Change In Thermal Diffusivity Research Articles

Role of microstructure in the exploitation of self-healing potential in form-stable composite phase change materials based on immiscible alloys

Metallic Phase Change Materials (PCMs), based on solid-liquid transitions, represents one of the most promising technologies for efficient Thermal Energy Storage (TES), due to their superior thermal conductivity and energy storability per unit volume, but suffer of limited solutions for their handling at the molten state. The use of Miscibility Gap Alloys (MGAs) allows to manage PCM volume expansion and keep it confined when molten, preventing interaction with the environment. A relevant example is provided by the Al-Sn system, where Al covers the role of the high-temperature stable and highly thermal-conductive passive matrix and Sn the active PCM. The alloy can thus be considered a Composite PCM (C-PCM). The response fastness of these systems depends on their thermal diffusivity, subjected to abrupt variations under the presence of discontinuities and damages. In this sense, the authors investigated the possibility to employ molten Sn mobility in a potentially damaged C-PCM for self-healing purposes, aimed to restore, at least partially, the material continuity and thus its thermal diffusivity. Exudation heat treatments above the melting temperature of Sn were performed on sets of Al-40%wt. Sn metallic composites, produced either with powder metallurgy or liquid metal routes, in order to quantify and assess the mobility of the Sn under simulated operating conditions. Exudation tests assess Simple Mixed powders and liquid metal routes sample as the ones with the highest healing potential. Al dissolution and re-deposition was established by EDS analyses as one of the principal Sn mobility mechanisms. Laser Flash Analysis tests, as well as microstructural investigations, were performed on the samples before and after both healing-focused and simulated service heat treatments to evaluate the changes of thermal diffusivity. Healing-focused treatment at 250°C for 1 hour generally displayed a moderate thermal diffusivity recovery and simulated service by shorter cycles between 170°C and 270°C slightly reduce it. The beneficial role of healing focused heat treatments at 250°C for 1 hour suggests that the presence of fully molten Sn phase during service for relatively long time could be beneficial for functional healing. The requirements of suitable Al-Sn microstructures for self-healing purposes, granting at the same time the C-PCM functionalities, i.e., thermal energy storage and form-stability, were set.

Thermodynamic and hydrological drivers of the soil and bedrock thermal regimes in central Spain

Abstract. An assessment of the soil and bedrock thermal structure of the Sierra de Guadarrama, in central Spain, is provided using subsurface and ground surface temperature data coming from four deep (20 m) monitoring profiles belonging to the Guadarrama Monitoring Network (GuMNet) and two shallow profiles (1 m) from the Spanish Meteorology Service (Agencia Estatal de Meteorología, AEMET) covering the time spans of 2015–2021 and 1989–2018, respectively. An evaluation of air and ground surface temperature coupling showed that soil insulation due to snow cover is the main source of seasonal decoupling, being especially relevant in winter at high-altitude sites. Temperature propagation in the subsurface was characterized by assuming a heat conductive regime by considering apparent thermal diffusivity values derived from the amplitude attenuation and phase shift of the annual cycle with depth. This methodology was further extended to consider the attenuation of all harmonics in the spectral domain, which allowed for analysis of thermal diffusivity from high-frequency changes in the soil near the surface at short timescales. For the deep profiles, the apparent thermal diffusivity ranges from 1 to 1.3×10-6 m2 s−1, which is consistent with values for gneiss and granite, the major bedrock components in the Sierra de Guadarrama. However, thermal diffusivity is lower and more heterogeneous in the soil layers close to the surface (0.4–0.8×10-6 m2 s−1). An increase in diffusivity with depth was observed that was generally larger in the soil–bedrock transition at 4–8 m depth. The outcomes are relevant for the understanding of soil thermodynamics in relation to other soil properties. Results with the spectral method suggest that changes in near-surface thermal diffusivity are related to changes in soil moisture content, which makes it a potential tool to gain information about soil drought and water resource availability from soil temperature data.

The Thermophysical and Physicochemical Properties of the Aqueous Dispersion of Graphene Oxide Dual-Beam Thermal Lens Spectrometry.

