Isothermal Coefficient Research Articles

Hygrothermal Behaviour of Three Internal Retrofit Prototype Solutions

Although the application of internal insulation to existing perimeter walls poses significant challenges in terms of building physics and loss of habitable space, it is sometimes an inevitable choice because of practical or legislative constraints. Innovative solutions are then required to deliver satisfying performances and reduce nuisance to inhabitants of residential buildings in case they are going to remain in their flats during the retrofit works.Three systems for inner thermal retrofitting purposes have been designed and produced as prototypes. Two of them are composed by silica aerogel containing fibrous material: the first one is a rigid flat laminated panel, the second one is a rollable solution with a fabric finishing layer. The third insulating system is a perlite based board with a hydrophobic layer. All the materials composing the retrofit solutions have been characterized by means of laboratory tests in order to measure their main hygrothermal properties. In fact, some parameters are fundamental for determining the hygrothermal performance of the composite systems: thermal conductivity, at dry and wet state (moisture dependant), water vapour diffusion resistance factor, hygroscopic sorption at isotherm condition and water absorption coefficient. All those measured data were necessary for optimizing the solutions, guaranteeing energy efficiency and vapour open layers to systems that are intended for installation on existing walls.

Analysis of Selected Thermodynamic Derivative Properties of Natural Gas Pipeline Flow Model

The thermodynamic derivatives based on fundamentals thermodynamic space and physical parameters of natural gas influences other variables of pipeline systems such as pressure, temperature, velocity, density, gas compressibility, etc. These variables are crucial for gas pipeline system knowledge and its accurate operation. Fundamental parameters are derived such as Joule-Thomson (J-T) coefficient, isothermal throttling coefficient and isentropic coefficient. They influence gas flow when during the expansion of natural gas in the pipeline, the gas cools down due to the J-T effect and due to the interaction between pipeline system and its surroundings to the conditions at which gas is saturated by water vapour (dew point), and gas is not able to keep excess humidity and its condensation and gas hydrate formation will occur. The article deals with analyses of selected thermodynamic derivatives in the range of chosen temperatures and pressures and also non-isothermal steady-state flow model for pipeline is presented.

Measurement and analysis of feedback reactivity in the Monju restart core

The purpose of this study is to develop a feedback reactivity measurement technique in the Japanese prototype fast breeder reactor Monju and to validate calculation methodology to forecast the nuclear feedback phenomena. A feedback reactivity measurement technique has been developed based on a reactivity model featuring components that depend on the reactivity coefficients, denoted as reactor power (KR) and reactor vessel inlet temperature (Kin). This technique can precisely measure the two reactivity components simultaneously and was applied to the feedback reactivity experiment conducted in the Monju system start-up test in May 2010. A thorough evaluation considering all possible biases and uncertainties demonstrated that the reactivity coefficients can be evaluated with a measurement uncertainty smaller than 3%. The evaluated reactivity coefficients were simulated considering the temperature distribution in the core. The calculated and measured values of KR agreed within 1%, and the value of Kin was consistent with that reported in a previous isothermal temperature coefficient experiment. The measured and calculated fuel subassembly outlet temperatures also agreed well within 0.2°C, which supports the validity of the temperature calculation.

Removal of Cu(II) Ions from Aqueous Solutions by Adsorption onto Natural Bentonites

