop power cycles using supercritical fluids, it is necessary to understand the flow characteristics of fluids under both supercritical and two-phase conditions. In this study, a Computational Fluid Dynamic (CFD) methodology was developed for supercritical fluids flowing through complex geometries. A real fluid property module was implemented to provide properties for different supercritical fluids. However, in each simulation case, there is only one species of fluid. As a result, the fluid property module provides properties for either supercritical CO₂ (S-CO₂) or supercritical water (SCW). The Homogeneous Equilibrium Model (HEM) was employed to model the two-phase flow. HEM assumes two phases have same velocity, pressure, and temperature, making it only applicable for the dilute dispersed two-phase flow situation. Three example geometries, including orifices, labyrinth seals, and valves, were used to validate this methodology with experimental data. For the first geometry, S-CO₂ and SCW flowing through orifices were simulated and compared with experimental data. The maximum difference between the mass flow rate predictions and experimental measurements is less than 5%. This is a significant improvement as previous works can only guarantee 10% error. In this research, several efforts were made to help this improvement. First, an accurate real fluid module was used to provide properties. Second, the upstream condition was determined by pressure and density, which determines supercritical states more precise than using pressure and temperature. For the second geometry, the flow through labyrinth seals was studied. After a successful validation, parametric studies were performed to study geometric effects on the leakage rate. Based on these parametric studies, an optimum design strategy for the see

Materials challenges for the supercritical water-cooled reactor (SCWR)

International Nuclear Information System (INIS)

Baindur, S.

2008-01-01

This paper discusses the materials requirements of the Supercritical Water-cooled Reactor (SCWR) which arise from its severe expected operating conditions: (i) Outlet Temperature (to 650 C); (ii) Pressure of 25 MPa for the coolant containment, (iii) Thermochemical stress in the presence of supercritical water, and (iv) Radiative damage (up to 150 dpa for the fast spectrum variant). These operating conditions are reviewed; the phenomenology of materials in the supercritical water environment that create the materials challenges is discussed; knowledge gaps are identified, and efforts to understand material behaviour under the operating conditions expected in the SCWR are described. (author)

Supercritical boiler material selection using fuzzy analytic network process

Directory of Open Access Journals (Sweden)

Saikat Ranjan Maity

2012-08-01

Full Text Available The recent development of world is being adversely affected by the scarcity of power and energy. To survive in the next generation, it is thus necessary to explore the non-conventional energy sources and efficiently consume the available sources. For efficient exploitation of the existing energy sources, a great scope lies in the use of Rankin cycle-based thermal power plants. Today, the gross efficiency of Rankin cycle-based thermal power plants is less than 28% which has been increased up to 40% with reheating and regenerative cycles. But, it can be further improved up to 47% by using supercritical power plant technology. Supercritical power plants use supercritical boilers which are able to withstand a very high temperature (650-720˚C and pressure (22.1 MPa while producing superheated steam. The thermal efficiency of a supercritical boiler greatly depends on the material of its different components. The supercritical boiler material should possess high creep rupture strength, high thermal conductivity, low thermal expansion, high specific heat and very high temperature withstandability. This paper considers a list of seven supercritical boiler materials whose performance is evaluated based on seven pivotal criteria. Given the intricacy and difficulty of this supercritical boiler material selection problem having interactions and interdependencies between different criteria, this paper applies fuzzy analytic network process to select the most appropriate material for a supercritical boiler. Rene 41 is the best supercritical boiler material, whereas, Haynes 230 is the worst preferred choice.

Heat Transfer Experiment with Supercritical CO{sub 2} Flowing Upward in a Circular Tube

Energy Technology Data Exchange (ETDEWEB)

Kim, Hyung Rae; Kim, Hwan Yeol; Song, Jin Ho; Kim, Hee Dong; Bae, Yoon Yeong [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

2005-07-01

SCWR (SuperCritical Water-cooled Reactor) is one of the six reactor candidates selected in the Gen-IV project, which aims at the development of new reactors with enhanced economy and safety. Heat transfer experiments under supercritical conditions are required in relevant geometries for the proper prediction of thermo-hydraulic phenomena in a reactor core. A heat transfer test loop, named as SPHINX (Supercritical Pressure Heat Transfer Investigation for NeXt generation), has been constructed in KAERI. The loop uses carbon dioxide as a surrogate fluid for water since the critical pressure and temperature of CO{sub 2} are much lower those of water. As a first stage of heat transfer experiments, a single tube test is being performed in the test loop. Controlled parameters for the tests are operating pressure, mass flux, and heat flux. Wall temperatures are measured along the tube. Experimental data are compared with existing correlations.

Experimental investigation of heat transfer to supercritical pressure carbon dioxide in a horizontal pipe

International Nuclear Information System (INIS)

Adebiyi, G.A.; Hall, W.B.

1976-01-01

Results obtained in an experimental investigation of heat transfer to supercritical and subcritical pressure CO 2 flowing through a uniformly heated 22.14 mm I.D. horizontal pipe are presented. The experimental work covers a flow inlet Reynolds number range of about 2 x 10 4 to 2 x 10 5 . Marked peripheral temperature variations are obtained which represent the influence of buoyancy. Comparison with buoyancy free data shows that heat transfer at the bottom of the pipe in enhanced and at the top is reduced by buoyancy. Criteria proposed by Jackson and Petukhov indicate that buoyancy effects would be expected under the conditions of all the experiments. (autho)

Application of GC–MS chromatography for the analysis of the oil fractions extracted by supercritical CO2 at high pressure

DEFF Research Database (Denmark)

Rudyk, Svetlana Nikolayevna; Spirov, Pavel; Søgaard, Erik Gydesen

2013-01-01

GC–MS chromatographic analysis has been applied for the investigation of the fractions of oil extracted by supercritical carbon dioxide at a temperature of 60 °C and at pressure values ranging from 22 to 56 MPa. The observations revealed, that the whole extraction process is clearly reflected...... in the chromatograms, demonstrating how the heavier hydrocarbon fractions were gradually involved in the extraction process. The shape of the chromatograms alters with increasing pressure from triangle to trapezoid, approaching the shape of the chromatogram of the crude oil. The observation of the fingerprints...

Modeling the outflow of liquid with initial supercritical parameters using the relaxation model for condensation

Directory of Open Access Journals (Sweden)

Lezhnin Sergey

2017-01-01

Full Text Available The two-temperature model of the outflow from a vessel with initial supercritical parameters of medium has been realized. The model uses thermodynamic non-equilibrium relaxation approach to describe phase transitions. Based on a new asymptotic model for computing the relaxation time, the outflow of water with supercritical initial pressure and super- and subcritical temperatures has been calculated.

Continuous production of biodiesel under supercritical methyl acetate conditions: Experimental investigation and kinetic model.

Science.gov (United States)

Farobie, Obie; Matsumura, Yukihiko

2017-10-01

In this study, biodiesel production by using supercritical methyl acetate in a continuous flow reactor was investigated for the first time. The aim of this study was to elucidate the reaction kinetics of biodiesel production by using supercritical methyl. Experiments were conducted at various reaction temperatures (300-400°C), residence times (5-30min), oil-to-methyl acetate molar ratio of 1:40, and a fixed pressure of 20MPa. Reaction kinetics of biodiesel production with supercritical methyl acetate was determined. Finally, biodiesel yield obtained from this method was compared to that obtained with supercritical methanol, ethanol, and MTBE (methyl tertiary-butyl ether). The results showed that biodiesel yield with supercritical methyl acetate increased with temperature and time. The developed kinetic model was found to fit the experimental data well. The reactivity of supercritical methyl acetate was the lowest, followed by that of supercritical MTBE, ethanol, and methanol, under the same conditions. Copyright © 2017. Published by Elsevier Ltd.

Core design of a high breeding fast reactor cooled by supercritical pressure light water

Energy Technology Data Exchange (ETDEWEB)

Someya, Takayuki, E-mail: russell@ruri.waseda.jp; Yamaji, Akifumi

2016-01-15

Highlights: • Core design concept of supercritical light water cooled fast breeding reactor is developed. • Compound system doubling time (CSDT) is applied for considering an appropriate target of breeding performance. • Breeding performance is improved by reducing fuel rod diameter of the seed assembly. • Core pressure loss is reduced by enlarging the coolant channel area of the seed assembly. - Abstract: A high breeding fast reactor core concept, cooled by supercritical pressure light water has been developed with fully-coupled neutronics and thermal-hydraulics core calculations, which takes into account the influence of core pressure loss to the core neutronics characteristics. Design target of the breeding performance has been determined to be compound system doubling time (CSDT) of less than 50 years, by referring to the relationship of energy consumption and economic growth rate of advanced countries such as the G7 member countries. Based on the past design study of supercritical water cooled fast breeder reactor (Super FBR) with the concept of tightly packed fuel assembly (TPFA), further improvement of breeding performance and reduction of core pressure loss are investigated by considering different fuel rod diameters and coolant channel geometries. The sensitivities of CSDT and the core pressure loss with respect to major core design parameters have been clarified. The developed Super FBR design concept achieves fissile plutonium surviving ratio (FPSR) of 1.028, compound system doubling time (CSDT) of 38 years and pressure loss of 1.02 MPa with positive density reactivity (negative void reactivity). The short CSDT indicates high breeding performance, which may enable installation of the reactors at a rate comparable to energy growth rate of developed countries such as G7 member countries.

Experimental study of elliptical jet from supercritical to subcritical conditions using planar laser induced fluorescence

Energy Technology Data Exchange (ETDEWEB)

Muthukumaran, C. K.; Vaidyanathan, Aravind, E-mail: aravind7@iist.ac.in [Department of Aerospace Engineering, Indian Institute of Space Science and Technology, Trivandrum, Kerala 695547 (India)

2015-03-15

The study of fluid jet dynamics at supercritical conditions involves strong coupling between fluid dynamic and thermodynamic phenomena. Beyond the critical point, the liquid-vapor coexistence ceases to exist, and the fluid exists as a single phase known as supercritical fluid with its properties that are entirely different from liquids and gases. At the critical point, the liquids do not possess surface tension and latent heat of evaporation. Around the critical point, the fluid undergoes large changes in density and possesses thermodynamic anomaly like enhancement in thermal conductivity and specific heat. In the present work, the transition of the supercritical and near-critical elliptical jet into subcritical as well as supercritical environment is investigated experimentally with nitrogen and helium as the surrounding environment. Under atmospheric condition, a liquid jet injected from the elliptical orifice exhibits axis switching phenomena. As the injection temperature increases, the axis switching length also increases. Beyond the critical temperature, the axis switching is not observed. The investigation also revealed that pressure plays a major role in determining the thermodynamic transition of the elliptical jet only for the case of supercritical jet injected into subcritical chamber conditions. At larger pressures, the supercritical jet undergoes disintegration and formation of droplets in the subcritical environment is observed. However, for supercritical jet injection into supercritical environment, the gas-gas like mixing behavior is observed.

Experimental study of elliptical jet from supercritical to subcritical conditions using planar laser induced fluorescence

International Nuclear Information System (INIS)

Muthukumaran, C. K.; Vaidyanathan, Aravind

2015-01-01

The study of fluid jet dynamics at supercritical conditions involves strong coupling between fluid dynamic and thermodynamic phenomena. Beyond the critical point, the liquid-vapor coexistence ceases to exist, and the fluid exists as a single phase known as supercritical fluid with its properties that are entirely different from liquids and gases. At the critical point, the liquids do not possess surface tension and latent heat of evaporation. Around the critical point, the fluid undergoes large changes in density and possesses thermodynamic anomaly like enhancement in thermal conductivity and specific heat. In the present work, the transition of the supercritical and near-critical elliptical jet into subcritical as well as supercritical environment is investigated experimentally with nitrogen and helium as the surrounding environment. Under atmospheric condition, a liquid jet injected from the elliptical orifice exhibits axis switching phenomena. As the injection temperature increases, the axis switching length also increases. Beyond the critical temperature, the axis switching is not observed. The investigation also revealed that pressure plays a major role in determining the thermodynamic transition of the elliptical jet only for the case of supercritical jet injected into subcritical chamber conditions. At larger pressures, the supercritical jet undergoes disintegration and formation of droplets in the subcritical environment is observed. However, for supercritical jet injection into supercritical environment, the gas-gas like mixing behavior is observed

Influence of reaction conditions and type of alcohol on biodiesel yields and process economics of supercritical transesterification

International Nuclear Information System (INIS)

Micic, Radoslav D.; Tomić, Milan D.; Kiss, Ferenc E.; Nikolić-Djorić, Emilija B.; Simikić, Mirko Ð.

2014-01-01

Highlights: • Transesterification in supercritical methanol, ethanol and 1-propanol investigated. • Effect of alcohol, reaction temperature, pressure and time on yields analyzed. • Temperature has the highest impact on yield, followed by time and pressure. • Direct material and energy costs for each of the production alternatives estimated. • Lowest costs are achieved at highest yields even at very low oil prices. - Abstract: Experiments with transesterification of rapeseed oil in supercritical alcohols (methanol, ethanol and 1-propanol) were carried out in a batch reactor at various reaction temperatures (250–350 °C), working pressure (8–12 MPa), reaction time, and constant 42:1 alcohol to oil molar ratio. Influence of different alcohols and reaction conditions on biodiesel yield was investigated using linear multiple regression models. Temperature had the highest impact on yields, followed by reaction time and pressure. With increased molecular weight of alcohols, relative importance of temperature for explanation of yields decreased and relative importance of time and pressure increased. Economic assessment has revealed that transesterification in supercritical methanol has the lowest direct material and energy costs. Yield has crucial impact on process economics. Direct costs decrease with increase in biodiesel yields. Even at very low prices of oil feedstock the lowest cost is achieved at the highest yield

Extension of the supercritical carbon dioxide Brayton cycle for application to the Very High Temperature Reactor

International Nuclear Information System (INIS)

Moisseytsev, A.; Sienicki, J. J.

2010-01-01

An investigation has been carried out of the feasibility of applying the supercritical carbon dioxide (S-CO 2 ) Brayton cycle to the Very High Temperature Reactor (VHTR). Direct application of the standard S-CO 2 recompression cycle to the VHTR was found to be challenging because of the mismatch in the inherent temperature drops across the He and CO 2 sides of the reactor heat exchanger resulting in a relatively low cycle efficiency of 45 % compared to 48 % for a direct helium cycle. Two approaches consisting of either a cascaded cycle arrangement with three separate cascaded S-CO 2 cycles or, alternately, operation of a single S-CO 2 cycle with the minimum pressure below the critical pressure and the minimum temperature above the critical temperature have been identified and shown to successfully enable the S-CO 2 Brayton cycle to be adapted to the VHTR such that the benefits of the higher S-CO 2 cycle efficiency can be realized. For both approaches, S-CO 2 cycle efficiencies in excess of 49 % are calculated. (authors)

Size-selective separation of polydisperse gold nanoparticles in supercritical ethane.

Science.gov (United States)

Williams, Dylan P; Satherley, John

2009-04-09

The aim of this study was to use supercritical ethane to selectively disperse alkanethiol-stabilized gold nanoparticles of one size from a polydisperse sample in order to recover a monodisperse fraction of the nanoparticles. A disperse sample of metal nanoparticles with diameters in the range of 1-5 nm was prepared using established techniques then further purified by Soxhlet extraction. The purified sample was subjected to supercritical ethane at a temperature of 318 K in the pressure range 50-276 bar. Particles were characterized by UV-vis absorption spectroscopy, TEM, and MALDI-TOF mass spectroscopy. The results show that with increasing pressure the dispersibility of the nanoparticles increases, this effect is most pronounced for smaller nanoparticles. At the highest pressure investigated a sample of the particles was effectively stripped of all the smaller particles leaving a monodisperse sample. The relationship between dispersibility and supercritical fluid density for two different size samples of alkanethiol-stabilized gold nanoparticles was considered using the Chrastil chemical equilibrium model.

Supercritical fluid technology for energy and environmental applications

CERN Document Server

Anikeev, Vladimir

2014-01-01

Supercritical Fluid Technology for Energy and Environmental Applications covers the fundamental principles involved in the preparation and characterization of supercritical fluids (SCFs) used in the energy production and other environmental applications. Energy production from diversified resources - including renewable materials - using clean processes can be accomplished using technologies like SCFs. This book is focused on critical issues scientists and engineers face in applying SCFs to energy production and environmental protection, the innovative solutions they have found, and the challenges they need to overcome. The book also covers the basics of sub- and supercritical fluids, like the thermodynamics of phase and chemical equilibria, mathematical modeling, and process calculations. A supercritical fluid is any substance at a temperature and pressure above its critical point where distinct liquid and gas phases do not exist. At this state the compound demonstrates unique properties, which can be "fine...

MIF-SCD computer code for thermal hydraulic calculation of supercritical water cooled reactor core

International Nuclear Information System (INIS)

Galina P Bogoslovskaia; Alexander A Karpenko; Pavel L Kirillov; Alexander P Sorokin

2005-01-01

Full text of publication follows: Supercritical pressure power plants constitute the basis of heat power engineering in many countries to day. Starting from a long-standing experience of their operation, it is proposed to develop a new type of fast breeder reactor cooled by supercritical water, which enables the economical indices of NPP to be substantially improved. In the Thermophysical Department of SSC RF-IPPE, an attempt is made to provide thermal-hydraulic validation of the reactor under discussion. The paper presents the results of analysis of the thermal-hydraulic characteristics of fuel subassemblies cooled by supercritical water based on subchannel analysis. Modification of subchannel code MIF - MIF-SCD Code - developed in the SSC RF IPPE is designed as block code and permits one to calculate the coolant temperature and velocity distributions in fuel subassembly channels, the temperature of fuel pin claddings and fuel subassembly wrapper under conditions of irregular geometry and non-uniform axial and radial power generation. The thermal hydraulics under supercritical pressure of water exhibits such peculiarities as abrupt variation of the thermal physical properties in the range of pseudo-critical temperature, the absence of such phenomenon as the critical heat flux which can lead to fuel element burnout in WWERs. As compared with subchannel code for light water, in order to take account of the variation of the coolant properties versus temperature in more detail, a block for evaluating the thermal physical properties of supercritical water versus the local coolant temperature in the fuel subassembly channels was added. The peculiarities of the geometry and power generation in the fuel subassembly of the supercritical reactor are considered as well in special blocks. The results of calculations have shown that considerable preheating of supercritical coolant (several hundreds degrees) can occur in the fuel subassembly. The test calculations according to

Experimental study of elliptical jet from sub to supercritical conditions

Energy Technology Data Exchange (ETDEWEB)

Muthukumaran, C. K.; Vaidyanathan, Aravind, E-mail: aravind7@iist.ac.in [Department of Aerospace Engineering, Indian Institute of Space Science and Technology, Trivandrum, Kerala 695547 (India)

2014-04-15

The jet mixing at supercritical conditions involves fluid dynamics as well as thermodynamic phenomena. All the jet mixing studies at critical conditions to the present date have focused only on axisymmetric jets. When the liquid jet is injected into supercritical environment, the thermodynamic transition could be well understood by considering one of the important fluid properties such as surface tension since it decides the existence of distinct boundary between the liquid and gaseous phase. It is well known that an elliptical liquid jet undergoes axis-switching phenomena under atmospheric conditions due to the presence of surface tension. The experimental investigations were carried out with low speed elliptical jet under supercritical condition. Investigation of the binary component system with fluoroketone jet and N{sub 2} gas as environment shows that the surface tension force dominates for a large downstream distance, indicating delayed thermodynamic transition. The increase in pressure to critical state at supercritical temperature is found to expedite the thermodynamic transition. The ligament like structures has been observed rather than droplets for supercritical pressures. However, for the single component system with fluoroketone jet and fluoroketone environment shows that the jet disintegrates into droplets as it is subjected to the chamber conditions even for the subcritical pressures and no axis switching phenomenon is observed. For a single component system, as the pressure is increased to critical state, the liquid jet exhibits gas-gas like mixing behavior and that too without exhibiting axis-switching behavior.

179 Extraction of Coal-tar Pitch by Supercritical Carbon Dioxide ...

African Journals Online (AJOL)

Meyer

Several extractions of coal-tar pitch were performed using supercritical fluid ..... pressure and temperature, unlike exhaustive extraction, which involves a change in ... mechanism that is operative on extracting coal-tar pitch components with.

Selective chelation-supercritical fluid extraction of metal ions from waste materials

International Nuclear Information System (INIS)

Wai, C.N.; Laintz, K.E.; Yonker, C.R.

1993-01-01

The removal of toxic organics, metals, and radioisotopes from solids or liquids is a major concern in the treatment of industrial and nuclear wastes. For this reason, developing methods for selective separation of toxic metals and radioactive materials from solutions of complex matrix is an important problem in environmental research. Recent developments indicate supercritical fluids are good solvents for organic compounds. Many gases become supercritical fluids under moderate temperatures and pressures. For example, the critical temperature and pressure of carbon dioxide are 31 degrees C and 73 atm, respectively. The high diffusivity, low viscosity, and T-P dependence of solvent strength are some attractive properties of supercritical fluid extraction (SFE). Since CO 2 offers the additional benefits of stability and non-toxicity, the SFE technique avoids generation of organic liquid waste and exposure of personnel to toxic solvents. While direct extraction of metal ions by supercritical fluids is highly inefficient, these ions when complexed with organic ligands become quite soluble in supercritical fluids. Specific ligands can be used to achieve selective extraction of metal ions in this process. After SFE, the fluid phase can be depressurized for precipitation of the metal chelates and recycled. The ligand can also be regenerated for repeated use. The success of this selective chelation-supercritical fluid extraction (SC-SFE) process depends on a number of factors including the efficiencies of the selective chelating agents, solubilities of metal chelates in supercritical fluids, rate of extraction, ease of regeneration of the ligands, etc. In this report, the authors present recent results on the studies of the solubilities of metal chelates in supercritical CO 2 , experimental ions from aqueous solution, and the development of selective chelating agents (ionizable crown ethers) for the extraction of lanthanides and actinides

Supercritical CO2 Brayton cycle compression and control near the critical point

International Nuclear Information System (INIS)

Wright, S. A.; Fuller, R.; Noall, J.; Radel, R.; Vernon, M. E.; Pickard, P. S.

2008-01-01

This report describes the supercritical compression and control issues, the analysis, and the measured test results of a small-scale supercritical CO 2 (S-CO 2 ) compression test-loop. The test loop was developed by Sandia and is described in a companion paper in this conference. The results of these experiments will for the first time evaluate and experimentally demonstrate supercritical compression and the required compressor inlet control approaches on an appropriate scale in a series of test loops at Sandia National Laboratories. The Sandia effort is focused on the main compressor of a supercritical Brayton loop while a separate DOE Gen lV program focus is on studying similar behavior in re-compression Brayton cycles that have dual compressors. One of the main goals of this program is to develop and demonstrate the ability to design, operate, and control the supercritical compression process near the critical point due to highly non-linear behavior near this point. This Sandia supercritical test-loop uses a 50 kW radial compressor to pump supercritical CO 2 (S-CO 2 ) through an orifice and through a water-cooled gas-chiller. At the design point the compressor flow rate is 3.5 kg/s, the inlet pressure is 7, 690 kPa, the pressure ratio is 1.8, the inlet temperature is 305 K, and the shaft speed is 75, 000 rpm. The purpose of the loop is to study the compression and control issues near the critical point. To study compression we intend to compare the design code predictions for efficiency and change in enthalpy (or pressure ratio / head) of the radial compressor with the measured results from actual tests. In the tests the inlet flow, temperature, and pressure, will be varied around the critical point of CO 2 (Tc=304.2 K, and Pc=7.377 MPa). To study control, the test loop will use a variety of methods including inventory control, shaft speed control, and cooling water flow rate, and cooling water temperature control methods to set the compressor inlet temperature

Design of experimental setup for supercritical CO2 jet under high ambient pressure conditions

Science.gov (United States)

Shi, Huaizhong; Li, Gensheng; He, Zhenguo; Wang, Haizhu; Zhang, Shikun

2016-12-01

With the commercial extraction of hydrocarbons in shale and tight reservoirs, efficient methods are needed to accelerate developing process. Supercritical CO2 (SC-CO2) jet has been considered as a potential way due to its unique fluid properties. In this article, a new setup is designed for laboratory experiment to research the SC-CO2 jet's characteristics in different jet temperatures, pressures, standoff distances, ambient pressures, etc. The setup is composed of five modules, including SC-CO2 generation system, pure SC-CO2 jet system, abrasive SC-CO2 jet system, CO2 recovery system, and data acquisition system. Now, a series of rock perforating (or case cutting) experiments have been successfully conducted using the setup about pure and abrasive SC-CO2 jet, and the results have proven the great perforating efficiency of SC-CO2 jet and the applications of this setup.

Geological model of supercritical geothermal reservoir related to subduction system

Science.gov (United States)

Tsuchiya, Noriyoshi

2017-04-01

Following the Great East Japan Earthquake and the accident at the Fukushima Daiichi Nuclear power station on 3.11 (11th March) 2011, geothermal energy came to be considered one of the most promising sources of renewable energy for the future in Japan. The temperatures of geothermal fields operating in Japan range from 200 to 300 °C (average 250 °C), and the depths range from 1000 to 2000 m (average 1500 m). In conventional geothermal reservoirs, the mechanical behavior of the rocks is presumed to be brittle, and convection of the hydrothermal fluid through existing network is the main method of circulation in the reservoir. In order to minimize induced seismicity, a rock mass that is "beyond brittle" is one possible candidate, because the rock mechanics of "beyond brittle" material is one of plastic deformation rather than brittle failure. Supercritical geothermal resources could be evaluated in terms of present volcanic activities, thermal structure, dimension of hydrothermal circulation, properties of fracture system, depth of heat source, depth of brittle factures zone, dimension of geothermal reservoir. On the basis of the GIS, potential of supercritical geothermal resources could be characterized into the following four categories. 1. Promising: surface manifestation d shallow high temperature, 2 Probability: high geothermal gradient, 3 Possibility: Aseismic zone which indicates an existence of melt, 4 Potential : low velocity zone which indicates magma input. Base on geophysical data for geothermal reservoirs, we have propose adequate tectonic model of development of the supercritical geothermal reservoirs. To understand the geological model of a supercritical geothermal reservoir, granite-porphyry system, which had been formed in subduction zone, was investigated as a natural analog of the supercritical geothermal energy system. Quartz veins, hydrothermal breccia veins, and glassy veins are observed in a granitic body. The glassy veins formed at 500-550 �

RELAP5-3D Code for Supercritical-Pressure Light-Water-Cooled Reactors

Energy Technology Data Exchange (ETDEWEB)

Riemke, Richard Allan; Davis, Cliff Bybee; Schultz, Richard Raphael

2003-04-01

The RELAP5-3D computer program has been improved for analysis of supercritical-pressure, light-water-cooled reactors. Several code modifications were implemented to correct code execution failures. Changes were made to the steam table generation, steam table interpolation, metastable states, interfacial heat transfer coefficients, and transport properties (viscosity and thermal conductivity). The code modifications now allow the code to run slow transients above the critical pressure as well as blowdown transients (modified Edwards pipe and modified existing pressurized water reactor model) that pass near the critical point.

Production of FAME by palm oil transesterification via supercritical methanol technology

International Nuclear Information System (INIS)

Tan, Kok Tat; Lee, Keat Teong; Mohamed, Abdul Rahman

2009-01-01

The present study employed non-catalytic supercritical methanol technology to produce biodiesel from palm oil. The research was carried out in a batch-type tube reactor and heated beyond supercritical temperature and pressure of methanol, which are at 239 o C and 8.1 MPa respectively. The effects of temperature, reaction time and molar ratio of methanol to palm oil on the yield of fatty acid methyl esters (FAME) or biodiesel were investigated. The results obtained showed that non-catalytic supercritical methanol technology only required a mere 20 min reaction time to produce more than 70% yield of FAME. Compared to conventional catalytic methods, which required at least 1 h reaction time to obtain similar yield, supercritical methanol technology has been shown to be superior in terms of time and energy consumption. Apart from the shorter reaction time, it was found that separation and purification of the products were simpler since no catalyst is involved in the process. Hence, formation of side products such as soap in catalytic reactions does not occur in the supercritical methanol method.

Heat Transfer Characteristics of CO2 at Supercritical Pressure in a Vertical Circular Tube

International Nuclear Information System (INIS)

Yoo, Tae Ho; Bae, Yoon Yong; Kim, Hwan Yeol

2011-01-01

At supercritical pressure, the physical properties of fluid change substantially and the heat transfer at a temperature similar to the critical or pseudo-critical temperature improves considerably: however, the heat transfer may deteriorate due to a sudden increase in the wall temperature at a certain condition of a mass and heat flux. In this study, the heat transfer rates in CO 2 flowing vertically upward and downward in a circular tube with a diameter of 4.57 mm under various conditions were calculated by measuring the temperature of the outer wall of the tube. The published heat transfer correlations(6,7) were analyzed by comparing their prediction values with 7,250 experimental data. By introducing a buoyancy parameter, a heat transfer correlation, which could be applied only to a normal heat transfer regime, was extended such that it can be applied to regime of heat transfer deterioration. The published criteria for heat transfer deterioration(9-12) were evaluated against the conditions obtained from the experiment in this study

Thermodynamic Analysis of a Supercritical Mercury Power Cycle

Energy Technology Data Exchange (ETDEWEB)

Roberts, Jr, A S

1969-04-15

An heat engine is considered which employs supercritical mercury as the working fluid and a magnetohydrodynamic (MHD) generator for thermal to electrical energy conversion. The main thrust of the paper is power cycle thermodynamics, where constraints are imposed by utilizing a MHD generator operating between supercritical, electrically conducting states of the working fluid; and, pump work is accomplished with liquid mercury. The temperature range is approximately 300 to 2200 K and system pressure is > 1,500 atm. Equilibrium and transport properties are carefully considered since these are known to vary radically in the vicinity of the critical point, which is found near the supercritical states of interest. A maximum gross plant efficiency is 20% with a regenerator effectiveness of 90% and greater, a cycle pressure ratio of two, and with highly efficient pump and generator. Certain specified cycle irreversibilities and others such as heat losses and heat exchanger pressure drops, which are not accounted for explicitly, reduce the gross plant efficiency to a few per cent. Experimental efforts aimed at practical application of the power cycle are discouraged by the marginal thermodynamic performance predicted by this study, unless such applications are insensitive to gross cycle efficiency.

Thermodynamic Analysis of a Supercritical Mercury Power Cycle

International Nuclear Information System (INIS)

Roberts, A.S. Jr.

1969-04-01

An heat engine is considered which employs supercritical mercury as the working fluid and a magnetohydrodynamic (MHD) generator for thermal to electrical energy conversion. The main thrust of the paper is power cycle thermodynamics, where constraints are imposed by utilizing a MHD generator operating between supercritical, electrically conducting states of the working fluid; and, pump work is accomplished with liquid mercury. The temperature range is approximately 300 to 2200 K and system pressure is > 1,500 atm. Equilibrium and transport properties are carefully considered since these are known to vary radically in the vicinity of the critical point, which is found near the supercritical states of interest. A maximum gross plant efficiency is 20% with a regenerator effectiveness of 90% and greater, a cycle pressure ratio of two, and with highly efficient pump and generator. Certain specified cycle irreversibilities and others such as heat losses and heat exchanger pressure drops, which are not accounted for explicitly, reduce the gross plant efficiency to a few per cent. Experimental efforts aimed at practical application of the power cycle are discouraged by the marginal thermodynamic performance predicted by this study, unless such applications are insensitive to gross cycle efficiency

Development of correlations for combustion modelling with supercritical surrogate jet fuels

Directory of Open Access Journals (Sweden)

Raja Sekhar Dondapati

2017-12-01

Full Text Available Supercritical fluid technology finds its application in almost all engineering aspects in one or other way. Technology of clean jet fuel combustion is also seeing supercritical fluids as one of their contender in order to mitigate the challenges related to global warming and health issues occurred due to unwanted emissions which are found to be the by-products in conventional jet engine combustion. As jet fuel is a blend of hundred of hydrocarbons, thus estimation of chemical kinetics and emission characteristics while simulation become much complex. Advancement in supercritical jet fuel combustion technology demands reliable property statistics of jet fuel as a function temperature and pressure. Therefore, in the present work one jet fuel surrogate (n-dodecane which has been recognized as the constituent of real jet fuel is studied and thermophysical properties of each is evaluated in the supercritical regime. Correlation has been developed for two transport properties namely density and viscosity at the critical pressure and over a wide range of temperatures (TC + 100 K. Further, to endorse the reliability of the developed correlation, two arithmetical parameters have been evaluated which illustrates an outstanding agreement between the data obtained from online NIST Web-Book and the developed correlation.

Convective heat transfer in supercritical flows of CO_2 in tubes with and without flow obstacles

International Nuclear Information System (INIS)

Eter, Ahmad; Groeneveld, Dé; Tavoularis, Stavros

2017-01-01

Highlights: • Measurements of supercritical heat transfer in tubes equipped with obstacles were obtained and compared with results in base tubes. • In general, flow obstacles improve supercritical heat transfer, but under certain conditions have a negative effect on it. • New correlations describing obstacle-enhanced supercritical heat transfer in the liquid-like and gas-like regimes are fitted to the data. - Abstract: Heat transfer measurements to CO_2-cooled tubes with and without flow obstacles at supercritical pressures were obtained at the University of Ottawa’s supercritical pressure test facility. The effects of obstacle geometry (obstacle pitch, obstacle shape, flow blockage) on the wall temperature and heat transfer coefficient were investigated. Tests were performed for vertical upward flow in a directly heated 8 mm ID tube for a pressure range from 7.69 to 8.36 MPa, a mass flux range from 200 to 1184 kg/m"2 s, and a heat flux range from 1 to 175 kW/m"2. The results are presented graphically in plots of wall temperature and heat transfer coefficient vs. bulk specific enthalpy of the fluid. The effects of flow parameters and flow obstacle geometry on supercritical heat transfer for both normal and deteriorated heat transfer are discussed. A comparison of the measurements with leading prediction methods for supercritical heat transfer in bare tubes and for spacer effects is also presented. The optimum increase in heat transfer coefficient was found to be for blunt obstacles, having a large flow blockage, and a short obstacle pitch.

Heat Transfer Phenomena of Supercritical Fluids

Energy Technology Data Exchange (ETDEWEB)

Krau, Carmen Isabella; Kuhn, Dietmar; Schulenberg, Thomas [Forschungszentrum Karlsruhe, Institute for Nuclear and Energy Technologies, 76021 Karlsruhe (Germany)

2008-07-01

In concepts for supercritical water cooled reactors, the reactor core is cooled and moderated by water at supercritical pressures. The significant temperature dependence of the fluid properties of water requires an exact knowledge of the heat transfer mechanism to avoid fuel pin damages. Near the pseudo-critical point a deterioration of heat transfer might happen. Processes, that take place in this case, are not fully understood and are due to be examined systematically. In this paper a general overview on the properties of supercritical water is given, experimental observations of different authors will be reviewed in order to identify heat transfer phenomena and onset of occurrence. The conceptional design of a test rig to investigate heat transfer in the boundary layer will be discussed. Both, water and carbon dioxide, may serve as operating fluids. The loop, including instrumentation and safety devices, is shown and suitable measuring methods are described. (authors)

Supercritical carbon dioxide extraction of oil from Clanis bilineata ...

African Journals Online (AJOL)

AJL

2012-02-16

Feb 16, 2012 ... temperature, 35°C; pressure, 25 MPa; supercritical CO2 flow rate, 20 L/min and time, 60 min. ... methyl esters were recovered after solvent evaporation in vacuum ... Effect of time on extraction of the oil from C. bilineata larvae.

Particle Formation by Supercritical Fluid Extraction and Expansion Process

Directory of Open Access Journals (Sweden)

Sujuan Pan

2013-01-01

Full Text Available Supercritical fluid extraction and expansion (SFEE patented technology combines the advantages of both supercritical fluid extraction (SFE and rapid expansion of supercritical solution (RESS with on-line coupling, which makes the nanoparticle formation feasible directly from matrix such as Chinese herbal medicine. Supercritical fluid extraction is a green separation technology, which has been developed for decades and widely applied in traditional Chinese medicines or natural active components. In this paper, a SFEE patented instrument was firstly built up and controlled by LABVIEW work stations. Stearic acid was used to verify the SFEE process at optimized condition; via adjusting the preexpansion pressure and temperature one can get different sizes of particles. Furthermore, stearic acid was purified during the SFEE process with HPLC-ELSD detecting device; purity of stearic acid increased by 19%, and the device can purify stearic acid.

Challenges of selecting materials for the process of biomass gasification in supercritical water

Energy Technology Data Exchange (ETDEWEB)

Boukis, N.; Habicht, W.; Hauer, E.; Dinjus, E. [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany). Inst. fuer Technische Chemie

2010-07-01

A new process for the gasification of wet biomass is the reaction in supercritical water. The product is a combustible gas, rich in hydrogen with a high calorific value. The reaction is performed under high temperatures - up to 700 C - and pressures up to 30 MPa. The combination of these physical conditions and the corrosive environment is very demanding for the construction materials of the reactor. Only few alloys exhibit the required mechanical properties, especially the mechanical strength at temperatures higher than 600 C. Ni-Base alloys like alloy 625 can be applied up to a temperature of 700 C and are common materials for application under supercritical water conditions. During gasification experiments with corn silage and other biomasses, corrosion of the reactor material alloy 625 appears. The gasification of an aqueous methanol solution in supercritical water at temperatures up to 600 C and 25 - 30 MPa pressure results in an product gas rich in hydrogen, carbon dioxide and some methane. Alloy 625 shows very low corrosion rates in this environment. It is obvious that the heteroatoms and salts present in biomass cause corrosion of the reactor material. (orig.)

Dynamics, thermodynamics and structure of liquids and supercritical fluids: crossover at the Frenkel line

Science.gov (United States)

Fomin, Yu D.; Ryzhov, V. N.; Tsiok, E. N.; Proctor, J. E.; Prescher, C.; Prakapenka, V. B.; Trachenko, K.; Brazhkin, V. V.

2018-04-01

We review recent work aimed at understanding dynamical and thermodynamic properties of liquids and supercritical fluids. The focus of our discussion is on solid-like transverse collective modes, whose evolution in the supercritical fluids enables one to discuss the main properties of the Frenkel line separating rigid liquid-like and non-rigid gas-like supercritical states. We subsequently present recent experimental evidence of the Frenkel line showing that structural and dynamical crossovers are seen at a pressure and temperature corresponding to the line as predicted by theory and modelling. Finally, we link dynamical and thermodynamic properties of liquids and supercritical fluids by the new calculation of liquid energy governed by the evolution of solid-like transverse modes. The disappearance of those modes at high temperature results in the observed decrease of heat capacity.

A Heat Transfer Correlation in a Vertical Upward Flow of CO2 at Supercritical Pressures

International Nuclear Information System (INIS)

Kim, Hyung Rae; Bae, Yoon Yeong; Song, Jin Ho; Kim, Hwan Yeol

2006-01-01

Heat transfer data has been collected in the heat transfer test loop, named SPHINX (Supercritical Pressure Heat Transfer Investigation for NeXt generation), in KAERI. The facility primarily aims at the generation of heat transfer data in the flow conditions and geometries relevant to SCWR (SuperCritical Water-cooled Reactor). The produced data will aid the thermohydraulic design of a reactor core. The loop uses carbon dioxide, and later the results will be scaled to the water flows. The heat transfer data has been collected for a vertical upward flow in a circular tube with varying mass fluxes, heat fluxes, and operating pressures. The results are compared with the existing correlations and a new correlation is proposed by fine-tuning the one of the existing correlations

Heat transfer in a seven-rod test bundle with supercritical pressure water (1). Experiments

International Nuclear Information System (INIS)

Ezato, Koichiro; Seki, Yohji; Dairaku, Masayuki; Suzuki, Satoshi; Enoeda, Mikio; Akiba, Masato; Mori, H.; Oka, Y.

2009-01-01

Heat transfer experiments in a seven-rod test bundle with supercritical pressure water has been carried out. The pressure drop and heat transfer coefficients (HTCs) in the test section are evaluated. In the present limited conditions, difference between HTCs at the surface facing the sub-channel center and those at the surface in the narrowest region between rods is not observed. (author)

European supercritical water cooled reactor

International Nuclear Information System (INIS)

Schulenberg, T.; Starflinger, J.; Marsault, P.; Bittermann, D.; Maraczy, C.; Laurien, E.; Lycklama a Nijeholt, J.A.; Anglart, H.; Andreani, M.; Ruzickova, M.; Toivonen, A.

2011-01-01

Highlights: → The HPLWR reactor design is an example of a supercritical water cooled reactor. → Cladding material tests have started but materials are not yet satisfactory. → Numerical heat transfer predictions are promising but need further validation. → The research project is most suited for nuclear education and training. - Abstract: The High Performance Light Water Reactor (HPLWR), how the European Supercritical Water Cooled Reactor is called, is a pressure vessel type reactor operated with supercritical water at 25 MPa feedwater pressure and 500 o C average core outlet temperature. It is designed and analyzed by a European consortium of 10 partners and 3 active supporters from 8 Euratom member states in the second phase of the HPLWR project. Most emphasis has been laid on a core with a thermal neutron spectrum, consisting of small fuel assemblies in boxes with 40 fuel pins each and a central water box to improve the neutron moderation despite the low coolant density. Peak cladding temperatures of the fuel rods have been minimized by heating up the coolant in three steps with intermediate coolant mixing. The containment design with its safety and residual heat removal systems is based on the latest boiling water reactor concept, but with different passive high pressure coolant injection systems to cause a forced convection through the core. The design concept of the steam cycle is indicating the envisaged efficiency increase to around 44%. Moreover, it provides the constraints to design the components of the balance of the plant. The project is accompanied by numerical studies of heat transfer of supercritical water in fuel assemblies and by material tests of candidate cladding alloys, performed by the consortium and supported by additional tests of the Joint Research Centre of the European Commission. Besides the scientific and technical progress, the HPLWR project turned out to be most successful in training the young generation of nuclear engineers

Thermal-hydraulic analysis of a 600 MW supercritical CFB boiler with low mass flux

International Nuclear Information System (INIS)

Pan Jie; Yang Dong; Chen Gongming; Zhou Xu; Bi Qincheng

2012-01-01

Supercritical Circulating Fluidized Bed (CFB) boiler becomes an important development trend for coal-fired power plant and thermal-hydraulic analysis is a key factor for the design and operation of water wall. According to the boiler structure and furnace-sided heat flux, the water wall system of a 600 MW supercritical CFB boiler is treated in this paper as a flow network consisting of series-parallel loops, pressure grids and connecting tubes. A mathematical model for predicting the thermal-hydraulic characteristics in boiler heating surface is based on the mass, momentum and energy conservation equations of these components, which introduces numerous empirical correlations available for heat transfer and hydraulic resistance calculation. Mass flux distribution and pressure drop data in the water wall at 30%, 75% and 100% of the boiler maximum continuous rating (BMCR) are obtained by iteratively solving the model. Simultaneity, outlet vapor temperatures and metal temperatures in water wall tubes are estimated. The results show good heat transfer performance and low flow resistance, which implies that the water wall design of supercritical CFB boiler is applicable. - Highlights: → We proposed a model for thermal-hydraulic analysis of boiler heating surface. → The model is applied in a 600 MW supercritical CFB boiler. → We explore the pressure drop, mass flux and temperature distribution in water wall. → The operating safety of boiler is estimated. → The results show good heat transfer performance and low flow resistance.

