Showing papers on "Thermal diffusivity published in 2003"
TL;DR: In this article, the authors investigated the increase of thermal conductivity with temperature for nano fluids with water as base fluid and particles of Al 2 O 3 or CuO as suspension material.
Abstract: Usual heat transfer fluids with suspended ultra fine particles of nanometer size are named as nanofluids, which have opened a new dimension in heat transfer processes. The recent investigations confirm the potential of nanofluids in enhancing heat transfer required for present age technology. The present investigation goes detailed into investigating the increase of thermal conductivity with temperature for nano fluids with water as base fluid and particles of Al 2 O 3 or CuO as suspension material. A temperature oscillation technique is utilized for the measurement of thermal diffusivity and thermal conductivity is calculated from it
2,177 citations
TL;DR: In this paper, the formation and distribution of condensed water in diffusion medium of proton exchange membrane fuel cells, and its tendency to reduce the local effective mass diffusivity and to influence cell performance, are studied.
922 citations
TL;DR: In this article, a set of magmatic, metamorphic and sedimentary rocks sampled from different depth levels of the Eastern Alpine crust were used to obtain an estimate of the temperature dependence of thermal conductivity and thermal capacity.
Abstract: Thermal modeling down to great depth, e.g. down to the Mohorovicic discontinuity, requires representative values of thermal conductivity and thermal capacity at an appropriate depth. Often there is a lack of data, especially concerning temperature and pressure dependence of thermal conductivity and thermal capacity, due to missing or questionable data from boreholes. Studies of the temperature and pressure dependence of thermal conductivity and thermal capacity showed that temperature is dominating. Thus measurements on a set of magmatic, metamorphic and sedimentary rocks sampled from different depth levels of the Eastern Alpine crust were used to obtain an estimate of the temperature dependence of both properties––at least for the area of investigation––and to give a review of the temperature dependence of thermal conductivity ( λ ), thermal capacity ( ρ × c p ) and thermal diffusivity ( κ ) for different types of rock. The temperature dependence of thermal conductivity for crystalline (magmatitic and metamorphic) rocks is different to that of sedimentary rocks. Using the approach that the thermal resistivity (1/ λ ) is a linear function of temperature whose slope increases with λ (0), the conductivity at a temperature of 0 °C, two general equations were determined. The equation for crystalline rocks was verified in the temperature range of 0–500 °C and the equation for sedimentary rocks was tested in the temperature range from 0 to 300 °C. A general equation for the temperature dependence of λ for Eastern Alpine rocks can thus be formulated: λ(T)= λ(0) 0.99+T(a−b/λ(0)) with empirical constants and corresponding uncertainties a =0.0030±0.0015 and b =0.0042±0.0006 for crystalline rocks. The constants for corresponding sedimentary rocks are a =0.0034±0.0006 and b =0.0039±0.0014. λ is given in W m −1 K −1 , T in °C. At ambient conditions thermal diffusivity ( κ ) and thermal conductivity ( λ ) for Eastern Alpine crystalline rocks show the relationship: κ=0.45×λ.
420 citations
TL;DR: In this article, the effect of water content and bulk density on the specific heat, volumetric heat capacity, and thermal diffusivity of some sieved and repacked soils was investigated through laboratory studies.
334 citations
TL;DR: In this article, a framework for the prediction and control of microstructure evolution during heat treatment of wrought alpha/beta titanium alloys in the two-phase field was established via carefully controlled induction heating trials on Ti-6Al-4V and accompanying mathematical modeling based on diffusion-controlled growth.
Abstract: A framework for the prediction and control of microstructure evolution during heat treatment of wrought alpha/beta titanium alloys in the two-phase field was established via carefully controlled induction heating trials on Ti-6Al-4V and accompanying mathematical modeling based on diffusion-controlled growth. Induction heat treatment consisted of heating to and soaking at a peak temperature T
p=955 °C, controlled cooling at a fixed rate of 11 °C/min, 42 °C/min, or 194 °C/min to a variety of temperatures, and final water quenching. Post-heat-treatment metallography and quantitative image analysis were used to determine the volume fraction of primary (globular) alpha and the nucleation sites/growth behavior of the secondary (platelet) alpha formed during cooling. The growth of the primary alpha during cooling was modeled using an exact solution of the diffusion equation which incorporated diffusion coefficients with a thermodynamic correction for the specific composition of the program material and which took into account the large supersaturations that developed during the heat-treatment process. Agreement between measurements and model predictions was excellent. The model was also used to establish a criterion for describing the initiation and growth of secondary alpha as a function of supersaturation, diffusivity, and cooling rate. The efficacy of the modeling approach was validated by additional heat treatment trials using a peak temperature of 982 °C.