The removal of Cu (II) ions from aqueous solutions using the adsorption process onto natural Slovak bentonites from deposits Jelšový potok, Hliník nad Hronom and Lieskovec has been investigated in this study. The adsorption experiments were carried out under batch process with initial concentration Cu (II) ions, time and temperature as the variables. A flame atomic absorption spectrometer was used for measuring the copper concentration before and after adsorption. Adsorption was very fast at low coverage and equilibrium was approached within 30 min. The results best fitted the pseudo-second order kinetic model. Langmuir and Freundlich isotherms were applied and isotherm coefficients were computed. The Langmuir isotherm was found to fit better the experimental data measured for used bentonites. The Langmuir maximum adsorption capacity of the adsorbents was from 13.4 to 43.1 mg g−1. The effect of temperature on the equilibrium adsorption of copper from aqueous solution using natural bentonites was investigated at three different temperatures (293, 303 and 313 K). Thermodynamic parameters, such as standard free energy changes (ΔGo), standard enthalpy change (ΔHo) and standard entropy change (ΔSo), were calculated using adsorption equilibrium constant obtained from the Langmuir isotherm. The copper adsorption on bentonite was a spontaneous and endothermic process. The results suggested that natural bentonites are suitable as a adsorbent material for recovery and adsorption of Cu (II) ions from aqueous solutions. Comparing the measured results for used bentonites is evident that for the removal of Cu (II) ions from aqueous solutions is more suitable the bentonite from Jelšový potok.

Evaluation of a sequencing batch reactor sewage treatment rig for investigating the fate of radioactively labelled pharmaceuticals: Case study of propranolol

Pharmaceuticals are frequently detected in the aquatic environment, and have potentially damaging effects. Effluents from sewage treatment plants (STPs) are major sources of these substances. The use of sequencing batch reactor (SBR) STPs, involving cycling between aerobic and anoxic conditions to promote nitrification and denitrification, is increasing but these have yet to be understood in terms of removal of pharmaceutical residues. This study reports on the development of a laboratory rig to simulate a SBR. The rig was used to investigate the fate of radiolabelled propranolol. This is a commonly prescribed beta blocker, but with unresolved fate in STPs.The SBR rig (4.5 L) was operated on an 8 h batch cycle with settled sewage. Effective treatment was demonstrated, with clearly distinct treatment phases and evidence of nitrogen removal. Radiolabelled 14C-propranolol was dosed into both single (closed) and continuous (flow-through) simulations over 13 SBR cycles. Radioactivity in CO2 off-gas, biomass and liquid was monitored, along with the characteristics of the sewage. This allowed apparent rate constants and coefficients for biodegradation and solid:water partitioning to be determined.Extrapolation from off-gas radioactivity measurements in the single dose 4-d study suggested that propranolol fell outside the definitions of being readily biodegradable (DegT50 = 9.1 d; 60% biodegradation at 12.0 d). During continuous dosing, 63–72% of propranolol was removed in the rig, but less than 4% of dose recovered as 14CO2, suggesting that biodegradation was a minor process (Kbiol(M) L kg d−1 = 22–49) and that adsorption onto solids dominated, giving rise to accumulations within biomass during the 17 d solid retention time in the SBR. Estimations of adsorption isotherm coefficients were different depending on which of three generally accepted denominators representing sorption sites was used (mixed liquor suspended solids, reactor COD or mass of waste activated sludge).With further development and evaluation, the rig developed for simulating SBR processes has potential to be used for informing better environmental risk assessments for those pharmaceuticals showing ambiguous results in field fate studies.

Remediation of Rare Earth Element Pollutants by Sorption Process Using Organic Natural Sorbents.

The effects of the sorption of environmental applications by various source materials of natural organic matter, i.e., bone powder, was examined. Sorption capacities and subsequent rare earth element retention characteristics of all metals tested were markedly increased by ionic task-specific. In this study, the abilities of three models’ isotherms widely were used for the equilibrium sorption data: Langmuir, Freundlich and Redlich-Peterson. For all studied metal ions the maximum adsorption capacity is close to those experimentally determined. The characteristic parameters for each isotherm and related coefficients of determination have been determined. The experimental data achieved excellent fits within the following isotherms in the order: Langmuir > Redlich-Peterson > Freundlich, based on their coefficient of determination values. The bone powder has developed higher adsorption performance in the removal process of Nd(III), Eu(III), La(III) from aqueous solutions than in the case of the removal process of Cs(I), Sr(II) and Tl(I) from aqueous solutions. The described relationships provide direct experimental evidence that the sorption-desorption properties of bone powder are closely related to their degree of the type of the metal. The results suggest a potential for obtaining efficient and cost-effective engineered natural organic sorbents for environmental applications.