SELECTIVE OXIDATION IN SUPERCRITICAL CARBON DIOXIDE USING CLEAN OXIDANTS

Science.gov (United States)

We have systematically investigated heterogeneous catalytic oxidation of different substrates in supercritical carbon dioxide (SC-CO2). Three types of catagysts: a metal complex, 0.5% platinum g-alumina and 0.5% palladium g-alumina were used at a pressure of 200 bar, temperatures...

Numerical investigation of supercritical LNG convective heat transfer in a horizontal serpentine tube

Science.gov (United States)

Han, Chang-Liang; Ren, Jing-Jie; Dong, Wen-Ping; Bi, Ming-Shu

2016-09-01

The submerged combustion vaporizer (SCV) is indispensable general equipment for liquefied natural gas (LNG) receiving terminals. In this paper, numerical simulation was conducted to get insight into the flow and heat transfer characteristics of supercritical LNG on the tube-side of SCV. The SST model with enhanced wall treatment method was utilized to handle the coupled wall-to-LNG heat transfer. The thermal-physical properties of LNG under supercritical pressure were used for this study. After the validation of model and method, the effects of mass flux, outer wall temperature and inlet pressure on the heat transfer behaviors were discussed in detail. Then the non-uniformity heat transfer mechanism of supercritical LNG and effect of natural convection due to buoyancy change in the tube was discussed based on the numerical results. Moreover, different flow and heat transfer characteristics inside the bend tube sections were also analyzed. The obtained numerical results showed that the local surface heat transfer coefficient attained its peak value when the bulk LNG temperature approached the so-called pseudo-critical temperature. Higher mass flux could eliminate the heat transfer deteriorations due to the increase of turbulent diffusion. An increase of outer wall temperature had a significant influence on diminishing heat transfer ability of LNG. The maximum surface heat transfer coefficient strongly depended on inlet pressure. Bend tube sections could enhance the heat transfer due to secondary flow phenomenon. Furthermore, based on the current simulation results, a new dimensionless, semi-theoretical empirical correlation was developed for supercritical LNG convective heat transfer in a horizontal serpentine tube. The paper provided the mechanism of heat transfer for the design of high-efficiency SCV.

Fabrication of a Cu/Ni stack in supercritical carbon dioxide at low-temperature

Energy Technology Data Exchange (ETDEWEB)

Rasadujjaman, Md, E-mail: rasadphy@duet.ac.bd [Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 4-3-11 Takeda, Kofu, Yamanashi 400-8511 (Japan); Department of Physics, Dhaka University of Engineering & Technology, Gazipur 1700 (Bangladesh); Watanabe, Mitsuhiro [Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 4-3-11 Takeda, Kofu, Yamanashi 400-8511 (Japan); Sudoh, Hiroshi; Machida, Hideaki [Gas-Phase Growth Ltd., 2-24-16 Naka, Koganei, Tokyo 184-0012 (Japan); Kondoh, Eiichi [Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 4-3-11 Takeda, Kofu, Yamanashi 400-8511 (Japan)

2015-09-30

We report the low-temperature deposition of Cu on a Ni-lined substrate in supercritical carbon dioxide. A novel Cu(I) amidinate precursor was used to reduce the deposition temperature. From the temperature dependence of the growth rate, the activation energy for Cu growth on the Ni film was determined to be 0.19 eV. The films and interfaces were characterized by Auger electron spectroscopy. At low temperature (140 °C), we successfully deposited a Cu/Ni stack with a sharp Cu/Ni interface. The stack had a high adhesion strength (> 1000 mN) according to microscratch testing. The high adhesion strength originated from strong interfacial bonding between the Cu and the Ni. However, at a higher temperature (240 °C), significant interdiffusion was observed and the adhesion became weak. - Highlights: • Cu/Ni stack fabricated in supercritical CO{sub 2} at low temperature. • A novel Cu(I) amidinate precursor was used to reduce the deposition temperature. • Adhesion strength of Cu/Ni stack improved dramatically. • Fabricated Cu/Ni stack is suitable for Cu interconnections in microelectronics.

Convective heat transfer in supercritical flows of CO{sub 2} in tubes with and without flow obstacles

Energy Technology Data Exchange (ETDEWEB)

Eter, Ahmad, E-mail: eng.eter@yahoo.com; Groeneveld, Dé, E-mail: degroeneveld@gmail.com; Tavoularis, Stavros, E-mail: stavros.tavoularis@uottawa.ca

2017-03-15

Highlights: • Measurements of supercritical heat transfer in tubes equipped with obstacles were obtained and compared with results in base tubes. • In general, flow obstacles improve supercritical heat transfer, but under certain conditions have a negative effect on it. • New correlations describing obstacle-enhanced supercritical heat transfer in the liquid-like and gas-like regimes are fitted to the data. - Abstract: Heat transfer measurements to CO{sub 2}-cooled tubes with and without flow obstacles at supercritical pressures were obtained at the University of Ottawa’s supercritical pressure test facility. The effects of obstacle geometry (obstacle pitch, obstacle shape, flow blockage) on the wall temperature and heat transfer coefficient were investigated. Tests were performed for vertical upward flow in a directly heated 8 mm ID tube for a pressure range from 7.69 to 8.36 MPa, a mass flux range from 200 to 1184 kg/m{sup 2} s, and a heat flux range from 1 to 175 kW/m{sup 2}. The results are presented graphically in plots of wall temperature and heat transfer coefficient vs. bulk specific enthalpy of the fluid. The effects of flow parameters and flow obstacle geometry on supercritical heat transfer for both normal and deteriorated heat transfer are discussed. A comparison of the measurements with leading prediction methods for supercritical heat transfer in bare tubes and for spacer effects is also presented. The optimum increase in heat transfer coefficient was found to be for blunt obstacles, having a large flow blockage, and a short obstacle pitch.

Steady state and linear stability analysis of a supercritical water natural circulation loop

International Nuclear Information System (INIS)

Sharma, Manish; Pilkhwal, D.S.; Vijayan, P.K.; Saha, D.; Sinha, R.K.

2010-01-01

Supercritical water (SCW) has excellent heat transfer characteristics as a coolant for nuclear reactors. Besides it results in high thermal efficiency of the plant. However, the flow can experience instabilities in supercritical water reactors, as the density change is very large for the supercritical fluids. A computer code SUCLIN using supercritical water properties has been developed to carry out the steady state and linear stability analysis of a SCW natural circulation loop. The conservation equations of mass, momentum and energy have been linearized by imposing small perturbation in flow rate, enthalpy, pressure and specific volume. The equations have been solved analytically to generate the characteristic equation. The roots of the equation determine the stability of the system. The code has been qualitatively assessed with published results and has been extensively used for studying the effect of diameter, height, heater inlet temperature, pressure and local loss coefficients on steady state and stability behavior of a Supercritical Water Natural Circulation Loop (SCWNCL). The present paper describes the linear stability analysis model and the results obtained in detail.

Infinite dilution partial molar volumes of platinum(II) 2,4-pentanedionate in supercritical carbon dioxide.

Science.gov (United States)

Kong, Chang Yi; Siratori, Tomoya; Funazukuri, Toshitaka; Wang, Guosheng

2014-10-03

The effects of temperature and density on retention of platinum(II) 2,4-pentanedionate in supercritical fluid chromatography were investigated at temperatures of 308.15-343.15K and pressure range from 8 to 40MPa by the chromatographic impulse response method with curve fitting. The retention factors were utilized to derive the infinite dilution partial molar volumes of platinum(II) 2,4-pentanedionate in supercritical carbon dioxide. The determined partial molar volumes were small and positive at high pressures but exhibited very large and negative values in the highly compressible near critical region of carbon dioxide. Copyright © 2014 Elsevier B.V. All rights reserved.

Heat Transfer Characteristics for an Upward Flowing Supercritical Pressure CO2 in a Vertical Annulus Passage

International Nuclear Information System (INIS)

Kang, Deog Ji; Kim, Sin; Kim, Hwan Yeol; Bae, Yoon Yeong

2007-01-01

Heat transfer experiments at a vertical annulus passage were carried out in the SPHINX(Supercritical Pressure Heat Transfer Investigation for NeXt Generation) to investigate the heat transfer behaviors of supercritical CO 2 . The collected test data are to be used for the reactor core design of the SCWR (SuperCritical Water-cooled Reactor). The mass flux was in the range of 400 ∼1200 kg/m 2 s and the heat flux was chosen up to 150 kW/m 2 . The selected pressures were 7.75 and 8.12 MPa. The heat transfer data were analyzed and compared with the previous tube test data. The test results showed that the heat transfer characteristics were similar to those of the tube in case of a normal heat transfer mode and degree of heat transfer deterioration became smaller than that in the tube. Comparison of the experimental heat transfer coefficients with the predicted ones by the existing correlations showed that there was not a distinct difference between the correlations

Regeneration of a deactivated USY alkylation catalyst using supercritical isobutane

Energy Technology Data Exchange (ETDEWEB)

Daniel M. Ginosar; David N. Ghompson; Kyle C. Burch

2005-01-01

Off-line, in-situ alkylation activity recovery from a completely deactivated solid acid catalyst was examined in a continuous-flow reaction system employing supercritical isobutane. A USY zeolite catalyst was initially deactivated during the liquid phase alkylation of butene with isobutane in a single-pass reactor and then varying amounts of alkylation activity were recovered by passing supercritical isobutane over the catalyst bed at different reactivation conditions. Temperature, pressure and regeneration time were found to play important roles in the supercritical isobutane regeneration process when applied to a completely deactivated USY zeolite alkylation catalyst. Manipulation of the variables that influence solvent strength, diffusivity, surface desorption, hydride transfer rates, and coke aging, strongly influence regeneration effectiveness.

Experimental study of supercritical water flow and heat transfer in vertical tube

International Nuclear Information System (INIS)

Li Hongbo; Yang Jue; Lu Donghua; Gu Hanyang; Zhao Meng

2012-01-01

The experiment of flow and heat transfer of supercritical water has been performed on the supercritical water multipurpose test loop co-constructed by China Guangdong Nuclear Power Group and Shanghai Jiao Tong University with a 7.6 mm vertical tube. Heat transfer experimental data is obtained. The results of experimental research of thermal-hydraulic parameters on flow and heat transfer of supercritical water show that: (1) Heat transfer enhancement occurs when the bulk temperature reaches pseudo-critical point with low mass flow velocity; (2) The heat transfer co- efficient and Nusselt number are decreased with the increasing of heat flux; (3) The wall temperature is decreased, but the heat transfer coefficient and Nusselt number are increased with the increasing of mass flow velocity; (4) The wall temperature is increased, but the heat transfer coefficient and Nusselt number are decreased with the increasing of sys- tem pressure. (authors)

Thermal-hydraulic analysis of heat transfer in subchannels of the European high performance supercritical Water-Cooled Reactor for different CFD turbulence models

Energy Technology Data Exchange (ETDEWEB)

Castro, Landy Y.; Rojas, Leorlen Y.; Gamez, Abel; Rosales, Jesus; Gonzalez, Daniel; Garcia, Carlos, E-mail: lcastro@instec.cu, E-mail: leored1984@gmail.com, E-mail: agamezgmf@gmail.com, E-mail: jrosales@instec.cu, E-mail: danielgonro@gmail.com, E-mail: cgh@instec.cu [Instituto Superior de Tecnologias y Ciencias Aplicadas (InSTEC), La Habana (Cuba); Oliveira, Carlos Brayner de, E-mail: cabol@ufpe.br [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil); Dominguez, Dany S., E-mail: dsdominguez@gmail.com [Universidade Estadual de Santa Cruz (UESC), Ilheus, BA (Brazil). Pos-Graduacao em Modelagem Computacional

2015-07-01

Chosen as one of six Generation‒IV nuclear-reactor concepts, Supercritical Water-cooled Reactors (SCWRs) are expected to have high thermal efficiencies within the range of 45 - 50% owing to the reactor's high pressures and outlet temperatures. In this reactor, the primary water enters the core under supercritical-pressure condition (25 MPa) at a temperature of 280 deg C and leaves it at a temperature of up to 510 deg C. Due to the significant changes in the physical properties of water at supercritical-pressure, the system is susceptible to local temperature, density and power oscillations. The behavior of supercritical water into the core of the SCWR, need to be sufficiently studied. Most of the methods available to predict the effects of the heat transfer phenomena within the pseudocritical region are based on empirical one-directional correlations, which do not capture the multidimensional effects and do not provide accurate results in regions such as the deteriorated heat transfer regime. In this paper, computational fluid dynamics (CFD) analysis was carried out to study the thermal-hydraulic behavior of supercritical water flows in sub-channels of a typical European High Performance Light Water Reactor (HPLWR) fuel assembly using commercial CFD code CFX-14. It was determined the steady-state equilibrium parameters and calculated the temperature and density distributions. A comparative study for different turbulence models were carried out and the obtained results are discussed. (author)

Thermal-hydraulic analysis of heat transfer in subchannels of the European high performance supercritical Water-Cooled Reactor for different CFD turbulence models

International Nuclear Information System (INIS)

Castro, Landy Y.; Rojas, Leorlen Y.; Gamez, Abel; Rosales, Jesus; Gonzalez, Daniel; Garcia, Carlos; Oliveira, Carlos Brayner de; Dominguez, Dany S.

2015-01-01

Chosen as one of six Generation‒IV nuclear-reactor concepts, Supercritical Water-cooled Reactors (SCWRs) are expected to have high thermal efficiencies within the range of 45 - 50% owing to the reactor's high pressures and outlet temperatures. In this reactor, the primary water enters the core under supercritical-pressure condition (25 MPa) at a temperature of 280 deg C and leaves it at a temperature of up to 510 deg C. Due to the significant changes in the physical properties of water at supercritical-pressure, the system is susceptible to local temperature, density and power oscillations. The behavior of supercritical water into the core of the SCWR, need to be sufficiently studied. Most of the methods available to predict the effects of the heat transfer phenomena within the pseudocritical region are based on empirical one-directional correlations, which do not capture the multidimensional effects and do not provide accurate results in regions such as the deteriorated heat transfer regime. In this paper, computational fluid dynamics (CFD) analysis was carried out to study the thermal-hydraulic behavior of supercritical water flows in sub-channels of a typical European High Performance Light Water Reactor (HPLWR) fuel assembly using commercial CFD code CFX-14. It was determined the steady-state equilibrium parameters and calculated the temperature and density distributions. A comparative study for different turbulence models were carried out and the obtained results are discussed. (author)

Supercritical Fluid Extraction of Lovastatin from the Wheat Bran Obtained after Solid-State Fermentation

Directory of Open Access Journals (Sweden)

Ruchir C. Pansuriya

2009-01-01

Full Text Available The objective of the present work is to extract lovastatin with minimum impurity by using supercritical carbon dioxide (SC-CO2. A strain of Aspergillus terreus UV 1617 was used to produce lovastatin by solid-state fermentation (SSF on wheat bran as a solid substrate. Extraction of lovastatin and its hydroxy acid form was initially carried out using organic solvents. Among the different screened solvents, acetonitrile was found to be the most efficient. SC-CO2 was used for extraction of lovastatin from the dry fermented matter. The effect of supercritical extraction parameters such as the amount of an in situ pretreatment solvent, temperature, pressure, flow rate and contact time were investigated. The maximum recovery of lovastatin was obtained with 5 mL of methanol as an in situ pretreatment solvent for 1.5 g of solid matrix, flow rate of the supercritical solvent 2 L/min, temperature 50 °C, and contact time 155 min at a pressure 300 bar. The lovastatin extract obtained after optimizing the conditions of supercritical fluid extraction was found to have 5-fold more HPLC purity than the organic solvent extract.

Critical review of supercritical carbon dioxide extraction of selected oil seeds

Directory of Open Access Journals (Sweden)

Sovilj Milan N.

2010-01-01

Full Text Available Supercritical carbon dioxide extraction, as a relatively new separation technique, can be used as a very efficient process in the production of essential oils and oleoresins from many of plant materials. The extracts from these materials are a good basis for the new pharmaceutical products and ingredients in the functional foods. This paper deals with supercritical carbon dioxide extraction of selected oil seeds which are of little interest in classical extraction in the food industry. In this article the process parameters in the supercritical carbon dioxide extraction, such as pressure, temperature, solvent flow rate, diameter of gound materials, and moisture of oil seed were presented for the following seeds: almond fruits, borage seed, corn germ, grape seed, evening primrose, hazelnut, linseed, pumpkin seed, walnut, and wheat germ. The values of investigated parameters in supercritical extraction were: pressure from 100 to 600 bar, temperature from 10 to 70oC, diameter of grinding material from 0.16 to 2.0 mm, solvent flow used from 0.06 to 30.0 kg/h, amount of oil in the feed from 10.0 to 74.0%, and moisture of oil seed from 1.1 to 7.5%. The yield and quality of the extracts of all the oil seeds as well as the possibility of their application in the pharmaceutical and food, industries were analyzed.

Safety analysis of high temperature reactor cooled and moderated by supercritical light water

International Nuclear Information System (INIS)

Ishiwatari, Yuki; Oka, Yoshiaki; Koshizuka, Seiichi

2003-01-01

This paper describes 'Safety' of a high temperature supercritical light water cooled and moderated reactor (SCRLWR-H) with descending flow water rods. The safety system of the SCLWR-H is similar to that of a BWR. It consists of reactor scram, high pressure auxiliary feedwater system (AFS), low pressure core injection system (LPCI), safety relief valves (SRV), automatic depressurization system (ADS), and main steam isolation valves (MSIV). Ten types of transients and five types of accidents are analyzed using a plant transient analysis code SPRAT-DOWN. The sequences are determined referring to LWRs. At the 'Loss of load without turbine bypass' transient, the coolant density and the core power are increased by the over-pressurization, and at the same time the core flow rate is decreased by the closure of the turbine control valves. The peak cladding temperature increases to 727degC. The high temperature at this type of transient is one of the characteristics of the SCLWR-H. Conversely at 'feedwater-loss' events, the core power decrease to some extend by density feedback before the reactor scram. The peak cladding temperatures at the 'Partial loss of feedwater' transient and the 'Total loss of feedwater' accident are only 702degC and 833degC, respectively. The cladding temperature does not increase so much at the transients 'Loss of feedwater heating' and 'CR withdrawal' because of the operation of the plant control system. All the transients and accidents satisfy the satisfy criteria with good margins. The highest cladding temperatures of the transients and the accidents are 727degC and 833degC at the 'Loss of load without turbine bypass' and 'Total loss of feedwater', respectively. The duration of the high cladding temperature is very short at the transients. According to the parametric survey, the peak cladding temperature are sensitive to the parameters such as the pump coast-down time, delay of pump trip, AFS capacity, AFS delay, CR worth, and SRV setpoint

Supercritical Water Mixture (SCWM) Experiment in the High Temperature Insert-Reflight (HTI-R)

Science.gov (United States)

Hicks, Michael C.; Hegde, Uday G.; Garrabos, Yves; Lecoutre, Carole; Zappoli, Bernard

2013-01-01

Current research on supercritical water processes on board the International Space Station (ISS) focuses on salt precipitation and transport in a test cell designed for supercritical water. This study, known as the Supercritical Water Mixture Experiment (SCWM) serves as a precursor experiment for developing a better understanding of inorganic salt precipitation and transport during supercritical water oxidation (SCWO) processes for the eventual application of this technology for waste management and resource reclamation in microgravity conditions. During typical SCWO reactions any inorganic salts present in the reactant stream will precipitate and begin to coat reactor surfaces and control mechanisms (e.g., valves) often severely impacting the systems performance. The SCWM experiment employs a Sample Cell Unit (SCU) filled with an aqueous solution of Na2SO4 0.5-w at the critical density and uses a refurbished High Temperature Insert, which was used in an earlier ISS experiment designed to study pure water at near-critical conditions. The insert, designated as the HTI-Reflight (HTI-R) will be deployed in the DECLIC (Device for the Study of Critical Liquids and Crystallization) Facility on the International Space Station (ISS). Objectives of the study include measurement of the shift in critical temperature due to the presence of the inorganic salt, assessment of the predominant mode of precipitation (i.e., heterogeneously on SCU surfaces or homogeneously in the bulk fluid), determination of the salt morphology including size and shapes of particulate clusters, and the determination of the dominant mode of transport of salt particles in the presence of an imposed temperature gradient. Initial results from the ISS experiments will be presented and compared to findings from laboratory experiments on the ground.

Extraction/fractionation and deacidification of wheat germ oil using supercritical carbon dioxide

Directory of Open Access Journals (Sweden)

P. Zacchi

2006-03-01

Full Text Available Wheat germ oil was obtained by mechanical pressing using a small-scale screw press and by supercritical extraction in a pilot plant. With this last method, different pressures and temperatures were tested and the tocopherol concentration in the extract was monitored during extraction. Then supercritical extracted oil as well as commercial pressed oil were deacidified in a countercurrent column using supercritical carbon dioxide as solvent under different operating conditions. Samples of extract, refined oil and feed oil were analyzed for free fatty acids (FFA and tocopherol contents. The results show that oil with a higher tocopherol content can be obtained by supercritical extraction-fractionation and that FFA can be effectively removed by countercurrent rectification while the tocopherol content is only slightly reduced.

Experiments in a natural circulation loop with supercritical water at low powers

International Nuclear Information System (INIS)

Pilkhwal, D.S.; Sharma, Manish; Jana, S.S.; Vijayan, P.K.

2013-05-01

Earlier, 1/2 ″ uniform diameter Supercritical Pressure Natural Circulation Loop (SPNL) was set-up in hall-7, BARC for carrying out experiments related to supercritical fluids. The loop is a rectangular loop having two heaters and two coolers. Experiments were carried out with CO 2 under supercritical conditions for various pressures and different combinations of heater and cooler orientations. Since, the design conditions are more severe for supercritical water (SCW) experiments, the loop was modified for SCW by installing new test sections, pressurizer and power supply for operation with supercritical water. Experimental data were generated on steady state, heat transfer and stability under natural circulation conditions for the horizontal heater and horizontal cooler (HHHC) orientation with SCW up to a heater power of 8.5 kW. The flow rate data and instability data were compared with the predictions of in-house developed 1-D code NOLSTA, which showed reasonable agreement. The heat transfer coefficient data were also compared with the predictions of various correlations exhibit peak at bulk temperature lower than that obtained in the experiments. Most of these correlations predicted experimental data well in the pseudo-critical region. However, all correlations are matching well with experimental data beyond the pseudo-critical region. The details of the experimental facility, Experiments carried out and the results presented in this report. (author)

Method and apparatus for waste destruction using supercritical water oxidation

Science.gov (United States)

Haroldsen, Brent Lowell; Wu, Benjamin Chiau-pin

2000-01-01

The invention relates to an improved apparatus and method for initiating and sustaining an oxidation reaction. A hazardous waste, is introduced into a reaction zone within a pressurized containment vessel. An oxidizer, preferably hydrogen peroxide, is mixed with a carrier fluid, preferably water, and the mixture is heated until the fluid achieves supercritical conditions of temperature and pressure. The heating means comprise cartridge heaters placed in closed-end tubes extending into the center region of the pressure vessel along the reactor longitudinal axis. A cooling jacket surrounds the pressure vessel to remove excess heat at the walls. Heating and cooling the fluid mixture in this manner creates a limited reaction zone near the center of the pressure vessel by establishing a steady state density gradient in the fluid mixture which gradually forces the fluid to circulate internally. This circulation allows the fluid mixture to oscillate between supercritical and subcritical states as it is heated and cooled.

Application of response surface methodology to optimise supercritical carbon dioxide extraction of volatile compounds from Crocus sativus.

Science.gov (United States)

Shao, Qingsong; Huang, Yuqiu; Zhou, Aicun; Guo, Haipeng; Zhang, Ailian; Wang, Yong

2014-05-01

Crocus sativus has been used as a traditional Chinese medicine for a long time. The volatile compounds of C. sativus appear biologically active and may act as antioxidants as well as anticonvulsants, antidepressants and antitumour agents. In order to obtain the highest possible yield of essential oils from C. sativus, response surface methodology was employed to optimise the conditions of supercritical fluid carbon dioxide extraction of the volatile compounds from C. sativus. Four factorswere investigated: temperature, pressure, extraction time and carbon dioxide flow rate. Furthermore, the chemical compositions of the volatile compounds extracted by supercritical fluid extraction were compared with those obtained by hydro-distillation and Soxhlet extraction. The optimum extraction conditions were found to be: optimised temperature 44.9°C, pressure 34.9 MPa, extraction time 150.2 min and CO₂ flow rate 10.1 L h⁻¹. Under these conditions, the mean extraction yield was 10.94 g kg⁻¹. The volatile compounds extracted by supercritical fluid extraction and Soxhlet extraction contained a large amount of unsaturated fatty acids. Response surface methodology was successfully applied for supercritical fluid CO₂ extraction optimisation of the volatile compounds from C. sativus. The study showed that pressure and CO₂ flow rate had significant effect on volatile compounds yield produced by supercritical fluid extraction. This study is beneficial for the further research operating on a large scale. © 2013 Society of Chemical Industry.

A Heat Transfer Correlation in a Vertical Upward Flow of CO{sub 2} at Supercritical Pressures

Energy Technology Data Exchange (ETDEWEB)

Kim, Hyung Rae; Bae, Yoon Yeong; Song, Jin Ho; Kim, Hwan Yeol [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

2006-07-01

Heat transfer data has been collected in the heat transfer test loop, named SPHINX (Supercritical Pressure Heat Transfer Investigation for NeXt generation), in KAERI. The facility primarily aims at the generation of heat transfer data in the flow conditions and geometries relevant to SCWR (SuperCritical Water-cooled Reactor). The produced data will aid the thermohydraulic design of a reactor core. The loop uses carbon dioxide, and later the results will be scaled to the water flows. The heat transfer data has been collected for a vertical upward flow in a circular tube with varying mass fluxes, heat fluxes, and operating pressures. The results are compared with the existing correlations and a new correlation is proposed by fine-tuning the one of the existing correlations.

Analysis of prompt supercritical process with heat transfer and temperature feedback

Institute of Scientific and Technical Information of China (English)

ZHU BO; ZHU Qian; CHEN Zhiyun

2009-01-01

The prompt supercritical process of a nuclear reactor with temperature feedback and initial power as well as heat transfer with a big step reactivity (ρ0>β) is analyzed in this paper.Considering the effect of heat transfer on temperature of the reactor,a new model is set up.For any initial power,the variations of output power and reactivity with time are obtained by numerical method.The effects of the big inserted step reactivity and initial power on the prompt supercritical process are analyzed and discussed.It was found that the effect of heat transfer on the output power and reactivity can be neglected under any initial power,and the output power obtained by the adiabatic model is basically in accordance with that by the model of this paper,and the analytical solution can be adopted.The results provide a theoretical base for safety analysis and operation management of a power reactor.

A novel spiral reactor for biodiesel production in supercritical ethanol

International Nuclear Information System (INIS)

Farobie, Obie; Sasanami, Kazuma; Matsumura, Yukihiko

2015-01-01

Highlights: • A novel spiral reactor for biodiesel production in supercritical ethanol was proposed. • The spiral reactor employed in this study successfully recovered heat. • The effects of temperature and time on FAEE yield were investigated. • FAEE yield as high as 0.937 mol/mol was obtained at 350 °C after 30 min. • The second-order kinetic model expressed the experimental yield well. - Abstract: A spiral reactor is proposed as a novel reactor design for biodiesel production under supercritical conditions. Since the spiral reactor serves as a heat exchanger, it offers the advantage of reduced apparatus space compared to conventional supercritical equipment. Experimental investigations were carried out at reaction temperatures of 270–400 °C, pressure of 20 MPa, oil-to-ethanol molar ratio of 1:40, and reaction times of 3–30 min. An FAEE yield of 0.937 mol/mol was obtained in a short reaction time of 30 min at 350 °C and oil-to-ethanol molar ratio of 1:40 under a reactor pressure of 20 MPa. The spiral reactor was not only as effective as conventional reactor in terms of transesterification reactor but also was superior in terms of heat recovery. A second-order kinetic model describing the transesterification of canola oil in supercritical ethanol was proposed, and the reaction was observed to follow Arrhenius behavior. The corresponding reaction rate constants and the activation energies as well as pre-exponential factors were determined

Evaluation and Optimization of a Supercritical Carbon Dioxide Power Conversion Cycle for Nuclear Applications

International Nuclear Information System (INIS)

Harvego, Edwin A.; McKellar, Michael G.

2011-01-01

There have been a number of studies involving the use of gases operating in the supercritical mode for power production and process heat applications. Supercritical carbon dioxide (CO2) is particularly attractive because it is capable of achieving relatively high power conversion cycle efficiencies in the temperature range between 550 C and 750 C. Therefore, it has the potential for use with any type of high-temperature nuclear reactor concept, assuming reactor core outlet temperatures of at least 550 C. The particular power cycle investigated in this paper is a supercritical CO2 Recompression Brayton Cycle. The CO2 Recompression Brayton Cycle can be used as either a direct or indirect power conversion cycle, depending on the reactor type and reactor outlet temperature. The advantage of this cycle when compared to the helium Brayton Cycle is the lower required operating temperature; 550 C versus 850 C. However, the supercritical CO2 Recompression Brayton Cycle requires an operating pressure in the range of 20 MPa, which is considerably higher than the required helium Brayton cycle operating pressure of 8 MPa. This paper presents results of analyses performed using the UniSim process analyses software to evaluate the performance of the supercritical CO2 Brayton Recompression Cycle for different reactor outlet temperatures. The UniSim model assumed a 600 MWt reactor power source, which provides heat to the power cycle at a maximum temperature of between 550 C and 750 C. The UniSim model used realistic component parameters and operating conditions to model the complete power conversion system. CO2 properties were evaluated, and the operating range for the cycle was adjusted to take advantage of the rapidly changing conditions near the critical point. The UniSim model was then optimized to maximize the power cycle thermal efficiency at the different maximum power cycle operating temperatures. The results of the analyses showed that power cycle thermal efficiencies in

Experimental study on heat transfer to supercritical water flowing in 1- and 4-m-long vertical tubes

International Nuclear Information System (INIS)

Kirillov, Pavel; Pomet'ko, Richard; Smirnov, Aleksandr; Grabezhnaia, Vera; Pioro, Igor; Duffey, Romney; Khartabil, Hussam

2005-01-01

This paper presents selected on heat transfer to supercritical water flowing upward in 1- and 4-m-long vertical tubes. Supercritical water heat-transfer data were obtained at pressures of 24-25 MPa, mass fluxes of 200 - 1500 kg/m 2 s, heat fluxes up to 1050 kW/m 2 and inlet temperature from 300 to 380degC for several combinations of wall and bulk fluid temperatures that were below, at or above the pseudocritical temperature. In general, the experiments confirmed that there are three heat transfer modes for water at supercritical pressures: (1) normal heat transfer characterized in general with heat transfer coefficients (HTCs) similar to those of subcritical convective heat transfer far from critical or pseudocritical regions, which are calculated according to the Dittus-Boelter type correlations, (2) deteriorated heat transfer with lower values of the HTC and hence higher values of wall temperature within some part of a test section compared to those of normal heat transfer and (3) improved heat transfer with higher values of the HTC and hence lower values of wall temperature within some part of a test section compared to those of normal heat transfer. These new heat-transfer data are applicable as a reference dataset for future comparison with supercritical water bundle data and for the verification of scaling parameters between water and modelling fluids. (author)

Supercritical fluid synthesis inthe preparation of β+-emitting labelled compounds

International Nuclear Information System (INIS)

Jacobson, G.; Markides, K.E.; Laangstroem, B.

1994-01-01

A system for synthesis in supercritical fluids has been developed for the microscale synthesis of pharmaceuticals labelled with 11 C. Supercritical ammonia was selected as the reaction medium and the following variables were studied in detail: trapping efficiency, cell design, substrate concentration, operation design, and temperature and pressure conditions. Alkylation of phenol by [ 11 C]methyl iodide to yield [methyl- 11 C]anisole was used as a model reaction for evaluation of the system. The results show an increased radiochemical yield in the highly compressible near-critical region. (au) (40 refs.)

Influence of various aspects of low Reynolds number k-ε turbulence models on predicting in-tube buoyancy affected heat transfer to supercritical pressure fluids

International Nuclear Information System (INIS)

Zhao, Chen-Ru; Zhang, Zhen; Jiang, Pei-Xue; Bo, Han-Liang

2017-01-01

Highlights: • Understanding of the mechanism of buoyancy effect on supercritical heat transfer. • Turbulence related parameters in upward and downward flows were compared. • Turbulent Prandtl number affected the prediction insignificantly. • Buoyancy production was insignificant compared with shear production. • Damping function had the greatest effect and is a priority for further modification. - Abstract: Heat transfer to supercritical pressure fluids was modeled for normal and buoyancy affected conditions using several low Reynolds number k-ε models, including the Launder and Sharma, Myong and Kasagi, and Abe, Kondoh and Nagano, with the predictions compared with experimental data. All three turbulence models accurately predicted the cases without heat transfer deterioration, but failed to accurately predict the cases with heat transfer deterioration although the general trends were captured, indicating that further improvements and modifications are needed for the low Reynolds number k-ε turbulence models to better predict buoyancy deteriorated heat transfer. Further investigations studied the influence of various aspects of the low Reynolds number k-ε turbulence models, including the turbulent Prandtl number, the buoyancy production of turbulent kinetic energy, and the damping function to provide guidelines for model development to more precisely predict buoyancy affected heat transfer. The results show that the turbulent Prandtl number and the buoyancy production of turbulent kinetic energy have little influence on the predictions for cases in this study, while new damping functions with carefully selected control parameters are needed in the low Reynolds number k-ε turbulence models to correctly predict the buoyancy effect for heat transfer simulations in various applications such as supercritical pressure steam generators (SPSGs) in the high temperature gas cooled reactor (HTR) and the supercritical pressure water reactor (SCWR).

Influence of various aspects of low Reynolds number k-ε turbulence models on predicting in-tube buoyancy affected heat transfer to supercritical pressure fluids

Energy Technology Data Exchange (ETDEWEB)

Zhao, Chen-Ru; Zhang, Zhen [Institute of Nuclear and New Energy Technology of Tsinghua University, Advanced Nuclear Energy Technology Cooperation Innovation Centre, Key Laboratory of Advanced Nuclear Engineering and Safety, Ministry of Education, Beijing 100084 (China); Jiang, Pei-Xue, E-mail: jiangpx@tsinghua.edu.cn [Beijing Key Laboratory of CO_2 Utilization and Reduction Technology/Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing 100084 (China); Bo, Han-Liang [Institute of Nuclear and New Energy Technology of Tsinghua University, Advanced Nuclear Energy Technology Cooperation Innovation Centre, Key Laboratory of Advanced Nuclear Engineering and Safety, Ministry of Education, Beijing 100084 (China)

2017-03-15

Highlights: • Understanding of the mechanism of buoyancy effect on supercritical heat transfer. • Turbulence related parameters in upward and downward flows were compared. • Turbulent Prandtl number affected the prediction insignificantly. • Buoyancy production was insignificant compared with shear production. • Damping function had the greatest effect and is a priority for further modification. - Abstract: Heat transfer to supercritical pressure fluids was modeled for normal and buoyancy affected conditions using several low Reynolds number k-ε models, including the Launder and Sharma, Myong and Kasagi, and Abe, Kondoh and Nagano, with the predictions compared with experimental data. All three turbulence models accurately predicted the cases without heat transfer deterioration, but failed to accurately predict the cases with heat transfer deterioration although the general trends were captured, indicating that further improvements and modifications are needed for the low Reynolds number k-ε turbulence models to better predict buoyancy deteriorated heat transfer. Further investigations studied the influence of various aspects of the low Reynolds number k-ε turbulence models, including the turbulent Prandtl number, the buoyancy production of turbulent kinetic energy, and the damping function to provide guidelines for model development to more precisely predict buoyancy affected heat transfer. The results show that the turbulent Prandtl number and the buoyancy production of turbulent kinetic energy have little influence on the predictions for cases in this study, while new damping functions with carefully selected control parameters are needed in the low Reynolds number k-ε turbulence models to correctly predict the buoyancy effect for heat transfer simulations in various applications such as supercritical pressure steam generators (SPSGs) in the high temperature gas cooled reactor (HTR) and the supercritical pressure water reactor (SCWR).

Mass transfer of Disperse Red 153 and its crude dye in supercritical CO2 fluid

Directory of Open Access Journals (Sweden)

Zheng Huan-Da

2017-01-01

Full Text Available In this paper, polyester fibers were dyed with Disperse Red 153 and its crude dye in supercritical CO2. The effect of dyeing temperature, dyeing time, dyeing pressure, as well as auxiliaries in the commercialized Disperse Red 153 on the dyeing performance of polyester fibers was investigated. The obtained results showed that the dyeing effect of crude dye for polyester was better than that of Disperse Red 153 in the same dyeing condition. The color strength values of the dyed polyester samples were increased gradually with the increase of temperature and pressure since mass transfer of dye was improved. In addition, the mass transfer model of Disperse Red 153 in supercritical CO2 was also proposed.

DNS of transcritical turbulent boundary layers at supercritical pressures under abrupt variations in thermodynamic properties

Science.gov (United States)

Kawai, Soshi

2014-11-01

In this talk, we first propose a numerical strategy that is robust and high-order accurate for enabling to simulate transcritical flows at supercritical pressures under abrupt variations in thermodynamic properties due to the real fluid effects. The method is based on introducing artificial density diffusion in a physically-consistent manner in order to capture the steep variation of thermodynamic properties in transcritical conditions robustly, while solving a pressure evolution equation to achieve pressure equilibrium at the transcritical interfaces. We then discuss the direct numerical simulation (DNS) of transcritical heated turbulent boundary layers on a zero-pressure-gradient flat plate at supercritical pressures. To the best of my knowledge, the present DNS is the first DNS of zero-pressure-gradient flat-plate transcritical turbulent boundary layer. The turbulent kinetic budget indicates that the compressibility effects (especially, pressure-dilatation correlation) are not negligible at the transcritical conditions even if the flow is subsonic. The unique and interesting interactions between the real fluid effects and wall turbulence, and their turbulence statistics, which have never been seen in the ideal-fluid turbulent boundary layers, are also discussed. This work was supported in part by Japan Society for the Promotion of Science (JSPS) Grant-in-Aid for Young Scientists (A) KAKENHI 26709066 and the JAXA International Top Young Fellowship Program.

The use of supercritical carbon dioxide for contaminant removal from solid waste

International Nuclear Information System (INIS)

Adkins, C.L.J.; Russick, E.M.; Smith, H.M.; Olson, R.B.

1994-01-01

Supercritical carbon dioxide is being explored as a waste minimization technique for separating oils, greases and solvents from solid waste. The containments are dissolved into the supercritical fluid and precipitated out upon depressurization. The carbon dioxide solvent can then be recycled for continued use. Definitions of the temperature, pressure, flowrate and potential co-solvents are required to establish the optimum conditions for hazardous contaminant removal. Excellent extractive capability for common manufacturing oils, greases, and solvents has been observed in both supercritical and liquid carbon dioxide. Solubility measurements are being used to better understand the extraction process, and to determine if the minimum solubility required by federal regulations is met

Code Development in Coupled PARCS/RELAP5 for Supercritical Water Reactor

Directory of Open Access Journals (Sweden)

Po Hu

2014-01-01

Full Text Available The new capability is added to the existing coupled code package PARCS/RELAP5, in order to analyze SCWR design under supercritical pressure with the separated water coolant and moderator channels. This expansion is carried out on both codes. In PARCS, modification is focused on extending the water property tables to supercritical pressure, modifying the variable mapping input file and related code module for processing thermal-hydraulic information from separated coolant/moderator channels, and modifying neutronics feedback module to deal with the separated coolant/moderator channels. In RELAP5, modification is focused on incorporating more accurate water properties near SCWR operation/transient pressure and temperature in the code. Confirming tests of the modifications is presented and the major analyzing results from the extended codes package are summarized.

Supercritical Extraction of Scopoletin from Helichrysum italicum (Roth) G. Don Flowers.

Science.gov (United States)

Jokić, Stela; Rajić, Marina; Bilić, Blanka; Molnar, Maja

2016-09-01

The increasing popularity of immortelle (Helichrysum italicum (Roth) G. Don) and its products, particularly in the cosmetic industry, is evident nowadays. This plant is a source of coumarins, especially scopoletin, which are highly soluble in supercritical CO2 . The objective of this study was to perform the supercritical CO2 extraction process of Helichrysum italicum flowers at different values of pressure and temperature and to optimise the extraction process using response surface methodology in terms of obtaining the highest extraction yield and yield of extracted scopoletin. Extraction was performed in a supercritical extraction system under different extraction conditions of pressure and temperature determined by central composite rotatable design. The mass of flowers in the extractor of 40 g, extraction time of 90 min and CO2 mass flow rate of 1.94 kg/h were kept constant during experiments. Antioxidant activity was determined using the DPPH (1,1-diphenyl-2-picrylhydrazyl) free radical scavenging assay method. Scopoletin concentration was determined by HPLC. Changes in extraction conditions affect the extracting results remarkably. The greatest extraction yield (6.31%) and the highest yield of scopoletin (1.933 mg/100 g) were obtained under extraction conditions of 20 MPa and 40°C. Extracts have also proven to possess antioxidant activity (44.0-58.1% DPPH scavenging activity) influenced by both temperature and pressure applied within the investigated parameters. The extraction conditions, especially pressure, exhibited significant influence on the extraction yield as well as the yield of extracted scopoletin and antioxidant activity of extracts. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Transcritical phenomena of autoignited fuel droplet at high pressures under microgravity

Science.gov (United States)

Segawa, Daisuke; Kajikawa, Tomoki; Kadoka, Toshikazu

2005-09-01

An experimental study has been performed under microgravity to obtain the detailed information needed for the deep understanding of the combustion phenomena of single fuel droplets which autoignite in supercritical gaseous environment. The microgravity environments both in a capsule of a drop shaft and during the parabolic flight of an aircraft were utilized for the experiments. An octadecanol droplet suspended at the tip of a fine quartz fiber in the cold section of the high-pressure combustion chamber was transferred quickly to be subjected to a hot gaseous medium in an electric furnace, this followed by autoignition and combustion of the fuel droplet in supercritical gaseous environment. High-pressure gaseous mixture of oxygen and nitrogen was used as the ambient gas. Temporal variation of temperature of the fuel droplet in supercritical gaseous environment was examined using an embedded fine thermocouple. Sequential backlighted images of the autoignited fuel droplet or the lump of fuel were acquired in supercritical gaseous environment with reduced oxygen concentration. The observed pressure dependence of the ignition delay and that of the burning time of the droplet with the embedded thermocouple were consistent with the previous results. Simultaneous imaging with thermometry showed that the appearance of the fuel changed remarkably at measured fuel temperatures around the critical temperature of the pure fuel. The interface temperature of the fuel rose well beyond the critical temperature of the pure fuel in supercritical gaseous environment. The fuel was gasified long before the end of combustion in supercritical gaseous environment. The proportion of the gasification time to the burning time decreased monotonically with increasing the ambient pressure.

Novel micronisation β-carotene using rapid expansion supercritical solution with co-solvent

Science.gov (United States)

Kien, Le Anh

2017-09-01

Rapid expansion of supercritical solution (RESS) is the most common approach of pharmaceutical pacticle forming methods using supercritical fluids. The RESS method is a technology producing a small solid product with a very narrow particle size distribution, organic solvent-free particles. This process is also simple and easy to control the operating parameters in comparision with other ways based on supercritical techniques. In this study, β-carotene, a strongly colored red-orange pigment abundant in plants and fruits, has been forming by RESS. In addition, the size and morphology effect of four different RESS parameters including co-solvent, extraction temperature, and extraction pressure and expansion nozzle temperature has surveyed. The particle size distribution has been determined by using laser diffraction experiment. SEM has conducted to analyze the surface structure, DSC and FTIR for thermal and chemical structure analysis.

