Modeling heat and mass transfer in the heat treatment step of yerba maté processing

In the work, the authors investigated the possibility of using the results of analytical solutions of the linear differential equations of unsteady heat conduction with constant heat transfer coefficients to calculate the temperature of the material during heat treatment of leathers. Heat treatment of natural leathers as heat-sensitive materials is carried out under mild temperature conditions and high air moisture contents, the temperature does not undergo significant changes, and the heat transfer coefficients change almost linearly. When using analytical solutions, the authors made the assumptions that for small temperature gradients over the cross section of a thin body, the thermal transfer of matter can be neglected and for values of the heat and mass transfer Biot criteria less than unity, the main factor, limiting heat and mass transfer, is the interaction of the evaporation surface of the body with the environment; so, in solving the differential heat equation we can restrict ourselves to one first member of an infinite series. In this case, a piecewise stepwise approximation of all thermophysical characteristics with constant values of these coefficients at the calculated time intervals was applied, which made it possible to take into account the change in the transfer coefficients throughout the entire heat treatment process. Processing of experimental data showed that in low-intensity processes with reliable values of the transfer coefficients, it is possible to use the results of solutions of differential equations of unsteady heat conduction in heat transfer calculations. The results of the study of heat transfer during drying of leather confirm the laws of temperature change established experimentally. Together with experimental studies of drying processes, analytical studies are of great practical importance in the development of new methods for calculating heat and mass transfer in wet bodies.

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Heat Treatment of Friction Surfaced Steel-Aluminum Couple

Materials Science Forum ◽

10.4028/www.scientific.net/msf.830-831.135 ◽

2015 ◽

Vol 830-831 ◽

pp. 135-138 ◽

Cited By ~ 1

Author(s):

K. Udaya Bhat ◽

Nithin ◽

Suma Bhat ◽

Sudeendran

Keyword(s):

Heat Treatment ◽

Solid State ◽

Mild Steel ◽

Steel Surface ◽

Aluminum Layer ◽

Friction Surfacing ◽

State Process ◽

Aluminide Layer ◽

Treatment Step ◽

Heat Treatment Step

Friction surfacing is a solid state process and it is amenable for deposition of aluminum on steel. In this investigation, the mild steel surface was coated with a layer of aluminum using friction surfacing route. The aluminum thickness was in the range of 40-50 μm. It was followed by a heat treatment step to convert aluminum layer in to an aluminide layer. Heat treatment was done in open atmosphere at 700 °C for 2 hours. Microstuctural analysis showed that the aluminide layer is mainly made of Fe2Al5 and Fe4Al13, FeAl and Fe3Al are minor in fraction. Formation of Fe2Al5 is discussed. The aluminide layer also has some amount of porosities.

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Effect of heat treatment residual stress on stress behavior of constant stress beam

Journal of Computational Design and Engineering ◽

10.1016/j.jcde.2017.07.001 ◽

2017 ◽

Vol 5 (1) ◽

pp. 137-143 ◽

Cited By ~ 4

Author(s):

Si Young Kwak ◽

Ho Young Hwang

Keyword(s):

Heat Treatment ◽

Residual Stress ◽

External Load ◽

Treatment Process ◽

Constant Stress ◽

Design Stage ◽

Treatment Processes ◽

Stress Behavior ◽

Treatment Step ◽

Heat Treatment Step

Abstract Although most casting and heat treatment processes generate significantly high residual stress in the products, this factor is generally not taken into account in the design stage of the product. In this study, experimental study and numerical analysis were conducted on a constant stress beam to examine effects of the residual stress generated during the heat treatment process on yielding behavior of the product in use. A constant stress beam of SUS 304 was designed in order to test the stress behavior related to residual stress. The residual stresses generated during quenching heat treatment of the beam were measured in advance by ESPI (Electronic Speckle-Pattern Interferometry) equipment, and then the external stresses generated while applying a simple external load on the beam were measured. Also, the residual stress distribution generated during the heat treatment process was computed using a numerical analysis program designed for analyzing heat treatment processes. Then, the stress distribution by a simple external load to the beam was combined with the calculated residual stress results of the previous heat treatment step. Finally, the results were compared with experimental ones. Simulation results were in good agreement with the experimental results. Consistency between experimental results and computational results prove that residual stress has significant effects on the stress behavior of mechanical parts. Therefore, the residual stress generated in the previous heat treatment step of casting must be taken into account in the stage of mechanical product design. Highlights The bigger compressive residual stress occurs, the closer surface. When the residual stress is close to plastic deformation, the stress by external load did not significantly change. The residual stress generated during the manufacturing process should be considered in the design stage.

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Reduction in transmission of hepatitis C after the introduction of a heat-treatment step in the production of C1-inhibitor concentrate

Transfusion ◽

10.1046/j.1537-2995.1995.35395184276.x ◽

1995 ◽

Vol 35 (3) ◽

pp. 209-212 ◽

Cited By ~ 34

Author(s):

M. Cicardi ◽

P. M. Mannucci ◽

R. Castelli ◽

M. G. Rumi ◽

A. Agostoni

Keyword(s):

Heat Treatment ◽

Hepatitis C ◽

C1 Inhibitor ◽

Treatment Step ◽

Heat Treatment Step

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Microstructure and Tensile Ductility of a Ti-43Al-4Nb-1Mo-0.1B Alloy

MRS Proceedings ◽

10.1557/proc-1128-u03-08 ◽

2008 ◽

Vol 1128 ◽

Author(s):

Laura M. Droessler ◽

Thomas Schmoelzer ◽

Wilfried Wallgram ◽

Limei Cha ◽

Gopal Das ◽

...