Modern heat-conducting materials require special attention to analyze their thermophysical properties. Compared to classical methods, thermal lens spectrometry (TLS) has advantages due to its high sensitivity to physical and chemical composition. To avoid a systematic error in the analysis of complex systems, it is necessary to realize the limits of the applicability of the method. This study considers the features of thermal-diffusivity measurements by TLS in the stationary state for dispersed systems with absorbances up to 0.05. The limits of applicability of the method in analyzing heterogeneous systems are shown, and a mathematical apparatus is proposed for indicating a systematic error in finding thermal diffusivity that does not exceed 1%. Graphene oxide (GO), which has attractive physicochemical properties, was used as the object of analysis. GO belongs to 2D objects, the study of which requires highly sensitive methods and special attention when discussing the results. The thermophysical properties of aqueous dispersions of graphene oxide in a wide range of concentrations (up to 2 g/L) and lateral sizes (up to 4 µm) were studied by TLS. It has been found that with increasing nanophase concentration, the thermal diffusivity of graphene oxide dispersions passes through a minimum, which can be used in solving thermal insulation problems. It has been established that prolonged laser irradiation of the dispersion leads to a change in thermal diffusivity, which indicates the photochemical reduction of graphene oxide.

Zn_{1-x}Ni_xTe semiconductor nanocrystals in transparent glass for optoelectronic device applications

Doping glass with semiconductors, particularly with nanostructured semiconductors, has attracted attention due to the large optical absorption cross-sections of the latter. Based on this property, Ni^{2+} (5 wt%) doped phosphate glass and Zn_{1-x}Ni_xTe (x = 0.5, 1.0, 5.0 and 10.0 wt% of Ni^{2+}) nanocrystals (NCs) doped phosphate glasses (GCs) were prepared by fusion method and subsequent heat treatment. Influence of Ni^{2+} on structural, thermo-optical and third-order nonlinear optical properties have been analysed through various spectroscopic characterizations. The XRD pattern of the glass (G) exhibits the amorphous nature of the host material while GCs exhibit not only amorphous halo but also the presence of quantum dots (QDs) or nanocrystals (NCs) phases. TEM analysis of the studied GCs samples confirm the presence of quantum dots (QDs) and bulk NCs with an average diameter of approximately 4.2 {pm } 0.3 nm and 13.4 {pm } 0.2 nm, respectively. Several phosphate groups were observed and reported from Raman and FTIR-ATR spectra. The absorption band positions confirmed that Ni^{2+} ions resemble to the octahedral symmetry. The intensity of absorption band around 1352 nm (^3T{_1}(F) rightarrow^3A{_2}(F)) increased with the increase of Ni^{2+} in GCs which is an indicative of the ^{[6]}Ni^{2+} coordination. The emission properties such as emission cross-sections ({sigma }_{emi}) full width at half maxima (FWHM) for the ^1T{_2}(D) rightarrow^3T{_2}(F) (visible) and ^3A{_2}(F) rightarrow^3T{_1}(F) (near-infrared) emission transitions were reported. Among the glass-containing semiconductor nanocrystals (GCs), the emission cross-sections in GC4 sample (x = 10% of Ni^{2+}) are the largest for both the visible (11.88 times 10^{-18} cm^2) and infrared (0.98 times 10^{-20} cm^2) transitions. Thermal diffusivity (D), thermal conductivity (K) and temperature dependent optical path length change (ds/dT) were obtained through time-resolved thermal lens (TL) and thermal relaxation (TR) methods. The D and K parameters do not change significantly with increase of Ni^{2+} ions (0.5–5%) in GCs. Nonlinear-refractive index and nonlinear absorption of the studied samples were also obtained using femtosecond Z-scan technique. The increase of nonlinear absorption coefficient (beta) is observed from GC2 (2.53 {times } 10^{-10} cm/W) to GC4 (7.98 {times } 10^{-10} cm/W). The GC4, sample with 10 wt% of Ni^{2+}, showed the lowest ds/dT (1.22 times 10^{-6} K^{-1}) with good lasing (FOM and emission cross-sections) and nonlinear absorption properties suggesting that it can be a good candidate for visible-red emission light conversion in LED technology.