Phonons in YB6 and LaB6: Effects of temperature and pressure

Raman scattering by phonons in YB6 and LaB6 has been studied in wide temperature (8–800 K) and pressure (up to 10 GPa) ranges. Acoustic phonons in both hexaborides exhibit anomalous softening with a decrease in the temperature. The positive isothermal Gruneisen coefficient of these modes in YB6 appears to be an order of magnitude lower than the absolute value of the negative isobaric coefficient, which indicates the dominating role of temperature effects. The temperature shifts of the vibration frequencies of the B sublattice in YB6 caused by phonon interactions have the opposite sign and exceed the respective shifts in LaB6.

Development of a novel carbon paste sensor for determination of micromolar amounts of sulfaquinoxaline in pharmaceutical and biological samples

A potentiometric carbon paste sensor was fabricated for determination of sulfaquinoxaline (SQX) based on the use of ion-association complex of sulfaquinoxaline sodium with 2,3,5-triphenyltetrazolium chloride. The proposed sensor exhibited Nernstian slope of 58.4 ± 0.3 mV per decade for sulfaquinoxaline over a wide concentration range of 5.0 × 10(-6) to 1.0 × 10(-2)M, with a low detection limit of 3.0 × 10(-6)M. The sensor manifested advantages of fast response time, satisfactory reproducibility, long life time, high thermal stability and, most importantly, excellent selectivities for sulfaquinoxaline relative to a wide variety of common foreign inorganic cations, anions, sugars and amino acids. The sensor was successfully used for determination of sulfaquinoxaline in pharmaceutical solution, blood serum, urine and milk samples. The isothermal coefficient of the electrode was calculated by the investigation of temperature effects on the electrode potential response.

Monte Carlo Perturbation Analysis of Isothermal Temperature Reactivity Coefficient in Kyoto University Critical Assembly

Experiments on the isothermal temperature reactivity coefficient (ITRC) have been carried out at the light water–moderated core with or without a D2O tank in the Kyoto University Critical Assembly. The ITRC experiments are analyzed by a continuous-energy Monte Carlo (MC) neutron transport analysis code, McCARD. Through the temperature changes of H2O and D2O, effects of the coolant density changes in moderator and reflector regions and the microscopic cross-section variations on the ITRC are investigated by sensitivity analyses with the use of the MC adjoint-weighted perturbation method. An adjoint-weighted correlated sampling method for the stochastic mixing technique of cross-section libraries is devised to estimate the reactivity change from a perturbation of the thermal scattering cross sections due to the temperature change. From results of the MC perturbation analyses, it is clearly seen that the ITRCs of the two core configurations are dominated by a negative contribution of the number density change of hydrogen in the moderator region and a positive contribution of the thermal scattering cross-section change of hydrogen in the reflector region.

Modeling thermodynamic derivative properties of ionic liquids with ePC-SAFT

In this work, ePC-SAFT was extended to predict the second order thermodynamic derivative properties of pure ionic liquids (ILs), such as isothermal and isentropic compressibility coefficients, thermal pressure coefficient, heat capacities, speed of sound, thermal expansion coefficient and internal pressure. ePC-SAFT predictions were compared with available experimental data of imidazolium-based ILs. The pure-component ePC-SAFT parameters for the IL-cations [C2mim]+, [C4mim]+, [C6mim]+ and [C8mim]+, and IL-anions [BF4]−, [PF6]− and [Tf2N]− were taken from literature in order to predict the thermodynamic derivative properties. The pure-component ePC-SAFT parameters for the IL-cations [C3mim]+, [C5mim]+, [C7mim]+ and [C10mim]+ were predicted based on linear molecular-weight-dependent relations. These estimated ePC-SAFT parameters were verified by comparing so-predicted pure-IL density as well as predicted CO2 solubility in ILs with respective experimental data. Further, these parameters were used to predict the second order thermodynamic derivative properties. The comparison of model prediction with experimental data showed that ePC-SAFT predictions were reliable in a wide temperature and pressure range.