274 citations
TL;DR: In this article, the meaning of thermal diffusivity in homogeneous materials and composite materials is clarified, and it is shown that sometimes the association of two good thermal diffusers gives a bad diffuser.
Abstract: The two main properties related to heat conduction are thermal conductivity (K ) and thermal diffusivity (D). However, while the meaning of K is very well known, the role played by D is usually undervalued and misunderstood. In this paper we will try to clarify the meaning of thermal diffusivity, first in homogeneous materials and then in composite materials. In this latter case, we will find that sometimes the association of two good thermal diffusers gives a bad diffuser. Moreover, by properly choosing the constituents of the composites we can manufacture materials with thermal properties that are not found in nature.
237 citations
TL;DR: In this paper, the thermal properties of high-strength concrete (HSC) were determined as a function of temperature, including thermal conductivity, specific heat, thermal expansion, and mass loss.
Abstract: For use in fire resistance calculations, the relevant thermal properties of high-strength concrete (HSC) were determined as a function of temperature. These properties included the thermal conductivity, specific heat, thermal expansion, and mass loss of plain and steel fibre-reinforced concrete made of siliceous and carbonate aggregate. The thermal properties are presented in equations that express the values of these properties as a function of temperature in the temperature range between 0 and 1,000°C. The effect of temperature on thermal conductivity, thermal expansion, specific heat, and mass loss of HSC is discussed. Test data indicate that the type of aggregate has a significant influence on the thermal properties of HSC, while the presence of steel fiber reinforcement has very little influence on the thermal properties of HSC.
236 citations
TL;DR: In this article, a second-order chemical reaction between reacting calcium aluminates and ingressing sulfates depletes the sulfate concentration, leading to changes in the diffusivity and a reduction in the elastic properties of the matrix.
Abstract: A chemomechanical mathematical model is presented to simulate the response of concrete exposed to external sulfate solutions. The model is based on the diffusion-reaction approach, and several mechanisms for the reaction of calcium aluminates with sulfates to form expansive ettringite are considered. Fick’s second law is assumed for diffusion of the sulfate ions. A second-order chemical reaction between reacting calcium aluminates and ingressing sulfates depletes the sulfate concentration. The products of the second-order reaction between the aluminates and sulfates are chosen among several competing mechanisms, and a rule-of-mixtures approach is used to relate the expansive nature of the products with the prescribed specific gravity of the compounds. It is furthermore assumed that the crystallization pressure of products of reaction results in a bulk expansion of the solid. The constitutive response of the matrix and the expansive stresses are calculated from the imposed volumetric strain. Microcracks are initiated when the strength of the matrix is reached, leading to changes in the diffusivity and a reduction in the elastic properties of the matrix. The variation of diffusivity is linked to the scalar damage parameter due to cracking of the matrix. Due to the changes in the diffusivity, the problem is treated as a moving boundary problem, and a methodology is proposed to adapt the solution of the 1D case to the 2D problem of a prismatic specimen. Theoretical expansion-time responses are obtained and compared with a variety of data available in the literature.
235 citations
TL;DR: In this article, hydrogen incorporation depths of >25μm were obtained in bulk, single-crystal ZnO during exposure to 2H plasmas for 0.5 h at 300°C, producing an estimated diffusivity of ∼8×10−10 cm2/V⋅s at this temperature.
Abstract: Hydrogen incorporation depths of >25 μm were obtained in bulk, single-crystal ZnO during exposure to 2H plasmas for 0.5 h at 300 °C, producing an estimated diffusivity of ∼8×10−10 cm2/V⋅s at this temperature. The activation energy for diffusion was 0.17±0.12 eV, indicating an interstitial mechanism. Subsequent annealing at 500–600 °C was sufficient to evolve all of the hydrogen out of the ZnO, at least to the sensitivity of secondary ion mass spectrometry (<5×1015 cm−3). The thermal stability of hydrogen retention is slightly greater when the hydrogen is incorporated by direct implantation relative to plasma exposure, due to trapping at residual damage in the former case.
200 citations
TL;DR: In this article, a combined application of composite theory and Powers' model for microstructural development is proposed for the estimation of the diffusion coefficient as a function of the moisture content of a defect-free cementitious material.