Thermal diffusivity variation assessment on Radio-Frequency Quadrupole Cu-OF copper due to proton irradiation

Particle accelerator components are exposed to high radiation environments that could lead to material property degradation and affect component’s performance and lifetime. The ability to deploy rapid, multi-modal, non-destructive techniques provides valuable insight in microstructure evolution of radiation induced effects. The current work demonstrates the use of Transient Grating Spectroscopy (TGS) as a powerful technique to detect post irradiation changes in thermal diffusivity of polycrystal, high-purity, oxygen-free copper (Cu-OF) used in Radio-Frequency Quadrupoles (RFQs). For that purpose, the nominal operation proton beam losses of the European Spallation source (ESS) RFQ were studied to define copper sample irradiation patterns at MIT Tandetron accelerator that emulate the radiation damage conditions corresponding to 24 h of operation. Sample measurements with TGS before and after irradiation were performed in order to assess potential variation in copper thermal properties. Irradiated samples with energy of 120 keV, incident angles of 0°, 40° and fluence of 1017 p/cm2 at room temperature and resulted damage of 0.015 dpa presented a decrease in their thermal diffusivity which can be attributed to point defect generation and void formation.

Changes in thermal properties of 7075 aluminium alloy by aging heat treatment

This study investigated the effects of aging heat treatment on the change of thermal properties of 7075 Al alloy using differential scanning calorimetry and a laser flash apparatus. The thermal diffusivity showed different trends in the three temperature ranges: In the range from room temperature to 160°C, the thermal diffusivity increased with increasing temperature. Between 160 and 240°C, the thermal diffusivity increased with an increase in the temperature of the specimen. Precipitation was completed at 240°C or higher, and the thermal diffusivity decreased with an increase in the temperature of the specimen. The amount of precipitation of η′ and η phases did not affect the change in thermal diffusivity but only contributed to the improvement of micro-hardness.

Fabrication of a photoacoustic cell and thermal diffusivity measurement of graphene oxide using photoacoustic spectroscopy

Photoacoustic spectroscopy (PAS) is an important technique for the characterization of materials by measuring the heat produced due to the non-radiative transitions. Here, the authors have fabricated a photoacoustic cell and made parametric studies to get maximum signal sensitivity. For the optimum signal, the cavity volume of the sample chamber is found to be 1.763 × 10–6 m3. After optimization of the cell, the thermal diffusivity of hummers method synthesized graphene oxide (GO) powder was measured using laser excitation at 980 nm and it is found to ∼(1.84 ± 0.10) × 10–4 m2/s. Also, the thermal diffusivity of the same sample was measured using 560 and 680 nm excitation wavelengths. No measurable change in thermal diffusivity with excitation wavelength is seen and it confirms that thermal diffusivity is independent of the excitation wavelength. Lastly, photoacoustic spectrum of the GO sample was measured in the 400–1200 nm range and compared with the spectrum of lamp black.

Thermal Diffusivity Characteristics of the IN718 Alloy Tested with the Modified Pulse Method.

The article presents the use of the modified pulse method (MPM) to determine the temperature characteristics of the thermal diffusivity of alloy 718. The experiment was carried out in the temperature range of 20-900 °C during the double heating of the sample with an interval of two weeks. The results of our own research showed a good correlation in the temperature range of 300-500 °C, during the first heating of the sample, with the recommended changes in thermal diffusivity by NPL & ASM and data from the MPDB database. On the other hand, clear deviations in the results occurred in the range of temperature changes up to about 300 °C, most likely responsible for the electron component of the conductivity of this alloy, and in the range above 700 °C, where there is a clear minimum that may be caused by the δ phase precipitation phenomenon.

An Application of the Finite Element Method for Heat and Mass Transfer of Boundary Layer Flow Using Variable Thermal Conductivity and Mass Diffusivity

Since mass diffusivity and thermal conductivity cannot be considered constants in practical analysis, an existing heat and mass transfer model of unsteady mixed convection flow over a stretching sheet is modified by incorporating the effects of nonlinear mixed convection variable thermal conductivity and mass diffusivity and solved its dimensionless form by applying the finite element method which is the main novelty of this work. Nonlinear governing equations are created because of changing thermal conductivity and mass diffusivity. Nonlinear solutions can be achieved by employing the Galerkin finite element approach. Temperature and concentration-based thermal conductivity and mass diffusivity are considered. The model is expressed as a set of partial differential equations, and furthermore, it is reduced to a system of dimensionless ordinary differential equations. These obtained equations are solved with the finite element method with linear interpolating polynomials and numerical integration. In addition, a Matlab solver bvp4c is also considered for comparison purposes or validation of the computed results. The graphs depict the effect of various parameters on the velocity, temperature, and concentration curves. The results show that thermal and diffusive wave propagation is significantly affected by thermal conductivity and mass diffusivity changes. Results show that flow velocity escalates by rising values of thermal and solutal Grashof numbers.