Analysis of equations of state for polymers

In the literature there are several studies comparing the accuracy of various models in describing the PvT behavior of polymers. However, most of these studies do not provide information about the quality of the estimated parameters or the sensitivity of the prediction of thermodynamic properties to the parameters of the equations. Furthermore, there are few studies exploring the prediction of thermal expansion and compression coefficients. Based on these observations, the objective of this study is to deepen the analysis of Tait, HH (Hartmann-Haque), MCM (modified cell model) and SHT (simplified hole theory) equations of state in predicting the PvT behavior of polymers, for both molten and solid states. The results showed that all equations of state provide an adequate description of the PvT behavior in the molten state, with low standard deviations in the estimation of parameters, adequate sensitivity of their parameters and plausible prediction of specific volume, thermal expansion and isothermal compression coefficients. In the solid state the Tait equation exhibited similar performance to the molten state, while HH showed satisfactory results for amorphous polymers and difficulty in adjusting the PvT curve for semicrystalline polymers.

Mechanism of pressure management by injecting nitrogen in casing annulus of deepwater wells

The influence factors of annular pressure buildup are analyzed, and the temperature and pressure characteristics of annulus trap medium are simulated for deepwater wells. The method of pressure management by injecting nitrogen in casing annulus is proposed based the experiment result. Limited by the well structure and subsea system, long casing annulus exists between technical casing and production casing and it is filled with water-based, synthetic based or oil-based drilling fluid. In the process of oil/gas test and production, the temperature of the trapped fluid rises significantly under the influence of the well-bore fluid and the trap pressure buildup appears because of liquid heat expansion. Experiments show that isothermal compressibility coefficient and thermal expansion coefficient are the key influencing factors for annulus pressure buildup. Trap pressure is very sensitive to the type of trapped medium (liquid, gas). Injecting 5%−20% volume fraction of nitrogen into the annulus can effectively control the annulus pressure build-up, and avoid casing collapse. Field practice shows that the method, convenient and highly reliable, can ensure the borehole safety during testing and production of deepwater oil and gas.

Performance analysis of a thermally regenerative electrochemical cycle for harvesting waste heat

The performance of a (TREC) thermally regenerative electrochemical cycle for harvesting waste heat has been investigated based on finite time analysis. The impacts of cell material and heat exchangers on the maximum power extracted and its corresponding efficiency have been analyzed. Results reveal that materials with larger isothermal coefficients, specific charge/discharge capacities, and lower internal resistances correspond to larger maximum power that can be extracted from them. If both power and efficiency are considered, materials with larger isothermal coefficients, specific charge/discharge capacities, appropriate internal resistances, and lower specific heats are more appealing. A better heat exchanger performance increases maximum power output; however, it does not guarantee higher efficiency. This work is expected to contribute in choosing appropriate materials and heat exchangers to improve the performance of TREC devices.

High-pressure (vapour + liquid) equilibria for ternary systems composed by {(E)-2-hexenal or hexanal + carbon dioxide + water}: Partition coefficient measurement

A new apparatus based on a static–analytic method assembled in this work was utilised to perform high-pressure (vapour+liquid) equilibria measurements of aqueous ternary systems. This work includes values of isothermal partition coefficients between CO2 and water of two apple aroma constituents, (E)-2-hexenal and hexanal. Additionally, this work reports new experimental (vapour+liquid) equilibria measurements for the ternary systems (CO2+(E)-2-hexenal+water) and (CO2+hexanal+water), at fixed liquid phase composition (600mg·kg−1), at temperatures of (313, 323 and 333)K and at pressures from (8 to 19)MPa. Vapour liquid interphase was checked and monitored visually for all the systems studied in this work. No liquid immiscibility was observed at the composition, temperatures and pressures studied. In order to suggest reasonable operation conditions for fractionation of aromas with dense carbon dioxide, partition coefficients of the aroma compounds between CO2 and water along with their separation factors from water were calculated. Partition coefficients of (E)-2-hexenal between CO2 and water were in the range of (6 to 91) and where found to be near six times higher than those of hexanal (9 to 17). Very high separation factors from water were observed (∼104) especially for (E)-2-hexenal. The highest separation factor, for both compounds, was found at a temperature of 313K and pressures from (12 to 14)MPa.