184 citations
TL;DR: In this paper, the performance characteristics of a GSHP system with a 50 m vertical 1 1 4 in. nominal diameter U-bend ground heat exchanger were investigated at the university level.
TL;DR: In this paper, a combination of the M-S formulation and the ideal adsorbed solution theory allows good predictions of binary mixture transport on the basis of only pure component diffusion and sorption data.
Abstract: Correlation effects in diffusion of CH 4 and CF 4 in MFI zeolite have been investigated with the help of molecular dynamics (MD) simulations and the Maxwell-Stefan (M-S) formulation. For single-component diffusion, the correlations are captured by the self-exchange coefficient D c o r r ii; in the published literature this coefficient has been assumed to be equal to the single-component M-S diffusivity, D i . A detailed analysis of single-component diffusivity data from MD, along with published kinetic Monte Carlo (KMC) simulations, reveals that D c o r r ii/D i is a decreasing function of the molecular loading, depends on the guest-host combination, and is affected by intermolecular repulsion (attraction) forces. A comparison of published KMC simulations for diffusion of various molecules in MFI, with those of primitive square and cubic lattices, shows that the self-exchange coefficient increases with increasing connectivity. Correlations in CH 4 /CF 4 binary mixtures are described by the binary exchange coefficient D c o r r 12; this exchange coefficient has been examined using Onsager transport coefficients computed from MD simulations. Analysis of the MD data leads to the development of a logarithmic interpolation formula to relate D c o r r 12 with the self-exchange coefficient D c o r r ii of the constituents. The suggested procedure for estimation of D c o r r 12 is validated by comparison with MD simulations of the Onsager and Fick transport coefficients for a variety of loadings and compositions. Our studies show that a combination of the M-S formulation and the ideal adsorbed solution theory allows good predictions of binary mixture transport on the basis of only pure component diffusion and sorption data.
TL;DR: In this paper, the normal modes of myoglobin, their lifetimes, the speed of sound, and mean free path were calculated to determine the coefficient of thermal conductivity and thermal diffusivity for the protein.
Abstract: The normal modes of myoglobin, their lifetimes, the speed of sound, and mean free path are calculated to determine the coefficient of thermal conductivity and thermal diffusivity for the protein. A propensity is found for frequency differences of pairs of normal modes localized to nearby regions of the protein to be several hundred cm-1. As a result, the anharmonic decay rate of higher frequency, localized normal modes, calculated by perturbation theory, is typically nearly independent of temperature, consistent with results of pump−probe studies on myoglobin. The thermal diffusivity of myoglobin at 300 K is calculated to be 14 A2 ps-1, the same as the value for water. The thermal conductivity at 300 K is found to be 2.0 mW cm-1 K-1, about one-third the value for water.
TL;DR: In this paper, a coarse-grained Langevin model of the polymer dynamics and a numerical solution of the flow generated by the motion of polymer segments are used to predict the dynamics of dissolved long-chain macromolecules in highly confined environments.
Abstract: The dynamics of dissolved long-chain macromolecules are different in highly confined environments than in bulk solution. A computational method is presented here for detailed prediction of these dynamics, and applied to the behavior of ∼1–100 μm DNA in micron-scale channels. The method is comprised of a self-consistent coarse-grained Langevin description of the polymer dynamics and a numerical solution of the flow generated by the motion of polymer segments. Diffusivity and longest relaxation time show a broad crossover from free-solution to confined behavior centered about the point H≈10Sb, where H is the channel width and Sb is the free-solution chain radius of gyration. In large channels, the diffusivity is similar to that of a sphere diffusing along the centerline of a pore. For highly confined chains (H/Sb≪1), Rouse-type molecular weight scaling is observed for both translational diffusivity and longest relaxation time. In the highly confined region, the scaling of equilibrium length and relaxation t...
TL;DR: In this article, the dealloying of Ag 0.7 Au 0.3 and Ag 0. 6 5 Au 0. 3 5 alloys in 0.1 M HClO 4 with the addition of halides was studied.