Probabilistic estimation of depth-resolved profiles of soil thermal diffusivity from temperature time series

Abstract. Improving the quantification of soil thermal and physical properties is key to achieving a better understanding and prediction of soil hydro-biogeochemical processes and their responses to changes in atmospheric forcing. Obtaining such information at numerous locations and/or over time with conventional soil sampling is challenging. The increasing availability of low-cost, vertically resolved temperature sensor arrays offers promise for improving the estimation of soil thermal properties from temperature time series, and the possible indirect estimation of physical properties. Still, the reliability and limitations of such an approach need to be assessed. In the present study, we develop a parameter estimation approach based on a combination of thermal modeling, sliding time windows, Bayesian inference, and Markov chain Monte Carlo simulation to estimate thermal diffusivity and its uncertainty over time, at numerous locations and at an unprecedented vertical spatial resolution (i.e., down to 5 to 10 cm vertical resolution) from soil temperature time series. We provide the necessary framework to assess under which environmental conditions (soil temperature gradient, fluctuations, and trend), temperature sensor characteristics (bias and level of noise), and deployment geometries (sensor number and position) soil thermal diffusivity can be reliably inferred. We validate the method with synthetic experiments and field studies. The synthetic experiments show that in the presence of median diurnal fluctuations ≥ 1.5 ∘C at 5 cm below the ground surface, temperature gradients > 2 ∘C m−1, and a sliding time window of at least 4 d the proposed method provides reliable depth-resolved thermal diffusivity estimates with percentage errors ≤ 10 % and posterior relative standard deviations ≤ 5 % up to 1 m depth. Reliable thermal diffusivity under such environmental conditions also requires temperature sensors to be spaced precisely (with accuracy to a few millimeters), with a level of noise ≤ 0.02 ∘C, and with a bias defined by a standard deviation ≤ 0.01 ∘C. Finally, the application of the developed approach to field data indicates significant repeatability in results and similarity with independent measurements, as well as promise in using a sliding time window to estimate temporal changes in soil thermal diffusivity, as needed to potentially capture changes in bulk density or water content.

Thermal diffusivity of organosuperelastic soft crystals during stress-induced phase transition

Thermal diffusivity during stress-induced phase transition was examined and precisely determined in terephthalamide, an organosuperelastic soft crystal. A 14% maximum change in thermal diffusivity was realized in a superelastic phase transformation at a shear stress below 0.5 MPa. Thermal diffusivity measurements under the crystal deformation were achieved using microscale photothermal temperature-wave analysis. A maximum fivefold anisotropy was found in the thermal diffusivity between the c axis and other crystal axes. The results indicate the potential for developing practical thermal applications of organosuperelastic single crystals.

Change in Thermal Diffusivity of Al-Si-Mg-Cu Alloy According to Heat Treatment Conditions at Automotive Engine Operating Temperature

Change in Thermal Diffusivity of Al-Si-Mg-Cu Alloy According to Heat Treatment Conditions at Automotive Engine Operating Temperature

Concentration dependent thermo-optical properties and nonlinear optical switching behavior of bimetallic Au-Ag nanoparticles synthesized by femtosecond laser ablation

Concentration, morphology and composition-dependent thermal diffusivity changes occurring in bimetallic Au-Ag nanoparticles synthesized by femtosecond laser ablation were investigated using a dual- beam mode matched thermal lens technique. The synthesis utilized the variation in ablation time of silver plate kept immersed in already synthesized gold nanoparticle seeds. Thermal diffusivity values were found to increase both with an increase in concentration of the samples as well as an increase in Ag/Au weight percentage ratio. Au-Ag core–shell and nanoalloy structure show much greater variation in the thermal diffusivity compared to the other samples. A possible explanation could be the modified surface state density of the bimetallic nanoparticles. A single beam z scan technique using an Nd:YAG laser operating at a wavelength of 532 nm was employed for the nonlinear optical characterization of the samples. At a fixed laser input fluence, a switching behavior from saturable absorption (SA) to reverse saturable absorption (RSA) was observed as the ablation time of the silver plate in gold nanoparticle solution increased. The effect of laser input fluence on nonlinear optical properties of core–shell and nanoalloy structures was also studied and the optical limiting threshold of nanoalloy was calculated. The results revealed an increase in the nonlinear absorption coefficient with an increase in input fluence. A linear variation of the limiting threshold was also observed with an increase in input fluence. Thermal diffusivity studies find applications in photo thermal therapies and optical limiting properties find application in optoelectronic switches.