Heat Transfer Characteristics for an Upward Flowing Supercritical Pressure CO{sub 2} in a Vertical Annulus Passage

Energy Technology Data Exchange (ETDEWEB)

Kang, Deog Ji; Kim, Sin [Cheju National Univ., Cheju (Korea, Republic of); Kim, Hwan Yeol; Bae, Yoon Yeong [KAERI, Daejeon (Korea, Republic of)

2007-07-01

Heat transfer experiments at a vertical annulus passage were carried out in the SPHINX(Supercritical Pressure Heat Transfer Investigation for NeXt Generation) to investigate the heat transfer behaviors of supercritical CO{sub 2}. The collected test data are to be used for the reactor core design of the SCWR (SuperCritical Water-cooled Reactor). The mass flux was in the range of 400 {approx}1200 kg/m{sup 2}s and the heat flux was chosen up to 150 kW/m{sup 2}. The selected pressures were 7.75 and 8.12 MPa. The heat transfer data were analyzed and compared with the previous tube test data. The test results showed that the heat transfer characteristics were similar to those of the tube in case of a normal heat transfer mode and degree of heat transfer deterioration became smaller than that in the tube. Comparison of the experimental heat transfer coefficients with the predicted ones by the existing correlations showed that there was not a distinct difference between the correlations.

Preparation of Cefquinome Nanoparticles by Using the Supercritical Antisolvent Process

Directory of Open Access Journals (Sweden)

Xiao Kefeng

2015-01-01

Full Text Available The supercritical antisolvent process was used successfully to prepare nanoparticles of cefquinome. These particles were observed by scanning electron microscope (SEM and their average diameter was measured by laser particle size analyzer. In the experiments, dimethyl sulfoxide (DMSO was selected as solvent to dissolve cefquinome sulfate. It was confirmed by orthogonal experiments that the concentration of solution was the primary factor in this process followed by feeding speed of solution, precipitation pressure, and precipitation temperature. Moreover, the optimal conditions of preparing nanoparticles of cefquinome by supercritical antisolvent process were that solution concentration was 100 mg/mL, solution flow speed was 1.5 mL/min, operating pressure was 13 Mpa, and operating temperature was 33°C. Confirmatory experiment was conducted under this condition. It was found that the appearance of particles was flakes and the average diameter of particles was 0.71 microns. Finally, influence law of individual factor on particle size was investigated by univariate analysis.

Extraction with supercritical gases

Energy Technology Data Exchange (ETDEWEB)

Schneider, G M; Wilke, G; Stahl, E

1980-01-01

The contents of this book derives from a symposium on the 5th and 6th of June 1978 in the ''Haus der Technik'' in Essen. Contributions were made to separation with supercritical gases, fluid extraction of hops, spices and tobacco, physicochemical principles of extraction, phase equilibria and critical curves of binary ammonia-hydrocarbon mixtures, a quick method for the microanalytical evaluation of the dissolving power of supercritical gases, chromatography with supercritical fluids, the separation of nonvolatile substances by means of compressed gases in countercurrent processes, large-scale industrial plant for extraction with supercritical gases, development and design of plant for high-pressure extraction of natural products.

Temperature feedback effects in a supercritical water reactor concept with multiple heat-up steps

International Nuclear Information System (INIS)

Barragan-Martinez, A.M.; Espinosa-Paredes, G.; Vazquez-Rodriguez, A.; Martin-del-Campo, C.; Francois, J.L.

2014-01-01

The Supercritical Water Cooled Reactor (SCWR) is one of the most promising and innovative designs selected by the Generation IV International Forum. One of the concepts being studied is the High Performance Light Water Reactor (HPLWR), which is the European version of the SCWR. In this paper we present the numerical analysis of the behavior of a HPLWR with temperature feedback effects. The neutronic process, the heat transfer in the fuel rod and the thermalhydraulics in the core of the HPLWR were considered in this study. The neutronic calculations were performed with HELIOS-2 and the obtained results were used to evaluate the reactivity due to fuel temperature and supercritical water density. (author)

Temperature feedback effects in a supercritical water reactor concept with multiple heat-up steps

Energy Technology Data Exchange (ETDEWEB)

Barragan-Martinez, A.M., E-mail: albrm29@yahoo.com [Universidad Nacional Autonoma de Mexico, Departamento de Sistemas Energeticos, Facultad de Ingenieria, Jiutepec, Mor (Mexico); Espinosa-Paredes, G.; Vazquez-Rodriguez, A., E-mail: gepe@xanum.uam.mx, E-mail: vara@xanum.uam.mx [Universidad Autonoma Metropolitana-Iztapalapa, Area de Ingenieria en Rescursos Energeticos, Col. Vicentina (Mexico); Martin-del-Campo, C.; Francois, J.L., E-mail: cecilia.martin.del.campo@gmail.com, E-mail: juan.louis.francois@gmail.com [Universidad Nacional Autonoma de Mexico, Departamento de Sistemas Energeticos, Facultad de Ingenieria, Jiutepec, Mor (Mexico)

2014-07-01

The Supercritical Water Cooled Reactor (SCWR) is one of the most promising and innovative designs selected by the Generation IV International Forum. One of the concepts being studied is the High Performance Light Water Reactor (HPLWR), which is the European version of the SCWR. In this paper we present the numerical analysis of the behavior of a HPLWR with temperature feedback effects. The neutronic process, the heat transfer in the fuel rod and the thermalhydraulics in the core of the HPLWR were considered in this study. The neutronic calculations were performed with HELIOS-2 and the obtained results were used to evaluate the reactivity due to fuel temperature and supercritical water density. (author)

Correlation of supercritical-fluid extraction recoveries with supercritical-fluid chromatographic retention data: A fundamental study

NARCIS (Netherlands)

Lou, X.W.; Janssen, J.G.M.; Cramers, C.A.M.G.

1995-01-01

The possibility of using supercritical-fluid chromatographic retention data for examining the effects of operational parameters, such as pressure and flow rate, on the extraction characteristics in supercritical-fluid extraction (SFE) was investigated. A model was derived for calculating the

Effects of process parameters on peanut skins extract and CO2 diffusivity by supercritical fluid extraction

Science.gov (United States)

Putra, N. R.; Yian, L. N.; Nasir, H. M.; Idham, Z. Binti; Yunus, M. A. C.

2018-03-01

Peanut skins (Arachis hypogea) are an agricultural waste product which has received much attention because they contain high nutritional values and can be potentially utilized in difference industries. At present, only a few studies have been conducted to study the effects of parameters on the peanut skins oil extraction. Therefore, this study aimed to determine the best extraction condition in order to obtain the highest extract yield using supercritical carbon dioxide (SC-CO2) with co-solvent Ethanol as compared to Soxhlet extraction method. Diffusivity of carbon dioxide in supercritical fluid extraction was determined using Crank model. The mean particle size used in this study was 425 µm. The supercritical carbon dioxide was performed at temperature (40 – 70 °C), flow rate of co-solvent ethanol (0 - 7.5% Vethanol/Vtotal), and extraction pressure (10 – 30 MPa) were used in this studies. The results showed that the percentage of oil yields and effective diffusivity increase as the pressure, rate of co-solvent, and temperature increased.

Remediation of flare pit soils using supercritical fluid extraction

Energy Technology Data Exchange (ETDEWEB)

Nagpal, V.; Guigard, S.E. [Alberta Univ., Edmonton, AB (Canada). Dept. of Civil Engineering

2005-09-01

A laboratory study was conducted to examine the ability of supercritical fluid extraction (SFE) to remove petroleum hydrocarbons (PHCs) from two flare pit soils in Alberta. SFE is a technology for remediation of contaminated soils. In order to determine the optimal extraction conditions and to understand the effects of pressure, temperature, supercritical carbon dioxide flow rate, soil type, and extraction time on the extraction efficiency of SFE, extractions were performed on two flare pit soils at various pressures and temperatures. Chemicals in the study included diesel oil, SAE 10-30W motor oil, n-decane, hexadecane, tetratriacontane and pentacontane. The best extraction conditions were defined as conditions that result in a treated soil with a PHC concentration that meets the regulatory guidelines of the Canadian Council of Ministers of the Environment in the Canada-wide standard for PHC is soil. The study results indicate that the efficiency of the SFE process is solvent-density dependent for the conditions studied. The highest extraction efficiency for both soils was obtained at conditions of 24.1 MPa and 40 degrees C. An increase in pressure at a fixed temperature led to an increase in the extraction efficiency while an increase in temperature at a fixed pressure led to a decrease in the extraction efficiency. The treated soils were observed to be lighter in colour, drier, and grainier than the soil prior to extraction. It was concluded that SFE is an effective method for remediating flare pit soils. 63 refs., 4 tabs., 5 figs.

Plastic reactor suitable for high pressure and supercritical fluid electrochemistry

DEFF Research Database (Denmark)

Branch, Jack; Alibouri, Mehrdad; Cook, David A.

2017-01-01

The paper describes a reactor suitable for high pressure, particularly supercritical fluid, electrochemistry and electrodeposition at pressures up to 30 MPa at 115◦C. The reactor incorporates two key, new design concepts; a plastic reactor vessel and the use of o-ring sealed brittle electrodes...... by the deposition of Bi. The application of the reactor to the production of nanostructures is demonstrated by the electrodeposition of ∼80 nm diameter Te nanowires into an anodic alumina on silicon template. Key advantages of the new reactor design include reduction of the number of wetted materials, particularly...... glues used for insulating electrodes, compatability with reagents incompatible with steel, compatability with microfabricated planar multiple electrodes, small volume which brings safety advantages and reduced reagent useage, and a significant reduction in experimental time....

Literature survey of heat transfer and hydraulic resistance of water, carbon dioxide, helium and other fluids at supercritical and near-critical pressures

Energy Technology Data Exchange (ETDEWEB)

Pioro, I.L.; Duffey, R.B

2003-04-01

This survey consists of 430 references, including 269 Russian publications and 161 Western publications devoted to the problems of heat transfer and hydraulic resistance of a fluid at near-critical and supercritical pressures. The objective of the literature survey is to compile and summarize findings in the area of heat transfer and hydraulic resistance at supercritical pressures for various fluids for the last fifty years published in the open Russian and Western literature. The analysis of the publications showed that the majority of the papers were devoted to the heat transfer of fluids at near-critical and supercritical pressures flowing inside a circular tube. Three major working fluids are involved: water, carbon dioxide, and helium. The main objective of these studies was the development and design of supercritical steam generators for power stations (utilizing water as a working fluid) in the 1950s, 1960s, and 1970s. Carbon dioxide was usually used as the modeling fluid due to lower values of the critical parameters. Helium, and sometimes carbon dioxide, were considered as possible working fluids in some special designs of nuclear reactors. (author)

A numerical study of a supercritical fluid jet

International Nuclear Information System (INIS)

Sierra-Pallares, J.; Garcia-Serna, J.; Cocero, M.J.; Parra-Santos, M.T.; Castro-Ruiz, F.

2009-01-01

This study affords the numerical solution of the mixing of a submerged turbulent jet under supercritical conditions and near-critical conditions. Turbulence plays a very important role in the behaviour of chemical engineering equipment. An accurate prediction of the turbulence at supercritical conditions with low computational cost is crucial in designing new processes such as reactions in supercritical media, high pressure separation processes, nanomaterials processing and heterogeneous catalysis. At high-pressure, the flow cannot be modelled accurately using the ideal-gas assumption. Therefore, the real gas models must be used in order to solve accurately the fluid flow and heat transfer problems where the working fluid behaviour deviate seriously from the ideal-gas assumption. The jet structure has three parts clearly distinguished: the injection, the transition and the fully developed jet. Once the flow is dominated by the turbulent eddies of the shear layer, the flow is fully developed and the radial profiles match a similarity profile. This work reports the state of the project that is not completed and is being processed now. This work is devoted to establish the distance downstream from the injector where the jet become self-preserving and the shape of the similarity profiles. This system is of interest in the design of supercritical reactor inlets, where two streams should be mixed in the shortest length, or mixing conditions strongly affect the behaviour of the processes. The numerical results have been validated with experimental measurements made in the jet mixing region. The radial profiles for average velocity, density and temperature are analyzed. The parameters of the profile that match better the numerical results are summarized in Table 1. The density requires a lower value of n than these for velocity and temperature, which reflect smoother profiles. These conclusions are in good agreement with the results from Oschwald and Schik. (author)

IMAGE Project: Results of Laboratory Tests on Tracers for Supercritical Conditions.

Science.gov (United States)

Brandvoll, Øyvind; Opsahl Viig, Sissel; Nardini, Isabella; Muller, Jiri

2016-04-01

The use of tracers is a well-established technique for monitoring dynamic behaviour of water and gas through a reservoir. In geothermal reservoirs special challenges are encountered due to high temperatures and pressures. In this work, tracer candidates for monitoring water at supercritical conditions (temperature > 374°C, pressure ca 218 bar), are tested in laboratory experiments. Testing of tracers at supercritical water conditions requires experimental set-ups which tolerate harsh conditions with respect to high temperature and pressure. In addition stringent HES (health, environment and safety) factors have to be taken into consideration when designing and performing the experiments. The setup constructed in this project consists of a pressure vessel, high pressure pump, instrumentation for pressure and temperature control and instrumentation required for accurate sampling of tracers. In order to achieve accurate results, a special focus has been paid to the development of the tracer sampling technique. Perfluorinated cyclic hydrocarbons (PFCs) have been selected as tracer candidates. This group of compounds is today commonly used as gas tracers in oil reservoirs. According to the literature they are stable at temperatures up to 400°C. To start with, five PFCs have been tested for thermal stability in static experiments at 375°C and 108 bar in the experimental setup described above. The tracer candidates will be further tested for several months at the relevant conditions. Preliminary results indicate that some of the PFC compounds show stability after three months. However, in order to arrive at conclusive results, the experiments have to be repeated over a longer period and paying special attention to more accurate sampling procedures.

Reducing the fuel temperature for pressure-tube supercritical-water-cooled reactors and the effect of fuel burnup

Energy Technology Data Exchange (ETDEWEB)

Nichita, E., E-mail: eleodor.nichita@uoit.ca; Kovaltchouk, V., E-mail: vitali.kovaltchouk@uoit.ca

2015-12-15

Highlights: • Typical PT-SCWR fuel uses single-region pins consisting of a homogeneous mixture of ThO{sub 2} and PuO{sub 2}. • Using two regions (central for the ThO{sub 2} and peripheral for the PuO{sub 2}) reduces the fuel temperature. • Single-region-pin melting-to-average power ratio is 2.5 at 0.0 MW d/kg and 2.3 at 40 MW d/kg. • Two-region-pin melting-to-average power ratio is 36 at 0.0 MW d/kg and 10.5 at 40 MW d/kg. • Two-region-pin performance drops with burnup due to fissile-element buildup in the ThO{sub 2} region. - Abstract: The Pressure-Tube Supercritical-Water-Cooled Reactor (PT-SCWR) is one of the concepts under investigation by the Generation IV International Forum for its promise to deliver higher thermal efficiency than nuclear reactors currently in operation. The high coolant temperature (>625 K) and high linear power density employed by the PT-SCWR cause the fuel temperature to be fairly high, leading to a reduced margin to fuel melting, thus increasing the risk of actual melting during accident scenarios. It is therefore desirable to come up with a fuel design that lowers the fuel temperature while preserving the high linear power ratio and high coolant temperature. One possible solution is to separate the fertile (ThO{sub 2}) and fissile (PuO{sub 2}) fuel materials into different radial regions in each fuel pin. Previously-reported work found that by locating the fertile material at the centre and the fissile material at the periphery of the fuel pin, the fuel centreline temperature can be reduced by ∼650 K for fresh fuel compared to the case of a homogeneous (Th–Pu)O{sub 2} mixture for the same coolant temperature and linear power density. This work provides a justification for the observed reduction in fuel centreline temperature and suggests a systematic approach to lower the fuel temperature. It also extends the analysis to the dependence of the radial temperature profile on fuel burnup. The radial temperature profile is

Heat Transfer Characteristics of the Supercritical CO2 Flowing in a Vertical Annular Channel

International Nuclear Information System (INIS)

Yoo, Tae Ho; Bae, Yoon Yeong; Kim, Hwan Yeol

2010-01-01

Heat transfer test facility, SPHINX(Supercritical Pressure Heat transfer Investigation for NeXt generation), has been operated at KAERI for an investigation of the thermal-hydraulic characteristics of supercritical CO 2 at several test sections with a different geometry. The loop uses CO 2 because it has much lower critical pressure and temperature than those of water. Experimental study of heat transfer to supercritical CO 2 in a vertical annular channel with and hydraulic diameter of 4.5 mm has been performed. CO 2 flows downward through the annular channel simulating the downward-flowing coolant in a multi-pass reactor or water rod moderator in a single pass reactor. The heat transfer characteristics in a downward flow were analyzed and compared with the upward flow test results performed previously with the same test section at KAERI

Experimental and numerical investigation of heat transfer from a narrow annulus to supercritical pressure water

International Nuclear Information System (INIS)

Wang, Han; Bi, Qincheng; Yang, Zhendong; Wang, Linchuan

2015-01-01

Highlights: • Heat transfer of supercritical water in a narrow annulus is investigated. • Effects of system parameters and flow direction on heat transfer are studied. • Deteriorated heat transfer is analyzed both experimentally and numerically. - Abstract: Heat transfer characteristics of supercritical pressure water in a narrow annulus with vertically upward and downward flows were investigated experimentally and numerically. The outer diameter of the inner heated rod is 8 mm with an effective heated length of 620 mm. Experimental parameters covered the pressure of 23–28 MPa, mass flux of 400–1000 kg/m 2 s and heat flux on the outer surface of the heated rod from 200 to 1000 kW/m 2 . The general heat transfer behaviors were discussed with respect to various mass fluxes and pressures. According to the experimental data, it was found that the effect of flow direction on heat transfer depends on the heat-flux to mass-flux ratio (q/G). Heat transfer is much improved in the downward flow compared to that of upward flow at high q/G ratios. At the pressure of 25 MPa, low-mass-flux deteriorated heat transfer occurred in the upward flow but not in the downward flow. At the same test parameters, however, heat transfer deterioration was observed at both of the two flow directions when the pressure was lowered to 23 MPa. The experimental results indicate that buoyancy plays an important role for this type of deterioration, but is not the only mechanism that leads to the heat transfer deterioration. Three turbulence models were assessed against the annulus test data, it was found that the SST k-ω model gives a satisfying prediction of heat transfer deterioration especially for the case of downward flow. The mechanisms for the low-mass-flow heat transfer deterioration were investigated from the viewpoints of buoyancy and property variations of the supercritical water

Enhancing power cycle efficiency for a supercritical Brayton cycle power system using tunable supercritical gas mixtures

Science.gov (United States)

Wright, Steven A.; Pickard, Paul S.; Vernon, Milton E.; Radel, Ross F.

2017-08-29

Various technologies pertaining to tuning composition of a fluid mixture in a supercritical Brayton cycle power generation system are described herein. Compounds, such as Alkanes, are selectively added or removed from an operating fluid of the supercritical Brayton cycle power generation system to cause the critical temperature of the fluid to move up or down, depending upon environmental conditions. As efficiency of the supercritical Brayton cycle power generation system is substantially optimized when heat is rejected near the critical temperature of the fluid, dynamically modifying the critical temperature of the fluid based upon sensed environmental conditions improves efficiency of such a system.

Pulse radiolysis study of supercritical water-G-value measurement up to 450 degree C

International Nuclear Information System (INIS)

Katsumura, Y.

2006-01-01

It is widely recognized that the understanding of water radiolysis at elevated temperatures is inevitably important in the field of water chemistry in light water reactors because water radiolysis is closely related to many subjects such as hydrogen water chemistry (H 2 injection), SCC (stress corrosion cracking), dose accumulation and so on. This situation would also be applied to the future reactor using supercritical water (>374 C, 22.1MPa) as a coolant, so called supercritical water-cooled reactor (SCWR). Therefore, it is important to investigate water radiolysis of supercritical water. In 1989 Prof. Oka, University of Tokyo, proposed the SCWR as a future reactor and done much design study. This reactor has many advantages such as high energy efficiency, applicability of experience accumulated in light water reactors and supercritical fissile plant, and compact structure. In 2002 the Department of Energy in USA has selected the SCWR as one of the six Generation IV reactors and fundamental research has started in different countries as a national or an international project. In the present research G-values of water radiolysis have been measured by using a pulse radiolysis method up to 450 degree C to obtain the fundamental data relevant to the development of the SCWR. In supercritical water, the pressure controls the density of water easily and it was found that the G-values are strongly dependent not only on temperature but also on density in supercritical water. After presentation of experimental method and its difficulties, temperature and density dependent G-values of water decomposition products in supercritical water would be summarized. (authors)

Numerical comparison of thermal hydraulic aspects of supercritical carbon dioxide and subcritical water-based natural circulation loop

Energy Technology Data Exchange (ETDEWEB)

Sarkar, Milan Krishna Singhar; Basu, Dipankar Narayan [Dept. of Mechanical Engineering, Indian Institute of Technology Guwahati, Guwahati (India)

2017-02-15

Application of the supercritical condition in reactor core cooling needs to be properly justified based on the extreme level of parameters involved. Therefore, a numerical study is presented to compare the thermalhydraulic performance of supercritical and single-phase natural circulation loops under low-to-intermediate power levels. Carbon dioxide and water are selected as respective working fluids, operating under an identical set of conditions. Accordingly, a three-dimensional computational model was developed, and solved with an appropriate turbulence model and equations of state. Large asymmetry in velocity and temperature profiles was observed in a single cross section due to local buoyancy effect, which is more prominent for supercritical fluids. Mass flow rate in a supercritical loop increases with power until a maximum is reached, which subsequently corresponds to a rapid deterioration in heat transfer coefficient. That can be identified as the limit of operation for such loops to avoid a high temperature, and therefore, the use of a supercritical loop is suggested only until the appearance of such maxima. Flow-induced heat transfer deterioration can be delayed by increasing system pressure or lowering sink temperature. Bulk temperature level throughout the loop with water as working fluid is higher than supercritical carbon dioxide. This is until the heat transfer deterioration, and hence the use of a single-phase loop is prescribed beyond that limit.

Systems design of direct-cycle supercritical-water-cooled fast reactors

International Nuclear Information System (INIS)

Oka, Yoshiaki; Koshizuka, Seiichi; Jevremovic, Tatjana; Okano, Yashushi

1995-01-01

The system design of a direct-cycle supercritical-water-cooled fast reactor is presented. The supercritical water does not exhibit a change of phase. the recirculation system, steam separator, and dryer of a boiling water reactor (BWR) are unnecessary. Roughly speaking, the reactor pressure vessel and control rods are similar to those of a pressurized water reactor, the containment and emergency core cooling system are similar to a BWR, and the balance of plant is similar to a supercritical-pressure fossil-fired power plant (FPP). the electric power of the fast converter is 1,508 MW(electric). The number of coolant loops is only two because of the high coolant enthalpy. Containment volume is much reduced. The thermal efficiency is improved 24% over a BWR. The coolant void reactivity is negative by placing thin zirconium-hydride layers between seeds and blankets. The power costs would be much reduced compared with those of a light water reactor (LWR) and a liquid-metal fast breeder reactor. The concept is based on the huge amount of experience with the water coolant technology of LWRs and FPPs. The oxidation of stainless steel cladding is avoided by adopting a much lower coolant temperature than that of the FPP

A system for traceable measurement of the microwave complex permittivity of liquids at high pressures and temperatures

International Nuclear Information System (INIS)

Dimitrakis, G A; Robinson, J; Kingman, S; Lester, E; George, M; Poliakoff, M; Harrison, I; Gregory, A P; Lees, K

2009-01-01

A system has been developed for direct traceable dielectric measurements on liquids at high pressures and temperatures. The system consists of a coaxial reflectometric sensor terminated by a metallic cylindrical cell to contain the liquid. It has been designed for measurements on supercritical liquids, but as a first step measurements on dielectric reference liquids were performed. This paper reports on a full evaluation of the system up to 2.5 GHz using methanol, ethanol and n-propanol at pressures up to 9 MPa and temperatures up to 273 °C. A comprehensive approach to the evaluation of uncertainties using Monte Carlo modelling is used

Geological Model of Supercritical Geothermal Reservoir on the Top of the Magma Chamber

Science.gov (United States)

Tsuchiya, N.

2017-12-01

We are conducting supercritical geothermal project, and deep drilling project named as "JBBP: Japan Beyond Brittle Project" The temperatures of geothermal fields operating in Japan range from 200 to 300 °C (average 250 °C), and the depths range from 1000 to 2000 m (average 1500 m). In conventional geothermal reservoirs, the mechanical behavior of the rocks is presumed to be brittle, and convection of the hydrothermal fluid through existing network is the main method of circulation in the reservoir. In order to minimize induced seismicity, a rock mass that is "beyond brittle" is one possible candidate, because the rock mechanics of "beyond brittle" material is one of plastic deformation rather than brittle failure. To understand the geological model of a supercritical geothermal reservoir, granite-porphyry system, which had been formed in subduction zone, was investigated as a natural analog of the supercritical geothermal energy system. Quartz veins, hydrothermal breccia veins, and glassy veins are observed in a granitic body. The glassy veins formed at 500-550 °C under lithostatic pressures, and then pressures dropped drastically. The solubility of silica also dropped, resulting in formation of quartz veins under a hydrostatic pressure regime. Connections between the lithostatic and hydrostatic pressure regimes were key to the formation of the hydrothermal breccia veins, and the granite-porphyry system provides useful information for creation of fracture clouds in supercritical geothermal reservoirs. A granite-porphyry system, associated with hydrothermal activity and mineralization, provides a suitable natural analog for studying a deep-seated geothermal reservoir where stockwork fracture systems are created in the presence of supercritical geothermal fluids. I describe fracture networks and their formation mechanisms using petrology and fluid inclusion studies in order to understand this "beyond brittle" supercritical geothermal reservoir, and a geological

Heat Transfer Experiments with Supercritical CO{sub 2} in a Vertical Circular Tube (9.0 mm)

Energy Technology Data Exchange (ETDEWEB)

Yoo, Tae Ho; Kim, Hwan Yeol [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Sim, Woo Gun; Bae, Yoon Yeong [Hannam University, Daejeon (Korea, Republic of)

2008-10-15

Heat transfer test facility, SPHINX(Supercritical Pressure Heat transfer Investigation for NeXt generation), has been operated at KAERI for an investigation of the thermal-hydraulic behaviors of supercritical CO{sub 2} at several test sections with a different geometry. The loop uses CO{sub 2} because it has critical pressure and temperature which is much lower than water. Experimental study of heat transfer to supercritical CO{sub 2} in a vertical circular tube with and inner diameter of 9.0mm has been performed. CO{sub 2} flows downward through the vertical circular tube for the simulation of the water rod which may be used for a moderation of the reactor. The heat transfer characteristics were analyzed and compared with the upward flow test results previously performed at the same test section at KAERI.

Parametric optimization design for supercritical CO2 power cycle using genetic algorithm and artificial neural network

International Nuclear Information System (INIS)

Wang Jiangfeng; Sun Zhixin; Dai Yiping; Ma Shaolin

2010-01-01

Supercritical CO 2 power cycle shows a high potential to recover low-grade waste heat due to its better temperature glide matching between heat source and working fluid in the heat recovery vapor generator (HRVG). Parametric analysis and exergy analysis are conducted to examine the effects of thermodynamic parameters on the cycle performance and exergy destruction in each component. The thermodynamic parameters of the supercritical CO 2 power cycle is optimized with exergy efficiency as an objective function by means of genetic algorithm (GA) under the given waste heat condition. An artificial neural network (ANN) with the multi-layer feed-forward network type and back-propagation training is used to achieve parametric optimization design rapidly. It is shown that the key thermodynamic parameters, such as turbine inlet pressure, turbine inlet temperature and environment temperature have significant effects on the performance of the supercritical CO 2 power cycle and exergy destruction in each component. It is also shown that the optimum thermodynamic parameters of supercritical CO 2 power cycle can be predicted with good accuracy using artificial neural network under variable waste heat conditions.

Optimization of supercritical fluid extraction and HPLC identification of wedelolactone from Wedelia calendulacea by orthogonal array design.

Science.gov (United States)

Patil, Ajit A; Sachin, Bhusari S; Wakte, Pravin S; Shinde, Devanand B

2014-11-01

The purpose of this work is to provide a complete study of the influence of operational parameters of the supercritical carbon dioxide assisted extraction (SC CO2E) on yield of wedelolactone from Wedelia calendulacea Less., and to find an optimal combination of factors that maximize the wedelolactone yield. In order to determine the optimal combination of the four factors viz. operating pressure, temperature, modifier concentration and extraction time, a Taguchi experimental design approach was used: four variables (three levels) in L9 orthogonal array. Wedelolactone content was determined using validated HPLC methodology. Optimum extraction conditions were found to be as follows: extraction pressure, 25 MPa; temperature, 40 °C; modifier concentration, 10% and extraction time, 90 min. Optimum extraction conditions demonstrated wedelolactone yield of 8.01 ± 0.34 mg/100 g W. calendulacea Less. Pressure, temperature and time showed significant (p yield. The supercritical carbon dioxide extraction showed higher selectivity than the conventional Soxhlet assisted extraction method.

Extraction of Stevia rebaudiana bertoni sweetener glycosides by supercritical fluid methods.

Directory of Open Access Journals (Sweden)

Juan José Hinojosa-González

2017-05-01

Full Text Available Aim. The aim was to evaluate the supercritical carbon dioxide extraction method with and without the addition of co-solvent to the system (mixture water: ethanol to obtain the glycosides from leaves of Stevia rebaudiana Bertoni. Methods. A SFT-150 SFE / SFR model with CO2 as a fluid was used for the supercritical extraction. The variables studied were temperature, pressure, extraction time and the presence or absence of the co-solvent (water-ethanol mixture in a concentration of 70:30 v/v, incorporated in different proportions to determine the effect on yield. The amount of glycoside sweeteners was analyzed by High Performance Liquid Chromatography (HPLC. Results. The pressure was the factor that favored the extraction, which was selective in obtaining Rebaudioside A with yields no greater than 2%. The inclusion of the co-solvent achieved an increase in yield to values of 2.9% Conclusion. Supercritical CO2 individually and mixed with ethanol-water as a co-solvent was not efficient to extract Stevia rebaudiana stevioside sweeteners

Supercritical heat transfer in an annular channel with two-sided heaing

International Nuclear Information System (INIS)

Sergeev, V.V.; Remizov, O.V.; Gal'chenko, Eh.F.

1986-01-01

The paper deals with experimental inestigation into worsening of heat transfer at forced up flow in steam-water mixture in a vertical annular channel with two-sided heating and development of technique for calculation of supercritical heat exchange in this channel. Bench-scale experiments are carried out at high-pressure at mass rates of the coolant equal to 300-865 kg/(m 2 x s), pressure of 9.8-17.8 MPa and heat flux on the internal surface - 20-400 kW/m 2 , on the external surface - 35-450 kW/m 2 . Technique for calculation of supercritical heat exchange in channels with one- and two-sided heating is suggested. Analysis of the obtained experimental data permits to determine conditions for arising departure nucleate boiling on the internal and external surfaces and on both surfaces simultaneously. It is concluded that the suggested technique of calculation adequately reflects the effect of regime parameters of coolant flow on temperature regime of heat transferring surfaces in the supercritical area

Heat Transfer Characteristics of the Supercritical CO{sub 2} Flowing in a Vertical Annular Channel

Energy Technology Data Exchange (ETDEWEB)

Yoo, Tae Ho; Bae, Yoon Yeong; Kim, Hwan Yeol [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2010-05-15

Heat transfer test facility, SPHINX(Supercritical Pressure Heat transfer Investigation for NeXt generation), has been operated at KAERI for an investigation of the thermal-hydraulic characteristics of supercritical CO{sub 2} at several test sections with a different geometry. The loop uses CO{sub 2} because it has much lower critical pressure and temperature than those of water. Experimental study of heat transfer to supercritical CO{sub 2} in a vertical annular channel with and hydraulic diameter of 4.5 mm has been performed. CO{sub 2} flows downward through the annular channel simulating the downward-flowing coolant in a multi-pass reactor or water rod moderator in a single pass reactor. The heat transfer characteristics in a downward flow were analyzed and compared with the upward flow test results performed previously with the same test section at KAERI

Performance Analysis and Working Fluid Selection of a Supercritical Organic Rankine Cycle for Low Grade Waste Heat Recovery

Directory of Open Access Journals (Sweden)

Yourong Li

2012-08-01

Full Text Available The performance analysis of a supercritical organic Rankine cycle system driven by exhaust heat using 18 organic working fluids is presented. Several parameters, such as the net power output, exergy efficiency, expander size parameter (SP, and heat exchanger requirement of evaporator and the condenser, were used to evaluate the performance of this recovery cycle and screen the working fluids. The results reveal that in most cases, raising the expander inlet temperature is helpful to improve the net power output and the exergy efficiency. However, the effect of the expander inlet pressure on those parameters is related to the expander inlet temperature and working fluid used. Either lower expander inlet temperature and pressure, or higher expander inlet temperature and pressure, generally makes the net power output more. Lower expander inlet temperature results in larger total heat transfer requirement and expander size. According to the screening criteria of both the higher output and the lower investment, the following working fluids for the supercritical ORC system are recommended: R152a and R143a.

Synthesis of p-Phenylenediamine (PPD) using Supercritical Ammonia

International Nuclear Information System (INIS)

Cho, Hang-Kyu; Lim, Jong Sung

2015-01-01

In this study, investigated the synthesis method of p-Phenylenediamine (PPD) by amination of p-Diiodobenzene (PDIB) under supercritical ammonia and CuI catalyst conditions. We examined the effects of various process variables (e.g., reaction temperature, pressure, amount of ammonia inserted, amount of catalyst inserted, and reaction time) on the production yield of PPD by analyzing the Gas Chromatography (GC). The experimental results demonstrated that PPD was not produced under non-catalyst conditions, and PPD production yield increased with increasing temperature, pressure, amount of catalyst inserted, and reaction time. However, for the reaction temperature case, it was found that 200 .deg. C was the optimal temperature, because thermal degradation of PPD occurred above 250 .deg. C. In addition, we confirmed the structure of PPD and the bonding characteristics of the amine group via FT-IR and H-NMR analysis

Synthesis of p-Phenylenediamine (PPD) using Supercritical Ammonia

Energy Technology Data Exchange (ETDEWEB)

Cho, Hang-Kyu; Lim, Jong Sung [Sogang University, Seoul (Korea, Republic of)

2015-02-15

In this study, investigated the synthesis method of p-Phenylenediamine (PPD) by amination of p-Diiodobenzene (PDIB) under supercritical ammonia and CuI catalyst conditions. We examined the effects of various process variables (e.g., reaction temperature, pressure, amount of ammonia inserted, amount of catalyst inserted, and reaction time) on the production yield of PPD by analyzing the Gas Chromatography (GC). The experimental results demonstrated that PPD was not produced under non-catalyst conditions, and PPD production yield increased with increasing temperature, pressure, amount of catalyst inserted, and reaction time. However, for the reaction temperature case, it was found that 200 .deg. C was the optimal temperature, because thermal degradation of PPD occurred above 250 .deg. C. In addition, we confirmed the structure of PPD and the bonding characteristics of the amine group via FT-IR and H-NMR analysis.

Supercritical fluid technology: concepts and pharmaceutical applications.

Science.gov (United States)

Deshpande, Praful Balavant; Kumar, G Aravind; Kumar, Averineni Ranjith; Shavi, Gopal Venkatesh; Karthik, Arumugam; Reddy, Meka Sreenivasa; Udupa, Nayanabhirama

2011-01-01

In light of environmental apprehension, supercritical fluid technology (SFT) exhibits excellent opportunities to accomplish key objectives in the drug delivery sector. Supercritical fluid extraction using carbon dioxide (CO(2)) has been recognized as a green technology. It is a clean and versatile solvent with gas-like diffusivity and liquid-like density in the supercritical phase, which has provided an excellent alternative to the use of chemical solvents. The present commentary provides an overview of different techniques using supercritical fluids and their future opportunity for the drug delivery industry. Some of the emerging applications of SFT in pharmaceuticals, such as particle design, drug solubilization, inclusion complex, polymer impregnation, polymorphism, drug extraction process, and analysis, are also covered in this review. The data collection methods are based on the recent literature related to drug delivery systems using SFT platforms. SFT has become a much more versatile and environmentally attractive technology that can handle a variety of complicated problems in pharmaceuticals. This cutting-edge technology is growing predominantly to surrogate conventional unit operations in relevance to the pharmaceutical production process. Supercritical fluid technology has recently drawn attention in the field of pharmaceuticals. It is a distinct conception that utilizes the solvent properties of supercritical fluids above their critical temperature and pressure, where they exhibit both liquid-like and gas-like properties, which can enable many pharmaceutical applications. For example, the liquid-like properties provide benefits in extraction processes of organic solvents or impurities, drug solubilization, and polymer plasticization, and the gas-like features facilitate mass transfer processes. It has become a much more versatile and environmentally attractive technology that can handle a variety of complicated problems in pharmaceuticals. This review is

Experiments on a forced convection heat transfer at supercritical pressures - 6.32 mm ID tube

Energy Technology Data Exchange (ETDEWEB)

Bae, Yoon Yeong; Kim, Hwan Yeol

2009-08-15

The size of a sub-channel of the conceptual SCWR core design studied at KAERI is 6.5 mm. In order to provide heat transfer information in such a narrow sub-channel at supercritical pressure, an experiment was performed with a test section made of Inconel 625 tube of 6.32 mm ID. The test pressures were 7.75 and 8.12 MPa corresponding to 1.05 and 1.1 times the critical pressure of CO{sub 2}, respectively. The mass flux and heat flux, which were in the range of 285 {approx} 1200 kg/m2s and 30 {approx} 170 kW/m2, were changed at a given system pressure. The corresponding Reynolds numbers are 1.8 x 10{sup 4} {approx} 7.5 x 10{sup 4}. The effect of mass flux and heat flux was dominant factor in the supercritical pressure heat transfer while the effect of pressure was negligible. The Bishop's correlation predicted the test result most closely and Bae and Kim's recent correlation was the next. The heat transfer deterioration occurred when GR)b/Re{sub b}{sup 2.7} > 2.0 x 10{sup -5}. As soon as the heat transfer was deteriorated, it entered a new regime and did not recover the normal heat transfer nevertheless Gr{sub b}/Re{sub b}{sup 2.7} reduced below 2.0 x 10{sup -5}. It may mean that the correlation must be developed for the normal and deterioration regime separately.

Evaluation and optimization of a supercritical carbon dioxide power conversion cycle for nuclear applications

International Nuclear Information System (INIS)

Harvego, Edwin A.; McKellar, Michael G.

2011-01-01

There have been a number of studies involving the use of gases operating in the supercritical mode for power production and process heat applications. Supercritical carbon dioxide (CO 2 ) is particularly attractive because it is capable of achieving relatively high power conversion cycle efficiencies in the temperature range between 550degC and 750degC. Therefore, it has the potential for use with any type of high-temperature nuclear reactor concept, assuming reactor core outlet temperatures of at least 550degC. The particular power cycle investigated in this paper is a supercritical CO 2 recompression Brayton Cycle. The CO 2 recompression Brayton Cycle can be used as either a direct or indirect power conversion cycle, depending on the reactor type and reactor outlet temperature. The advantage of this cycle when compared to the helium Brayton Cycle is the lower required operating temperature; 550degC versus 750degC. However, the supercritical CO 2 recompression Brayton Cycle requires a high end operating pressure in the range of 20 MPa, which is considerably higher than the required helium Brayton cycle high end operating pressure of 7 MPa. This paper presents results of analyses performed using the UniSim process analyses software to evaluate the performance of the supercritical CO 2 recompression Brayton cycle for different reactor coolant outlet temperatures and mass flow rates. The UniSim model assumed a 600 MWt reactor power source, which provides heat to the power cycle at a maximum temperature of between 550degC and 850degC. Sensitivity calculations were also performed to determine the affect of reactor coolant mass flow rates for a reference reactor coolant outlet temperature of 750degC. The UniSim model used realistic component parameters and operating conditions to model the complete power conversion system. CO 2 properties were evaluated, and the operating range for the cycle was adjusted to take advantage of the rapidly changing conditions near the

Design of Test Loops for Forced Convection Heat Transfer Studies at Supercritical State

Science.gov (United States)

Balouch, Masih N.

Worldwide research is being conducted to improve the efficiency of nuclear power plants by using supercritical water (SCW) as the working fluid. One such SCW reactor considered for future development is the CANDU-Supercritical Water Reactor (CANDU-SCWR). For safe and accurate design of the CANDU-SCWR, a detailed knowledge of forced-convection heat transfer in SCW is required. For this purpose, two supercritical fluid loops, i.e. a SCW loop and an R-134a loop are developed at Carleton University. The SCW loop is designed to operate at pressures as high as 28 MPa, temperatures up to 600 °C and mass fluxes of up to 3000 kg/m2s. The R-134a loop is designed to operate at pressures as high as 6 MPa, temperatures up to 140 °C and mass fluxes in the range of 500-6000 kg/m2s. The test loops designs allow for up to 300 kW of heating power to be imparted to the fluid. Both test loops are of the closed-loop design, where flow circulation is achieved by a centrifugal pump in the SCW loop and three parallel-connected gear pumps in the R-134a loop, respectively. The test loops are pressurized using a high-pressure nitrogen cylinder and accumulator assembly, which allows independent control of the pressure, while simultaneously dampening pump induced pressure fluctuations. Heat exchangers located upstream of the pumps control the fluid temperature in the test loops. Strategically located measuring instrumentation provides information on the flow rate, pressure and temperature in the test loops. The test loops have been designed to accommodate a variety of test-section geometries, ranging from a straight circular tube to a seven-rod bundle, achieving heat fluxes up to 2.5 MW/m2 depending on the test-section geometry. The design of both test loops allows for easy reconfiguration of the test-section orientation relative to the gravitational direction. All the test sections are of the directly-heated design, where electric current passing through the pressure retaining walls of the

Determination of major aromatic constituents in vanilla using an on-line supercritical fluid extraction coupled with supercritical fluid chromatography.

Science.gov (United States)

Liang, Yanshan; Liu, Jiaqi; Zhong, Qisheng; Shen, Lingling; Yao, Jinting; Huang, Taohong; Zhou, Ting

2018-04-01

An on-line supercritical fluid extraction coupled with supercritical fluid chromatography method was developed for the determination of four major aromatic constituents in vanilla. The parameters of supercritical fluid extraction were systematically investigated using single factor optimization experiments and response surface methodology by a Box-Behnken design. The modifier ratio, split ratio, and the extraction temperature and pressure were the major parameters which have significant effects on the extraction. While the static extraction time, dynamic extraction time, and recycle time had little influence on the compounds with low polarity. Under the optimized conditions, the relative extraction efficiencies of all the constituents reached 89.0-95.1%. The limits of quantification were in the range of 1.123-4.747 μg. The limits of detection were in the range of 0.3368-1.424 μg. The recoveries of the four analytes were in the range of 76.1-88.9%. The relative standard deviations of intra- and interday precision ranged from 4.2 to 7.6%. Compared with other off-line methods, the present method obtained higher extraction yields for all four aromatic constituents. Finally, this method has been applied to the analysis of vanilla from different sources. On the basis of the results, the on-line supercritical fluid extraction-supercritical fluid chromatography method shows great promise in the analysis of aromatic constituents in natural products. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of hydrostatic pressure and supercritical carbon dioxide on the viability of Botryococcus braunii algae cells.