Abstract: We present the results of dealloying studies of Ag 0 . 7 Au 0 . 3 and Ag 0 . 6 5 Au 0 . 3 5 alloys in 0.1 M HClO 4 with the addition of either 0.1 M KCl, 0.1 M KBr, or 0.1 M KI. The critical overpotential decreases with the addition of halides with KI having the largest potential reduction of almost 50%. This decrease is discussed with respect to a competition between the rates of increase of Au surface diffusivity and Ag exchange current density with halide additions. The size scale of porosity produced during the dealloying of Ag 0 . 6 5 Au 0 . 3 5 in the above electrolytes was found to increase with the addition of halides. Without the addition of halides, a pore size of approximately 8 nm is produced while 17, 16, and 67 nm is measured in the KCl-, KBr-, and KI-containing electrolytes. The value of surface diffusivity required to coarsen the dealloyed structure to these size scales has been calculated to be 2 × 10 - 1 6 cm 2 s - 1 (0.1 M HClO 4 ), 3 X 10 - 1 5 cm 2 s - 1 (KBr or KCI), and 8 X 10 - 1 3 cm 2 s - 1 (KI).
TL;DR: In this paper, atomically detailed simulations are used to compute the self-diffusivity and transport diffusivity of Ar and Ne through single walled carbon nanotube (SWNT) pores at room temperature.
Abstract: Atomically detailed simulations are used to compute the self-diffusivity and transport diffusivity of Ar and Ne through single walled carbon nanotube (SWNT) pores at room temperature. The diffusivi...
TL;DR: In this paper, the microstructure of the as-sprayed nanostructured zirconia coating was characterized with Scanning electronic microscopy (SEM), Transmission electron microscopy, X-ray diffraction (XRD) and Raman spectrum (RS).
Abstract: Yttria partially stabilized nanostructured zirconia coatings were deposited by atmospherical plasma spraying (APS). The microstructure of the as-sprayed nanostructured coating was characterized with Scanning electronic microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectrum (RS). The laser-flash diffusivity method and push-rod method were used to examine the thermomechanical properties of the nanostructured zirconia coatings. The results obtained indicated that the plasma-sprayed zirconia coating possessed nano-structure and its average grain size was about 73 nm. The average thermal expansion coefficients of the nanostructured coating at the first thermal cycle and second thermal cycle from room temperature to 1200 °C are 11.0 and 11.6×10−6 °C−1, respectively. The thermal diffusivity of the nanostructured zirconia coating was 1.80–2.54×10−3 cm2/s between 200 and 1200 °C. The microhardness of the nanostructured zirconia coating was 8.6 GPa, which was 1.6 times as large as that of traditional zirconia coating.
TL;DR: In this article, a one-dimensional two-phase model is used to derive an analytical light-off criterion for a straight channeled catalytic monolith with washcoat, in which the flow is laminar.
15 Jul 2003-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, the diffusion coefficient of boron in Fe2B was estimated based on a kinetic model obtained from the mass balance and considering thermodynamic equilibrium at the Fe 2B/α interface during growth.
Abstract: Experimental data from the paste-boriding process during growth of a Fe2B layer have been used to estimate the diffusion coefficient of boron in Fe2B based on a kinetic model obtained from the mass balance and considering thermodynamic equilibrium at the Fe2B/α interface during growth. A diffusivity of boron in Fe2B was obtained: D Fe 2 B =1.311×10 −6 exp − 151×10 3 kJ RT ( m 2 s −1 ) for 1223 K K .
TL;DR: First measurements of oxygen grain boundary diffusion coefficients in nanocrystalline yttria-doped ZrO2 are presented, and an oxygen diffusivity, DB, in the grain boundaries can be deduced, which is ≈3 orders of magnitude higher than in single crystals.
Abstract: First measurements of oxygen grain boundary diffusion coefficients in nanocrystalline yttria-doped ZrO2 (n-ZrO2⋅6.9 mol % Y2O3) are presented. The 18O diffusion profiles measured by secondary ion mass spectroscopy are much deeper in the nanocrystalline specimens than in single crystals. An oxygen diffusivity, DB, in the grain boundaries can be deduced, which is ≈3 orders of magnitude higher than in single crystals. From the present data the temperature variation of the oxygen grain boundary diffusivity, DB = 2.0 × 10−5 exp (−0.91 eV/kBT) m2/s, and the oxygen surface exchange coefficient, k = 1.4 × 10−2 exp (−1.13 eV/kBT) m/s, are derived.
TL;DR: In this paper, an alternative Darcian explanation and theory that retrieves the earlier advantages of the simple sorptivity test in providing parametric information about the material's hydraulic properties and allowing simple predictive formulae for the wetting profile to be generated.