Active Thermal Testing of Impact Damage in 3D-Printed Composite Materials

Using the method of ultrasonic infrared thermography, it has been shown that 3D printing technology prevents cracking of the edges of access holes in composites during their machining. It is expedient to evaluate the impact strength of composites by the relative change in the thermophysical characteristics in the zones of impact damage, based on the assumption that a higher impact energy leads to the more developed defects and, accordingly, to the greater relative changes in thermal inertia and thermal diffusivity. The impact resistances of Kevlar and carbon fiber composite specimens, as well as their hybrid, have been compared. The highest impact resistance was demonstrated by a hybrid sample of Kevlar and carbon fiber composite, in which the change in thermal inertia and thermal diffusivity after an impact with an energy of 15 J was 4 and 8%, respectively, compared with 10 and 9% for the CFRP and 15 and 11% for the Kevlar.

Characterising Ion-Irradiated FeCr: Hardness, Thermal Diffusivity and Lattice Strain

Ion-irradiated FeCr alloys are useful for understanding and predicting neutron damage in the structural steels of future nuclear reactors. Previous studies have largely focused on the structure of irradiation-induced defects, probed by transmission electron microscopy (TEM), as well as changes in mechanical properties. Across these studies, a wide range of irradiation conditions has been employed on samples with different processing histories, which complicates the analysis of the relationship between defect structures and material properties. Furthermore, key properties, such as irradiation-induced changes in thermal transport and lattice strain, are little explored.Here we present a systematic study of Fe3Cr, Fe5Cr and Fe10Cr binary alloys implanted with 20 MeV Fe3+ ions to nominal doses of 0.01 dpa and 0.1 dpa at room temperature. Nanoindentation, transient grating spectroscopy (TGS) and X-ray micro-beam Laue diffraction were used to study the changes in hardness, thermal diffusivity and strain in the material as a function of damage and Cr content. Our results suggest that Cr leads to an increased retention of irradiation-induced defects, causing substantial changes in hardness and lattice strain. However, thermal diffusivity varies little with increasing damage and instead degrades significantly with increasing Cr content in the material. We find significant lattice strains even in samples exposed to a nominal displacement damage of 0.01 dpa. The defect density predicted from the lattice strain measurements is significantly higher than that observed in previous TEM studies, suggesting that TEM may not fully capture the irradiation-induced defect population.

Effect of laser shock peening on the microstructure, tensile and heat transport properties of Alloy D9

Present work investigates the effect of laser shock peening on the microstructure and properties of alloy D9, a candidate material for the core applications in fast breeder reactors. For select peening parameter, surface and depth distribution of residual compressive stresses, microstructure, hardness, tensile properties and thermal diffusivity have been compared with a reference (annealed) material. After shock peening, using laser energy of 3J/pulse, compressive stresses were present up to a depth of 360 μm from the surface with a maximum magnitude of 330 MPa at a depth of 20-30 μm from the surface. Though the microstructure showed no appreciable change, both hardness and yield strength increased (by 32% and 63% respectively) and ductility decreased after peening. Mechanical property evaluation using miniaturized tensile testing gave a truly quantitative estimate of the change in properties due to peening. Change in thermal diffusivity measured from ambient temperature up to 700 °C suggested the superior thermal stability of laser shock peened specimen.

Thermal diffusivity degradation and point defect density in self-ion implanted tungsten

Using transient grating spectroscopy (TGS) we measure the thermal diffusivity of tungsten exposed to different levels of 20 MeV self-ion irradiation. Damage as low as 3.2 × 10−4 displacements per atom (dpa) causes a measurable reduction in thermal diffusivity. Doses of 0.1 dpa and above, up to 10 dpa, give a degradation of ∼55% from the pristine value at room temperature. Using a kinetic theory model, the density of irradiation-induced point defects is estimated based on the measured changes in thermal diffusivity as a function of dose. These predictions are compared with point defect and dislocation loop densities observed in transmission electron microscopy (TEM). Molecular dynamics (MD) predictions are combined with the TEM observations to estimate the density of point defects associated with defect clusters too small to be probed by TEM. When these “invisible” defects are accounted for, the total point defect density agrees well with that estimated from TGS for a range of doses spanning 3 orders of magnitude. Kinetic theory modelling is also used to estimate the thermal diffusivity degradation expected due to TEM-visible and invisible defects. Finely distributed invisible defects appear to play a much more important role in the thermal diffusivity reduction than larger TEM-visible dislocation loops. This work demonstrates the capability of TGS, in conjunction with kinetic theory models, to provide rapid, quantitative insight into defect densities and property evolution in irradiated materials.