Science.gov (United States)

Yildiz-Ozturk, Ece; Ilhan-Ayisigi, Esra; Togtema, Arnoud; Gouveia, Joao; Yesil-Celiktas, Ozlem

2018-05-01

In bio-based industries, Botryococcus braunii is identified as a potential resource for production of hydrocarbons having a wide range of applications in chemical and biopolymer industries. For a sustainable production platform, the algae cultivation should be integrated with downstream processes. Ideally the algae are not harvested, but the product is isolated while cultivation and growth is continued especially if the doubling time is slow. Consequently, hydrocarbons can be extracted while keeping the algae viable. In this study, the effects of pressure on the viability of B. braunii cells were tested hydrostatically and under supercritical CO 2 conditions. Viability was determined by light microscopy, methylene blue uptake and by re-cultivation of the algae after treatments to follow the growth. It was concluded that supercritical CO 2 was lethal to the algae, whereas hydrostatic pressure treatments up to 150 bar have not affected cell viability and recultivation was successful. Copyright © 2018 Elsevier Ltd. All rights reserved.

Fatty acid methyl esters synthesis from non-edible vegetable oils using supercritical methanol and methyl tert-butyl ether

International Nuclear Information System (INIS)

Lamba, Neha; Modak, Jayant M.; Madras, Giridhar

2017-01-01

Highlights: • FAMEs were synthesized from non-edible oils using supercritical MeOH and MTBE. • Effect of time, temperature, pressure and molar ratio on conversions was studied. • Rate constants of reaction with methanol and MTBE differ by an order of magnitude. • Non-catalytic supercritical reactions are one order faster than acid catalyzed synthesis. - Abstract: Fatty acid methyl esters (FAMEs) are useful as biodiesel and have environmental benefits compared to conventional diesel. In this study, these esters were synthesized non-catalytically from non-edible vegetable oils: neem oil and mahua oil with two different methylating agents: methanol and methyl tert-butyl ether (MTBE). The effects of temperature, pressure, time and molar ratio on the conversion of triglycerides were studied. The temperature was varied in the range of 523–723 K with molar ratios upto 50:1 and a reaction time of upto 150 min. Conversion of neem and mahua oil to FAMEs with supercritical methanol was found to be 83% in 15 min and 99% in 10 min, respectively at 698 K. Further, a conversion of 46% of mahua oil and 59% of neem oil was obtained in 15 min at 723 K using supercritical MTBE. The rate constants evaluated using pseudo first order reaction kinetics were in the range of 4.7 × 10"−"6 to 1.0 × 10"−"3 s"−"1 for the investigated range of temperatures. The activation energies obtained were in the range of 62–113 kJ/mol for the reaction systems investigated. The supercritical synthesis was found to be superior to the catalytic synthesis of the corresponding FAMEs.

SiC Coating Process Development Using H-PCS in Supercritical CO2

International Nuclear Information System (INIS)

Park, Kwangheon; Jung, Wonyoung

2013-01-01

We tried SiC coating using supercritical fluids. Supercritical fluids are the substance exists over critical temperature and critical pressure. It is hard to expect that there would be a big change as single-solvent as the fluid is incompressible and the space between the molecules is almost steady. But the fluid which is being supercritical can bring a great change when it is changed its pressure near its critical point, showing its successive change in the density, viscosity, diffusion coefficient and the polarity. We have tested the 'H-PCS into SiC' coating experiment with supercritical CO 2 which has the high penetration, low viscosity as well as the high density and the high solubility that shows the property of the fluid. This experiment is for SiC coating using H-PCS in supercritical CO 2 . It shows the clear difference that the penetration of H-PCS into the SiC between dip coating method and using the supercritical CO 2 If we can make a metal cladding with SiC composites as a protective layer, the use of the cladding will be very broad and diverse. Inherent safe nuclear fuels can be possible that can stand under severe accident conditions. SiC is known to be one of a few materials that maintain very corrosion-resistant properties under tough corrosive environments. The metal cladding with SiC composites as a protective layer will be a high-tech product that can be used in many applications including chemical, material, and nuclear engineering and etc

Extraction of heavy oil by supercritical carbon dioxide

DEFF Research Database (Denmark)

Rudyk, Svetlana Nikolayevna; Spirov, Pavel; Søgaard, Erik Gydesen

2010-01-01

The present study deals with the extraction of heavy oil by supercritical carbon dioxide at the pressure values changing from 16 to 56 MPa at the fixed value of temperature: 60oC. The amount of the recovered liquid phase of oil was calculated as a percentage of the extracted amount to the initial...... 40 gm of oil. The noticeable breackover point in the graph of the oil recovery versus pressure was observed at 27 MPa, which was in concordance with the conclusions from chromatographic analysis of the extracted oil samples. But the recovery rate of 14 % at this pressure value was not high enough...

Corrosion phenomena on alloy 625 in aqueous solutions containing hydrochloric acid and oxygen under subcritical and supercritical conditions

International Nuclear Information System (INIS)

Boukis, N.; Kritzer, P.

1997-01-01

Supercritical Water Oxidation (SCWO) is a very effective process to destroy hazardous aqueous wastes containing organic contaminants. The main target applications in the USA are the destruction of DOD and DOE wastes such as rocket fuels and explosives, warfare agents and organics present in low level radioactive liquid wastes. Alloy 625 is frequently used as reactor material for Supercritical Water Oxidation (SCWO) applications. This is due to the favorable combination of mechanical properties, corrosion resistance, price and availability. Nevertheless, the corrosion of alloy 625 like the corrosion of other Ni-base alloys during oxidation of hazardous organic waste containing chloride proceeds too fast and is a major problem in SCWO applications. In these experiments high pressure, high-temperature resistant tube reactors made of alloy 625 were used as specimens. They were exposed to SCWO conditions, without organics, at temperatures up to 500 C and pressures up to 37 MPa for up to 150 h. Simultaneously, coupons also made from alloy 625 are exposed inside the test tubes. The most important corrosion problem for alloy 625 is pitting and intercrystalline corrosion at temperatures near the critical temperature, i.e. in the preheater and cooling sections of the test tubes. Under certain conditions, stress corrosion cracking appears and leads to premature failure of the test reactors. The corrosion products were insoluble in supercritical water and formed thick layers in the supercritical part of the reactor. Under these layers only minor corrosion occurred. 33 refs

Supercritical CO2 extraction of candlenut oil: process optimization using Taguchi orthogonal array and physicochemical properties of the oil.

Science.gov (United States)

Subroto, Erna; Widjojokusumo, Edward; Veriansyah, Bambang; Tjandrawinata, Raymond R

2017-04-01

A series of experiments was conducted to determine optimum conditions for supercritical carbon dioxide extraction of candlenut oil. A Taguchi experimental design with L 9 orthogonal array (four factors in three levels) was employed to evaluate the effects of pressure of 25-35 MPa, temperature of 40-60 °C, CO 2 flow rate of 10-20 g/min and particle size of 0.3-0.8 mm on oil solubility. The obtained results showed that increase in particle size, pressure and temperature improved the oil solubility. The supercritical carbon dioxide extraction at optimized parameters resulted in oil yield extraction of 61.4% at solubility of 9.6 g oil/kg CO 2 . The obtained candlenut oil from supercritical carbon dioxide extraction has better oil quality than oil which was extracted by Soxhlet extraction using n-hexane. The oil contains high unsaturated oil (linoleic acid and linolenic acid), which have many beneficial effects on human health.

Removal of common organic solvents from aqueous waste streams via supercritical C02 extraction: a potential green approach to sustainable waste management in the pharmaceutical industry.

Science.gov (United States)

Leazer, Johnnie L; Gant, Sean; Houck, Anthony; Leonard, William; Welch, Christopher J

2009-03-15

Supercritical CO2 extraction of aqueous streams is a convenient and effective method to remove commonly used solvents of varying polarities from aqueous waste streams. The resulting aqueous layers can potentially be sewered; whereas the organic layer can be recovered for potential reuse. Supercritical fluid extraction (SFE) is a technology that is increasingly being used in commercial processes (1). Supercritical fluids are well suited for extraction of a variety of media, including solids, natural products, and liquid products. Many supercritical fluids have low critical temperatures, allowing for extractions to be done at modestly low temperatures, thus avoiding any potential thermal decomposition of the solutes under study (2). Furthermore, the CO2 solvent strength is easily tuned by adjusting the density of the supercritical fluid (The density is proportional to the pressure of the extraction process). Since many supercritical fluids are gases at ambient temperature, the extract can be concentrated by simply venting the reaction mixture to a cyclone collection vessel, using appropriate safety protocols.

Heat transfer characteristics of supercritical pressure waster in vertical upward annular channels

International Nuclear Information System (INIS)

Wang Han; Bi Qincheng; Yang Zhendong; Wu Gang

2013-01-01

Within the range of pressure from 23 to 28 MPa, mass flux from 350 to 1000 kg/(m 2 · s), and outside wall heat flux from 200 to 1000 kW/m 2 , experimental investigation was conducted on the heat transfer characteristics of supercritical pressure water in vertical upward annular channels. The effects of heat flux, pressure, mass flux and spiral spacer on heat transfer were analyzed, and two types of heat transfer deterioration occurred in the experiments were compared. The experimental results show that the heat transfer of water can be enhanced by increasing the mass flux or decreasing the wall heat flux. The effect of pressure on heat transfer is not uniform and depends on heat transfer form. It was found that the spiral spacer not only enhances the heat transfer of water, but also delays the heat transfer deterioration which occurs in high heat flux and low mass flux conditions. (authors)

Coupling of Modular High-Temperature Gas-Cooled Reactor with Supercritical Rankine Cycle

Directory of Open Access Journals (Sweden)

Shutang Zhu

2008-01-01

Full Text Available This paper presents investigations on the possible combination of modular high-temperature gas-cooled reactor (MHTGR technology with the supercritical (SC steam turbine technology and the prospective deployments of the MHTGR SC power plant. Energy conversion efficiency of steam turbine cycle can be improved by increasing the main steam pressure and temperature. Investigations on SC water reactor (SCWR reveal that the development of SCWR power plants still needs further research and development. The MHTGR SC plant coupling the existing technologies of current MHTGR module design with operation experiences of SC FPP will achieve high cycle efficiency in addition to its inherent safety. The standard once-reheat SC steam turbine cycle and the once-reheat steam cycle with life-steam have been studied and corresponding parameters were computed. Efficiencies of thermodynamic processes of MHTGR SC plants were analyzed, while comparisons were made between an MHTGR SC plant and a designed advanced passive PWR - AP1000. It was shown that the net plant efficiency of an MHTGR SC plant can reach 45% or above, 30% higher than that of AP1000 (35% net efficiency. Furthermore, an MHTGR SC plant has higher environmental competitiveness without emission of greenhouse gases and other pollutants.

Experimental study on the supercritical startup and heat transport capability of a neon-charged cryogenic loop heat pipe

International Nuclear Information System (INIS)

Guo, Yuandong; Lin, Guiping; He, Jiang; Bai, Lizhan; Zhang, Hongxing; Miao, Jianyin

2017-01-01

Highlights: • A neon-charged CLHP integrated with a G-M cryocooler was designed and investigated. • The CLHP can realize the supercritical startup with an auxiliary heat load of 1.5 W. • Maximum heat transport capability of the CLHP was 4.5 W over a distance of 0.6 m. • There existed an optimum auxiliary heat load to expedite the supercritical startup. • There existed an optimum charged pressure to reach the largest heat transfer limit. - Abstract: Neon-charged cryogenic loop heat pipe (CLHP) can realize efficient cryogenic heat transport in the temperature range of 30–40 K, and promises great application potential in the thermal control of future space infrared exploration system. In this work, extensive experimental studies on the supercritical startup and heat transport capability of a neon-charged CLHP integrated with a G-M cryocooler were carried out, where the effects of the auxiliary heat load applied to the secondary evaporator and charged pressure of the working fluid were investigated. Experimental results showed that the CLHP could successfully realize the supercritical startup with an auxiliary heat load of 1.5 W, and there existed an optimum auxiliary heat load and charged pressure of the working fluid respectively, to achieve the maximum temperature drop rate of the primary evaporator during the supercritical startup. The CLHP could reach a maximum heat transport capability of 4.5 W over a distance of 0.6 m corresponding to the optimum charged pressure of the working fluid; however, the heat transport capability decreased with the increase of the auxiliary heat load. Furthermore, the inherent mechanisms responsible for the phenomena observed in the experiments were analyzed and discussed, to provide a better understanding from the theoretical view.

SOLUBILITY OF ORGANIC BIOCIDES IN SUPERCRITICAL CO2 AND CO2+ COSOLVENT MIXTURES

Science.gov (United States)

Solubilities of four organic biocides in supercritical carbon dioxide (Sc-CO2) were measured using a dynamic flowr apparatus over a pressure range of 10 to 30 MPa and temperature of 35-80 degrees C. The biocides studied were: Amical-48 (diiodomethyl p-tolyl sulfone), chlorothalo...

European supercritical water cooled reactor (HPLWR Phase 2 project)

International Nuclear Information System (INIS)

Schulenberg, Thomas; Starflinger, Joerg; Marsault, Philippe; Bittermann, Dietmar; Maraczy, Czaba; Laurien, Eckart; Lycklama, Jan Aiso; Anglart, Henryk; Andreani, Michele; Ruzickova, Mariana; Heikinheimo, Liisa

2010-01-01

The High Performance Light Water Reactor (HPLWR), how the European Supercritical Water Cooled Reactor is called, is a pressure vessel type reactor operated with supercritical water at 25 MPa feedwater pressure and 500 deg C maximum core outlet temperature. It is designed and analyzed by a European consortium of 13 partners from 8 Euratom member states in the second phase of the HPLWR project. Most emphasis has been laid on a core with a thermal neutron spectrum, consisting of small, housed fuel assemblies with 40 fuel pins each and a central water box to improve the neutron moderation despite the low coolant density. Peak cladding temperatures of the fuel rods have been minimized by heating up the coolant in three steps with intermediate coolant mixing. The innovative core design with upward and downward flow through its assemblies has been studied with neutronic, thermal-hydraulic and stress analyses and has been reviewed carefully in a mid-term assessment. The containment design with its safety and residual heat removal systems is based on the latest boiling water reactor concept, but with different passive high pressure coolant injection systems to cause a forced convection through the core. The design concept of the steam cycle is indicating the envisaged efficiency increase to around 44%. Moreover, it provides the constraints to design the components of the balance of the plant. The project is accompanied by numerical studies of heat transfer of supercritical water in fuel assemblies and by material tests of candidate cladding alloys, performed by the consortium and supported by additional tests of the Joint Research Centre of the European Commission. An overview of results achieved up to now, given in this paper, is illustrating the latest scientific and technological advances. (author)

Corrosion in Supercritical carbon Dioxide: Materials, Environmental Purity, Surface Treatments, and Flow Issues

Energy Technology Data Exchange (ETDEWEB)

Sridharan, Kumar; Anderson, Mark

2013-12-10

The supercritical CO{sub 2} Brayton cycle is gaining importance for power conversion in the Generation IV fast reactor system because of its high conversion efficiencies. When used in conjunction with a sodium fast reactor, the supercritical CO{sub 2} cycle offers additional safety advantages by eliminating potential sodium-water interactions that may occur in a steam cycle. In power conversion systems for Generation IV fast reactors, supercritical CO{sub 2} temperatures could be in the range of 30°C to 650°C, depending on the specific component in the system. Materials corrosion primarily at high temperatures will be an important issue. Therefore, the corrosion performance limits for materials at various temperatures must be established. The proposed research will have four objectives centered on addressing corrosion issues in a high-temperature supercritical CO{sub 2} environment: Task 1: Evaluation of corrosion performance of candidate alloys in high-purity supercritical CO{sub 2}: The following alloys will be tested: Ferritic-martensitic Steels NF616 and HCM12A, austenitic alloys Incoloy 800H and 347 stainless steel, and two advanced concept alloys, AFA (alumina forming austenitic) steel and MA754. Supercritical CO{sub 2} testing will be performed at 450°C, 550°C, and 650°C at a pressure of 20 MPa, in a test facility that is already in place at the proposing university. High purity CO{sub 2} (99.9998%) will be used for these tests. Task 2: Investigation of the effects of CO, H{sub 2}O, and O{sub 2} impurities in supercritical CO{sub 2} on corrosion: Impurities that will inevitably present in the CO{sub 2} will play a critical role in dictating the extent of corrosion and corrosion mechanisms. These effects must be understood to identify the level of CO{sub 2} chemistry control needed to maintain sufficient levels of purity to manage corrosion. The individual effects of important impurities CO, H{sub 2}O, and O{sub 2} will be investigated by adding them

Experimental investigation of heat transfer for supercritical pressure water flowing in vertical annular channels

International Nuclear Information System (INIS)

Gang Wu; Bi Qincheng; Yang Zhendong; Wang Han; Zhu Xiaojing; Hao Hou; Leung, L.K.H.

2011-01-01

Highlights: → Two annular test sections were constructed with annular gaps of 4 and 6 mm. → Two heat transfer regions have been observed: normal and deteriorated heat transfer. → The spacer enhances the heat transfer at downstream locations. → The Jackson correlation agrees quite closely with the experimental data. - Abstract: An experiment has recently been completed at Xi'an Jiaotong University (XJTU) to obtain wall-temperature measurements at supercritical pressures with upward flow of water inside vertical annuli. Two annular test sections were constructed with annular gaps of 4 and 6 mm, respectively, and an internal heater of 8 mm outer diameter. Experimental-parameter ranges covered pressures of 23-28 MPa, mass fluxes of 350-1000 kg/m 2 /s, heat fluxes of 200-1000 kW/m 2 , and bulk inlet temperatures up to 400 deg. C. Depending on the flow conditions and heat fluxes, two distinctive heat transfer regimes, referring to as the normal heat transfer and deteriorated heat transfer, have been observed. At similar flow conditions, the heat transfer coefficients for the 6 mm gap annular channel are larger than those for the 4 mm gap annular channel. A strong effect of spiral spacer on heat transfer has been observed with a drastic reduction in wall temperature at locations downstream of the device in the annuli. Two tube-data-based correlations have been assessed against the experimental heat transfer results. The Jackson correlation agrees with the experimental trends and overpredicts slightly the heat transfer coefficients. The Dittus-Boelter correlation is applicable only for the normal heat transfer region but not for the deteriorated heat transfer region.

Muonium kinetics in sub- and supercritical water

Energy Technology Data Exchange (ETDEWEB)

Ghandi, K.; Addison-Jones, B.; Brodovitch, J.C.; Kecman, S.; McKenzie, I.; Percival, P.W

2003-02-01

Muonium is long-lived in pure water and has been studied over a very wide range of temperatures and pressures, from 5 deg. C to over 400 deg. C and from 1 to 400 bar. We have determined rate constants for representative reactions of muonium in aqueous solution; equivalent data on H atom kinetics is sparse and stops well short of the maximum temperature and pressure attained in our experiments. The results show remarkable deviations from the predictions of standard reaction theories. In particular, rate constants pass through a maximum with temperature well below the critical point. This seems to be a general phenomenon, since we have observed it for spin-exchange and chemical reactions that are diffusion limited at low temperatures, as well as for activated reactions. We believe that a key factor in the drop of rate constants at high temperature is the cage effect, in particular the number of collisions between a pair of reactants over the duration of their encounter. Whatever the reason, the implications are profound for both the efficiency of supercritical water oxidation reactors and for the modelling of radiation chemistry in pressurized water nuclear reactors.

Muonium kinetics in sub- and supercritical water

International Nuclear Information System (INIS)

Ghandi, K.; Addison-Jones, B.; Brodovitch, J.C.; Kecman, S.; McKenzie, I.; Percival, P.W.

2003-01-01

Muonium is long-lived in pure water and has been studied over a very wide range of temperatures and pressures, from 5 deg. C to over 400 deg. C and from 1 to 400 bar. We have determined rate constants for representative reactions of muonium in aqueous solution; equivalent data on H atom kinetics is sparse and stops well short of the maximum temperature and pressure attained in our experiments. The results show remarkable deviations from the predictions of standard reaction theories. In particular, rate constants pass through a maximum with temperature well below the critical point. This seems to be a general phenomenon, since we have observed it for spin-exchange and chemical reactions that are diffusion limited at low temperatures, as well as for activated reactions. We believe that a key factor in the drop of rate constants at high temperature is the cage effect, in particular the number of collisions between a pair of reactants over the duration of their encounter. Whatever the reason, the implications are profound for both the efficiency of supercritical water oxidation reactors and for the modelling of radiation chemistry in pressurized water nuclear reactors

Sensitivity analysis of CFD code FLUENT-12 for supercritical water in vertical bare tubes

Energy Technology Data Exchange (ETDEWEB)

Farah, A.; Haines, P.; Harvel, G.; Pioro, I., E-mail: amjad.farah@yahoo.com, E-mail: patrickjhaines@gmail.com, E-mail: glenn.harvel@uoit.ca, E-mail: igor.pioro@uoit.ca [Univ. of Ontario Inst. of Technology, Faculty of Energy Systems and Nuclear Science,Oshawa, Ontario (Canada)

2012-07-01

The ability to use FLUENT 12 or other CFD software to accurately model supercritical water flow through various geometries in diabatic conditions is integral to research involving coal-fired power plants as well as Supercritical Water-cooled Reactors (SCWR). The cost and risk associated with constructing supercritical water test loops are far too great to use in a university setting. Previous work has shown that FLUENT 12, specifically realizable k-ε model, can reasonably predict the bulk and wall temperature distributions of externally heated vertical bare tubes for cases with relatively low heat and mass fluxes. However, sizeable errors were observed for other cases, often those which involved large heat fluxes that produce deteriorated heat transfer (DHT) regimes. The goal of this research is to gain a more complete understanding of how FLUENT 12 models supercritical water cases and where errors can be expected to occur. One control case is selected where expected changes in bulk and wall temperatures occur and they match empirical correlations' predictions, and the operating parameters are varied individually to gauge their effect on FLUENT's solution. The model used is the realizable k-ε, and the parameters altered are inlet pressure, mass flux, heat flux, and inlet temperature. (author)

Performance Estimation of Supercritical Co2 Micro Modular Reactor (MMR) for Varying Cooling Air Temperature

International Nuclear Information System (INIS)

Ahn, Yoonhan; Kim, Seong Gu; Cho, Seong Kuk; Lee, Jeong Ik

2015-01-01

A Small Modular Reactor (SMR) receives interests for the various application such as electricity co-generation, small-scale power generation, seawater desalination, district heating and propulsion. As a part of SMR development, supercritical CO2 Micro Modular Reactor (MMR) of 36.2MWth in power is under development by the KAIST research team. To enhance the mobility, the entire system including the power conversion system is designed for the full modularization. Based on the preliminary design, the thermal efficiency is 31.5% when CO2 is sufficiently cooled to the design temperature. A supercritical CO2 MMR is designed to supply electricity to the remote regions. The ambient temperature of the area can influence the compressor inlet temperature as the reactor is cooled with the atmospheric air. To estimate the S-CO2 cycle performance for various environmental conditions, A quasi-static analysis code is developed. For the off design performance of S-CO2 turbomachineries, the experimental result of Sandia National Lab (SNL) is utilized

Effect of Stabilization on Morphology Polystyrene and Supercritical Carbon Dioxide Thermoplastic Foams

Directory of Open Access Journals (Sweden)

Mozafar Mokhtari Motameni Shirvan

2016-01-01

Full Text Available Microcellular thermoplastic foams can be usually produced in a one-step batch system using a physical foaming agent which is dissolved in a polymer system under specific pressure and temperature, higher than the critical condition of solvent and the glass transition temperature of polymer and solvent mixture. By application of a sudden pressure drop the foam structure is formed through stages of nucleation, growth and coalescence. After pressure drop, if the foam temperature is reduced below the glass transition of the gas-polymer mixture, the cells stop growing which results in a foam with stabilized morphology. This stabilization stage has not been thoroughly focused in previous studies. In this work, polystyrene as a polymer system and supercritical carbon dioxide as a solvent were used at 18.5 MPa pressure and different temperatures. The stabilization process took place within milliseconds and helped to a better understanding of cellular structure in thermoplastic foams. In this mechanism, the nucleation takes place in the phase transition of solvent molecules at supercritical state to the gas state and the formation of very small nuclei containing gas molecules between polymer chains. The energy originated from the nuclei growth is in competition with the elastic energy of polymer chains, and the predominance of one type of energy over another determines the final cell size. The results showed that the effect of stabilization process on the structure of the foam depended on the foaming temperature. Stabilization at 110°C resulted in a 50% cell size reduction and a 60% cell density promotion, while at lower temperatures, the stabilization led to greater cell size and reduced cell density.

PULSE RADIOLYSIS IN SUPERCRITICAL RARE GAS FLUIDS

International Nuclear Information System (INIS)

HOLROYD, R.

2007-01-01

Recently, supercritical fluids have become quite popular in chemical and semiconductor industries for applications in chemical synthesis, extraction, separation processes, and surface cleaning. These applications are based on: the high dissolving power due to density build-up around solute molecules, and the ability to tune the conditions of a supercritical fluid, such as density and temperature, that are most suitable for a particular reaction. The rare gases also possess these properties and have the added advantage of being supercritical at room temperature. Information about the density buildup around both charged and neutral species can be obtained from fundamental studies of volume changes in the reactions of charged species in supercritical fluids. Volume changes are much larger in supercritical fluids than in ordinary solvents because of their higher compressibility. Hopefully basic studies, such as discussed here, of the behavior of charged species in supercritical gases will provide information useful for the utilization of these solvents in industrial applications

Supercritical fluid extraction of silicone oil from uranate microspheres prepared by sol-gel process

International Nuclear Information System (INIS)

Kumar, R.; Venkatakrishnan, R.; Sivaraman, N.; Srinivasan, T.G.; Vasudeva Rao, P.R.

2005-01-01

Supercritical fluid extraction of silicone oil from urania microspheres prepared through sol-gel route was investigated. The influence of pressure, temperature, and flow rate on the extraction efficiency was studied. Experimental conditions were optimised for the complete removal of silicone oil from urania microspheres. (author)

Supercritical fluid reverse micelle separation

Science.gov (United States)

Fulton, J.L.; Smith, R.D.

1993-11-30

A method of separating solute material from a polar fluid in a first polar fluid phase is provided. The method comprises combining a polar fluid, a second fluid that is a gas at standard temperature and pressure and has a critical density, and a surfactant. The solute material is dissolved in the polar fluid to define the first polar fluid phase. The combined polar and second fluids, surfactant, and solute material dissolved in the polar fluid is maintained under near critical or supercritical temperature and pressure conditions such that the density of the second fluid exceeds the critical density thereof. In this way, a reverse micelle system defining a reverse micelle solvent is formed which comprises a continuous phase in the second fluid and a plurality of reverse micelles dispersed in the continuous phase. The solute material is dissolved in the polar fluid and is in chemical equilibrium with the reverse micelles. The first polar fluid phase and the continuous phase are immiscible. The reverse micelles each comprise a dynamic aggregate of surfactant molecules surrounding a core of the polar fluid. The reverse micelle solvent has a polar fluid-to-surfactant molar ratio W, which can vary over a range having a maximum ratio W[sub o] that determines the maximum size of the reverse micelles. The maximum ratio W[sub o] of the reverse micelle solvent is then varied, and the solute material from the first polar fluid phase is transported into the reverse micelles in the continuous phase at an extraction efficiency determined by the critical or supercritical conditions. 27 figures.

Field-emitting Townsend regime of surface dielectric barrier discharges emerging at high pressure up to supercritical conditions

International Nuclear Information System (INIS)

Pai, David Z; Stauss, Sven; Terashima, Kazuo

2015-01-01

Surface dielectric barrier discharges (DBDs) in CO 2 from atmospheric pressure up to supercritical conditions generated using 10 kHz ac excitation are investigated experimentally. Using current–voltage and charge–voltage measurements, imaging, optical emission spectroscopy, and spontaneous Raman spectroscopy, we identify and characterize a field-emitting Townsend discharge regime that emerges above 0.7 MPa. An electrical model enables the calculation of the discharge-induced capacitances of the plasma and the dielectric, as well as the space-averaged values of the surface potential and the potential drop across the discharge. The space-averaged Laplacian field is accounted for in the circuit model by including the capacitance due to the fringe electric field from the electrode edge. The electrical characteristics are demonstrated to fit the description of atmospheric-pressure Townsend DBDs (Naudé et al 2005 J. Phys. D: Appl. Phys. 38 530–8), i.e. self-sustained DBDs with minimal space-charge effects. The purely continuum emission spectrum is due to electron–neutral bremsstrahlung corresponding to an average electron temperature of 2600 K. Raman spectra of CO 2 near the critical point demonstrate that the average gas temperature increases by less than 1 K. (paper)

Supercritical fluid chromatography in drug analysis: a literature survey.

Science.gov (United States)

Salvador, A; Jaime, M A; Becerra, G; Guardia, M de L

1996-08-01

The applications of supercritical fluid chromatography to the analysis of drugs have been carefully revised from the literature compiled in the Analytical Abstracts until March 1994. Easy-to-read tables provide useful information about the state-of-the-art and possibilities offered by SFC in pharmaceutical analysis. The tables comprise extensive data about samples analyzed, pharmaceutical principles determined, solvents used and sample quantity injected, supercritical fluids and modifiers employed, injection system, instrumentation, experimental conditions for chromatographic separations (density, pressure, flow, temperature), characteristics of columns employed (type, support, length, diameter, particle film thickness, stationary phase), detectors, type of restrictors, and also some analytical features of the methods developed (such as retention time, resolution, sensitivity, limit of detection and relative standard deviation).

Assessment of hydrogen bonding effect on ionization of water from ambient to supercritical region–MD simulation approach

International Nuclear Information System (INIS)

Swiatla-Wojcik, D.; Mozumder, A.

2014-01-01

We present a novel, molecular dynamics (MD) simulation based, strategy to analyze how the degree of hydrogen bonding may influence the ionization and dissociation of water upon heating from ambient to supercritical temperatures. Calculations show a negligible change in the ionization energy up to 200 °C. At higher temperatures the ionization energy increases due to the decreasing degree of hydrogen bonding. The influence of density (pressure) is pronounced in the supercritical region. The ionization is more energy consuming in the less dense fluid. We also show that high temperature and low density may promote dissociation of the electronically excited water molecules. Implications on the initial radiation chemical yields of the hydrated electron, hydrogen atom and hydroxyl radical are discussed. - Highlights: • Up to 200 °C changes in the vertical and adiabatic ionization potentials are negligible. • At higher temperatures ionization is more energy consuming. • Ionization potential increases with decreasing density of supercritical water. • High temperature and low density promote dissociation of the excited molecules

Supercritical Regeneration of an Activated Carbon Fiber Exhausted with Phenol

Directory of Open Access Journals (Sweden)

M. Jesus Sanchez-Montero

2018-01-01

Full Text Available The properties of supercritical CO2 (SCCO2 and supercritical water (SCW turn them into fluids with a great ability to remove organic adsorbates retained on solids. These properties were used herein to regenerate an activated carbon fiber (ACF saturated with a pollutant usually contained in wastewater and drinking water, phenol. Severe regeneration conditions, up to 225 bar and 400 °C, had to be employed in SCCO2 regeneration to break the strong interaction established between phenol and the ACF. Under suitable conditions (regeneration temperature, time, and pressure, and flow of SCCO2 the adsorption capacity of the exhausted ACF was completely recovered, and even slightly increased. Most of the retained phenol was removed by thermal desorption, but the extra percentage removed by extraction allowed SCCO2 regeneration to be significantly more efficient than the classical thermal regeneration methods. SCCO2 regeneration and SCW regeneration were also compared for the first time. The use of SCW slightly improved regeneration, although SCW pressure was thrice SCCO2 pressure. The pathways that controlled SCW regeneration were also investigated.

Supercritical water oxidation of dioxins and furans in waste incinerator fly ash, sewage sludge and industrial soil.

Science.gov (United States)

Zainal, Safari; Onwudili, Jude A; Williams, Paul T

2014-08-01

Three environmental samples containing dioxins and furans have been oxidized in the presence of hydrogen peroxide under supercritical water oxidation conditions. The samples consisted of a waste incinerator fly ash, sewage sludge and contaminated industrial soil. The reactor system was a batch, autoclave reactor operated at temperatures between 350 degrees C and 450degrees C, corresponding to pressures of approximately 20-33.5 MPa and with hydrogen peroxide concentrations from 0.0 to 11.25 vol%. Hydrogen peroxide concentration and temperature/pressure had a strong positive effect on the oxidation of dioxins and furans. At the highest temperatures and pressure of supercritical water oxidation of 4500C and 33.5 MPa and with 11.25 vol% of hydrogen peroxide, the destruction efficiencies of the individual polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDD/PCDF) isomers were between 90% and 99%. There did not appear to be any significant differences in the PCDD/PCDF destruction efficiencies in relation to the different sample matrices of the waste incinerator fly ash, sewage sludge and contaminated industrial soil.

Optimization of supercritical fluid extraction and HPLC identification of wedelolactone from Wedelia calendulacea by orthogonal array design

Directory of Open Access Journals (Sweden)

Ajit A. Patil

2014-11-01

Full Text Available The purpose of this work is to provide a complete study of the influence of operational parameters of the supercritical carbon dioxide assisted extraction (SC CO2E on yield of wedelolactone from Wedelia calendulacea Less., and to find an optimal combination of factors that maximize the wedelolactone yield. In order to determine the optimal combination of the four factors viz. operating pressure, temperature, modifier concentration and extraction time, a Taguchi experimental design approach was used: four variables (three levels in L9 orthogonal array. Wedelolactone content was determined using validated HPLC methodology. Optimum extraction conditions were found to be as follows: extraction pressure, 25 MPa; temperature, 40 °C; modifier concentration, 10% and extraction time, 90 min. Optimum extraction conditions demonstrated wedelolactone yield of 8.01 ± 0.34 mg/100 g W. calendulacea Less. Pressure, temperature and time showed significant (p < 0.05 effect on the wedelolactone yield. The supercritical carbon dioxide extraction showed higher selectivity than the conventional Soxhlet assisted extraction method.

Enhanced metal recovery through oxidation in liquid and/or supercritical carbon dioxide

KAUST Repository

Blanco, Mario

2017-08-24

Process for enhanced metal recovery from, for example, metal-containing feedstock using liquid and/or supercritical fluid carbon dioxide and a source of oxidation. The oxidation agent can be free of complexing agent. The metal-containing feedstock can be a mineral such as a refractory mineral. The mineral can be an ore with high sulfide content or an ore rich in carbonaceous material. Waste can also be used as the metal-containing feedstock. The metal-containing feedstock can be used which is not subjected to ultrafine grinding. Relatively low temperatures and pressures can be used. The metal-containing feedstock can be fed into the reactor at a temperature below the critical temperature of the carbon dioxide, and an exotherm from the oxidation reaction can provide the supercritical temperature. The oxidant can be added to the reactor at a rate to maintain isothermal conditions in the reactor. Minimal amounts of water can be used as an extractive medium.

A Technique for Dynamic Corrosion Testing in Supercritical CO2

International Nuclear Information System (INIS)

Loewen, Eric P.; Davis, Cliff B.; Shropshire, David E.; Weaver, Kevan

2004-01-01

An experimental apparatus for the investigation of the flow-assisted corrosion of potential fuel cladding and structural materials to be used on a fast reactor cooled by supercritical carbon dioxide has been designed. This experimental project is part of a larger research at the Department of Energy being lead by the Idaho National Engineering and Environmental Laboratory (INEEL) to investigate the suitability of supercritical carbon dioxide for cooling a fast reactor designed to produce low-cost electricity as well as for actinide burning. The INEEL once-through corrosion apparatus consists of two syringe pumps, a pre-heat furnace, a 1.3 meter long heated corrosion test section, and a gas measuring system. The gas flow rates, heat input, and operating pressure can be adjusted so that a controlled coolant flow rate, temperature, and oxygen potential are created within each of six test sections. The corrosion cell will test tubing that is commercially available in the U.S. and specialty coupons to temperatures up to 600 deg. C and a pressure of 20 MPa. The ATHENA computer code was used to estimate the fluid conditions in each of the six test sections during normal operation. (authors)

Adsorption of ethyl acetate onto modified clays and its regeneration with supercritical CO2

Directory of Open Access Journals (Sweden)

A. M. Cavalcante

2005-03-01

Full Text Available Modified clays were used to remove ethyl acetate from aqueous solutions. These clays were regenerated using supercritical CO2. Structural changes in the montmorillonite clay after treatment with quaternary amines were studied. The surface properties of the modified clay changed from highly hydrophilic to highly organophilic. The clay was regenerated by percolation of a stream of CO2 through the porous montmorillonite matrix. Different pressures and temperatures were employed, resulting in different fluid conditions (gas, liquid, and supercritical. The experimental data was fitted with a simplified model. The best desorption result was found under supercritical conditions. A crossover effect was observed. The capacity of the modified clay as a pollutant attenuator remained almost unchanged after a regeneration cycle.

Supercritical fluid extraction of uranium from tissue paper matrix using organic extractants

International Nuclear Information System (INIS)

Kanekar, A.S.; Bhattacharyya, A.; Pathak, P.N.; Mohapatra, P.K.; Manchanda, V.K.

2009-01-01

Direct extraction of dried uranyl nitrate from tissue paper matrix was carried out using supercritical carbon dioxide modified with methanol solutions of extractants such as tri-n-butyl phosphate (TBP) and di-n-hexyl octanamide (DHOA)). The effects of temperature, pressure, extractant and nitric acid concentration on the extraction of uranyl ion were investigated. (author)

The use of supercritical fluid extraction as a sample preparation technique for soils

International Nuclear Information System (INIS)

Levy, J.M.; Dolata, L.A.; Rosselli, A.C.; Ravey, R.M.

1994-01-01

Using off-line supercritical fluid extraction (SFE), polynuclear aromatic hydrocarbons (PAHs) were extracted at different levels from various soil and sediment matrices. Based upon GC/MS measurements a number of SFE operational parameters including pressure, temperature and flow rate, were optimized to yield the highest efficiencies with the best precision

Experimental research on heat transfer performance of supercritical water in vertical tube

International Nuclear Information System (INIS)

Wang Fei; Yang Jue; Li Hongbo; Lu Donghua; Gu Hanyang; Zhao Meng

2013-01-01

Experimental research under supercritical pressure conditions was carried out on heat transfer performance in vertical tube of φ10 mm with a wide range of experimental parameters. The impacts of heat flux, mass flow rate and pressure on wall temperature and heat transfer coefficient were investigated. The experimental parameters are following: The pressures are 23, 25, 26 MPa, the mass flow rate range is 450 1200 kg/(m 2 ·s), and the heat flux range is 200-1200 kW/m 2 . Experimental results indicate that the wall temperature gradually increases with the bulk temperature, and heat transfer enhancement exists near the critical temperature as the drastic changes in physical properties. The increase in heat flux and the decrease in mass flow rate reduce heat transfer enhancement and lead to deterioration of heat transfer. The main effects of pressure are reflected in the difference of heat flux and bulk temperature of the start point where heat transfer deterioration and enhancement occur. (authors)

Heat Transfer Phenomena in Supercritical Water Nuclear Reactors

International Nuclear Information System (INIS)

Mark H. Anderson; MichaelL. Corradini; Riccardo Bonazza; Jeremy R. Licht

2007-01-01

A supercritical water heat transfer facility has been built at the University of Wisconsin to study heat transfer in a circular and square annular flow channel. A series of integral heat transfer measurements has been carried out over a wide range of heat flux, mass velocity and bulk water temperatures at a pressure of 25 MPa. The circular annular test section geometry is a 1.07 cm diameter heater rod within a 4.29 diameter flow channel

Heat Transfer Phenomena in Supercritical Water Nuclear Reactors

Energy Technology Data Exchange (ETDEWEB)

Mark H. Anderson; MichaelL. Corradini; Riccardo Bonazza; Jeremy R. Licht

2007-10-03

A supercritical water heat transfer facility has been built at the University of Wisconsin to study heat transfer in ancircular and square annular flow channel. A series of integral heat transfer measurements has been carried out over a wide range of heat flux, mas velocity and bulk water temperatures at a pressure of 25 MPa. The circular annular test section geometry is a 1.07 cm diameter heater rod within a 4.29 diameter flow channel.

CO{sub 2}-based supercritical fluids as environmentally-friendly processing solvents

Energy Technology Data Exchange (ETDEWEB)

Rubin, J.B.; Davenhall, L.B.; Taylor, C.M.V.; Pierce, T. [Los Alamos National Lab., NM (United States). Physical Organic Chemistry Group; Tiefert, K. [Hewlett-Packard Co., Inc., Santa Clara, CA (United States)

1999-03-01

The production of integrated circuits involves a number of discrete steps that utilize hazardous or regulated solvents. Environmental, safety and health considerations associated with these chemicals have prompted a search for alternative, more environmentally benign, solvent systems. An emerging technology for conventional solvent replacement is the use of supercritical fluids based on carbon dioxide (CO{sub 2}). Supercritical CO{sub 2} (SCCO{sub 2}) is an excellent choice for IC manufacturing processes since it is non-toxic, non-flammable, inexpensive, and is compatible with all substrate and metallizations systems. Also, conditions of temperature and pressure needed to achieve the supercritical state are easily achievable with existing process equipment. The authors first describe the general properties of supercritical fluids, with particular emphasis on their application as alternative solvents. Next, they review some of the work which has been published involving the use of supercritical fluids, and particularly CO{sub 2}, as they may be applied to the various steps of IC manufacture, including wafer cleaning, thin film deposition, etching, photoresist stripping, and waste treatment. Next, they describe the research work conducted at Los Alamos, on behalf of Hewlett-Packard, on the use of SCCO{sub 2} in a specific step of the IC manufacturing process: the stripping of hard-baked photoresist.

Supercritical CO2 extraction of oil and omega-3 concentrate from Sacha inchi (Plukenetia volubilis L. from Antioquia, Colombia

Directory of Open Access Journals (Sweden)

D. M. Triana-Maldonado

2017-03-01

Full Text Available Sacha inchi (Plukenetia volubilis L. seeds were employed for oil extraction with supercritical CO2 at laboratory scale. The supercritical extraction was carried out at a temperature of 60 °C, pressure range of 400–500 bars and CO2 flow of 40–80 g/min. The maximum recovery was 58% in 180 min, favored by increasing the residence time of CO2 in the extraction tank. Subsequently, the process was evaluated at pilot scale reaching a maximum recovery of 60% in 105 min, with a temperature of 60 °C, pressure of 450 bars and CO2 flow of 1270 g/min. The fatty acid composition of the oil was not affected for an extraction period of 30–120 min. The Sacha inchi oil was fractionated with supercritical CO2 to obtain an omega-3 concentrate oil without finding a considerable increase in the proportion of this compound, due to the narrow range in the carbon number of fatty acids present in the oil (16–18 carbons, making it difficult for selective separation.

Supercritical CO2 extraction of oil and omega-3 concentrate from Sacha inchi (Plukenetia volubilis L.) from Antioquia, Colombia

International Nuclear Information System (INIS)

Torijano-Gutiérrez, S.A.; Triana-Maldonadoa, D.M.; Giraldo-Estradaa, C.