Keyword(s):

Heat Treatment ◽

Thermodynamic Equilibrium ◽

Room Temperature ◽

Volume Fraction ◽

Tensile Ductility ◽

Heat Treatments ◽

Air Cooling ◽

B2 Phase ◽

Treatment Step ◽

Heat Treatment Step

AbstractThe microstructural development of a forged Ti-43Al-4Nb-1Mo-0.1B (in at%) alloy during two-step heat-treatments was investigated and its impact on the tensile ductility at room temperature was analyzed. The investigated material, a so-called TNM™ gamma alloy, solidifies via the β-route, exhibits an adjustable β/B2-phase volume fraction and can be forged under near conventional conditions. Post-forging heat-treatments can be applied to achieve moderate to near zero volume fractions of β/B2-phase allowing for a controlled adjustment of the mechanical properties. The first step of the heat-treatment minimizes the β/B2-phase and adjusts the size of the α-grains, which are a precursor to the lamellar γ/α2-colonies. However, due to air cooling after the first annealing step, the resulting microstructure is far from thermodynamic equilibrium. Therefore, a second heat-treatment step is conducted below the eutectoid temperature which brings the microstructural constituents closer to thermodynamic equilibrium. It was found that temperature and duration of the second heat-treatment step critically affect the solid-state phase transformations and, thus, control the plastic fracture strain at room temperature. Scanning and transmission electron microscopy studies as well as hardness tests have been conducted to characterize the multi-phase microstructure and to study its correlation to the observed room temperature ductility.

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Validation of the Heat Treatment Step Used in the Production of Diaspirin Crosslinked Hemoglobin (Delhb™) For Viral Deactivation - Effect of Crosslinking

Artificial Cells Blood Substitutes and Biotechnology ◽

10.3109/10731199709117449 ◽

1997 ◽

Vol 25 (6) ◽

pp. 521-526 ◽

Cited By ~ 4

Author(s):

M. Azari ◽

J. Catarello ◽

K. Burhop ◽

T. Camacho ◽

A. Ebeling ◽

...

Keyword(s):

Heat Treatment ◽

Treatment Step ◽

Heat Treatment Step ◽

Diaspirin Crosslinked Hemoglobin

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High Pressure Heat Treatment of AM Parts—Combining HIP and Heat Treatment

10.31399/asm.cp.ht2019p0011 ◽

2019 ◽

Author(s):

Magnus Ahlfors

Keyword(s):

Heat Treatment ◽

Hot Isostatic Pressing ◽

Vacuum Furnace ◽

Creep Ductility ◽

Post Process ◽

Treatment Step ◽

Hip Process ◽

Heat Treatment Step ◽

Defect Elimination ◽

Metal Additive

Abstract Hot Isostatic Pressing (HIP) has been used for several decades within different industries for a wide variety of applications [1]. During the recent years HIP has become an important post process for metal additive manufacturing (AM) to secure material performance and quality. The HIP process uses a high isostatic pressure and elevated temperature to densify additively manufactured material by eliminating internal defects. The elimination of defects results in improved material properties such as fatigue, creep, ductility and fracture toughness [2-8]. HIP have historically been used only for densification and defect elimination and any modification and optimization of a material’s microstructure is usually performed after the HIP process in a separate heat treatment step in separate equipment e.g. a vacuum furnace. The main reason that these processes have been performed separately is that the achievable cooling rates in HIP systems have traditionally been relatively low, lower than what many materials require for heat treatment to for example create martensite or a super saturated condition.

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Study of ALDH from Thermus thermophilus–Expression, Purification and Characterisation of the Non-Substrate Specific, Thermophilic Enzyme Displaying Both Dehydrogenase and Esterase Activity

Cells ◽

10.3390/cells10123535 ◽

2021 ◽

Vol 10 (12) ◽

pp. 3535

Author(s):

Kim Shortall ◽

Edel Durack ◽

Edmond Magner ◽

Tewfik Soulimane

Keyword(s):

Heat Treatment ◽

Life Form ◽

Thermus Thermophilus ◽

Gel Filtration ◽

Aldehyde Dehydrogenases ◽

E Coli ◽

Ability To Act ◽

High Yields ◽

Treatment Step ◽

Heat Treatment Step

Aldehyde dehydrogenases (ALDH), found in all kingdoms of life, form a superfamily of enzymes that primarily catalyse the oxidation of aldehydes to form carboxylic acid products, while utilising the cofactor NAD(P)+. Some superfamily members can also act as esterases using p-nitrophenyl esters as substrates. The ALDHTt from Thermus thermophilus was recombinantly expressed in E. coli and purified to obtain high yields (approximately 15–20 mg/L) and purity utilising an efficient heat treatment step coupled with IMAC and gel filtration chromatography. The use of the heat treatment step proved critical, in its absence decreased yield of 40% was observed. Characterisation of the thermophilic ALDHTt led to optimum enzymatic working conditions of 50 °C, and a pH of 8. ALDHTt possesses dual enzymatic activity, with the ability to act as a dehydrogenase and an esterase. ALDHTt possesses broad substrate specificity, displaying activity for a range of aldehydes, most notably hexanal and the synthetic dialdehyde, terephthalaldehyde. Interestingly, para-substituted benzaldehydes could be processed efficiently, but ortho-substitution resulted in no catalytic activity. Similarly, ALDHTt displayed activity for two different esterase substrates, p-nitrophenyl acetate and p-nitrophenyl butyrate, but with activities of 22.9 and 8.9%, respectively, compared to the activity towards hexanal.

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