THERMAL DIFFUSIVITY VARIATION EFFECT ON A HYDRO-THERMAL CONVECTIVE FLOW IN A POROUS MEDIUM

We consider a hydrothermal convective flow in a porous medium to investigate the effect of the vertical rate of change in thermal diffusivity. Using a weakly nonlinear approach, we derive the linear and first-order systems assuming a no-flow basic state system. The solutions for the linear and first-order systems are computed numerically using both the fourth-order Runge-Kutta and shooting methods. Numerical results obtained in this study show a stabilizing effect on the dependent variables for the case of a positive vertical rate of change in diffusivity, whereas a destabilizing effect is noticed for the case of a negative vertical rate of change in diffusivity. The present results indicate that convective flow driven by the buoyancy force is more effective if thermal diffusivity is weaker, while the opposite result holds for a stronger diffusivity effect. In particular, both velocity and convective temperature decrease with increasing diffusivity, while they increase with decreasing diffusivity. At the middle of the layer (z = 0) for x = 0, the contribution of the linear and first-order solutions to the velocity component are 0.3345, 0.3031, and 0.3679 for the respective values 0.0, 0.6, and -0.4 of the diffusivity parameter. For temperature, these contributions are 0.0167, 0.0116, and 0.0229, respectively. Some other quantitative results are provided in tabular form.

Thermal Diffusivity of Fresh Silicone Rubber Composite Insulators Determined by Photothermal Radiometry

Thermal diffusivity was confirmed to be a useful parameter for evaluating the aging degree of silicone rubber composite insulators widely used in high-voltage–power systems. However, the aging induced thermal diffusivity change of composite insulators not only is related to the initial thermal diffusivity of fresh silicone rubber, but also could be within a certain range for fresh composite insulators due to composition differences of base polymer and fillers and additives, makes the direct correlation of thermal diffusivity of aged composite insulator to aging degree difficult. In this work, thermal diffusivities of fresh composite insulators with different voltage grades, different mechanical load grades, and manufactured by different vendors are determined with photothermal radiometry (PTR) by fitting experimental frequency dependences of PTR amplitude and phase to an appropriate theoretical model. The thermal diffusivities of composite insulators from two vendors are approximately 3.70 × 10−7 m2·s−1 to 3.76 × 10−7 m2·s−1 and 4.87 × 10−7 m2·s−1 to 4.94 × 10−7 m2·s−1, respectively, showing significant difference, due to composition difference. The thermal diffusivities of composite insulators with voltage grades 35 kV, 110 kV, and 220 kV, and with mechanical load grades 70 KN, 100 KN, and 120 KN are also measured and found to be only slightly divergent, due to the same composition. In addition, the thermal diffusivity uncertainties of two vendors are quite different, indicating sample homogeneity discrepancy. This variation is useful information for evaluating aging process of silicone rubber composite insulators from the thermal diffusivity measurements of aged composite insulators.

Thermal Diffusivity, Moisture Diffusivity, and Color Change of Codonopsis javanica with the Support of the Ultrasound for Drying

In this study, drying kinetics, including thermal and moisture, of Codonopsis javanica with the support of ultrasonic technology in the drying process were investigated. Experimental processes were carried out at drying air temperatures of 40°C, 45°C, and 50°C with and without ultrasound at a frequency of 20 kHz and three levels of intensity: 1.3 kW/m2, 1.8 kW/m2, and 2.2 kW/m2. Based on theoretical calculations, experimental data, and the particle swarm optimization (PSO) algorithm, the coefficient of thermal diffusion was determined in the range of 1.01–1.36 × 10−7 m2/s, and the coefficient of moisture diffusion is in the range of 3.2–6.7 × 10−10 m2/s. In addition, the color parameters (L∗, a∗, and b∗) of the drying materials were also considered. Results showed the overall color differences (∆E) of dried products change in the range of 8.0–12.9 compared with the fresh ones. In this work, the multiple boundary conditions were considered to determine the moisture and thermal diffusion coefficients; the results obtained prove that the quality of dried products in terms of color change is also improved.