2017-01-01

Sacha inchi (Plukenetia volubilis L.) seeds were employed for oil extraction with supercritical CO2 at laboratory scale. The supercritical extraction was carried out at a temperature of 60 °C, pressure range of 400–500 bars and CO2 flow of 40–80 g/min. The maximum recovery was 58% in 180 min, favored by increasing the residence time of CO2 in the extraction tank. Subsequently, the process was evaluated at pilot scale reaching a maximum recovery of 60% in 105 min, with a temperature of 60 °C, pressure of 450 bars and CO2 flow of 1270 g/min. The fatty acid composition of the oil was not affected for an extraction period of 30–120 min. The Sacha inchi oil was fractionated with supercritical CO2 to obtain an omega-3 concentrate oil without finding a considerable increase in the proportion of this compound, due to the narrow range in the carbon number of fatty acids present in the oil (16–18 carbons), making it difficult for selective separation. [es

Research activities on supercritical fluid science in food biotechnology.

Science.gov (United States)

Khosravi-Darani, Kianoush

2010-06-01

This article serves as an overview, introducing the currently popular area of supercritical fluids and their uses in food biotechnology. Within each application, and wherever possible, the basic principles of the technique, as well as a description of the history, instrumentation, methodology, uses, problems encountered, and advantages over the traditional, non-supercritical methods are given. Most current commercial application of the supercritical extraction involve biologically-produced materials; the technique may be particularly relevant to the extraction of biological compounds in cases where there is a requirement for low-temperature processing, high mass-transfer rates, and negligible carrying over of the solvent into the final product. Special applications to food processing include the decaffeination of green coffee beans, the production of hops extracts, the recovery of aromas and flavors from herbs and spices, the extraction and fractionation of edible oils, and the removal of contaminants, among others. New advances, in which the extraction is combined with reaction or crystallization steps, may further increase the attractiveness of supercritical fluids in the bioprocess industries. To develop and establish a novel and effective alternative to heating treatment, the lethal action of high hydrostatic pressure CO(2) on microorganisms, with none or only a minimal heating process, has recently received a great deal of attention.

Reactions of nitrate salts with ammonia in supercritical water

International Nuclear Information System (INIS)

Dell'Orco, P.C.; Gloyna, E.F.; Buelow, S.J.

1997-01-01

Reactions involving nitrate salts and ammonia were investigated in supercritical water at temperatures from 450 to 530 C and pressures near 300 bar. Reaction products included nitrite, nitrogen gas, and nitrous oxide. Observed reaction rates and product distributions provided evidence for a free-radical reaction mechanism with NO 2 , NO, and NH 2 · as the primary reactive species at supercritical conditions. In the proposed elementary mechanism, the rate-limiting reaction step was determined to be the hydrolysis of MNO 3 species, which resulted in the formation of nitric acid and subsequently NO 2 . A simple second-order reaction model was used to represent the data. In developing an empirical kinetic model, nitrate and nitrate were lumped as an NO x - reactant. Empirical kinetic parameters were developed for four MNO x /NH 3 reacting systems, assuming first orders in both NH 3 and NO x - . Observed MNO x /NH 3 reaction rates and mechanisms suggest immediately a practical significance of these reactions for nitrogen control strategies in supercritical water oxidation processes

Swelling kinetics and impregnation of PLA with thymol under supercritical CO2 conditions

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Milovanović Stoja L.

2016-01-01

Full Text Available The present work was aimed to study swelling kinetics of polylactic acid (PLA and its impregnation with thymol in supercritical carbon dioxide (scCO2 medium. The influences of temperature and soaking time on the swelling kinetics and impregnation yield of PLA cylindrical disc and film were investigated. Swelling experiments were performed in a high pressure view cell at 10 MPa and temperatures of 40°C, 60°C and 75°C for 2 to 24 h. On the basis of swelling kinetics, pressure of 10 MPa and temperature of 40°C were chosen for supercritical solvent impregnation (SSI of the PLA samples during 2 to24 h. The highest swelling extent was observed for the PLA monolith after 24 h treatment with pure scCO2 (7.5% and scCO2 with thymol (118.3%. It was shown that sufficiently high amount of thymol can be loaded into both PLA monolith and film using SSI after only 2 h (10.0% and 6.6%, respectively. Monolith and film of PLA impregnated with thymol could be suitable for active food packaging and sterile medical disposables.

Lipase-catalyzed transesterification of soybean oil and phytosterol in supercritical CO2.

Science.gov (United States)

Hu, Lizhi; Llibin, Sun; Li, Jun; Qi, Liangjun; Zhang, Xu; Yu, Dianyu; Walid, Elfalleh; Jiang, Lianzhou

2015-12-01

The transesterification of phytosterol and soybean oil was performed using Novozym 435 in supercritical carbon dioxide (SC-CO2). The transesterification reaction was conducted in soybean oil containing 5-25% phytosterol at 55-95 °C and free-water solvent. The effects of temperature, reaction time, phytosterol concentration, lipase dosage and reaction pressure on the conversion rate of transesterification were investigated. The optimal reaction conditions were the reaction temperature (85 °C), reaction time (1 h), phytosterol concentration (5%), reaction pressure (8 Mpa) and lipase dosage (1%). The highest conversion rate of 92% could be achieved under the optimum conditions. Compared with the method of lipase-catalyzed transesterification of phytosterol and soybean oil at normal pressure, the transesterification in SC-CO2 reduced significantly the reaction temperature and reaction time.

Supercritical fluid extraction of positron-emitting radioisotopes from solid target matrices

International Nuclear Information System (INIS)

Schlyer, D.

2000-01-01

Supercritical fluids are attractive as media for both chemical reactions, as well as process extraction, since their physical properties can be manipulated by small changes in pressure and temperature near the critical point of the fluid. Such changes can result in drastic effects on density-dependent properties such as solubility, refractive index, dielectric constant, viscosity and diffusivity of the fluid. This suggests that pressure tuning of a pure supercritical fluid may be a useful means to manipulate chemical reactions on the basis of a thermodynamic solvent effect. It also means that the solvation properties of the fluid can be precisely controlled to enable selective component extraction from a matrix. In recent years there has been a growing interest in applying supercritical fluid extraction to the selective removal of trace metals from solid samples. Much of the work has been done on simple systems comprised of inert matrices such as silica or cellulose. Recently, this process as been expanded to environmental samples as well. However, very little is understood about the exact mechanism of the extraction process. Of course, the widespread application of this technology is highly dependent on the ability of scientists to model and predict accurate phase equilibria in complex systems. In this project, we plan to explore the feasibility of utilizing supercritical fluids as solvents for reaction and extraction of radioisotopes produced from solid enriched targets. The reason for this work is that many of these enriched target materials used for radioisotope production are expensive

Comparative analysis of single-step and two-step biodiesel production using supercritical methanol on laboratory-scale

International Nuclear Information System (INIS)

Micic, Radoslav D.; Tomić, Milan D.; Kiss, Ferenc E.; Martinovic, Ferenc L.; Simikić, Mirko Ð.; Molnar, Tibor T.

2016-01-01

Highlights: • Single-step supercritical transesterification compared to the two-step process. • Two-step process: oil hydrolysis and subsequent supercritical methyl esterification. • Experiments were conducted in a laboratory-scale batch reactor. • Higher biodiesel yields in two-step process at milder reaction conditions. • Two-step process has potential to be cost-competitive with the single-step process. - Abstract: Single-step supercritical transesterification and two-step biodiesel production process consisting of oil hydrolysis and subsequent supercritical methyl esterification were studied and compared. For this purpose, comparative experiments were conducted in a laboratory-scale batch reactor and optimal reaction conditions (temperature, pressure, molar ratio and time) were determined. Results indicate that in comparison to a single-step transesterification, methyl esterification (second step of the two-step process) produces higher biodiesel yields (95 wt% vs. 91 wt%) at lower temperatures (270 °C vs. 350 °C), pressures (8 MPa vs. 12 MPa) and methanol to oil molar ratios (1:20 vs. 1:42). This can be explained by the fact that the reaction system consisting of free fatty acid (FFA) and methanol achieves supercritical condition at milder reaction conditions. Furthermore, the dissolved FFA increases the acidity of supercritical methanol and acts as an acid catalyst that increases the reaction rate. There is a direct correlation between FFA content of the product obtained in hydrolysis and biodiesel yields in methyl esterification. Therefore, the reaction parameters of hydrolysis were optimized to yield the highest FFA content at 12 MPa, 250 °C and 1:20 oil to water molar ratio. Results of direct material and energy costs comparison suggest that the process based on the two-step reaction has the potential to be cost-competitive with the process based on single-step supercritical transesterification. Higher biodiesel yields, similar or lower energy

Thermal–hydraulic calculation and analysis of a 600 MW supercritical circulating fluidized bed boiler with annular furnace

International Nuclear Information System (INIS)

Wang, Long; Yang, Dong; Shen, Zhi; Mao, Kaiyuan; Long, Jun

2016-01-01

Highlights: • Non-linear model of supercritical CFB boiler with annular furnace is developed. • Many empirical correlations are used to solve the model. • The thermal–hydraulic characteristics of boiler are analyzed. • The results show that the design of the annular furnace is reasonable. - Abstract: The development of supercritical Circulating Fluidized Bed (CFB) boiler has great economic and environmental value. An entirely new annular furnace structure with outer and inner ring sidewalls for supercritical CFB boiler has been put forward by Institute of Engineering Thermophysics (IET), Chinese Academy of Sciences and Dongfang Boiler Group Co., Ltd. (DBC). Its outer and inner ring furnace structure makes more water walls arranged and reduces furnace height availably. In addition, compared with other additional evaporating heating surface structures such as mid-partition and water-cooled panels, the integrative structure can effectively avoid the bed-inventory overturn and improve the penetrability of secondary air. The conditions of the 600 MW supercritical CFB boiler including capability, pressure and mass flux are harsh. In order to insure the safety of boiler operation, it is very necessary to analyze the thermal–hydraulic characteristics of water-wall system. The water-wall system with complicated pipe arrangement is regarded as a network consisting of series-parallel circuits, pressure nodes and linking circuits, which represent vertical water-wall tubes, different headers and linking tubes, respectively. Based on the mass, momentum and energy conservation, a mathematical model is built, which consists of some simultaneous nonlinear equations. The mass flux in circuits, pressure drop between headers, outer vapor temperature of water-wall system and metal temperature data of tubes at the boiler maximum continuous rating (BMCR), 75% BMCR and 30% BMCR loads are obtained by solving the mathematical model. The results show that the vertical water

Numerical simulation of stress distribution in Inconel 718 components realized by metal injection molding during supercritical debinding

Science.gov (United States)

Agne, Aboubakry; Barrière, Thierry

2018-05-01

Metal injection molding (MIM) is a process combining advantages of thermoplastic injection molding and powder metallurgy process in order to manufacture components with complex and near net-shape geometries. The debinding of a green component can be performed in two steps, first by using solvent debinding in order to extract the organic part of the binder and then by thermal degradation of the rest of the binder. A shorter and innovative method for extracting an organic binder involves the use of supercritical fluid instead of a regular solvent. The debinding via a supercritical fluid was recently investigated to extract organic binders contained in components obtained by Metal Injection Molding. It consists to put the component in an enclosure subjected to high pressure and temperature. The supercritical fluid has various properties depending on these two conditions, e.g., density and viscosity. The high-pressure combined with the high temperature during the process affect the component structure. Three mechanisms contributing to the deformation of the component can been differentiated: thermal expansion, binder extraction and supercritical fluid effect on the outer surfaces of the component. If one supposes that, the deformation due to binder extraction is negligible, thermal expansion and the fluid effect are probably the main mechanisms that can produce several stress. A finite-element model, which couples fluid-structures interaction and structural mechanics, has been developed and performed on the Comsol Multiphysics® finite-element software platform allowed to estimate the stress distribution during the supercritical debinding of MIM component composed of Inconel 718 powders, polypropylene, polyethylene glycol and stearic acid as binder. The proposed numerical simulations allow the estimation of the stress distribution with respect to the processing parameters for MIM components during the supercritical debinding process using a stationary solver.

Corrosion behavior of porous chromium carbide in supercritical water

International Nuclear Information System (INIS)

Dong Ziqiang; Chen Weixing; Zheng Wenyue; Guzonas, Dave

2012-01-01

Highlights: ► Corrosion behavior of porous Cr 3 C 2 in various SCW conditions was investigated. ► Cr 3 C 2 is stable in SCW at temperature below 420–430 °C. ► Cracks and disintegration were observed at elevated testing temperatures. ► Degradation of Cr 3 C 2 is related to the intermediate product CrOOH. - Abstract: The corrosion behavior of highly porous chromium carbide (Cr 3 C 2 ) prepared by a reactive sintering process was characterized at temperatures ranging from 375 °C to 625 °C in a supercritical water environment with a pressure of 25–30 MPa. The test results show that porous chromium carbide is stable in SCW environments at temperatures under 425 °C, above which disintegration occurred. The porous carbide was also tested under hydrothermal conditions of pressures between 12 MPa and 50 MPa at constant temperatures of 400 °C and 415 °C, respectively. The pressure showed little effect on the stability of chromium carbide in the tests at those temperatures. The mechanism of disintegration of chromium carbide in SCW environments is discussed.

Heat Transfer to Supercritical Water in Gaseous State or Affected by Mixed Convection in Vertical Tubes

International Nuclear Information System (INIS)

Pis'menny, E.N.; Razumovskiy, V.G.; Maevskiy, E.M.; Koloskov, A.E.; Pioro, I.L.

2006-01-01

The results on heat transfer to supercritical water heated above the pseudo-critical temperature or affected by mixed convection flowing upward and downward in vertical tubes of 6.28-mm and 9.50-mm inside diameter are presented. Supercritical water heat-transfer data were obtained at a pressure of 23.5 MPa, mass flux within the range from 250 to 2200 kg/(m 2 s), inlet temperature from 100 to 415 deg. C and heat flux up to 3.2 MW/m 2 . Temperature regimes of the tubes cooled with supercritical water in a gaseous state (i.e., supercritical water at temperatures beyond the pseudo-critical temperature) were stable and easily reproducible within a wide range of mass and heat fluxes. An analysis of the heat-transfer data for upward and downward flows enabled to determine a range of Gr/Re 2 values corresponding to the maximum effect of free convection on the heat transfer. It was shown that: 1) the heat transfer coefficient at the downward flow of water can be higher by about 50% compared to that of the upward flow; and 2) the deteriorated heat-transfer regime is affected with the flow direction, i.e., at the same operating conditions, the deteriorated heat transfer may be delayed at the downward flow compared to that at the upward flow. These heat-transfer data are applicable as the reference dataset for future comparison with bundle data. (authors)

Estimation of Oxidation Kinetics and Oxide Scale Void Position of Ferritic-Martensitic Steels in Supercritical Water

Directory of Open Access Journals (Sweden)

Li Sun

2017-01-01

Full Text Available Exfoliation of oxide scales from high-temperature heating surfaces of power boilers threatened the safety of supercritical power generating units. According to available space model, the oxidation kinetics of two ferritic-martensitic steels are developed to predict in supercritical water at 400°C, 500°C, and 600°C. The iron diffusion coefficients in magnetite and Fe-Cr spinel are extrapolated from studies of Backhaus and Töpfer. According to Fe-Cr-O ternary phase diagram, oxygen partial pressure at the steel/Fe-Cr spinel oxide interface is determined. The oxygen partial pressure at the magnetite/supercritical water interface meets the equivalent oxygen partial pressure when system equilibrium has been attained. The relative error between calculated values and experimental values is analyzed and the reasons of error are suggested. The research results show that the results of simulation at 600°C are approximately close to experimental results. The iron diffusion coefficient is discontinuous in the duplex scale of two ferritic-martensitic steels. The simulation results of thicknesses of the oxide scale on tubes (T91 of final superheater of a 600 MW supercritical boiler are compared with field measurement data and calculation results by Adrian’s method. The calculated void positions of oxide scales are in good agreement with a cross-sectional SEM image of the oxide layers.

Transonic steady- and unsteady-pressure measurements on a high-aspect-ratio supercritical-wing model with oscillating control surfaces

Science.gov (United States)

Sandford, M. C.; Ricketts, R. H.; Cazier, F. W., Jr.

1980-01-01

A supercritical wing with an aspect ratio of 10.76 and with two trailing-edge oscillating control surfaces is described. The semispan wing is instrumented with 252 static orifices and 164 in situ dynamic-pressure gages for studying the effects of control-surface position and motion on steady- and unsteady-pressures at transonic speeds. Results from initial tests conducted in the Langley Transonic Dynamics Tunnel at two Reynolds numbers are presented in tabular form.

Degradation Characteristics of Wood Using Supercritical Alcohols

Directory of Open Access Journals (Sweden)

Jeeban Poudel

2012-11-01

Full Text Available In this work, the characteristics of wood degradation using supercritical alcohols have been studied. Supercritical ethanol and supercritical methanol were used as solvents. The kinetics of wood degradation were analyzed using the nonisothermal weight loss technique with heating rates of 3.1, 9.8, and 14.5 °C/min for ethanol and 5.2, 11.3, and 16.3 °C/min for methanol. Three different kinetic analysis methods were implemented to obtain the apparent activation energy and the overall reaction order for wood degradation using supercritical alcohols. These were used to compare with previous data for supercritical methanol. From this work, the activation energies of wood degradation in supercritical ethanol were obtained as 78.0–86.0, 40.1–48.1, and 114 kJ/mol for the different kinetic analysis methods used in this work. The activation energies of wood degradation in supercritical ethanol were obtained as 78.0–86.0, 40.1–48.1, and 114 kJ/mol. This paper also includes the analysis of the liquid products obtained from this work. The characteristic analysis of liquid products on increasing reaction temperature and time has been performed by GC-MS. The liquid products were categorized according to carbon numbers and aromatic/aliphatic components. It was found that higher conversion in supercritical ethanol occurs at a lower temperature than that of supercritical methanol. The product analysis shows that the majority of products fall in the 2 to 15 carbon number range.

Supercritical Extraction Process of Allspice Essential Oil

Directory of Open Access Journals (Sweden)

Yasvet Y. Andrade-Avila

2017-01-01

Full Text Available Allspice essential oil was extracted with supercritical carbon dioxide (SC-CO2 in a static process at three different temperatures (308.15, 313.15, and 318.15 K and four levels of pressure (100, 200, 300, and 360 bar. The amount of oil extracted was measured at intervals of 1, 2, 3, 4, 5, and 6 h; the most extraction yield reached was of 68.47% at 318.15 K, 360 bar, and 6 h of contact time. In this supercritical extraction process, the distribution coefficient (KD, the mean effective diffusion coefficient (Def, the energy of activation (Ea, the thermodynamic properties (ΔG0, ΔH0, and ΔS0, and the apparent solubility (S expressed as mass fraction (w/w were evaluated for the first time. At the equilibrium the experimental apparent solubility data were successfully correlated with the modified Chrastil equation.

Corrosion testing of NiCrAl(Y) coating alloys in high-temperature and supercritical water

International Nuclear Information System (INIS)

Biljan, S.; Huang, X.; Qian, Y.; Guzonas, D.

2011-01-01

With the development of Generation IV (Gen IV) nuclear power reactors, materials capable of operating in high-temperature and supercritical water environment are essential. This study focuses on the corrosion behavior of five alloys with compositions of Ni20Cr, Ni5Al, Ni50Cr, Ni20Cr5Al and Ni20Cr10AlY above and below the critical point of water. Corrosion tests were conducted at three different pressures, while the temperature was maintained at 460 o C, in order to examine the effects of water density on the corrosion. From the preliminary test results, it was found that the binary alloys Ni20Cr and Ni50Cr showed weight loss above the critical point (23.7 MPa and 460 o C). The higher Cr content alloy Ni50Cr suffered more weight loss than Ni-20Cr under the same conditions. Accelerated weight gain was observed above the critical point for the binary alloy Ni5Al. The combination of Cr, Al and Y in Ni20Cr10AlY provides stable scale formation under all testing conditions employed in this study. (author)

Pourbaix diagrams for the iron–water system extended to high-subcritical and low-supercritical conditions

International Nuclear Information System (INIS)

Cook, William G.; Olive, Robert P.

2012-01-01

Highlights: ► Pourbaix diagrams for iron–water are extended to low-supercritical temperatures. ► Thermodynamic properties for use in R-HKF model re-evaluated. ► Above the critical point, magnetite solubility is between 10 −11 and 10 −10 mol/kg. - Abstract: The supercritical water-cooled reactor (SCWR) is a Generation IV reactor concept that will operate at temperatures and pressures above water’s thermodynamic critical point. Pourbaix diagrams for the iron–water system at temperatures slightly below and above the critical point at 25 MPa have been constructed to aid the evaluation and development of potential construction materials. High temperature data extrapolation was performed using a revised Helgeson–Kirkham–Flowers model and fit to data on magnetite and hematite solubility in high-temperature water. A low-concentration diagram at 350 °C reveals the importance of water chemistry control to avoid transitioning to an active corrosion region.

A comparative study of solvent and supercritical Co2 extraction of Simarouba gluaca seed oil

International Nuclear Information System (INIS)

Anjaneyulu, B.; Satyannarayana, S.; Kanjilal, S.; Siddaiah, V.; Prasanna Rani, K.N.

2017-01-01

In the present study, the supercritical carbon dioxide (Co2) extraction of oil from Simarouba gluaca seeds was carried out at varying conditions of pressure (300–500 bar), temperature (50–70 °C) and CO2 flow rate (10–30 g·min-1). The extraction condition for maximum oil yield was obtained at 500 bar pressure, 70 °C and at 30 g·min-1 flow rate of CO2. The extracted oil was analyzed thoroughly for physico-chemical properties and compared with those of conventional solvent extracted oil. An interesting observation is a significant reduction in the phosphorus content of the oil (8.4 mg·kg-1) extracted using supercritical CO2 compared to the phosphorous content of the solvent extracted oil (97 mg·kg-1). Moreover, the content of total tocopherols in supercritically extracted oil (135.6 mg·kg-1) was found to be higher than the solvent extracted oil (111 mg·kg-1). The rest of the physico-chemical properties of the two differently extracted oils matched well with each other. The results indicated the possible benefits of supercritical CO2 extraction over solvent extraction of Simarouba gluaca seed oil. [es

A comparative study of solvent and supercritical CO2 extraction of Simarouba gluaca seed oil

Directory of Open Access Journals (Sweden)

B. Anjaneyulu

2017-09-01

Full Text Available In the present study, the supercritical carbon dioxide (CO2 extraction of oil from Simarouba gluaca seeds was carried out at varying conditions of pressure (300–500 bar, temperature (50–70 °C and CO2 flow rate (10–30 g·min-1. The extraction condition for maximum oil yield was obtained at 500 bar pressure, 70 °C and at 30 g·min-1 flow rate of CO2. The extracted oil was analyzed thoroughly for physico-chemical properties and compared with those of conventional solvent extracted oil. An interesting observation is a significant reduction in the phosphorus content of the oil (8.4 mg·kg-1 extracted using supercritical CO2 compared to the phosphorous content of the solvent extracted oil (97 mg·kg-1. Moreover, the content of total tocopherols in supercritically extracted oil (135.6 mg·kg-1 was found to be higher than the solvent extracted oil (111 mg·kg-1. The rest of the physico-chemical properties of the two differently extracted oils matched well with each other. The results indicated the possible benefits of supercritical CO2 extraction over solvent extraction of Simarouba gluaca seed oil.

Extraction of Genistein from Sophora flavescens with Supercritical Carbon Dioxide

Energy Technology Data Exchange (ETDEWEB)

Han, Chang-Nam; Kang, Choon-Hyoung [Chonnam National University, Gwangju (Korea, Republic of)

2015-08-15

This study was directed to finding an optimum extraction condition of genistein from the S. flavescens with supercritical carbon dioxide as a solvent. In this effort, effects of the extraction conditions including pressure, temperature and a co-solvent on the extraction efficiency were investigated. The aqueous ethanol and methanol solutions were used as co-solvents while the tested operating pressure and temperature ranges were from 200 bar to 300 bar and from 308.15 K to 323.15 K, respectively. The concentration of genistein was determined by means of HPLC equipped with a UV detector. From the results, it was observed that an increase in pressure led to the higher extraction efficiency. Further, methanol showed better performance as a co-solvent than ethanol. The DPPH radical scavenging activities were measured to compare antioxidant activities of S. flavescens extracts.

Development of Nuclear Decontamination Technology Using Supercritical Fluid

Energy Technology Data Exchange (ETDEWEB)

Jung, Wonyoung; Park, Kwangheon; Park, Jihye; Lee, Donghee [Kyunghee Univ., Yongin (Korea, Republic of)

2014-05-15

Soil cleaning technologies that have been developed thus far increase treatment costs in contaminated soil recovery processes because they generate large amounts of secondary wastes. In this respect, this study is intended to develop soil decontamination methods using CO{sub 2}, which is a nontoxic, environmentally friendly substance, in order to fundamentally suppress the generation of secondary wastes from the decontamination process and to create high added values. In this study, to develop decontamination methods for uranium-contaminated soil using supercritical CO{sub 2}, a soil decontamination system using supercritical CO{sub 2} was constructed. In addition, the basic principle of supercritical CO{sub 2} decontamination using a TBP-HNO3 complex was explained. According to the results of the study, sea-sand samples having the same degree of contamination showed different results of decontamination according to the quantities of the TBP-HNO3 complex used as an extraction agent, which resulted in high extraction rates. Thus far, a most widely used method of extracting uranium has been the dissolving of uranium in acids. However, this method has the large adverse effect of generating strong acidic wastes that cannot be easily treated. On the other hand, supercritical CO{sub 2} requires critical conditions that are no more difficult to meet than those of other supercritical fluids, since its density can be changed from a very low state close to that of an ideal gas to a high state close to that of liquids. The critical gas conditions are a pressure of 71 bar and a temperature of 31 .deg. C, both of which are inexpensive to achieve. Moreover, CO{sub 2} is a solvent that is not harmful to the human body and few effects on environmental pollution. Therefore, nontoxic and environment friendly processes can be developed using supercritical CO{sub 2}. Supercritical CO{sub 2}'s advantages over prevailing methods suggest its potential for developing innovative

Development of Nuclear Decontamination Technology Using Supercritical Fluid

International Nuclear Information System (INIS)

Jung, Wonyoung; Park, Kwangheon; Park, Jihye; Lee, Donghee

2014-01-01

Soil cleaning technologies that have been developed thus far increase treatment costs in contaminated soil recovery processes because they generate large amounts of secondary wastes. In this respect, this study is intended to develop soil decontamination methods using CO 2 , which is a nontoxic, environmentally friendly substance, in order to fundamentally suppress the generation of secondary wastes from the decontamination process and to create high added values. In this study, to develop decontamination methods for uranium-contaminated soil using supercritical CO 2 , a soil decontamination system using supercritical CO 2 was constructed. In addition, the basic principle of supercritical CO 2 decontamination using a TBP-HNO3 complex was explained. According to the results of the study, sea-sand samples having the same degree of contamination showed different results of decontamination according to the quantities of the TBP-HNO3 complex used as an extraction agent, which resulted in high extraction rates. Thus far, a most widely used method of extracting uranium has been the dissolving of uranium in acids. However, this method has the large adverse effect of generating strong acidic wastes that cannot be easily treated. On the other hand, supercritical CO 2 requires critical conditions that are no more difficult to meet than those of other supercritical fluids, since its density can be changed from a very low state close to that of an ideal gas to a high state close to that of liquids. The critical gas conditions are a pressure of 71 bar and a temperature of 31 .deg. C, both of which are inexpensive to achieve. Moreover, CO 2 is a solvent that is not harmful to the human body and few effects on environmental pollution. Therefore, nontoxic and environment friendly processes can be developed using supercritical CO 2 . Supercritical CO 2 's advantages over prevailing methods suggest its potential for developing innovative decontamination methods, as demonstrated

Subsonic and transonic pressure measurements on a high-aspect-ratio supercritical-wing model with oscillating control surfaces

Science.gov (United States)

Sandford, M. C.; Ricketts, R. H.; Watson, J. J.

1981-01-01

A high aspect ratio supercritical wing with oscillating control surfaces is described. The semispan wing model was instrumented with 252 static orifices and 164 in situ dynamic pressure gases for studying the effects of control surface position and sinusoidal motion on steady and unsteady pressures. Data from the present test (this is the second in a series of tests on this model) were obtained in the Langley Transonic Dynamics Tunnel at Mach numbers of 0.60 and 0.78 and are presented in tabular form.

Flow Distribution Measurement Feasibility in Supercritical CO₂

Energy Technology Data Exchange (ETDEWEB)

Lance, Blake [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-12-01

Supercritical CO₂ (sCO₂) is a fluid of interest for advanced power cycles that can reach thermal to electric energy conversion efficiencies of 50% or higher. Of particular interest for fossil-fired natural gas is the Allam cycle that captures nearly all CO₂ emissions and exports it as a fluid stream where it may be of value. The combustion process conditions are unlike any before realized with 90-95% CO₂ concentration, temperatures around 1000°C, and pressures near 300 bar. This work outlines the experimental feasibility of flow measurements to acquire the first known data in pure sCO₂ at similar but reduced temperature and pressure conditions.

Low Temperature Synthesis of Metal Oxides by a Supercritical Seed Enhanced Crystallization (SSEC) Process

DEFF Research Database (Denmark)

Jensen, Henrik; Brummerstedt Iversen, Steen; Joensen, Karsten Dan

2006-01-01

A novel method for producing crystalline nanosized metal oxides by a Supercritical Seed Enhanced Crystallization (SSEC) Process has been developed. The process is a modified sol-gel process taking place at temperatures as low as 95 ºC with supercritical CO2 as solvent and polypropylene as seeding...... material. The nanocrystalline product is obtained without having to resort to costly post-reaction processing and the product is obtained directly after the SSEC process. TiO2 powders produced by the SSEC process were shown to have a crystallinity of 60 % and a crystal size of 7.3 ± 2.6 nm....... The crystallinity can be controlled by changing the heating rate of the initial formation of the nanoparticles and the morphology can be altered by changing the process time....

Study of high-pressure adsorption from supercritical fluids by the potential theory

DEFF Research Database (Denmark)

Monsalvo, Matias Alfonso; Shapiro, Alexander

2009-01-01

The multicomponent potential theory of adsorption (MPTA), which has been previously used to study low-pressure adsorption of subcritical fluids, is extended to adsorption equilibria from supercritical fluids up to high pressures. The MPTA describes an adsorbed phase as an inhomogeneous fluid...... the adsorbed and the gas phases. We have also evaluated the performance of the classical Soave-Redlich-Kwong (SRK) EoS. The fluid-solid interactions are described by simple Dubinin-Radushkevich-Astakhov (DRA) potentials. In addition, we test the performance of the 10-4-3 Steele potential. It is shown...... that application of sPC-SAFT slightly improves the performance of the MPTA and that in spite of its simplicity, the DRA model can be considered as an accurate potential, especially, for mixture adsorption. We show that, for the sets of experimental data considered in this work, the MPTA is capable of predicting...

Supercritical water corrosion of high Cr steels and Ni-base alloys

International Nuclear Information System (INIS)

Jang, Jin Sung; Han, Chang Hee; Hwang, Seong Sik

2004-01-01

High Cr steels (9 to 12% Cr) have been widely used for high temperature high pressure components in fossil power plants. Recently the concept of SCWR (supercritical water-cooled reactor) has aroused a keen interest as one of the next generation (Generation IV) reactors. Consequently Ni-base (or high Ni) alloys as well as high Cr steels that have already many experiences in the field are among the potential candidate alloys for the cladding or reactor internals. Tentative inlet and outlet temperatures of the anticipated SCWR are 280 and 510 .deg. C respectively. Among many candidate alloys there are austenitic stainless steels, Ni base alloys, ODS alloys as well as high Cr steels. In this study the corrosion behavior of the high Cr steels and Ni base (or high Ni) alloys in the supercritical water were investigated. The corrosion behavior of the unirradiated base metals could be used in the near future as a guideline for the out-of-pile or in-pile corrosion evaluation tests

Supercritical fluid extraction for the determination of optimum oil recovery conditions

Energy Technology Data Exchange (ETDEWEB)

Al-Marzouqi, Ali H.; Zekri, Abdulrazag Y.; Jobe, Baboucarr; Dowaidar, Ali [Chemical and Petroleum Engineering Department, U.A.E. University, P.O. Box: 17555, Al-Ain (United Arab Emirates)

2007-01-15

CO{sub 2} under supercritical (SC) conditions is a powerful solvent capable of extracting hydrocarbons from crude oil. The extraction capacity of CO{sub 2} is a function of pressure, temperature and composition of the crude oil. This paper presents the results of a laboratory study investigating the capacity of CO{sub 2} to extract hydrocarbons from an oil-saturated soil under a wide range of pressures and temperatures (80-120 bar for temperatures ranging from 40 to 60 C and 200-300 bar for temperatures varying from 100 to 140 C). The soil samples were collected from Sahel oil filed, which is near Bu Hasa oil field (Abu Dhabi, UAE) where the crude oil was obtained from. The extracted oil from the SC CO{sub 2} process and the residual oil remaining in the soil sample were analyzed by gas chromatography to shed more light on the extraction phenomenon. Extraction efficiency of CO{sub 2} increased with pressure and decreased with temperature. Moreover, the amount of extracted heavy fractions increased with pressure for all temperatures. On the other hand, the amount of extracted heavy hydrocarbons decreased with temperature for the low pressure range (80-120 bar) and remained the same for the pressure range of 250-300 bar. The maximum extraction efficiency of CO{sub 2} was 72.4%, which was obtained at the highest pressure (300 bar) and a temperature of 100 C. (author)

Supercritical heat transfer correlation for carbon dioxide flowing upward in a vertical tube

International Nuclear Information System (INIS)

Mokry, S. J.; Pioro, I. L.; Farah, A.; King, K.

2010-01-01

The objective of the current study was to analyze heat-transfer at supercritical conditions using carbon dioxide as a modeling fluid, and to develop a heat-transfer correlation based on data published in open literature. Supercritical (SC) fluids have unique properties. Beyond the critical point (22.1 MPa and 374.1 deg.C for water and 7.38 MPa and 31.0 deg.C for carbon dioxide), the fluid resembles a dense gas. The transition from single-phase liquid to single-phase gas does not involve a distinct phase change under these conditions. Phenomena such as dryout (or critical heat flux) are therefore not relevant. However, at supercritical conditions, deteriorated heat-transfer regime, (i.e., lower Heat Transfer Coefficient (HTC) values, compared to those for the normal or regular heat-transfer regime) may exist. Experiments with Supercritical Water (SCW) are very expensive due to high critical parameters. Therefore, a number of experiments are performed in modeling fluids such as carbon dioxide or/and refrigerants. However, there is no common opinion if SC modeling fluids' correlations can be applied to SCW and vice versa. Thus, the objective of this work was to generalize SC carbon dioxide data with a new correlation, and also, to compare these data with SCW correlations The experimental data was analyzed, and a new correlation was developed as part of a larger project assessing the feasibility of Generation IV SCW reactor concepts. Results are given for supercritical heat-transfer for several combinations of wall and bulk-fluid temperatures that were below, at or above the pseudo critical temperature. Uncertainties of all primary parameters were estimated. Two modes of heat transfer at supercritical pressures have been identified: (I) Normal Heat Transfer (NHT), and (2) Deteriorated Heat Transfer (DHT) characterized by lower-than-expected HTCs (i.e., higher-than-expected wall temperatures) than in the normal heat-transfer regime. These heat-transfer data are

CFD study on the supercritical carbon dioxide cooled pebble bed reactor

Energy Technology Data Exchange (ETDEWEB)

Yu, Dali, E-mail: ydlmitd@outlook.com; Peng, Minjun; Wang, Zhongyi

2015-01-15

Highlights: • An innovation concept of supercritical carbon dioxide cooled pebble bed reactor is proposed. • Body-centered cuboid (BCCa) arrangement is adopted for the pebbles. • S-CO{sub 2} would be a good candidate coolant for using in pebble bed reactor. - Abstract: The thermal hydraulic study of using supercritical carbon dioxide (S-CO{sub 2}), a superior fluid state brayton cycle medium, in pebble bed type nuclear reactor is assessed through computational fluid dynamics (CFD) methodology. Preliminary concept design of this S-CO{sub 2} cooled pebble bed reactor (PBR) is implemented by the well-known KTA heat transfer correlation and Ergun pressure drop equation. Eddy viscosity transport turbulence model is adopted and verified by KTA calculated results. Distributions of the temperature, velocity, pressure and Nusselt (Nu) number of the coolant near the surface of the middle spherical fuel element are obtained and analyzed. The conclusion of the assessment is that S-CO{sub 2} would be a good candidate coolant for using in pebble bed reactor due primarily to its good heat transfer characteristic and large mass density, which could lead to achieve lower pressure drop and higher power density.

Ultralow temperature helium compressor for Japan Atomic Energy Research Institute

International Nuclear Information System (INIS)

Asakura, Hiroshi

1988-01-01

Ishikawajima Harima Heavy Industries Co., Ltd. started the development of an ultralow temperature helium compressor for helium liquefaction in 1984 jointly with Japan Atomic Energy Research Institute, and has delivered the first practical machine to the Superconductive Magnet Laboratory of JAERI. For a large superconductive magnet to be used in the stable state for a fusion reactor, conventional superconductive materials (NbTi, NbTi 3 Sn, etc.) must be used, being cooled forcibly with supercritical helium. The supercritical helium which is compressed above the critical pressure of 228 kPa has a stable cooling effect since the thermal conductivity does not change due to the evaporation of liquid helium. In order to maintain the temperature of the supercritical helium below 4 K before it enters a magnet, a heat exchanger is used. The compressor that IHI has developed has the ability to reduce the vapor pressure of liquid helium from atmospheric pressure to 50.7 kPa, and can attain the temperature of 3.5 K. The specification of this single stage centrifugal compressor is: mass flow rate 25 - 64 g/s, speed 80,000 rpm, adiabatic efficiency 62 - 69 %. The structure and the performance are reported. (K.I.)

Supercritical Water Oxidation Program (SCWOP)

International Nuclear Information System (INIS)

1994-02-01

Purpose of SCWOP is to develop and demonstrate supercritical water oxidation as a viable technology for treating DOE hazardous and mixed wastes and to coordinate SCWO research, development, demonstration, testing, and evaluation activities. The process involves bringing together organic waste, water, and an oxidant (air, O 2 , etc.) to temperatures and pressures above water's critical point (374 C, 22.1 MPa); organic destruction is >99.99% efficient, and the resulting effluents (mostly water, CO 2 ) are relatively benign. Pilot-scale (300--500 gallons/day) SCWO units are to be constructed and demonstrated. Two phases will be conducted: hazardous waste pilot plant demonstration and mixed waste pilot demonstration. Contacts for further information and for getting involved are given

Artificial Neural Network Approach to Predict Biodiesel Production in Supercritical tert-Butyl Methyl Ether

Directory of Open Access Journals (Sweden)

Obie Farobie

2016-05-01

Full Text Available In this study, for the first time artificial neural network was used to predict biodiesel yield in supercritical tert-butyl methyl ether (MTBE. The experimental data of biodiesel yield conducted by varying four input factors (i.e. temperature, pressure, oil-to-MTBE molar ratio, and reaction time were used to elucidate artificial neural network model in order to predict biodiesel yield. The main goal of this study was to assess how accurately this artificial neural network model to predict biodiesel yield conducted under supercritical MTBE condition. The result shows that artificial neural network is a powerful tool for modeling and predicting biodiesel yield conducted under supercritical MTBE condition that was proven by a high value of coefficient of determination (R of 0.9969, 0.9899, and 0.9658 for training, validation, and testing, respectively. Using this approach, the highest biodiesel yield was determined of 0.93 mol/mol (corresponding to the actual biodiesel yield of 0.94 mol/mol that was achieved at 400 °C, under the reactor pressure of 10 MPa, oil-to-MTBE molar ratio of 1:40 within 15 min of reaction time.

On the gasification of wet biomass in supercritical water : over de vergassing van natte biomassa in superkritiek water

NARCIS (Netherlands)

Withag, J.A.M.

2013-01-01

Supercritical water gasification (SCWG) is a challenging thermo-chemical conversion route for wet biomass and waste streams into hydrogen and/or methane. At temperatures and pressures above the critical point the physical properties of water differ strongly from liquid water or steam. Because of the

Reaction kinetics of cellulose hydrolysis in subcritical and supercritical water

Science.gov (United States)

Olanrewaju, Kazeem Bode

The uncertainties in the continuous supply of fossil fuels from the crisis-ridden oil-rich region of the world is fast shifting focus on the need to utilize cellulosic biomass and develop more efficient technologies for its conversion to fuels and chemicals. One such technology is the rapid degradation of cellulose in supercritical water without the need for an enzyme or inorganic catalyst such as acid. This project focused on the study of reaction kinetics of cellulose hydrolysis in subcritical and supercritical water. Cellulose reactions at hydrothermal conditions can proceed via the homogeneous route involving dissolution and hydrolysis or the heterogeneous path of surface hydrolysis. The work is divided into three main parts. First, the detailed kinetic analysis of cellulose reactions in micro- and tubular reactors was conducted. Reaction kinetics models were applied, and kinetics parameters at both subcritical and supercritical conditions were evaluated. The second major task was the evaluation of yields of water soluble hydrolysates obtained from the hydrolysis of cellulose and starch in hydrothermal reactors. Lastly, changes in molecular weight distribution due to hydrothermolytic degradation of cellulose were investigated. These changes were also simulated based on different modes of scission, and the pattern generated from simulation was compared with the distribution pattern from experiments. For a better understanding of the reaction kinetics of cellulose in subcritical and supercritical water, a series of reactions was conducted in the microreactor. Hydrolysis of cellulose was performed at subcritical temperatures ranging from 270 to 340 °C (tau = 0.40--0.88 s). For the dissolution of cellulose, the reaction was conducted at supercritical temperatures ranging from 375 to 395 °C (tau = 0.27--0.44 s). The operating pressure for the reactions at both subcritical and supercritical conditions was 5000 psig. The results show that the rate-limiting step in

Injection of Fluids into Supercritical Environments

National Research Council Canada - National Science Library

Oschwald, M

2004-01-01

This paper summarizes and compares the results of systematic research programs at two independent laboratories regarding the injection of cryogenic liquids at subcritical and supercritical pressures...

Supercritical Carbon Dioxide Extraction of Selected Herbal Leaves: An Overview

Science.gov (United States)

Hamid, I. A. Abd; Ismail, N.; Rahman, N. Abd

2018-05-01

Supercritical fluid extraction of carbon dioxide (SC-CO2) is one of new alternative extraction method that has been widely used to isolate bioactive components from variety of plant materials. The method was proved to be clean and safe, compatible for the extraction of edible products such as spices, food additives, medicines and nutritional supplement products compared to traditional extraction techniques such as solvent extraction, hydro distillation and steam distillation. The SC-CO2 extraction was known as highly influenced by its process parameter such as temperature and pressure for obtaining maximum yield. Therefore, a clear review on the optimum range of temperature and pressure for herbal leaves extraction using SC-CO2 is necessary for future reference. The aim of this work is to analyze the effect of temperature and pressure of SC-CO2 process without modifier on extraction yield of some selected herbal leaves i.e clubmoss, drumstick leaves, kratom leaves, mallee and myrtle leaves. The values of investigated parameters were; pressure from 8.9 to 50 MPa and temperature from 35 to 80°C. The results showed that the highest extraction yields were obtained when the pressure and temperature were above 30 MPa and 40°C. The interaction between pressure and temperature for SC-CO2 extraction of plant leaves are crucial since the values cannot be very high or very low in order to preserve the quality of the extracts.