Correction to “Equilibrium Isotherm and Mass Transfer Coefficient for Adsorption of Pure Argon on Small Particles of Pelletized LiLSX Zeolite”

Correction to “Equilibrium Isotherm and Mass Transfer Coefficient for Adsorption of Pure Argon on Small Particles of Pelletized LiLSX Zeolite”

The AMMON experiment in EOLE zero power facility: a challenging program devoted to the neutron and photon physics

The AMMON integral experiment was carried out in the EOLE critical mock-up at CEA Cadarache. It has been dedicated to the analysis of the Jules Horowitz Reactor (JHR) neutron and photon physics and has a very specific design in comparison with previous cores (MISTRAL, FUBILA, etc.) consisting in the loading of UOX or MOX fuel pins in EOLE. The core configurations consisted of an experimental zone of six or seven JHR-type assemblies with U3Si2–Al 27% 235U enriched curved fuel plates, surrounded by a driver zone with enough standard pressurized water reactor (PWR) UOX fuel pins to reach criticality. Five main configurations have been studied during this three-year ambitious program.The purpose of this paper is to synthesize the main features of this program in terms of experimental methods and associated uncertainties. Almost all the measurements have been analyzed with TRIPOLI-4® Monte Carlo reference calculations, using the JEFF-3.1.1 nuclear data library; this paper gives examples of the analysis of the critical states studied in the experiment as well as the analysis of the isothermal temperature coefficient.

The reduced bioavailability of copper by nano-TiO₂ attenuates the toxicity to Microcystis aeruginosa.

Nano-TiO2 is a widely applied nanoparticle (NPs) and co-exists with other pollutants such as heavy metals in aquatic environments. However, minimal knowledge is available concerning the ecological risk of these mixtures. Our study reported that at no toxic effect concentrations of TiO2 nanoparticles (5 mg/L), the toxicity of Cu ions to the algae Microcystis aeruginosa was significantly attenuated by TiO2 nanoparticles. Specifically, the concentration of photosynthetic pigments (i.e., concentration of Chla) increased 37% when comparing only Cu ions treated and the nano-TiO2-Cu co-incubation. The levels of phycocyanin (PC), allophycocyanin (APC), phycoerythrin (PE), and phycobiliprotein (PBPs) were also recovered at levels ranging from 23 to 35% after 72 h. For oxidative indexes, the decreased activities of the superoxide dismutase (SOD), peroxidase (POD) content, and malondialdehyde (MDA) with the existence of nano-TiO2 displayed a lower level compared to Cu ions treatment only at 24 and 48 h. This toxicity attenuation can be confirmed by subcellular structures because the impairment to cellular membranes and organelles reduced with the presence of nano-TiO2. The potential mechanisms of the antagonism between the nano-TiO2 and Cu ions can be partially attributed to the sorption of copper onto TiO2 nanoparticles, which fitted the Freundlich isotherm (coefficient = 0.967). The decreased bioavailability of Cu ions protected algae cells from being attacked by free Cu ions. Given the abundance of released nanoparticles and unique physicochemical property of nanoparticles, our results elucidated the ecosafety of nanoparticles and co-substrates in aquatic systems.