Abstract: The absorption of fluid by unsaturated, rigid porous materials may be characterized by the sorptivity. This is a simple parameter to determine and is increasingly being used as a measure of a material's resistance to exposure to fluids (especially moisture and reactive solutes) in aggressive environments. The complete isothermal absorption process is described by a nonlinear diffusion equation, with the hydraulic diffusivity being a strongly nonlinear function of the degree of saturation of the material. This diffusivity can be estimated from the sorptivity test. In a typical test the cumulative absorption is proportional to the square root of time. However, a number of researchers have observed deviation from this behaviour when the infiltrating fluid is water and there is some potential for chemo-mechanical interaction with the material. In that case the current interpretation of the test and estimation of the hydraulic diffusivity is no longer appropriate. Kuntz and Lavallee (2001) discuss the anomalous behaviour and propose a non-Darcian model as a more appropriate physical description. We present an alternative Darcian explanation and theory that retrieves the earlier advantages of the simple sorptivity test in providing parametric information about the material's hydraulic properties and allowing simple predictive formulae for the wetting profile to be generated.
TL;DR: The results of the analysis, when combined with previous spectroscopic analyses, strongly suggest that the lipids provide most of the SC water barrier in either case; thus, the diffusion pathway for water is primarily transcellular.
TL;DR: A survey of data-reduction methods-algorithms for calculation of thermal diffusivity from the experimental data can be found in this article, where an up-to-date summary of the theory and application of the flash method is presented.
Abstract: It is more than forty years since Parker et al (1961 J. Appl. Phys. 32 1679-1684), working for the US Navy Radiological Defense Laboratory, released their original paper introducing the flash technique. Since then this photothermal experimental method has been extended worldwide and it has become the most popular method for the measurement of the thermal diffusivity of solids. The simplicity and the efficiency of the measurement, the accuracy and the reliability of results, and possibilities of application under a wide range of experimental conditions and materials are the main advantages of the flash method. The fact that the flash method has received standard status in many countries acknowledges its universality. We present an up-to-date summary of the theory and application of the flash method. We discuss the ideal adiabatic model and non-ideal models that account for the influence of the main disturbing phenomena-heat losses from the sample, finite heat pulse durations, and nonuniform heating effects. The paper focuses on the survey of data-reduction methods-algorithms for calculation of thermal diffusivity from the experimental data. It provides also references to several original papers with descriptions of the experimental apparatus. Attention is given to applications of the flash method for the measurement of advanced materials-semitransparent media, materials with significant dependence of their thermophysical properties on temperature, anisotropic materials, layered structures, thin films, and composites. The paper contains a short note about various experimental methods having their origin in the flash method.
TL;DR: In this paper, the authors used the effective diffusivity as a quantitative diagnostic of transport and mixing in time-periodic flows and compared it with other diagnostics, and showed that it accurately captures the location and character of barrier and mixing regions.
Abstract: The advection-diffusion equation for the concentration of a tracer may be transformed into a pure diffusion equation by using the area inside concentration contours as a coordinate. The corresponding effective diffusivity depends on the geometry of the tracer field, which is determined by the underlying flow. Recent studies have used effective diffusivity, calculated from a suitable tracer, as a qualitative indicator of the transport and mixing properties of a given flow. Here we show that the effective diffusivity may further be used as a quantitative diagnostic of transport and mixing. We use a family of incompressible two-dimensional time-periodic flows as a test-bench and compare the calculated effective diffusivity with other diagnostics. The results demonstrate how the effective diffusivity accurately captures the location and character of barrier and mixing regions. We also show that the effective diffusivity parameterizes the transport of particles relative to the tracer-based coordinates. These results support the use of effective diffusivity as a quantifier of transport and mixing, and thereby strengthen the conclusions of previous qualitative studies.
20 Jan 2003-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the thermal diffusivity and thermal conductivity of magnesium-aluminium alloys AM20, AM50 and AM60 were investigated in the temperature range from 20 to 300 °C.
Abstract: The thermal diffusivity and thermal conductivity of magnesium–aluminium alloys AM20, AM50 and AM60 were investigated in the temperature range from 20 to 300 °C. The thermal diffusivity of AM20 increases with increasing temperature upto 160 °C, above this temperature the increase is less marked. The change in the slope of the temperature variation of the thermal diffusivity is probably caused by a reduction of the amount of Mg 17 Al 12 phase. The values of the thermal diffusivity and of the thermal conductivity of the solid solution are lower than those obtained when the alloys contain two phases. The measured values are compared with those calculated by transformed Nordheim rule.
02 Jan 2003-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, the authors studied the effect of pineapple leaf fiber reinforced phenolformaldehyde (PF) composites on the effective thermal conductivity and effective thermal diffusivity.