Impregnation of Ibuprofen into Polycaprolactone using supercritical carbon dioxide

International Nuclear Information System (INIS)

Yoganathan, Roshan; Mammucari, Raffaella; Foster, Neil R

2010-01-01

Polycaprolactone (PCL) is a Food and Drug Administration (FDA) approved biodegradable polyester used in tissue engineering applications. Ibuprofen is an anti-inflammatory drug which has good solubility in supercritical CO 2 (SCCO 2 ). The solubility of CO 2 in PCL allows for the impregnation of CO 2 -soluble therapeutic agents into the polymer via a supercritical fluid (SCF) process. Polymers impregnated with bio-active compounds are highly desired for medical implants and controlled drug delivery. In this study, the use of CO 2 to impregnate PCL with ibuprofen was investigated. The effect of operating conditions on the impregnation of ibuprofen into PCL was investigated over two pressure and two temperature levels, 150bar and 200bar, 35 0 C and 40 0 C, respectively. Polycaprolactone with drug-loadings as high as 27% w/w were obtained. Impregnated samples exhibited controlled drug release profiles over several days.

Control-rod, pressure and flow-induced accident and transient analysis of a direct-cycle, supercritical-pressure, light-water-cooled fast breeder reactor

International Nuclear Information System (INIS)

Kitoh, Kazuaki; Koshizuka, Seiichi; Oka, Yoshiaki

1996-01-01

The features of the direct-cycle, supercritical-pressure, light-water-cooled fast breeder reactor (SCFBR) are high thermal efficiency and simple reactor system. The safety principle is basically the same as that of an LWR since it is a water-cooled reactor. Maintaining the core flow is the basic safety requirement of the reactor, since its coolant system is the one through type. The transient behaviors at control rod, pressure and flow-induced abnormalities are analyzed and presented in this paper. The results of flow-induced transients of SCFBR were reported at ICONE-3, though pressure change was neglected. The change of fuel temperature distribution is also considered for the analysis of the rapid reactivity-induced transients such as control rod withdrawal. Total loss of flow and pump seizure are analyzed as the accidents. Loss of load, control rod withdrawal from the normal operation, loss of feedwater heating, inadvertent start of an auxiliary feedwater pump, partial loss of coolant flow and loss of external power are analyzed as the transients. The behavior of the flow-induced transients is not so much different from the analyses assuming constant pressure. Fly wheels should be equipped with the feedwater pumps to prolong the coast-down time more than 10s and to cope with the total loss of flow accident. The coolant density coefficient of the SCFBR is less than one tenth of a BWR in which the recirculation flow is used for the power control. The over pressurization transients at the loss of load is not so severe as that of a BWR. The power reaches 120%. The minimum deterioration heat flux ratio (MDHFR) and the maximum pressure are sufficiently lower than the criteria; MDHFR above 1.0 and pressure ratio below 1.10 of 27.5 MPa, maximum pressure for operation. Among the reactivity abnormalities, the control rod withdrawal transient from the normal operation is analyzed

MUFITS Code for Modeling Geological Storage of Carbon Dioxide at Sub- and Supercritical Conditions

Science.gov (United States)

Afanasyev, A.

2012-12-01

Two-phase models are widely used for simulation of CO2 storage in saline aquifers. These models support gaseous phase mainly saturated with CO2 and liquid phase mainly saturated with H2O (e.g. TOUGH2 code). The models can be applied to analysis of CO2 storage only in relatively deeply-buried reservoirs where pressure exceeds CO2 critical pressure. At these supercritical reservoir conditions only one supercritical CO2-rich phase appears in aquifer due to CO2 injection. In shallow aquifers where reservoir pressure is less than the critical pressure CO2 can split in two different liquid-like and gas-like phases (e.g. Spycher et al., 2003). Thus a region of three-phase flow of water, liquid and gaseous CO2 can appear near the CO2 injection point. Today there is no widely used and generally accepted numerical model capable of the three-phase flows with two CO2-rich phases. In this work we propose a new hydrodynamic simulator MUFITS (Multiphase Filtration Transport Simulator) for multiphase compositional modeling of CO2-H2O mixture flows in porous media at conditions of interest for carbon sequestration. The simulator is effective both for supercritical flows in a wide range of pressure and temperature and for subcritical three-phase flows of water, liquid CO2 and gaseous CO2 in shallow reservoirs. The distinctive feature of the proposed code lies in the methodology for mixture properties determination. Transport equations and Darcy correlation are solved together with calculation of the entropy maximum that is reached in thermodynamic equilibrium and determines the mixture composition. To define and solve the problem only one function - mixture thermodynamic potential - is required. The potential is determined using a three-parametric generalization of Peng-Robinson equation of state fitted to experimental data (Todheide, Takenouchi, Altunin etc.). We apply MUFITS to simple 1D and 2D test problems of CO2 injection in shallow reservoirs subjected to phase changes between

Numerical investigation of heat transfer in upward flows of supercritical water in circular tubes and tight fuel rod bundles

International Nuclear Information System (INIS)

Yang Jue; Oka, Yoshiaki; Ishiwatari, Yuki; Liu Jie; Yoo, Jaewoon

2007-01-01

Heat transfer in upward flows of supercritical water in circular tubes and in tight fuel rod bundles is numerically investigated by using the commercial CFD code STAR-CD 3.24. The objective is to have more understandings about the phenomena happening in supercritical water and for designs of supercritical water cooled reactors. Some turbulence models are selected to carry out numerical simulations and the results are compared with experimental data and other correlations to find suitable models to predict heat transfer in supercritical water. The comparisons are not only in the low bulk temperature region, but also in the high bulk temperature region. The two-layer model (Hassid and Poreh) gives a better prediction to the heat transfer than other models, and the standard k-ε high Re model with the standard wall function also shows an acceptable predicting capability. Three-dimensional simulations are carried out in sub-channels of tight square lattice and triangular lattice fuel rod bundles at supercritical pressure. Results show that there is a strong non-uniformity of the circumferential distribution of the cladding surface temperature, in the square lattice bundle with a small pitch-to-diameter ratio (P/D). However, it does not occur in the triangular lattice bundle with a small P/D. It is found that this phenomenon is caused by the large non-uniformity of the flow area in the cross-section of sub-channels. Some improved designs are numerically studied and proved to be effective to avoid the large circumferential temperature gradient at the cladding surface

Solubility of grape seed oil in supercritical CO2: Experiments and modeling

International Nuclear Information System (INIS)

Duba, Kurabachew Simon; Fiori, Luca

2016-01-01

Highlights: • Solubility of grape seed oil in SC-CO 2 for P: 20–50 MPa and T: 313–343 K. • Experimental procedure: dynamic method and oil dispersed on the surface of glass beads. • Eight density-based models and a thermodynamic model to fit the experimental data. • All the models predict the solubility of grape seed oil in SC-CO 2 to a reasonable degree. • Models by Chrastil, del Valle and Aguilera, Kumar and Johnston, and the thermodynamic model are preferable. - Abstract: The solubility of grape (Vitis vinifera L.) seed oil in supercritical CO 2 was measured in the temperature range 313–343 K and pressure range 20–50 MPa using the dynamic technique. Several data and global trends were reported. The results show that, at constant temperature, the solubility increases with the increase in pressure, while the effect of the temperature is different for low and high pressure. The experimental data were modeled by eight density-based models and a thermodynamic model based on the Peng-Robinson equation of state. By best fitting procedures, the “free parameters” of the various models were calculated: in general, all the tested models have proved to be able to predict the solubility of grape seed oil in supercritical CO 2 . Differences in model capabilities have been discussed based on the main characteristics of the various models, evidencing their distinct and common features. The predictive capability of the thermodynamic model was comparable to that of the density-based models.

Supercritical gas extracts from low-quality coals. On the search of new precursors for carbon materials

Energy Technology Data Exchange (ETDEWEB)

Garcia, Roberto; Arenillas, Ana; Rubiera, Fernando; Moinelo, Sabino R. [Instituto Nacional del Carbon INCAR, CSIC, Apartado 73, 33080, Oviedo (Spain)

2004-11-25

This paper studies the chemical composition of several supercritical gas (SCG) extracts and its influence on the thermal behaviour under carbonisation conditions. The extracts were obtained from a Spanish lignite (Mequinenza), a low-quality coal from the point of view of energy applications. The lignite was treated with toluene, ethanol (EtOH) and tetrahydrofuran (THF) as solvents under different supercritical temperature and pressure conditions. The extracts display high aliphatic nature and enhanced concentrations of oxygen functional groups, aided by the contribution of hydrogenation and oxygen incorporation reactions occurring in the SCG extraction with EtOH and THF. Thiophenic compounds are also present in great concentrations derived from the exceptionally high organic sulphur content of the parent coal. The carbonisation of the extracts renders anisotropic material with fine mosaic texture, as a consequence of the significant thermal reactivity inferred by the aliphatic and oxygenated groups. The size of the mosaic increases with the temperature of the SCG extraction and varies with the supercritical solvent in the order: toluene

Near-critical and supercritical fluid extraction of polycyclic aromatic hydrocarbons from town gas soil

International Nuclear Information System (INIS)

Kocher, B.S.; Azzam, F.O.; Cutright, T.J.; Lee, S.

1995-01-01

The contamination of soil by hazardous and toxic organic pollutants is an ever-growing problem facing the global community. One particular family of contaminants that are of major importance are polycyclic aromatic hydrocarbons (PAHs). PAHs are the result of coal gasification and high-temperature processes. Sludges from these town gas operations were generally disposed of into unlined pits and left there for eventual biodegradation. However, the high levels of PAH contained in the pits prevented the occurrence of biodegradation. PAH contaminated soil is now considered hazardous and must be cleaned to environmentally acceptable standards. One method for the remediation is extraction with supercritical water. Water in or about its critical region exhibits enhanced solvating power toward most organic compounds. Contaminated soil containing 4% by mass of hydrocarbons was ultra-cleaned in a 300-cm 3 semicontinuous system to an environmentally acceptable standard of less than 200 ppm residual hydrocarbon concentration. The effects of subcritical or supercritical extraction, solvent temperature, pressure, and density have been studied, and the discerning characteristics of this type of fluid have been identified. The efficiencies of subcritical and supercritical extraction have been discussed from a process engineering standpoint

Supercritical carbon dioxide extraction of methylxanthines from maté tea leaves

Directory of Open Access Journals (Sweden)

M.D.A. Saldaña

2000-09-01

Full Text Available Methylxanthines are alkaloids found in natural products such as tea, coffee and guaraná. These alkaloids are commonly used in cola drinks and pharmaceutical products due principally to their stimulant and diuretic effects on the human organism. In this work, experimental data on the supercritical CO2 extraction of caffeine, theophylline and theobromine from herbal maté tea, a beverage traditionally consumed by the gauchos of southern Brazil, the Argentine, Paraguay and Uruguay, were obtained using high pressure extraction equipment that allows adequate control of temperature and pressure. The continuous extraction/fractionation of maté tea leaves, Ilex paraguariensis in natura using carbon dioxide was carried out at 313.2 and 343.2 K and pressures of 13.8 and 25.5 MPa. Extraction/fractionation curves revealed the large influence of temperature and pressure on extraction yield. CO2 was also found to show a higher selectivity for caffeine than for theophylline and theobromine.

Development of artificial neural network models for supercritical fluid solvency in presence of co-solvents

Energy Technology Data Exchange (ETDEWEB)

Shokir, Eissa Mohamed El-Moghawry; El-Midany, Ayman Abdel-Hamid [Cairo University, Giza (Egypt); Al-Homadhi, Emad Souliman; Al-Mahdy, Osama [King Saud University, Riyadh (Saudi Arabia)

2014-08-15

This paper presents the application of artificial neural networks (ANN) to develop new models of liquid solvent dissolution of supercritical fluids with solutes in the presence of cosolvents. The neural network model of the liquid solvent dissolution of CO{sub 2} was built as a function of pressure, temperature, and concentrations of the solutes and cosolvents. Different experimental measurements of liquid solvent dissolution of supercritical fluids (CO{sub 2}) with solutes in the presence of cosolvents were collected. The collected data are divided into two parts. The first part was used in building the models, and the second part was used to test and validate the developed models against the Peng- Robinson equation of state. The developed ANN models showed high accuracy, within the studied variables range, in predicting the solubility of the 2-naphthol, anthracene, and aspirin in the supercritical fluid in the presence and absence of co-solvents compared to (EoS). Therefore, the developed ANN models could be considered as a good tool in predicting the solubility of tested solutes in supercritical fluid.

Oxidation stability of biodiesel fuel as prepared by supercritical methanol

Energy Technology Data Exchange (ETDEWEB)

Jiayu Xin; Hiroaki Imahara; Shiro Saka [Kyoto University, Kyoto (Japan). Department of Socio-Environmental Energy Science, Graduate School of Energy Science

2008-08-15

A non-catalytic supercritical methanol method is an attractive process to convert various oils/fats efficiently into biodiesel. To evaluate oxidation stability of biodiesel, biodiesel produced by alkali-catalyzed method was exposed to supercritical methanol at several temperatures for 30 min. As a result, it was found that the tocopherol in biodiesel is not stable at a temperature higher than 300{sup o}C. After the supercritical methanol treatment, hydroperoxides were greatly reduced for biodiesel with initially high in peroxide value, while the tocopherol slightly decreased in its content. As a result, the biodiesel prepared by the supercritical methanol method was enhanced for oxidation stability when compared with that prepared by alkali-catalyzed method from waste oil. Therefore, supercritical methanol method is useful especially for oils/fats having higher peroxide values. 32 refs., 8 figs., 3 tabs.

Stress corrosion cracking behavior of annealed and cold worked 316L stainless steel in supercritical water

Energy Technology Data Exchange (ETDEWEB)

Sáez-Maderuelo, A., E-mail: alberto.saez@ciemat.es; Gómez-Briceño, D.

2016-10-15

Highlights: • The alloy 316L is susceptible to stress corrosion cracking in supercritical water. • The susceptibility of alloy 316L increases with temperature and plastic deformation. • Dynamic strain ageing processes may be active in the material. - Abstract: The supercritical water reactor (SCWR) is one of the more promising designs considered by the Generation IV International Forum due to its high thermal efficiency and improving security. To build this reactor, standardized structural materials used in light water reactors (LWR), like austenitic stainless steels, have been proposed. These kind of materials have shown an optimum behavior to stress corrosion cracking (SCC) under LWR conditions except when they are cold worked. It is known that physicochemical properties of water change sharply with pressure and temperature inside of the supercritical region. Owing to this situation, there are several doubts about the behavior of candidate materials like austenitic stainless steel 316L to SCC in the SCWR conditions. In this work, alloy 316L was studied in deaerated SCW at two different temperatures (400 °C and 500 °C) and at 25 MPa in order to determine how changes in this variable influence the resistance of this material to SCC. The influence of plastic deformation in the behavior of alloy 316L to SCC in SCW was also studied at both temperatures. Results obtained from these tests have shown that alloy 316L is susceptible to SCC in supercritical water reactor conditions where the susceptibility of this alloy increases with temperature. Moreover, prior plastic deformation of 316L SS increased its susceptibility to environmental cracking in SCW.

Electron mobility in supercritical pentanes as a function of density and temperature

International Nuclear Information System (INIS)

Itoh, Kengo; Nakagawa, Kazumichi; Nishikawa, Masaru

1988-01-01

The excess electron mobility in supercritical n-, iso- and neopentane was measured isothermally as a function of density. The density-normalized mobility μN in all three isomers goes through a minimum at a density below the respective critical densities, and the mobility is quite temperature-dependent in this region, then goes through a minimum. The μN behavior around the minimum in n-pentane is well accounted for by the Cohen-Lekner model with the structure factor S(K) estimated from the speed of sound, while that in iso- and neopentane is not. (author)

Sub- and supercritical jet disintegration

Science.gov (United States)

DeSouza, Shaun; Segal, Corin

2017-04-01

Shadowgraph visualization and Planar Laser Induced Fluorescence (PLIF) are applied to single orifice injection in the same facility and same fluid conditions to analyze sub- to supercritical jet disintegration and mixing. The comparison includes jet disintegration and lateral spreading angle. The results indicate that the shadowgraph data are in agreement with previous visualization studies but differ from the PLIF results that provided quantitative measurement of central jet plane density and density gradients. The study further evaluated the effect of thermodynamic conditions on droplet production and quantified droplet size and distribution. The results indicate an increase in the normalized drop diameter and a decrease in the droplet population with increasing chamber temperatures. Droplet size and distribution were found to be independent of chamber pressure.

Thermodynamics of aqueous association and ionization reactions at high temperatures and pressures

International Nuclear Information System (INIS)

Mesmer, R.E.; Marshall, W.L.; Palmer, D.A.; Simonson, J.M.; Holmes, H.F.

1990-01-01

Electrochemical and electrical conductance cells have been widely used at ORNL over the years to quantitatively determine equilibrium constants and their salt effects to 300 degree C (EMF) and 800 degree C (conductance) at the saturation pressure of water (EMF) and to 4000 bars (conductance). The most precise results to 300 degree C for a large number of weak acids and bases show very similar thermodynamic behavior, which will be discussed. Results for the ionization constants of water, NH 3 (aq), HCl(aq), and NaCl(aq), which extend well into the supercritical region, have been fitted in terms of a model with dependence on density and temperature. The entropy change is found to be the driving force for ion-association reactions and this tendency increases (as it must) with increasing temperature at a given pressure. Also, the variation of all thermodynamic properties is greatly reduced at high fixed densities. Considerable variation occurs at low densities. From this analysis, the dependence of the reaction thermodynamics on the P-V-T properties of the solvent is shown, and the implication of large changes in hydration for solutes in the vicinity of the critical temperature will be discussed. Finally, the change in the molar compressibility coefficient for all reactions in water is shown to be the same and dependent only on the compressibility of the solvent

Supercritical fluid chromatography coupled with in-source atmospheric pressure ionization hydrogen/deuterium exchange mass spectrometry for compound speciation.

Science.gov (United States)

Cho, Yunju; Choi, Man-Ho; Kim, Byungjoo; Kim, Sunghwan

2016-04-29

An experimental setup for the speciation of compounds by hydrogen/deuterium exchange (HDX) with atmospheric pressure ionization while performing chromatographic separation is presented. The proposed experimental setup combines the high performance supercritical fluid chromatography (SFC) system that can be readily used as an inlet for mass spectrometry (MS) and atmospheric pressure photo ionization (APPI) or atmospheric pressure chemical ionization (APCI) HDX. This combination overcomes the limitation of an approach using conventional liquid chromatography (LC) by minimizing the amount of deuterium solvents used for separation. In the SFC separation, supercritical CO2 was used as a major component of the mobile phase, and methanol was used as a minor co-solvent. By using deuterated methanol (CH3OD), AP HDX was achieved during SFC separation. To prove the concept, thirty one nitrogen- and/or oxygen-containing standard compounds were analyzed by SFC-AP HDX MS. The compounds were successfully speciated from the obtained SFC-MS spectra. The exchange ions were observed with as low as 1% of CH3OD in the mobile phase, and separation could be performed within approximately 20min using approximately 0.24 mL of CH3OD. The results showed that SFC separation and APPI/APCI HDX could be successfully performed using the suggested method. Copyright © 2016 Elsevier B.V. All rights reserved.

Supercritical temperature synthesis of fluorine-doped VO2(M) nanoparticle with improved thermochromic property

Science.gov (United States)

Riapanitra, Anung; Asakura, Yusuke; Cao, Wenbin; Noda, Yasuto; Yin, Shu

2018-06-01

Fluorine-doped VO2(M) nanoparticles have been successfully synthesized using the hydrothermal method at a supercritical temperature of 490 °C. The pristine VO2(M) has the critical phase transformation temperature of 64 °C. The morphology and homogeneity of the monoclinic structure VO2(M) were adopted by the fluorine-doped system. The obtained particle size of the samples is smaller at the higher concentration of anion doping. The best reduction of critical temperature was achieved by fluorine doping of 0.13% up to 48 °C. The thin films of the fluorine-doped VO2(M) showed pronounced thermochromic property and therefore are suitable for smart window applications.

Impregnation of Ibuprofen into Polycaprolactone using supercritical carbon dioxide

Energy Technology Data Exchange (ETDEWEB)

Yoganathan, Roshan; Mammucari, Raffaella; Foster, Neil R, E-mail: n.foster@unsw.edu.a [Supercritical Fluids Research Group, School of Chemical Sciences and Engineering, University of New South Wales, NSW 2052 (Australia)

2010-03-01

Polycaprolactone (PCL) is a Food and Drug Administration (FDA) approved biodegradable polyester used in tissue engineering applications. Ibuprofen is an anti-inflammatory drug which has good solubility in supercritical CO{sub 2} (SCCO{sub 2}). The solubility of CO{sub 2} in PCL allows for the impregnation of CO{sub 2}-soluble therapeutic agents into the polymer via a supercritical fluid (SCF) process. Polymers impregnated with bio-active compounds are highly desired for medical implants and controlled drug delivery. In this study, the use of CO{sub 2} to impregnate PCL with ibuprofen was investigated. The effect of operating conditions on the impregnation of ibuprofen into PCL was investigated over two pressure and two temperature levels, 150bar and 200bar, 35{sup 0}C and 40 {sup 0}C, respectively. Polycaprolactone with drug-loadings as high as 27% w/w were obtained. Impregnated samples exhibited controlled drug release profiles over several days.

Supercritical CO2 impregnation of polyethylene components for medical purposes

Directory of Open Access Journals (Sweden)

Gamse Thomas

2007-01-01

Full Text Available Modem hip and knee endoprosthesis are produced in titanium and to reduce the friction at the contact area polymer parts, mainly ultra-high molecular weight polyethylene (UHMW-PE, are installed. The polyethylene is impregnated with a-tocopherol (vitamin E before processing for remarkable decrease of oxidative degradation. Cross linked UHMW-PE offers much higher stability, but a-tocopherol cannot be added before processing, because a-tocopherol hinders the cross linking process accompanied by a heavy degradation of the vitamin. The impregnation of UHMW-PE with a-tocopherol has to be performed after the cross linking process and an accurate concentration has to be achieved over the cross section of the whole material. In the first tests UHMW-PE-cubes were stored in pure a-tocopherol under inert atmosphere at temperatures from 100 to 150 °C resulting in a high mass fraction of a-tocopherol in the edge zones and no constant concentration over the cross section. For better distribution and for regulating the mass fraction of a-tocopherol in the cross linked UHMW-PE material supercritical CO2 impregnation tests were investigated. Again UHMW-PE-cubes were impregnated in an autoclave with a-tocopherol dissolved in supercritical CO2 at different pressures and temperatures with variable impregnation times and vitamin E concentrations. Based on the excellent results of supercritical CO2 impregnation standard hip and knee cups were stabilized nearly homogeneously with varying mass fraction of a-tocopherol.

Supercritical Fluid Chromatographic Separation of Dimethylpolysiloxane Polymer

Energy Technology Data Exchange (ETDEWEB)

Pyo, Dong Jin; Lim, Chang Hyun [Kangwon National University, Chuncheon (Korea, Republic of)

2005-02-15

Water was used as a polar modifier and a μ-porasil column as a saturator column. The μ-porasil column was inserted between the pump outlet and the injection valve. During the passage of the supercritical fluid mobile phase through the silica column, a polar modifier (water) can be dissolved in the pressurized supercritical fluid. Dimethylpolysiloxane polymer has been known as more polar polymer than polystyrene polymer. Dimethylpolysiloxane polymer has never been separated using water modified mobile phase. In this paper, using a μ-porasil column as a saturator column, excellent supercritical fluid chromatograms of dimethylpolysiloxane oligomers were obtained. The use of compressed (dense) gases and supercritical fluids as chromatographic mobile phases in conjunction with liquid chromatographic (LC)-type packed columns was first reported by Klesper et al. in 1962. During its relatively short history, supercritical fluid chromatography (SFC) has become an attractive alternative to GC and LC in certain industrially important applications. SFC gives the advantage of high efficiency and allows the analysis of nonvolatile or thermally labile mixtures.

Supercritical Fluid Chromatographic Separation of Dimethylpolysiloxane Polymer

International Nuclear Information System (INIS)

Pyo, Dong Jin; Lim, Chang Hyun

2005-01-01

Water was used as a polar modifier and a μ-porasil column as a saturator column. The μ-porasil column was inserted between the pump outlet and the injection valve. During the passage of the supercritical fluid mobile phase through the silica column, a polar modifier (water) can be dissolved in the pressurized supercritical fluid. Dimethylpolysiloxane polymer has been known as more polar polymer than polystyrene polymer. Dimethylpolysiloxane polymer has never been separated using water modified mobile phase. In this paper, using a μ-porasil column as a saturator column, excellent supercritical fluid chromatograms of dimethylpolysiloxane oligomers were obtained. The use of compressed (dense) gases and supercritical fluids as chromatographic mobile phases in conjunction with liquid chromatographic (LC)-type packed columns was first reported by Klesper et al. in 1962. During its relatively short history, supercritical fluid chromatography (SFC) has become an attractive alternative to GC and LC in certain industrially important applications. SFC gives the advantage of high efficiency and allows the analysis of nonvolatile or thermally labile mixtures

Development of a Convective Heat Transfer Correlation of a Supercritical CO2 with Vertical Downward Flow in Circular Tubes

International Nuclear Information System (INIS)

Yoo, Tae Ho; Kim, Hwan Yeol; Bae, Yoon Yeong

2009-01-01

Pressure of coolant flowing through a SCWR core subchannel is supercritical and the heat transfer behavior is known to be quite different from those at a subcritical pressure. Therefore the heat transfer study in a supercritical pressure is required for the acquisition of a reliable heat transfer correlation. A downward flow as well as an upward flow occurs in a multi-pass reactor core. The heat transfer at a supercritical pressure in downward channel has been known to result in a quite different behavior from an upward flow. An experiment for a supercritical CO 2 flowing vertically downward in circular tubes with inner diameters of 6.32 mm and 9 mm was performed by using SPHINX(Supercritical Pressure Heat transfer Investigation for NeXt generation) at KAERI. The obtained test results are compared with the estimations from the existing correlations and an empirical formula for a downward flow is suggested

Generation of Microcellular Biodegradable Polycaprolactone Foams in Supercritical Carbon Dioxide

Institute of Scientific and Technical Information of China (English)

Xu Qun; Ren Xian-wen; Chang Yu-ning; Yu Long; Wang Jing-wu

2004-01-01

Present now the application of microcellular polymeric materials in biomedical field is growing rapidly, as that of guided tissue regeneration and cell transplantation. As far as guided tissue regeneration is concerned, porous implants are used as size selective membrane to promote the growth of a special tissue in a healing site. Ideally, the implant should be inherently biocompatible,have well-defined cell size and be resorbable with appropriate biodegradation rates.Poly(a-caprolactone) (PCL) is a kind of materials suit for the demands above. PCL is biocompatible and biodegradable aliphatic polyester which is nontoxic for living organisms and bioresorbable after a period of implantation. Because of its unique combination of biocompatibility, permeability and biodegradability, PCL and some of its copolymer with lactides and glycolide have been widely applied in medicine as artificial skin, artificial bone and containers for sustained drug release.Goel and Beckman have reported a new method to generate microcellular poly(methy l methacrylate) foams in which the samples are saturated with CO2 under a series of supercritical (SC)conditions, and then the system is rapidly depressurized to atmospheric pressure at constant temperature. Unlike traditional methods, it reduces glass-transition temperature (Tg) of the mixture to below the experimental temperature rather than directly heat the system above Tg. In this process of nucleation, no phase separation occurs as well as no phase boundary meets, so the cellular structure of the foam can be retained better.In this work, we have generated PCL foams by using supercritical CO2. Because of the low glass transition temperature (Tg = -60 ℃) of PCL far below the ice point, the experimental temperature in our study is much higher than Tg, which is different from the studies by others before. A series of variable factors on the foam structure as saturation temperature, saturation pressure, saturation time and depressurization

Thermodynamic analysis of a supercritical water reactor

International Nuclear Information System (INIS)

Edwards, M.

2007-01-01

A thermodynamic model has been developed for a hypothetical design of a Supercritical Water Reactor, with emphasis on Canadian design criteria. The model solves for cycle efficiency, mass flows and physical conditions throughout the plant based on input parameters of operating pressures and efficiencies of components. The model includes eight feedwater heaters, three feedwater pumps, a deaerator, a condenser, the core, three turbines and two reheaters. To perform the calculations, Microsoft Excel was used in conjunction with FLUIDCAL-IAPWS95 and VBA code. The calculations show that a thermal efficiency of 47.5% can be achieved with a core outlet temperature of 625 o C. (author)

Biodiesel production with continuous supercritical process: non-catalytic transesterification and esterification with or without carbon dioxide.

Science.gov (United States)

Tsai, Yu-Ting; Lin, Ho-mu; Lee, Ming-Jer

2013-10-01

The non-catalytic transesterification of refined sunflower oil with supercritical methanol, in the presence of carbon dioxide, was conducted in a tubular reactor at temperatures from 553.2 to 593.2K and pressures up to 25.0 MPa. The FAME yield can be achieved up to about 0.70 at 593.2 K and 10.0 MPa in 23 min with methanol:oil of 25:1 in molar ratio. The effect of adding CO2 on the FAME yield is insignificant. The kinetic behavior of the non-catalytic esterification and transesterification of oleic acid or waste cooking oil (WCO) with supercritical methanol was also investigated. By using the supercritical process, the presence of free fatty acid (FFA) in WCO gives positive contribution to FAME production. The FAME yield of 0.90 from WCO can be achieved in 13 min at 573.2K. The kinetic data of supercritical transesterification and esterifaication were correlated well with a power-law model. Copyright © 2012 Elsevier Ltd. All rights reserved.

Heat transfer to water at supercritical pressures in a circular and square annular flow geometry

International Nuclear Information System (INIS)

Licht, Jeremy; Anderson, Mark; Corradini, Michael

2008-01-01

A supercritical water heat transfer facility has been built at the University of Wisconsin to study heat transfer in a circular and square annular flow channel. Operating conditions included mass velocities of 350-1425 kg/m 2 s, heat fluxes up to 1.0 MW/m 2 , and bulk inlet temperatures up to 400 o C; all at a pressure of 25 MPa. The accuracy and validity of selected heat transfer correlations and buoyancy criterion were compared with heat transfer measurements. Jackson's Nusselt correlation was able to best predict the test data, capturing 86% of the data within 25%. Watts Nusselt correlation showed a similar trend but under predicted measurements by 10% relative to Jackson's. Comparison of experimental results with results of previous investigators has shown general agreement with high mass velocity data. Low mass velocity data have provided some insight into the difficulty in applying these Nusselt correlations to a region of deteriorated heat transfer. Geometrical differences in heat transfer were seen when deterioration was present. Jackson's buoyancy criterion predicted the onset of deterioration while modifications were applied to Seo's Froude number based criterion

Development of a test facility for analyzing transients in supercritical water-cooled reactors by fractional scaling analysis

Energy Technology Data Exchange (ETDEWEB)

Roberto, Thiago D., E-mail: thiagodbtr@gmail.com [Instituto de Engenharia Nuclear (IEN/CNEN—RJ), Rua Hélio de Almeida, 75 21941-972, Rio de Janeiro Caixa-Postal: 68550, RJ (Brazil); Silva, Mário A. B. da, E-mail: mabs500@gmail.com [Departamento de Energia Nuclear (CTG/UFPE), Av. Professor Luiz Freire, 1000, Recife 50740-540, PE (Brazil); Lapa, Celso M.F., E-mail: lapa@ien.gov.br [Instituto de Engenharia Nuclear (IEN/CNEN—RJ), Rua Hélio de Almeida, 75 21941-972, Rio de Janeiro Caixa-Postal: 68550, RJ (Brazil)

2016-01-15

The feasibility of performing experiments using water under supercritical conditions is limited by technical and financial difficulties. These difficulties can be overcome by using model fluids that are characterized by feasible supercritical conditions, that is, lower critical pressure and critical temperature. Experimental investigations are normally used to determine the conditions under which model fluids reliably represent supercritical fluids under steady-state conditions. A fluid-to-fluid scaling approach has been proposed to determine the model fluids that represent supercritical fluids in a transient state. Recently, a similar technique known as fractional scaling analysis was developed to establish the conditions under which experiments can be performed using models that represent transients in prototypes. This paper presents a fractional scaling analysis application to determine parameters for a test facility in which transient conditions in supercritical water-cooled reactors are simulated by using carbon dioxide as a model fluid, whose critical point conditions are more feasible than those of water. Similarity is obtained between water (prototype) and carbon dioxide (model) by depressurization in a simple vessel. The main parameters required for the construction of a future test facility are obtained using the proposed method.

Development of a test facility for analyzing transients in supercritical water-cooled reactors by fractional scaling analysis

International Nuclear Information System (INIS)

Roberto, Thiago D.; Silva, Mário A. B. da; Lapa, Celso M.F.

2016-01-01

The feasibility of performing experiments using water under supercritical conditions is limited by technical and financial difficulties. These difficulties can be overcome by using model fluids that are characterized by feasible supercritical conditions, that is, lower critical pressure and critical temperature. Experimental investigations are normally used to determine the conditions under which model fluids reliably represent supercritical fluids under steady-state conditions. A fluid-to-fluid scaling approach has been proposed to determine the model fluids that represent supercritical fluids in a transient state. Recently, a similar technique known as fractional scaling analysis was developed to establish the conditions under which experiments can be performed using models that represent transients in prototypes. This paper presents a fractional scaling analysis application to determine parameters for a test facility in which transient conditions in supercritical water-cooled reactors are simulated by using carbon dioxide as a model fluid, whose critical point conditions are more feasible than those of water. Similarity is obtained between water (prototype) and carbon dioxide (model) by depressurization in a simple vessel. The main parameters required for the construction of a future test facility are obtained using the proposed method.

Supercritical droplet dynamics and emission in low speed cross-flows

International Nuclear Information System (INIS)

Chae, J. W.; Yang, H. S.; Yoon, W. S.

2008-01-01

Droplet dynamics and emission of a supercritical droplet in crossing gas stream are numerically investigated. Effects of ambient pressure and velocity of nitrogen gas on the dynamics of the supercritical oxygen droplet are parametrically examined. Unsteady conservative axisymmetric Navier-Stokes equations in curvilinear coordinates are preconditioned and solved by dual-time stepping method. A unified property evaluation scheme based on a fundamental equation of state and extended corresponding-state principle is established to deal with thermodynamic non-idealities and transport anomalies. At lower pressures and velocities of nitrogen cross flows, both the diffusion and the convection are important in determining the droplet dynamics. Relative flow motion causes a secondary breakup and cascading vortices, and the droplet lifetime is reduced with increasing in ambient pressure. At higher ambient pressures and velocities, however, the droplet dynamics become convection-controlled while the secondary breakup is hindered by reduced diffusivity of the oxygen. Gas-phase mixing depends on the convection and diffusion velocities in conjunction with corresponding droplet deformation and flow interaction. Supercritical droplet dynamics and emission is not similar with respect to the pressure and velocity of the ambient gas and thus provides no scale

Experimental investigation on combustion performance of cavity-strut injection of supercritical kerosene in supersonic model combustor

Science.gov (United States)

Sun, Ming-bo; Zhong, Zhan; Liang, Jian-han; Wang, Hong-bo

2016-10-01

Supersonic combustion with cavity-strut injection of supercritical kerosene in a model scramjet engine was experimentally investigated in Mach 2.92 facility with the stagnation temperatures of approximately 1430 K. Static pressure distribution in the axial direction was determined using pressure transducers installed along the centerline of the model combustor top walls. High speed imaging camera was used to capture flame luminosity and combustion region distribution. Multi-cavities were used to and stabilize the combustion in the supersonic combustor. Intrusive injection by thin struts was used to enhance the fuel-air mixing. Supercritical kerosene at temperatures of approximately 780 K and various pressures was prepared using a heat exchanger driven by the hot gas from a pre-burner and injected at equivalence ratios of approximately 1.0. In the experiments, combustor performances with different strut injection schemes were investigated and compared to direct wall injection scheme based on the measured static pressure distributions, the specific thrust increments and the images obtained by high-speed imaging camera. The experimental results showed that the injection by thin struts could obtain an enhanced mixing in the field but could not acquire a steady flame when mixing field cannot well match cavity separation region. There is no significant difference on performance between different schemes since the unsteady intermittent and oscillating flame leads to no actual combustion efficiency improvement.

High-pressure phase behavior of propyl lactate and butyl lactate in supercritical carbon dioxide

International Nuclear Information System (INIS)

Cho, Dong Woo; Shin, Jungin; Shin, Moon Sam; Bae, Won; Kim, Hwayong

2012-01-01

Highlights: ► The phase behavior of propyl lactate and butyl lactate in scCO 2 was measured. ► Experimental data were correlated by the PR-EOS. ► The critical constants were estimated by the three group contribution methods. ► Acentric factor was estimated by the Lee–Kesler method. ► The Nannoolal–Rarey and Lee–Kesler method shows the best correlation results. - Abstract: Lactate esters synthesized with lactic acid and ester are used as solvents and reactants in various industries, including agricultural chemistry, pharmaceuticals, electronics, and fine chemicals. Among lactate esters, high purity propyl lactate and butyl lactate are used to produce fine chemicals and in the synthesis of chiral intermediates for use in pesticides and drugs. However, distillation for the removal of propyl lactate and butyl lactate alters or degenerates products due the high boiling points of these two lactate esters. This problem can be solved by supercritical fluid extraction (SCFE) at lower temperatures. SCFE process requires high-pressure phase behavior data on CO 2 and lactates for its design and operation. In this study, high-pressure phase behavior of propyl lactate and butyl lactate in CO 2 was measured from (323.2 to 363.2) K using a variable-volume view cell apparatus. Experimental data were well correlated by the Peng–Robinson equation of state using the van der Waals one-fluid mixing rules. The critical constants were estimated by the Joback method, the Constantinou–Gani method, and the Nannoolal–Rarey method. Acentric factor was estimated by the Lee–Kesler method.

Mixing Dynamics of Supercritical Droplets and Jets

National Research Council Canada - National Science Library

Talley, Douglas G; Cohn, R. K; Coy, E. B; Chehroudi, B; Davis, D. W

2005-01-01

.... At supercritical pressures, however, a distinct difference between "gaseous" and "liquid" phases no longer exists, surface tension and the enthalpy of vaporization vanish, and "gas" phase density...

Study on neutronics performance of flower shape advanced supercritical water cooled fast reactor with different solid moderators

International Nuclear Information System (INIS)

Yu Tao; Li Zhifeng; Xie Jinsen; Peng Honghua

2015-01-01

The supercritical water cooled fast reactors worked at such harsh condition with high temperature and high pressure, huge hydrogen balance pressure and thermal shock can result in a great loss of hydrogen. The released hydrogen would be out of control under accident situations. K_e_f_f, conversion ratio, moderator temperature effect, Doppler effect and void effect of different material such as ZrH_1_._7, Bp, BeO, C and SiC are discussed. BeO and SiC hold better integrated performance among these materials. Besides, moderators have less effect on the Doppler effect of fuel. (authors)

SCW Pressure-Channel Nuclear Reactors: Some Design Features and Concepts

International Nuclear Information System (INIS)

Duffey, R.B.; Pioro, I.L.; Gabaraev, B.A.; Kuznetsov, Yu. N.

2006-01-01

Concepts of nuclear reactors cooled with water at supercritical pressures were studied as early as the 1950's and 1960's in the USA and Russia. After a 30-year break, the idea of developing nuclear reactors cooled with supercritical water (SCW) became attractive again as the ultimate development path for water-cooling. The main objectives of using SCW in nuclear reactors are 1) to increase the thermal efficiency of modern nuclear power plants (NPPs) from 33 -- 35% to about 40 -- 45%, and 2) to decrease capital and operational costs and hence decrease electrical energy costs (∼$ 1000 US/kW). SCW NPPs will have much higher operating parameters compared to modern NPPs (pressure about 25 MPa and outlet temperature up to 625 deg. C), and a simplified flow circuit, in which steam generators, steam dryers, steam separators, etc., can be eliminated. Also, higher SCW temperatures allow direct thermo-chemical production of hydrogen at low cost, due to increased reaction rates. Pressure-channel SCW nuclear reactor concepts are being developed in Canada and Russia. Design features related to both channels and fuel bundles are discussed in this paper. Also, Russian experience with operating supercritical steam heaters at NPP is presented. The main conclusion is that development of SCW pressure-channel nuclear reactors is feasible and significant benefits can be expected over other thermal energy systems. (authors)

Supercritical carbon dioxide (SC-CO2) extraction of essential oil from Swietenia mahagoni seeds

Science.gov (United States)

Norodin, N. S. M.; Salleh, L. M.; Hartati; Mustafa, N. M.

2016-11-01

Swietenia mahagoni (Mahogany) is a traditional plant that is rich with bioactive compounds. In this study, process parameters such as particle size, extraction time, solvent flowrate, temperature and pressure were studied on the extraction of essential oil from Swietenia mahagoni seeds by using supercritical carbon dioxide (SC-CO2) extraction. Swietenia mahagoni seeds was extracted at a pressure of 20-30 MPa and a temperature of 40-60°C. The effect of particle size on overall extraction of essential oil was done at 30 MPa and 50°C while the extraction time of essential oil at various temperatures and at a constant pressure of 30 MPa was studied. Meanwhile, the effect of flowrate CO2 was determined at the flowrate of 2, 3 and 4 ml/min. From the experimental data, the extraction time of 120 minutes, particle size of 0.5 mm, the flowrate of CO2 of 4 ml/min, at a pressure of 30 MPa and the temperature of 60°C were the best conditions to obtain the highest yield of essential oil.

Large Eddy Simulation of Cryogenic Injection Processes at Supercritical Pressure

Science.gov (United States)

Oefelein, Joseph C.

2002-01-01

This paper highlights results from the first of a series of hierarchical simulations aimed at assessing the modeling requirements for application of the large eddy simulation technique to cryogenic injection and combustion processes in liquid rocket engines. The focus is on liquid-oxygen-hydrogen coaxial injectors at a condition where the liquid-oxygen is injected at a subcritical temperature into a supercritical environment. For this situation a diffusion dominated mode of combustion occurs in the presence of exceedingly large thermophysical property gradients. Though continuous, these gradients approach the behavior of a contact discontinuity. Significant real gas effects and transport anomalies coexist locally in colder regions of the flow, with ideal gas and transport characteristics occurring within the flame zone. The current focal point is on the interfacial region between the liquid-oxygen core and the coaxial hydrogen jet where the flame anchors itself.

Quality of Cosmetic Argan Oil Extracted by Supercritical Fluid Extraction from Argania spinosa L.

Directory of Open Access Journals (Sweden)

Chouaa Taribak

2013-01-01

Full Text Available Argan oil has been extracted using supercritical CO2. The influence of the variables pressure (100, 200, 300, and 400 bar and temperature (35, 45, 55°C was investigated. The best extraction yields were achieved at a temperature of 45°C and a pressure of 400 bar. The argan oil extracts were characterized in terms of acid, peroxide and iodine values, total tocopherol, carotene, and fatty acids content. Significant compositional differences were not observed between the oil samples obtained using different pressures and temperatures. The antioxidant capacity of the argan oil samples was high in comparison to those of walnut, almond, hazelnut, and peanut oils and comparable to that of pistachio oil. The physicochemical parameters of the extracted oils obtained by SFE, Soxhlet, and traditional methods are comparable. The technique used for oil processing does not therefore markedly alter the quality of argan oil.