Power optimization of an irreversible regenerative Brayton cycle with isothermal heat addition

An irreversible regenerative Brayton cycle model with two heat additions is analyzed here. The external irreversibilities due to finite temperature difference and internal irreversibilities due to fluid friction losses in compressor / turbine, regenerative heat loss, pressure loss are included in the analysis. Power output of the model is obtained and thermodynamically optimized. A detailed analysis shows that with judicious selection of parameters viz. efficiency of turbine and compressor, effectiveness of various heat exchangers, isothermal pressure drop ratio, pressure drop recovery coefficients and heat capacitance rate of the working fluid, the power output of the model can be made to reach its highest possible value. It is well proven with the obtained results that induction of two heat additions significantly enhances model efficiency above 20% as compared to conventional gas power plants. The power output remains constant while the corresponding thermal efficiency increases as regenerator side effectiveness is increased. This meticulous result is different from those obtained by previous researchers. The model analyzed in this paper gives lower values of power output and corresponding thermal efficiency as expected and replicates the results of an irreversible regenerative Brayton cycle model discussed in the literature at pressure recovery coefficients of α=α2=1. regenerative Brayton cycle based on endoreversible and irreversible configuration with the application of isothermal heat additions in the view of finite time thermodynamic approach. Wang et al. [14] applied the hypothesis of finite time thermodynamics to analyze an irreversible closed intercooled regenerated Brayton cycle and optimized the intercooler pressure ratio for optimum power and corresponding efficiency. Kaushik et al. [15] performed a thermodynamic analysis of an irreversible regenerative Brayton cycle with isothermal heat addition and optimized the power output in context with working medium temperature. They observed an improvement of 15% in the thermal efficiency of Brayton cycle with heat addition at constant temperature. Chen et al. [16] analyzed power and efficiency of an endoreversible closed intercooled regenerated Brayton cycle in the view of finite time thermodynamics. Wang et al. [17-19] performed power optimization by altering effectiveness of various heat exchangers for intercooled and regenerated Brayton cycles coupled to fixed [17] and finite temperature [18-19] heat reservoirs based on endoreversible [17,18] and irreversible [19] mode.. Jubeh [20] performed exergy analysis of a regenerative Brayton cycle and found appreciable increase in second law efficiency at lesser pressure ratio, small environment temperature and elevated entrance temperature of expander with the introduction of two heat additions. Further, Wang et al. [21] investigated power and power density of externally irreversible Brayton cycle with two heat additions in the view of finite time thermodynamics and found the range of isothermal heat addition on various performance parameters of endoreversible Brayton cycle. On the basis of recent literature, a model of an irreversible regenerative Brayton cycle with pressure drop as supplementary irreversibility is considered in this paper and expressions for maximum power output and corresponding thermal efficiency of an irreversible regenerative Brayton cycle are obtained. The effect of effectiveness of various heat exchangers, efficiency of turbine and compressor, heat capacitance rates, isothermal pressure drop ratio and pressure recovery coefficients have been studied in detail and the results are presented on graphs. The model analyzed in this paper gives lower values of power output and corresponding thermal efficiency as expected. as

Equilibrium Isotherm and Mass Transfer Coefficient for Adsorption of Pure Argon on Small Particles of Pelletized Lithium-Exchanged Low Silica X Zeolite

New experimental data are reported for equilibrium adsorption isotherm and mass transfer of pure argon on a sample of pelletized lithium-exchanged low silica X (LiLSX) zeolite. Model analysis of the data indicate that the zeolite behaved like a nearly homogeneous adsorbent for Ar adsorption while it exhibited substantial heterogeneity for adsorption of N2 and milder heterogeneity for adsorption of O2. The overall mass transfer coefficient for Ar adsorption was comparable in magnitude with those of N2 and O2. The coefficient increased with increasing pressure and decreased with increasing temperature like those for N2 and O2. A large skin resistance at the adsorbent particle surface was observed for Ar mass transfer like that for adsorption of O2 and N2.

Work Process Calculation of Rotary Hybrid Energy Converting Displacement Machines

The paper presents the design of rotary hybrid displacement machines with a high indicator isothermal efficiency coefficient, with compressor section improved efficiency and reduced materials consumption. A mathematical model of the hybrid machine pump and compressor section work processes has been developed. The results of the indicator diagrams comparison obtained by computational and experimental methods are presented. In conclusion a schematic diagram of the rotary hybrid displacement machines with hydrodiode is given.