Abstract: Simultaneous measurment of effective thermal conductivity (λ) and effective thermal diffusivity (κ) of pineapple leaf fiber reinforced phenolformaldehyde (PF) composites have been studied by transient plane source (TPS) technique. The samples of different weight percentage typically (15, 20, 30, 40 and 50%) have been taken. It is found that of effective thermal conductivity and effective thermal diffusivity of the composites decrease, as compared with pure PF as the fraction of fiber loading increases. Using Y. Agari, model thermal conductivity of pure fiber is evaluated and compared with the thermal conductivity of fiber determined by extrapolated experimental value of composite. Also, we have compared the results of thermal conductivity of composites with two models (Rayleigh–Maxwell and Meredith–Tobias model). Good agreement between theoretical and experimental result has been found.
TL;DR: Within the framework of an international benchmark test, the Soret coefficient S T, thermal diffusion coefficient D T and mutual mass diffusion coefficientD of the three binary mixtures of dodeca... as discussed by the authors.
Abstract: Within the framework of an international benchmark test, the Soret coefficient S T , thermal diffusion coefficient D T and mutual mass diffusion coefficient D of the three binary mixtures of dodeca...
TL;DR: In this paper, high-temperature heat capacity and thermal diffusivity of neodymium zirconate (Nd 2 Zr 2 O 7 ) were measured by differential scanning calorimetry and laser flash, respectively.
TL;DR: In this article, three models were used to describe the extraction of essential oils from oregano bracts using compressed carbon dioxide, two particle phase derived models, the Single Plate model (SP model) and the Simple Single Plate (SSP model), differ only by the allowance or not for a film coefficient (kf) and have as the only adjustable parameter the matrix diffusivity (Dm).
Abstract: Three models were used to describe the extraction of essential oils from oregano bracts using compressed carbon dioxide. They were developed on the basis of a plate-like geometry of the particles and were tested experimentally using various bract pre-treatments, pressures, temperatures and solvent flow rates. The two particle phase derived models applied, the Single Plate model (SP model) and the Simple Single Plate model (SSP model), differ only by the allowance or not for a film coefficient (kf) and have as the only adjustable parameter the matrix diffusivity (Dm). The third model, the Fluid Phase/Simple Single Plate model (FP/SSP model), considers both the particle mass balance and a detailed description of the fluid mass balance. In addition to the matrix diffusivity the FP/SSP model may require the adjustment of the fraction of oil leached by the solvent during the pressurisation procedure (f0). All models gave a good fit to the experimental data though the FP/SSP model gave the best fit. However, the matrix diffusivities found correlated very poorly with the estimated diffusivity of essential oils in carbon dioxide (D12), which indicates a complex intraparticle transport.
TL;DR: In this paper, the relationship between particle and heat transport in an internal transport barrier (ITB) has been systematically investigated in reversed shear (RS) and high βp mode plasmas of JT-60U.
Abstract: The relationship between particle and heat transport in an internal transport barrier (ITB) has been systematically investigated in reversed shear (RS) and high βp mode plasmas of JT-60U. The electron effective diffusivity is well correlated with the ion thermal diffusivity in the ITB region. The ratio of particle flux to electron heat flux, calculated on the basis of the linear stability analysis, shows a similar tendency to an experiment in the RS plasma with a strong ITB. However, the calculated ratio of ion anomalous heat flux to electron heat flux is smaller than the experiment in the ITB region. Helium and carbon are not accumulated inside the ITB even with ion heat transport close to a neoclassical level, but argon is accumulated. The helium diffusivity (DHe) and the ion thermal diffusivity (χi) are 5–15 times higher than the neoclassical level in the high βp mode plasma. In the RS plasma, DHe is reduced from 6–7 times to a 1.4–2 times higher level than the neoclassical level when χi is reduced from 7–18 times to a 1.2–2.6 times higher level than the neoclassical level. The carbon and argon diffusivities estimated assuming the neoclassical inward convection velocity are 4–5 times larger than the neoclassical value, even when χi is close to the neoclassical level. Argon exhaust from the inside of the ITB is demonstrated by applying electron cyclotron heating (ECH) in the high βp mode plasma, where both electron and argon density profiles become flatter. The flattening of the argon density profile is consistent with the reduction of the neoclassical inward convection velocity due to the reduction of the bulk plasma density gradient. In the RS plasma, the density gradient is not decreased by ECH and argon is not exhausted. These results suggest the importance of density gradient control in suppressing impurity accumulation.