Laboratory experiments for understanding mechanical properties of fractured granite under supercritical conditions

Science.gov (United States)

Kitamura, M.; Takahashi, M.; Takagi, K.; Hirano, N.; Tsuchiya, N.

2017-12-01

To extract geothermal energy effectively and safely from magma and/or adjacent hot rock, we need to tackle many issues which require new technology development, such as a technique to control a risk from induced-earthquakes. On a development of induced-earthquake mitigation technology, it is required to understand roles of factors on occurrences of the induced-earthquake (e.g., strength, crack density, and fluid-rock reaction) and their intercorrelations (e.g., Asanuma et al., 2012). Our purpose of this series of experiments is to clarify a relationship between the rock strength and the crack density under supercritical conditions. We conducted triaxial deformation test on intact granite rock strength under high-temperature (250 - 750°C), high-pressure (104 MPa) condition at a constant load velocity (0.1 μm/sec) using a gas-rig at AIST. We used Oshima granite, which has initially Young's modulus increased with decreasing the temperature from 32.3 GPa at 750°C to 57.4 GPa at 250°C. At 400 °C, the stress drop accelerated the deformation with 98 times faster velocity than that at load-point. In contrast, at 650°C and 750°C, the velocity during stress drop kept the same order of the load-point velocity. Therefore, the deformation mechanism may start to be changed from brittle to ductile when the temperature exceeds 650°C. Highly dense cracked granite specimens were formed by a rapid decompression test (RDT) using an autoclave settled at Tohoku University (Hirano et al., 2016JpGU), caused by a reduction of fluid pressure within 1-2 sec from vapor/supercritical state (10 - 48 MPa, 550 °C) to ambient pressure. The specimens after RDT show numerous microcracks on X-ray CT images. The RDT imposed the porosity increasing towards 3.75 % and Vp and Vs decreasing towards 1.37±0.52 km/s and 0.97±0.25 km/s. The Poisson's ratio shows the negative values in dry and 0.5 in wet. In the meeting, we will present results of triaxial deformation test on such cracked granites

Thermodynamic analysis and numerical modeling of supercritical injection

OpenAIRE

Banuti, Daniel

2015-01-01

Although liquid propellant rocket engines are operational and have been studied for decades, cryogenic injection at supercritical pressures is still considered essentially not understood. This thesis intends to approach this problem in three steps: by developing a numerical model for real gas thermodynamics, by extending the present thermodynamic view of supercritical injection, and finally by applying these methods to the analysis of injection. A new numerical real gas thermodynamics mode...

Method of making supercritical fluid molecular spray films, powder and fibers

Science.gov (United States)

Smith, Richard D.

1988-01-01

Solid films are deposited, or fine powders formed, by dissolving a solid material into a supercritical fluid solution at an elevated pressure and then rapidly expanding the solution through a heated nozzle having a short orifice into a region of relatively low pressure. This produces a molecular spray which is directed against a substrate to deposit a solid thin film thereon, or discharged into a collection chamber to collect a fine powder. In another embodiment, the temperature of the solution and nozzle is elevated above the melting point of the solute, which is preferably a polymer, and the solution is maintained at a pressure such that, during expansion, the solute precipitates out of solution within the nozzle in a liquid state. Alternatively, a secondary solvent mutually soluble with the solute and primary solvent and having a higher critical temperature than that of primary solvent is used in a low concentration (<20%) to maintain the solute in a transient liquid state. The solute is discharged in the form of long, thin fibers. The fibers are collected at sufficient distance from the orifice to allow them to solidify in the low pressure/temperature region.

Supercritical fluid molecular spray film deposition and powder formation

Science.gov (United States)

Smith, Richard D.

1986-01-01

Solid films are deposited, or fine powders formed, by dissolving a solid material into a supercritical fluid solution at an elevated pressure and then rapidly expanding the solution through a short orifice into a region of relatively low pressure. This produces a molecular spray which is directed against a substrate to deposit a solid thin film thereon, or discharged into a collection chamber to collect a fine powder. Upon expansion and supersonic interaction with background gases in the low pressure region, any clusters of solvent are broken up and the solvent is vaporized and pumped away. Solute concentration in the solution is varied primarily by varying solution pressure to determine, together with flow rate, the rate of deposition and to control in part whether a film or powder is produced and the granularity of each. Solvent clustering and solute nucleation are controlled by manipulating the rate of expansion of the solution and the pressure of the lower pressure region. Solution and low pressure region temperatures are also controlled.

Hydrogen production by supercritical water gasification of alkaline black liquor

Energy Technology Data Exchange (ETDEWEB)

Cao, Changqing; Guo, Liejin; Chen, Yunan; Lu, Youjun [Xi' an Jiatong Univ. (China)

2010-07-01

Black liquor was gasified continuously in supercritical water successfully and the main gaseous products were H{sub 2}, CO{sub 2} and CH{sub 4} with little amount of CO, C{sub 2}H{sub 4} and C{sub 2}H{sub 6}. The increase of the temperature and the decrease of the flow rate and black liquor concentration enhanced SCWG of black liquor. The change of the system pressure had limited influence on the gasification effect. The maximal COD removal efficiency of 88.69 % was obtained at the temperature of 600 C. The pH values of the aqueous residue were all decreased to the range of 6.4{proportional_to}8 while the pH value of cooling effluence below 360 C increased to about 11 and the sodium content was much higher than that in the aqueous residue. The reaction rate for COD degradation in supercritical water was obtained by assuming pseudo first order reaction. And the activation energy and pre-exponential for COD removal in SCWG were 74.38kJ/mol and 1.11 x 10{sup 4} s{sup -1} respectively. (orig.)

Development of a Convective Heat Transfer Correlation of a Supercritical CO{sub 2} with Vertical Downward Flow in Circular Tubes

Energy Technology Data Exchange (ETDEWEB)

Yoo, Tae Ho; Kim, Hwan Yeol; Bae, Yoon Yeong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2009-05-15

Pressure of coolant flowing through a SCWR core subchannel is supercritical and the heat transfer behavior is known to be quite different from those at a subcritical pressure. Therefore the heat transfer study in a supercritical pressure is required for the acquisition of a reliable heat transfer correlation. A downward flow as well as an upward flow occurs in a multi-pass reactor core. The heat transfer at a supercritical pressure in downward channel has been known to result in a quite different behavior from an upward flow. An experiment for a supercritical CO{sub 2} flowing vertically downward in circular tubes with inner diameters of 6.32 mm and 9 mm was performed by using SPHINX(Supercritical Pressure Heat transfer Investigation for NeXt generation) at KAERI. The obtained test results are compared with the estimations from the existing correlations and an empirical formula for a downward flow is suggested.

Heat Transfer Behaviour and Thermohydraulics Code Testing for Supercritical Water Cooled Reactors (SCWRs)

International Nuclear Information System (INIS)

2014-08-01

The supercritical water cooled reactor (SCWR) is an innovative water cooled reactor concept which uses water pressurized above its thermodynamic critical pressure as the reactor coolant. This concept offers high thermal efficiencies and a simplified reactor system, and is hence expected to help to improve economic competitiveness. Various kinds of SCWR concepts have been developed, with varying combinations of reactor type (pressure vessel or pressure tube) and core spectrum (thermal, fast or mixed). There is great interest in both developing and developed countries in the research and development (R&D) and conceptual design of SCWRs. Considering the high interest shown in a number of Member States, the IAEA established in 2008 the Coordinated Research Project (CRP) on Heat Transfer Behaviour and Thermo-hydraulics Code Testing for SCWRs. The aim was to foster international collaboration in the R&D of SCWRs in support of Member States’ efforts and under the auspices of the IAEA Nuclear Energy Department’s Technical Working Groups on Advanced Technologies for Light Water Reactors (TWG-LWR) and Heavy Water Reactors (TWG-HWR). The two key objectives of the CRP were to establish accurate databases on the thermohydraulics of supercritical pressure fluids and to test analysis methods for SCWR thermohydraulic behaviour to identify code development needs. In total, 16 institutes from nine Member States and two international organizations were involved in the CRP. The thermohydraulics phenomena investigated in the CRP included heat transfer and pressure loss characteristics of supercritical pressure fluids, development of new heat transfer prediction methods, critical flow during depressurization from supercritical conditions, flow stability and natural circulation in supercritical pressure systems. Two code testing benchmark exercises were performed for steady state heat transfer and flow stability in a heated channel. The CRP was completed with the planned outputs in

Heat Transfer Behaviour and Thermohydraulics Code Testing for Supercritical Water Cooled Reactors (SCWRs)

Energy Technology Data Exchange (ETDEWEB)

NONE

2014-08-15

The supercritical water cooled reactor (SCWR) is an innovative water cooled reactor concept which uses water pressurized above its thermodynamic critical pressure as the reactor coolant. This concept offers high thermal efficiencies and a simplified reactor system, and is hence expected to help to improve economic competitiveness. Various kinds of SCWR concepts have been developed, with varying combinations of reactor type (pressure vessel or pressure tube) and core spectrum (thermal, fast or mixed). There is great interest in both developing and developed countries in the research and development (R&D) and conceptual design of SCWRs. Considering the high interest shown in a number of Member States, the IAEA established in 2008 the Coordinated Research Project (CRP) on Heat Transfer Behaviour and Thermo-hydraulics Code Testing for SCWRs. The aim was to foster international collaboration in the R&D of SCWRs in support of Member States’ efforts and under the auspices of the IAEA Nuclear Energy Department’s Technical Working Groups on Advanced Technologies for Light Water Reactors (TWG-LWR) and Heavy Water Reactors (TWG-HWR). The two key objectives of the CRP were to establish accurate databases on the thermohydraulics of supercritical pressure fluids and to test analysis methods for SCWR thermohydraulic behaviour to identify code development needs. In total, 16 institutes from nine Member States and two international organizations were involved in the CRP. The thermohydraulics phenomena investigated in the CRP included heat transfer and pressure loss characteristics of supercritical pressure fluids, development of new heat transfer prediction methods, critical flow during depressurization from supercritical conditions, flow stability and natural circulation in supercritical pressure systems. Two code testing benchmark exercises were performed for steady state heat transfer and flow stability in a heated channel. The CRP was completed with the planned outputs in

Prediction of wall friction for fluids at supercritical pressure with CFD models

International Nuclear Information System (INIS)

Angelucci, M.; Ambrosini, W.; Forgione, N.

2011-01-01

In this paper, the STAR-CCM+ CFD code is used in the attempt to reproduce the values of friction factor observed in experimental data at supercritical pressures at various operating conditions. A short survey of available data and correlations for smooth pipe friction in circular pipes puts the basis for the discussion, reporting observed trends of friction factor in the liquid-like and the gas-like regions and within the transitional region around the pseudo-critical temperature. For smooth pipes, a general decrease of the friction factor in the transitional region is reported, constituting one of the relevant effects to be predicted by the computational fluid-dynamic models. A limited number of low-Reynolds number models is adopted, making use of refined near-wall discretisations as required by the constraint y + < 1 at the wall. In particular, the Lien k-ε and the SST k-ω models are considered. The values of the wall shear stress calculated by the code are then post-processed on the basis of bulk fluid properties to obtain the Fanning and then the Darcy-Weisbach friction factors, basing on their classical definitions. The obtained values are compared with those provided by experimental tests and correlations, finding a reasonable qualitative agreement. Expectedly, the agreement is better in the gas-like and liquid-like regions, where fluid property changes are moderate, than in the transitional region, where the trends provided by available correlations are reproduced only in a qualitative way. (author)

Numerical experiment on different validation cases of water coolant flow in supercritical pressure test sections assisted by discriminated dimensional analysis part I: the dimensional analysis

International Nuclear Information System (INIS)

Kiss, A.; Aszodi, A.

2011-01-01

As recent studies prove in contrast to 'classical' dimensional analysis, whose application is widely described in heat transfer textbooks despite its poor results, the less well known and used discriminated dimensional analysis approach can provide a deeper insight into the physical problems involved and much better results in all cases where it is applied. As a first step of this ongoing research discriminated dimensional analysis has been performed on supercritical pressure water pipe flow heated through the pipe solid wall to identify the independent dimensionless groups (which play an independent role in the above mentioned thermal hydraulic phenomena) in order to serve a theoretical base to comparison between well known supercritical pressure water pipe heat transfer experiments and results of their validated CFD simulations. (author)

Materials, Turbomachinery and Heat Exchangers for Supercritical CO2 Systems

Energy Technology Data Exchange (ETDEWEB)

Anderson, Mark; Nellis, Greg; Corradini, Michael

2012-10-19

The objective of this project is to produce the necessary data to evaluate the performance of the supercritical carbon dioxide cycle. The activities include a study of materials compatibility of various alloys at high temperatures, the heat transfer and pressure drop in compact heat exchanger units, and turbomachinery issues, primarily leakage rates through dynamic seals. This experimental work will serve as a test bed for model development and design calculations, and will help define further tests necessary to develop high-efficiency power conversion cycles for use on a variety of reactor designs, including the sodium fast reactor (SFR) and very high-temperature gas reactor (VHTR). The research will be broken into three separate tasks. The first task deals with the analysis of materials related to the high-temperature S-CO{sub 2} Brayton cycle. The most taxing materials issues with regard to the cycle are associated with the high temperatures in the reactor side heat exchanger and in the high-temperature turbine. The system could experience pressures as high as 20MPa and temperatures as high as 650°C. The second task deals with optimization of the heat exchangers required by the S-CO{sub 2} cycle; the S-CO{sub 2} flow passages in these heat exchangers are required whether the cycle is coupled with a VHTR or an SFR. At least three heat exchangers will be required: the pre-cooler before compression, the recuperator, and the heat exchanger that interfaces with the reactor coolant. Each of these heat exchangers is unique and must be optimized separately. The most challenging heat exchanger is likely the pre-cooler, as there is only about a 40°C temperature change but it operates close to the CO{sub 2} critical point, therefore inducing substantial changes in properties. The proposed research will focus on this most challenging component. The third task examines seal leakage through various dynamic seal designs under the conditions expected in the S-CO{sub 2} cycle

Wheat germ oil extracted by supercritical carbon dioxide with ethanol: Fatty acid composition

International Nuclear Information System (INIS)

Parczewska-Plesnar, B.; Brzozowski, R.; Gwardiak, H.; Białecka-Florjańczyk, E.; Bujnowski, Z.

2016-01-01

In this work, supercritical fluid extraction (SFE) using CO2 with ethanol as entrainer was performed at a temperature of 40 o C under a pressure of 21 MPa. For comparison, a similar extraction without the entrainer was carried out. The extraction yield of wheat germ using supercritical CO2 with ethanol was slightly higher (10.7 wt%) than that of extraction without the entrainer (9.9 wt%). Fractions of SFE extracts were collected separately during the experiments and the composition of fatty acids in each fraction was analyzed. The SFE extracted oils were rich (63.4-71.3%) in the most valuable polyunsaturated fatty acids (PUFA) and their content in all collected fractions was approximately constant. Similar PUFA contents were found in the reference samples of oils extracted by n-hexane (66.2-67.0%), while the commercial cold-pressed oil contained significantly less PUFA (60.2%). These results show a higher nutritional value of the oil obtained by extraction with supercritical CO2 than cold pressed oil which is generally considered to be very valuable. [es

Mass transfer and kinetic modelling of supercritical CO 2 extraction of fresh tea leaves (Camellia sinensis L.

Directory of Open Access Journals (Sweden)

Pravin Vasantrao Gadkari

Full Text Available Abstract Supercritical carbon dioxide extraction was employed to extract solids from fresh tea leaves (Camellia sinensis L. at various pressures(15 to 35 MPa and temperatures (313 to 333K with addition of ethanol as a polarity modifier. The diffusion model and Langmuir model fit well to experimental data and the correlation coefficients were greater than 0.94. Caffeine solubility was determined in supercritical CO2 and the Gordillo model was employed to correlate the experimental solubility values. The Gordillo model fit well to the experimental values with a correlation coefficient 0.91 and 8.91% average absolute relative deviation. Total phenol content of spent materials varied from 57 to 85.2 mg of gallic acid equivalent per g spent material, total flavonoid content varied from 50.4 to 58.2 mg of rutin equivalent per g spent material and the IC50 value (antioxidant content varied from 27.20 to 38.11 µg of extract per mL. There was significant reduction in polyphenol, flavonoid and antioxidant content in the extract when supercritical CO2 extraction was carried out at a higher pressure of 35 MPa.

RED WINE EXTRACT OBTAINED BY MEMBRANE-BASED SUPERCRITICAL FLUID EXTRACTION: PRELIMINARY CHARACTERIZATION OF CHEMICAL PROPERTIES.

Directory of Open Access Journals (Sweden)

W. Silva

Full Text Available ABSTRACT This study aims to obtain an extract from red wine by using membrane-based supercritical fluid extraction. This technique involves the use of porous membranes as contactors during the dense gas extraction process from liquid matrices. In this work, a Cabernet Sauvignon wine extract was obtained from supercritical fluid extraction using pressurized carbon dioxide as solvent and a hollow fiber contactor as extraction setup. The process was continuously conducted at pressures between 12 and 18 MPa and temperatures ranged from 30 to 50ºC. Meanwhile, flow rates of feed wine and supercritical CO2 varied from 0.1 to 0.5 mL min-1 and from 60 to 80 mL min-1 (NCPT, respectively. From extraction assays, the highest extraction percentage value obtained from the total amount of phenolic compounds was 14% in only one extraction step at 18MPa and 35ºC. A summarized chemical characterization of the obtained extract is reported in this work; one of the main compounds in this extract could be a low molecular weight organic acid with aromatic structure and methyl and carboxyl groups. Finally, this preliminary characterization of this extract shows a remarkable ORAC value equal to 101737 ± 5324 µmol Trolox equivalents (TE per 100 g of extract.

Exergoeconomic Evaluation of a Modern Ultra-Supercritical Power Plant

Directory of Open Access Journals (Sweden)

Lingnan Wu

2012-09-01

Full Text Available In this paper, the exergoeconomic analysis was conducted to an existing ultra-supercritical coal-fired power plant in China to understand the cost-formation process, to evaluate the economic performance of each component and to find possible solutions for more cost-effective designs. The total revenue requirement (TRR and the specific exergy costing (SPECO methods were applied for economic analysis and exergy costing, respectively. Quantitative balances of exergy and exergetic costs as well as necessary auxiliary equations for both individual component and the overall system were established. The results show that the exergoeconomic factors of the furnace and heat exchangers at low temperature levels, including air preheater and low-pressure feedwater preheaters, are rather small; while those of other components are relatively large. Moving more heat absorption into furnace to use the effective radiation heat transfer, increasing the air preheating temperature and adding more low pressure feedwater preheaters can be promising solutions for future design.

On the use of semiempirical models of (solid + supercritical fluid) systems to determine solid sublimation properties

International Nuclear Information System (INIS)

Tabernero, Antonio; Martin del Valle, Eva M.; Galan, Miguel A.

2011-01-01

Research highlights: → We propose a method to determine sublimation properties of solids. → Low deviations were produced calculating sublimation enthalpies and pressures. → It is a required step to determine the vaporization enthalpy of the solid. → It is possible to determine solid properties using semiempirical models solid-SCF. - Abstract: Experimental solubility data of solid-supercritical fluids have significantly increased in the last few years, and semiempirical models are emerging as one of the best choices to fit this type of data. This work establishes a methodology to calculate sublimation pressures using this type of equations. It requires the use of Bartle's equation to model equilibria data solid-supercritical fluids with the aim of determining the vaporization enthalpy of the compound. Using this method, low deviations were obtained by calculating sublimation pressures and sublimation enthalpies. The values of the sublimation pressures were subsequently used to successfully model different multiphasic equilibria, as solid-supercritical fluids and solid-solvent-supercritical fluids with the Peng-Robinson equation of state (without considering the sublimation pressure as an adjustable parameter). On the other hand, the sublimation pressures were also used to calculate solid sublimation properties and acetaminophen solvation properties in some solvents. Also, solubility data solid-supercritical fluids from 62 pharmaceuticals were fitted with different semiempirical equations (Chrastil, Kumar-Johnston and Bartle models) in order to present the values of solvation enthalpies in sc-CO 2 and vaporization enthalpies for these compounds. All of these results highlight that semiempirical models can be used for any other purpose as well as modeling (solid + supercritical fluids) equilibria.

Selective chelation and extraction of lanthanides and actinides with supercritical fluids

International Nuclear Information System (INIS)

Brauer, R.D.; Carleson, T.E.; Harrington, J.D.; Jean, F.; Jiang, H.; Lin, Y.; Wai, C.M.

1994-01-01

This report is made up of three independent papers: (1) Supercritical Fluid Extraction of Thorium and Uranium with Fluorinated Beta-Diketones and Tributyl Phosphate, (2) Supercritical Fluid Extraction of Lanthanides with Beta-Diketones and Mixed Ligands, and (3) A Group Contribution Method for Predicting the Solubility of Solid Organic Compounds in Supercritical Carbon Dioxide. Experimental data are presented demonstrating the successful extraction of thorium and uranium using fluorinated beta-diketones to form stable complexes that are extracted with supercritical carbon dioxide. The conditions for extracting the lanthanide ions from liquid and solid materials using supercritical carbon dioxide are presented. In addition, the Peng-Robison equation of state and thermodynamic equilibrium are used to predict the solubilities of organic solids in supercritical carbon dioxide from the sublimation pressure, critical properties, and a centric factor of the solid of interest

Biodiesel production through non-catalytic supercritical transesterification: current state and perspectives

Directory of Open Access Journals (Sweden)

C. da Silva

2014-06-01

Full Text Available The inconveniences of the conventional method for biodiesel production by alkaline catalysis suggests research towards alternative methods, with the non-catalytic transesterification using an alcohol at supercritical conditions proposed as a promising technique for biodiesel production. The so-called supercritical method (SCM has powerful advantages over conventional techniques, such as fast reaction rates, feedstock flexibility, production efficiency and environmentally friendly benefits. However, application of this methodology has some limitations, like operating conditions (elevated temperature and pressure and higher amounts of alcohol, which result in high energy costs and degradation of the products generated. In this review paper the state of the art in relation to the use of the SCM for biodiesel production is reported and discussed, describing the characteristics of the method, the influence of operational parameters on the ester yield, patents available in the field and the perspectives for application of the technique.

Optimizing supercritical carbon dioxide in the inactivation of bacteria in clinical solid waste by using response surface methodology

International Nuclear Information System (INIS)

Hossain, Md. Sohrab; Nik Ab Rahman, Nik Norulaini; Balakrishnan, Venugopal; Alkarkhi, Abbas F.M.; Ahmad Rajion, Zainul; Ab Kadir, Mohd Omar

2015-01-01

Highlights: • Supercritical carbon dioxide sterilization of clinical solid waste. • Inactivation of bacteria in clinical solid waste using supercritical carbon dioxide. • Reduction of the hazardous exposure of clinical solid waste. • Optimization of the supercritical carbon dioxide experimental conditions. - Abstract: Clinical solid waste (CSW) poses a challenge to health care facilities because of the presence of pathogenic microorganisms, leading to concerns in the effective sterilization of the CSW for safe handling and elimination of infectious disease transmission. In the present study, supercritical carbon dioxide (SC-CO 2 ) was applied to inactivate gram-positive Staphylococcus aureus, Enterococcus faecalis, Bacillus subtilis, and gram-negative Escherichia coli in CSW. The effects of SC-CO 2 sterilization parameters such as pressure, temperature, and time were investigated and optimized by response surface methodology (RSM). Results showed that the data were adequately fitted into the second-order polynomial model. The linear quadratic terms and interaction between pressure and temperature had significant effects on the inactivation of S. aureus, E. coli, E. faecalis, and B. subtilis in CSW. Optimum conditions for the complete inactivation of bacteria within the experimental range of the studied variables were 20 MPa, 60 °C, and 60 min. The SC-CO 2 -treated bacterial cells, observed under a scanning electron microscope, showed morphological changes, including cell breakage and dislodged cell walls, which could have caused the inactivation. This espouses the inference that SC-CO 2 exerts strong inactivating effects on the bacteria present in CSW, and has the potential to be used in CSW management for the safe handling and recycling-reuse of CSW materials

Optimizing supercritical carbon dioxide in the inactivation of bacteria in clinical solid waste by using response surface methodology

Energy Technology Data Exchange (ETDEWEB)

Hossain, Md. Sohrab [Department of Environmental Technology, School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang (Malaysia); Nik Ab Rahman, Nik Norulaini [School of Distance Education, Universiti Sains Malaysia, 11800 Penang (Malaysia); Balakrishnan, Venugopal [Institute for Research in Molecular Medicine, Universiti Sains Malaysia, 11800 Penang (Malaysia); Alkarkhi, Abbas F.M. [Department of Environmental Technology, School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang (Malaysia); Ahmad Rajion, Zainul [School of Dental Science, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan (Malaysia); Ab Kadir, Mohd Omar, E-mail: akmomar@usm.my [Department of Environmental Technology, School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang (Malaysia)

2015-04-15

Highlights: • Supercritical carbon dioxide sterilization of clinical solid waste. • Inactivation of bacteria in clinical solid waste using supercritical carbon dioxide. • Reduction of the hazardous exposure of clinical solid waste. • Optimization of the supercritical carbon dioxide experimental conditions. - Abstract: Clinical solid waste (CSW) poses a challenge to health care facilities because of the presence of pathogenic microorganisms, leading to concerns in the effective sterilization of the CSW for safe handling and elimination of infectious disease transmission. In the present study, supercritical carbon dioxide (SC-CO{sub 2}) was applied to inactivate gram-positive Staphylococcus aureus, Enterococcus faecalis, Bacillus subtilis, and gram-negative Escherichia coli in CSW. The effects of SC-CO{sub 2} sterilization parameters such as pressure, temperature, and time were investigated and optimized by response surface methodology (RSM). Results showed that the data were adequately fitted into the second-order polynomial model. The linear quadratic terms and interaction between pressure and temperature had significant effects on the inactivation of S. aureus, E. coli, E. faecalis, and B. subtilis in CSW. Optimum conditions for the complete inactivation of bacteria within the experimental range of the studied variables were 20 MPa, 60 °C, and 60 min. The SC-CO{sub 2}-treated bacterial cells, observed under a scanning electron microscope, showed morphological changes, including cell breakage and dislodged cell walls, which could have caused the inactivation. This espouses the inference that SC-CO{sub 2} exerts strong inactivating effects on the bacteria present in CSW, and has the potential to be used in CSW management for the safe handling and recycling-reuse of CSW materials.

Application of response surface methodology for the optimization of supercritical fluid extraction of essential oil from pomegranate (Punica granatum L.) peel.

Science.gov (United States)

Ara, Katayoun Mahdavi; Raofie, Farhad

2016-07-01

Essential oils and volatile components of pomegranate ( Punica granatum L.) peel of the Malas variety from Meybod, Iran, were extracted using supercritical fluid extraction (SFE) and hydro-distillation methods. The experimental parameters of SFE that is pressure, temperature, extraction time, and modifier (methanol) volume were optimized using a central composite design after a (2 4-1 ) fractional factorial design. Detailed chemical composition of the essential oils and volatile components obtained by hydro-distillation and optimum condition of the supercritical CO 2 extraction were analyzed by GC-MS, and seventy-three and forty-six compounds were identified according to their retention indices and mass spectra, respectively. The optimum SFE conditions were 350 atm pressure, 55 °C temperature, 30 min extraction time, and 150 µL methanol. Results showed that oleic acid, palmitic acid and (-)-Borneol were major compounds in both extracts. The optimum extraction yield was 1.18 % (w/w) for SFE and 0.21 % (v/w) for hydro-distillation.

Performance optimization of low-temperature power generation by supercritical ORCs (organic Rankine cycles) using low GWP (global warming potential) working fluids

International Nuclear Information System (INIS)

Le, Van Long; Feidt, Michel; Kheiri, Abdelhamid; Pelloux-Prayer, Sandrine

2014-01-01

This paper presents the system efficiency optimization scenarios of basic and regenerative supercritical ORCs (organic Rankine cycles) using low-GWP (global warming potential) organic compounds as working fluid. A more common refrigerant, i.e. R134a, was also employed to make the comparison. A 150-°C, 5-bar-pressurized hot water is used to simulate the heat source medium. Power optimization was equally performed for the basic configuration of supercritical ORC. Thermodynamic performance comparison of supercritical ORCs using different working fluids was achieved by ranking method and exergy analysis method. The highest optimal efficiency of the system (η sys ) is always obtained with R152a in both basic (11.6%) and regenerative (13.1%) configurations. The highest value of optimum electrical power output (4.1 kW) is found with R1234ze. By using ranking method and considering low-GWP criterion, the best working fluids for system efficiency optimization of basic and regenerative cycles are R32 and R152a, respectively. The best working fluid for net electrical power optimization of basic cycle is R1234ze. Although CO 2 has many desirable environmental and safety properties (e.g. zero ODP (Ozone Depletion Potential), ultra low-GWP, non toxicity, non flammability, etc.), the worst thermodynamic performance is always found with the cycle using this compound as working fluid. - Highlights: • Performance optimizations were carried out for the supercritical ORCs using low-GWP working fluids. • Heat regeneration was used to improve the system efficiency of the supercritical ORC. • Thermodynamic performances of supercritical ORCs at the optima were evaluated by ranking method and exergy analysis

Under-expanded jets and dispersion in supercritical CO_2 releases from a large-scale pipeline

International Nuclear Information System (INIS)

Guo, Xiaolu; Yan, Xingqing; Yu, Jianliang; Zhang, Yongchun; Chen, Shaoyun; Mahgerefteh, Haroun; Martynov, Sergey; Collard, Alexander; Proust, Christophe

2016-01-01

Highlights: • A large-scale full instrumented CO_2 test pipeline (258 m long, 233 mm id) has been developed. • The dynamic pressure evolutions near the orifice were recorded with differential pressure transducers. • The highly under-expanded jet flow structure in the near-field was studied in supercritical leakage. • The formation of the visible cloud, the distributions of temperature and concentration in the far-field were analysed. - Abstract: Long-distance CO_2 pipelines will be widely applied to transport captured CO_2 from fossil fuel fired power plants for subsequent sequestration. In the event of pipeline failure a large mass of the inventory may be discharged within a short time, this represents a significant hazard if leaks continue undetected. An important result of the risk assessment for a CO_2 pipeline is the safety distance. At present the lack of knowledge concerning near-field source terms and the far-field dispersion behavior of CO_2 leaking from pipelines can make the calculation of safety distances imprecise. Study of near-field source terms and dispersion behavior is therefore necessary and of paramount importance for assessing safety distances and the impact of CO_2 pipeline releases on the surrounding environment. In order to study CO_2 pipeline leakage, a large-scale pipeline set-up with a total length of 258 m and an internal diameter of 233 mm was constructed to study the near-field characteristics and dispersion behavior of supercritical CO_2 during sudden releases. The dynamic pressure near the orifice and CO_2 concentrations and temperatures within the downstream dispersion region were measured together with the pressures inside the pipeline. The under-expanded jet flow structure and phase transitions in the near-field were studied for supercritical CO_2 released though different orifice diameters (15 mm, 50 mm and Full Bore Rupture). The formation of the visible cloud, the distribution of cloud temperatures and CO_2

Advanced Concepts for Pressure-Channel Reactors: Modularity, Performance and Safety

Science.gov (United States)

Duffey, Romney B.; Pioro, Igor L.; Kuran, Sermet

Based on an analysis of the development of advanced concepts for pressure-tube reactor technology, we adapt and adopt the pressure-tube reactor advantage of modularity, so that the subdivided core has the potential for optimization of the core, safety, fuel cycle and thermal performance independently, while retaining passive safety features. In addition, by adopting supercritical water-cooling, the logical developments from existing supercritical turbine technology and “steam” systems can be utilized. Supercritical and ultra-supercritical boilers and turbines have been operating for some time in coal-fired power plants. Using coolant outlet temperatures of about 625°C achieves operating plant thermal efficiencies in the order of 45-48%, using a direct turbine cycle. In addition, by using reheat channels, the plant has the potential to produce low-cost process heat, in amounts that are customer and market dependent. The use of reheat systems further increases the overall thermal efficiency to 55% and beyond. With the flexibility of a range of plant sizes suitable for both small (400 MWe) and large (1400 MWe) electric grids, and the ability for co-generation of electric power, process heat, and hydrogen, the concept is competitive. The choice of core power, reheat channel number and exit temperature are all set by customer and materials requirements. The pressure channel is a key technology that is needed to make use of supercritical water (SCW) in CANDU®1 reactors feasible. By optimizing the fuel bundle and fuel channel, convection and conduction assure heat removal using passive-moderator cooling. Potential for severe core damage can be almost eliminated, even without the necessity of activating the emergency-cooling systems. The small size of containment structure lends itself to a small footprint, impacts economics and building techniques. Design features related to Canadian concepts are discussed in this paper. The main conclusion is that development of

Application of supercritical fluid extraction in analytical science

International Nuclear Information System (INIS)

Kumar, Pradeep

2015-01-01

In the recent years, supercritical fluid extraction (SFE) has emerged as a promising alternative to conventional solvent extraction process owing to its potential to minimize the generation of the liquid volume and simplification of the extraction process.This technology is some times referred to as 'green technology' and 'clean technology'. Supercritical fluid extraction process assumes significance as it exhibits practical advantages such as enhanced extraction rate due to rapid mass transfer in supercritical fluid medium and change of solvent properties such as density by tuning pressure/temperature conditions. Supercritical fluids (SCF) offer faster, cleaner and efficient extraction owing to low viscosity, high density, low surface tension and better diffusivity properties. Higher diffusivity than liquids facilitates rapid mass transfer and faster completion of reaction. Due to low viscosity and surface tension, SCF can penetrate deep inside the material, extracting the component of interest. Liquid like solvating characteristics of SCFs enable dissolution of compounds whereas gas like diffusion characteristics provide conditions for high degree of extraction in shorter time duration. CO 2 has been widely employed as supercritical fluid owing to its moderate critical constants (Pc= 72.9 atm, Tc =304.3 K, ñ c = 0.47 g mL -1 ) and attractive properties such as being easily available, recyclable, non-toxic, chemically inert, non inflammable and radio-chemically stable. SCF finds application in variety of fields. In nuclear industry for separation and purification of actinides from liquids and solid matrices. In food industry, Decaffeination of coffee is done by SCF. Pharmaceutical industry, organic compounds can be extracted from plants by SC CO 2 avoiding liquid solvent usage. SCF may also be utilised for the production of fine powders. In polymer and plastics industries, examples of applications include the impregnation of medical material

Evaluation of high temperature pressure sensors

International Nuclear Information System (INIS)

Choi, In-Mook; Woo, Sam-Yong; Kim, Yong-Kyu

2011-01-01

It is becoming more important to measure the pressure in high temperature environments in many industrial fields. However, there is no appropriate evaluation system and compensation method for high temperature pressure sensors since most pressure standards have been established at room temperature. In order to evaluate the high temperature pressure sensors used in harsh environments, such as high temperatures above 250 deg. C, a specialized system has been constructed and evaluated in this study. The pressure standard established at room temperature is connected to a high temperature pressure sensor through a chiller. The sensor can be evaluated in conditions of changing standard pressures at constant temperatures and of changing temperatures at constant pressures. According to the evaluation conditions, two compensation methods are proposed to eliminate deviation due to sensitivity changes and nonlinear behaviors except thermal hysteresis.

Enhanced arrangement for recuperators in supercritical CO2 Brayton power cycle for energy conversion in fusion reactors

International Nuclear Information System (INIS)

Serrano, I.P.; Linares, J.I.; Cantizano, A.; Moratilla, B.Y.

2014-01-01

Highlights: •We propose an enhanced power conversion system layout for a Model C fusion reactor. •Proposed layout is based on a modified recompression supercritical CO 2 Brayton cycle. •New arrangement in recuperators regards to classical cycle is used. •High efficiency is achieved, comparable with the best obtained in complex solutions. -- Abstract: A domestic research program called TECNO F US was launched in Spain in 2009 to support technological developments related to a dual coolant breeding blanket concept for fusion reactors. This concept of blanket uses Helium (300 °C/400 °C) to cool part of it and a liquid metal (480 °C/700 °C) to cool the rest; it also includes high temperature (700 °C/800 °C) and medium temperature (566 °C/700 °C) Helium cooling circuits for divertor. This paper proposes a new layout of the classical recompression supercritical CO 2 Brayton cycle which replaces one of the recuperators (the one with the highest temperature) by another which by-passes the low temperature blanket source. This arrangement allows reaching high turbine inlet temperatures (around 600 °C) with medium pressures (around 225 bar) and achieving high cycle efficiencies (close to 46.5%). So, the proposed cycle reveals as a promising design because it integrates all the available thermal sources in a compact layout achieving high efficiencies with the usual parameters prescribed in classical recompression supercritical CO 2 Brayton cycles

CFD analysis using two-equation turbulence models for the vertical upward flow of water in a heated tube at supercritical pressure(I)

International Nuclear Information System (INIS)

Kim, Y. I.; Kim, S. H.; Bae, Y. Y.; Cho, B. H.

2003-12-01

Numerical simulation was performed referring to the Yamagata's experiment on the heat transfer in a vertical tube where water flows upward at supercritical pressure. Numerical simulation was performed for the conditions of tube diameter of 7.5 mm, heated tube length of 2 m, operation pressure at 245 bar, bulk temperatures from 300 to 420 .deg. C, heat fluxes from 465 to 930 kW/m 2 and mass velocity 1,260 kg/m 2 s, by Fluent code and compared with the Yamagata's experiments. At the heat flux 465 kW/m 2 , the maximum difference between calculated results and Yamagata's experiment were less than 20% and the difference between the results using different turbulence models was not so significant. But at the heat flux, 930 kW/m 2 , the difference between the calculations and Yamagata's experiment increased to about 25%, and the difference between the results using different turbulence models increased significantly. The case with RNG κ-ε and enhanced wall treatment predicted the Yamagata's experiment best

Design and operational parameters of transportable supercritical water oxidation waste destruction unit

International Nuclear Information System (INIS)

McFarland, R.D.; Brewer, G.R.; Rofer, C.K.

1991-12-01

Supercritical water oxidation (SCWO) is the destruction of hazardous waste by oxidation in the presence of water at temperatures and pressures above its critical point. A 1 gal/h SCWO waste destruction unit (WDU) has been designed, built, and operated at Los Alamos National Laboratory. This unit is transportable and is intended to demonstrate the SCWO technology on wastes at Department of Energy sites. This report describes the design of the WDU and the preliminary testing phase leading to demonstration

Decontamination of uranium-contaminated waste oil using supercritical fluid and nitric acid

International Nuclear Information System (INIS)

Sung, J.; Kim, J.; Lee, Y.; Seol, J.; Ryu, J.; Park, K.

2011-01-01

The waste oil used in nuclear fuel processing is contaminated with uranium because of its contact with materials or environments containing uranium. Under current law, waste oil that has been contaminated with uranium is very difficult to dispose of at a radioactive waste disposal site. To dispose of the uranium-contaminated waste oil, the uranium was separated from the contaminated waste oil. Supercritical R-22 is an excellent solvent for extracting clean oil from uranium-contaminated waste oil. The critical temperature of R-22 is 96.15 deg. C and the critical pressure is 49.9 bar. In this study, a process to remove uranium from the uranium-contaminated waste oil using supercritical R-22 was developed. The waste oil has a small amount of additives containing N, S or P, such as amines, dithiocarbamates and dialkyldithiophosphates. It seems that these organic additives form uranium-combined compounds. For this reason, dissolution of uranium from the uranium-combined compounds using nitric acid was needed. The efficiency of the removal of uranium from the uranium-contaminated waste oil using supercritical R-22 extraction and nitric acid treatment was determined. (authors)

Titania aerogel prepared by low temperature supercritical drying

Czech Academy of Sciences Publication Activity Database

Štengl, Václav; Bakardjieva, Snejana; Šubrt, Jan; Szatmáry, Lórant

2006-01-01

Roč. 91, 1-3 (2006), s. 1-6 ISSN 1387-1811 R&D Projects: GA MŠk(CZ) 1M0577 Institutional research plan: CEZ:AV0Z40320502 Keywords : aerogels * titanium oxide * supercritical drying Subject RIV: CA - Inorganic Chemistry Impact factor: 2.796, year: 2006

Supercritical fluid extraction of γ-Pyrones from Ammi visnaga L. fruits

Directory of Open Access Journals (Sweden)

Mokhtar Bishr

2018-06-01

Full Text Available Extraction with supercritical fluid technique has proved to be effective in many applications including extraction and separation of various active principals from medicinal plants. It was used due to its advantages especially safety, specificity, selectivity and ease of component recovery.Ammi visnaga, L. belongs to the family Apiaceae. The fruits are used specifically for the treatment of kidney stones depending on its γ-Pyrones (mainly khellin and visnagin [2]. The supercritical fluid extraction technique of khellin and visnagin was investigated and the operating conditions for their extraction were optimized. The effect of different pressure (150, 200, 300, 400 and 500 bars, temperature (35, 40, 45, 50 and 55 °C, and particle sizes of the raw material (0.5, 1, 1.4 mm and entire fruits on the extract yield was studied under dynamic conditions for extraction for a run time of 90 min. Optimum supercritical extraction condition was found to be 200 bars at 45 °C and optimum particle size was found to be 1.4 mm. The yield is yellowish white bitter powder and measures 1.74% w/w relative to the dried weight of the fruits containing 38.414% w/w average γ-Pyrones content of which 29.4%w/w khellin, and 9.014%w/w visnagin.The obtained extracts were analyzed by reversed phase HPLC. Keywords: Ammi visnaga fruits, γ-Pyrones (khellin and visnagin, Supercritical fluid extraction and HPLC

Hydrogen production from high moisture content biomass in supercritical water

Energy Technology Data Exchange (ETDEWEB)

Antal, M.J. Jr.; Xu, X. [Univ. of Hawaii, Honolulu, HI (United States). Hawaii Natural Energy Inst.

1998-08-01

By mixing wood sawdust with a corn starch gel, a viscous paste can be produced that is easily delivered to a supercritical flow reactor by means of a cement pump. Mixtures of about 10 wt% wood sawdust with 3.65 wt% starch are employed in this work, which the authors estimate to cost about $0.043 per lb. Significant reductions in feed cost can be achieved by increasing the wood sawdust loading, but such an increase may require a more complex pump. When this feed is rapidly heated in a tubular flow reactor at pressures above the critical pressure of water (22 MPa), the sawdust paste vaporizes without the formation of char. A packed bed of carbon catalyst in the reactor operating at about 650 C causes the tarry vapors to react with water, producing hydrogen, carbon dioxide, and some methane with a trace of carbon monoxide. The temperature and history of the reactor`s wall influence the hydrogen-methane product equilibrium by catalyzing the methane steam reforming reaction. The water effluent from the reactor is clean. Other biomass feedstocks, such as the waste product of biodiesel production, behave similarly. Unfortunately, sewage sludge does not evidence favorable gasification characteristics and is not a promising feedstock for supercritical water gasification.

High Temperature Heat Exchanger Design and Fabrication for Systems with Large Pressure Differentials

Energy Technology Data Exchange (ETDEWEB)

Chordia, Lalit [Thar Energy, LLC, Pittsburgh, PA (United States); Portnoff, Marc A. [Thar Energy, LLC, Pittsburgh, PA (United States); Green, Ed [Thar Energy, LLC, Pittsburgh, PA (United States)

2017-03-31

The project’s main purpose was to design, build and test a compact heat exchanger for supercritical carbon dioxide (sCO₂) power cycle recuperators. The compact recuperator is required to operate at high temperature and high pressure differentials, 169 bar (~2,500 psi), between streams of sCO₂. Additional project tasks included building a hot air-to-sCO₂ Heater heat exchanger (HX) and design, build and operate a test loop to characterize the recuperator and heater heat exchangers. A novel counter-current microtube recuperator was built to meet the high temperature high differential pressure criteria and tested. The compact HX design also incorporated a number of features that optimize material use, improved reliability and reduced cost. The air-to-sCO₂ Heater HX utilized a cross flow, counter-current, micro-tubular design. This compact HX design was incorporated into the test loop and exceeded design expectations. The test loop design to characterize the prototype Brayton power cycle HXs was assembled, commissioned and operated during the program. Both the prototype recuperator and Heater HXs were characterized. Measured results for the recuperator confirmed the predictions of the heat transfer models developed during the project. Heater HX data analysis is ongoing.

Microencapsulation of fish oil using supercritical antisolvent process

Directory of Open Access Journals (Sweden)

Fahim Tamzeedul Karim

2017-07-01

Full Text Available In order to improve the encapsulation process, a newly supercritical antisolvent process was developed to encapsulate fish oil using hydroxypropyl methyl cellulose as a polymer. Three factors, namely, temperature, pressure, and feed emulsion rate were optimized using response surface methodology. The suitability of the model for predicting the optimum response value was evaluated at the conditions of temperature at 60°C, pressure at 150 bar, and feed rate at 1.36 mL/min. At the optimum conditions, particle size of 58.35 μm was obtained. The surface morphology of the micronized fish oil was also evaluated using field emission scanning electron microscopy where it showed that particles formed spherical structures with no internal voids. Moreover, in vitro release of oil showed that there are significant differences of release percentage of oil between the formulations and the results proved that there was a significant decrease in the in vitro release of oil from the powder when the polymer concentration was high.

Microencapsulation of fish oil using supercritical antisolvent process.

Science.gov (United States)

Karim, Fahim Tamzeedul; Ghafoor, Kashif; Ferdosh, Sahena; Al-Juhaimi, Fahad; Ali, Eaqub; Yunus, Kamaruzzaman Bin; Hamed, Mir Hoseini; Islam, Ashraful; Asif, Mohammad; Sarker, Mohammed Zaidul Islam

2017-07-01

In order to improve the encapsulation process, a newly supercritical antisolvent process was developed to encapsulate fish oil using hydroxypropyl methyl cellulose as a polymer. Three factors, namely, temperature, pressure, and feed emulsion rate were optimized using response surface methodology. The suitability of the model for predicting the optimum response value was evaluated at the conditions of temperature at 60°C, pressure at 150 bar, and feed rate at 1.36 mL/min. At the optimum conditions, particle size of 58.35 μm was obtained. The surface morphology of the micronized fish oil was also evaluated using field emission scanning electron microscopy where it showed that particles formed spherical structures with no internal voids. Moreover, in vitro release of oil showed that there are significant differences of release percentage of oil between the formulations and the results proved that there was a significant decrease in the in vitro release of oil from the powder when the polymer concentration was high. Copyright © 2017. Published by Elsevier B.V.

Supercritical heat transfer phenomena in nuclear system

International Nuclear Information System (INIS)

Seo, Kyoung Woo; Kim, Moo Hwan; Anderson, Mark H.; Corradini, Michael L.

2005-01-01

A supercritical water (SCW) power cycle has been considered as one of the viable candidates for advanced fission reactor designs. However, the dramatic variation of thermo-physical properties with a modest change of temperature near the pseudo-critical point make existing heat transfer correlations such as the Dittus-Boelter correlation not suitably accurate to calculate the heat transfer in supercritical fluid. Several other correlations have also been suggested but none of them are able to predict the heat transfer over a parameter range, needed for reactor thermal-hydraulics simulation and design. This has prompted additional research to understand the characteristic of supercritical fluid heat transfer

Nucleation of super-critical carbon dioxide in a venturi nozzle

Energy Technology Data Exchange (ETDEWEB)

Jarrahbashi, D., E-mail: dorrin.jarrahbashi@me.gatech.edu; Pidaparti, S.R.; Ranjan, D.

2016-12-15

Highlights: • Nucleation of S-CO{sub 2} in a nozzle near critical point has been computationally studied. • The nucleation behavior is very sensitive to the inlet pressure and temperature. • After nucleation, high liquid-content two-phase mixture near wall travels downstream. - Abstract: Pressure reduction at the entrance of the compressor in supercritical CO{sub 2} Brayton cycles may cause nucleation and create a mixture of vapor and liquid droplets due to operation near the saturation conditions. Transient behavior of the flow after nucleation may cause serious issues in operation of the cycle and degrade the materials used in the design. The nucleation behavior of supercritical carbon-dioxide inside a venturi nozzle near the critical point is computationally studied. A transient compressible 3D Navier–Stokes solver, coupled with continuity, and energy equations have been implemented. In order to expedite the simulations, Fluid property Interpolation Tables (FIT) based on a piecewise biquintic spline interpolation of Helmholtz energy have been integrated with OpenFOAM to model S-CO{sub 2} properties. The mass fraction of vapor created in the venturi nozzle has been calculated using homogeneous equilibrium model (HEM). Nucleation behavior has been shown to be very sensitive to the inlet pressure, inlet temperature, and flow rate. The flow conditions that led to nucleation were identified. Nucleation was observed in the throat area and divergent section of the nozzle for mass flow rates from 0.050 kg/s to 0.065 kg/s, inlet pressure from 7.8 to 7.4 MPa for fixed exit pressure equal to 7.28 MPa. The inception of high-vapor-content nucleation was first observed in the throat area away from the side walls that remained confined to the throat region in later times. However, near the walls, a high liquid-content two-phase region was detected, first in the divergent section. At later times, the two-phase region was convected downstream toward the nozzle exit

Multipoint Pressure and Temperature Sensing Fiber Optic Cable for Monitoring CO₂ Sequestration

Energy Technology Data Exchange (ETDEWEB)

Challener, William [General Electric Company, Niskayuna, NY (United States)

2015-02-10

This report describes the work completed on contract DE-FE0010116. The goal of this two year project was to develop and demonstrate in the laboratory a highly accurate multi-point pressure measurement fiber optic cable based on MEMS pressure sensors suitable for downhole deployment in a CO₂ sequestration well. The sensor interrogator was also to be demonstrated in a remote monitoring system and environmental testing was to be completed to indicate its downhole survivability over a lengthy period of time (e.g., 20 years). An interrogator system based on a pulsed laser excitation was shown to be capable of multiple (potentially 100+) simultaneous sensor measurements. Two sensors packages were completed and spliced in a cable onto the same fiber and measured. One sensor package was subsequently measured at high temperatures and pressures in supercritical CO₂, while the other package was measured prior and after being subjected to high torque stresses to mimic downhole deployment. The environmental and stress tests indicated areas in which the package design should be further improved.

β-Sitosterol: Supercritical Carbon Dioxide Extraction from Sea Buckthorn (Hippophae rhamnoides L. Seeds

Directory of Open Access Journals (Sweden)

Marie Sajfrtová

2010-04-01

Full Text Available Supercritical fluid extraction represents an efficient and environmentally friendly technique for isolation of phytosterols from different plant sources. Sea buckthorn (Hippophae rhamnoides L. seeds were extracted with supercritical carbon dioxide at pressures ranging from 15–60 MPa and temperatures of 40-80 °C. Oil and β-sitosterol yields were measured in the extraction course and compared with Soxhlet extraction with hexane. The average yield of β-sitosterol was 0.31 mg/g of seeds. The maximum concentration of β-sitosterol in the extract, 0.5% w/w, was achieved at 15 MPa, 40 °C, and a carbon dioxide consumption of 50 g/g of seeds. The extraction rate was maximal at 60 MPa and 40 °C. Both β-sitosterol yield and its concentration in the extract obtained with hexane were lower than with carbon dioxide.

β-Sitosterol: Supercritical Carbon Dioxide Extraction from Sea Buckthorn (Hippophae rhamnoides L.) Seeds

Science.gov (United States)

Sajfrtová, Marie; Ličková, Ivana; Wimmerová, Martina; Sovová, Helena; Wimmer, Zdeněk

2010-01-01

Supercritical fluid extraction represents an efficient and environmentally friendly technique for isolation of phytosterols from different plant sources. Sea buckthorn (Hippophae rhamnoides L.) seeds were extracted with supercritical carbon dioxide at pressures ranging from 15–60 MPa and temperatures of 40–80 °C. Oil and β-sitosterol yields were measured in the extraction course and compared with Soxhlet extraction with hexane. The average yield of β-sitosterol was 0.31 mg/g of seeds. The maximum concentration of β-sitosterol in the extract, 0.5% w/w, was achieved at 15 MPa, 40 °C, and a carbon dioxide consumption of 50 g/g of seeds. The extraction rate was maximal at 60 MPa and 40 °C. Both β-sitosterol yield and its concentration in the extract obtained with hexane were lower than with carbon dioxide. PMID:20480045

Enhanced arrangement for recuperators in supercritical CO{sub 2} Brayton power cycle for energy conversion in fusion reactors

Energy Technology Data Exchange (ETDEWEB)

Serrano, I.P.; Linares, J.I., E-mail: linares@dim.icai.upcomillas.es; Cantizano, A.; Moratilla, B.Y.

2014-10-15

Highlights: •We propose an enhanced power conversion system layout for a Model C fusion reactor. •Proposed layout is based on a modified recompression supercritical CO{sub 2} Brayton cycle. •New arrangement in recuperators regards to classical cycle is used. •High efficiency is achieved, comparable with the best obtained in complex solutions. -- Abstract: A domestic research program called TECNO{sub F}US was launched in Spain in 2009 to support technological developments related to a dual coolant breeding blanket concept for fusion reactors. This concept of blanket uses Helium (300 °C/400 °C) to cool part of it and a liquid metal (480 °C/700 °C) to cool the rest; it also includes high temperature (700 °C/800 °C) and medium temperature (566 °C/700 °C) Helium cooling circuits for divertor. This paper proposes a new layout of the classical recompression supercritical CO{sub 2} Brayton cycle which replaces one of the recuperators (the one with the highest temperature) by another which by-passes the low temperature blanket source. This arrangement allows reaching high turbine inlet temperatures (around 600 °C) with medium pressures (around 225 bar) and achieving high cycle efficiencies (close to 46.5%). So, the proposed cycle reveals as a promising design because it integrates all the available thermal sources in a compact layout achieving high efficiencies with the usual parameters prescribed in classical recompression supercritical CO{sub 2} Brayton cycles.

Experimental analysis on a novel solar collector system achieved by supercritical CO2 natural convection

International Nuclear Information System (INIS)

Chen, Lin; Zhang, Xin-Rong

2014-01-01

Highlights: • Supercritical CO 2 flow is proposed for natural circulation solar water heater system. • Experimental system established and consists of supercritical fluid high pressure side and water side. • Stable supercritical CO 2 natural convective flow is well induced and water heating process achieved. • Seasonal solar collector system efficiency above 60% achieved and optimization discussed. - Abstract: Solar collector has become a hot topic both in scientific research and engineering applications. Among the various applications, the hot water supply demand accounts for a large part of social energy consumption and has become one promising field. The present study deals with a novel solar thermal conversion and water heater system achieved by supercritical CO 2 natural circulation. Experimental systems are established and tested in Zhejiang Province (around N 30.0°, E 120.6°) of southeast China. The current system is designed to operate in the supercritical region, thus the system can be compactly made and achieve smooth high rate natural convective flow. During the tests, supercritical CO 2 pipe flow with Reynolds number higher than 6700 is found. The CO 2 fluid temperature in the heat exchanger can be as high as 80 °C and a stable supply of hot water above 45 °C is achieved. In the seasonal tests, relative high collector efficiency generally above 60.0% is obtained. Thermal and performance analysis is carried out with the experiment data. Comparisons between the present system and previous solar water heaters are also made in this paper

MODELING OF SUPERCRITICAL FLUID EXTRACTION KINETIC OF FLAXSEED OIL BY DIFFUSION CONTROL METHOD

Directory of Open Access Journals (Sweden)

Emir Zafer HOŞGÜN

2013-06-01

Full Text Available In this study, Flaxseed oil was extracted by Supercritical Carbondioxide Extraction, and extractionkinetics was modelled using diffusion controlled method.The effect of process parameters, such as pressure (20, 35, 55 MPa, temperature (323 and 343 K, and CO2 flow rate (1 and 3 L CO2 /min on the extraction yield and effective diffusivity (De was investigated. The effective diffusion coefficient varied between 2.4 x10-12 and 10.8 x10-12 m2s-1 for the entire range of experiments and increased with the pressure and flow rate. The model fitted well theexperimental data (ADD varied between 2.35 and 7.48%.

Mass transfer in supercritical fluids instancing selected fluids in supercritical carbon dioxide

Science.gov (United States)

Hu, Miao; Benning, Rainer; Delgado, Antonio; Ertunc, Oezguer

solvent -sub-critical CO2. The ex-periment pressure is reached by reducing the volume of the container above the critical pressure of the solvent. For nucleation the container is firstly filled with saturated mixture of solvent -supercritical CO2 and the sample, the experiment pressure is achieved by enlarging the volume of the container below the critical pressure of the solvent. During the experiments the pressure and temperature data are monitored and recorded. As a direct observation means a high speed camera is used, the visual changes inside are recorded through the windows integrated on the container. The experiments are carried out under three different initial conditions, namely with three start temperatures (313K, 333K and 353K), to cover the area from vicinity of the critical point. This research serves as a pilot project topic in cooperation with DLR, which has the ultimate aim of performing the experiments of mass transfer processes in a longtime microgravity facility (e.g. ISS) in order to further explore the influences and utilities of earth gravity on these basic transport processes.

Assessment of a general methodology for the analysis of natural circulation stability with water at supercritical pressure

International Nuclear Information System (INIS)

Debrah, K. S.

2014-07-01

To advance nuclear energy to meet future energy needs, the concept of Super Critical Water-Cooled Reactor (SCWR) as part or Generation IV (Gen IV) reactors was introduced with plans to deploy by 2030. Supercritical water-cooled reactors pose new challenges in stability and natural circulation phenomena at supercritical pressures because of the strong variability of thermodynamic and thermo-physical properties. ln this research, included in the frame work of the International Atomic Energy Agency (lAEA) fellowship and Coordinated Research Project (CRP) on H eat transfer Behavior and Thermo hydraulics Codes Testing for SCWRs , the natural circulation H 2 O experimental data at supercritical pressures of 25 MPa obtained at the China Institute of Atomic Energy (CIAE) of China, was used to evaluate the predictions of different system codes: RELAP5/MOD3.3, STAR-CCM+ as well as three (3) different and independent developed in-house codes (Ishii-sup loop, NCLoop T ran and NCLoop L ine). Stability analyses of an idealized loop (loop equivalent to CIAE natural circulation loop) of uniform diameter equivalent to the CIAE natural circulation loop at 25 MPa was performed using RELAP5 and an in-house code (Ishii-sup Loop). It was found for both RELAP and Ishii-sup Loop that, when heat structures are accounted for in models equipped with heat transfer and friction correlations for 'normal' fluids, the comparison with experimental data is not completely satisfactory because the observed experimental oscillations were delayed in simulation. It has also been found that the stability margin was slightly earlier than the peak of the flow rate-power curve at a given inlet enthalpy. Results from STAR-CCM+ was also compared with results obtained with RELAP5 and the in-house code of NCLoop. Even though STAR-CCM+ predicted a lower flow rate than the in-house codes, all codes exhibited the ability to predict the instability and results from all codes compared favorably. Stability

Numerical Investigation on the Flow and Heat Transfer Characteristics of Supercritical Liquefied Natural Gas in an Airfoil Fin Printed Circuit Heat Exchanger

Directory of Open Access Journals (Sweden)

Zhongchao Zhao

2017-11-01

Full Text Available As a new kind of highly compact and efficient micro-channel heat exchanger, the printed circuit heat exchanger (PCHE is a promising candidate satisfying the heat exchange requirements of liquefied natural gas (LNG vaporization at low and high pressure. The effects of airfoil fin arrangement on heat transfer and flow resistance were numerically investigated using supercritical liquefied natural gas (LNG as working fluid. The thermal properties of supercritical LNG were tested by utilizing the REFPROF software database. Numerical simulations were performed using FLUENT. The inlet temperature of supercritical LNG was 121 K, and its pressure was 10.5 MPa. The reference mass flow rate of LNG was set as 1.22 g/s for the vertical pitch Lv = 1.67 mm and the staggered pitch Ls = 0 mm, with the Reynolds number of about 3750. The SST k-ω model was selected and verified by comparing with the experimental data using supercritical liquid nitrogen as cold fluid. The airfoil fin PCHE had better thermal-hydraulic performance than that of the straight channel PCHE. Moreover, the airfoil fins with staggered arrangement displayed better thermal performance than that of the fins with parallel arrangement. The thermal-hydraulic performance of airfoil fin PCHE was improved with increasing Ls and Lv. Moreover, Lv affected the Nusselt number and pressure drop of airfoil fin PCHE more obviously. In conclusion, a sparser staggered arrangement of fins showed a better thermal-hydraulic performance in airfoil fin PCHE.

Simulation of Oxygen Disintegration and Mixing With Hydrogen or Helium at Supercritical Pressure

Science.gov (United States)

Bellan, Josette; Taskinoglu, Ezgi

2012-01-01

The simulation of high-pressure turbulent flows, where the pressure, p, is larger than the critical value, p(sub c), for the species under consideration, is relevant to a wide array of propulsion systems, e.g. gas turbine, diesel, and liquid rocket engines. Most turbulence models, however, have been developed for atmospheric-p turbulent flows. The difference between atmospheric-p and supercritical-p turbulence is that, in the former situation, the coupling between dynamics and thermodynamics is moderate to negligible, but for the latter it is very significant, and can dominate the flow characteristics. The reason for this stems from the mathematical form of the equation of state (EOS), which is the perfect-gas EOS in the former case, and the real-gas EOS in the latter case. For flows at supercritical pressure, p, the large eddy simulation (LES) equations consist of the differential conservation equations coupled with a real-gas EOS. The equations use transport properties that depend on the thermodynamic variables. Compared to previous LES models, the differential equations contain not only the subgrid scale (SGS) fluxes, but also new SGS terms, each denoted as a correction. These additional terms, typically assumed null for atmospheric pressure flows, stem from filtering the differential governing equations, and represent differences between a filtered term and the same term computed as a function of the filtered flow field. In particular, the energy equation contains a heat-flux correction (q-correction) that is the difference between the filtered divergence of the heat flux and the divergence of the heat flux computed as a function of the filtered flow field. In a previous study, there was only partial success in modeling the q-correction term, but in this innovation, success has been achieved by using a different modeling approach. This analysis, based on a temporal mixing layer Direct Numerical Simulation database, shows that the focus in modeling the q

SUPERCRITICAL FLUID EXTRACTION OF POLYCYCLIC AROMATIC HYDROCARBON MIXTURES FROM CONTAMINATED SOILS

Science.gov (United States)

Highly contaminated (with PAHs) topsoils were extracted with supercritical CO2 to determine the feasibility and mechanism of supercritical fluid extraction (SFE). Effect of SCF density, temperature, cosolvent type and amount, and of slurrying the soil with water were ...

Effect of various experimental parameters on the swelling and supercritical extraction properties of lignite

Energy Technology Data Exchange (ETDEWEB)

Hacimehmetoglu, S.; Sinag, A.; Tekes, A.T.; Misirlioglu, Z.; Canel, M. [Ankara University, Ankara (Turkey). Faculty of Science

2007-07-01

The original lignite sample, the samples swollen in dimethylsulfoxide (DMSO), dimethylformamide (DMF), pyridine, tetrahydrofuran (THF), acetone, ethylenediamine (EDA), N-methyl-2-pyrrolidone (NMP), tetrabutylammonium hydroxide (TBAH), the samples impregnated by ZnCl{sub 2} as catalyst and the samples both swollen in the solvents and impregnated by ZnCl{sub 2} were subjected to the supercritical toluene extraction and the effects of temperature, pressure, pre-swelling procedure, hydrogen donor solvent (tetralin), and catalyst on the extract yields were investigated.

Feasibility analysis of the modified ATHLET code for supercritical water cooled systems

Energy Technology Data Exchange (ETDEWEB)

Zhou Chong, E-mail: ch.zhou@sjtu.edu.cn [School of Nuclear Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Institute of Fusion and Reactor Technology, Karlsruhe Institute of Technology, Vincenz-Priessnitz-Str. 3, 76131 Karlsruhe (Germany); Yang Yanhua [School of Nuclear Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Cheng Xu [Institute of Fusion and Reactor Technology, Karlsruhe Institute of Technology, Vincenz-Priessnitz-Str. 3, 76131 Karlsruhe (Germany)

2012-09-15

Highlights: Black-Right-Pointing-Pointer Modification of system code ATHLET for supercritical water application. Black-Right-Pointing-Pointer Development and assessment of a heat transfer package for supercritical water. Black-Right-Pointing-Pointer Validation of the modified code at supercritical pressures with the theoretical point-hydraulics model and the SASC code. Black-Right-Pointing-Pointer Application of the modified code to LOCA analysis of a supercritical water cooled in-pile fuel qualification test loop. - Abstract: Since the existing thermal-hydraulic computer codes for light water reactors are not applicable to supercritical water cooled reactors (SCWRs) owing to the limitation of physical models and numerical treatments, the development of a reliable thermal-hydraulic computer code is very important to design analysis and safety assessment of SCWRs. Based on earlier modification of ATHLET for SCWR, a general interface is implemented to the code, which serves as the platform for information exchange between ATHLET and the external independent physical modules. A heat transfer package containing five correlations for supercritical water is connected to the ATHLET code through the interface. The correlations are assessed with experimental data. To verify the modified ATHLET code, the Edwards-O'Brian blow-down test is simulated. As first validation at supercritical pressures, a simplified supercritical water cooled loop is modeled and its stability behavior is analyzed. Results are compared with that of the theoretical model and SASC code in the reference and show good agreement. To evaluate its feasibility, the modified ATHLET code is applied to a supercritical water cooled in-pile fuel qualification test loop. Loss of coolant accidents (LOCAs) due to break of coolant supply lines are calculated for the loop. Sensitivity analysis of some safety system parameters is performed to get further knowledge about their influence on the function of the

Design of an efficient space constrained diffuser for supercritical CO2 turbines

Science.gov (United States)

Keep, Joshua A.; Head, Adam J.; Jahn, Ingo H.

2017-03-01

Radial inflow turbines are an arguably relevant architecture for energy extraction from ORC and supercritical CO 2 power cycles. At small scale, design constraints can prescribe high exit velocities for such turbines, which lead to high kinetic energy in the turbine exhaust stream. The inclusion of a suitable diffuser in a radial turbine system allows some exhaust kinetic energy to be recovered as static pressure, thereby ensuring efficient operation of the overall turbine system. In supercritical CO 2 Brayton cycles, the high turbine inlet pressure can lead to a sealing challenge if the rotor is supported from the rotor rear side, due to the seal operating at rotor inlet pressure. An alternative to this is a cantilevered layout with the rotor exit facing the bearing system. While such a layout is attractive for the sealing system, it limits the axial space claim of any diffuser. Previous studies into conical diffuser geometries for supercritical CO 2 have shown that in order to achieve optimal static pressure recovery, longer geometries of a shallower cone angle are necessitated when compared to air. A diffuser with a combined annular-radial arrangement is investigated as a means to package the aforementioned geometric characteristics into a limited space claim for a 100kW radial inflow turbine. Simulation results show that a diffuser of this design can attain static pressure rise coefficients greater than 0.88. This confirms that annular-radial diffusers are a viable design solution for supercritical CO2 radial inflow turbines, thus enabling an alternative cantilevered rotor layout.

Supercritical fluid extraction of ginger (Zingiber Officinale Var. Amarum) : Global yield and composition study

Science.gov (United States)

Fitriady, Muhammad Arifuddin; Sulaswatty, Anny; Agustian, Egi; Salahuddin, Aditama, Deska Prayoga Fauzi

2017-11-01

An experiment to observe the effect of temperature and time process in ginger rhizome-Supercritical Fluid Extraction (SFE) using CO2 as the solvent has been conducted. The ginger rhizome (Zingiber Officinale Var. Amarum) was washed, drained, sliced, sun-dried, and then stored in a sealed bag prior to usage. The temperature and time process variables are each 35, 40, 45°C and 2, 4, 6 hours respectively with the pressure variable are 3500, 4000, and 4500 psi. It is found that the highest yield (2.9%) was achieved using temperature of 40°C and pressure of 4500 psiwith the process time of 4 hours. However, using the curve-fitting method, it is suggested to use 42°C as the temperature and 5 hours, 7 minutes, and 30 seconds (5.125 Hours) as the time process to obtain the highest yield. The temperature changes will affect both solvent and vapor pressure of diluted compounds of the ginger which will influence the global yield and the composition of the extract. The three major components of the extract are curcumene, zingiberene, and β - sesquipellandrene,

Statistical correlations for thermophysical properties of Supercritical Argon (SCAR) used in cooling of futuristic High Temperature Superconducting (HTS) cables

International Nuclear Information System (INIS)

Kalsia, Mohit; Dondapati, Raja Sekhar; Usurumarti, Preeti Rao

2017-01-01

Highlights: • The developed correlations can be integrated into thermohydraulic analysis of HTS cables. • This work also explains the phenomenon of flow with less pumping power and maximum heat transfer in HTS cables. • Pumping power required to circulate the SCAR for cooling of HTS cables would be significantly lower. • For Hg-based high temperature superconductors (T_c > 134 K), SCAR found to be a suitable coolant. - Abstract: High Temperature Superconducting (HTS) cables are emerging as an alternative to conventional cables in efficient power transmission. However, these HTS cables require cooling below the critical temperature of superconductors used to transmit larger currents. With the invention of high temperature superconductors whose critical temperatures are up to 134 K (Hg based), it is a great challenge to identify a suitable coolant which can carry away the heating load on the superconductors. In order to accomplish such challenge, an attempt has been made in the present work to propose supercritical Argon (SCAR) as the alternative to cool the HTS cables. Further, a statistical correlation has been developed for the thermophysical properties such as density, viscosity, specific heat and thermal conductivity of SCAR. In addition, the accuracy of developed correlations is established with the help of few statistical parameters and validated with standard database available in the literature. These temperature dependent accurate correlations are useful in predicting the pressure drop and heat transfer behaviour in HTS cables using numerical or computational techniques. In recent times, with the sophistication of computer technology, solving of various complex transport equations along with the turbulence models became popular and hence the developed correlations would benefit the technological community. It is observed that, a decrease in pressure, density and viscosity are found to be decreasing whereas the thermal conductivity and specific heat

Statistical correlations for thermophysical properties of Supercritical Argon (SCAR) used in cooling of futuristic High Temperature Superconducting (HTS) cables

Energy Technology Data Exchange (ETDEWEB)

Kalsia, Mohit [School of Mechanical Engineering, Lovely Professional University, Phagwara, 144 401 (India); Dondapati, Raja Sekhar, E-mail: drsekhar@ieee.org [School of Mechanical Engineering, Lovely Professional University, Phagwara, 144 401 (India); Usurumarti, Preeti Rao [Department of Mechanical Engineering, PVK Institute of Technology, Anantpur, 515 001 (India)

2017-05-15

Highlights: • The developed correlations can be integrated into thermohydraulic analysis of HTS cables. • This work also explains the phenomenon of flow with less pumping power and maximum heat transfer in HTS cables. • Pumping power required to circulate the SCAR for cooling of HTS cables would be significantly lower. • For Hg-based high temperature superconductors (T{sub c} > 134 K), SCAR found to be a suitable coolant. - Abstract: High Temperature Superconducting (HTS) cables are emerging as an alternative to conventional cables in efficient power transmission. However, these HTS cables require cooling below the critical temperature of superconductors used to transmit larger currents. With the invention of high temperature superconductors whose critical temperatures are up to 134 K (Hg based), it is a great challenge to identify a suitable coolant which can carry away the heating load on the superconductors. In order to accomplish such challenge, an attempt has been made in the present work to propose supercritical Argon (SCAR) as the alternative to cool the HTS cables. Further, a statistical correlation has been developed for the thermophysical properties such as density, viscosity, specific heat and thermal conductivity of SCAR. In addition, the accuracy of developed correlations is established with the help of few statistical parameters and validated with standard database available in the literature. These temperature dependent accurate correlations are useful in predicting the pressure drop and heat transfer behaviour in HTS cables using numerical or computational techniques. In recent times, with the sophistication of computer technology, solving of various complex transport equations along with the turbulence models became popular and hence the developed correlations would benefit the technological community. It is observed that, a decrease in pressure, density and viscosity are found to be decreasing whereas the thermal conductivity and specific

Safety study of an experimental apparatus for extraction with supercritical CO2

Directory of Open Access Journals (Sweden)

V. B. Soares

2012-09-01

Full Text Available During the process of supercritical CO2 extraction it is necessary to use high pressures in the procedure. The explosion of a pressure vessel can be harmful to people and cause serious damage to the environment. The aim of this study is to investigate the probability of death and injury in a laboratory unit for supercritical fluid extraction in the case of an explosion of the extractor vessel. The procedure is explained via a case study involving fatty acid extraction from vegetable oils with carbon dioxide above its supercritical conditions and under optimum operating conditions. According to the results, more importance should be given to the use of a protective headset because the probability of eardrum injury is superior to the probability of death from lung injury.

Study on the possibility of supercritical fluid extraction for reprocessing of spent nuclear fuel from high temperature gas-cooled reactor

International Nuclear Information System (INIS)

Duan Wuhua; Zhu Liyang; Zhu Yongjun; Xu Jingming

2011-01-01

International interest in high temperature gas-cooled reactor (HTGR) has been increasing in recent years. It is important to study on reprocessing of spent nuclear fuel from HTGR for recovery of nuclear resource and reduction of nuclear waste. Treatment of UO 2 pellets for preparing fuel elements of the 10 MW high temperature gas-cooled reactor (HTR-10) using supercritical fluid extraction was investigated. UO 2 pellets are difficult to be directly dissolved and extracted with TBP-HNO 3 complex in supercritical CO 2 (SC-CO 2 ), and the extraction efficiency is only about 7% under experimental conditions. UO 2 pellets are also difficult to be converted completely into nitrate with N 2 O 4 . When UO 2 pellets break spontaneously into U 3 O 8 powders with particle size below 100 μm under O 2 flow and 600degc, the extraction efficiency of U 3 O 8 powders with TBP-HNO 3 complex in SC-CO 2 can reach more than 98%. U 3 O 8 powders are easy to be completely converted into nitrate with N 2 O 4 . The extraction efficiency of the nitrate product with TBP in SC-CO 2 can reach more than 99%. So it has a potential prospect that application of supercritical fluid extraction in reprocessing of spent nuclear fuel from HTGR. (author)

Supercritical water oxidation treatment of textile sludge.

Science.gov (United States)

Zhang, Jie; Wang, Shuzhong; Li, Yanhui; Lu, Jinling; Chen, Senlin; Luo, XingQi

2017-08-01

In this work, we studied the supercritical water oxidation (SCWO) of the textile sludge, the hydrothermal conversion of typical textile compounds and the corrosion properties of stainless steel 316. Moreover, the influence mechanisms of NaOH during these related processes were explored. The results show that decomposition efficiency for organic matter in liquid phase of the textile sludge was improved with the increment of reaction temperature or oxidation coefficient. However, the organic substance in solid phase can be oxidized completely in supercritical water. Serious coking occurred during the high pressure water at 250-450°C for the Reactive Orange 7, while at 300 and 350°C for the polyvinyl alcohol. The addition of NaOH not only accelerated the destruction of organic contaminants in the SCWO reactor, but effectively inhibited the dehydration conversion of textile compounds during the preheating process, which was favorable for the treatment system of textile sludge. The corrosion experiment results indicate that the stainless steel 316 could be competent for the body materials of the reactor and the heat exchangers. Furthermore, there was prominent enhancement of sodium hydroxide for the corrosion resistance of 316 in subcritical water. On the contrary the effect was almost none during SCWO.

Comparison of the Behaviour of Polymers in Supercritical Fluids and Organic Solvents Via Small Angle Neutron Scattering

International Nuclear Information System (INIS)

Melnichenko, Y.B.; Kiran, E.; Heath, K.D.; Salaniwal, S.; Cochran, H.D.; Stamm, M.; Van Hook, W.A.; Wignall, G.D.

1999-01-01

Small-angle neutron scattering has been used to study the effect of temperature and pressure on the phase behavior of semidilute solutions of polymers dissolved in organic and supercritical solvents. Above the theta temperature (To), these systems exhibit a ''good solvent'' domain, where the molecules expand beyond the unperturbed dimensions in both organic solvents and in COZ. However, this transition can be made to occur at a critical ''theta pressure'' (PO) in CO2 and this represents a new concept in the physics of polymer-solvent systems. For T < To, and P < Po, the system enters the ''poor solvent'' domain where diverging concentration fluctuations prevent the chains from collapsing and allow them to maintain their unperturbed dimensions

Improvement of supercritical CO2 Brayton cycle using binary gas mixture

International Nuclear Information System (INIS)

Jeong, Woo Seok

2011-02-01

A Sodium-cooled Fast Reactor (SFR) is one of the strongest candidates for the next generation nuclear reactor. However, the conventional design of a SFR concept with an indirect Rankine cycle is inevitably subjected to a sodium-water reaction. To prevent hazardous situation caused by sodium-water reaction, the SFR with Brayton cycle using Supercritical Carbon dioxide (S-CO 2 cycle) as a working fluid can be an alternative approach. The S-CO 2 Brayton cycle is more sensitive to the critical point of working fluids than other Brayton cycles. This is because compressor work significantly decreases at slightly above the critical point due to high density near the boundary between the supercritical state and the subcritical state. For this reason, the minimum temperature and pressure of cycle are just above the CO 2 critical point. The critical point acts as a limitation of the lowest operating condition of the cycle. In general, lowering the rejection temperature of a thermodynamic cycle increases the efficiency and thus, changing the critical point of CO 2 can result in an improvement of the total cycle efficiency with the same cycle layout. Modifying the critical point of the working fluid can be done by adding other gases to CO 2 . The direction and range of the CO 2 critical point variation depends on the mixed component and its amount. In particular, chemical reactivity of the gas mixture itself and the gas mixture with sodium at high temperatures are of interest. To modify the critical point of the working fluid, several gases were chosen as candidates by which chemical stability with sodium within the interested range of cycle operating condition was assured: CO 2 was mixed with N 2 , O 2 , He, Ar and Xe. To evaluate the effect of shifting the critical point and changes in the properties of the S-CO 2 Brayton cycle, a supercritical Brayton cycle analysis code connected with the REFPROP program from the NIST was developed. The developed code is for evaluating

Radiolytic and electron-transfer reactions in supercritical CO2

International Nuclear Information System (INIS)

Bartels, D. M.; Dimitrijevic, N. M.; Jonah, C. D.; Takahashi, K.

2000-01-01

Using supercritical fluids as solvents is useful for both practical and theoretical reasons. It has been proposed to use supercritical CO 2 as a solvent for synthesis because it eliminates the air pollution arising from other solvents. The properties of supercritical fluids can be easily varied with only modest changes in temperature and density, so they provide a way of testing theories of chemical reactions. It has also been proposed to use supercritical fluids for the treatment of hazardous mixed waste. For these reasons the authors have studied the production of radiolytic species in supercritical CO 2 and have measured their reactivity as a function of density. They have shown that the C 2 O 4 + is formed. They also have shown that the electron transfer reactions of dimethylaniline to C 2 O 4 + and CO 2 (e - ) to benzoquinone are diffusion controlled over a considerable density range

Numerical Study on the Heat Transfer of Carbon Dioxide in Horizontal Straight Tubes under Supercritical Pressure

Science.gov (United States)

Yang, Mei

2016-01-01

Cooling heat transfer of supercritical CO2 in horizontal straight tubes with wall is numerically investigated by using FLUENT. The results show that almost all models are able to present the trend of heat transfer qualitatively, and the stand k−ε with enhanced wall treatment model shows the best agreement with the experimental data, followed by LB low Re turbulence model. Then further studies are discussed on velocity, temperature and turbulence distributions. The parameters which are defined as the criterion of buoyancy effect on convection heat transfer are introduced to judge the condition of the fluid. The relationships among the inlet temperature, outlet temperature, the mass flow rate, the heat flux and the diameter are discussed and the difference between the cooling and heating of CO2 are compared. PMID:27458729

Numerical Study on the Heat Transfer of Carbon Dioxide in Horizontal Straight Tubes under Supercritical Pressure.

Directory of Open Access Journals (Sweden)

Mei Yang

Full Text Available Cooling heat transfer of supercritical CO2 in horizontal straight tubes with wall is numerically investigated by using FLUENT. The results show that almost all models are able to present the trend of heat transfer qualitatively, and the stand k-ε with enhanced wall treatment model shows the best agreement with the experimental data, followed by LB low Re turbulence model. Then further studies are discussed on velocity, temperature and turbulence distributions. The parameters which are defined as the criterion of buoyancy effect on convection heat transfer are introduced to judge the condition of the fluid. The relationships among the inlet temperature, outlet temperature, the mass flow rate, the heat flux and the diameter are discussed and the difference between the cooling and heating of CO2 are compared.

State of the art on the heat transfer experiments under supercritical pressure condition

International Nuclear Information System (INIS)

Kim, Hwan Yeol; Song, Chul Hwa

2003-07-01

The SCWR(Super-Critical Water cooled Reactor) is one of the six reactor candidates selected in the Gen-IV project which aims at the development of new reactors with enhanced economy and safety. The SCWR is considered to be a feasible concept of new nuclear power plant if the existing technologies developed in fossil fuel fired plant and LWR technologies together with additional research on several disciplines such as materials, water chemistry and safety. As KAERI takes part in the GIF(Generation IV Forum) for the Gen-IV project, domestic concerns about the SCWR have been recently increased. In order to establish a foundation for the development of SCWR, efforts should be concentrated on the conceptual design of systems and the associated key experiments as well. Heat transfer experiments, among others, under supercritical condition are required for the proper prediction of thermal hydraulic phenomena, which are essential for the thermal hydraulic designs of reactor core. Nevertheless, the experiments have not been performed in Korea yet. This report deals with fundamental surveys on the heat transfer experiments under supercritical conditions, which are required for the understanding of heat transfer characteristics for the thermal hydraulic designs of supercritical reactor core. Investigations on the physical properties of water and CO 2 showed that the physical properties such as density, specific heat, viscosity and thermal conductivity are significantly changed near the pseudo-critical points. The state of the art on the heat transfer characteristics in relation with heat transfer deterioration and heat transfer coefficient is briefly described. In addition, previous experiments with supercritical water as well as supercritical CO 2 and Freon used for an alternating fluid are presented

State of the art on the heat transfer experiments under supercritical pressure condition

Energy Technology Data Exchange (ETDEWEB)

Kim, Hwan Yeol; Song, Chul Hwa

2003-07-01

The SCWR(Super-Critical Water cooled Reactor) is one of the six reactor candidates selected in the Gen-IV project which aims at the development of new reactors with enhanced economy and safety. The SCWR is considered to be a feasible concept of new nuclear power plant if the existing technologies developed in fossil fuel fired plant and LWR technologies together with additional research on several disciplines such as materials, water chemistry and safety. As KAERI takes part in the GIF(Generation IV Forum) for the Gen-IV project, domestic concerns about the SCWR have been recently increased. In order to establish a foundation for the development of SCWR, efforts should be concentrated on the conceptual design of systems and the associated key experiments as well. Heat transfer experiments, among others, under supercritical condition are required for the proper prediction of thermal hydraulic phenomena, which are essential for the thermal hydraulic designs of reactor core. Nevertheless, the experiments have not been performed in Korea yet. This report deals with fundamental surveys on the heat transfer experiments under supercritical conditions, which are required for the understanding of heat transfer characteristics for the thermal hydraulic designs of supercritical reactor core. Investigations on the physical properties of water and CO{sub 2} showed that the physical properties such as density, specific heat, viscosity and thermal conductivity are significantly changed near the pseudo-critical points. The state of the art on the heat transfer characteristics in relation with heat transfer deterioration and heat transfer coefficient is briefly described. In addition, previous experiments with supercritical water as well as supercritical CO{sub 2} and Freon used for an alternating fluid are presented.

Supercritical impregnation of cinnamaldehyde into polylactic acid as a route to develop antibacterial food packaging materials.

Science.gov (United States)

Villegas, Carolina; Torres, Alejandra; Rios, Mauricio; Rojas, Adrián; Romero, Julio; de Dicastillo, Carol López; Valenzuela, Ximena; Galotto, María José; Guarda, Abel

2017-09-01

Supercritical impregnation was used to incorporate a natural compound with antibacterial activity into biopolymer-based films to develop active food packaging materials. Impregnation tests were carried out under two pressure conditions (9 and 12MPa), and three depressurization rates (0.1, 1 and 10MPamin -1 ) in a high-pressure cell at a constant temperature equal to 40°C. Cinnamaldehyde (Ci), a natural compound with proven antimicrobial activity, was successfully incorporated into poly(lactic acid) films (PLA) using supercritical carbon dioxide (scCO 2 ), with impregnation yields ranging from 8 to 13% w/w. Higher pressure and slower depressurization rate seem to favor the Ci impregnation. The incorporation of Ci improved thermal, structural and mechanical properties of the PLA films. Impregnated films were more flexible, less brittle and more resistant materials than neat PLA films. The tested samples showed strong antibacterial activity against the selected microorganisms. In summary, this study provides an innovative route to the development of antibacterial biodegradable materials, which could be used in a wide range of applications of active food packaging. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Effect of Pressure and Solvent on the Supercritical Fluid Chromatography Separation of Tocol Analogs in Palm Oil

Directory of Open Access Journals (Sweden)

Mei Han Ng

2017-08-01

Full Text Available There are six tocol analogs present in palm oil, namely α-tocopherol (α-T, α-tocomonoenol (α-T1, α-tocotrienol (α-T3, γ-tocotrienol (γ-T3, β-tocotrioenol (β-T3 and δ-tocotrienol (δ-T3. These analogs were difficult to separate chromatographically due to their similar structures, physical and chemical properties. This paper reports on the effect of pressure and injection solvent on the separation of the tocol analogs in palm oil. Supercritical CO2 modified with ethanol was used as the mobile phase. Both total elution time and resolution of the tocol analogs decreased with increased pressure. Ethanol as an injection solvent resulted in peak broadening of the analogs within the entire pressure range studied. Solvents with an eluent strength of 3.4 or less were more suitable for use as injecting solvents.

High Density Thermal Energy Storage with Supercritical Fluids

Science.gov (United States)

Ganapathi, Gani B.; Wirz, Richard

2012-01-01

A novel approach to storing thermal energy with supercritical fluids is being investigated, which if successful, promises to transform the way thermal energy is captured and utilized. The use of supercritical fluids allows cost-affordable high-density storage with a combination of latent heat and sensible heat in the two-phase as well as the supercritical state. This technology will enhance penetration of several thermal power generation applications and high temperature water for commercial use if the overall cost of the technology can be demonstrated to be lower than the current state-of-the-art molten salt using sodium nitrate and potassium nitrate eutectic mixtures.

Effects of Gravity on Supercritical Water Oxidation (SCWO) Processes

Science.gov (United States)

Hegde, Uday; Hicks, Michael